Fight Aging!

As a general rule, 10% life extension in mice via metabolic alteration is uninteresting. It depends on the fine details, of course, but most age-slowing interventions so far discovered are in some way upregulating cellular stress response mechanisms, or adjusting growth hormone signaling. Neither of these approaches works anywhere near as well in long-lived mammals, such as our own species, as it does in short-lived mammals, such as mice, and in lower animal species. Short-lived species have life spans that are very plastic in response to environmental cues, such as the lack of nutrients that provoke greater stress response activity. Calorie restriction can extend life in mice by as much as 40%, but certainly doesn't have that great an effect in humans. Growth hormone receptor knockout can extend mouse life span to an even greater degree, but humans with the analogous Laron syndrome don't appear to live significantly longer than the rest of us.

Today's open access paper reports on another novel dead end in considering the effects of metabolic change on longevity. Here, an mTOR inhibitor is given to mice in early life. The result is slowed development, reduced growth, and a modest 11.8% extension of median life span. mTOR inhibition is a well-proven way to modestly and reliably slow aging when used in later life in mice, but here the effects appear an amalgam of the usual mechanisms of stress response upregulation coupled with the reduced growth seen in mice in which growth hormone signaling is disabled. It is scientifically interesting to see that developmental effects can lead to this outcome, but the relevance to human medicine seems tenuous. At the end of the day, this is simply not an area of study that can plausibly lead to sizable gains in human healthy longevity.

Rapamycin treatment during development extends life span and health span of male mice and Daphnia magna

Some indirect evidence supports the causal relationship between inhibition of growth signaling and longevity if targeted during development. For example, growth hormone (GH) knockout mice and mice lacking GH production live up to 50% longer than their wild-type siblings. However, their longevity was diminished if they were treated with growth hormone during early postnatal development. At the same time, growth hormone knockout induced at adult age had limited to no effects on longevity. However, there have been no experiments where growth pathways are directly inhibited only during development and the longevity outcomes measured.

Rapamycin is a well-characterized mechanistic target of rapamycin (mTOR) inhibitor and is among the most validated and potent pharmaceutical interventions that extend life span in mice. Rapamycin can extend life span if given in adulthood or later in life in various mouse strains, including genetically diverse UMHET3 mice (a cross of four inbred strains). Rapamycin failed to extend the life span of growth hormone receptor knockout mice. Furthermore, early life (EL) rapamycin treatment was previously shown to suppress growth of mice. Thus, rapamycin is a perfect candidate to test how targeting growth only early in life can affect life span, and we used it in our study, examining its effects on longevity, health span, biological age, and gene expression.

Here, we subjected genetically diverse UMHET3 mice to rapamycin for the first 45 days of life. The mice grew slower and remained smaller than controls for their entire lives. Their reproductive age was delayed without affecting offspring numbers. The treatment was sufficient to extend the median life span by 10%, with the strongest effect in males, and helped to preserve health as measured by frailty index scores, gait speed, and glucose tolerance and insulin tolerance tests. Mechanistically, the liver transcriptome and epigenome of treated mice were younger at the completion of treatment. Analogous to mice, rapamycin exposure during development robustly extended the life span of Daphnia magna and reduced its body size. Overall, the results demonstrate that short-term rapamycin treatment during development is a novel longevity intervention that acts by slowing down development and aging, suggesting that aging may be targeted already early in life.

Researchers here review the evidence for metabolites produced by the gut microbiome to influence the behavior of innate immune cells in the brain. The gut microbiome changes in composition with age, altering the production of metabolites and inflammatory signaling in ways that degrade tissue function throughout the body. Fixing the many resulting issues at the source by introducing a youthful mix of microbes to the aging gut is a tempting path forward, likely relatively straightforward to achieve via fecal microbiota transplantation from young individuals to old individuals. This short-cut would hopefully evade the onerous requirement to fully understand how exactly harms to the brain result from the aging of the gut microbiome, and thus improve late life health in the near term rather than requiring many more years of research.

There is now increasing evidence that metabolites produced in the gut can enter the brain and impact brain macrophages. The macrophages residing in the brain comprise parenchymal microglia and non-parenchymal macrophages located in the perivascular spaces, meninges, and the choroid plexus. It is important to better understand the underlying mechanisms of age-related dysbiosis, which causes changes in gut-derived metabolites and ultimately influence the central nervous system, as well as immune and endocrine responses of the host.

Several studies have found that microbial metabolites can affect gut-brain responses, affecting the morphology and function of brain macrophages. These changes include their polarization and phagocytic capacity, which, in turn, controls behavior and emotional processes. Levels of microbiota-derived metabolites are elevated in older individuals with age-associated diseases and cognitive defects compared to younger, healthy age groups. The identified metabolites with higher concentration in aged hosts, which include choline and trimethylamine, are known risk factors for age-related diseases.

While the underlying mechanisms and pathways remain elusive for the most part, it has been shown, that these metabolites are able to trigger the innate immunity in the central nervous system by influencing development and activation status of brain-resident macrophages. In this review, we highlight the impact of age on the composition of the microbiome and microbiota-derived metabolites and their influence on age-associated diseases caused by dysfunctional brain-resident macrophages.

Link: https://doi.org/10.3389/fncel.2022.944526

The state of the gut microbiome is influential on health, perhaps as much as exercise. The balance of microbial populations shifts with age, reducing beneficial metabolite production, and increasing inflammation. Experiments in animals have shown that resetting those populations towards a more youthful configuration can improve health and extend life. Producing of a greater understanding of how exactly microbial populations produce changes in health is a work in progress, and today's research is an example of one approach, correlating microbial populations with blood metabolites. Many such metabolites have known associations with aspects of health and aging, which will hopefully guide future research to more effective approaches to intervention.

Human gut microbiota produce a variety of molecules, some of which enter the bloodstream and impact health. Conversely, dietary or pharmacological compounds may affect the microbiota before entering the circulation. Characterization of these interactions is an important step towards understanding the effects of the gut microbiota on health. In this cross-sectional study, we used deep metagenomic sequencing and ultra-high-performance liquid chromatography linked to mass spectrometry for a detailed characterization of the gut microbiota and plasma metabolome, respectively, of 85,83 participants invited at age 50 to 64 from the population-based Swedish CArdioPulmonary bioImage Study.

Here, we find that the gut microbiota explain up to 58% of the variance of individual plasma metabolites and we present 997 associations between alpha diversity and plasma metabolites and 546,819 associations between specific gut metagenomic species and plasma metabolites in an online atlas. We exemplify the potential of this resource by presenting novel associations between dietary factors and oral medication with the gut microbiome, and microbial species strongly associated with the uremic toxin p-cresol sulfate. This resource can be used as the basis for targeted studies of perturbation of specific metabolites and for identification of candidate plasma biomarkers of gut microbiota composition.

Link: https://doi.org/10.1038/s41467-022-33050-0

There is some debate over whether persistent viral infection, such as by herpesvirus, contributes meaningfully to the onset and development of Alzheimer's disease. It would be a convenient explanation, given that many people with all of the lifestyle risk factors for neurodegeneration, such as being overweight and sedentary, do not in fact go on to develop Alzheimer's. The epidemiology is mixed, however, with some studies suggesting yes, some no. Some of the positive data suggests that use of antiviral drugs lowers the risk of Alzheimer's. More recent work argues that multiple different viral infections are required for a significant effect on Alzheimer's risk, which might explain why earlier epidemiology has produced conflicting results.

Meanwhile, researchers continue to explore the cellular biochemistry that might cause viral infection to increase production of amyloid-β, an anti-microbial peptide. Ever greater aggregation of misfolded amyloid-β is the early stage of Alzheimer's disease, and the more amyloid-β being generated, the faster that pathological process will progress, or at least that is the hypothesis. Today's open access paper is an example of cell culture studies being conducted to better understand the interaction between viral particles and the biochemistry of the brain. It adds a little more context to the picture, but doesn't address the conflicting epidemiological evidence.

Herpes Simplex Virus Infection Increases Beta-Amyloid Production and Induces the Development of Alzheimer's Disease

Alzheimer's disease, a neurodegenerative memory disease, primarily results from the formation of amyloid plaques (Aβ) that gradually inhibit neuron communications. The entire mechanism of Aβ production remains unclear to date, and it is of particular interest among scientists to find out the exact mechanism that leads to amyloid precursor protein (APP) cleavage through the amyloidogenic pathway so that effective treatments can be developed.

Our hypothesis states that HSV-1 infection induces APP endocytosis, increases APP cleavage by β-secretase, and raises Aβ levels inside a cell. The Aβ peptides will then exit the cell via exocytosis to form beta-amyloid plaques. Two sets of experiments with the use of human neuroglioma cell lines are proposed to fully investigate the validity of the hypothesis. All of the experiments involve immunoblotting of Aβ using an anti-Aβ antibody, and the results would be analyzed with the assistance of an image analyzer. A significant amount of Aβ would be expected to be present in the cytoplasm of cells with herpes simplex virus (HSV-1) applied, as APP endocytosis would be induced by HSV-1, which leads to higher Aβ levels inside the cell.

Overall, we expect a high level of Aβ peptide concentration intracellularly after the introduction of HSV-1 to neuroglioma cell line. However, after the introduction of chloroquine to inhibit endocytosis, the intracellular Aβ concentration would be expected to remain normal even under HSV-1 infection. We also expect a high intracellular but low extracellular Aβ concentration for cell lines introduced with tetanus neurotoxin (TeNT) to inhibit exocytosis as the Aβ peptides are forced to accumulate in the cytoplasm. Lastly, we would expect to observe a high extracellular but low intracellular Aβ concentration for cell lines without TeNT introduction as the Aβ peptides are able to exit cells via exocytosis and aggregate extracellularly.

If all experimental data match the expected results, it can be concluded that herpesvirus infection induces Aβ peptide production in the brain due to an increase in APP endocytosis and that the peptides exit cells via exocytosis to induce the development of Alzheimer's disease.

Age-related frailty is a late stage manifestation of degenerative aging, a state of physical weakness and vulnerability that precedes death. Aging is the accumulation of damage and dysfunction, and the burden of such damage and dysfunction needed to produce frailty is one step removed from the amount needed to cause one of the many forms of fatal system failure that cause human mortality. Whether death is eventually due to cardiovascular disease, dementia, or kidney failure, frailty is a proximate indicator.

In this long-term population-based prospective cohort comprising 9,912 participants, we evaluated the risk of mortality according to longitudinal repeated measurements of Frailty Index (FI). Both levels of FI and the proportions of frail participants gradually increased with age and there was significant variability in the progression of frailty. We observed clear dose-response relationships between FI values and all-cause, cancer, and cardiovascular disease (CVD) mortality, with associations being substantially stronger and consistent across various lengths of follow-up when FI was considered as a time-varying predictor variable rather than being based on a single measurement at baseline.

The increase in prevalence of frailty with age is well established in both cross-sectional and longitudinal studies in aging research. For example, in a cross-sectional study among 993 adults aged 70+ conducted in Spain, prevalence of frailty (measured by Fried frailty) was reported to be 7.1%, 14.5%, 29.7%, 31.8%, and 43.2%, in participants aged 70-74, 75-79, 80-84, 85-89 and over 90 years, respectively. In a cohort study conducted in 350 older adults (≥65 years) residing in long-term care facilities in Korea, the prevalence of frailty (measured by Fried frailty) increased from 25.8% to 35.2% during three years of follow-up.The increase in frailty prevalence with age is in line with the expected consequence of the cumulative decline in multiple physiological systems occurring at older age.

Nevertheless, in agreement with results from other recent studies, our study demonstrates that there is substantial inter-individual variability in development and progression of frailty with increasing age, including the possibility of regression of frailty. A variety of factors contributes to the development of frailty and frailty transitions, including nutritional status, environmental factors, diseases, and psychological factors. Therefore, these changeable characteristics make frailty a comprehensive and reversible health condition.

Link: https://doi.org/10.1016/j.eclinm.2022.101630

In many species, aging of the female reproductive system occurs more rapidly than is the case for other parts of the body. This is one of a few biological systems subject to what appears to be premature aging, relative to other organs. Other examples include the thymus, which atrophies well before late life. Researcher here suggest that mitochondrial quality control, the process of mitophagy, is involved in the aging of oocytes to a great enough degree that upregulation of mitophagy may delay female reproductive aging.

Women's reproductive cessation is the earliest sign of human aging and is caused by decreasing oocyte quality. Similarly, C. elegans' reproduction declines in mid-adulthood and is caused by oocyte quality decline. Aberrant mitochondrial morphology is a hallmark of age-related dysfunction, but the role of mitochondrial morphology and dynamics in reproductive aging is unclear. We examined the requirements for mitochondrial fusion and fission in oocytes of both wild-type worms and the long-lived, long-reproducing insulin-like receptor mutant daf-2. We find that normal reproduction requires both fusion and fission, but that daf-2 mutants utilize a shift towards fission, but not fusion, to extend their reproductive span and oocyte health.

daf-2 mutant oocytes' mitochondria are punctate (fissioned) and this morphology is primed for mitophagy, as loss of the mitophagy regulator PINK-1 shortens daf-2's reproductive span. daf-2 mutants maintain oocyte mitochondria quality with age at least in part through a shift toward punctate mitochondrial morphology and subsequent mitophagy. Supporting this model, Urolithin A, a metabolite that promotes mitophagy, extends reproductive span in wild-type mothers - even in mid-reproduction - by maintaining youthful oocytes with age. Our data suggest that promotion of mitophagy may be an effective strategy to maintain oocyte health with age.

Link: https://doi.org/10.1371/journal.pgen.1010400

Today's open access paper underscores the point that prevention and treatment of atherosclerosis should be a high priority in medical research, development, and practice. It is the single largest cause of death in our species, killing a quarter of humanity directly, and arguably another tenth indirectly. Atherosclerosis is the malfunction of macrophage cells responsible for clearing excess and altered cholesterol from blood vessel walls. The result is the accumulation of fatty lesions, and a tipping point in which the contents of the lesion overwhelm the macrophage cells attempting to remove it, thereafter continually adding dead cells to the growing atheroma. Blood vessels are narrowed, weakened, and inflamed. The inevitable rupture produces a stroke or heart attack. Along the way, reduced blood flow contributes to numerous other age-related conditions.

The authors here focus on prevention of atherosclerosis via lowered blood cholesterol. It is true that over a normal human life span, people with very low levels of blood cholesterol exhibit little atherosclerosis. Very low levels require treatments or mutation to achieve, but merely low levels can be attained through lifestyle choice. In such cases, the tipping point at which macrophages are overwhelmed is pushed out late enough that other forms of age-driven mortality are dominant in later life. If those other causes of death were dealt with, however, then sooner or later atherosclerosis would become a problem. Still, the epidemiology shows that the majority of the present pervasive mortality caused by atherosclerosis could in principle be avoided by suitable lifestyle choices. This is a frustrating state of affairs for clinicians, and that shows in the tone of the paper.

There is urgent need to treat atherosclerotic cardiovascular disease risk earlier, more intensively, and with greater precision: A review of current practice and recommendations for improved effectiveness

Atherosclerosis is the leading cause of disease, disability, and death in the United States and globally. Current medical practice has made progress, but agonizingly slowly considering the millions of people still adversely afflicted by atherosclerotic complications despite use of current treatments. This review examines how new approaches can significantly reduce the human cost of atherosclerosis. In light of the continued high rate of atherosclerotic disease, what seems needed is what Martin Luther King, Jr. called "the fierce urgency of now". An entire paradigm shift is required such that preventive efforts are embraced much earlier in life, as discussed later in the paper. We propose that preventing and controlling atherosclerosis, the greatest killer of both men and women, be the top priority of medical care in the United States.

While there has been a significant reduction in heart attack and stroke, large numbers of Americans still sustain myocardial and cerebral infarctions and other complications of atherosclerotic cardiovascular disease (ASCVD) Despite the wealth of evidence and the availability of effective preventive interventions, declines in ASCVD hit a nadir, and in fact, cardiovascular mortality has been on the rise over the last decade in both men and women in the US, and throughout the world. Even though modern technology has helped more victims of acute cardiovascular events survive, significant numbers of patients who survive due to stents and other interventions in the immediate acute phase nevertheless often experience long-term disability, reinfarction, and death secondary to inadequate treatment. Further, atherosclerosis causes or contributes to many other diseases besides coronary artery disease. Success cannot be claimed until they are equally addressed and reduced.

Current practices are certainly not eliminating atherosclerotic disease. Atherosclerotic disease is preventable since its drivers of risk are largely modifiable (e.g., hyperlipidemia, hypertension, diabetes, cigarette smoking, sedentary lifestyle, obesity). A more intensive, more precise approach applied earlier than is current practice has a higher likelihood of significantly reducing the total burden of atherosclerotic disease. Atherosclerosis represents a clinical paradox: it is potentially the most preventable or treatable chronic disease, yet it remains the greatest cause of disability and death throughout the world. This does not have to be the case.

There has been compelling and convincing justification for some time that an approach that includes keeping plasma atherogenic lipoproteins low from early in life will greatly reduce risk for ASCVD. The fact that animals, non-human primates, and humans who maintain low cholesterol levels from early in life have very little atherosclerosis all suggest that a 'normal' non-atherogenic LDL-C level is 20-40 mg/dl. That is of course difficult to achieve in a modern society, but may not in fact be necessary. The Tsimane tribe of Bolivia, for example, live unexposed to 'developed' life and are essentially free of atherosclerotic disease. The mean LDL-C and HDL-C in the Tsimane people are at 90 mg/dL and 39.5 mg/dL, respectively.

Senescent cells accumulate in tissues throughout the body with age, the lung included, as noted here. This accumulation is thought to be largely the result of the progressive failure of the immune system to destroy newly created senescent cells in a timely fashion. These cells secrete a mix of signals that disrupts tissue structure and function, provoking chronic inflammation. Senolytic therapies capable of selectively destroying senescent cells have shown considerable promise in animal studies, reversing many aspects of aging and age-related disease. Senescent cells actively maintain a degraded state of tissue, and getting rid of them allows some degree of regeneration and restoration of lost function - a true rejuvenation therapy.

Aging results in systemic changes that leave older adults at much higher risk for adverse outcomes following respiratory infections. Much work has been done over the years to characterize and describe the varied changes that occur with aging from the molecular/cellular up to the organismal level. In recent years, the systemic accumulation of senescent cells has emerged as a key mediator of many age-related declines and diseases of aging. Many of these age-related changes can impair the normal function of the respiratory system and its capability to respond appropriately to potential pathogens that are encountered daily.

In this review, we aim to establish the effects of cellular senescence on the disruption of normal lung function with aging and describe how these effects compound to leave an aged respiratory system at great risk when exposed to a pathogen. We will also discuss the role cellular senescence may play in the inability of most vaccines to confer protection against respiratory infections when administered to older adults. We posit that cellular senescence may be the point of convergence of many age-related immunological declines. Enhanced investigation into this area could provide much needed insight to understand the aging immune system and how to effectively ameliorate responses to pathogens that continue to disproportionately harm this vulnerable population.

Link: https://doi.org/10.3389/fimmu.2022.1006710

Researchers here note that cytotoxic T cells undergo age-related changes in protein expression that make them more effective in the task of destroying cancer cells, an unusual example of a component of the immune system improving with age. Overall, an aged immune system is impaired in numerous ways, and is worse at protecting the individual against the onset of cancer. Identifying specific populations of immune cells that can effectively destroy cancer cells, if given direction and greater numbers, is relevant to the production of better immunotherapies, however.

The older someone is, the more likely they are to get cancer. This was thought to suggest that the human immune system becomes weaker with age and that the same must therefore be true of the killer T cells that play such a critical role in fighting off pathogens. The job of the T cell is to track down and kill virus-infected cells or tumour cells in the body. Up until now the accepted scientific view has been that T cells function less effectively as they age. However, researchers have now found the rather surprising result that the ability of cytotoxic CD8+ T cells to destroy tumour cells does not deteriorate but actually improves with age.

The reason why T cells are such effective killers has to do with the highly effective weapons that they have at their disposal. The production of the molecules perforin and granzyme is enhanced in older T cells. As its name suggests, the molecule perforin perforates the target cells making tiny pores in the cell membrane. Granzyme can then enter the cells and initiate apoptosis, a form of programmed cell death. In addition, older experienced T cells have an accurate picture of who they are supposed to be targeting. Cytotoxic CD8+ T cells have a good memory of who they have attacked and destroyed in the past. And as part of the adaptive immune system, they live and learn. T cells are able to form memory cells. If they come into contact with a pathogen that they are already acquainted with, they respond very quickly and very effectively.

This begs the question as to why older people are not better protected against tumour cells and viruses if their T cells are so powerful. "On the one hand we have age-related processes that occur naturally as the cell ages, but we also have to consider changes in cell function due to the ageing of the cell's environment. In the case of T cells, the evidence seems to suggest that the reason for the deteriorating immune response is not to be found in the T cells themselves but rather in the ageing environment."

Link: https://www.eurekalert.org/news-releases/965427

Amyloid-β is an anti-microbial peptide, a part of the innate immune system's attempt to disrupt the activities of infectious pathogens. Some data suggests that Alzheimer's disease, characterized in its early and preclinical stages by slow aggregation of misfolded amyloid-β in ever larger amounts, is driven by persistent infection. It is by no means certain that this is the case, but it does place the aggregation of amyloid-β in a somewhat different light than was originally the case, when it was thought of as molecular waste and little more.

Given that amyloid-β is performing a useful function, reducing or eliminating its production is probably a bad idea - and indeed this idea was attempted and made patient outcomes worse. The right way forward in the matter of amyloid-β is most likely periodic clearance of the harmful aggregates or harmful excess elsewhere in cells, a goal presently complicated by the failure of clearance via immunotherapies to produce patient benefits in the clinic. This may be because the wrong forms or locations of amyloid-β were targeted, or because amyloid-β ceases to be the primary pathology in later stages of the condition, when chronic inflammation and tau aggregation drive one another in a feedback loop that kills neurons and leads to death.

Does An Immune Role for Beta-Amyloid Create a Therapeutic Dilemma for SENS?

Neurons produce Abeta as an anti-microbial peptide (AMP), a way to protect themselves from microbial assailants. When they come in contact with a pathogen, molecules of Abeta bind to the intruder, which triggers them to stick together into aggregates. Trapping the brain bugs in a sticky web allows Abeta to deactivate the microbial raiders, protecting the brain from infectious assault. With this model, a number of things that scientists have been reporting for years suddenly start to make sense. For one thing, it's long been known that the complement system is activated in the early stages of Alzheimer's disease. The complement system is a part of the innate immune system that directly destroys pathogens by tearing open their membranes, and it was already known to be activated by other AMPs. The model also explains why proteins that are part of the complement system are often found bound up with Abeta plaques in the brain.

If Abeta is an AMP, it also reframes the role of inflammation in the aging and Alzheimer's brain, and the associated activation of brain-resident immune cells called microglia. Microglia are like the macrophages of the brain, gobbling up particulate matter, cellular debris, and other harmful materials in the brain - including, importantly, Abeta - and digesting it in their lysosomes. Microglia have receptors on their surfaces that cause them to spring into action when they get a whiff of activated complement proteins, and Abeta causes dormant complement protein precursors to be converted into their active forms. In the Abeta-as-AMP model, this becomes an elegant host defense system: Abeta is released, traps a marauding microbe in a self-aggregating web of proteins, and then activates complement to help finish off the enemy and to recruit microglia to clean up the battlefield.

This sequence protects the brain from these toxic materials in the short term - first from the infectious intruder, and then from Abeta itself. Abeta is produced in the short term as an emergency response to microbial marauders; microglia are then activated and recruited to clear the dead pathogens and aggregated proteins out of the brain so that they don't cause harm of a different sort. So long as this cycle is executed flawlessly, the brain remains protected from threats and sustains function. But none of these processes are perfect, they leave behind a few microbes here ... a few protein aggregates there ... and a few dysregulated microglia in another corner. Meanwhile, other aging processes make it increasingly difficult to close the loop on the cycle of releasing and aggregating Abeta, destroying pathogens, and recruiting microglia to clean up the battlefield afterward.

Abeta defends the brain against microbial invaders by forming aggregates that capture and neutralize them. Once they've already carried out the attack, the whole snarled-up mess - Abeta polymers, dead microbes, and complement proteins - serves no further purpose and can be toxic to the brain. So Abeta that is cleared out after becoming aggregated has already finished serving a useful purpose, and is mere battlefield rubble that must be safely swept away to help rebuild the neighborhood.

The present approaches to treating vascular stiffening with age are near entirely compensatory, small molecule drugs that attempt to override signaling and force certain outcomes in the behavior of tissues. This interesting commentary notes that because stiffening has two primary components, compensatory approaches of this nature can produce adverse effects in some circumstances. Stiffening is caused by (a) loss of elasticity in the extracellular matrix of blood vessel walls, and (b) failure of the smooth muscle that controls contraction and dilation to properly respond to environmental cues. Stiffening leads to the raised blood pressure of hypertension, and hypertension causes so much damage to delicate tissues over time that, on its own, it meaningfully raises the risk of age-related disease and mortality in later life.

The mechanical and structural properties of blood vessels differ along the vascular tree. There are two categories of large arteries: elastic and muscular arteries. Elastic arteries are close to the heart, contain more elastin per unit of area and play an important role in buffering the ejected blood volume. More distal muscular arteries have a higher smooth muscle cell content. They regulate wall tension and shear stress by adjusting the vascular tone and transport blood to the smaller resistance vessels that control blood flow.

With increasing age, the structural and cellular components of the arterial wall change. Mechanistically, the arterial wall is largely dependent on the balance between elastin and collagen and their interplay with vascular smooth muscle cell (VSMC) contraction. This balance is disrupted during aging, leading to a higher collagen content, a lower elastin content, more elastin fragmentation, and more cross-linking of both collagen and elastin. On a cellular level, vascular aging is related to endothelial dysfunction and impaired nitric oxide bioavailability, leading to reduced endothelium-dependent vasodilation and therefore more pronounced vasoconstriction. These microstructural and functional changes are typically thought to result in an overall stiffening of the arterial wall.

Researchers have investigated how nitroglycerin (NTG)-mediated vasodilation acutely affects vascular stiffness and whether this differs between elastic and muscular arteries. NTG is an organic nitrate and acts as a nitric oxide (NO) donor. Results show that the arterial stiffness of the carotid artery and the regional carotid-femoral pulse wave velocity (cfPWV) is, as expected, higher in hypertensive individuals than in controls, but this was not observed in the brachial artery. While the stiffness of the elastic carotid artery, as well as cfPWV, increased, the stiffness of the muscular brachial artery did not change significantly. These findings were independent of hypertensive status.

Further analyses revealed that in the carotid artery, the active VSMC stiffness index parameter was lower than the passive ECM stiffness index, whereas these two indices were almost equal in the brachial artery. This leads to the hypothesis that the different stiffness responses to vasodilation are a result of the ratio of active to passive stiffness contributions. When this difference is positive (active stiffness is greater than passive stiffness), decreasing arterial tone will decrease the overall wall stiffness as the active contribution decreases. In contrast, when this difference is negative, vasodilation will lead to an increase in stiffness.

In conclusion, this study highlights the importance of investigating whether vasodilatory drugs, used as antihypertensive medication, have an adverse effect on large arteries by increasing their stiffness, which has inherent potential cardiovascular risks.

Link: https://doi.org/10.1038/s41440-022-01012-0

Senescent cells contribute significantly to the chronic inflammation of aging, via their secretions, the senescence-associated secretory phenotype. A comparatively small number of such cells produces an outsized effect both on nearby cell behavior, and behavior throughout the body, and this accelerates the progression of age-related degeneration. Yet this increase in inflammatory signaling due to the presence of senescent cells takes place without producing well-correlated effects on the established inflammatory marker assays measured in blood samples. This is one of the aspects of senescent cell biology that complicates the production of useful, low-impact tests to measure senescent cell burden in an individual.

Is there any established correlation between Senescence-Associated Secretory Phenotype (SASP) or senescent cell burden on one side and the measured C-reactive protein level or any other routinely measured inflammatory marker in an individual on the other side? Unfortunately not. Scientists first started asking this question around the time of the first proof-of-concept of the value of destroying senescent cells, and initially hoped it would be a straightforward matter of simply measuring the levels of various SASP factors directly in the blood. While none of the components of the SASP are common blood tests like C-reactive protein, some commercial blood-testing labs do test for specific proteins that are part of the SASP, including interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α).

Somewhat surprisingly, however, things did not turn out to be quite that simple, for reasons that aren't entirely clear. Perhaps the SASP factors concentrate too locally around senescent cells to be easily picked up in the blood. Or perhaps it relates to the fact that none of the individual proteins and lipid derivatives released from senescent cells as part of the SASP are actually unique to senescent cells. Instead, all of the proteins that make up the witches' brew of proteins that is the SASP are are repurposed growth factors, protein-degrading enzymes, and above all inflammatory signaling molecules that also produced by non-senescent cells in the body to do things like break down damaged muscle, recruit immune cells, remodel injured tissue, and so on. This might mean that the signal from true SASP factors is swamped out by the fact that those same factors are produced at relatively high levels in an aged person's body for other reasons, in response to their high burden of aging damage.

And precisely because each individual SASP factor is produced by non-senescent cells for other purposes entirely, no one marker can be used as a reliable index of SASP production: the level of any given factor always reflects a mixture of SASP-related production and production for entirely different reasons. As such, measuring just one or even a few SASP factors in the blood and correlating that to the actual number of senescent cells in your body or the level of SASP they're producing is likely a fool's errand from the start.

Link: https://www.sens.org/correlation-between-senescent-cells-and-inflammatory-markers/

My attention was drawn recently to a small mouse life span study run by one of the groups that has been in the longevity community for a while now. It is interesting for testing combinations of interventions that have in the past been demonstrated to modestly slow aging in mice (such as rapamycin), or modestly improve aspects of cell function in old tissues (such as nicotinamide mononucleotide). Combinatorial studies are rare in academia and industry, for reasons that have a lot to do with (a) the perverse incentives produced by the existence of intellectual property, in that the rights to use specific interventions can be owned, granted, refused and (b) the way in which the huge cost of regulatory approval determines which projects that can be successfully funded, typically only those in which patents grant a monopoly on use.

The results are much as one might expect, given the interventions chosen, in that most of the combinations did little to nothing to mouse survival and life span. The only one that appears to have an effect is the use of C60 - an intervention that, you might recall, has a checkered history in animal studies. The most recent data, from Ichor Therapeutics and others, who spent some years working with C60, is that it is not a useful intervention in the matter of modestly slowing aging.

Unfortunately, this study did not control for inadvertent calorie restriction. When an intervention makes mice feel ill, they will eat less. Mouse weight is a sensitive barometer of mouse well-being. Even minor degrees of calorie restriction can extend mouse life span, distorting the effects of interventions. This is one of the reasons why rigorous studies, such as those conducted by the Interventions Testing Program, tend to find no effect when repeating earlier studies in which an intervention was claimed to modestly slow aging. Sadly, this means that positive outcomes here don't have all that much weight, and it is possible that some of the neutral outcomes are actually poor outcomes.

Bucky Labs Longevity Study

Our mouse longevity study completed with interesting results. Frankly, we did not know what to expect. We tested our products and other promising substances on 245 interbred male C57BL/6 mice. We started the interventions when mice were 300 days old (about 50 in human yrs). Caveats: the sample sizes were very small, optimal dosages were guesses, and we did not weigh the mice - so some effects may be from dietary restriction, etc.

1 C60 99.95 Olive Oil 10%
2 C60 in MCT oil 10%
4 cycloastragenol, NMN, fisetin, icariin, berberine, cistanche, AFA algae
5 exosomes, klotho, FOXO4-DRI, gdf11, epitalon
6 rapamycin, Azithromycin, metformin, NMN, spermidine, echinacea
7 NMN, fisetin, C60
8 RG7834, DHEA, berberine, fisetin, NMN
9 berberine, BHB, NMN, ALA, cycloastragenol, spermidine, DHEA, rhodiola, fisetin, icariin, echinacea, cistanche
10 rapamycin, metformin, aspirin, niacin, RG7834, spermidine, FOXO4-DRI, gdf11
11 centrophenoxine, exosomes, fisetin, metformin
12 double dose fisetin, double NMN, double cycloastragenol
13 klotho, RG7834, spermidine
15 MOTS-C
16 gdf11
17 spermidine
18 double NMN, double berberine, double centrophenoxine, double cycloastragenol, double fisetin
20 NMN, ALA, pterostilbene, cycloastragenol, centrophenoxine, spermidine, DHEA, melatonin, rhodiola, luteolin, fisetin, icariin, echinacea, cistanche, carnitine
21 double fisetin, double NMN, double berberine, NAC, DHEA, echinacea, cistanche

The best intervention was Intervention 1 (red line), C60 Olive Oil (the mouse feed was supplemented with about 10% C60 in organic olive oil). This group also had the largest number of mice (16), so the confidence that something real is happening is greatest with this intervention. The next best group was Intervention 9 (NMN, spermidine, berberine, BHB, ALA, cycloastragenol, dhea, rhodiola, fisetin, icariin, echinacea, cistanche). The following next best interventions are clustered closely around the control, so no conclusions should be made. Surprising that the poorest performer was Intervention #20 (NMN, ALA, pterostilbene, cycloastragenol, centrophenoxine, spermidine, DHEA, melatonin, rhodiola, luteolin, fisetin, icariin, echinacea, cistanche, carnitine) which is similar to the 2nd best performer. Also, Intervention #8 (RG7834, DHEA, berberine, fisetin, NMN) did not do well.

The results with our peptides/proteins did not appear to result in any significant longevity increases. Also, surprising was that the interventions with rapamycin did not appear to produce significant improvements. Lastly, ours is the first lifespan study to investigate C60 with an alternative lipid, we tried MCT oil (basically coconut), and there was no lifespan improvement.

This popular science article is a good view of the present state of development and use of epigenetic clocks, covering the issues as well as the promise. Epigenetic age can be measured, with many different clocks using many different combinations of DNA methylation sites on the genome, and greater epigenetic age correlates with greater mortality and risk of age-related disease. What processes of aging actually drive epigenetic age, however? How will epigenetic age change following interventions that target only one or only several of the myriad causes and consequences of aging? Will those changes accurately reflect outcomes on mortality and disease risk? No-one knows, which is why it is currently difficult to use epigenetic clocks to assess the ability of any given approach to produce rejuvenation or a slowing of aging.

Despite their obvious promise and growing popularity, epigenetic clocks still have some notable shortcomings. First, it's difficult to tell exactly how accurate biological age measurements are. Epigenetic clocks are much better at predicting lifespan than previous techniques, like oxidative damage or telomere length. But the challenge with longevity research is that studies to determine whether biological age predictions translate to actual lifespans take decades. In other words, if you're 25 with a biological age of 30, will you die five years sooner than average? Secondly, scientists haven't pinpointed which changes are directly caused by aging. It's possible that some changes occur by happenstance in older people, independent of aging. In other words, some changes we associate with aging may not actually impact the length or quality of our lives.

Finally, some scientists suspect that epigenetic clocks are more of a measure of biological age than a driver of it. "Think of the clock as a wristwatch. If you broke your wristwatch, the time would still go on. My guess would be that if we stopped these methylation sites from changing, we wouldn't interfere much with the aging process." But these researchers still see epigenetic clocks as an excellent marker for biological age, a measure of how quickly the aging process is proceeding in humans or other animals, independent of calendar years. For example, a smoker at age 50 might have an epigenetic age of 65, while a person at the same who exercises frequently might have an epigenetic age of 45. Others are a bit more optimistic. "I would say there are DNA methylation sites that actually matter a lot. If you change the right locations, you may actually rejuvenate cells. I won't claim that, I'm just saying nobody knows."

Epigenetic clocks remain a powerful tool in the science of rejuvenation. In the short term, researchers believe their best use is as a measuring tool, a kind of epigenetic yardstick that determines whether other interventions are successful. Although there are outstanding questions about how we define aging, how we measure rejuvenation, and how this could unfold economically, epigenetic clocks are "a true revolution." When it comes to aging research in humans, epigenetic clocks could be a tool that helps quantify a treatment's effectiveness while subjects are still alive. In other words, if epigenetic clocks become sophisticated enough that the FDA accepts them as surrogate endpoints, it would allow researchers to quickly demonstrate a drug's efficacy in mere months by measuring methylation - as opposed to waiting years to see how the drug affects survival. Longevity research could speed ahead, no longer reliant on death as a primary endpoint.

Link: https://neo.life/2022/09/2-minutes-to-midlife-the-fantastic-unspecified-future-of-epigenetic-clocks/

A great deal of time and effort goes into identifying proteins that are expressed to different degrees in young versus old tissues. It is comparatively easy to find such proteins, the question is always what to do with that information. That levels of a given protein change with age is no guarantee that it is meaningfully involved in aging, or that its role is well known, or even that a good catalog of the other protein machinery that it interacts with will help in the production of interventions to treat aging. Exploration of aging at the level of protein expression is, in large part, quite disconnected from understanding of the causes of aging, or of the consequences of aging. This is the challenge of dealing with an enormously complex biological system: a great deal of work is yet needed to be able to robustly connect what is known of causes, proteomics, and outcomes in aging.

Aging is characterized by the gradual loss of physiological integrity, resulting in impaired function and greater mortality. It is very important to find biomarkers that can prevent aging. In this study, key senescence-related molecules (SRMs) were identified in young and senescent fibroblasts by integrating transcriptome and proteomics from aging tissue/cells, and the correlation between these differentially expressed genes and well-known aging-related pathways. We first combined proteomics and transcriptomics to identify four SRMs. Existing data sets and qPCR confirmed that ETF1, PLBD2, ASAH1, and MOXD1 were identified as SRMs. Then the correlation between SRMs and aging-related pathways was excavated and verified. Next, we verified the expression of SRMs at the tissue level and qPCR, and explored the correlation between them and immune infiltrating cells. Finally, at the single-cell transcriptome level, we verified their expression and explored the possible pathway by which they lead to aging.

Briefly, ETF1 may affect the changes of inflammatory factors such as IL-17, IL-6, and NFKB1 by indirectly regulating the enrichment and differentiation of immune cells. MOXD1 may regulate senescence by affecting the WNT pathway and changing the cell cycle. ASAH1 may affect development and regulate the phenotype of aging by affecting cell cycle-related genes. In conclusion, based on the analysis of proteomics and transcriptome, we identified four SRMs that may affect aging and speculated their possible mechanisms, which provides a new target for preventing aging, especially skin aging.

Link: https://doi.org/10.3389/fgene.2022.881051

Is the slow amyloid-β aggregation, occurring for years prior to the onset of evident symptoms, really the cause of Alzheimer's disease? The amyloid cascade hypothesis suggests that this accumulation of misfolded amyloid-β, and the toxic biochemistry surrounding its aggregates, set the stage for the much more severe later stage of Alzheimer's disease, in which neuroinflammation and tau aggregation kill neurons - and ultimately the patient. The hypothesis makes sense given what is known of the relevant biochemistry, but has been strongly challenged by (a) the great difficulty in clearing amyloid-β from the brain, a project that took decades to produce successful therapies, and (b) that successful clearance has failed to produce meaningful patient benefits.

The biochemistry of the brain is exceptionally complex, and the failure of amyloid-β clearance to help patients may not in fact imply that the amyloid cascade hypothesis is very wrong. "Very wrong" in this context could mean that, for example, the aggregation of amyloid-β is a side-effect, a consequence of other processes that actually drive the onset of Alzheimer's, and thus targeting it will never prove to be useful. Or it could mean that while amyloid-β is a meaningful component of the condition, it is not sufficient to clear it without also repairing the vasculature, or removing senescent cells, or damping down neuroinflammation. However, it may also be the case that amyloid-β is in fact a useful target, and the failure to help patients occurred because the wrong forms or localizations of amyloid-β were targeted, or that patients were treated too late in the progression of Alzheimer's disease, after a point at which amyloid-β became irrelevant.

Biochemistry is complicated! Researchers have devoted a great deal of thought in recent years to amending the amyloid cascade hypothesis in ways that could explain the failure of successful clearance to help patients. Today's open access paper is one example of a modified amyloid cascade hypothesis, an attempt to reconcile what is known into a unified understanding. It may well be just as wrong as other views of Alzheimer's disease.

The Amyloid Cascade Hypothesis 2.0: On the Possibility of Once-in-a-Lifetime-Only Treatment for Prevention of Alzheimer's Disease and for Its Potential Cure at Symptomatic Stages

We posit that Alzheimer's disease (AD) is driven by amyloid-β (Aβ) generated in the amyloid-β protein precursor (AβPP) independent pathway, which is activated by AβPP-derived Aβ accumulated intraneuronally, in a life-long process. This interpretation constitutes the Amyloid Cascade Hypothesis 2.0 (ACH2.0). It defines a tandem intraneuronal-Aβ (iAβ)-anchored cascade occurrence: intraneuronally-accumulated, AβPP-derived iAβ triggers relatively benign cascade that activates the AβPP-independent iAβ-generating pathway, which, in turn, initiates the second, devastating cascade that includes tau pathology and leads to neuronal loss.

The entire output of the AβPP-independent iAβ-generating pathway is retained intraneuronally and perpetuates the pathway's operation. This process constitutes a self-propagating, autonomous engine that drives AD and ultimately kills its host cells. Once activated, the AD Engine is self-reliant and independent from Aβ production in the AβPP proteolytic pathway; operation of the former renders the latter irrelevant to the progression of AD by relegating its iAβ contribution to insignificance, and making its manipulation for therapeutic purposes, such as via BACE (beta-site AβPP-cleaving enzyme) inhibition, as futile.

In the proposed AD paradigm, the only valid direct therapeutic strategy is targeting the engine's components, and the most effective feasible approach appears to be the activation of BACE1 and/or of its homolog BACE2, with the aim of exploiting their Aβ-cleaving activities. Such treatment would collapse the iAβ population and 'reset' its levels below those required for the operation of the AD Engine. Any sufficiently selective iAβ-depleting treatment would be equally effective. Remarkably, this approach opens the possibility of a short-duration, once-in-a-lifetime-only or very infrequent, preventive or curative therapy for AD; this therapy would be also effective for prevention and treatment of the 'common' pervasive aging-associated cognitive decline.

The ACH2.0 clarifies all ACH-unresolved inconsistencies, explains the widespread 'resilience to AD' phenomenon, predicts occurrences of a category of AD-afflicted individuals without excessive Aβ plaque load and of a novel type of familial insusceptibility to AD; it also predicts the lifespan-dependent inevitability of AD in humans if untreated preventively. The article details strategy and methodology to generate an adequate AD model and validate the hypothesis; the proposed AD model may also serve as a research and drug development platform.

Regeneration without scarring is a desirable goal. Given that this ability exists in very early life in mammals, is retained in limited ways into adulthood in some mammalian species, and is exhibited in a range of other higher animals such as salamanders, it seems plausible that enabling regeneration without scarring is just a matter of finding the right switches to change cell behavior. That search has been ongoing in earnest for several decades now, digging into the biology of highly regenerative species, while manipulating the biology of mammals in search of the key, the most important points of intervention.

Fibroblasts are mesenchymal cells that account for the majority of the cellular density of the dermis and have a crucial role in wound healing. Until recently, fibroblasts were not considered to have extensive involvement in the field of scarless wound healing and were seen only as extracellular matrix (ECM) producing cells. It is now understood that there are many lineages of human fibroblasts with distinct and heterogeneous functions. Simply, some of these fibroblasts lead to scarring and some lead to regeneration. The early human foetus has mainly regenerative fibroblasts, but during aging the number of scarring fibroblasts increase to become the majority in the adult.

Scarring is the typical physiological outcome of wound healing. It is an evolutionary adaptation that provides quick and effective repair to damaged tissues, sometimes at the expense of tissue integrity and function. Scar tissue lacks skin appendages and has an organised collagen structure replacing the typical "basket-weave" dermal structure in unwounded tissues, leading to reduced tensile strength. Ideal wound repair would involve regeneration of the normal skin structure, including its associated appendages.

The ability to prevent scarring has applications beyond cosmetic and aesthetic uses, with the ability to restore function to extensively damaged tissues and preclude pathological scarring. This article describes current understanding of fibroblast heterogenicity and involvement in wound healing, focusing on the role of fibroblasts during physiological scarring. We also present the current most promising targets involving fibroblasts in the reduction of scarring and how we can manipulate the behaviour of fibroblasts to mimic the wound regeneration models in the human foetus. These targets include the pro-fibrotic EN1 positive fibroblast lineage, TGFβ1 inhibition, and genetic therapies utilising miRNAs and siRNAs.

Link: https://doi.org/10.1177/20595131221095348

Providing a summary of the present state of aging research is a tall order, given the rapid growth in the field, and great breadth of work in both academia and industry, but the authors of this lengthy review paper take a swing at it. They look at areas of interest, new and well-established, apply a loose taxonomy to diverse initiatives, and attempt to draw it all together into a cohesive whole. The thrust of the field nowadays is towards intervention, attempting to slow or reverse aging in order to treat and prevent age-related disease. The important debates are over which strategies are more likely versus less likely to succeed in this goal, and thus over whether important areas of fundamental and preclinical research are underfunded or overfunded, and whether large-scale funding for clinical development is misplaced.

Aging has attracted curiosity and elicited imagination throughout human history. However, it has been only 30 years since a new epoch in aging research was established after the isolation of the first long-lived strains in C. elegans. Nowadays, studies in the aging field are exploding with the ever-expanding knowledge of the molecular and cellular bases of life and diseases, whilst subjected to scientific scrutiny. In this current review, we summarize the cutting-edge developments in aging research, presenting the landscape of aging across multiple layers.

In the first chapter, at the cellular level, we focus on cellular senescence, a main culprit of aging, harnessing a panel of phenotypes from various aspects to reveal underlying molecular alterations and mechanisms. In addition, cellular senescence bridges aging and cancer, for which aging is a major risk factor but the causal relationship still remains elusive. On one hand, cellular senescence constitutes a potent, cell autonomous anti-cancer mechanism in vivo of higher eukaryotes; on the other hand, cellular senescence accumulating with age may evoke intrinsic reprogramming of stem cells and contribute to tumor-promoting microenvironment through SASP and inflammaging.

Amongst all cell types, stem cell aging is of particular interest, as their exhaustion and dysfunction impair tissue function and regeneration capacity and lead to age-associated disorders, driving impacts way up to organismal aging. Indeed, aging is manifested as a multisystemic deterioration throughout the body that leads to declining tissue and organ functions. What we have learned about cellular aging from the first chapter are also reflected at the tissue level; and moreover, in this aging community of cells, they are affected by each other in the same tissue through the microenvironment, or even across tissues by systemic factors.

In the second chapter, we summarize aging-associated changes that occur in various tissues and organs, including those in the circulatory system, hematopoietic and immune system, nervous system, musculoskeletal system, reproductive system, digestive system as well as the microbiota therein. Collectively, understanding mechanisms and identifying targets of tissue/organ aging open vistas to therapeutic interventions for alleviating aging and age-associated disorders.

Finally, in the third chapter, we review geroprotective approaches in the hope to rewind the biological clock to a youthful state. This can be achieved by targeting key pro-/reverse-aging factors to rejuvenate aged cells, by eliminating senescent cells, or by transplanting genetically-modified stem cells. The rejuvenating effect can be local or systematic. Sophisticated strategies have been developed to deliver it through gene therapy, antibodies, or small molecule-based drugs.

We are now entering an inspiring era of aging research. According to new scientific findings summarized here and in other equivalent publications, this era now offers unprecedented hope for extending human healthspan: preventing, delaying or, even in certain cases, reversing many of the signs of aging. Whether this era promises to extend the longest human lifespan still remains an open question. However, what is clear is that after 30 years of fundamental research linking specific genes to aging, although many aspects still await further investigation, such as the interplay between metabolism and systemic aging, a solid foundation has been established, and clinical trials for interventions that target the aging process are being initiated. Although we may encounter considerable difficulties in applying this research to humans, the potential rewards in healthy aging far outweigh the risks.

Link: https://doi.org/10.1007/s11427-022-2161-3

T cells replicate aggressively in response to infection and other threats, yet these cells must also persist in the body for years in order to maintain immunological memory. Telomeres, repeated DNA sequences at the ends of chromosomes, shorten with each cell division. This mechanism forms a part of the Hayflick limit on somatic cell replication. When telomeres become too short, cells become senescent and self-destruct, or are destroyed by immune cells. T cells can employ telomerase to lengthen telomeres, but not to any great degree. So how do they manage such long lives in an environment of repeated threats by pathogens, and thus repeated bursts of telomere-shortening replication?

In today's open access paper, the authors outline a fascinating mechanism by which antigen-presenting B cells, which interact with T cells to coordinate the immune response, donate telomeres to those T cells, thereby increasing their replicative life span. One initial thought in response to this finding is that it should be possible to create telomere-bearing vesicles to replicate this effect, more broadly than it occurs naturally. As is the case for telomerase gene therapy, and all such analogous approaches aimed at lengthening telomeres, there is the issue of selectivity, however. Extending telomeres in cells that probably should be destroyed as well as those that will continue beneficial work is a concern, even given the very positive data in mice resulting from upregulation of telomerase.

An intercellular transfer of telomeres rescues T cells from senescence and promotes long-term immunological memory

The common view is that T lymphocytes activate telomerase to delay senescence. Here we show that some T cells (primarily naïve and central memory cells) elongated telomeres by acquiring telomere vesicles from antigen-presenting cells (APCs) independently of telomerase action. Upon contact with these T cells, APCs degraded shelterin to donate telomeres, which were cleaved by the telomere trimming factor TZAP, and then transferred in extracellular vesicles at the immunological synapse.

Telomere vesicles retained the Rad51 recombination factor that enabled telomere fusion with T-cell chromosome ends lengthening them by an average of ~3,000 base pairs. Thus, there are antigen-specific populations of T cells whose ageing fate decisions are based on telomere vesicle transfer upon initial contact with APCs. These telomere-acquiring T cells are protected from senescence before clonal division begins, conferring long-lasting immune protection.

How senescent T cells are formed remains poorly understood. We propose a model whereby telomere transfer from APCs protects the recipient T cells from replicative senescence. The recipient is preferably a naïve or central memory T cell. When recipient T cells acquire telomeres from APCs during antigen presentation, they shift towards a stem-like/central long-lived memory state. Failure to acquire telomeres skews them towards senescence instead.

It is not clear how T cells with APC telomeres will divide upon telomere transfer; however, these T cells may subsequently divide and differentiate both linearly and/or asymmetrically after antigen stimulation, if telomere transfer occurs. It is possible that antigen strength may affect the amount of telomere transfer and subsequent division of T cells. However, even in situations where antigen specificity was identical, a large proportion of T cells still failed to acquire telomeres from APCs, shifting towards a short-lived effector state; some of these cells may serve as senescent progenitors. Therefore, additional mechanisms controlling telomere transfer during antigen presentation beyond T-cell receptor specificity would have to exist.

We suggest that senescent T cells, or their progenitors, may be short-lived cells that are continuously generated by episodes of activation that lack telomere transfer. An important but as-yet-undefined function of the immunological synapse is, therefore, immediate determination of senescence fates of T cells. The intercellular telomere transfer reaction described is a different form of decentralized immunity whereby APCs distribute telomeres to favour some T cells becoming long-lived memory cells, bypassing senescence. Decentralization indicates that T cells do not rely on just a single molecule, telomerase, to extend telomeres. Whether the memory T cells generated in the absence of telomere transfer have the same longevity outlook than those telomere-acquiring T cells we have studied remains to be determined.

Chronic inflammation in brain tissue is a feature of neurodegenerative conditions, including those characterized by aggregation of misfolded proteins. This includes the synucleopathies, such as Parkinson's disease, in which which α-synuclein misfolds to produce toxicity, spreading through the brain to cause dysfunction and cell death. As researchers note here, this is accelerated by the presence of inflammatory signaling.

Age is the main risk factor for neurodegenerative disorders with dementia and movement dysfunction including Alzheimer's Disease (AD), Dementia with Lewy bodies (DLB), and Parkinson's Disease (PD). While in AD, amyloid beta (Aβ) and tau play a central role, in DLB and PD, ɑ-synuclein (ɑ-syn) is a key mediator. However, ɑ-syn has been shown to accumulate in the brain during aging and in AD and in DLB, Aβ, and tau are also found in conjunction with ɑ-syn in selected brain regions.

Under physiological conditions ɑ-syn is an intracellular protein that might play a role in neuroplasticity, however during aging and under pathological conditions ɑ-syn aggregates can be released to the extracellular space leading to cell to cell propagation spreading and seeding of small aggregates into preformed protofibrils (pff) and fibrils in neighboring neuronal and non-neuronal cells. Recent evidence has shown that the intrinsic structure of ɑ-syn fibrils dictates the characteristic of the synucleinopathies and for instance inoculation of selected ɑ-syn pff into the CNS can reproduce several aspects of the pathology of DLB/PD in wild type animals models.

Although protein aggregation and spreading have been extensively studied, less is known about the contribution of aging. One possibility by which aging might lead to neurodegeneration is dysregulation in immune cell function. This might be in part mediated by extracellular ɑ-syn propagating to glial cells. For example, it has been shown that ɑ-syn can activate innate immune responses via Toll like receptors.

In this study we evaluated the role of aging in neurodegeneration in the ɑ-syn pff model. We found that inoculation of ɑ-syn pff in aged mice resulted in greater spreading and deficits compared to young mice, with ɑ-syn pff-inducing gene networks in young mice that overlapped with genes differentially expressed in aged mice. We propose that changes in inflammatory gene expression underly the increased susceptibility of aged mice to enhanced ɑ-syn induced pathology and might represent a new avenue for therapeutics.

Link: https://doi.org/10.1186/s13024-022-00564-6

Researchers here report on an approach to treating fibrosis via vaccination to target distinctive molecular features of activated fibroblasts, the cells that generate the scar-like deposits of excess collagen that are characteristic of fibrosis. This scarring disrupts tissue structure and function. At the present time, there are no truly effective treatments for fibrosis in the clinic, and it is a problem characteristic of old age that affects numerous vital organs, such as heart, lungs, liver, and kidneys. Approaches that can efficiently reverse the progression of fibrosis are very much needed.

Fibrosis is the final path of nearly every form of chronic disease, regardless of the pathogenesis. Upon chronic injury, activated, fibrogenic fibroblasts deposit excess extracellular matrix, and severe tissue fibrosis can occur in virtually any organ. However, antifibrotic therapies that target fibrogenic cells, while sparing homeostatic fibroblasts in healthy tissues, are limited. We tested whether specific immunization against endogenous proteins, strongly expressed in fibrogenic cells but highly restricted in quiescent fibroblasts, can elicit an antigen-specific cytotoxic T cell response to ameliorate organ fibrosis.

In silico epitope prediction revealed that activation of the genes Adam12 and Gli1 in profibrotic cells and the resulting "self-peptides" can be exploited for T cell vaccines to ablate fibrogenic cells. We demonstrate the efficacy of a vaccination approach to mount CD8+ T cell responses that reduce fibroblasts and fibrosis in the liver and lungs in mice. These results provide proof of principle for vaccination-based immunotherapies to treat fibrosis.

Link: https://doi.org/10.1016/j.stem.2022.08.012

Lysosomes are membrane-bound packages of enzymes found in cells. They recycle damaged and excess molecules and structures in the cell by breaking them down into raw materials that can be reused for protein synthesis. This activity is vital to cell health, and dysfunction of lysosomes is a noted feature of aging. Thus it is interesting to see a greater understanding of the ways in which cells maintain lysosomes, as outlined in today's research materials. The focus is on the repair of lysosomal membranes, a process that may break down with age, and thus some degree of benefit might be achieved by enhancing this repair. The first step on that road is to understand which proteins are involved, and thus might be targets for manipulation.

That said, it is isn't at all clear that this issue of membrane damage is the important aspect of lysosomal decline in later life. Another issue involves the accumulation of cellular waste materials that the lysosome cannot break down, which occurs in inherited lysosomal storage conditions due to loss of function mutation that robs an individual of one or more essential lysosomal enzymes, but also over the course of aging in long-lived cells. In old individuals, this mix of problem waste molecules is called lipofuscin, and lysosomes become bloated with it, unable to perform their usual tasks. Cells fall into a garbage catastrophe and become dysfunctional or die. Membrane repair is most likely not all that relevant to lysosomal performance in this situation.

Scientists Discover How Cells Repair Longevity-Promoting 'Recycling System'

As the cell's recycling system, lysosomes contain potent digestive enzymes that degrade molecular waste. These contents are walled off from damaging other parts of the cell with a membrane that acts like a chain link fence around a hazardous waste facility. Although breaks can occur in this fence, a healthy cell quickly repairs the damage. An enzyme called PI4K2A accumulated on damaged lysosomes within minutes and generated high levels of a signaling molecule called PtdIns4P, which recruits other molecules called ORPs. ORP proteins work like tethers. One end of the protein binds to the PtdIns4P red flag on the lysosome, and the other end binds to the endoplasmic reticulum, the cellular structure involved in synthesis of proteins and lipids.

The endoplasmic reticulum wraps around the lysosome like a blanket. Normally, the endoplasmic reticulum and lysosomes barely touch each other, but once the lysosome was damaged, researchers found that they were embracing. Through this embrace, cholesterol and a lipid called phosphatidylserine are shuttled to the lysosome and help patch up holes in the membrane fence. Phosphatidylserine also activates a protein called ATG2, which acts like a bridge to transfer other lipids to the lysosome, the final membrane repair step in the newly described PITT - or phosphoinositide-initiated membrane tethering and lipid transport - pathway.

The researchers suspect that in healthy people, small breaks in the lysosome membrane are quickly repaired through the PITT pathway. But if the damage is too extensive or the repair pathway is compromised - due to age or disease - leaky lysosomes accumulate. In Alzheimer's, leakage of tau fibrils from damaged lysosomes is a key step in progression of the disease.

A phosphoinositide signalling pathway mediates rapid lysosomal repair

Lysosomal dysfunction has been increasingly linked to disease and normal ageing. Lysosomal membrane permeabilization (LMP), a hallmark of lysosome-related diseases, can be triggered by diverse cellular stressors. Given the damaging contents of lysosomes, LMP must be rapidly resolved, although the underlying mechanisms are poorly understood. Here, using an unbiased proteomic approach, we show that LMP stimulates a phosphoinositide-initiated membrane tethering and lipid transport (PITT) pathway for rapid lysosomal repair.

Upon LMP, phosphatidylinositol-4 kinase type 2α (PI4K2A) accumulates rapidly on damaged lysosomes, generating high levels of the lipid messenger phosphatidylinositol-4-phosphate. Lysosomal phosphatidylinositol-4-phosphate in turn recruits multiple oxysterol-binding protein (OSBP)-related protein (ORP) family members, including ORP9, ORP10, ORP11, and OSBP, to orchestrate extensive new membrane contact sites between damaged lysosomes and the endoplasmic reticulum. The ORPs subsequently catalyse robust endoplasmic reticulum-to-lysosome transfer of phosphatidylserine and cholesterol to support rapid lysosomal repair.

Finally, the lipid transfer protein ATG2 is also recruited to damaged lysosomes where its activity is potently stimulated by phosphatidylserine. Independent of macroautophagy, ATG2 mediates rapid membrane repair through direct lysosomal lipid transfer. Together, our findings identify that the PITT pathway maintains lysosomal membrane integrity, with important implications for numerous age-related diseases characterized by impaired lysosomal function.

SPARC is one of a number of proteins that mediate interactions between cells and the extracellular matrix. Researchers here note that SPARC is connected to the chronic inflammation of aging, and the relationship between visceral fat tissue and inflammatory signaling, perhaps largely via its influence on whether macrophages adopt inflammatory behaviors in response to their environment. Reducing the amount of SPARC in fat tissue reduces chronic inflammation and thereby improves health, and this may be a meaningful mechanism in the way in which calorie restriction produces lowered inflammation and improved health. Therapies that target SPARC might prove to be useful; any approach that lowers inappropriate inflammatory signaling in later life without impacting necessary inflammatory signaling may be promising.

The risk of chronic diseases caused by aging is reduced by caloric restriction (CR)-induced immunometabolic adaptation. Here, we found that the matricellular protein, secreted protein acidic and rich in cysteine (SPARC), was inhibited by 2 years of 14% sustained CR in humans and elevated by obesity. SPARC converted anti-inflammatory macrophages into a pro-inflammatory phenotype with induction of interferon-stimulated gene (ISG) expression via the transcription factors IRF3/7.

Mechanistically, SPARC-induced ISGs were dependent on toll-like receptor-4 (TLR4)-mediated TBK1, IRF3, IFN-β, and STAT1 signaling without engaging the Myd88 pathway. Metabolically, SPARC dampened mitochondrial respiration, and inhibition of glycolysis abrogated ISG induction by SPARC in macrophages. Furthermore, the N-terminal acidic domain of SPARC was required for ISG induction, while adipocyte-specific deletion of SPARC reduced inflammation and extended health span during aging. Collectively, SPARC, a CR-mimetic adipokine, is an immunometabolic checkpoint of inflammation and interferon response that may be targeted to delay age-related metabolic and functional decline.

Link: https://doi.org/10.1016/j.immuni.2022.07.007

Unsurprisingly, given other data on exercise and aging, researchers here show that greater activity correlates with a reduced risk of suffering dementia. The data in this study comes from accelerometer devices, counting steps and intensity. The introduction of accelerometers over the past few decades has led to a considerable improvement in the quality of epidemiological data relating to physical activity, particularly the relationship between low levels of activity and health. Any increment above being sedentary provides a meaningful improvement, relative to the harms done by inactivity, but the optimal level of activity is somewhat higher than that.

Step-based recommendations may be appropriate for dementia-prevention guidelines. However, the association of step count and intensity with dementia incidence is unknown. This study examined the dose-response association between daily step count and intensity and incidence of all-cause dementia among adults in the UK. This was a UK Biobank prospective population-based cohort study (February 2013 to December 2015) with 6.9 years of follow-up (data analysis conducted May 2022). A total of 78,430 of 103,684 eligible adults aged 40 to 79 years with valid wrist accelerometer data were included. Registry-based dementia was ascertained through October 2021.

We found no minimal threshold for the beneficial association of step counts with incident dementia. Our findings suggest that approximately 9,800 steps per day may be optimal to lower the risk of dementia. We estimated the minimum dose at approximately 3,800 steps per day, which was associated with 25% lower incident dementia. This finding suggests that population-wide dementia prevention might be improved by shifting away from the least-active end of the step-count distributions. Unlike previous studies investigating mortality outcomes, our analyses highlight the importance of stepping intensity for preventing dementia. Both purposeful steps and peak 30-minute cadence (i.e. an indicator of overall best natural effort in a free-living environment) were associated with lower risks of dementia.

Link: https://doi.org/10.1001/jamaneurol.2022.2672

A great deal of modern medicine starts out as genetic studies in cells and animal models, but then the programs abandon genetics to use small molecules to produce a small fraction of the effect of the genetic alteration of interest. The reasons for this have a lot to do with the high cost of regulation and conservatism of funding sources, to the point at which the development of a poor therapy using well-proven approaches is very much favored over the development of a much better therapy using new approaches. In the broader sense, in the longer term, the true promise of gene therapies, the various approaches that dial up and dial down the expression of specific genes, is that the research and development industry can stop producing treatments that are objectively bad in comparison to the alterations of gene expression that inspired them.

Given the state of the industry today, however, one should absolutely expect that any promising form of therapy derived from genetic studies will be the subject of intense effort to translate it into a small molecule treatment that produces only a fraction of the benefits. So it goes with cellular reprogramming as an approach to rejuvenation, resetting epigenetic patterns in old cells by overexpressing the Yamanaka factors, typically for only a short period of time. Researchers are trying to find combinations of small molecules that tinker with transcription factor expression or downstream mechanisms to use in place of the mRNA therapies currently employed for partial reprogramming of cells in animal studies. It will be interesting to see the degree to which they succeed as this initiative moves forward in the years ahead.

Chemical reprogramming ameliorates cellular hallmarks of aging and extends lifespan

The dedifferentiation of somatic cells into a pluripotent state by cellular reprogramming coincides with a reversal of age-associated molecular hallmarks. Although transcription factor induced cellular reprogramming has been shown to ameliorate these aging phenotypes in human cells and extend health and lifespan in mice, translational applications of this approach are still limited. More recently, chemical reprogramming via small molecule cocktails have demonstrated a similar ability to induce pluripotency in vitro, however, its potential impact on aging is unknown.

Here, we demonstrated that partial chemical reprogramming is able to improve key drivers of aging including genomic instability and epigenetic alterations in aged human cells. Moreover, we identified an optimized combination of two reprogramming molecules sufficient to induce the amelioration of additional aging phenotypes including cellular senescence and oxidative stress. Importantly, in vivo application of this two-chemical combination significantly extended C. elegans lifespan by 42%. Together, these data demonstrate that improvement of key drivers of aging and lifespan extension is possible via chemical induced partial reprogramming, opening a path towards future translational applications.

The interesting research noted here implicates pressure-based changes in the structure of vitronectin as a mediating mechanism linking raised blood pressure and ocular pressure and calcification in tissues. Calcification results from changes in cell behavior that lead to calcium deposition akin to that occurring in bone tissue, but in inappropriate locations such as blood vessel walls. This is disruptive of structure and function, a facet of aging that should be addressed as a part of any comprehensive package of rejuvenation therapies.

"Proteins in the blood are under constant and changing pressure because of the different ways blood flows throughout the body. For example, blood flows more slowly through small blood vessels in the eyes compared to larger arteries around the heart. Blood proteins need to be able to respond to these changes, and this study gives us fundamental truths about how they adapt to their environment, which is critical to targeting those proteins for future treatments."

There are hundreds of proteins in our blood, but the researchers focused on vitronectin, one of the most abundant. In addition to circulating in high concentrations in the blood, vitronectin is found in the scaffolding between cells and is also an important component of cholesterol. "This protein is an important target for macular degeneration because it accumulates in the back of the eye, causing vision loss. Similar deposits appear in the brain in Alzheimer's disease and in the arteries in atherosclerosis. We want to understand why this happens and leverage this knowledge to develop new treatments."

To approach this question, the researchers were interested in learning how the protein changes its structure at different temperatures and under different levels of pressure, approximating what happens in the human body. Through detailed biochemical analysis, the researchers found that the protein can subtly change its shape under pressure. These changes cause it to bond more easily to calcium ions in the blood, which the researchers suggest leads to the buildup of calcified plaque deposits characteristic of macular degeneration and other age-related diseases. "It's a very subtle rearrangement of the molecular structure, but it has a big impact on how the protein functions. The more we learn about the protein on a structural and mechanistic level, the better chance we have of successfully targeting it with treatments."

Link: https://sbpdiscovery.org/news/how-a-single-protein-could-unlock-age-related-vision-loss

Exercise is known to slow the progression of Parkinson's disease, or at least attenuate the symptoms. What is the underlying mechanism? Researchers here suggest that the myokine signal protein irisin accounts for much of this, by promoting greater removal of problematic α-synuclein aggregates. Parkinson's disease is associated with α-synuclein misfolding and consequent aggregation, these toxic versions of a normally helpful protein spreading through the central nervous system over time to cause cell death and dysfunction in vulnerable populations of neurons. Clearing misfolded α-synuclein seems a viable strategy, given the right approach, something much more potent than the effects of exercise.

Physical exercise is thought to have beneficial effects on the symptoms of Parkinson's disease (PD). Irisin is an exercise-induced myokine released into the circulation. We therefore tested whether irisin itself could have a beneficial effect on pathologic α-synuclein (α-syn) accumulation and concomitant neurodegeneration in PD.

Here, we show that irisin prevents pathologic α-synuclein (α-syn)-induced neurodegeneration in the α-syn preformed fibril (PFF) mouse model of sporadic PD. Intravenous delivery of irisin via viral vectors following the injection of α-syn PFF cause a reduction in the formation of pathologic α-syn and prevented the loss of dopamine neurons and lowering of striatal dopamine. Irisin also substantially reduced the α-syn PFF-induced motor deficits as assessed behaviorally by the pole and grip strength test.

In vitro, recombinant sustained irisin treatment of primary cortical neurons attenuated α-syn PFF toxicity by reducing the formation of phosphorylated serine 129 of α-syn and neuronal cell death. Tandem mass spectrometry and biochemical analysis revealed that irisin reduced pathologic α-syn by enhancing endolysosomal degradation of pathologic α-syn. Our findings highlight the potential for therapeutic disease modification of irisin in PD.

Link: https://doi.org/10.1073/pnas.2204835119

Senescent cells accumulate with age, and their presence contributes to chronic inflammation and many other age-related disruptions to normal tissue function. Academia and industry are engaged in many programs aimed at the creation of senolytic treatments that can selectively destroy senescent cells. The most proven senolytic treatment to date is the dasatinib and quercetin combination, shown to partially clear senescent cells from tissues in both old mice and old humans. Dasatinib is a tyrosine kinase inhibitor, and here researchers report their evidence in support another tyrosine kinase inhibitor, nintedanib, to be usefully senolytic.

Will nintedanib prove to be better or worse than dasatinib? That is hard to say, and different members of the same class of drugs can vary widely in all characteristics. The evidence here should be balanced against the history of nintedanib, given that it is approved for use in slowing the progression of idiopathic pulmonary fibrosis, and has been used for some years in that role. Senescent cells are thought to contribute to the development of idiopathic pulmonary fibrosis, and the dasatinib and quercetin combination showed promise in a small clinical trial for idiopathic pulmonary fibrosis patients. Animal data suggests dasatinib to be much less senolytic on its own, without quercetin, but no-one has yet earnestly tried to combine nintedanib and quercetin. Time will tell as to which senolytic approaches are the most useful.

Nintedanib induces senolytic effect via STAT3 inhibition

Selective removal of senescent cells, or senolytic therapy, has been proposed to be a potent strategy for overcoming age-related diseases and even for reversing aging. We found that nintedanib, a tyrosine kinase inhibitor, selectively induced the death of primary human dermal fibroblasts undergoing replicative senescence. Similar to ABT263, a well-known senolytic agent, nintedanib triggered intrinsic apoptosis in senescent cells. Additionally, at the concentration producing the senolytic effect, nintedanib arrested the cell cycle of nonsenescent cells in the G1 phase without inducing cytotoxicity.

Interestingly, the mechanism by which nintedanib activated caspase-9 in the intrinsic apoptotic pathway differed from that of ABT263 apoptosis induction; specifically, nintedanib did not decrease the levels of Bcl-2 family proteins in senescent cells. Moreover, nintedanib suppressed the activation of the JAK2/STAT3 pathway, which caused the drug-induced death of senescent cells. STAT3 knockdown in senescent cells induced caspase activation. Moreover, nintedanib reduced the number of senescence-associated β-galactosidase-positive senescent cells in parallel with a reduction in STAT3 phosphorylation and ameliorated collagen deposition in a mouse model of bleomycin-induced lung fibrosis. Consistently, nintedanib exhibited a senolytic effect through bleomycin-induced senescence of human pulmonary fibroblasts.

Overall, we found that nintedanib can be used as a new senolytic agent and that inhibiting STAT3 may be an approach for inducing the selective death of senescent cells. Our findings pave the way for expanding the senolytic toolkit for use in various aging statuses and age-related diseases.

You might recall that researchers recently reported that the combination of rapamycin, acarbose, and phenylbutyrate appear to meaningfully improve physical function in old mice. Here, the same team reports on the efforts of this intervention on cognitive function in mice. Individually, these treatments, applied over the long term, are all shown to slow aging to some degree in mice. It remains to be seen whether combination treatments of this sort, upregulation of cellular stress responses, mimicking aspects of the cellular response to exercise and calorie restriction, will be as useful in humans. It is the case that life span is not greatly affected by this type of strategy in long-lived mammals, only in short-lived mammals do adjustments to metabolism mimicking calorie restriction produce sizable life extension.

Aging is a primary risk factor for cognitive dysfunction and exacerbates multiple biological processes in the brain, including but not limited to nutrient sensing dysregulation, insulin sensing dysfunction and histone deacetylation. Therefore, pharmaceutical intervention of aging targeting several distinct but overlapping pathways provides a basis for testing combinations of drugs as a cocktail. A recent study showed that middle-aged mice treated with a drug cocktail of rapamycin, acarbose, and phenylbutyrate for three months had increased resilience to age related cognitive decline. This finding provided the rationale to investigate the comprehensive transcriptomic and molecular changes within the brain of mice that received this cocktail treatment or control substance.

Transcriptome profiles were generated through RNA sequencing and pathway analysis was performed by gene set enrichment analysis to evaluate the overall RNA message effect of the drug cocktail. Molecular endpoints representing aging pathways were measured through immunohistochemistry to further validate the attenuation of brain aging in the hippocampus of mice that received the cocktail treatment, each individual drug or controls. Results indicated that biological processes that enhance aging were suppressed, while autophagy was increased in the brains of mice given the drug cocktail. The molecular endpoint assessments indicated that treatment with the drug cocktail was overall more effective than any of the individual drugs for relieving cognitive impairment by targeting multiple aging pathways.

Link: https://doi.org/10.1101/2022.09.07.506968

Researchers here note that expression of β2-microglobulin rises with age in cells of the inner cheek, correlating with p16 expression, a marker of cellular senescence. β2-microglobulin is connected to inflammation, and senescent cell burden is one of the more important contributions to the chronic inflammation of old age. One can never have too many biomarkers of age, even if they are individually only loosely correlated with age, as combining them can in principle produce better and more accurately correlated metrics.

β2-microglobulin (β2M) is a small protein that is expressed in all nucleated cells, previous data showed that its activity increases during inflammation. β2M interplays with cytokines for instance, IL-6, IL-8 and others intracellularly to induce inflammatory responses. In addition, it can bind and modulate the activity of growth factors and hormones and receptors. β2M has been exploited as a biomarker for many disorders with inflammatory components.

Our group previously showed that β2M expressed highly in senescent cells, and recently it has been shown by our group that β2M expressed highly in blood samples of old people comparing to youngers. Furthermore, we have shown that β2M correlated significantly with oxidative stress biomarkers, which could underscore a potential role in oxidative stress network. Therefore, there is a rationality to test the expression of β2M across different group of age using other easier source of sample such as buccal cells.

Buccal cells are epithelial cells that are similar to brain and skin in nature. Buccal cells can be collected easily, deriving a high number of cells that can be used for different biological assays. Comparing to other sample methods, buccal cell samples are less invasive and very easy to collect. In addition, buccal cells are very stable after isolation from the mouth, which makes them easy to process and analyze. Moreover, buccal cells are easy to preserve, making them an easy source for diagnosis.

In this study, we used buccal cells to examine the expression of β2M in different age groups. The expression of β2M increased significantly with fold change 3.40, 4.80, 6.60, 8.20 and 12.04 for the group of age 18-25 years, 26-35 years, 36-45 years, 46-55 years, and 56-70 years respectively. The same observation was seen with markers of biological aging (p16INK4a) with fold change 3.19, 3.90, 4.80, 8.50 and 12.40 for the group of age 18-25 years, 26-35 years, 36-45 years, 46-55 years, and 56-70 years respectively.

As expected, there was an increase in expression of inflammatory genes (IL-1β and IL-6) in the elderly. Moreover, there was a direct significant correlation (Pearson correlation coefficient, r = 90) between β2M expression and age, and the same direct significant correlation between p16INK4a expression and age was also seen (r = 90). In addition, a direct correlation between β2M and p16INK4a was also seen (r = 0.83), there was also direct correlation between β2M and IL-1β (r = 0.5) and IL-6 (r = 0.68).

This evidence showed that β2M increased in buccal cells of the elderly compared to younger, and thereby buccal cells can be exploited to assess biological aging by measuring β2M levels, however, large sample size and using another assessing method such as β2M protein levels should be performed to confirm the results.

Link: https://doi.org/10.1016/j.sjbs.2022.103418

I suspect that a sizable, earnest community of opportunists and alchemists focused on anti-aging and longevity will continue to exist even as we transition from an era in which the only approaches to aging (beyond exercise and calorie restriction) were snake oil, the only service providers frauds, to an era in which therapies to slow aging and produce rejuvenation actually exist and are robustly proven to do what they say on the label. Will reliable, low-cost ways to measure biological age drive out the true believers who try whatever intervention is hyped, fail to gain scientific understanding, and fail to use adequate measures of success, living on a diet of hope? Will reliable, low-cost ways to measure biological age drive out the opportunists who sell that hope, in the form of whatever trendy, unproven strategy is claimed to slow aging today? Maybe, given time.

Sadly, the advent of epigenetic clocks hasn't yet helped that much. Since no-one knows what exactly an epigenetic clock measures in terms of the progression of aspects of aging, such as underlying molecular damage, or specific loss of function to organs and systems, we now have would-be demagogues claiming justification via low epigenetic ages allegedly resulting from their own personal strategies. This sort of data cannot yet be trusted in the absence of accompanying biomarkers of aging in which one can see meaningful differences following interventions. Those biomarkers are in short supply for basically healthy people much under the age of 50; differences will be small until later life for near everything that can be attempted at the present time. There are few exceptions to this situation, such as the state of the gut microbiome and the thymus and the ovaries, but the important line items of immune health, cardiovascular health, and function of other organs just haven't faltered enough by that stage of life to be useful markers at this time.

Today's article, with the usual depressing undertone of virtue signaling that journalists of the popular press seem to think is required these days, is an example of the consequences of a world in which most people cannot tell the difference, or do not care to tell the difference, between arrant nonsense, unproven therapies, proven therapies, legitimate scientific development, and outright snake oil. It all gets lumped into one bucket labeled "treating aging", and those of us on the inside of aging research, patient advocacy, and the longevity industry wonder why it is sometimes challenging to convince people that aging can be treated, that we are on the way to human rejuvenation, that it is different this time, that what is going on is something more than branded skin care, fools tilting at windmills, fraud, and lies to cover up the wrinkles and the failing physiology.

The Death Cheaters

Last fall, a group of 30 people gathered at an Etobicoke estate to sample the latest in life-extension innovations. They sipped brain-boosting beverages laced with lion's mane mushrooms and garnished with grapefruit, participated in a breathwork session and soaked up the electromagnetic pulses of the BioCharger, a $20,000 device that looks like a giant blender, sounds like a bionic mosquito and is purported to fight chronic disease, brain fog, and flagging libido, among many other ailments. The evening was a soft launch for Longevity House, a private members' club for Toronto's burgeoning community of biohackers.

The price tag, $100,000 for a lifetime membership, was staggering. The promise, even more so: a chance to live longer, possibly to 120 years old. And not just longer but better, free from chronic illness and cognitive decline, by which standard six figures starts to sound like a bargain. Before launching Longevity House, Michael Nguyen was best known as the haberdasher to Toronto's one-percenters. In 2021, Nguyen purchased a $3-million, 7,500-square-foot mansion in Mimico and packed it with the latest in high-performance fitness equipment: alongside the BioCharger is a Tonal (the weightlifting system LeBron James uses), a Carol (an artificially intelligent exercise bike) and a Katalyst (an electronic muscle-stimulation garment that looks like a wetsuit and promises "the world's most efficient workout"). There is also a red-light therapy room, a full-body vibration plate, a cold plunge tub, and a custom-built sauna. Nguyen and his team have secured partner-ships with in-demand health and wellness-practitioners-naturopaths, breathwork specialists, a chakra guy, a therapist who specializes in psychedelics, and functional-medicine doctors who read blood and stool samples like physiological tea leaves.

Biohacking - to "hack" one's biology for the purposes of optimization - is wellness spiked with gadgetry. It's New Age woo-woo with internet-age efficiency, Gwyneth Paltrow's Goop but for tech bros. (As yet, Longevity House has no female members, and on more than one occasion, I heard Joe Rogan's name spoken with reverence.) What is a biohack, exactly? That's hard to pin down since the category covers pretty much any health intervention, from the obvious to the outlandish. Yoga is a biohack. So is wearing a Fitbit. So are probiotics and mood-enhancing supplements, forest bathing, and looking deeply into another person's eyes for a full minute. Also DIY experimental gene editing, fecal transplantation, and uploading your consciousness onto an external server in the hopes of one day joining a race of cyborgs. (Elon Musk is working on it.) The common thread among biohackers is a mindset that views Mother Nature's work as a starting point.

Nguyen is used to the naysayers - history is littered with them. "We're operating outside the norms of society, which can make people nervous," he says. And that's true, isn't it? Don't all breakthroughs start off as someone's outlandish idea? Wasn't Galileo convicted of heresy for his audacious insistence that the Earth orbits the sun? Isn't it possible that my staunch allegiance to science will leave me on my deathbed while the biohackers skateboard into the next century? Nguyen is a charming and passionate hype man. But is he a modern Galileo or just a guy cashing in on the latest craze?

The epidemiological study noted here makes use of phenotypic age, a simple biomarker-based aging clock. The calculation used to derive a phenotypic age based on common biomarkers can be in the methods section of the paper, for those interested. It is a mortality-related calculation, and a higher phenotypic age is presumed to indicate a greater risk of age-related disease and death. Where phenotypic age is greater than chronological age, this may represent a faster pace of aging in that individual, as is the case for epigenetic clocks and epigenetic age acceleration.

The conclusion reached in the study here is that unhealthy lifestyle choices, such as becoming overweight, mediate much of the relationship between childhood adversity and shorter life expectancy, which we might compare with past research suggesting that early life adversity raises the chance of early exposure to cytomegalovirus and thus leads to a higher lifetime burden of inflammation and immune dysfunction.

Accelerated aging makes adults more vulnerable to chronic diseases and death. Whether childhood adversity is associated with accelerated aging processes, and to what extent lifestyle mediates the association, remain unknown. Out objective was to examine the associations of childhood adversity with a phenotypic aging measure and the role of unhealthy lifestyle in mediating these associations. A retrospective cohort analysis was conducted using data from adult participants in the UK Biobank baseline survey (2006-2010) and online mental health survey (2016). Childhood adversity, including physical neglect, emotional neglect, sexual abuse, physical abuse, and emotional abuse, was assessed retrospectively through the online mental health survey (2016).

A phenotypic aging measure, phenotypic age acceleration, was calculated, with higher values indicating accelerated aging. Body mass index, smoking status, alcohol consumption, physical activity, and diet were combined to construct an unhealthy lifestyle score (range, 0-5, with higher scores denoting a more unhealthy lifestyle). A total of 127,495 participants aged 40 to 69 years were included. Each individual type of childhood adversity and cumulative childhood adversity score were associated with phenotypic age acceleration. For instance, compared with participants who did not experience childhood adversity, those who experienced 4 (β = 0.296) or 5 (β = 0.833) childhood adversities had higher phenotypic age acceleration in fully adjusted models. The formal mediation analysis revealed that unhealthy lifestyle partially mediated the associations of childhood adversity with phenotypic age acceleration by 11.8% to 42.1%.

In this retrospective cohort study, childhood adversity was significantly associated with acceleration of aging and, more importantly, unhealthy lifestyle partially mediated these associations. These findings reveal a pathway from childhood adversity to health in middle and early older adulthood through lifestyle and underscore the potential of more psychological strategies beyond lifestyle interventions to promote healthy aging.

Link: https://doi.org/10.1001/jamanetworkopen.2022.30690

Following on from a recent study that suggested undergoing yearly vaccination for influenza can greatly reduce Alzheimer's risk, researchers here show that influenza vaccination correlates with a lower risk of stroke. The mechanisms of interest behind both of these correlations seem likely to revolve around chronic inflammation, an important factor in both the growth of atherosclerotic plaques in blood vessels and the onset and progression of neurodegenerative conditions. Firstly, suffering influenza is an inflammatory event, and the vaccine lowers the incidence and severity of that outcome. Secondly vaccination of this sort can reduce inflammation in the central nervous system via what is known as trained immunity, an improvement in the function of the innate immune system in response to the vaccine.

Researchers looked at a health care database in Spain and identified people who were at least 40 years old and had a first stroke over a 14-year period. Each person who had a stroke was compared to five people of the same age and sex. There were 14,322 people who had a stroke and 71,610 people who did not have a stroke. Then the researchers looked at whether people had received the influenza vaccine at least 14 days before the stroke or before that same date for those who did not have a stroke.

A total of 41.4% of those who had a stroke had received the flu shot, compared to 40.5% of those who did not have a stroke. But the people who got the shot were more likely to be older and to have other conditions such as high blood pressure and high cholesterol that would make them more likely to have a stroke. Once researchers adjusted for those factors, they found that those who received a flu shot were 12% less likely to have a stroke than those who did not.

The researchers also looked at whether the pneumonia vaccine had any effect on the risk of stroke and found no protective effect. Since the study was observational, it does not prove that getting the flu shot reduces the risk of stroke. It only shows an association. There could be other factors that were not measured that could affect the risk of stroke.

Link: https://www.aan.com/PressRoom/Home/PressRelease/5012

There is considerable enthusiasm in the cancer research community regarding the prospects for improved patient outcomes via the use of senolytics to clear senescent cells from tissues. It seems fairly clear that an increased burden of senescent cells results from the use of traditional cancer therapies, chemotherapy and radiotherapy, and that this is most likely the cause of a large fraction of the greater risk of age-related disease and shorter remaining life expectancy in cancer survivors. Undergoing those forms of cancer therapy is literally a matter of signing up for accelerated aging - and still the preferable alternative, of course, when the other option is death by runaway cell growth and metastasis.

It seems plausible that senolytic therapies can be applied after cancer treatment has ended to mitigate the long-term consequences of that treatment. There are more senescent cells, induced by treatment, and effective senolytics will remove a large fraction of those cells. This is straightforward. What is less straightforward is whether (and in what circumstances) it will be helpful or harmful to use senolytics alongside cancer treatments, at the same time. For some cancers and stages of cancer, this may dramatically improve outcomes. We might think of the forms of leukemia that appear to create senescent cells in order to produce a more favorable growth environment, for example. In other cases, it might not be so helpful, but time will tell.

Targeting senescence as an anti-cancer therapy

Senescence exerts multiple and sometimes opposing effects in tumorigenesis. The oncogenic activation events involved in cancer initiation trigger oncogene-induced senescence (OIS) in preneoplastic lesions and limit their progression. Consequently, mutations that disable senescence are needed for tumours to progress to more malignant stages. Most cancer therapies work, at least in part, by triggering senescence (therapy-induced senescence, TIS). But TIS in non-cancerous cells has been linked to some of the side effects associated with chemotherapy. And lingering senescent cells present in the tumour and TME contribute to sustain cancer development and progression.

Different types of senescent cells are present in the tumour microenvironment (TME) during cancer initiation, progression and in response to therapy. Many preneoplastic lesions are enriched in senescent cells. This is because activation of oncogenes (e.g., RAS in lung or BRAF in nevi) or loss of tumour suppressor (e.g., PTEN in the prostate) induces senescence, what restrains tumour progression. Another contributor to senescence-induction in the context of tumorigenesis are anti-cancer treatments, as radiotherapy, conventional chemotherapy and some targeted therapies: that cause so-called therapy-induced senescence (TIS) in the tumour cells. Cancer therapies can also induce senescence in cells other than the tumour cells. Indeed, induction of senescence in normal tissues has been suggested to cause some of the side effects associated with chemotherapy.

Finally, other cells in the TME might also undergo senescence. Stromal senescent cells are an emerging factor contributing to tumorigenesis and promote cancer drug resistance. Senescent cells in the TME can also arise in a paracrine fashion, as factors secreted by tumour (senescent) cells can induce senescence in the stroma or render infiltrating immune cells senescent. For example, a study using a p16INK4A luciferase reporter mice show how after implanting different tumour cells grafts that do not express the luciferase reporter, luciferase activity arises in the tumour-associated stroma, demonstrating the ability of tumours to induce senescence in their surroundings.

In this review, we enumerate how current anti-cancer therapies induce senescence in tumour cells and how senolytic agents could be deployed to complement anticancer therapies. While senescent cells influence many aspects of tumour progression, a way to deploy senotherapeutics for cancer treatment is the so-called "one-two punch" approach. The rationale of "one-two punch" therapies is that many cancer therapies induce senescence and using senolytics (as a second punch) would therefore target a newly exposed vulnerability in the cancer cells. "One-two punch" represents an emerging and promising new strategy in cancer treatment.

One-two punch protocols have been tried with a wide range of senolytics, including cardiac glycosides, BRD4 inhibitors, and galacto-coated nanoparticles loaded with doxorubicin or navitoclax or the Gal-Nav prodrug. There are several clinical trials evaluating the effect of the senolytic navitoclax in combination with chemotherapy in cancer patients. However, the contribution of senescence and senolysis to the therapeutic effect will not be evaluated on most of those trials. In addition, other senolytics, such as the dasatinib and quercetin combination or fisetin, are being evaluated in different trails, including one aiming to improve frailty in adult survivors of childhood cancer.

In addition to clinical trials, retrospective analysis is another way to test the potential of drugs repurposed as senolytics. For example, cancer patients treated with the cardiac glycoside digoxin during chemotherapy have a better overall survival. Cardiac glycosides have pleiotropic effects, and the aforementioned study attributed the effect to immunogenic cell death. But given that cardiac glycosides have senolytic properties, it would be worthy investigating whether senolysis might explain those results.

TREM2 is a receptor found on microglia in the brain, and in recent years researchers have found that targeting it with antibodies can enhance clearance of amyloid-β in mouse models of Alzheimer's disease. The microglia, responsible for clearing molecular waste, are stimulated to greater activity by this interaction with TREM2. The usual caveats apply here, such as the artificiality of mouse models for this condition, and the fact that successful clearance of amyloid-β via immunotherapy in Alzheimer's patients has not resulted in meaningful improvement to symptoms. Nonetheless, work on amyloid-β clearance continues, with the hope that early intervention, in the years prior to the point at which Alzheimer's manifests, during which amyloid-β levels slowly increase in the brain, will push back onset of the condition.

A newly developed agonistic antibody reduced the amyloid pathology in mice with Alzheimer's disease, signaling its promise as a potential treatment for the disease. Researchers found that a tetra-variable domain antibody targeting the triggering receptor expressed on myeloid 2 (TREM2) - dubbed TREM2 TVD-lg - reduced amyloid burden, eased neuron damage, and alleviated cognitive decline in mice with Alzheimer's disease.

TREM2 is a single-pass receptor expressed by microglia - supportive cells that function as scavengers in the central nervous system. The antibody increased TREM2 activation and promoted phagocytosis of amyloid and microglia survival. Microglia play a crucial role in the removal of amyloids that cluster around amyloid-beta plaques, a hallmark of Alzheimer's disease. While previous research has shown that TREM2 plays an important role in the pathophysiology of Alzheimer's disease, the recent findings suggest that increasing TREM2 activation could have therapeutic effects such as improved cognition.

Link: https://www.uth.edu/news/story/new-antibody-shows-therapeutic-effects-in-mice-with-alzheimers-disease

Countless processes operating in the body progressively fail with age, each one an inconvenience at the outset, and many turning from that to an ultimately fatal reduction in vital capabilities over the decades of later life. The defense against pathogens offered by innate immune functions, including generation of mucus to trap and expel pathogens, holds up relatively well with advancing age, in comparison to many organs, but it is nonetheless is reduced in capacity with age. Researchers note here that the mucosal systems of the lung suffer detrimental changes with aging, with the consequence of increased vulnerability to inhaled pathogens and particles.

The lung is exposed to a myriad of substances with every breath we take. To protect itself from pollutants, dust, particulate matter, allergens, viruses, bacteria, and fungi that exist in the air around us, the lung has evolved a highly tuned innate immune system. One of the first lines of defense against inhaled matter is mucociliary clearance, which is performed by the airway epithelium of the trachea and the central conducting airways.

The conducting airways of the lung are lined by ciliated airway epithelial cells. The ciliated cells are covered by a thin periciliary sol layer that is approximately the same height as the cilia. The periciliary layer is low viscosity and facilitates ciliary beating. Interspersed with the ciliated cells are mucus-producing cells. In the conducting airways, goblet cells are the most prevalent mucus-producing cell. The apical cytoplasm of goblet cells is filled with membrane-bound secretory granules filled with mucins. These granules are secreted to form the mucus layer. Mucus is a thick, gel-like material that consists of water, salts, mucins, proteoglycans, lipids, and proteins. This blanket of mucus is free-floating over the respiratory epithelium. When an insoluble foreign substance is inhaled and deposits in the airway, it is trapped in a blanket of mucus. The cilia then beat in a coordinated manner to expel mucus from the lungs.

Cough is also an important mechanism of clearing the airways. In humans, cough increases as mucociliary clearance slows. Impairment in cough sensitivity can lead to recurrent pneumonia. Mucociliary clearance can be affected by changes in the quantity, viscosity, or composition of mucus or changes in ciliary number, structure, beating, or coordination. Aging can cause changes in many of the mucociliary clearance apparatus components, include structural changes in the airway epithelium, changes in cilia function, as well as changes in mucus quality, leading to a higher propensity for chronic lung disease and infection with aging.

Link: https://doi.org/10.20900/agmr20220005

The SENS Research Foundation has published its annual reports for 2022, for those interested. SENS, the Strategies for Engineered Negligible Senescence, is both (a) a laundry list of forms of cell and tissue damage that cause aging, with supporting evidence from the past century of scientific research into aging, and (b) a laundry list methods of intervention that should produce rejuvenation. Aging is damage accumulation, and rejuvenation is repair of that damage.

Funding for SENS programs, and initiatives to produce therapies based on the SENS view of damage repair, remain as relevant as ever. In fact, even more relevant now than was the case in the early 2000s, given the extensive evidence gathered over the past decade to support the SENS view on the role of senescent cells in aging. The view that accumulation of senescent cells is an important aspect of aging, and a viable point of intervention for the first rejuvenation therapies worthy of the name, was first published by Aubrey de Grey and others in an academic paper in 2002, well in advance of the 2011 technology demonstration of senescent cell clearance that convinced enough of the research community for further exploration to be prioritized.

Today, twenty years after the first call to action, and ten years after the first compelling demonstration, many biotech companies are working on the development of therapies to selectively destroy or modulate the behavior of senescent cells, scores of animal studies show reversal of measures of age-related disease following partial clearance of senescent cells in old mice, human clinical trials are underway, and countless research groups are investigating the biology of senescent cells, in search of new approaches to achieve these goals.

Senescent cells are just one of the seven categories of cell and tissue damage outlined in the SENS proposals for a rejuvenation biotechnology industry. The SENS Research Foundation and its allied researchers and spin-out companies remain necessary: the success achieved in turning senescent cell clearance from a compelling idea to (almost) a clinical reality must be repeated, and repeated many times, if we are to achieve the goal of cures for age-related disease, prevention of frailty, sickness, and death in the old, elimination of the largest cause of suffering and mortality in the human condition.

2022 Annual Report

Like so much in our modern world, curing the diseases of aging is a collaborative effort. In 2021, SENS Research Foundation (SRF) found itself at the center of a brand new way to fundraise. The ingenuity and generosity of Richard Heart, and the willingness to envision a life free from age-related disease from a forward-thinking global community, provided SRF with unprecedented resources. We gained not only in dollars, but also in number of supporters. Our vision struck a chord that reverberated across a broader group of people than ever before. Our mission inspired so many to put their trust and resources behind us, and we could not be more grateful or more determined to honor their support through the acceleration and expansion of our vital research. At the same time, we had a changing of the guard at SRF. Undergoing internal investigations in the public eye, under intense scrutiny. Saying goodbye to our visionary founder, to a full half of our Board of Directors, and to our long-time Director of Education.

Within the last year, SRF has seen more upheaval, more incredible support, and more intense criticism, than in the entirety of the previous decade. And yet we remain, passionately in pursuit of the mission that drove our founding. Our dedication to making the 'Strategies for Engineered Negligible Senescence' a life-saving reality is rock-solid, as we hope this Annual Report will make clear. Our mission is vital; one hundred thousand people die every day of age-related disease. Millions more suffer due to age- related decline and disability. Our mission cannot be side-tracked, cannot be delayed, and must take precedence over all other concerns. Last year was difficult, but also empowering. Our leadership may change, but our founding vision is powerful and keeps us focused on the path ahead. Our mission is our defining priority. Together, we will build this new world, one brick at a time.

2022 Research Report

Catalytic Antibodies Targeting Intracellular Tau Oligomers

Therapeutic interventions with anti-tau immunotherapies have shown promise, but the efficacy seems to vary greatly. The tau LysoSENS group at SENS Research Foundation is investigating the therapeutic potential of catabodies (catalytic antibodies) targeted to the intracellular compartment to degrade tau aggregates and prevent or reverse tau-associated neurodegeneration. Unlike conventional binding antibodies, catabodies bind transiently to their targets and hydrolyze them into very small hydrolytic end-products, leaving the catabody free to attack the next target molecule.

Rejuvenating Immune Surveillance of Senescent Cells

Natural Killer (NK) cells are a known key immune cell type responsible for the immune-mediated senolysis of senescent cells. Moreover, NK cells are increasingly emerging as an important defense against several age-related diseases, the best-understood example of which is cancer. However, NK cell function declines as part of immunosenescence, and this likely includes immune surveillance of senescent cells, leaving the host increasingly vulnerable to diseases of aging, as recently reviewed in a paper published by the Sharma lab at SENS Research Foundation.

To understand the potential of NK cell transplantation as an immunosenolytic therapy, the ApoptoSENS team is collaborating with the Campisi lab at the Buck Institute to investigate the effect of aging on NK cell cytotoxicity toward senescent cells. Studies will test the ability of young vs. old donor derived NK cells to remove senescent cells in a mouse model. Additionally, the Sharma lab is in the process of developing CAR (Chimeric Antigen Receptor)-NK cells with enhanced ability to target senescent cells for adoptive cell therapy, and the above studies will be repeated using CAR-NK cells.

Studying age-related changes in the immune cells has led the ApoptoSENS team to discover a sub-population of T-cells that declines with age. Analysis indicates that these "X cells" constitute only approximately 5% of total peripheral blood mononuclear cells, so in order to investigate their interaction with senescent cells, the team established a protocol for enrichment of X cells in culture. These experiments indicated that X cells rapidly kill senescent cells. Based on these promising initial results, Sharma and coworkers are now further assessing the therapeutic potential of this sub- population of T cells, as they appear to be highly selective in eliminating senescent cells in a substantially shorter time than has been reported by others or observed in their own prior work with NK cells.

Engineering New Mitochondrial Genes to Restore Mitochondrial Function

The MitoSENS lab at SENS Research Foundation, led by Dr. Amutha Boominathan, is working to develop rejuvenation biotechnologies to repair or obviate the accumulation of mitochondrial DNA (mtDNA) mutations with age. Their principal focus is allotopic expression (AE), in which copies of the protein-encoding mtDNA genes are placed in the nucleus, with suitable modifications to allow them to be expressed in the nucleus and translated in the cytosol, following which they must be imported into the mitochondria. There, these gene copies can incorporate into the relevant electron transport chain complexes and contribute to sustaining oxidative phosphorylation. This would allow mitochondria to continue producing ATP, irrespective of the accumulation of particular mtDNA mutations.

Boominathan and colleagues implemented that strategy in the past to synthesize 2 versions of the 13 mtDNA genes: a) the minimally recoded version that is absolutely required for productive protein translation in the cytosol and b) the codon-optimized version, synchronizing the codon usage in these genes to the mammalian nuclear code. They were able to successfully demonstrate robust transient protein production and mitochondrial association for all the 13 mtDNA genes using the codon-optimized gene expression constructs. Cytosolic protein expression under transient expression was substantially higher for the codon-optimized than for minimally-recoded genes, and similarly for steady-state mRNA levels under stable selection. Eight of the re-engineered genes retained expression and targeting to the organelle after stable selection. Building on these early observations, the team validated the utility of these codon-optimized mtDNA gene constructs for additional mitochondrial protein targets that did not work in the past.

The mitochondrial DNA deletions that accumulate in aging cells have a strong selection advantage, amplifying within post-mitotic cells to the point of homoplasmy. The MitoSENS team is exploring a strategy to address this issue by transferring exogenous, viable mitochondria modified for sustained retention and for therapeutic activity. While mitochondrial transplantation is already being investigated by several groups and companies as a therapeutic intervention strategy, Dr. Boominathan's team is advancing an improvement on this strategy using mitochondria with genomes engineered for dominance over the native genotype.

Target Prioritization of Extracellular Matrix Aging

As we age, changes occur not only in the cells within the extracellular matrix (ECM), but importantly also in the composition and chemistry of the ECM. Many of the characteristic physical changes that we associate with ageing, such as the changes in skin appearance or the decrease in flexibility of joints, are specifically the result of changes in the structure and composition of the ECM. Two important components of the ECM are elastin and collagen; indeed, collagen is estimated to account for about 30% of the protein in the body. The Clarke lab is investigating age-related changes in the chemical structure of elastin and collagen and how these changes impact the mechanical behavior of the tissues.

Prior to Clark's investigations, the general consensus in the literature was that tendon increases in stiffness with age and that this was due to an increase in crosslinking between collagen molecules. His group has instead found was that it is not possible to say that tendon gets stiffer with age, particularly when comparing mature to genuinely aged animal tissue. Instead, Clark and colleagues report an increase in the breaking strain, a decrease in the ability to absorb stress, and an increase in the fragility (chance of rupture) with age. This is clearly a more refined and complex description of the physical properties, and accords better with the orthopedic vulnerabilities of aging human tissues.

Clarke's research has also revealed an increase in irreversible crosslinks in the tendon with age, which increase the force required to break a tendon. This increase occurs even as the tendon gradually becomes depleted of reversible crosslinks that allow the tendon to adapt to and absorb force. Understanding how each of these different crosslinks affect the mechanical properties of a tissue and how they change in number with age will enable more targeted strategies for rejuvenation biotechnologies. Based their findings, Clarke and colleagues predict that to rejuvenate youthful tendon function would entail decreasing the number of irreversible crosslinks while greatly increasing the reversible crosslinks. Conceptually, this could be achieved through various means, some of which might not involve directly targeting the crosslinks themselves, but instead cell therapy or other approaches that rejuvenate the behavior of the cells that turn over the ECM. In principle, an unbalanced approach based exclusively on breaking a subset of crosslinks might improve some aspects of tissue function but also cause structural problems.

Lipofuscin Degradation by Bacterial Hydrolases

According to the "garbage catastrophe theory of aging", the accumulation of lipofuscin aggregates limits the remaining life span of the organism by disturbing lysosomal function and inducing cell death. While humans have no enzymes capable of breaking down lipofuscin, microorganisms possess a wide array of enzymes that allow the degradation of any conceivable molecule formed in nature. Thus, the LysoSENS strategy seeks to identify microbes that are able to degrade lipofuscin via specific hydrolases as lead candidates for potential longevity therapeutics. To pursue this goal, the Grune lab will use authentic lipofuscin derived from human cardiac tissue.

Dr. Grune and colleagues extracted microorganisms from different soil samples collected at a residential yard, a forest, a compost heap, and a riverbed. The team used these extracts to select lipofuscin-degrading bacteria by growing cultures on isolated lipofuscin as the only energy, carbon, and sulphur source. Following 20 sets of sub-culture passaging, bacterial mixtures growing on human tissue-derived lipofuscin were extracted, and 12 bacterial strains were isolated. These strains and their specific enzymes will be isolated and further investigated. It bears noting that it is not expected that these bacterial enzymes will prove to be proteases, but hydrolases able to degrade complex crosslinks between proteins. This fact will complicate the identification of lead candidates, but on the other hand, such structures will be unique to lipofuscin and able to function in mammalian cells (after suitable modification) without the danger of digesting functional proteins. A future task will be the targeting of the identified hydrolases towards the lysosomal compartment.

SenoStem: Combinatorial Rejuvenation Biotechnologies

Age-related disease and disability results from the complex interaction of multiple forms of cellular and molecular aging damage. Prominent examples of this damage are the loss of stem cells and the accumulation of senescent cells. Senescent cells propagate damage and impose systemic metabolic derangement through the secretion of a senescence-associated secretory profile (SASP). The SenoStem project at SENS Research Foundation is testing the hypothesis that combination therapy using senolytics and stem cell transplantation will have a synergistic beneficial effect on aging mice and might be able to further improve health and lifespan - literally a remove-and-replace strategy. This approach builds toward SRF's larger long-term goal to develop synergistic combinatorial rejuvenation biotechnology approaches.

Microglia as a Vehicle for Brain Rejuvenation

With SRF funding, the Hébert team has developed a protocol for using microglia as a delivery system for biologics over wide areas of the adult brain. With this protocol, endogenous microglia are replaced with transplanted microglia after a single superficial cell injection. Microglia are migratorily more active compared to neuronal progenitors and more easily spread throughout the brain. In addition to therapeutic proteins, this system can be used to deliver new neurons to all areas of the brain to counteract neuronal loss with age. The transplanted microglia can be engineered to produce a secreted biologic, or engineered to be reprogrammed to new neurons. In both cases, normal microglia density is innately re-established, minimizing any effect of transient microglia depletion while providing novel therapeutic support to brain function.

Identification and Targeting of Noncanonical Death Resistant Cells

It is well established that senescent cells (SCs) can result from a number of stressors, including replicative stress, telomere erosion and damage, and oncogene expression. They are also induced as part of tissue remodeling in wound healing and development. More recently, it was discovered that SCs can spread the senescent phenotype to other cells in the body. Characterization of secondary SCs and differentiating their biology and vulnerabilities from those of primary SCs is thus critical to developing longevity therapeutics targeting the full spectrum of senescence in aging, and is the central focus of Dr. Admasu's work at SENS Research Foundation. With his SRF colleagues, Dr. Adamasu developed a novel protocol to overcome one major roadblock in this endeavor, which has allowed him to make new insights into secondary senescence and identify a highly significant therapeutic target for senolytic drugs with broad senolytic activity against both primary and secondary SCs.

Researchers here provide evidence for the raised blood pressure of hypertension to accelerate the progression of osteoporosis, the loss of bone density characteristic of old age, leading to an earlier onset of the condition. They speculate that inflammation is the mechanism of interest, based on the differences in outcome following induced hypertension in old mice, already suffering the inflammation of aging, versus induced hypertension in young mice. There are already many good reasons to work to minimize both chronic inflammation and any increase in blood pressure with age; more evidence for just how bad these aspects of aging are just reinforces that call to action.

Researchers compared young mice with induced hypertension to older mice without hypertension to assess the potential relationship of hypertension to bone aging. A group of 12 young mice (4 months old) were given angiotensin II for six weeks, a hormone that leads to high blood pressure. A group of 11 older mice (16 months old) also received of angiotensin II for six weeks. Two control groups of 13 young mice and 9 old mice received a buffer solution that did not include angiotensin II, and these mice did not develop high blood pressure.

After six weeks, researchers analyzed the bones of mice from all four groups using micro-computed tomography. When compared to the young mice without hypertension, the young mice with induced hypertension had a significant 24% reduction in bone volume fraction, an 18% reduction in the thickness of the sponge-like trabecular bone located at the end of long bones, such as femurs and the spinal column, and a 34% reduction in estimated failure force, which is the ability of bones to withstand different types of force.

In contrast, the older mice who were given the angiotensin-II infusion did not exhibit similar bone loss. During the study, however, the old mice, with or without high blood pressure, exhibited a reduced bone quality similar to that of the hypertensive young mice. To assess the impact of inflammation on bone health of the mice, researchers analyzed the bone marrow using flow cytometry. This tool allowed researchers to identify individual cells and to sort out specific immune cells. In the hypertensive young mice, they found an increase in the number of inflammatory signaling molecules, indicating an increase in inflammation in the bones when compared to the young mice that did not receive angiotensin II.

"This increase in active immune cells tells us that the older mice are more inflamed overall, and that a continued state of inflammation, whether they had high blood pressure or not, may have an impact on bone health. It appeared that high blood pressure was adjusting the bone remodeling process toward bone loss, rather than bone gain or bone equilibrium, in the hypertensive young mice. As a result, bones will be weaker, leading to an increased risk for osteoporosis and fragility fracture. In humans, this might mean that we should screen for osteoporosis in people with high blood pressure."

Link: https://newsroom.heart.org/news/high-blood-pressure-may-accelerate-bone-aging

Measures of aging tend to correlate with one another in any given study population. If someone is more affected by aging, then all of his or her physiology tends to be more functionally impacted. Thus it isn't always clear as to what can be learned from epidemiology of the sort noted here. One has to look closely at the details. Nonetheless, researchers here show that allostatic load over the course of aging correlates with the risk of suffering hearing loss. Allostatic load is a measure of stress and divergence from optimal function in the systems of the body, more or less, as determined by a range of biomarkers relating to the endocrine system, cardiovascular system, immune system, and metabolism.

Allostatic load is a cumulative measure of the physiological stressors to the body throughout the life course, reflected by damage to multiple biological systems over time. An advantage using allostatic load in predicting health outcomes, as opposed to the use of single biomarkers, is that it captures the effects of stressors on several biological systems simultaneously. Several conditions implicated with high allostatic load have associations with hearing impairment, including diabetes, obesity, sub-clinical atherosclerosis, and vascular degeneration, as have behaviours including poor diet and smoking. However, little work has been carried out into the association between inflammatory biomarkers and hearing impairment, and none (to our knowledge) on the association with allostatic load.

Data were taken from the English Longitudinal Study of Ageing (ELSA), a nationally representative study of people aged 50+ living in England over 3 time points between 2008 and 2014. Allostatic load score was comprised of thirteen different measures available at baseline and 4 years post-baseline (high-density lipoprotein/total cholesterol, triglyceride, fibrinogen, haemoglobin A1c, C-reactive protein, insulin-like growth factor 1 (IGF-1), systolic and diastolic blood pressure, mean arterial pressure, resting pulse rate, peak expiratory flow, BMI and waist circumference), measured using clinical cut-off points for normal biomarker parameters. Hearing acuity was measured with a simple handheld tone-producing device at follow-up 7 years post-baseline, while self-reported hearing impairment was measured at time point.

We included samples of 4,373 and 4,430 individuals for the cross-sectional and longitudinal analysis, respectively. In the cross-sectional model high allostatic load was associated both self-reported (odds ratio, OR = 1.08) and objective hearing loss (OR = 1.10) adjusting for age and sex. In longitudinal modelling, high allostatic load was associated with both audiometric (OR = 1.11) and self-reported hearing impairment (OR = 1.08) adjusting for age and sex. Thus prolonged high allostatic load was associated with risk of hearing impairment.

Link: https://doi.org/10.1016/j.bbih.2022.100496

Atherosclerosis, the condition that kills upwards of a quarter of humanity at the present time, is a failure of cholesterol transport. Cholesterol is made in the liver and transported out into the body in the bloodstream, attached to LDL particles. All cells need cholesterol. Some of this LDL-cholesterol ends up stuck in blood vessel walls in too large an amount, or oxidized into toxic forms, aggravating the blood vessel tissues. Macrophage cells ingest this excess cholesterol and then attach it to HDL particles that return the cholesterol to the liver for excretion. The latter part of this complicated system is called reverse cholesterol transport, and works well in youth.

The point of failure that emerges with advancing age is that macrophages become less able to perform reverse cholesterol transport, allowing blood vessel walls to reach a tipping point of excess or altered cholesterol deposition. These regions become too much for macrophages to handle, but they keep on trying - arriving, becoming inflammatory, and dying while drawing in more cells to try to help. It is a feedback loop in which diseased region of blood vessel wall becomes a toxic cell graveyard, growing to form fatty lesions that narrow and weaken blood vessels. Eventually something ruptures, leading to a stroke or heart attack.

Finding ways to enhance the operation of reverse cholesterol transport has been the subject of research programs for some decades. Increased expression of proteins in macrophages involved in cholesterol ingestion, or transfer to HDL particles, or creation of HDL particles have all been tried, as well as the introduction of more HDL particles directly. All of this works at least modestly well to reverse the progression of atherosclerosis in mice, but the few of these approaches tried in humans have failed. It seems that the balance of factors determining the tipping point of fatty lesion growth versus reversal is quite different in the two species.

HDL, cholesterol efflux, and ABCA1: Free from good and evil dualism

Loss-of-function mutations in ABCA1 cause Tangier disease. The phenotype of their markedly reduced or loss of blood high-density lipoprotein (HDL) cholesterol, as well as examination of ATP-binding cassette transporter A1 (ABCA1)-deficient mice, proved that ABCA1 is a key player in HDL production. The ABCA1-mediated cholesterol efflux is the first step in the reverse cholesterol transport system and understanding the regulation of its expression was expected to lead to the development of anti-atherosclerotic drugs. However, from the viewpoint of intracellular cholesterol homeostasis, it is difficult to say that simple activation of ABCA1 or promotion of cholesterol efflux is a good strategy.

This review discusses the possibilities and limitations of strategies to increase HDL, activate cholesterol efflux, and enhance ABCA1 expression, centered on the strict regulatory mechanisms of intracellular cholesterol. Since the benefits of increasing blood levels of HDL-C, once called "good cholesterol," have been doubted, attention has turned to cholesterol efflux enhancement and ABCA1 activation as the next "good" thing. However, there is no evidence that HDL-increasing drugs by enhancing ABCA1 expression prevent atherosclerotic cardiovascular disease in humans.

Essentially, HDL, cholesterol efflux, and ABCA1, may be systems for transporting lipophilic "poisons" including cholesterol to the liver which is the main detoxification organ. In particular, ABCA1 has been reported to not only excrete cholesterol and phospholipids, but also to temporarily reserve the outer leaflet of the plasma membrane and to flop excess cholesterol from the inner to the outer leaflet of the plasma membrane. As these findings show, the organism has a very sophisticated system, so a rough treatment that simply increases blood HDL-C levels, cholesterol efflux, or ABCA1 expression is not likely to be successful. On the other hand, in situations where intracellular cholesterol homeostasis is disrupted by inflammation, aging, or metabolic abnormalities, a strategy that restores reduced ABCA1 expression and cholesterol efflux in a timely and localized manner may be useful.

Researchers here make the point that the aging of the immune system into a lesser capacity to defend against pathogens and senescent and potentially cancerous cells, the state known as immunosenescence, is both complex in its myriad changes, and probably includes some beneficial adaptations that help to modestly reduce the negative impact of aging. That is interesting to note, in those details that are known and hypothesized, but it doesn't really change the primary strategy for immune rejuvenation: restore active thymic tissue to enable production of new T cells; repair the hematopoietic stem cell populations and their niches to ensure creation of immune cells; clear out malfunctioning, senescent, and exhausted populations of immune cell.

For a long time, immunosenescence has been considered harmful. However, it is noteworthy that immunosenescence is a remodeling and retuning process with increase in some new functions rather than complete decline of immune function. Serum levels of IgG and IgA are increased with age, which is conducive to protecting against viral and bacterial infections effectively in older people. Although the generation of naive T cells and naive B cells continues to decline, the adaptive immune system adjusts to age-related changes and protects the body from most pathogens. Only later in life does the immune function decline gradually, which increases morbidity and mortality in the elderly.

But not all older people suffer from age-related diseases, centenarians can delay the aging process and live up to the limits of human life. Centenarians have a large quantity of anti-inflammatory molecules, such as TGF-β1, IL-10 and IL-1 receptor antagonist (IL-1RA), to counterbalance increased inflammatory molecules, such as IL-1β, IL-6, TNF-α, IL-8, C-reactive protein (CRP) and CXCL9, achieving a dynamic balance between pro-inflammatory and anti-inflammatory levels. In addition, telomere length and telomerase activity are higher in centenarians.

There are currently several strategies to deal with senescence and senescent cells. First of all, rejuvenation of old hematopoietic stem cells (HSCs) may be an effective therapeutic strategy to restore the balance between myeloid and lymphatic systems and the numbers of T and B cells. The involution of the thymus is one of the main features of aging, which might lead to the decrease of T cells, so restoring the structure and function of the aging thymus could reverse immunosenescence. Thymo-stimulatory property of IL-10, leptin, keratinocyte growth factor (KGF) and thymic stromal lymphopoietin (TSLP) may contribute to immune reconstitution of the elderly. IL-7 is a crucial cytokine for T cell development, so IL-7 treatment promotes the expansion of peripheral T cells and the diversity of T cell receptors. Telomerase is a significant component for T cell development, so upregulation of telomerase expression enhances T cell immune response and prolongs lifespan.

Link: https://doi.org/10.3389/fimmu.2022.942796

This open access paper discusses the evidence for viral infections to increase the burden of cellular senescence, specifically in the context of atherosclerosis and immunosenescence in aging. Viral infection is thought to contribute to both issues, and from what is known of the role of increased numbers of senescent cells in aging, it is possible that increased senescent cells numbers is a significant mechanism. Certainly, we should hope to see researchers establish that a great deal of degenerative aging, accelerated by viral infection or otherwise, can be blamed on the unwanted activities of lingering senescent cells. The development of senolytic therapies to remove senescent cells is a going concern, and the option to live a life without senescent cell accumulation lies in the near future.

The immune system is a versatile and dynamic body organ which offers survival and endurance of human beings in their hostile living environment. However, similar to other cells, immune cells are hijacked by senescence. The ageing immune cells lose their beneficial functions but continue to produce inflammatory mediators which draw other immune and non-immune cells to the senescence loop. Immunosenescence has been shown to be associated with different pathological conditions and diseases, among which atherosclerosis has recently come to light. There are common drivers of both immunosenescence and atherosclerosis; e.g. inflammation, reactive oxygen species (ROS), chronic viral infections, genomic damage, oxidized-LDL, hypertension, cigarette smoke, hyperglycaemia, and mitochondrial failure. Chronic viral infections induce inflammaging, sustained cytokine signaling, reactive oxygen species generation and DNA damage which are associated with atherogenesis.

Recent data indicate that chronic viral infections manipulate the pathways involved in replicative senescence (RS), oncogene-induced senescence (OIS), and possibly genotoxicity-induced senescence (GIS) in immune and non-immune cells. The senescence pathways induced by infectious agents are shared with other senescence inducing stimuli. The induction of senescence in immune cells is more robust in chronic viral infections due to direct stimulation of the immune system by viral antigens. From early childhood, the immune cells of human-beings are challenged with viral infections and fortunately enough, in most cases the virus is contained and even eradicated by immune system. However, continuous encounter with viruses and especially establishment of chronic viral infections in the body results in a state of more inflammatory and less protective immune response.

In atherosclerosis, as one of the old inflammatory conditions and the mother of cardiovascular disease and stroke, immunosenescence is induced both in immune and non-immune cells. Therefore, chronic viral infections, through induction of immunosenescence, may directly or indirectly play a role in development or progression of atherosclerosis. The premature ageing as a result of viral co-infections may also accelerate immunosenescence and inflammatory diseases.

Link: https://doi.org/10.3389/fimmu.2022.945016

This post reports on the outcome of a self-experiment with three of the Khavinson peptides (epitalon, thymogen, and vilon) and the supplement melatonin in an attempt to produce thymic regrowth. There is evidence in animals for some of these peptides to produce thymic regrowth, as well as evidence for some of these peptides (thymogen particularly) to reduce mortality in old human patients. All of this comes from the Russian research community, however, and original sources are not all that accessible. Certainly, no-one has checked to see whether the thymus is regrown in humans following treatment with these peptides.

Thymic regrowth is a desirable goal, a way to restore immune function in older people who have lost some, most, or all of the active thymic tissue needed for the production of naive T cells. The loss of this supply of new T cells is an important component in the age-related decline of the immune system. Thus it seems worth the effort to gather data on this front. Last year I posted a study outline for a self-experiment with Khavinson peptides, and this year I have a report from one adventurous self-experimenter, using a more aggressive version of that study protocol.

Study Outline

Based on the published outline, this was a nine-month study. On each of the first ten days of every month, a mix of 10mg epitalon, 10mg thymogen, and 10mg vilon in was injected subcutaneously. This was split between two injections 12 hours apart, morning and evening.

This study included the use of a high dose (20mg daily) of melatonin in addition to Khavinson peptides, on the basis that there is good safety data for melatonin, and a single study has shown an increase in thymic tissue resulting from supplementation with melatonin at the equivalent dose in mice. This is an entirely speculative addition, but years of data on melatonin use suggests no meaningful downside at this dose. The 20mg of melatonin were taken orally in the evening, which differs from the mouse study, in which melatonin was supplied in drinking water.

A CT scan of the thymus was taken before and after the study. A complete blood count assay was used to assess lymphocyte:monocyte ratio before and after the study. That is a number that becomes lower with age, and which should increase if the thymus is more rather than less active. Ideally an assay to measure recent thymic emigrants would have been included, but was not. Recent thymic emigrants are T cells recently emerged from the thymus, within the past few weeks.

Subject Details

The subject for the self-experiment was in the 45-55 age range, healthy and without chronic conditions, with a BMI of ~22 throughout the duration of the experiment. Diet and exercise were described as "relatively consistent" across the study duration. I feel that one should always be relatively skeptical of that sort of claim, however, no matter how formal or informal the study.

Results

CT images of the thymus showed a visible reduction in active tissue across the nine months of the study, the opposite of the hoped outcome. In the image below, paired cross-sections through the chest are shown, before on the left, after on the right. For guidance on reading CT scans of the thymus, refer to "Normal Thymus in Adults: Appearance on CT and Associations with Age, Sex, BMI and Smoking". In a cross-section of the chest, as below, and as in the examples given in that paper, the thymus is the triangular patchy grey structure closer to the top of the image, immediately below the sternum (white). Areas of fat will appear dark in the range chosen here, and thus a more atrophied thymus, in which more active tissue is replaced with fat, will appear darker. By late life, the thymus is entirely dark, fatty.

There was no meaningful change in lymphocyte:monocyte ratio. Over four years of complete blood count data prior to this study, leukocyte:monocyte ratio varied from 4.4 to 6.5, with no particular trend. In three measures after the study, leukocyte:monocyte ratio was 5.8, 6.0, and 4.0.

Conclusion

Use of the Khavinson peptides and melatonin in combination in this way, at this dose, negatively impacts the thymus, producing a reduction in active tissue and increase in atrophy to fatty tissue. The degree to which this atrophy occurred is greater than one would expect to take place over nine months of aging at this stage of life.

Why did this outcome occur, given the animal studies showing thymic regrowth, and the studies showing reduced later life mortality following use of thymogen? We can only speculate. Firstly, the dose makes the poison, and the dosing here may have been too high, too frequent. In one of the human studies, testing thymogen only, dosing for ten days occurred only one every six months, rather than monthly as here. Secondly, it may be that these peptides are pleiotropic in their effect on the thymus, and only beneficial after the thymus is very atrophied. Thirdly, it may be that in humans any benefit to the use of Khavinson peptides arises from increased peripheral T cell replication in useful populations, such as naive T cells. This could be beneficial on balance in late life, allowing greater resistance to infection, even if it pushes the patient further towards the accumulation of senescent and exhausted T cells. Lastly, the existing study data for Khavinson peptides relevant to this exercise may simply be dubious, wrong, or otherwise bad.

Regular moderate exercise is well known and well established to be beneficial to long term health in many ways. Lack of exercise is actively harmful to long term health, on the other hand. Researchers here add another correlation between exercise and brain health, in that the size of functional areas of the brain is larger in those who do exercise, providing more of a protective buffer against the onset of neurodegeneration and cognitive decline.

Which of the numerous mechanisms connecting exercise and brain function are most important in this effect remains an open question, though the data in this study suggests that increased blood flow is the dominant aspect. Exercise does boost blood flow to the brain, but also upregulates BDNF expression, which in turn increases neurogenesis, the creation of new neurons. Balancing the relative importance of these and other mechanisms is challenging given the complexity of the aging, biology, and the brain.

Researchers examined data on exercise and the brain for 2,550 participants of the Rhineland Study. "We were able to show that physical activity had a noticeable effect on almost all brain regions investigated. Generally, we can say that the higher and more intense the physical activity, the larger the brain regions were, either with regard to volume or cortical thickness. In particular, we observed this in the hippocampus, which is considered the control center of memory. Larger brain volumes provide better protection against neurodegeneration than smaller ones." However, the dimensions of the brain regions do not increase linearly with physical activity. The research team found the largest, almost sudden volume increase when comparing inactive and only moderately physically active study participants - this was particularly evident in older individuals over the age of 70.

"In principle, this is very good news - especially for those who are reluctant to exercise. Our study results indicate that even small behavioral changes, such as walking 15 minutes a day or taking the stairs instead of the elevator, may have a substantial positive effect on the brain and potentially counteract age-related loss of brain matter and the development of neurodegenerative diseases. In particular, older adults can already profit from modest increases of low intensity physical activity." Young and somewhat athletic subjects who usually engaged in moderate to intense physical activity also had relatively high brain volumes. However, in even more active subjects, these brain regions were slightly larger. Also here it showed: the more active, the greater the effect, although at high levels of physical activity, the beneficial effects tended to level off.

To characterize the brain regions that benefited most from physical activity, the research team searched databases for genes that are particularly active in these brain areas. "Mainly, these were genes that are essential for the functioning of mitochondria, the power plants of our cells." This means that there are particularly large numbers of mitochondria in these brain regions. Mitochondria provide our body with energy, for which they need a lot of oxygen. "Compared to other brain regions, this requires increased blood flow. This is ensured particularly well during physical activity, which could explain why these brain regions benefit from exercise."

Link: https://www.dzne.de/en/news/press-releases/press/the-brain-already-benefits-from-moderate-physical-activity/

Looking at T cells, researchers here note correlated age-related alterations in cell stiffness and reduced capability for cell migration, which maybe involved in the declining capabilities of the immune system, the onset of immunosenescence. Many aspects of cell behavior change with age, as epigenetic changes characteristic of aging reshape gene expression. At this point in the development of aging research as a field, cataloging all of these changes should be a lower priority than working on ways to address causes of aging. Nonetheless, a great deal of aging research remains devoted to observing aging, in increasingly fine detail, rather than doing something about it.

Age-associated changes in T-cell function play a central role in immunosenescence. The role of aging in the decreased T-cell repertoire, primarily because of thymic involution, has been extensively studied. However, increasing evidence indicates that aging also modulates the mechanical properties of cells and the internal ordering of diverse cell components. Cellular functions are generally dictated by the biophysical phenotype of cells, which itself is also tightly regulated at the molecular level. Based on previous evidence suggesting that the relative nuclear size contributes to variations of T-cell stiffness, here we examined whether age-associated changes in T-cell migration are dictated by biophysical parameters, in part through nuclear cytoskeleton organization and cell deformability.

In this study, we first performed longitudinal analyses of a repertoire of 111 functional, biophysical, and biomolecular features of the nucleus and cytoskeleton of mice CD4+ and CD8+ T cells, in both naive and memory state. Focusing on the pairwise correlations, we found that age-related changes in nuclear architecture and internal ordering were correlated with T-cell stiffening and declined interstitial migration. A similarity analysis confirmed that cell-to-cell variation was a direct result of the aging process and we applied regression models to identify biomarkers that can accurately estimate individuals' age. Finally, we propose a biophysical model for a comprehensive understanding of the results: aging involves an evolution of the relative nuclear size, in part through DNA-hypomethylation and nuclear lamin B1, which implies an increased cell stiffness, thus inducing a decline in cell migration.

Link: https://doi.org/10.1111/imm.13559

Exercise modestly slows aging. In humans epidemiological data only allows for the establishment of correlation between physical activity and measures of aging and mortality. Animal data, however, shows that regular exercise modestly slows aging to an extent that improves long-term health, increasing healthspan without extending maximum life span. It is not as impressive as the effects of calorie restriction on life span, but the effects on health along the way are not all that dissimilar in nature.

In today's open access paper, the authors present a view of exercise and aging that is essentially hormetic in nature. They suggest that exercise slows aging because the short-term stresses generated by exercise overlap to some degree with the long-term stresses generated by the aging of tissues, and adaptation to the former grants greater resistance to the latter. This really need not be the case for exercise to slow aging, however. All that is needed is for the stresses of exercise to trigger generally beneficial responses. Or for exercise to correlate with reduced visceral fat burden, or reduced frailty, or reduced overall calorie intake.

Hormesis is used to describe situations in which mild stress and damage can produce a net gain in function by spurring a lasting increase in maintenance, repair, and defensive activities among the cells making up our tissues. Many forms of stress have this effect, such as reduced nutrient intake, exposure to toxins, heat, cold, and so forth. Exercise evidently stresses tissues via increased energy demands and pushes mitochondria to greater activity, generating oxidative stress as a side-effect, which cells must respond to with greater maintenance, but it also produces a range of other stress mechanisms, such as via inflammatory signaling.

Exercise as an Aging Mimetic: A New Perspective on the Mechanisms Behind Exercise as Preventive Medicine Against Age-Related Chronic Disease

Preventive lifestyle strategies such as exercise have emerged as potent, cost-effective means of reducing chronic disease risk. Exercise has a critical role in disease prevention and has been proposed as a form of "medicine". The protective effects of exercise on chronic disease risk are ultimately accumulated over time through physiological adaptations to the stress of exercise. Acute exercise causes widespread physiological disruptions that require a complex, integrated response from the major physiological systems (autonomic, cardiovascular, metabolic, musculoskeletal, etc.) to meet the substantial requirements of human locomotion. Repeated exposure to the physiological disruptions incurred by acute exercise (through exercise training) stimulate physiological adaptations that act to attenuate stress during subsequent exercise bouts. These exercise adaptations provide the foundation through which individuals can adapt and improve their ability to perform physical work (e.g., increase muscular power, endurance, aerobic capacity, etc.) and also prevent development of age-related chronic disease.

Thus, physiologic adaptations to exercise are the latent mechanisms through which exercise acts as medicine and reduces chronic disease risk. Despite seminal work that has identified several key mechanisms underlying the protective effects of exercise, there has yet to be an overarching hypothesis that explains broadly why or how it is that exercise protects against age-related chronic disease. We posit that exercise prevents age-related chronic disease because it acutely elicits physiological responses that mimic physiological changes seen with aging, the greatest contributing risk factor to all chronic disease. Thus, we propose the hypothesis that exercise is "medicine" that protects against age-related chronic diseases because exercise can effectively simulate "aging."

Acute exercise transiently disrupts cardiovascular, musculoskeletal, and brain function and triggers a substantial inflammatory response in a manner that mimics aging/age-related chronic disease. Data indicate that select acute exercise responses may be similar in magnitude to changes seen with an added 10-50 years of aging. The initial insult of the age-mimicking effects of exercise induces beneficial adaptations that serve to attenuate disruption to successive "aging" stimuli (i.e., exercise). Ultimately, these exercise-induced adaptations reduce the subsequent physiological stress incurred from aging and protect against age-related chronic disease. To further examine this hypothesis, future work should more intricately describe the physiological signature of different types/intensities of acute exercise in order to better predict the subsequent adaptation and chronic disease prevention with exercise training in healthy and at-risk populations.

An interesting set of connections are made in this paper, in which researchers show that favorable changes to the gut microbiome produced by the practice of calorie restriction lead to greater butyrate production, generally thought to be a positive change, as butyrate can improve neurogenesis, among other beneficial effects. However butyrate supplementation also suppresses the generation of new immune cells, an outcome also known to be a feature of calorie restriction and fasting. Whether this suppression is outright harmful is an open question; certainly fasting has been shown to help clear damaged immune cells following cancer therapy, to pick one example, and repeated reductions in circulating immune cells may be beneficial in the long term in healthy individuals via partial clearance of problem immune cell populations.

Dietary restriction (DR) is one of the most robust interventions shown to extend health-span and remains on the forefront of anti-aging intervention studies, though conflicting results have been shown on its effect on lifespan both in rodents and primates. The severe inhibitory effects on the lymphoid lineage by DR remains one of its major negative downsides which reduces its overall beneficial effects on organismal health. Yet, the underlying mechanism of how DR suppresses the lymphoid system remains to be explored.

Here, we show that antibiotic ablation of gut microbiota significantly rescued the inhibition of lymphopoiesis by DR. Interestingly, glycolysis in lymphocytes was significantly down-regulated in DR mice and pharmacological inhibition of glycolysis reverted this rescue effect of lymphopoiesis in DR mice with ablated gut microbiota. Furthermore, DR remarkably reconstructed gut microbiota with a significant increase in butyrate-producing bacterial taxa and in expression of But, a key gene involved in butyrate synthesis. Moreover, supplemental butyrate feeding in AL mice suppressed glycolysis in lymphoid cells and mimicked the inhibition of lymphopoiesis in AL mice.

Together, our study reveals that gut microbiota mediates the inhibition on lymphopoiesis via down-regulation of glycolysis under DR conditions, which is associated with increased butyrate-synthesis. Our study uncovered a candidate that could potentially be targeted for ameliorating the negative effects of DR on lymphopoiesis, and therefore may have important implications for the wider application of DR and promoting healthy aging.

Link: https://doi.org/10.1080/19490976.2022.2117509

The goal of cancer therapies is to kill cancerous cells or force those cells into the state of senescence, to shut down their uncontrolled replication. Chemotherapy and radiotherapy do harm non-cancerous cells as well, however, and can create further senescent cells in this way. It is thought that a substantial fraction of the increased mortality and risk of age-related disease seen in cancer survivors is due to the increased burden of senescent cells produced by the treatment of cancer. That is obviously preferential to death by cancer, but it is a concern, with a significant negative impact to remaining life expectancy. With the advent of senolytic therapies capable of selectively destroying senescent cells, it seems likely that this further harm inflicted on cancer patients can be ameliorated, however.

Cellular senescence is an inherent and virtually unavoidable consequence of treatment in patients with cancer. Cancer cell senescence mainly refers to surviving cancer cells that enter stable and durable cell cycle arrest, but can also be triggered in non-malignant cells in various organ systems across the body. Given the complex cell-extrinsic effects that senescent cells can exert in their surroundings, and the fundamental cell-intrinsic rewiring that profoundly alters cellular functionality and can account for stem-like reprogramming, the consequences of senescence are far more complex than those of apoptosis. Thus, managing residual senescent cancer cells as well as the consequences of senescence of non-malignant cells in patients receiving pro-senescent antitumour therapies is a clinical challenge.

Weighing the balance between the 'bright' and 'dark' sides of senescence is difficult, given that tumour-suppressive and tumour-promoting effects linked to senescent cancer cells can coexist in the same patient. Specifically, neither a dependable quantitative assessment of the different contributions that such effects could have on long-term outcome nor marker-based detection and selective targeting of less-desirable senescent cell populations is currently feasible in the clinic. Pharmacological suppression or modulation of the senescence-associated secretory phenotype (SASP) might work to a certain extent, but is unlikely to robustly change tumour fate. By and large, premature cancer cell senescence has acutely beneficial but chronically detrimental ramifications.

Most cytotoxic and cytostatic cancer treatments currently available induce senescence, whether intended or not, as a collateral effect in a certain proportion of the surviving cancer cell population. Thus far, senolysis (that is, senescence-related opportunities to eliminate drug-exposed malignant cells that failed to undergo apoptotic cell death in the first place but contributed to the initial treatment response via proliferative arrest) seems to be the preferred strategy because it seems the only definitive option towards tumour eradication. Although numerous promising candidate senolytics are being identified, some of which have entered clinical trials, prospective results of large-cohort oncology trials remain to be reported. Such studies should provide insights as to whether protection from post-senescent cancer relapse and concurrent elimination of organ function-disabling senescent cells in non-malignant tissues can be established as key objectives of therapeutic senolytic approaches in patients with cancer.

Link: https://doi.org/10.1038/s41571-022-00668-4

Funding for aging research and the development of therapies to treat aging as a medical condition used to be hard to come by. It was a fringe field of medicine. But slow years of bootstrapping incremental progress - hard work, patient advocacy, and philanthropy - eventually led to technology demonstrations, such as the rejuvenation of mice with senolytic therapies, that convinced the first large sources of funding to enter the field. That produced further progress, and the start of a longevity industry, enough to convince deeper pockets to participate. That in turn made slowing and reversing aging a viable investment for a growing number of sizable sources of wealth.

History teaches to be cautious about newly announced large investments in the field of aging and longevity, however. Calico launched with much fanfare, hundreds of millions of Google's dollars devoted to aging research, but a decade on it seems clear that little will result from this initiative. We might look at Altos Labs, recently launched with $3 billion in funding, as a newer Calico, but with the narrow goal of achieving human rejuvenation via cell reprogramming technologies. Will a narrow focus allow success where a broad focus leads to an organization losing its way? Only time will tell.

So to today's topic, the Hevolution Foundation, which has broadly announced intentions to funnel very large amounts of Saudia Arabian sovereign wealth into aging research and the longevity industry. The organization has started slowly, but we can ask the same sorts of questions as of other large intiatives: will meaningful projects be funded? Much of the longevity industry, and much of aging research, is focused on goals that cannot and will not make much of a difference to the healthy human life span, such as the prevalent calorie restriction mimetics, supplements, and approaches to cellular stress response upregulation. Many of the large investment funds have devoted much of their funding to date to aging-branded efforts that are really just business as usual in medicine and biotech, nothing that offers the possibility to significantly change the shape of a human life.

The most important battle today, with regard to human aging, is over steering funding to projects that are more likely rather than less likely to result in significant rejuvenation. Senolytics, not calorie restriction. Partial reprogramming, not more supplements. And so forth. Until the broad scope of aging research and the longevity industry is significantly focused on rejuvenation, it is hard to be more than cautiously optimistic about any new large-scale venture, no matter how good their rhetoric sounds at the outset.

Hevolution CEO on how to spend $1 billion a year on longevity

"First of all, we are very much about extending healthy life, not just lifespan. I think if you ask anybody, with rare exception, they don't want to live longer for the sake of living longer. 'For the benefit of all' means not only being all-inclusive, but how do you democratise these technologies and discoveries? If we can't scale and democratise discoveries, and how to maximise the impact, then we should question ourselves: why are we doing this? Number one, we need to provide and support the development of the scientific field," says Hevolution's CEO Dr Mehmood Khan, who bemoans the huge gap in funding from governments around the world that goes into aging research compared to diseases like cancer, Alzheimer's, and heart disease (most of which are the consequences of aging). There's a log scale, if not two log scales, difference between the funding that goes into understanding how to keep people healthy on a biological level, versus treating the consequences of it. And that gap needs to be filled."

Another challenge that Khan sees is that most of the funding that is currently available for aging research is very much siloed, both within countries but also within disciplines. "One institute will fund the biology, and another will fund clinical research - it is not integrated together, for a whole variety of reasons. And that all needs to change. The irony is that the largest part of the healthcare budget for all developed countries is age-related diseases. So, we're already paying for the consequences of this ... and it's only getting bigger because our populations are aging."

When setting up Hevolution, Khan strongly felt that, to achieve all of this with the right incentives, the organisation had to be a non-profit. "If we were mandated as a for-profit organisation, then it's going to all be about return on investment back to our investors, and funders, which changes the types of decisions you'll make. To avoid this, you have to create a non-profit organisation, where the mission implementation is about funding science, which has no strings attached. We're not looking for an equity stake or anything like that - just fund the science, regardless of geographic location, for the benefit of all."

"Our vision is that we can invest up to a billion dollars a year, but the question now is how do we get there? The rate-limiting step in this is not the ability to invest or provide scientific research funding, but how to do that responsibly, such that the field can absorb it. This field needs to grow, and part of that is creating a pipeline of good scientific ideas, a pipeline of talent, and then pull that through into where venture comes in and build companies and then grow those companies. Some are already along that spectrum, but the funnel is not large enough, the pipeline is not large enough. So we're starting by funding science but we'll also be announcing our first investments very soon." Khan says that Hevolution's research funding and venture capital investment approaches will run in parallel, although how much of that $1 billion budget is allocated to each is not yet determined.

The paper noted here is titled "New Trends in Aging Drug Discovery", but the authors really only discuss the development of senolytics and other classes of treatment that target the burden of senescent cells in aged tissues. Senescent cells are created throughout life, but in youth are cleared quickly by the immune system; with age, the balance between creation and destruction shifts, and the numbers of such cells increase. Lingering senescent cells produce disruptive signaling that changes the behavior of normal cells for the worse and provokes the immune system into chronic inflammation, contributing to age-related disease and mortality.

Research over the past decade has demonstrated that selective elimination of senescent cells (SnCs) extends health and lifespan in animal models and can significantly ameliorate aging-associated diseases; therefore, numerous efforts are invested in the development of senolytics that target molecular pathways underlying senescence to selectively kill SnCs. In this sense, resistance to apoptosis is a key characteristic feature of SnCs and inhibition of pro-survival and anti-apoptotic regulators is the most common strategy for the development of means to remove senescent cells.

The removal or modulation of SnCs by senotherapeutic drugs has become an attractive approach to prevent, delay, and even revert many of the chronic age-associated disorders and to extend healthspan. Senotherapeutic compounds can be divided into senolytics, which selectively promote the death of SnCs or induce senolysis, and senomorphics that suppress markers of senescence, in particular the senescence-associated secretory phenotype (SASP), to cause senostasis and prevent the detrimental cell-extrinsic effects of SnCs. Here we detail the most profoundly characterized small molecules and their mechanism of action in the context of the diseases in which they have been studied.

Aging is commonly regarded as an inevitable part of the life cycle; however, current research suggests that it may not be the inexorable process we consider it at the present moment. Actually, obtained results with different models indicate that (i) cells become senescent as time passes; (ii) SnCs have altered functions, which eventually lead to aging-related diseases; (iii) aged cells are different from young cells and these differences can be exploited for specific targeting; (iv) senescent cell removal or rejuvenation strategies involve improvements in aging-related pathological states; (v) there exist compounds (that may become drugs in the near future) that, by correcting and modulating cellular senescence can slow down, halt or even reverse aging-related diseases. Globally, these results suggest that aging is a druggable process that can be targeted with the appropriate drugs, similar to other chronic disorders.

Link: https://doi.org/10.3390/biomedicines10082006

Better fitness in later life reduces mortality, and the study results here are just one of many examples that demonstrate this correlation, though specifically for cardiovascular disease in this case. While only correlations can be determined from most human data, animal studies make it quite clear that better fitness causes a reduced later life mortality. Maintaining better physical fitness is a good idea for many reasons, and it seems clear that health and longevity will benefit from doing so.

The Atherosclerosis Risk in Communities (ARIC) study, an ongoing community-based cohort enrolled 15,792 participants, ages 45-64 years from 1987-1989, to investigate the causes for atherosclerotic disease (plaque or fatty buildup in the arteries). Yearly and semi-yearly (beginning in 2012) check-ins included phone calls and in-person clinic exams. The present study evaluated health data from ARIC visit 5 (2011-2013; all participants were older than age 65) as a baseline, when the Short Physical Performance Battery (SPPB) test was first collected. The SPPB measured physical function to produce a score according to walking speed, speed of rising from a chair without using your hands, and standing balance.

Researchers analyzed health data for 5,570 adults, average age of 75 from 2011 to 2019. Using SPPB scores, the physical function of the participants was categorized into three groups: low, intermediate, and high, based on their test performance. Researchers examined the association of SPPB scores with future heart attack, stroke, and heart failure, as well as the composite of the three, adjusting for major cardiovascular disease risk factors, such as high blood pressure, smoking, high cholesterol, diabetes, and history of cardiovascular disease.

Among all participants, 13% had low, 30% had intermediate, and 57% had high physical function scores. During the 8 years of the study, there were 930 participants with one or more confirmed cardiovascular events: 386 diagnosed with heart attack, 251 who had a stroke, and 529 heart failure cases. Compared to adults with high physical function scores, those with low physical function scores were 47% more likely to experience at least one cardiovascular disease event, and those with intermediate physical function scores had a 25% higher risk of having at least one cardiovascular disease event. The association between physical function and cardiovascular disease remained after controlling for traditional cardiovascular disease risk factors such as age, high blood pressure, high cholesterol, and diabetes.

Link: https://newsroom.heart.org/news/low-physical-function-after-age-65-associated-with-future-cardiovascular-disease

Regulatory T cells, as the name might suggest, are involved in controlling the immune response, particularly damping it down at the point at which it should resolve. They also prevent an inflammatory response from starting when it would be harmful or unnecessary, such as in response to self-antigens. A failure of regulatory T cell function is likely involved in autoimmunity, as well as in the chronic inflammation of aging.

As today's open access paper notes, regulatory T cells may be both harmful and helpful in older individuals, attempting to suppress inappropriate inflammation, but also becoming dysfunctional in ways that both suppress appropriate immune responses to infection and allow autoimmune conditions to arise by failing to suppress the response to self-antigens. Yet all too little of this is certain in the details, and published studies provide a wealth of entirely contradictory evidence. The paper notes studies that report, variously, that immune suppression by regulatory T cells is increased, decreased, or unchanged with age under various circumstances.

How does a class of immune cells responsible for suppressing inflammatory signaling and behavior manage to both over-suppress where inappropriate and under-suppress where inappropriate? Therein lies the question. The immune system is complicated, and no class of T cells is a single monolithic entity. Regulatory T cells have subtypes, while the effects of the surrounding environment on their behavior are just as complicated, situational, and distant from a full understanding as is the case for the rest of the immune system as a whole.

The dark side of Tregs during aging

From a holistic point of view, aging results from the progressive decline of various systems. Among them, the distinctive age-dependent changes in the immune system contribute to the enhanced frailty of the elderly. One of these affects a population of lymphocytes, known as regulatory T cells (Tregs), as accumulating evidence suggest that there is a significant increase in the frequency of these cells in secondary lymphoid organs of aged animals. Although there are still discrepancies in the literature about modifications to their functional properties during aging, mounting evidence suggests a detrimental role for Tregs in the elderly in the context of bacterial and viral infections by suppressing immune responses against non-self-antigens. Interestingly, Tregs seem to also contribute to the reduced effectiveness of immunizations against many pathogens by limiting the production of vaccine-induced protective antibodies

With regard to Treg immunosuppressive activity, there is still an open debate regarding whether these cells have increased or decreased functionality during aging, with evidence for both outcomes. However, there is also evidence from other studies that the suppressive activity of Tregs is not contingent on age, but instead is retained at nearly the same level throughout the lifespan. These studies showed that Tregs from young and aged mice as well as in humans have the same suppressive capacity since they can suppress CD4+ T cell proliferation to the same extent. On the other hand, Tregs from old mice have also been described as being better suppressors than those from young adult animals due to higher IL-10 production.

The most likely reason behind these inconsistencies and conflicting data is that CD25 does not accurately recapitulate Foxp3 expression and Treg activity in aged mice, so it may act as a confounding factor in the interpretation of suppression assays. Another major caveat regarding the use and interpretation of in vitro suppression assays is that they may not be truly representative of in vivo Treg-mediated suppression mechanisms. Results obtained through the use of anti-CD25 antibodies do not allow researchers to discriminate between the suppressive activity of CD4+ and CD8+ Tregs, which have also been reported to increase with age. Results can also be deeply influenced by the responder cells, which may change depending on the cell's age and type, as well as the stimuli they receive, independently of Treg functions. Moreover, the in vivo model used might affect Treg suppression, phenotype, and homing, depending on the unique local inflammatory environment.

Taken together, these conflicting data do not completely explain the simultaneously increased risk of autoimmunity, cancer, and infections observed in the elderly. Therefore, how the intrinsic functions of Tregs change during aging and what the impact of those changes may be remain questions yet to be elucidated.

In this open access paper, the authors discuss the merits of bacteriophages to carry therapeutics to specific cell populations, offering targeting of senescent cells as a starting point. While they see bacteriophages as a way to displace existing viral vectors in the long run, clearly this will be a matter of decades from where things stand now, if it comes to pass. It is, nonetheless, an interesting look at a growing area of therapeutic development. Setting aside the question of senescent cells, a better general platform for carrying gene therapies to specific tissues, or throughout the body with high efficiency, is very much needed. Whether lipid nanoparticles, improvements to existing viral vectors, or some other technology such as engineered bacteriophages will satisfy that need at the end of the day is yet to be determined. Work proceeds on all fronts, at various stages of development.

Bacteriophages are viruses that are widespread in the environment because they occur wherever they find a suitable bacterial host to survive and multiply; thus, they are naturally present on and in the human body. Because of their selectivity to specific bacterial species, they are highly specialised in infecting bacteria and fighting bacterial infections. Interestingly, this selectivity is not accompanied by any harmful effects on human cells, which is probably the result of large interspecies differences. For this reason, various studies have used phages and their enzymes as alternatives to antibiotics to address dangerously increasing antibiotic resistance.

Several unique features of bacteriophages include the ability to integrate fragments of an exogenous nucleic acid into their genome and undergo easy chemical modification to display specific targeting and/or imaging ligands on the phage surface; because of such features, they may be used as new forms of modern high-performance vectors for therapeutic compounds and vaccine delivery. Bacteriophages can carry various types of cargo, including oligonucleotides, peptides, antibodies, proteins, carbohydrates, vitamins, drugs, fluorescent dyes, aptamers, siRNA, CRISPR-Cas, large mammalian gene expression cassette, synthetic polymers, photosensitizers, quantum dots and other small nanoparticles. It was demonstrated that the potential of phages as vectors is broadened by their good biocompatibility, homogeneity, thermodynamic stability, high load capacity, efficient self-organisation ability, and scalability.

Moreover, genetic engineering and/or chemical methods may enable the synthesis of a specially designed phage with the ability to target a specific surface marker of a senescent cell. The application of a preparation composed of one type of phages to the patient is called single therapy. As many types of senescent cells characterized by various surface markers are present in different tissues simultaneously, even more beneficial than single therapy, seems to be a combination therapy. Such therapy can be simultaneous and rely on the introduction at the same time of a mixture of several types of phages (so-called phage cocktail) as well as sequential, consisting of the application of different types of phages or their cocktails at fixed intervals.

Link: https://doi.org/10.1016/j.cbi.2022.110098

A sizable part of the magic of blockchain technologies is the ability of the present ecosystem to materialize significant funding for near any effort that would have struggled to find backers via more traditional approaches. So much money flows through the exchanges and ongoing speculation that any new blockchain connected to that system quickly gains value almost regardless of its merit. That of course enables a lot of fraud. But at the same time, it enables worthwhile exercises such as VitaDAO, an organization that is using its blockchain-derived resources to fund meaningful research and development in the aging field, leading towards means to treating aging as a medical condition. As VitaDAO expands its activities, it is attracting more attention from the research community, always interested in novel means of funding fundamental science.

Like all researchers, Morten Scheibye-Knudsen is constantly looking for ways to fund his research, and he had been considering crowdfunding, when, out of the blue, he was contacted about a new platform under development for resourcing potential therapeutic programs using an online network of like-minded individuals - a so-called DAO, or decentralized autonomous community - who contribute their time or money to projects. In recent years, other DAOs have been emerging in life sciences. Scheibye-Knudsen's project searching for molecules that promote longevity seemed like an ideal program with which to test drive the new platform, which came to be called VitaDAO. Intrigued by this new means of funding, with its unusual community of stakeholders, Scheibye-Knudsen decided to apply. Several mostly academic programs have received funding from VitaDAO in the two years since he joined the group.

VitaDAO is housed on the Swiss web3-powered company Molecule, which in July received its first round of funding with a $12.6 million investment from a set of investors - some, including lead firm NorthPond Ventures, well known in the biotech space. Molecule was launched on a shoestring two years ago to catalyze the assembly of communities of life-science researchers, patients, and other stakeholders into DAOs, with the goal of democratizing and advancing translational research. Molecule's core innovation is a system for sharing intellectual property (IP) through non-fungible tokens (IP-NFTs), which simply turns IP into a digital asset, one with verifiable ownership by virtue of its being on Molecule's blockchain. The aim is to open up siloed research, at the same time enabling DAO members to play roles in advancing research that they care about.

A few weeks prior had marked the first anniversary of VitaDAO, which is Molecule's most advanced DAO. Last year, VitaDao raised more than $10 million through a token sale, $2 million of which, as of late July, has been allotted to funding various projects in geroscience, among them four that forged IP-NFTs. The idea is to provide infrastructure to market research in emerging areas that are underfunded by conventional avenues but show commercial promise - in VitaDAO's case, in geroscience. Should the DAO achieve commercial success with its projects, through a licensing event, partnership or co-development deal that further advances the asset, any financial gains will be plowed back into the platform to fund future generations of research.

Link: https://doi.org/10.1038/s41587-022-01459-z

In today's open access paper, researchers discuss the evidence for the existence of germline stem cells in the ovaries, responsible for maintaining fertility in the usual manner of stem cells, by generating daughter cells that replace losses and ensure function. Is ovarian aging, leading into age-related infertility, much accelerated over the aging of other organs in our species because this stem cell population loses function more rapidly than those in other tissues? That is a reasonable hypothesis, and some of the possible mechanisms are discussed. That ovaries are a hypoxic environment to begin with, and that supply of oxygen and nutrients does tend to decline with age for a range of reasons, is one of the more intriguing ideas.

A number of groups, including a few biotech startups in the growing longevity industry, appear to believe that ovarian aging is a good place to start on the development of the next generation of regenerative medicine, deploying more sophisticated approaches to either replace stem cell populations or rejuvenate existing populations and their damaged niches. In part this is because such therapies would be targeted to people who are not very old, are more robust and resilient. In part it is because the understanding of ovarian tissue and cell function has reached a tipping point: we are past the point at which researchers have constructed artificial ovaries and demonstrated that they are functional following transplantation into mice, for example. Techniques that succeed in restoring ovarian function could generalize to other stem cell populations. This may or may not come to pass, depending on how much of a special case ovarian aging turns out to be, but we can hope.

Female germline stem cells: aging and anti-aging

The underlying mechanisms for the aging of the ovary are still poorly understood, partially because it is a complex biological process in which many factors interact internally and externally. Compared with the "evergreen" male testes, female ovaries in advanced age women are more like "rotten root of old tree". What makes this big difference? The researchers believe that the female germline stem cells (FGSCs) aging directly determines the ovarian aging. In physiological conditions, when women reach their advanced age, the stem cells in their ovaries are exhausted, they face menopause and symptoms of hypoestrogenism, while males enjoy their old age life without dramatic decline of their testes function. They still have the ability to father as long as their spouses are young enough.

Whether mammal's ovaries have FGSCs to supplement the original follicle pool after birth has been debated for nearly one century. Now, however, scientists have isolated cells that could be subcultured in vitro and express the both stem and germ cell-specific protein markers in mice, adult mice, rats, and human ovarian tissue cortex respectively. Using a variety of methods, including stem cell culture and expansion, stem cell transplantation, genetic modification and gene editing, in vivo cell lineage tracking, the researchers confirmed existence of FGSCs in the postnatal ovaries in a variety of mammals, including humans, even old women ovarian surface epithelium, and observed that FGSCs had the ability to direct differentiation into eggs, continuously replenish follicle pools, and restore progeny to infertile model. FGSCs with GFP were transplanted into infertile mice, and both mature follicles with GFP and offspring with GFP were is covered obtained, which provided the most direct evidence of FGSCs existence.

Accumulating evidence suggest the FGSCs niche is the key link to ovarian failure. The FGSCs niche might be more important than aging of FGSCs themselves. The niche of ovaries in mammals maybe includes follicular membrane-stromal cells, granulosa cells, extracellular matrix, blood vessels, immune system-related cells and cytokines. Transplanting niche cells (mainly refer to Sertoli or mesenchymal cells) can regenerate the non-functional gonads, and this approach has resulted in the birth of fertile offspring in mice. The stem cell niche, combined with exogenous microenvironment alterations, such as changes from oxygen tension, temperature, hormones or cytokines from blood supplement, results in restricted self-renewal, senescence, skewed differentiation and compromised regeneration.

In the exogenous microenvironment, special focus has to be placed on the role of hypoxia in inducing and accelerating stem cell aging. Hypoxia, the unbalance between oxygen supply and demand, is the primary culprit of oxidative stress and chronic inflammation. Unfortunately, ovary is a deeply hypoxic organ due to it's unique structure and cell composition. On the one hand, with the growth and progression of follicular oocytes and the proliferation and division of granulosa cells, the oxygen demand gradually increases. On the other hand, continuous ovulation results in the increase of fibrous connective tissue and the significant reduction of blood vessels in the ovary, which leads to the decrease of oxygen supply in the ovary, and the decrease of blood vessels and blood supply in the ovary with the increase of age. In addition, chronic, low-grade inflammatory response caused by repeated ovulation and the accompanying oxidative stress aggravate the imbalance between supply and demand, resulting in low oxygen concentration in the ovary. This may be the important reason that the speed of ovarian aging should be faster than other organs.

In summary, exploring the mechanism of FGSCs aging is helpful in solving female infertility fundamentally in clinical practice. Rebuilding niches of FGSCs, regulation of immune dysfunction, anti-inflammation, and oxidative stress remission are expected to restore or replenish FGSCs, ultimately to delay ovarian aging.

It is in principle possible to obtain cells from the peripheral nervous system that may, once cultured and expanded in number, and possibly altered in their behavior via the application of suitable signal molecules, produce regeneration in the brain or other portions of the central nervous system. The peripheral nervous system is more readily accessed than the central nervous system, and this is the big point in favor of searching the periphery of the body for cells that might be useful in areas of the more protected, less accessible inner body.

With a steadily aging population there is an increasing prevalence of neurological disorders. Given the lack of effective treatment strategies and a limited ability for the central nervous system (CNS) to regenerate endogenously, there is a critical need to better understand exogenous strategies for nervous system repair. Stem cell therapy offers a promising approach to promote the repair of neurologic tissue and function, however studies to date have been limited by various factors including challenges in harvesting donor cells from the CNS, ethical concerns regarding use of embryonic or fetal tissue, tumorigenic potential of induced pluripotent stem cells, and immune-mediated rejection of non-autologous cell sources.

Here we review and propose two alternative sources of autologous cells derived from the peripheral nervous system (PNS) for CNS repair: enteric neuronal stem cells (ENSCs) and neural crest-derived Schwann cells found in subcutaneous adipose tissue (termed SAT-NSCs). ENSCs can be successfully isolated from the postnatal enteric nervous system, propagated in vitro, and transplanted successfully into models of CNS injury via both direct intracerebral injection and systemic tail vein injection. Similarly, SAT-NSCs can be readily isolated from both human and mouse adipose tissue and, although not yet utilized in models of CNS injury, have successfully been transplanted and restored function in models of colonic aganglionosis and gastroparesis. These unique sources of PNS-derived autologous cells offer an exciting option for stem cell therapies for the CNS as they have proven neurogenic potential and eliminate concerns around tumorigenic risk, ethical considerations, and immune-mediated rejection.

Link: https://doi.org/10.3389/fnins.2022.970350

Here, researchers demonstrate that inflammatory proteins found in extracellular vesicles, used by cells to communicate, are correlated with mortality risk. This is not a surprising result, as the signaling associated with chronic inflammation causes disruption of normal tissue function and cell behavior in many ways. It is an important contributing factor in the progression of age-related degeneration, and the risk of suffering many of the common age-related conditions is strongly correlated with the burden of chronic inflammation. Aiming to minimize age-related inflammation without disrupting immune function is a noteworthy goal for future research and development. Senolytic therapies to remove senescent cells and their pro-inflammatory signaling is a step forward, but other causes of age-related inflammation, such as the DNA debris released by stressed and dying cells, will be harder to deal with.

Even before the COVID-19 pandemic declines in life expectancy in the United States were attributed to increased mortality rates in midlife adults across racial and ethnic groups, indicating a need for markers to identify individuals at risk for early mortality. Extracellular vesicles (EVs) are small, lipid-bound vesicles capable of shuttling functional proteins, nucleic acids, and lipids. Given their role as intercellular communicators and potential biomarkers of disease, we explored whether circulating EVs may be markers of mortality in a prospective, racially, and socioeconomically diverse middle-aged cohort.

We isolated plasma EVs from 76 individuals (mean age = 59.6 years) who died within a 5 year period and 76 surviving individuals matched by age, race, and poverty status. There were no significant differences in EV concentration, size, or EV-associated mitochondrial DNA levels associated with mortality. We found that several EV-associated inflammatory proteins including CCL23, CSF-1, CXCL9, GDNF, MCP-1, STAMBP, and 4E-BP1 were significantly associated with mortality. IL-10RB and CDCP1 were more likely to be present in plasma EVs from deceased individuals than in their alive counterparts. Our results suggest that plasma EV-associated inflammatory proteins are promising potential clinical biomarkers of mortality.

Link: https://doi.org/10.1038/s41598-022-17944-z

The hallmarks of aging form a catalog of largely better studied changes in cells and tissues considered relevant, and possibly more important, in the onset and development of age-related degeneration and disease. This is not the same thing as a list of causes of aging. A few of the hallmarks mostly likely are or include deeper causes of aging, or close to causes of aging. The hallmarks do overlap with the SENS description of aging as a set of root causes, forms of molecular damage that result from the normal operation of a youthful metabolism. Since the hallmarks of aging are not, and are not intended to be a list of causes of aging, it is always possible to argue for an expansion, particularly since the hallmarks as they stand omit a number of line items that are not as well studied, but still probably important. Equally, once started on an expansion of the hallmarks, where does one stop?

We might ask ourselves: what use is a taxonomy of aging? To my eyes, the best thing that a taxonomy can achieve is to focus research and development efforts in directions that are more likely to produce meaningful gains in health and longevity. It isn't clear that the hallmarks of aging will achieve that goal, given that the primary issue in the treatment of aging lies in identifying mechanisms that are more rather than less likely to produce large effect sizes when used as a basis for anti-aging therapies. Picking a prevalent aspect of aging is no guarantee of success in this regard. Many quite prominent aspects of aging are far removed from the causes of aging (in the SENS view, at least), and treating them will most likely have little effect on overall health because the underlying causes will continue forward untouched, producing many other problems.

The SENS advocates had the right idea, "let's just talk about root causes", which produces a limited list. Whereas if less constrained, to "important things about aging that we're looking into", then there is potentially no end to the list, and no guidance as to whether any given hallmark is a good target for intervention. Certainly the hallmarks of aging look more relevant to the field today as the 14 items suggested in the open access conference report below, rather than the original 9 items, but then a decade from now they will look more relevant as 26 items, well on their way to becoming a poor guide to strategy in the treatment of aging as a medical condition.

New hallmarks of ageing: A 2022 Copenhagen ageing meeting summary

The definition of nine cellular and molecular hallmarks of ageing in 2013 provided a contextual framework to guide future ageing research. These hallmarks comprise: genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient-sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication. Recently, these hallmarks have been criticized for being insufficient in serving as a causative paradigm of ageing. Importantly though, they have recently been shown to map to age-related diseases. To address this and to explore potential new hallmarks, a research symposium "New Hallmarks of Ageing" was held in Copenhagen (Denmark) on the 22nd of March 2022, focusing on novel findings and the recontextualization of the nine hallmarks of ageing. This included the discussion of new advances and the future of the field of ageing research.

The panel stressed the importance of progress in the field, as ageing is the primary risk factor of many major human diseases. It was highlighted that increasing average lifespan over the last decades is one of the most remarkable human accomplishments, but that this success has led to a different, challenging problem, namely the ever-increasing number of chronically ill patients suffering from age-related diseases, and the resulting toll on individuals and society. Understanding the mechanisms of the ageing process will therefore be pivotal to treat the root cause of multiple age-related diseases. The panellists emphasised that only taking a limited number of defined hallmarks into account might also halt progress on processes relevant to ageing but not currently defined as hallmarks. The panellists thereby discussed the inclusion of new hallmarks to the current list.

1) Compromised autophagy is observed in numerous ageing conditions including neurodegeneration and immunosenescence. Importantly activation of autophagy can increase mouse lifespan, and even improve immune response to vaccination in older humans by overcoming immunosenescence. While originally considered under hallmark 'altered proteostasis', autophagy regulates a number of other hallmarks of ageing such as DNA repair and nutrient sensing/metabolism, and hence it was proposed to be categorised as an integrative hallmark.

2) Dysregulation of RNA processing has been noted in human ageing population studies while interventions that appear to reverse senescent phenotypes act at least in part by restoring youthful patterns of splicing factor expression. Similarly, alternative polyadenylation of mRNAs, already known to contribute to cancer, is altered with ageing and may contribute to senescence. Such changes in RNA processing add an additional layer of gene expression control over those of genome integrity, transcriptional efficacy and epigenetic regulation that are already known to change during biological ageing.

3) Microbiome disturbances: recent advances in next generation sequencing technologies have allowed the identification of notable changes in the gut microbiome with age, pointing in particular to shifts in microbial populations and loss of species diversity. Together with age-associated loss of structural integrity of the gut and other barriers (e.g. blood brain barrier), this shift in microbial populations can drive inflammation.

4) Altered mechanical properties applies both to cells and to the extracellular milieu. For example, fibroblast senescence is accompanied by a major change from a mobilizable pool of actin that can be readily polymerised and depolymerised during cell motility, to stable stress fibres of f-actin anchored through focal adhesions to the substrate, which is particularly marked in cells from patients with premature ageing syndromes and which is likely to impact on cell motility and cell-cell communication. The nucleoskeleton is also altered during ageing, with the nuclear lamina becoming destabilised, with concomitant extrusion of chromatin into the cytoplasm which trigger the SASP in senescence. Finally, extracellular matrix also changes with ageing, which greatly alters cell behaviour. Increased rigidity and loss of elasticity, for example arising through glycation cross-links between collagen molecules, can lead to multiple age-related disease states such as hypertension with concomitant kidney and neurological defects - such cross-linking may contribute to the accelerated ageing seen in patients with diabetes. The field of mechanobiology and its intersection with ageing is thus very promising in terms of 'rejuvenation'.

5) Inflammation: Inflammageing, age-dependent chronic inflammation, is implicated in a wide range of age-related diseases. Ageing correlates with high, levels of inflammatory mediators in the blood, such as IL-1, IL-6, C-reactive protein, IFNα, and several others. Originally inflammation was considered part of the hallmark 'altered intercellular communication', however it could be considered on its own merit, due to its large contribution to the ageing process and its cross-play with other hallmarks such as cellular senescence and the newly proposed gut microbiota.

People bearing more visceral fat are less healthy as a rule, due to its contribution to inflammation and burden of senescent cells, among other issues. Additionally, however, that fat tissue becomes more harmful with age, as there are changes in its function, as well as the function of other fat deposits in the body. The paper here looks at some of what is known of the functional decline in fat tissue with age.

Adipose tissue undergoes significant anatomical and functional changes with aging, leading to an increased risk of metabolic diseases. Age-related changes in adipose tissue include overall defective adipogenesis, dysfunctional adipokine secretion, inflammation, and impaired ability to produce heat by nonshivering thermogenesis. Thermogenesis in adipose tissue is accomplished by brown and beige adipocytes, which also play a role in regulating energy homeostasis. Brown adipocytes develop prenatally, are found in dedicated depots, and involute in early infancy in humans. In contrast, beige adipocytes arise postnatally in white adipose tissue and persist throughout life, despite being lost with aging.

In recent years, there have been significant advances in the understanding of age-related reduction in thermogenic adipocyte mass and function. Mechanisms underlying such changes are beginning to be delineated. They comprise diminished adipose precursor cell pool size and adipogenic potential, mitochondrial dysfunction, decreased sympathetic signaling, and altered paracrine and endocrine signals. This review presents current evidence from animal models and human studies for the mechanisms underlying thermogenic adipocyte loss and discusses potential strategies targeting brown and beige adipocytes to increase health span and longevity.

Link: https://doi.org/10.3389/fcell.2022.955612

There is a continuing debate over the role of persistent viral infection in the development of neurodegenerative disease. It seems plausible that such infection could increase chronic inflammation, and inflammation in brain tissue is a hallmark of neurodegenerative conditions. Just because the mechanism exists doesn't mean it is the primary, or even important, component of the disease process however. This is ever the challenge in complex age-related diseases, determining which of the many mechanisms in play are in fact those that primarily cause the condition. So there is a back and forth of epidemiological studies in recent years, attempting to settle the role of viral infection, particularly by herpesviruses, in neurodegenerative conditions such as Alzheimer's disease. At present neither side has a convincing advantage in weight of evidence, which suggests that there may be a more complex set of interactions going on under the hood.

The causes of Alzheimer's disease are not fully understood. There are clear associations with the accumulation of abnormal proteins in the brain, beta-amyloid and tau. There is also clear evidence of neuroinflammation, and there appears to be evidence of immune dysfunction in microglia, a type of immune cell found within the brain. One recurring theory is that herpes viruses, which are responsible for cold sores, genital herpes and other infections, might cause Alzheimer's disease.

However, researchers studying 1,009 participants in the Baltimore Longitudinal Study of Aging (BLSA) have found that while symptomatic herpes viruses were associated with neurological and cognitive symptoms, but there was no evidence to support the long-held theory that they are linked to Alzheimer's disease. The participants who were diagnosed with herpes had higher cognitive scores at the beginning of their participation but demonstrated greater longitudinal decreases in attention performance. The study did not find a link between herpes virus infection and the volume of total brain or gray matter, or in areas associated with Alzheimer's disease. Of the total participants, 119 had a record of symptomatic herpes infection. These infections were linked to longitudinal decreases in white matter volume, particularly in the temporal lobe. Being treated with antivirals slowed the declines in occipital white matter.

Link: https://www.biospace.com/article/study-symptomatic-herpes-viruses-linked-to-brain-changes-but-not-alzheimer-s/

The varieties of B cell in the immune system participate in the immune response to pathogens by creating antibodies to match specific antigens, and spreading the information represented by that antibody to portions of the adaptive immune system capable of attacking threats. This is a very crude, high level summary of an enormously complex system. The fine details of how subsets of the B cell population generate suitable antibodies, and then communicate with one another and the rest of the immune system, are complicated indeed, involving many different subsets of cell, different paths of activation, and different mechanisms.

Aspects of B cell function are known to decline with age, contributing to the broader loss of efficacy in the immune response, the onset of immunosenescence. Is this a problem with the B cells themselves becoming changed or damaged, or is it a problem of the broader system within which B cells function? This sort of question is always hard to answer in the study of aging. Biology is very complicated, and everything interacts with everything else. Isolating the specifics of any one mechanism amidst all of that is very challenging. There are always avenues by which to make some progress, however. In today's open access paper, researchers analyze the behavior of B cells transplanted from old mice into young mice, using this as a strategy to obtain some insight into which aspects of B cell function decline due to intrinsic defects in the aged cells, and which are due to age-related deficiencies in other parts of the immune system.

Interestingly, other work shows that B cells can be readily cleared from the body in old animals, and regenerate rapidly following this intervention. Immune function is improved as a result. Thus while the work here shows that old B cells remain surprisingly functional if only given a young immune system to work with, there is in fact a degradation of function that is distinct from any problem in the hematopoietic cell populations responsible for creating B cells. Some populations of problem B cells have been identified, described as age-associated B cells in the literature, and it seems we'd all be better off for their removal from the aging body.

B cell-intrinsic changes with age do not impact antibody-secreting cell formation but delay B cell participation in the germinal centre reaction

Vaccines typically protect against (re)infections by generating pathogen-neutralising antibodies. However, as we age, antibody-secreting cell formation and vaccine-induced antibody titres are reduced. Antibody-secreting plasma cells differentiate from B cells either early post-vaccination through the extrafollicular response or from the germinal centre (GC) reaction, which generates long-lived antibody-secreting cells. As the formation of both the extrafollicular antibody response and the GC requires the interaction of multiple cell types, the impaired antibody response in ageing could be caused by B cell intrinsic or extrinsic factors, or a combination of the two.

Here, we show that B cells from older people do not have intrinsic defects in their proliferation and differentiation into antibody-secreting cells in vitro compared to those from the younger donors. However, adoptive transfer of B cells from aged mice to young recipient mice showed that differentiation into extrafollicular plasma cells was favoured at the expense of B cells entering the GC during the early stages of GC formation. In contrast, by the peak of the GC response, GC B cells derived from the donor cells of aged mice had expanded to the same extent as those from the younger donors. This indicates that age-related intrinsic B cell changes delay the GC response but are not responsible for the impaired antibody-secreting response or smaller peak GC response in ageing.

Collectively, this study shows that B cells from aged individuals are not intrinsically defective in responding to stimulation and becoming antibody-secreting cells, implicating B cell-extrinsic factors as the primary cause of age-associated impairment in the humoral immunity.

Diluting blood plasma in old individuals reduces circulating levels of harmful signals, such as pro-inflammatory proteins and debris, for long enough to allow improvement in tissue function. Significant dilution requires the introduction of new albumin, and there is presently some question over how much of the benefits result from the dilution of circulating factors versus delivery of albumin which is typically sourced from blood donations from (on average) younger individuals, and is thus less damaged. Researchers here report on the effects of repeated plasma dilution treatments in three human patients, showing an improvement in circulating protein levels known to change with age, some inflammation-linked, some more generally associated with processes of aging. It is an interesting addition to present understanding, and suggests the need for clinical trials of plasma dilution: it is a cheap intervention, and thus even modest benefit makes it worth the effort.

For people, plasma dilution is known as plasmapheresis or therapeutic plasma exchange (TPE); it replaces a patient's plasma with saline and purified albumin. The blood cells are returned to the patient so that while the cell profile does not change, the circulating blood proteins are diluted, including cytokines, autoreactive antibodies or toxins, and such pathogenic determinants of specific disorders. Although its full therapeutic benefits are still being discovered, TPE is one of the treatments for autoimmune and neurological diseases.

Here, we followed the effects of a miniaturized TPE in mice and of pilot studies of TPE with 3 human patients by studying the longitudinal effects of rounds of TPE on hallmarks of systemic aging. The results demonstrate significant and lasting rejuvenation of both humoral and cellular blood compartments in people who underwent repeated plasmapheresis. The rejuvenative changes are not limited to a reduction of inflammaging but encompass diminished circulatory protein markers of neurodegeneration and cancer, as well as reduced senescence, lower DNA damage, and improved myeloid/lymphoid homeostasis.

Link: https://doi.org/10.1007/s11357-022-00645-w

Researchers here report on an interesting discovery relating to the way in which aquaporin-4 functions in clearance of molecular waste from the brain. An uncommon isoform of aquaporin-4 has a role in clearing excess amyloid-β, and possibly many other forms of molecular waste. Given that a failure of clearance of molecular waste from the brain is apparently involved in many neurodegenerative conditions, approaches that enhance clearance are promising. Increased amounts of this more effective isoform can be achieved via a variety of strategies in mice, and in mice engineered to generate excess amyloid-β, this results in a reduction of amyloid-β in the brain. This is quite interesting, but further work is required to determine a useful way to implement this shift in protein isoforms in humans.

Every once in a while, the brain protein aquaporin 4 is synthesized with an extra little tail on the end. Scientists already knew that the cell's protein-building machinery occasionally fails to stop where it should. When the machinery doesn't stop - a phenomenon known as readthrough - it creates extended forms of proteins that sometimes function differently than the regular forms. "At first, we thought it couldn't possibly be relevant. But then we looked at the gene sequence, and it was conserved across species. And it had this really striking pattern in the brain: it was only in structures that are important for waste clearance. So that's when we got excited."

Researchers found the long form - but not the short one - in the so-called endfeet of astrocytes. Astrocytes are a kind of support cell that help maintain the barrier between the brain and the rest of the body. Their endfeet wrap around tiny blood vessels in the brain and help regulate blood flow. Astrocytic endfeet are the perfect place to be if your job is to keep the brain free of unwanted proteins by flushing waste out of the brain and into the bloodstream, where it can be carried away and disposed of.

Thinking that increasing the amount of long aquaporin 4 might increase waste clearance, researchers screened 2,560 compounds for the ability to increase readthrough of the aquaporin 4 gene. They found two: apigenin, a dietary flavone, and sulphaquinoxaline, a veterinary antibiotic. Sulphaquinoxaline is not safe for use in people. Apigenin is available as a dietary supplement, but it's not known how much gets into the brain. The researchers studied mice genetically engineered to have high levels of amyloid in their brains. They treated the mice with apigenin; sulphaquinoxaline; an inert liquid; or a placebo compound that has no effect on readthrough. Mice treated with either apigenin or sulphaquinoxaline cleared amyloid beta significantly faster than those treated with either of the two inactive substances.

"There's a lot of data that says reducing amyloid levels by just 20% to 25% stops amyloid buildup, at least in mice, and the effects we saw were in that ballpark. This could be a novel approach to treating Alzheimer's and other neurodegenerative diseases that involve protein aggregation in the brain. There's nothing that says this process is specific for amyloid beta. It may be enhancing, say, alpha-synuclein clearance, too, which could benefit people with Parkinson's disease."

Link: https://medicine.wustl.edu/news/study-points-to-new-approach-to-clearing-toxic-waste-from-brain/

This post is an update for an earlier report on a self-experiment with flagellin immunization, tested as an approach to adjust the balance of microbial populations in the aging gut microbiome in a favorable, more youthful direction. Commentary and data from the earlier report are repeated, with the addition of a new assessment of the gut microbiome taken two years after the end of the experiment. In summary, changes from this short and simple intervention were largely favorable, and largely sustained over this period of time.

Flagellin is the protein that makes up bacterial flagellae, and it is hypothesized that there is a sizable overlap between populations of gut microbes that possess flagellae and populations of gut microbes that are harmful rather than helpful. The harmful microbes are largely a problem because they contribute to chronic inflammation, while helpful microbes are largely beneficial due to the metabolites that they produce. The gut microbiome changes with age, shifting towards more harmful and fewer helpful microbes.

If the immune system can be roused to do a better job of eliminating the problem microbes, then perhaps this could lead to improved health. Flagellin immunization has been trialed in humans as a vaccine adjuvant, and shown to be safe in the small studies conducted to date. In recent years, researchers tested its ability to adjust the gut microbiome in mice, with favorable results. In 2020, I posted a potential study outline for a self-experiment in flagellin immunization as a prompt for discussion, and in 2021 I published a report from one adventurous self-experimenter who gave it a try.

Setting Expectations

The motivation for this self-experiment was curiosity: would human data be similar to the mouse data? After a couple of years, the results continue to be, on balance, positive. The mouse data doesn't cover this sort of time span, but it is worth noting that in killifish adjustments to the gut microbiome made by fecal microbiota transplant are lasting, at least on the relatively short scale of a killifish life span. The question of whether results from an intervention to change the gut microbiome will last is of course quite an important one! A useful, lasting intervention is a great deal more valuable than one that does not last. This is a self-experiment in which there is an unusually clear readout for the outcome of interest, in the form of the Viome gut microbiome assay. This is nonetheless a study population of one. The results should be taken as interesting, but not supportive of any particular conclusion beyond the desire to run a larger and more formal study.

Schedule for the Self-Experiment

The self-experiment ran for ten weeks. Weekly intramuscular injections of 10 μg flagellin in 0.5ml phosphate-buffered saline were used, with Viome gut microbiome assays performed (a) beforehand, (b) at 10 weeks, (c) at 8 months, (d) and finally at 28 months.

• Week 1: Viome gut microbiome assessment.
• Week 1: Intramuscular injection of 10 μg of flagellin.
• Week 2: Intramuscular injection of 10 μg of flagellin.
• Week 3: Intramuscular injection of 10 μg of flagellin.
• Week 4: Intramuscular injection of 10 μg of flagellin.
• Week 5: Intramuscular injection of 10 μg of flagellin.
• Week 6: Intramuscular injection of 10 μg of flagellin.
• Week 7: Intramuscular injection of 10 μg of flagellin.
• Week 8: Intramuscular injection of 10 μg of flagellin.
• Week 9: Intramuscular injection of 10 μg of flagellin.
• Week 10: Intramuscular injection of 10 μg of flagellin.
• Week 10: Viome gut microbiome assessment.
• Week 34: Viome gut microbiome assessment.
• Week 122: Viome gut microbiome assessment.

Subject Details

The subject for the self-experiment was in the 45-55 age range, healthy and without chronic conditions, with a BMI of ~22 throughout the duration of the experiment. Diet and exercise were described as "relatively consistent" across this time, including the six month and two year follow up assessments. I feel that one should always be relatively skeptical of that sort of claim, however, no matter how formal or informal the study.

Summary of Results

Viome does not provide raw data on species and prevalence of gut microbes and their biochemistry, but rather a set of scores derived from that raw data. The algorithm used isn't public, meaning that one can't really dispute any of their choices or the studies used to support those choices, unfortunately. The algorithm is, nonetheless, consistent between assays at different times, and so can be used as a point of comparison for the purposes of a self-experiment, at least.

Over the course of the self-experiment, Viome summary scores improved for Inflammatory Activity, Digestive Efficiency, Gut Lining Health, Protein Fermentation, and Gas Production. The summary scores declined for Metabolic Fitness and Active Microbial Diversity. The gains (largely bad scores transforming into good scores) were larger than the declines (bad scores becoming worse scores). Some of these areas of function are likely more important than others to health, though expect arguments over which and why. My bias would be to prioritize Inflammatory Activity and Gut Lining Health when it comes to interactions between the gut microbiome and the processes of aging, but this is certainly a viewpoint that could be challenged.

Viome Data - Overall Score

Gut Microbiome Health:
   Before: 27
   After: 43
   Week 34: 49
   Week 122: 42

Viome Data - Summary Scores

Inflammatory Activity (lower is better):
   Before: 50
   After: 45
   Week 34: 28
   Week 122: 31

Metabolic Fitness (higher is better):
   Before: 25
   After: 29
   Week 34: 21
   Week 122: 25

Digestive Efficency (higher is better):
   Before: 0
   After: 57
   Week 34: 68
   Week 122: 52

Gut Lining Health (higher is better):
   Before: 12
   After: 64
   Week 34: 69
   Week 122: 75

Protein Fermentation (lower is better):
   Before: 87
   After: 49
   Week 34: 33
   Week 122: 54

Gas Production (lower is better):
   Before: 83
   After: 48
   Week 34: 35
   Week 122: 35

Active Microbial Diversity (higher is better):
   Before: 34
   After: 15
   Week 34: 15
   Week 122: 5

Viome Data - Other Ratings

Ammonia Production Pathways
   Before: Not Optimal
   After: Average
   Week 34: Good
   Week 122: Not Optimal

Bile Acid Metabolism Pathways
   Before: Average
   After: Good
   Week 34: Good
   Week 122: Average

Biofilm, Chemotaxis, and Virulence Pathways
   Before: Not Optimal
   After: Not Optimal
   Week 34: Good
   Week 122: Not Optimal

Butyrate Production Pathways
   Before: Average
   After: Average
   Week 34: Not Optimal
   Week 122: Average

Flagellar Assembly Pathways
   Before: Not Optimal
   After: Not Optimal
   Week 34: Average
   Week 122: Average

LPS Biosynthesis Pathways
   Before: Average
   After: Average
   Week 34: Average
   Week 122: Average

Methane Gas Production Pathways
   Before: Good
   After: Not Optimal
   Week 34: Good
   Week 122: Average

Oxylate Metabolism Pathways
   Before: Average
   After: Not Optimal
   Week 34: Not Optimal
   Week 122: Not Optimal

Putrescine Production Pathways
   Before: Not Optimal
   After: Not Optimal
   Week 34: Average
   Week 122: Average

Salt Stress Pathways
   Before: Average
   After: Average
   Week 34: Average
   Week 122: Average

Sulfide Gas Production Pathways
   Before: Not Optimal
   After: Average
   Week 34: Average
   Week 122: Good

TMA Production Pathways
   Before: Good
   After: Good
   Week 34: Good
   Week 122: Average

Uric Acid Production Pathways
   Before: Not Optimal
   After: Not Optimal
   Week 34: Not Optimal
   Week 122: Good

Anecdotal Notes

The first few injections of flagellin produced a minor injection site reaction that lasted a few days: red and tender. That was reduced with each injection, and later injections produced no reaction. Beyond that, no perceptible change in health or digestion, positive or negative, was observed as a result of the self-experiment.

Conclusion

Coupled with the animal data, and the existing human trial data for safety, the results here suggests that someone should run a formal, controlled trial of flagellin immunization in older people, 65 and over. The goal would be to see whether (a) this sort of outcome holds up in a larger group of people, and (b) there is a meaningful impact on chronic inflammation and other parameters of health that are known to be affected by the aging of the gut microbiome.

The most interesting part of the data is perhaps the decline in microbial diversity, when considered against the gains elsewhere. Microbial diversity correlates with better health in epidemiological studies, but there isn't a good mechanistic understanding as to why this is the case, or what factors provoke diversity versus a lack of diversity.

It is becoming harder for the world at large to ignore the field of senolytics, the large number of research groups and companies working towards therapies that clear a fraction of senescent cells from aged tissues. Senescent cells accumulate in later life, likely because the immune system becomes less able to remove them promptly. Lingering senescent cells actively disrupt normal tissue function and provoke chronic inflammation, thus contributing to age-related degeneration. Scores of mouse studies conducted over the last decade demonstrate that senolytic treatments produce rapid, reliable reversal of many age-related conditions and extension of healthy life span. Most interestingly, the best of the early senolytic treatments, the dasatinib and quercetin combination, is cheap, readily available, and in human clinical trials with promising initial results. The opening decades of the 21st century are the start of a golden future, in which none of us will have to be as impacted by aging and age-related disease as our parents and grandparents were.

Cells eventually stop dividing and enter a "senescent" state in response to various forms of damage. The body removes most of them. But others linger like zombies. They aren't dead. But they can harm nearby cells like moldy fruit corrupting a fruit bowl. They accumulate in older bodies, which mounting evidence links to an array of age-related conditions such as dementia, cardiovascular disease, and osteoporosis. But scientists wonder: Can the zombie cell buildup be stopped? "The ability to understand aging - and the potential to intervene in the fundamental biology of aging - is truly the greatest opportunity we have had, maybe in history, to transform human health. Extending the span of healthy years impacts quality of life, public health, socioeconomics, the whole shebang."

"When you're young, your immune system is able to recognize these senescent cells and eliminate them. But when we start getting old ... the activity of our immune system also gets diminished, so we're losing the capacity to eliminate them." Senescent cells resist apoptosis, or programmed cell death, and characteristically get big and flat, with enlarged nuclei. They release a blend of molecules, some of which can trigger inflammation and harm other cells - and paradoxically can also stimulate the growth of malignant cells and fuel cancer.

Experimental drugs designed to selectively clear senescent cells have been dubbed "senolytics." In mice, they've been shown to be effective at delaying, preventing, or easing several age-related disorders. Possible benefits for people are just emerging. Researchers undertook a pilot study providing initial evidence that patients with a serious lung disease might be helped by pairing a chemotherapy drug with a plant pigment. Another pilot study found the same combination reduced the burden of senescent cells in the fat tissue of people with diabetic kidney disease. At least a dozen clinical trials with senolytics are now testing things like whether they can help control Alzheimer's progression, improve joint health in osteoarthritis, and improve skeletal health.

Scientists say serious work to improve human health could also bring fringe benefits - like reducing skin wrinkling. "I tell my lab that if we find a drug that clears the bad senescent cells and not the good ones and we cure Parkinson's disease and Alzheimer's and osteoporosis and macular degeneration, it would be wonderful. But if we cure wrinkles, we'll be rich, and I'll never have to write another grant. We know that senolytics work pretty well in mice. We're still really figuring out the basics with people."

Link: https://apnews.com/article/zombie-cells-central-quest-active-vital-old-age-e52713983444185dcd6ed116305d0764

One of the causes of immune system aging is the growing dysfunction of hematopoietic stem cell populations, responsible for the production of immune cells. While some of this degeneration comes from the aging of the bone marrow niche, some it appears to be intrinsic to the cells themselves, and thus there may be benefits to be found in transplantation of functional hematopoietic stem cells derived from a patient's own cells. This would be the case if these cells could be made to reliably survive and engraft in any reasonable number, however. That is a challenging prospect, but it is worth keeping an eye on the cancer field, where transplantation of donor stem cells is used to attack leukemias, for signs of promising advances such as the one noted here.

Hardly a day goes by without someone receiving an infusion of healthy donor-derived hematopoietic stem cells (HSCs) to replace those lost or damaged by disease. But the types of stem cells contained in such a transplant are not all the same. The majority are "short-term" HSCs. These cells can give rise to all manner of white blood cells, thus offering a reprieve from cancer or disease. But the cells have limited capacity for self-renewal, a biological weakness that constrains the duration of their therapeutic benefit.

A different population of rare stem cells has the potential for prolonged reconstitution of the blood-forming system. These "long-term" HSCs can both sustain the stem cell pool and differentiate into their short-term kin, which makes them ideal from a therapeutic standpoint. But long-term HSCs have their own drawback: they are not particularly adept at engraftment, the process of taking root in recipient individuals - and researchers have now discovered why.

Researchers showed that, compared to short-term HSCs, the reduced expression of key adhesion molecules in long-term HSCs explained their poor engraftment ability. The researchers then found a type of drug commonly used to treat diabetes; when added to long-term HSCs, this drug altered the dynamics of cell surface adhesion molecules in ways that improved uptake of the cells in mice. Another type of adhesion-targeted treatment also augmented the engraftment potential of short-term HSCs - and, as an added bonus, it made the cells behave more like their long-term counterparts. Researchers next hope to test the strategy with human stem cells and human recipients.

Link: https://discovery.kaust.edu.sa/en/article/1270/sticky-stem-cells-make-for-better-transplants