Fecal Microbiota Transplantation from Young Mice Improves Function in Old Progeroid Mice

Scientists like to conduct studies using mouse lineages that exhibit forms of accelerated aging, as a faster study is a cheaper study. These mice do not exhibit accelerated aging per se, of course. Each lineage suffers from some sort of increased production of cell and tissue damage, leading to a faster onset of conditions akin to natural age-related diseases. Aging itself is a matter of damage accumulation, but it is usually the case that the types and mix of damage matters when it comes to drawing conclusions from an animal study. Not always, though. In today's open access paper, that the mice are damaged in ways that cause a faster onset of age-related disability and disease doesn't detract from the finding that resetting the aged gut microbiome to a more youthful state produces benefits to health.

As is now well known, the gut microbiome changes with age in ways that cause harm to long-term health. The reasons for this change are not fully understood, but the age-related decline of the immune system, responsible for gardening the gut microbiome, may be an important factor. Beneficial microbial populations, such as those that generate useful metabolites, decline in number. Harmful populations increase in number, provoking chronic inflammation. Numerous animal studies have demonstrated that fecal microbiota transplantation from young individual to old individuals can produce a lasting improvement in the state of the gut microbiome. That is accompanied by improved health and, in some studies, extension of life span.

Regular fecal microbiota transplantation to Senescence Accelerated Mouse-Prone 8 (SAMP8) mice delayed the aging of locomotor and exploration ability by rejuvenating the gut microbiota

Recent evidence points out the role of the gut microbiota in the aging process. However, the specific changes and relevant interventions remain unclear. In this study, Senescence Accelerated Mouse-Prone 8 (SAMP8) mice were divided into four groups; young-FMT-group transplanted fecal microbiota from young donors (2-3 months old) and old-FMT-group transplanted from old donors (10-11 months old); additionally, other two groups, either adult mice injected with saline solution or untreated mice, served as the saline and blank control groups, respectively. All mice were intervened from their 7-months-old until 13-months-old.

The open field test conducted at 9 and 11 months of age showed that the mice transplanted with gut microbiota from young donors had significantly better locomotor and exploration ability than those of transplanted with old-donors gut microbiota and those of saline control while was comparable with the blank control. 16S rRNA gene sequencing showed that the gut microbiome of recipient mice of young donors was altered at 11 months of age, whereas the alteration of the gut microbiome of old-donor recipient mice was at 9 months. For comparison, the recipient mice in the blank and saline control groups exhibited changes in the gut microbiome at 10 months of age.

The hallmark of aging-related gut microbiome change was an increase in the relative abundance of Akkermansia, which was significantly higher in the recipients transplanted with feces from older donors than younger donors at 9 months of age. This study shows that fecal microbiota transplantation from younger donors can delay aging-related declines in locomotor and exploration ability in mice by changing the gut microbiome.

10% of Older People Suffer Dementia, Another 20% Exhibit Mild Cognitive Impairment

One in three people over 65 in the US exhibit either dementia or mild cognitive impairment. There is a great need for treatments that target the mechanisms of aging, particularly those that contribute to the environment of chronic inflammation that characterizes the aging brain. Neurodegenerative conditions are the outcome of so many different contributing mechanisms that success in the medical control of aging, finding ways to repair or work around the cell and tissue damage that causes aging, seems the most plausible path towards anything that resembles either a cure or absolute prevention.

Dementia is a highly prevalent condition characterized by cognitive difficulties that typically begin in adulthood and affect a person's ability to independently perform everyday activities. Alzheimer's disease is the most common cause of dementia, accounting for approximately 60% to 80% of all dementia cases. Mild cognitive impairment (MCI) is a clinical classification assigned to people who are thought to be transitioning between normal aging and dementia. Because age is the most potent risk factor for dementia and MCI, the number of adults with these conditions is projected to rise dramatically in the US and around the world due to demographic trends that have transformed populations from mostly young adults to mostly older adults.

Based on a community cohort of older adults in Chicago, Illinois, the prevalence of dementia due to Alzheimer's disease in the US in 2021 was estimated at 11.3% of those 65 years and older, which translates to about 6.2 million adults. Other recent estimates have been somewhat lower, likely related to differences in study methods. Similarly, different implementation of MCI criteria and cohort characteristics drive variability in MCI prevalence and rates of progression to dementia across cohorts. It is well established that annual progression rates of MCI to dementia in population- or community-based studies are lower (4% to 15%) than in clinic-based studies (12% to 17%).

The Health and Retirement Study (HRS) provides a core resource for researchers who require US population-level data on dementia and MCI prevalence and incidence. The Harmonized Cognitive Assessment Protocol (HCAP) was developed to update national estimates of the prevalence of MCI and dementia in the US. Of 9,972 age-eligible HRS participants, 4,425 were randomly selected for HCAP, and 3,496 completed a comprehensive neuropsychological test battery and informant interview, none of whom were excluded.

A total of 393 individuals (10%) were classified as having dementia and 804 (22%) as having MCI. Every 5-year increase in age was associated with higher risk of dementia (weighted odds ratio, OR, 1.95 per 5-year age difference) and MCI (OR 1.17 per 5-year age difference). Each additional year of education was associated with a decrease in risk of dementia (OR 0.93 per year of school) and MCI (OR 0.94 per year of school). In conclusion, the national prevalence of dementia and MCI in 2016 found in this cross-sectional study was similar to that of other US-based studies.

Link: https://doi.org/10.1001/jamaneurol.2022.3543

Reprogramming as an Approach to Reduce T Cell Exhaustion

T cell exhaustion occurs following repeated stimulation, such as when faced with a growing cancer or persistent viral infection. It manifests as a progressive loss of function, the T cells no longer attacking pathogens or errant cells. Finding a way to minimize this phenomenon would assist in a range of conditions, such as by improving the outcome of T cell immunotherapies targeting cancer, and might help improve the aged immune system, in which T cell exhaustion is also observed. Here, the use of partial reprogramming is suggested as an approach to achieve this goal. In partial reprogramming, cells are exposed to the factors that can change somatic cells into pluripotent stem cells, but only for a limited time. This exposure does not change cell type, but resets the epigenetic landscape - and thus cell behavior - to a more youthful, functional state.

Turn Biotechnologies, a cell rejuvenation company developing novel mRNA medicines to cure untreatable, age-related conditions, today presents interim pre-clinical data that demonstrates treating T cells with its proprietary technologies can significantly increase their ability to kill cancer. The data show that using Turn Bio's Epigenetic Reprogramming of Aging (ERA) technology in the manufacture of T cells can produce and deliver more effective therapies more efficiently. The findings promise to help reduce the cost of T-cell therapies and make them more accessible to cancer patients.

Turn Bio's technologies were applied concurrently with the CAR T-cell manufacturing process, which demonstrates that T-cell immunotherapy products can be enhanced without additional time or facilities beyond those already needed for manufacturing. The company's process can transfect immune cells with rates as high as industry-standard electroporation, but with no cytotoxicity while precisely controlling timing, duration and activation of the ERA factor cocktail while preserving cellular identity.

Link: https://www.prnewswire.com/news-releases/t-cells-treated-by-turn-biotechnologies-show-increased-cancer-killing-effectiveness-301656869.html

Aubrey de Grey Establishes the Longevity Escape Velocity Foundation

Aubrey de Grey, co-founder of the Methuselah Foundation and later the SENS Research Foundation (SRF), funding the latter organization with $13M of his own resources to add to the donations of philanthropists, has over the past year separated from the SRF, for reasons that I intend to neither discuss nor have a public opinion on. Per his presentation at the recent Longevity Summit Dublin, he has now founded the Longevity Escape Velocity (LEV) Foundation in collaboration with the Ichor Life Sciences principals to continue to bring funding into the programs that he believes need to happen in order to unblock important lines of research and development leading to rejuvenation therapies.

It is quite clearly the case that we wouldn't be as far advanced as we are today without the past twenty years of patient advocacy, agitation, education, outreach, and philanthropic funding of blocked and neglected research, without the efforts of the staff and leadership of the Methuselah Foundation, SENS Research Foundation, and their growing list of allies in the research community.

Details are somewhat sparse as to which specific programs will be undertaken by the LEV Foundation, but we should probably expect them to be much along the same lines as the work done at SRF over the past decade. Combining interventions appears to be an initial focus; it was always the case that the SENS approach to aging was envisaged as many different therapies targeting different forms of age-related damage. Meanwhile, many promising programs are roadblocked in the early stages by problematic financial and regulatory incentives, which can only be efficiently bypassed by philanthropic funding aimed at simply getting the job done: do the work, unblock the program, get it to a point at which it is interesting to entrepreneurs and biotech investors. That approach to progress at the SRF has led to a number of spin-out biotech companies working towards human rejuvenation, and more of the same lies in the future at the LEV Foundation.

The SRF (and Methuselah Foundation!) of course continue as they were: they are still conducting useful programs that advance specific areas of research relevant to human rejuvenation towards readiness for well-funded development. The Methuselah Foundation tends to focus much of its energy on projects relating to the tissue engineering of replacement organs, and running the Methuselah Fund for investment in biotech startups in the longevity industry, while the SRF has a broader remit connected to the fundamental biochemistry of aging, and the SENS vision of rejuvenation as repair of the underlying molecular damage that causes aging. Both are doing good work.

LEV Foundation

Longevity Escape Velocity (LEV) Foundation exists to proactively identify and address the most challenging obstacles on the path to the widespread availability of genuinely effective treatments to prevent and reverse human age-related disease.

Aubrey de Grey inspires at Longevity Summit Dublin 2022

Dr. Aubrey de Grey presented an overview of the projects LEV Foundation is already funding during his talk at Longevity Summit Dublin, video of which is available.

Towards Direct Reprogramming of Heart Fibroblasts into Cardiomyocytes

A promising approach to inducing regeneration from injury and age-related fibrosis in the heart is the reprogramming of fibroblast cells into heart muscle cells, cardiomyocytes. Like all such efforts, much of the work lies in establishing the recipe of regulatory signals needed to produce the desired outcome. The research results reported here are an illustrative example, representative of programs taking place in many laboratories, in which scientists are attempting to improve on the discovered forms of reprogramming in order to make them efficient enough to be useful as a basis for regenerative therapies.

Mammalian hearts have almost no ability to grow new heart muscle cells, called cardiomyocytes, after birth. Thus, dead tissue after an adult heart attack is not repaired with new cardiomyocytes. It is instead replaced with scar tissue that weakens the pumping power of the heart and often leads to heart failure. One promising strategy to remuscularize the injured heart is the direct cardiac reprogramming of heart fibroblast cells into cardiomyocytes.

Current cocktails for direct reprogramming of human fibroblasts suffer from low efficiency and insufficient production of functional cardiomyocytes. Researchers have now identified TBX20 as the most underexpressed factor when they compared cardiomyocytes induced from fibroblasts using a current reprogramming cocktail versus functional cardiomyocytes. The addition of TBX20 promoted cardiac reprogramming, as seen in activation of cardiac genes related to sarcomere structure, ion channels and heart contractions. A sarcomere is the smallest functional unit of striated muscle.

Mechanistically, the researchers found that TBX20 was bound to and activated cardiac gene enhancers. In detail, TBX20 primarily activated genes at the late stage of reprogramming, enhancing calcium flux, contractility, and mitochondrial function in the induced-cardiomyocytes. Mitochondria are the energy source for heart muscle contractions. TBX20 appeared to help the mitochondria in the induced cardiomyocytes switch to an adult cardiomyocyte-like respiration.

Link: https://www.uab.edu/news/research/item/13190-tbx20-enhances-reprogramming-of-heart-fibroblasts-into-heart-muscle-cells

Epigenetic Inheritance of Benefits Resulting from Parental Physical Fitness

Evolution has produced a system in which the epigenetics of offspring are adapted to the environment experienced by the parents, an effect presumably selected to produce greater fitness, in the same way as improved health in response to lower calorie intake is selected to produce greater fitness. Physically active parents produce an altered epigenetic landscape in offspring in comparison to those with worse health. This has been demonstrated in a number of species, with the research in mice noted here as one of many examples. Similar effects on the epigenetics of offspring no doubt exist in humans as well, but would be challenging to disentangle from the consequences of cultural transmission of lifestyle choices.

This study used mice to evaluate how their lifestyles - eating fatty foods vs. healthy and exercising vs. not - affected the metabolites of their offspring. Metabolites are substances made or used when the body breaks down food, drugs or chemicals, or its own fat or muscle tissue. "We have previously shown that maternal and paternal exercise improve health of offspring. Tissue and serum metabolites play a fundamental role in the health of an organism, but how parental exercise affects offspring tissue and serum metabolites has not yet been investigated."

Researchers used targeted metabolomics - the study of metabolites - to determine the impact of maternal exercise, paternal exercise, and the combination of maternal and paternal exercise on the metabolite profile in offspring liver, skeletal muscle, and blood serum levels. This study found that all forms of parental exercise improved whole-body glucose metabolism in offspring as adults, and metabolomics profiling of offspring serum, muscle, and liver reveal that parental exercise results in extensive effects across all classes of metabolites in all of these offspring tissues.

Link: https://www.eurekalert.org/news-releases/968791

Stem Cell Derived Extracellular Vesicles Reduce Epigenetic Age in Mice

As a strategy, the measurement of epigenetic age to assess the outcome of therapy intended to slow or reverse aging has its issues. Since it remains unknown as to how near all of the epigenetic marks on the genome are caused by the underlying processes of aging, it is quite possible that any given epigenetic clock will underestimate or overestimate the effects of a given approach to therapy, based on the choice and weighting of epigenetic marks used in the clock. It is suspected that the existing clocks are strongly influenced by only some of the mechanisms of aging.

Thus the assessment epigenetic age in a study of a potential treatment targeting aging should be considered exploratory at this time, a part of the ongoing and likely lengthy process of calibrating the clocks. It should be accompanied by a range of other measures of health and function.

Today's open access paper, covering an extracellular vesicle based intervention, is an example of going about this in the right way, in which epigenetic age is only one of a number of measures of the impact of aging on the mice involved. The use of extracellular vesicles derived from cultured stem cells is a logical evolution of early stem cell therapies, in which the benefits are derived near entirely from the signaling produced by the transplanted cells. Delivery of vesicles is a logistically easier approach, with evidence suggesting that this can produce similar outcomes to stem cell therapies.

Small extracellular vesicles from young adipose-derived stem cells prevent frailty, improve health span, and decrease epigenetic age in old mice

Extracellular vesicles (EVs), small vesicles that are released by virtually all cell types, with an innate ability to mediate the transmission of signaling molecules (proteins, small RNAs, and DNA) between cells are among the factors that are involved in the communication between cells. Stem cells have intrinsic regenerative effects that are not only mediated by the repopulation of damaged tissue. The releasing of regulatory molecules is also proposed as one of the most important mechanisms in stem cell therapies. More specifically, small EVs (sEVs) derived from multiple stem cells have demonstrated their capacity to promote tissue regeneration after several types of damage. Compared to stem cells, sEVs are more stable, have no risk of aneuploidy, have a lower chance of immune rejection, and can provide an alternative therapy for various diseases.

Here, we show that sEVs from young adipose-derived stem cells (ADSC-sEVs) improve several functions that are impaired in old mice. Old mice that received young ADSC-sEVs showed lower levels of frailty and improvements on physical condition tests, fur regeneration, and renal function. ADSC-sEVs induced proregenerative effects in muscle and kidney of aged mice, as well as a decrease in oxidative stress, inflammation, and senescence markers. Moreover, predicted epigenetic age was lower in tissues of old mice treated with ADSC-sEVs and the metabolome of old mice treated with ADSC-sEVs changed from an old-like pattern to a youth-like one.

We observed a reduction of senescence in tissues and in vitro when sEVs were introduced; however, the mechanism of action remains unclear, as we did not find senolytic activity. They may probably act as senomorphics, molecules that suppress the senescent phenotype without the specific induction of apoptosis in senescent cells, probably through the inhibition of the senescence-associated secretory phenotype, as has been suggested recently.

We gained some insight into the microRNAs (miRNAs) contained in sEVs that might be responsible for the observed effects. We have explored miRNAs contained in young ADSC-sEVs and found that they are involved in several processes and pathways affected by aging, thus proposing miRNAs as possible mediators of the effects shown in mice. Taking into account our results and other preliminary studies, miR-214-3p may play a role in senescence. It is important to point out the debate on the relevance of miRNAs in the function of EVs, as recent studies have shown low levels of miRNAs in EVs, along with a limited delivery into target cells. More studies are needed to identify factors derived from stem cells that can assist tissue function and regeneration, as they could have an enormous impact on age-related pathologies, such as frailty or renal failure.

An Age of Metabolomics

Obtaining enormous amounts of data on the human metabolome now costs little. Databases of metabolomic data available for analysis have become vast, and continue to grow. Productive analysis trails far behind the production of data, unfortunately, as is true for all of the omics technologies. In this paper, researchers discuss the present state of metabolomic knowledge in the context of aging, and the path forward to producing useful understanding from this deluge of human data, contributing perhaps to the better development of treatments for aging.

Aging is a fundamental part of the human experience, and it has long been understood to be a crucial component of health and disease. Population estimates of mortality fundamentally incorporate and adjust for age, which is widely considered the most important predictor of mortality. Defining the biology that drives aging is challenging, but theories of aging have coalesced around several key hallmarks, ranging from cellular senescence and stem cell exhaustion to mitochondrial, proteostasis, and genomic dysfunction. As the world's population ages, with one in six expected to be 60 or older by the end of 2030, understanding these physiological pathways and how to intervene in them will be critical to the prevention and management of the major drivers of morbidity and mortality.

In recent decades, technological advancements have opened up new possibilities for obtaining molecular data at a population scale. One of these technologies is metabolomics, which refers to the study of small molecules in the body. The Recon3D resource has mapped over 4,000 unique metabolites in a model of human metabolism, comprising over 13,000 metabolic reactions, and the Human Metabolome Database (HMDB) has annotated over 200,000 metabolites that may potentially be found in humans. Metabolites span a diversity of physiological processes, including the building blocks of the major macromolecules (e.g., amino acids, nucleic acids, carbohydrates, and fatty acids), functional nutrients (e.g., vitamins and cofactors), and compounds such as sex hormones, drug intermediates, and toxins. While this molecular diversity makes chemical identification more challenging, it also makes the metabolome an attractive dataset for application to many biomedical problems.

The decreasing cost and increasing scalability of metabolomics platforms have led to a proliferation of cohorts and biobanks adding metabolomics to their studies. For instance, the U.K. Biobank, one of the largest population cohorts to date, announced a project in 2018 to measure over 200 metabolites in half a million blood samples; the Trans-Omics for Precision Medicine (TOPMed) program has funded metabolomics collection in over 60,000 samples from diverse populations to pair with deep phenotyping and whole-genome sequencing data; and the Consortium of Metabolomics Studies (COMETS) has been working since 2014 to combine blood metabolomics data from dozens of cohorts worldwide for large-scale biomedical research. These studies represent a new era of population health research and molecular epidemiology that has enabled an unprecedented molecular view of aging processes with profound implications for precision health applications.

Link: https://doi.org/10.1126/sciadv.add6155

Theorizing a Role for Prelamin A in Aging

Researchers here review the evidence for prelamin A to have a role in aging. This derives from research into the LMNA mutation that results in Hutchinson-Gilford progeria syndrome, as normal prelamin A has some commonalities with the mutated lamin A, called progerin, that produces pathology in that condition. As is always the case, the mechanisms look plausible, but the question remains open as to whether this does in fact produce a meaningful contribution to aging. The only way to find out is to downregulate prelamin A efficiently without affecting other mechanisms of aging, and see what happens.

Almost since the discovery that mutations in the LMNA gene, encoding the nuclear structure components lamin A and C, lead to Hutchinson-Gilford progeria syndrome, people have speculated that lamins may have a role in normal aging. The most common HPGS mutation creates a splice variant of lamin A, progerin, which promotes accelerated aging pathology. While some evidence exists that progerin accumulates with normal aging, an increasing body of work indicates that prelamin A, a precursor of lamin A prior to C-terminal proteolytic processing, accumulates with age and may be a driver of normal aging.

Prelamin A shares properties with progerin and is also linked to a rare progeroid disease, restrictive dermopathy. Here, we describe mechanisms underlying changes in prelamin A with aging and lay out the case that this unprocessed protein impacts normative aging. This is important since intervention strategies can be developed to modify this pathway as a means to extend healthspan and lifespan.

Link: https://doi.org/10.18632/aging.204342

More on the Debate Over the Classification of Aging as a Disease

Whether or not aging is clearly listed as a disease in the International Classification of Diseases (ICD) maintained by the World Health Organization (WHO) only matters because medical research and development is heavily regulated. Since aging isn't classified as a disease, there is no clear roadmap to obtaining regulatory approval to treat aging with a working rejuvenation therapy, and therefore no investor is willing to commit to funding that work. What happens instead is that the range of biotech companies presently working to produce age-slowing and rejuvenating therapies pick a specific age-related disease to start with, and progress through the regulatory system on that basis. After approval, it will then become something of a political battle of wills between regulators and physicians as to whether widespread off-label use emerges.

So it may or may not make all that much difference at the end of the day as to whether or not the WHO incorporated a clear definition for aging into the ICD-11 as a clearly defined disease. It is probably not going to greatly change the enormous costs imposed on medical development and provision of medical services by the FDA and similar regulatory organizations. Nonetheless, there are factions within the research community that are agitating hard for one outcome or the other, and factions within the WHO that are clearly far more concerned about appearances and ageism than about progress towards therapies that can reduce suffering in old age. It is a circus and probably a waste of effort.

The only thing that will change the behavior of the ponderous, uncaring, regulatory giants is competition. That competition will have to arise in other countries, those more willing to allow therapies, with more reasonably regulatory burdens. Medical tourism is at present disorganized and a small concern in the bigger picture, but when every human over the age of 40 is a potential customer, rather than only the few who are severely ill at any given time, that may well start to change. The existence of effective therapies that are substantially cheaper and more readily available, even given the cost of travel, will put considerable pressure on the regulators who currently act as a roadblock to the mass adoption of these therapies. That hasn't happened yet for senolytics, or fecal microbiota transplantation, or other possibilities, but I think that it will as evidence from clinical trials accumulates.

The debate over whether aging is a disease rages on

Last year, over Canadian Thanksgiving weekend, Kiran Rabheru eagerly joined a call with officials from the World Health Organization (WHO). Word had spread of a change coming to the WHO's International Classification of Diseases (ICD), a catalogue used to standardize disease diagnosis worldwide. In an upcoming revision, the plan was to replace the diagnosis of "senility," a term considered outdated, with something more expansive: "old age." The new phrasing would be filed under a diagnostic category containing "symptoms, signs, or clinical findings." Crucially, the code associated with the diagnosis - a designation that is needed to register new drugs and therapies-included the word "pathological," which could have been interpreted as suggesting that old age is a disease in itself.

Some researchers looked forward to the revision, seeing it as part of the path toward creating and distributing anti-­aging therapies. But Rabheru, a professor at the University of Ottawa and a geriatric psychiatrist at the Ottawa Hospital, feared that these changes would only further ageism. If age alone were presumed to be a disease, that could lead to inadequate care from physicians, he says. Rather than pinpoint exactly what's troubling a patient, a problem could simply be dismissed as a consequence of advanced years.

Rabheru became part of a group that secured the call with the catalogue team. Those on his side presented their arguments and, he says, were "very pleasantly surprised" by the response-a formal review followed by a retraction. On January 1, 2022, the 11th version of the ICD was released without the term "old age" - or language that suggests aging is a disease - in its contents. The decision wasn't welcomed by everyone. "My question to the scientists and doctors who protested the inclusion of old age in their handbook is: What is so threatening?" David Sinclair says. "I would really love to know the motivation, besides just trying to maintain the status quo." Sinclair is also concerned about ageism. But he argues that the best way to combat ageism is to tackle aging: facing the problem head-on by devising treatments to slow its progress. "The current view that aging is acceptable is ageism in itself."

In the years leading up to the debut of ICD-11, a number of researchers argued that linking old age more directly to disease would help the field of longevity research overcome regulatory obstacles, paving the way for drugs designed specifically to treat aging. This issue, however, is seemingly becoming less of a concern as anti-­aging research becomes more mainstream. The US Food and Drug Administration, for example, has said it doesn't consider aging a disease. But in 2015, the agency made the surprising decision to greenlight the Targeting Aging with Metformin (TAME) study, a clinical trial that aims to show that aging can be targeted head-on, by testing whether the diabetes drug metformin can delay the development or progression of chronic diseases associated with aging.

Sinclair sees the WHO's decision as a temporary setback. "Fortunately, the momentum is there from scientists, from the public, from investors. This is going to happen, and changes to some of the language in a document aren't going to stop progress. Still, language is extremely important to how society views problems and potential solutions."

Implicating Cellular Senescence in the Fibrosis and Inflammation of NASH

Nonalcoholic steatohepatitis, NASH, is a condition characterized by chronic inflammation and fibrosis in the liver. Fibrosis is a malfunction of tissue maintenance, the deposition of excessive, scar-like collagen that disrupts tissue structure and function. Like all fibrotic diseases, means of effectively reversing the progression of NASH are presently lacking. NASH is a lifestyle condition, a consequence of fatty liver and obesity, but losing weight and otherwise changing lifestyle will not significantly reverse established fibrosis and loss of liver function. Where fibrosis and inflammation characterize a condition, we might by now expect senescent cells to be involved. Senescent cells secrete pro-growth, pro-inflammatory signals, and there is good evidence for cellular senescence to drive the progression of fibrosis in many tissues, including kidney, heart, and lungs. Thus why not the liver as well?

Cellular senescence is a state of irreversible cell cycle arrest and has been shown to play a key role in many diseases, including metabolic diseases. To investigate the potential contribution of hepatocyte cellular senescence to the metabolic derangements associated with non-alcoholic steatohepatitis (NASH), we treated human hepatocyte cell lines with the senescence-inducing drugs nutlin-3a, doxorubicin, and etoposide. The senescence-associated markers p16, p21, p53, and beta galactosidase were induced upon drug treatment, and this was associated with increased lipid storage, increased expression of lipid transporters and the development of hepatic steatosis.

Drug-induced senescence also led to increased glycogen content, and increased VLDL secretion from hepatocytes. Senescence was also associated with an increase in glucose and fatty acid oxidation capacity, while de novo lipogenesis was decreased. Surprisingly, cellular senescence caused an overall increase in insulin signaling in hepatocytes, with increased insulin-stimulated phosphorylation of insulin receptor, Akt, and MAPK. Together, these data indicate that hepatic senescence plays a causal role in the development of NASH pathogenesis, by modulating glucose and lipid metabolism, favoring steatosis. Our findings contribute to a better understanding of the mechanisms linking cellular senescence and fatty liver disease and support the development of new therapies targeting senescent cells for the treatment of NASH.

Link: https://doi.org/10.3389/fendo.2022.957616

Relationships Between Strength Training and Aerobic Exercise and Late Life Mortality

Both strength training and aerobic exercise independently correlate with improved health and reduced mortality in later life. Animal studies demonstrate causation, in that we'd expect both strength training and aerobic activity to produce the result of improved health and reduced mortality. It is reasonable to proceed on the believe that this will hold up in humans. Meanwhile, here is yet another epidemiological study that shows correlation in a human population, noteworthy for assessing the effects of both strength training and aerobic activity separately in the same study.

It is recommended that older adults (aged ≥65 years) participate in balance training, muscle-strengthening activities (MSAs; ≥2 days per week), and moderate to vigorous aerobic physical activity (MVPA; ≥150 minutes per week at moderate intensity, ≥75 minutes per week at vigorous intensity, or an equivalent combination). In this cohort study, we assessed self-reported leisure time physical activity and deaths among 1998-2018 National Health Interview Survey (NHIS) participants.

Leisure time MSA and MVPA were independently associated with lower all-cause mortality in this cohort study of 115,489 US adults aged 65 years or older. During a mean follow-up of 7.9 years, 44,794 deaths occurred. Adjusting for MVPA, 2 to 3 and 4 to 6 MSA episodes per week (but not 7 to 28 episodes per week) were associated with a lower hazard of all-cause mortality, compared with fewer than 2 episodes. Adjusting for MSA, 10 to 149, 150 to 300, and more than 300 MVPA minutes per week were associated with a lower hazard of all-cause mortality vs less than 10 minutes per week. Combinations of MSA and MVPA had lower hazard estimates.

By using finer age and physical activity categories, a larger sample, and longer follow-up, we build on earlier studies and offer new insights for older adults and their health care professionals. First, the U-shaped dose-response between MSA and mortality, independent of aerobic physical activity, suggests that 2 to 6 episodes per week may be optimal. Second, the age-stratified associations indicate that current physical activity guidelines are important for all older adults, including those aged 85 years or older.

Link: https://doi.org/10.1001/jamanetworkopen.2022.36778

Back to Debating Limits to Human Life Span Again

While it is self-evident that longevity is limited in the practical sense, in that one or more degenerative processes of aging eventually make it so unlikely for survival to continue that everyone dies somewhere before age 120, that doesn't mean that longevity is limited in any other sense. If we alter the consequences of the underlying processes of aging, by repairing the damage that they cause, by changing the process, and so forth, then longevity will increase. While the authors of today's open access paper make generally sensible statements about the nature of aging, they seem far too skeptical that anything of practical use can be achieved in the near future in the field of rejuvenation research. They mount an argument from complexity, against the ability to increase maximum life span from any single intervention into processes of aging, that doesn't seem at all sound to me.

If anything, the demonstrated network of interactions between processes of aging, and between processes and cellular metabolism, is an argument for addressing any one process to be broadly beneficial, eliminating harmful effects throughout cellular biochemistry and tissue function. That evolution has not produced this outcome in any given species is not an argument against the benefits of, for example, removing senescent cells from aging tissues. It is more an argument against the idea that evolutionary selection operates strongly on matters relating to later life. Species lifespan is most likely a consequence of evolutionary pressures operating on the early life environment, a byproduct of that tooth and nail competition, not a selected outcome.

Why Gilgamesh failed: the mechanistic basis of the limits to human lifespan

Thus far, geroscience has been remarkably successful in increasing our insight into aging and convincingly demonstrating that lifespan, at least mean lifespan, as well as healthspan, can be modulated, based on interventions targeting the molecular pathways first discovered in the worm. What it has not done, however, is demonstrate that the maximum lifespan of a vertebrate can be radically extended. The possibility of doing just that, however, is suggested by the large diversity of mortality curves across species.

Confidence in technological progress has now become so high that it has been argued that new medical interventions will soon emerge and radically increase human longevity. Such optimism is the driving force behind the very large sums of money recently donated by billionaires to new organizations active in geroscience. These include: the Methuselah Foundation, which has set up a series of prizes to demonstrate longevity extension in mice; the SENS Research Foundation, which has funded research into aging and rejuvenation; Calico, launched by Google, has engaged in multiple collaborations with academic and commercial researchers; Human Longevity, founded by Craig Venter of human genome fame, and largely focused on a concierge longevity service; and Altos Labs, a newcomer with $3 billion of funding.

Despite their impressive rosters and large cash flows, these organizations face great difficulty in achieving their lofty goals. Currently, there is little consensus as to the cause, or causes, of aging. Most would agree that aging is the result of damage, that is, deleterious changes, that are ultimately molecular in nature. Although preventative measures can be useful, a damage-repair approach, like the one advocated by the SENS Research Foundation and others, will be necessary

While in theory targeting cellular defense systems, including systems for DNA repair, detoxification, immune response and programmed cell death, to boost the quick removal of damage to biological macromolecules, protein aggregates, and senescent cells, should be feasible in the long term, singular causes of aging are conflicting with evolutionary theory. Indeed, if there would be one highly conserved central cause of aging, possibly going back in evolutionary time to the early replicators, multicellular organisms would fall prey to the late-life adverse effects of mutations that accumulate in the germline due to the age-related decline in efficacy of natural selection. This would mean that, independent of any hypothetical central cause of aging, a host of additional adverse late-life effects have to be taken into account.

This would essentially mean that any fix of the limits to lifespan would require interventions at many choke points. Such multipoint targeting would also need to be fine-balanced so as to avoid side effects. Indeed, there are few if any gene regulatory pathways exclusively involved in somatic maintenance and it is this complexity that essentially rules out successful interventions aiming to exclusively extend maximum lifespan of a species. In essence, what needs to be done is to mimic evolution as to how this gave rise to extremely long-lived species, such as those mentioned above, but in real time. As this would involve possibly millions of genetic variants, this seems an impossible quest.

Based on the above, geroscientists should clearly distinguish between mean and maximum lifespan and not give the impression that their research can substantially increase the current limits to human lifespan. Their focus should be on improving life expectancy and healthspan, that is, bringing more people closer to the maximum lifespan possible for members of Homo sapiens and improving the quality of those years.

Repeating the Point that Metformin Just Doesn't Look Good in Animal Studies

Based on studies conducted in mice, metformin is a terrible candidate drug for the treatment of aging. It may well benefit metabolically abnormal individuals, such as diabetics, but results for aged, metabolically normal mice are all over the map. Further, the gold standard, rigorous Interventions Testing Program found no benefit in their assessment. If the goal is to modestly slow aging, then rapamycin is way and far better: robust, replicated results on health and life span in animal studies. But the goal should not be to modestly slow aging! It should be to produce rejuvenation! The sizable fraction of academia and industry that is focused on altering metabolism to provoke greater stress responses and modestly slow aging will, unfortunately, most likely do little to reduce the suffering and death of old age.

The animal study most often cited as evidence that metformin slows aging in lab mice is no such evidence at all. The investigators tested two doses of metformin in healthy, wild-type, nonobese mice. At the lower of the two tested doses, metformin increased the animals' mean survival by a paltry 4-6%, and had no effect on maximum lifespan, meaning that the drug prevented a small number of deaths during and before middle age, but had no effect on aging. And when the mice were given the higher dose of metformin, it actually shortened the animals' lives!

The best animal study to test metformin as a potential anti-aging drug was conducted as part of the National Institute on Aging (NIA)'s Interventions Testing Program: a rigorous, systematic effort to test conventional "messing with metabolism" anti-aging agents. ITP studies are designed with several features that make them a better test than the great majority of studies of whether a potential longevity therapeutic actually works (in mice!). First, each time the ITP tests a potential longevity therapeutic, the lifespan study is done not just once, but three times independently in parallel, with three separate cohorts of mice living out their lives at three independent research sites, cared for by three different groups of scientists. Second, ITP tests all candidate longevity therapeutics in a healthy, genetically-diverse mouse population, which better resembles the normal human population than the genetically homogenous mouse strains widely used in biomedical research.

When the ITP researchers put metformin to the test, the result was unambiguous. It did not extend the lives of the mice at any site. It did not even cause the modest reduction in early deaths seen in the previous, widely-cited study. Metformin simply has no effect at all on lifespan in normal, healthy mice.

Link: https://www.sens.org/tame-attempt-slow-aging-part-1-metformin-in-mice/

Oxidative Stress and Inflammation in Aging Muscles

With advancing age, muscle tissue loses mass and strength, leading to sarcopenia and frailty. A range of mechanisms are thought to contribute to this progressive degeneration, but researchers here suggest that the preventative focus for muscle aging should be placed on ways to reduce oxidative stress and chronic inflammation. These two aspects of aging go hand in hand, linked by a number of different mechanisms, such as the level of damage and altered behavior of mitochondria in cells. Both oxidative stress and inflammation change cell behavior for the worse, and in muscle tissue it may be that reduced activity in the stem cell populations responsible for generating new somatic cells to replace losses are of greatest importance.

With aging, the progressive loss of skeletal muscle will have negative effect on multiple physiological parameters, such as exercise, respiration, thermoregulation, and metabolic homeostasis. Accumulating evidence reveals that oxidative stress and inflammation are the main pathological characteristics of skeletal muscle during aging. Here, we focus on aging-related sarcopenia, summarize the relationship between aging and sarcopenia, and elaborate on aging-mediated oxidative stress and oxidative damage in skeletal muscle and its critical role in the occurrence and development of sarcopenia.

In addition, we discuss the production of excessive reactive oxygen species (ROS) in aging skeletal muscle, which reduces the ability of skeletal muscle satellite cells to participate in muscle regeneration, and analyze the potential molecular mechanism of ROS-mediated mitochondrial dysfunction in aging skeletal muscle. Furthermore, we have also paid extensive attention to the possibility and potential regulatory pathways of skeletal muscle aging and oxidative stress mediate inflammation. Finally, in response to the abnormal activity of oxidative stress and inflammation during aging, we summarize several potential antioxidant and anti-inflammatory strategies for the treatment of sarcopenia, which may provide beneficial help for improving sarcopenia during aging.

Link: https://doi.org/10.3389/fcell.2022.964130

The Burden of Somatic Mutation with Age

Mutational damage occurs constantly to nuclear DNA throughout life. Little of that damage goes unrepaired, and little of the lasting breakage occurs in active parts of the genome. Where mutations go unrepaired in active parts of the genome, little of that occurs in important genes. Where it does occur in important genes, that only matters to the extent that (a) the mutation can spread, and (b) the mutation is potentially cancerous. Comparatively few cells in the body have the capacity to create many descendant cells through replication, as the Hayflick limit ensures that near all cells are limited in the number of times they can divide. The cell population of most tissues turns over with time, removing mutations.

Nonetheless, mutations in precursor cell and stem cell populations, responsible for generating new somatic cells to support a given tissue, can lead to patchwork patterns of those mutations spread throughout the tissue. This is known as somatic mosaicism, and it most likely makes some contribution to both cancer risk and altered tissue function with age.

Beyond this, a more recent suggestion is that double strand breaks, regardless of where in the genome they occur, can deplete cellular resources in ways that provoke epigenetic changes characteristic of aging. This work needs replication and greater support, but it would provide a convenient way to directly link mutation rate with contributions to degenerative aging, explaining many of the observations linking mutational burden with degree of aging. Otherwise, it is challenging to explain why a large fraction of age-related dysfunction should result from mutation, given that the vast majority of mutations don't seem to have much of an effect on cell and tissue function.

Age-related somatic mutation burden in human tissues

There is now absolute consensus that somatic mutations accumulate with age in many if not all human tissues, independent of the method used for mutation evaluation. The mutation frequencies in human tissues and the increase with age are dependent on multiple factors, including environmental mutagens, such as exposure to sun and tobacco smoke.

Importantly, the accumulation rate of somatic mutations in humans differs significantly among different tissues. In this respect, the two extremes are germ tissue and colorectal crypts. The possible reasons are multiple, but the main one seems to be driven by the length of time needed for a cell or tissue type to function. This is likely why germ tissue has a very low somatic mutation burden and the expendable colonic crypts are tolerant for mutation accumulation. The intestinal epithelium is one of the most rapidly dividing regions of cells in the human body and mutations easily accumulate as replication errors. Also tissues exposed directly to high levels of exogenous genotoxicity harbor heavier mutation burdens, such as liver, skin, and lung.

Accumulation of somatic mutations will result in intra-tissue genetic heterogeneity, known as genome mosaicism. Thus far, the impact of genome mosaicism on the aging phenotype, other than cancer, remains unclear. Cancer risk increases exponentially as a function of age in both humans and animals through a mechanism of repeated cycles of somatic mutation (often in interaction with germline variants) and selection for a range of characteristics, including growth, tissue invasion, immune suppression, and metastasis. Accumulating somatic mutations are likely to play a role in the age-related increase in tumor incidence.

Elsewhere we proposed three possible general mechanisms for a functional impact of age-accumulated somatic mutations: (1) clonal expansion, (2) somatic evolution, and (3) mutational networking. The first two are based on clonal expansion of a mutation, either because of a selective advantage or genetic drift. They include hyperplastic or neoplastic disease, although mutations that occur early enough can have late-life effects on postmitotic tissues as well. The third possibility involves the actual adverse effects of high mutation burden on cell functioning, possibly through destabilization of gene regulatory networks. Genomes are robust and redundancy buffers them against mutations. However, when the mutation burden rises to very high levels, the functional organization of genomes in multiple regulatory sequences serving networks of extensively interacting genes will amplify the effects of mutations.

Intermittent Hypoxia Doubles Nematode Life Span

A number of interventions can produce a doubling or greater extension of life span in the nematode C. elegans. Nematode worms demonstrate the plasticity of longevity in short-lived animals, far greater than is the case in long-lived mammals such as our own species. Interventions that alter metabolism in ways that upregulate cellular stress responses, and in doing so produce greatly extended nematode longevity, might be expected to only improve long-term health and add a few years of life in humans. We only have to look at the practice of calorie restriction to see a direct comparison and illustration of this point. Thus while it is interesting to see in this preprint paper that the hypoxia response can be guided to produce a large effect on life span in nematodes, we should not expect that to imply that hypoxia mechanisms are of great worth as a basis for interventions to slow aging in humans.

Genetic activation of the hypoxia response robustly extends lifespan in C. elegans, while environmental hypoxia shows more limited benefit. Here we describe an intermittent hypoxia therapy (IHT) able to double the lifespan of wildtype worms. The lifespan extension observed in IHT does not require HIF-1 but is partially blocked by loss of DAF-16/FOXO. RNAseq analysis shows that IHT triggers a transcriptional state distinct from continuous hypoxia and affects down-stream genes of multiple longevity pathways.

We performed a temperature sensitive forward genetic screen to isolate mutants with delayed nuclear localization of DAF-16 in response to IHT and suppression of IHT longevity. One of these mutations mapped to the enzyme Inositol Polyphosphate MultiKinase (IPMK-1). ipmk-1 mutants, like daf-16 mutants, partially suppress the benefits of IHT, while other effectors of phosphatidyl inositol signaling pathways (PLCβ4, IPPK, Go/) more robustly suppress IHT longevity.

Link: https://doi.org/10.1101/2022.10.13.512140

A Subpopulation of Thymic Cells Can Restore Function to an Aged Thymus

You may recall that researchers have shown that endothelial progenitor cells can restore function to an atrophied thymus. Here, researchers identify a particular subset of functional cells in the thymus that can achieve the same result. The thymus loses active tissue with age, and this loss is a major contribution to the age-related decline of the immune system. The thymus is where thymocytes, created in the bone marrow, mature into new T cells of the adaptive immune system. Absent this supply of T cell reinforcements, the immune system becomes ever more crowded, year after year, with dysfunctional, broken cells. Restoring the aged thymus to enable production of T cells one more is an important goal for the rejuvenation research community.

Thymic atrophy and the progressive immune decline that accompanies it is a major health problem, chronically with age and acutely with immune injury. No solution has been defined. Here we demonstrate that one of the three mesenchymal cell subsets identified by single-cell analysis of human and mouse thymic stroma is a critical niche component for T lymphopoiesis. The Postn+ subset is located perivascularly in the cortical-medullary junction, medulla and subcapsular regions.

Cell depletion demonstrated that this cell population recruits T competent cells to the thymus and initiates T lymphopoiesis in vivo. This subset distinctively expresses the chemokine Ccl19 necessary for niche functions. It markedly declines with age and in the acute setting of hematopoietic stem cell transplant conditioning. When isolated and adoptively transferred, these cells durably engrafted the atrophic thymus, recruited early T progenitors, increased T cell neogenesis, expanded T cell receptor complexity and enhanced T cell response to vaccination. These data define a thymus lymphopoietic niche cell type that may be manipulated therapeutically to regenerate T lymphopoiesis.

Link: https://doi.org/10.1101/2022.10.12.511184

There is Such a Thing as Too Much of a Focus on Low-Hanging Fruit in the Longevity Industry

The longevity industry includes a few companies that will genuinely revolutionize the medical industry, such as Maia Biotechnology, the first deployment of a near-universal cancer therapy based on targeting telomerase activity. For every such gem there are, unfortunately, a half dozen companies that are marketing dietary supplements and the like that will do just about nothing to change the human condition. It is a great deal easier to market a supplement than it is to revolutionize the medical industry by developing a completely new biotechnology, and this truth has a significant impact on the funding available to a company based on their strategy of choice.

Venture funds that invest in biotech startups obtain their funds from limited partners, ranging from high net worth individuals to large holding companies. The venture partners running the fund are the industry experts, while the limited partners tend to know a lot less about the markets that they invest in. They are, in effect, hiring the venture fund to manage this opportunity. However, venture funds exist in a competitive marketplace for limited partner funds, and limited partners are primarily interested in financial outcomes rather than changing the world. Thus we see that all too many funds, company builders, and the like that focus on the longevity industry choose to make only safe, incremental investments in companies that are working on safe, incremental projects that cannot even in principle produce large gains in health and longevity.

In the article I want to point out today, Maximon is one such example. I'm not singling out the Maximon principals for any reason other than the fact that they drifted past my eyes recently; numerous other funds have taken the same approach, and just haven't spoken in public on the topic of their investment strategies of late. All use the current hype for longevity in order to obtain limited partner investment, and then fund projects that are prioritized by how likely they are to keep the limited partners happy with the bottom line at the end of the day. Unfortunately, a safe project in this context usually means that it is unambitious and unlikely to greatly affect the bottom line of human health. Is this outcome the fault of the limited partners, the venture partners, the entrepreneurs, or all three? There is a question to think on.

Meet the company builders that think they can reverse ageing

Marc Bernegger, a former crypto entrepreneur, cofounded the longevity company builder Maximon in 2021. He and his partners ran a two-day longevity investor conference last month in Gstaad in the Swiss Alps. The agenda included both investments opportunities and an overview of scientific research, with speakers including the investor Christian Angermayer and Eric Verdin, CEO of the Buck Institute for Research on Aging. "We had quite a few billionaires flying in from all over the world. That is a good indication that there's now serious money coming into this field. And having some well-known guests coming to an event like this makes it more tangible for investors," Bernegger says. The enthusiasm, and the capital, for the field is there - the longevity market is projected to reach $44bn by 2030 - but time is, ironically, not on this industry's side.

Maximon's strategy is to look for more low-hanging fruits, says Bernegger. So far, the company builder has invested in Swiss supplement startup Avea and Biolytica, another Swiss startup which is combining health data analytics and personalised longevity programmes. Bernegger believes that although a lot of longevity supplements, such as NMN and NAD+ boosters, already exist on the global market, the "made in Switzerland" selling point will be beneficial to lure customers away from other brands, as well as attract new customers. Low-hanging fruit or not, Maximon is looking for ways to bring longevity technology to the masses. One way to do this - as both organisations are already about to - is by building longevity clinics, where people can go and find out what supplements and treatments would be beneficial to them on a personal level.

RNA Splicing Dysfunction in Alzheimer's Disease

RNA splicing is the process by which RNA is assembled from portions of a gene, joining exon sequences together while omitting intron sequences. Like all aspects of cellular biochemistry, RNA splicing runs awry with age in a variety of ways, and this is thought to lead to dysfunction in cells. Here, researchers dive into a very specific issue in RNA splicing that appears associated with Alzheimer's disease, though as always in this sort of research one has to ask whether the effect size is meaningful, and whether the animal models are decent reflections of what happens in humans. Mice do not naturally develop Alzheimer's, and so the models all are based on some assumptions about the important mechanisms; those assumptions may produce dementia in mice, but may or may not be relevant to the human condition.

Researchers previously revealed that a specific component of the RNA splicing machinery, called the U1 small nuclear ribonucleoprotein (snRNP), creates aggregates in the brains of individuals with Alzheimer's. The U1 snRNP complex is essential in RNA splicing. Now, the team have demonstrated that the dysfunction of the U1 snRNP contributes to neurodegeneration, opening new avenues of research for Alzheimer's treatment. The study found that RNA splicing dysfunction due to U1 snRNP pathology helps cause neurodegeneration.

The researchers created a novel mouse model of RNA splicing defects called N40K-Tg. The scientists observed basic neurodegeneration when they deregulated the splicing machinery, but they wanted to understand why that was the case. Inhibitory neuron activity prevents the brain from getting over-excited. If the inhibitory neuron activity is repressed, the neurons become more active, but it can cause toxicity. The researchers found a significant impact on synaptic proteins in the new mouse model, in particular the proteins involved in inhibitory neuron activity. "Excitatory toxicity is very important because it is already known in the Alzheimer's disease field. Even 20-30 years ago, people recognized that neurons become super excited, and now we find that the splicing machinery may be contributing to the excitatory toxicity observed in Alzheimer's patients."

Link: https://www.stjude.org/media-resources/news-releases/2022-medicine-science-news/how-rna-splicing-defects-contribute-to-alzheimers-disease.html

Senescent Cells in Muscle Tissue Harm Muscle Stem Cell Function

Researchers here use fisetin as a senolytic in progeroid mice to demonstrate that senescent cells in muscle tissue are harmful to tissue function via a negative impact on muscle stem cells. Mice with this form of progeroid mutation generate a lot of senescent cells, far more than occurs during normal aging, but the principle may nonetheless hold, that senescent cells are providing a meaningful contribution to age-related loss of muscle mass and strength. The proof lies in running the studies.

Muscle progenitor/stem cells (MPCs) progressively lose their capacity for proliferation and myogenic differentiation during the ageing process, likely through both autonomous and non-autonomous mechanisms. The cell autonomous mechanism mainly involves increased DNA damage, telomere shortening, and activation of chronic inflammatory signalling (i.e. NF-κB), whereas the cell non-autonomous mechanism involves the regulatory roles of other types of neighbouring cells in the tissues on the function of local stem cells. However, the mechanism of MPCs being regulated by neighbouring cells during the ageing process of muscles remains largely unknown.

Adjacent to MPCs in the skeletal muscle are myofibres, immune cells, blood vessel endothelial cells and fibro-adipogenic progenitors (FAPs). FAPs are tissue-resident mesenchymal stromal cells (MSCs) characterized by the high expression of PDGFR-α that play important roles in the homeostasis and repair of multiple tissues. By studying the muscles and primary cells of age matched wild-type (WT) mice and Zmpste24-/- (Z24-/-) mice, an accelerated ageing model for Hutchinson-Gilford progeria syndrome (HGPS), we examined the interaction between FAPs and MPCs in progeria-aged muscle, and the potential effect of senolytic drug fisetin in removing senescent FAPs and improving the function of MPCs.

We observed that, compared with muscles of WT mice, muscles of Z24-/- mice contained a significantly increased number of FAPs (2.4-fold) and decreased number of MPCs (2.8-fold). FAPs isolated from Z24-/- muscle contained about 44% SA-β-gal+ senescent cells, in contrast to about 3.5% senescent cells in FAPs isolated from WT muscle. The treatment of the in vitro co-culture system of Z24-/- FAPs and WT MPCs with the senolytic drug fisetin led to increased apoptosis of Z24-/- FAPs (14.5-fold) and rescued the impaired function of MPCs by increasing the number of MHC-positive myotubes for 3.1 times. Treatment of Z24-/- mice with fisetin in vivo was effective in reducing the number of senescent FAPs and restoring the number of muscle stem cells (2.6-fold), leading to improved muscle pathology in Z24-/- mice.

These results indicate that the application of senolytics in the progeria-aged muscles can be an efficient strategy to remove senescent cells, including senescent FAPs, which results in improved function of muscle progenitor/stem cells. The senescent FAPs can be a potential novel target for therapeutic treatment of progeria ageing related muscle diseases.

Link: https://doi.org/10.1002/jcsm.13101

A View of the Road Ahead to Viable Xenotransplantation

In principle, engineering pig organs to survive in humans is a viable project for this age of biotechnology. Pig organs are the right size, and strategies exist to address the known issues in rejection of tissues, transfer of retroviruses, and the like. An entire industry is coming into being based on enabling cells and tissues from one individual to be introduced into another without rejection. Much of the work needed to make that possible between individuals of the same species also enables transplantation between species.

In a world in which organs fail, and transplants are in limited supply, there are several roads ahead towards providing an unlimited, on-demand supply of replacements. Xenotransplantation is one of them, farming engineering pigs for their organs. Secondly, there is decellularization, taking a donor organ and stripping it of cells, leaving the extracellular matrix and all of its chemical cues, before introducing the recipient's cells to repopulate the empty organ. Further, researchers are working to be able to build organs from scratch, from a cell sample. This is a challenging process in which the major hurdle remains the establishment of complex small-scale capillary networks. Lastly, there is the longer-term prospect of entirely artificial, machine organs, a field that receives less attention and seems likely to fall behind given advances in biotechnology.

It has hard to say which of the biological approaches will win out in the next few decades. Many of the difficulties are yet to be discovered in each case. Xenotransplantation is running at ahead of the others at this stage, but equally, as the first human studies are conducted, this is where the unknown difficulties start to arise.

Developing pig-to-human organ transplants

Over 100,000 people in the US are currently waiting for organ transplants. Because the human organ donor pool cannot keep pace with this demand, many patients die without receiving the life-saving transplant they need. Pigs are similar to humans in organ size and physiology, so the transplantation of pig organs to humans offers a potential solution to this problem and raises the prospect of scheduled, elective transplantation of quality-controlled organs, even for patients who would not currently meet the criteria for allocation of a scarce human organ. Although other technologies, such as tissue engineering, may eventually offer alternative solutions to this shortage, there is currently no substitute for transplantation of a fully formed, functioning organ. Several developments in the past year, most notably the first pig-to-human transplants, bring this promising solution closer to fruition, but challenges remain.

Transplants from one species to another are called xenotransplants. Because nonhuman primates (NHPs) are closest to humans phylogenetically, early human xenotransplantation efforts used NHP organs. However, graft survivals were short, and the use of NHPs for xenotransplantation was later deemed to be unsafe owing to potential virus transmission, impractical because of limited animal availability, and more ethically challenging than the use of pigs, which consequently became the xenograft source animal of choice. However, transplantation of pig organs into NHPs resulted in rapid "hyperacute" rejection (HAR) owing to the binding of preexisting "natural" antibodies (NAbs) in the NHP to targets on endothelial cells lining the transplant organ's blood vessels. Activation of complement and coagulation cascades then resulted in ischemic organ death within minutes to hours.

NAbs exist in the absence of any known exposure to pig tissues owing to cross-reaction with antigens that are shared by common microbes. During the 1990s, pigs transgenically expressing human complement regulatory proteins were developed, and it was discovered that most human and NHP anti-pig NAbs recognize a single carbohydrate, α-galactose-1,3-galactose (Gal), making it possible to remove these antibodies by adsorption. These advances extended the survival of pig organs to days or weeks in NHPs. Enthusiasm for xenotransplantation was nevertheless dampened by the identification of porcine endogenous retroviruses (PERVs) and concerns about the possibility that new viral illnesses might arise in humans as a result.

Guidelines have been developed to mitigate the risk of pathogen transmission from pigs to humans. Notably, PERV infection has not been detected in any pig-to-human or pig-to-NHP transplant recipient, although PERVs may have lower affinity for NHP forms of its receptor than of the human receptor. PERV loci have also been suppressed or deleted from some pigs, further improving safety. Consequently, there is broader acceptance of the likely safety of pig-to-human xenotransplantation with appropriate animal husbandry and microbial surveillance of the source animals, recipients, and their close contacts.

These encouraging developments have set the stage to proceed with clinical xenotransplantation. The first trials of pig-to-human organ xenotransplantation took place in 2021.

LXA4 Levels in the Brain Decrease With Age, Perhaps Increasing Inflammation and Accelerating Neurodegeneration

Chronic inflammation in brain tissue is connected to the onset and progression of neurodegenerative conditions, so it is reasonable to expect that researchers will, from time to time, discover evidence for regulators of inflammation to be involved in aging and neurodegeneration. Here, scientists discuss LXA4, which has a role in resolution of the inflammatory response, and declines in abundance with age. Delivery of LXA4 produces functional benefits and greater resistance to inflammation in mouse models, making it a potentially interesting target for the development of therapies. The question, as always for attempts to suppress age-related inflammation, is whether this will reduce pathological, excess inflammation only, leaving necessary inflammation untouched. The side-effects of reducing necessary inflammation include increased cancer risk and vulnerability to pathogens, particularly undesirable in later life.

Age increases the risk for cognitive impairment and is the single major risk factor for Alzheimer's disease (AD), the most prevalent form of dementia in the elderly. The pathophysiological processes triggered by aging that render the brain vulnerable to dementia involve, at least in part, changes in inflammatory mediators.

Here we show that lipoxin A4 (LXA4), a lipid mediator of inflammation resolution known to stimulate endocannabinoid signaling in the brain, is reduced in the aging central nervous system. We demonstrate that genetic suppression of 5-lipoxygenase (5-LOX), the enzyme mediating LXA4 synthesis, promotes learning impairment in mice. Conversely, administration of exogenous LXA4 attenuated cytokine production and memory loss induced by inflammation in mice.

We further show that cerebrospinal fluid LXA4 is reduced in patients with dementia and positively associated with cognitive performance, brain-derived neurotrophic factor (BDNF), and AD-linked amyloid-β. Our findings suggest that reduced LXA4 levels may lead to vulnerability to age-related cognitive disorders and that promoting LXA4 signaling may comprise an effective strategy to prevent early cognitive decline in AD.

Link: https://doi.org/10.1038/s41398-022-02208-1

Cognitive Impairment Indicative of Later Dementia can be Detected Early

Researchers here present epidemiological evidence from a large population database to suggest that measurable cognitive decline occurs quite early in the progression towards dementia, years before diagnosis. Thus better screening could open the door for widespread use of existing preventative interventions and the development of new and better preventative interventions. Prevention is almost always an easier prospect than effective treatment of later stage disease, and something to be encouraged.

Neurodegenerative diseases present a significant health, social, and economic burden. Disease-modifying therapies and effective preventive strategies are lacking. Treatment trials are typically conducted after symptoms have emerged, which may be too late in the disease process to alter its course. Understanding the earliest, pre-diagnostic phase in neurodegenerative disease could open opportunities for more effective preventive and treatment trials.

We use UK Biobank data demonstrate cognitive and functional antecedents of several idiopathic neurodegenerative syndromes in the years prior to diagnosis. In line with findings of pre-symptomatic cognitive decline in familial mutation carriers of Alzheimer's disease and frontotemporal dementia, these changes were identified at a baseline assessment averaging 5 to 9 years before diagnosis. The pre-diagnostic linear decline in a number of measures supports our supposition that these changes represent early progressive neurodegeneration rather than a low cognitive or functional baseline.

Link: https://doi.org/10.1002/alz.12802

Notes from the Rejuvenation Startup Summit, Held in Berlin in October 2022

A fair number of longevity industry and related companies presented this past weekend in Berlin, at the Rejuvenation Startup Summit hosted by the Forever Healthy Foundation. Unlike the past Undoing Aging events, this is much more focused on the industry rather than on scientific programs, but there was nonetheless a great deal of science on display. I took a few notes in between other activities, for posterity. As Michael Greve noted in his introduction to the participants, these are the early years of what will become the largest industry on the planet. Everyone ages, and everyone is a customer for the rejuvenation therapies and related technologies that lie just around the corner.

Eric Verdin of the Buck Institute gave the opening keynote, discussing recent work on biomarkers of aging, and specifically the most promising line of epigenetic clocks based on assessment of DNA methylation status. Given ways to reliably extend life in mice (e.g. rapamycin and senolytics), we now need a way to measure that outcome that doesn't involve waiting around for the results of a life span study. The point made in this presentation was that different immune cell populations exhibit sizable differences in assessed epigenetic age, which probably means that all clock data based on blood samples is suspect. The Buck Institute researchers have found differences of as much as ~20 years in epigenetic age between immune cell types, as well as differences based on infection and inflammation status, so clearly more care needs to be taken here. In an attempt to address this issue, the team built a new clock that is invariant across immune cell subpopulations. We will no doubt be hearing more about this as it progresses, given the prevalence of work that uses epigenetic age derived from blood samples.

Lou Hawthorne of Nanotics gave an outline of their technology platform, a way to produce particles that bind specific molecules in the blood stream in a controllable way, depleting them for minutes to hours. Heterochronic parabiosis research has led to evidence for harmful factors to circulate in the aged bloodstream, maintaining inflammation and dysfunction, which naturally leads to the desire to remove these factors in a targeted way. Nanotics is particularly focused on pro-inflammatory factors, and their view of aging is inflammation-centric. Thus the cytokine storm of sepsis is not a bad starting place to test this sort of therapy in the clinic. The Nanotics platform allows the targeting of signal processes that are inaccessible to small molecule therapeutics, so offers ways to potentially dial down inflammatory signaling without also blocking necessary immune functions.

Alexander Schueller of cellvie discussed their view of the mitochondrial dysfunction observed in aging, and the relevance of mitochondrial damage caused by ischemia to the cell death and dysfunction following ischemic injury. The cellvie approach is to deliver replacement mitochondria to be taken up by cells in need. Like the other companies working on this approach, they are near entirely focused on the logistics and process development needed for this goal. Their intent to is to generate allogeneic mitochondria, harvested from standard cell lines. Once ready, cellvie is looking at sarcopenia as a first indication for clinical development, based on promising animal data.

Vlad Vitoc of Maia Biotechnology gave an impressive overview of their progress towards a near-universal cancer therapy. They develop therapies based delivery of THIO, a compound that is metabolised and utilized by telomerase, and then incorporated into telomeres to produce cell death. Since near all cancer cells aggressively utilize telomerase, these are the cells that die when THIO is introduced. The company has orphan drug designations for a variety of cancers, and are well advanced in the path to clinical trials. A first phase 1 is running now, with further trials coming up in next few years, including one phase 2 just starting in Australia. These trials are conducted in partnership with Regeneron, and they put THIO into patients in conjunction with a Regeneron-developed checkpoint inhibitor therapy. The company went public recently, and they are using the sizable funding they have raised to date in order to build new and more efficient versions of THIO. We should expect the important questions regarding telomerase as a target to be answered in the years ahead, now that it is an ongoing project, such as how to manage the effects of telomerase-targeted therapeutics on stem cell function, and what those effects are in practice.

Chris Rinsch of Amazentis talked about the use of urolithin A as supplement-based approach to improving mitochondrial function in aged individuals. Their initial aim is to look at muscle function in aging, attempting to produce modest improvements via this approach. They hold the consensus view that urolithin A works by improving both mitophagy and mitochondrial biosynthesis, though as for many such compounds exactly how it achieves this outcome is far from settled.

Unfortunately, I had to miss the presentation by Alex Blyth of LifT Biosciences. This company pursues an interesting approach to cancer via transplantation of donor leukocytes; you might recall the original work on granulocyte transfer presented at SENS meetings back in the day. The original research showed great promise, and the company has been doing well these past few years, judging from the public updates.

Dobri Kiprov of Lyfspn presented on the merits of therapeutic plasma exchange. He presented a range of human data from patients in past years, including a reduction of epigenetic age via this approach, as well as immune improvements, improvement in joint issues, and improved liver and kidney function. Their view is that the most important aspect of this removal of bad factors is that it modulates the immune system, reducing the state of inflammaging and consequent harm and dysfunction. But the data they have is not rigorous, it results from clinical practice, and thus they founded this company to generate high quality data via clinical trials. They acknowledge that these are still the early days for therapeutic plasma exchange, and they still lack firm, defensible answers to even simple questions such as how long the benefits last from one treatment.

Pankaj Kapahi of Juvify discussed the science supporting this supplement company spinout from the Buck Institute. Their product is a modulator of glycation, acting to reducing the impact of sugar consumption and obesity on long-term health. Their hypothesis is that the generation of advanced glycation endproducts (AGEs) is the major problem that is produced by sugar metabolism. They work with compounds that target one type of shorter-lived AGE, methylglycoxal AGEs. Thus benefits may be a matter of reducing inflammatory signaling caused by AGEs via the RAGE pathway, but they think that RAGE is not the only mechanism of interest here. Interestingly, these compounds suppress appetite, so somehow short-lived AGEs are acting as appetite enhancers. Ongoing studies in mice also indicate that this interference in short-lived AGEs, conducted over the long term, decreases growth hormone signaling and reduces the burden of cellular senescence, among other benefits. Since appetite is reduced, is it possible that the benefits are all simply benefits of calorie restriction? They think that this is a factor, but only part of story.

Yuri Deigin of Youth Bio presented on partial reprogramming, a huge potential market, based on evidence from animal studies showing rejuvenation in many different tissues. Certainly, investors believe it will be huge, judging by the vast financial support for this part of the industry, dwarfing investment elsewhere. Youth Bio are an early stage preclinical company, at the point of having completed mouse studies showing reversal of measures of aging. They are working on a few different projects in parallel. Firstly they are attempting to produce new reprogramming approaches with novel factors and tissue-specificity. They avoid the liver and intestine for safety reasons, as mice tend to die when these are repeatedly reprogrammed. Secondly, they are working towards viable therapies based on use of the existing OSKM factors. Alzheimer's disease is their first indication on this side of the house, and they propose the use of a one-time gene therapy that introduces inducible genes, followed by delivery of small molecules for periodic activation of those genes.

Silke Hüttner of Rejuvenate Biomed outlined their approach to combinatorial therapies using small molecules identified through screening and later optimization. They are, unfortunately, cagey about the details of their compounds, but their present lead therapeutic candidate is a combination of two compounds that they have developed, which positively affects inflammation and other properties relevant to aging. The company is initially focused on sarcopenia, but they want to move on from there to other age-related conditions and then aging itself as a target. The company has produced successful studies in both progeroid mice and naturally aged mice, with early human trials ongoing.

Mourad Topors presented as the CSO of Repair Biotechnologies, the company that I co-founded with Bill Cherman. We develop a means of safely breaking down excess intracellular free cholesterol, delivered as a gene therapy to arbitrary cells in the body, or as a cell therapy of engineered cells equipped with this capability. We work towards reversal of atherosclerosis, the primary cause of human mortality, resulting at root from the presence of excessive cholesterol deposits in arterial walls. We are finding a faster path to the clinic in treatment of nonalcoholic steatohepatitis (NASH), however, largely because the delivery systems for liver-targeted gene therapies are far more developed. We presented recent results showing reversal of liver inflammation and fibrosis in NASH model mice, and noted that we're raising funds to start our clinical development program leading to human trials. Therapies to reverse atherosclerosis progression will follow shortly on the heels of this work on NASH.

Robin Mansukhani of Deciduous Therapeutics discussed their approach to immune system modulation via small molecules, training invariant natural killer cells to attack senescent cells. The point was made that engaging the immune system may be a way to work around many of the present unknowns regarding senescent cell status, biomarkers, and subtypes. Interestingly, a one-time treatment via their approach rouses immune cells for at least months thereafter, consistently clearing senescent cells over that time.

Mike Kope of Cyclarity presented on their approach. Cyclarity is the renamed Underdog Pharmaceuticals, a spinout from the SENS Research Foundation that employs engineered cyclodextrins to bind 7-ketocholesterol. This is essentially a test of the degree to which 7-ketocholesterol is a meaningful cause of pathology in human atherosclerosis and other conditions. They have great cell data, showing that they can reverse the foam cell state that arises from 7-ketocholesterol exposure, and they also test in human plaques obtained from cadavers and surgical procedures. Despite a lack of animal models for 7-ketocholesterol presence in atherosclerotic disease, Clarity has engineered a fast path to the clinic, based on the safety profile of cyclodextrins as a class. They will begin their first clinical trials next year.

Cristiana Banila of Mitra Bio discussed the need for better ways to measure skin aging. They have developed a way to measure epigenetic age in skin non-invasively, with no biopsy. They obtain cells from the skin surface via adhesive tape and have shown that this produces the same results as are obtained using biopsies. The company uses this approach to assess methods that are alleged to reverse skin aging, and presented data for an example treatment that can in fact reverse epigenetic age in UV-damaged skin. They plan to test many more of the established and potential skin-focused interventions that exist, to generate personalized recommendations for patients.

Brian Kennedy talked about his scientific work at the National University of Singapore. This spans a range of preclinical studies, including efforts to produce treatments based on the hallmarks of aging and work on biomarkers and epigenetic clocks. They tend to run 6-9 month interventions in mice, starting at 18 months of age, and assessing frailty and biomarkers of aging rather than using life span as a measure of success. Similarly, they run human studies, presently small ones, and again 6-9 months of intervention in healthy older people, while assessing biomarkers. The researchers are focused on the standard panoply of well-known small molecule geroprotectors, such as rapamycin, largely calorie restriction mimetics. In nematode worms, the development of automation now allows this research group to run studies of combinations of such compounds, tens of thousands of these studies every year; this capacity has led to a new company that intends to ramp up to millions of studies or more per year. One of the more interesting conclusions from the work carried out to date is that combinations produce unexpected results. The individual outcome of two small molecules is no guide as whether the combination will be better, worse, or indifferent. Any and all polypharmacy, or even combination of supplements, is a walk in the dark.

Chris Shepard of Thymofox gave an overview of the importance of thymic involution to the aging of the immune function. The insight leading to the creation of this company is that a young thymus regenerates from injury, but this capacity is much reduced in adults, and further so with aging. They are looking for the regulators of this decline, upstream of FOXN1. They aim to produce small molecules to indirectly upregulate FOXN1 expression in the thymus, searching via a high-throughput screen they they designed. They believe that along the way so far they have discovered some genetic regulators of FOXN1 level that may be useful in other ways, but details on their progress to date are light.

Mark Allen of Elevian gave his outline on their work on GDF11, one of the first candidate factors for the effects of parabiosis, back when it was though that the effects of parabiosis might be mediated by beneficial factors in young blood, rather than a dilution of harmful factors in old blood. This line of research has been underway for a while now, and they are narrowed down to applications in stroke recovery as the first clinical indication. Their evidence in mice shows recombinant GDF11 to promote vascular regeneration, activate various stem cell and progenitor cell populations, suppress inflammatory to some degree, and improves metabolism. They think that indications could be addressed via GDF11 therapies, and the first clinical trial for stroke recovery will begin in 2023. Further, they have identified an regulatory responsible for the age-related downregulation of GDF11 expression, and are working towards an antibody therapy as an alternative to delivery of recombinant GDF11.

Matthias Breugelmans of Elastrin Therapeutics discussed the regeneration of damaged elastin fibers in the extracellular matrix to restore elasticity in aged tissues. The company employs an albumin nanoparticle decorated with antibodies that bind to damaged elastin to deliver their therapy in a very targeted way. The nanoparticle contains EDTA and a proprietary PGG compound. In their eyes, damaged elastin in blood vessels and other tissues produces a local inflammatory response which in turn provokes calcification and other woes. They are targeting a variety of indications, including vascular calcification, aneurysm, hypertension, and a few rare orphan conditions. The company has obtained large reductions of vascular calcification in animal models, and a first phase 1 trial starts in 2023. Beyond the nanoparticle approach, they are working with delivery of mRNA encoding tropoelastin in order to stimulate the production of new elastin, but this is quite new, and earlier in development.

Matthew Rosen of CoRegen outlined a regulatory T-cell (Treg) based approach to defeating many different types of cancer. This is a spin out from Baylor College of Medicine, and uses the college infrastructure. One of the ways in which solid tumors subvert the immune system is to co-opt Treg cells, which then prevent other immune cells from attacking the cancer. Researchers have seen that gene knockdown of SRC-3 in Tregs will stop this from happening, however, and the CoRegen therapy is based on this finding. SRC-3 controls a lot of other genes, including checkpoint inhibitors, and it is thus fair to say it is a master regulator of immune capabilities against cancer. The company engineers Tregs by knocking out SRC-3, and then injects those cells, either systemically or into a tumor. This appears to provide lasting benefits in terms of resistance to cancer, and complete remission of existing cancer in mice: a small number of engineered Tregs outweighs the effects of native Tregs. The company is aiming at a first phase 1 in 2023.

Peter Fedichev of Gero presented on the company's use of AI and animal models to characterize the split of degenerative aging into two quite different processes, which they term (a) damage (or frailty) and (b) loss of resilience. These are two quite different things, and the balance between these portions of aging is different in mice and humans. Humans are more resilient, meaning a greater resistance to perturbations to equilibrium in later life. In the Gero view, the hallmarks of aging are all linked, and a drug working on any one will have effects on all. They predict that most small molecules that slow aging in mice will have little effect on aging in healthy humans, because humans are already resilient in ways that mice are not. The company is running drug discovery programs based on this philosophy, and beginning to collaborate with big pharma entities.

Aaron Cravens of Revel Pharmaceuticals presented the company as developing a platform to produce enzyme therapies generally, at a fraction of the cost and time of past efforts. High throughput enzyme engineering, in essence. They use computational modelling of enzyme libraries to suggest new variants and desired properties, then validate in vitro. You will recall that they launched to work on enzymes to break glucosepane, CML, and other cross-links involved in aging, and that remains the initial application of their platform. This is an early stage effort, and they have not yet tested candidate molecules in animals. They intend to raise a series A next year.

Hans S. Keirstead outlined work under way at Immunis, one of the more advanced of the companies presenting at the event. They harvest the secretome of carefully tailored progenitor cell lines, and package those molecules as a therapeutic product. The result contains factors that can modulate the immune system, as well as provide other useful effects on cell behavior. This program is fairly advanced in its progression through the IND process with the FDA. They have demonstrated in IND-enabling studies that delivery of this secretome as a therapeutic helps with sarcopenia and fibrosis, reduces inflammation and arterial stiffness, and improves adaptive immunity. A phase 2 human trial for muscle atrophy is starting up now.

Robert Cargill of Glionics presented work on the use of engineered microglia to deliver therapeutic molecules throughout the brain. It is otherwise hard to get many types of compound into the brain, with good biodistribution, because of the blood-brain barrier. But microglia will naturally spread throughout the brain, provided that native microglia are cleared via some form of CSF1R inhibitor. The company is starting with klotho as the therapeutic molecule of choice. They have demonstrated repopulation following clearance in mice. Just a few thousand microglia will replicate and move throughout the brain, delivering a factor as they go, BDNF in that case. The intent is to generate therapeutic microglia from universal iPSC lines, a popular choice in research and development at the moment.

Rob Konrad Maciejewski of Biolytica outlined a vision for data-driven approach to personalized medicine and lifestyle changes. This is a software company; they build a visualization product for complex health data in order to help patients understand tests, make choices, aim towards goals, and navigate the sizable amount of data that can be obtained these. Then on top of that add recommendations for lifestyle and supplement choices, and managing relationships with doctors and providers. The initial aim is to help people who could in principle make sizable gains in long-term health via lifestyle changes to make use of the present medical assay environment in order to achieve those gains.

Joshua McClure of Maxwell Biosciences presented on their drug discovery platform, based on producing variations on an antimicrobial peptide that is effective against pathogens of many types, including fungi, bacteria, and viruses. The story started with examination of blood plasma from young and old mice, finding a heat shock protein LL-37, a protein that is also an antimicrobial peptide that (a) seems to have broadly beneficial effects on many systems and (b) is downregulated with age. It attacks many targets from cancers to pathogens, acting via membrane disruption. Unfortunately it can't be used as a drug, as is rapidly cleared from circulation, so instead the company makes similar peptides that have the same function while also being stable. This can be, in principle, a replacement for existing antibiotics and antivirals, with additional beneficial effects to health via heat shock protein mechanisms. The company is quite well advanced in their preclinical program, and intends to raise sizable amounts for clinical development in the coming year.

Sophie Chabloz presented on Avea, a standard issue modern dietary supplement company. They presently offer formulations incorporating nicotinamide mononucleotide and the like, aiming to produce NAD+ upregulation.

Felix Frueh of PAGE Therapeutics discussed the value of targeting metastasis in cancer therapy. Prevention of metastasis would make solid tumors far less dangerous, in any cancer. The company pursues an interesting mechanism: cancers produce circulating tumor cells, but only clusters of these circulating cells actually produce metastasis, not single cells. So why not dissolve the clusters? They found an existing drug that achieves this outcome and blocks metastasis in mice. This can then be combined with other cancer therapeutics. A trial in breast cancer patients is ongoing as a proof of concept. Despite all of this backstory from academia, they are actually in quite an early stage as a company, working to produce novel small molecule drugs targeting this cancer cell clustering mechanism via screening.

Jürgen Reeß of the very early stage company Mogling Bio introduced their work aimed at restoration of immune function in older individuals. They wish to use derivatives of CASIN to inhibit CDC42, shown in academic work to rejuvenate the immune system with a single treatment. CASIN appears to improve function in stem cell populations generally, but in the case of hematopoietic stem cells this leads to an improved, more youthful production of immune cells. The company is just getting starting, based on promising mouse data, and will target the obvious indications relating to age-related immune dysfunction.

All told, it was quite an interesting selection of ongoing work. The cancer side of the house in particular is looking very promising these days, with numerous quite general approaches under development that should be both effective and applicable to many different types of cancer.

SFRP4 Knockdown Suppresses the Senescence-Associated Secretory Phenotype in Senescent Skin Cells

Researchers here note that SFRP4 is expressed in aged skin cells, and especially in senescent skin cells. Gene knockdown of SFRP4 in mice was shown to reduce the harmful signaling generated by these cells, the senescence-associated secretory phenotype (SASP), and improve measures of skin aging in the treated animals. On the whole, modulating the SASP seems a poor strategy in comparison to selectively destroying senescent cells with senolytic therapies. For one, a SASP-suppressing treatment is unlikely to suppress all of the diverse molecular components of the SASP, and secondly has to be taken continuously over time. A senolytic treatment definitely gets rid of the SASP, whether or not researchers can currently measure it, and needs to be taken only intermittently.

There is growing evidence that the appearance and texture of the skin that is altered during the aging process are considerably enhanced by the accumulation of senescent dermal fibroblasts. These senescent cells magnify aging via an inflammatory, histolytic, and senescence-associated secretory phenotype (SASP). Secreted frizzled-related protein 4 (SFRP4) was previously determined to be expressed in dermal fibroblasts of aging skin, and its increased expression has been shown to promote cellular senescence. However, its role in the SASP remains unknown.

We found that SFRP4 was significantly expressed in p16ink4a-positive human skin fibroblasts and that treatment with recombinant SFRP4 promoted SASP and senescence, whereas siRNA knockdown of SFRP4 suppressed SASP. Furthermore, we found that knockdown of SFRP4 in mouse skin ameliorates age-related reduction of subcutaneous adipose tissue, panniculus carnosus muscle layer, and thinning and dispersion of collagen fibers. These findings suggest a potential candidate for the development of new skin rejuvenation therapies that suppress SASP.

Link: https://doi.org/10.18632/aging.204273

Amyloid-β Binding Exosomes in Blood Samples as a Biomarker of Alzheimer's Disease

Several research groups are in the later stages of developing a number of different approaches to blood-based assays to detect the early stages of Alzheimer's disease, or at least the buildup of amyloid-β in the brain that takes place over a span of years, long before symptoms manifest. Early detection should lead to means of early intervention, always a good deal easier than later intervention. Here, researchers outline a novel approach to detection of amyloid-β burden, finding amyloid-β levels correlated with those of a form of exosome carried in the circulation.

One of the primary causes of Alzheimer's disease is the accumulation of amyloid β (Aβ) in the brain, where it forms plaques. Alzheimer's disease is mostly seen in individuals over 65 years of age, and cannot currently be stopped or reversed. In addition to the lack of effective treatments of Alzheimer's, there are few methods to diagnose Alzheimer's. Alzheimer's can only be definitively diagnosed by direct examination of the brain-which can only be done after death. Aβ accumulation in the brain can be measured by cerebrospinal fluid testing or by positron emission tomography; however, the former is an extremely invasive test that cannot be repeated, and the latter is quite expensive. Thus, there is a need for a diagnostic test that is economical, accurate and widely available.

Previous work has shown that Aβ build-up in the brain is associated with Aβ-binding exosomes secreted from neurons, which degrade and transport Aβ to the microglial cells of the brain. Exosomes are membrane-enclosed sacs secreted by cells that possess cell markers on their surface. The team established a way to quantify the concentration of Aβ-binding exosomes in as little as 100 µL of blood. The device they developed traps molecules and particles in a sample one-by-one in a million micrometer-sized microscopic wells on a measurement chip and detects the presence or absence of fluorescent signals emitted by the cleaving of the Aβ-binding exosomes.

When tested on mouse models, the Aβ-binding exosome assay showed that the concentration of Aβ-binding exosomes increased with the increase in age of the mice. This is significant as the mice used were Alzheimer's disease model mice, where Aβ builds up in the brain with age. Clinical trials of the technology are currently underway in humans.

Link: https://www.global.hokudai.ac.jp/blog/detecting-alzheimers-disease-in-the-blood/

Testing Narrow Epigenetic Clocks in Centenarians

Many different epigenetic clocks have been proposed and tested in recent years, all using different weighted combinations of DNA methylation status at various CpG sites on the genome, some using fewer than ten sites, others using hundreds of sites. DNA methylation is in constant flux, regulating gene expression in cells, but some changes are characteristic of age, and machine learning approaches have produced clocks with strong correlations to chronological age. Where clock age is higher than chronological age, individuals have been shown to have greater incidence and risk of age-related disease and mortality.

Researchers still, however, do not have more than the rudimentary beginnings of a map to link methylation at specific CpG sites to the underlying damage and dysfunction of aging. Thus it is hard to treat epigenetic clock data as actionable for any given individual and their treatments. The clocks are quite good good for unmodified aging, but what we really want is a way to cost-effectively, rapidly assess the outcome of potential rejuvenation therapies, each of which will tend to only directly affect one of the many mechanisms of aging, without undertaking the time and expense of life span studies.

Given this, it is hard to trust narrow epigenetic clocks that use few CpG sites. They seem very unlikely to accurately reflect all of the processes of aging, and thus even trying to calibrate them against specific therapies seems likely to produce poor results. Nonetheless, since such narrow clocks are cheaper than broad clocks using hundreds of CpG sites, many research groups are working in this direction.

Centenarians consistently present a younger epigenetic age than their chronological age with four epigenetic clocks based on a small number of CpG sites

The study of DNA methylation in human aging has revealed the occurrence of two types of age-related DNA methylation changes. The first, known as epigenetic drift, is characterized by the progressive divergence of the methylome of individuals acquired environmentally and stochastically across their lifespan, which even affects monozygotic twins. The second type of DNA methylation changes is called the epigenetic clock and refers to all age-related DNA methylation variations that consistently increase or decrease in every individual, thereby correlating to their chronological age.

The latter type of epigenetic modifications has been widely used as biomarkers of aging in several age-prediction models to estimate the chronological and biological age of individuals, mainly from blood DNA samples. These models are based on multiple regression, machine learning, and deep learning approaches using either a large number of CpGs requiring high-throughput technologies such as genome-wide epigenotyping array or a smaller number of CpGs requiring high resolution locus-specific methods such as pyrosequencing. DNA methylation-based age (DNAmage) prediction has proven to be of great interest in several bio-medical applications. It could notably give a better estimation of the biological age than chronological age and could also be a good indicator or predicator of different risks, health conditions and age-related diseases when compared to the chronological age.

In the present study, we investigated the DNAmage of French long-lived individuals (LLI) including centenarians and semi-supercentenarians (n = 214), as well as nonagenarian's and centenarian's offspring (n = 143) of the CEPH aging cohort using blood extracted DNA and four epigenetic clocks based on a small number of CpGs and locus-specific pyrosequencing. These clocks, known as Bekaert, Thong, Garali MQR and Garali GBR clocks, were developed from 2 to 4 CpGs located in the promoters of 1 to 4 genes (ASPA, EDARADD, ELOVL2, KLF14, PDE4C, and TRIM59).

Compared to their chronological age, DNAmage of centenarians and semi-supercentenarians was strongly underestimated (15 to 28.5 years in average), which was still strongly significantly underestimated when compared to control group DNAmage (10.8 to 21 years in average). This might indicate that the epigenetic clock and potentially aging were decelerated in exceptionally long-lived individuals, who presented younger DNAmage and potentially also younger biological age.

Will Rejuvenation Therapies Be Useful for Progeria Patients?

Progeroid conditions are colloquially described as accelerated aging, but they are not in fact accelerated aging. They are only tangentially related to normal aging, in the sense that they are a form of molecular damage run rampant, and such damage tends to produce tissue and organ dysfunction that broadly resembles aging. It is not the same, however. Some progerias arguably involve forms of damage that do exist in normal aging and do contribute to normal aging, but when that damage represents near 100% of the total damage burden, rather than the normal much lesser fraction, the outcome ceases to be something that we can legitimately call aging. We cannot use it to teach us much about normal aging, and most of the rejuvenation treatments that will be beneficial to normally aged individuals will likely do little for a progeria patient. Only where the form of damage in a progeria aligns with a specific approach to rejuvenation through damage repair might there be utility.

All of the so-called "premature aging" diseases are in one critical sense entirely different from aging, inasmuch as they are the result of a relatively simple, unitary problem: patients carry just one key mutation in their cells. By contrast, real aging is the result of many different kinds of damage - and that damage accumulates as an unintended result of normal, healthy genes carrying out normal, life-sustaining metabolic processes that unfortunately inflict damage on previously healthy, non-mutated cells. In aging, there is no underlying mutation to fix, and we interfere with normal metabolic processes at our peril. So repairing the many different kinds of cellular and molecular aging damage is our best path to a future where we can live free of age-related ill-health.

"Damage-repair" rejuvenation biotechnologies might very well help progeria patients by removing, repairing, or replacing the subset of their cellular abnormalities that occur in their bodies and line up closely enough with forms of cellular and molecular aging damage targeted by these SENS-like damage-repair approaches. For instance, the high burden of what appear to be senescent cells in Hutchinson-Gilford Progeria Syndrome (HGPS) patients and mouse models is the result of a mutation in the gene for LMNA, whose encoded proteins are important structural components of the nuclear envelope, leading to senescent-cell-like phenotypes. The accumulation of senescent cells is, of course, involved in normal aging.

Even if the abnormal cells accumulating in HGPS patients' bodies aren't true senescent cells, there's still every reason to expect these patients to benefit from destroying the aberrant cells. This isn't just a reasonable prediction from first principles: it has proof-of-concept. In an animal study, scientists destroyed large numbers of the senescent-like cells in the tissues of mice with the same mutation as HGPS patients engineered into their genome. However, even after this senolytic treatment, however, these mice still aren't nearly as healthy or as long-lived as normal mice. HGPS causes other abnormalities in non-"senescent" cells, and both these mice and HGPS patients are rapidly accumulating these abnormal cells in comparison to normal individuals.

Link: https://www.sens.org/will-sens-benefit-progeria-patients/

The Future of Treating Aging

Here find a sensible, readable paper discussing the years ahead in the treatment of aging as a medical condition. The potential to slow and reverse aspects of aging, demonstrated in animal studies in the laboratory, is now beginning to reach the clinic. A great shift in the provision of medicine, expectations for health in later life, and priorities in research and development will occur over the next few decades. Where we stand today, with senolytic drugs, the first form of rejuvenation therapy worthy of the name, in initial clinical trials, is merely the opening of a lengthy, world-changing process. The human condition will change for the better, in ways that are just as profound as those that attended the advent of antibiotics and the sudden ability to greatly control infectious disease.

Population aging is expected to yield a greater proportion of older adults in the United States than ever before. Therefore, the health of this age group, and that of the U.S. population more broadly, will depend greatly on improved prevention and management of chronic diseases. While age is known to be a risk factor for many conditions that affect healthspan and lifespan, age has been considered largely immutable, and the increased risk of disease has been accepted as a fact of life. However, recent developments in geroscience research suggest that the biological processes underlying aging may be more plastic.

The potential of this finding is significant in that appropriate interventions may enable a paradigm shift from the management of diseases associated with advanced age to broad prevention of many illnesses through which individuals may increase the number of years they live in good health. In terms of both humanistic and economic factors, there is an emerging incentive to develop treatments and monitoring techniques that can properly assess and treat the hallmarks of aging. While classifying aging as a disease could be detrimental to older adults, treating the underlying biological processes that occur in every individual may provide a means to broadly improve health, given the strong links between these processes and the development of chronic disease.

However, without key scientific evidence to clinically define biological aging, measure its progress and effects, and produce an appropriate indication for geroscientific treatments, regulatory approval ensuring the safety and efficacy of products will continue to be an obstacle. The development of gerotherapeutics that can be administered across the lifespan will require an in-depth assessment of biomarkers for the aging process, and the acceptance of these biomarkers by scientific communities as well as by the FDA. This challenge has drawn the interest of clinicians, patients, caretakers, entrepreneurs, sociologists, and government officials alike. Through deliberate collaboration among these important stakeholders, we will be able to pave a path forward to improve the healthspan of older adults and the population at large.

Link: https://doi.org/10.38105/spr.d97k21lnkj

An Update on Senolytics Company Cleara Biotech

Senescent cells accumulate with age, and that accumulation is responsible for a meaningful fraction of degenerative aging. Many groups are working on ways to remove these cells and thereby reverse aspects of aging. Among their number, Cleara Biotech was founded four years ago on to advance initially promising work on the FOXO4-p53 interaction in cellular senescence, a possible targeted way to destroy senescent cells. This approach will join the numerous other mechanisms already being exploited as the basis for potential rejuvenation therapies.

A couple of companies have been looking into FOXO4 biochemistry in the context of cellular senescence, with very little new information emerging in recent years. Four years isn't that long in the biotech field, in which every aspect of development is challenging, but silence suggests that making something of the early FOXO4-related research has proved to be harder than expected.

Still, the Cleara principals appear confident enough in their present approach to be gearing up to prepare for clinical development. Certainly, there will be room for many different approaches and specializations in the clearance of senescent cells; it is coming to be a crowded field of many biotech startups and other entities pursing a diverse set of approaches and development programs.

Cleara Biotech Raises $2.5 Million in Seed Financing to Advance FOXO4-Therapeutics Pipeline for Treating Cancer and Chronic Diseases

Cleara Biotech B.V., a preclinical-stage biotechnology company focused on developing innovative, proprietary therapies for treating different pathologies of "scarred cellular" senescence, including late-stage cancer and chronic diseases, today announced that it closed a $2.5 million seed financing round earlier in the year, led by Apollo Health Ventures, with participation from Curie Capital B.V., ROM Utrecht Region, and Longevity Tech Fund.

Cleara has optimized two lead developmental candidates, CL04177 and CL04183, that can eliminate scarred cancer cells found in several late-stage cancers and chronic diseases in humans. The company is aiming to develop precision medicine tools that treat specific diseases with clear niche-directed, anti-senescent lead candidates, accompanied with associated biomarkers, around its FOXO4-based D-amino acid peptides and pipeline against subtypes of senescence.

Designed and optimized based on an extensive (3D) structural, molecular and cellular understanding of cell scarring's mechanism of action and how FOXO4 restrains this particular form of the cell guardian p53, both lead compounds potently counter viability of scarred cancer cells in 2D culture and 3D organoids, as well as strongly reduce the metastatic burden and infiltration in mouse in vivo models for metastatic colon cancer and triple-negative breast cancer. Furthermore, they show favorable pharmacokinetics and tissue distribution in mice, with an maximum tolerable dose that is well above their efficacious dose.

HDL Level, Age, and Smoking are the Largest Determinants of Mortality Risk in Old People

An interesting epidemiological study here stratifies the contributions of various metrics to mortality in later life, age 70 and older. The authors find that the largest effects arise from HDL level, chronological age, and smoking. The largest single cause of death in our species is atherosclerosis, a progressive malfunction in clearance of cholesterol from blood vessel walls that leads to fatty plaques, narrowed arteries, stroke, and heart attack. HDL particles carry excess cholesterol from blood vessel walls back to the liver for excretion, and - thus over a lifetime - the more HDL in circulation one has, the greater the metabolic dysfunction needed to begin in earnest the development of atherosclerotic plaque.

The Duke Established Populations for Epidemiologic Studies of the Elderly (D-EPESE) is a longitudinal cohort of community-dwelling older adults designed to overcome the above-mentioned limitations. D-EPESE included 1507 participants, aged ≥71 years with biomarker data and 27 years of death data from the time of blood sample acquisition in 1992. This research aimed to identify clinical and molecular biomarkers that predict, and causally affect, longevity, from 186 clinically accessible measures that geriatricians and clinicians can, and frequently obtain in a clinic setting.

We studied the relationships of patient-reported outcomes and questionnaires, and clinically available medical tests with survival status and identified optimal predictors. We chose to explore 2-, 5- and 10-year longevity since these time horizons are clinically relevant for this cohort of mean age 78 years with mean life expectancy of 9.37 years (men) and 10.92 years (women). These time horizons are also relevant for clinical decision-making that considers the benefits and burdens of tests (e.g., colon, breast, and prostate cancer screening), and treatment (stringency of lipid and blood pressure lowering), based on life expectancy.

We identified a relatively small number of putative direct causes of longevity from among 186 clinically accessible variables, with 8 to 15 variables containing the totality of signal for each time horizon. Greater concentrations of small HDL particles, younger age, and fewer pack years of cigarette smoking were the strongest determinants of longevity at 2-, 5- and 10-years, respectively.

Link: https://doi.org/10.1016/j.ebiom.2022.104292

SIRT3 Knockout Increases Life Extension Resulting from Calorie Restriction

Unexpectedly, researchers find that knockout of SIRT3, involved in mitochondrial function, increases the gain in life span exhibited by calorie restricted mice. Yet it does so while reducing physical fitness. Work on SIRT3 and aging typically focuses on upregulation of SIRT3, as this is beneficial to mitochondrial function, particularly in the damaged tissue environment of later life. Loss of SIRT3 modestly accelerates aging; add calorie restriction, however, and it becomes beneficial to life span, while still having a negative impact on physical performance. The data here for the combination of SIRT3 knockout and calorie restriction is an illustration of the point that everything in cellular biology and aging is a great deal more complex than we would like it to be.

One of the hallmarks of calorie restriction (CR) is the preservation of mitochondrial function through reducing oxidative stress, enhancing fuel utilization, and maintaining mitochondrial dynamics and integrity. Previous studies have proposed that Sirtuin3 (SIRT3)-dependent deacetylation may play a major role in modulating mitochondria under CR. Nonetheless, direct evaluation of the contribution by SIRT3 to CR-dependent lifespan extension and mitochondrial performance during aging is lacking.

Here, using male Sirt3+/+ (wild type) and Sirt3-/- mice, we report that SIRT3 is required for whole-body aerobic capacity but is dispensable for CR-dependent lifespan extension. Under CR, loss of SIRT3 (Sirt3-/-) yielded a longer overall and maximum lifespan as compared to Sirt3+/+ mice. This unexpected lifespan extension was associated with altered mitochondrial protein acetylation in oxidative metabolic pathways, reduced mitochondrial respiration, and reduced aerobic exercise capacity. Also, Sirt3-/-CR mice exhibit lower spontaneous activity and a trend favoring fatty acid oxidation during the postprandial period.

This study shows the uncoupling of lifespan and healthspan parameters (aerobic fitness and spontaneous activity) and provides new insights into SIRT3 function in CR adaptation, fuel utilization, and aging.

Link: https://doi.org/10.1111/acel.13721

In Health and Mortality, Do Human Genetic Variants Matter More With Age Or Less With Age?

To what degree do genetic variants drive the observed differences in human life expectancy? The old consensus guesstimate was that environment determines 75% of life expectancy, and genetic variants the other 25%. Further, it is the common wisdom that gene variants become more important to life expectancy in later life, either by providing greater resilience to specific forms of damage and dysfunction, or slowing the pace at which that damage and dysfunction accumulates. A great deal of medical research is based on the insight that gene variants are thought to provide on disease processes.

Views on genetic variants are changing, however. Modern research that makes use of genetic databases that cover very large populations is trending in the direction of demonstrating that ever smaller contributions to life expectancy arise from genetic variants. As the importance of genetic variants diminishes, the importance of environmental factors and lifestyle choices becomes ever greater, and the value of research into genetic variations and aging becomes more questionable.

Today's research materials discuss a recent study in which the authors provide data to suggest that gene variants become less important with age, that their contribution to emergent differences in cell metabolism is outweighed by other factors. This, like the genetic studies on large populations, is an attack on the value of research programs that focus on gene variants in the context of age-related disease. There are a great many such programs, as well as ongoing searches for new variants that might be useful to investigate more deeply. If gene variants largely do not tend to usefully predict cell and tissue behavior across an aged population, then then other high-level research strategies may well prove to be more cost-effective in the long term.

Age vs. genetics: Which is more important for how you age?

In a study of the relative effects of genetics, aging, and the environment on how some 20,000 human genes are expressed, the researchers found that aging and environment are far more important than genetic variation in affecting the expression profiles of many of our genes as we get older. The level at which genes are expressed - that is, ratcheted up or down in activity - determines everything from our hormone levels and metabolism to the mobilization of enzymes that repair the body.

while our individual genetic makeup can help predict gene expression when we are younger, it is less useful in predicting which genes are ramped up or down when we're older - in this study, older than 55 years. Identical twins, for example, have the same set of genes, but as they age, their gene expression profiles diverge, meaning that twins can age much differently from each other. The findings have implications for efforts to correlate diseases of aging with genetic variation in humans. Such studies should perhaps focus less on genetic variants that impact gene expression when pursuing drug targets.

The findings are in line with Medawar's hypothesis: Genes that are turned on when we are young are more constrained by evolution because they are critical to making sure we survive to reproduce, while genes expressed after we reach reproductive age are under less evolutionary pressure. So, one would expect a lot more variation in how genes are expressed later in life. "Across all the tissues in your body, genetics matters about the same amount. It doesn't seem like it plays more of a role in one tissue or another tissue. But aging is vastly different between different tissues. In your blood, colon, arteries, esophagus, fat tissue, age plays a much stronger role than your genetics in driving your gene expression patterns."

Tissue-specific impacts of aging and genetics on gene expression patterns in humans

Overall this work has several important implications. Our results shed light on recent work on the prediction accuracy of polygenic risk scores (PRS) which found that numerous factors, including age, sex, and socioeconomic status can profoundly impact the prediction accuracy of such scores even in individuals with the same genetic ancestry. Our results highlight that genetics exhibit varied predictive power in several different tissues as a function of age, potentially playing a role in differential PRS accuracy between young and old individuals.

This also has important implications for disease association and prediction approaches that leverage expression quantitative trait loci (eQTLs) to prioritize variants. If a significant proportion of eQTLs exhibit age-associated biases in their effect size in a tissue of interest, then these approaches may be less powerful when applied to diseases for which age is a primary risk factor such as heart disease, Alzheimer's disease, cancers, and diabetes.

High Allostatic Load Correlates with Greater Risk of Cancer Mortality

Allostatic load is a compound measure of stress on the body, usually including an emphasis on inflammatory activity in the immune system. The measures making up allostatic load are raised by psychological stress, chronic exposure to pathogens or pollutants, and similar circumstances. Researchers here note that this, perhaps unsurprisingly, correlates with increased cancer mortality. Greater inflammation produces a more hospitable environment for cancer to occur and then grow, and the relationship between allostatic load and cancer may indeed be largely determined by the state of the immune system.

Allostatic load attempts to quantify physiological stress by measuring biomarkers across cardiovascular, immune, and metabolic systems. It has been defined using varying configurations, although most incorporate biomarker measures from these three different categories of physiologic functioning. While there is no consensus definition, we elected to define allostatic load using components including body mass index (BMI), diastolic blood pressure (DBP), glycohemoglobin (hemoglobin A1c), systolic blood pressure (SBP), total cholesterol, serum triglycerides, serum albumin, serum creatinine, and C-reactive protein (CRP).

Chronic stress activates the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system, causing the release of corticosteroids and catecholamines respectively. Frequent exposure to these compounds have been linked to the development of cancer by DNA damage, inhibition of p53, and promoting a microenvironment favoring tumorigenesis. Chronic stress has also been shown to modulate the immune system in favor of conditions for cancer progression. In the innate immune system chronic stress and associated hormones increase pro-inflammatory cytokines. Long term pro-inflammation can influence all stages of cancer development through manipulation of tumor microenvironment, genetic mutation, and epigenetic modifications.

In fully adjusted models, high allostatic load was associated with a 14% increased risk of cancer death among all participants and a 18% increased risk of cancer death among Non-Hispanic White (NH-White) adults. When further stratified by age (participants aged less than 40 years), high allostatic load was associated with a 80% increased risk among all participants; a 95% increased risk among NH-White adults; a 2-fold increased risk among Non-Hispanic Black (NH-Black) adults; and a 36% increased risk among Hispanic adults.

Link: https://doi.org/10.1016/j.ssmph.2022.101185

Cognitively Healthy Centenarians are Resistant to Age-Related Brain Pathology

The article here notes that researchers find cognitively healthy centenarians exhibit levels of protein aggregation and other brain lesions typical of people showing symptoms of neurodegenerative diseases. They are in some way more resistant, but why this is the case is a continuing research project. It is possible to identify specific gene variants and more youthful gene expression for some genes in cognitively healthy older individuals, but it is long trek from that data to an understanding of the mechanisms involved.

Researchers initially aimed to recruit 500 cognitively healthy centenarians. As of June 2021, 406 had signed up. Their average age when they joined was 101; the oldest is now 107. Seventy percent are women; 43 percent still live independently. About 30 percent have agreed to donate their brains after death and, to date, 95 of them have passed away. Researchers have presented the neuropathology findings from 85 of those.

At autopsy, some of these centenarians were found to have had pathologies typical of people with Alzheimer's disease (AD). Many had been in stage 2 or 3 amyloidosis when they died, as judged by NIA criteria, and had accumulated stage 2 or even stage 3 neuritic plaques per CERAD scores. All were in at least Braak stage I for neurofibrillary tangles, though the majority were at stage III or higher. The brains weighed about as much as those from people who had had AD dementia, but neither plaques nor tangles correlated with cognitive assessments.

The same was true for a host of other age-related pathologies, including cerebral amyloid angiopathy, TDP-43 proteinopathy, Lewy bodies, hippocampal sclerosis, granulovacuolar degeneration, atherosclerosis, and vascular infarcts. Many centenarians had at least one of these. Across all of these pathologies, increased levels in the postmortem brain generally came with lower cognitive scores before death, but the associations were weak. Of all neuropathological substrates tested, tangles correlated most robustly with lower performance, but these healthy centenarians seemed surprisingly resistant even to the effects of high levels of tangles.

Scientists compared the centenarians' proteomes to those from 50- to 95-year-old people with AD and to 50- to 90-year-old healthy controls. They found that, while concentrations of about two dozen proteins fall with age, in centenarians, these protein levels were higher than expected for their age. For four other proteins that normally tick up with age, levels remained steady in the centenarians. The proteins that bucked these trends included those involved in microtubule and intermediate filament biology, myelination, the immune system, basic metabolism, and protein transport. "In a nutshell, these centenarians have younger-looking brains."

Link: https://www.alzforum.org/news/research-news/sharp-100-thank-you-genes-thank-you-immune-system

A Few Years of Difference in Life Expectancy Between Poorest and Wealthiest in Spain

Wealth, and the closely related construct of socioeconomic status, correlate with life expectancy. Wealth also correlates with environmental exposure to air pollution, as wealthier people tend to live in better surroundings, intelligence, education, access to and effective use of medical services, lifestyle choices that impact health, and a range of other line items that are also correlate with life expectancy.

Picking out the important mechanisms that directly impact long-term health and mortality risk is a challenge, for all that it is tempting to point to the obvious candidates of excess weight and smoking habits, both of which are individually accompanied by a great deal of evidence for the size of effect and strength of correlation. There are always other mechanisms! Intelligence is suggested to have genetic contributions that overlap with those determining physical robustness, for example.

This is the usual story in human epidemiology: correlations abound, but identifying actionable, harmful mechanisms for intervention is difficult. There is a very good mechanistic argument that reducing particulate air pollution will reduce chronic inflammation and cardiovascular mortality. But is that a significant contribution in comparison to the choice to smoke, or the choice to become obese? Individuals can look at the research and make sensible choices in an environment of uncertainty surrounding the details, to the best of their ability, and that may be all that can come of it at the end of the day.

Association of socioeconomic deprivation with life expectancy and all-cause mortality in Spain, 2011-2013

Life tables summarise a population's mortality experience during a time period. Sex- and age-specific life tables are needed to compute various cancer survival measures. However, mortality rates vary according to socioeconomic status. We present sex- and age-specific life tables based on socioeconomic status at the census tract level in Spain during 2011-2013 that will allow estimating cancer relative survival estimates and life expectancy measures by socioeconomic status.

Life expectancy (LE) at birth was higher among women than among men. Women and men in the most deprived census tracts in Spain lived 3.2 and 3.8 years less than their counterparts in the least deprived areas. Overall, we found a consistent LE gap at birth according to socioeconomic status for both sexes in Spain during the 2011-2013 period. However, the gap was wider among men than among women, with the least deprived male group experiencing shorter LE at birth than the most deprived female group. Furthermore, we found a geographical pattern characterised by shorter LE at birth in the southwest for both sexes in Spain.

Furthermore, our results on LE at birth by deprivation are consistent with those of other European studies. In the UK, LE at birth in 2005 presented a similar pattern, with the highest LE in the most affluent groups compared to the most deprived group, with a gap between 2.7 and 5.0 years for males and between 2.5 and 3.6 years for females. Overall, differences in LE are seen by deprivation and by region, and the regions with higher LE are also the least deprived. Similar to the geographical pattern found in Spain, a regional pattern characterised by a clear north-south gradient was found in the UK, with deprivation explaining most of the geographical variation in LE.

A Complex Systems View of the Biology of Aging

The study of complex systems, made up of many interacting parts, is a well-developed area of research and development, spanning many distinct disciplines of science and engineering. Any particular subset of cellular biology can be considered a complex system, and the tools developed in other disciplines can be adapted to use in the life sciences. Here, researchers discuss how to apply complex systems frameworks to the study of aging. This approach to develop means of intervention embraces the complexity of our biology. It is the polar opposite of, say, the SENS approach to rejuvenation, which seeks to work around that complexity (and the amount of work needed to understand it) by focusing on the comparatively narrow domain of the root causes of aging. If addressing causes, we do not need to fully understand all of the consequences of those causative mechanisms in detail, we just need to fix those causes.

The goals of aging biology research are broad and ambitious - to understand how a multitude of genes, pathways, and mechanisms at multiple scales contribute to declines in function, health and lifespan in ways that can vary across populations, environments and species. Enormous progress has been made identifying individual genes, pathways, molecules and their connection in mechanisms that modulate aging. However, there has been limited progress in our understanding of how these factors interact to produce a global set of aging processes, or in how these processes combine to produce functional phenotypes of aging such as frailty, or demographic patterns such as the Gompertz mortality curves found across the tree of life.

Accordingly, research is increasingly focusing on understanding how mechanisms and pathways integrate, drawing on concepts of complex systems such as resilience, homeostasis, networks, and interactions. This transition to a complex systems view of aging has been happening piecemeal and is only sometimes explicitly acknowledged; many of the core concepts and methods are unfamiliar to biologists and may be defined in various ways. Here, we provide a theoretical framework and introduction to the key concepts of complex systems theory as applied to aging, as a primer to orient researchers new to the field and in the attempt to offer a unifying vision for how a complex systems approach could be transformative in aging biology research.

Link: https://doi.org/10.1038/s43587-022-00252-6

Cancers Force T Cells into Senescence

Established cancers aggressively manipulate the immune system to their advantage, co-opting innate and adaptive immune cells to support rather than attack a tumor. Researchers here note a mechanism by which cancerous tissue forces T cells into a senescent state. Inhibiting this transition makes the immune system more effective at attacking the cancer, where fired up by a suitable immunotherapy that overcomes other barriers that the cancer puts in place to suppress the immune response.

It is now recognized that T cell functional state in the tumor microenvironment (TME) is a key determinant for effective antitumor immunity and immunotherapy. In addition to exhaustion, cellular senescence in tumor-infiltrating T cells (TILs) has recently been identified as an important T cell dysfunctional state induced by various malignant tumors. Therefore, a better understanding of the molecular mechanism responsible for T cell senescence in the TME and development of novel strategies to prevent effector T cell senescence are urgently needed for cancer immunotherapy.

We report that both mouse malignant tumor cells and regulatory T cells (Tregs) can induce responder T cell senescence, similar as shown in human Treg and tumor cells. Accumulated senescent T cells also exist in the TME in tumor models of lung cancer, breast cancer, and melanoma. Induction of ataxia-telangiectasia mutated protein (ATM)-associated DNA damage is the cause for T cell senescence induced by both mouse tumor cells and Treg cells, which is also regulated by mitogen-activated protein kinase (MAPK) signaling.

Furthermore, blockages of ATM-associated DNA damage and/or MAPK signaling pathways in T cells can prevent T cell senescence mediated by tumor cells and Treg cells in vitro and enhance antitumor immunity and immunotherapy in vivo in adoptive transfer T cell therapy melanoma models. Importantly, prevention of tumor-specific T cell senescence via ATM and/or MAPK signaling inhibition combined with anti-PD-L1 checkpoint blockade can synergistically enhance antitumor immunity and immunotherapy in vivo.

Link: https://doi.org/10.1136/jitc-2022-005020

Mitochondrial Stress Provokes Inflammation via Fragments of Mitochondrial DNA

A large body of evidence links mitochondrial dysfunction with chronic inflammation. These are both features of aging, but it appears that dysfunctional, stressed mitochondria are a meaningful cause of inflammatory signaling. Mitochondria can generate molecular fragments, such as pieces of mitochondrial DNA, that are recognized as potentially threatening by the innate immune system. These damage-associated molecular patterns are present in much greater amounts in old tissues, and the immune system reacts to them to produce lasting, unresolved inflammation, harmful to tissue function rather than protective.

In today's research materials, scientists report on their investigation of how exactly it is that mitochondrial DNA fragments are ejected from cells to then provoke an immune response. Understanding the details of the processes involved may reveal points of intervention that can be used to suppress age-related chronic inflammation. The researchers here suggest FEN1 inhibition as a possibility, as this protein is involved in producing the fragments of DNA that then exit the cell to act as damage-associated molecular patterns.

How Mitochondrial Damage Ignites the "Auto-Inflammatory Fire"

When stressed, damaged or dysfunctional, mitochondria expel their DNA (mtDNA), oxidized and cleaved, into the cytosol - the fluid within a cell in which organelles float - and beyond into the bloodstream, triggering inflammation. In autoimmune conditions like lupus and rheumatoid arthritis, the amounts of circulating oxidized mtDNA correlate with disease severity, flare-ups, and how well patients respond to therapies. An unanswered question that has plagued the field is whether oxidized mtDNA is simply a biomarker or indicator of disease or something more: a critical player in disease pathology.

In a new study, researchers describe the biochemical pathway that results in the generation of oxidized mtDNA, how it is expelled by mitochondria and how it triggers the complex and destructive inflammatory response that follows. "In addition to charting a new pathway responsible for the generation of inflammation-provoking fragments of oxidized mtDNA, this work opens the door to the development of new anti-inflammatory agents."

Oxidized DNA fragments exit mitochondria via mPTP- and VDAC-dependent channels to activate NLRP3 inflammasome and interferon signaling

Mitochondrial DNA (mtDNA) escaping stressed mitochondria provokes inflammation via cGAS-STING pathway activation and, when oxidized (Ox-mtDNA), it binds cytosolic NLRP3, thereby triggering inflammasome activation. However, it is unknown how and in which form Ox-mtDNA exits stressed mitochondria in non-apoptotic macrophages. We found that diverse NLRP3 inflammasome activators rapidly stimulated uniporter-mediated calcium uptake to open mitochondrial permeability transition pores (mPTP) and trigger VDAC oligomerization. This occurred independently of mtDNA or reactive oxygen species, which induce Ox-mtDNA generation.

Within mitochondria, Ox-mtDNA was either repaired by DNA glycosylase OGG1 or cleaved by the endonuclease FEN1 to 500-650 base pair fragments that exited mitochondria via mPTP- and VDAC-dependent channels to initiate cytosolic NLRP3 inflammasome activation. Ox-mtDNA fragments also activated cGAS-STING signaling and gave rise to pro-inflammatory extracellular DNA. Understanding this process will advance the development of potential treatments for chronic inflammatory diseases, exemplified by FEN1 inhibitors that suppressed interleukin-1β (IL-1β) production and mtDNA release in mice.

Centrophenoxine Is Not That Interesting

The Forever Healthy Foundation publishes, intermittently, a series of rigorous literature reviews for presently available treatments that are alleged to help with mechanisms of aging. The viewpoint is conservative; the authors are less convinced by the evidence for the utility of early senolytics than I am, for example. Their latest publication covers centrophenoxine, not a treatment I am familiar with, but by the sound of it I'm not missing out on anything. The data is emblematic of much of what is marketed under the "anti-aging" banner; unconvincing, mixed, marginal.

Centrophenoxine (CPH) is a compound consisting of dimethylaminoethanol (DMAE) and para-chlorophenoxyacetic acid (pCPA), joined by a chemical bond. DMAE can be converted by cells into choline, which is a precursor of membrane phospholipids, neurotransmitters, and other important biomolecules. The pCPA component enhances the penetration of CPH across the blood-brain barrier. CPH supplementation is hypothesized to increase brain acetylcholine levels, protect neurons from oxidative damage, improve cognitive function, and reduce age-related lipofuscin accumulation.

There is moderate evidence that centrophenoxine may benefit patients hospitalized for injury to the brain from either vascular or traumatic origin, especially in acute cerebral hemorrhage. However, despite several decades of use since it was first synthesized, the clinical utility of centrophenoxine in healthy individuals remains unclear, primarily because the vast majority of published trials test the efficacy of centrophenoxine in treating study populations with specific diseases.

Centrophenoxine is marketed as a general anti-aging supplement, however, we found no evidence in humans to support this purported benefit. Preclinical studies on the effect of centrophenoxine on longevity in animals are also scant. The evidence regarding the use of centrophenoxine as a cognitive enhancer is inconsistent. Many studies employed a wide battery of tests, often reporting a narrow but significant positive result among many assessments that did not change, or occasionally worsened. Most studies were small, less than 30 participants, conducted in older adults with significant cognitive impairment, often in frail clinical condition, and suffered from high dropout rates.

Although low doses are unlikely to cause harm, we conclude that, in the healthy population, the evidence for any benefits of centrophenoxine supplementation is not sufficiently compelling to overcome the precautionary principle.

Link: https://brain.forever-healthy.org/display/EN/Centrophenoxine

Cellular Senescence and Abdominal Aortic Aneurysm

In recent years, researchers have presented evidence for the age-related accumulation of senescent cells to be a meaningful contributing cause of aneurysm, the formation of a bulging weak spot in a blood vessel, vulnerable to bursting. Relatedly, pro-inflammatory immune cells are also implicated. The commonality here is inflammatory signaling, disruptive to tissue function. Here researchers review the mechanisms likely involved, and the high points of existing evidence for a relationship between the presence of senescent cells and formation of aneurysms.

Abdominal aortic aneurysm (AAA) is locally weak and aneurysm-like dilatation of the abdominal aorta, with a diameter of 3 cm or more, more than 1.5 times the normal diameter AAA is a common disease among the elderly, and the incidence of AAA increases with age. Most AAA patients are asymptomatic and are discovered accidentally during a physical exam or ultrasound screening. However, rupture or precursor rupture may occur when patients present with symptoms such as lumbago and abdominal pain. The in-hospital mortality rate of rupture is about 40%, while the out-of-hospital mortality rate can be as high as 90%, resulting in about 150,000-200,000 deaths globally per year.

The threat of AAA mainly in elderly patients is becoming more and more serious. Currently there is no effective method to inhibit AAA progress via treatment with clinical drug. Thus it is of great clinical significance to study the pathogenesis of AAA and explore potential therapeutic targets. The purpose of this paper is to analyze the pathogenesis of AAA from the perspective of cellular senescence: on the basis of clear evidence of cellular senescence in aneurysm wall, we actively elucidate specific molecular and regulatory pathways, and to explore the targeted drugs related to senescence and senescent cell elimination measures, eventually improve the health of patients with AAA and prolong the life of human beings.

Link: https://doi.org/10.3389/fcvm.2022.999465

An Interesting Delivery Method for GDF11

GDF11 was one of the earliest allegedly beneficial factors identified in parabiosis experiments, in which young and old mice have their circulatory systems joined. Researchers saw higher levels of GDF11 in younger mice, and proposed that increased GDF11 signaling was a meaningful mechanism to explain the observed improvement in function of tissues in older mice. Following on from that, there has been considerable, continuing debate over whether or not this is in fact the case.

A company, Elevian, was founded to build GDF11-based therapies, and claims to have resolved much of that controversy. Still, later studies have demonstrated very convincingly that parabiosis benefits derive from a dilution of harmful circulating molecules in the circulation of old mice, rather than the delivery of beneficial molecules from young mice. It remains to be seen as to where this broad area of research will lead, an increased interest in plasma dilution and replacement of albumin are the latest developments.

Along the way, a few studies have suggested that delivery of recombinant GDF11 or upregulation of GDF11 expression can produce benefits in mice, such as reduced inflammatory signaling or other improvements in metabolism. Today's open access paper is a recent example. It is noteworthy for the delivery method used, which is quite intriguing. The researchers produced a yeast lineage that expresses GDF11, and fed the yeast to the mice in their diet, resulting in delivery of that GDF11 to the circulation. One might wonder how many other proteins would survive the oral administration route via this approach.

Dietary intake of GDF11 delays the onset of several biomarkers of aging in male mice through anti-oxidant system via Smad2/3 pathway

Since the discovery of GDF11 as a "youth factor", it has become a "hot" molecule in the field of anti-aging study. Yet there is still controversy over the age-related change in concentration of GDF11 and its role in the genesis of rejuvenation conditions. With the aid of a highly specific anti-GDF11 antibody, here we show that GDF11 concentration declines with age in male mice, confirming the results of ours and others that blood GDF11 abundance reduces with age in both fish and mouse as well as humans.

In this study, we displayed rGDF11 on the surface of the yeast Yarrowic Lipolytica, and proved the bioavailability of the yeast-displayed rGDF11 by oral delivery in aged male mice. On the basis of these findings, we started to explore the anti-aging activity and underlying mechanisms of displayed rGDF11. It was found that dietary intake of displayed rGDF11 had little influence on the body weight and biochemical parameters of aged male mice, but delayed the occurrence and development of age-related biomarkers such as lipofuscin and senescence-associated-β-galactosidase, and to some extent, prolonged the lifespan of aged male mice.

Moreover, we demonstrated once again that dietary intake of displayed rGDF11 enhanced the activity of anti-oxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPX), reduced the reactive oxygen species (ROS) level, and slowed down the protein oxidation and lipid peroxidation. Importantly, we showed for the first time that rGDF11 enhanced the activity of CAT, SOD, and GPX through activation of the Smad2/3 signaling pathway. Our study also provided a simple and safe route for delivery of recombinant GDF11, facilitating its therapeutic application in the future.

Is Blood-Brain Barrier Dysfunction Cause or Consequence in Alzheimer's Disease Pathology?

The blood-brain barrier is a layer of specialized cells wrapping blood vessels in the central nervous system, isolating the brain from the rest of the body by allowing on some cells and molecules to pass. The blood-brain barrier becomes leaky with age, however, as vascular dysfunction progresses. This allows inappropriate molecules into the brain to provoke inflammatory responses from brain-resident immune cells, and no doubt produces other detrimental consequences as well. Researchers do not consider it settled that blood-brain barrier dysfunction is a deeper cause of neurodegeneration, however. It may be at least in part a consequence of other aspects of neurodegenerative aging that take place in brain tissue.

Alzheimer's disease (AD) is a complex disorder that is clinically characterized by the progressive decline in cognition, and pathologically characterized by the accumulation of amyloid-β (Aβ) and phosphorylated tau (P-tau) in the brain. In recent years, a series of studies have demonstrated that AD is linked to blood brain barrier (BBB) dysfunction. BBB dysfunction has been identified in the early stage of AD. The BBB is a continuous membrane formed by a tightly sealed monolayer of endothelial cells. The main function of the BBB is maintenance of the brain health micro-environment by keeping neurotoxic components, pathogens, and circulating blood out of the brain.

The first clues regarding BBB dysfunction came from studies performed in AD genetic animal models with Aβ or tau pathology. Therefore, at that time, it was believed that BBB dysfunction was associated with Aβ or tau pathology. However, BBB breakdown and vascular dysregulation were also determined in preclinical and early-stage AD patients before cognitive decline or positive Aβ and tau pathology. These results suggested that the BBB breakdown that appeared in the early stage of AD could not be fully explained by the consequence of Aβ and/or tau pathology (the forms of plaques, tangles, and oligomers).

In recent years, emerging evidence has supported the contributions of neuroinflammation to AD pathogenesis. The associations between BBB breakdown and neuroinflammation have been explored in several studies. An injured BBB was associated with neuroinflammation such as microglial activation and elevated inflammatory cytokines release. However, the exact role of BBB dysfunction in AD pathogenesis is still unknown. It remains elusive whether BBB dysfunction is a consequence or a cause of Aβ pathology, tau pathology, neuroinflammation, or other conditions.

Link: https://doi.org/10.14336/AD.2022.0130-1

More On Depletion of Soluble Amyloid-β in Alzheimer's Disease

If slow amyloid-β aggregation over years is the cause of Alzheimer's disease, then how to explain the older individuals who have high levels of amyloid-β in the brain, but do not suffer from Alzheimer's disease? Further, how to explain the failure of amyloid-β clearance via immunotherapy in clinical trials? Amyloid-β is successfully cleared from the brain, but patient outcomes do not improve meaningfully. This line of thinking led to the hypothesis, with supporting evidence, that amyloid-β aggregation is pathological only because it depletes levels of soluble amyloid-β. It doesn't cause that issue to the same degree in every older individual, however, and individuals who manage to maintain high levels of soluble amyloid-β avoid Alzheimer's disease even when they have a large burden of amyloid-β aggregates.

Key support for the toxic amyloid hypothesis comes from the observation that mutations in any of three genes (APP, PSEN1, and PSEN2) lead to Alzheimer's disease (AD). The genetic evidence causally implicates the fibrillogenic 42-amino acid amyloid-β peptide (Aβ42). However, the disease pathogenesis may arise from either of two ends of the protein aggregation process: the increase in insoluble amyloid plaques or the depletion of the soluble Aβ42 peptide, which has important functions. While insoluble amyloid plaques can be present in normal individuals, low soluble levels of Aβ42 are an invariable feature of AD.

The hypothesis of Aβ toxicity has traditionally been supported by the notion that AD-causing mutation carriers must have high levels of soluble Aβ42 relative to non-mutation populations. In fact, mutation carriers have lower Aβ42 levels compared to non-mutation populations. The reduction in soluble Aβ42 levels among mutation carriers begins as many as 25 years before the onset of cognitive symptoms. Therefore, the toxicity in the process of accelerated protein aggregation among mutation carriers may conceivably be due to the depletion in soluble Aβ42 to a greater extent than the corresponding increase in amyloid. This alternative hypothesis offers an explanation for the failures in translating amyloid reduction into cognitive improvement, even among mutation carriers, and for the paradoxes posed by the large proportion of amyloid-positive individuals without dementia and even of centenarians without history of cognitive abnormalities, half of whom have autopsy-confirmed AD pathology.

We recently observed that among amyloid positron emission tomography (PET)-positive individuals, higher levels of soluble Aβ42 were associated with normal cognition and brain volumes in all tertiles of brain amyloidosis, with an effect size greater than that of increases in brain amyloid burden.

Link: https://doi.org/10.3233/JAD-220808

RAS/MAPK Pathway Inhibition as an Example of the Way in Which Cancer Research Informs Aging Research

A sizable number of potential approaches to slowing aging via metabolic manipulation were first tested in the cancer research community. In part, this is because that side of the research community has tested near every compound in the libraries at some point in time, but it is also the case there are deep ties between approaches that might impact cancer and changes that might slow aging. This is particularly the case in the matter of cellular senescence, of great relevance to both cancer and aging, and the first senolytic drugs to clear senescent cells had already seen some success in the cancer field. In at least one case, dasatinib, this success is likely precisely because it is a senolytic, and senescent cells encourage growth of the leukemias that the dasatinib is used to treat.

More often, however, the outcome for aging is not as dramatic as is the case for senolytics. Slowing aging is a usually a marginal affair, achieved by triggering cellular stress response mechanisms, or influencing growth and energy metabolism in some way. The gains in humans will most likely be much smaller than those achieved in mice, judging from the existing points of comparison, such as practice of calorie restriction, or populations with loss of function mutations affecting growth hormone signaling, such as Laron syndrome. Today's open access paper is an example of this sort of age-slowing intervention, well-explored in the cancer research community, and which may gain some interest in the aging research community. Yet we shouldn't expect this to result in any wondrous new therapies to treat aging in humans.

Molecular inhibition of RAS signalling to target ageing and age-related health

Ageing research in model organisms has led to the rapid identification and genetic dissection of key ageing pathways, including the RAS/MAPK signalling pathway. Genetic interventions that modulate signalling through RAS proteins and their downstream effectors have been shown to increase lifespan in these model systems and to improve multiple parameters of health, both during normal ageing and in animal models of age-related disease. RAS/MAPK signalling therefore adds to an emerging theme that manipulating cancer-promoting pathways, either by inhibiting the function of oncogenes or by increasing the activity of tumour suppressors, can affect healthy ageing.

Examples from rodent models that extend lifespan include Myc haploinsufficiency, extra genomic copies of the Ink4/Arf locus, that elevate expression of its encoded tumour suppressor proteins p16 and p14, and increased gene dosage of the tumour suppressor Pten, or mimicking its activation through genetic inhibition of its direct target, PI3K. Interestingly, although some these models had reduced cancer incidence, researchers also observed lifespan extension in cancer-free animals, suggesting that delayed ageing may not simply be a consequence of protection against cancer.

The prominent role of RAS/MAPK signalling in cancer has led to the isolation of several small molecule inhibitors of the pathway, and some are already in clinical use. Recent work with model organisms suggests that these same compounds may provide beneficial effects on age-related health. Thus, repurposing these anti-cancer treatments could provide a useful strategy to develop novel interventions to promote healthy ageing. Moreover, other pro-longevity pharmacological interventions may elicit their effects on ageing and age-related health, at least in part through perturbations in RAS/MAPK signal transduction. It should be noted, though, that compounds like metformin, acarbose, dihydromyricetin, and statins have much broader effects, and, although they have an impact on RAS/MAPK outputs, they do not exclusively target this pathway.

However, cancer therapeutics, including small molecule inhibitors of RAS/MAPK signalling, are notoriously toxic and can elicit severe side effects. Effective strategies to limit these adverse effects will therefore be essential for clinical implementation. Determining the critical time periods during the life course when RAS/MAPK inhibition modulates ageing, and assessing the effect of intermittent dosing, could be one such approach to minimise side effects. Careful titration will also help to provide the geroprotective effects of these drugs without side effects or drug resistance.

Patients Suffering From More Age Related Conditions Exhibit a Greater Risk of Dementia

The growing burden of age-related cell and tissue damage, and consequent dysfunction, manifests in later stages as the presence of age-related conditions. The more age-related diseases that a person has, the greater the risk of the later onset of other conditions, simply because the underlying level of dysfunction and damage is high. Thus in this epidemiological study we see the expected correlation between the existence of multiple age-related conditions and greater risk of the onset of dementia. The best path forward to improve health in later life is to focus on the underlying damage, not the conditions themselves. Striking at the root of aging, successfully reversing the cell and tissue damage that causes aging, will improve all aspects of health.

Individual conditions have been identified as risk factors for dementia; however, it is important to consider the role of multimorbidity, as conditions often co-occur. This study investigated whether multimorbidity is associated with incident dementia and whether associations vary by different clusters of disease and genetic risk for dementia. The study used data from the UK Biobank cohort, with baseline data collected between 2006 and 2010 and with up to 15 years of follow-up. Participants included women and men without dementia and aged at least 60 years at baseline. The presence of at least 2 long-term conditions from a preselected list of 42 conditions was used to define multimorbidity.

A total of 206,960 participants (mean age 64.1 years) were included in the final sample, of whom 89,201 participants (43.1%) had multimorbidity. Over a mean of 11.8 years of follow-up, 6,182 participants (3.0%) developed dementia. The incidence rate was 1.87 per 1,000 person-years for those without multimorbidity and 3.41 per 1,000 person-years for those with multimorbidity. In Cox proportional hazards models adjusted for age, sex, ethnicity, education, socioeconomic status, and APOE-ε4 carrier status, multimorbidity was associated with an increased risk of incident dementia (hazard ratio [HR], 1.63).

The highest dementia risk was observed for the hypertension, diabetes, and coronary heart disease cluster (HR 2.20) and pain, osteoporosis, and dyspepsia cluster (HR 2.00) in women and in the diabetes and hypertension cluster (HR 2.24) and coronary heart disease, hypertension, and stroke cluster (HR 1.94) in men, compared with no multimorbidity. The associations between multimorbidity and dementia were greater in those with a lower genetic risk of dementia (HR 1.96) than in those with a higher genetic risk of dementia (HR 1.39). Similar findings were observed when stratifying diseases clusters by genetic risk for dementia.

Link: https://doi.org/10.1001/jamanetworkopen.2022.32124

GATA4 and Cellular Senescence

Researchers have in the past connected GATA4 expression to various age-related conditions, such as scarring in heart tissue. Here, they link GATA4 to cellular senescence, which is also implicated in many of the same conditions. Senescent cells accumulate with age, and their pro-growth, pro-inflammatory signals are disruptive to tissue function throughout the body. In recent years the evidence for clearance of senescent cells via senolytic therapies to be beneficial in older individuals has prompted greater research to connect cellular senescence to many other lines of research in the context of aging and age-related disease.

DNA damage can activate Ataxia telangiectasia-mutated serine/threonine kinase (ATM) and Rad3-related serine/threonine kinase (ATR), after which p53 activates p21, stopping the cell cycle and inducing cell senescence. GATA4 is a transcription factor that regulates signal response processes in many organs, such as cardiac precursor cell differentiation, cardiac development, cardiac hypertrophy, and resistance to apoptosis, as well as mediating the effects of genetic mutations caused by congenital heart disease.

GATA4 regulates proteins in a context-dependent manner, thereby performing multiple functions. It has been reported that GATA4 is regulated upstream by the DNA damage response (DDR) pathway co-opting ATM and ATR, and downstream in a manner different from the conventional DDR pathway, leading to senescence. GATA4 is regulated by ATM and ATR, which inhibit the binding of p62 and GATA4 to inhibit selective lineage autophagy of GATA4, thereby activating NF-κB, leading to cellular senescence. In addition, alterations in the GATA4 signaling pathway have been frequently observed in various age-related diseases, including atherosclerosis and heart failure.

This paper reviews the mechanisms through which the DDR signaling pathway leads to cellular senescence, the involvement of the GATA4 factor in these processes, as well as the link to atherosclerosis and heart failure. This provides many possibilities to invent a drug to inhibit GATA4 activity and thereby prevent cell senescence, but there are still many problems to be solved.

Link: https://doi.org/10.3389/fnagi.2022.933015

Correlation Between a Worse Gut Microbiome and Aging of the Heart

The state of the gut microbiome may be as influential on health as exercise. The balance of microbial populations changes with age, in detrimental ways, for reasons that are not fully understood. The decline of the immune system, responsible for gardening the gut microbiome and defending intestinal tissue, may be one of the more important factors. With age, microbial populations producing beneficial metabolites decline in number, while populations contributing to chronic inflammation grow in number. There are interventions, such as fecal microbiota transplant, that can reverse these changes in a lasting way to improve health in animal studies, but as yet this strategy has yet to be introduced into human medicine as a treatment for aging.

Measurement of the gut microbiome is now readily accomplished via metagenomic techniques, and so scientists can begin to correlate the size and presence of microbial populations with the state of age-related degeneration. In today's short open access commentary, researchers report on clear correlations between specific microbial populations and the aging of the heart, leading into cardiovascular conditions. The number of study participants is small, but it is nonetheless interesting data. More and larger studies of this nature should be undertaken, in combination with the development of therapies such as fecal microbiota transplantation, for widespread use in older people.

Distinct gut microbiota composition among older adults with myocardial ageing

Changes in cardiac structure and function occur with ageing and may lead towards ageing-related cardiovascular disease. Recent explorations into intestinal microbiota have provided important insights into shifts in microbial composition that occur in response to cardiovascular disease pathogenesis. Several proposed mechanisms include altered gut permeability, endotoxemia, and the systemic effect of metabolites including trimethylamine (TMA), short-chain fatty acids (SCFA), and secondary bile acids. However, causal associations between gut microbes and left ventricular (LV) function have yet to be proven. We sought to determine whether gut microbial composition is associated with left ventricular myocardial relaxation, an early manifestation of myocardial ageing, among older adults.

Among n = 15 participants (53% males, mean age 75 ± 4 years) recruited as part of a community-based research study on myocardial ageing, subjects with normal LV ejection fraction (60% and above) on baseline echocardiography were selected to undergo gut microbial composition examination in this proof-of-concept cross-sectional study. Myocardial ageing was assessed to be more impaired in those subjects with lower calculated ratios of peak early (E) to late diastolic (A, atrial contraction) velocities on Doppler echocardiography. We compared metagenomic reads between older adults with myocardial ageing (n = 8) vs. those without myocardial ageing (n = 7), based on E/A ratios.

Older adults with cardiac ageing had higher levels of several pathogenic gut bacteria. Ruminococcus, of the phylum Firmicutes, have been associated with higher C-reactive protein levels and higher pulse wave velocity. Certain Ruminococcus species are also capable of producing TMA, which has been linked to atherosclerotic disease and heart failure. Several Paraprevotella species, including P. xylaniphila, can produce pro-inflammatory metabolites, such as succinic acid, and is also associated with hypertension, metabolic diseases, and inflammatory diseases. Increase in gut Paraprevotella has been observed in association with the development of heart failure in mice.

Among individuals without cardiac ageing, we found higher levels of Firmicutes bacteria. Firmicutes are producers of SCFAs that regulate cholesterol levels, and some species have been associated with higher serum HDL. Reduced levels of Firmicutes were associated with LV hypertrophy and progression to heart failure in rats. In conjunction with higher levels of Bacteroidetes bacteria seen in our samples with cardiac ageing, we speculate that the balance between Firmicutes and Bacteroidetes (i.e., ratio) may be useful for studying gut microbial composition in relation to myocardial ageing in the future.

Reviewing Changes to the Actin Cytoskeleton in Aging and their Possible Consequences

Near every system within the body and within cells undergoes some form of change and degeneration with advancing age. A vast amount of work could be carried out by the research community, for decades yet, in order to provide even a high level understanding of how every cellular component changes with age, as well as the relationships between them, as one form of dysfunction causes others. The paper here offers an example of this sort of investigation, discussing the actin cytoskeleton in the context of aging, a structure that allows cells to control shape and movement.

At some point, more of the scientific impulse to catalog everything has to be diverted into building effective therapies to treat aging based on what is already known. Biology must give rise to medicine, or else what is the point? Given that we have a fairly good catalog of the root causes of aging, the research community is equipped to build potentially effective therapies without further deep understanding of the effects of aging on every cellular component. Address the causes age-related dysfunction, and we can hope that the rest of the cell takes care of itself.

Recent study reported that dynamic mitochondrial behavior, including the balance between fusion, fission, and movement, may play pivotal roles in regulation of mitochondrial activity. Mitochondria are transported along the actin cytoskeleton by specific motor proteins. The mechanical properties of the cytoskeleton significantly differ between old and young cells. The cytoskeleton exhibits increased stiffness and a decreased capacity to reversibly form in old cells. The mechanical properties of the cytoskeleton are important for transfer of mechanical signals. Therefore, both mechanical properties and cell stiffness linked with the cytoskeleton may be associated with mitochondrial functional activity in aging cells. However, the role of the actin cytoskeleton in mitochondrial dysfunction related with aging is unclear.

There are several lines of evidence that a relationship exists between the actin cytoskeleton and aging. Perturbed integrity of the actin cytoskeleton is connected with loss of mitochondrial function and aging. Several scientists have attempted to elucidate how modulation of the cytoskeleton can control aging. Chemical and biological stimuli and mechanical signals from extracellular environments can regulate cellular behaviors. Biophysical signals modulate the mechanical properties of the cytoskeleton. The mechanical properties of cells regulate cellular behaviors, such as proliferation, differentiation, and apoptosis. The mechanical properties of the cytoskeleton dramatically change with aging. Artificial disturbance of the cytoskeleton induces aging phenotypes, such as slow proliferation and increased mitochondrial dysfunction. Aged cells treated with a cytoskeleton stabilizer exhibit reversal of aging phenotypes due to recovery of mitochondrial functional activities.

Taken together, these findings demonstrate that the cytoskeletal stability is a key factor for reversal of aging.

Link: https://doi.org/10.3390/cells11182896

Air Pollution Correlates with Risk and Outcome of Stroke

Exposure to air pollution tends to inversely correlate with wealth and socioeconomic status, both of which clearly correlate with health in epidemiological studies. More careful studies of similar populations with differing exposure, and what is known of the biochemistry of tissue interaction with particulate matter, make it reasonable to think that the effects of particulate air pollution on chronic inflammation - and thus pace of development of atherosclerosis - play a role in the comparatively poor health of those people in regions of greater pollution. One of the outcomes of atherosclerosis is stroke, and as noted here, particulate air pollution correlates with greater risk of stroke and worse outcomes following stroke.

The study involved 318,752 people in the UK biobank database with an average age of 56. The participants did not have a history of stroke or cardiovascular disease at the start of the study. Researchers looked at people's exposure to air pollution based on where they lived at the start of the study. The participants were followed for an average of 12 years. During that time, 5,967 people had a stroke. Of those, 2,985 people developed cardiovascular diseases and 1,020 people later died. People exposed to high levels of air pollution were more likely to have a first stroke, post-stroke cardiovascular disease or death than people not exposed to high levels of pollution.

After adjusting for other factors that could play a role, such as smoking and physical activity level, researchers found that for each 5 micrograms per cubic meter (µg/m3) increase of fine particulate matter, for example, the risk of transitioning from being healthy to having a first stroke increased by 24% and from being healthy to dying the risk increased by 30%. Particulate matter consists of liquids or solids suspended in air. Fine particulate matter, PM2.5, is less than 2.5 microns in diameter and includes fly ash from coal combustion. Those who had a stroke during the study had an average exposure of 10.03 µg/m3 of PM2.5, compared to 9.97 µg/m3 for those who did not have a stroke. The researchers also found that the pollutants nitrogen oxide and nitrogen dioxide were associated with an increased risk of stroke and death.

Link: https://www.eurekalert.org/news-releases/965849

Interventions Testing Program Results for Rapamycin and Arcabose in Combination

The Interventions Testing Program (ITP) at the National Institute on Aging (NIA) performs rigorous, expensive assessments of the ability of various (usually pharmaceutical) interventions to slow aging in mice. Conducting a study with rigor in this context means the use of large numbers of mice spread across multiple facilities, with careful control of the environment in order to minimize both known and unknown confounding factors in life span studies. Most of the interventions tested over the past twenty years of the ITP, on the basis of earlier studies suggesting that they may slow aging, in fact fail to extend life in mice once put under this degree of scrutiny. This outcome says something about the difficulty of robustly determining whether or not any given approach actually slows aging to a great enough degree to be useful. We should be suspicious of any single study in mice.

Today's open access paper is an update from the ITP, outlining the results from some of their recent work. It is interesting to note that the ITP is starting, slowly, to test combinations of interventions. There is far too little work taking place in the scientific community when it comes to assessing combinations of treatments that impact aging. Yet since degenerative aging comprises many distinct, very different processes, any effective approach must necessarily combine different interventions targeting different mechanisms.

The ITP has not yet branched out from dietary supplements and pharmaceuticals to test many of what I would consider to be interesting approaches. There is the potentially senolytic fisetin (which showed no effect on mouse life span at the dose used), but beyond that, the portfolio of interventions tested consists of line items that we should not expect to have meaningfully large impacts on human life span. The best and most reliable of these interventions is rapamycin, which, like most other approaches shown to extend life in mice, mimics aspects of the metabolic response to calorie restriction. We know that calorie restriction, while producing benefits to health, certainly doesn't extend life span by anywhere near as much in humans as it does in mice.

Lifespan benefits for the combination of rapamycin plus acarbose and for captopril in genetically heterogeneous mice

Eight of the 35 agents tested by the ITP have significantly increased lifespan in one or both sexes. None has shortened lifespan. Five of the 8, that is, nordihydroguaiaretic acid (NDGA), aspirin, 17-α-estradiol (17E2), Protandim, and canagliflozin have increased lifespan only in males. None of the agents tested to date has increased lifespan only in females. Three agents led to significant lifespan increased in both sexes, but with varying degrees of sex-specificity. Glycine, for example, led to small but similar increases, significant in both sexes. Acarbose effects were more dramatic in males than in females at any of the three tested doses, and if started later in life, that is, at 20 months of age. Rapamycin, over a range of doses and at two starting ages, has had strong positive effects in both sexes, but at a given dose in chow typically leads to a larger percentage increase in female than in male mice, Five of the agents that increase lifespan (NDGA, aspirin, rapamycin, 17E2, and acarbose) have been re-examined in later cohorts with different dosages and treatment durations. Of these, only aspirin did not replicate, although it was only tested at higher doses.

The ITP has also begun to test combinations of lifespan-extending agents for potential additive effects. Metformin and rapamycin were tested in combination based on the hypothesis that the insulin-sensitizing action of metformin might compensate for the potentially deleterious insulin desensitizing effect of rapamycin and potentially different mechanisms of action of the two agents might have additive effects on survival. The results were not entirely clear-cut because in both sexes the combination of metformin and rapamycin led to a larger percentage benefit compared with simultaneous controls than had been seen in previous studies of rapamycin alone, but the benefit of the combination over rapamycin-only historical controls was not statistically significant. Here, we extend this strategy, testing rapamycin and acarbose in combination, starting at 9 or 16 months of age, based on a similar rationale to that used for the metformin/rapamycin trial.

In male mice, the combination of rapamycin and acarbose produced a larger absolute and percentage change in survival than that seen in mice that had, in previous years, received the same dose (14 ppm) of rapamycin alone. Rapamycin-treated males in the previous C2006 cohort lived, on average, 10% longer than simultaneous controls (average of values at each site), and in the previous C2009 cohort males lived an average of 5% longer than controls. The males in the current study dosed with rapamycin and acarbose lived 19% longer, more than twice the percent change seen in either of the two earlier studies.

NALCN is a Regulator of Cancer Metastasis

If cancers were not metastatic, did not spread themselves throughout the body, then cancer would be a much less dangerous medical condition. Tumors would be largely amenable to surgical removal, and long-term control and suppression of cancer, even at late stages, would be a feasible goal. Thus research into the biochemistry of metastasis is important. If commonalities exist in the regulation of metastasis across many cancers, interventions to suppress metastasis could lead to a sizable reduction in cancer mortality. The research here shows that cancers may hijack an existing regulatory mechanism controlling cell motility in order to become metastatic, which in turn suggests that this mechanism may prove to be common to many types of cancer, and thus a promising point of intervention.

Researchers found that blocking the activity of the NALCN protein in cells in mice with cancer triggers metastasis. They also discovered that this process is not just restricted to cancer. To their surprise, when they removed NALCN from mice without cancer, this caused their healthy cells to leave their original tissue and travel around the body where they joined other organs. They found, for example, that healthy cells from the pancreas migrated to the kidney where they became healthy kidney cells. This suggests that metastasis isn't an abnormal process limited to cancer as previously thought, but is a normal process used by healthy cells that has been exploited by cancers to migrate to other parts of the body to generate metastases.

Despite being one of the main causes of death in cancer patients, metastasis has remained incredibly difficult to prevent, largely because researchers have found it hard to identify key drivers of this process that could be targeted by drugs. Now that researchers have identified NALCN's role in metastasis, the team are looking into various ways to restore its function, including using existing drugs on the market.

NALCN stands for sodium (Na+) leak channel, non-selective. Sodium leak channels are expressed predominately in the central nervous system but are also found throughout the rest of the body. These channels sit across the membranes of cells and control the amount of salt - that is, sodium - that goes in and out of the cell. Controlling this process also alters the balance of electricity across the cell membrane. It is not yet clear why these channels seem to be implicated so directly in cancer metastasis.

Link: https://www.cam.ac.uk/research/news/breakthrough-in-understanding-of-how-cancer-spreads-could-lead-to-better-treatments

Magnetic Fields Modestly Extend Life in Nematode Worms via Effects on Mitochondrial Function

Electromagnetic effects on cellular biochemistry, and their potential use as interventions, are little studied in comparison to the use of pharmaceutical agents. That state of affairs shows little sign of changing in the near future, despite the existence of interesting studies on regeneration, or this one on the longevity of nematodes. Researchers pin down a potential mechanism to explain how a magnetic field can alter the activities of cells in ways that modestly extend life in this short-lived species. It is worth noting that nematode life span is very plastic in response to circumstances and interventions. Approaches that have little effect on longer-lived mammals can double the life span of a nematode, so the 18% median life extension noted here should be taken as a small effect size in the bigger picture. Nonetheless, the mechanism is quite interesting.

Ageing is regulated by intrinsic genetic pathways and in response to extrinsic environmental cues. Diet and temperature are widely reported to modulate longevity through a network of molecular signalling. The magnetic field is another critical environmental factor to all life on earth, which has a mild dipolar geomagnetic field (GMF) of 25-65 μT. Whereas artificial magnetic fields of high energy are hazardous by ionizing and thermal effects, GMF is known to have many significant biological effects. Magnetotactic bacteria sense GMF for cellular migration. Other organisms across taxa, such as butterflies, salmon, and birds, are considered to navigate over long distances by tracing GMF. The moderate magnetic field has recently been shown to regulate immune cell function and redox homeostasis. Given its various biological effects, it is intriguing to explore the potential influence of the moderate magnetic field in ageing and the underlying mechanisms.

The nematode Caenorhabditis elegans is a well-established model organism in ageing research, with conserved ageing phenotypes and mechanisms. Adult C. elegans is around 1 mm in length and 31-72 μm in diameter. In lab, these tiny worms are grown on a two-dimensional bacteria lawn. These features make it easy to treat multiple worms and different worm tissues with similar magnetic field intensity. Moreover, C. elegans was suggested to sense GMF during vertical burrowing migrations. Here, we investigated the effect of a moderate magnetic field on worm ageing. Our results indicate that a static magnetic field (SMF) of 10 mT extends worms lifespan and enhances the motility of aged worms, potentially through inhibiting the ageing-related changes of mitochondrial morphology and function. We further found that SMF treatment upregulates a group of cytochrome P450 (CYP) genes to induce longevity.

CYPs have intensive interaction with mitochondria. Mitochondria is a major cellular organelle of CYPs localisation. The mitochondrial electron transport system serves as an electron donor for mitochondrial CYPs catalytic activity, whereas the products of CYP-dependent metabolism affect mitochondrial functions. CYP2U1, the mammalian ortholog of the three CYPs in SMF-induced longevity, is localised in mitochondria and controls mitochondrial morphology. As the three CYPs also regulate the morphological changes of mitochondria during worm ageing, it will be interesting to clarify their interaction with mitochondria further and to pursue the potential role of CYP2U1 in mammal ageing.

Link: https://doi.org/10.1038/s41598-022-20647-0

Still No Success Worthy of the Name in Anti-Amyloid Immunotherapies to Treat Alzheimer's Disease

Work on immunotherapies that can clear amyloid-β from the brain, an approach to treating Alzheimer's disease, continues to slowly grind out incremental benefits. First, the prospective treatments failed to clear amyloid-β, then they failed to show any degree of patient benefits, and now the latest trial data indicates a minor slowing of progression in Alzheimer's patients. It is unclear where the ceiling lies in this slow and painful process. Amyloid-β clearance is in principle a good idea, and implementations may become useful, given time and better understanding. It is certainly the case that an expensive therapy that merely slows the progression of Alzheimer's by 27% is not much of a therapy, however.

Sadly, the incentives operating on the leadership of pharmaceutical companies working with therapies targeted to large patient populations tend to favor efforts to spin mediocre outcomes into a success story. Medical regulation makes it so expensive to deploy new therapies that only very large organizations can carry work forward into late stage clinical trials, where the costs rise into the hundreds of millions of dollars. These organizations are beholden first and foremost to their shareholders, not to the patient community. Not that it would be any better were large governmental agencies to do the same thing.

Finally: Big Win on All Outcomes for Lecanemab in Phase 3 Topline Results

Eisai and Biogen yesterday announced positive topline results from the Phase 3 Clarity trial of their anti-amyloid antibody lecanemab. The drug slowed decline on the primary endpoint, CDR-SB, by 27 percent over 18 months, and also nudged down decline on all secondary clinical endpoints. The incidence of the brain edema known as ARIA-E was 12.5 percent, about one-third of that seen with Biogen's approved anti-amyloid antibody Aduhelm. That said, researchers also noted the absolute difference in CDR-SB scores was small, at 0.45, with some questioning how clinically meaningful this is. In the bigger picture, researchers said the data strengthen the amyloid cascade hypothesis. "This confirms the importance of Aβ in disease pathogenesis. This is the first time a therapeutic antibody has clearly changed the course of Alzheimer's disease. It is a pivotal moment in the history of Alzheimer's therapy."

Five big questions about the new Alzheimer's treatment

In the study, people getting lecanemab still had cognitive decline, but it progressed 27% slower than in those on a placebo. That translates to 0.45 points on the 18-point CDR-SB. Although the difference is modest, it's spawning hope. "This does make us feel a little better. These drugs do work." Lecanemab had side effects, most notably certain brain abnormalities seen with other anti-amyloid therapies, including swelling and small hemorrhages in the brain. Neuroimaging turned up these concerns in about 21% of patients on lecanemab, and 9% of those on the placebo. Although these abnormalities often produce no symptoms, about 3% of those getting lecanemab did have symptoms from them.

Doctors aren't sure how the apparently gentler slope of cognitive decline would be perceived by patients and their families. "Does that mean that grandma is going to have a few better days, a few better months, a few better years? It's still an open question." Commenters hesitate to make grand pronouncements, especially after last year's flameout of aducanemab. "We're all feeling a sense of wariness and caution. We want to dig into the data before we make any large conclusions."

The Evident Good of Treating Aging as a Medical Condition

It seems a little strange that advocates for aging research must still make the argument that it is a good thing to prevent people from becoming sick and dying. This seems self-evident! It is true that prevention and cure of disease is a goal with widespread support when discussing specific diseases or age-related conditions. Yet, somehow, as soon as one starts to talk about treating aging as a medical condition, the root cause of the majority of disease and suffering, we are right back to objections that amount to defending a world in which people become sick and die. It is a strange situation that is hard to understand.

As long as there have been humans, there has been death. There's evidence that funeral rituals may date back hundreds of thousands of years, so it's likely our species has grappled with its finitude for at least tens of millennia. Is knowing it will end what motivates us to succeed, or provides meaning at all? The first thing to say is that this is one of many objections that demonstrate how we put ageing research into its own ethical category - no-one would ask a cancer researcher whether they're concerned that a reduction in death arising from their research might negatively affect the human condition, and yet, for ageing biologists, this is a common query.

Much of the meaning in our lives comes from the people that fill it, our families and friends. And much of the pain, both emotional and physical, results from ill health, either theirs or our own. If we were all living longer lives in good health, as medicines against ageing promise, why wouldn't we want to continue living? And as art, music, science, technology and more continue to advance (perhaps to new places only possible thanks to creators or researchers with extended careers, able to make discoveries only possible with extra decades of experience), it seems incredibly unlikely that we'd get bored.

And, even if we do tire of life itself aged 250, wouldn't you rather go in a short, painless manner at a time of your own choosing, rather than having life slowly and painfully taken from you over decades by the ageing process? The key point is that medicines for ageing are just that - medicine. They're no stranger than a heart disease researcher trying to prolong healthy life by creating a drug to lower cholesterol. There's no real evidence that the extra years bought by preventing heart attacks have stripped modern life of its meaning - so why would adding a few more years free from heart attacks and cancer and frailty do so?

Link: https://www.polytechnique-insights.com/en/columns/health-and-biotech/science-says-we-could-cure-ageing-but-should-we/

DNA Damage and Inflammation in Aging

Both stochastic DNA damage and chronic inflammation are characteristic of aging. DNA damage can contribute to inflammatory signaling via a range of mechanisms, but, as noted here, it is challenging in a system as complex as our cellular biochemistry to pick apart the relative importance of these mechanisms. It is nonetheless reasonable to think that some fraction of the unresolved inflammation of aging, disruptive to tissue function throughout the body, results from the increased amount of DNA damage in later life.

Persistent DNA lesions build up with aging triggering inflammation, the body's first line of immune defense strategy against foreign pathogens and irritants. Once established, DNA damage-driven inflammation takes on a momentum of its own, due to the amplification and feedback loops of the immune system leading to cellular malfunction, tissue degenerative changes, and metabolic complications.

There is much work to be done before we will be able to dissect the functional links between persistent DNA damage and inflammation in vivo. The use of progeroid murine models with tissue-specific defects in genome maintenance will allow us to further delineate the causal contribution of specific cell types to systemic inflammation with old age. In parallel, animal models with tagged DNA repair factors coupled to functional genomics and proteomics strategies may prove valuable for identifying new gene targets or protein partners that could link genome maintenance with innate immune signaling. It will also be essential to identify how an active DNA damage response originating from any alterations in the physicochemical structure of the DNA activates cytoplasmic stress responses and the release of proinflammatory factors in the tissue microenvironment.

Likewise, it will be vital to dissect the functional links between DNA damage-driven chronic inflammation and metabolic rewiring with old age. Finally, the recent development of novel therapeutic strategies indicates that, in the long run, it may be more valuable to invest in approaches targeting the DNA damage itself rather than suppressing downstream proinflammatory signals. Such strategies could open new, meaningful avenues towards the development of new rationalized therapeutic interventions against a wide range of adverse pathological outcomes during aging

Link: https://doi.org/10.3389/fragi.2022.973781

The Problem with Biomarkers of Aging

Today's research materials illustrate the primary challenge faced by those who want to develop and use biomarkers of aging, ways to measure biological age rather than chronological age. All reasonable biomarkers of aging are actually useful and informative when it comes to unmodified aging. This is true of everything from combinations of simple tests, such as walking speed and grip strength, through to more modern contrivances based on machine learning techniques applied to epigenetic, transcriptomic, proteomic, or other voluminous data on the state of our biology that can be easily produced these days. One can see clear correlations between these biomarkers and mortality, and between these biomarkers and state of health in later life.

The problem arises once we start considering the effective treatment of aging as a medical condition. Not aging as a whole, of course, because aging is a set of diverse processes and their consequences that are very different from one another, and require very different strategies in order to build meaningful therapies. When testing a rejuvenation therapy that repairs one form of damage, or reverses one process of the many processes of aging, how will that treatment affect measures of aging? The answer probably differs on a case by case basis, and at present, despite the existence of at least one approach to rejuvenation that has actual, working therapies, meaning the clearance of senescent cells via senolytic treatments, there is no map to connect treatment to effect on biomarkers.

In practice, this means that biomarkers can't be trusted as tools to evaluate whether or not potential rejuvenation therapies are actually any good, at least until after researchers have run many life span studies using both those therapies and those biomarkers in order to produce a calibration. That will take a good deal of time and effort, and makes biomarkers for aging a very much less useful than hoped at the present time.

Biomarkers used to track benefits of anti-ageing therapies can be misleading

The nematode C. elegans begin adulthood vigorously exploring their environment. Over time, they slow and stop crawling, a behavioural stage known as vigorous movement cessation (VMC). VMC is a biomarker of ageing and a proxy for nematode health. Studies of genetically identical nematodes have shown it is a powerful predictor of a worm's lifespan, but at the same time, interventions designed to alter ageing can disproportionately affect VMC in comparison to lifespan and vice versa.

Researchers developed the 'Lifespan Machine', a device that can follow the life and death of tens of thousands of nematodes at once. The worms live in a petri dish under the watchful eye of a scanner that monitors their entire lives. By imaging the nematodes once per hour for months, the device gathers data at unprecedented statistical resolution and scale. The research team found that nematodes have at least two partially independent ageing processes taking place at the same time - one that determines VMC and the other determines time of death. While both processes follow different trajectories, their rates are correlated to each other, in other words, in individuals for whom VMC occurred at an accelerated rate, so did time of death, and vice versa. In other words, the study revealed that each individual nematode has at least two distinct biological ages.

The study calls into question a crucial assumption of ageing biomarkers, that when interventions such as exercise or diet "rejuvenate" a biomarker, it's a good sign that the underlying biology of ageing has similarly changed. "Our model shows that biomarkers can be trivially decoupled from outcomes because they measure an ageing process that is not directly involved in the outcome but simply correlates with it in a system of hierarchical processes. In simple terms, just because two parts of an individual tend to correlate in their biological age across individuals, it doesn't mean that one causes the other, or that they are likely to involve shared ageing mechanisms."

A Hierarchical Process Model Links Behavioral Aging and Lifespan in C. elegans

Individuals who remain vigorous longer tend to live longer, supporting the design of predictive behavioral biomarkers of aging. In C. elegans, the timing of age-associated vigorous movement cessation (VMC) and lifespan correlate strongly between individuals. However, many genetic and pharmaceutical interventions that alter aging produce disproportional effects on VMC and lifespan, appearing to "uncouple" the rate of behavioral aging and lifespan. To study the causal structure underlying such uncoupling, we developed a high-throughput, automated imaging platform to quantify behavioral aging and lifespan at an unprecedented scale.

Our method reveals an inverse correlation between each individuals' vigorous movement span and their remaining lifespan. Robust across many lifespan-altering interventions, our data shows that individual C. elegans experience at least two distinct but coupled physical declines - one governing VMC and the other governing lifespan. Through simulations and modeling, we clarify the causal relationship between these two "biological ages" and highlight a crucial but often untested assumption in conventional aging biomarker research: predictive biomarkers may not always report on the same biological age as that which determines long-term health outcomes.

Clearance of Senescent Cells Improves Immune Cell Function in the Aged Brain

Immune cells resident to the brain become more activated and inflammatory with age. Researchers have found that at least some of these cells are senescent, generating inflammatory signaling. Clearing these cells via senolytic therapies, such as the well-established dasatinib and quercetin combination, reduces inflammation and markers of neurodegeneration in mice. In the study here, researchers instead use genetic means of selective senescent cell destruction in mice, and see similar improvements. There is an ongoing trial of senolytics as a means to treat Alzheimer's disease; to the degree that Alzheimer's is primarily driven by immune dysfunction and chronic inflammation in brain tissue, a view of the condition that is gaining traction, this seems a sensible test of the ability of senolytics to impact inflammatory age-related disease in humans to the same degree that it can in mice.

Cellular senescence is a plausible mediator of inflammation-related tissue dysfunction. In the aged brain, senescent cell identities and the mechanisms by which they exert adverse influence are unclear. Here we used high-dimensional molecular profiling, coupled with mechanistic experiments, to study the properties of senescent cells in the aged mouse brain. We show that senescence and inflammatory expression profiles increase with age and are brain region- and sex-specific. p16-positive myeloid cells exhibiting senescent and disease-associated activation signatures, including upregulation of chemoattractant factors, accumulate in the aged mouse brain. Senescent brain myeloid cells promote peripheral immune cell chemotaxis in vitro.

Our results suggest several scenarios by which senescent cell targeting may beneficially influence brain immune cell composition. First, p16-positive brain myeloid cells (resident microglia and infiltrating myeloid cells) may drive peripheral immune cell recruitment, and their targeting may prevent a shift to homeostatic imbalance, characterized by infiltration of activated, potentially senescent, circulating inflammatory cells. Second, other senescent cell types (e.g., p16-positive astrocytes, oligodendrocytes, and endothelial cells) may also exert proinflammatory influence and may also be cleared. Third, reducing the abundance of circulating senescent immune cells may thereby deplete the pool available for recruitment into the brain under steady-state inflammatory conditions. Fourth, systemic senescent cell elimination may reduce the abundance of senescent cells throughout the body that contributes senescence-associated secretory phenotype (SASP) factors to the circulating progeronic proteome, which is a driver of age-related brain dysfunction.

Based on the established influence of circulating senescent inflammatory cells and SASP factors as mediators of organ homeostasis, we assert that rejuvenation of the inflammatory brain cell landscape and associated improvements in cognitive function following clearance of p16-positive cells in aged mice may reflect a combination of senescent cell elimination in the brain, periphery, and circulation.

Link: https://doi.org/10.1038/s41467-022-33226-8

Alzheimer's Disease as Innate Autoimmunity

The failure of amyloid-β clearance via immunotherapy to produce benefits in Alzheimer's disease patients has spurred a great deal of theorizing, attempts to find a new way forward. Most researchers, from a survey of the field, continue to believe that amyloid-β aggregation is an important contributing factor in at least the early development of Alzheimer's. However, an increasing emphasis on immune dysfunction and chronic inflammation is creeping into modified versions of the amyloid cascade hypothesis, alongside different interpretations of the role of amyloid-β in this process, based on its participation in the innate immune response as an anti-microbial peptide.

The role of amyloid-β (Aβ) in Alzheimer's disease (AD) is debated: some argue Aβ takes center stage as the principal actor; others contend it is merely a spectator in the pageant of pathologies that typify AD. Nonetheless, a diversity of data (including in vitro neurotoxicity studies and genetic linkage analyses) do compellingly link Aβ to AD's pathology. Accordingly, rather than unconditionally rejecting the role of Aβ (or any other proposed specific disease mechanism), the need for an innovative broadly encompassing model of AD, which harmonizes multiple divergent theories into a single unified comprehensive explanation, emerges as a much-needed milestone on the road to a cure.

Herein, such a broad new molecular-level model of AD is proposed: "Alzheimer's disease as an autoimmune disease" ("AD-squared" or "AD2"). In the AD2 model, AD is explained as a brain-centric disorder of innate immunity involving concurrent autoimmune and autoinflammatory mechanisms. Although AD2 still includes Aβ as an important molecular player, it rejects the "amyloid misfolding hypothesis" per se, instead recognizing Aβ as a physiologically oligomerizing cytokine-like immunopeptide, which is merely one part of a much larger, comprehensive, highly interconnected immunopathic conceptualization of AD.

The AD2 model may be summarized as follows: in response to diverse pathogen-associated molecular pattern (PAMP) and damage-associated molecular pattern (DAMP) immune-stimulating events (e.g., infection, trauma, ischemia, air pollution, depression), Aβ is physiologically biosynthesized and released as an early responder immunopeptide, and triggers an innate immunity cascade in which oligomeric Aβ exhibits both immunomodulatory and antimicrobial properties. The immunomodulatory properties of Aβ (mediated via Aβ's oligomeric interactions with TREM2, glycosaminoglycan, and NLRP3 receptors) augment ongoing microglial activation and pro-inflammatory cytokine release thereby ultimately contributing to apoptotic neuronal death via non-specific autoinflammatory processes in which bystander neurons are killed.

Link: https://doi.org/10.1002/alz.12789

Commentary on Old Age in the International Classification of Diseases

The world of medicine and medical research is regulated to the point of extreme dysfunction. Regulation determines the flows of funding in the clinic, which in turn determines priorities for research and development. To swim against the tide is significantly harder than to go along with it, and this has a material effect on the speed with which the scientific community and biotech and pharmaceutical industries can create and deploy therapies to treat aging. Even the prospect of treating aging as a medical condition at all is shadowed by the way in which regulation distorts the playing field. Yes, a working, proven rejuvenation therapy will ensure its own success, and all positions will rapidly adjust to the new reality, but getting to the point of making such a therapy, and getting to the point of proving it sufficiently well to convince the world, is made significantly harder by the perverse incentives of medical regulation.

Today, I'll point out a little of the ongoing commentary surrounding one of the most bureaucratic, slowest aspects of medical regulation, the periodically updated International Classification of Diseases (ICD), now up to version ICD11. The ICD is relevant because much of the developed world bases their medical regulation on the classifications in the ICD. If a condition is not included in the ICD in a usefully explicit way, then the barriers to gaining approval for a therapy are very high indeed. That in turn shapes all of the research and development priorities leading up the creation of new therapies. The ICD is managed by the World Health Organization (WHO), a body that exemplifies the traits of large bureaucracy to the point of self-parody. For example, as the first commentary indicates, avoiding the appearance of ageism is a somewhat higher priority than encouraging development of means to treat aging in order to reduce late life suffering and mortality.

None of this is ideal, and at present most biotech startups in the longevity industry are doing their best to avoid the whole situation by devoting their efforts towards treating specific defined conditions of aging, rather than aging in general. That has its own disadvantages when it comes to turning science into treatments that are broadly rather than narrowly beneficial. It leads me to the belief that the best way forward, in the bigger picture, is to use philanthropic funding to pay for clinical trials that produce compelling demonstrations of human rejuvenation, compelling enough to shake up the regulatory system. At the present time, I think that the fastest path to this outcome is to show the world, beyond a doubt, that senolytic treatments can rejuvenate the old, and that the very impressive results achieved in aged mice can be replicated in humans.

How "old age" was withdrawn as a diagnosis from ICD-11

WHO had proposed the inclusion of the term "old age" in ICD-11. Ageing is not a pathological process and is globally accepted as a normal human attribute, with longevity being a privilege that we all hope to enjoy. The new "old age" label in ICD-11 was intended to replace the R54 code of "senility", previously used in ICD version. The decision to replace the R54 code resulted from increasingly negative connotations around the term "senility". An additional extension code (XT9T) was included in the causality section of ICD-11, which defined "ageing-related" as "caused by pathological processes which persistently lead to the loss of organism's adaptation and progress in older ages". The intention for including the additional code was to provide a greater focus on the biological aspects of ageing in global health policy and better opportunities for the development of new biological therapies. However, because of societal ageism, and because biological ageing and chronological ageing are not synonymous, the addition of these two codes left the ICD-11 proposal with potential for unintended negative consequences.

To be clear, WHO's inclusion of "old age" in ICD-11 was not intended to cast age or ageing as a disease, nor to consider ageing in terms of the number of years since birth, or greater than a particular age category. The intention was to recognise that the physiological process of ageing has a detrimental effect on a person's intrinsic capacity. In the context of healthy ageing, "ageing associated decline in intrinsic capacity", in very sharp contrast to the diagnosis of "old age", would be fully aligned with and reflect the ICD's purpose, and accomplish the ICD's envisioned resolutions. With global ageing, an urgent imperative exists to accurately assess population health and to holistically target maintenance and optimisation of physical and cognitive function, which would also be possible by enhancing ICD's reporting system with use of the term "ageing associated decline in intrinsic capacity". We believe there would be a substantial shift of focus with use of this term, from a static to a dynamic assessment of the person's health and capacity across a life trajectory.

Advanced pathological ageing should be represented in the ICD

The latest version of the International Classification of Diseases, ICD11, supports installed new dynamics in the nascent field of longevity medicine by classifying ageing as a disease. It allows physicians to target ageing in a comprehensive rather than a less efficacious disease and syndromes-oriented manner. Researchers have called for excluding old age from ICD-11, suggesting replacement by frailty.

Whether the term old age is the best choice of terminology for a state of multi-malfunction is a semantic, redundant debate. First, ICD codes are carefully considered and revised before being implemented. Secondly, frailty refers to, mostly but not exclusively, age-related disabilities, although old age is not always associated with frailty. Thus, these terms are not mutually exclusive and can co-exist in the ICD, as a part of a hierarchy of causation. The extension code XT9T guarantees coding for measurable age-related processes - eg, inflammageing, mitochondrial dysfunctions, etc.

The MG2A code, on the other hand, is representative of the paradigm shift in the definition of an individual's age, from chronological to biological, and will promote the development of therapies to optimise biological age. This paradigm shift in the definition of age, along with technological advances in the ability to control biological age, has led to considerable investment in the field of longevity to develop interventions targeting ageing mechanisms and systemic rejuvenation rather than a single organ or system at a time.

Targeting the Gut Microbiome to Treat Aging

The distribution of microbial populations making up the gut microbiome changes with age in ways that are harmful to health, causing a reduction in production of beneficial metabolites and an increase in chronic inflammation. Animal studies make it clear that some approaches to restoring a more youthful gut microbiome, such as fecal microbiota transplantation from young donors, can produce a sustained rejuvenation of the gut microbiome and consequent improvement in later life health. Given the comparatively simplicity of this approach, and that the state of the gut microbiome can accurately measured via low-cost assays, this seems a cost-effective, near-term approach to the treatment of aging.

The link between human health and the gut microbiome is profound and has been speculated upon for thousands of years. In 400 B.C., it was suggested by Hippocrates that "bad digestion is the root of all evil" and "death sits in the bowels". It is now well-known that humans are inhabited by microorganisms, including bacteria, viruses and archaea, that live in harmony with them. Many aspects of human health are also influenced by the gut microbiota, as they may provide energy and nutrients to the host by aiding the digestion of nondigestible dietary components and can also contribute to inflammation, infection, gastrointestinal diseases, diabetes mellitus, and obesity. Interestingly, the composition of the human gut microbiota shifts with age, leading to influenced changes in the host's health. In this regard, the disturbance of the microbiome has been suggested as a new hallmark of ageing.

Diet can be used to modulate the composition of gut microbiota. An abundance of short-chain fatty acids, which are produced by gut microbes and have been shown to exhibit protective roles against a panoply of diseases, has been shown to correlate with diet. It was shown that as compared to an animal-based diet, vegan and vegetarian diets which comprise greater intake levels of fibre, resulted in higher levels of short-chain fatty acids. Interestingly, calorie restriction is known as the only experimental procedure that can, in various animal models, effectively lengthen lifespan. In a study that studied the shift in gut microbiota induced by a high-fat diet versus a low-fat diet in mice, it was demonstrated that mice with a 30% restriction of low-fat diet had a unique gut microbiota, indicating that modulation of the gut microbiota can be achieved by restricting the intake of diet.

Prebiotics - nondigestible food ingredients that are metabolized by selective intestinal microorganisms - can be used to modulate the gut microbiota to increase the abundance and activities of beneficial bacteria. Prebiotics resist digestion in the small intestine to reach the colon, where they are acted upon by gut microflora, leading to specific changes in composition and activity in the gut microbiota. Probiotic supplementation has been applied in the modulation of the gut microbiota to convey health benefits. Probiotics are defined as live microorganisms that confer to improve the health of the host when adequate amounts are administered in a safe and efficacious manner. Several studies have supported the use of probiotic supplementation for its therapeutic effects against a broad range of diseases, especially for metabolic and gastrointestinal disorders. In addition, the ability of probiotic supplementation to modulate the gut microbiota was reported in terms of faecal bacterial community structure being significantly different as compared to placebo.

Faecal microbiota transplantation is the administration, into a recipient's intestinal tract, of the whole microbiota from healthy donor faeces to modify or normalize intestinal microbiota composition. The ability of faecal microbiota transplantation to treat several diseases, including irritable bowel syndrome, metabolic diseases, autoimmune diseases, constipation, neuropsychiatric conditions, colon cancer, chronic fatigue syndrome, and allergic disorders, has been reported. The ability of faecal microbiota transplantation to treat Clostridioides difficile infection in the elderly (85 years old and above) was recently investigated, and the report indicated that severe infections in all cases were improved following one faecal microbiota transplantation, indicating that "frail older people" might benefit from faecal microbiota transplantation.

It is now clear that the age-related dysbiosis of the gut microbiota may lead to unhealthy ageing, contribute to the development of comorbidities and may even dictate the lifespan of individuals, as shown in the previous sections. Hence, by inducing changes in the gut microbiota, it might be possible to improve the health of the elderly and even prolong their lifespan.

Link: https://doi.org/10.3390/microorganisms10091869

Atherosclerosis Leading to Peripheral Artery Disease Impacts Muscle Function via Reduced Blood Flow

Researchers working on a new way to assess the progression of peripheral artery disease here note how this consequence of atherosclerosis harms function of muscles via reduced blood flow. Reduced blood flow is in fact something of a theme in aging, as the heart weakens, physical activity is reduced, capillary density in tissues declines, and atherosclerotic lesions grow to the point of narrowing critical arteries. This is all good reason to find approaches to minimize and treat atherosclerosis, develop strategies to provoke greater angiogenesis in later life to better maintain capillary networks, and stay active.

Peripheral artery disease (PAD) affects more than 7% of Americans over age 40 and more than 29% of those over 70. The disease can cause pain when walking, coldness or numbness in the lower leg, painful leg or arm cramps, difficulty sleeping and erectile dysfunction, among other symptoms, though it also may cause no symptoms at all. The lack of adequate blood flow to the limbs may make it difficult for wounds to heal and can, in severe cases, lead to amputation. Existing treatments include medicine to improve blood flow and manage pain; for appropriate cases, doctors may also consider options such as surgery or the placement of a stent to open clogged arteries.

Researchers were able to use a new magnetic-resonance imaging (MRI) technique at the end of exercise to understand the effects of PAD in the calves of patients with the disease and distinguish them from normal volunteers. The approach they used, called chemical exchange saturation transfer, or CEST, produced results comparable to the current gold standard. CEST, they found, offered added benefits without requiring highly specialized equipment unavailable to many hospitals and researchers. "The beauty of CEST is that it creates an image of energy stores in the muscle which we can match to images of blood flow. This gives us a new understanding of how atherosclerosis in the leg arteries causes problems in the muscles downstream."

Link: https://www.eurekalert.org/news-releases/965636