Fight Aging!

Fight Aging! publishes news and commentary relevant to the goal of ending all age-related disease, to be achieved by bringing the mechanisms of aging under the control of modern medicine. This weekly newsletter is sent to thousands of interested subscribers. To subscribe or unsubscribe from the newsletter, please visit: https://www.fightaging.org/newsletter/

Longevity Industry Consulting Services

Reason, the founder of Fight Aging! and Repair Biotechnologies, offers strategic consulting services to investors, entrepreneurs, and others interested in the longevity industry and its complexities. To find out more: https://www.fightaging.org/services/

Contents

• If We Could Efficiently Address the Causes of Aging, No-One Would Care About Social and Behavioral Factors in Aging
• Lamin B1 in the Age-Related Loss of Neural Stem Cell Activity
• Reporting on a Study of One with Flagellin Immunization to Adjust the Gut Microbiome
• The Role of Reactive Oxygen Species in Aging is Complex
• A Discussion of Epigenetic Reprogramming and Rejuvenation
• Physical Exercise and the Resilience of the Brain to Aging
• Pharmacology to Target the Mechanisms of Aging is a Going Concern
• Transcriptional Differences in Non-Coding RNA Between Fit and Sedentary Elderly People
• What is Known of the Interaction of Cancer Stem Cells and Tumor Associated Macrophages
• The SREBP Pathway is a Mechanism by which Cancers Subvert Regulatory T Cells
• A Mechanism by Which Exercise Strengthens Bone and Immune Function
• Neurofilament Light Chain Levels in Blood Plasma as a Biomarker of Aging
• Targeting the Mitochondrial Permeability Transition Pore to Restore Mitochondrial Function in Aging
• Elastrin Develops a Means to Break Down Calcification of Tissues
• Combining Cell Reprogramming and Scaffold Materials for Muscle Regrowth

If We Could Efficiently Address the Causes of Aging, No-One Would Care About Social and Behavioral Factors in Aging
https://www.fightaging.org/archives/2021/03/if-we-could-efficiently-address-the-causes-of-aging-no-one-would-care-about-social-and-behavioral-factors-in-aging/

Aging is caused primarily by our biology, not by our choices. You can certainly cause yourself to age more rapidly by neglecting your health, but the only reason that we see any great level of concern regarding social and behavioral factors in aging is that rejuvenation therapies that have far larger beneficial results than exercise and diet are not yet in widespread use. So people can today look at effect sizes of a year gained here and a year lost there via lifestyle choices and think that this merits further investigation and funding, as it is on a par with what has been achieved via the poor past approaches to treating age-related disease.

In reality we should care very little about such small effects, and focus instead on medical research programs that can in principle add decades to healthy life spans by repairing the cell and tissue damage that causes aging. Bluntly, people who declare that breakthroughs in aging research must incorporate the study of social and behavioral factors are talking nonsense. It is the usual process of the social sciences fishing for funding in the wake of actually important work, combined with low expectations as to how much aging can be slowed or reversed in the decades ahead.

For breakthroughs in slowing aging, scientists must look beyond biolog

A trio of recent studies highlight the need to incorporate behavioral and social science alongside the study of biological mechanisms in order to slow aging. Exciting biological discoveries about rate of aging in non-human species are sometimes not applicable or lost when we apply them to humans. Including behavioral and social research can support translation of geroscience findings from animal models to benefit human. "The move from slowing fundamental processes of aging in laboratory animals to slowing aging in humans will not be as simple as prescribing a pill and watching it work. Compared to aging in laboratory animals, human aging has many behavioral/social in addition to cellular origins and influences. These influences include potential intervention targets that are uniquely human, and therefore are not easily investigated in animal research."

Several of these human factors have big impacts on health and mortality: stress and early life adversity, psychiatric history, personality traits, intelligence, loneliness and social connection, and purpose in life are connected to a variety of late-life health outcomes. These important factors need to be taken into account to get a meaningful prediction of human biological aging. "Geroscience can be augmented through collaboration with behavioral and social science to accomplish translation from animal models to humans, and improve the design of clinical trials of anti-aging therapies. It's vital that geroscience advances be delivered to everyone, not just the well-to-do, because individuals who experience low education, low incomes, adverse early-life experiences, and prejudice are the people who age fastest and die youngest."

"Social hallmarks of aging" can be strongly predictive of age-related health outcomes - in many cases, even more so than biological factors. While the aging field commonly discusses the biological hallmarks of aging, we don't tend to include the social and behavioral factors that lead to premature aging. Researchers have called the main five factors "the Social Hallmarks of aging" and poses that these should not be ignored in any sample of humans and the concepts should be incorporated where possible into non-human studies.

Researchers examined data that was collected in 2016 from the Health and Retirement Study, a large, nationally representative study of Americans over the age of 56 that incorporates both surveys regarding social factors and biological measurements, including a blood sample for genetic analysis. For the study, she focused the five social hallmarks for poor health outcomes: 1) low lifetime socioeconomic status, including lower levels of education, 2) adversity in childhood and adulthood, including trauma and other hardships, 3) being a member of a minority group, 4) adverse health behaviors, including smoking, obesity, and problem drinking, 5) adverse psychological states, such as depression, negative psychological outlook and chronic stress. The presence of these five factors were strongly associated with older adults having difficulty with activities of daily living, experiencing problems with cognition, and multimorbidity (having five or more diseases).

Lamin B1 in the Age-Related Loss of Neural Stem Cell Activity
https://www.fightaging.org/archives/2021/03/lamin-b1-in-the-age-related-loss-of-neural-stem-cell-activity/

Neurogenesis is the creation and integration of new neurons into neural circuits, necessary for learning, and for the maintenance of functional brain tissue. Neural stem cells are responsible for providing a supply of new neurons, but, as is the case for stem cells throughout the body, their activity declines with age. Loss of neurogenesis is one important contributing factor in the aging of the brain. Considered at the high level, a progressive loss of stem cell activity may be an evolved response to rising levels of cell and tissue damage and dysfunction, reducing the risk of death by cancer at the cost of a slow decline into death by loss of tissue function. At the low level, scientists are digging in to the specific mechanisms involved in age-related stem cell dysfunction. Today's research materials are an example of this sort of research program, focused on neural stem cells in this case.

All stem cells produce daughter somatic cells via replication in order to maintain the tissues that they support. Stem cells practice asymmetric cell division as one of several necessary strategies needed to maintain the pace of replication over a lifetime. They unload accumulated metabolic waste and damaged components onto each new daughter somatic cell in order to keep the level of damage in the stem cell low. Researchers here identified that lamin B1 is important in ensuring this asymmetry in neural stem cells, but levels decline with age. They used a gene therapy approach to increase lamin B1 expression, thereby improving neural stem cell function and the supply of new neurons in mice.

Reactivating Aging Stem Cells in the Brain

A new study shows how the formation of new neurons is impaired with advancing age. Protein structures in the nuclei of neural stem cells make sure that harmful proteins accumulating over time are unevenly distributed onto the two daughter cells during cell division. This seems to be an important part of the cells' ability to proliferate over a long time in order to maintain the supply of neurons. With advancing age, however, the amounts of nucleic proteins change, resulting in defective distribution of harmful proteins between the two daughter cells. This results in a decrease in the numbers of newly generated neurons in the brains of older mice.

The central element in this process is a nuclear protein called lamin B1, the levels of which decrease as people age. When the researchers increased lamin B1 levels in experiments in aging mice, stem cell division improved and the number of new neurons grew. The research is part of several ongoing projects aiming to reactivate aging stem cells. The ability to regenerate damaged tissue generally declines with age, thus affecting almost all types of stem cells in the body. These latest findings are an important step towards exploring age-dependent changes in the behavior of stem cells. "We now know that we can reactivate aging stem cells in the brain. Our hope is that these findings will one day help increase levels of neurogenesis, for example in older people or those suffering from degenerative diseases such as Alzheimer's. Even if this may still be many years in the future."

Declining lamin B1 expression mediates age-dependent decreases of hippocampal stem cell activity

Neural stem cells (NSCs) generate neurons throughout life in the hippocampal dentate gyrus. With advancing age, levels of neurogenesis sharply drop, which has been associated with a decline in hippocampal memory function. However, cell-intrinsic mechanisms mediating age-related changes in NSC activity remain largely unknown. Here, we show that the nuclear lamina protein lamin B1 (LB1) is downregulated with age in mouse hippocampal NSCs, whereas protein levels of SUN-domain containing protein 1 (SUN1), previously implicated in Hutchinson-Gilford progeria syndrome (HGPS), increase. Balancing the levels of LB1 and SUN1 in aged NSCs restores the strength of the endoplasmic reticulum diffusion barrier that is associated with segregation of aging factors in proliferating NSCs. Virus-based restoration of LB1 expression in aged NSCs enhances stem cell activity in vitro and increases progenitor cell proliferation and neurogenesis in vivo. Thus, we here identify a mechanism that mediates age-related decline of neurogenesis in the mammalian hippocampus.

Reporting on a Study of One with Flagellin Immunization to Adjust the Gut Microbiome
https://www.fightaging.org/archives/2021/03/reporting-on-a-study-of-one-with-flagellin-immunization-to-adjust-the-gut-microbiome/

This post is a report on a self-experiment with flagellin immunization, tested as an approach to adjust the gut microbiome in a favorable direction. Flagellin is the protein that makes up bacterial flagellae, and it is hypothesized that there is a sizable overlap between populations of gut microbes that possess flagellae and populations of gut microbes that are harmful rather than helpful. The harmful microbes are largely a problem because they contribute to chronic inflammation, while helpful microbes are largely beneficial due to the metabolites that they produce. The gut microbiome changes with age, shifting towards more harmful and fewer helpful microbes.

If the immune system can be roused to do a better job of eliminating the problem microbes, then perhaps this could lead to improved health. Flagellin immunization has been trialed in humans as a vaccine adjuvant, and shown to be safe in the small studies conducted to date. Recently, researchers tested its ability to adjust the gut microbiome in mice, with favorable results. Last year I posted a study outline for a self-experiment in flagellin immunization, and this year I have a report from one adventurous self-experimenter.

Setting Expectations

The motivation for this self-experiment was curiosity: would human data be similar to the mouse data? The results here were on balance positive. This is a self-experiment in which there is an unusually clear readout for the outcome of interest, in the form of the Viome gut microbiome assay. This is nonetheless a study population of one. The results should be taken as interesting, but not supportive of any particular conclusion beyond the desire to run a larger and more formal study.

Schedule for the Self-Experiment

The self-experiment ran for ten weeks. Weekly intramuscular injections of 10 μg flagellin in 0.5ml phosphate-buffered saline were used, with Viome gut microbiome assays performed beforehand, at 10 weeks, and six months later.

• Day 0: Perform a Viome gut microbiome assessment.
• Day 1: Intramuscular injection of 10 μg of flagellin.
• Day 8: Intramuscular injection of 10 μg of flagellin.
• Day 15: Intramuscular injection of 10 μg of flagellin.
• Day 22: Intramuscular injection of 10 μg of flagellin.
• Day 29: Intramuscular injection of 10 μg of flagellin.
• Day 36: Intramuscular injection of 10 μg of flagellin.
• Day 43: Intramuscular injection of 10 μg of flagellin.
• Day 50: Intramuscular injection of 10 μg of flagellin.
• Day 57: Intramuscular injection of 10 μg of flagellin.
• Day 64: Intramuscular injection of 10 μg of flagellin.
• Day 65: Perform a Viome gut microbiome assessment.
• Day 225: Perform a Viome gut microbiome assessment.

Subject Details

The subject for the self-experiment was in the 45-50 age range, healthy and without chronic conditions, with a BMI of ~22 throughout the duration of the experiment. Diet and exercise were described as "relatively consistent" across this time, including the six month follow up assessment. I feel that one should always be relatively skeptical of that sort of claim, however, no matter how formal or informal the study.

Summary of Results

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

Over the course of the self-experiment, Viome summary scores improved for Inflammatory Activity, Digestive Efficiency, Gut Lining Health, Protein Fermentation, and Gas Production. The summary scores declined for Metabolic Fitness and Active Microbial Diversity. The gains (largely bad scores transforming into good scores) were larger than the declines (bad scores becoming worse scores).

Viome Data

Gut Microbiome Health (overall score):
   Before: 27
   After: 43
   +6 months: 49

Inflammatory Activity (lower is better):
   Before: 50
   After: 45
   +6 months: 28
Metabolic Fitness (higher is better):
   Before: 25
   After: 29
   +6 months: 21
Digestive Efficency (higher is better):
   Before: 0
   After: 57
   +6 months: 68
Gut Lining Health (higher is better):
   Before: 12
   After: 64
   +6 months: 69
Protein Fermentation (lower is better):
   Before: 87
   After: 49
   +6 months: 33
Gas Production (lower is better):
   Before: 83
   After: 48
   +6 months: 35
Active Microbial Diversity (higher is better):
   Before: 34
   After: 15
   +6 months: 15

Ammonia Production Pathways
   Before: Not Optimal
   After: Average
   +6 months: Good
Bile Acid Metabolism Pathways
   Before: Average
   After: Good
   +6 months: Good
Biofilm, Chemotaxis, and Virulence Pathways
   Before: Not Optimal
   After: Not Optimal
   +6 months: Good
Butyrate Production Pathways
   Before: Average
   After: Average
   +6 months: Not Optimal
Flagellar Assembly Pathways
   Before: Not Optimal
   After: Not Optimal
   +6 months: Average
LPS Biosynthesis Pathways
   Before: Average
   After: Average
   +6 months: Average
Methane Gas Production Pathways
   Before: Good
   After: Not Optimal
   +6 months: Good
Oxylate Metabolism Pathways
   Before: Average
   After: Not Optimal
   +6 months: Not Optimal
Putrescine Production Pathways
   Before: Not Optimal
   After: Not Optimal
   +6 months: Average
Salt Stress Pathways
   Before: Average
   After: Average
   +6 months: Average
Sulfide Gas Production Pathways
   Before: Not Optimal
   After: Average
   +6 months: Average
TMA Production Pathways
   Before: Good
   After: Good
   +6 months: Good
Uric Acid Production Pathways
   Before: Not Optimal
   After: Not Optimal
   +6 months: Not Optimal

Anecdotal Notes

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

Conclusion

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

The Role of Reactive Oxygen Species in Aging is Complex
https://www.fightaging.org/archives/2021/03/the-role-of-reactive-oxygen-species-in-aging-is-complex/

Every compound and aspect of biology has a dose-response relationship of some sort. Wildly different outcomes should be expected at different levels of a drug, different degrees of expression of a protein, differing activity of a signaling pathway. What is a beneficial therapy at one dose is a toxin at another. A great many toxic substances and ostensibly harmful processes that damage the mechanisms of a cell are in fact beneficial at low doses, thanks to the hormetic response. A cell senses damage and engages a greater activity of its repair and maintenance processes, such as autophagy. The result is a net gain in cell maintenance. A mild stress, repeated infrequently, can improve cell function, tissue function, and, as a consequence, overall health and life span.

This underlies much of the observed complexity of the interaction between oxidative molecules and aging. In old age, there is an excess of oxidative molecules, reactive oxygen species, as a result of mitochondrial dysfunction, chronic inflammation, and other issues that provoke a greater generation of oxidative stress. This is harmful, it is past the point at which any benefit occurs. Interventions that greatly increase oxidative stress in animal models shorten life span. But there are many examples of genetic alterations in short-lived species in which a mild increase in the output of reactive oxygen species by mitochondria results in a gain in life span. Similarly, many of the metabolic improvements of exercise are provoked by raised mitochondrial generation of reactive oxygen species, as they work harder to provide energy to muscles.

For cells, an increase in reactive oxygen species is both a signal to undertake beneficial activities, and a harm that must be defended against by antioxidants and repair of damaged molecules. The two are tied together. The outcome depends on the dose, a dose that rises steadily with age as damage and dysfunction overtakes the biological systems of the body.

Beneficial and Detrimental Effects of Reactive Oxygen Species on Lifespan: A Comprehensive Review of Comparative and Experimental Studies

Aging is the greatest risk factor for a multitude of diseases including cardiovascular disease, neurodegeneration, and cancer. Despite decades of research dedicated to understanding aging, the mechanisms underlying the aging process remain incompletely understood. The widely-accepted free radical theory of aging (FRTA) proposes that the accumulation of oxidative damage caused by reactive oxygen species (ROS) is one of the primary causes of aging.

To define the relationship between ROS and aging, there have been two main approaches: comparative studies that measure outcomes related to ROS across species with different lifespans, and experimental studies that modulate ROS levels within a single species using either a genetic or pharmacologic approach. Comparative studies have shown that levels of ROS and oxidative damage are inversely correlated with lifespan. While these studies in general support the FRTA, this type of experiment can only demonstrate correlation, not causation.

Experimental studies involving the manipulation of ROS levels in model organisms have generally shown that interventions that increase ROS tend to decrease lifespan, while interventions that decrease ROS tend to increase lifespan. However, there are also multiple examples in which the opposite is observed: increasing ROS levels results in extended longevity, and decreasing ROS levels results in shortened lifespan. While these studies contradict the predictions of the FRTA, these experiments have been performed in a very limited number of species, all of which have a relatively short lifespan.

Overall, the data suggest that the relationship between ROS and lifespan is complex, and that ROS can have both beneficial or detrimental effects on longevity depending on the species and conditions. Accordingly, the relationship between ROS and aging is difficult to generalize across the tree of life.

A Discussion of Epigenetic Reprogramming and Rejuvenation
https://www.fightaging.org/archives/2021/03/a-discussion-of-epigenetic-reprogramming-and-rejuvenation/

Cell reprogramming can be achieved by gene therapies that express pluripotency genes - some or all of the Yamanaka factors. It is akin to the process that takes place in the early stages of embryonic development, and which removes the mitochondrial dysfunction and epigenetic alterations found in old tissues. Although germline cells are already very well protected, this extra step is necessary in order for children to be born physiologically young.

Cell reprogramming has largely been used to produce induced pluripotent stem cells, an important tool in the field of regenerative medicine and tissue engineering. In recent years, however, researchers have started to deploy cell reprogramming gene therapies in animal studies, finding the potential to achieve reversal of at least some markers of aging. Mitochondrial function and epigenetic regulation of gene expression are the targets of greatest interest, and this is giving new energy to the minority faction in the research community who think of aging as an evolved epigenetic program.

To my eyes, epigenetic change looks like a downstream outcome of deeper processes of aging, such as repeated cycles of DNA damage and repair, perhaps. Raised blood pressure is also a downstream consequence, but reduced mortality in older people can be achieved via forced control of blood pressure, implemented without addressing the underlying causes. Will reversal of epigenetic change prove to be a better version of blood pressure control, so to speak? A greater possible gain for health, while still leaving the underlying causes of aging to produce other harms? That remains to be seen.

There are clearly issues that cannot be solved by success in the application of reprogramming to reverse age-related epigenetic alterations. Many forms of harmful metabolic waste (persistent cross-links, lipofuscin components, and the like) cannot be broken down effectively even in youthful cells and tissues. Nuclear DNA damage and somatic mosaicism cannot be erased by rejuvenating cells. Cancerous and senescent cells should be destroyed, not rejuvenated. And so forth.

Aging and rejuvenation - a modular epigenome model

Gerontology is perhaps the biological discipline that has given rise to the largest number and variety of theories even before the development of modern science. Most theories aimed not only at elucidating the mechanism of aging but also at providing effective interventions to slow aging down. In the late 1950s the focus of research attention moved to DNA as the likely driver of aging either by expressing a program of aging or by being the target of endogenous and external insults that accumulated damage on the molecule during the lifetime of an organism. Up to this stage, aging was considered as an essentially irreversible process. However, with the discovery of cell reprogramming, early in this century, a view began to emerge that considers aging as a reversible epigenetic process.

The hypothesis proposing the epigenome as the driver of aging was significantly strengthened by the converging discovery that DNA methylation at specific CpG sites could be used as a highly accurate biomarker of age defined by the Horvath clock. The strong correlation between the dynamics of DNA methylation profiles and the rate of biological aging leads to the idea that the epigenetic clock may in fact be the pacemaker of aging or at least a component of it. And it is at this point where epigenetic rejuvenation comes into play as a strategy to reveal to what extent biological age can be set back by making the clock tick backwards.

The few initial results already documented seem to suggest that when the clock is forced to tick backwards in vivo, it is only able to drag the phenotype to a partially rejuvenated condition. Nevertheless, it would be premature to draw firm conclusions from the scanty experimental results so far documented. What seems to be clear is that epigenetic rejuvenation by cyclic partial reprogramming or alternative non-reprogramming strategies holds the key to both understanding the mechanism by which the epigenome drives the aging process and arresting or even reversing organismal aging.

Physical Exercise and the Resilience of the Brain to Aging
https://www.fightaging.org/archives/2021/03/physical-exercise-and-the-resilience-of-the-brain-to-aging/

Being active and fit slows the impact of aging on the brain. A diverse set of mechanisms are involved, and, as is often the case in these matters, it is far from clear as to which of these mechanisms are the most important. Fitness helps to maintain the vascular system in a better shape, keep levels of chronic inflammation lower, causes mild stress that makes cells throughout the body undertake greater maintenance activities, ensures that the gut microbiome ages more slowly, better maintaining the production of metabolites that affect neurogenesis. And so forth - the list goes on.

Nowadays, we are constantly bombarded by media, physicians, and other health professionals to engage in physical/sports activities to reduce physical/psychological stress, improve our health, and reduce the risk of chronic disease. The literature has clearly demonstrated aerobic fitness as one of the best indicators of resilience. This is supported by evidence from a number of studies showing that physical fitness confers physiological and psychological benefits and protects against the development of stress-related disorders, as well as improves cognition and motor function that are a consequence of aging and of neurological disorders.

Although we have learned about neurobiological mechanisms of physical fitness from the neuroplasticity and neuroprotection that confer resilience, these effects and mechanisms are diverse and complex and need to be further explored. However, we can summarize that exercise modulates several mechanisms that may increase brain health and counteract brain disorders. Exercise positively influences neuronal reserve by increasing BDNF expression which promotes neurogenesis and synaptic plasticity, reduces oxidative stress and inflammation, and enhances cerebral and peripheral blood flow, which stimulates angiogenic factors that lead to positive changes in the structure and morphology of brain vasculature. All these changes shape brain activity and serve as a buffer against stress-related disorders.

While several models of physical activity or exercise may impact positively on brain resilience such yoga, dance, martial arts, etc., in this review we aimed to focus mainly on the effects of aerobic exercise of low and moderate intensity or resistance exercise. Thus, physiological markers including heart rate variability, blood pressure, and cortisol might be regularly used as indicator of stress to determine the impact of exercise on brain resilience. Some examples of stress systems are the immune-inflammatory system, the hypothalamic-pituitary-adrenal (HPA) axis and the autonomic nervous system. Disturbance of these systems could lead to hyperactivity of the HPA-axis, sympathetic activation, and systemic inflammation.

However, there are still unanswered questions concerning (1) whether physical exercise in early life can prevent or delay cognitive decline in later life, (2) the effectiveness of exercise programs for individuals across the life span and for those with neurological diseases, and (3) how much exercise is necessary to gain beneficial effects on cognitive health. This is a field of research that deserves more attention.

Pharmacology to Target the Mechanisms of Aging is a Going Concern
https://www.fightaging.org/archives/2021/03/pharmacology-to-target-the-mechanisms-of-aging-is-a-going-concern/

Traditional pharmacological drug development involves (a) identifying a protein or protein interaction of interest in the body, (b) screening the small molecule libraries for a compound that affects that target, and then (c) making a better version of that small molecule: more effective, less harmful. That remains the bulk of the medical research and development industry, despite the proliferation of other approaches, including cell therapies, gene therapies, recombinant proteins, monoclonal antibodies, and so forth. There are goals that cannot be achieved by small molecules, and, as techniques improve and costs fall, gene therapies of various sorts will ultimately replace a great many small molecule therapies.

That is yet to come, however, and thus much of the first wave of the longevity industry is focused on turning out small molecule drugs that can in some way influence mechanisms of aging. This can be very promising, as in the case of senolytic drugs that cause senescent cells to self-destruct, or it can be likely of only modest benefit, as in the case of mTOR inhibitors that provoke cells into greater stress response activity. All too much of the work taking place today is of the latter category, and will probably provide, at best, similar gains in long term health and life span to those that can be achieved by exercise or the practice of calorie restriction. If we want to truly change the shape of a human life, more than this is needed.

The number of compounds that have been shown to increase longevity in preclinical models is growing exponentially: it was approximately 300 in 2005, 1300 in 2015, and most recently to 2000 in 2020. Meanwhile, the discovery of longevity-associated genes has plateaued, following an exponential growth until approximately 2010 before transitioning to a slower growth over the last decade. There are probably many more longevity genes left, but the incentives for their discovery are reduced since most newly discovered genes now tend to eventually lead towards already known pathways.

The number of longevity companies has also doubtlessly increased dramatically, although this is harder to subjectively measure, as it is difficult to define what makes a company longevity-focused. Most of these companies deal with the hallmarks of aging, most notably oxidative stress and mitochondrial dysfunction, cellular senescence, and pathways implicated in caloric restriction, such as mTOR. The acquisition of longevity companies by big pharma, for example the purchase of Alkahest by Grifols, is also just beginning to occur. One concern is the lack of strategic diversity. It is possible that too much weight is being put on these areas despite the much broader range of potential strategies.

Recently, the field has also seen its first clinical failures, a notable rite of passage for all new fields of medicine. In 2019, ResTORbio's mTOR inhibitor RTB101 failed its Phase 3 trial for a lung disease, and Unity Biotechnology's senolytic UBX0101 failed to meet its endpoints in osteoarthritis just last year. A myriad of challenges can complicate translation, such as a lack of genetic diversity in preclinical models, pathways that are not conserved between species, and the selection of proper primary endpoints. However, the list of ongoing clinical trials is constantly growing, with active studies including COVID-19, macular degeneration, frailty, and neurodegenerative diseases. The TAME trial of metformin represents a pivotal proof-of-concept study, which may pave the way for future therapies aiming to broadly target longevity in their applications to the FDA rather than any specific disease. Interest has also been growing in off-label prescriptions and nutritional supplements.

There has also been a ramping up of computer-based methods being applied to the field of longevity. Bioinformatics, machine learning, and artificial intelligence, -omics approaches, and large public databases are just beginning to be fully utilized. These techniques may someday improve our abilities to predict the outcomes of clinical trials. They also aim to identify candidate drugs and biomarker and may eventually play a role in the application of personalized, precision medicine. When taken as a whole, these trends characterize a vibrant, growing longevity industry in its early maturation stage. There are many parallels to the early days of some fields of pharmacology that are now well established, such as cancer and heart disease.

Transcriptional Differences in Non-Coding RNA Between Fit and Sedentary Elderly People
https://www.fightaging.org/archives/2021/03/transcriptional-differences-in-non-coding-rna-between-fit-and-sedentary-elderly-people/

Structured exercise programs cause sweeping beneficial changes in metabolism and the transcriptional landscape of cells in older individuals. Health improves, mortality is reduced, numerous measures of the aging of muscle tissue slowed. Researchers here look at one small slice of this bigger picture, the activity of non-coding RNAs in muscle tissue. These molecules are produced via transcription from genetic blueprints, but are not translated into functional proteins. Instead they largely appear to influence the process of translation of other RNA molecules into proteins. This class of RNA molecule is far from fully catalogued or understood, and there are likely functions yet to be discovered and catalogued.

In a previous study, the whole transcriptome of the vastus lateralis muscle from sedentary elderly and from age-matched athletes with an exceptional record of high-intensity, life-long exercise training was compared - the two groups representing the two extremes on a physical activity scale. Exercise training enabled the skeletal muscle to counteract age-related sarcopenia by inducing a wide range of adaptations, sustained by the expression of protein-coding genes involved in energy handling, proteostasis, cytoskeletal organization, inflammation control, and cellular senescence. Building on the previous study, we examined here the network of non-coding RNAs participating in the orchestration of gene expression and identified differentially expressed microRNAs and long-non-coding RNAs and some of their possible targets and roles.

Unsupervised hierarchical clustering analyses of all non-coding RNAs were able to discriminate between sedentary and trained individuals, regardless of the exercise typology. Validated targets of differentially expressed microRNA were grouped by KEGG analysis, which pointed to functional areas involved in cell cycle, cytoskeletal control, longevity, and many signaling pathways, including AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR), which had been shown to be pivotal in the modulation of the effects of high-intensity, life-long exercise training. The analysis of differentially expressed long-non-coding RNAs identified transcriptional networks, involving long-non-coding RNAs, microRNAs and messenger RNAs, affecting processes in line with the beneficial role of exercise training.

What is Known of the Interaction of Cancer Stem Cells and Tumor Associated Macrophages
https://www.fightaging.org/archives/2021/03/what-is-known-of-the-interaction-of-cancer-stem-cells-and-tumor-associated-macrophages/

Cancers subvert the immune system in order to survive, but also to accelerate their growth. Macrophages are a part of the innate immune system, and have roles in wound healing. They become engaged by a tumor; tumor-associated macrophages assist in the rampant growth of tumor cells by supporting them in an analogous way to the support of regrowth in injured tissues. A cancer is, in many ways, the twisted reflection of regeneration. In place of the intricate dance between macrophages, stem cells, and somatic cells, there is instead an equally complex interaction between tumor-associated macrophages, cancer stem cells, and cancer cells. Better understanding of these interactions might lead to ways to sabotage a cancer by picking apart the signaling, or finding ways in which tumor-associated macrophages or cancer stem cells could be selectively targeted for destruction.

Cancer stem cells (CSCs) constitute a cancer cell subpopulation similar to the other stem cell types in terms of self-renewal and multilineage differentiation potential but drive tumor development besides heterogeneity and dissemination of cancer cells. Targeting CSCs for therapeutic purposes is a goal of the scientific community. Currently, cancer treatments target the bulk population of the tumor cells without identifying and targeting CSCs. The significant problem in this regard is the lack of identification marker/s specific for CSCs.

Macrophages are large specialized phagocytic cells that exist in tissues or at infection sites. They arise from monocytes in the bone marrow and perform different functions and roles in the microenvironments of normal and tumor tissue. Macrophages differentiate into classically activated subtypes: CD68 expressing M1 mainly involved in pro-inflammatory activities, and CD163 expressing M2, that promote anti-inflammatory processes. In tumors, tumor-associated macrophages (TAM) comprise up to 50% of the tumor mass, with M2 phenotype being most abundant in the TME. The primary signals provided by TAMs include interleukin 4 (IL-4) and transforming growth factor-beta (TGF-β). TAMs play a key role in tumor initiation, development, and cancer cell propagation.

TAMs promote tumor growth by inducing neoangiogenesis, supporting CSCs, and downregulating tumour-targeting immune cells' number and function. Due to the significance of the tasks in which TAMs are involved, TAMs are increasingly becoming principal targets of novel therapeutic approaches, especially in the field of nanomedicine. The roles, connections, and functions of the crosstalk between TAMs and CSCs have been studied in-depth during the recent past. The interactions may be direct or indirect, and the effects on CSCs include chemoresistance, preservation, and the capacity to differentiate. TAMs produce cytokines including milk fat globule epidermal growth factor 8 (MFG-E8); interleukin 6 (IL-6), which can activate STAT3; and the Hedgehog signaling pathway, which seems to be one of the causes of drug resistance. For example, in hepatocarcinoma, IL-6 promotes the expression of CD44, inducing tumor development.

In-depth understanding of interaction between TAMs and CSCs is needed to develop novel treatment strategies in future. In this direction, researchers have already reported the presence of CSCs in many solid tumors as the leading cause of cancer relapse and chemotherapeutic drug resistance. In addition to this subpopulation of cells, macrophages and other immune cells also participate in interactions that may aid or impede the fight against cancer. For this reason, the targeting TAMs offer a novel treatment option against cancer. We believe that targeting TAMs may trigger various stromal reactions in the tumor milieu that are difficult to predict, even if the variability from patient to patient is kept as a consideration. Targeting TAMs could not only inhibit the tumor microenvironment, but also renovate the tumor "soil" to build a tumor-suppressive microenvironment, thereby suppressing tumor development. This strategy may become an effective therapeutic intervention that may be used either alone or in combination with other therapeutic strategies to treat cancer.

The SREBP Pathway is a Mechanism by which Cancers Subvert Regulatory T Cells
https://www.fightaging.org/archives/2021/03/the-srebp-pathway-is-a-mechanism-by-which-cancers-subvert-regulatory-t-cells/

Cancers subvert the immune system in a variety of ways, such as in order to aid growth, or suppress the immune response normally triggered by the presence of cancerous cells. Regulatory T cells are involved in halting the immune response after it is has done its job, and in preventing autoimmunity, in which the immune system attacks the body. This role is abused in cancerous tissue in order to protect the cancer from the immune system. Researchers here identify some of the controlling biochemistry that makes regulatory T cells behave differently in this scenario. The mechanism appears distinct enough, operating only in cancerous tissue, to be a good basis for the development of therapies that could in principle strip much of this protection from a cancer.

Immunologists have discovered that tumors use a unique mechanism to switch on regulatory T cells to protect themselves from attack by the immune system. Surprisingly, the mechanism does not affect regulatory T cell function outside the tumor and may therefore limit the immune-associated toxicities of targeting regulatory T cells. The finding offers the promise of drug treatment to selectively shut down regulatory T cells in a tumor, rendering the tumor vulnerable to cancer immunotherapies that activate the immune system to kill the tumor. The researchers showed that blocking tumor-associated regulatory T cell activity eliminated tumors cells in mice and sensitized the cells to cancer immunotherapy called anti-PD-1 therapy.

Researchers discovered the pathway by challenging mice with melanoma cells and then analyzing which genes were switched on in regulatory T cells. Investigators compared tumor-infiltrating regulatory T cells with regulatory T cells in other tissues to compare gene activation. The experiment revealed a master genetic switch that was activated only in regulatory T cells in the tumor microenvironment. The switch was a transcription factor family called SREBP.

The researchers determined that the tumor-specific regulatory T cell pathway was switched on in a range of cancers - melanoma, breast cancer, and head and neck cancer. The tumor-specific pathway was not switched on in animal models of inflammation or autoimmune disease. Genetically blocking the SREBP pathway selectively in regulatory T cells led to rapid clearance of tumor cells in mice with melanoma and colon adenocarcinoma. Targeting the pathway also reduced tumor growth in mice with established tumors. Blocking the pathway had no effect on the proliferation of regulatory T cells or their overall function in the body.

A Mechanism by Which Exercise Strengthens Bone and Immune Function
https://www.fightaging.org/archives/2021/03/a-mechanism-by-which-exercise-strengthens-bone-and-immune-function/

Regular exercise is very beneficial for long-term health, generating sweeping changes in metabolism and improving tissue and organ function across the board. Research suggests that present recommendations for the optimal amount of exercise are probably half or less of what they should be. Given that most people do not reach those recommendations, and all too many are entirely sedentary, there is certainly room for improvement. Studies show that structured exercise programs reverse a surprisingly large degree of age-related loss of function and mortality, a fraction of the declines of old age that is entirely self-inflicted. An era of low-cost comfort, telecommunication, and omnipresent engines of transport has allowed us to self-sabotage ourselves into losing years of health and life span.

Researchers have discovered that forces created from walking or running are transmitted from bone surfaces along arteriolar blood vessels into the marrow inside bones. Bone-forming cells that line the outside of the arterioles sense these forces and are induced to proliferate. This not only allows the formation of new bone cells, which helps to thicken bones, but the bone-forming cells also secrete a growth factor that increases the frequency of cells that form lymphocytes around the arterioles. Lymphocytes are the B cells and T cells that allow the immune system to fight infections. When the ability of the bone-forming cells to sense pressure caused by movement was blocked, it reduced the formation of new bone cells and lymphocytes, causing bones to become thinner and reducing the ability of mice to clear a bacterial infection.

The skeletal stem cells that give rise to most of the new bone cells that form during adulthood in the bone marrow. They are Leptin Receptor+ (LepR+) cells. They line the outside of blood vessels in the bone marrow and form critical growth factors for the maintenance of blood-forming cells. Researchers also found that a subset of LepR+ cells synthesize a previously undiscovered bone-forming growth factor called Osteolectin. Osteolectin promotes the maintenance of the adult skeleton by causing LepR+ to form new bone cells.

In the current study, researchers looked more carefully at the subset of LepR+ cells that make Osteolectin. They discovered that these cells reside exclusively around arteriolar blood vessels in the bone marrow and that they maintain nearby lymphoid progenitors by synthesizing stem cell factor (SCF) - a growth factor on which those cells depend. Deleting SCF from Osteolectin-positive cells depleted lymphoid progenitors and undermined the ability of mice to mount an immune response to bacterial infection. "The findings in this study show Osteolectin-positive cells create a specialized niche for bone-forming and lymphoid progenitors around the arterioles. Therapeutic interventions that expand the number of Osteolectin-positive cells could increase bone formation and immune responses, particularly in the elderly."

Neurofilament Light Chain Levels in Blood Plasma as a Biomarker of Aging
https://www.fightaging.org/archives/2021/03/neurofilament-light-chain-levels-in-blood-plasma-as-a-biomarker-of-aging/

The measurement of biological rather than chronological age is a goal for many research groups. Numerous approaches are under development, and the levels of a wide variety of compounds in the blood have been found to vary with advancing age. The example here, neurofilament light chain, is just one of many. A robust biomarker of biological age, measuring the burden of many different forms of cell and tissue damage, as well as their downstream consequences, will likely be a combination of numerous different measures.

Neurofilament light chain (NfL) is a structural protein found in nerve cells. The nervous system has been implicated in aging and longevity, so the fact that NfL can be detected in human bodily fluids makes it potentially useful as a biomarker for aging. NfL levels are known to increase with age and in response to neurodegenerative diseases, strengthening the case for its use as a biomarker.

To test the idea, an international team of scientists measured NfL levels in blood plasma from a cohort of people aged 21 to 107. They found a non-linear increase and greater variability with age. Plasma proteome data had already been generated from the same cohort, and NfL levels correlated with 53 of the proteins (out of roughly 1300). The proteins correlated with NfL levels are involved in apoptosis as well as synapse formation and plasticity, supporting the notion that plasma NfL levels reflect the activity of pathways associated with neuronal function.

The researchers then evaluated NfL as a predictor of mortality. They collected blood from separate cohorts of centenarians and nonagenarians, measured NfL levels, and tracked the cohorts over the next few years (or until death). They used activities of daily living (ADL) and Mini-Mental State Examination (MMSE) measures to assess the health of the participants. Overall, individuals with lower NfL levels lived longer than those with higher levels and did better on MMSE and ADL measures, though the difference was smaller for ADL. Finally, the team also showed that NfL levels increase with age in mice and that dietary restriction, which is known to extend the lifespan of mice, brings down NfL levels.

Targeting the Mitochondrial Permeability Transition Pore to Restore Mitochondrial Function in Aging
https://www.fightaging.org/archives/2021/03/targeting-the-mitochondrial-permeability-transition-pore-to-restore-mitochondrial-function-in-aging/

There is an increased interest in the mitochondrial permeability transition pore as a target for interventions that might improve mitochondrial function in aging. Mitochondria are the power plants of the cell, bacteria-like factories that package the chemical energy store molecule ATP via an energetic process of reactions. Mitochondria become dysfunction in aged tissues for reasons that include changes in their ability to divide and fuse together, and a faltering in the quality control mechanism of mitophagy. This loss of function is particularly important in the aging of energy-hungry tissues such as the muscles and brain.

The research community is at present largely focused on trying to reverse specific symptoms of mitochondrial dysfunction, such as lower NAD+ levels, or changes in gene expression related to mitochondrial dynamics, or changes in mitochondrial permeability transition pore behavior. It isn't clear as to how effective these options will turn out to be, whether they are targeted close enough to the root of the problem to make a meaningful difference. There are also efforts to replace mitochondria, or eliminate those that are dysfunctional, and copy mitochondrial genes to the cell nucleus as a backup source of necessary proteins for mitochondrial function. These will probably be better approaches, but these are still comparatively early days in which there is all too little data for efficacy.

A better understanding of the cellular and molecular mechanisms underlying aging is central to the successful development and clinical translation of novel therapies and prevention strategies. Recent work has demonstrated that changes in mitochondrial permeability transition pore (mPTP) function may contribute directly to cellular dysfunction with aging. These changes include increases in reactive oxygen species (ROS) production, induction of cellular senescence (particularly in aging stem cells), and activation of the inflammasome, the latter contributing directly to the chronic state of inflammation often referred to as "inflammaging". mPTP dysfunction has been cited as a key factor in neurodegenerative pathologies through its role in collapsing mitochondrial membrane potential, repressing mitochondrial respiratory function, releasing mitochondrial Ca2+ and cytochrome c, and enhancing ROS generation. Thus, the mPTP has received increased attention as a potential therapeutic target.

The relationship between the mPTP and the generation of mitochondrial reactive oxygen species (mROS) has attracted significant interest within the context of aging and age-related tissue degeneration. Recently, it was found that mROS can stimulate the opening of the mPTP, which can lead to further mROS production and release. This positive feedback mechanism ultimately leads to an excessive amount of ROS accumulation. ROS accumulation in turn damages nuclear DNA, activates pro-apoptotic signaling pathways, and drives cellular aging. On the other hand, ROS can in some cases activate protective pathways, decrease stress on the mitochondria, and increase lifespan. It is currently thought that the mPTP plays an important role in integrating the effects of mROS and hence may play a vital role in the aging process. In this review, we discuss the various mechanisms inducing activation of the mPTP and the age-associated cell damage seen as a byproduct of mPTP activation. Furthermore, we discuss potential therapies that target the mPTP and may therefore inhibit the effects of aging and injury.

Elastrin Develops a Means to Break Down Calcification of Tissues
https://www.fightaging.org/archives/2021/03/elastrin-develops-a-means-to-break-down-calcification-of-tissues/

Calcification of tissues is one of the mechanisms by which stiffening occurs in the cardiovascular system, leading to a range of increasingly serious downstream consequences. The evidence of recent years suggests that chronic inflammation and the harmful signaling of senescent cells are a major cause of cells in blood vessel walls inappropriately taking on osteoblast-like behavior, depositing calcium into the extracellular matrix as though they are building bone. Among the many other consequences, this process damages the elastin molecules in areas in which it occurs, and the approach taken by biotech startup Elastrin Therapeutics is to use that damage as a target in order to deliver nanoparticles that will remove the calcification. It is an interesting approach.

Elastrin, a biotechnology start-up leveraging a platform technology to develop therapeutics that render calcified tissue and organs supple again, will receive seed funding from Kizoo Technology Capital. It is the latest addition to the growing portfolio of Kizoo, a rejuvenation biotech investor focused on reversing age-related damage on a cellular and molecular level. Elastrin's lead asset is a nanoparticle conjugated with a novel monoclonal antibody to treat heart valve and vascular calcification. The platform targets and restores degraded elastin by removing the harmful calcification that stiffens arteries, improving the efficacy of drugs and eliminating side-effects by combining particle design with elastin targeting.

"Elastin fibers are critical for the homeostasis of tissues around the body, including the skin, vasculature, and pulmonary tissues. As elastin fibers become damaged over time, arterial walls weaken, and the body's physiological response results in aortic wall stiffening, aneurysms, and hypertension." The Elastrin team has developed a platform that can restore vascular health by removing pathological calcification, specifically from sites where elastin has been degraded. This is achieved via targeting albumin nanoparticles loaded with therapeutic agents directly to the tissue site of interest with the company's anti-elastin monoclonal antibody.

"Cardiovascular diseases are the number one cause of death globally, taking an estimated 18 million lives each year. On top of that, everyone above 30 years old is suffering from damage to the cardiovascular system, resulting in severe symptoms one day. Our technology can reverse damage to the arteries and heart and bring the body back to a state before the damage even occurred. This is a true game-changer in the industry and one of the puzzle pieces towards healthy aging. Nobody wants to live forever in an old and sick body, but we do want to live long in a healthy one."

Combining Cell Reprogramming and Scaffold Materials for Muscle Regrowth
https://www.fightaging.org/archives/2021/03/combining-cell-reprogramming-and-scaffold-materials-for-muscle-regrowth/

A well established field of research is focused on the development of implantable scaffold materials to encourage regeneration of lost tissue, such as in the case of severe muscle injuries. A wide variety of scaffold approaches incorporate signaling molecules and increasingly sophisticated small-scale structure, all intended to mimic aspects of the natural extracellular matrix, as well as other features. Use of a natural extracellular matrix is also an option, via decellularization of donor tissue. A great deal of innovation is taking place. As an example, researchers here combine a scaffolding approach with cell reprogramming to demonstrate muscle regrowth in an animal model.

In serious injuries such as those sustained in car accidents or tumor resection which results in a volumetric muscle loss (VML), the muscle's ability to recover is greatly diminished. A promising strategy to improve the functional capacity of the damaged muscle is to induce de novo regeneration of skeletal muscle via the integration of transplanted cells. Diverse types of cells, including satellite cells (muscle stem cells), myoblasts, and mesenchymal stem cells, have been used to treat muscle loss.

An important issue is controlling the three-dimensional microenvironment at the injury site to ensure that the transplanted cells properly differentiate into muscle tissues with desirable structures. A variety of natural and synthetic biomaterials have been used to enhance the survival and maturation of transplanted cells while recruiting host cells for muscle regeneration. However, there are unsolved, long-lasting dilemmas in tissue scaffold development. Natural scaffolds exhibit high cell recognition and cell binding affinity, but often fail to provide mechanical robustness in large lesions or load-bearing tissues that require long-term mechanical support. In contrast, synthetic scaffolds provide a precisely engineered alternative with tunable mechanical and physical properties, as well as tailored structures and biochemical compositions, but are often hampered by lack of cell recruitment and poor integration with host tissue.

To overcome these challenges, a research team has devised a novel protocol for artificial muscle regeneration. The team achieved effective treatment of VML in a mouse model by employing direct cell reprogramming technology in combination with a natural-synthetic hybrid scaffold. Direct cell reprogramming, also called direct conversion, is an efficient strategy that provides effective cell therapy because it allows the rapid generation of patient-specific target cells using autologous cells from the tissue biopsy. Fibroblasts are the cells that are commonly found within the connective tissues, and they are extensively involved in wound healing. As the fibroblasts are not terminally differentiated cells, it is possible to turn them into induced myogenic progenitor cells (iMPCs) using several different transcription factors. Herein, this strategy was applied to provide iMPC for muscle tissue engineering.

In order to provide structural support for the proliferating muscle cells, polycaprolactone (PCL), was chosen as a material for the fabrication of a porous scaffold due to its high biocompatibility. However, the synthetic PCL fiber scaffolds alone do not provide optimal biochemical and local mechanical cues that mimic muscle-specific microenvironment. Hence the construction of a hybrid scaffold was completed through the incorporation of decellularized muscle extracellular matrix (MEM) hydrogel into the PCL structure.

The resultant bioengineered muscle fiber constructs showed mechanical stiffness similar to that of muscle tissues and exhibited enhanced muscle differentiation and elongated muscle alignment in vitro. Furthermore, implantation of bioengineered muscle constructs in the VML mouse model not only promoted muscle regeneration with increased innervation and angiogenesis but also facilitated the functional recovery of damaged muscles.