Fight Aging! Newsletter, June 28th 2021

Today is a doubly important day: it marks the final day of the PEARL campaign and it is a celebration of another victory for the life extension community. PEARL smashed its initial fundraising goal and sailed through its two stretch goals, raising just under 183k thanks to the generous support of the community. The Participatory Evaluation (of) Aging (with) Rapamycin (for) Longevity Study, or PEARL, will launch the first large-scale placebo-controlled clinical trial to determine the effects of rapamycin on human aging. The principal investigator is Dr. James P. Watson based at UCLA.

The PEARL trial will follow up to 200 participants over 12 months testing four different rapamycin dosing regimens. It will be double-blind, randomized, placebo-controlled and registered with clinicaltrials.gov. The principal investigator is Dr. James P Watson at UCLA, who was also a principle investigator for the famous TRIIM trial. To ensure safety the participants' blood will be regularly monitored and side effects noted.

A battery of tests and measurements will be taken, both after 6 and 12 months. These will include autonomic health tests, blood tests, body composition tests, fecal microbiome testing, immune and inflammation health tests, methylation age clock testing, and skeletal muscle tests. With your help we will find out if and how well rapamycin works to combat human aging. And, armed with a positive result, we will finally be able to help slow down onset of age related damage for you and those who you love and care about.

Although partial reprogramming proved that senescent cells can be reverted, early termination of this reprogramming process is known to cause epigenetic dysregulation, resulting in dedifferentiated dysplastic cells such as renal cancer. Therefore, a novel therapeutic strategy without such critical limitations is highly needed. Cellular senescence is caused by complex interactions among biomolecules that govern cell cycle, DNA damage response, energy metabolism, and cytokine secretion. Recent studies showed that cellular senescence, previously considered as an irreversible biological phenomenon, can be reversed, but due to the nature of such complex interactions governing cellular senescence, the mechanism by which cellular senescence can be reversed has not been revealed.

Researchers reconstructed an ensemble of 5000 Boolean network models that can represent senescence, quiescence, and proliferation phenotypes by integrating information from the literature, network databases and phosphoprotein array data of dermal fibroblasts. In their models, cellular senescence is induced by simultaneous activation of DNA damage signal (doxorubicin) and growth signal (IGF-1 plus serum). They identified 3-phosphoinositide-dependent protein kinase 1 (PDK1) as the optimal protein target that can safely revert senescence to quiescence while avoiding uncontrolled proliferation, through extensive computer simulation analysis of the ensemble model. PDK1 forms a positive feedback structure along with AKT, IKBKB, and PTEN, that simultaneously control both nuclear factor κB, which controls cytokine secretion, and mTOR, which regulates cell growth.

In order to validate the simulation results, researchers conducted in vitro experiments and confirmed that when PDK1 was inhibited, various markers of cellular senescence are returned to normal and proliferation potential is restored. From wound healing assays and 3D reconstructed skin tissue experiments, they also reaffirmed that the reverted cells are able to respond appropriately to external stimuli. In particular, by observing dermal fibroblast within dermis along with keratinocyte within epidermis, 3D reconstructed skin tissue experiments verified that PDK1 inhibition promotes epidermal renewal and restores skin thickness, resulting in reversal of age-related skin degeneration.

The maximum human life expectancy has increased since the mid-1800s by ~3 months per year. These gains have resulted from shifting the majority of deaths from early to later and later ages, with no evidence of slowing the rate at which mortality increases with age (i.e. the 'rate of ageing'). Further substantial extensions of human longevity will depend on whether it is possible to slow the rate of ageing or otherwise reduce late life mortality. Consequently, the nature of biological constraints on ageing is a central problem in the health sciences and, because of its implications for demographic patterns, is also of long-standing interest in ecology and evolutionary biology.

Across species, rates of ageing are strongly correlated with other aspects of the life history-pre-adult mortality, age at first reproduction, birth rate, metabolic rate and generation time - as well as with morphological traits such as body size and growth rate. These correlations suggest that ageing evolves in concert with a suite of other traits, which may produce constraints on the rate of ageing within species. Indeed, researchers have long hypothesised that the rate of ageing is relatively fixed within species, not only in humans but also other animals.

This 'invariant rate of ageing' hypothesis has received mixed support. Understanding the nature and extent of biological constraints on the rate of ageing and other aspects of age-specific mortality patterns is critical for identifying possible targets of intervention to extend human lifespans, and for understanding the evolutionary forces that have shaped lifespans within and across species. Although no consensus has been reached about the invariant rate of ageing hypothesis, further evidence that biological constraints may shape human ageing comes from the remarkably consistent relationship between life expectancy at birth and lifespan equality in a diverse set of human populations. While life expectancy at birth (a measure of the 'pace' of mortality) describes the average lifespan in a population, lifespan equality (a measure of the 'shape' of mortality) describes the spread in the distribution of ages at death in a population.

To better understand biological constraints on ageing, here we answer two questions. First, is the highly regular linear relationship between life expectancy and lifespan equality in humans also evident in other primates? Second, if so, do biological constraints on ageing underlie this highly regular relationship? We first recapitulate, in nonhuman primates, the highly regular relationship between life expectancy and lifespan equality seen in humans. We next demonstrate that variation in the rate of ageing within genera is orders of magnitude smaller than variation in pre-adult and age-independent mortality. Finally, we demonstrate that changes in the rate of ageing, but not other mortality parameters, produce striking, species-atypical changes in mortality patterns. Our results support the invariant rate of ageing hypothesis, implying biological constraints on how much the human rate of ageing can be slowed.

Can we humans slow our own rate of ageing? Our findings support the idea that, in historical population when life expectancies were low, mortality improvements for infants, and in age-independent mortality, were the central contributors to the decades-long trend towards longer human life expectancies and greater lifespan equality. These improvements were largely the result of environmental influences including social, economic, and public health advances. Since the middle of the 20th century, however, declines in the baseline level of adult mortality have very likely played an increasingly important role in industrialised societies. As we show here, improvements in the environment are unlikely to translate into a substantial reduction in the rate of ageing, or in the dramatic increase in lifespan that would result from such a change. It remains to be seen if future advances in medicine can overcome the biological constraints that we have identified here, and achieve what evolution has not.

Clinical data on the possible benefits and risks of using dasatinib and quercetin (D+Q) as senolytics is extremely limited. Published results exist from 3 human trials, two in diseased populations and one in healthy subjects. A total of only 8 benefits were documented in these clinical studies. Of the 8 benefits, 5 were actually various measurements of markers of senescence or the SASP, hypothesized to translate to clinically beneficial effects. Only 3 benefits had any direct clinical relevance and they were of low magnitude. Based on the current state of evidence, the beneficial effects of D+Q seem to be extremely limited in humans.

Several more benefits that encompass many organ systems have been reported in preclinical studies. However, the amount of relevant preclinical research is also limited. We identified only 31 preclinical trials related to D+Q as senolytics and the majority of reported benefits occurred exclusively in diseased animals. Only 13 trials included a group of "healthy" animals that were treated with D+Q. Of those 13 trials, only 6 reported a positive effect of D+Q senolytic treatment on aged, otherwise healthy animals as compared to controls.

The main benefits seen in clinical and preclinical trials of D+Q senolytic therapy are: (a) decreased markers of senescent cells in various tissues (clinical and preclinical); (b) increased health span and lifespan (preclinical); (c) improved cognition and cortical blood flow (preclinical); (d) decreased amounts of liver fat (preclinical); (e) improved vasomotor/endothelial function (preclinical); (e) decreased intimal plaque calcification (preclinical). The main risks that have appeared in clinical trials are mostly due to dasatinib. In the two high quality, open-label human pilot senolytic trials there was only one serious adverse event reported (bacterial multifocal pneumonia and pulmonary edema superimposed on the idiopathic pulmonary fibrosis that was the subject of the trial) and no subjects required drug discontinuation.

The 3 clinical trials published to date have all used different protocols (doses, frequency, duration, and repetition). There is no consensus on the optimal treatment protocol. Unfortunately, as of today, there is no single test that is completely sensitive or specific for senescent cells. Generally, a combination of assays is needed to estimate the senescent cell burden in tissue samples. It is unknown if senescent cell abundance in biopsies of skin, adipose tissue, or other tissues, cheek swabs, cells in blood reliably reflect senescent cell abundance overall. Similarly, whether levels of SASP factors or senescence-associated microRNAs in plasma or blood cells reflect senescent cell burden is not clear.

Therefore, until there are more published results showing benefits in humans, a clearer picture of the senolytic-use specific risk profile, and a consensus on the treatment protocol, we will avoid the use of D+Q senolytic therapy.

Some inflammatory diseases, such as periodontitis, might represent a factor that can contribute to central nervous system (CNS) damage. Periodontitis is a multifactorial chronic inflammatory disease that affects the supporting tissues around the teeth, triggered by dysbiotic biofilms that can lead to systemic inflammation. Periodontal disease is one of the most frequent causes of tooth loss, and is highly prevalent in adults affecting about 20-50% of the global population. It can lead to a systemic inflammatory state through mechanisms that include the spread of pro-inflammatory cytokines and/or bacteria located in the oral cavity. Persistent systemic inflammation/infection can cause neuroinflammation in the brain. Considering this possible interaction, the present study aims to systematically review the evidence supporting the association between the presence of some neurodegenerative disease and periodontitis.

From 534 articles found in this systemic review, 12 were included, of which eight were case-control, three were cross-sectional, and one was a cohort, giving a total of 3,460 participants. All studies presented a low risk of bias and reported an association between neurodegenerative disease and periodontitis. The articles showed that the groups with the two concomitant diseases had higher inflammatory markers levels, IgG levels of periodontal bacteria, and/or clinical parameters of periodontitis compared with the isolated conditions. However, the heterogeneity of the studies taken together hindered the accuracy of the evidence and also made impossible the merging of data. Also, it should be highlighted that no cohort study was retrieved regarding the association between periodontal disease and neurodegenerative diseases; therefore, causality cannot be claimed.

Although all the included studies in this review reported an association between neurodegenerative diseases and periodontitis, the level of evidence was classified to be very low, which suggests a cautious interpretation of the results.

Cellular senescence has emerged as a significant and potentially tractable mechanism of aging and multiple aging-related conditions. Biomarkers of senescent cell burden, including molecular signals in circulating immune cells and the abundance of circulating senescence-related proteins, have been associated with chronological age and clinical parameters of biological age in humans. The extent to which senescence biomarkers are affected by interventions that enhance health and function has not yet been examined.

Here, we report that a 12-week structured exercise program drives significant improvements in several performance-based and self-reported measures of physical function in older adults. Impressively, the expression of key markers of the senescence program, including p16, p21, cGAS, and TNFα, were significantly lowered in CD3+ T cells in response to the intervention, as were the circulating concentrations of multiple senescence-related proteins. Moreover, partial least squares discriminant analysis showed levels of senescence-related proteins at baseline were predictive of changes in physical function in response to the exercise intervention.

Our study provides first-in-human evidence that biomarkers of senescent cell burden are significantly lowered by a structured exercise program and predictive of the adaptive response to exercise.

Aging is one of the major risk factors for degenerative joint disorders, including those involving the temporomandibular joint (TMJ). TMJ degeneration occurs primarily in the population over 65, significantly increasing the risk of joint discomfort, restricted joint mobility, and reduced quality of life. Unfortunately, there is currently no effective mechanism-based treatment available in the clinic to alleviate TMJ degeneration with aging.

We now demonstrate that intermittent administration of the senolytic combination of dasatinib and quercetin, which can selectively clear senescent cells, preserved mandibular condylar cartilage thickness, improved subchondral bone volume and turnover, and reduced Osteoarthritis Research Society International (OARSI) histopathological score in both 23- to 24-month-old male and female mice. Senolytics had little effect on 4 months old young mice, indicating age-specific benefits.

Our study provides proof-of-concept evidence that age-related TMJ degeneration can be alleviated by pharmaceutical intervention targeting cellular senescence. Since the senolytics used in this study have been proven relatively safe in recent human studies, our findings may help justify future clinical trials addressing TMJ degeneration in old age.

Recently, fasting has become one of the most compelling topics of the Nutrition Era. In the last five years, interest has passed from the Mediterranean to the Ketogenic Era, including the concept of caloric restriction and 'only water' fasting. Recently, research in animal models and humans has highlighted the potential health-promoting physiological responses to fasting including ketogenesis, hormone modulation, reduced oxidative stress and inflammation, and increased stress resistance, lipolysis, and autophagy. Although the panorama of evidence on fasting and caloric restriction is wide, there is a lack of a correct and safe fasting protocol to guide nutritionists and physicians in its application.

The act of fasting gained an increased focus in the scientific panorama thanks to several pieces of research developed around 30 years ago. The first studies referred to minor organisms and not directly to humans, because fasting and caloric restriction were considered tough interventions, combined with health risks if not adequately structured. Initially, studies on yeasts and murine models brought remarkably interesting results, later to be replicated in humans.

Some people, to be committed to their health, try adopting new habits as nutritional styles change. Nowadays, people are motivated by information from various sources: media, social networks, doctors, gyms, health coaches, and, simply, word of mouth and rumor. The accumulated information is not in line with scientific discoveries and safety protocols. Mere abstinence from food cannot result in efficacy if it is not well contextualized within a structured nutritional intervention. Fasting improves blood biomarkers for metabolic health, stress resistance, and suppresses inflammation. For example, most Westerners emulate their idols, picking up a fasting model that is supposed to help with losing and sustaining weight, keeping mentally sharp, and promoting longevity. Most of the time they do not experience the suggested benefits because of an unbalanced diet.

In the light of the above, the goal of our paper is to examine the context in which fasting could be practiced, and the most important discoveries in fasting used in pathological conditions such as chronic degenerative diseases. Moreover, it aims to offer to clinical experts in nutrition a specific guide to be consulted and personalized for each patient.

The pituitary gland is a small, globular gland located underneath the brain that plays a major role in the hormonal system. Due to the central role played by the pituitary, its ageing may contribute to the reduction of hormonal processes and hormone levels in our body - as is the case with menopause, for instance. A new study provides significant insight into the stem cells in the ageing pituitary gland. In 2012, researchers showed that a prompt reaction of stem cells to injury in the gland leads to repair of the tissue, even in adult animals. "As a result of this new study, we now know that stem cells in the pituitary do not lose this regenerative capacity when the organism ages. In fact, the stem cells are only unable to do their job because, over time, the pituitary becomes an 'inflammatory environment' as a result of the chronic inflammation. But as soon as the stem cells are taken out of this environment, they show the same properties as stem cells from a young pituitary."

This insight opens up a number of potential therapeutic avenues: would it be possible to reactivate the pituitary? This wouldn't just involve slowing down hormonal ageing processes, but also repairing the damage caused by a tumour in the pituitary, for example. The study also suggests another interesting avenue: the use of anti-inflammatory drugs to slow down pituitary ageing or rejuvenate an ageing pituitary. "Several studies have shown that anti-inflammatory drugs may have a positive impact on some ageing organs. No research has yet been performed on this effect in relation to the pituitary."

"Mice have a much greater regeneration capacity than humans. They can repair damaged teeth, for instance, while humans have lost this ability over the course of their evolution. Regardless, there are plenty of signs suggesting that pituitary processes in mice and humans are similar, and we have recent evidence to hand that gene expression in the pituitaries of humans and mice is very similar. As such, it is highly likely that the insights we gained in mice will equally apply to humans."

Researchers have demonstrated that elderly monkeys had up to 59 percent fewer plaque deposits in their brains after treatment with CpG oligodeoxynucleotides (CpG ODN), compared with untreated animals. These amyloid beta plaques are protein fragments that clump together and clog the junctions between neurons. Brains of treated animals also had a drop in levels of toxic tau. This nerve fiber protein can destroy neighboring tissue when disease-related changes to its chemical structure cause it to catch on other cells.

The investigators say the treatment led to cognitive benefits as well. When presented with a series of puzzles, elderly monkeys given the drug performed similarly to young adult animals and much better than those in their age group that had remained untreated. The treated monkeys also learned new puzzle-solving skills faster than their untreated peers. According to researchers, past treatment efforts targeting the immune system failed because the drugs overstimulated the system, causing dangerous levels of inflammation, which can kill brain cells. "Our new treatment avoids the pitfalls of earlier attempts because it is delivered in cycles, giving the immune system a chance to rest between doses."

A growing body of evidence has implicated the immune system, the set of cells and proteins that defend the body from invading bacteria and viruses, as a contributor to Alzheimer's disease. A subset of immune cells, those within the innate immune system, swallow and clear away debris and toxins from bodily tissues along with invading microbes. Studies have shown that these immune custodians become sluggish as a person ages and fail to clear toxins that cause neurodegeneration.

The new investigation is the first to target the innate immune system with a potential therapy for the disorder in monkeys. The CpG ODN drugs are part of a class of innate immune regulators that quicken these worn out immune custodians. The research team is also the first to use the "pulsing" drug administration technique to avoid excess inflammation, the immune-driven responses like swelling and pain that result from the homing in by immune cells on sites of injury or infection. While necessary to immune defenses and healing, too much inflammation contributes to many disease mechanisms.

A clinical trial has shown for the first time that heart failure treatments using cells derived from the patient's own bone marrow and heart resulted in improved quality of life and reduced major adverse cardiac events for patients after one year. "This is a very important advance in the field of cell therapy and in the management of heart failure. It suggests that a treatment, given only once, can produce long-term beneficial effects on the quality of life and prognosis of these patients. The results pave the way for a larger, Phase 3 trial of cell therapy in heart failure."

CONCERT-HF evaluated the use of two types of cells - autologous mesenchymal stromal cells (MSCs) and c-kit positive cardiac cells (CPCs) - alone or in combination, in patients with heart failure caused by chronic ischemic cardiomyopathy, a decrease in heart pumping effectiveness due to heart attacks and a lack of blood getting to the heart. Autologous MSCs are derived from the patient's bone marrow and CPCs are from the patient's heart tissue. Both are known as "autologous" cells because they come from the same patient in whom they are returned for the treatment.

In the study, patients treated with CPC cells alone had a significant 22% reduction in major adverse cardiac events, particularly hospitalization. Patients treated with MSC cells alone and with a combination of both types of cells experienced significantly improved quality of life compared with patients who received no treatment. Left ventricular ejection fraction, left ventricular volumes, scar size, 6-min walking distance, and peak oxygen consumption did not differ significantly among groups.

All living organisms use the same 20 amino acids for protein synthesis. Interestingly, the protein compositional content of the sulfur amino acids methionine and cysteine is species-specific and is associated with animal longevity. Thus, long-lived animal species show the lower methionine and cysteine protein content, surely as adaptive response to the low rate of endogenous damage and highly resistant macromolecular components also present in longevous species. Reinforcing these observations, the free tissue methionine content is also lower in diverse long-lived animal species; and the pro-longevity effects of nutritional (methionine restriction, MetR) and pharmacological (metformin) interventions are mediated by changes in methionine metabolism.

In addition to its role in several intracellular processes, methionine is the core of a complex metabolic network which can be divided in three parts: methionine cycle, the transsulfuration pathway, and polyamine biosynthesis. Significantly, manipulation of each of these branches affects longevity in diverse experimental animal models. Consequently, available findings point to the metabolism of methionine as a key target to study the molecular adaptive mechanisms underlying differences in animal longevity.

The present study follows a comparative approach to analyse the plasma methionine metabolic profile from 11 mammalian species with a longevity ranging from 3.5 to 120 years. Our findings demonstrate the existence of a species-specific plasma profile for methionine metabolism associated with longevity characterised by: i) reduced methionine, cystathionine and choline; ii) increased non-polar amino acids; iii) reduced succinate and malate; and iv) increased carnitine. Our results support the existence of plasma longevity features that might respond to an optimised energetic metabolism and intracellular structures found in long-lived species.

Cellular senescence is linked to chronic age-related diseases including atherosclerosis, diabetes, and neurodegeneration. Compared to proliferating cells, senescent cells express distinct subsets of proteins. In this study, we used cultured human diploid fibroblasts rendered senescent through replicative exhaustion or ionizing radiation to identify proteins differentially expressed during senescence. We identified acid ceramidase (ASAH1), a lysosomal enzyme that cleaves ceramide into sphingosine and fatty acid, as being highly elevated in senescent cells. This increase in ASAH1 levels in senescent cells was associated with a rise in the levels of ASAH1 mRNA and a robust increase in ASAH1 protein stability.

Furthermore, silencing ASAH1 in pre-senescent fibroblasts decreased the levels of senescence proteins p16, p21, and p53, and reduced the activity of the senescence-associated β-galactosidase. Interestingly, depletion of ASAH1 in pre-senescent cells sensitized these cells to the senolytics dasatinib and quercetin (D+Q).

Together, our study indicates that ASAH1 promotes senescence, protects senescent cells, and confers resistance against senolytic drugs. Given that inhibiting ASAH1 sensitizes cells towards senolysis, this enzyme represents an attractive therapeutic target in interventions aimed at eliminating senescent cells.

Increased oxidative stress, leukocyte telomere length (LTL) shortening, endothelial dysfunction, and lower insulin-like growth factor (IGF)-1 concentrations reflect key molecular mechanisms of aging. We hypothesized that biomarkers representing these pathways are associated with measures of subclinical atherosclerosis and all-cause mortality.

We evaluated 2,314 Framingham Offspring Study participants (mean age 61 years, 55% women) with available biomarkers of aging: LTL, circulating concentrations of IGF-1, asymmetrical dimethylarginine (ADMA), and urinary F2-Isoprostanes indexed to urinary creatinine. We evaluated the association of each biomarker with coronary artery calcium (CAC) and carotid intima-media thickness (IMT).

In multivariable-adjusted linear regression models, higher ADMA levels were associated with higher CAC values. Additionally, shorter LTL and lower IGF-1 values were associated with higher IMT values. During a median follow-up of 15.5 years, 593 subjects died. In multivariable-adjusted Cox regression models, LTL and IGF-1 values were inversely associated with all-cause mortality. F2-Isoprostanes and ADMA values were positively associated with all-cause mortality.

In conclusion, in our prospective community-based study, aging-related biomarkers were associated with measures of subclinical atherosclerosis cross-sectionally and with all-cause mortality prospectively, supporting the concept that these biomarkers may reflect the aging process in community-dwelling adults.

The skin is our largest organ. Its aging reflects both intrinsic (or chronological) and extrinsic (such as radiation and pollution exposure) aging processes at the molecular and phenotypic levels. Skin aging is a process accompanied by changes that alter the local microenvironment, such as weakening of the skin barrier and the accumulation of stressed and senescent cells, both of which foster inflammation through the invasion/release of Pathogen-Associated Molecular Patterns and Damage-Associated Molecular Patterns. The consequences of such an altered microenvironment include the promotion of the senescence-associated secretory phenotype (SASP), compromising tissue renewal and function, altered cellular interactions, and chronic low-grade inflammation. This sterile inflammatory state, termed inflammaging, develops in several organs with advanced age and is associated with persistent inflammation that ultimately exhausts the skin's defense system.

Macrophages (Mφ), a group of heterogeneous and plastic cells, play a central role in tissue homeostasis and repair, as well as host defense. In the skin, Mφ can be found in different layers, being classified as recruited Mφ originating from monocytes following a recruitment process started by tissue injury, or as tissue-resident macrophages (TRM), which are derived from both adult and embryonic progenitors. Mφ may acquire different phenotypes in response to various stimuli. In this sense, based on in vitro assays, Mφ have been divided into two groups based on their polarization phenotypes: M1 and M2. Classically activated Mφ are deemed as M1 and constitute catabolic, proinflammatory cells that are involved in antimicrobial host defense. M2, or alternatively activated Mφ, are anabolic cells with anti-inflammatory and tissue repair properties. However, mainly due to recent advances in single-cell RNA sequencing, it is now clear that such a dichotomy does not accurately represent Mφ in vivo but represents the extremes of a wide range of continuous phenotypes which have been reported.

The aging process has a great impact on Mφ, including alterations in Mφ metabolic and immune function, impacting the Mφ capability of clearance and immunosurveillance, constituting an important aspect of immunosenescence. In fact, old Mφ in a mice model were characterized with a senescent, proinflammatory profile, associated with increased oxidative stress, compromised antioxidant defenses, and impaired function. Mφ are considered as gatekeepers of tissue homeostasis and integrity, constituting primary inflammatory cytokine producers, as well as initiators and regulators of inflammation, and representing one of the main cellular players in adaptive immunity exacerbation and exhaustion during aging. In recognition of the age-related alterations on Mφ function and their importance during skin aging, in this review, we will dissect how aging hallmarks may alter the Mφ phenotype and function and connect these plastic cells with skin inflammaging.