Epigenetic Drift Is a Determinant of Mammalian Lifespan

Multimodal cell atlas of the ageing human skeletal muscle

Muscle atrophy and functional decline (sarcopenia) are common manifestations of frailty and are critical contributors to morbidity and mortality in older people1. Deciphering the molecular mechanisms underlying sarcopenia has major implications for understanding human ageing2. Yet, progress has been slow, partly due to the difficulties of characterizing skeletal muscle niche heterogeneity (whereby myofibres are the most abundant) and obtaining well-characterized human samples3,4. Here we generate a single-cell/single-nucleus transcriptomic and chromatin accessibility map of human limb skeletal muscles encompassing over 387,000 cells/nuclei from individuals aged 15 to 99 years with distinct fitness and frailty levels. We describe how cell populations change during ageing, including the emergence of new populations in older people, and the cell-specific and multicellular network features (at the transcriptomic and epigenetic levels) associated with these changes. On the basis of cross-comparison with genetic data, we also identify key elements of chromatin architecture that mark susceptibility to sarcopenia. Our study provides a basis for identifying targets in the skeletal muscle that are amenable to medical, pharmacological and lifestyle interventions in late life.

Polyphenolic Compounds: Orchestrating Intestinal Microbiota Harmony during Aging

In the aging process, physiological decline occurs, posing a substantial threat to the physical and mental well-being of the elderly and contributing to the onset of age-related diseases. While traditional perspectives considered the maintenance of life as influenced by a myriad of factors, including environmental, genetic, epigenetic, and lifestyle elements such as exercise and diet, the pivotal role of symbiotic microorganisms had been understated. Presently, it is acknowledged that the intestinal microbiota plays a profound role in overall health by signaling to both the central and peripheral nervous systems, as well as other distant organs. Disruption in this bidirectional communication between bacteria and the host results in dysbiosis, fostering the development of various diseases, including neurological disorders, cardiovascular diseases, and cancer. This review aims to delve into the intricate biological mechanisms underpinning dysbiosis associated with aging and the clinical ramifications of such dysregulation. Furthermore, we aspire to explore bioactive compounds endowed with functional properties capable of modulating and restoring balance in this aging-related dysbiotic process through epigenetics alterations.

Exercise-induced redox modulation as a mediator of DNA methylation in health maintenance and disease prevention

The evidence for physical activity (PA) as a major public health preventive approach and a potent medical therapy has increased exponentially in the last decades. The biomolecular mechanisms supporting the associations between PA and/or structured exercise training with health maintenance and disease prevention are not completely characterized. However, increasing evidence pointed out the role of epigenetic modifications in exercise adaptation and health-enhancing PA throughout life, DNA methylation being the most intensely studied epigenetic modification induced by acute and chronic exercise. The current data on the modulation of DNA methylation determined by physically active behavior or exercise interventions points out genes related to energy regulation, mitochondrial function, and biosynthesis, as well as muscle regeneration, calcium signaling pathways, and brain plasticity, all consistent with the known exercise-induced redox signaling and/or reactive oxygen species (ROS) unbalance. Thus, the main focus of this review is to discuss the role of ROS and redox-signaling on DNA methylation profile and its impact on exercise-induced health benefits in humans.

The rate of epigenetic drift scales with maximum lifespan across mammals

Epigenetic drift or "disorder" increases across the mouse lifespan and is suggested to underlie epigenetic clock signals. While the role of epigenetic drift in determining maximum lifespan across species has been debated, robust tests of this hypothesis are lacking. Here, we test if epigenetic disorder at various levels of genomic resolution explains maximum lifespan across four mammal species. We show that epigenetic disorder increases with age in all species and at all levels of genomic resolution tested. The rate of disorder accumulation occurs faster in shorter lived species and corresponds to species adjusted maximum lifespan. While the density of cytosine-phosphate-guanine dinucleotides ("CpGs") is negatively associated with the rate of age-associated disorder accumulation, it does not fully explain differences across species. Our findings support the hypothesis that the rate of epigenetic drift explains maximum lifespan and provide partial support for the hypothesis that CpG density buffers against epigenetic drift.

Ten-Eleven Translocation 1 and 2 Enzymes Affect Human Skin Fibroblasts in an Age-Related Manner

Ten-eleven translocation (TET) enzymes catalyze the oxidation of 5-methylcytosine (5mC), first to 5-hydroxymethylcytosine (5hmC), then to 5-formylcytosine (5fC), and finally to 5-carboxycytosine (5caC). Evidence suggests that changes in TET expression may impact cell function and the phenotype of aging. Proliferation, apoptosis, markers of autophagy and double-strand DNA break repair, and the expression of Fibulin 5 were assessed by flow cytometry in TET1 and TET2-overexpressing fibroblasts isolated from sun-unexposed skin of young (23-35 years) and age-advanced (75-94 years) individuals. In cells derived from young individuals, TET1 overexpression resulted in the inhibition of proliferation and apoptosis by 37% (p = 0.03) and 24% (p = 0.05), respectively, while the overexpression of TET2 caused a decrease in proliferation by 46% (p = 0.01). Notably, in cells obtained from age-advanced individuals, TETs exhibited different effects. Specifically, TET1 inhibited proliferation and expression of autophagy marker Beclin 1 by 45% (p = 0.05) and 28% (p = 0.048), respectively, while increasing the level of γH2AX, a marker of double-strand DNA breaks necessary for initiating the repair process, by 19% (p = 0.04). TET2 inhibited proliferation by 64% (p = 0.053) and increased the level of γH2AX and Fibulin 5 by 46% (p = 0.007) and 29% (p = 0.04), respectively. These patterns of TET1 and TET2 effects suggest their involvement in regulating various fibroblast functions and that some of their biological actions depend on the donor's age.

Which Factors Influence Healthy Aging? A Lesson from the Longevity Village of Bama in China

A growing aging population is associated with increasing incidences of aging-related diseases and socioeconomic burdens. Hence, research into healthy longevity and aging is urgently needed. Longevity is an important phenomenon in healthy aging. The present review summarizes the characteristics of longevity in the elderly population in Bama, China, where the proportion of centenarians is 5.7-fold greater than the international standard. We examined the impact of genetic and environmental factors on longevity from multiple perspectives. We proposed that the phenomenon of longevity in this region is of high value for future investigations in healthy aging and aging-related disease and may provide guidance for fostering the establishment and maintenance of a healthy aging society.

Epigenetics as a mediator of plasticity in cancer

The concept of an epigenetic landscape describing potential cellular fates arising from pluripotent cells, first advanced by Conrad Waddington, has evolved in light of experiments showing nondeterministic outcomes of regulatory processes and mathematical methods for quantifying stochasticity. In this Review, we discuss modern approaches to epigenetic and gene regulation landscapes and the associated ideas of entropy and attractor states, illustrating how their definitions are both more precise and relevant to understanding cancer etiology and the plasticity of cancerous states. We address the interplay between different types of regulatory landscapes and how their changes underlie cancer progression. We also consider the roles of cellular aging and intrinsic and extrinsic stimuli in modulating cellular states and how landscape alterations can be quantitatively mapped onto phenotypic outcomes and thereby used in therapy development.

Aging and aging-related diseases: from molecular mechanisms to interventions and treatments

Aging is a gradual and irreversible pathophysiological process. It presents with declines in tissue and cell functions and significant increases in the risks of various aging-related diseases, including neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. Although the development of modern medicine has promoted human health and greatly extended life expectancy, with the aging of society, a variety of chronic diseases have gradually become the most important causes of disability and death in elderly individuals. Current research on aging focuses on elucidating how various endogenous and exogenous stresses (such as genomic instability, telomere dysfunction, epigenetic alterations, loss of proteostasis, compromise of autophagy, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, deregulated nutrient sensing) participate in the regulation of aging. Furthermore, thorough research on the pathogenesis of aging to identify interventions that promote health and longevity (such as caloric restriction, microbiota transplantation, and nutritional intervention) and clinical treatment methods for aging-related diseases (depletion of senescent cells, stem cell therapy, antioxidative and anti-inflammatory treatments, and hormone replacement therapy) could decrease the incidence and development of aging-related diseases and in turn promote healthy aging and longevity.

Network Approaches for Charting the Transcriptomic and Epigenetic Landscape of the Developmental Origins of Health and Disease

The early developmental phase is of critical importance for human health and disease later in life. To decipher the molecular mechanisms at play, current biomedical research is increasingly relying on large quantities of diverse omics data. The integration and interpretation of the different datasets pose a critical challenge towards the holistic understanding of the complex biological processes that are involved in early development. In this review, we outline the major transcriptomic and epigenetic processes and the respective datasets that are most relevant for studying the periconceptional period. We cover both basic data processing and analysis steps, as well as more advanced data integration methods. A particular focus is given to network-based methods. Finally, we review the medical applications of such integrative analyses.

The intervention on aging system: A classification model, the requirement for five novel categories

Aging is widely considered an immovable fact of life. Cultural conditioning has ensured that therapeutics for extreme human lifespans are considered out of reach technologies. However, longevity therapies such as stem cell replacement, fasting, gene therapies, fasting mimetics such as metformin and rapamycin, regulation and tissue reprogramming with OSK transcription factors, blood dilution, metabolic pathway engineering, reversal of epigenetic drift, heterochronic parabiosis, coenzyme replacement technologies (nicotinamide adenine dinucleotide) and a plethora of other established sciences are showing great potential at slowing down the rate at which tissues enter dysfunction. Recent discoveries have shed light on major mysteries of the aging process. Longevity-based discoveries are not only landing quickly, but therapies to prevent or reverse those drivers of aging are also being devised regularly and this is opening up an entirely new industry, the longevity industry. This presents the requirement for a new classification system where subjects can be divided into specific groups based on their potential for mortality. This system also enables the public to target which class of this classification system they wish to be on. Moving the population on the classification system to become more disease resistant holds great benefit for society and governments as a whole.

Mitochondrial DNA methylation drift and postoperative delirium in mice

BACKGROUND

Mitochondrial dysfunction is linked to the etiopathogenesis of postoperative delirium (POD), which severely affects the prognosis of elderly patients undergoing surgery. The methylation of mitochondrial DNA (mtDNA), a new and incompletely described phenomenon that regulates the structure and function of mitochondria, is associated with ageing. However, the relationship between mtDNA methylation and POD has not been established.

OBJECTIVE

To explore the potential roles of mitochondrial epigenetic regulation in POD.

DESIGN

A randomised animal study.

PARTICIPANTS

Eighty-eight 6-month-old and one hundred seventy-six 18-month-old male C57BL/6N mice.

INTERVENTIONS

POD was induced by abdominal surgery under 1.4% isoflurane for 2 h. Behavioural tests were performed at 24 h before surgery and at 6, 9 and 24 h after surgery.

MAIN OUTCOME MEASURES

5-methylcytosine (5-mC) at five CpG sites of the displacement loop (D-loop) and at 60 CpG sites of coding gene loci in the mitochondrial genome after surgery of the hippocampus, prefrontal cortex, amygdala and anterior cingulate cortex in 6 and 18-month-old mice were detected using bisulfite pyrosequencing. Mitochondrial structure, mitochondrial gene expression and mtDNA copy number were also examined using Electron microscopy and real time PCR to find the association with mtDNA methylation.

RESULTS

The mtDNA methylation drift manifested as a decrease in the methylation levels at the D-loop and an increase or decrease in the methylation levels at several coding gene loci, ultimately resulting in reduced mtDNA copy numbers, altered mitochondrial gene expression and damaged mitochondrial structures in the hippocampus and prefrontal cortex after surgery. The activation of Silent information regulator-1 (SIRT1) ameliorated anaesthesia-induced and surgery-induced mitochondrial dysfunction and delirium-like behaviours by regulating mtDNA methyltransferase-mediated mtDNA methylation.

CONCLUSION

These data support the existence of epigenetic mtDNA regulation in POD; however, further studies are required to explore the specific mechanisms.

TRIAL REGISTRATION

No 20181204 Drum tower hospital.

The Annoying Flaws of Gerontological Research

Gerontological research has accelerated dramatically in the last few decades. However, despite increased public interest, federal funding, an army of researchers, and many notable discoveries and high-impact publications, the goal of achieving even a modest extension of human lifespan seems to be as far away as ever or, at best, remains within the realm of lifestyle and diet optimization efforts. Humanity has already benefited from a lifespan revolution in the first half of 20^th Century, which was brought about by improved sanitation and hygiene, clean water, and our successful war on infectious diseases. Thanks to all these developments, in which gerontologists played no part, our expected lifespan increased by about 40% and our primary causes of death decidedly shifted from extrinsic to intrinsic causality. The next step is not that simple as it implies tackling intrinsic mechanisms of aging, and the lack of working human-specific antiaging solutions likely stems from flawed research strategies.

Impact of chromosomal organization on epigenetic drift and domain stability revealed by physics-based simulations

We examine the relationship between the size of domains of epigenetic marks and the stability of those domains using our theoretical model that captures the physical mechanisms governing the maintenance of epigenetic modifications. We focus our study on histone H3 lysine-9 trimethylation, one of the most common and consequential epigenetic marks with roles in chromatin compaction and gene repression. Our model combines the effects of methyl spreading by methyltransferases and chromatin segregation into heterochromatin and euchromatin because of preferential heterochromatin protein 1 (HP1) binding. Our model indicates that, although large methylated domains are passed successfully from one chromatin generation to the next, small alterations to the methylation sequence are not maintained during chromatin replication. Using our predictive model, we investigate the size required for an epigenetic domain to persist over chromatin generations while surrounded by a much larger domain of opposite methylation and compaction state. We find that there is a critical size threshold in the hundreds-of-nucleosomes scale above which an epigenetic domain will be reliably maintained over generations. The precise size of the threshold differs for heterochromatic and euchromatic domains. Our results are consistent with natural alterations to the epigenetic sequence occurring during embryonic development and due to age-related epigenetic drift.

Nanoparticle platforms for dermal antiaging technologies: Insights in cellular and molecular mechanisms

Aging is a continuous process defined by a progressive functional decline in physiological parameters. Skin, being one of the most vulnerable organs, shows early signs of aging which are predominantly affected by intrinsic factors like hormone, gender, mood, enzymes, and genetic predisposition, and extrinsic factors like exposure to radiation, air pollution, and heat. Visible morphological and anatomical changes associated with skin aging occur due to underlying physiological aberrations governed by numerous complex interactions at cellular and subcellular levels. Nanoparticles are perceived as a powerful tool in the cosmeceutical industry both for augmenting the efficacy of existing agents and as a novel standalone therapy. Both organic and inorganic nanoparticles have been extensively investigated in antiaging applications. The use of nanoparticles helps to enhance the activity of antiaging molecules by selectively targeting cellular and molecular pathways. On the other hand, the nanoparticle platforms also gained increasing popularity as the skin protectant against extrinsic factors such as UV radiation and pollutants. This review comprehensively discusses skin aging and its mechanism by highlighting the impact on cellular, subcellular, and epigenetic elements. Importantly, the review elaborates on the examples of organic and inorganic nanoparticle-based formulations developed for antiaging application and provides mechanistic insights on how they modulate the mechanisms of skin aging. The clinical progress of nanoparticle antiaging technologies and factors that impact clinical translation are also explored. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Epigenetic enzymes: A role in aging and prospects for pharmacological targeting

The development of interventions aimed at improving healthspan is one of the priority tasks for the academic and public health authorities. It is also the main objective of a novel branch in biogerontological research, geroscience. According to the geroscience concept, targeting aging is an effective way to combat age-related disorders. Since aging is an exceptionally complex process, system-oriented integrated approaches seem most appropriate for such an interventional strategy. Given the high plasticity and adaptability of the epigenome, epigenome-targeted interventions appear highly promising in geroscience research. Pharmaceuticals targeted at mechanisms involved in epigenetic control of gene activity are actively developed and implemented to prevent and treat various aging-related conditions such as cardiometabolic, neurodegenerative, inflammatory disorders, and cancer. In this review, we describe the roles of epigenetic mechanisms in aging; characterize enzymes contributing to the regulation of epigenetic processes; particularly focus on epigenetic drugs, such as inhibitors of DNA methyltransferases and histone deacetylases that may potentially affect aging-associated diseases and longevity; and discuss possible caveats associated with the use of epigenetic drugs.

Caloric restriction following early-life high fat-diet feeding represses skeletal muscle TNF in male rats

Chronic metabolic diseases are on the rise worldwide and their etiology is multifactorial. Among them, inflammatory components like Tumor Necrosis Factor (TNF), contribute to whole-body metabolic impairment. Caloric Restriction (CR) combats metabolic diseases, but how it reduces inflammation remains understudied. We aimed to evaluate the impact of chronic CR on muscle inflammation, in particular TNF. In our study, 4-week old male Sprague-Dawley rats were fed a high-fat diet (HF, 45% Kcal of fat from lard) ad libitum for 3 months. After estimation of their energy requirement (1 month), they were then divided into three groups: HF ad libitum (OL), weight maintenance with AIN93M (9.5% Kcal from fat; ML, 100% of energy requirement), and caloric restriction (CR, AIN93M with 75% of energy requirement). This dietary intervention continued for six months. At this point, rats were sacrificed and gastrocnemius muscle was collected. CR induced a profound shift in fat and lean mass, and decreased growth factor IGF-1. Muscle qPCR analysis showed a marked decrease in inflammation and TNF (premRNA, mRNA, and protein) by CR, accompanied by Tnf promoter DNA hypermethylation. CR increased expression of histone deacetylase Sirt6 and decreased methyltransferase Suv39h1, together with decreased Tnf promoter and coding region binding of NF- κB and C/EBP-β. Following miRNA database mining, qPCR analysis revealed that CR downregulated the proinflammatory miR-19b and increased the anti-inflammatory miR-181a and its known targets. Chronic CR is able to regulate muscle-specific inflammation by targeting the NF-κB pathway as well as transcriptional and post-transcriptional regulation of Tnf gene.

Specific Differentially Methylated and Expressed Genes in People with Longevity Family History

Background

We attempt to identify specific differentially methylated and expressed genes in people with longevity family history, it will contribute to discover significant features about human longevity.

Methods

A prevalence study was conducted during October 2017 to January 2019 in Bama County of Guangxi, China and individuals were recruited and grouped into longevity family (n=60) and non-longevity family (n=60) to identify differentially methylated genes (DMGs). The expression profile dataset GSE16717 was downloaded from the GEO database in which individuals were divided into 3 groups, namely longevity (n=50), longevity offspring (n=50) and control (n=50) for identifying differentially expressed genes (DEGs). It was considered significantly different when P or adjusted P≤0.05.

Results

In total, 117 longevity-related hypermethylated genes enriched in interleukin secretion/production regulation, chemokine signaling pathway and natural killer cell-mediated cytotoxicity. Another 296 significant key longevity-related DEGs primarily involved in protein binding, nucleus, cytoplasm, T cell receptor signaling pathway and Metabolic pathway, H19 and PFKFB4 were found to be both methylated and downregulated in people with longevity family history.

Conclusion

Human longevity-specific genes involve in many immunity regulations and cellular immunity pathways, H19 and PFKFB4 show hypermethylated and suppressed status in people with longevity family history and might serve as longevity candidate genes.

Wandering along the epigenetic timeline

BACKGROUND

Increasing life expectancy but also healthspan seems inaccessible as of yet but it may become a reality in the foreseeable future. To extend lifespan, it is essential to unveil molecular mechanisms involved in ageing. As for healthspan, a better understanding of the mechanisms involved in age-related pathologies is crucial.

MAIN BODY

We focus on the epigenetic side of ageing as ageing is traced by specific epigenetic patterns and can be measured by epigenetic clocks. We discuss to what extent exposure to environmental factor, such as alcohol use, unhealthy diet, tobacco and stress, promotes age-related conditions. We focused on inflammation, cancer and Alzheimer's disease. Finally, we discuss strategies to reverse time based on epigenetic reprogramming.

CONCLUSIONS

Reversibility of the epigenetic marks makes them promising targets for rejuvenation. For this purpose, a better understanding of the epigenetic mechanisms underlying ageing is essential. Epigenetic clocks were successfully designed to monitor these mechanisms and the influence of environmental factors. Further studies on age-related diseases should be conducted to determine their epigenetic signature, but also to pinpoint the defect in the epigenetic machinery and thereby identify potential therapeutic targets. As for rejuvenation, epigenetic reprogramming is still at an early stage.

Commentary on Some Recent Theses Relevant to Combating Aging: December 2019

Theses reviewed in this issue include "Atrophied Thymus, a Tumor Reservoir for Harboring Melanoma Cells," "Evolutionary Adaptations in Developmental Signaling Pathways Underlie Regenerative Scar-Free Wound Repair in African Spiny Mouse (Genus Acomys)," "Integrated Immunoassays on Paper/Polymer Hybrid Microfluidic Devices for Low-Cost Detection of Disease Biomarkers," "RNA Regulation in the Nervous System: CircRNA Expression Changes During Aging, and Function of the Calm1 Extended 3' UTR Isoform," "The Role of Amylin in Alzheimer's Disease," and "Therapeutic Monoclonal Antibodies to Detect and Halt ATTR Cardiac Amyloidosis and Neuropathy."

Commentary on Some Recent Theses Relevant to Combating Aging: June 2019

Theses reviewed in this issue include "Age-Associated Lamin-B1 Reduction in the Thymic Epithelial Cells and Its Role in Thymic Involution," "Brainstem Structural Integrity in the Progression of Alzheimer's Disease," "Challenging Current Paradigms: Increasing the Efficacy of Radiation Therapy with Novel Radiation Schemes," "Cross-Talk Between the Skeletal Muscle Stem Cells and Endothelial Cells," "Design and Synthesis of Enzyme-MOF (Metal-Organic Framework) Composites for Long-Persistent Biomedical Applications," and "Megakaryocyte-Membrane Wrapped Nanoparticles for Targeted Delivery to Hematopoietic Stem Cells."

Urinary ionomic analysis reveals new relationship between minerals and longevity in a Han Chinese population

Human longevity involves genetic, nutritional, environmental and many other factors playing a key role in healthy aging. Previous studies have shown that mineral metabolism and homeostasis are associated with lifespan extension. However, the majority of them have focused on a limited number of elements and ignored the complex relationship between them. In this study, we carried out a network-based approach to investigate the urinary ionome of nonagenarians and centenarians (longevity group) when compared with their biologically unrelated and younger family members (control group) from a Han Chinese population. Several differentially changed elements were identified, almost all of which showed an elevated level in the longevity group. Correlation analysis of the ionome revealed significant element-element interactions in each group. We then divided each group into distinct subgroups according to age ranges, and built the elemental correlation network for each of them. Significant elemental correlations and correlation changes involving all examined elements were identified within or between different subgroups, implying a highly dynamic and complex crosstalk among the elements during human life. Finally, more similar elemental patterns were observed between extremely old and middle-aged people. Overall, our data reveal new relationship between urinary minerals and human longevity, which may extend our understanding of the mechanism of healthy aging.

Epigenetic Regulation of Metabolism and Inflammation by Calorie Restriction

Chronic caloric restriction (CR) without malnutrition is known to affect different cellular processes such as stem cell function, cell senescence, inflammation, and metabolism. Despite the differences in the implementation of CR, the reduction of calories produces a widespread beneficial effect in noncommunicable chronic diseases, which can be explained by improvements in immuno-metabolic adaptation. Cellular adaptation that occurs in response to dietary patterns can be explained by alterations in epigenetic mechanisms such as DNA methylation, histone modifications, and microRNA. In this review, we define these modifications and systematically summarize the current evidence related to CR and the epigenome. We then explain the significance of genome-wide epigenetic modifications in the context of disease development. Although substantial evidence exists for the widespread effect of CR on longevity, there is no consensus regarding the epigenetic regulations of the underlying cellular mechanisms that lead to improved health. We provide compelling evidence that CR produces long-lasting epigenetic effects that mediate expression of genes related to immuno-metabolic processes. Epigenetic reprogramming of the underlying chronic low-grade inflammation by CR can lead to immuno-metabolic adaptations that enhance quality of life, extend lifespan, and delay chronic disease onset.

The Impact of Caloric Restriction on the Epigenetic Signatures of Aging

Aging is characterized by an extensive remodeling of epigenetic patterns, which has been implicated in the physiopathology of age-related diseases. Nutrition plays a significant role in modulating the epigenome, and a growing amount of data indicate that dietary changes can modify the epigenetic marks associated with aging. In this review, we will assess the current advances in the relationship between caloric restriction, a proven anti-aging intervention, and epigenetic signatures of aging. We will specifically discuss the impact of caloric restriction on epigenetic regulation and how some of the favorable effects of caloric restriction on lifespan and healthspan could be mediated by epigenetic modifications.

A Clinical Trial Using Methylation Age to Evaluate Current Antiaging Practices

Recent advances in the technology of "aging clocks" based on DNA methylation suggest that it may be possible to measure changes in the rate of human aging over periods as short as a year or two. To the extent that methylation (and other biomarkers) are valid surrogates for biological age, the testing of antiaging interventions has thus become radically cheaper, faster, and more practical. Together with colleagues at UCLA, I have initiated a clinical trial to evaluate some of the most popular antiaging strategies currently deployed by "early adopters" in the lay community of personal health activists. We are recruiting 5000 subjects, age 45-65, and interviewing them in detail about their diet, drugs and supplements, exercise, social, and other practices that plausibly contribute to modulate the rate of aging. They agree to submit blood samples for analysis of methylation age at the beginning, middle, and end of a 2-year test period. Primary endpoint is the difference in methylation age over the course of 2 years. We are in the process of developing a specialized clock, optimized for individual differences over time. Results will be viewed as an exploratory study to identify synergistic combinations of age-retarding treatments. It is our expectation that there is a great deal of redundancy in the strategies that have been researched and promoted to the aware public; thus, most combinations can retard the rate of aging by only a few percent, consistent with the best known single measures. However, we hope that among the many strategies that our subjects have adopted, there will be some combinations that synergize and achieve age retardation by ≥25% or more. A mock-up analysis of computer-generated data has been performed to fix parameters of the study, and confirm that such combinations will be able to be detected with good probability, should they exist. All data (redacted for privacy) will be open sourced, available to the scientific community and to the public.

Developmental Tuning of Epigenetic Clock

Research in the field of gerontology has traditionally focused on later life stages. There is increasing evidence, however, that both the rate of age-related functional decline and the later-life health status can be programmed during early development. The central role of epigenetic mechanisms (methylation of DNA, histone modifications and regulation by non-coding RNAs) in mediating these long-term effects has been elucidated. Both rate and direction of age-associated change of epigenetic patterns (“epigenetic drift”) were shown to be largely dependent on early-life environmental conditions. Inter-individual divergences in epigenetic profiles may arise following the stochastic errors in maintaining epigenetic marks, but they may also be adaptively mediated by specific environmental cues. Recent cohort studies indicate that ticking rate of epigenetic clock, estimated by a DNA methylation-based methods, may be developmentally adjusted, and that individual’s discrepancies among epigenetic and chronological age would be likely programmed early in development. In this Perspective article, recent findings suggesting the importance of early-life determinants for life-course dynamics of epigenetic drift are summarized and discussed.

Developmental programming of aging trajectory

There is accumulating evidence that aging phenotype and longevity may be developmentally programmed. Main mechanisms linking developmental conditions to later-life health outcomes include persistent changes in epigenetic regulation, (re)programming of major endocrine axes such as growth hormone/insulin-like growth factor axis and hypothalamic-pituitary-adrenal axis and also early-life immune maturation. Recently, evidence has also been generated on the role of telomere biology in developmental programming of aging trajectory. In addition, persisting changes of intestinal microbiota appears to be crucially involved in these processes. In this review, experimental and epidemiological evidence on the role of early-life conditions in programming of aging phenotypes are presented and mechanisms potentially underlying these associations are discussed.

Physiological and Molecular Mechanisms of Methionine Restriction

Methionine restriction (MR) has been studied extensively over the last 25 years for its role in altering metabolic hallmarks of disease. Animals subjected to MR, display changes in metabolic flexibility demonstrated by increases in energy expenditure, glucose tolerance, and lifespan. These changes have been well characterized in a number of model systems and significant progress has been made in understanding how hepatic fibroblast growth factor 21 links MR to several components of its metabolic phenotype. Despite these advances, a complete understanding of mechanisms engaged by dietary MR remains elusive. In this review, we offer a brief history of MR and its known mechanisms associated with stress, metabolism, and lifespan extension. We consider the role of epigenetics in the response of animals to MR and propose a novel epigenetic pathway involving the regulation of microRNAs during MR.