Prediction of biological age by morphological staging of sarcopenia in Caenorhabditis elegans

Sarcopenia encompasses a progressive decline in muscle quantity and quality. Given its close association with ageing, it may represent a valuable healthspan marker. The commonalities with human muscle structure and facile visualization possibilities make Caenorhabditis elegans an attractive model for studying the relationship between sarcopenia and healthspan. However, classical visual assessment of muscle architecture is subjective and has low throughput. To resolve this, we have developed an image analysis pipeline for the quantification of muscle integrity in confocal microscopy images from a cohort of ageing myosin::GFP reporter worms. We extracted a variety of morphological descriptors and found a subset to scale linearly with age. This allowed establishing a linear model that predicts biological age from a morphological muscle signature. To validate the model, we evaluated muscle architecture in long-lived worms that are known to experience delayed sarcopenia by targeted knockdown of the daf-2 gene. We conclude that quantitative microscopy allows for staging sarcopenia in C. elegans and may foster the development of image-based screens in this model organism to identify modulators that mitigate age-related muscle frailty and thus improve healthspan.

Summary: A tool for quantitative image analysis of muscle deterioration that allows predicting healthspan in the nematode model Caenorhabditis elegans and may lead to the first C. elegans-based high-throughput sarcopenia screening platform.

Skeletal muscle mitochondrial respiration in a model of age-related osteoarthritis is impaired after dietary rapamycin

A decline in skeletal muscle mitochondrial function is associated with the loss of skeletal muscle size and function during knee osteoarthritis (OA). We have recently reported that 12-weeks of dietary rapamycin (Rap, 14 ppm), with or without metformin (Met, 1000 ppm), increased plasma glucose and OA severity in male Dunkin Hartley (DH) guinea pigs, a model of naturally occurring, age-related OA. The purpose of the current study was to determine if increased OA severity after dietary Rap and Rap+Met was accompanied by impaired skeletal muscle mitochondrial function. Mitochondrial respiration and hydrogen peroxide (H₂O₂) emissions were evaluated in permeabilized muscle fibers via high-resolution respirometry and fluorometry using either a saturating bolus or titration of ADP. Rap and Rap+Met decreased complex I (CI)-linked respiration and tended to increase ADP sensitivity, consistent with previous findings in patients with end-stage OA. The decrease in CI-linked respiration was accompanied with lower CI protein abundance. Rap and Rap+Met did not change mitochondrial H₂O₂ emissions. There were no differences between mitochondrial function in Rap versus Rap+Met suggesting that Rap was likely driving the change in mitochondrial function. This is the first inquiry into how lifespan extending treatments Rap and Rap+Met can influence skeletal muscle mitochondria in a model of age-related OA. Collectively, our data suggest that Rap with or without Met inhibits CI-linked capacity and increases ADP sensitivity in DH guinea pigs that have greater OA severity.

Generation and characterization of a tractable C. elegans model of tauopathy

Alzheimer's disease(AD) is an age-associated neurodegenerative disease that results in deterioration of memory and cognitive function. As a currently untreatable disorder, AD has emerged as one of the defining biomedical challenges of our time. Thus, new approaches that can examine the cellular and molecular mechanisms underlying age-related AD pathology are sorely needed. One of the hallmarks of Alzheimer's disease is the hyperphosphorylation of the tau protein. Caenorhabditis elegans have been previously used to study the genetic pathways impacted by tau proteotoxic stress; however, currently, available C. elegans tau models express the human protein solely in neurons, which are unresponsive to global RNA interference (RNAi). This limits powerful RNAi screening methods from being utilized effectively in these disease models. Our goal was to develop a C. elegans tau model that has pronounced tau-induced disease phenotypes in cells that can be modified by feeding RNAi methods. Towards this end, we generated a novel C. elegans transgenic line with codon-optimized human 0N4R V337M tau expressed in the body wall muscle under the myo-3 promoter. Immunoblotting experiments revealed that the expressed tau is phosphorylated on epitopes canonically associated with human AD pathology. The tau line has significantly reduced health metrics, including egg laying, growth rate, paralysis, thrashing frequency, crawling speed, and lifespan. These defects are suppressed by RNAi directed against the tau mRNA. Taken together, our results suggest that this alternative tau genetic model could be a useful tool for uncovering the mechanisms that influence the hyperphosphorylation and toxicity of human tau via RNAi screening and other approaches.

Analysis of representative mutants for key DNA repair pathways on healthspan in Caenorhabditis elegans

Although the link between DNA damage and aging is well accepted, the role of different DNA repair proteins on functional/physiological aging is not well-defined. Here, using Caenorhabditis elegans, we systematically examined the effect of three DNA repair genes involved in key genome stability pathways. We assayed multiple health proxies including molecular, functional and resilience measures to define healthspan. Loss of XPF-1/ERCC-1, a protein involved in nucleotide excision repair (NER), homologous recombination (HR) and interstrand crosslink (ICL) repair, showed the highest impairment of functional and stress resilience measures along with a shortened lifespan. brc-1 mutants, with a well-defined role in HR and ICL are short-lived and highly sensitive to acute stressors, specifically oxidative stress. In contrast, ICL mutant, fcd-2 did not impact lifespan or most healthspan measures. Our efforts also uncover that DNA repair mutants show high sensitivity to oxidative stress with age, suggesting that this measure could act as a primary proxy for healthspan. Together, these data suggest that impairment of multiple DNA repair genes can drive functional/physiological aging. Further studies to examine specific DNA repair genes in a tissue specific manner will help dissect the importance and mechanistic role of these repair systems in biological aging.

Preclinical and clinical evidence of NAD+ precursors in health, disease, and ageing

NAD⁺ is a fundamental molecule in human life and health as it participates in energy metabolism, cell signalling, mitochondrial homeostasis, and in dictating cell survival or death. Emerging evidence from preclinical and human studies indicates an age-dependent reduction of cellular NAD⁺, possibly due to reduced synthesis and increased consumption. In preclinical models, NAD⁺ repletion extends healthspan and / or lifespan and mitigates several conditions, such as premature ageing diseases and neurodegenerative diseases. These findings suggest that NAD⁺ replenishment through NAD⁺ precursors has great potential as a therapeutic target for ageing and age-predisposed diseases, such as Alzheimer's disease. Here, we provide an updated review on the biological activity, safety, and possible side effects of NAD⁺ precursors in preclinical and clinical studies. Major NAD⁺ precursors focused on by this review are nicotinamide riboside (NR), nicotinamide mononucleotide (NMN), and the new discovered dihydronicotinamide riboside (NRH). In summary, NAD⁺ precursors have an exciting therapeutic potential for ageing, metabolic and neurodegenerative diseases.

The protein inputs of an ultra-predictive aging clock represent viable anti-aging drug targets

Machine learning models capable of predicting age given a set of inputs are referred to as aging clocks. We recently developed an aging clock that utilizes 491 plasma protein inputs, has an exceptional accuracy, and is capable of measuring biological age. Here, we demonstrate that this clock is extremely predictive (r = 0.95) when used to measure age in a novel plasma proteomic dataset derived from 370 human subjects aged 18-69 years. Over-representation analyses of the proteins that make up this clock in the Gene Ontology and Reactome databases predominantly implicated innate and adaptive immune system processes. Immunological drugs and various age-related diseases were enriched in the DrugBank and GLAD4U databases. By performing an extensive literature review, we find that at least 269 (54.8 %) of these inputs regulate lifespan and/or induce changes relevant to age-related disease when manipulated in an animal model. We also show that, in a large plasma proteomic dataset, the majority (57.2 %) of measurable clock proteins significantly change their expression level with human age. Different subsets of proteins were overlapped with distinct epigenetic, transcriptomic, and proteomic aging clocks. These findings indicate that the inputs of this age predictor likely represent a rich source of anti-aging drug targets.

The Role of Rapamycin in Healthspan Extension via the Delay of Organ Aging

Aging can not only shorten a healthy lifespan, but can also lead to multi-organ dysfunction and failure. Anti-aging is a complex and worldwide conundrum for eliminating the various pathologies of senility. The past decade has seen great progress in the understanding of the aging-associated signaling pathways and their application for developing anti-aging approaches. Currently, some drugs can improve quality of life. The activation of mammalian target of rapamycin (mTOR) signaling is one of the core and detrimental mechanisms related to aging; rapamycin can reduce the rate of aging, improve age-related diseases by inhibiting the mTOR pathway, and prolong lifespan and healthspan effectively. However, the current evidence for rapamycin in lifespan extension and organ aging is fragmented and scattered. In this review, we summarize the efficacy and safety of rapamycin in prolonging a healthy lifespan by systematically alleviating aging in multiple organ systems, i.e., the nervous, urinary, digestive, circulatory, motor, respiratory, endocrine, reproductive, integumentary and immune systems, to provide a theoretical basis for the future clinical application of rapamycin in anti-aging.

Healthy Aging Interventions Reduce Repetitive Element Transcripts

Transcripts from noncoding repetitive elements (REs) in the genome may be involved in aging. However, they are often ignored in transcriptome studies on healthspan and lifespan, and their role in healthy aging interventions has not been characterized. Here, we analyze REs in RNA-seq datasets from mice subjected to robust healthspan- and lifespan-increasing interventions including calorie restriction, rapamycin, acarbose, 17-α-estradiol, and Protandim. We also examine RE transcripts in long-lived transgenic mice, and in mice subjected to a high-fat diet, and we use RNA-seq to investigate the influence of aerobic exercise on RE transcripts with aging in humans. We find that (a) healthy aging interventions/behaviors globally reduce RE transcripts, whereas aging and high-fat diet (an age-accelerating treatment) increase RE expression; and (b) reduced RE expression with healthy aging interventions is associated with biological/physiological processes mechanistically linked with aging. Our results suggest that RE transcript dysregulation and suppression are likely novel mechanisms underlying aging and healthy aging interventions, respectively.

Balancing DNA repair to prevent ageing and cancer

DNA damage is a constant stressor to the cell. Persistent damage to the DNA over time results in an increased risk of mutation and an accumulation of mutations with age. Loss of efficient DNA damage repair can lead to accelerated ageing phenotypes or an increased cancer risk, and the trade-off between cancer susceptibility and longevity is often driven by the cell's response to DNA damage. High levels of mutations in DNA repair mutants often leads to excessive cell death and stem cell exhaustion which may promote premature ageing. Stem cells themselves have distinct characteristics that enable them to retain low mutation rates. However, when mutations do arise, stem cell clonal expansion can also contribute to age-related tissue dysfunction as well as heightened cancer risk. In this review, we will highlight increasing DNA damage and mutation accumulation as hallmarks common to both ageing and cancer. We will propose that anti-ageing interventions might be cancer preventative and discuss the mechanisms through which they may act.

The Jackson Laboratory Nathan Shock Center: impact of genetic diversity on aging

Healthspan is a complex trait, influenced by many genes and environmental factors that accelerate or delay aging, reduce or increase disease risk, and extend or reduce lifespan. Thus, assessing the role of genetic variation in aging requires an experimental strategy capable of modeling the genetic and biological complexity of human populations. The goal of the The Jackson Laboratory Nathan Shock Center (JAX NSC) is to provide research resources and training for geroscience investigators that seek to understand the role of genetics and genetic diversity on the fundamental process of aging and diseases of human aging using the laboratory mouse as a model system. The JAX NSC has available novel, deeply characterized populations of aged mice, performs state-of-the-art phenotyping of age-relevant traits, provides systems genetics analysis of complex data sets, and provides all of these resources to the geroscience community. The aged animal resources, phenotyping capacity, and genetic expertise available through the JAX NSC benefit the geroscience community by fostering cutting-edge, novel lines of research that otherwise would not be possible. Over the past 15 years, the JAX NSC has transformed aging research across the geroscience community, providing aging mouse resources and tissues to researchers. All JAX NSC data and tools are publicly disseminated on the Mouse Phenome Database and the JAX NSC website, thus ensuring that the resources generated and expertise acquired through the Center are readily available to the aging research community. The JAX NSC will continue to enhance its ability to perform innovative research using a mammalian model to illuminate novel genotype-phenotype relationships and provide a rational basis for designing effective risk assessments and therapeutic interventions to boost longevity and disease-free healthspan.

Investigation of the relationships between sleep behaviors and risk of healthspan termination: a prospective cohort study based on 323,373 UK-Biobank participants

OBJECTIVES

To examine the associations between four sleep behaviors and the risk of healthspan termination.

METHODS

This study included 323,373 participants, free of terminated healthspan at baseline, from the UK-Biobank (UKB). We applied multivariable-adjusted Cox regression models to estimate the risk of terminated healthspan based on four sleep behaviors (insomnia/sleeplessness, napping, daytime sleepiness, and difficulty getting up from bed), which were self-reported and measured on Likert scales from "usually" to "never/rarely" experiences. In this study, healthspan was defined based on eight events that are strongly associated with longevity (congestive heart failure, myocardial infarction, chronic obstructive pulmonary disease, stroke, dementia, diabetes, cancer, and death).

RESULTS

Participants who reported the following unhealthy sleep behaviors had a significantly higher risk of terminated healthspan: "usually experience sleeplessness/insomnia" (HR = 1.05, 95% CI: 1.03-1.07; P < 0.001); "usually nap" (HR = 1.22, 95% CI: 1.18-1.26; P < 0.01); "excessive daytime sleepiness" (HR = 1.25, 95% CI: 1.19-1.32; P < 0.001); and "difficult getting up from bed" (HR = 1.08, 95% CI: 1.05-1.10; P < 0.001). The corresponding population attributable risk percentage (PAR%) indicated that about 7% of healthspan termination in this cohort would have been eliminated if all participants had healthy sleep behaviors.

CONCLUSION

Participants who reported "usually experience sleeplessness/insomnia," "usually nap," "excessive daytime sleepiness," and "difficult getting up from bed" had increased risk of shortened healthspan. Therefore, adherence to healthy sleep behavior is significant for the extension of healthspan.

Beta-guanidinopropionic acid has age-specific effects on markers of health and function in mice

AMP-activated protein kinase (AMPK) is a central regulator of both lifespan and health across multiple model organisms. β-Guanidinopropionic acid (GPA) is an endogenous AMPK activator previously shown to improve metabolic function in young and obese mice. In this study, we tested whether age of administration significantly affects the physiological outcomes of GPA administration in mice. We report that intervention starting at 7-8 months (young) results in activation of AMPK signaling and a phenotype consisting of lower body mass, improved glucose control, enhanced exercise tolerance, and altered mitochondrial electron transport chain flux similar to previous reports. When GPA treatment is started at 18-19 months (old), the effect of GPA on AMPK signaling is blunted compared to younger mice despite similar accumulation of GPA in skeletal muscle. Even so, GPA administration in older animals delayed age-related declines in lean mass, improved measures of gait performance and circadian rhythm, and increased fat metabolism as measured by respiratory exchange ratio. These results are likely partially driven by the relative difference in basal function and metabolic plasticity between young and old mice. Our results suggest that age-related declines in AMPK sensitivity may limit potential strategies targeting AMPK signaling in older subjects and suggest that further research and development is required for AMPK activators to realize their full potential.

Clinical biomarkers and associations with healthspan and lifespan: Evidence from observational and genetic data

Background

Biomarker-disease relationships are extensively investigated. However, associations between common clinical biomarkers and healthspan, the disease-free lifespan, are largely unknown. We aimed to explore the predictive values of ten biomarkers on healthspan and lifespan, and to identify putative causal mechanisms.

Methods

Using data from 12,098 Swedish individuals aged 47–94 years, we examined both serum concentrations and genetically predicted levels of ten glycemic, lipid-, inflammatory, and hematological biomarkers. During a follow-up period of up to 16 years, 3681 incident cases of any chronic disease (i.e., end of healthspan) and 2674 deaths (i.e., end of lifespan) were documented. Cox regression models were applied to estimate the associations of a one standard deviation increase in biomarkers with healthspan and lifespan.

Findings

Seven out of ten serum biomarkers were significantly associated with risks of any chronic disease and death; elevated glycemic biomarkers and high-density lipoprotein-related biomarkers showed the strongest detrimental (hazard ratio [HR] 1·29 [95% CI 1·24–1·34]) and protective effects (HR 0·92 [95% CI 0·89–0·96]), respectively. Genetic predisposition to elevated fasting blood glucose (FBG) was associated with increased risks of any chronic disease (HR 1·05 [95% CI 1·02–1·09]); genetically determined higher C-reactive protein correlated with lower death risks (HR 0·91 [95% CI 0·87–0·95]). Notably, the genetically proxied FBG-healthspan association was largely explained by serum FBG concentration.

Interpretation

Circulating concentrations of glycemic, lipid-, and inflammatory biomarkers are predictive of healthspan and lifespan. Glucose control is a putative causal mechanism and a potential intervention target for healthspan maintenance.

Funding

This study was supported by the Swedish Research Council (2015–03,255, 2018–02,077), FORTE (2013–2292), the Loo & Hans Osterman Foundation, the Foundation for Geriatric Diseases, the Magnus Bergwall Foundation, the Strategic Research Program in Epidemiology at Karolinska Institutet (SH, JJ), the China Scholarship Council, and the Swedish National Graduate School for Competitive Science on Ageing and Health. The Swedish Twin Registry is managed by Karolinska Institutet and receives funding as an infrastructure through the Swedish Research Council, 2017–00,641.

H3K27 modifiers regulate lifespan in C. elegans in a context-dependent manner

Background

Evidence of global heterochromatin decay and aberrant gene expression in models of physiological and premature ageing have long supported the “heterochromatin loss theory of ageing”, which proposes that ageing is aetiologically linked to, and accompanied by, a progressive, generalised loss of repressive epigenetic signatures. However, the remarkable plasticity of chromatin conformation suggests that the re-establishment of such marks could potentially revert the transcriptomic architecture of animal cells to a “younger” state, promoting longevity and healthspan. To expand our understanding of the ageing process and its connection to chromatin biology, we screened an RNAi library of chromatin-associated factors for increased longevity phenotypes.

Results

We identified the lysine demethylases jmjd-3.2 and utx-1, as well as the lysine methyltransferase mes-2 as regulators of both lifespan and healthspan in C. elegans. Strikingly, we found that both overexpression and loss of function of jmjd-3.2 and utx-1 are all associated with enhanced longevity. Furthermore, we showed that the catalytic activity of UTX-1, but not JMJD-3.2, is critical for lifespan extension in the context of overexpression. In attempting to reconcile the improved longevity associated with both loss and gain of function of utx-1, we investigated the alternative lifespan pathways and tissue specificity of longevity outcomes. We demonstrated that lifespan extension caused by loss of utx-1 function is daf-16 dependent, while overexpression effects are partially independent of daf-16. In addition, lifespan extension was observed when utx-1 was knocked down or overexpressed in neurons and intestine, whereas in the epidermis, only knockdown of utx-1 conferred improved longevity.

Conclusions

We show that the regulation of longevity by chromatin modifiers can be the result of the interaction between distinct factors, such as the level and tissue of expression. Overall, we suggest that the heterochromatin loss model of ageing may be too simplistic an explanation of organismal ageing when molecular and tissue-specific effects are taken into account.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12915-021-00984-8.

Health and longevity studies in C. elegans: the "healthy worm database" reveals strengths, weaknesses and gaps of test compound-based studies

Several biogerontology databases exist that focus on genetic or gene expression data linked to health as well as survival, subsequent to compound treatments or genetic manipulations in animal models. However, none of these has yet collected experimental results of compound-related health changes. Since quality of life is often regarded as more valuable than length of life, we aim to fill this gap with the “Healthy Worm Database” (http://healthy-worm-database.eu). Literature describing health-related compound studies in the aging model Caenorhabditis elegans was screened, and data for 440 compounds collected. The database considers 189 publications describing 89 different phenotypes measured in 2995 different conditions. Besides enabling a targeted search for promising compounds for further investigations, this database also offers insights into the research field of studies on healthy aging based on a frequently used model organism. Some weaknesses of C. elegans-based aging studies, like underrepresented phenotypes, especially concerning cognitive functions, as well as the convenience-based use of young worms as the starting point for compound treatment or phenotype measurement are discussed. In conclusion, the database provides an anchor for the search for compounds affecting health, with a link to public databases, and it further highlights some potential shortcomings in current aging research.

Growth hormone and aging

Growth hormone (GH) actions impact growth, metabolism, and body composition and have been associated with aging and longevity. Lack of GH results in slower growth, delayed maturation, and reduced body size and can lead to delayed aging, increased healthspan, and a remarkable extension of longevity. Adult body size, which is a GH-dependent trait, has a negative association with longevity in several mammalian species. Mechanistic links between GH and aging include evolutionarily conserved insulin/insulin-like growth factors and mechanistic target of rapamycin signaling pathways in accordance with long-suspected trade-offs between anabolic/growth processes and longevity. Height and the rate and regulation of GH secretion have been related to human aging, but longevity is not extended in humans with syndromes of GH deficiency or resistance. However, the risk of age-related chronic disease is reduced in individuals affected by these syndromes and various indices of increased healthspan have been reported.

Hypothalamic gene transfer of BDNF promotes healthy aging

The aging process and age-related diseases all involve metabolic decline and impaired ability to cope with adversity. Environmental enrichment (EE)-a housing environment which recapitulates aspects of active lifestyle-exerts a wide range of health benefits in laboratory rodents. Brain-derived neurotrophic factor (BDNF) in the hypothalamus orchestrates autonomic and neuroendocrine processes, serving as one key brain mediator of EE-induced resistance to obesity, cancer, and autoimmunity. Recombinant adeno-associated virus (AAV)-mediated hypothalamic BDNF gene transfer alleviates obesity, diabetes, and metabolic syndromes in both diet-induced and genetic models. One recent study by our lab demonstrates the efficacy and safety of a built-in autoregulatory system to control transgene BDNF expression, mimicking the body's natural feedback systems in middle-age mice. Twelve-month old mice were treated with autoregulatory BDNF vector and monitored for 7months. BDNF gene transfer prevented age-associated metabolic decline by: reducing adiposity, preventing the decline of brown fat activity, increasing adiponectin while reducing leptin and insulin in circulation, improving glucose tolerance, increasing energy expenditure, alleviating hepatic steatosis, and suppressing inflammatory genes in the hypothalamus and adipose tissues. Furthermore, BDNF treatment reduced anxiety-like and depression-like behaviors. This chapter summarizes this work and discusses potential roles that hypothalamic BDNF might play in promoting healthy aging.

Intrapopulation analysis of longitudinal lifespan in Caenorhabditis elegans identifies W09D10.4 as a novel AMPK-associated healthspan shortening factor

Caenorhabditis elegans is a model organism widely used for longevity studies. Current advances have been made in the methods that allow automated monitoring of C. elegans behavior. However, ordinary manual assays as well as automated methods have yet to achieve qualitative whole-life analysis of C. elegans longevity based on intrapopulation variation. Here, we utilized live-cell analysis system to determine the parameters of nematode lifespans. Image-based superposition method enabled to determine not only frailty in worms, but also to measure individual and longitudinal lifespan, healthspan, and frailspan. Notably, k-means clustering via principal component analysis revealed four clusters with distinct longevity patterns in wild-type C. elegans. Physiological relevance of clustering was confirmed by assays with pharmacological and/or genetic manipulation of AMP-activated protein kinase (AMPK), a crucial regulator of healthspan. Finally, we focused on W09D10.4 among the possible regulators extracted by integrative expression analysis with existing data sets. Importantly, W09D10.4 knockdown increased the high-healthspan populations only in the presence of AMPK, suggesting that W09D10.4 is a novel AMPK-associated healthspan shortening factor in C. elegans. Overall, the study establishes a novel platform of longitudinal lifespan in C. elegans, which is user-friendly, and may be a useful pharmacological tool to identify healthspan modulatory factors.

Repurposing drugs to fight aging: The difficult path from bench to bedside

The steady rise in life expectancy occurred across all developed countries during the last century. This demographic trend is, however, not accompanied by the same healthspan extension. This is since aging is the main risk factor for all age-associated pathological conditions. Therefore, slowing the rate of aging is suggested to be more efficient in preventing or delaying age-related diseases than treat them one by one, which is the common approach in a current pharmacological disease-oriented paradigm. To date, a variety of medications designed to treat particular pathological conditions have been shown to exhibit pro-longevity effects in different experimental models. Among them, there are many commonly used prescription and over-the-counter pharmaceuticals such as metformin, rapamycin, aspirin, statins, melatonin, vitamin antioxidants, etc. All of them are being increasingly investigated in preclinical and clinical trials with the aim of determine whether they have potential for extension of human healthspan. The results from these trials are frequently inconclusive and fall short of initial expectations, suggesting that innovative research ideas and additional translational steps are required to overcome obstacles for implementation of such approaches in clinical practice. In this review, recent advances and challenges in the field of repurposing widely used conventional pharmaceuticals to target the aging process are summarized and discussed.

Calorie restriction for enhanced longevity: The role of novel dietary strategies in the present obesogenic environment

Calorie restriction (CR) is a potent modulator of longevity in multiple species. A growing body of evidence shows that sustained periods of CR without malnutrition improves risk factors involved in the pathophysiology of type 2 diabetes, cardiovascular diseases, cancer, and neurological disorders in humans. Innovative dietary strategies such as intermittent fasting and protein restriction have recently emerged as alternative approaches that improve markers of aging. Some of these newer strategies might provide benefits for healthy aging with little to no CR and therefore, compared to traditional CR, may be easier to follow. Further to providing an update of CR studies in humans, the present narrative review appraises the influence of these contemporary dietary strategies on mechanisms posited to drive CR-induced longevity in humans, including those involving energy metabolism, oxidative damage, inflammation, glucose homeostasis, and functional changes in the neuroendocrine systems. The review also discusses the utilization of these diets for populations in the current obesogenic environment, and comments on whether current research can inform an optimal diet that attenuates aging, can be easily followed, and promises to improve longevity in humans.

Innovations in Geroscience to enhance mobility in older adults

Aging is the primary risk factor for functional decline; thus, understanding and preventing disability among older adults has emerged as an important public health challenge of the 21st century. The science of gerontology - or geroscience - has the practical purpose of "adding life to the years." The overall goal of geroscience is to increase healthspan, which refers to extending the portion of the lifespan in which the individual experiences enjoyment, satisfaction, and wellness. An important facet of this goal is preserving mobility, defined as the ability to move independently. Despite this clear purpose, this has proven to be a challenging endeavor as mobility and function in later life are influenced by a complex interaction of factors across multiple domains. Moreover, findings over the past decade have highlighted the complexity of walking and how targeting multiple systems, including the brain and sensory organs, as well as the environment in which a person lives, can have a dramatic effect on an older person's mobility and function. For these reasons, behavioral interventions that incorporate complex walking tasks and other activities of daily living appear to be especially helpful for improving mobility function. Other pharmaceutical interventions, such as oxytocin, and complementary and alternative interventions, such as massage therapy, may enhance physical function both through direct effects on biological mechanisms related to mobility, as well as indirectly through modulation of cognitive and socioemotional processes. Thus, the purpose of the present review is to describe evolving interventional approaches to enhance mobility and maintain healthspan in the growing population of older adults in the United States and countries throughout the world. Such interventions are likely to be greatly assisted by technological advances and the widespread adoption of virtual communications during and after the COVID-19 era.

Measuring health promotion: translating science into policy

Commonly, it is the end of life when our health is deteriorating, that many will make drastic lifestyle changes to improve their quality of life. However, it is increasingly recognized that bringing good health-promoting behaviors into practice as early in life as possible has the most significant impact across the maximal healthspan. The WHO has brought clarity to health promotion over the last fifteen years, always centering on language relating to a process of enabling people to increase control over, and to improve, their physical, mental and social health. A good healthspan is not just freedom from morbidity and mortality, it is that joie de vivre ("joy of living") that should accompany every day of our lifespan. Therefore, health promotion includes not only the health sector, but also needs individual commitment to achieve that target of a healthspan aligned with the lifespan. This paper explores health promotion and health literacy, and how to design appropriate nutritional studies to characterize contributors to a positive health outcome, the role the human microbiome plays in promoting health and addressing and alleviating morbidity and diseases, and finally how to characterize phenotypic flexibility and a physiologic resilience that we must maintain as our structural and functional systems are bombarded with the insults and perturbations of life.

From lifespan to healthspan: the role of nutrition in healthy ageing

Across the globe, there has been a marked increase in longevity, but significant inequalities remain. These are exacerbated by inadequate access to proper nutrition and health care services and to reliable information to make the decisions related to nutrition and health care. Many in economically developing as well as developed societies are plagued with the double-burden of energy excess and undernutrition. This has resulted in mental and physical deterioration, increased non-communicable disease rates, lost productivity, increased medical costs and reduced quality of life. While adequate nutrition is fundamental to good health at all stages of the life course, the impact of diet on prolonging good quality of life during ageing remains unclear. For progress to continue, there is need for new and/or innovative approaches to promoting health as individuals age, as well as qualitative and quantitative biomarkers and other accepted tools that can measure improvements in physiological integrity throughout life. A framework for progress has been proposed by the World Health Organization in their Global Strategy and Action Plan on Ageing and Health. Here, we focused on the impact of nutrition within this framework, which takes a broad, person-centred emphasis on healthy ageing, stressing the need to better understand each individual's intrinsic capacity, their functional abilities at various life stages, and the impact of their mental, and physical health, as well as the environments they inhabit.

Differential Effects of Rapamycin and Metformin in Combination With Rapamycin on Mechanisms of Proteostasis in Cultured Skeletal Myotubes

mTOR inhibition extends life span in multiple organisms. In mice, when metformin treatment (Met) is added to the mTOR inhibitor rapamycin (Rap), median and maximal life span is extended to a greater degree than with Rap or Met alone. Treatments that extend life span often maintain proteostasis. However, it is less clear how individual tissues, such as skeletal muscle, maintain proteostasis with life span-extending treatments. In C2C12 myotubes, we used deuterium oxide (D2O) to directly measure two primary determinants of proteostasis, protein synthesis, and degradation rates, with Rap or Met+Rap treatments. We accounted for the independent effects of cell growth and loss, and isolated the contribution of autophagy and mitochondrial fission to obtain a comprehensive assessment of protein turnover. Compared with control, both Rap and Met+Rap treatments lowered mitochondrial protein synthesis rates (p < .001) and slowed cellular proliferation (p < .01). These changes resulted in greater activation of mechanisms promoting proteostasis for Rap, but not Met+Rap. Compared with control, both Rap and Met+Rap slowed protein breakdown. Autophagy and mitochondrial fission differentially influenced the proteostatic effects of Rap and Met+Rap in C2C12 myotubes. In conclusion, we demonstrate that Met+Rap did not increase protein turnover and that these treatments do not seem to promote proteostasis through increased autophagy.