Impact of caloric restriction on health and survival in rhesus monkeys from the NIA study. Nature. 2012;489:318-321. [PMID: 22932268 DOI: 10.1038/nature11432]

Summary and Assessment of Studies on Cardiac Aging in Nonhuman Primates

Nonhuman primates (NHP) are important translational models for cardiac aging. To assess progress in this research area and to provide a reference for other investigators, we identified papers indexed in PubMed to determine what species, ages, outcomes, treatments, and approaches have been studied. Since 1983, 33 studies of cardiac aging in NHP have been published. Of these, 27 used species of macaque, 6 baboon, 1 vervet, 1 orangutan, and 1 marmoset (some studies were multispecies). Common research approaches were echocardiography, ECG, and histology of the left ventricle. Only 10 studies performed sex-based analyses. The average age of the oldest macaque studied was 26 y. The reported mean lifespan of macaques in captivity is around 30 y. The age of the oldest baboon studied was 24 y. Baboons in captivity are reported to live on average to 21 y. Twelve studies took a "life course" approach, studying animals of a wide range of ages from less than or equal to 10 y through the late teens to thirties, and employing analyses designed to show change over time. Keeping NHP into old age is a major challenge for biomedical research. The ideal design is to start monitoring in early life and to track how cardiac structure and function change with age. Important issues for future research are an increased focus on life-course approaches, investment in existing life-course NHP cohorts, better reporting of study sample characteristics, more molecular studies to identify genetic risk factors and mechanisms, attention to sex as a biological variable, a move away from descriptive reports to mechanistic studies, development of biomarkers to predict disease risk, and exploration of interventions that are implemented early in life to prevent or delay age-related disease later in life. Reducing exposure to early life adversity, identifying early-life biomarkers of aging and age-related disease, and early treatment can contribute to longer health span.

Epidemiological and genetic overlap among biological aging clocks: New challenges in biogerontology

Estimators of biological age (BA) - defined as the hypothetical underlying age of an organism - have attracted more and more attention in the last years, especially after the advent of new algorithms based on machine learning and genetic markers. While different aging clocks reportedly predict mortality in the general population, very little is known on their overlap. Here we review the evidence reported so far to support the existence of a partial overlap among different BA acceleration estimators, both from an epidemiological and a genetic perspective. On the epidemiological side, we review evidence supporting shared and independent influence on mortality risk of different aging clocks - including telomere length, brain, blood and epigenetic aging - and provide an overview of how an important exposure like diet may affect the different aging systems. On the genetic side, we apply linkage disequilibrium score regression analyses to support the existence of partly shared genomic overlap among these aging clocks. Through multivariate analysis of published genetic associations with these clocks, we also identified the most associated variants, genes, and pathways, which may affect common mechanisms underlying biological aging of different systems within the body. Based on our analyses, the most implicated pathways were involved in inflammation, lipid and carbohydrate metabolism, suggesting them as potential molecular targets for future anti-aging interventions. Overall, this review is meant as a contribution to the knowledge on the overlap of aging clocks, trying to clarify their shared biological basis and epidemiological implications.

Effect of lactate administration on mouse skeletal muscle under calorie restriction

Calorie restriction (CR) involves a reductions of calorie intake without altering the nutritional balance, and has many beneficial effects, such as improving oxidative metabolism and extending lifespan. However, CR decreases in skeletal muscle mass and fat mass in correlation with the reduction in food intake. Lactate is known to have potential as a signaling molecule rather than a metabolite during exercise. In this study, we examined the effects of the combination of caloric restriction and lactate administration on skeletal muscle adaptation in order to elucidate a novel role of lactate. We first demonstrated that daily lactate administration (equivalent to 1 g/kg of body weight) for 2 weeks suppressed CR-induced muscle atrophy by activating mammalian/mechanistic target of rapamycin (mTOR) signaling, a muscle protein synthesis pathway, and inhibited autophagy-induced muscle degradation. Next, we found that lactate administration under calorie restriction enhanced mitochondrial enzyme activity (citrate synthase and succinate dehydrogenase) and the expression of oxidative phosphorylation (OXPHOS) protein expression. Our results suggest that lactate administration under caloric restriction not only suppresses muscle atrophy but also improves mitochondrial function.

Evaluating the beneficial effects of dietary restrictions: A framework for precision nutrigeroscience

Dietary restriction (DR) has long been viewed as the most robust nongenetic means to extend lifespan and healthspan. Many aging-associated mechanisms are nutrient responsive, but despite the ubiquitous functions of these pathways, the benefits of DR often vary among individuals and even among tissues within an individual, challenging the aging research field. Furthermore, it is often assumed that lifespan interventions like DR will also extend healthspan, which is thus often ignored in aging studies. In this review, we provide an overview of DR as an intervention and discuss the mechanisms by which it affects lifespan and various healthspan measures. We also review studies that demonstrate exceptions to the standing paradigm of DR being beneficial, thus raising new questions that future studies must address. We detail critical factors for the proposed field of precision nutrigeroscience, which would utilize individualized treatments and predict outcomes using biomarkers based on genotype, sex, tissue, and age.

Intermittent fasting in the prevention and treatment of cancer

Chronic caloric restriction (CR) has powerful anticarcinogenic actions in both preclinical and clinical studies but may be difficult to sustain. As an alternative to CR, there has been growing interest in intermittent fasting (IF) in both the scientific and lay community as a result of promising study results, mainly in experimental animal models. According to a survey by the International Food Information Council Foundation, IF has become the most popular diet in the last year, and patients with cancer are seeking advice from oncologists about its beneficial effects for cancer prevention and treatment. However, as discussed in this review, results from IF studies in rodents are controversial and suggest potential detrimental effects in certain oncologic conditions. The effects of IF on human cancer incidence and prognosis remain unknown because of a lack of high-quality randomized clinical trials. Preliminary studies suggest that prolonged fasting in some patients who have cancer is safe and potentially capable of decreasing chemotherapy-related toxicity and tumor growth. However, because additional trials are needed to elucidate the risks and benefits of fasting for patients with cancer, the authors would not currently recommend patients undergoing active cancer treatment partake in IF outside the context of a clinical trial. IF may be considered in adults seeking cancer-prevention benefits through means of weight management, but whether IF itself affects cancer-related metabolic and molecular pathways remains unanswered.

Reevaluation of the effect of dietary restriction on different recombinant inbred lines of male and female mice

Dietary restriction (DR) was reported to either have no effect or reduce the lifespan of the majority of the 41‐recombinant inbred (RI) lines studied by Liao et al. (Aging Cell, 2010, 9, 92). In an appropriately power longevity study (n > 30 mice/group), we measured the lifespan of the four RI lines (115‐RI, 97‐RI, 98‐RI, and 107‐RI) that were reported to have the greatest decrease in lifespan when fed 40% DR. DR increased the median lifespan of female RI‐115, 97‐RI, and 107‐RI mice and male 115‐RI mice. DR had little effect (<4%) on the median lifespan of female and male 98‐RI mice and male 97‐RI mice and reduced the lifespan of male 107‐RI mice over 20%. While our study was unable to replicate the effect of DR on the lifespan of the RI mice (except male 107‐RI mice) reported by Liao et al. (Aging Cell, 2010, 9, 92), we found that the genotype of a mouse had a major impact on the effect of DR on lifespan, with the effect of DR ranging from a 50% increase to a 22% decrease in median lifespan. No correlation was observed between the changes in either body composition or glucose tolerance induced by DR and the changes observed in lifespan of the four RI lines of male and female mice. These four RI lines of mice give the research community a unique resource where investigators for the first time can study the anti‐aging mechanism of DR by comparing mice in which DR increases lifespan to mice where DR has either no effect or reduces lifespan.

Overview of age-related changes in psychomotor and cognitive functions in a prosimian primate, the gray mouse lemur (Microcebus murinus): Recent advances in risk factors and antiaging interventions

Aging is not homogeneous in humans and the determinants leading to differences between subjects are not fully understood. Impaired glucose homeostasis is a major risk factor for cognitive decline in middle-aged humans, pointing at the existence of early markers of unhealthy aging. The gray mouse lemur (Microcebus murinus), a small lemuriform Malagasy primate, shows relatively slow aging with decreased psychomotor capacities at middle-age (around 5-year old). In some cases (∼10%), it spontaneously leads to pathological aging. In this case, some age-related deficits, such as severe cognitive decline, brain atrophy, amyloidosis, and glucoregulatory imbalance are congruent with what is observed in humans. In the present review, we inventory the changes occurring in psychomotor and cognitive functions during healthy and pathological aging in mouse lemur. It includes a summary of the cerebral, metabolic, and cellular alterations that occur during aging and their relation to cognitive decline. As nutrition is one of the major nonpharmacological antiaging strategies with major potential effects on cognitive performances, we also discuss its role in brain functions and cognitive decline in this species. We show that the overall approach of aging studies in the gray mouse lemur offers promising ways of investigation for understanding, prevention, and treatments of pathological aging in humans.

Rodent diet aids and the fallacy of caloric restriction

Understanding the molecular mechanisms of normal aging is a prerequisite to significantly improving human health span. Caloric restriction (CR) can delay aging and has served as a yardstick to evaluate interventions extending life span. However, mice given unlimited access to food suffer severe obesity. Health gains from CR depend on control mice being sufficiently overweight and less obese mouse strains benefit far less from CR. Pharmacologic interventions that increase life span, including resveratrol, rapamycin, nicotinamide mononucleotide and metformin, also reduce body weight. In primates, CR does not delay aging unless the control group is eating enough to suffer from obesity-related disease. Human survival is optimal at a body mass index achievable without CR, and the above interventions are merely diet aids that shouldn't slow aging in healthy weight individuals. CR in humans of optimal weight can safely be declared useless, since there is overwhelming evidence that hunger, underweight and starvation reduce fitness, survival, and quality of life. Against an obese control, CR does, however, truly delay aging through a mechanism laid out in the following tumor suppression theory of aging.

The tumor suppression theory of aging

Despite continued increases in human life expectancy, the factors determining the rate of human biological aging remain unknown. Without understanding the molecular mechanisms underlying aging, efforts to prevent aging are unlikely to succeed. The tumor suppression theory of aging introduced here proposes somatic mutation as the proximal cause of aging, but postulates that oncogenic transformation and clonal expansion, not functional impairment, are the relevant consequences of somatic mutation. Obesity and caloric restriction accelerate and decelerate aging due to their effect on cell proliferation, during which most mutations arise. Most phenotypes of aging are merely tumor-suppressive mechanisms that evolved to limit malignant growth, the dominant age-related cause of death in early and middle life. Cancer limits life span for most long-lived mammals, a phenomenon known as Peto's paradox. Its conservation across species demonstrates that mutation is a fundamental but hard limit on mammalian longevity. Cell senescence and apoptosis and differentiation induced by oncogenes, telomere shortening or DNA damage evolved as a second line of defense to limit the tumorigenic potential of clonally expanding cells, but accumulating senescent cells, senescence-associated secretory phenotypes and stem cell exhaustion eventually cause tissue dysfunction and the majority, if not most, phenotypes of aging.

A comprehensive overview of the complex relationship between epigenetics, bioactive components, cancer, and aging

Among age-related diseases, the incidence of cancer increases significantly due to the overlap of some molecular pathways between cancer and aging. While the genetic influence on the human lifespan is estimated to be about 20-25%, epigenetic changes play an important role in modulating individual health status, aging. Aging and age-related conditions are processes that can be modified by both genetic, environmental factors, including dietary habits. Epigenetics is a new discipline has significant potential to be applied for the prevention, management of certain carcinomas and diseases. Epigenetic modifications may play an important role in disease occurrence and pathogenesis. Some nutritional components can be significantly effective in the prevention of breast, skin, esophagus, colorectal, prostate, pancreatic, lung cancers. It contains minerals, vitamins, and some bioactive components (curcumin, indole 3 carbinol, di-indolylmethane, sulforaphane, epigallocatechin-3-gallate, genistein, resveratrol, pterostilbene, apigenin, etc.) regulatory processes. However, compelling evidence suggests that dietary habits can manipulate the aging process and/or its consequences, have health benefits. Aging processes become complex when combined with the relational role of bioactive nutritional components on gene expression. In this review, the relationship between epigenetic processes caused by DNA methylylation, histone modification, non-coding m-RNA, and telomerase activity, the risk of aging and cancer is discussed.

DNA methylation age analysis of rapamycin in common marmosets

Human DNA methylation data have previously been used to develop highly accurate biomarkers of aging ("epigenetic clocks"). Subsequent studies demonstrate that similar epigenetic clocks can also be developed for mice and many other mammals. Here, we describe epigenetic clocks for common marmosets (Callithrix jacchus) based on novel DNA methylation data generated from highly conserved mammalian CpGs that were profiled using a custom Infinium array (HorvathMammalMethylChip40). From these, we developed and present here two epigenetic clocks for marmosets that are applicable to whole blood samples. We find that the human-marmoset clock for relative age exhibits moderately high age correlations in two other non-human primate species: vervet monkeys and rhesus macaques. In a separate cohort of marmosets, we tested whether intervention with rapamycin, a drug shown to extend lifespan in mice, would alter the epigenetic age of marmosets, as measured by the marmoset epigenetic clocks. These clocks did not detect significant effects of rapamycin on the epigenetic age of marmoset blood. The common marmoset stands out from other mammals in that it is not possible to build accurate estimators of sex based on DNA methylation data: the accuracy of a random forest predictor of sex (66%) was substantially lower than that observed for other mammals (which is close to 100%). Overall, the epigenetic clocks developed here for the common marmoset are expected to be useful for age estimation of wild-born animals and for anti-aging studies in this species.

Fasting drives the metabolic, molecular and geroprotective effects of a calorie-restricted diet in mice

Calorie restriction (CR) promotes healthy ageing in diverse species. Recently, it has been shown that fasting for a portion of each day has metabolic benefits and promotes lifespan. These findings complicate the interpretation of rodent CR studies, in which animals typically eat only once per day and rapidly consume their food, which collaterally imposes fasting. Here we show that a prolonged fast is necessary for key metabolic, molecular and geroprotective effects of a CR diet. Using a series of feeding regimens, we dissect the effects of calories and fasting, and proceed to demonstrate that fasting alone recapitulates many of the physiological and molecular effects of CR. Our results shed new light on how both when and how much we eat regulate metabolic health and longevity, and demonstrate that daily prolonged fasting, and not solely reduced caloric intake, is likely responsible for the metabolic and geroprotective benefits of a CR diet.

Substitution of Sugar-Sweetened Beverages for Other Beverages: Can It Be the Next Step Towards Healthy Aging?

PURPOSE OF REVIEW

With the prolongation of life expectancy, the gap between lifespan and "health span," the disease-free lifespan, has been widening due to the massive burden of age-related chronic diseases and research on healthy aging has been gaining momentum. A growing body of evidence suggests that diet is a strong determinant of healthy aging and consumption of sugar-sweetened beverages (SSB), a major source of added sugars, predicts poor health outcomes in the aging population, including cardiovascular disease, diabetes, and cancer. Evidence further supports a link between sugar-sweetened beverages-triggered pathological processes and biologic factors of aging, including inflammaging, oxidative stress, and alterations in intestinal microbiota. At present, substitution of sugar-sweetened beverages with healthier alternative beverage remains the most robust strategy to limit the deleterious effects of sugar-sweetened beverages on health worldwide and may help achieve healthy longevity. The purpose of this review is to provide an overview of mechanisms by which sugar-sweetened beverages consumption may impact the physiological aging process and how a simple intervention of beverage replacement may promote healthy aging.

RECENT FINDINGS

Recent findings indicate that SSB are associated with accelerated aging phenotype and activate various adverse biological processes such as chronic inflammation, oxidative stress, insulin resistance, and gut dysbiosis. Replacing SSB with healthier beverages may be a reasonable option to reduce the burden of chronic disease in the aging population and even prolong life and healthspan.

The Effects of Intermittent Fasting on Brain and Cognitive Function

The importance of diet and the gut-brain axis for brain health and cognitive function is increasingly acknowledged. Dietary interventions are tested for their potential to prevent and/or treat brain disorders. Intermittent fasting (IF), the abstinence or strong limitation of calories for 12 to 48 h, alternated with periods of regular food intake, has shown promising results on neurobiological health in animal models. In this review article, we discuss the potential benefits of IF on cognitive function and the possible effects on the prevention and progress of brain-related disorders in animals and humans. We do so by summarizing the effects of IF which through metabolic, cellular, and circadian mechanisms lead to anatomical and functional changes in the brain. Our review shows that there is no clear evidence of a positive short-term effect of IF on cognition in healthy subjects. Clinical studies show benefits of IF for epilepsy, Alzheimer’s disease, and multiple sclerosis on disease symptoms and progress. Findings from animal studies show mechanisms by which Parkinson’s disease, ischemic stroke, autism spectrum disorder, and mood and anxiety disorders could benefit from IF. Future research should disentangle whether positive effects of IF hold true regardless of age or the presence of obesity. Moreover, variations in fasting patterns, total caloric intake, and intake of specific nutrients may be relevant components of IF success. Longitudinal studies and randomized clinical trials (RCTs) will provide a window into the long-term effects of IF on the development and progress of brain-related diseases.

Calorie intake rather than food quantity consumed is the key factor for the anti-aging effect of calorie restriction

Although calorie restriction has been reported to extend lifespan in several organisms, animals subjected to calorie restriction consume not only fewer calories but also smaller quantities of food. Whether it is the overall restriction of calories or the coincidental reduction in the quantity of food consumed that mediates the anti-aging effects is unclear. Here, we subjected mice to five dietary interventions. We showed that both calorie and quantity restriction could improve early survival, but no maximum lifespan extension was observed in the mice fed isocaloric diet in which food quantity was reduced. Mice fed isoquant diet with fewer calories showed maximum lifespan extension and improved health among all the groups, suggesting that calorie intake rather than food quantity consumed is the key factor for the anti-aging effect of calorie restriction. Midlife liver gene expression correlations with lifespan revealed that calorie restriction raised fatty acid biosynthesis and metabolism and biosynthesis of amino acids but inhibited carbon metabolism, indicating different effects on fatty acid metabolism and carbohydrate metabolism. Our data illustrate the effects of calories and food quantity on the lifespan extension by calorie restriction and their potential mechanisms, which will provide guidance on the application of calorie restriction to humans.

Aging and Cancer: The Waning of Community Bonds

Cancer often arises in the context of an altered tissue landscape. We argue that a major contribution of aging towards increasing the risk of neoplastic disease is conveyed through effects on the microenvironment. It is now firmly established that aged tissues are prone to develop clones of altered cells, most of which are compatible with a normal histological appearance. Such increased clonogenic potential results in part from a generalized decrease in proliferative fitness, favoring the emergence of more competitive variant clones. However, specific cellular genotypes can emerge with reduced cooperative and integrative capacity, leading to disruption of tissue architecture and paving the way towards progression to overt neoplastic phenotypes.

Mechanisms of Caloric Restriction-Mediated Stress-Resistance in Acute Kidney Injury

Caloric restriction (CR)-mediated organ protection has been shown to be extremely efficient in rodent models of acute kidney injury (AKI). Limited understanding of the underlying mechanisms paired with a risk of malnourishment and feasibility problems has hindered the translation of this immense potential to the patient setting. In this mini-review, the current mechanistic concepts of CR-mediated stress-resistance as potential key targets for renal protection in AKI will be highlighted.

Beyond calorie restriction: aging as a biological target for nutrient therapies

Arguably, the most important discovery in the biology of aging to date was that simply reducing food intake extended life and improved many aspects of health in a diversity of animal species. The conventional wisdom that emerged from first 50 years of rodent food restriction studies included (1) that the longevity impact of restriction was greater the longer restriction was imposed, and (2) that restricting calories rather than any specific macronutrient was critical to its health and longevity benefits. However these assumptions began to crumble as more and more restriction research was performed on other species besides laboratory rodents. Recent investigations of flies, rodents, monkeys, and increasingly humans, has begun to parse how calorie restriction, protein restriction, intermittent fasting, and the temporal pattern of eating all impact the health benefits of food restriction. Fly research continues to inform, as it has repeatedly shown that genotype, age, sex, duration, and tempo restriction all affect the health impact. Ultimately, optimizing human diets will require a personalized approach using omics approaches.

The role of mTOR in age-related diseases

The ageing population is becoming a significant socio-economic issue. To address the expanding health gap, it is important to deepen our understanding of the mechanisms underlying ageing in various organisms at the single-cell level. The discovery of the antifungal, immunosuppressive, and anticancer drug rapamycin, which possesses the ability to extend the lifespan of several species, has prompted extensive research in the areas of cell metabolic regulation, development, and senescence. At the centre of this research is the mTOR pathway, with key roles in cell growth, proteosynthesis, ribosomal biogenesis, transcriptional regulation, glucose and lipid metabolism, and autophagy. Recently, it has become obvious that mTOR dysregulation is involved in several age-related diseases, such as cancer, neurodegenerative diseases, and type 2 diabetes mellitus. Additionally, mTOR hyperactivation affects the process of ageing per se. In this review, we provide an overview of recent insights into the mTOR signalling pathway, including its regulation and its influence on various hallmarks of ageing at the cellular level.

The Potential of Calorie Restriction and Calorie Restriction Mimetics in Delaying Aging: Focus on Experimental Models

Aging is a biological process determined by multiple cellular mechanisms, such as genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, and altered intercellular communication, that ultimately concur in the functional decline of the individual. The evidence that the old population is steadily increasing and will triplicate in the next 50 years, together with the fact the elderlies are more prone to develop pathologies such as cancer, diabetes, and degenerative disorders, stimulates an important effort in finding specific countermeasures. Calorie restriction (CR) has been demonstrated to modulate nutrient sensing mechanisms, inducing a better metabolic profile, enhanced stress resistance, reduced oxidative stress, and improved inflammatory response. Therefore, CR and CR-mimetics have been suggested as powerful means to slow aging and extend healthy life-span in experimental models and humans. Taking into consideration the difficulties and ethical issues in performing aging research and testing anti-aging interventions in humans, researchers initially need to work with experimental models. The present review reports the major experimental models utilized in the study of CR and CR-mimetics, highlighting their application in the laboratory routine, and their translation to human research.

Gastrodin extends the lifespan and protects against neurodegeneration in the Drosophila PINK1 model of Parkinson's disease

Gastrodin is the main bioactive ingredient of a famous Chinese herb Rhizoma Gastrodiae. Many studies have reported that gastrodin has antioxidative and neuroprotective effects, although its effect on longevity and the mechanism of neuroprotection have not been well studied. Here, we use Drosophila melanogaster as a model to investigate the longevity and neuroprotective effects of gastrodin. Gastrodin significantly extended the lifespan, increased the climbing ability, enhanced the resistance to oxidative stress, increased the enzyme activities of superoxide dismutase (SOD) and catalase (CAT), and promoted the expression of anti-oxidative genes in old flies. The food intake, reproduction and starvation resistance were not affected in flies treated with gastrodin. Moreover, gastrodin delayed the onset of Parkinson-like phenotypes in Pink1^B9 mutant flies, including the prolongation of the lifespan, rescue of the climbing ability, rescue of the progressive loss of a cluster of dopaminergic neurons in the protocerebral posterial lateral 1 region, and increase of the dopamine content in the brain. Gastrodin did not ameliorate the tau-induced neurobehavioral deficits in the fly AD model of taupathy. Together, these results indicate that gastrodin could prolong the lifespan by regulating the antioxidant ability, and protect against neurodegeneration in the Pink1^B9 model of PD. This suggests that gastrodin can be considered as an ideal therapeutic candidate for drug development towards anti-aging.

miR-125-chinmo pathway regulates dietary restriction-dependent enhancement of lifespan in Drosophila

Dietary restriction (DR) extends healthy lifespan in diverse species. Age and nutrient-related changes in the abundance of microRNAs (miRNAs) and their processing factors have been linked to organismal longevity. However, the mechanisms by which they modulate lifespan and the tissue-specific role of miRNA-mediated networks in DR-dependent enhancement of lifespan remains largely unexplored. We show that two neuronally enriched and highly conserved microRNAs, miR-125 and let-7 mediate the DR response in Drosophila melanogaster. Functional characterization of miR-125 demonstrates its role in neurons while its target chinmo acts both in neurons and the fat body to modulate fat metabolism and longevity. Proteomic analysis revealed that Chinmo exerts its DR effects by regulating the expression of FATP, CG2017, CG9577, CG17554, CG5009, CG8778, CG9527, and FASN1. Our findings identify miR-125 as a conserved effector of the DR pathway and open the avenue for this small RNA molecule and its downstream effectors to be considered as potential drug candidates for the treatment of late-onset diseases and biomarkers for healthy aging in humans.

Effect of intermittent and continuous caloric restriction on Sirtuin1 concentration depends on sex and body mass index

BACKGROUND & AIMS

The favorable effect of caloric restriction (CR) on health span is well known and partly mediated by the sirtuin system. Sirtuin1, a regulator of energy homeostasis in response to nutrient availability, is activated by CR. We therefore investigated effects of two different CR regimens on Sirtuin1 concentrations.

METHODS & RESULTS

The study included 112 abdominally obese subjects, randomized to intermittent or continuous CR for 1 year. Blood samples and anthropometric measures were collected at baseline and after 12 months. Sirtuin1 concentrations were measured by ELISA. Sirtuin1 correlated significantly to BMI at baseline (r = .232, p = 0.019). Mean reduction in body-weight was 8.0 and 9.0 kg after intermittent and continuous CR, respectively. After 1 year, no significant between-group differences in Sirtuin1 levels were observed according to regimen (p = 0.98) and sex (p = 0.41). An increase in median Sirtuin1 concentrations (pg/mL) [25, 75 percentiles] from baseline was observed after intermittent CR in the total population (884 [624, 1285] vs.762 [530, 1135]; p = 0.041), most marked in men (820 [623, 1250] vs. 633 [524, 926]; p = 0.016). Improvement in BMI after 1 year correlated to Sirtuin1 changes, but varied according to sex. In women, Spearman's rho = .298, p = 0.034, with stronger correlation in the intermittent CR group (r = .424, p = 0.049). In men, there was an inverse relation to Sirtuin1 changes, only in the intermittent CR group (r = -.396, p = 0.045).

CONCLUSIONS

Effects on Sirtuin1 concentrations after 1 year of CR are sex and BMI-related. Intermittent CR regimen affected Sirtuin1 to a stronger extent than continuous CR, suggesting individualized dietary intervention.

Modeling transcriptomic age using knowledge-primed artificial neural networks

The development of 'age clocks', machine learning models predicting age from biological data, has been a major milestone in the search for reliable markers of biological age and has since become an invaluable tool in aging research. However, beyond their unquestionable utility, current clocks offer little insight into the molecular biological processes driving aging, and their inner workings often remain non-transparent. Here we propose a new type of age clock, one that couples predictivity with interpretability of the underlying biology, achieved through the incorporation of prior knowledge into the model design. The clock, an artificial neural network constructed according to well-described biological pathways, allows the prediction of age from gene expression data of skin tissue with high accuracy, while at the same time capturing and revealing aging states of the pathways driving the prediction. The model recapitulates known associations of aging gene knockdowns in simulation experiments and demonstrates its utility in deciphering the main pathways by which accelerated aging conditions such as Hutchinson-Gilford progeria syndrome, as well as pro-longevity interventions like caloric restriction, exert their effects.

Modulation of Endocannabinoids by Caloric Restriction Is Conserved in Mice but Is Not Required for Protection from Acute Kidney Injury

Acute kidney injury (AKI) is a frequent and critical complication in the clinical setting. In rodents, AKI can be effectively prevented through caloric restriction (CR), which has also been shown to increase lifespan in many species. In Caenorhabditis elegans (C. elegans), longevity studies revealed that a marked CR-induced reduction of endocannabinoids may be a key mechanism. Thus, we hypothesized that regulation of endocannabinoids, particularly arachidonoyl ethanolamide (AEA), might also play a role in CR-mediated protection from renal ischemia-reperfusion injury (IRI) in mammals including humans. In male C57Bl6J mice, CR significantly reduced renal IRI and led to a significant decrease of AEA. Supplementation of AEA to near-normal serum concentrations by repetitive intraperitoneal administration in CR mice, however, did not abrogate the protective effect of CR. We also analyzed serum samples taken before and after CR from patients of three different pilot trials of dietary interventions. In contrast to mice and C. elegans, we detected an increase of AEA. We conclude that endocannabinoid levels in mice are modulated by CR, but CR-mediated renal protection does not depend on this effect. Moreover, our results indicate that modulation of endocannabinoids by CR in humans may differ fundamentally from the effects in animal models.

The old guard: Age-related changes in microglia and their consequences

Among all major organs, the brain is one of the most susceptible to the inexorable effects of aging. Throughout the last decades, several studies in human cohorts and animal models have revealed a plethora of age-related changes in the brain, including reduced neurogenesis, oxidative damage, mitochondrial dysfunction and cell senescence. As the main immune effectors and first responders of the nervous tissue, microglia are at the center of these events. These cells experience irrevocable changes as a result from cumulative exposure to environmental triggers, such as stress, infection and metabolic dysregulation. The age-related immunosenescent phenotype acquired by microglia is characterized by profound modifications in their transcriptomic profile, secretome, morphology and phagocytic activity, which compromise both their housekeeping and defensive functions. As a result, aged microglia are no longer capable of establishing effective immune responses and sustaining normal synaptic activity, directly contributing to age-associated cognitive decline and neurodegeneration. This review discusses how lifestyle and environmental factors drive microglia dysfunction at the molecular and functional level, also highlighting possible interventions to reverse aging-associated damage to the nervous and immune systems.

Importance of circadian timing for aging and longevity

Dietary restriction (DR) decreases body weight, improves health, and extends lifespan. DR can be achieved by controlling how much and/or when food is provided, as well as by adjusting nutritional composition. Because these factors are often combined during DR, it is unclear which are necessary for beneficial effects. Several drugs have been utilized that target nutrient-sensing gene pathways, many of which change expression throughout the day, suggesting that the timing of drug administration is critical. Here, we discuss how dietary and pharmacological interventions promote a healthy lifespan by influencing energy intake and circadian rhythms.

Circadian clocks link physiologic processes to environmental conditions and a mismatch between internal and external rhythms has negative effects on organismal health. In this review, the authors discuss the interactions between circadian clocks and dietary interventions targeted to promote healthy aging.

Taurine Improves Lipid Metabolism and Increases Resistance to Oxidative Stress

Calorie restriction (CR) by 30-40% decreases morbidity of age-related diseases and prolongs the lifespan of various laboratory animal species. Taurine (2-aminoethanesulfonic acid) is an important nutrient for lipid metabolism as it conjugates bile acids. Here, we investigated how taurine supplementation induces effects similar to the CR beneficial effects. Sprague Dawley rats were fed a diet containing different taurine concentrations (0, 0.5, 1.0, 3.0, 5.0%) to analyze the effects on growth, blood, and hepatic parameters. Rats fed a 5% taurine-supplemented diet showed a significant decrease in visceral fat weight, compared with control rats. Moreover, there were significant decreases in the serum total cholesterol, hepatic cholesterol and triglyceride concentrations in the taurine-supplemented groups compared with the control group in a dose-dependent manner. These results were associated with decreased mRNA expression of fatty acid synthase, and increased mRNA expression of carnitine palmitoyltransferase 1α. C57BL/6 mice were fed a 5.0% taurine-supplemented diet, and their response to 3-nitropropionic acid-induced oxidative stress was analyzed. The rate of weight loss due to oxidative stress decreased and the survival rate significantly increased in the taurine-supplemented groups compared with the control group. Finally, cells were treated with 100 μM taurine and their resistance to UV-induced oxidative stress was analyzed. We found that the p53-Chk1 pathway was less activated in taurine-treated cells compared with control cells. Furthermore, damage to cells evaluated by oxidative stress indicators revealed a reduction in oxidative damage with taurine treatment. These findings suggest that taurine partially acts as a CR mimetic.

Energy Balance and Risk of Mortality in Spanish Older Adults

Clinical data on the direct health effects of energy deficit or surplus beyond its impact on body weight are scarce. We aimed to assess the association with all-cause, cardiovascular and cancer mortality of (1) sustained energy deficit or surplus, calculated according to each individual’s en-ergy intake (EI) and theoretical energy expenditure (TEE), and (2) mid-term change in total EI in a prospective study. In 7119 participants in the PREDIMED Study (PREvención con DIeta MEDi-terránea) with a mean age of 67 years, energy intake was derived from a 137-item food frequency questionnaire. TEE was calculated as a function of age, sex, height, body weight and physical ac-tivity. The main exposure was the proportion of energy requirement covered by energy intake, cumulative throughout the follow-up. The secondary exposure was the change in energy intake from baseline. Cox proportional hazard models were used to estimate hazard ratios and 95% con-fidence intervals for all-cause, cardiovascular and cancer mortality. Over a median follow-up of 4.8 years, there were 239 deaths (excluding the first 2 years). An energy intake exceeding energy needs was associated with an increase in mortality risk (continuous HR_{10% over energy needs} = 1.10; 95% CI 1.02, 1.18), driven by cardiovascular death (HR = 1.26; 95% CI 1.11, 1.43). However, consum-ing energy below estimated needs was not associated with a lower risk. Increments over time in energy intake were associated with greater all-cause mortality (HR_{10% increase} = 1.09; 95% CI 1.02, 1.17). However, there was no evidence that a substantial negative change in energy intake would reduce mortality risk. To conclude, in an older Mediterranean cohort, energy surplus or increase over a 5-year period was associated with greater risk of mortality, particularly cardiovascular mortality. Energy deficit, or reduction in energy intake over time were not associated with mortal-ity risk.

Beyond weight loss: current perspectives on the impact of calorie restriction on healthspan and lifespan

Introduction: Changes to mental, physical, and physiological functions drive the complex processes underlying the variable progression of human aging. Nutritional interventions are one of the most promising non-pharmacological therapeutics to attenuate aging in humans. This narrative review aims to describe the implications of moderate and prolonged calorie restriction (CR) in healthy adults without obesity that occur beyond weight loss.Areas covered: Findings from CR studies, such as the CALERIE (Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy) trials, the most rigorous trials to date examining a prolonged 25% CR, are described. The main areas covered include; changes to anthropometrics, energy metabolism, cardiometabolic health, inflammation and immune function, physical fitness, health behaviors, and mental health in response to weight loss (1-year) and weight loss maintenance (2-year).Expert opinion: CR presents a novel and effective therapeutic approach for improving healthspan and biomarkers of lifespan. To date, scientific evidence suggests that continued CR, under medical supervision, is accompanied with persistent and beneficial effects on health outcomes independent of weight loss. Mechanisms are yet to be fully elucidated, and novel dietary approaches that may similarly attenuate aging-related conditions should be explored and compared to traditional CR.

Dietary nutrition for neurological disease therapy: Current status and future directions

Adequate food intake and relative abundance of dietary nutrients have undisputed effects on the brain function. There is now substantial evidence that dietary nutrition aids in the prevention and remediation of neurologic symptoms in diverse pathological conditions. The newly described influences of dietary factors on the alterations of mitochondrial dysfunction, epigenetic modification and neuroinflammation are important mechanisms that are responsible for the action of nutrients on the brain health. In this review, we discuss the state of evidence supporting that distinct dietary interventions including dietary supplement and dietary restriction have the ability to tackle neurological disorders using Alzheimer's disease, Parkinson's disease, stroke, epilepsy, traumatic brain injury, amyotrophic lateral sclerosis, Huntington's disease and multiple sclerosis as examples. Additionally, it is also highlighting that diverse potential mechanisms such as metabolic control, epigenetic modification, neuroinflammation and gut-brain axis are of utmost importance for nutrient supply to the risk of neurologic condition and therapeutic response. Finally, we also highlight the novel concept that dietary nutrient intervention reshapes metabolism-epigenetics-immunity cycle to remediate brain dysfunction. Targeting metabolism-epigenetics-immunity network will delineate a new blueprint for combating neurological weaknesses.

The influence of fasting and caloric restriction on inflammation levels in humans: A protocol for systematic review and meta analysis

BACKGROUND

Fasting and caloric restriction have a potential means of anti-inflammatory, as they can decrease the level of systemic inflammation. Although encouraging results have been obtained in animal experiments, there is no consensus on whether these results are applicable to human. The objective of this systematic review and meta-analysis is to analyze the influence of fasting and caloric restriction on inflammation levels in humans.

METHODS

The systematic review and meta-analysis will be conducted in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The following eight databases will be searched:(The retrieval time is from the establishment of each database to December 2020): PubMed, the Cochrane Library, Embase, Web of Science, China National Knowledge infrastructure (CNKI), China Biology Medicine (CBM), Wan Fang Data, the Chinese Science and Technology Periodical Database (VIP). Relevant data will be performed by Revman 5.3 software provided (Cochrane Collaboration) and Stata 14.0 statistical software.

RESULTS

The results of this systematic review and meta-analysis will be published in a peer-reviewed journal.

CONCLUSIONS

This systematic review will provide evidence to judge the effectiveness of fasting and calorie restriction in human subjects, so as to provide a sound basis for future research and lifestyle promotion.

INPLASY REGISTRATION NUMBER

INPLASY202130026.

Healthy Aging-Nutrition Matters: Start Early and Screen Often

The amount of time spent in poor health at the end of life is increasing. This narrative review summarizes consistent evidence indicating that healthy dietary patterns and maintenance of a healthy weight in the years leading to old age are associated with broad prevention of all the archetypal diseases and impairments associated with aging including: noncommunicable diseases, sarcopenia, cognitive decline and dementia, osteoporosis, age-related macular degeneration, diabetic retinopathy, hearing loss, obstructive sleep apnea, urinary incontinence, and constipation. In addition, randomized clinical trials show that disease-specific nutrition interventions can attenuate progression-and in some cases effectively treat-many established aging-associated conditions. However, middle-aged and older adults are vulnerable to unhealthy dietary patterns, and typically consume diets with inadequate servings of healthy food groups and essential nutrients, along with an abundance of energy-dense but nutrient-weak foods that contribute to obesity. However, based on menu examples, diets that are nutrient-dense, plant-based, and with a moderately low glycemic load are better equipped to meet the nutritional needs of many older adults than current recommendations in US Dietary Guidelines. These summary findings indicate that healthy nutrition is more important for healthy aging than generally recognized. Improved public health messaging about nutrition and aging, combined with routine screening and medical referrals for age-related conditions that can be treated with a nutrition prescription, should form core components of a national nutrition roadmap to reduce the epidemic of unhealthy aging.

SIRT6 in Senescence and Aging-Related Cardiovascular Diseases

SIRT6 belongs to the nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylases and has established diverse roles in aging, metabolism and disease. Its function is similar to the Silent Information Regulator 2 (SIR2), which prolongs lifespan and regulates genomic stability, telomere integrity, transcription, and DNA repair. It has been demonstrated that increasing the sirtuin level through genetic manipulation extends the lifespan of yeast, nematodes and flies. Deficiency of SIRT6 induces chronic inflammation, autophagy disorder and telomere instability. Also, these cellular processes can lead to the occurrence and progression of cardiovascular diseases (CVDs), such as atherosclerosis, hypertrophic cardiomyopathy and heart failure. Herein, we discuss the implications of SIRT6 regulates multiple cellular processes in cell senescence and aging-related CVDs, and we summarize clinical application of SIRT6 agonists and possible therapeutic interventions in aging-related CVDs.

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.

Metabolic Reprogramming by Reduced Calorie Intake or Pharmacological Caloric Restriction Mimetics for Improved Cancer Immunotherapy

Caloric restriction and fasting have been known for a long time for their health- and life-span promoting effects, with coherent observations in multiple model organisms as well as epidemiological and clinical studies. This holds particularly true for cancer. The health-promoting effects of caloric restriction and fasting are mediated at least partly through their cellular effects-chiefly autophagy induction-rather than reduced calorie intake per se. Interestingly, caloric restriction has a differential impact on cancer and healthy cells, due to the atypical metabolic profile of malignant tumors. Caloric restriction mimetics are non-toxic compounds able to mimic the biochemical and physiological effects of caloric restriction including autophagy induction. Caloric restriction and its mimetics induce autophagy to improve the efficacy of some cancer treatments that induce immunogenic cell death (ICD), a type of cellular demise that eventually elicits adaptive antitumor immunity. Caloric restriction and its mimetics also enhance the therapeutic efficacy of chemo-immunotherapies combining ICD-inducing agents with immune checkpoint inhibitors targeting PD-1. Collectively, preclinical data encourage the application of caloric restriction and its mimetics as an adjuvant to immunotherapies. This recommendation is subject to confirmation in additional experimental settings and in clinical trials. In this work, we review the preclinical and clinical evidence in favor of such therapeutic interventions before listing ongoing clinical trials that will shed some light on this subject.

Late-life intermittent fasting decreases aging-related frailty and increases renal hydrogen sulfide production in a sexually dimorphic manner

Global average life expectancy continues to rise. As aging increases the likelihood of frailty, which encompasses metabolic, musculoskeletal, and cognitive deficits, there is a need for effective anti-aging treatments. It is well established in model organisms that dietary restriction (DR), such as caloric restriction or protein restriction, enhances health and lifespan. However, DR is not widely implemented in the clinic due to patient compliance and its lack of mechanistic underpinnings. Thus, the present study tested the effects of a somewhat more clinically applicable and adoptable DR regimen, every-other-day (EOD) intermittent fasting, on frailty in 20-month-old male and female C57BL/6 mice. Frailty was determined by a series of metabolic, musculoskeletal, and cognitive tasks performed prior to and toward the end of the 2.5-month dietary intervention. Late-life EOD fasting attenuated overall energy intake, hypothalamic inflammatory gene expression, and frailty in males. However, it failed to reduce overall caloric intake and had a little positive effect in females. Given that the selected benefits of DR are dependent on augmented production of the gasotransmitter hydrogen sulfide (H₂S) and that renal H₂S production declines with age, we tested the effects of EOD fasting on renal H₂S production capacity and its connection to frailty in males. EOD fasting boosted renal H₂S production, which positively correlated with improvements in multiple components of frailty tasks. Therefore, late-life initiated EOD fasting is sufficient to reduce aging-related frailty, at least in males, and suggests that renal H₂S production capacity may modulate the effects of late-life EOD fasting on frailty.

An isocaloric moderately high-fat diet extends lifespan in male rats and Drosophila

The health effect of dietary fat has been one of the most vexing issues in the field of nutrition. Few animal studies have examined the impact of high-fat diets on lifespan by controlling energy intake. In this study, we found that compared to a normal diet, an isocaloric moderately high-fat diet (IHF) significantly prolonged lifespan by decreasing the profiles of free fatty acids (FFAs) in serum and multiple tissues via downregulating FFA anabolism and upregulating catabolism pathways in rats and flies. Proteomics analysis in rats identified PPRC1 as a key protein that was significantly upregulated by nearly 2-fold by IHF, and among the FFAs, only palmitic acid (PA) was robustly and negatively associated with the expression of PPRC1. Using PPRC1 transgenic RNAi/overexpression flies and in vitro experiments, we demonstrated that IHF significantly reduced PA, which could upregulate PPRC1 through PPARG, resulting in improvements in oxidative stress and inflammation and prolonging the lifespan.

Fasting ameliorates oxidative stress: A review of physiological strategies across life history events in wild vertebrates

Fasting is a component of many species' life history due to environmental factors or behavioral patterns that limit access to food. Despite metabolic and physiological challenges associated with these life history stages, fasting-adapted wild vertebrates exhibit few if any signs of oxidative stress, suggesting that fasting promotes redox homeostasis. Here we review mammalian, avian, reptilian, amphibian, and piscine examples of animals undergoing fasting during prolonged metabolic suppression (e.g. hibernation and estivation) or energetically demanding processes (e.g. migration and breeding) to better understand the mechanisms underlying fasting tolerance in wild vertebrates. These studies largely show beneficial effects of fasting on redox balance via limited oxidative damage. Though some species exhibit signs of oxidative stress due to energetically or metabolically extreme processes, fasting wild vertebrates largely buffer themselves from the negative consequences of oxidative damage through specific strategies such as elevating antioxidants, selectively maintaining redox balance in critical tissues, or modifying behavioral patterns. We conclude with suggestions for future research to better elucidate the protective effects of fasting on oxidative stress as well as disentangle the impacts from other life history stages. Further research in these areas will facilitate our understanding of the mechanisms wild vertebrates use to mitigate the negative impacts associated with metabolically-extreme life history stages as well as potential translation into therapeutic interventions in non-fasting-adapted species including humans.

Nutritional Preconditioning in Cancer Treatment in Relation to DNA Damage and Aging

Dietary restriction (DR) is the most successful nutritional intervention for extending lifespan and preserving health in numerous species. Reducing food intake triggers a protective response that shifts energy resources from growth to maintenance and resilience mechanisms. This so-called survival response has been shown to particularly increase life- and health span and decrease DNA damage in DNA repair-deficient mice exhibiting accelerated aging. Accumulation of DNA damage is the main cause of aging, but also of cancer. Moreover, radiotherapies and most chemotherapies are based on damaging DNA, consistent with their ability to induce toxicity and accelerate aging. Since fasting and DR decrease DNA damage and its effects, nutritional preconditioning holds promise for improving (cancer) therapy and preventing short- and long-term side effects of anticancer treatments. This review provides an overview of the link between aging and cancer, highlights important preclinical studies applying such nutritional preconditioning, and summarizes the first clinical trials implementing nutritional preconditioning in cancer treatment.

Feed Restriction Modulates Growth, Gut Morphology and Gene Expression in Zebrafish

A reduction in daily caloric or nutrient intake has been observed to promote health benefits in mammals and other vertebrates. Feed Restriction (FR), whereby the overall food intake of the organism is reduced, has been explored as a method to improve metabolic and immune health, as well as to optimize productivity in farming. However, less is known regarding the molecular and physiological consequences of FR. Using the model organism, Danio rerio, we investigated the impact of a short-term (month-long) FR on growth, gut morphology and gene expression. Our data suggest that FR has minimal effects on the average growth rates, but it may affect weight and size heterogeneity in a sex-dependent manner. In the gut, we observed a significant reduction in gut circumference and generally lower mucosal heights, whereas other parameters remained unchanged. Gene Ontology (GO), EuKaryotic Orthologous Groups (KOG), and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified numerous metabolic, reproductive, and immune response pathways that were affected by FR. These results broaden our understanding of FR and contribute towards growing knowledge of its effects on vertebrate health.

Simulated microgravity accelerates aging in Saccharomyces cerevisiae

The human body experiences physiological changes under microgravity environment that phenocopy aging on Earth. These changes include early onset osteoporosis, skeletal muscle atrophy, cardiac dysfunction, and immunosenescence, and such adaptations to the space environment may pose some risk to crewed missions to Mars. To investigate the effect of microgravity on aging, many model organisms have been used such as the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and mice. Herein we report that the budding yeast Saccharomyces cerevisiae show decreased replicative lifespan (RLS) under simulated microgravity in a clinostat. The reduction of yeast lifespan is not a result of decreased tolerance to heat shock or oxidative stress and could be overcome either by deletion of FOB1 or calorie restriction, two known interventions that extend yeast RLS. Deletion of the sirtuin gene SIR2 worsens the simulated microgravity effect on RLS, and together with the fob1Δ mutant phenotype, it suggests that simulated microgravity augments the formation of extrachromosomal rDNA circles, which accumulate in yeast during aging. We also show that the chronological lifespan in minimal medium was not changed when cells were grown in the clinostat. Our data suggest that the reduction in longevity due to simulated microgravity is conserved in yeast, worms, and flies, and these findings may have potential implications for future crewed missions in space, as well as the use of microgravity as a model for human aging.

Plasma from Young Rats Injected into Old Rats Induce Antiaging Effects

An experimental novel antiaging intervention strategy is based on the concept of parabiosis, which involves long-term treatment with factors derived from young blood facilitating rejuvenation of old individuals. In this study, we employed blood plasma from young rats as an intervention strategy to evaluate whether this could impact aging biomarkers in aged rats. The biomarkers studied include: reactive oxygen species, the ferric reducing ability of plasma, plasma membrane redox system, reduced glutathione, malondialdehyde, protein carbonyl, and advanced oxidation protein products in blood. Additionally, the level of tumor necrosis factor-α and interleukin-6 were also estimated in blood. We found that old rats injected with plasma from young rats were protected from oxidative stress. Thus, this study provides some evidence of the rejuvenating effects of young plasma. We hypothesize that young plasma may contain certain "factors," which may be responsible for the observed effects. The mechanism of action is not clearly understood and is open to further studies.

Comparison of Genetically Engineered Immunodeficient Animal Models for Nonclinical Testing of Stem Cell Therapies

For the recovery or replacement of dysfunctional cells and tissue-the goal of stem cell research-successful engraftment of transplanted cells and tissues are essential events. The event is largely dependent on the immune rejection of the recipient; therefore, the immunogenic evaluation of candidate cells or tissues in immunodeficient animals is important. Understanding the immunodeficient system can provide insights into the generation and use of immunodeficient animal models, presenting a unique system to explore the capabilities of the innate immune system. In this review, we summarize various immunodeficient animal model systems with different target genes as valuable tools for biomedical research. There have been numerous immunodeficient models developed by different gene defects, resulting in many different features in phenotype. More important, mice, rats, and other large animals exhibit very different immunological and physiological features in tissue and organs, including genetic background and a representation of human disease conditions. Therefore, the findings from this review may guide researchers to select the most appropriate immunodeficient strain, target gene, and animal species based on the research type, mutant gene effects, and similarity to human immunological features for stem cell research.

Effects of Caloric Restriction Diet on Arterial Hypertension and Endothelial Dysfunction

The most common manifestation of cardiovascular (CV) diseases is the presence of arterial hypertension (AH), which impacts on endothelial dysfunction. CV risk is associated with high values of systolic and diastolic blood pressure and depends on the presence of risk factors, both modifiable and not modifiable, such as overweight, obesity, physical exercise, smoking, age, family history, and gender. The main target organs affected by AH are the heart, brain, vessels, kidneys, and eye retina. AH onset can be counteracted or delayed by adopting a proper diet, characterized by a low saturated fat and sodium intake, a high fruit and vegetable intake, a moderate alcohol consumption, and achieving and maintaining over time the ideal body weight. In this review, we analyzed how a new nutritional approach, named caloric restriction diet (CRD), can provide a significant reduction in blood pressure values and an improvement of the endothelial dysfunction. In fact, CRD is able to counteract aging and delay the onset of CV and neurodegenerative diseases through the reduction of body fat mass, systolic and diastolic values, free radicals production, and oxidative stress. Currently, there are few studies on CRD effects in the long term, and it would be advisable to perform observational studies with longer follow-up.

Fasting and fasting-mimicking diets for chemotherapy augmentation

The increasingly older population in most developed countries will likely experience aging-related chronic diseases such as diabetes, metabolic syndrome, heart and lung diseases, osteoporosis, arthritis, dementia, and/or cancer. Genetic and environmental factors, but also lifestyle choices including physical activity and dietary habits, play essential roles in disease onset and progression. Sixty-five percent of Americans diagnosed with cancer now survive more than 5 years, making the need for informed lifestyle choices particularly important to successfully complete their treatment, increase the recovery from the cytotoxic therapy options, and improve cancer-free survival. This review will discuss the findings on the use of prolonged fasting, as well as fasting-mimicking diets to augment cancer treatment. Preclinical studies in rodents strongly support the implementation of these dietary interventions and a small number of clinical trials begin to provide encouraging results for cancer patients and cancer survivors.

Impact of supervised beego, a traditional Chinese water-only fasting, on thrombosis and haemostasis

Beego is a traditional Chinese complete water-only fasting practice initially developed for spiritual purposes, later extending to physical fitness purposes. Beego notably includes a psychological induction component that includes meditation and abdominal breathing, light body exercise and ends with a specific gradual refeeding program before returning to a normal diet. Beego has regained its popularity in recent decades in China as a strategy for helping people in subhealthy conditions or with metabolic syndrome, but we are unaware of any studies examining the biological effects of this practice. To address this, we here performed a longitudinal study of beego comprising fasting (7 and 14 day cohorts) and a 7-day programmed refeeding phase. In addition to detecting improvements in cardiovascular physiology and selective reduction of blood pressure in hypertensive subjects, we observed that beego decreased blood triacylglycerol (TG) selectively in TG-high subjects and increased cholesterol in all subjects during fasting; however, the cholesterol levels were normalised after completion of the refeeding program. Strikingly, beego reduced platelet formation, activation, aggregation and degranulation, resulting in an alleviated thrombosis risk, yet maintained haemostasis by sustaining levels of coagulation factors and other haemostatic proteins. Mechanistically, we speculate that downregulation of G6B and MYL9 may influence the observed beego-mediated reduction in platelets. Fundamentally, our study supports that supervised beego reduces thrombosis risk without compromising haemostasis capacity. Moreover, our results support that beego under medical supervision can be implemented as non-invasive intervention for reducing thrombosis risk, and suggest several lines of intriguing inquiry for future studies about this fasting practice (http://www.chictr.org.cn/index.aspx, number, ChiCTR1900027451).

Thymus involution sets the clock of the aging T-cell landscape: Implications for declined immunity and tissue repair

Aging is generally characterized as a gradual increase in tissue damage, which is associated with senescence and chronic systemic inflammation and is evident in a variety of age-related diseases. The extent to which such tissue damage is a result of a gradual decline in immune regulation, which consequently compromises the capacity of the body to repair damages, has not been fully explored. Whereas CD4 T lymphocytes play a critical role in the orchestration of immunity, thymus involution initiates gradual changes in the CD4 T-cell landscape, which may significantly compromise tissue repair. In this review, we describe the lifespan accumulation of specific dysregulated CD4 T-cell subsets and their coevolution with systemic inflammation in the process of declined immunity and tissue repair capacity with age. Then, we discuss the process of thymus involution-which appears to be most pronounced around puberty-as a possible driver of the aging T-cell landscape. Finally, we identify individualized T cell-based early diagnostic biomarkers and therapeutic strategies for age-related diseases.