Lack of Immune Resilience Negatively Affects Physical Resilience: Results From the InCHIANTI Follow-Up Study

There is consistent evidence that immune response declines with aging, with wide interindividual variability and a still unclear relationship with the development of frailty. To address this question, we assessed the role of immune resilience (capacity to restore immune functions), operationalized as the neutrophil-to-lymphocytes ratio (NL-ratio) and monocytes-to-lymphocytes ratio (ML-ratio), in the pathway that from robust status shifts to pre-frailty and frailty, and finally to death. The InCHIANTI study enrolled representative samples from the registry lists of 2 towns in Tuscany, Italy. Baseline data were collected in 1998, with follow-up visits every 3 years. The 1 453 participants enrolled were assessed and followed for lifestyle, clinical condition, physical performance, clinical, and physiological measures. For the purpose of this analysis, we used only 1 022 subjects aged 65 or older at baseline. Participants in the 3 highest deciles of distribution for NL-ratio (>2.44) were more likely to experience a transition from robust to pre-frail, and to overt frailty status. Moreover, NL-ratio (tenth decile > 3.53) and ML-ratio (tenth decile > 2.02) were both predictors of mortality. These results were independent of chronological age, sex, comorbidities, and chronic low-grade inflammation assessed by high sensitivity C-reactive protein measurement. The 2 leucocytes-derived ratios, NL-ratio and ML-ratio, represent markers of immune resilience and predict changes in physical resilience and mortality. These biomarkers are inexpensive because they are based on data routinely collected in clinical practice and can be used to assess the risk of frailty progression and mortality. Clinical Trials Registration Number: NCT01331512.

Resilience, aging, and response to radiation exposure (RARRE) in nonhuman primates: a resource review

The Wake Forest nonhuman primate (NHP) Radiation Late Effects Cohort (RLEC) is a unique and irreplaceable population of aging NHP radiation survivors which serves the nation's need to understand the late effects of radiation exposure. Over the past 16 years, Wake Forest has evaluated > 250 previously irradiated rhesus macaques (Macaca mulatta) that were exposed to single total body irradiation (IR) doses of 1.14-8.5 Gy or to partial body exposures of up to 10 Gy (5% bone marrow sparing) or 10.75 Gy (whole thorax). Though primarily used to examine IR effects on disease-specific processes or to develop radiation countermeasures, this resource provides insights on resilience across physiologic systems and its relationship with biological aging. Exposure to IR has well documented deleterious effects on health, but the late effects of IR are highly variable. Some animals exhibit multimorbidity and accumulated health deficits, whereas others remain relatively resilient years after exposure to total body IR. This provides an opportunity to evaluate biological aging at the nexus of resilient/vulnerable responses to a stressor. Consideration of inter-individual differences in response to this stressor can inform individualized strategies to manage late effects of radiation exposure, and provide insight into mechanisms underlying systemic resilience and aging. The utility of this cohort for age-related research questions was summarized at the 2022 Trans-NIH Geroscience Interest Group's Workshop on Animal Models for Geroscience. We present a brief review of radiation injury and its relationship to aging and resilience in NHPs with a focus on the RLEC.

Insulin Sensitivity Initially Worsens but Later Improves With Aging in Male C57BL/6N Mice

Aging is believed to induce insulin resistance in humans. However, when and how insulin sensitivity changes with aging remains unclear in both humans and mice. In this study, groups of male C57BL/6N mice at 9-19 weeks (young), 34-67 weeks (mature adult), 84-85 weeks (presenile), and 107-121 weeks of age underwent hyperinsulinemic-euglycemic clamp studies with somatostatin infusion under awake and nonrestrained conditions. The glucose infusion rates for maintaining euglycemia were 18.4 ± 2.9, 5.9 ± 1.3, 20.3 ± 7.2, and 25.3 ± 4.4 mg/kg/min in young, mature adult, presenile, and aged mice, respectively. Thus, compared with young mice, mature adult mice exhibited the expected insulin resistance. In contrast, presenile and aged mice showed significantly higher insulin sensitivity than mature adult mice. These age-related changes were mainly observed in glucose uptake into adipose tissue and skeletal muscle (rates of glucose disappearance were 24.3 ± 2.0, 17.1 ± 1.0, 25.5 ± 5.2, and 31.8 ± 2.9 mg/kg/min in young, mature adult, presenile, and aged mice, respectively). Epididymal fat weight and hepatic triglyceride levels were higher in mature adult mice than those in young and aged mice. Our observations indicate that, in male C57BL/6N mice, insulin resistance appears at the mature adult stage of life but subsequently improves markedly. These alterations in insulin sensitivity are attributable to changes in visceral fat accumulations and age-related factors.

Major depression and the biological hallmarks of aging

Major depressive disorder (MDD) is characterized by psychological and physiological manifestations contributing to the disease severity and outcome. In recent years, several lines of evidence have suggested that individuals with MDD have an elevated risk of age-related adverse outcomes across the lifespan. This review provided evidence of a significant overlap between the biological abnormalities in MDD and biological changes commonly observed during the aging process (i.e., hallmarks of biological aging). Based on such evidence, we formulate a mechanistic model showing how abnormalities in the hallmarks of biological aging can be a common denominator and mediate the elevated risk of age-related health outcomes commonly observed in MDD. Finally, we proposed a roadmap for novel studies to investigate the intersection between the biology of aging and MDD, including the use of geroscience-guided interventions, such as senolytics, to delay or improve major depression by targeting biological aging.

DNA damage in circulating hematopoietic progenitor stem cells as promising biological sensor of frailty

Frailty is an age-related syndrome that exposes individuals to increased vulnerability. Although it is potentially reversible, in most cases it leads to negative outcomes, including mortality. The different methods proposed identify frailty after the onset of clinical manifestations. An early diagnosis might make it possible to manage the frailty progression better. The frailty pathophysiology is still unclear although mechanisms, in particular, those linked to inflammation and immunosenescence, have been investigated. A common feature of several clinical aspects involved in senescent organisms is the increase of oxidative stress, described as one of the major causes of deoxyribonucleic acid (DNA) damage accumulation in aged cells including the adult stem cell compartment. Likely, this accumulation is implicated in frailty status. The oxidative status of our frail, pre-frail, and non-frail population was characterized. In addition, the DNA damage in hematopoietic cells was evidenced by analyzing the peripheral blood mononuclear cell and their T lymphocyte, monocyte, circulating hematopoietic progenitor stem cell (cHPSC) subpopulations. The phosphorylation of C-terminal of histone H2AX at amino acid Ser 139 (γ-H2AX), which occurs at the DNA double-strand break focus, was evaluated. In our frail population, increased oxidative stress and a high level of DNA damage in cHPSC were found. This study may have potential implications because the increment of DNA damage in cHPSC could be suggestive of an organism impairment preceding the evident frailty. In addition, it may open the possibility for attenuation of frailty progression throughout specific drugs acting on preventing DNA damage or removing damaged cells

A geroscience motivated approach to treat Alzheimer's disease: Senolytics move to clinical trials

The pathogenic processes driving Alzheimer's disease (AD) are complex. An incomplete understanding of underlying disease mechanisms has presented insurmountable obstacles for developing effective disease-modifying therapies. Advanced chronological age is the greatest risk factor for developing AD. Intervening on biological aging may alter disease progression and represents a novel, complementary approach to current strategies. Toward this end, cellular senescence has emerged as a promising target. This complex stress response harbors damaged cells in a cell cycle arrested, apoptosis-resistant cell state. Senescent cells accumulate with age where they notoriously secrete molecules that contribute to chronic tissue dysfunction and disease. Thus, benefits of cell survival in a senescent fate are countered by their toxic secretome. The removal of senescent cells improves brain structure and function in rodent models at risk of developing AD, and in those with advanced Aβ and tau pathology. The present review describes the path to translating this promising treatment strategy to AD clinical trials. We review evidence for senescent cell accumulation in the human brain, considerations and strategies for senescence-targeting trials specific to AD, approaches to detect senescent brain cells in biofluids, and summarize the goals of the first senolytic trials for the treatment of AD (NCT04063124 and NCT04685590). This article is part of the Special Issue - Senolytics - Edited by Joao Passos and Diana Jurk.

Beta-guanidinopropionic acid does not extend D rosophila lifespan

Activation of AMP activated protein kinase (AMPK) signaling has been demonstrated to extend lifespan and improve healthspan across multiple species. This suggests pharmaceutical approaches to increase AMPK hold the potential to modify the aging process and promote healthy aging. Beta-guanidinopropionic acid (GPA) is a naturally occurring metabolite structurally similar to creatine. GPA is capable of activating AMPK signaling in mammalian models via competitive inhibition of cytosolic creatine kinase. A previous report suggested that dietary GPA supplementation increased lifespan in Drosophila through its effect on AMPK signaling and regulation of autophagy. However, studies in Caenorhabditis have found no beneficial effect of this compound on worm lifespan and that GPA may actually diminish lifespan in at least one Caenorhabditis species. To confirm previous reports of increased longevity in Drosophila, we tested a wide range of GPA concentrations on lifespan and healthspan in both male and female W¹¹¹⁸ flies. We report here that GPA does not extend lifespan in Drosophila as previously reported. Moreover, high doses of GPA are detrimental to Drosophila lifespan and stress resistance in male flies. These results suggest the lack of a robust effect of GPA on Drosophila lifespan and highlight the importance of replication studies within the field of aging.

Age-dependent changes in nuclear-cytoplasmic signaling in skeletal muscle

Mechanical forces are conducted through myofibers and into nuclei to regulate muscle development, hypertrophy, and homeostasis. We hypothesized that nuclei in aged muscle have changes in the nuclear envelope and associated proteins, resulting in altered markers of mechano-signaling.

METHODS

YAP/TAZ protein expression and gene expression of downstream targets, Ankrd1 and Cyr61, were evaluated as mechanotransduction indicators. Expression of proteins in the nuclear lamina and the nuclear pore complex (NPC) were assessed, and nuclear morphology was characterized by electron microscopy. Nuclear envelope permeability was assessed by uptake of 70 kDa fluorescent dextran.

RESULTS

Nuclear changes with aging included a relative decrease of lamin β1 and Nup107, and a relative increase in Nup93, which could underlie the aberrant nuclear morphology, increased nuclear leakiness, and elevated YAP/TAZ signaling.

CONCLUSION

Aged muscles have hyperactive nuclear-cytoplasmic signaling, indicative of altered nuclear mechanotransduction. These data highlight a possible role for the nucleus in aging-related aberrant mechano-sensing.

Greater Skeletal Muscle Oxidative Capacity Is Associated With Higher Resting Metabolic Rate: Results From the Baltimore Longitudinal Study of Aging

Resting metabolic rate (RMR) tends to decline with aging. The age-trajectory of decline in RMR is similar to changes that occur in muscle mass, muscle strength, and fitness, but while the decline in these phenotypes has been related to changes of mitochondrial function and oxidative capacity, whether lower RMR is associated with poorer mitochondrial oxidative capacity is unknown. In 619 participants of the Baltimore Longitudinal Study of Aging, we analyzed the cross-sectional association between RMR (kcal/day), assessed by indirect calorimetry, and skeletal muscle maximal oxidative phosphorylation capacity, assessed as postexercise phosphocreatine recovery time constant (τ PCr), by phosphorous magnetic resonance spectroscopy. Linear regression models were used to evaluate the relationship between τ PCr and RMR, adjusting for potential confounders. Independent of age, sex, lean body mass, muscle density, and fat mass, higher RMR was significantly associated with shorter τ PCr, indicating greater mitochondrial oxidative capacity. Higher RMR is associated with a higher mitochondrial oxidative capacity in skeletal muscle. This association may reflect a relationship between better muscle quality and greater mitochondrial health.

Aging Alters Cerebrovascular Endothelial GPCR and K+ Channel Function: Divergent Role of Biological Sex

Age-related dementia entails impaired blood flow to and throughout the brain due, in part, to reduced endothelial nitric oxide signaling. However, it is unknown whether sex affects cerebrovascular Gq-protein-coupled receptors (GPCRs) and K+ channels underlying endothelium-derived hyperpolarization (EDH) during progressive aging. Thus, we simultaneously evaluated intracellular Ca2+ ([Ca2+]i) and membrane potential (Vm) of intact endothelial tubes freshly isolated from posterior cerebral arteries of young (4-6 mo), middle-aged (12-16 mo), and old (24-28 mo) male and female C57BL/6 mice. Purinergic receptor function (vs. muscarinic) was dominant and enhanced for [Ca2+]i increases in old females versus old males. However, Ca2+-sensitive K+ channel function as defined by NS309-evoked Vm hyperpolarization was mildly impaired in females versus males during old age. This sex-based contrast in declined function of GPCRs and K+ channels to produce EDH may support a greater ability for physiological endothelial GPCR function to maintain optimal cerebral blood flow in females versus males during old age. As reflective of the pattern of cerebral blood flow decline in human subjects, inward-rectifying K+ (KIR) channel function decreased with progressive age regardless of sex. Combined age-related analyses masked male versus female aging and, contrary to expectation, hydrogen peroxide played a minimal role. Altogether, we conclude a sex-based divergence in cerebrovascular endothelial GPCR and K+ channel function while highlighting a previously unidentified form of age-related endothelial dysfunction as reduced KIR channel function.

The Role of Ames Dwarfism and Calorie Restriction on Gut Microbiota

The gut microbiome (GM) represents a large and very complex ecosystem of different microorganisms. There is an extensive interest in the potential role of the GM in different diseases including cancer, diabetes, cardiovascular diseases, and aging. The GM changes over the lifespan and is strongly associated with various age-related diseases. Ames dwarf (df/df) mice are characterized by an extended life- and healthspan, and although these mice are protected from many age-related diseases, their microbiome has not been studied. To determine the role of microbiota on longevity animal models, we investigated the changes in the GM of df/df and normal control (N) mice, by comparing parents before mating and littermate mice at three distinct time points during early life. Furthermore, we studied the effects of a 6-month calorie restriction (CR), the most powerful intervention extending the lifespan. Our data revealed significant changes of the GM composition during early life development, and we detected differences in the abundance of some bacteria between df/df and N mice, already in early life. Overall, the variability of the microbiota by genotype, time-point, and breeding pair showed significant differences. In addition, CR caused significant changes in microbiome according to gastrointestinal (GI) location (distal colon, ileum, and cecum), genotype, and diet. However, the overall impact of the genotype was more prominent than that of the CR. In conclusion, our findings suggest that the gut microbiota plays an important role during postnatal development in long-living df/df mice and CR dietary regimen can significantly modulate the GM.

Is Aging Biology Ageist?

The scientific questions we pursue are shaped by our cultural assumptions and biases, often in ways we are unaware. Here, we argue that modern biases against older adults (ageism) have unconsciously led aging biologists to assume that traits of older individuals are negative and those of younger individuals positive. We illustrate this bias with the example of how a medieval Chinese scholar might have approached the task of understanding aging biology. In particular, aging biologists have tended to emphasize functional declines during aging, rather than biological adaptation and population selection or composition processes; the reality is certainly that all these processes interact. Failure to make these distinctions could lead to interventions that improve superficial markers of aging while harming underlying health, particularly as the health priorities of older adults (autonomy, function, freedom from suffering, etc.) are often quite different from the goals of aging biologists (reducing disease, prolonging life). One approach to disentangling positive, negative, and neutral changes is to map trajectories of change across the life course of an individual (physiobiography). We emphasize that our goal is not to criticize our colleagues-we have been guilty too-but rather to help us all improve our science.

Vascular dysfunction as a potential culprit of sarcopenia

Aging-related changes to biological structures such as cardiovascular and musculoskeletal systems contribute to the development of comorbid conditions including cardiovascular disease and frailty, and ultimately lead to premature death. Although, frail older adults often demonstrate both cardiovascular and musculoskeletal comorbidities, the etiology of sarcopenia, and especially the contribution of cardiovascular aging is unclear. Aging-related vascular calcification is prevalent in older adults and is a known risk factor for cardiovascular disease and death. The effect vascular calcification has on function during aging is not well understood. Emerging findings suggest vascular calcification can impact skeletal muscle perfusion, negatively affecting nutrient and oxygen delivery to skeletal muscle, ultimately accelerating muscle loss and functional decline. The present review summarizes existing evidence on the biological mechanisms linking vascular calcification with sarcopenia during aging.

Bring Back the Rat!

As 2020 is "The Year of the Rat" in the Chinese astrological calendar, it seems an appropriate time to consider whether we should bring back the laboratory rat to front-and-center in research on the basic biology of mammalian aging. Beginning in the 1970s, aging research with rats became common, peaking in 1992 but then declined dramatically by 2018 as the mouse became preeminent. The purpose of this review is to highlight some of the historical contributions as well as current advantages of the rat as a mammalian model of human aging, because we suspect at least a generation of researchers is no longer aware of this history or these advantages. Herein, we compare and contrast the mouse and rat in the context of several biological domains relevant to their use as appropriate models of aging: phylogeny/domestication, longevity interventions, pathology/physiology, and behavior/cognition. It is not the goal of this review to give a complete characterization of the differences between mice and rats, but to provide important examples of why using rats as well as mice is important to advance our understanding of the biology of aging.

A Geroscience Perspective on COVID-19 Mortality

A novel coronavirus, SARS-CoV-2, emerged in December 2019, leading within a few months to a global pandemic. COVID-19, the disease caused by this highly contagious virus, can have serious health consequences, though risks of complications are highly age-dependent. Rates of hospitalization and death are less than 0.1% in children, but increase to 10% or more in older people. Moreover, at all ages, men are more likely than women to suffer serious consequences from COVID-19. These patterns are familiar to the geroscience community. The effects of age and sex on mortality rates from COVID-19 mirror the effects of aging on almost all major causes of mortality. These similarities are explored here, and underscore the need to consider the role of basic biological mechanisms of aging on potential treatment and outcomes of COVID-19.

Brain Protein Synthesis Rates in the UM-HET3 Mouse Following Treatment With Rapamycin or Rapamycin With Metformin

Treatment with the mechanistic target of rapamycin (mTOR) inhibitor, rapamycin (RAP), alone and in combination with the antidiabetic drug, metformin (RAP+MET), extends lifespan in mice. The mechanisms underlying lifespan extension are unclear. One possibility is improved capacity for proteostatic maintenance. We have previously characterized peripheral protein synthesis rates following treatment with RAP. However, it is unknown if RAP+MET elicits similar changes, or if either treatment affects protein synthesis in the brain. We hypothesized that 8 weeks of treatment with RAP and RAP+MET would alter brain protein synthesis rates to reflect proteostatic processes. Using the stable isotopic tracer, deuterium oxide (D2O), we demonstrate in UM-HET3 mice that protein synthesis rates measured in whole brain were unaffected by treatment in young male mice, whereas RAP+MET decreased mitochondrial protein synthesis in young females. Conversely, RAP increased mitochondrial protein synthesis rates in older females. Activity through the AMPK/mTOR pathway was affected in a sex-specific manner in young mice, and minimal changes were observed in the older cohort. Thus, we establish D2O for measurements of biogenesis in the brain. These results provide initial insights into the effects of RAP and RAP+MET on brain protein synthesis. Additionally, these data emphasize that responses to slowed aging treatments vary with sex and age.

An Understudied Dimension: Why Age Needs to Be Considered When Studying Epigenetic-Environment Interactions

We live in a complex chemical environment where there are an estimated 350 000 chemical compounds or mixtures commercially produced. A strong body of literature shows that there are time points during early development when an organism’s epigenome is particularly sensitive to chemicals in its environment. What is less understood is how gene-environment and epigenetic-environment interactions change with age. This question is bidirectional: (1) how do chemicals in the environment affect the aging process and (2) how does aging affect an organism’s response to its chemical environment? The study of gene-environment interactions with age is especially important because, in many parts of the world, older individuals are a large and rapidly growing proportion of the population and because aging is a process universal to most of the animal kingdom. Epigenetics has emerged as a crucial framework for studying aging as epigenetic pathways, often triggered by environmental stimuli, have been shown to be essential regulators of the aging process. In this perspective article, we delineate the connection between aging, epigenetics, and environmental exposures. We discuss why it is essential to consider age when researching how an organism interacts with its environment. We describe recent advances in understanding how the chemical environment affects aging and the gap in research on how age affects an organism’s response to the environment. Finally, we highlight how model organisms and network approaches can help fill this crucial gap. Taken together, systemic changes that occur in the epigenome with age indicate that adult organisms cannot be treated as a homogeneous population and that there are discrete mechanisms modulating the aging epigenome that we do not yet understand.

Lack of consensus on an aging biology paradigm? A global survey reveals an agreement to disagree, and the need for an interdisciplinary framework

At a recent symposium on aging biology, a debate was held as to whether or not we know what biological aging is. Most of the participants were struck not only by the lack of consensus on this core question, but also on many basic tenets of the field. Accordingly, we undertook a systematic survey of our 71 participants on key questions that were raised during the debate and symposium, eliciting 37 responses. The results confirmed the impression from the symposium: there is marked disagreement on the most fundamental questions in the field, and little consensus on anything other than the heterogeneous nature of aging processes. Areas of major disagreement included what participants viewed as the essence of aging, when it begins, whether aging is programmed or not, whether we currently have a good understanding of aging mechanisms, whether aging is or will be quantifiable, whether aging will be treatable, and whether many non-aging species exist. These disagreements lay bare the urgent need for a more unified and cross-disciplinary paradigm in the biology of aging that will clarify both areas of agreement and disagreement, allowing research to proceed more efficiently. We suggest directions to encourage the emergence of such a paradigm.

Association of sleep quality with telomere length, a marker of cellular aging: A retrospective cohort study of older adults in the United States

BACKGROUND

Sleep quality is a risk factor for age-related diseases, and although the underlying mechanisms remain unclear, the effects of poor sleep quality on telomere length (TL) may play a role.

OBJECTIVE

The objective of the study was to evaluate the independent association between sleep quality and salivary TL in a large sample of older adults.

DESIGN

We adopted a retrospective cohort design, and participants comprised 5,268 adults drawn from the Health and Retirement Study. We used the 2006 (baseline) and 2008 (follow-up) waves. Baseline sleep quality was assessed using 4 Likert scale questions (trouble falling asleep, waking up during the night, waking up too early and not being able to fall sleep again, and feeling well rested in the morning). The TL was assessed using the T/S ratio, a continuous variable. The associations between sleep quality and T/S were assessed using multivariable ordinary least squares regressions. All analyses were adjusted for demographics, lifestyle characteristics, psychosocial, and other factors.

RESULTS

Overall, 16% reported never feeling well rested in the morning; 25.7% of respondents always had trouble waking during the night; and 12.8% always had trouble waking up too early in the morning. Respondents who never felt rested in the morning had significantly shorter TL than those who always felt rested in the morning (adjusted beta = -0.08, standard error = 0.03, P < .01). The composite sleep measure was not significantly associated with shorter TL.

CONCLUSIONS

In this cohort of older adults, not feeling well rested in the morning was significantly and inversely associated with TL; however, the composite measure of sleep quality was not significantly associated with TL. These findings suggest a potential connection between one of the measures of impaired sleep and reduction in TL, a marker of cellular aging that has been linked to multiple chronic conditions.

Evaluation of Cerebrospinal Fluid Neurofilament Light Chain as a Routine Biomarker in a Memory Clinic

Systematic evaluation of biomarkers in representative populations is needed to validate their clinical utility. In this work, we assessed the diagnostic performance of cerebrospinal fluid (CSF) neurofilament light chain (NfL) in a neurocognitive clinical setting. A total of 51 patients with different cognitive clinical syndromes and 11 cognitively normal individuals were evaluated in a memory clinic in Argentina. Clinical conditions included mild cognitive impairment (MCI, n = 12), dementia of Alzheimer's type (DAT, n = 14), behavioral variant frontotemporal dementia (bvFTD, n = 13), and primary progressive aphasia (logopenic [n = 6], semantic [n = 2], and nonfluent [n = 4]). We quantified CSF NfL and core Alzheimer's disease biomarkers using commercially available ELISA kits. Cortical thickness was analyzed on brain magnetic resonance imaging scans from 10 controls and 10 patients. CSF NfL was significantly increased in MCI, FTD, and DAT patients compared with controls (Kruskal-Wallis, p < .0001). Interestingly, receiver operating characteristic curve analysis showed the highest area under the curve (AUC) value when analyzing control versus bvFTD patients (AUC = 0.9441). Also, we observed a marginally significant correlation between NfL levels and left orbitofrontal cortex thickness in a small group of patients with FTD. Overall, our results further support CSF NfL as a promising biomarker in the diagnostic workup of bvFTD.

Age-related changes in mitochondrial membrane composition of Nothobranchius furzeri.: comparison with a longer-living Nothobranchius species

Membrane compositions, particularly of mitochondria, could be critical factors in the mechanisms of growth and aging, especially during phases of high oxidative stress that result in molecular damage. Changes affecting lipid class or fatty acid (FA) compositions could affect phospholipid (PL) properties and alter mitochondrial function. In the present study, mitochondrial membrane PL compositions were analysed throughout the life-cycle of Nothobranchius furzeri, a species with explosive growth and one of the shortest-lived vertebrates. Mitochondrial PLs showed several changes with age. Proportions of total PLs and PC were reduced while an increase in PS, CL and PE was observed, mainly between the 2.5 and 5 months of fish age, the time during which animals doubled their weight. FA compositions of individual PLs in mitochondria were also significantly affected with age suggesting the existence of increasing damage to mitochondrial lipids during the life-cycle of N. furzeri that could be one of the main contributors to degraded mitochondrial function associated with aging. The peroxidation index values from N. furzeri mitochondrial PLs were significantly lower than those reported in N. rachovii, a species with a twofold longer life span than N. furzeri, which seems to contradict the membrane pacemaker theory of animal metabolism.

The Intersection of Aging Biology and the Pathobiology of Lung Diseases: A Joint NHLBI/NIA Workshop

Death from chronic lung disease is increasing and chronic obstructive pulmonary disease has become the third leading cause of death in the United States in the past decade. Both chronic and acute lung diseases disproportionately affect elderly individuals, making it likely that these diseases will become more frequent and severe as the worldwide population ages. Chronic lung diseases are associated with substantial morbidity, frequently resulting in exercise limiting dyspnea, immobilization, and isolation. Therefore, effective strategies to prevent or treat lung disease are likely to increase healthspan as well as life span. This review summarizes the findings of a joint workshop sponsored by the NIA and NHLBI that brought together investigators focused on aging and lung biology. These investigators encouraged the use of genetic systems and aged animals in the study of lung disease and the development of integrative systems-based platforms that can dynamically incorporate data sets that describe the genomics, transcriptomics, epigenomics, metabolomics, and proteomics of the aging lung in health and disease. Further research was recommended to integrate benchmark biological hallmarks of aging in the lung with the pathobiology of acute and chronic lung diseases with divergent pathologies for which advanced age is the most important risk factor.

Mitochondrial Aging: Is There a Mitochondrial Clock?

Fragmentation (fission) of mitochondria, occurring in response to oxidative challenge, leads to heterogeneity in the mitochondrial population. It is assumed that fission provides a way to segregate mitochondrial content between the "young" and "old" phenotype, with the formation of mitochondrial "garbage," which later will be disposed. Fidelity of this process is the basis of mitochondrial homeostasis, which is disrupted in pathological conditions and aging. The asymmetry of the mitochondrial fission is similar to that of their evolutionary ancestors, bacteria, which also undergo an aging process. It is assumed that mitochondrial markers of aging are recognized by the mitochondrial quality control system, preventing the accumulation of dysfunctional mitochondria, which normally are subjected to disposal. Possibly, oncocytoma, with its abnormal proliferation of mitochondria occupying the entire cytoplasm, represents the case when segregation of damaged mitochondria is impaired during mitochondrial division. It is plausible that mitochondria contain a "clock" which counts the degree of mitochondrial senescence as the extent of flagging (by ubiquitination) of damaged mitochondria. Mitochondrial aging captures the essence of the systemic aging which must be analyzed. We assume that the mitochondrial aging mechanism is similar to the mechanism of aging of the immune system which we discuss in detail.

A Clinically Relevant Frailty Index for Aging Rats

Frailty is a clinical syndrome that is increasingly prevalent during aging. Frailty involves the confluence of reduced strength, speed, physical activity, and endurance and is associated with adverse health outcomes. The present study adapts existing clinical and preclinical indices of frailty to the Fischer (F344) rat. Male F344 rats (n = 133; 17 mo) completed a battery of behavioral tasks, including forelimb wire suspension (strength), rotarod (speed), open field (physical activity), and inclined screen (endurance). Rats that performed poorly (lowest quintile) on two tasks were considered mildly frail (17.29%, n = 23), and rats that performed poorly on 3-4 tasks were considered frail (2.26%, n = 3). Logistic regression of 100-day survival revealed that mildly frail rats were 3.8 times and frail rats were 27.5 times more likely to die during that period than nonfrail rats (p = .038; 95% confidence interval: 2.030, 372.564). The selected criterion tests, cutoff points, and index provide a potential tool for identifying frailty in aged F344 rats, which is consistent with existing frailty indices for humans and mice.

Differential menopause- versus aging-induced changes in oxidative stress and circadian rhythm gene markers

Menopause is characterized by the depletion of estrogen that has been proposed to cause oxidative stress. Circadian rhythm is an internal biological clock that controls physiological processes. It was analyzed the gene expression in peripheral blood mononuclear cells and the lipids and glucose levels in plasma of a subgroup of 17 pre-menopausal women, 19 men age-matched as control group for the pre-menopausal women, 20 post-menopausal women and 20 men age-matched as control group for the post-menopausal women; all groups were matched by body mass index. Our study showed a decrease in the expression of the oxidative stress-related gene GPX1, and an increase in the expression of SOD1 as consequence of menopause. In addition, we found that the circadian rhythm-related gene PER2 decreased as consequence of menopause. On the other hand, we observed a decrease in the expression of the oxidative stress-related gene GPX4 and an increase in the expression of CAT as a consequence of aging, independently of menopause. Our results suggest that the menopause-induced oxidative stress parallels a disruption in the circadian clock in women, and part of the differences in oxidative stress observed between pre- and post-menopausal women was due to aging, independent of menopause. Clinical Trials.gov.Identifier: NCT00924937.

Impact of vitamin D receptor polymorphisms in centenarians

Vitamin D is a seco-sterol produced endogenously in the skin or obtained from certain foods. It exerts its action through binding to intracellular vitamin D receptor (VDR). Lately, the role of vitamin D has been revised regarding its potential advantage on delaying the process of aging. The aim of this study was to assess the contribution of VDR gene polymorphisms in healthy aging and longevity. We evaluated the frequency of four polymorphisms of the VDR gene (FokI, BsmI, ApaI, and TaqI) in centenarians (102 subjects, mean age: 102.3 ± 0.3 years), compared to septuagenarians (163 subjects, mean age: 73.0 ± 0.6 years) and we analyzed a variety of pathophysiologically relevant functions in centenarians. BsmI and ApaI provided a significant association with longevity: there was a highly significant difference in the frequency of BsmI genotypes (p = 0.037), ApaI genotypes (p = 0.022), and ApaI alleles (p = 0.050) in centenarians versus septuagenarians. Furthermore, we found a significant correlation of all the VDR gene polymorphisms in centenarians with some measured variables such as hand grip strength, body mass index, blood pressure, HDL cholesterol, and mini-mental state examination. We also found a correlation with the prevalence of medical history of hypertension, acute myocardial infarction, angina, venous insufficiency, dementia, chronic obstructive pulmonary disease, and arthrosis. In conclusion, this study proposes a new scenario in which the variability of the VDR gene is relevant in the aging process and emphasizes the role of VDR genetic background in determining healthy aging.

Rapamycin Attenuates Age-associated Changes in Tibialis Anterior Tendon Viscoelastic Properties

Rapamycin extends mouse life span, but the extent to which rapamycin prevents aging-associated changes in specific tissues remains unclear. Stiffness increases and collagen turnover decreases in mouse tendon with aging; thus, our aim was to determine the effect of long-term rapamycin treatment on the mechanical and structural properties of tendons from old mice. Tendons were harvested from female UM-HET3 mice maintained on a standard chow diet for 4 (adult) or 22 (old) months or fed chow containing polymer-encapsulated rapamycin (eRAPA) from 9 to 22 months of age (old RAPA). Stiffness was twofold higher for tendons of old compared with adult mice, but in old RAPA mice, tendon stiffness was maintained at a value not different from that of adults. Additionally, expression of collagen decreased, expression of matrix metalloproteinase-8 increased, and total hydroxyproline content trended toward decreased levels in tendons of old eRAPA-fed mice compared with controls. Finally, age-associated calcification of Achilles tendons and accompanying elevations in expression of chondrocyte and osteoblast markers were all lower in old eRAPA-fed mice. These results suggest that long-term administration of rapamycin alters the molecular pathways responsible for aging of tendon extracellular matrix, resulting in tissue that is structurally and mechanically similar to tendons in adult mice.