A Murine Frailty Index Based on Clinical and Laboratory Measurements: Links Between Frailty and Pro-inflammatory Cytokines Differ in a Sex-Specific Manner

Animal Models Relevant for Geroscience: Current Trends and Future Perspectives in Biomarkers, and Measures of Biological Aging

For centuries, aging was considered inevitable and immutable. Geroscience provides the conceptual framework to shift this focus toward a new view that regards aging as an active biological process, and the biological age of an individual as a modifiable entity. Significant steps forward have been made toward the identification of biomarkers for and measures of biological age, yet knowledge gaps in geroscience are still numerous. Animal models of aging are the focus of this perspective, which discusses how experimental design can be optimized to inform and refine the development of translationally relevant measures and biomarkers of biological age. We provide recommendations to the field, including: the design of longitudinal studies in which subjects are deeply phenotyped via repeated multilevel behavioral/social/molecular assays; the need to consider sociobehavioral variables relevant for the species studied; and finally, the importance of assessing age of onset, severity of pathologies, and age-at-death. We highlight approaches to integrate biomarkers and measures of functional impairment using machine learning approaches designed to estimate biological age as well as to predict future health declines and mortality. We expect that advances in animal models of aging will be crucial for the future of translational geroscience but also for the next chapter of medicine.

Spermidine is essential for fasting-mediated autophagy and longevity

Caloric restriction and intermittent fasting prolong the lifespan and healthspan of model organisms and improve human health. The natural polyamine spermidine has been similarly linked to autophagy enhancement, geroprotection and reduced incidence of cardiovascular and neurodegenerative diseases across species borders. Here, we asked whether the cellular and physiological consequences of caloric restriction and fasting depend on polyamine metabolism. We report that spermidine levels increased upon distinct regimens of fasting or caloric restriction in yeast, flies, mice and human volunteers. Genetic or pharmacological blockade of endogenous spermidine synthesis reduced fasting-induced autophagy in yeast, nematodes and human cells. Furthermore, perturbing the polyamine pathway in vivo abrogated the lifespan- and healthspan-extending effects, as well as the cardioprotective and anti-arthritic consequences of fasting. Mechanistically, spermidine mediated these effects via autophagy induction and hypusination of the translation regulator eIF5A. In summary, the polyamine-hypusination axis emerges as a phylogenetically conserved metabolic control hub for fasting-mediated autophagy enhancement and longevity.

Preclinical Studies on the Effects of Frailty in the Aging Heart

Age is a major risk factor for the development of cardiovascular diseases in men and in women. However, not all people age at the same rate and those who are aging rapidly are considered frail, compared with their fit counterparts. Frailty is an important clinical challenge because those who are frail are more likely to develop and die from illnesses, including cardiovascular diseases, than fit people of the same age. This increase in susceptibility to cardiovascular diseases in older individuals might occur as the cellular and molecular mechanisms involved in the aging process facilitate structural and functional damage in the heart. Consistent with this, recent studies in murine frailty models have provided strong evidence that maladaptive cardiac remodelling in older mice is the most pronounced in mice with a high level of frailty. For example, there is evidence that ventricular hypertrophy and contractile dysfunction increase as frailty increases in aging mice. Additionally, fibrosis and slowing of conduction in the sinoatrial node and atria are proportional to the level of frailty. These modifications could predispose frail older adults to diseases like heart failure and atrial fibrillation. This preclinical work also raises the possibility that emerging interventions designed to "treat frailty" might also treat or prevent cardiovascular diseases. These findings might help to explain why frail older people are most likely to develop these disorders as they age.

Sex-specific effects of frailty on cardiac structure and function: insights from preclinical models

Advanced age is an independent risk factor for cardiovascular diseases in both sexes. This is thought to be due, in part, to age-dependent cellular, structural, and functional changes in the heart, a process known as cardiac aging. An emerging view is that cardiac aging leads to the accumulation of cellular and subcellular deficits that increase susceptibility to cardiovascular diseases. Still, people age at different rates, with those aging rapidly considered frail. Evidence suggests that frailty, rather than simply age, is a major risk factor for cardiovascular disease and predicts adverse outcomes in those affected. Recent studies in mouse models of frailty show that many adverse changes associated with cardiac aging are more prominent in mice with a high degree of frailty. This suggests that frailty sets the stage for late life cardiovascular diseases to flourish and raises the possibility that treating frailty may treat cardiovascular diseases. These studies show that ventricular dysfunction increases with frailty in males only, whereas atrial dysfunction increases with frailty in both sexes. These results may shed light on the reasons that men and women can be susceptible to different cardiovascular diseases as they age, and why frail individuals are especially vulnerable to these disorders.

Quantification of healthspan in aging mice: introducing FAMY and GRAIL

The population around the world is graying, and as many of these individuals will spend years suffering from the burdens of age associated diseases, understanding how to increase healthspan, defined as the period of life free from disease and disability, is an urgent priority of geroscience research. The lack of agreed-upon quantitative metrics for measuring healthspan in aging mice has slowed progress in identifying interventions that do not simply increase lifespan, but also healthspan. Here, we define FAMY (Frailty-Adjusted Mouse Years) and GRAIL (Gauging Robust Aging when Increasing Lifespan) as new summary statistics for quantifying healthspan in mice. FAMY integrates lifespan data with longitudinal measurements of a widely utilized clinical frailty index, while GRAIL incorporates these measures and also adds information from widely utilized healthspan assays and the hallmarks of aging. Both metrics are conceptually similar to quality-adjusted life years (QALY), a widely utilized measure of disease burden in humans, and can be readily calculated from data acquired during longitudinal and cross-sectional studies of mouse aging. We find that interventions generally thought to promote health, including calorie restriction, robustly improve healthspan as measured by FAMY and GRAIL. Finally, we show that the use of GRAIL provides new insights, and identify dietary restriction of protein or isoleucine as interventions that robustly promote healthspan but not longevity in female HET3 mice. We suggest that the routine integration of these measures into studies of aging in mice will allow the identification and development of interventions that promote healthy aging even in the absence of increased lifespan.

Quantification of healthspan in aging mice: Introducing FAMY and GRAIL

The population around the world is graying, and as many of these individuals will spend years suffering from the burdens of age associated diseases, understanding how to increase healthspan, defined as the period of life free from disease and disability, is an urgent priority of geroscience research. The lack of agreed-upon quantitative metrics for measuring healthspan in aging mice has slowed progress in identifying interventions that do not simply increase lifespan, but also healthspan. Here, we define FAMY (Frailty-Adjusted Mouse Years) and GRAIL (Gauging Robust Aging when Increasing Lifespan) as new summary statistics for quantifying healthspan in mice. FAMY integrates lifespan data with longitudinal measurements of a widely utilized clinical frailty index, while GRAIL incorporates these measures and also adds information from widely utilized healthspan assays and the hallmarks of aging. Both metrics are conceptually similar to quality-adjusted life years (QALY), a widely-utilized measure of disease burden in humans, and can be readily calculated from data acquired during longitudinal and cross-sectional studies of mouse aging. We find that interventions generally thought to promote health, including calorie restriction, robustly improve healthspan as measured by FAMY and GRAIL. Finally, we show that the use of GRAIL provides new insights, and identify dietary restriction of protein or isoleucine as interventions that robustly promote healthspan but not longevity in female HET3 mice. We suggest that the routine integration of these measures into studies of aging in mice will allow the identification and development of interventions that promote healthy aging even in the absence of increased lifespan.

Imaging-based chromatin and epigenetic age, ImAge, quantitates aging and rejuvenation

Biomarkers of biological age that predict the risk of disease and expected lifespan better than chronological age are key to efficient and cost-effective healthcare1-3. To advance a personalized approach to healthcare, such biomarkers must reliably and accurately capture individual biology, predict biological age, and provide scalable and cost-effective measurements. We developed a novel approach - image-based chromatin and epigenetic age (ImAge) that captures intrinsic progressions of biological age, which readily emerge as principal changes in the spatial organization of chromatin and epigenetic marks in single nuclei without regression on chronological age. ImAge captured the expected acceleration or deceleration of biological age in mice treated with chemotherapy or following a caloric restriction regimen, respectively. ImAge from chronologically identical mice inversely correlated with their locomotor activity (greater activity for younger ImAge), consistent with the widely accepted role of locomotion as an aging biomarker across species. Finally, we demonstrated that ImAge is reduced following transient expression of OSKM cassette in the liver and skeletal muscles and reveals heterogeneity of in vivo reprogramming. We propose that ImAge represents the first-in-class imaging-based biomarker of aging with single-cell resolution.

Accumulating awareness on the clinical significance and relevance of frailty in cirrhosis: Time to dig deeper into mechanistic basis!

Frailty corresponds to an emerging construct in the hepatology which is originally introduced as a validated geriatric syndrome regarding increased vulnerability to pathophysiological stressors. As for patients with cirrhosis, the presence of frailty is indicative of debilitating conditions that subjects are prone to deleterious acute insults and have difficulties to restore even if the underlying liver function partially returned to normal levels. Since this conceptual development, a variety of tools assessing frailty have been proposed and evaluated in the context of cirrhosis. A recent performance-based metric for frailty, designated as Liver Frailty Index, has broadly been applied in patients with cirrhosis and exhibited acceptable predictive ability in relation to disease progression, mortality and hospitalization. However, those functional tests measuring frailty may be impossible to perform in circumstance that patients are critically ill or undergoing detrimental events. An interesting modality indicates the use of alternative tests to evaluate frailty, which may be more adaptable and of choice for specific subgroups. The interrelation between frailty and various cirrhosis-associated pathological entities is of clinical importance and implication. Noticeably, it is imperative to clarify these complex linkages to highlight novel therapeutic targets or interventional endpoints. The efficient and effective management of frailty is still challenging, but many attempts have been made to overcome barriers of affordability and availability. Some clinical trials on small scale revealed that home-based exercise and individualized nutrition therapy show benefits in patients with cirrhosis, and high adherence to the treatment regimen may direct better efficacy and performance.

Ameliorative effect of Brassica oleracea var. Italica extract on oxidative damage of arsenic in the rat's brain: biochemical, pathological, and behavioral aspects

Brain damage caused by the metal accumulation may result in the permanent injuries including severe neurological disorders. Thus, the aim of this study was to determine the medicinal efficacy of broccoli extract in arsenic-induced brain poisoning. Twenty-eight female rats were classified into 4 groups; control, receiving sodium arsenate (As), As + broccoli extract (As + Bc), and (Bc). Then, the Elevated Plus-Maze and pathological-biochemical assessment of the brain tissue were performed. Moreover, the GC-MS was used to explore the quantity and quality of broccoli extract. The catalase had a significant decrease in the As group compared to that of the control group; As + Bc and Bc groups also showed a significant increase compared to that of the As group. Glutathione peroxidase was the lowest in the As group (1.84 ± 0.97) and the highest in the Bc group (5.51 ± 2.31). The Treatment significantly reduced pro-inflammatory cytokines in the As + Bc group. In addition, in terms of behavioral changes, the duration of presence in the open arm was reduced in the As group compared to that of the control group. Besides, the open arm duration increased significantly in the Bc group. Interestingly, there was a significant increase in estrogen and gonadotropin hormones in the Bc group compared to the other groups. Pathological findings showed that the condition of cortical neurons was improved and the surrounding space was reduced in As + Bc compared to that of the As group. In addition, more than 30% of the extract's compounds are made up Phytol,1-isothiocyanate-4-[methylsulfinyl] butane, and γ-Sitosterol. Thereby, the broccoli extract with active substances was highly effective in enhancing the behavioral and pathological parameters switch in rats with arsenic-induced poisoned brains.

Assessment of Some Heavy Metals and Their Relationship with Oxidative Stress and Immunological Parameters in Aquatic Animal Species

Heavy metal accumulation changes the immune system and leads to oxidative damage in aquatic animals. The present study evaluated the correlation between heavy metal accumulation, with immunological and oxidative stress parameters, in various species in the aquatic environment of Western Iran. Fresh samples included fish (trout and carp) and shrimp obtained from Sanandaj aquaculture. After blood sampling and serum isolation for immunological study, meat sections of these animals were used to measure heavy metal concentrations to determine the oxidative stress and immunological parameters. The highest concentrations of Pb (0.82 ± 0.10), As (0.53 ± 0.18), Hg (0.47 ± 0.08), and Zn (28.77 ± 1.88) (µg/g) were found in trout, while the lowest accumulation of heavy metals except for Cd (0.24 ± 0.11) and Se (1.57 ± 0.42) (µg/g) were observed in shrimp. The antioxidant enzymes glutathione peroxidase (GPx) (1.89 ± 0.13) and superoxide dismutase (SOD) (1.96 ± 0.62) U/mg showed the highest concentrations in shrimp and lowest in the trout. Significant negative correlations were found between these enzymes with As and Pb in trout and carp. A significant positive correlation was determined between Se and Zn with GPx and a negative correlation with malondialdehyde (MDA) in shrimp. Immunological biomarkers indicated the concentrations of IL-6, TNF-α, and IFN-Ƴ were higher in fish than in shrimp, and the lowest IgM level was obtained in Shrimp. Increased Pb and Cd showed a significant relationship with increased IL-6 and TNF-α in trout compared to shrimp and carp. An increase in As and Se concentration beyound maximum permissible limits (MPL) were recorded in fish and shrimp, while a Zn level less than MPL was recorded. The target hazard quotients (THQ) and target cancer risk (TR) values of non-essential heavy metals were obtained under acceptable ranges. We suggest reducing the As and Pb content under aquaculture farms and increase in the amount of Zn through diets to keep healthy immunological and physiological conditions for aquatic species in the west of Iran.

Measurements of damage and repair of binary health attributes in aging mice and humans reveal that robustness and resilience decrease with age, operate over broad timescales, and are affected differently by interventions

As an organism ages, its health-state is determined by a balance between the processes of damage and repair. Measuring these processes requires longitudinal data. We extract damage and repair transition rates from repeated observations of binary health attributes in mice and humans to explore robustness and resilience, which respectively represent resisting or recovering from damage. We assess differences in robustness and resilience using changes in damage rates and repair rates of binary health attributes. We find a conserved decline with age in robustness and resilience in mice and humans, implying that both contribute to worsening aging health - as assessed by the frailty index (FI). A decline in robustness, however, has a greater effect than a decline in resilience on the accelerated increase of the FI with age, and a greater association with reduced survival. We also find that deficits are damaged and repaired over a wide range of timescales ranging from the shortest measurement scales toward organismal lifetime timescales. We explore the effect of systemic interventions that have been shown to improve health, including the angiotensin-converting enzyme inhibitor enalapril and voluntary exercise for mice. We have also explored the correlations with household wealth for humans. We find that these interventions and factors affect both damage and repair rates, and hence robustness and resilience, in age and sex-dependent manners.

Unsupervised learning of aging principles from longitudinal data

Age is the leading risk factor for prevalent diseases and death. However, the relation between age-related physiological changes and lifespan is poorly understood. We combined analytical and machine learning tools to describe the aging process in large sets of longitudinal measurements. Assuming that aging results from a dynamic instability of the organism state, we designed a deep artificial neural network, including auto-encoder and auto-regression (AR) components. The AR model tied the dynamics of physiological state with the stochastic evolution of a single variable, the "dynamic frailty indicator" (dFI). In a subset of blood tests from the Mouse Phenome Database, dFI increased exponentially and predicted the remaining lifespan. The observation of the limiting dFI was consistent with the late-life mortality deceleration. dFI changed along with hallmarks of aging, including frailty index, molecular markers of inflammation, senescent cell accumulation, and responded to life-shortening (high-fat diet) and life-extending (rapamycin) treatments.

Molecular and histological correlates of cognitive decline across age in male C57BL/6J mice

INTRODUCTION

Increasing age is the number one risk factor for developing cognitive decline and neurodegenerative disease. Aged humans and mice exhibit numerous molecular changes that contribute to a decline in cognitive function and increased risk of developing age-associated diseases. Here, we characterize multiple age-associated changes in male C57BL/6J mice to understand the translational utility of mouse aging.

METHODS

Male C57BL/6J mice from various ages between 2 and 24 months of age were used to assess behavioral, as well as, histological and molecular changes across three modalities: neuronal, microgliosis/neuroinflammation, and the neurovascular unit (NVU). Additionally, a cohort of 4- and 22-month-old mice was used to assess blood-brain barrier (BBB) breakdown. Mice in this cohort were treated with a high, acute dose of lipopolysaccharide (LPS, 10 mg/kg) or saline control 6 h prior to sacrifice followed by tail vein injection of 0.4 kDa sodium fluorescein (100 mg/kg) 2 h later.

RESULTS

Aged mice showed a decline in cognitive and motor abilities alongside decreased neurogenesis, proliferation, and synapse density. Further, neuroinflammation and circulating proinflammatory cytokines were increased in aged mice. Additionally, we found changes at the BBB, including increased T cell infiltration in multiple brain regions and an exacerbation in BBB leakiness following chemical insult with age. There were also a number of readouts that were unchanged with age and have limited utility as markers of aging in male C57BL/6J mice.

CONCLUSIONS

Here we propose that these changes may be used as molecular and histological readouts that correspond to aging-related behavioral decline. These comprehensive findings, in the context of the published literature, are an important resource toward deepening our understanding of normal aging and provide an important tool for studying aging in mice.

The association of a frailty index from laboratory tests and vital signs with clinical outcomes in hospitalized older adults

BACKGROUND

Frailty, a state of vulnerability to stressors resulting from loss of physiological reserve due to multisystemic dysfunction, is common among hospitalized older adults. Hospital clinicians need objective and practical instruments that identify older adults with frailty. The FI-LAB is based on laboratory values and vital signs and may capture biological changes of frailty that predispose hospitalized older adults to complications. The study's aim was to assess the association of the FI-LAB versus VA-FI with hospital and post-hospital clinical outcomes in older adults.

METHODS

Retrospective cohort study was conducted on Veterans aged ≥60 admitted to a VA hospital. We identified acute hospitalizations January 2011-December-2014 with 1-year follow-up. A 31-item FI-LAB was created from blood laboratory tests and vital signs collected within the first 48 h of admission and scores were categorized as low (<0.25), moderate (0.25-0.40), and high (>0.40). For each FI-LAB group, we obtained odds ratio (OR) and confidence intervals (CI) for hospital and post-hospital outcomes using multivariate binomial logistic regression. Additionally, we calculated hazard ratios (HR) and CI for all-cause in-hospital mortality comparing the high and moderate FI-LAB group with the low group.

RESULTS

Patients were 1407 Veterans, mean age 72.7 (SD = 9.0), 67.8% Caucasian, 96.1% males, 47.0% (n = 661), 41.0% (n = 577), and 12.0% (n = 169) were in the low, moderate, and high FI-LAB groups, respectively. Moderate and high scores were associated with prolonged LOS, OR:1.62 (95% CI:1.29-2.03); and 3.36 (95% CI:2.27-4.99), ICU admission, OR:1.40 (95% CI:1.03-1.90); and OR:2.00 (95% CI:1.33-3.02), nursing home placement OR:2.36 (95% CI:1.26-4.44); and 5.99 (95% CI:2.83-12.70), 30-day readmissions OR:1.74 (95% CI:1.20-2.52); and 2.20 (95% CI:1.30-3.74), 30-day mortality OR: 2.51 (95% CI:1.01-6.23); and 8.97 (95% CI:3.42-23.53), 6-month mortality OR:3.00 (95% CI:1.90-4.74); and 6.16 (95% CI:3.55-10.71), and 1-year mortality OR: 2.66 (95% CI:1.87-3.79); and 4.76 (95% CI:3.00-7.54) respectively. The high FI-LAB group showed higher risk of in-hospital mortality, HR:18.17 (95% CI:4.01-80.52) with an area-under-the-curve of 0.843 (95% CI:0.75-0.93).

CONCLUSIONS

High and moderate FI-LAB scores were associated with worse in-hospital and post-hospital outcomes. The FI-LAB may identify hospitalized older patients with frailty at higher risk and assist clinicians in implementing strategies to improve outcomes.

A machine-vision-based frailty index for mice

Heterogeneity in biological aging manifests itself in health status and mortality. Frailty indices (FIs) capture health status in humans and model organisms. To accelerate our understanding of biological aging and carry out scalable interventional studies, high-throughput approaches are necessary. Here we introduce a machine-learning-based visual FI for mice that operates on video data from an open-field assay. We use machine vision to extract morphometric, gait and other behavioral features that correlate with FI score and age. We use these features to train a regression model that accurately predicts the normalized FI score within 0.04 ± 0.002 (mean absolute error). Unnormalized, this error is 1.08 ± 0.05, which is comparable to one FI item being mis-scored by 1 point or two FI items mis-scored by 0.5 points. This visual FI provides increased reproducibility and scalability that will enable large-scale mechanistic and interventional studies of aging in mice.

The Use of Dietary Supplements and Amino Acid Restriction Interventions to Reduce Frailty in Pre-Clinical Models

Frailty is a state of accelerated aging that increases susceptibility to adverse health outcomes. Due to its high societal and personal costs, there is growing interest in discovering beneficial interventions to attenuate frailty. Many of these interventions involve the use of lifestyle modifications such as dietary supplements. Testing these interventions in pre-clinical models can facilitate our understanding of their impact on underlying mechanisms of frailty. We conducted a narrative review of studies that investigated the impact of dietary modifications on measures of frailty or overall health in rodent models. These interventions include vitamin supplements, dietary supplements, or amino acid restriction diets. We found that vitamins, amino acid restriction diets, and dietary supplements can have beneficial effects on frailty and other measures of overall health in rodent models. Mechanistic studies show that these effects are mediated by modifying one or more mechanisms underlying frailty, in particular effects on chronic inflammation. However, many interventions do not measure frailty directly and most do not investigate effects in both sexes, which limits their applicability. Examining dietary interventions in animal models allows for detailed investigation of underlying mechanisms involved in their beneficial effects. This may lead to more successful, translatable interventions to attenuate frailty.

Frailty in rodents: Models, underlying mechanisms, and management

Frailty is a clinical geriatric syndrome characterized by decreased multisystem function and increased vulnerability to adverse outcomes. Although numerous studies have been conducted on frailty, the underlying mechanisms and management strategies remain unclear. As rodents share homology with humans, they are used extensively as animal models to study human diseases. Rodent frailty models can be classified broadly into the genetic modification and non-genetic modification models, the latter of which include frailty assessment models (based on the Fried frailty phenotype and frailty index methods) and induced frailty models. Such models were developed for use in investigating frailty-related physiological changes at the gene, cellular, molecular, and system levels, including the organ system level. Furthermore, exercise, diet, and medication interventions, in addition to their combinations, could improve frailty status in rodents. Rodent frailty models provide novel and effective tools for frailty research. In the present paper, we review research progress in rodent frailty models, mechanisms, and management, which could facilitate and guide further clinical research on frailty in older adults.

Physiological Systems in Promoting Frailty

Frailty is a complex syndrome affecting a growing sector of the global population as medical developments have advanced human mortality rates across the world. Our current understanding of frailty is derived from studies conducted in the laboratory as well as the clinic, which have generated largely phenotypic information. Far fewer studies have uncovered biological underpinnings driving the onset and progression of frailty, but the stage is set to advance the field with preclinical and clinical assessment tools, multiomics approaches together with physiological and biochemical methodologies. In this article, we provide comprehensive coverage of topics regarding frailty assessment, preclinical models, interventions, and challenges as well as clinical frameworks and prevalence. We also identify central biological mechanisms that may be at play including mitochondrial dysfunction, epigenetic alterations, and oxidative stress that in turn, affect metabolism, stress responses, and endocrine and neuromuscular systems. We review the role of metabolic syndrome, insulin resistance and visceral obesity, focusing on glucose homeostasis, adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and nicotinamide adenine dinucleotide (NAD⁺ ) as critical players influencing the age-related loss of health. We further focus on how immunometabolic dysfunction associates with oxidative stress in promoting sarcopenia, a key contributor to slowness, weakness, and fatigue. We explore the biological mechanisms involved in stem cell exhaustion that affect regeneration and may contribute to the frailty-associated decline in resilience and adaptation to stress. Together, an overview of the interplay of aging biology with genetic, lifestyle, and environmental factors that contribute to frailty, as well as potential therapeutic targets to lower risk and slow the progression of ongoing disease is covered. © 2022 American Physiological Society. Compr Physiol 12:1-46, 2022.

Preclinical frailty assessments: Phenotype and frailty index identify frailty in different mice and are variably affected by chronic medications

Use of different objective frailty assessment tools may improve understanding of the biology of frailty and allow evaluation of effects of interventions on frailty. Polypharmacy is associated with increased risk of frailty in epidemiologic studies, regardless of frailty definition, but the pathophysiology of the association is not well understood. This study aims to (1) assess and compare the prevalence of frailty from middle to old age following control, chronic polypharmacy or monotherapy treatment, when measured using the clinical frailty index assessment and the mouse frailty phenotype tools; and (2) to evaluate and compare the effects of chronic polypharmacy regimens with zero, low and high Drug Burden Index (DBI) and monotherapies from middle to old age on the rate of deficit accumulation on the frailty index, mean number of phenotype criteria, odds of being frail assessed by the frailty index or phenotype, and the time to onset of frailty assessed by the frailty index or phenotype. In a longitudinal study, middle-aged (12 months) male C57BL/6J(B6) mice were administered non medicated control feed and water, or therapeutic doses of different polypharmacy combinations or monotherapies in feed and/or water. Frailty assessments were performed at 12, 15, 18, 21 and 24 months. There was limited overlap between animals identified as frail using different frailty assessments. Polypharmacy has measurable and different effects on each frailty assessment. Long-term chronic administration of some polypharmacy and monotherapy therapeutic drug regimens increased the number of frailty deficits (clinical frailty index: low DBI polypharmacy (15 and 21 months), high DBI polypharmacy (15-21 months), oxycodone (15-18 months), oxybutynin (15-18 months), citalopram (15-21 months) and metoprolol monotherapy (15 months) and modified frailty phenotype assessment (over the whole duration of treatment, low DBI polypharmacy (adjusted Risk Ratio(aRR) = 1.97, 95% confidence interval (CI) 1.43-2.72), high DBI polypharmacy (aRR = 1.88; 95% CI 1.36-2.60), oxybutynin (aRR = 1.48; 95% CI 1.01-2.16) and citalopram monotherapy (aRR = 1.96; 95% CI 1.41-2.74), p < 0.05) . The odds of developing frailty measured with the clinical frailty index increased with high DBI polypharmacy (adjusted odds ratio (aOR) = 3.13; 95% CI 1.01-9.66) and when measured with the frailty phenotype assessment increased with low DBI polypharmacy (aOR = 4.38, 95% CI 1.40-13.74), high DBI polypharmacy (aOR = 3.43; 95% CI 1.12-10.50) and citalopram monotherapy (aOR = 4.63; 95% CI 1.39-15.54)). No treatment affected time to frailty using either frailty assessment. Analysis of the number of deficits on the frailty index or number of positive criteria on the frailty phenotype allows analysis of rate of change and provides greater sensitivity, while the odds of being frail analysis provided a clinically relevant indicator of whether mice had greater chance of reaching a cut-off for becoming frail with medication exposure than without. Our results are consistent with clinical studies, demonstrating that certain polypharmacy regimens induce frailty, with different relationships observed when using different frailty assessments and analyses.

Aerobic Exercise Attenuates Frailty in Aging Male and Female C57Bl/6 Mice and Effects Systemic Cytokines Differentially by Sex

Aerobic exercise is a promising intervention to attenuate frailty, but preclinical studies have used only male animals. We investigated the impact of voluntary aerobic exercise on frailty, biological age (FRailty Inferred Geriatric Health Timeline [FRIGHT] clock), predicted life expectancy (Analysis of FRAIlty and Death [AFRAID] clock), and mortality in both sexes and determined whether exercise was associated with changes in inflammation. Older (21-23 months) male (n = 12) and female (n = 22) C57Bl/6 mice matched for baseline frailty scores were randomized into exercise (running wheel) and sedentary (no wheel) groups. Frailty index scores were measured biweekly (13 weeks), and 23 serum cytokines were measured at midpoint and end point. Exercise levels varied between mice but not between the sexes. Exercise had no effect on mortality, but it attenuated the development of frailty in both sexes (female = 0.32 ± 0.04 vs 0.21 ± 0.01; p = .005; male = 0.30 ± 0.02 vs 0.22 ± 0.02; p = .042) and reduced frailty in older females after 10 weeks. FRIGHT scores were unaffected by exercise but increased with time in sedentary males indicating increased biological age. Exercise prevented the age-associated decline in AFRAID scores in older females such that exercised females had a longer life expectancy. We investigated whether aerobic exercise was associated with changes in systemic inflammation. Cytokine levels were not affected by exercise in males, but levels of pro-inflammatory cytokines were positively correlated with the frequency of exercise in females. Despite increases in systemic inflammation, exercise reduced frailty and increased life span in older females. Thus, voluntary aerobic exercise, even late in life, has beneficial effects on health in both sexes but may be especially helpful in older females.

Frailty in ethnic minority women

In majority populations in high- and middle-income countries, women live longer yet experience higher levels of frailty than men of the same age. It is unclear whether this 'sex-frailty paradox' is present in ethnic minority populations. In this narrative review, we explore biological, behavioural and social factors associated with mortality, morbidity and frailty in women, particularly ethnic minority women. We ascertain that natural menopause occurs earlier in women of particular ethnicities. Ethnic minority women (living in high-income countries) have more children and higher rates of chronic disease and disability, all of which are associated with frailty. In some ethnic minorities, women are less likely to engage in deleterious health behaviours such as smoking and alcohol consumption. However, in others the reverse is true. Women from migrant ethnic minorities tend to have lower levels of physical activity. With time, they can also adopt adverse behavioural patterns of the majority population. Although the evidence is sparse, sex differences in health reporting and social assets, as well as gender roles, are likely to contribute to sex differences in frailty in ethnic minorities. Overall, ethnic minority women are a particularly vulnerable group, but the majority of risk factors for frailty appear to be mutable rather than fixed. Future research may examine interventions that target frailty in different races and ethnicities at individual, population and global levels.

Sex Differences in the Relation Between Frailty and Endothelial Dysfunction in Old Mice

Vascular endothelial function declines with age on average, but there is high variability in the magnitude of this decline within populations. Measurements of frailty, known as frailty index (FI), can be used as surrogates for biological age, but it is unknown if frailty relates to the age-related decline in vascular function. To examine this relation, we studied young (4-9 months) and old (23-32 months) C57BL6 mice of both sexes. We found that FI was greater in old compared with young mice, but did not differ between old male and female mice. Middle cerebral artery (MCA) and mesenteric artery endothelium-dependent dilation (EDD) also did not differ between old male and female mice; however, there were sex differences in the relations between FI and EDD. For the MCA, FI was inversely related to EDD among old female mice, but not old male mice. In contrast, for the mesenteric artery, FI was inversely related to EDD among old male mice, but not old female mice. A higher FI was related to a greater improvement in EDD with the superoxide scavenger TEMPOL in the MCAs for old female mice and in the mesenteric arteries for old male mice. FI related to mesenteric artery gene expression negatively for extracellular superoxide dismutase (Sod3) and positively for interleukin-1β (Il1b). In summary, we found that the relation between frailty and endothelial function is dependent on sex and the artery examined. Arterial oxidative stress and pro-inflammatory signaling are potential mediators of the relations of frailty and endothelial function.

The degree of frailty as a translational measure of health in aging

Frailty is a multiply determined, age-related state of increased risk for adverse health outcomes. We review how the degree of frailty conditions the development of late-life diseases and modifies their expression. The risks for frailty range from subcellular damage to social determinants. These risks are often synergistic-circumstances that favor damage also make repair less likely. We explore how age-related damage and decline in repair result in cellular and molecular deficits that scale up to tissue, organ and system levels, where they are jointly expressed as frailty. The degree of frailty can help to explain the distinction between carrying damage and expressing its usual clinical manifestations. Studying people-and animals-who live with frailty, including them in clinical trials and measuring the impact of the degree of frailty are ways to better understand the diseases of old age and to establish best practices for the care of older adults.

Sex differences in frailty: Comparisons between humans and preclinical models

Frailty can be viewed as a state of physiological decline that increases susceptibility to adverse health outcomes. This loss of physiological reserve means that even small stressors can lead to disability and death in frail individuals. Frailty can be measured with various clinical tools; the two most popular are the frailty index and the frailty phenotype. Clinical studies have used these tools to show that women are frailer than men even though they have longer lifespans. Still, factors responsible for this frailty-mortality paradox are not well understood. This review highlights evidence for male-female differences in frailty from both the clinical literature and in animal models of frailty. We review evidence for higher frailty levels in female animals as seen in many preclinical models. Mechanisms that may contribute to sex differences in frailty are highlighted. In addition, we review work that suggests frailty may play a role in susceptibility to chronic diseases of aging in a sex-specific fashion. Additional mechanistic studies in preclinical models are needed to understand factors involved in male-female differences in frailty in late life.

Maladaptive Changes Associated With Cardiac Aging Are Sex-Specific and Graded by Frailty and Inflammation in C57BL/6 Mice

We investigated whether late-life changes in cardiac structure and function were related to high levels of frailty and inflammation in male and female mice. Frailty (frailty index), ventricular structure/function (echocardiography), and serum cytokines (multiplex immunoassay) were measured in 16- and 23-month-old mice. Left ventricular (LV) mass and septal wall thickness increased with age in both sexes. Ejection fraction increased with age in males (60.4 ± 1.4 vs 68.9 ± 1.8%; p < .05) but not females (58.8 ± 2.5 vs 62.6 ± 2.4%). E/A ratios declined with age in males (1.6 ± 0.1 vs 1.3 ± 0.1; p < .05) but not females (1.4 ± 0.1 vs 1.3 ± 0.1) and this was accompanied by increased ventricular collagen levels in males. These changes in ejection fraction (r = 0.52; p = .01), septal wall thickness (r = 0.59; p = .002), E/A ratios (r = -0.49; p = .04), and fibrosis (r = 0.82; p = .002) were closely graded by frailty scores in males. Only septal wall thickness and LV mass increased with frailty in females. Serum cytokines changed modestly with age in both sexes. Nonetheless, in males, E/A ratios, LV mass, LV posterior wall thickness, and septal wall thickness increased as serum cytokines increased (eg, IL-6, IL-3, IL-1α, IL-1β, tumor necrosis factor-α, eotaxin, and macrophage inflammatory protein-1α), while ejection fraction declined with increasing IL-3 and granulocyte-macrophage colony stimulating factor. Cardiac outcomes were not correlated with inflammatory cytokines in females. Thus, changes in cardiac structure and function in late life are closely graded by both frailty and markers of inflammation, but this occurs primarily in males. This suggests poor overall health and inflammation drive maladaptive changes in older male hearts, while older females may be resistant to these adverse effects of frailty.

Improved assessment of overall health in variably aged murine models of Multiple Sclerosis with a novel frailty index tool

The experimental autoimmune encephalomyelitis (EAE) model is the most commonly used animal model of Multiple Sclerosis (MS). However, phenotypic characterization of mice based on the traditional 5-point clinical paralysis scale does not fully capture disease progression. The frailty index (FI) conceptualizes frailty as the accumulation of health deficits and it is widely used to assess overall health in aging humans and pre-clinical models. Here we adapted an established mouse FI tool for use in EAE mice and determined whether this could evaluate general signs of health in variably aged female EAE mice. The EAE-Clinical FI included 34 items related to clinical signs and deficits characteristic of aging and MS. This tool clearly showed more detailed EAE progression and severity at all ages, highlighting changes in systems other than motor paralysis measured with the traditional 5-point paralysis scale. When we induced disease at 3- and 6-months-of-age, mice showed typical EAE clinical manifestations with peak disease severity between 17-19 days post-induction and mean frailty scores of 0.36 ± 0.04 (3-month-old) and 0.43 ± 0.05 (6-month-old). By contrast, disease severity peaked after 14 days in 12-month-old mice. They showed atypical signs including wobbling, early belly drag, and splayed hindlegs that were better captured with the EAE-Clinical FI. Peak frailty scores also were higher than those of younger animals (0.54 ± 0.04). As MS most often develops in young to middle-aged people, this new tool may have significant value for use in EAE animal studies as first step towards translation to people with MS.

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.

Peripheral IL-6 Levels but not Sarcopenia Are Predictive of 1-Year Mortality After Hip Fracture in Older Patients

BACKGROUND

Sarcopenic patients may have an increased risk of poor outcomes after a hip fracture. The objective of this study was to determine whether sarcopenia and a set of biomarkers were potential predictors of 1-year-mortality in older patients after a hip fracture.

METHODS

About 150 patients at least 80 years old were hospitalized for the surgical treatment of a hip fracture. The primary outcome measure was the death in the first year after the hip fracture. Sarcopenia was defined at baseline by having both low muscle mass (bioimpedance analysis) and handgrip and using the updated European Working Group on Sarcopenia in Older People (EWGSOP2) definition of probable sarcopenia. Janssen's (J) and Masanés (M) cutoff points were used to define low muscle mass.

RESULTS

Mortality 1 year after the hip fracture was 11.5%. In univariate analyses, baseline sarcopenia was not associated with mortality, using neither of the muscle mass cutoff points: 5.9% in sarcopenic (J) versus 12.4% in non-sarcopenic participants (p = .694) and 16% in sarcopenic (M) versus 9.6% in non-sarcopenic participants (p = .285). Probable sarcopenia (EWGSOP2) was not associated with mortality. Peripheral levels of IL-6 at baseline were significantly higher in the group of participants who died in the year after the hip fracture (17.14 ± 16.74 vs 11.42 ± 7.99 pg/mL, p = .026). TNF-α peripheral levels had a nonsignificant trend to be higher in participants who died. No other biomarker was associated with mortality.

CONCLUSIONS

Sarcopenia at baseline was not a predictor of 1-year mortality in older patients after a hip fracture. IL-6 was associated with a higher risk of mortality in these patients, regardless of sarcopenia status.

Preclinical models of frailty: Focus on interventions and their translational impact: A review

The concept of frailty refers to heterogeneity in the risk of adverse outcomes for people of the same age. It is traditionally thought of as the inability of the body to maintain homeostasis. It can help explain differences between chronological and biological age and can quantify healthspan in experimental studies. Although clinical studies have developed tools to quantify frailty over the past two decades, preclinical models of frailty have only recently been introduced. This review describes the notion of frailty and outlines two commonly used clinical approaches to quantify frailty: the frailty phenotype and the frailty index. Translation of these methodologies for use in animals is introduced and studies that use these models to evaluate interventions designed to attenuate or exacerbate frailty are discussed. These include studies involving manipulation of diet, implementation of exercise regimens and tests of pharmaceutical agents to exacerbate or attenuate frailty. Together, this body of work suggests that preclinical frailty assessment tools are a valuable new resource to quantify the impact of interventions on overall health. Future studies could deploy these models to evaluate new frailty therapies, test combinations of interventions and assess interventions to enhance the ability to resist stressors in the setting of ageing.

Identifying Characteristics of Frailty in Female Mice Using a Phenotype Assessment Tool

Preclinical studies are important in identifying the underlying mechanisms contributing to frailty. Frailty studies have mainly focused on male rodents with little directed at female rodents. Therefore, the purposes of this study were to identify the onset and prevalence of frailty across the life span in female mice, and to determine if frailty predicts mortality. Female C57BL/6 (n = 27) mice starting at 17 months of age were assessed across the life span using a frailty phenotype, which included body weight, walking speed, strength, endurance, and physical activity. The onset of frailty occurred at approximately 17 months (1/27 mice), with the prevalence of frailty increasing thereafter. At 17 months, 11.1% of the mice were pre-frail and by 26 months peaked at 36.9%. The percentage of frail mice progressively increased up to 66.7% at 32 months. Non-frail mice lived to 29 months whereas frail/pre-frail mice lived only to 26 months (p = .04). In closing, using a mouse frailty phenotype, we are able to identify that the prevalence of frailty in female mice increases across the life span and accurately predicts mortality. Together, this frailty phenotype has the potential to yield information about the underlying mechanisms contributing to frailty.

SS-31 and NMN: Two paths to improve metabolism and function in aged hearts

The effects of two different mitochondrial-targeted drugs, SS-31 and NMN, were tested on Old mouse hearts. After treatment with the drugs, individually or Combined, heart function was examined by echocardiography. SS-31 partially reversed an age-related decline in diastolic function while NMN fully reversed an age-related deficiency in systolic function at a higher workload. Metabolomic analysis revealed that both NMN and the Combined treatment increased nicotinamide and 1-methylnicotinamide levels, indicating greater NAD+ turnover, but only the Combined treatment resulted in significantly greater steady-state NAD(H) levels. A novel magnetic resonance spectroscopy approach was used to assess how metabolite levels responded to changing cardiac workload. PCr/ATP decreased in response to increased workload in Old Control, but not Young, hearts, indicating an age-related decline in energetic capacity. Both drugs were able to normalize the PCr/ATP dynamics. SS-31 and NMN treatment also increased mitochondrial NAD(P)H production under the higher workload, while only NMN increased NAD+ in response to increased work. These measures did not shift in hearts given the Combined treatment, which may be owed to the enhanced NAD(H) levels in the resting state after this treatment. Overall, these results indicate that both drugs are effective at restoring different aspects of mitochondrial and heart health and that combining them results in a synergistic effect that rejuvenates Old hearts and best recapitulates the Young state.

Age and life expectancy clocks based on machine learning analysis of mouse frailty

The identification of genes and interventions that slow or reverse aging is hampered by the lack of non-invasive metrics that can predict the life expectancy of pre-clinical models. Frailty Indices (FIs) in mice are composite measures of health that are cost-effective and non-invasive, but whether they can accurately predict health and lifespan is not known. Here, mouse FIs are scored longitudinally until death and machine learning is employed to develop two clocks. A random forest regression is trained on FI components for chronological age to generate the FRIGHT (Frailty Inferred Geriatric Health Timeline) clock, a strong predictor of chronological age. A second model is trained on remaining lifespan to generate the AFRAID (Analysis of Frailty and Death) clock, which accurately predicts life expectancy and the efficacy of a lifespan-extending intervention up to a year in advance. Adoption of these clocks should accelerate the identification of longevity genes and aging interventions.

Considering Cause and Effect of Immune Cell Aging on Cardiac Repair after Myocardial Infarction

The importance of the immune system for cardiac repair following myocardial infarction is undeniable; however, the complex nature of immune cell behavior has limited the ability to develop effective therapeutics. This limitation highlights the need for a better understanding of the function of each immune cell population during the inflammatory and resolution phases of cardiac repair. The development of reliable therapies is further complicated by aging, which is associated with a decline in cell and organ function and the onset of cardiovascular and immunological diseases. Aging of the immune system has important consequences on heart function as both chronic cardiac inflammation and an impaired immune response to cardiac injury are observed in older individuals. Several studies have suggested that rejuvenating the aged immune system may be a valid therapeutic candidate to prevent or treat heart disease. Here, we review the basic patterns of immune cell behavior after myocardial infarction and discuss the autonomous and nonautonomous manners of hematopoietic stem cell and immune cell aging. Lastly, we identify prospective therapies that may rejuvenate the aged immune system to improve heart function such as anti-inflammatory and senolytic therapies, bone marrow transplant, niche remodeling and regulation of immune cell differentiation.

Complementing chronic frailty assessment at hospital admission with an electronic frailty index (FI-Laboratory) comprising routine blood test results

BACKGROUND

Acutely ill and frail older adults have complex social and health care needs. It is important to understand how this complexity affects acute outcomes for admission to hospital. We validated a frailty index using routine admission laboratory tests with outcomes after patients were admitted to hospital.

METHODS

In a prospective cohort of older adults admitted to a large tertiary hospital in the United Kingdom, we created a frailty index from routine admission laboratory investigations (FI-Laboratory) linked to data comprising hospital outcomes. We evaluated the association between the FI-Laboratory and total days spent in hospital, discharge to a higher level of care, readmission and mortality.

RESULTS

Of 2552 admissions among 1750 older adults, we were able to generate FI-Laboratory values for 2254 admissions (88.3% of the cohort). More than half of admitted patients were women (55.3%) and the mean age was 84.6 (SD 14.0) years. We found that the FI-Laboratory correlated weakly with the Clinical Frailty Scale (CFS; r ² = 0.09). An increase in the CFS and the equivalent of 3 additional abnormal laboratory test results in the FI-Laboratory, respectively, were associated with an increased proportion of inpatient days (rate ratios [RRs] 1.43, 95% confidence interval [CI] 1.35-1.52; and 1.47, 95% CI 1.41-1.54), discharge to a higher level of care (odd ratios [ORs] 1.39, 95% CI 1.27-1.52; and 1.30, 95% CI 1.16-1.47) and increased readmission rate (hazard ratios [HRs] 1.26, 95% CI 1.17-1.37; and 1.18, 95% CI 1.11-1.26). Increases in the CFS and FI-Laboratory were associated with increased mortality HRs of 1.39 (95% CI 1.28-1.51) and 1.45 (95% CI 1.37-1.54), respectively.

INTERPRETATION

We determined that FI-Laboratory, distinct from baseline frailty, could be used to predict risk of many adverse outcomes. The score is therefore a useful way to quantify the degree of acute illness in frail older adults.

Chronic Treatment With the ACE Inhibitor Enalapril Attenuates the Development of Frailty and Differentially Modifies Pro- and Anti-inflammatory Cytokines in Aging Male and Female C57BL/6 Mice

Studies on interventions that can delay or treat frailty in humans are limited. There is evidence of beneficial effects of angiotensin converting enzyme (ACE) inhibitors on aspects related to frailty, such as physical function, even in those without cardiovascular disease. This study aimed to longitudinally investigate the effect of an ACE inhibitor on frailty in aging male and female mice. Frailty was assessed with a clinical frailty index (FI) which quantifies health-related deficits in middle-aged (9-13 months) and older (16-25 months) mice. Chronic treatment with enalapril (30 mg/kg/day in feed) attenuated frailty in middle-aged and older female mice, and older male mice, without a long-term effect on blood pressure. Enalapril treatment resulted in a reduction in the proinflammatory cytokines interleukin (IL)-1α, monocyte chemoattractant protein-1 and macrophage inflammatory protein-1a in older female mice, and an increase in the anti-inflammatory cytokine IL-10 in older male mice compared with control animals. These sex-specific effects on inflammation may contribute to the protective effects of enalapril against frailty. This is the first study to examine the longitudinal effect of an intervention on the FI in mice, and provides preclinical evidence that enalapril may delay the onset of frailty, even when started later in life.

A toolbox for the longitudinal assessment of healthspan in aging mice

The number of people aged over 65 is expected to double in the next 30 years. For many, living longer will mean spending more years with the burdens of chronic diseases such as Alzheimer's disease, cardiovascular disease, and diabetes. Although researchers have made rapid progress in developing geroprotective interventions that target mechanisms of aging and delay or prevent the onset of multiple concurrent age-related diseases, a lack of standardized techniques to assess healthspan in preclinical murine studies has resulted in reduced reproducibility and slow progress. To overcome this, major centers in Europe and the United States skilled in healthspan analysis came together to agree on a toolbox of techniques that can be used to consistently assess the healthspan of mice. Here, we describe the agreed toolbox, which contains protocols for echocardiography, novel object recognition, grip strength, rotarod, glucose tolerance test (GTT) and insulin tolerance test (ITT), body composition, and energy expenditure. The protocols can be performed longitudinally in the same mouse over a period of 4-6 weeks to test how candidate geroprotectors affect cardiac, cognitive, neuromuscular, and metabolic health.

Nutrition interventions for healthy ageing across the lifespan: a conference report

Thanks to advances in modern medicine over the past century, the world’s population has experienced a marked increase in longevity. However, disparities exist that lead to groups with both shorter lifespan and significantly diminished health, especially in the aged. Unequal access to proper nutrition, healthcare services, and information to make informed health and nutrition decisions all contribute to these concerns. This in turn has hastened the ageing process in some and adversely affected others’ ability to age healthfully. Many in developing as well as developed societies are plagued with the dichotomy of simultaneous calorie excess and nutrient inadequacy. This has resulted in mental and physical deterioration, increased non-communicable disease rates, lost productivity and quality of life, and increased medical costs. While adequate nutrition is fundamental to good health, it remains unclear what impact various dietary interventions may have on improving healthspan and quality of life with age. With a rapidly ageing global population, there is an urgent need for innovative approaches to health promotion as individual’s age. Successful research, education, and interventions should include the development of both qualitative and quantitative biomarkers and other tools which can measure improvements in physiological integrity throughout life. Data-driven health policy shifts should be aimed at reducing the socio-economic inequalities that lead to premature ageing. A framework for progress has been proposed and published by the World Health Organization in its Global Strategy and Action Plan on Ageing and Health. This symposium focused on the impact of nutrition on this framework, stressing the need to better understand an individual’s balance of intrinsic capacity and functional abilities at various life stages, and the impact this balance has on their mental and physical health in the environments they inhabit.

Retinol-binding protein 4 (RBP4), a potential biomarker of frailty in HIV-infected people on stable antiretroviral therapy

OBJECTIVES

A quantitative biomarker for identification of pre-frail and frail persons is still lacking. This study aimed to identify biomarker predictors of frailty in HIV-infected patients.

METHODS

A cross-sectional study of HIV-infected patients who had been on antiretroviral therapy (ART) for at least 1 year and who presented an undetectable viral load (< 50 HIV-1 RNA copies/mL) at baseline was carried out. For each frail patient, up to four pre-frail and robust patients were randomly selected. The frailty status assessment was based on the five-item criteria described by Fried et al. Sociodemographic, anthropometric, biochemical and HIV-related characteristics were evaluated. Multiple potential biomarkers of frailty and a biological age biomarker were analysed.

RESULTS

A total of 73 HIV-infected patients on ART for at least 1 year were evaluated. The patients were categorized as robust (n = 33), pre-frail (n = 32) and frail (n = 8) using the Fried criteria. All patients were on ART, with 100% undetectable viral load (< 50 copies/mL) at baseline. No significant differences in demographic, clinical or analytical characteristics were observed among patients in the different categories based on Fried criteria, with the exception of the veterans aging cohort study index (VACS). Similarly, no differences were observed in HIV-related characteristics, although nucleoside reverse transcriptase inhibitor (NRTI) use was less common in frail persons. The distribution of biomarker values varied according to frailty status, with frail persons having higher levels of interleukin (IL)-8, IL-18, CXC chemokine ligand 10 (CXCL10) and retinol-binding protein 4 (RBP4). In multivariable analysis, the assocation of frailty with RBP4 showed a tendency to statistical significance (odds ratio 1.0; 95% confidence interval 0.99-1.00; P < 0.05).

CONCLUSIONS

Differential biomarker expression was present according to Fried status. Longitudinal studies will clarify the utility of these biomarkers as targets for diagnostic or therapeutic intervention.

A Frailty Index based on clinical data to quantify mortality risk in dogs

Frailty is defined as a decline in an organism’s physiological reserves resulting in increased vulnerability to stressors. In humans, a single continuous variable, the so-called Frailty Index (FI), can be obtained by multidimensionally assessing the biological complexity of an ageing organism. Here, we evaluate this variability in dogs and compare it to the data available for humans. In dogs, there was a moderate correlation between age and the FI, and the distribution of the FI increased with age. Deficit accumulation was strongly related to mortality. The effect of age, when combined with the FI, was negligible. No sex-related differences were evident. The FI could be considered in epidemiological studies and/or experimental trials to account for the potential confounding effects of the health status of individual dogs. The age-related deficit accumulation reported in dogs is similar to that demonstrated in humans. Therefore, dogs might represent an excellent model for human aging studies.

Bed rest and accelerated aging in relation to the musculoskeletal and cardiovascular systems and frailty biomarkers: A review

Prolonged bed rest and lifelong physical inactivity cause deleterious effects to multiple physiological systems that appear to hasten aging processes. Many such changes are similar to those seen with microgravity in space, but at a much faster rate. Head down tilt bed rest models are used to study whole-body changes that occur with spaceflight. We propose that bed rest can be used to quantify accelerated human aging in relation to frailty. In particular, frailty as a measure of the accumulation of deficits estimates the variability in aging across systems, and moves away from the traditional single-system approach. Here, we provide an overview of the impact of bed rest on the musculoskeletal and cardiovascular systems as well as frailty-related biological markers and inflammatory cytokines. We also propose future inquiries to study the accumulation of deficits with head down bed rest and bed rest in the clinical setting, specifically to understand how unrepaired and unremoved subclinical and subcellular damage give rise to clinically observable health problems.

Frailty biomarkers in humans and rodents: Current approaches and future advances

Even though they would have great benefit across research and clinical fields, currently there are no accepted biomarkers of frailty. Cross-sectional studies in humans have identified promising candidates including inflammatory markers such as IL-6, immune markers such as WBC count, clinical markers such as albumin, endocrine markers such as vitamin D, oxidative stress markers such as isoprostanes, proteins such as BDNF and epigenetic markers such as DNA methylation, but there are limitations to the current state of the research. Future approaches to the identification of frailty biomarkers should include longitudinal studies, studies using animal models of frailty, studies incorporating novel biomarkers combined into composite panels, and studies investigating sex differences and potential overlap between markers of biological age and frailty.

High intensity interval training improves physical performance in aged female mice: A comparison of mouse frailty assessment tools

Frailty syndrome increases the risk for disability and mortality, and is a major health concern amidst the geriatric shift in the population. High intensity interval training (HIIT), which couples bursts of vigorous activity interspersed with active recovery intervals, shows promise for the treatment of frailty. Here we compare and contrast five Fried physical phenotype and one deficit accumulation based mouse frailty assessment tools for identifying the impacts of HIIT on frailty and predicting functional capacity, underlying pathology, and survival in aged female mice. Our data reveal a 10-minute HIIT regimen administered 3-days-a-week for 8-weeks increased treadmill endurance, gait speed and maintained grip strength. One frailty tool identified a benefit of HIIT for frailty, but many were trending suggesting HIIT was beneficial for physical performance in these mice, but the 8-week timeframe may have been insufficient to induce frailty benefits. Finally, most frailty tools distinguished between surviving or non-surviving mice, whereas half correlated with functional capacity measured by nest building ability, and none correlated with underlying pathology. In summary, this study supports the ongoing development of mouse assessment tools as useful instruments for frailty research.

The biology of frailty in humans and animals: Understanding frailty and promoting translation

Frailty is a state of high vulnerability to adverse health outcomes. This concept is used to explain the heterogeneity in rates of aging in people of the same age. Frailty has important clinical implications, because even minor stressors can lead to adverse outcomes, including death, in frail individuals. Although frailty mechanisms are not well understood, advances in our ability to qualify frailty have encouraged efforts in this area. Quantification of frailty with both "frailty phenotype" and "frailty index" approaches has begun to highlight putative frailty mechanisms and new animal models of frailty are inspiring preclinical research. These models either adapt frailty phenotype and frailty index tools for use in animals or they use genetically manipulated mice that mimic conditions seen in frailty (eg, inflammation, sarcopenia, weakness). This review: describes commonly used tools to quantify frailty clinically, discusses potential frailty mechanisms, and describes animal models of frailty. It also highlights how these models have been used to explore frailty mechanisms and potential frailty interventions, including pharmacological treatments, diet, and exercise. These exciting new developments in the field have the potential to facilitate translational research, improve our understanding of mechanisms of frailty, and help develop new interventions to mitigate frailty in our aging population.