Association of cardiovascular fibrosis, remodeling, and dysfunction with frailty, pre-frailty, and functional performance: the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND

Cardiovascular disease is associated with higher incidence of frailty. However, the nature of the mechanisms underlying this association remain unclear. The purpose of this study is to identify cardiovascular phenotypes most associated with physical frailty and functional performance in the Multi-Ethnic Study of Atherosclerosis (MESA).

METHODS

As part of the MESA study, 3045 participants underwent cardiovascular magnetic resonance and computed tomography between 2010-2012. Of these, 1743 completed a Six-Minute Walk test (6MWT) and questionnaires (follow-up Exam: 2016-2018) which were used to generate a binary combined frail/prefrail vs. robust score according to a modified FRAIL Scale (self-report questionnaire). Multivariable logistic (binary frail outcome) or linear (6MWT) regression assessed the association between frailty and cardiovascular structure and function, aortic stiffness, coronary artery calcium, and myocardial fibrosis (ECV, extracellular volume fraction).

RESULTS

Participants were 66±8yrs, 52% female at the time of imaging, and 29.4% were classified as frail or pre-frail. Older age and female gender were associated with greater odds of being in the frail/prefrail group. Concentric left ventricular remodeling (OR 1.89,p=0.008; Coef. -52.9,p<0.001), increased ECV (OR 1.10,p=0.002; Coef. -4.0,p=0.001), and worsening left atrial strain rate at early diastole (OR 1.56,p=<0.001; Coef. -22.75,p=0.027) were found to be associated with a greater likelihood of being in a frail state and lower 6MWT distance (m) . All associations with 6MWT performance were attenuated with adjustments for risk factors while ECV and LA strain rate remained independently associated with frailty.

CONCLUSIONS

These findings suggest a significant overlap in pathways associated with subclinical cardiac dysfunction, cardiovascular fibrosis and physical frailty.

Single-cell morphology encodes functional subtypes of senescence in aging human dermal fibroblasts

Cellular senescence is an established driver of aging, exhibiting context-dependent phenotypes across multiple biological length-scales. Despite its mechanistic importance, profiling senescence within cell populations is challenging. This is in part due to the limitations of current biomarkers to robustly identify senescent cells across biological settings, and the heterogeneous, non-binary phenotypes exhibited by senescent cells. Using a panel of primary dermal fibroblasts, we combined live single-cell imaging, machine learning, multiple senescence induction conditions, and multiple protein-based senescence biomarkers to show the emergence of functional subtypes of senescence. Leveraging single-cell morphologies, we defined eleven distinct morphology clusters, with the abundance of cells in each cluster being dependent on the mode of senescence induction, the time post-induction, and the age of the donor. Of these eleven clusters, we identified three bona-fide senescence subtypes (C7, C10, C11), with C10 showing the strongest age-dependence across a cohort of fifty aging individuals. To determine the functional significance of these senescence subtypes, we profiled their responses to senotherapies, specifically focusing on Dasatinib + Quercetin (D+Q). Results indicated subtype-dependent responses, with senescent cells in C7 being most responsive to D+Q. Altogether, we provide a robust single-cell framework to identify and classify functional senescence subtypes with applications for next-generation senotherapy screens, and the potential to explain heterogeneous senescence phenotypes across biological settings based on the presence and abundance of distinct senescence subtypes.

Using Photovoice to Explore the Lived Environment and Experience of Older Adults with Frailty on their Kidney Transplant Journey

Key Points

Photovoice, a qualitative method, visually depicted the daily lives of participants with frailty, providing insights into independence and symptom management to guide clinicians and researchers. This photovoice study uncovered subthemes of home safety and organization, revealing potential safety hazards like dialysis fluid storage, and suggests its potential use in geriatric nephrology. The findings emphasize the importance of integrating participant values and goals into care decisions and interventional design in the context of kidney transplant journeys for frail adults.

Background

Older adults with frailty and kidney failure face higher waitlist mortality and are more likely to be listed as inactive on the kidney transplant (KT) waitlist. Photovoice is a qualitative participatory research method where participants use photographs to represent their environment, needs, and experiences. It offers unique insight into the lived environment and experience of patients and may offer direction in how to improve functional independence, symptom burden, and KT outcomes in adults with frailty.

Methods

This photovoice study was embedded within a larger intervention adaptation project. Participants with prefrailty or frailty awaiting a KT or recently post-transplant took photographs with Polaroid cameras and wrote short descriptions for 11 prompts. Each participant completed a semistructured interview wherein their photographs were discussed. The team coded and discussed photographs and interviews to determine overarching themes and implications. Focus groups were used to triangulate visual data findings.

Results

Sixteen participants completed both the photovoice and the interview. Participants were a mean age of 60.5 years, 31.2% female, 43.4% self-identifying as Black, and 69% were frail. Outcomes were categorized into seven themes: functional space, home safety, medication management, adaptive coping, life-changing nature of dialysis, support, and communication. Visual data clarified and sometimes changed the interpretations of the text alone. Especially within the themes of home safety and functional space, safety hazards not previously recognized in the literature, like dialysis fluid storage, were identified.

Conclusions

Photovoice contextualizes the living conditions and experiences of adults with frailty on the KT journey and could be a useful tool in geriatric nephrology and transplant. Addressing issues of home storage, organization, and accessibility should be explored as potential intervention targets. Incorporating participant values and goals into care decisions and interventional design should be further explored.

Soluble TNFR1 has greater reproducibility than IL-6 for the assessment of chronic inflammation in older adults: the case for a new inflammatory marker in aging

Chronic inflammatory pathway activation, commonly referred to as "Inflammaging" or chronic inflammation (CI), is associated with frailty, cognitive and functional decline, and other causes of health span decline in older adults. We investigated the variability of candidate serum measures of CI among community-dwelling older adults selected for mild low-grade inflammation. We focused on serum cytokines known to be highly predictive of adverse health outcomes in older adults (sTNFR1, IL-6) during a short-term (weeks) and medium-term (months) follow-up, as well as immune markers that are less studied in aging but reflect other potentially relevant domains such as adaptive immune activation (sCD25), innate immune activation (sCD14 and sCD163), and the inflammation-metabolism interface (adiponectin/Acrp30) during short-term (weeks) follow up. We found that sTNFR1 was more reproducible than IL-6 over a period of weeks and months short-term and medium-term. The intra-class correlation coefficient (ICC) for sTNFR1 was 0.95 on repeated measures over 6 weeks, and 0.79 on repeated measures with mean interval of 14 weeks, while the ICC for IL-6 was 0.52 over corresponding short-term and 0.67 over corresponding medium-term follow-up. This suggests that sTNFR1 is a more reliable marker of CI than IL-6. This study provides new insights into the reproducibility of serum markers of CI in older adults. The findings suggest that sTNFR1 may be a better marker of CI than IL-6 in this population. Further studies are needed to confirm these findings and to investigate the clinical utility of sTNFR1 in older adults.

Unlocking the protective potential of the angiotensin type 2 receptor (AT2R) in acute lung injury and age-related pulmonary dysfunction

Despite its known importance in the cardiovascular system, the specific role and impact of the angiotensin type 2 receptor (AT2R) in lung physiology and pathophysiology remain largely elusive. In this study, we highlight the distinct and specialized lung-specific roles of AT2R, primarily localized to an alveolar fibroblast subpopulation, in contrast to the angiotensin type 1 receptor (AT1R), which is almost exclusively expressed in lung pericytes. Evidence from our research demonstrates that the disruption of AT2R (AT2R-/y), is associated with a surge in oxidative stress and impaired lung permeability, which were further intensified by Hyperoxic Acute Lung Injury (HALI). With aging, AT2R-/y mice show an increase in oxidative stress, premature enlargement of airspaces, as well as increased mortality when exposed to hyperoxia as compared to age-matched WT mice. Our investigation into Losartan, an AT1R blocker, suggests that its primary HALI lung-protective effects are channeled through AT2R, as its protective benefits are absent in AT2R-/y mice. Importantly, a non-peptide AT2R agonist, Compound 21 (C21), successfully reverses lung oxidative stress and TGFβ activation in wild-type (WT) mice exposed to HALI. These findings suggest a possible paradigm shift in the therapeutic approach for lung injury and age-associated pulmonary dysfunction, from targeting AT1R with angiotensin receptor blockers (ARBs) towards boosting the protective function of AT2R.

Late-life plasma proteins associated with prevalent and incident frailty: A proteomic analysis

Proteomic approaches have unique advantages in the identification of biological pathways that influence physical frailty, a multifactorial geriatric syndrome predictive of adverse health outcomes in older adults. To date, proteomic studies of frailty are scarce, and few evaluated prefrailty as a separate state or examined predictors of incident frailty. Using plasma proteins measured by 4955 SOMAmers in the Atherosclerosis Risk in Community study, we identified 134 and 179 proteins cross-sectionally associated with prefrailty and frailty, respectively, after Bonferroni correction (p < 1 × 10-5 ) among 3838 older adults aged ≥65 years, adjusting for demographic and physiologic factors and chronic diseases. Among them, 23 (17%) and 82 (46%) were replicated in the Cardiovascular Health Study using the same models (FDR p < 0.05). Notably, higher odds of prefrailty and frailty were observed with higher levels of growth differentiation factor 15 (GDF15; pprefrailty  = 1 × 10-15 , pfrailty  = 2 × 10-19 ), transgelin (TAGLN; pprefrailty  = 2 × 10-12 , pfrailty  = 6 × 10-22 ), and insulin-like growth factor-binding protein 2 (IGFBP2; pprefrailty  = 5 × 10-15 , pfrailty  = 1 × 10-15 ) and with a lower level of growth hormone receptor (GHR, pprefrailty  = 3 × 10-16 , pfrailty  = 2 × 10-18 ). Longitudinally, we identified 4 proteins associated with incident frailty (p < 1 × 10-5 ). Higher levels of triggering receptor expressed on myeloid cells 1 (TREM1), TAGLN, and heart and adipocyte fatty-acid binding proteins predicted incident frailty. Differentially regulated proteins were enriched in pathways and upstream regulators related to lipid metabolism, angiogenesis, inflammation, and cell senescence. Our findings provide a set of plasma proteins and biological mechanisms that were dysregulated in both the prodromal and the clinical stage of frailty, offering new insights into frailty etiology and targets for intervention.

Serum and plasma protein biomarkers associated with frailty in patients with cirrhosis

Frailty, a clinical phenotype of decreased physiological reserve, is a strong determinant of adverse health outcomes in patients with cirrhosis. The only cirrhosis-specific frailty metric is the Liver Frailty Index (LFI), which must be administered in person and may not be feasible for every clinical scenario. We sought to discover candidate serum/plasma protein biomarkers that could differentiate frail from robust patients with cirrhosis. A total of 140 adults with cirrhosis awaiting liver transplantation in the ambulatory setting with LFI assessments and available serum/plasma samples were included. We selected 70 pairs of patients on opposite ends of the frailty spectrum (LFI>4.4 for frail and LFI<3.2 for robust) who were matched by age, sex, etiology, HCC, and Model for End-Stage Liver Disease-Sodium. Twenty-five biomarkers with biologically plausible associations with frailty were analyzed using ELISA by a single laboratory. Conditional logistic regression was used to examine their association with frailty. Of the 25 biomarkers analyzed, we identified 7 proteins that were differentially expressed between frail and robust patients. We observed differences in 6 of the 7 proteins in the expected direction: (a) higher median values in frail versus robust with growth differentiation factor-15 (3682 vs. 2249 pg/mL), IL-6 (17.4 vs. 6.4 pg/mL), TNF-alpha receptor 1 (2062 vs. 1627 pg/mL), leucine-rich alpha-2 glycoprotein (44.0 vs. 38.6 μg/mL), and myostatin (4066 vs. 6006 ng/mL) and (b) lower median values in frail versus robust with alpha-2-Heremans-Schmid glycoprotein (0.11 vs. 0.13 mg/mL) and free total testosterone (1.2 vs. 2.4 ng/mL). These biomarkers represent inflammatory, musculoskeletal, and endocrine/metabolic systems, reflecting the multiple physiological derangements observed in frailty. These data lay the foundation for confirmatory work and development of a laboratory frailty index for patients with cirrhosis to improve diagnosis and prognostication.

Decoding Angiotensin Receptors: TOMAHAQ-Based Detection and Quantification of Angiotensin Type-1 and Type-2 Receptors

Background The renin-angiotensin system plays a crucial role in human physiology, and its main hormone, angiotensin, activates 2 G-protein-coupled receptors, the angiotensin type-1 and type-2 receptors, in almost every organ. However, controversy exists about the location, distribution, and expression levels of these receptors. Concerns have been raised over the low sensitivity, low specificity, and large variability between lots of commercially available antibodies for angiotensin type-1 and type-2 receptors, which makes it difficult to reconciliate results of different studies. Here, we describe the first non-antibody-based sensitive and specific targeted quantitative mass spectrometry assay for angiotensin receptors. Methods and Results Using a technique that allows targeted analysis of multiple peptides across multiple samples in a single mass spectrometry analysis, known as TOMAHAQ (triggered by offset, multiplexed, accurate mass, high resolution, and absolute quantification), we have identified and validated specific human tryptic peptides that permit identification and quantification of angiotensin type-1 and type-2 receptors in biological samples. Several peptide sequences are conserved in rodents, making these mass spectrometry assays amenable to both preclinical and clinical studies. We have used this method to quantify angiotensin type-1 and type-2 receptors in postmortem frontal cortex samples of older adults (n=28) with Alzheimer dementia. We correlated levels of angiotensin receptors to biomarkers classically linked to renin-angiotensin system activation, including oxidative stress, inflammation, amyloid-β load, and paired helical filament-tau tangle burden. Conclusions These robust high-throughput assays will not only catalyze novel mechanistic studies in the angiotensin research field but may also help to identify patients with an unbalanced angiotensin receptor distribution who would benefit from angiotensin receptor blocker treatment.

A Study of Physical Resilience and Aging (SPRING): Conceptual framework, rationale, and study design

Understanding the physiological basis of physical resilience to clinical stressors is crucial for the well-being of older adults. This article presents a novel framework to discover the biological underpinnings of physical resilience in older adults as part of the "Characterizing Resiliencies to Physical Stressors in Older Adults: A Dynamical Physiological Systems Approach" study, also known as The Study of Physical Resilience and Aging (SPRING). Physical resilience, defined as the capacity of a person to withstand clinical stressors and quickly recover or improve upon a baseline functional level, is examined in adults aged 55 years and older by studying the dynamics of stress response systems. The hypothesis is that well-regulated stress response systems promote physical resilience. The study employs dynamic stimulation tests to assess energy metabolism, the hypothalamic-pituitary-adrenal axis, the autonomic nervous system, and the innate immune system. Baseline characteristics influencing resilience outcomes are identified through deep phenotyping of physical and cognitive function, as well as of biological, environmental, and psychosocial characteristics. SPRING aims to study participants undergoing knee replacement surgery (n = 100), bone and marrow transplantation (n = 100), or anticipating dialysis initiation (n = 60). Phenotypic and functional measures are collected pre-stressor and at multiple times after stressor for up to 12 months to examine resilience trajectories. By improving our understanding of physical resilience in older adults, SPRING has the potential to enhance resilient outcomes to major clinical stressors. The article provides an overview of the study's background, rationale, design, pilot phase, implementation, and implications for improving the health and well-being of older adults.

Substitution of self-reported measures for objectively assessed grip strength and slow walk in the Physical Frailty Phenotype: ramifications for validity

BACKGROUND

Frailty assessment promises to identify older adults at risk for adverse consequences following stressors and target interventions to improve health outcomes. The Physical Frailty Phenotype (PFP) is a widely-studied, well validated assessment but incorporates performance-based slow walk and grip strength criteria that challenge its use in some clinical settings. Variants replacing performance-based elements with self-reported proxies have been proposed. Our study evaluated whether commonly available disability self-reports could be substituted for the performance-based criteria in the PFP while still identifying as "frail" the same subpopulations of individuals.

METHODS

Parallel analyses were conducted in 3393 female and 2495 male Cardiovascular Health Study, Round 2 participants assessed in 1989-90. Candidate self-reported proxies for the phenotype's "slowness" and "weakness" criteria were evaluated for comparable prevalence and agreement by mode of measurement. For best-performing candidates: Frailty status (3 + positive criteria out of 5) was compared for prevalence and agreement between the PFP and mostly self-reported versions. Personal characteristics were compared between those adjudicated as frail by (a) only a self-reported version; (b) only the PFP; (c) both, using bivariable analyses and multinomial logistic regression.

RESULTS

Self-reported difficulty walking ½ mile was selected as a proxy for the phenotype's slowness criterion. Two self-reported weakness proxies were examined: difficulty transferring from a bed or chair or gripping with hands, and difficulty as just defined or in lifting a 10-pound bag. Prevalences matched to within 4% between self-reported and performance-based criteria in the whole sample, but in all cases the self-reported prevalence for women exceeded that for men by 11% or more. Cross-modal agreement was moderate, with by-criterion and frailty-wide Kappa statistics of 0.55-0.60 in all cases. Frail subgroups (a), (b), (c) were independently discriminated (p < 0.05) by race, BMI, and depression in women; by age in men; and by self-reported health for both.

CONCLUSIONS

Commonly used self-reported disability items cannot be assumed to stand in for performance-based criteria in the PFP. We found subpopulations identified as frail by resultant phenotypes versus the original phenotype to systematically differ. Work to develop self-reported proxies that more closely replicate their objective phenotypic counterparts than standard disability self-reports is needed.

Deletion of quinolinate phosphoribosyltransferase gene accelerates frailty phenotypes and neuromuscular decline with aging in a sex-specific pattern

Decline in neuromuscular function with aging is known to be a major determinant of disability and all-cause mortality in late life. Despite the importance of the problem, the neurobiology of age-associated muscle weakness is poorly understood. In a previous report, we performed untargeted metabolomics on frail older adults and discovered prominent alteration in the kynurenine pathway, the major route of dietary tryptophan degradation that produces neurotoxic intermediate metabolites. We also showed that neurotoxic kynurenine pathway metabolites are correlated with increased frailty score. For the present study, we sought to further examine the neurobiology of these neurotoxic intermediates by utilizing a mouse model that has a deletion of the quinolinate phosphoribosyltransferase (QPRT) gene, a rate-limiting step of the kynurenine pathway. QPRT-/- mice have elevated neurotoxic quinolinic acid level in the nervous system throughout their lifespan. We found that QPRT-/- mice have accelerated declines in neuromuscular function in an age- and sex-specific manner compared to control strains. In addition, the QPRT-/- mice show premature signs of frailty and body composition changes that are typical for metabolic syndrome. Our findings suggest that the kynurenine pathway may play an important role in frailty and age-associated muscle weakness.

Physical Frailty and Brain White Matter Abnormalities: The Atherosclerosis Risk in Communities Study

BACKGROUND

Physical frailty is associated with increased risk for dementia and other neurologic sequelae. However, the neurobiological changes underlying frailty and frailty risk remain unknown. We examined the association of cerebral white matter structure with current and future frailty.

METHODS

Atherosclerosis Risk in Communities Study Neurocognitive Study participants who underwent 3T brain MRI were included. Frailty status was classified according to the Fried criteria. Cerebral white matter integrity was defined using white matter hyperintensity (WMH) volume and microstructure, measured using diffusion tensor imaging fractional anisotropy (FA) and mean diffusivity (MD). Multivariable linear regression was used to relate baseline frailty to white matter structure; multivariable logistic regression was used to relate baseline white matter to frailty risk among participants nonfrail at baseline.

RESULTS

In the cross-sectional analysis (N = 1 754; mean age: 76 years), frailty was associated with greater WMH volume, lower FA, and greater MD. These associations remained consistent after excluding participants with a history of stroke or dementia. Among participants nonfrail at baseline who completed follow-up frailty assessment (N = 1 379; 6.6-year follow-up period), each standard deviation increase in WMH volume was associated with 1.46 higher odds of frailty at follow-up. Composite FA and MD measures were not associated with future frailty; however, secondary analyses found several significant white matter tract-specific associations with frailty risk.

CONCLUSION

The current study demonstrates a robust association of WMH volume with current and future frailty. Although measures of white matter microstructure were altered in frail individuals, these measures were not generally associated with progression from nonfrail to frail status.

Patterns of Daily Physical Movement, Chronic Inflammation, and Frailty Incidence

INTRODUCTION

Low physical activity is a criterion of phenotypic frailty defined as an increased state of vulnerability to adverse health outcomes. Whether disengagement from daily all-purpose physical activity is prospectively associated with frailty and possibly modified by chronic inflammation-a pathway often underlying frailty-remains unexplored.

METHODS

Using the Study to Understand Fall Reduction and Vitamin D in You data from 477 robust/prefrail adults (mean age = 76 ± 5 yr; 42% women), we examined whether accelerometer patterns (activity counts per day, active minutes per day, and activity fragmentation [broken accumulation]) were associated with incident frailty using Cox proportional hazard regression. Baseline interactions between each accelerometer metric and markers of inflammation that include interleukin-6, C-reactive protein, and tumor necrosis factor-alpha receptor 1 were also examined.

RESULTS

Over an average of 1.3 yr, 42 participants (9%) developed frailty. In Cox regression models adjusted for demographics, medical conditions, and device wear days, every 30 min·d -1 higher baseline active time, 100,000 more activity counts per day, and 1% lower activity fragmentation was associated with a 16% ( P = 0.003), 13% ( P = 0.001), and 8% ( P < 0.001) lower risk of frailty, respectively. No interactions between accelerometer metrics and baseline interleukin-6, C-reactive protein, or tumor necrosis factor-alpha receptor 1 were detected (interaction P > 0.06 for all).

CONCLUSIONS

Among older adults who are either robust or prefrail, constricted patterns of daily physical activity (i.e., lower total activity minutes and counts, and higher activity fragmentation) were prospectively associated with higher risk of frailty but not modified by frailty-related chronic inflammation. Additional studies, particularly trials, are needed to understand if this association is causal.

Metabolomics-Based Identification of Metabolic Dysfunction in Frailty

Dysregulation of energy producing metabolic pathways has been observed in older adults with frailty. In this study, we used liquid chromatography-mass spectrometry technology to identify aging- and frailty-related differences in metabolites involved in glycolysis, the tricarboxylic (TCA) cycle, and other energy metabolism-related pathways in the serum of a cohort of community-dwelling adults aged 20-97 (n = 146). We also examined the relationship between serum levels of metabolites and functional measures, physical frailty, and risk status for adverse health outcomes. We observed elevated levels of TCA cycle and glycolytic intermediates in frail subjects; however, the differences in the levels of ATP and other energy metabolites between young, nonfrail, and frail adults were not significant. Instead, we found that serum levels of neurotransmitters N-acetyl-aspartyl-glutamate, glutamate, and γ-aminobutyric acid were significantly elevated in older adults with frailty. These elevations of glycolytic and TCA cycle intermediates, and neurotransmitters may be part of the biological signature of frailty.

METABOLIC SYNDROME, GLUCOSE INTOLERANCE, AND PHYSICAL RESILIENCE

When confronted with a major physical stressor, some older adults are able to recover to baseline with minimal changes, while others undergo irreversible declines. The ability to adapt and recover well from physical stress is called physical resilience and may be impeded by altered glucose-insulin dynamics. Among 55 participants in the pilot phase of the Study of Physical Resilience IN Geriatrics(SPRING), we examined associations between metabolic syndrome and/or diabetes status to physical resiliency recovery parameters after the clinical stressors total knee replacement and bone marrow transplant. These parameters included health outcomes, functional recovery, and pain in the weeks after the intervention. Additionally, we hypothesized that less resilient individuals would have abnormal glucose and insulin responses to a 75-gram oral glucose tolerance test at 0, 30, 60, 120 minutes and tested this in a subset (n=40) without known diabetes. Exploratory analyses of this pilot study will be presented during this session.

ATIP LEVELS ARE ASSOCIATED WITH LESS AMYLOID-Β BURDEN IN POSTMORTEM BRAINS OF OLDER ADULTS WITH ALZHEIMER’S DEMENTIA

Angiotensin system, aging, and Alzheimer's disease are tightly linked. Of the brain angiotensin receptors, the subtype 2 receptor (AT2R) is relatively less studied. Canonically, the AT2R functions through nitric oxide release, and its activation has been linked to vasodilatation and neurite outgrowth as well as anti-inflammation. How AT2R signals is not known, however, an AT2R-binding protein (ATIP) has been recently described. Controversies exist on the link between ATIP and AT2R functions. Here, we describe the development of the first non-antibody based ultra-sensitive and specific quantitative mass spectrometry assay for ATIP. Using a technique that permits targeted analysis of multiple peptides across multiple samples in a single mass spectrometry run, known as TOMAHAQ, we have identified specific human tryptic peptides that permit quantification of ATIP abundance. We have used this method to quantify ATIP in postmortem frontal cortex samples of older adults (n= 60) with Alzheimer’s dementia (AD). We correlated levels of ATIP to brain RAS receptors, and biomarkers of AD pathogenesis including oxidative stress, inflammation, mitochondrial dysfunction as well as amyloid-β, and tau burden. Our results show that ATIP expression (ANLKNPQIMYLEQELESLK sequence of ATIP) is positively correlated with neuronal nitric oxide synthase (nNOS) (p = 0.009, r = 0.337). Furthermore, expression of ATIP is negatively correlated with amyloid-β load in several brain regions including hippocampus (p= 0.014, r= -0.317), entorhinal cortex (p= 0.010, r= -0.331), frontal cortex (p= 0.023, r= -0.294), and overall (p= 0.004, r= -0.365). These results highlight a potential protective role for ATIP in Alzheimer’s disease.

Losartan Mitigates Oxidative Stress in the Brains of Aged and Inflamed IL-10-/- Mice

Chronic inflammation, oxidative stress, and dysregulation of the renin-angiotensin system are closely linked, and their crosstalk commonly contributes to age-related physical and cognitive decline. The primary dementia-protective benefits of Angiotensin II type 1 receptor (AT1R) blockers are believed to arise from systemic effects on blood pressure. However, there is an independently regulated brain-specific renin-angiotensin system. Here, we examined the impact of 4 weeks of oral Losartan treatment on the brains of aged (100 weeks old) IL-10-/- mice, an animal model of chronic inflammation and frailty. Our data show that aged IL-10-/- mice have higher AT1R and Nitrotyrosine (oxidative stress marker) levels in their frontal cortex tissue but not in cerebellar or hippocampal tissue compared to age- and sex-matched wild type mice. Losartan treatment for 4 weeks is associated with lower AT1R protein level, Nitrotyrosine, and Tau protein in the frontal cortex of aged IL-10-/- mice. Our results highlight the impact of Losartan, an AT1R blocker commonly prescribed for treating high blood pressure, on the brain-specific angiotensin system and AT1R-linked downstream effects such as brain oxidative stress damage and Tau burden in a frailty mouse model.

Agreement between standard and self-reported assessments of physical frailty syndrome and its components in a registry of community-dwelling older adults

BACKGROUND

The ability to identify frail older adults using a self-reported version of the physical frailty phenotype (PFP) that has been validated with the standard PFP could facilitate physical frailty detection in clinical settings.

METHODS

We collected data from volunteers (N = 182), ages 65 years and older, in an aging research registry in Baltimore, Maryland. Measurements included: standard PFP (walking speed, grip strength, weight loss, activity, exhaustion); and self-reported questions about walking and handgrip strength. We compared objectively-measured gait speed and grip strength to self-reported questions using Cohen's Kappa and diagnostic accuracy tests. We used these measures to compare the standard PFP with self-reported versions of the PFP, focusing on a dichotomized identification of frail versus pre- or non-frail participants.

RESULTS

Self-reported slowness had fair-to-moderate agreement (Kappa(k) = 0.34-0.56) with measured slowness; self-reported and objective weakness had slight-to-borderline-fair agreement (k = 0.10-0.21). Combining three self-reported slowness questions had highest sensitivity (81%) and negative predictive value (NPV; 91%). For weakness, three questions combined had highest sensitivity (72%), while all combinations had comparable NPV. Follow-up questions on level of difficulty led to minimal changes in agreement and decreased sensitivity. Substituting subjective for objective measures in our PFP model dichotomized by frail versus non/pre-frail, we found substantial (k = 0.76-0.78) agreement between standard and self-reported PFPs. We found highest sensitivity (86.4%) and NPV (98.7%) when comparing the dichotomized standard PFP to a self-reported version combining all slowness and weakness questions. Substitutions in a three-level model (frail, vs pre-frail, vs. non-frail) resulted in fair-to-moderate agreement (k = 0.33-0.50) with the standard PFP.

CONCLUSIONS

Our results show potential utility as well as challenges of using certain self-reported questions in a modified frailty phenotype. A self-reported PFP with high agreement to the standard phenotype could be a valuable frailty screening assessment in clinical settings.

The Design and Rationale of a Phase 2b, Randomized, Double-Blinded, and Placebo-Controlled Trial to Evaluate the Safety and Efficacy of Lomecel-B in Older Adults with Frailty

BACKGROUND

Frailty in older adults is a rapidly growing unmet medical need. It is an aging-related syndrome characterized by physical decline leading to higher risk of adverse health outcomes.

OBJECTIVES

To evaluate the efficacy of Lomecel-B, an allogeneic medicinal signaling cell (MSC) formulation, in older adults with frailty.

DESIGN

This multicenter, randomized, parallel-arm, double-blinded, and placebo-controlled phase 2b trial is designed to evaluate dose-range effects of Lomecel-B for frailty on physical functioning, patient-reported outcomes (PROs), frailty status, and biomarkers.

SETTING

Eight enrolling clinical research centers, including the Miami Veterans Affairs Medical Center.

PARTICIPANTS

Target enrollment is 150 subjects aged 70-85 years of any race, ethnicity, or gender. Enrollment criteria include a Clinical Frailty Score of 5 ("mild") or 6 ("moderate"), a 6MWT of 200-400 m, and serum tumor necrosis factor-alpha (TNF-α) ≥2.5 pg/mL.

INTERVENTION

A single intravenous infusion of Lomecel-B (25, 50, 100, or 200 million cells) or placebo (N=30/arm). Patients are followed for 365 days for safety, and the efficacy assessments performed at 90, 180, and 270 days.

MEASUREMENTS

The primary endpoint is change in 6MWT in the Lomecel-B-treated arms versus placebo at 180 days post-infusion. Secondary and exploratory endpoints include change in: 6MWT and other physical function measures at all time points; PROs; frailty status; cognitive status; and an inflammatory biomarkers panel. A pre-specified sub-study examines vascular/endothelial biomarkers. Safety is evaluated throughout the trial.

RESULTS

The trial is conducted under a Food and Drug Administration Investigational New Drug (IND), with Institutional Review Board approval, and monitoring by an NIH-appointed independent Data Safety Monitoring Board.

CONCLUSION

This clinical trial investigates the use of a regenerative medicine strategy for frailty in older adults. The results will further the understanding of the potential for Lomecel-B in the geriatric condition of frailty.

Unexplained anemia of aging: Etiology, health consequences, and diagnostic criteria

BACKGROUND

Up to 15% of people aged 60 and over are anemic, and the prevalence of anemia increases with age. In older men and women, anemia is associated with increases in the risk of death and all-cause hospitalization, poor functional capacity, quality of life, and depression.

METHODS AND RESULTS

We reviewed the literature describing anemia in aging populations, focusing on the specific diagnostic criteria of anemia and potential causes in older men and women. Even after extensive etiologic workup that involves careful medical history, physical examination, laboratory measurements, and additional studies such as bone marrow biopsy, anemia of aging is unexplained in up to 40% of older patients with anemia. As a result, treatment options remain limited.

CONCLUSIONS

The prevalence of unexplained anemia of aging (UAA; also called unexplained anemia of the elderly, UAE), its deleterious impacts on health, physical function, and quality of life, and the lack of effective treatment or therapy guidelines represent a compelling unmet clinical need. In this review and consensus document, we discuss the scope of the problem, possible causes of UAA, diagnostic criteria, and potential treatment options. Because even mild anemia is strongly linked to poor clinical outcomes, it should receive clinical attention rather than simply being considered a normal part of aging.

Angiotensin Receptor Blockers Upregulate Angiotensin Type 4 Receptor in Brains of Cognitively Intact Individuals

The primary dementia-protective benefits of Angiotensin receptor type 1 (AT1R) blockers (ARBs) are believed to arise from systemic effects on blood pressure. However, there is a brain-specific renin-angiotensin system (b-RAS) that acts mainly through three receptor subtypes: AT1R, AT2R, and AT4R. AT1R promotes inflammation and oxidative stress (OS). AT2R increases nitric oxide. AT4R is essential for dopamine release and mediates memory consolidation. Here, we aimed to investigate the effects of ARBs on b-RAS, OS, inflammation, PHF-tau, and beta-amyloid load. Postmortem frontal-cortex brains of age- and sex-matched cognitively intact (CI) individuals using (n=30) and not using ARBs (n=30) and Alzheimer's disease (AD) patients using (n=30) and not using ARBs (n=30) were studied. Protein levels of receptors were measured by Western blot. Protein carbonyl (PC) and cytokine levels were measured by ELISA. Tangle and amyloid-β scores were used as outcomes. In CI individuals, our data shows that ARB treatment was associated with higher protein levels of AT4R (median(range) 0.69(1.92) vs 0.17(1.18) CI+ARBs vs CI, p=0.02), lower level of OS marker PC (10.60(8.32) vs 11.26(7.44), CI+ARBs vs CI, p=0.03) and lower hippocampal and overall amyloid scores (0(5.45) vs 1.15(4.21) p=0.03, 0.79(12.75) vs 3.41(13.36) p=0.04, CI+ARBs vs CI, respectively). In AD group, ARB treatment was associated with lower AT1R protein levels (0.47(1.15) vs 0.59(1.99), AD+ARBs vs AD, p=0.02). No significant changes were observed in OS, inflammation, or PHF-tau and amyloid load in AD brains treated with ARBs. Our results highlight the impact of ARBs on the brains of cognitively intact and AD older individuals.

Accelerometer-Derived Patterns of Physical Activity and Incident Frailty

Low physical activity (PA) is a common phenotype of frailty, but whether disengagement of daily lifestyle PA signals impending frailty remains unexplored. Using STURDY (Study to Understand Fall Reduction and Vitamin D in You) data from 499 robust/prefrail adults (mean age=76 + 5 years; 42% women), we examined whether accelerometer patterns (activity counts/day, active minutes/day, and activity fragmentation) were prospectively associated with incident frailty over 2 years of follow-up; 48 (10%) participants developed frailty. In Discrete-Cox hazard models adjusted for demographics, medical conditions, and device wear days, every 30 min/day higher baseline active time, 100,000 more activity counts/day, and 1% lower activity fragmentation was associated with a 13% (p=0.003), 10% (p=0.001), and 8% (p&lt;0.001) lower risk of frailty, respectively. Our results show that both reduced amounts and fragmented patterns of daily PA captured from accelerometry are associated with phenotypic frailty and might signal frailty onset.

Characterization of a Mouse Model of Inducible Frailty: The Humanized IL-6 Mouse

The cytokine interleukin-6 (IL-6) has pleiotropic effects in aging and is elevated in frail older adults. We have developed a conditional mouse model to better characterize the role of IL-6 in promoting frailty and age-related mitochondrial dysregulation. The human IL-6 (hIL-6) knock-in mouse (TetO-hIL6) was developed utilizing CRISPR/Cas9 technology with transgene donor vector containing a tetracycline response element promoter driving expression of hIL-6 cDNA. Male TetO-hIL6 mice were treated with doxycycline-containing water for six weeks starting at 8 months old. RNAseq analysis of whole blood demonstrated significant upregulation of pro-inflammatory related markers at 6 weeks compared to baseline and upregulated cell proliferation and metabolism pathways. Physical testing of TetO-hIL6 mice before and after hIL-6 induction demonstrated decreased grip strength (p =0.003), decreased running capacity (p = 0.02), and 40% increase in falls off of the treadmill (p = 0.001). Induced mice also demonstrated decreased basal body temperature (p &lt; 0.001). Given the significant dysregulation of metabolism-related genes in RNAseq analysis and changes in basal body temperature following hIL-6 induction, we next performed untargeted metabolomics on plasma from mice at baseline and 6 weeks post-induction to better evaluate metabolic changes associated with hIL-6 elevation. We found changes in key serum metabolites, including circulating adenosine triphosphate (56% reduction, p = 0.02), pyruvate (35% reduction, p = 0.0006), alpha-ketoglutarate (47% reduction, p = 0.04), and succinate (306% increase, p = 0.001). The TetO-hIL6 mouse model allows for induction of hIL-6 at various timepoints across the lifespan and demonstrates features of a frailty phenotype.

Transplant Centers That Measure Frailty as Part of Clinical Practice Have Better Outcomes

Frailty predicts adverse outcomes for kidney transplant (KT) patients; yet the impact of clinical assessments of frailty on center-level outcomes remains unclear. We sought to test whether KT centers that measure frailty as part of clinical practice have better pre- and post-KT outcomes. We conducted a survey of US transplant centers (11/2017-4/2018), 132 KT centers (response rate=65.3%) reported frequencies of frailty assessment at candidacy evaluation and KT admission. Center characteristics and clinical outcomes were gleaned from the national registry (2017-2019). Poisson regression was used to estimate incidence rate ratios (IRRs) of waitlist mortality rate and transplantation rate in candidates and graft loss rates in recipients by frequency of frailty assessment. All models were adjusted for case mix and center characteristics. Given similar center characteristics, centers assessing frailty at evaluation had a lower waitlist mortality rate (always=3.5, sometimes=3.2, never=4.1 deaths per 100 person-years). After adjustment, centers assessing frailty at evaluation had a lower rates of waitlist mortality (always IRR=0.91, 95% CI:0.84-0.99; sometimes=0.89, 95% CI:0.83-0.96) and transplantation (always IRR=0.94, 95% CI:0.91-0.97; sometimes=0.88, 95% CI:0.85-0.90) than those never assessing frailty. Centers that always assessed frailty at KT admission had 0.71 (95% CI:0.54-0.92) times the rate of death-censored graft loss than their counterparts never assessing frailty. Assessing frailty at evaluation is associated with lower transplantation rate but better waitlist survival; centers always assessing frailty at admission are likely to have better graft survival. Research is needed to explore how routine assessment of frailty in other clinical practices benefits broader patient populations.

2015-2016 Normative Data for the 3-m Usual Walk, Five Repeated Chair Stands, and Static Balance Components of the SPPB Among U.S. Older Adults Across Two Nationally Representative Data Sets: NSHAP and NHATS

OBJECTIVES

Our primary objective was to examine the distribution of 3-m usual walk, five repeated chair stands, and three static balance stance performances among age and gender subgroups of adults at least 65 years in two national data sets. We secondarily determined whether demographic-function associations varied across data sets, birth cohorts, or models incorporating data from those "unable to do" tasks.

METHODS

Two nationally representative data sets were used to generate survey weight-adjusted performance distributions: the 2015-2016 National Social Life Health and Aging Project and the 2016 National Health and Aging Trends Study. We then regressed walk and chair stand performance on age, gender, and race/ethnicity, examining differences across data sets, birth cohorts (1920-1947, 1948-1965), and before/after incorporating the "unable to do" performers.

RESULTS

Findings confirmed the gradual decline in function with age and allowed estimation of "relative" performance within age/gender subgroups. Data set distribution differences were noted, possibly due to recruitment, eligibility, and protocol variations. Demographic associations were similar across data sets but generally weaker among the 1948-1965 cohort and in models including the sizable "unable to do" group.

DISCUSSION

We present the largest, most current Short Physical Performance Battery reference data in U.S. adults aged 65 or older. Findings support standardization of administration protocols in research and clinical care and differentiating absolute from relative performance.