Project description:Vitamin D deficiency is common among older adults and has been linked to muscle weakness. Vitamin D supplementation has been proposed as a strategy to improve muscle function in older adults. The aim of this study was to investigate the effect of calcifediol (25-hydroxycholecalciferol) on whole genome gene expression in skeletal muscle of vitamin D deficient frail older adults. A double-blind placebo controlled trial was conducted in vitamin D deficient frail older adults (aged above 65), characterized by blood 25-hydroxycholecalciferol concentrations between 20 and 50 nmol/L. Subjects were randomized across the placebo group (n=12) and the calcifediol group (n=10, 10 µg per day). Muscle biopsies were obtained before and after six months of calcifediol or placebo supplementation and subjected to whole genome gene expression profiling using Affymetrix HuGene 2.1ST arrays. Expression of the vitamin D receptor gene was virtually undetectable in human skeletal muscle biopsies. Calcifediol supplementation led to a significant increase in blood 25-hydroxycholecalciferol levels compared to the placebo group. No difference between treatment groups was observed on strength outcomes. The whole transcriptome effects of calcifediol and placebo were very weak. Correcting for multiple testing using false discovery rate did not yield any differentially expressed genes using any sensible cut-offs. P-values were uniformly distributed across all genes, suggesting that low p-values are likely to be false positives. Partial least squares-discriminant analysis and principle component analysis was unable to separate treatment groups. Calcifediol supplementation did not affect the skeletal muscle transcriptome in frail older adults. Our findings indicate that vitamin D supplementation has no effects on skeletal muscle gene expression, suggesting that skeletal muscle may not be a direct target of vitamin D in older adults.
Project description:Frailty affects the physical, cognitive, and social domains exposing older adults to an increased risk of cardiovascular disease (CVD) and death. The mechanisms linking frailty and cardiovascular outcomes are mostly unknown. Here, we studied the association of abundance (flow cytometry) and gene expression profile (RNAseq) of stem/progenitor cells (HSPCs) and molecular markers of inflammaging (ELISA) with the cardiorespiratory phenotype and prospective adverse events of individuals classified according to levels of frailty. Two cohorts of older adults were enrolled in the study. In a cohort of pre-frail 35 individuals (average age: 75 years), a physical frailty score above the median identified subjects with initial alterations in cardiorespiratory function. RNA sequencing revealed S100A8/A9 upregulation in HSPCs from the bone marrow (>10-fold) and peripheral blood (>200-fold) of individuals with greater physical frailty. Moreover higher frailty was associated with increased alarmins S100A8/A9 and inflammatory cytokines in peripheral blood. We then studied a cohort of 104 more frail individuals (average age: 81 years) with multi-domain health deficits. Reduced levels of circulating HSPCs and increased S100A8/A9 concentrations were independently associated with the frailty index. Remarkably, low HSPCs and high S100A8/A9 simultaneously predicted major adverse cardiovascular events at 1-year follow-up after adjustment for age and frailty index. In conclusion, inflammaging characterized by alarmin and pro-inflammatory cytokines in pre-frail individuals is mirrored by the pauperization of HSPCs in frail older people with comorbidities. S100A8/A9 is upregulated within HSPCs, identifying a phenotype that associates with poor cardiovascular outcomes.
Project description:The skeletal muscle system plays an important role in the independence of older adults. In this study we examine differences in the skeletal muscle transcriptome between healthy young and older subjects and (pre‐)frail older adults. Additionally, we examine the effect of resistance‐type exercise training on the muscle transcriptome in healthy older subjects and (pre‐)frail older adults. Baseline transcriptome profiles were measured in muscle biopsies collected from 53 young, 73 healthy older subjects, and 61 frail older subjects. Follow‐up samples from these frail older subjects (31 samples) and healthy older subjects (41 samples) were collected after 6 months of progressive resistance‐type exercise training. Frail older subjects trained twice per week and the healthy older subjects trained three times per week. At baseline genes related to mitochondrial function and energy metabolism were differentially expressed between older and young subjects, as well as between healthy and frail older subjects. Three hundred seven genes were differentially expressed after training in both groups. Training affected expression levels of genes related to extracellular matrix, glucose metabolism, and vascularization. Expression of genes that were modulated by exercise training was indicative of muscle strength at baseline. Genes that strongly correlated with strength belonged to the protocadherin gamma gene cluster (r = −0.73). Our data suggest significant remaining plasticity of ageing skeletal muscle to adapt to resistance‐type exercise training. Some age‐related changes in skeletal muscle gene expression appear to be partially reversed by prolonged resistance‐type exercise training. The protocadherin gamma gene cluster may be related to muscle denervation and re‐innervation in ageing muscle.
Project description:Global ageing poses a substantial economic burden on health and social care costs. Enabling a greater proportion of older people to stay healthy for longer is key to the future sustainability of health, social and economic policy. Frailty and associated decrease in resilience plays a central role in poor health in later life. In this study, we present a population level assessment of the metabolic phenotype associated with frailty. Analysis of serum from 1191 older individuals (aged between 56 and 84 years old) and subsequent longitudinal validation (on 786 subjects) was carried out using liquid and gas chromatography-mass spectrometry metabolomics and stratified across a frailty index designed to quantitatively summarize vulnerability. Through multivariate regression and network modelling and mROC modeling we identified 12 significant metabolites (including three tocotrienols and six carnitines) that differentiate frail and non-frail phenotypes. Our study provides evidence that the dysregulation of carnitine shuttle and vitamin E pathways play a role in the risk of frailty.
Project description:As human society ages globally, age-related disorders are becoming increasingly common. Due to decreasing physiological reserves and increasing organ system dysfunction associated with age, frailty affects many elderly people, compromising their ability to cope with acute stressors. Frail elderly people commonly manifest complex clinical symptoms, including cognitive dysfunction, hypomobility, and impaired daily activity, the metabolic basis of which has been little understood. We applied untargeted, comprehensive, LC-MS metabolomic analysis to human blood from 19 frail and non-frail elderly patients, who were clinically evaluated using the Edmonton Frail Scale, the MoCA-J for cognition, and the TUG for mobility. Among 131 metabolites assayed, we identified 22 markers for frailty, cognition, and hypomobility, most of which were abundant in blood. Frailty markers included 5 of 6 markers specifically related to cognition and 6 of 12 associated with hypomobility. These overlapping sets of markers include metabolites related to antioxidation, muscle or nitrogen metabolism, and amino acids, most of which decrease in frail elderly people. Five frailty-related metabolites that decreased (1,5-anhydroglucitol, acetyl-carnosine, ophthalmic acid, leucine, and isoleucine) have been previously reported as markers of aging, providing a metabolic link between human aging and frailty. Our findings clearly indicate that metabolite profiles efficiently distinguish frailty from non-frailty. Importantly, the antioxidant, ergothioneine, which decreases in frailty, is neuroprotective. Oxidative stress resulting from diminished antioxidant levels, could be a key vulnerability for pathogenesis of frailty, exacerbating illnesses related to human aging.
Project description:Physical frailty's impact on hemagglutination inhibition antibody titers (HAI) and peripheral blood mononuclear cell (PBMC) transcriptional responses after influenza vaccination is unclear. Physical frailty was assessed using the 5-item Fried frailty phenotype in 168 community- and assisted-living adults ≥55 years of age during an observational study. Blood was drawn before, 3, 7, and 28 days post-vaccination with the 2017-2018 inactivated influenza vaccine. HAI response to the A/H1N1 strain was measured at Days 0 and 28 using seropositivity, seroconversion, log2 HAI titers, and fold-rise in log2 HAI titers. RNA sequencing of PBMCs from Days 0, 3 and 7 was measured in 28 participants and compared using pathway analyses. Frailty was not significantly associated with any HAI outcome in multivariable models. Compared with non-frail participants, frail participants expressed decreased cell proliferation, metabolism, antibody production, and interferon signaling genes. Conversely, frail participants showed elevated gene expression in IL-8 signaling, T-cell exhaustion, and oxidative stress pathways compared with non-frail participants. These results suggest that reduced effectiveness of influenza vaccine among older, frail individuals may be attributed to immunosenescence-related changes in PBMCs that are not reflected in antibody levels.
Project description:Community acquired pneumonia (CAP) is a leading cause of hospitalistion and is associated with high mortality and morbidity. Neutrophils from CAP donors display altered functions, and these altered functions are associated with adverse outcomes. We undertook an oberservational study of CAP in frail older adults and age matched controls to determine drivers of neutrophil dysfunction.
Project description:The global transcriptome of the Bifidobacterium animalis subsp. lactis Bl-04 was analyzed during exponential growth on 11 prebiotic carbohydrates and glucose to identify the specific gene cluster differentially upregulated in response to each carbohydrate.