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: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: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:Type 2 diabetes (T2D) is consistently associated with an elevated risk of cognitive decline and dementia. The underlying molecular mechanisms relating T2D to cognitive decline remain unclear, impeding the ability to detect the earliest stages of cognitive decline in older adults with T2D, consequently hindering advancement of preventive interventions. This study compared quantitative alterations in glycoproteoforms, represented by tryptic glycopeptiforms—specific glycan compositions on amino acid sites of proteins—in older T2D adults. We utilized label free, mass spectrometry-based glycoproteomics to analyze protein N-glycosylation and glycation patterns in serum samples, collected at two time points (T1 and T2), an average 52 months apart, from two initially cognitively healthy T2D groups. One group was comprised of individuals who experienced cognitive decline (“decliners”; N=8), and the other, of individuals who maintained normal cognition (“non-decliners”; N=14) over time. Comparison of these two groups revealed distinct patterns for glycosylation and glycation. Glycosylation primarily affected platelet function pathways. Glycation was also involved in immune system and platelet function along with various metabolic pathways. These findings suggest that aberrant glycoproteomic modifications may contribute to the development of cognitive impairment in T2D and may serve as potential early biomarkers. Further research is warranted to elucidate the functional implications of glycopeptiform modifications in T2D-related cognitive decline.
Project description:Human neonates and older adults frequently exhibit a reduced capacity to control microbial infections. A variety of mechanisms involving both the innate and adaptive immune systems have been proposed to contribute to these deficiencies. The emergence of RNA sequencing (RNA-seq) as an accurate and quantitative method for examining mRNA levels provides an opportunity to compare transcriptional responses to a stimulus at a global scale in neonates, adults, and older adults. An examination of ex vivo monocyte responses to lipopolysaccharide stimulation or Listeria monocytogenes infection (with cord blood monocytes representing neonatal monocytes) revealed extensive similarities between all three age groups, with only a small number of genes exhibiting statistically significant differences. Using transcription factor motif analyses and RNA-seq data sets from a variety of mouse mutants, the most significant neonatal deficiencies corresponded to genes that require interferon response factor-3 or type 1 interferon signaling for their activation. In older adults, the most striking difference was broad, low-level activation of inflammatory genes prior to stimulation, consistent with prior evidence of a chronic inflammatory state in older adults. These results demonstrate the value of quantitative RNA-seq analyses and the feasibility of cross-species comparisons between well-defined mouse networks and human data sets.
Project description:CD8+ T-cells provide robust anti-viral immunity, yet how epitope-specific T-cells evolve across the human lifespan is unknown. We defined CD8+ T-cell immunity directed at the prominent influenza epitope, HLA-A*02:01-M158-66 (A2/M158) across four age groups (newborns, children, adults and elderly) ex vivo at phenotypic, single cell sequence (transcriptomic), clonal and functional levels. We identified a linear differentiation trajectory from newborns to children then adults, followed by divergence and a clonal reset in older adults. Gene profiles in older adults closely resembled those observed in newborns and children, despite being clonally-different. However, only child- and adult-derived A2/M158+CD8+ T-cells had the potential to differentiate into highly cytotoxic epitope-specific CD8+ T-cells, which was linked to highly functional public TCRab-signatures. Suboptimal TCRab-signatures detected in older adults led to poorer proliferation, polyfunctionality, avidity and recognition of peptide mutants, although displayed no signs of exhaustion. Our study suggests that priming T-cells at different stages of life might greatly affect CD8+ T-cell responses towards viral infections.
Project description:Streptococcus pneumoniae colonization in the upper respiratory tract is linked to pneumococcal disease development, predominantly affecting young children and older adults. As the global population ages and comorbidities increase, there is a heightened concern about this infection. We investigated the immunological responses of older adults to pneumococcal controlled human infection by analysing the cellular composition and gene expression in the nasal mucosa. Our comparative analysis with data from a concurrent study in younger adults revealed distinct gene expression patterns in older individuals susceptible to colonization, highlighted by neutrophil activation and elevated levels of CXCL9 and CXCL10. Unlike younger adults challenged with pneumococcus, older adults did not show recruitment of monocytes into the nasal mucosa following nasal colonization. However, older adults who were protected from colonization showed increased degranulation of CD8+ T cells, both before and after pneumococcal challenge. These findings suggest age-associated cellular changes, in particular enhanced mucosal inflammation, that may predispose older adults to pneumococcal colonization.
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:Evidence from clinical trials and observational studies suggests that both progressive resistance training (PRT) and metformin delay a variety of age-related morbidities. Previously, we completed a clinical trial testing the effects of 14 weeks of PRT + metformin (metPRT) compared to PRT with placebo (plaPRT) on muscle hypertrophy in older adults. We found that metformin blunted PRT-induced muscle hypertrophic response. To understand potential mechanisms underlying the inhibitory effect of metformin on PRT, we analyzed the muscle transcriptome in 23 metPRT and 24 plaPRT participants. PRT significantly increased expression of genes involved in extracellular matrix remodeling pathways, and downregulated RNA processing pathways in both groups, however, metformin blunted the number of differentially expressed genes within these pathways compared to plaPRT. Pathway analysis showed that genes unique to metPRT modulated aging-relevant pathways, such as cellular senescence and autophagy. Differentially expressed genes from baseline biopsies in older adults compared to resting muscle from young volunteers were reduced following PRT in plaPRT and were further reduced in metPRT. We suggest that although metformin may blunt pathways induced by PRT to promote muscle hypertrophy, adjunctive metformin during PRT may have beneficial effects on aging-associated pathways in muscle from older adults.