title: Lean mass, muscle strength and gene expression in community dwelling older men: findings from the Hertfordshire Sarcopenia Study (HSS).
abstract: Sarcopenia is associated with adverse health outcomes. This study investigated whether skeletal muscle gene expression was associated with lean mass and grip strength in community-dwelling older men. Utilising a cross-sectional study design, lean muscle mass and grip strength were measured in 88 men aged 68-76 years. Expression profiles of 44 genes implicated in the cellular regulation of skeletal muscle were determined. Serum was analysed for circulating cytokines TNF (tumour necrosis factor), IL-6 (interleukin 6, IFNG (interferon gamma), IL1R1 (interleukin-1 receptor-1). Relationships between skeletal muscle gene expression, circulating cytokines, lean mass and grip strength were examined. Participant groups with higher and lower values of lean muscle mass (n = 18) and strength (n = 20) were used in the analysis of gene expression fold change. Expression of VDR (vitamin D receptor) [fold change (FC) 0.52, standard error for fold change (SE) ± 0.08, p = 0.01] and IFNG mRNA (FC 0.31; SE ± 0.19, p = 0.01) were lower in those with higher lean mass. Expression of IL-6 (FC 0.43; SE ± 0.13, p = 0.02), TNF (FC 0.52; SE ± 0.10, p = 0.02), IL1R1 (FC 0.63; SE ± 0.09, p = 0.04) and MSTN (myostatin) (FC 0.64; SE ± 0.11, p = 0.04) were lower in those with higher grip strength. No other significant changes were observed. Significant negative correlations between serum IL-6 (R = -0.29, p = 0.005), TNF (R = -0.24, p = 0.017) and grip strength were demonstrated. This novel skeletal muscle gene expression study carried out within a well-characterized epidemiological birth cohort has demonstrated that lower expression of VDR and IFNG is associated with higher lean mass, and lower expression of IL-6, TNF, IL1R1 and myostatin is associated with higher grip strength. These findings are consistent with a role of proinflammatory factors in mediating lower muscle strength in community-dwelling older men.
authors: MRC Lifecourse Epidemiology Unit, Southampton General Hospital, University of Southampton, Tremona Road, Southampton, SO16 6YD, UK, hp@mrc.soton.ac.uk.
authors: Harnish P
authors: HP
authors: Patel
authors: Nasser
authors: N
authors: Al-Shanti
authors: Lucy C
authors: LC
authors: Davies
authors: Sheila J
authors: SJ
authors: Barton
authors: Miranda D
authors: MD
authors: Grounds
authors: Ross L
authors: RL
authors: Tellam
authors: Claire E
authors: CE
authors: Stewart
authors: Cyrus
authors: C
authors: Cooper
authors: Avan Aihie
authors: AA
authors: Sayer
mesh_terms: D000368:Aged; D000886:Anthropometry; D001706:Biopsy; D001823:Body Composition; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004739:England; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism; D055435:Myostatin / Q000378:metabolism; D016133:Polymerase Chain Reaction; D053573:Receptors, Interleukin-1 Type I / Q000378:metabolism; D055948:Sarcopenia / Q000473:pathology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: C573415:IFNG protein, human; C508590:IL1R1 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D055435:Myostatin; D053573:Receptors, Interleukin-1 Type I; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma