Abstract
Systemic inflammation is believed to contribute to declining muscle health during aging. The present study aims to examine associations between indicators of muscle health and pro- and anti-inflammatory biomarkers in older men and women, while also considering the impacts of physical activity and protein intake. An assessment of skeletal muscle index (SMI) by bioelectrical impedance analysis, handgrip strength, and 5-sit-to-stand time, using standardized procedures, was conducted in a population of older men (n = 90) and women (n = 148) aged 65–70 years. The inflammatory biomarkers C-reactive protein (CRP), fibrinogen, interleukin (IL)-6, IL-10, IL-18, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein-1, and macrophage inflammatory protein-1α were assessed in blood samples. Data were analyzed and stratified according to biological sex using multiple linear regression models. In older women, SMI was inversely associated with the pro-inflammatory markers CRP (β = −0.372; p < 0.05), fibrinogen (β = −0.376; p < 0.05), and IL-6 (β = −0.369; p < 0.05). Importantly, these associations were independent of abdominal adiposity (waist circumference), protein intake, physical activity level, as well as any adherence to muscle strengthening guidelines (≥2 sessions/week). In contrast, no corresponding associations were observed in men. In conclusion, our findings indicate the detrimental influence of a pro-inflammatory environment on muscle health regardless of important lifestyle-related factors in older women. However, the lack of such associations in older men highlights the importance of considering biological sex when examining the complex interaction between the systemic inflammatory environment and muscle health.
Highlights
The aging process is associated with a gradual loss of skeletal muscle mass and a concomitant decline in muscle strength and function, which may lead to the development of sarcopenia [1]
Slight yet chronic elevations in circulating levels of cytokines, such as interleukin-6 (IL-6), IL-18, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, and acute-phase proteins C-reactive protein (CRP) and fibrinogen contribute to a pro-inflammatory environment in older adults [6,7,8,9,10]
No statistical difference was observed between sexes for the pro-inflammatory biomarkers TNF-α, IL-6, and MCP-1 (Table S1)
Summary
The aging process is associated with a gradual loss of skeletal muscle mass and a concomitant decline in muscle strength and function, which may lead to the development of sarcopenia [1]. Impaired muscle health in older adults has been associated with adverse health outcomes including physical disability, increased risk of falls, fractures, and mortality [2,3]. Recent research has suggested that changes in the systemic inflammatory environment may contribute to the deterioration of muscle health in older adults [5]. Slight yet chronic elevations in circulating levels of cytokines, such as interleukin-6 (IL-6), IL-18, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, and acute-phase proteins C-reactive protein (CRP) and fibrinogen contribute to a pro-inflammatory environment in older adults [6,7,8,9,10]. The systemic environment in older adults is influenced by IL-10, which has been shown to play an important anti-inflammatory role by inhibiting the production of pro-inflammatory cytokines by monocytes [11]. While few reports have investigated the associations between IL-10 and muscle health in humans, modest increases in muscle IL-10 mRNA have been reported in
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