Effects of Physical Activity Status and Exercise Modality on the T-Cell and Monocyte Response to Acute Exercise in Older Adults
Levine, Rachel Graff
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Older adults are at increased risk for many inflammation-associated chronic diseases, especially when aging is combined with physical inactivity. Maintaining an active lifestyle significantly reduces the risk of chronic disease in older adulthood, which may be due, in part, to the ability of regular exercise to maintain optimal immune function and minimize chronic inflammation. The specific immune system and inflammatory effects of cardiorespiratory (CRE) compared to resistance (RE) exercise in older adults are not fully understood. The purpose of this study was to examine the effects of exercise modality (cardiorespiratory vs. resistance training), and training status (physically active vs. inactive) on the immune system and inflammatory response to acute exercise of physically active older adults (OPA) and physically inactive older adults (OPI). Twenty-four healthy older adults (OPA n=12; OPI n=12) completed one bout of CRE and one bout of RE in a randomized order, both at a moderate intensity, and separated by at least 7 days. Blood samples were collected pre-exercise, post-exercise, and 1h post-exercise (recovery) time points and analyzed for CD4+ and CD8+ T-cells and T-cell subsets expressing surface markers CD45RA, CD62L, CD57, CD161, and CD196, and monocytes and monocyte subsets expressing surface markers CD11b, CCR5, CX3CR1, and CCR2. Monocyte function was assessed in vitro by LPS-stimulated cytokine (IL-6 and TNF) secretion and a glucocorticoid resistance assay. OPI had higher numbers of circulating CD57+ EMRA CD4+ T-cells (mean ± SE; OPA, 1 ± 2 cells/μL; OPI, 6 ± 2 cells/μL) and higher CCR2+ non-classical monocytes MFI (mean ± SE arbitrary units; OPA, 8 ± 4; OPI, 21 ± 4) than OPA at rest. Furthermore, RE mobilized more T-cell and monocyte subsets than CRE in both OPA and OPI groups, and CRE resulted in increased LPS-stimulated TNF production and decreased Th17 cell mobilization post-exercise, while RE caused decreased LPS-stimulated TNF production post-exercise and increased Th17 cell mobilization. Taken together, there were not major differences between the OPA and OPI response to acute exercise. However, differences in the immune system and inflammatory response to CRE compared to RE may exist and these differences may provide important insight to informing future exercise prescriptions for older adults to minimize inflammation and promote optimal immune function.