Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7279129 | Brain, Behavior, and Immunity | 2018 | 42 Pages |
Abstract
Natural Killer cells are cytotoxic lymphocytes that recognize and eliminate tumor cells. Exercise enhances NK cell cytotoxic activity (NKCA), yet the underlying mechanisms are not fully understood. Exercise-induced shifts in NK-cell subsets has been proposed as one mechanism. Alternatively, exercise alters stress hormone and cytokine levels, which are also known to affect NKCA. AIM: Determine the role(s) of exercise-induced shifts in the proportions of NK-cell subsets found in the blood, and changes in serum IL-2, IL-6, IL-12, IFN-γ, TNF-α and cortisol, on exercise-induced changes in NKCA. METHODS: Twelve adults cycled 30â¯min at 115% of their lactate threshold power. Peripheral blood mononuclear cells (PBMCs) and serum were isolated from blood collected pre-, post-, and 1â¯h post-exercise. To investigate the effect of shifts in NK-cell subsets, pre-, post- and 1â¯h post-exercise NK cells were incubated with target cells (K562 and U266) in the presence of autologous pre-exercise serum. The effects of hormones and cytokines released during exercise were determined by incubating pre-exercise PBMCs with tumor target cells (K562 and U266) in the presence of pre-, post-, and 1â¯h post-exercise serum. NKCA and phenotypes were assessed by flow cytometry. RESULTS: Although exercise mobilized high-differentiated NK cell subsets (NKG2A-/KIR+), NKCA per cell was not altered post-exercise in the presence of pre-exercise serum. Conversely, 1â¯h post-exercise serum significantly increased the cytotoxicity of pre-exercise NK cells against HLA-expressing target cells (U266). This increase associated with lower levels of cortisol, and occurred when serum contained higher levels of IFN-γ. CONCLUSIONS: Exercise-induced shifts in NK-cell subsets did not fully explain changes in NKCA. Rather, factors present in serum during exercise recovery enhanced NKCA against target cells. Our results suggest lower cortisol and higher IFN-γ levels may explain exercise-induced changes in NKCA.
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Authors
Priti Gupta, Austin B. Bigley, Melissa Markofski, Mitzi Laughlin, Emily C. LaVoy,