Abstract
Post-exercise lymphopenia occurs in cortisol-responders. Cortisol is apparently responsible for T cell lymphopenia after exercise, but the mechanism by which cortisol drives T cells away from circulation is unknown. We asked whether chemokine receptor is responsible for cortisol-induced lymphopenia after acute exercise. PURPOSE: The aim of this study was to find what chemokine receptor is induced or activated by acute exercise-induced cortisol, and to find out if it is involved in post-exercise T cell mobilization. METHODS: Isolated peripheral blood mononuclear cells (PBMC) were incubated with cortisol and analyzed for expression of a panel of chemokine receptors on T cells by flow cytometry. Seven young healthy male volunteers (age:23.7 ± 0.8 yrs) performed cycling exercise for 90 min at exercise intensity of 70% peak oxygen uptake. Heparinized blood samples were obtained at different time points. Plasma was kept frozen until use. Isolated PBMC were analyzed for the expression of chemokine receptors. Plasma concentration of cortisol was determined by radio-immuno assay. Plasma samples obtained were tested for the ability to induce chemokine receptors. RESULTS: CXCR4 was the only chemokine receptor up regulated by glucocorticoids, and T cell CXCR4 expression increased in a dose dependent manner within physiological range of cortisol concentration. CXCR4 expression on circulating T cells was significantly decreased 1 day after exercise up to 3 days. Plasma cortisol was elevated in 6 out of 7 subjects and decreased in one subject. Plasma with elevated cortisol enhanced CXCR4 expression, while that with decreased cortisol down-regulated CXCR4 expression on T cells in culture. DISCUSSION: Circulating T cells with enhanced CXCR4 expression may quickly be mobilized to tissues constitutively expressing unique ligand for CXCR4, CXCL12, leaving only T cells with smaller amount of CXCR4 expression in circulation. CONCLUSION: CXCR4 was found to be the major chemokine receptor whose expression can be enhanced by exercise-induced cortisol. Enhanced CXCR4 expression may mobilize T cells out of circulation to various tissues, resulting in lymphopenia after exercise.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call