Dynamic Transcriptomic Responses of Circulating Immune Cells in Response to Subsequent Days of Exercise Heat Stress

Acute exercise and chronic training have diverse effects on immune function that are still not well understood. There are remaining questions about how an acute bout of exercise, competition, or repeated training over a period affects an individual’s immune defense system. In a related study, there is evidence that acute exercise may serve as an adjuvant to enhance response to immune function as well as contradicting evidence, including our preliminary data (unpublished). Understanding the fundamental function and gene expression of circulating immune cells in response to acute exercise and in various contexts such as heat stress is critical in understanding our immune health. This study accomplished 2 aims: 1) a systematic review of the literature for studies of immune responses to exercise in our target cell population (circulating immune cells) and 2) complete a human subjects study of genome-wide changes in gene expression, that occur in the circulating immune cells important for immune defense in response to two subsequent exposures to exercise and environmental stress. Both male and female participants (VO2max\u3e40, 45 mL×kg-1×min-1 respectively) went through two days of heat exposure in a 40°C, 40% relative humidity chamber. Blood samples of 6 participants from all 14 time points were analyzed for differential gene expression. Fold changes from baseline and HTT, and differential gene expression was analyzed for functional annotation and pathway analyses. Findings from our experimental study revealed differences in men and women relative to their respective pre-acclimation state, in the global genome expression landscape in pathways related to stress response and protein homeostasis. Ongoing research will examine additional subjects and pursue more in-depth pathway analyses of our results for men and women before and after exercise-heat acclimation