Exercise Acutely Modulates Mitochondrial Function in Peripheral Blood Mononuclear Cells

Exercise trained individuals have greater immune system function, which may be attributed to enhanced peripheral blood mononuclear cells (PBMC) function. Exercise training is a potent stimulator of mitochondrial adaptation, which may explain improvements in immune system function. However, the mechanisms by which exercise acutely modulates PBMCs to lead toward beneficial adaptations remain unclear. PURPOSE: The purpose of this pilot was to test the hypothesis that exercise acutely modulates PBMC mitochondrial function. METHODS: Ten participants (eight males, two females, 22.81 ± 4.49 years) had blood drawn prior to a bout of exercise that included a graded exercise test (VO2max: 45.19 ± 1.85 mlO2/kg/min) followed by 30 minutes of cycling at 50% of maximum aerobic workload (160.0 ±39.09 W). Immediately following the exercise, blood was drawn again. PBMCs were isolated, counted, and placed in a high-resolution respirometer to assess mitochondrial respiratory capacity. Paired t-tests were conducted to compare respiratory states pre- and post-exercise. RESULTS: Cardiorespiratory fitness was not associated with coupled (r=0.19; p=0.59) or uncoupled (r=0.29; p=0.42) respiration. LEAK respiration was not different (p=0.43) between pre- (1.48 ± 0.67 pmol/(s*Mill)) and post- (1.14 ± 1.34 pmol/(s*Mill)) exercise. Acute exercise did not affect maximal coupled respiration (Pre: 20.25 ± 7.09 pmol/(s*Mill), Post: 18.10 ± 5.17 pmol/(s*Mill); p=0.22). However, acute exercise did impair maximal uncoupled respiration (Pre: 27.23 ± 11 pmol/(s*Mill), Post: 22.57 ± 7.08 pmol/(s*Mill); p=0.10). CONCLUSION: These data indicate that exercise likely acutely modulates uncoupled mitochondrial respiration in PBMCs. Importantly, the variability in the response to exercise is quite large, even in a small sample size of a relatively homogenous group. Future efforts are necessary to determine if these acute changes in mitochondrial respiratory capacity relate to long-term adaptations. Moreover, it is necessary to understand whether the same bout of exercise elicits a similar acute response in a broader range of fitness and age.