Impact of Exercise and Cytomegalovirus Infection on Age-Associated Changes in T-Cell Immunity

Human Cytomegalovirus (CMV) is a beta-herpesvirus widely considered to impact the immune system and decrease life-expectancy. Research within the past decade indicates physically active individuals have better immune profiles compared to their sedentary counterparts; however, it is not known if exercise training can reverse these differences, especially in persons infected with CMV. This dissertation examines the effects of exercise across varying interventions on the immune profiles of CMV seropositive individuals. The first study examined the impact of stress load on the immune response to maximal exercise using a longitudinal study. Collegiate athletes are exposed to varying levels of academic and physical stressors, placing them at increased risk for stress-activated latent viral infections. Results indicated CMV seropositive and seronegative participants had similar resting percentages of senescent T-cells during periods of high allostatic stress. However, CMV seronegative participants exhibited decreases in senescent T-cells as stress load diminished; while, CMV seropositive participants retained high senescent T-cell percentages. These results suggest stress impacts CMV seropositive individuals differently. Regular exercise is associated with changes in peripheral blood mononuclear cell (PBMC) proportions that have enhanced effector functions in young and old adults; however, the effects of acute exercise on PBMC nutrient sensors and metabolic function in young adults is unknown. Therefore, this was the purpose of the second study. Exercise mobilized activated T-cells while concomitantly increasing PBMC mitochondrial oxidative capacity at the tissue level. However, PBMC mitochondrial function was not affected by CMV serostatus. The last study was designed to investigate the effects of a 16-week exercise intervention on T-cell phenotype and nutrient sensing as well as PBMC mitochondrial function in older adults. Participants also completed a mixed meal test to further investigate the impact of training and changing circulating nutrient concentrations on immune profiles. Training decreased the number of senescent CD4+ T-cells in response to the mixed meal challenge; however, an increase in the number of highly differentiated CD4+ T-cells was observed at rest. PBMC mitochondrial oxidative capacity did not change. Taken together, these data suggest 16-week exercise intervention was insufficient to reverse the effects of aging on the resting immune profiles of older adults