175. High levels of aerobic fitness are associated with fewer senescent T-cells and a lower prevalence of latent cytomegalovirus infection in healthy men

Abstract

The immune risk profile (IRP) is an array of immunological biomarkers that is associated with decreased vaccine efficacy, increased disease susceptibility and 3–5 year mortality in the elderly. Increased proportions of KLRG1 + CD28-CD8 (senescent) T-cells and latent cytomegalovirus (CMV) infection are key components of the IRP. We have previously shown that high aerobic fitness levels (determined by VO2 max) are associated with a decreased accumulation of senescent T-cells during aging, but it is not known if fitness affects CMV prevalence or viral load. T-cell phenotypes and CMV status was determined in 74 healthy men (aged 18–64) categorized as “High Fit” ( n = 36) or “Low Fit” ( n = 38) according to age-adjusted VO2max scores. High aerobic fitness was associated with lower proportions of senescent CD8+ T-cells (23.0% v 46.6%; p < 0.05) and lower CMV seroprevalence (33.3% v 63.2%), but did not impact CMV IgG antibody titers (a measure of viral load) in the seropositive participants. Although CMV can drive T-cell differentiation, the effects of fitness on senescent CD8+ T-cell proportions withstood adjustment for CMV serostatus, indicating that fitness may impact the composition of the CD8+ T-cell pool independently of CMV. Plasma testosterone levels and serostatus/titers for Epstein-Barr virus, toxoplasmosis, and Helicobacter Pylori were not affected by fitness. In conclusion, high levels of aerobic fitness across the lifespan are associated with a less differentiated T-cell profile and a lower prevalence of CMV.