Regular Exercise Reduces Measures of Immunosenescence in Old Individuals
Regular exercise improves many aspects of health in later life. It reduces incidence of age-related disease and mortality risk by a significant degree. It improves near all aspects of metabolism, and reverses the downward decline of many metrics of health and aging. Hunter-gatherer populations that sustain high levels of physical activity into later life exhibit a fraction of the cardiovascular disease of populations in wealthier parts of the world. The work here illustrates another known relationship: that active older individuals have a better immune function than their less active peers, as exercise improves the measured immune cell population metrics.
Regular physical activity has a profound effect on normal functioning of the immune system. For decades it has been accepted that prolonged periods of high-intensity exercise could depress immunity. However, current evidence from epidemiological studies shows that leading a physically active lifestyle is likely to be beneficial rather than harmful to the immune function. Exercise-induced improvements in immunity can be related to reduction in inflammation, maintenance of thymic mass, changes in the composition of memory and naïve T lymphocytes or enhanced immunosurveillance. Indeed, physical activity is a powerful intervention that has a great potential to improve immune and health outcomes in the older adults, the obese, and patients with cancer and chronic viral infections. The benefits of regular physical activity undertaken by the older adults are much less documented than the effects of regular physical activity on the immune system in young individuals.
In recent years the effects of regular physical activity on T lymphocytes have attracted a considerable interest and plenty of evidence showed the lifestyle exercise may lead to rejuvenation of the immune system and may exert a positive effect on thymic output. The active older adults in our study were observed to have a statistically significantly increased percentage of blood CD4+CD45RA+ T lymphocytes in comparison to the inactive older adults. This may be associated with elevated IL-15 levels that affect the immune homeostasis which is caused by the induction of a better survival rate of naïve T lymphocytes.
Attempts to determine the relationships between cytomegalovirus (CMV)-seropositivity and changes in the count of T lymphocytes have been undertaken by scientists for many years. The results of the research carried out due to the health condition of the examined patients, genetic background and/or many others factors in highly diverse human populations are varied. Most researchers agree that CMV infection at least accelerates the age-related decrease in the number of naïve T lymphocytes and the increase in memory T lymphocytes.
In our study, we showed that, regardless of CMV-seropositivity, in the physically active older adults there was an increase in the count of CD4+CD45RA+ T lymphocytes as well as in the CD4+CD45RA+/CD4+CD45RO+ ratio compared to the inactive CMV-seropositive older adults. This emphasises the beneficial effect which the activity of older adults exerts on their immune system functioning. Latent infection in people with normal immunity frequently shows no symptoms, but it could be dangerous for immune compromised ones. This is associated with CD4/CD8 < 1 identified in immune-risk individuals, which induces a high risk of mortality due to weaker immune response. In our study, the inactive older adults CMV-seropositive individuals showed a lower CD4/CD8 ratio compared to the active older adults CMV-seropositive adults. Interestingly, older active CMV-seronegative adults obtained the CD4/CD8 ratio of 2.8 ± 1.5 which is higher than that observed in the active older CMV-seropositive adults (2.5 ± 1.0) as well as in the inactive CMV-seropositive individuals (2.1 ± 0.9).