Physical Activity in Multiple Sclerosis: A Comparative Study of Vitamin D, Brain-Derived Neurotrophic Factor and Regulatory T Cell Populations

Abstract

BACKGROUND: Previous studies suggest beneficial effects of exercise in multiple sclerosis (MS). However, knowledge on the effects of physical activity on the immune system is limited. OBJECTIVE: To assess potential relationships between cardiorespiratory fitness, cognitive function, and immune parameters in physically active and inactive MS patients. METHODS: We identified 83 patients with relapsing-remitting disease, an unrestricted walking range, and stable interferon-β treatment from our data base. Based on the subjective report of physical activity, the lower/inactive (n = 21) and upper/active quartiles (n = 21) of patients were selected. We assessed the frequency of T cells, B cells, NK cells, monocytes and regulatory T cell populations by flow cytometry, measured brain-derived neurotrophic factor and vitamin D serum levels by ELISA, and conducted spiroergometry and transcranial sonography. RESULTS: Physical activity and cardiorespiratory fitness were not associated with brain-derived neurotrophic factor, frequency of T regulatory cells or any other immune cell subpopulation. However, we found a positive correlation of vitamin D serum levels with cardiorespiratory fitness. CONCLUSION: Overall, we found no negative effect of physical activity on the immune system. The association between vitamin D and cardiorespiratory fitness most likely reflects longer hours of sunlight exposure in active patients, suggesting a desirable 'side- effect' of physical activity.