Exercise as both friend and foe for anti-viral immunity

Published: May 6, 2021

It has generally been considered that prolonged high-intensity exercise, such as a marathon, impairs anti-viral immunity, and exacerbates viral infections such as the common cold. On the other hand, there are some reports showing that people who exercise hard are less likely to catch colds. Thus, the influence of prolonged high-intense exercise on anti-viral immunity, and the underlying mechanism, have remained unclear. Therefore, we investigated whether prolonged high-intensity exercise is good or bad for anti-viral immunity, and the underlying mechanisms.

In a recent study published in The Journal of Allergy and Clinical Immunology (JACI), Adachi et al. evaluated the influence of prolonged high-intensity exercise on the severity of a herpes simplex virus type 2 (HSV-2)-intravaginal infection model in mice. Mice were infected with HSV-2 and then exposed to run on the treadmill for 3 hours at two different time point (8 hours or 17 hours after the viral infection). They compared the clinical phenotype of HSV-2 infection in mice with or without exercise.

Prolonged high-intensity exercise starting 8 hours after viral infection reduced the severity of HSV-2 infection, while the exercise starting 17 hours after the viral infection increased the severity. During the exercise, plasmacytoid dendritic cells (pDCs), an immune cell population that exerts anti-viral immune responses, moved from the blood to the bone marrow, and the number of pDCs in the blood showed a transient decrease, followed by a transient increase. The transient decrease and increase of the circulating pDCs were the cause of impaired or enhanced anti-viral immunity, respectively. The dynamics of pDCs in the blood was regulated by glucocorticoids.

Prolonged high-intensity exercise can be both good and bad in anti-viral immunity, depending on the interval between viral infections and exercise. Their results shed new light into our understanding of the effects of exercise on our health, and may lead to a development of novel therapeutic strategy to increase anti-viral immunity from the perspective of exercise.

The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.

Full Article