Neuroendocrine and Lymphocyte Responses to Varied Intensities of Exercise

Abstract

Introduction: Dual stress challenges combine the stress of exercise with additional psychological stresses. Under many circumstances, such as military training, these stresses are inseparable. The dual stress challenge provides an appropriate model to look at neuroendocrine changes with exercise, under “real-life” circumstances. The endocrine part of this response to exercise and stress has been well documented, but the effects of these stimuli on the immune system are still being elucidated. Conventional understanding of exercise immunology says that exercise has an immunosuppressive effect. However, as the body of literature grows, this belief has come into question, as more information regarding the migration of immune cells from blood to tissue has become available. Methods: Two experiments approached this question from different directions. The first study looked at alterations in whole immune cell populations in response to bouts of Marine Corps Martial Arts Training Program (MCMAP), using elevated and standard intensity training bouts to compare immunoendocrine responses between moderate and high intensity exercise. Blood was collected from nineteen female and thirty-six male volunteers from the United States Marine Corps at pre-, immediate-post, 15 min, 30 min, 45 min and 60 min post-exercise and sent off for analysis of immunoendocrine variables. The second study used RNA-sequencing to find differentially expressed genes (DEG) in CD4+ T-cells following exercise. Blood was drawn from six volunteers before and 20 min following a dual stress challenge. CD4+ T-cells were then isolated, and RNA was extracted to undergo RNA-sequencing. Ingenuity Pathway Analysis (IPA) was used to analyze the pathways most affected by these DEG. Conclusions: MCMAP training elicited similar immunoendocrine responses as have been shown in past dual stress challenge studies. RNA-sequencing identified a number of novel genes related to signaling pathways in CD4+ T-cells. Combined, these two studies tie together the innate and adaptive immune responses to exercise by combining changes in whole cell populations of innate and adaptive cells with intracellular signaling changes from CD4+ T-cells, which make up a large population of adaptive immune cells in the human body. This information provides a novel mechanism for CD4+ T-cell function with exercise and how this could play a role in overall immune function under these conditions.