Effect of acute or subchronic stress on T cell response in peripheral blood: Regulatory role of vitamin D

The immune response, orchestrated by helper (Th1, Th2, and Th17) and regulatory (Treg) T cells, is modulated by stress and Vitamin D (Vit-D). Although the immunomodulatory functions of both are known, their specific roles on Th cells have not been fully clarified, yet. On this background, we aimed to investigate the effect of acute or subchronic stress on the distribution of peripheral T lymphocytes, as well as the immunomodulatory role of Vit-D. Young adult male, Swiss-albino mice (30–40g) were allocated to the control, acute stress (AS), subchronic stress (ChS), control+Vit-D, AS+Vit-D, and ChS+Vit-D groups (n=11/group). The combined cold (2-h at 4°C)-immobilization (2-h in a restrainer) stress protocol was employed as one day in AS groups and five consecutive days in ChS groups. Vit-D (2?g/kg ip) was applied every other day, until the end of the protocol. Serum cortisol, Vit-D and cytokine levels (IL-4, IFN-?, and IL-17A) were measured, and lymphocytes from blood samples were subtyped by flow-cytometry. Stress exposure caused differential Th and Treg responses, acute stress shifting the response to Th1, and subchronic stress shifting the response to Th2. Th17 and Treg cells were lower in subchronic stress exposed mice. These changes became comparable to control values in Vit-D treated groups. The T cell response, crucial for immune system function, differs on the basis of stress exposure as such the Vit-D treatment. The tolerogenic profile created by Vit-D should be considered for management of stress-related diseases. Our results may help to provide a better understanding of disease pathogenesis.