7A–C). In addition, whereas stressed mice demonstrated a significant increase in the frequency of splenic CD4+CD25+ T cells as compared with nonstressed mice (17.3 and 14.7%, respectively, p < 0.05; Fig. 7D and E), the fraction of CD127− cells among CD4+CD25+ T cells was significantly lower in stressed than in nonstressed mice in the spleen (76 and 82%, respectively, p < 0.05; Fig. 7D and E) and in the blood (65.6 and 77%, respectively, p < JQ1 purchase 0.01; Supporting Information Fig. 5A and B). Comparing the frequency of cells expressing CD127+ and CD127+ within splenic (Fig. 7D and F) and blood-derived (Supporting Information Fig.

5A and C) CD4+ T cells revealed a significant decrease in the CD127+/CD127+ ratio in stressed mice compared with nonstressed mice. This was evident primarily within the CD4+CD25high subpopulation MK-8669 in vivo and to a lesser extent within the CD25low population, but was not evident in the CD25+ subpopulation. Notably, the frequency of CD25+CD127+, but not CD25+CD127+, within splenic (Fig. 7G) and blood-derived (Supporting Information Fig. 5D) CD4+ T cells was significantly higher in stressed than in nonstressed mice. This indicates that the increased Teff/Treg ratio in stressed mice resulted from an increase in the effector T-cell population with no change in the Treg-cell population. The frequency of Foxp3+ cells and the CD127−/CD127+ ratio among CD4+CD25+

T cells were then examined following EAE induction. As shown in Figure 7H, whereas the frequency of splenic Foxp3 Treg cells among CD4+ T cells was generally reduced in stressed mice prior to EAE induction, no difference was observed between stressed and nonstressed mice following EAE. Similarly, no difference was observed in the CD127+/CD127+ ratio among blood-derived CD4+CD25+ T cells between stressed and nonstressed mice

following EAE induction or remission (Supporting Information Fig. 5E). Notably, both the frequency of Foxp3+ cells (Fig. 7H) and the CD127+/CD127+ ratio among CD4+CD25+ T cells (Supporting Information Fig. 5E) were reduced at EAE onset and gradually recovered toward disease remission. The present study aimed to test the effects of chronic variable stress on immunoregulatory processes involved in autoimmune diseases. Although stress has been traditionally considered to suppress the immune system and shift it toward an antiinflammatory Janus kinase (JAK) response through the secretion of CORT [3, 13], our results show that prolonged stress exposure exacerbates, rather than ameliorates, EAE in female C57BL/6 mice; this phenomenon, however, could be prevented by blocking CORT signaling throughout the stress exposure period. We also show that CORT levels under basal conditions are significantly lower in male than in female mice, which is associated with exacerbated EAE symptoms. Finally, we show that stress decreases the Treg/Teff ratio, and increases the Th1-Th17/Th2 ratio, within the Teff-cell subsets.