Endogenous glucocorticoid increases the basal level of Treg-Th17 balance under early phase of stress

Objective： To explore the changes of Treg-Thl 7 balance influenced by corticosterone, major ef- fect hormone ofhypothalamic-pituitary-adrenal （HPA） axis under running stress. Methods： Atotal of 25 corticotropin-releasing hor- mone （CRH） wildtype （CRH＋/＋） and knockout （CRH-/-） mice were adopt and divided into 4 groups as follows： CRH＋/＋ ctrl, CRH＋/＋ stress, CRH-/- ctrl and CRH-/- stress. All mice in stress groups were under 2 h running. After 1 h, blood plasma in all groups was collected and the ex- pression of corticosterone and IL- 17A was detected by ELISA. Meanwhile, unicell suspensions of peripheral lymph node and spleen in each group were prepared too and stained by PE-CD4 and FITC-CD25, then the changes of Treg （CD4＋CD25＋） in different groups were checked by flow cytometry; all data were statistically analyzed by the software of WinMDI 2.9, SPSS 11.5, Origin 7.5 and Matlab 2-D and 3-D plot function. Results： The levels of corticosterone were signifi- cantly higher in stress groups than that in correspond- ing control groups （P〈0.05）, especially in CRH＋/＋ stress group （P〈0.01）. However, the changes of Tregs were not obvious between stress groups and control groups with respective genotypes （P〈0.05）. Compared with that in CRH＋/＋ control group, the ratio of Treg and the expres- sion of IL-17A in CRH-/- stress group were significantly higher than those in control group （P〈0.05）. Combined with the expression levels of corticosterone, Treg and Thl7, our study suggests that endogenous glucocorti- cold with basal level may cause the changes in Treg- Thl7 balance. Moreover, as the corticosterone level increases, the expression of Treg and Thl7 appears to manifest antagonistic fluctuant status with a rising ten- dency in general. Conclusion： Endogenous glucocorticoid under early stage of stress may increase the function of T lymphocyte immunity to some extent.