Toll-like receptor 9 is required for chronic stress-induced immune suppression

摘要

Psychological and physical stress can suppress the immune system in both humans and animals. The mechanism by which stress affects immune responses, however, remains poorly defined. Toll-like receptors (TLRs) play a key role in modulating immune responses and cell survival. The mechanisms by which TLRs modulates chronic stress are largely unexplored. In current study, we revealed that a deficiency of TLR9 is resistant to chronic stress-induced lymphocyte apoptosis. In addition, TLR9 knockout (KO) mice significantly diminish the chronic stress-induced up-regulation of corticosterone levels. Notably, we found that lymphocytes from both TLR9 KO mice and wild type mice were similarly sensitive to corticosteroid-induced cell apoptosis. Moreover, we demonstrated that a deficiency of TLR9 blocks chronic stress-induced imbalance of Th1 and Th2 cytokine levels. Taken together, our findings reveal that TLR9 plays an essential role in chronic stress-induced immune suppression.