Neuroendocrine regulation of cytokine production during experimental influenza viral infection: effects of restraint stress-induced elevation in endogenous corticosterone.

A murine model of influenza viral infection was used to examine the neuroendocrine regulation of cytokine production. Restraint stress (RST) was used to activate the hypothalamic-pituitary-adrenal axis and elevate corticosterone (CORT) levels in influenza A/Puerto Rico/8/34 (PR8) virus-infected C57BL/6 mice. The type II glucocorticoid receptor antagonist RU486 was used to specifically examine the modulation of PR8 virus-specific cytokine responses by CORT. RST suppressed the PR8 virus- specific production of Th1-type (IL-2 and IFN-gamma) and Th2-type IL-10) cytokines by cells from the regional lymph nodes and spleens. In addition, IL-6 production by splenocytes was inhibited by RST; however, IL-6 production by cells from the regional lymph nodes was enhanced. Treatment of mice with RU486 prevented the effects of RST, suggesting that the RST-induced alterations in cytokine responses were mediated by CORT. Furthermore, CORT was shown to inhibit the PR8 virus-specific production of both Thl-type and Th2-type cytokines in vitro at doses corresponding to the physiologic range of free plasma CORT following hypothalamic-pituitary-adrenal axis activation.