Immunomodulatory effects of in vitro stress hormones on FoxP3, Th1/Th2 cytokine and costimulatory molecule mRNA expression in human peripheral blood mononuclear cells

Abstract

Background: Stress influences immune function through mechanisms including an impact on regulatory elements. We have previously demonstrated that glucocorticoids (GCs) and catecholamines can influence immunomodulation including changes in Th1/Th2 cytokine production. These immunoregulatory imbalances are associated with elevated cortisol in vivo and in the presence of GCs in vitro.

Methods: We examined the effects of dexamethasone (DEX) and epinephrine (EPI) on the balance of regulatory T cells (Tregs), Th1/Th2 cytokine gene expression by peripheral blood mononuclear cells (PBMCs) from 16 normal subjects after 24-hour and 11-day cultures with tetanus toxoid. We wished to determine whether the immunomodulatory effects of stress hormones involved differences in costimulatory signal pathways including CD28, CTLA-4 (CD152), and CD80/86.

Results: Our results revealed that FoxP3 mRNA expression (representing Tregs) was decreased in PBMCs cultured with DEX relative to the control within 24 h (short term). DEX decreased the Th1/Th2 cytokine mRNA balance after 11 days (long term). CD28 and CD80 mRNA were decreased in short-term incubation with DEX whereas the effect of inhibition by DEX on CTLA-4 mRNA was detected only in long-term cultures.

Conclusions: These results suggest that the Treg (FoxP3 mRNA) and CD28/CD80 costimulatory signal pathway may be a target of stress hormones in acute stress while the CTLA-4/CD80-86 pathway may be more susceptible in chronic stress.