Estrogen restores cellular immunity in injured male mice via suppression of interleukin-6 production

This study examined whether estrogen treatment can improve immunity in male mice after combined ethanol and burn injuries. 17beta-Estradiol [estrogen, given subcutaneously (s.c.)] or oil (control) was administered at 30 min and 24 h postinjury. At 48 h postinjury, ethanol/burn-injured mice demonstrated significant suppression of cellular immunity. Estrogen treatment restored the delayed-type hypersensitivity (P<0.01) and splenocyte-proliferative (P<0.05) responses, reduced macrophage interleukin-6 (IL-6) (P<0.05), and increased survival after bacterial challenge (P<0.01). In vitro neutralization of IL-6, combined with macrophage supernatant experiments, confirmed that the beneficial effects of estrogen treatment were mediated through modulation of macrophage IL-6 production. Moreover, estrogen treatment resulted in a decrease in splenic nuclear factor-kappaB (NF-kappaB) activation in injured mice. There were no changes in cellular NF-kappaB or IkappaBalpha protein expression or IkappaBalpha phosphorylation at serine 32. Taken together, these studies suggest that estrogen treatment of injured male mice improves cellular immunity through direct modulation of NF-kappaB activation.