Estrogen suppression of macrophage-derived IL-6 restores immunity in male mice given ethanol and burn injury

The first set of experiments examined the influence of the macrophage on cellular immunity when mice were given an ethanol injection resulting in 100 mg/dl or 300 mg/dl prior to burn. Mice with moderate (100 mg/dl) circulating levels of ethanol at the time of burn had suppressed DTH and splenocyte proliferative responses to Concanavlin A, which was augmented when mice were given the high (300 mg/dl) dose of ethanol before burn. Although circulating and macrophage IL-6 concentrations were increased with moderate ethanol, this was augmented only in the circulation of mice treated with high ethanol before burn. Culture of splenocytes with αCD3ϵ or macrophages depletion restored proliferation only in cultures generated from the moderate ethanol/burn mice.; The second set of experiments focused on the ability of estrogen (E ₂) treatment to modulate immunity in mice given the moderate dose of ethanol (ethanol/burn) prior to burn injury. E₂ (80 ng) or oil (control) was given at 30 min and 24 hr post-injury. E₂ treatment restored the DTH and splenocyte proliferative responses, reduced secretion of macrophage-derived IL-6, and increased in survival of bacterial challenge. Moreover, in vitro neutralization of IL-6 restored splenocyte proliferation in ethanol/burn (oil) treated mice, but had no influence when mice were treated with E₂. Furthermore, macrophage supernatants generated from ethanol/burn (oil) mice, but not E₂ treated mice, suppressed proliferation, which was ameliorated by the addition of IL-6 neutralizing antibodies.; The final series of experiments sought to determine the mechanism through which E₂ was modulating the IL-6 mediated immune suppression in this injury model. An increase in NF-κB activation in unfractionated splenocytes and splenic macrophages from ethanol/burn mice was observed using the electrophoretic mobility shift assay (EMSA). Furthermore, treatment of ethanol/burn mice with E₂ reduced NF-κB activation to baseline in the absence of detectable changes in cellular NF-κB or IκBα protein expression, or phosphorylation by western blot. Immuno-histochemical analysis of ERα and ERβ showed no differences in receptor expression in the spleen regardless of injury or E₂ treatment. Additional in vitro studies suggested that E₂ was modulating IL-6 production by splenic macrophages directly.; In conclusion, the studies presented in this dissertation show that administration of estrogen can restore the macrophage-mediated, IL-6 dependent, suppression of cell-mediated immunity in a murine model of ethanol exposure followed by burn injury via modulation of macrophage NF-κB activation.