Estradiol suppresses psoriatic inflammation in mice by regulating neutrophil and macrophage functions.

BACKGROUND:Psoriasis is a common inflammatory skin disease resulting from dysregulation of the IL-23/TH17 immune axis. The prevalence and severity of psoriasis is higher in men than in women, although the underlying reasons for this are unclear. OBJECTIVE:We studied whether estradiol, a female hormone, plays protective roles in imiquimod-induced psoriatic inflammation in mice by regulating neutrophil and macrophage functions. METHODS:Wild-type mice and conditional knockout mice were ovariectomized, supplemented with placebo or estradiol pellets, and an imiquimod-containing cream applied. RESULTS:Mice without endogenous ovarian hormones exhibited exacerbated psoriatic inflammation including increased production of IL-17A and IL-1β, which was reversed by exogenously added estradiol. The suppressive effect of estradiol on the production of IL-1β and IL-17A was abolished in mice lacking estrogen receptors in neutrophils and macrophages (Esr1f/fEsr2f/fLysM-Cre+ mice). IL-1β, which is required for production of IL-17A in the psoriasis model, was mainly produced by neutrophils and inflammatory macrophages. Estradiol suppressed IL-1β production from neutrophils and macrophages in mice both in vivo and in vitro and from human neutrophils in vitro. CONCLUSION:Our results suggest a novel mechanism for sex-dependent differences in psoriasis clinical phenotypes that may shed new light on the pathology of psoriasis.