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This Article Full Text Full Text (PDF) All Versions of this Article: 78/3/432    most recent biolreprod.107.063545v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Rettew, J. A. Articles by Marriott, I. PubMed PubMed Citation Articles by Rettew, J. A. Articles by Marriott, I. Agricola Articles by Rettew, J. A. Articles by Marriott, I.

Testosterone Reduces Macrophage Expression in the Mouse of Toll-Like Receptor 4, a Trigger for Inflammation and Innate Immunity

Department of Biology, University of North Carolina at Charlotte, Charlotte, North Carolina 28223

ABSTRACT

Though gender-based differences in the development of protective or pathological adaptive host responses have been widely noted, it is becoming apparent that sex may also influence the early perception of microbial challenges and the generation of inflammatory immune responses. These differences may be due to the actions of reproductive hormones, and such a hypothesis is supported by the presence of receptors for these hormones in a variety of immune cell types. Androgens such as testosterone have been shown to decrease immune functions, including cytokine production. However, the mechanisms by which testosterone limits such responses remain undefined. In this study, we have investigated the acute effects of testosterone on the level of expression of a key trigger for inflammation and innate immunity, Toll-like receptor 4 (TLR4), on isolated mouse macrophages. We show that in vitro testosterone treatment of macrophages, generated in the absence of androgen, elicits a modest but significant decrease in TLR4 expression and sensitivity to a TLR4-specific ligand. In addition, we have studied the effect of in vivo removal of endogenous testosterone on TLR4 expression and endotoxin susceptibility. We report that orchidectomized mice were significantly more susceptible to endotoxic shock and show that macrophages isolated from these animals have significantly higher TLR4 cell surface expression than those derived from sham gonadectomized mice. Importantly, these effects were not apparent in orchidectomized animals that received exogenous testosterone treatment. As such, these data may represent an important mechanism underlying the immunosuppressive effects of testosterone.

cytokines, immunology, testosterone