287. LPS introduced at mating induces KC production in the murine uterus during early pregnancy

Abstract

An inflammatory cascade is elicited in the female reproductive tract following mating in mice. The recruited leukocytes and cytokines have roles in facilitating implantation through activating immunological tolerance and endometrial tissue remodelling. We have previously shown that seminal plasma acts to induce synthesis of GM-CSF and IL-6 in the female reproductive tract in response to TGFβ₁ present in seminal fluid. Recently we have shown that chemokines, specifically the neutrophil chemoattractant KC, is dramatically upregulated after mating. The purpose of this study was to identify the active constituent of semen responsible for KC induction. Female mice were mated with either intact, seminal vesicle deficient or vasectomized males and uterine flushings were collected approximately 8 h later, when KC content was measured by specific ELISA. KC production was increased 13-fold, 6-fold and 10-fold respectively, indicating that neither the seminal plasma nor the sperm fraction of semen was necessary for induction. To investigate more precisely the identity of the KC inducing factor, an in vitro primary uterine epithelial cell culture system was employed. Uterine epithelial cells were harvested from estrous female mice and exposed to a range of doses of seminal vesicle fluid, TGFβ₁or lipopolysaccharide (LPS). Following addition of seminal vesicle fluid or TGFβ₁ KC production was decreased by 100% and 58% respectively whereas it was increased ~2-fold in response to LPS. Together these data indicate that LPS derived from the male or lower female reproductive tract accessing the uterus after insemination is required for KC induction, and implicate commensal bacteria as having a key regulatory role in the cellular and molecular quality of the uterine immune environment during early pregnancy.