155. UNDERSTANDING THE CROSSTALK IN THE HUMAN UTERINE CAVITY: ROLES FOR SOLUBLE MEDIATORS DURING EMBRYO IMPLANTATION

Abstract

Embryo implantation requires synchronized dialogue between a receptive endometrium and an activated blastocyst via locally produced soluble mediators. During the mid-secretory (MS) phase of the menstrual cycle there is increased glandular secretion into the uterine lumen. These secretions contain important mediators that modulate the endometrium and support the conceptus during implantation. Analysis of the composition of uterine fluid across the menstrual cycle and in fertile and infertile women will, therefore, provide new insights into uterine receptivity. We hypothesized that multiplex platform analysis of human uterine lavages would identify soluble mediators important for the establishment of pregnancy in humans. Lavages were collected (by flushing the uterine cavity with 5mL of saline) from fertile and infertile women during the MS phase and from fertile women during the mid-proliferative (MP) phase of the menstrual cycle. Comparison of lavages from the three cohorts was performed using quantitative MilliplexTM Luminex® cytokine/chemokine assays containing 42-analytes. Luminex analysis detected a number of cytokines in uterine fluid, revealing 8 soluble mediators previously unknown in the endometrium and present in human uterine fluid including, PDGF-AA, TNFβ, sIL-2Rα, Flt-3 ligand, sCD40L, IL-7, IFNα2 and GRO. Furthermore comparison of the three cohorts revealed VEGF levels were significantly higher in the fertile (MS) fluid when compared to infertile. Functional studies demonstrated that rhVEGF treatment significantly increased the adhesive properties in cells present at the maternal-fetal interface. These findings suggest VEGF plays a role in regulating embryo implantation. Furthermore identifying the soluble mediators in uterine fluid may provide potential markers of endometrial receptivity, insight into the unique microenvironment essential for pregnancy and a profile of maternal factors that influence the implanting blastocyst.