Poster Presentations

Problem: Epidemiological studies in humans implicate maternal expression of different combinations of KIRs, which are a family of cell surface receptors that tune cellular activation status, as being predictive in pregnancy complication onset (e.g., preeclampsia) and fetal health. This receptor family is expressed in both innate and adaptive immune cell populations, including the most abundant cell types found in the pregnant uterus. Due to limitations in studying human samples, a mouse model was generated in which the functionally homologous receptor family, Ly49s, has been globally deleted. The deletion of this gene complex leads to impaired vasculature formation and remodeling in mid-pregnancy, ultimately driving pregnancy defects, mirroring the correlations seen in the human population. However, the problem is that the mechanisms by which the lack of Ly49 receptors change immune cell function and leads to deleterious pregnancy outcomes remains unknown. Method of Study: To investigate the contributions of Ly49 receptors in pregnancy associated angiogenesis, we mated wildtype (WT) and Ly49−/− dams with WT sires and analyzed the implantation sites at gestational day 9.5. We performed a proteomic screen for expression of proteins known to be involved in angiogenesis, followed by verification via flow cytometry and western blot. Additionally, cultured WT and Ly49−/− uterine single cell suspensions were analyzed by flow cytometry and conditionedmedia was utilized an in-vitro angiogenesis assayusingamurineendothelial cell line, SVEC4-10, onaGeltrexextracellular matrix bed. Endothelial tube formation was imaged by light microscopy and quantified using ImageJ. Results: Ly49−/− dams at gestational day 9.5 display a skewed expression of angiogenesis related proteins, as compared to WT dams, with several proteins having significantly decreased abundance. VEGF expression in particular is 2–3-fold lower in Ly49−/− implantation sites, with this decrease coming from a non-immune cell population. Cultured Ly49−/− uterine cells display an increased production of pro-inflammatory cytokines compared to WT, including TNFa and IFNg, whose cellular source is from a monocyte/macrophage lineage. Conditioned media from Ly49−/− uterine cells leads to a significant anti-angiogenic effect, with a substantial decrease in endothelial tube branching and pronouncedmorphological changes. Conclusion: Together, these data indicate that loss of Ly49 receptors is leading to dysregulated immune cell function and production of