206. Identification of new candidate proteins involved in preeclampsia

Introduction Preeclampsia is a major disease of pregnancy, affecting 2–8% of pregnant women. It is characterized by arterial hypertension and proteinuria occurring from the 20th week of amenorrhea. The STOX1 overexpressing mice develop a preeclamptic syndrome. This model is very relevant to identify potential new actors in preeclampsia because the phenotype is both precocious and severe. Objectives Using this mouse model of severe PE, we aim to identify plasma proteins quantitatively modified during pregnancy with a global proteomics approach in the blood and to validate these proteins on human placental cell models. Methods We provoked preeclamptic gestations in mice by crossing WT females with transgenic STOX1 males. Blood was taken at E6.5 of gestation and plasma was analyzed using ITRAQ mass spectrometry to identify proteins of differential abundance. In parallel, we developed BeWo cells stably overexpressing STOX1. BeWo is a choriocarcinoma cell line in which fusion is induced by forskolin treatment and reproduces therefore the physiology of villous trophoblast that syncytialize into syncytiotrophoblast. We are validating the link between STOX1 overexpression and sLIFR production by qRT-PCR and ELISA in this cell model. Results We identified 15 proteins differentially present, two of which have human homologs: sLIFR (soluble Leukemia Inhibitory Factor Receptor) and TTR (transthyretin) respectively increased and decreased in the preeclamptic mice. In the BeWo cells, after fusion or in the presence of STOX1, alternative splicing of LIFR mRNA increases, leading to more secretion of sLIFR in the supernatant. Discussion An early excess of sLIFR could trap Leukemia Inhibitory Factor (LIF) at early stages of embryo implantation and development. Given the primordial role of LIF in implantation in mice and humans, this could lead to a defective implantation and/or placentation possibly causing embryo resorptions or a preeclamptic phenotype.