Many obstetrical complications, including preeclampsia and intrauterine growth retardation, two of the more significant causes of maternal and fetal morbidity/mortality, are associated with trophoblast dysfunction and aberrant vascular function. However, the molecular mechanisms responsible for these functional defects are poorly understood. Trophoblasts normally produce high levels of the angiogenic growth factor, placenta growth factor (PGF). PGF binds to its membrane associated receptor (Flt1) expressed on different cell types including endothelial cells and trophoblast where it promotes vasodilation, angiogenesis and cell survival. Clinical studies have confirmed that expression of PGF is significantly reduced;while a splice variant and soluble form of Flt1 (sFlt1) is dramatically increased, prior to and during preeclampsia. The resulting "anti-angiogenic" environment contributes to the clinical symptoms that define preeclampsia: hypertension and proteinuria. Although we and others have shown that oxygen tension can regulate trophoblast expression of PGF and sFlt1, we now have convincing novel data indicating similar dysregulation of these genes in human trophoblast by pro-inflammatory pathway activation, also a common occurrence in preeclampsia. Importantly, these effects are independent of oxygen tension. The goal of our studies is to delineate the molecular mechanisms by which pro-inflammatory pathway (NFkB) activation induces aberrant PGF and sFlt1 expression in human trophoblast. We will use a combination of in vitro gene manipulation approaches correlated with ex vivo studies of human placentae in the following specific aims to accomplish this goal. We have shown that GCM1, a placenta-specific transcription factor, is a principal regulator fPGF expression in trophoblast.
Aim1 will characterize the molecular mechanisms by which activated NFkB subunits influence PGF transcription directly by altering GCM1 activity.
Aim 2 will determine transcriptional and post transcriptional regulatory mechanisms mediated via pro-inflammatory pathway activation that increases trophoblast sFlt1 expression.
Aim 3 will utilize ex vivo human placentae cultures to recapitulate expression differences in PGFandsFlt1 expression in normal villi following pro-inflammatory pathway activation. Results from these studies will provide novel mechanistic information regarding the ability of pro- inflammatory signaling, independent of oxygen tension, to regulate the balance of PGF and sFlt1 expression in human trophoblast. Collectively, these approaches will facilitate a better understanding of mechanisms that contribute to vascular function during normal and perfusion compromised pregnancies and may provide new therapeutic avenues for treatment. We also expect that information gained from these studies will have broad applicability to vascular biology since sites of angiogenesis in adults are associated with inflammation.
Inadequate blood vessel formation and/or function during pregnancy contributes to a number of obstetrical complications, the most common being preeclampsia. It is well accepted that altered production of pro- and anti-angiogenic proteins by the placenta regulate blood vessel function and directly contributes to systemic disease. How this imbalance occurs is not known. This application will begin to determine the novel molecular mechanisms responsible for aberrant expression of two prominent pro- and anti-angiogenic factors produced by placental cells.