ENDOTHELIAL ACTIVATION BY CYTOKINES AND FATTY ACID

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Preeclampsia is a serous obstetrical syndrome characterized by hypertension, proteinuria and generalized edema, that affects about 7 percent of pregnant women. Despite its recognition since antiquity, the current treatment of this disorder is not based on an understanding of its pathophysiology but remains empirical: delivery of the fetus and placenta. The high maternal and neonatal morbidity and mortality associated with preeclampsia results from the iatrogenic preterm interruption of affected pregnancies. The cellular biology that underlies this syndrome remains a mystery. The studies proposed in Project 0002 of the application extend our ongoing investigation of maternal vascular endothelial dysfunction in preeclampsia, but with the specific focus of understanding the biochemical pathways involved in abnormal fatty acid and prostanoid metabolism. For more than 15 years it has been recognized that prostaglandin production is abnormal in maternal and fetal tissues affected by preeclampsia. The proposed studies will address possible mechanisms of endothelial activation in this syndrome. Two cytokines, TNF-alpha and endothelin-1, have been identified by Drs. Conrad (Project 0005) and Taylor in the plasma of preeclamptic women and by Drs. Fisher and McLaughlin (Projects 0003 and 0004) using in vitro models of placental hypoxia. In Specific Aim #1, we will investigate the abilities of these cytokines to activate key regulatory enzymes (phospholipases A2 and cycloozygenase-2) involved in endothelial cell prostaglandin production. The induction, modification (i.e., phosphorylation) and activity of these enzymes will be assessed in human umbilical and decidual endothelial cells. Regulation of fatty acid binding and delivery into endothelial cells by albumin isoforms is addressed in specific Aim #2. Toxicity preventing activity (TxPA), a pI-5.6 isoform of plasma albumin, will be purified to study its lipid binding and its ability to modulate the availability of intracellular fatty acid precursors of prostanoid production. In Specific Aim #3 the activation of peroxisome proliferator activated receptors (PPARs) by extra- or intracellular fatty acid metabolites will be addressed. Endothelial cell PPARs will be identified and transfected recombinant peroxisome proliferator response element (PPRE) reporter constructs will be used to screen for prostanoid activators of these nuclear receptors. The proposed studies will characterize the pathways by which cytokines and fatty acids activate endothelial cells in preeclampsia. These molecules should provide ideal targets for the future development of therapeutic antagonists which ultimately could lead to the rational treatment and possible prophylaxis of preeclampsia.