A current hypothesis for the etiology of pre-eclampsia is that endothelial dysfunction is secondary to oxidative stress and some clinical studies have indicated that prophylactic administration of anti-oxidants may be useful in its prevention. A much larger trial utilizing the anti-oxidants vitamin C and vitamin E is, at present, being carried out by the Maternal-Fetal Network of the NICHD to assess their effectiveness in the prevention of pre-eclampsia. Endothelial cell activation is usually a constant accompaniment with this condition. Endothelial cell activation leads to endothelial cell dysfunction and is also accompanied by expression of adhesion molecules, i.e. vascular cell adhesion molecule-1 (VCAM-1), and other adhesion molecules. This leads to adhesion of monocytes to endothelial cells resembling early atherogenesis. There is evidence in the literature that tumor necrosis factor a (TNFa) may be released by the placenta and activated leukocytes leading to activation of endothelial cells. The current proposal will mainly focus on mechanisms by which estrogens and anti-oxidants prevent TNFa-induced endothelial cell activation and apoptosis. We will, therefore, test the following four hypotheses. Hypothesis 1: Exposure of endothelial cells to TNFa leads, initially, to activation of the cells leading to VCAM-1 expression and increased synthesis of anti-apoptotic proteins, followed by stimulation of the survival pathway. Hypothesis 2: Estrogen and its metabolites prevent TNFa-induced activation, as well as apoptosis of HUVEC, by increasing the expression of eNOS and phosphorylation of Akt and ERK 1/2, in spite of the absence of migration of NFkB to the nucleus, thereby, directing the cells to the """"""""survival pathway"""""""". Hypothesis 3: Anti-oxidants prevent endothelial cell activation and inhibit NFkB migration to the nucleus following exposure of endothelial cells to TNFa by an NO-independent Fak-mediated mechanism. Hypothesis 4: Anti-oxidants attenuate apoptosis in endothelial cells exposed to TNFa by upregulation of ERK 1/2 phosphorylation and downregulation of p38 phosphorylation. Results from these studies will also help explain the different mechanism(s) by which estrogens and anti-oxidants prevent activation of endothelial cells and apoptosis and, thereby, lay the scientific foundation by which anti-oxidants administered to women may prevent pre- eclampsia in women at risk of developing this condition. Pre-eclampsia is a condition that suddenly develops during pregnancy and is accompanied by high blood pressure, swelling of the body, and leakage of proteins. This condition can adversely affect both the mother and the fetus. Pre-eclampsia is more prevalent in Afro-Americans and is also seen in the lower socio-economic groups. Results from our studies will indicate to us which anti-oxidants are likely to be more effective than others and which can be used clinically to prevent this condition. ? ? ?
| Janzen, Carla; Sen, Suvajit; Cuevas, Janis et al. (2011) Protein phosphatase 2A promotes endothelial survival via stabilization of translational inhibitor 4E-BP1 following exposure to tumor necrosis factor-?. Arterioscler Thromb Vasc Biol 31:2586-94 |
