Epidermal growth factor rescues trophoblast apoptosis induced by reactive oxygen species

Abstract

Pre-eclampsia and intrauterine growth restriction are associated with increased apoptosis of placental villous trophoblast. This may result from placental hypoperfusion, leading to the generation of reactive oxygen species (ROS). Apoptosis can be induced in villous trophoblast following exposure to oxidative stress. Epidermal growth factor (EGF) reduces trophoblast apoptosis resulting from exposure to hypoxia. We hypothesised that exposure to hydrogen peroxide, a potent generator of ROS, would induce apoptosis in term placental villous explants and that this could be reduced by treatment with EGF. Placental explants were taken from normal term pregnancies and exposed to increasing doses of hydrogen peroxide (0-1,000 microM) or to a combination of increasing doses of hydrogen peroxide and EGF (0-100 ng/ml) for either 6 or 48 h. Apoptosis was assessed by TUNEL, proliferation by Ki-67 immunostaining, necrosis by lactate dehydrogenase activity and trophoblast differentiation by human chorionic gonadotrophin (hCG) secretion in conditioned culture media. Immunoperoxidase staining was performed to identify phosphorylated-AKT (p-AKT) and phosphorylated-PI3 kinase (p-PI3k). Exposure to 1,000 microM hydrogen peroxide for 48 h induced apoptosis in placental explants. The increase in TUNEL positive nuclei predominantly localised to syncytiotrophoblast. The amount of apoptosis was reduced to control levels by treatment with 10 and 100 ng/ml EGF. Proliferation of cytotrophoblasts within villous explants was significantly reduced following exposure to 1,000 microM hydrogen peroxide, this was restored to control levels by simultaneous treatment with 10 or 100 ng/ml EGF. Neither exposure to hydrogen peroxide or EGF altered the amount of necrosis. There was increased immunostaining for pPI3K following treatment with EGF. This study shows that apoptosis may be induced in villous trophoblast following exposure to ROS, and demonstrates the anti-apoptotic effect of EGF in trophoblast, the maintenance of which is essential for normal pregnancy.

Evidence for Immune Cell Involvement in Decidual Spiral Arteriole Remodeling in Early Human Pregnancy

“…The protocol was followed according to the manufacturer's instructions with minor modifications, as previously reported. 25 Negative controls involved application of labeled-dUTP to sections in the absence of TdT enzyme.…”

“…To determine the extent of vascular remodeling, qualitative analysis was performed on 50 vessels selected randomly from the total 25 immunostained decidua basalis samples, to assess the degree of VSMC and endothelial cell disruption and loss, and the presence or absence of vEVTs. Vessels were classified into four different types, based on the combination of attributes and this was tested by three independent observers blind to the identity of the tissue.…”

Increased risk for the development of preeclampsia in obese pregnancies: weighing in on the mechanisms

“…Trophoblast cells express ET precursors and receptors (163). Fiore et al (47) showed that exaggerated levels of ET-1 trigger placental villi to produce reactive oxygen species, which promote trophoblast apoptosis (47,116). Placentas from preeclamptic pregnancies have increased placental oxidative stress and ET-1 binding (8,22).…”

Maternal growth factor regulation of human placental development and fetal growth

“…Recently, several studies have suggested that soluble factors in the maternal circulation, including growth factors, can influence placental development and function (Baczyk et al 2005, Johnstone et al 2005b, Sferruzzi-Perri et al 2006, Moll et al 2007, Forbes et al 2008, 2010a,b,c, Hoffmann et al 2009). This review will examine the role of such growth factors in the regulation of trophoblast function by briefly discussing their effect on extravillous trophoblast invasion (see the recent review by Knofler (2010) for more detail on this topic), and focussing in detail on the control of villous cytotrophoblast proliferation and function.…”

“…EGF promotes trophoblast proliferation and cell survival by stimulating PI3K/AKT pathway (Johnstone et al 2005a, Moll et al 2007, while in placental stromal cells, the PI3K/AKT pathway is required for FGF2 and vascular endothelial growth factor-stimulated endothelial cell proliferation (Wang et al 2009). It is now emerging that PI3K/AKT may also play additional roles within the placenta by regulating expression of leptin (Gambino et al 2010), a known mediator of trophoblast proliferation and survival (Magarinos et al 2007).…”