Abstract 128: Role of Hypoxia-dependent Autophagy in the Trophoblast of BPH/5, a Mouse Model of Pre-eclampsia (PE)

Abstract

Autophagy, a mechanism of cell survival, plays an important role in normal placentation and protects the fetus during stress. Previously, we showed that autophagy was increased in fetoplacental units (FPUs) from pregnant BPH/5 mice, a model that develops a PE-like syndrome including late-gestational hypertension, proteinuria, abnormal placentation and poor feto-placental outcomes. We also showed that increased autophagy led to reduced invasion capacity of BPH/5 trophoblasts. Evidence suggests that hypoxia increase autophagy, so we measured the invasion capacity of trophoblasts isolated from C57 mice in normoxic/hypoxic conditions. Trophoblasts cultured in hypoxia exhibited defective invasion, effect partially blocked by autophagy inhibitor chloroquine diphosphate (CQ; 1.7-fold decrease, n=4 p<0.005 hypoxia vs. normoxia; 1.35-fold increase p<0.5 CQ vs. hypoxia). We also tested the effect of conditioned media from BPH/5 or C57 placental explants on the invasion capacity of JAR cells, a human choriocarcinoma trophoblast cell line. Conditioned media from BPH5 explants decreased JAR invasion, but only for 24h after placental collection (1.8-fold decrease, n=4 p<0.005 vs. C571.33-fold p<0.05 vs. BPH/5). However, when the explants were kept in hypoxia, JAR invasion capacity decreased following treatment with BPH5 explants conditioned media, even after 48h; effect partially inhibited by CQ (1.6-fold decrease, n=4 p<0.005 vs. CTR; 1.7-fold, n=4 p<0.05 vs. BPH/5). As autophagy plays a key role in the invasion of trophoblasts and thus remodeling of uterine arteries, we performed a tube formation assay with endothelial cells treated with conditioned media from BPH/5 or C57 placental explants. Tube formation decreased after treatment with conditioned media from BPH/5 explants (1.7-fold decrease, n=3 p<0.05). Co-culture of endothelial and trophoblast cells under hypoxia resulted in less efficient tube formation. Treatment with CQ partially blocked this effect (1.55-fold decrease, n=3 p<0.05 vs normoxia; 1.2-fold, n=3 p<0.05 vs hypoxia). These data demonstrate that invasion capacity and tube formation are defective in trophoblasts from BPH/5 mice, suggesting that hypoxia-dependent autophagy may play a causal role in PE in the BPH/5 model.