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Abstract

Objectives Autophagy is an intracellular degradation system for energy production under stress. We have studied the role of autophagy in extravillous trophoblast (EVT) invasion and vascular remodeling under hypoxia. Methods EVT cell lines, HTR8/ SVneo and HchEpC1b, were used. We have established autophagy deficient EVT cell lines by infection of ATG4BC74A mutant expression vector. Autophagy was evaluated by the detection of LC3 dot formation by immunohistochemistry and L3C-IIby western blotting. Vascular remodeling was evaluated by tube formation assay using EVT cells and endothelial cells co-culture system. This study was approved by ethics committee of University of Toyama. Results Autophagy was observed in EVT cells under hypoxia or CoCl2 treatment. In wild type EVT cells, the invasions of EVT were enhanced under hypoxic condition. On the other hand, the invasion and vascular remodeling were significantly reduced in autophagy deficient EVT cells compared with wild type EVT cells under hypoxia. Importantly, soluble endoglin (sEng) suppressed EVT invasion and vascular remodeling under hypoxia by inhabitation of autophagy formation. Soluble Flt-1 and TNFα did not affect the autophagy formation under hypoxia. CoCl2, which induces hypoxia inducible factor 1α (HIF-1α) over-expression, activated autophagy in EVT cells even in normoxic condition. Cell invasion in autophagy deficient EVT cells were reduced by CoCl2 treatment through the suppression of MMP-9 level and cellular ATP levels. Decreased invasiveness was neutralized by ATP supplementation. P62 which is selectively degraded by autophagy accumulated in interstitial EVT and vascular EVT in placental biopsy samples of preeclampsia (n = 10), but not in FGR cases, suggesting that autophagy is impaired in EVT of preeclampsia, but not in FGR. Conclusions Impaired autophagy by sEng, through decreased EVT invasion and vascular remodeling, is one of the etiologies of poor placentation in preeclampsia. Disclosures S. Saito: None. A. Nakashima: None.