Downregulation of CLDN1 impairs trophoblast invasion and endovascular trophoblast differentiation in early-onset preeclampsia

To investigate the role of claudin-1 (CLDN1) in trophoblast invasion and endovascular trophoblast (enEVT) differentiation in early-onset preeclampsia (EOPE).The expression and localization of CLDN1 in normal (n = 18) and EOPE (n = 20) placental tissues were detected by immunohistochemical (IHC) staining, quantitative real-time polymerase chain reaction (qRT‒PCR) and Western blotting. Next, invasion, migration and tube formation assays were performed to explore the involvement of CLDN1 in trophoblast invasion and enEVT differentiation in trophoblast cell lines (HTR8/SVneo). Then, invasion and enEVT markers were analyzed via Western blotting and qRT‒PCR, respectively. Finally, we established an EOPE mouse model to detect the Cldn1 protein level.CLDN1 expression was significantly decreased in EOPE placental tissues. Knockdown of CLDN1 suppressed HTR8/SVneo cell invasion, migration and the ability to penetrate the endothelial tube. Conversely, overexpression of CLDN1 promoted trophoblast invasion and the ability to invade the endothelial tube. Inhibition of CLDN1 decreased the protein expression of VIM and SNAIL along with downregulating IL1B and PECAM1 mRNA levels, while overexpression of CLDN1 gave the opposite results. In the EOPE mouse model, we found a decrease in Cldn1 expression in EOPE mouse placentas.These results suggest that the downregulation of CLDN1 in trophoblast cells is involved in the pathogenesis of early-onset preeclampsia by affecting trophoblast invasion and enEVT differentiation.