Do progesterone receptor membrane components (PGRMC)s play a role in the chorions refractoriness to epithelial-to-mesenchymal transition (EMT)?

Fetal membrane inflammation is one of the drivers of adverse pregnancy outcomes. One of the reported pathways of inflammation is epithelial-mesenchymal transition (EMT) of amniotic epithelial cells. EMT is resisted during gestation via signaling initiated by the binding of progesterone (P4) to progesterone receptor membrane components (PGRMC1/PGRMC2). The vulnerability of chorionic trophoblast cells (CTCs) to transition has not been studied. Here, we examined CTCs EMT in response to the stressors and the role of PGRMC1/PGRMC2. CTCs were treated with the autophagy inhibitor bafilomycin (Baf), transforming growth factor beta (TGF-β, EMT-inducer), and lipopolysaccharide (LPS) to simulate cellular stressors associated with an adverse pregnancy environment. The primary endpoints included morphological evidence of EMT, N-cadherin-to-E-cadherin ratio, vimentin/cytokeratin staining, pro-inflammatory cytokine and P4 production. PGRMC1/PGRMC2 knock-out (KO) CTCs were prepared using CRISPR/Cas9, and experiments were repeated to test the influence of the P4-PGRMC axis. Wild-type CTCs were resistant to cellular transitions, changes in P4 production, and shifts in the inflammatory status under normal, LPS, or TGF-β conditions. Autophagy inhibition tended to cause CTCs to transition (morphological changes; high N-cadherin-to-E-cadherin ratio [p < 0.05], no change in vimentin/cytokeratin), though a complete transition was not evident. Further, neither PGRMC1/PGRMC2 played a role in CTC cellular transitions, as their KO did not cause any major changes. Chorion cells resist EMT to minimize inflammation and to maintain their barrier functions regardless of the presence of PGRMC1/ PGRMC2. Cellular stressors or infectious antigens are likely to impact the amnion, where membrane weakening can be initiated.