The autophagy process and oxidized LDL independently modulate the invasion and differentiation of extravillous trophoblastic cells to an endothelial-like phenotype in normoxia

Introduction: The mechanisms leading to proper placentation are not fully understood. Extravillous trophoblasts (EVTs) are crucial for placentation through invasion and vascular remodeling, which, when impaired, promote a poor placentation. How autophagy could regulate EVTs function and the study of regulators of these processes, such as oxidized low-density lipoproteins (ox-LDL), could contribute to better understand events associated with pregnancy complications related to abnormal placental development, such as preeclampsia (PE). Aim: To investigate the role of autophagy and oxidized LDL (ox-LDL) in invasion and endothelial-like phenotype acquisition of a model of EVTs, as well as to determine the levels of autophagy flux markers in control and PE placentas. Methods: Invasion and endothelial-like phenotype acquisition assays were performed in a cell line model of first trimester EVTs: HTR-8/SVneo cultured in normoxia (oxygen concentration of 20 %), in the absence or the presence of the autophagy inhibitor bafilomycin or/and ox-LDL. Markers of autophagic flux were evaluated in human term placentas. Results: Autophagy is essential for EVTs to acquire an endothelial-like phenotype but does not affect invasion. Conversely, ox-LDL decreases invasion and reticular structures formation, independent of autophagy. At pregnancy term, the levels of the autophagy markers LC3 and p62 are deregulated in the trophoblast cells of PE placentas. Conclusion: Autophagy is necessary for proper endothelial-like phenotype acquisition in HTR-8/SVneo cultured in normoxia, and ox-LDL impairs this process as well as the invasion of EVTs by a mechanism independent of autophagy. Changes in autophagy and/or in the concentration of ox-LDL could affect placental vascular remodeling.