Spatial activation of autophagy in human placenta-related tissue during labor: a possible mechanism for labor onset

Introduction: The study aimed to explore the mechanism of labor onset via investigation on autophagy in placental tissues of normal pregnant women. Methods: : Placentas at the first, second, and third months of gestation and membrane samples from uniparous women without signs of uterine contractions (gestation group) were collected as well as placentas and membranes from uniparous women (parturition group) who underwent vaginal delivery (parturition-initiation group; PI group) or cesarean sections (parturition-non-initiation group; PNI group) without any medical complications. Autophagosomes were observed by transmission electron microscopy (TEM). Immunofluorescence and western blotting (WB) were used to quantify the protein levels of autophagy markers LC3A and LC3B in placenta and fetal membrane. TEM, immunohistochemistry (IHC) and WB were used to compare the autophagy in different parts of placenta and fetal membrane in the PI and PNI groups. Results: : TEM and IHC results showed that the number of autophagosomes and autophagolysosomes increased in the gestation group, and WB results suggested increased LC3B/A ratio between the placenta and the fetal membrane in gestation group. Autophagy in the maternal side of placenta in PI group was significantly increased, and the autophagy level in the placenta and fetal membrane near rupture became higher in both PI and PNI groups. Discussion: Autophagy can occur in placenta and fetal membrane, with its activity higher in the initiation of labor, indicating its role during labor.