Markers of epithelial-mesenchymal transformation in placentas from very early preterm births
Authors: Tkalich V.O. , Bila V.V. , Zahorodnia O.S. 
Published: October 2024

Premature birth complicates one in ten births in the world, two-thirds of which are caused by spontaneous labor and premature rupture of membranes (PROM). The opinion about the inflammatory origin of preterm birth is generally accepted, more and more attention is devoted to the phenomena of epithelial-mesenchymal transformation (EMT).The objective: to study markers of cell proliferation and EMT in samples of placentas from very early preterm, early preterm and term births.Materials and methods. Placenta samples were examined from 101 women who had labour at 22–27 weeks of gestation on the background of PROM (I group), 102 women who had labour at 22–27 weeks on the background of intact fetal membranes (II group), 100 women who had labour at 28-34 weeks on the background of PROM (III group) and 102 women in labour – at 28-34 weeks on the background of intact membranes (IV group). Samples of 60 placentas from timely normal births were included in the control group.The presence of proliferation factor Ki-67 was determined in placenta samples by immunohistochemical method, cytokeratin-18 content was determined in 10 placentas of each group, and vimentin – in 10 amniotic membrane samples. Regarding the proliferation antigen Ki-67, the placentas were divided according to the detection of the sign in the distal, proximal and basal villi. The expression of cytokeratin and vimentin in syncytium and amnion cells was measured in conventional units and compared between groups.The statistical evaluation of the obtained differences was carried out using the Student’s test.Results. Proliferation antigen Ki-67 was detected in 61.9% of all placentas, including term births. In the groups of very early preterm birth (PB), they were detected mainly in villi of distal localization – in 44.6% in the group of PROM and in 51.0% – in the group of labour on the background of intact membranes. In the case of deliveries on the background of intact membranes in extremely premature terms, only 22.5% of the samples had a positive antigen in the basal villi, on the background of PROM in these terms – in 36.7%, in the groups of early PB – in 79.4% and 74.0% respectively.Distal Ki-67 expression in such placentas was a rare finding – 10.0% in the III group, 11.8% – in the IV group, and 8.3% – in placentas from term deliveries.In all gestational periods, the expression of cytokeratin in amniotic membranes in placentas from births on the background of PROM is statistically lower than in placentas from births on the background of intact membranes.In the case of very early PB, the greater expression of vimentin in the distal villi (0.324±0.001 units in the I group and 0.356±0.007 units in the II group) than in the intermediate villi (0.234±0.004 units and 0.248±0.002 units, respectively) and basal ones (0.178±0.002 units and 0.189±0.006 units, respectively). This once again confirms that the inflammatory reaction and the associated EMT at birth before 28 weeks are mainly of fetal origin.In placentas from early PB, the pattern is the opposite – from 0.345±0.007 units and 0.369±0.009 units in III and IV groups, respectively, in basal villi to 0.257±0.004 units and 0.239±0.005 – in intermediate villi and 0.178±0.009 units and 0.165±0.005 units – in the distal ones.Conclusions. 1. The expression of the inflammatory proliferation marker Ki-67 was detected in two thirds of the studied placentas regardless of the term of delivery, but very early PBs are characterized by the predominant localization of the marker in the distal villi, while in early PBs – in the basal and proximal villi. 2. The expression of EMT markers indicates the fetal origin of the inflammatory response in very early PB – less cytokeratin in syncytial cells and more vimentin in distal chorionic villi. In placentas from early PB and term deliveries, a more pronounced expression of vimentin in the basal vessels of the chorion dominates.