The Research Of Effect Of Activin A On Apoptosis In Human Cytotrophoblasts Of Early Pregnancy And The Relationship Between This Effect And Hypertensive Disorder Complicating Pregnancy

IntroductionHypertensive disorder complicating pregnancy remains a leading cause of maternal and prenatal morbidity and mortality, and etiological of the disorder is an important aspect of obstetrics study. It is accepted that superficial implantation of placenta and poorly transformed spiral arteries are central etiology and pathology of hypertensive disorder complicating pregnancy, which are related to depressed invasive ability of cytotrophoblasts. Appropriate invasive ability of cy-totrophoblasts is a key of foundation, maintaining and ending of pregnancy, pathological pregnancy will be induced by over - strong or over - weak invasive ability of cytotrophoblasts. Two aspects determine invasive ability of cells; one is MMPs secreted by cells, which can dissolve extracellular matrix ( ECM). Another is the number of invasive cells, which is affected by apoptosis. Over - ap-optosis of cytotrophoblasts may bring decreased of invasive cells and transformed cells of spiral arteries, which will lead to superficial implantation of placenta and poorly transformed spiral arteries, and induces hypertensive disorder complicating pregnancy.Activin A, a member of transforming growth factor - beta super - family (TGF - β super - family) , has various effects on diverse biological systems, specially effects of proliferation, differentiation, apoptosis and cancerogenesis on cells. Activin A can induce proliferating cells to apoptosis. cytotrophoblasts be-long to a stem cell population and proliferate, activin A receptors express in cytotrophoblasts , so we speculate that activin A may regulate proliferation and apoptosis of cytotrophoblasts. The function of activin A may affect normal and pathological pregnancy but there is no related report. From the information we guess that activin A works in hypertensive disorder complicating pregnancy by inducing cytotrophoblasts to apoptosis.ObjectiveIn order to validate our guess, we detected apoptosis and apoptosis related molecules in placenta of normal pregnancy and preeclampsia, expression of activin A, activin receptors and follistatin, and looked for relationship from over apoptosis and increased expression of activin A. In vitro to ulteriorly validate our guess we observed effects of activin A on cytotrophoblasts. The study in vivo and vitro will offer more information for discussing about relationship of activin A and hypertensive disorder complicating pregnancy.MethodsIn vivo apoptosis and apoptosis related molecules in placentas of normal pregnancy and preeclampsia at gestation weeks 25 to term were detected by TUNEL and RT - PCR. Expression of activin A , activin receptors and follistatin were detected by RT - PCR and immunohistochemistry. In vitro activin A stimulated serum - free cultured human cytotrophoblasts and detected apoptosis signal molecules and apoptosis related molecules by confocal, western blotting , TUNEL and so on.ResultsApoptosis was increased in placenta of preeclampsia comparing to normal, and gradually increased from the gestational week 25 to term in two types placenta. There was obvious apoptosis of cytotrophoblasts, synotrophoblasts and vascular endothelial cell in villi in preeclampsia while obvious apoptosis of synotropho-blasts in normal. A little of vascular endothelial cell in villi was positive TUNEL in normal term placenta. The expression at mRNA level of P53 and Bax was increased and Bel - 2 was decreased in preeclampsia. There is limited - apoptosis in amount and location in normal placenta but over - apoptosis in amount and location in preeclampsia placenta, also as apoptosis - related molecules. Preeclampsia is closely correlative to over - apoptosis in placenta.Expression at mRNA level of activin A and activin receptors in placenta of preeclampsia was increased. Expression of activin pA and activin receptor I B was distinctly increased, activin receptor I and E weakly increased. But expression of follistatin had no change. Exprerssion of activin A and receptors were higher in placenta of gestation week 26 than 32 and 38, Location of activin receptor I B was in cytotrophoblasts, extravillous cytotrophoblasts and vascular endothelial cell, which was the same to location of apoptosis, so activin A may be relative to apoptosis.Expression of Caspase - 3, 8, 9 and P53, Bax was increased after 50ng/ml activin A stimulating serum - free cultured cytotrophoblasts of early pregnancy in vitro. And TUNEL positive cell per field of vision also was elevated. So activin A could induce cytotrophoblasts to apoptosis, which might be mechanism of increased activin A in hypertensive disorder complicating pregnancy .ConclusionsThis study clarifies temporal and spatial location of apoptosis and expression of activin A and activin receptors in placenta of preeclampsia. Activin A may be a reason of over apoptosis in placenta of preeclampsia. The results of vitro study confirmed presumption, in other words, activin A can induce cytotrophoblasts to apoptosis, which may be a mechanism of hypertensive disorder complicating pregnancy and a new study project.