Endotoxin Regulates Invasion Of Cytotrophoblast And Its Relationship With Pre-eclampsia

Pre-eclampsia is the leading cause for mortality and morbidity of pregnancy and perinatal fetus. But the etiology and mechanism of pre-eclampsia is still uncertain. Therefore, the study on them is a focus in the field of perinatal medicine. Many advances have been taken up and many theories are developed. Hypoxia in placenta is one of the theories. The central point in it is that decreased invasion of cytotrophoblast results in abnormal development and placentation of placenta, and lead to failure of remodeling of the spiral artery and hypoxia in placenta. Hypoxia makes placenta tissue to release toxic substance, which can injury vascular endothelial cells and arise symptoms and signs of pre-eclampsia. Now it is suggested that decreased expression of matrix metalloproteinase and excessive apoptosis are leading cause for down-regulation of cytotrophoblast invasion.Matrix metalloproteinases are a family of Zn-dependent proteolytic enzymes, which hydrolyze almost all the extracellular matrix. Matrix metalloproteinases-2 and matrix metalloproteinases-9 are tightly connected with cytotrophoblast invasion. In the procession of invasion, cytotrophoblasts must break through the structure constituted of cells of the mother, its basement membrane and extracellular matrix. In thisstructure, there are plenty of type IV collagen, fibrinogen, laminin, vimentin,nidogen, gelatin and proteoglycans, which are substrates of matrix metalloproteinase-2 and matrix metalloproteinase-9.Recent studies indicated that endotoxin involves in pre-eclampsia. Endotoxin comes from the cell wall of gram-negative bacteria. When infection occurs, endotoxin enters human body. Now, urinogenital and oral infections are found to be predisposing factors of pre-eclampsia. In this infection, gram-negative bacteria are predominating. Moreover, Fass made a rat model of pre-eclampsia by injection endotoxin. According to the above discussion, we speculate that endotoxin has regulation effects on invasion of cytotrophoblast.ObjectiveThe aim of this study was to investigate effects of endotoxin on invasion of cytotrophoblast and its relationship with pre-eclampsia. In vitro experiments, we observed the effects of endotoxin on the expression of matrix metalloproteinase and apoptosis of cytotrophoblast. In clinical experiments, we revealed the relationship between the expression of matrix metalloproteinase in placenta and pre-eclampsia.MethodsThe expression of matrix metalloproteinase in cytotrophoblast treated with endotoxin was determined by RT-PCR and immune fluorescence-confocal microscope. Transwell was used to reveal the invasion of cytotrophoblast in vitro. In the observation of effects of endotoxin on apoptosis of cytotrophoblast, electron transmission microscope, Hoechst DNA staining and western blot were applied. Tissue immunochemistry was used to study the expression of matrix metalloproteinase in placenta in normal pregnancy and pre-eclampsia.ResultsThe result of RT-PCR and confocal microscope revealed that endotoxin inhibited expression of matrix metalloproteinase in cytotrophoblast. By using transwell, it was indicated that endotoxin inhibited invasion of cytotrophoblast. It was indicated that endotoxin induced apoptosis of cytotrophoblast in a dose-dependent manner by using morphological and immune methods. Immunochemistry study indicated that expression of matrix metalloproteinase in placenta was markly decreased in pre-eclampsia, in contrast to normal pregnancy.ConclusionsIn this study, endotoxin was found to down-regulate invasion of cytotrophoblast. It revealed the mechanism by which infection in pregnancy induced pre-eclampsia and the value of antibiotic in the prevention and treatment of pre-eclampsia.