| Objective: Severe preeclampsia(SPE)is a specific disease of pregnancy,which is the main reason for the increasing of maternal and perinatal mortality.However,the underline pathogenesis is still unclear.MiRNA is an endogenous Encoding small RNA,which exists in almost all cells,mainly affects the development,differentiation and transcriptional regulation of cells.Differential expressions of miRNA during the occurrence and development of preeclampsia were observed in recent studies,and let-7 is one of them.Recent researches suggest that let-7 is significantly down-regulated in the placental tissue of SPE pregnant women and involved in the pathogenesis of SPE.let-7b is the key members of the let-7 family,so we hyperthesize that let-7b may be involved in onset of severe preeclampsia;Tumor necrosis factor α(TNF-α)is an important inflammatory factor,which is closely related to the damage of vascular endothelial cells and cell apoptosis,and one of the basic pathological changes in preeclampsia is vascular endothelial cells are damaged.The recent studies in serum and cell lines of patients with endometriosis show that let-7b can regulate the expression of TNF-α,thus promoting the inflammatory responses of cell,leading to increasing apoptosis and Endothelial injury,however,let-7b expression in severe preeclampsia and regulation of TNF-α are rarely investigated.Our study intends to evaluate the expression of let-7b and TNF-α in SPE placenta tissue and correlation,further providing a new theoretical basis for the pathogenesis of severe preeclampsia.Methods: The placental tissues of 30 patients with severe preeclampsia who underwent regular cesarean delivery in our hospital from August 2017 to October 2018 were selected as the experimental group(SPE group).Placental tissues of 20 normal pregnant women during the same period of cesarean section was taken as the normal group(NC group).Total RNA was extracted by Trizol method,and the expression levels of mi RNA let-7b and mRNA TNF-α were detected by qRT-PCR.Western-blotting(WB)was used to detect the expression of TNF-α protein in the two groups.Statistical analysis was used to examine the correlation between let-7b and TNF-α and their respective clinical characteristics.Results: 1.The expression level of let-7b in the placenta tissue of the normal group was 0.23 ± 0.03,the SPE group was 0.07 ± 0.01,and the SPE group was significantly lower than the normal group(P < 0.05);2.The expression level of TNF-α mRNA in the placenta tissues of NC group was 0.19 ± 0.02,and the SPE group was 0.47 ± 0.05.the SPE group was significantly higher than the normal group(P < 0.05);3.The expression results of TNF-α protein showed that the expression level of TNF-α protein in SPE group was higher than that in normal group,and it was statistically significant(P < 0.05);4.The correlation analysis between let-7b and TNF-α in maternal placenta of SPE group and clinical characteristics were performed using Pearson test.The results showed that let-7b was significantly negatively correlated with TNF-α(r =-0.41,P < 0.05),TNF-α was significantly positively correlated with systolic and diastolic blood pressure(r = 0.92,P < 0.05;r = 0.90,P < 0.05).Conclusions: let-7b may be involved in the occurrence and development of severe preeclampsia by negatively regulating the expression of TNF-α. |
