Correlative Analysis Of Methylation Of CTGF Promoter In Pre-Eclampsia

Objective Preeclampsia(PE)is a serious obstetric complication during pregnancy,which can lead to irreversible damage of maternal system and fetal growth restriction(FGR).Its pathogenesis has been the focus of obstetric research.In recent years,the study of DNA methylation,which is a type of epigenetics,is in the ascendant in the pathogenesis of preeclampsia.Connective tissue growth factor(CTGF/CCN2),which belongs to the CNN family,is an important vascular regulatory growth factor.It has many biological functions such as promoting cell differentiation,adhesion,chemotaxis,migration,apoptosis and remodeling of extracellular matrix(ECM).It also participates in various pathophysiological processes.The objective of this study was to investigate the methylation level of CTGF promoter in peripheral blood during PE,and to detect the mRNA and protein expression levels of CTGF in placental tissues during PE so as to explore its role in the pathogenesis of PE.Methods Methylation-specific PCR was applied to detect the methylation rates of CTGF promoter in 90 cases of peripheral blood from pregnant women with PE(PE group)and 94 cases of peripheral blood from normal pregnant women(control group).The methylation rates of CTGF promoter in two groups were analyzed and compared.Meanwhile,placental samples were collected from 18 patients with PE and 18 normal pregnant women.The real-time fluorescent quantitative PCR(qRT-PCR)was conducted to detect the transcription level of of CTGF mRNA in placental tissues of the two groups;Western Blot was adopted to detect the expression level of CTGF protein in placental tissues of the two groups;Immunohistochemistry was applied to detect the location and expression of CTGF protein in placental tissues of the two groups.Results According to the statistical analysis,the methylation rate of CTGF promoter in PE group was 32.2%,which was lower than that in control group(46.8%).There was significant difference between PE group and CTL group(P<0.05).Meanwhile,the results of qRT-PCR showed that the level of CTGF mRNA of placenta in PE group(3.97±0.85)was significantly higher than that in control group(1.23±0.22,P<0.01).Western Blot showed that the level of CTGF protein of placenta in PE group(1.60±0.08)was higher than that in control group(1.37±0.31).Whereas,there was no significant difference between PE group and CTL group(P>0.05).Furthermore,immunohistochemical results showed that CTGF protein was expressed in placental tissues of both groups with no significant difference and was mainly located in villous trophoblast cells.Conclusion The methylation rate of CTGF promoter in pregnant women with PE is lower than normal pregnant women.The levels of CTGF mRNA in placenta from patients with PE was higher than that in control group.However,in terms of CTGF protein,there was no significant difference between the two groups.We speculate that the occurrence of PE may be related to the abnormal hypomethylation level of CTGF gene in the promoter region,suggesting that CTGF may be a potential pathogenic target of PE,but the specific mechanism of CTGF methylation needs further study.