Association Of The Expression Of SHLA-G In Placenta With Severe Preeclampsia In Third Trimester

Preeclampsia(PE) is a type of idiopathic Hypertensive disorder complicating pregnancy (HDCP) firstly after20weeks gestation, and is a major cause of maternal and fetal mortality and morbidity, especially in instances of severe PE. PE affects5%to7%of pregnant women worldwide,9.4%in China. Though there were many researches about PE around home and abroad, as precise etiopathogenesis of PE remains unknown. That inadequate tolerance of mother-fetal as an important pathogeny of PE is generally accepted and is the hot.Lots of researchers considered fetal who carried father’s gene as an allogeneic transplant for mother. In normal pregnancy, a balanced immune system tolerance exists between the mother and fetus which allows them to immune maintaining stability with each other. Once the immune tolerance is broken, this may induce pathological alteration similarly to acute transplant rejection reaction.HLA antigens are major causes of allogeneic graft rejection reaction, HLA-G belongs to non-classical HLA class Ib molecule. HLA-G is specifically expressed in the extravillous cytotrophoblast and promotes cytotrophoblast to invade uterus, inhibits cytolytic function of NK cell from decidua, and maintains mother-fetal immune balance, many scholars have targeted this as part of their research. It has been demonstrated that HLA-G gene possesses limited polymorphism, as the polymorphism could affect HLA-G stability, and result in abnormal or decreased expression of HLA-G in placenta. That abnornal or decreased expression of HLA-G was associated with some main pregnancy related diseases, such as recurrent spontaneous abortion, preeclampsia and so on. The role of gene was expressed by its translation product—protein. The isofonns of soluble HLA-G (sHLA-Gl/G5) play an important role in maintaining mother-fetal immune balance. We deternined the levels of sHLA-Gl/G5mRNA and protein in placentas of severe PE and normal pregnancy women to discuss the association of the expression of sHLA-Gl/G5with severe PE.ObjectiveWe used Real-time PCR, immunocytochemistry and Western Blot to compare mRNA and protein expressions of sHLA-Gl/G5in placentas of severe PE and normal pregnancy women, who deliveried in the Third Affiliated Hospital of Zhengzhou University from October2008to February2011, so as to discuss the association of expression of sHLA-Gl/G5with severe PE.Materials and methods1MaterialsThe85placentas of severe PE and104placentas of normal pregnancy women were recruited from the Third Affiliated Hospital of Zhengzhou University between October2008and February2011. The diagnosis of severe PE based on the seventh edition of 《bstetrics and gynecology》 which was published by the People’s Medical Publishing House. All the subjects enrolled into this study were the Chinese Han population, delivered by caesarean section. Moreover, between the case and control group, there were no significant differences in age or gravidity.(P>0.05)2MethodsFive biopsies (2cm X2cm X0.5cm) avoided calcification and necrosis place of placentas obtained after delivery within15minutes, each of which was located3、6、9、12clock and the centre of the placenta. Tissue samples for HE stainning and immunohistochemistry were fixed in10%formalin. Tissue samples for RNA and protein extraction were stored at sterile freeze-stored tube and immediately snap frozen with liquid nitrogen and stored at-80℃until required. We used Real-time PCR, immunohistochemistry and Western blot to determined mRNA and protein expression of sHLA-G1/G5in placentas of severe PE and normal pregnancy women.3Statistics analysisStatistical analysis was performed by using SPSS17.0software. Normal distribution measuring data using the t-test, Non-normal distribution measuring data using Kruskal-Wallis Test. A2-tailed P<0.05was considered to be statistically significant.Results1Comparison of simple clinical informations of the two groupsThe average age of severe preeclampsia women was30.15±5.28, compared with29.64±6.17of control, no significant differences were observed in the two groups (P>0.05); but the average gestational age of severe preeclampsia women was34.27±3.32, which was strikingly lower than38.56±1.65of control(P<0.05).2The HLA-G1/G5mRNA expression in placentas of the two groups2.1The HLA-G1mRNA expression in placenta of the two groupsThe relative expression of HLA-G1mRNA in preeclamptic placentas was significantly lower than that of control (P<0.05).2.2The HLA-G5mRNA expression in placenta of the two groupsThe relative expression of HLA-G5mRNA in preeclamptic placentas was also significantly lower than that of control (P<0.05).3The sHLA-G protein expression in placentas of the two groupssHLA-G was expressed on trophoblast cells which including villous trophoblast cells and extravillous cytotrophoblast cells in placenta, specifically expressed on the extravillous cytotrophoblast which located in maternal-placental interface.The result of immunohistochemistry showed:sHLA-G expressed on cell membrane, cell plasma, and the expression of sHLA-G protein in severe PE was strikingly lower than control. The result of Western Blot was:the relative expression of sHLA-G protein in severe PE was0.360±0.023, which was strikingly lower than0.375±0.028of control(P<0.05).ConclusionsBoth of mRNA and protein expressions of soluble HLA-G (sHLA-G1/G5) in third trimester significantly lower than control that may be one of the pathogenesis of severe preeclampsia.