Study On The Mechanism Of Human Leukocyte Antigen G In Preeclampsia

Background:Preeclampsia(PE)is a hypertensive disorder occurring especially after 20 weeks of gestation,affecting 2-8% of pregnancies worldwide and posing a serious risk to maternal and newborn health.Currently,defective trophoblast differentiation and poor uterine spiral artery remodeling caused by extravillous trophoblast(EVT)invasion are thought to be primary events of PE,but the mechanisms behind EVT invasion remain unclear.Human leucocyte antigen-G(HLA-G)is a class I HLA molecule expressed by EVT.HLA-G mediates immunosuppression by interacting with its immunosuppressive receptors.Known immunosuppressive receptors of HLA-G include leukocyte immunoglobulin-like subfamily B member 1(LILRB1)and leukocyte immunoglobulin-like receptor B2.These receptors are expressed by immune cells at the maternal-fetal interface,among which the decidual natural killer cells(d NK)are the most abundant lymphocyte population at the interface.d NK cells have been implicated in a variety of pregnancy disorders,including recurrent abortion and PE.Therefore,we speculated that HLA-G might affect EVT invasion through the LILRB1 pathway of d NK cells.Objective:To analyze the expression of HLA-G in PE maternal-fetal interface decidua.To investigate the effect of HLA-G and its inhibitory receptor LILRB1 on EVT invasion through d NK cells,as well as the possible molecular mechanism,in order to clarify the role and mechanism of HLA-G in the pathogenesis of PE.Methods:1.PE and normal decidua tissues were collected from 20 patients in late pregnancy,and the difference of HLA-G expression between PE and normal decidua tissues was detected by immunohistochemistry.2.d NK cells were isolated from 11 decidua tissues in early pregnancy by flow cytometry.Transwell system was used to co-culture the sorted d NK cells with HTR-8/Svneo cells for 24 h.They were grouped according to the intervention method and culture method:(1)anti-LILRB1 group: anti-LILRB1 antibody and anti-HLA-G antibody were added simultaneously;(2)anti-HLA-G group: only anti-HLA-G antibody was added;(3)HLA-G group: no antibody intervention;(4)d NK group: d NK cells were cultured alone as a control group.3.Enzyme-linked immunosorbent assay was used to detect the difference of cytokine expression in the supernatant of d NK cells cultured in each group.4.The expression of LILRB1 in d NK cells of different groups was detected by western blot.5.Transwell method was used to detect the invasion ability of HTR-8/Svneo cells in each group after 24 h co-culture with d NK cells.Results:1.The expression level of HLA-G in PE decidua was significantly lower than that in normal pregnancy decidua(P<0.0001).2.When LILRB1 was blocked by antibody,the expression of Ang-2,GM-CSF,IFN-γ,IL-8,IP-10 and VEGF-C in d NK cells were significantly decreased.When HLA-G was blocked by antibody,the expression of Ang-2,GM-CSF,IL-8,IP-10 and VEGF-C were significantly decreased,while the expression level of IFN-γ was significantly increased(P<0.05).3.The expression level of LILRB1 in the anti-HLA-G group was significantly lower than that in the HLA-G group and d NK group(P<0.05).4.The invasion ability of HTR-8/Svneo cells in anti-LILRB1 group was significantly weaker than in the anti-HLA-G and HLA-G groups.The invasion ability of HTR-8/Svneo cells in HLA-G group was significantly stronger than that in anti-LILRB1 group and antiHLA-G group.The invasion of HTR-8/Svneo cells in the anti-HLA-G group was stronger than that in the anti-LILRB1 group and weaker than that in the HLA-G group(P<0.0001).Conclusion:The expression of HLA-G was lower in decidua of PE patients than normal pregnancy.HLA-G can bind to the inhibitory receptor LILRB1 on d NK cells and up-regulate the expression of LILRB1 in d NK cells.HLA-G /LILRB1 pathway can regulate the level of related cytokines expressed by d NK cells to affect EVT invasion.Low HLA-G expression may lead to reduced EVT invasion ability,which may be an important mechanism of PE.