Investigation Of The Relationship Between The Expression Ratio Of LILRB1 In Peripheral Blood And Decidual NK Cells In Early Pregnancy And Recurrent Spontaneous Abortion

Objective: Recurrent abortion(RSA)is a common complication of female pregnancy.After systematic etiology screening,the etiology of more than half of RSA patients is still unknown.It is currently believed that the pathogenesis may be related to maternal immune factors.Natural killer(NK)cells are mainly found in peripheral blood,but the proportion of decidual immune cells in the first three months of pregnancy reaches 70%.Peripheral blood NK(p NK)cells are different from decidual NK(d NK)cells in terms of cell phenotype and cell function.PNK cells mainly have high cytotoxicity and d NK cells have high secretory activity.Changes in the number of NK cells and abnormal functions in early pregnancy may cause adverse pregnancy outcomes such as spontaneous abortion.Leukocyte immunoglobulin-like receptor B1(LILRB1)is an immunosuppressive receptor that is expressed on the surface of a variety of immune cells.The expression of LILRB1 can inhibit the cell killing effect of NK cells,maintain the escape of embryos from maternal immune attack,and increase the secretion of growth factors and promote the remodeling of placental blood vessels,which is beneficial to the maintenance of pregnancy.Therefore,we believe that there may be abnormal changes in the expression ratio of LILRB1 in NK cells of RSA patients.This study intends to detect the expression ratio of LILRB1 in peripheral blood and decidual tissue NK cells in early pregnancy RSA patients and healthy pregnant women by flow cytometry and explore its clinical significance.Methods: 1.Relationship between the proportion of LILRB1+p NK cells in peripheral blood NK(p NK)cells in early pregnancy and recurrent abortion: Sixty early pregnant patients with recurrent spontaneous abortion in our hospital from January 2019 to September 2019 were selected as RSA-A group.Forty healthy early pregnant women as N-A group.All subjects collected 1m L peripheral blood on an empty stomach in the early morning.Flow cytometry to detect the expression of LILRB1 in peripheral blood NK cells.2.Relationship between the proportion of LILRB1+d NK cells in decidual NK cells(d NK)cells in early pregnancy and recurrent abortion: Eight early pregnant patients with RSA undergoing induced abortion due to spontaneous abortion in our hospital from October2019 to December 2019 were selected as RSA-B group.Twenty healthy early pregnant women undergoing induced abortion voluntary as N-B group.Collect peripheral blood and discarded decidual tissue after abortion,get decidual lymphocytes by density gradient centrifugation and flow cytometry to detect the expression of LILRB1 in decidual NK cells.Analysis by Flowjo 10.5 and statistical analysis of flow cytometry results.P <0.05 indicates that the difference is statistically significant.Results: 1.The expression of LILRB1 in pNK of RSA-A group was lower than that of NA group.(P<0.05).2.The expression of LILRB1 in d NK of RSA-B group was lower than that of N-B group.(P<0.05).3.The pregnancy outcomes of patients in the RSA-A group were followed up.The patients with spontaneous abortion in this pregnancy(11 cases)had a lower ratio of LILRB1+p NK than those in the second trimester(49 cases)(30.73 ± 14.90 vs 47.54 ± 23.46,P> 0.05),significantly lower than the N-A group(P <0.05).Correlation analysis showed that the ratio of LILRB1+p NK in peripheral blood of RSA patients was positively correlated with pregnancy outcome(P = 0.035,correlation coefficient 0.272).4.Comparison of peripheral blood and decidual specimens from early RSA patients(6 cases)and healthy pregnant women(6 cases)from early pregnancy.The proportions were lower than those of healthy pregnant women(P <0.05),and the ratio of peripheral blood LILRB1+p NK was positively correlated with the ratio of decidual LILRB1+d NK(P = 0.016,correlation coefficient 0.676).5.The ratio of decidual LILRB1+d NK cells is positively related to parity and negatively related to the number of spontaneous abortions(P = 0.007,P = 0.000,the correlation coefficients are 0.504 and-0.642);the ratio of peripheral blood LILRB1+p NK cells to pregnancy,parity,and spontaneous abortion were unrelated.Conclusion: 1.Low expression level of peripheral blood and decidual LILRB1+NK cells in early pregnancy may be involved in the pathogenesis of recurrent spontaneous abortion.2.Low peripheral blood LILRB1+p NK cell ratio in early pregnancy may lead to adverse pregnancy outcomes.