Interaction between Kynurenine and Aryl Hydrocarbon Receptor in Regulating the Balance of T helper 17 Cells and Regulatory T-cells in Decidua during Early Gestation

Objective:To investigate whether kynurenine/aryl hydrocarbon receptor(AHR)affects the maternal-fetal tolerance by involving the differentiation of T helper 17(Th17)/regulatory T(Treg)cells,and to provide theoretical basic for new treatment of unexplained abortion.Methods:Flow cytometry(FCM)was used to detect the expression of AHR in peripheral/decidual CD4+T,Treg,and Th17 cells.The effect of Kyn on the differentiation of peripheral/decidual naïve T-cells under Treg-/Th17-polarizing condition was detected by FCM;enzyme-linked immunosorbent assay was performed to examine the level of Kyn in villus and decidual tissues from normal pregnancy(NP)and unexplained abortion(UA).Student’s t-test in the case of two groups or one-way ANOVA in multiple groups was used.Results:AHR expression in CD4+T-cells was decreased in decidua versus blood in early pregnancy(P<0.0001).Kyn could promote the differentiation of peripheral and decidual naïve T-cells to Th17 cells under Treg-polarizing conditions(P<0.01).There was no statistical significance about the concentration of Kyn in decidual or villi tissues between NP and UA,and compared with NP,the expression of AHR in decidual CD4+T-cells from UA was increased(P<0.001).Conclusions:Kyn/AHR promotes Th17 and restricts Treg cells’differentiation,which is involved in maintaining the balance of Treg/Th17 cells at the maternal-fetal interface.