The Clinical Value Of Different Subsets Of Regulatory B Cells In The Homeostasis Of Renal Transplantation

ObjectiveTo explore the relationship between different subpopulations of regulatory B cells(Breg)and immune homeostasis of renal transplant recipients,and to further detect the change and immune monitoring effect of different subpopulations of Breg in immune homeostasis of renal transplant recipients.Methods1.With healthy donors(HD)as control,a nested case-control study was conducted by testing the kidney puncture biopsy and peripheral blood of 25 patients with stable renal function(ST)and 18 patients with antibody mediated rejection(AMR)after kidney transplantation in the First Affiliated Hospital of Zhengzhou University.The study analysed the role of four subpopulations of Breg,including memory Breg(mBreg),transitional Breg(tBreg),IL-10 producing mBreg(IL-10+mBreg)and IL-10+tBreg,in maintaining immune homeostasis.2.We collected the peripheral blood and partly dissociated cells of kidney biopsy tissue from the HD group before transplantation,from the ST group at 90 days postoperation,from the AMR group before anti-rejection treatment.The four subpopulations of Breg were detected by flow cytometry.The correlation between the four subpopulations of Breg and immune homeostasis was analyzed.3.The peripheral blood from the HD group was collected at preoperation,1 day,7 day and 14 day postoperation.The peripheral blood from the ST group was collected at preoperation,1 day,7 day,14 day,30 day and 90 day postoperation.The dynamic changes of four subpopulations of Breg were analyzed by flow cytometry.Results1.The positive rate of C4d biopsy,donor specific antibody(DSA)level(especially anti-class II DSA),and the scores of tubulitis,interstitial inflammation,peritubular capillary inflammation and microvascular inflammation were higher in the AMR group than those in the ST group(all P<0.05).2.The results of flow cytometry of PBMCs from the healthy group before surgery,from the ST group at 90 days postoperation,and from the AMR group before anti-rejection therapy showed that the percentages of B cells in PBMCs,mBreg in B cells and tBreg in B cells had no significant differences(all P>0.05).However,IL-10+mBreg and IL-10+tBreg ratios in B cells in the ST group and the HD group were obviously higher than those in the AMR group(all P<0.05).3.The percentages of circulating Breg in B cells from the ST group at 90 days postoperation and from the AMR group before anti-rejection therapy were analyzed by ROC method.We found that,compared with mBreg and tBreg ratios,IL-10+mBreg and IL-10+tBreg ratios in B cells had a better ability to distinguish between stable function and antibody-mediated rejection of transplanted kidney.4.The results of flow cytometry showed that the proportions of IL-10+mBreg and IL-10+tBreg in leukocytes in the AMR group were significantly higher than those in the ST group and the HD group(all P<0.05).5.The PBMCs in the ST group at preoperation,1,7,14,30 and 90 days postoperation and those in the HD group at preoperation,1,7 and 14 days postoperation were analyzed by flow cytometry.On the one hand,there were no significant differences of the percentages of mBreg and tBreg in B cells between the HD group and the ST group at preoperation,1,7,and 14 days postoperation(all P>0.05).However,the percentages of IL-10+mBreg and IL-10+tBreg in B cells in the HD group were obviously lower than those in the ST group at 1,7 and 14 days postoperation(all P<0.05).On the other hand,compared with preoperation,the percentages of mBreg and tBreg in B cells in the ST group were higher at 7,14,30 and 90 days postoperation(all P<0.05),but the percentages of IL-10+mBreg and IL-10+tBreg in B cells in the ST group were significantly higher at 1,7,14,30 and 90 days postoperation(all P<0.05).Conclusion1.The degree of transplanted kidney damage in the AMR group was higher than that in the ST group,which may be related to the high C4d-positive and the level of anti-class II DSA.2.The decreases of circulating IL-10+mBreg and IL-10+tBreg were closely related to the occurrence of AMR in kidney transplantation.The stable state of kidney transplantation was positively related to the increases of circulating IL-10+mBreg and IL-10+ tBreg.3.The detection of the proportions of circulating IL-10+mBreg and IL-10+tBreg in B cells is helpful to distinguish the stable and AMR patients,which has a good diagnostic and differential value.4.The proportions of IL-10+ mBreg and IL-10+ tBreg in leukocytes in transplanted kidney were less in the ST group than those in the AMR group,which further indicated that the detection of circulating IL-10+mBreg and IL-10+tBreg was more suitable for evaluating the stability of transplanted kidney than that of kidney IL-10+mBreg and IL-10+tBreg.5.The proportions of circulating IL-10+mBreg and IL-10+tBreg in B cells in the ST group remained higher than at preoperation during the three months following transplantation,which further indicated that circulating IL-10+mBreg and IL-10+tBreg played an important role in the stability of transplanted kidney.The circulating IL-10+mBreg and IL-10+ tBreg were potential indicators to evaluate the stability of transplanted kidney.