"immune .th17/treg Balancing Role In The Pathogenesis Of Idiopathic Membranous Nephropathy And Cyclosporin A Influence

Background and ObjectiveIdiopathic membranous nephropathy (IMN) is the leading cause of nephrotic syndrome in adults. However,the precise mechanisms involved in IMN have not been clear.Data from studies in human and Heymann nephritis indicated that, MN is a conceptually simple organ-specific autoimmune disease,which involve T and B lymphocytes dysfunction.CD4+T helper(Th) cells play important roles in regulation of autoimmunity in vivo. Traditionally, CD 4+Th cells had been divided into two types of subsets:type 1 and type2. Recently, regulatory T cells (Treg) cells and Thl7 cells have been described as two distinct subsets from Thl and Th2 cells.Treg and Th17 cells,both of which gerated from naive CD4+T cells, play opposite roles and restrain each other.The balance between Th17 and Treg may be important in the development/prevention of autoimmunity. It has been reported that Th17/Treg imbalance exists in inflammation, infection, tumour and autoimmue diseases.However, it is not clare wether it exisits in nephrotic syndrome,especial membranous nephropathy. In addition, cyclosporine A (CsA) is considered as an effective treatment with IMN.Several studies had been focused on the influence of immunosuppressive drugs on Th17/Treg balance in posttraplant patients, and the influence in IMN has not been investigated. So, the objective of this study was to evaluate whether the Th17/Treg balance was broken in IMN patients, and how CsA impacts the Thl7/Treg balance during treating IMN.MethodsFourty-nine patients, diagnosted IMN by renal biopsy and exluded potential secondary factors, were enrolled in this study.Twenty-eight age-and sex-matched healthy volunteers served as healthy controls(HC).The frequencies of peripheral Th cell subsets(Treg/Thl7/Thl/Th2),B cells and T cell subsets(CD3+,CD4+,CD8+)were evaluated in IMN patients and HC by flow cytometry.The expression of CD127,CD39 and CD73 were also evaluated by flow cytometry.The peripheral relative mRNA expression of key transcription factors for Treg and Th17, Foxp3 and RORyt,were determined by real-time RT-PCR assay. The concentrations of plasma cytokines were evaluated by ELISA. Proliferation assay were performed on isolated CD4+CD25+T cells and/or target lymphocytes.Correlations between CD4+Th subpopulations and plasma cytokines or clinical manifestations in IMN patients were analized.The infiltration of Treg cells and expression of IL-17 in renal tissue from HC and IMN patients were determined by immunohistochemical staining. Nineteen patients with IMN who received CsA plus corticosteroids treatment were evaluated the changes of peripheral Treg, Th17 and T, B subpopulations over six months. In addition, we observed the influence of diferent concentrations of CsA or/and Methylprednisolone (MP) on Treg and Thl7 cells in vitro.Results(1) Compared with healthy controls, the frequency of peripheral Treg cells and plasma TGF-β1 level decreased,while the frequencies of Th2,Th17, B lymphocytes and plasma IL-23, IL-17 levels increased significantly in IMN patients(p<0.05).The key transcription factors of Treg and Th17, Foxp3 and RORyt, had similar alterations in HC and IMN patients.(2) TGF-β1 concentrations were positively correlated with peripheral blood frequencies of Treg (r=0.311,p=0.029) and IL-23 concentrations were positively correlated with peripheral blood frequencies of Th17 (r=0.347,P=0.014) in IMN patients.(3) Alterations of Treg cell surface markers in IMN patients:the frequency of CD39 markly decreased, while the expression of CD25 and CD127 had no difference with controls.(4) The peripheral CD4+CD25+Treg cells from IMN patients exhibited a decreased inhibition of CD4+CD25-effect T cells proliferation and B cells secretion of IgG.(5) The Th17/Treg ratios increased along with increased proteinuria(r=0.294,P=0.036) and decreased albumin levels (r=-0.323,p=0.024) in patients with IMN.(6) Patients were divided into two groups based on the response to therapy after 6 months. Data showed that patients who have no response to treatment had a higher proteinuria level, CD4/CD8 ratio and Th17/Treg ratio than those who had good response to treatment.(7) IL-17 protein expression in the renal tissue of IMN patients increased significantly compared with that in control subjects (p<0.05). Infiltration of Treg cells was also detected in the renal tissue of IMN patients, while rare Treg cells had been seen in normal renal tissue. Treg cells allways located in renal interstitium along with other type of lymphocytes in IMN potients. The infiltration of Treg cells in renal interstitium also related to a higher clinical remmision in IMN patients.(8) IMN patients receiving CsA plus corticosteroids therapy showed a significant decrease of Th17/Treg ratio, peripheral frequencies of B cells and Th2 cells, as well as obvious increase of plasma TGF-β1 level along with the decrease of proteinuria level.(9) CsA inhibited the differentiation of Treg cells induced by TGF-β, as well as the IL-17 expressing T cells in vitro. In addition, MP could enhance the inhibition of Thl7 cells, and alleviate the inhibition of Treg cell differentiation by CsA.ConclusionsTh17/Treg imbalance, charactered by enhanced peripheral and local Th17 function and weakened Treg function, existed in IMN patients. Altered function of Treg cells may contributed to activating of B cells by Th2 cytokines. The clinical meaning of infiltration of Treg cells in renal tissue deserved further studies in IMN patients. With the decrease of proteinuria, the peripheral Th17/Treg imbalance recovered after effective CsA plus corticosteroids therapy in IMN patients. MP plus CsA had more benefit to maintain Th17/Treg balance in vitro experiment of which the exact mechanisms need further explorations.