Characteristics Of Lymphocyte Subsets And Cytokines In Patients With IgG4-related Disease

Background:Immunoglobulin G4-related disease(IgG4-RD)is a chronic inflammatory and fibrotic disease characterized by multi-organomegaly,serum IgG4 elevation and IgG4-positive plasma cell infiltration.The pathogenesis is mediated by immunity,and both innate immunity and adaptive immunity are involved.Variety of T and B lymphocytes,especially CD4~+T lymphocyte subsets,play an important role in the pathogenesis of IgG4-RD.It has been confirmed that the immune disorder between T helper 17(Th17)and Regulatory T cells(Treg)and the change of cytokines microenvironment are the key links in the occurrence of autoimmune diseases.However,the status of Th17/Treg in IgG4-RD remains unknown.IgG4-related dacryoadenitis and sialoadenitis(IgG4-DS)as a known subclass of IgG4-RD,namely Mikulicz’s disease(MD),is similar to the clinical symptoms of primary Sjogren’s syndrome(pSS).This two concept is often confused previously,and the differences in the circulating immunological mechanism between the two disease still need to be further explored.In this study,We generalized clinical feature,laboratory data,imaging,pathology and therapeutic effect of IgG4-RD patients,especially the expression levels of CD4~+T cell subsets and the correlation between Th17/Treg ratio and disease activity.The circulating lymphocyte levels in patients with MD and pSS had meanwhile been compared.We aim to reveal the mechanism in occurrence and development of IgG4-RD disease,and provide a new direction and target for treatment.Objective:1.We investigated the levels of circulating lymphocytes,especially CD4~+T cell subsets and cytokines in IgG4-RD patients,and explored the correlation between Th17/Treg ratio and disease activity indicators;2.We clarified the difference in the expression of circulating immune cells between MD patients and PSS patients,so as to provide ideas for clinical differentiation.Methods:A total of untreated 41 IgG4-RD patients,including 32 MD patients who were admitted to the Rheumatic Immunology Department of the Second Hospital of Shanxi Medical University from March 2016 to December 2020 were enrolled.We collected their Clinical and laboratory data,and selected 30 age and sex matched healthy people and pSS patients as control group.Flow cytometry was used to detect the percentage and absolute number of lymphocyte subsets(T,B,NK)and CD4~+T subsets(Th1,Th2,Th17,CD25~+Foxp3~+Treg)in peripheral blood of IgG4-RD patients and control groups.Serum IL-2,IL-4,IL-6,IL-10,IL-17,TNF-αand IFN-γwere determined by flow liquid multiple protein quantification(CBA).Correlations between Th17/Treg ratio and disease-related inflammatory indicators were also analyzed.Results:1.The percent of CD4~+Th cells in peripheral blood of IgG4-RD patients was higher than that of healthy controls(P<0.05).The percent and absolute number of Th17 cells were also increased in IgG4-RD patients[1.13(0.7-1.56)vs.0.77(0.45-1.07),P<0.05;7.67(5.03-11.07)cells/μl vs.5.60(3.12-8.47)cells/μl,P<0.01],while the percent of Treg cells was decreased[3.60(3.02-5.51)vs.4.78(4.10-6.25),P<0.01].Th17/Treg ratio was significantly increased in IgG4-RD patients[0.32(0.16-0.46)vs.0.16(0.10-0.23),P<0.01].2.Th17/Treg ratio was positively correlated with IgG4-RD response index(r=0.410,P<0.01).3.Except serum IL-2,IL-4(P<0.05)、IL-6(P<0.001)、IL-10(P<0.001)、IL-17(P<0.05)、TNF-α(P<0.001)、IFN-γ(P<0.001)in IgG4-RD group were significantly higher than those in healthy control group.Moreover,Th17/Treg ratio was negatively correlated with IL-2(r=-0.463,P<0.05)and IL-10(r=-0.481,P<0.05)level.4.Compared with pSS patients,the percent of CD19~+B cells in peripheral blood of MD patients was decreased(P<0.01),while the percent and absolute number of CD4~+Th cells were increased(P<0.05).The percent and absolute number of Th2 cells were both increased[1.10(0.83-1.47)vs.0.77(0.54-1.11),P<0.05;9.05(5.92-14.02)cells/μl vs.5.62(2.80-9.03)cells/μl,P<0.01].There was no significant difference in cytokine levels between the two groups.Conclusion:There is Th17/Treg immune imbalance in IgG4-RD patients,which is related to disease activity.IL-2 and IL-10 play an important role in Th17/Treg immune imbalance.The significant increase of circulating Th2 cells in MD patients may be one of the immunological mechanisms that distinguish MD from PSS.