The Expression And Clinical Significance Of Regulatory B Cells In Peripheral Blood Of Patients With Systemic Lupus Erythematosus

BackgroundSystemic lupus erythmatosus?SLE?is a chronic autoimmune disease whose etiology is not clear.SLE is characterized by deposition of immune complexes,overproduction of autoantibodies and hyperactivity of both T and B lymphocytes.In recent years,a group of special B cell subpopulations,called regulatory B cells?Bregs?,was found to negatively regulate immune responses.Bregs can inhibit the proliferation and differentiation of immune cells such as T cells,dendritic cells?DCs?,monocytes and macrophages by secreting interleukin 10?IL-10?,IL-35 and transforming growth factor??TGF-??.The abnormal expression levels and defective regulatory functions of Bregs have been confirmed in a variety of immune-related diseases including infections,tumors,and collagen-induced arthritis?CIA?.Although some animal models have demonstrated the role of Bregs in SLE,there is still little research on humans at home and abroad.Moreover,results of these studies are inconsistent.Therefore,in order to further study the mechanism of Bregs and discover new therapies for SLE,it is significant to analyze whether the expression levels of Bregs in SLE patients are abnormal and to explore the possible factors.ObjectivesThis study was performed to compare the differences between Bregs expression levels in peripheral blood from SLE patients and healthy controls,and to verify the validity of the phenotype CD19⁺CD24^hiCD38^hi.Then,the possible influence of clinical indicators on Bregs levels and the diagnostic value of Bregs in SLE would be also investigated.MethodsA total of 38 female SLE patients and 38 healthy females were included in this study.Face-to-face questionnaires were used to obtain general information of all subjects and clinical data of SLE patients.Collect 5ml of peripheral venous blood;extract peripheral blood mononuclear cells?PBMCs?;use CD19-APC,CD24-PE and CD38-FITC for fluorescent staining;and then detect the expression levels of CD19⁺CD24^hiCD38^hi B cells?Bregs?by flow cytometry.The significance for the differences of Bregs expression levels between SLE patients and healthy controls was determined by the Mann-Whitney U test.Kruskal-Wallis H test was used to compare the differences of Bregs expression levels among active SLE patients,inactive SLE patients and healthy controls.Further pairwise comparisons were conducted by Dunnett's T3 method.Spearman's rank correlation analysis was applied to detect correlations between Bregs expression levels and survey data.The diagnostic value of Bregs for SLE was evaluated by calculating area under the curve?AUC?value,sensitivity and specificity.The P value less than 0.05 was indicative of statistically significance.Results?1?The expression levels and absolute numbers of Bregs in peripheral blood from SLE patients were both significantly higher than those in healthy controls?Z=-3.543,P<0.001;Z=-2.873,P=0.004?.The expression levels of CD19⁺CD24^hiCD38^lo B cells were significantly lower than those in healthy controls?Z=-2.140,P=0.032?.The expression levels of CD19⁺CD24^loCD38^hi B cells were significantly higher than those in healthy controls?Z=-5.033,P<0.001?.?2?The expression levels of Bregs in peripheral blood from active and inactive SLE patients were both significantly higher than those in healthy controls?P<0.05?.?3?There were no significant correlations between Bregs levels in peripheral blood from SLE patients and SLEDAI?r_s=0.099,P=0.561?,C3?r_s=0.163,P=0.372?,ESR?r_s=0.094,P=0.597?,CRP?r_s=-0.204,P=0.272?,Ig A?r_s=-0.108,P=0.633?and Ig M?r_s=-0.098,P=0.641?,respectively.However,it was significantly positively correlated with Ig G?r_s=0.468,P=0.021?.?4?The clinical applications of glucocorticoids and hydroxychloroquine had no significant effects on Bregs expression levels in peripheral blood from SLE patients,while there were significant statistical differences between Bregs levels of SLE patients with and without cyclophosphamide?Z=-2.223,P=0.026?.?5?ROC analysis showed that the AUC of Bregs levels to distinguish SLE patients from healthy controls was 0.736?95%CI?0.616,0.857?,P<0.001?.ConclusionsThe expression levels of Bregs in peripheral blood from SLE patients were significantly higher than those in healthy controls.The expression levels of CD19⁺CD24^loCD38^hiB cells significantly increased,suggesting that CD24 and CD38are both effective markers for Bregs.The expression levels of Bregs in peripheral blood from active and inactive SLE patients were both significantly higher than those in healthy controls;Bregs levels were significantly positively correlated with Ig G;and cyclophosphamide?immunosuppressant?had an effect on Bregs levels,so we speculated that Bregs might be involved in the pathogenesis of SLE.It was also found that Bregs levels could distinguish SLE patients from healthy controls,which is of great significance for the diagnosis of SLE.Furthermore,it would provide a theoretical basis for further researches on the action mechanism of Bregs and new therapies for SLE.