Elevated frequency of IL‐37‐ and IL‐18R&agr;‐positive T cells in the peripheral blood of rheumatoid arthritis patients
HighlightsIL‐37 and IL‐18R&agr; positive T cells were significantly elevated in RA patients.IL‐37 and its receptors may play an immunoregulatory role in the CD4+T activation.IL‐37 plays an important role in the regulation of inflammation in RA.IL‐37 may be a therapeutic target for rheumatoid arthritis. Objective: To detect the expression of IL‐37 and its receptors IL‐18R&agr; and IL‐1R8 in CD4+ T cells and total lymphocytes in rheumatoid arthritis (RA) patients and the relationship between autoantibodies and disease activity. To investigate the mechanism of IL‐37 and its receptors involved in the pathogenesis of RA. To evaluate the effects of different concentrations of rhIL‐37 on peripheral blood mononuclear cells (PBMCs) in RA patients with TNF‐&agr;, and IL‐6. Methods: The expression of IL‐37 and its receptor IL‐18R&agr; and IL‐1R8 in peripheral blood CD4+ T cells and total lymphocytes in RA patients and healthy controls were measured by flow cytometry. The levels of TNF‐&agr; and IL‐6 in the supernatant were measured by ELISA after rhIL‐37 stimulation with PBMCs. Results: The expression of IL‐37 and IL‐18R&agr; in the total lymphocytes, especially in CD4+ T cells in RA patients, was significantly higher than in the healthy control group. There was a positive correlation between the frequency of IL‐37‐ or IL‐18R&agr;‐positive CD4+ T cells and ESR, CRP, and DAS28 values. Additionally, rhIL‐37 significantly down‐regulated TNF‐&agr; and IL‐6 production in RA patients’ PBMCs. Conclusions: IL‐37 plays an important role in the regulation of inflammation in RA. IL‐37 and its receptors may play an immunoregulatory role in the activation of lymphocytes, especially CD4+ T cells, in RA patients. IL‐37 may represent a therapeutic target for rheumatoid arthritis.