Background Recently, there is emerging evidence that IL-22 and IL-22-producing Th cells are involved in the pathogenesis of autoimmune diseases. The roles of IL-22 and IL-22-producing Th cells in SLE remain unclear.
Objectives To investigate the correlations between IL-22 and IL-22-producing Th cells (Th1, Th17 and Th22) to further explore the roles of IL-22 and IL-22-producing Th cells in the pathogenesis of SLE.
Methods Plasma levels of IL-22 and IL-22 autoantibody were measured in 19 new-onset and 20 healthy controls by ELISA. Meanwhile, the percentages of CD4+IFN-γ+ (Th1), CD4+IL-17+ (Th17) and CD4+IFN-γ–IL-17– IL-22+ (Th22) cells in peripheral lymphocytes were determined by flow cytometry.
Results Plasma IL-22 levels in new-onset SLE patients (53.91±3.94 pg/ml) were significantly decreased compared to healthy controls (72.76±6.11 pg/ml, p<0.001). After treatment with prednisone and hydroxychloroquine, the levels of plasma IL-22 in new-onset SLE patients (63.21±6.25 pg/ml) were obviously increased but still lower than healthy controls (p<0.001). There was a positive correlation between plasma IL-22 levels and the percentages of Th22 cells (r=0.711, p=0.001). Moreover, plasma IL-22 levels correlated with SLEDAI scores and ESR. High frequencies of plasma IL-22 autoantibodies were detected in new-onset SLE patients. However, IL-22 levels didn't correlate with IL-22 autoantibody (r= -0.100, p=0.683).
Conclusions Decreased plasma IL-22 levels may be a distinct feature in new-onset SLE. Moreover, IL-22 correlates with Th22 cell and SLE disease activity.
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Acknowledgements This work was supported by grants from Medicine and Health Projects of Zhejiang Province (No.2013KYA058). We also would like to thank healthy volunteers and patients with SLE for providing blood samples.
Disclosure of Interest None declared