The efficacy and mechanism for action of iguratimod in primary Sjögren’s syndrome patients

Purpose Primary Sjögren’s syndrome (pSS) has been proven as a systemic autoimmune disorder (such as Sjogren’s syndrome dry eye). This research aimed to evaluate potential treating effects of Iguratimod on pSS. Methods Fifty pSS patients were enrolled and randomly divided into Conventional group and Iguratimod group. Improvement in pSS was evaluated every 4 weeks. pSS disease activity was evaluated with European League Against Rheumatism (EULAR) Sjögren’s syndrome disease activity index (ESSDAI). Symptoms were evaluated by determining EULAR Sjögren’s syndrome patient-reported index (ESSPRI), platelet (PLT), IgG and Schirmer I test. Peripheral blood B cell molecules (CD135, IgD, CD38, CD20) and human B cell-activating factor-receptor (BAFF-R) were analyzed with flow cytometry. Results After treating for 12-weeks, pSS patients in Iguratimod and Conventional group showed a significant decrease in disease activity (ESSPRI, ESSDAI, PLT, IgG and Schirmer I test) comparing with baselines. Patients’ ESSPRI (2.92 ± 0.19) and disease activity of ESSDAI (4.32 ± 0.29), PLT (95.64 ± 1.86), IgG (13.0 ± 0.45) and Schirmer I test (4.67 ± 0.31) in Iguratimod group were significantly lower compared to Conventional group (4.64 ± 0.15, 5.8 ± 2.08, 77.44 ± 1.41, 16.5 ± 0.44 and 2.25 ± 0.11) ( p < 0.0001). Changes of ESSPRI, ESSDAI, PLT, IgG and Schirmer I test were remarkable observed between two groups ( p < 0.001). Iguratimod and Conventional treatment demonstrated a significant reduction in total B cells in pSS patients compared with pre-treatment. The pSS patients from Iguratimod and Conventional group showed a significant decreased BAFF-R (61.82 ± 1.52, 74.07 ± 1.11) and CD38 + IgD + (48.08 ± 0.92, 62.66 ± 1.12) on B cells after treatment compared with baseline (92.26 ± 0.32, 91.53 ± 0.45, 84.39 ± 0.59, 85.04 ± 0.46) ( p < 0.001). After treating 12 weeks, BAFF-R, CD38 + IgD + expression in Iguratimod group decreased significantly compared to Conventional group ( p < 0.001). Conclusions Iguratimod alleviated symptoms and mediated adaptive-immunity balance by suppressing BAFF-R positive B cell in pSS patients.