Rheumatoid arthritis (RA) is a systemic autoimmune disease, which mainly involves joints across the body, resulting in joint stiffness and loss of daily activity. Recent evidence suggests that numerous self-reacting T cells, including Th1 and Th17, infiltrate the synovium in RA patients, accompanied by functionally-compromised Treg. Iguratimod, a new small molecule with anti-inflammatory and immunomodulatory effects, has shown curative effects in animal models of arthritis. In this study, we aimed to test the clinical effects of Iguratimod's on RA patients and its role in immunoregulation.

We examined the clinical effects of iguratimod on RA patients in a random controlled clinical trials and analyzed its effects on Thl, Th17 and Treg as well as their associated cytokines and transcription factors by flow cytometry and real-time polymerase chain reaction (PCR). Then t-test, chi-square test and rank sum test were used to conduct statistical analysis.

Our results revealed that iguratimod therapy provided significantly greater clinical benefit [ACR20, ACR50, ACR70 reached 50%, 20%, 15% respectively in iguratimod treatment group, Z=-2.216,P=0.027] than placebo group with the reduction of Th1 and Th17 but increment of Treg after iguratimod treatment [Th1: week 0 (26.5±8.0)%, week 24 (14.2±7.3)%, P<0.01; Th17: week 0 (1.7±0.7)%, week 24 (1.3±0.4)%, P<0.05; Treg: week 0 (6.8±1.6)%, week 24 (8.9±2.9)%, P<0.05], which was statistically significant.

Our results provide theoretical and clinical based evidence for the impact of iguratimod on immunomodulation of RA.

Arthritis, rheumatoid; Iguratimod; Treatment outcome; Immunoregulation; T-lympho-cytes, helper-inducer