The Effect of Curcumin on T Helper 1/T Helper 17 Balance in Rat Collagen-Induced Arthritis Model

Immunomodulatory imbalance is the characteristic feature of autoimmune diseases like rheumatoid arthritis (RA). T helper (Th) 17 plays a critical role in the pathogenesis of RA. The balance of Th1 and Th17 is important for normal immune response. In RA therapy, methotrexate (MTX) has an important use depending on its anti-inflammatory effects, however, is limited due to its side effects. Curcumin is a natural plant product used as an immunomodulator. This study aimed to investigate the impact of curcumin and MTX administration singly or combined on a rat model with collagen-induced arthritis. The results revealed that the level of serum interleukin (IL)-17 showed a positive correlation with IL-23, interferon-gamma (IFN) and transforming growth factor-beta (TGF) and a negative correlation with IL-27 at the end of the experiment. Treatment with curcumin, MTX and their combinations also caused a significant (P<0.05) reduction in the pro-inflammatory cytokines (IL-17, IL-23, IFN, and TGF) and improvement of the histopathological appearance of the hind paw as compared to arthritic rats at the end. However, single treatment with curcumin added more amelioration by induction of chondrocytes in the histopathology of the hind paw. Thereby, the combined treatment of curcumin and MTX is associated with suppression of Th1/Th17 cytokines and showed a significant production of IL-27 as a protective cytokine.