A combination of sinomenine and methotrexate reduces joint damage of collagen induced arthritis in rats by modulating osteoclast-related cytokines

Abstract

Objective: To analyze the combination therapy of Sinomenine (SIN) and Methotrexate (MTX) in rheumatoid arthritis (RA), we herein demonstrated the combination effect of SIN and MTX on collagen-induced arthritis (CIA) in rats through their modulation on osteoclast-related cytokines.

Methods: CIA was induced by the immunization of type II collagen (CII) in SD rats. SIN and MTX were administrated alone or in combination after the onset of arthritis. Arthritis index and histological analysis were used to evaluate the effect of treatments. Effects of SIN and MTX on expression of receptor activator of NF-κB ligand (RANKL) and osteopontin (OPN) in synovial tissues were assayed by immunohistochemistry. RANKL, osteoprotegerin (OPG), IL-6, IL-17 and matrix metalloproteinases (MMPs) in rat serum were measured by ELISA. The expression of osteoclast-related cytokines in fibroblast-like synoviocytes (FLS) from RA patients was assayed by RT-PCR.

Results: SIN and MTX combination additively reduced the inflammatory symptoms and joint damage in CIA. Combination of SIN and MTX significantly repressed synovial RANKL and OPN production. SIN and MTX exhibited complementary and synergistic effect upon down-regulating RANKL, IL-6, IL-17 and MMPs in rat serum. SIN and MTX also modulated the expression of RANKL and OPG in RA-FLS.

Conclusion: SIN and MTX have additive effects, decreasing inflammation and joint damage in CIA rats by modulating osteoclast-related cytokines. These results are indicative of the combined effect of SIN and MTX for anti-arthritic treatment in RA.

Keywords: Collagen induced arthritis; Fibroblast-like synoviocytes; Methotrexate; Osteoclasts; Sinomenine.