Combination of MTX and LEF attenuates inflammatory bone erosion by down-regulation of receptor activator of NF-kB ligand and interleukin-17 in type II collagen-induced arthritis rats

The objectives of this study were to determine the effect of combination of methotrexate (MTX) and leflunomide (LEF) on type II collagen–induced arthritis rats and its mechanism. Curative effect was confirmed on CIA rats, which were randomized and divided into model, MTX, LEF and MTX + LEF group. Weights and joint swelling scores of rats were recorded. Interleukin (IL)-17, receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) concentration in serum were determined by ELISA. H&E dyeing of joint was used to estimate the inflammation and osteoclasia extent. The mechanism was investigated through fibroblast-like synoviocytes isolated from RA patients. The effect of MTX and LEF on cell viability, and RANKL and OPG expression were indicated through MTT and RT-PCR analysis, respectively. Combination therapy would be effective in treating CIA rats. Joint swelling scores and IL-17 and RANKL level in serum were decreased obviously (P < 0.05), while OPG level was elevated (P < 0.05). Anti-inflammatory and anti-osteoclasia effect would be indicated by H&E dyeing results. Moreover, FLS cell viability was inhibited by combination treatment in vitro (P < 0.05), and expression of osteoclasia-related genes (RANKL and OPG) was modified (P < 0.05). Combination therapy would relive the synovium hypertrophy through depressing cell viability and osteoclasia through decreasing RANKL and increasing OPG expression. Otherwise, combination was superior to monotherapy.