Anti-rheumatoid arthritis effects of traditional Chinese herb couple in adjuvant-induced arthritis in rats

Clematis chinensis Osbeck / Notopterygium incisum Ting ex H, T-Chang (CN) is a traditional Chinese herb couple with prominent efficacy. The herb couple has been commonly used for clinical treatment of arthralgia syndrome (“Bi Zheng” in Chinese) for centuries in China, including rheumatic arthritis, osteoarthritis and gout in modern medicine. To evaluate the anti-arthritic effect of CN herb couple in a rat model of rheumatoid arthritis (RA). Rats were divided randomly into six groups with eight each. Adjuvant-induced arthritis (AIA) model was established by intradermal injection of complete Freund's adjuvant (CFA). Rats were treated orally with different dosages of CN (0.7 g/kg, 2.1 g/kg, 6.3 g/kg) from day 16 till day 40. Ibuprofen (50.4 mg/kg) served as a positive control. Spontaneous activity, body weight, paw swelling, and arthritis index (AI) were monitored throughout drug treatment. Then serum levels of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), and vascular endothelial growth factor (VEGF) were determined by enzyme linked immunosorbent assay (ELISA) kits. In addition, histopathological examination and immunohistochemistry were used to assess the severity of arthritis. Three dosage of CN significantly ameliorated symptoms of RA via increasing body weight as well as reducing paw swelling (at dose of 6.3 g/kg, p<0.01) in AIA rats. An extremely significant reduction of AI (p<0.001) was also observed with treatment of CN (6.3 g/kg) compared with model group. In parallel, treatment of CN significantly down-regulated levels of TNF-α, IL-6, and VEGF both in serum (p<0.01) and in joint synovial compared with model rats. And histopathology revealed noticeable reduction in synovial hyperplasia, cartilage damage, and inflammatory infiltration by CN treatment, especially at dose of 6.3 g/kg. To conclude, all results suggest that CN possesses evident anti-arthritic effects in AIA rats.