To confirm the anti-arthritic effect and explore the potential mechanism of the dried heartwood of Caesalpinia sappan L. (HCS) on collagen-induced arthritis (CIA) in rats, an animal model of rheumatoid arthritis.
CIA was induced in male Wistar rats by intradermal injection of bovine collagen-II in Freund's incomplete adjuvant (IFA). The rats in the onset of arthritis were treated daily with oral administration of an ethanol extract from HCS (EHCS) at different doses (1.2, 2.4 and 3.6g/kg) or olive oil-vehicle for 10 days. Paw swelling, arthritis index, radiographic and histopathologic changes were evaluated to confirm the anti-arthritic effect of EHCS on CIA in rats. Levels of proinflammatory cytokines interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-α) as well as prostaglandin E2 (PGE2) in blood and expression of cyclooxygenase-2 (COX-2) and transcription factor NF-κB p65 in paw cartilage were detected to further study the molecular mechanism of the anti-arthritic effects of EHCS on CIA in rats. In addition, the adverse effects of EHCS on liver and kidney of rats were also evaluated.
The results showed that the EHCS markedly attenuated collagen-induced arthritis and reduced the levels of IL-1β, IL-6, TNF-α and PGE2 in serum and the expression of COX-2 and transcription factor NF-κB p65 in paw cartilage of CIA rats. EHCS (3.6g/kg) induced slight hepatotoxicity and body weight loss.
These results indicate that EHCS significantly attenuates CIA in rats by decreasing the levels of IL-1β, IL-6, TNF-α and PGE2 in serum and the expression of COX-2 and transcription factor NF-κB in paw cartilage.