Tibetan medicine Kuan-Jin-Teng exerts anti-arthritic effects on collagen-induced arthritis rats via inhibition the production of pro-inflammatory cytokines and down-regulation of MAPK signaling pathway

Abstract

Background: The stems of Tinospora sinensis (Lour.) Merr commonly named "Kuan-Jin-Teng" in Chinese, have been used to treat rheumatoid arthritis as a Tibetan medicine.

Purpose: The effects of the EtOAc fraction of ethanolic extract from the stems of T. sinensis (KJT) on the pro-inflammatory cytokines and MAPK pathway were studied in collagen-induced arthritis (CIA) model.

Study design: Anti-arthritic activity of KJT was investigated in CIA model.

Methods: The chemical constituents of KJT were analyzed by LC-MS and HPLC. The CIA model was established with injecting the bovine CII emulsified in Freund's adjuvant in Wistar rats. Several doses of KJT (50.0, 100.0 and 200.0 mg/kg) were administrated via oral gavage to CIA rats daily for 4 weeks. The anti-arthritic activity of KJT was investigated by clinical arthritis scoring, paw swelling inspection and hyperalgesia measurement, as well as radiological and histological analysis in CIA rats. The impacts of KJT on the activation of MAPK pathway, production of pro-inflammatory cytokines (TNF-α, IL-1β and IL-17) in ankle joints, serum, and spleen in CIA rats were examined by western blot, immunohistochemical staining, ELISA, and quantitative real-time PCR respectively. Lastly, the effects of KJT on production of the nitric oxide (NO) and pro-inflammatory cytokines as well as the regulation of the phosphorylation of p38 and Erk were detected in lipopolysaccharide (LPS)-stimulated RAW264.7 murine macrophage cells.

Results: KJT significantly alleviated the paw swelling, hyperalgesia and arthritic severity, and reduced the synovial tissue proliferation and inflammatory cell infiltration in the CIA rats. Moreover, KJT suppressed the production of TNF-α, IL-1β, and IL-17 in ankle joints, serum, and spleen and reversed the up-regulation of the phosphorylation of p38 and Erk in CIA rats. KJT was also demonstrated to inhibit the production of NO and pro-inflammatory cytokines (TNF-α, IL-1β and IL-6), and phosphorylation of p38 and Erk in LPS-stimulated RAW264.7 cells.

Conclusion: These results suggest the mechanisms of KJT performing its anti-arthritis effect may be attributed to inhibiting the production of pro-inflammatory cytokines and down-regulating the MAPK signaling pathway.

Keywords: Mitogen-activated protein kinases; Pro-inflammatory cytokines; Rheumatoid arthritis; Tinospora sinensis (Lour.) Merr.