Anti-arthritic effect of total anthraquinone from Polygonum cuspidatum on type II collagen-induced arthritis in rats

Purpose: To study the anti-arthritic effect of total anthraquinone from Polygonum cuspidatum (TAPC) on type II collagen-induced arthritis (CIA) in rats, and to investigate the underlying mechanism(s).Methods: CIA rats were prepared and treated orally with TAPC at doses of 50, 100 and 200 mg/kg/day, for 24 days. Paw volume and arthritis score were measured prior to TAPC treatment, and subsequently at 3-day intervals on days 3, 6, 9, 12, 15, 18, 21 and 24. Serum levels of TNF-α, IL-6 and IL-17 were determined by enzyme-linked immunosorbent assay (ELISA), while synovial tissue TNF-α, IL-6 and IL-17mRNA expressions were assayed by real time-polymerase chain reaction (RT-PCR). Thymus and spleen indices were also determined.Results: TAPC (50, 100 and 200 mg/kg) significantly alleviated paw swelling (p < 0.05), arthritis scores (p < 0.05) and thymus and spleen indices (p < 0.05) of CIA rats, when compared with the control rats. In addition, TAPC significantly decreased serum levels of the pro-inflammatory cytokines TNF-α, IL-6 and IL-17 (p < 0.01); and down-regulated their mRNA expressions in synovial tissues (p < 0.01).Conclusion: These results suggest that TAPC exerts good anti-arthritic activity in rats, most probably via suppression of inflammatory responses.Keywords: Polygonum cuspidatum, Anthraquinone, Type II collagen-induced arthritis, Pro-inflammatory cytokines