Six-week old female BALB/C mice were immunized with type II collagen and treated with vehicle alone icariin (25 mg/kg) for 21 days; a control remained untreated. Serum concentrations of type I collagen C-terminal telopeptide (CTX-I) and cartilage oligomeric matrix protein (COMP) and urinary concentrations of deoxypyridinoline (DPD) were measured, and disease severity was assessed.
Compared with immunized, untreated mice, immunized icariin-treated mice had significantly lower urinary DPD (¡«25 % , p < 0.01) and serum COMP (¡«11.9 % , p < 0.01) concentrations, with serum CTX-1 (RatLaps) concentrations being significantly lower in immunized, icariin treated mice than in immunized, vehicle treated (p < 0.01) and non-immunized (p < 0.005) mice. Icariin also reduced the clinical signs of arthritis.
Icariin inhibited cathpesin K activity in vitro and was effective in a mouse model of CIA similar to human RA, suggesting that this agent may have promise in the treatment of patients with RA.