Effect of FTY720, a novel immunosuppressant, on adjuvant-induced arthritis in rats.

Abstract

Anti-arthritic effect of FTY720, a novel immunosuppressant, was compared with those of immunosuppressants cyclosporin A and tacrolimus in adjuvant-induced arthritis in rats. Male LEW rats. FTY720 (0.03-0.3 mg/kg), cyclosporin A (1-10 mg/kg) or tacrolimus (0.3-3 mg/kg) were orally administered to rats for 21 days beginning on the day (day 0) of adjuvant inoculation. In addition, the anti-arthritic effect of FTY720 (0.3 mg/kg) and cyclosporin A (10 mg/kg) were evaluated by administration to animals for 5 consecutive days (days 2-6, 6-10, and 10-14). Adjuvant-induced arthritis was produced by intradermal injection of 0.5 mg heat-killed Mycobacterium tuberculosis. Hindpaw edema was measured plethysmographically. The day of arthritis onset was determined macroscopically. Bone degradation was determined by radiography. Peripheral blood leukocytes were classified microscopically. All test compounds inhibited the incidence of arthritis, hindpaw edema and bone destruction. In addition, FTY720 but not cyclosporin A or tacrolimus markedly decreased the number of peripheral blood lymphocytes. FTY720 treatment on days 6 to 10 inhibited the bone destruction and hindpaw edema. These results suggest that the anti-arthritic effect of FTY720 in this adjuvant-induced arthritic model was more potent than those of cyclosporin A and tacrolimus. FTY720 administered on days 6 to 10 showed the inhibitory effect on the bone destruction and hindpaw edema. FTY720 may be effective in the treatment of rheumatoid arthritis.