Therapeutic and preventive effects of methotrexate on zymosan-induced arthritis in SKG mice.

The purpose of this study was to investigate the pathology of zymosan-induced arthritis in the SKG mouse model of rheumatoid arthritis in humans, and to validate this model as a reliable drug screening system. To achieve this purpose, methotrexate (1 or 10 mg/kg, once daily) or vehicle only was administered intraperitoneally to SKG mice with zymosan-induced arthritis. Histologically, this arthritis was characterized by the presence of granulation tissue rich in granulocytes. Methotrexate suppressed the development of arthritis in ankle and wrist joints in both clinical and histological studies. These results indicated that methotrexate has not only prophylactic, but also therapeutic effects on zymosan-induced arthritis developed in SKG mice and may thus be a promising control agent for drug research in the SKG mouse model of rheumatoid arthritis.