The use of Ribomunyl^®in the immunomodulatory treatment of rats with adjuvant arthritis

Immunomodulatory therapy of inflammatory rheumatic diseases, especially in refractory forms of systemic lupus erythematosus (Rovensky et al.) and rheumatoid arthritis (Mateicka et al.) has its tradition. The very immunosuppressive therapy may induce the development of resistance and to participate in recurrent secondary infections in patients suffering from systemic diseases of the connective tissue. Alternatives of immunomodulatory therapy are therefore sough for that would eliminate some adverse effects of immunosuppressive agents on the cell-mediated and non-specific immunity function, and would favorably affect the clinical condition of the patient.

To verify our working hypothesis concerning the appropriateness of immunomodulatory therapy with Ribomunyl^®, the adjuvant arthritis model in rats was chosen. Following drugs and their combinations were orally administered to animals in a long-term prophylactic course: Cyclosporine A (CyA, 2,5 mg/kg/day), methotrexate (MTX, 0,3 mg/kg, 2 times a week), Ribomunyl^® (25 mg/kg 4 times a week), CyA+MTX, CyA+Ribomunyl^®, MTX+Ribomunyl^®, and the three-combination of CyA+MTX+ Ribomunyl^®. When given in combination, both the doses and the frequency of administration were the same as when the drugs were administered alone. The following markers of inflammation and arthritic process were measured: serum albumin, joint X-ray, hind paw swelling, and on day 40 of the study, bone mineral density (BMD) and bone mineral content (BMC).

Our results showed that Ribomunyl^® alone has no marked effect on markers of inflammation and arthritis in animals with adjuvant arthritis. When combined with the immunosuppressive drugs CyA and MTX, a similar and/or better therapeutical effect was observed than with the basic drug without Ribomunyl^®. However, the effect of the three-combination of CyA+MTX+Ribomunyl^® was rather remarkable. This combination had the most pronounced therapeutical effect on rats with adjuvant arthritis. It significantly inhibited inflammatory and arthritic markers as well as BMD and BMC reductions.

Our results obtained using the adjuvant arthritis model suggest that immunomodulatory procedures are promising. These result therefore need to be verified in additional animal models and markers of cell-mediated immunity and/or cytokines involved in the induction of this therapeutic effect should be investigated.