Objective: To evaluate the safety and efficacy of L-asparaginase as an immunosuppressive agent in a mouse model of rheumatoid arthritis.
Methods: Male DBA/1 mice with collagen-induced arthritis (CIA) were treated at different intervals with various doses of native and pegylated L-asparaginase from E. coli. The mice were observed for 4 weeks during which time arthritis was scored. Outcome parameters included effect on severity and progression of established arthritis as well as prevention of disease. In addition, X-rays from the affected joints were obtained for comparison.
Results: Both native L-asparaginase at a dose of 50 IU/injection intraperitoneally three days a week and pegylated asparaginase (PEG-L-asparaginase) at a dose of 25 IU/injection twice a week, significantly reduced the mean arthritic score (MAS) in mice with established arthritis (p < 0.001 for PEG-L-asparaginase). When native L-asparaginase was administered before the onset of arthritis (days 14-post immunization) the number of mice developing arthritis as well as the number of arthritic paws and the severity of arthritis in the treatment group were significantly decreased (p < 0.0001). Significant differences were found in the X-ray evaluation between treated and control mice. None of the animals died due to drug related events or showed signs of asparaginase induced toxicity.
Conclusion: Our data provide the first direct evidence that L-asparaginase is a potent antiarthritic agent and may represent an effective second line agent for future treatment studies in juvenile and adult rheumatoid arthritis.