Influence of neutrophil elastase on experimental rheumatoid arthritis.

To elucidate the role of neutrophil elatsase on joint destruction in rheumatoid arthritis (RA), the following experiments were performed.1. A specific inhibitor of neutrophil elastase (ONO-5046) was injected into the knee joint three times a week for three weeks in heat-killed E. coli O: 14 induced arthritis in 10 rabbits, which were prepared as RA models. As a result, the development of pathological changes in the synovial membrane and cartilage was found to be suppressed.2. Neutrophil elastase dissolved in saline was injected into the knee joint of rabbits for three to nine weeks in order to examine its effect on the joint histologically. A moderate degree of synovitis was observed in all the synovial membranes. In the long-term groups, the cartilage also degenerated.These findings suggested that neutrophil elastase should play a role as one of the etiologies to the joint destructive process of RA, and that the clinical application of its inhibitors might be expected.