Interleukin-1-induced cartilage degradation is independent of substance P level in rabbit knees.

The effect of SP on recombinant human IL-1 alpha-induced cartilage degradation in rabbit knees was investigated. Co-injection of 10 ng IL-1 and 1 micrograms SP did not increase cartilage degradation above the level observed after injection of 10 ng IL-1 alone. Co-injection of 100 ng IL-1 and 150 micrograms Spantide, a potent SP antagonist, did not reduce the level of cartilage degradation. Infusion of 100 ng SP/day for two weeks did not induce cartilage degradation. These observations suggest that cartilage degradation induced by IL-1 is independent of SP concentrations in rabbit knees.