Prostromelysin and procollagenase genes are differentially UP‐regulated in chondrocytes from the knees of rabbits with experimental osteoarthritis

Abstract

OBJECTIVE: To determine the relative expressions of matrix metalloprotease (MMP) genes pro-MMP1 and pro-MMP3 in the cartilage of rabbits with experimentally induced osteoarthritis (OA), and to assess the role of the chondrocyte in this process. METHODS: OA was induced in rabbits after partial medial meniscectomy. Rabbits were killed at 4 weeks or 8 weeks, and total cellular RNA was prepared from cartilage and probed by Northern blotting with pro-MMP 32P-labeled complementary DNA. Monolayer chondrocytes were used to assess MMP-inducing activity of chondrocyte factor(s). RESULTS: Pro-MMP messenger RNAs (mRNAs) were up-regulated in experimental OA cartilage; pro-MMP3 mRNA expression exceeded that of pro-MMP1. Conditioned medium from OA-derived chondrocytes up-regulated pro-MMP mRNAs in normal chondrocytes. CONCLUSION: Up-regulation of MMP genes in this OA model may contribute to cartilage degradation. Chondrocytes up-regulate MMP genes via an autocrine pathway.