DIFFERENTIAL IN-VIVO EXPRESSION OF COLLAGENASE MESSENGER-RNA IN SYNOVIUM AND CARTILAGE - QUANTITATIVE COMPARISON WITH STROMELYSIN MESSENGER-RNA LEVELS IN HUMAN RHEUMATOID-ARTHRITIS AND OSTEOARTHRITIS PATIENTS AND IN 2 ANIMAL-MODELS OF ACUTE INFLAMMATORY ARTHRITIS

Objective. To compare quantitatively the in vivo expression of collage nase messenger RNA (mRNA) and stromelysin mRNA in the joint tissues of human osteoarthritis (OA) and rheumatoid arthritis (RA) patients and in two animal models of acute inflammatory arthritis. Methods. In vivo levels of metalloproteinase mRNA and protein were determined by quant itative Northern hybridization and by enzyme-linked immunosorbent assa y, respectively. Results. In synovium, mean levels of collagenase mRNA were similar to those of stromelysin mRNA; however, in cartilage, mea n levels of collagenase mRNA were significantly lower. The ratios of c ollagenase mRNA to stromelysin mRNA levels in RA and OA cartilage refl ected similar ratios of collagenase protein to stromelysin protein lev els in synovial fluid. Conclusion. The regulation of collagenase mRNA expression in cartilage is distinct from that of stromelysin, suggesti ng distinct roles for these two metalloproteinases in normal and abnor mal physiologic functioning of cartilage.