COLLAGENASE-3 (MATRIX METALLOPROTEASE-13) IS PREFERENTIALLY LOCALIZEDIN THE DEEP LAYER OF HUMAN ARTHRITIC CARTILAGE IN-SITU - IN-VITRO MIMICKING EFFECT BY TRANSFORMING-GROWTH-FACTOR-BETA

Objective, To examine, by immunohistochemistry, the localization and d istribution of human collagenase-3 in normal, osteoarthritis (OA), and rheumatoid arthritis (RA) cartilage, and to investigate the effects o f interleukin-1 beta (IL-1 beta) and transforming growth factor beta ( TGF beta) on the synthesis and distribution of collagenase-3, Methods, Human cartilage specimens were obtained from tibial plateaus, In the first series of experiments, the OA specimens were excised from fibril lated and nonfibrillated areas of cartilage, and RA specimens were exc ised from lesional areas, including the cartilage-pannus junction when present, In the second series, full strips of cartilage were processe d for culture in the presence or absence of IL-1 beta (100 units/ml) o r TGF beta (150 ng/ml), Each specimen was processed for immunohistoche mical analysis using a collagenase-3 monoclonal antibody, Results. The number of cells that stained for collagenase-3 in normal cartilage wa s very low (similar to 3%), In OA cartilage, the percentage increased dramatically, and no difference was found between fibrillated and nonf ibrillated areas, A statistically significant increase in the percenta ge of cells staining for collagenase-3 was found in the deep layer com pared with the superficial layer, This finding was noted in both the f ibrillated areas (mean +/- SEM 58.4 +/- 1.6% and 40.1 +/- 3.9%, respec tively; P < 0.007) and the nonfibrillated areas (55.4 +/- 3.2% and 43. 2 +/- 2.7%; P < 0.01), Similarly, RA cartilage showed a statistically significant (P < 0.001) increase in the level of chondrocytes staining positive for collagenase-3 in the deep layers (46.4 +/- 4.1%) compare d with the superficial layers (26.2 +/- 3.4%), In these RA specimens, the numbers of positively staining chondrocytes were similar both clos e to and at a distance from the pannus junction, Both IL-1 beta and TG F beta increased the number of chondrocytes producing collagenase-3, I nterestingly, in normal specimens, TGF beta had a predominant effect i n the deep layers, while IL-1 beta had a greater effect on the superfi cial layers, Conclusion, This study demonstrates that, in situ, the in crease in the level of chondrocytes synthesizing collagenase-3 in arth ritic cartilage is predominant in the deep layers, The results further indicate that TGF beta can up-regulate the level of this enzyme and, in normal cartilage in vitro, can cause a mimicking of the in situ dis tribution observed in arthritic cartilage.