“…In contrast to RA, OA synovium and synovial fluid contain markedly lower levels of MMPs, and expression is restricted to active OA cartilage lesions, where destruction of type II collagen (CII) and proteoglycan occurs; these lesions contain MMPs 1,3,8,9,and 13. Surprisingly, the neutrophil collagenase (MMP-8) is found in arthritic lesions in the absence of neutrophils, demonstrating that chondrocytes can produce this enzyme (14,16). Comparing the 3 collagenases that are present, it is likely that MMP-13 plays a pivotal role in cartilage degradation because it is expressed by the chondrocytes and because it has the ability to hydrolyze CII more efficiently than the other collagenases (13).…”