Reactive oxygen species and the regulation of metalloproteinase expression

Irreparable degradation of articular cartilage is a characteristic feature of arthritic diseases and much of this degradation occurs as a result of increased levels of matrix metalloproteinases (MMPs) such as collagenase and stromelysin [1-6]. The elevated levels of degradative enzymes are due to increased synthesis by cells in joint tissue such as chondrocytes and synoviocytes, as well as invading cells, such as macrophages and neutrophils [7-9]. Thus, depending on the type of joint disease, several cell types may be involved in promoting cartilage destruction. In osteoarthritic cartilage, there is a marked depletion of matrix around the chondrocyte suggesting that this cell plays a key role in cartilage degradation. In inflammatory arthritis, both resident cells, synoviocytes and chondrocytes, as well as invading inflammatory cells are involved.