Cartilage oligomeric matrix protein level in rheumatic diseases: potential use as a marker for measuring articular cartilage damage and/or the therapeutic efficacy of treatments.

Cartilage oligomeric matrix protein (COMP) is a tissue-specific noncollagenous protein that was first detected in the serum and the synovial fluid of patients suffering from rheumatic disorders, such as rheumatoid arthritis, reactive arthritis, juvenile chronic arthritis, and osteoarthritis. In this review, the authors consider serum COMP levels in different diseases and discuss their study of patients with rheumatoid arthritis treated with anti-TNF-alpha, to evaluate whether COMP is able to predict a rapid and sustained clinical response to these drugs. They observe that patients with high COMP levels have a lower ACR 70 response independently of the state of systemic inflammation, and conclude that COMP seems to have a pathogenetic role that is independent of the mechanisms regulating inflammatory processes.