Response of Cartilage Oligomeric Matrix Protein to Monoclonal Antibody Drugs in Patients with Rheumatoid Arthritis

Abstract

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by an erosive synovitis, resulting in cartilage degeneration and joint destruction.1 A better understanding of the immune and inflammatory mechanisms underlying joint damage, leading to disorganization of the joint structures and functional damage, in patients with RA is fundamental for the development of effective therapies.2 Advances in molecular technology techniques have contributed greatly to the creation of targeted treatments aimed at blocking the action of pro-inflammatory cytokines (eg, tumor necrosis factor-alpha [TNF-a], interleukin-6 [IL-6]) and more effective therapeutic strategies decreasing the incidence of both synovitis and joint damage in patients with RA being treated with disease monitoring antirheumatic drugs (DMARDs).3 Serum biomarkers of cartilage turnover represent a potentially useful tool for assessing the efficacy of DMARDs in patients with RA.4 Among them, cartilage oligomeric matrix protein (COMP), a pentameric protein originally isolated from cartilage, seems to have a structural role in the formation of extracellular matrix and in the interaction between the matrix and its proteins.5 Many studies have shown that changes in serum levels of COMP are related to cartilage processes and may occur early in the course of RA.6,7 The enzyme-linked immunosorbent assay (ELISA) for COMP has been automated and shown to have good analytical performance characteristics. The total imprecision (CV%, coefficient variation) was 3.27%–5.50% for concentrations ranging between 7.09 and 14.69 U/L. The test was linear for COMP concentrations ranging between 4 and 32 U/L.8 Quantification of serum levels of COMP by ELISA have been introduced into clinical practice as a valuable support to clinical and radiological methods used in the early assessment of the progression of joint cartilage destruction and/or the effect of treatment in patients with RA.9–12 However, when a serum biomarker is used …