The Role of Chitinase-3-like Protein 1(YKL-40) as a Biomarker of Psoriatic Arthritis

Abstract

Psoriatic arthritis (PsA) is a chronic autoimmune disease characterised by joint inflammation and psoriatic skin changes. The manifestations of PsA are diverse involving peripheral joints, entheses, dactylitis and axial skeleton. Psoriatic arthritis is a distinctive form of inflammatory arthritis which can occur in association with psoriasis. Though it is now recognized as a separate disease entity from other inflammatory arthritic disorders, yet, it is considered a part of the seronegative spondyloarthropathy family with the characteristic inflammatory manifestations of both spinal and peripheral joints. The diagnosis of PsA may be missed because the patients commonly presented by symptoms other than frank arthritis. The most sensitive and specific criteria that is available to date is the Classification Criteria for Psoriatic Arthritis (CASPAR). Early diagnosis and treatment result in better outcomes for patients with PsA in terms of joint function and erosive joint disease. Chitinase-3-like protein 1 (YKL-40), a 39 kD heparin and chitin binding glycoprotein, is a novel potential biomarker of inflammatory processes, which is expressed and secreted by immune cells such as activated macrophages and neutrophils. It is hypothesized that YKL-40 participates in acute and chronic inflammations, based on the fact that this glycoprotein is over-expressed in pathological conditions associated with active inflammatory processes.