Elevated chemerin levels in synovial fluid and synovial membrane from patients with knee osteoarthritis

To test the serum, synovial fluid and synovial membrane levels of the adipokine chemerin in patients with knee osteoarthritis (KOA) and investigate their relationships with the severity of articular cartilage damage and synovitis. According to the American College of Rheumatology criteria for diagnosis of osteoarthritis (OA), 30 cases with OA diagnoses (OA group) were selected from patients who underwent arthroscopic surgery in our hospital from June 2013 to February 2014. Another 30 cases with other knee joint diseases (non-OA group) were included as controls. The synovial fluid and serum levels of chemerin were assayed by ELISA, and the synovial membrane level of chemerin was assayed by the immunohistochemical method. The severity of the knee articular cartilage damage and synovitis-related pathological changes were evaluated by arthroscopy using the Outerbridge and Ayral scores, respectively. The synovial fluid and synovial membrane levels of chemerin in the OA group were higher than those in the non-OA group. Statistically significant differences were found between the two groups in the synovial fluid and synovial membrane levels of chemerin (P < 0.05). The synovial fluid and synovial membrane levels of chemerin were positively correlated with the serum level of high-sensitivity C-reactive protein (HS-CRP), Outerbridge score and Ayral score in the OA group. The synovial fluid and synovial membrane levels of chemerin are increased in KOA patients and are positively correlated with the severity of KOA.