Background Osteoarthritis (OA) is characterized by the progressive destruction of articular cartilage with joint space narrowing and osteophyte formation (1). Although the etiology and pathogenesis of OA remain poorly understood, recent studies have shown that biochemical factors with physiological factors play an important role in the development of OA.
The Wnt-β-catenin signaling pathway has well-recognized roles as a critical regulator of bone and cartilage homeostasis (2). Previous many studies have suggested that elevated Wnt-β-catenin activity is a common mechanism in the excess bone formation and loss of overlying cartilage in OA (3). Sclerostin has been identified as an inhibitor of the Wnt pathways (4).
Objectives We hypothesized that concentrations of sclerostin in plasma and synovial fluid might be associated with severity in knee OA patients. The aim of the present study was to evaluate the relationships between radiographic grading of knee osteoarthritis and plasma and synovial fluid concentrations of sclerostin.
Methods Plasma and synovial fluid samples (n=87) were obtained from patients who underwent total knee replacement, arthroscopic partial meniscectomy, or arthroscopic cruciate ligament reconstruction. Disease severity was determined using radiographs of the knee and the Kellgren-Lawrence (K-L) grading scale. Sclerostin concentrations were evaluated using enzyme-linked immunosorbent assay.
Results Radiographic OA patients (K-L grade ≥2) had lower sclerostin concentrations than controls (K-L grade 0 or 1) in both plasma (373.5±299.7 pg/ml vs. 1157.7±1097.3 pg/ml, p<0.001) and synovial fluid (30.9±85.0 pg/ml vs. 434.6±641.0 pg/ml, p<0.001). Sclerostin concentrations in synovial fluid were 3.5-fold lower than in corresponding plasma samples (193.3±454.3 pg/ml vs. 689.0±823.9 pg/ml, p<0.001) and there was a positive correlation between plasma and synovial fluid sclerostin concentrations (r =0.904, p<0.001). Sclerostin correlated negatively with knee OA severity for both plasma (r = -480, p<0.001) and synovial fluid (r = -423, p<0.001).
Conclusions Sclerostin concentration in plasma and synovial fluid is inversely related to the severity of joint damage in knee OA. Sclerostin might play a role in the pathogenesis of the degenerative process of OA.
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Disclosure of Interest None Declared