Dermatan sulfate in the synovial fluid of patients with knee osteoarthritis

Biochemical factors play an important role in osteoarthritis (OA) pathogenesis. The purpose of this study is to clarify whether the dermatan sulfate (DS) levels in the synovial fluid of patients with knee OA are related to residual cartilage. Synovial fluid was obtained from 51 OA patients. Knee radiographs were evaluated with the Kellgren–Lawrence (K/L) grading scale. The levels of the following disaccharides were measured by high-performance liquid chromatography (HPLC): DS (DSΔDi4S), chondroitin 6-sulfate (CSΔDi6S), and chondroitin 4-sulfate (CSΔDi4S). The concentration of cartilage oligomeric matrix protein (COMP) was measured by a sandwich ELISA. The levels of DSΔDi4S in Grades 0 and I OA were significantly higher than levels in Grade II (P = 0.0458), Grade III (P < 0.0001) and Grade IV (P < 0.0001), and we found strong relationships between the levels of DSΔDi4S and those of CSΔDi6S (P < 0.0001, r = 0.705), CSΔDi4S (P < 0.0001, r = 0.750), and COMP (P < 0.0001, r = 0.699). We conclude that the presence of DSΔDi4S reflects proteoglycan metabolism in the residual articular cartilage of OA patients. This suggests that metabolism of the small leucine-rich repeat proteoglycans decorin and biglycan, which contain chains of DSΔDi4S, is similar to that of aggrecan.