ADIPONECTIN AND ITS THREE SUBFORMS CORRELATE WITH MRI SYNOVIAL INFLAMMATION IN KNEE OSTEOARTHRITIS

Background: The adipocyte-derived adiponectin is present in plasma and synovial fluid (SF) from patients with osteoarthritis (OA). Adiponectin circulates in three subforms: high, medium and low molecular weight (HMW, MMW, and LMW). Both experimental and clinical results indicate that adiponectin is involved in cartilage destruction in OA. Data on the effects of adiponectin and its subforms in knee OA are sparse. Objectives: The objective of the study was to compare plasma and SF levels of adiponectin and its subforms in patients with moderate to severe knee OA and to correlate these values to morphological changes measured by magnetic resonance imaging (MRI) and to conventional parameters for pain and function. Methods: We included 23 patients fulfilling the American College of Rheumatology criteria for primary OA of the knee joint. Plasma and SF adiponectin was determined by an in-house time-resolved immuno-fluorometric assay. HMM, MMW and LMW subforms were separated by fast protein liquid chromatography. Synovitis, effusion, and bone marrow lesions were estimated by MRI. Pain was scored on a visual analogue scale immediately after walking 50 m. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Lequesne Functional Indexes were performed. Results: The concentration of adiponectin and its three subforms were higher in plasma than in SF (all p<0.001). SF adiponectin and all its subforms were positively correlated with the degree of synovitis on MRI, and LMW was positively correlated with MRI effusion. No other correlations with effusion or bone marrow lesions were found (see table). Plasma adiponectin and its subforms did not correlate with MRI data. No correlations were found to conventional parameters for pain and function, neither for plasma nor for SF values. Correlations between SF adiponectin and its subforms and MRI data. Adiponectin Synovial fluidMRI SynovitisMRI EffusionMRI bone marrow lesions Total adiponectin0.52 (0.02)NSNS HMW0.48 (0.02)NSNS MMW0.46 (0.03)NSNS LMW0.48 (0.02)0.45 (0.03)NS Data are presented as r-values and p-values in brackets. NS: not significant. Conclusion: Levels of SF adiponectin and its three subforms were correlated with the degree of MRI synovitis in knee OA. Our findings support that adiponectin plays a pathogenetic role in knee OA. Disclosure of Interest: None declaredCitation: Annals of the Rheumatic Diseases, volume 68, supplement 3, year 2009, page 142Session: Abstract Session: Osteoarthritis Clinical advances (Oral Presentations )