Cross-sectional and predictive associations between plasma adipokines and radiographic signs of early-stage knee osteoarthritis: data from CHECK.

OBJECTIVE: To investigate cross-sectional and predictive associations of plasma adipokines with biochemical markers of systemic joint metabolism and radiographic signs of early-stage knee osteoarthritis (OA). DESIGN: The adipokines pLeptin, pAdiponectin, and pResistin, the cartilage markers C-terminal telopeptide of type II collagen (uCTX-II), N-terminal propeptide of type IIA procollagen (sPIIANP), chondroitin sulfate 846 (sCS846), and cartilage oligomeric matrix protein (sCOMP), and the synovial markers hyaluronic acid (sHA) and N-terminal propeptide of type III procollagen (sPIIINP) were assessed by enzyme-linked immunosorbent assay or radioactive immunoassay in baseline samples of Cohort Hip and Cohort Knee (CHECK), a cohort of 1002 subjects with early-stage symptomatic knee and/or hip OA. Knee radiographs were obtained at baseline and after 2 and 5 years and scored according to Kellgren & Lawrence. RESULTS: pLeptin showed positive associations with uCTX-II, sCOMP, sPIIANP, sHA, and sPIIINP, and with presence and progression of radiographic knee OA. Associations expectedly disappeared after adjustment for body mass index. pResistin showed positive associations with sPIIINP and present and incident radiographic knee OA that were largely independent of BMI. pAdiponectin showed positive associations with uCTX-II and sCOMP. Furthermore, pAdiponectin did not show associations with radiographic knee OA on itself, but associations of pResistin with present radiographic knee OA were stronger in higher pAdiponectin tertiles (P = 0.024 for interaction between pAdiponectin and pResistin). Although statistically significant, all associations were weak. CONCLUSIONS: Adipokines may have aggravating, although may be minor, structural effects in early-stage knee OA.