Background Osteoarthritis (OA) is a disease characterized by a number of structural changes including cartilage loss and subchondral bone abnormalities. Metabolic triggered inflammation has been implicated in the pathogenesis of OA. Serum resistin levels increase with obesity in humans and the specific functions of resistin and IL-17 are still unknown in the development of knee OA.
Objectives To investigate cross-sectional associations between serum levels of resistin and interleukin-17 and cartilage defects and bone marrow lesions in patients with knee symptomatic osteoarthritis (OA).
Methods 194 randomly-selected patients with knee symptomatic OA (mean 55.4 years, range 34 to 74, 87% females) were included in Anhui Osteoarthritis (AHOA) Study. Knee cartilage defects and bone marrow lesions were determined at medial and lateral tibial, femoral and patellar sites using T2-weighted fat-suppressed fast spin echo MRI. Serum resistin and IL-17 levels were measured using ELISA.
Results Serum resistin was positively associated with cartilage defects at lateral femoral (OR: 1.23, 95%CI 1.12 to 1.35), lateral tibial (OR: 1.14, 95%CI 1.04 to 1.24) and medial tibial (OR: 1.13, 95%CI 1.03 to 1.23) sites after adjustment for covariates. The significant associations were also present with bone marrow lesions at lateral femoral (OR: 1.19, 95%CI 1.09 to 1.30) and tibial sites (OR: 1.13, 95%CI 1.02 to 1.24) after adjustment for covariates. All these associations remained significant after further adjustment for IL-17. In patients with highest quartiles of hs-CRP (>2.45 pg/ml), IL-17 was significantly associated with total cartilage defect score (r=0.267, p=0.001) and cartilage defects at nearly all sites (except for medial tibial) after adjustment for covariates. These significant associations decreased in magnitude and became non significant at medial femoral, lateral tibial and patellar sites after further adjustment for resistin. Similarly, IL-17 was significantly associated with BMLs at lateral and medial femoral sites after adjustment for covariates, and the association at lateral femoral site became non significant after further adjustment for resistin.
Conclusions Serum levels of resistin are independently and consistently associated with cartilage defects and BMLs in patients with knee OA. In addition, the associations of serum IL-17 with cartilage defects and BMLs in patients with a higher inflammatory status are largely mediated by resistin suggesting resistin may play a key role in cartilage loss and bone abnormalities in patients with knee OA.
Disclosure of Interest None declared