Background Diabetes-associated osteoarthritis has been proposed as a distinct OA phenotype. To date, this phenotype has not been thoroughly described both in terms of its clinical and laboratory manifestations. We hypothesized that patients with diabetes-associated OA might have changed biomarkers of cartilage destruction, autoimmunity, and DNA methylation.

Objectives To evaluate concentrations of serum aggrecan, autoantibodies to collagen type II (anti-CII), and global DNA methylation in peripheral blood mononuclear cells (PBMC) in patients with diabetes-associated OA.

Methods Sera and PBMC were obtained from 78 patients with diabetes-associated OA and 26 control OA patients. Circulating aggrecan and anti-CII levels were measured using commercial ELISA. To assess global PBMC methylation we measured nuclear 5-methylcytosine (5-MeC) using flow cytometry.

Results Patients with diabetes-associated OA had significantly increased concentrations of serum aggrecan (p=0.004), and anti-CII (p=0.006). In comparison with OA alone, PBMC nuclear levels of 5-MeC were significantly increased (p=0.001) in patients with OA and diabetes.

Conclusions Diabetes-associated OA is characterized by increased cartilage degradation, autoimmunity to CII, and elevated global PBMC methylation. These findings may provide further framework for studies on this OA phenotype pathogenesis.

Acknowledgements We acknowledge Dr H. Trifonova for her help in collecting clinical data and laboratory samples handling.

Disclosure of Interest None declared