Objectives: Metabolic factors play significant role in the natural history of knee osteoarthritis (KO). There is a limited understanding of molecular and cellular events that give rise to the disease in patients. This study explored the possible cellular mechanisms by which metabolic syndrome leads to KO.
Methods: This cross-sectional study enrolled 80 subjects with KO who fulfilled the ACR diagnostic criteria and were undergoing total knee replacement surgery. The patients were divided into two groups: KO patients without metabolic syndrome and KO patients with metabolic syndrome.
Results: We hypothesised that metabolic syndrome may accelerate pathogenesis of OA by enhanced RAGE axis in articular cartilage and Infrapatellar fat pad of the knee joint. We have found enhanced protein expression of receptor for advanced glycation end products (RAGE) and its ligands AGEs and HMGB-1 in knee joint tissue of KO patients with metabolic syndrome as compared to KO patients without metabolic syndrome. Further downstream, the gene expression of oxidative stress regulators such as NADPH and inflammation, NFĸB were upregulated in KO patients with MetS as compared to KO patients alone. Higher levels of advanced oxidation products and inflammatory marker IL-17 were exhibited in synovial fluid of KO patients with metabolic syndrome. The enhanced levels of these oxidative stress and inflammatory markers were reflected in the serum of KO patients with metabolic syndrome as well.
Conclusions: We conclude that enhanced function of RAGE axis could be one of the mechanisms by which metabolic syndrome leads to KO.