Inflammatory mediators: tracing links between obesity and osteoarthritis

Osteoarthritis (OA), the most common form of arthritis, is associated with joint malfunction and chronic disability in the aged population. It is a multifactorial disorder to which several factors-such as age, sex, trauma, and obesity-contribute significantly. Obesity is one of the most influential but modifiable risk factors because it exerts an increased mechanical stress on the tibiofemoral cartilage. However, the high prevalence of OA in obese individuals in non-weightbearing areas, like finger joints, suggests that the link between being overweight and OA lies with factors other than simple biomechanics. An important correlation has been made between obesity and inflammation. Adipose tissues (and the infrapatellar fat pad) play an important role in this context because they are the major source of cytokines, chemokines, and metabolically active mediators called adipokines (or adipocytokines). These metabolic factors are known to possess catabolic and proinflammatory properties and to orchestrate the pathophysiological processes in OA. This review provides information on the relationship between obesity and OA through biomechanical and biochemical factors and highlights the functions of important obesity-related inflammatory products in the initiation and progression of OA. This information will broaden our thinking in identifying the targets for both prevention and intervention for OA.