Interleukin-6 predicts knee osteoarthritis

A higher body mass index (BMI) and increased circulating levels of interleukin-6 (IL-6) are associated with the development of radiographic knee osteoarthritis (RKOA). Therefore, IL-6 is a potential new biomarker for OA development that may provide information that is useful in predicting disease outcome.

Livshits and associates examined IL-6, tumor necrosis factor α (TNF-α), and C-reactive protein (CRP) in a cohort of patients from the Chingford Study (a population-based, prospective study of knee OA in healthy middle-aged women monitored for 15 years). They also measured BMI to see whether this was related to inflammation. Radiographic evidence of knee OA (Kellgren/Lawrence grade 2 or higher) served as the outcome criterion.

The BMI, CRP level, and IL-6 level were consistently higher in patients who had a diagnosis of RKOA than in those who did not have OA. Age, higher baseline BMI, and elevated levels of IL-6 at year 5 significantly and independently predicted who would have RKOA by year 10, but CRP levels did not. The evidence for an association with serum TNF-α levels was negligible.

The authors noted that highlighting the potential key role of IL-6 in the OA disease process may lead to studies of IL-6 blockade as a therapeutic strategy.