Exercise-induced changes in interleukin-10 in patients with knee osteoarthritis: new perspectives?

Osteoarthritis (OA) of the knee is a common chronic disease affecting more than half of older persons. Moreover, owing to both aging and life-style factors, its prevalence is expected to increase in the coming years. Undoubtedly, OA may lead to increased morbidity and reduced quality of life in many older people. OA progresses slowly and for clinicians it is a well-known phenomena that, although patients with OA suffer from chronic pain, exacerbations may occur and these are associated with more pain, low-grade inflammation, and joint swelling.Unfortunately, therapeutic options that interfere with the progression of OA have not yet been found. For that reason, pain reduction with analgesic and anti-inflammatory drugs and life-style interventions, such as weight loss in adipose older persons and physical therapy, are the treatment options for OA. Exercise therapy has been shown to be beneficial for pain and physical functioning. However, the underlying mechanism of the effects of exercise therapy has not been fully elucidated.From that perspective, we welcome the article by Helmark and colleagues [1] in this issue of Arthritis Research & Therapy. In the article, which shows that exercise therapy appears to influence the intra-articular inflammatory response, the authors observed the effects of exercise on (peri-)synovial biochemical markers by using the microdialysis method. Surprisingly, this study showed that exercise might also influence the inflammatory processes in the joint. Women with symptomatic knee OA and a Kellgren-Lawrence grade of at least 1 (n = 31) were randomly assigned to nonexercise or exercise therapy. Directly after exercise, blood and urine samples were taken and microdialysis catheters were placed. The catheters were positioned intra-articularly and extra-articularly (near the synovium), and every 30 minutes, samples were collected over a period of 3 hours. The intra-articular and peri-synovial interleukin- 10 (IL-10) levels were significantly i