Interleukin-6 in Synovial Fluid as a Tool for Differentiation of Inflammation and Degeneration in Chronic Synovitis and Treatment Selection

Although Osteoarthritis (OA) is a widespread type of arthritis, no cure or medication can halt its natural progression. Only weight loss and physiotherapy can help to relieve pain and preserve function. Chronic un-inflammatory synovitis is not uncommon in OA; however, Inflammatory Arthritis (IA) can also start in middle-aged adults affected by OA. Pain and swelling of the joints, especially in the knee joints, are usual complaints in rheumatological practice where the primary treatment for chronic inflammatory arthritis is disease-modifying antirheumatic drugs (DMARDs). At the same time, persistent chronic synovitis leads to secondary OA due to inflammation, aging, and other factors. Discrimination between chronic synovitis due to inflammation or degeneration poses a significant challenge, especially when specific markers for IA are negative. Interleukin-6 (IL-6) has been a research topic for many scientific publications over the past several years. Although IL-6 production and signaling have been observed in OA, a recently published article shows much more elevated IL-6 concentration in synovial fluid (SF) of symptomatic joints in different types of IA [1]. We decided to clarify the importance of IL-6 concentration in synovial fluid (SF) for diagnostic and treatment purposes.