The presence and production of soluble factors in the osteoarthritic (OA) joint have always been a focus of research, as they are assumed to play a role in initiation and/or progression of disease. Many tissue and cell types in the joint are capable of their production, with the synovial fluid serving as a reservoir into which they can be secreted. Although an increasing interest is directed towards chemokines, growth factors and adipokines, traditionally, a subset of inflammatory, anti-inflammatory and modulatory cytokines has been studied. Differential profiles compared to healthy joints were found in the knee and other OA joints, whereby also joint damage induces a specific change in secretory pattern. However, for the cytokines commonly assumed to play a role in OA, such as IL-1 and TNFa, their consistently low levels, frequent lack of association with disease and the presence of natural inhibitors suggest that other soluble factors may be more promising as possible targets.,
Erasmus MC: University Medical Center Rotterdam

Bastiaansen-Jenniskens, Y., Saris, D., & Creemers, L. (2017). Pro-and anti-inflammatory cytokine profiles in osteoarthritis. In Cartilage: Volume 2: Pathophysiology (pp. 81–97). doi:10.1007/978-3-319-45803-8_5