Synovitis in osteoarthritis (OA) is a predictor of more intense cartilage loss and a more aggressive course of the disease. Numerous studies have established the importance of the local low-grade inflammation from the earliest stages of the disease. In the conditions of synovitis, the synovial membrane has been infiltrated by mononuclear cells (macrophages and lymphocytes) which produce cytokines. The degree of infiltration is a major factor of the degenerative changes in the joints in OA. With persistent or recurrent local inflammation, the synovium is in state of hyperplasia,the neoangiogenesis begins, and the fibrosis occurs in later stages. Three groups of cytokines are involved in the pathogenesis of the activated OA: catabolic, anabolic, and regulatory. In addition to the "traditional" cytokines associated with the severity of OA are adipokines and lipid mediators (pristaglandins and leukotrienes). Nitric oxide synthase (iNOS) -induced NO production from arginine in chondrocytes is also associated with OA.
Identifying the key participants in the low-grade inflammation will allow new therapeutic approaches to be established and give new abilities for slowing the progression of the destruction of the joints.
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.