Further investigation into the importance of this cytokine family in disease models is necessary to determine whether they play a central role in progressive joint degeneration in OA. Chemokines are small molecules that play an important role DAPT price in mediating recruitment and trafficking of inflammatory cells and mesenchymal progenitors. Many chemokines are produced in the joint tissues of patients with OA [28] and [41].

Thus, they represent potential therapeutic targets to either enhance repair mechanisms or decrease inflammation in patients with OA. We recently demonstrated that synovial inflammatory infiltrates were associated with expression of a distinct mRNA chemokine signature in patients with meniscal injury [87]. The signature included IL-8, CCL5, CCL19 and its receptor CCR7. Expression of CCL19 and CCR7 was also associated with greater pre-operative symptoms, and based on these observations, their expression may have utility as

biomarkers of early synovial inflammation. CCR7 is expressed by synovial fibroblasts, and mediates upregulation of VEGF in response to its ligand, CCL19 [14], suggesting a role in synovial angiogenesis. Other chemokines, Selleck Doramapimod specifically MCP-1 and MIP-1β, have been associated with knee pain in patients undergoing arthroscopic procedures [24]. An important role for MIP-1γ produced by T helper cells in the synovium was demonstrated in a murine model of OA induced by ligament transection [94]. Similar to the cytokines discussed above, chemokines can induce matrix metalloproteinase (MMP)-3 and proteoglycan loss from articular cartilage [11]. Furthermore, many chemokines may directly affect osteoclast-mediated remodeling of peri-articular bone. In summary, chemokines represent a class of soluble inflammatory mediators that have pleiotropic effects on multiple joint tissues, and may contribute to inflammation and clinical symptoms in patients with OA. Further studies are needed to investigate the utility of targeting specific chemokines for symptom control or disease modification in OA. There is increasing evidence that synovial inflammation

plays Tyrosine-protein kinase BLK a critical role in the symptoms and structural progression of OA. Importantly, synovitis has been shown to correlate with symptom severity, rate of cartilage degeneration and osteophytosis (Fig. 2). The synovial response in OA is complex and variable with regard to histologic pattern (Fig. 1), and in part this complexity can be attributed to changing patterns as disease evolves and progresses. Although structural joint damage in OA is a constant feature, the clinical syndrome of OA is quite variable, with differences in affected joint patterns, risk factors, rates of progression, and severity of symptoms. Further efforts to understand the cellular and molecular variability of OA-associated synovitis may provide insights into the clinical heterogeneity of the disease.