120-kDa FN-fragment Induces MCP-1 Production in Human Temporomandibular Joint Fibroblast-like Synoviocytes

Abstract

Fibronectin is a component of the extracellular matrix in the synovium. Fibronectin fragments（FN-fragments）result from fibronectin breakdown by proteolytic enzymes released from an early inflammatory response. We examined the effect of a 120-kDa fibronectin fragment（120-kDa FN-fragment）in the inflammatory condition of temporomandibular joint（TMJ）synovitis. Fibroblast-like synoviocytes, which were isolated from the TMJ synovium using the outgrowth method, were treated with or without 120-kDa FN-fragment. The fibronectin fragment induced the expression of monocyte chemotactic protein（MCP）-1, -2, and -3 genes in fibroblast-like synoviocytes as seen with DNA microarray analysis and real-time PCR. Among 120-kDa FN-fragment response genes, MCP-1（also called CCL2）, which is the main MCP chemokine, was abundantly expressed. MCP-1 protein level was increased in the conditioned medium with fibroblast-like synoviocytes treated with 120-kDa FN-fragment using ELISA. Furthermore, experiments using inhibitors of signaling pathway revealed that 120-kDa FN-fragment up-regulated MCP-1 expression as a result of NF-κB activation. MCP-1 mainly induces monocyte/macrophage migration in inflammation caused by various diseases. These results suggest that production of the MCP chemokine by 120-kDa FN-fragment may be involved in promoting the inflammatory condition of TMJ.