VLA-5-mediated interaction with fibronectin induces cytokine production by human chondrocytes

Adhesion molecules of the integrin family, including very late activation antigens (VLA), have been implicated in various cellular functions. In this study, we investigated the contribution of integrin-mediated interaction with ECM proteins to the cytokine gene expression in human chondrocytes. Human articular chondrocytes expressed VLA-1, -2, -3 and -5 on the cell surface, and could adhere to various ECM proteins, especially to fibronectin (FN). Furthermore, the production of GM-CSF and IL-6 was potently induced by culturing chondrocytes on immobilized FN. This stimulative effect of FN was completely inhibited by an anti-integrin alpha 5 chain mAb, as well as by anti-integrin beta 1 chain mAbs. These results indicate an important role of the VLA-5-mediated interaction with FN in regulating inflammatory cytokine production by human articular chondrocytes.