Stimulation of Gro-.ALPHA. Gene Expression and Production by IL-I.BETA. in Synovial Fibroblasts from Human Temporomandibular Joints

Abstract

Elevated levels of IL-1β have been found in synovial fluid from patients with temporomandibular disorders (TMD) and are thought to be involved in pain and progression of TMD. Synovial cells in the temporomandibular joint have important roles in progression of synovitis ; however, their biological roles are poorly understood. In this study, we examined the effect of IL-1β on gene expression in synovial fibroblast cultures from 5 different patients. Gene expression was monitored by Affymetrix GeneChip analysis and real-time PCR. Gro-α protein level was measured by ELISA. Among the genes with altered expression, GeneChip analysis detected increased Gro-α mRNA in fibroblasts from all 5 synovial specimens. This increased Gro-α gene expression was confirmed by real-time PCR. Gro-α protein was preferentially increased by IL-1β in synovial fibroblasts. Gro-α has chemotactic effects on lymphocytes and monocytes, and it also regulates endothelial cell proliferation and stimulates angiogenesis. When these established effects are taken together with the results presented herein, increased gene expression and protein production of Gro-α in synovial fibroblasts in response to IL-1β appears to play an important role in recruitment of inflammatory cells into the synovium and in progression of synovitis.