Objective: To investigate the expression pattern of transforming growth factor-β-inducible gene-h3 (βig-h3) within rheumatoid synovial tissue and the regulation of βig-h3 synthesis in fibroblast-like synoviocyte (FLS). Methods: Synovial tissues obtained from patients with rheumatoid arthritis and osteoarthritis were obtained during joint replacement surgery. βig-h3 expression was evaluated with immunohistochemical stain. FLS was isolated from synovial tissues and stimulated with cytokines including TGF-β, TNF-α, IL-1β, IFN-γ, IL-6, IL-4, and IL-10. βig-h3 synthesis was measured using semiquantitative RT-PCR, ELISA, immunofluorescence stain, and flow cytometry. Results: Expression of βig-h3 was diffuse and abundant in both lining and sublining layers of rheumatoid synovium, which was more prominent than those of osteoarthritis. Production of βig-h3 in FLS was regulated by TGF-β1 in a dose-dependent manner and was highest at 5 ng/mL of TGF-β1. TNF-α and IL-1β upregulated the production of βig-h3 from FLS synergistically with TGF-β1 but other cytokines such as IL-4, IL-6, IL-10 did not affect. βig-h3 synthesis was efficiently inhibited by dexamethasone at higher dose (100 nM) but not by cyclosporine-A. Conclusion: Production of βig-h3, which is highly upregulated in rheumatoid synovitis, is differentially regulated by inflammatory cytokines.

Keywords: Rheumatoid arthritis, Transforming growth factor-β-inducible gene-h3, Fibroblast-like synoviocyte