TY - JOUR T1 - Reduction of tumor necrosis factor induced nuclear factor-kappaB nuclear translocation and DNA binding by dexamethasone in human osteoarthritic synovial tissue explants. JF - The Journal of Rheumatology JO - J Rheumatol SP - 787 LP - 795 VL - 29 IS - 4 AU - Thomas Lehmann AU - Christian Murphy AU - David G Zahra AU - Malcolm L Handel Y1 - 2002/04/01 UR - http://www.jrheum.org/content/29/4/787.abstract N2 - OBJECTIVE: The antiinflammatory effects of glucocorticoids are mediated by several mechanisms, including inhibition of nuclear factor-kappaB (NF-kappaB) nuclear translocation and DNA binding. This mechanism is not evident in some cell types, including endothelial cells and rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLS). We determined the effect of glucocorticoids and tumor necrosis factor (TNF) on nuclear localization and DNA binding of the transcription factor NF-kappaB in osteoarthritic (OA) synovial tissue. METHODS: Explants of synovial tissue from patients undergoing joint replacement surgery for arthritis were placed in culture and treated with dexamethasone 10(-6) M for 18 h and again at 30 min prior to stimulation with TNF for a further 30 min. NF-kappaB and AP-1 DNA binding activities were determined by electrophoretic mobility shift analysis of nuclear extracts prepared from 6 whole tissue explants. Nuclear localization of NF-kappaB was determined by quantitative immunohistochemistry for Rel-A(p65) in thin sections of 5 synovial tissue explants. RESULTS: TNF induced NF-kappaB nuclear translocation and DNA binding in all OA synovial tissue explants, although there were no consistent effects on AP-1 DNA binding. Dexamethasone reduced TNF stimulated nuclear translocation of RelA(p65) in all 5 OA synovial explants analyzed by immunohistochemistry. Dexamethasone partially decreased NF-kappaB DNA binding in 5 of 6 TNF stimulated explants and 4 of 6 unstimulated explants. In cultured rheumatoid arthritis and OA fibroblast-like synoviocytes and Mono Mac 6 cells the effects of dexamethasone on NF-kappaB DNA binding were not evident. CONCLUSION: Dexamethasone partially inhibits TNF induced NF-kappaB DNA binding in human synovial tissue. It is feasible to use explants of intact fresh human synovium as a substrate for the action of antirheumatic drugs targeting a transcription factor. ER -