Reduction of tumor necrosis factor induced nuclear factor-kappaB nuclear translocation and DNA binding by dexamethasone in human osteoarthritic synovial tissue explants

J Rheumatol. 2002 Apr;29(4):787-95.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Inflammatory Agents / pharmacology*
  • Cells, Cultured
  • DNA / metabolism*
  • DNA-Binding Proteins / metabolism
  • Dexamethasone / pharmacology*
  • Drug Combinations
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Fibroblasts / pathology
  • Humans
  • Image Processing, Computer-Assisted
  • Immunohistochemistry
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / biosynthesis*
  • Osteoarthritis* / metabolism
  • Osteoarthritis* / pathology
  • Recombinant Proteins
  • Synovial Membrane / drug effects*
  • Synovial Membrane / metabolism
  • Synovial Membrane / pathology
  • Transcription Factor AP-1 / metabolism
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha / pharmacology


  • Anti-Inflammatory Agents
  • DNA-Binding Proteins
  • Drug Combinations
  • NF-kappa B
  • Recombinant Proteins
  • Transcription Factor AP-1
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha
  • Dexamethasone
  • DNA