A failure of TNFAIP3 negative regulation maintains sustained NF-κB activation in Sjögren's syndrome

Histochem Cell Biol. 2011 Jun;135(6):615-25. doi: 10.1007/s00418-011-0821-3. Epub 2011 May 21.

Abstract

Sjögren's syndrome (SS) is characterized by the features of systemic autoimmunity and exocrine gland dysfunction and inflammation. Deregulated cytokine production is known to contribute to the etiology of SS but the underlying molecular mechanism is still remains to be unclear. TNF-α-induced protein 3 or TNFAIP3 is involved in the negative feedback regulation of nuclear factor-κB (NF-κB) signaling in response to specific pro-inflammatory stimuli in different cell types. To define the contribution of TNFAIP3 to SS, the levels of TNFAIP3 expression in human salivary gland epithelial cells (SGEC) derived from active primary SS patients were analyzed. Histological analysis was performed on paraffin-embedded human Sjögren's samples and healthy tissues. In separate experiments, immunofluorescence staining, western blot analysis and quantitative real-time PCR for TNFAIP3 was conducted in SGEC from SS and healthy subjects. Our findings clearly demonstrate changes in levels of the protein and gene expression between healthy controls and SS patients, depicting a very weak positivity for TNFAIP3 in SS samples. TNFAIP3 was found down-regulated in SGECs derived from SS patients in comparison with controls, and the cells with down-regulated TNFAIP3 expression exhibited enhanced NF-κB activities. In addition, to investigate the role of TNFAIP3 in the activation of NF-κB, we depleted TNFAIP3 expression by siRNA in healthy SGEC after treatment with or without TNF-α. Intriguingly, the silencing of TNFAIP3 by its siRNA in healthy SGEC increased NF-κB activation that could explain the deregulated cytokines production observed in SS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cells, Cultured
  • DNA-Binding Proteins
  • Epithelial Cells / metabolism
  • Epithelial Cells / pathology
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics*
  • Intracellular Signaling Peptides and Proteins / metabolism
  • NF-kappa B / metabolism*
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Salivary Glands / metabolism
  • Salivary Glands / pathology
  • Signal Transduction / genetics
  • Sjogren's Syndrome / genetics*
  • Sjogren's Syndrome / pathology
  • Tumor Necrosis Factor alpha-Induced Protein 3

Substances

  • DNA-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • NF-kappa B
  • Nuclear Proteins
  • TNFAIP3 protein, human
  • Tumor Necrosis Factor alpha-Induced Protein 3