TLR4 and MD-2 expression is regulated by immune-mediated signals in human intestinal epithelial cells

Maria T Abreu, Elizabeth T. Arnold, Lisa S. Thomas, Rivkah Gonsky, Yuehua Zhou, Bing Hu, Moshe Arditi

Research output: Contribution to journalArticle

290 Citations (Scopus)

Abstract

The normal intestinal epithelium is not inflamed despite contact with a high density of commensal bacteria. Intestinal epithelial cells (IEC) express low levels of TLR4 and MD-2 and are lipopolysaccharide (LPS)-unresponsive. We hypothesized that immune-mediated signals regulate the expression of TLR4 and MD-2 in IEC. Expression of TLR4 and MD-2 was examined in normal colonic epithelial cells or intestinal epithelial cell lines. The effect of the cytokines interferon (IFN)-γ, IFN-α, and tumor necrosis factor-α (TNF-α) on TLR4 and MD-2 expression was examined by reverse transcription-PCR and Western blot. NF-κB transcriptional activation and interleukin-8 secretion were used as measures of LPS responsiveness. Native colonic epithelial cells and IEC lines express a low level of TLR4 and MD-2 mRNA. IFN-γ regulates MD-2 expression in both IEC lines, whereas IFN-γ and TNF-α regulate TLR4 mRNA expression in IEC lines. Pre-incubation with IFN-γ and/or TNF-α sensitizes IEC to LPS-dependent interleukin-8 secretion. To examine MD-2 transcriptional regulation, we cloned a 1-kb sequence proximal to the MD-2 gene translational start site. This promoter directed expression of a reporter gene in endothelial cells and IEC. IFN-γ positively regulated MD-2 promoter activity in IEC. Co-expression of a STAT inhibitor, SOCS3, blocked IFN-γ-mediated MD-2 promoter activation. T cell-derived cytokines lead to increased expression of TLR4 and MD-2 and LPS-dependent pro-inflammatory cytokine secretion in IEC. IFN-γ regulates expression of the critical TLR4 co-receptor MD-2 through the Janus tyrosine kinase-STAT pathway. Th1 cytokines may initiate or perpetuate intestinal inflammation by altering toll-like receptor expression and bacterial reactivity.

Original languageEnglish
Pages (from-to)20431-20437
Number of pages7
JournalJournal of Biological Chemistry
Volume277
Issue number23
DOIs
StatePublished - Jun 7 2002
Externally publishedYes

Fingerprint

Epithelial Cells
Interferons
Lipopolysaccharides
Cytokines
Cell Line
Tumor Necrosis Factor-alpha
Interleukin-8
Genes
Chemical activation
Intestinal Secretions
Janus Kinases
Messenger RNA
Toll-Like Receptor 4
T-cells
Toll-Like Receptors
Endothelial cells
Transcription
Intestinal Mucosa
Reporter Genes
Protein-Tyrosine Kinases

ASJC Scopus subject areas

  • Biochemistry

Cite this

TLR4 and MD-2 expression is regulated by immune-mediated signals in human intestinal epithelial cells. / Abreu, Maria T; Arnold, Elizabeth T.; Thomas, Lisa S.; Gonsky, Rivkah; Zhou, Yuehua; Hu, Bing; Arditi, Moshe.

In: Journal of Biological Chemistry, Vol. 277, No. 23, 07.06.2002, p. 20431-20437.

Research output: Contribution to journalArticle

Abreu, Maria T ; Arnold, Elizabeth T. ; Thomas, Lisa S. ; Gonsky, Rivkah ; Zhou, Yuehua ; Hu, Bing ; Arditi, Moshe. / TLR4 and MD-2 expression is regulated by immune-mediated signals in human intestinal epithelial cells. In: Journal of Biological Chemistry. 2002 ; Vol. 277, No. 23. pp. 20431-20437.
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