Human intestinal epithelial cells are broadly unresponsive to toll-like receptor 2-dependent bacterial ligands: Implications for host-microbial interactions in the gut

Gil Melmed, Lisa S. Thomas, Nahee Lee, Samuel Y. Tesfay, Katie Lukasek, Kathrin S. Michelsen, Yuehua Zhou, Bing Hu, Moshe Arditi, Maria T Abreu

Research output: Contribution to journalArticle

352 Citations (Scopus)

Abstract

Intestinal epithelial cells (IEC) interact with a high density of Gram-positive bacteria and are active participants in mucosal immune responses. Recognition of Gram-positive organisms by Toll-like receptor (TLR)2 induces proinflammatory gene expression by diverse cells. We hypothesized that IEC are unresponsive to Gram-positive pathogen-associated molecular patterns and sought to characterize the functional responses of IEC to TLR2-specific ligands. Human colonic epithelial cells isolated by laser capture microscopy and IEC lines (Caco-2, T84, HT-29) were analyzed for expression of TLR2, TLR6, TLR1, and Toll inhibitory protein (Tollip) mRNA by RT-PCR and quantitative real-time PCR. Response to Gram-positive bacterial ligands was measured by NF-κB reporter gene activation and IL-8 secretion. TLR2 protein expression was analyzed by immunofluorescence and flow cytometry. Colonic epithelial cells and lamina propria cells from both uninflamed and inflamed tissue demonstrate low expression of TLR2 mRNA compared with THP-1 monocytes. IECs were unresponsive to TLR2 ligands including the staphylococcal-derived Ags phenol soluble modulin, peptidoglycan, and lipotechoic acid and the mycobacterial-derived Ag soluble tuberculosis factor. Transgenic expression of TLR2 and TLR6 restored responsiveness to phenol soluble modulin and peptidoglycan in IEC. In addition to low levels of TLR2 protein expression, IEC also express high levels of the inhibitory molecule Tollip. We conclude that IEC are broadly unresponsive to TLR2 ligands secondary to deficient expression of TLR2 and TLR6. The relative absence of TLR2 protein expression by IEC and high level of Tollip expression may be important in preventing chronic proinflammatory cytokine secretion in response to commensal Gram-positive bacteria in the gut.

Original languageEnglish
Pages (from-to)1406-1415
Number of pages10
JournalJournal of Immunology
Volume170
Issue number3
StatePublished - Feb 1 2003
Externally publishedYes

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Microbial Interactions
Toll-Like Receptor 2
Epithelial Cells
Ligands
Proteins
Peptidoglycan
Gram-Positive Bacteria
Mucosal Immunity
Messenger RNA
Interleukin-8
Reporter Genes
Confocal Microscopy
Transcriptional Activation
Fluorescent Antibody Technique
Real-Time Polymerase Chain Reaction
Monocytes
Flow Cytometry
Mucous Membrane
Tuberculosis

ASJC Scopus subject areas

  • Immunology

Cite this

Human intestinal epithelial cells are broadly unresponsive to toll-like receptor 2-dependent bacterial ligands : Implications for host-microbial interactions in the gut. / Melmed, Gil; Thomas, Lisa S.; Lee, Nahee; Tesfay, Samuel Y.; Lukasek, Katie; Michelsen, Kathrin S.; Zhou, Yuehua; Hu, Bing; Arditi, Moshe; Abreu, Maria T.

In: Journal of Immunology, Vol. 170, No. 3, 01.02.2003, p. 1406-1415.

Research output: Contribution to journalArticle

Melmed, G, Thomas, LS, Lee, N, Tesfay, SY, Lukasek, K, Michelsen, KS, Zhou, Y, Hu, B, Arditi, M & Abreu, MT 2003, 'Human intestinal epithelial cells are broadly unresponsive to toll-like receptor 2-dependent bacterial ligands: Implications for host-microbial interactions in the gut', Journal of Immunology, vol. 170, no. 3, pp. 1406-1415.
Melmed, Gil ; Thomas, Lisa S. ; Lee, Nahee ; Tesfay, Samuel Y. ; Lukasek, Katie ; Michelsen, Kathrin S. ; Zhou, Yuehua ; Hu, Bing ; Arditi, Moshe ; Abreu, Maria T. / Human intestinal epithelial cells are broadly unresponsive to toll-like receptor 2-dependent bacterial ligands : Implications for host-microbial interactions in the gut. In: Journal of Immunology. 2003 ; Vol. 170, No. 3. pp. 1406-1415.
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AU - Michelsen, Kathrin S.

AU - Zhou, Yuehua

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