Intestinal Epithelial Cells: Immunological Aspects

Abstract

Intestinal epithelial cells are the cell boundary between the external environment and tissues of the gastrointestinal tract. From this interface the epithelial cells have evolved processes that help guide whether inflammation or an immune response will occur in the intestines. Indeed intestinal epithelial cells are active participants in the inflammatory and immune response because they (1) secrete inflammatory mediators, including cytokines, when they detect certain microbes; (2) secrete mediators when they become detached from the basement membrane; (3) recruit and engage dendritic cells, professional antigenā€presenting cells which sample the intestinal lumen prior to presenting antigens to lymphocytes and (4) directly present antigens to T lymphocytes using a unique repertoire of molecules. Antigen presentation to lymphocytes is required for the initiation of a specific adaptive immune response, whether humoral (antibody) or cellular, and may be key to explaining many human chronic inflammatory diseases.

Key concepts

  • Intestinal epithelial cells form a monolayer of cells that define the boundary between tissues of the intestine and the external environment.

  • From this point of interface, intestinal epithelial cells receive and interpret insults/assaults from the intestinal lumen and signal to the tissues whether inflammation will ensue.

  • Intestinal epithelial cells communicate through the secretion of protein and glycoprotein mediators, some of which launch the inflammatory response including by recruiting leucocytes into the tissues.

  • Intestinal epithelial cells interact with and control lymphocyte activation using specialized molecules, some of which are used in antigen presentation.

  • Antigen presentation to lymphocytes is critical to launching the adaptive (humoral and cellular) immune responses.

  • Antigen presentation by intestinal epithelial cells most commonly results in the inhibition of activation of T lymphocytes, including CD8+ T lymphocytes.

Keywords: intestinal epithelium; cytokine; chemokine; antigen presentation; CD1

Figure 1.

Architecture of the intestinal epithelium. The intestinal epithelium is a single‐cell thick layer of columnar epithelial cells lining the villi and crypts of the small intestine and crypts of the large intestine. The epithelial cells are polarized such that the apical surface brushborder microvilli are in contact with the lumen while the basolateral surface is adherent to the basement membrane. A population of stem cells exist around the fourth cell position from the crypt bottom and daughter cells arise from division of the stem cells. The daughter cells will also continue to divide and differentiate while migrating away from the stem cell position. These cells eventually stop dividing when differentiated into one of the final four main epithelial cell types. Interspersed among the epithelial cells and located between cells of the basolateral sides are the IELs. There also are lymphocytes under basement membrane of the epithelium in the tissue (lamina propria).

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Further Reading

Dougan SK, Kaser A and Blumberg RS (2007) CD1 expression on antigen‐presenting cells. Current Topics in Microbiology and Immunology 314: 113–141.

Gribar SC, Richardson WM, Sodhi CP and Hackman DJ (2008) No longer an innocent bystander: epithelial Toll‐like receptor signalling in the development of mucosal inflammation. Molecular Medicine 14: 645–659.

Hershberg RM and Mayer LF (2000) Antigen processing and presentation by intestinal epithelial cells – polarity and complexity. Immunology Today 21: 123–128.

Jabri B and Ebert E (2007) Human CD8+ intraepithelial lymphocytes: a unique model to study the regulation of effector cytotoxic T lymphocytes in tissue. Immunological Reviews 215: 202–214.

Lee JW, Wang P, Kattah MG et al. (2008) Differential regulation of chemokines by IL‐17 in colonic epithelial cells. Journal of Immunology 181: 6536–6545.

Matthews AN, Friend DS, Zimmerman N et al. (1998) Eotaxin is required for the baseline level of tissue Eosinophils. Proceedings of the National Academy of Sciences of the United States of America 95: 6273–6278.

Olivares‐Villagomez D, Mendez‐Fernandez YV et al. (2008) Thymus leukemia antigen controls intraepithelial lymphocyte function an inflammatory bowel disease. Proceedings of the National Academy of Sciences of the United States of America 105: 17931–17936.

Perera L, Shao L, Patel A et al. (2007) Expression of nonclassical class I molecules by intestinal epithelial cells. Inflammatory Bowel Diseases 13: 298–307.

Stadnyk AW (2002) Intestinal epithelial cells as a source of inflammatory cytokines and chemokines. Canadian Journal of Gastroenterology 16: 241–246.

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How to Cite close
Stadnyk, Andrew W(Sep 2009) Intestinal Epithelial Cells: Immunological Aspects. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0003816.pub2]