“For Whom the Bell Tolls!” - Innate Defense Mechanisms and Survival Strategies of the Intestinal Epithelium Against Lumenal Pathogens

Zusammenfassung

Das intestinale Epithel ist zentraler Bestandteil der defensiven Schutzbarriere des mukosalen Immunsystems - mit einer bipolaren Grenzfläche zwischen zahlreichen lumenalen Mikroben einerseits und Immunzellen der Lamina propria andererseits. Intestinale Epithelzellen exprimieren verschiedene “pattern recognition receptors”, die zur frühzeitigen Erkennung von “pathogen-associated molecular patterns” als „fremd” dienen und gezielte angeborene Immunantworten zur Verteidigung initiieren. Es wird hier das derzeitige Verständnis zusammengefasst, wie das intestinale Epithel mit verschiedenen angeborenen Immuneigenschaften lumenale Homöostase sichert, und es wird diskutiert, wie deren Dysregulation eine zentrale pathogenetische Rolle in der überschießenden Immunantwort bei chronisch-entzündlichen Darmerkrankungen spielen könnte.

Abstract

The intestinal epithelium serves as an essential defensive barrier of the mucosal immune system that forms a bipolar interface between the diverse populations of microbes of the lumen and subjacent immune cells present in the lamina propria. Intestinal epithelial cells express various pattern recognition receptors - poised to recognize microbial “pathogen-associated molecular patterns” as “non-self” and to rapidly initiate innate immune responses of survival and active defense strategies against lumenal pathogens. Current understanding of the variety of innate immune features present in intestinal epithelium to maintain homeostasis is summarized and the mechanisms through which dysregulation may play a central role in initiation and perpetuation of inflammatory bowel disease are discussed.

Schlüsselwöter

Angeborene Immunität - Intestinales Epithel - Wirtsverteidigung - Mukosa - Toll-like Rezeptoren - Nods - Apoptose

Key words

Innate immunity - intestinal epithelium - host defense - mucosa - toll-like receptors - nods - apoptosis

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