Heads up! How the intestinal epithelium safeguards mucosal barrier immunity through the inflammasome and beyond.
OBJECTIVE
The intestinal epithelium serves as a highly dynamic immunologic frontier - exhibiting both innate and adaptive immune features. This review focuses on recent advances and novel insights into key intrinsic processes of the intestinal epithelium to closely monitor its intracellular and extracellular environment, communicate messages to neighbouring cells and rapidly initiate active defensive and repair measures, if necessary.


RESULTS
The intestinal epithelium is uniquely equipped with a vast array of features to control immune barrier homeostasis at the gates of the healthy intestinal mucosa. Deficient Toll-like receptor or NOD-like receptor signalling in the intestinal epithelium may imbalance commensal-dependent homeostasis, facilitating mucosal injury and leading to inflammatory disease. Dysfunction of the NLRP3 inflammasome may trigger aggravation of mucosal inflammation and cancer and has been associated with human inflammatory bowel diseases. Deregulated autophagy may alter inflammasome activity.


CONCLUSIONS
Exciting progress has been made in better understanding the complex diversity of physiological functions of innate immune responses in the intestinal epithelial barrier. Regulatory platforms of signalling mechanisms exist which are closely related and interact. However, many questions remain to be answered and more puzzles have arisen which are highlighted here.
Cario
Elke
E
Division of Gastroenterology & Hepatology, University Hospital of Essen, and Medical School, University of Duisburg-Essen, Essen, Germany. elke.cario@uni-due.de
D000818:Animals; D002450:Cell Communication; D006706:Homeostasis / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate / Q000502:physiology*; D018928:Immunity, Mucosal; D058847:Inflammasomes / Q000276:immunology* / Q000502:physiology; D007249:Inflammation / Q000276:immunology; D015212:Inflammatory Bowel Diseases / Q000276:immunology; D007413:Intestinal Mucosa / Q000276:immunology* / Q000502:physiology; D015398:Signal Transduction; D051193:Toll-Like Receptors / Q000276:immunology
D058847:Inflammasomes; D051193:Toll-Like Receptors