title: Varied role of the gut epithelium in mucosal homeostasis.
abstract: OBJECTIVE
  The epithelium makes numerous important contributions to intestinal function. It acts as a physical barrier to prevent pathogenic infection, but allows nutrient uptake and the bidirectional passage of ions and water to lubricate the intestinal lumen while restricting fluid loss. The epithelium mediates communication between the immune system and the commensal flora, and plays a major role in antigen sampling and development of tolerance. After mucosal injury, the epithelium must reestablish its barrier and transport functions for homeostasis to be restored. Here, we will discuss recent advances in our understanding of the roles of the epithelium in intestinal homeostasis.
  
  
  RESULTS
  Mechanisms responsible for epithelial communication with enteric flora and pathogens include the regulation and function of Toll-like receptors and nucleotide-binding oligomerization domain-2, and maintenance and repair of epithelial barrier properties, including the role of growth factors and bacterial peptides in epithelial repair.
  
  
  CONCLUSIONS
  Recent advances in our understanding of mechanisms by which the gut epithelium modulates, and is modified by, enteric flora and the mucosal immune system illuminate the importance of the epithelium in gut physiology. The work discussed may also identify novel targets that can potentially be modulated therapeutically, either with existing medications or newer agents in development.
authors: School of Medicine, University of California at San Diego, San Diego, California 92093-0063, USA.
authors: Declan F
authors: DF
authors: McCole
authors: Kim E
authors: KE
authors: Barrett
mesh_terms: D000938:Antigen-Presenting Cells / Q000276:immunology; D002446:Celiac Disease / Q000276:immunology; D003424:Crohn Disease / Q000276:immunology; D004847:Epithelial Cells / Q000502:physiology; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology* / Q000502:physiology*; D008070:Lipopolysaccharides / Q000276:immunology; D053473:Nod2 Signaling Adaptor Protein / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology
chemical_list: D008070:Lipopolysaccharides; C429018:NOD2 protein, human; D053473:Nod2 Signaling Adaptor Protein