TLR signaling in the gut in health and disease

J Immunol. 2005 Apr 15;174(8):4453-60. doi: 10.4049/jimmunol.174.8.4453.

Abstract

The human intestine has evolved in the presence of diverse enteric microflora. TLRs convert the recognition of pathogen-associated molecules in the gut into signals for anti-microbial peptide expression, barrier fortification, and proliferation of epithelial cells. Healing of injured intestinal epithelium and clearance of intramucosal bacteria require the presence of intact TLR signaling. Nucleotide oligomerization domain (Nod)1 and Nod2 are additional pattern recognition receptors that are required for defense against invasive enteric pathogens. Through spatial and functional localization of TLR and Nod molecules, the normal gut maintains a state of controlled inflammation. By contrast, patients with inflammatory bowel disease demonstrate inflammation in response to the normal flora. A subset of these patients carry polymorphisms in TLR and CARD15/NOD2 genes. A better understanding of the delicate regulation of TLR and Nod molecules in the gut may lead to improved treatment for enteric infections and idiopathic inflammatory bowel diseases.

Publication types

  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / immunology
  • Bacteria / immunology
  • Bacteria / pathogenicity
  • Enteritis / immunology
  • Humans
  • Immunity, Innate
  • Immunity, Mucosal
  • Inflammatory Bowel Diseases / genetics
  • Inflammatory Bowel Diseases / immunology
  • Intestinal Mucosa / immunology*
  • Intestinal Mucosa / microbiology
  • Intracellular Signaling Peptides and Proteins
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / immunology*
  • Models, Immunological
  • Nod1 Signaling Adaptor Protein
  • Nod2 Signaling Adaptor Protein
  • Polymorphism, Genetic
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / immunology*
  • Signal Transduction
  • Toll-Like Receptors

Substances

  • Adaptor Proteins, Signal Transducing
  • Intracellular Signaling Peptides and Proteins
  • Membrane Glycoproteins
  • NOD1 protein, human
  • NOD2 protein, human
  • Nod1 Signaling Adaptor Protein
  • Nod2 Signaling Adaptor Protein
  • Receptors, Cell Surface
  • Toll-Like Receptors