title: Toll-like receptor 4-mediated signaling by epithelial surfaces: necessity or threat?
abstract: Recent data suggest that the lipopolysaccharide receptor Toll-like receptor (TLR) 4 is expressed by epithelial cells and might play a role in the mucosal host defense against Gram-negative bacteria. However, since many body surfaces are colonized by the physiological microflora, activation of epithelial TLRs must be tightly controlled to avoid unintended stimulation and mucosal inflammation. The present review summarizes the current understanding of TLR4-mediated recognition and addresses specific questions on microbial recognition on mucosal surfaces, with particular emphasis on the gastrointestinal and urinary tract.
authors.affiliation: Microbiology and Tumor Biology Center (MTC) and Swedish Institute for Disease Control (SMI), Karolinska Institutet, Nobelsväg 16, 17177 Stockholm, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Bäckhed
authors.forename: Mathias
authors.initials: M
authors.lastname: Hornef
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000235:genetics / Q000502:physiology; D001419:Bacteria / Q000276:immunology / Q000472:pathogenicity; D004847:Epithelial Cells; D006801:Humans; D007413:Intestinal Mucosa / Q000276:immunology / Q000382:microbiology / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000502:physiology*; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology*; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors; D014551:Urinary Tract / Q000276:immunology / Q000382:microbiology
chemical_list: D000954:Antigens, Surface; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors