title: Expression of Toll-like receptors in enterocromaffin-like cells and their function in histamine release.
abstract: BACKGROUND
  Enterocromaffin-like cells (ECL) are specialized endocrine gastric cells able to release histamine, which in turn controls gastric acid production by parietal cells. Helicobacter pylori infection and other conditions signal in the gastrointestinal tract via Toll-like receptors (TLRs) and modify gastric acid production, but there is no evidence of expression and function of TLRs in ECL cells. In this work, we analyzed gene and protein expression of TLR-2, 4, 5, and 9, and other molecules involved in TLR signaling in ECL cells.
  
  
  METHODS
  ECL cells were isolated from Sprague-Dawley rats. The histamine-releasing ability of TLR ligands was also evaluated after culture of the ECL cells for a short time.
  
  
  RESULTS
  With ECL cells that expressed the TLR-2, TLR-4, TLR-5, and TLR-9 genes we were able to confirm protein expression for TLR-2, TLR-5, and TLR-9. Functionally, ECL cells were able to release histamine in response to TLR-2 stimulation by peptidoglycan (PGN), a TLR-2 ligand. After PGN stimulus, IRAK and p38 phosphorylation could be observed. SB 203580, a p38 inhibitor, reversed PGN-induced histamine release. Lipopolysaccharide (LPS), a TLR-4 ligand, was also able to induce histamine release in ECL cells, but by a mechanism independent of TLRs.
  
  
  CONCLUSIONS
  We have demonstrated for the first time that ECL cells express TLRs and respond to TLR-2 ligand by increasing histamine release. This response could be involved in host defense against gastrointestinal bacterial pathogens but could also contribute to control of gastric acid secretion in the absence of pathogens.
authors.affiliation: Clinical Pharmacology and Gastroenterology Unit, São Francisco University Medical School, Av. São Francisco de Assis 218, Bragança Paulista, SP 12916-900, Brazil.
authors.forename: Carolina Bernardi
authors.initials: CB
authors.lastname: Stefani
authors.forename: Rafael Martins
authors.initials: RM
authors.lastname: de Oliveira
authors.forename: Angélica Aparecida Antoniellis
authors.initials: AA
authors.lastname: Silveira
authors.forename: Lucio Fabio Caldas
authors.initials: LF
authors.lastname: Ferraz
authors.forename: Marcelo Lima
authors.initials: ML
authors.lastname: Ribeiro
authors.forename: Alessandra
authors.initials: A
authors.lastname: Gambero
authors.forename: José
authors.initials: J
authors.lastname: Pedrazzoli Júnior
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D006632:Histamine / Q000378:metabolism*; D008024:Ligands; D008297:Male; D012313:RNA / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction; D013270:Stomach / Q000166:cytology*; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*
chemical_list: D008024:Ligands; D051193:Toll-Like Receptors; D012313:RNA; D006632:Histamine