title: TLR2 and TLR9 modulate enteric nervous system inflammatory responses to lipopolysaccharide.
abstract: Accumulating evidence suggest that the enteric nervous system (ENS) plays important roles in gastrointestinal inflammatory responses, which could be in part mediated by Toll-like receptor (TLR) activation. The aim of this study was to characterise the expression and functionality of TLR2/4/9 in the ENS.
  
  
  
  TLR2/4/9 expression was assessed in the plexuses of adult rats and embryonic ENS cultures by immunofluorescence and quantitative PCR. Following stimulation with TLR2/4/9 ligands or their combinations, activation of NF-kB, production of TNF-α, IL-6 and MCP-1 and chemoattraction of RAW264.7 macrophages were evaluated by means of Western blot, ELISA, immunofluorescence and migration assays in transwell inserts.
  
  
  
  TLR2/4/9 staining colocalised with enteric neuronal markers, whereas their presence in enteroglial processes was low to inexistent. Stimulation of ENS cultures with selective ligands induced NF-kB activation and release of cytokines and chemokines by neurons and resident immunocytes. TLR2 neutralisation before lipopolysaccharide (LPS) challenge reduced production of inflammatory mediators, whereas combination of TLR2/4 ligands promoted macrophage migration. Combined stimulation of cultures with LPS and the CpG oligonucleotide 1826 (TLR4/9 ligands) caused a synergic increase in chemoattraction and cytokine production.
  
  
  
  Our results suggest that the ENS, and particularly enteric neurons, can integrate a variety of microbial signals and respond in a relatively selective fashion, depending on the particular TLRs stimulated. These findings additionally suggest that the ENS is capable of initiating a defensive response against pathogens and expanding inflammation.
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain.
authors.forename: Joan F
authors.initials: JF
authors.lastname: Burgueño
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Barba
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain.
authors.forename: Elena
authors.initials: E
authors.lastname: Eyre
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Romero
authors.affiliation: INSERM, UMR913, Nantes, F-44093, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Neunlist
authors.affiliation: Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, Bellaterra, Barcelona, 08193, Spain. ester.fernandez@uab.cat.
authors.forename: Ester
authors.initials: E
authors.lastname: Fernández
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000378:metabolism; D004195:Disease Models, Animal; D004622:Embryo, Mammalian; D017615:Enteric Nervous System / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007249:Inflammation / Q000139:chemically induced* / Q000473:pathology*; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D051195:Toll-Like Receptor 2 / Q000276:immunology / Q000378:metabolism*; D051217:Toll-Like Receptor 9 / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; C491766:Ccl2 protein, rat; D018932:Chemokine CCL2; D008070:Lipopolysaccharides; D016328:NF-kappa B; C495343:Tlr2 protein, rat; D051195:Toll-Like Receptor 2; D051217:Toll-Like Receptor 9
keywords: Chemoattraction; Enteric nervous system; Enteric neuron; Inflammation; TLR2; TLR4; TLR9