title: Toll-like receptor 4 or 2 agonists decrease allergic inflammation.
abstract: Toll-like receptors (TLRs) recognize highly conserved microbial molecular patterns, such as found in endotoxin. This study tested whether TLR4 and TLR2 stimulation in vivo would modulate subsequent adaptive (allergic) immune responses. We analyzed the effects of pulmonary administration of a TLR4 agonist, lipid A (LpA), and two TLR2 agonists, peptidoglycan (Ppg) and PamCys, in a murine model of allergic inflammation. The TLR agonists were administered during allergen sensitization or challenge. Both TLR agonists decreased the allergen-induced pulmonary recruitment of eosinophils when administered at sensitization or challenge. When given before sensitization, the TLR4 and TLR2 agonists decreased additional allergen-induced parameters of inflammation (pulmonary eosinophilia, bronchoalveolar lavage IL-13, total serum IgE, and airway hyperresponsiveness). Interestingly, TLR4 and TLR2 agonists decreased the number of CD4+ cells in the lung. Also, at the site of local allergen stimulation, the draining thoracic lymph nodes, allergen-induced lymphocyte proliferation, and IL-13 secretion were decreased by administration of LpA and Ppg. These data provide a distinct example of the modulation of adaptive (allergic) responses by non-antigen-dependent stimuli. Our findings also demonstrate that both TLR4 and TLR2 agonists decrease allergic responses, supporting the concept that exposure to bacterial components under defined conditions may protect against allergic disease.
authors.affiliation: Respiratory and Critical Care Division, Brigham and Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
authors.forename: German
authors.initials: G
authors.lastname: Velasco
authors.forename: Monica
authors.initials: M
authors.lastname: Campo
authors.forename: Oscar J
authors.initials: OJ
authors.lastname: Manrique
authors.forename: Abdelouahab
authors.initials: A
authors.lastname: Bellou
authors.forename: Hongzhen
authors.initials: H
authors.lastname: He
authors.forename: Ruth S S
authors.initials: RS
authors.lastname: Arestides
authors.forename: Bianca
authors.initials: B
authors.lastname: Schaub
authors.forename: David L
authors.initials: DL
authors.lastname: Perkins
authors.forename: Patricia W
authors.initials: PW
authors.lastname: Finn
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D004802:Eosinophilia / Q000188:drug therapy; D006967:Hypersensitivity / Q000188:drug therapy*; D007249:Inflammation / Q000188:drug therapy*; D008070:Lipopolysaccharides / Q000008:administration & dosage / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D008562:Membrane Glycoproteins / Q000819:agonists*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011956:Receptors, Cell Surface / Q000819:agonists*; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors
chemical_list: D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D051193:Toll-Like Receptors