title: TLR4 and MyD88 control protection and pulmonary granulocytic recruitment in a murine intranasal RSV immunization and challenge model.
abstract: An intranasal vaccine composed of Toll-like receptor 2 (TLR2) ligand Neisseria meningitidis outer membrane proteins and Toll-like receptor 4 (TLR4) ligand Shigella flexneri lipopolysaccharide (LPS) (Protollin) and enriched respiratory syncytial virus (RSV) proteins (eRSV) has been demonstrated to promote balanced Th1/Th2 responses without eosinophil recruitment and to protect against challenge in mouse models. We used TLR2, TLR4 and myeloid differentiation factor 88 (MyD88) knock-out (-/-) mice to investigate the roles of these signalling pathways on immunogenicity, protection and pulmonary infiltrates following RSV immunization and challenge. Antigen-specific systemic and mucosal antibody production was significantly impaired only in TLR4-/- mice following Protollin-eRSV immunization. In contrast, an intact MyD88 pathway was crucial to elicit a balanced type 1:type 2 immune response, characterized by increased splenocyte production of antigen-induced IFNgamma and IL-10 with concomitant reduction of IL5, IgG2a isotype switching and abrogation of pulmonary eosinophil recruitment following challenge. MyD88-dependent signalling also contributed to neutrophil recruitment to the lungs following immunization with eRSV antigen, in the presence or absence of Protollin, compared to a mock antigen or vaccine. Both TLR4 and MyD88-signalling were required for optimal protection against challenge. The upregulation of early signalling molecules IFN-beta, TNFalpha, CD40 and CD86 were studied in splenocytes isolated from naïve TLR2, TLR4 and MyD88-/- mice following stimulation with vaccine components. Splenocytes from TLR4-/- mice displayed reduced IFN-beta while those of MyD88-/- mice elicited less TNFalpha and lower expression of CD40 and CD86 on CD11c+ cells. Together, our results suggest that optimal immunogenicity and protection against RSV without risk of enhanced pulmonary inflammation requires intact TLR4/MyD88-dependent signalling.
authors.affiliation: Research Institute of the McGill University Health Center, Montreal General Hospital, Montreal, Quebec, Canada H3G IA4. sonya.l.cyr@gskbio.com
authors.forename: Sonya L
authors.initials: SL
authors.lastname: Cyr
authors.forename: Isabelle
authors.initials: I
authors.lastname: Angers
authors.forename: Loic
authors.initials: L
authors.lastname: Guillot
authors.forename: Ioana
authors.initials: I
authors.lastname: Stoica-Popescu
authors.forename: Michèle
authors.initials: M
authors.lastname: Lussier
authors.forename: Salman
authors.initials: S
authors.lastname: Qureshi
authors.forename: David S
authors.initials: DS
authors.lastname: Burt
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Ward
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001425:Bacterial Outer Membrane Proteins / Q000494:pharmacology*; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D005260:Female; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008168:Lung / Q000276:immunology / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000172:deficiency / Q000276:immunology*; D009345:Neisseria meningitidis / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D018357:Respiratory Syncytial Virus Infections / Q000276:immunology / Q000517:prevention & control; D022261:Respiratory Syncytial Virus Vaccines / Q000276:immunology*; D012763:Shigella flexneri / Q000276:immunology; D013154:Spleen / Q000276:immunology; D051195:Toll-Like Receptor 2 / Q000172:deficiency / Q000276:immunology; D051197:Toll-Like Receptor 4 / Q000172:deficiency / Q000276:immunology*
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D001425:Bacterial Outer Membrane Proteins; D016207:Cytokines; D008070:Lipopolysaccharides; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; D022261:Respiratory Syncytial Virus Vaccines; C493486:Tlr2 protein, mouse; C493487:Tlr4 protein, mouse; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4