title: TLR4 mediates vaccine-induced protective cellular immunity to Bordetella pertussis: role of IL-17-producing T cells.
abstract: Whole cell pertussis vaccines (Pw) induce Th1 responses and protect against Bordetella pertussis infection, whereas pertussis acellular vaccines (Pa) induce Ab and Th2-biased responses and also protect against severe disease. In this study, we show that Pw failed to generate protective immunity in TLR4-defective C3H/HeJ mice. In contrast, protection induced with Pa was compromised, but not completely abrogated, in C3H/HeJ mice. Immunization with Pw, but not Pa, induced a population of IL-17-producing T cells (Th-17), as well as Th1 cells. Ag-specific IL-17 and IFN-gamma production was significantly lower in Pw-immunized TLR4-defective mice. Furthermore, treatment with neutralizing anti-IL-17 Ab immediately before and after B. pertussis challenge significantly reduced the protective efficacy of Pw. Stimulation of dendritic cells (DC) with Pw promoted IL-23, IL-12, IL-1beta, and TNF-alpha production, which was impaired in DC from TLR4-defective mice. B. pertussis LPS, which is present in high concentrations in Pw, induced IL-23 production by DC, which enhanced IL-17 secretion by T cells, but the induction of Th-17 cells was also dependent on IL-1. In addition, we identified a new effector function for IL-17, activating macrophage killing of B. pertussis, and this bactericidal activity was less efficient in macrophages from TLR4-defective mice. These data provide the first definitive evidence of a role for TLRs in protective immunity induced by a human vaccine. Our findings also demonstrate that activation of innate immune cells through TLR4 helps to direct the induction of Th1 and Th-17 cells, which mediate protective cellular immunity to B. pertussis.
authors.affiliation: Immune Regulation Research Group, School of Biochemistry and Immunology, Trinity College, Dublin 2, Ireland.
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Higgins
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Jarnicki
authors.forename: Ed C
authors.initials: EC
authors.lastname: Lavelle
authors.forename: Kingston H G
authors.initials: KH
authors.lastname: Mills
mesh_terms: D000818:Animals; D001886:Bordetella pertussis / Q000276:immunology; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology; D005434:Flow Cytometry; D007111:Immunity, Cellular; D020381:Interleukin-17 / Q000276:immunology*; D008262:Macrophage Activation / Q000276:immunology; D008264:Macrophages / Q000276:immunology; D051379:Mice; D010567:Pertussis Vaccine / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D051197:Toll-Like Receptor 4 / Q000276:immunology*; D022282:Vaccines, Acellular / Q000276:immunology
chemical_list: D016207:Cytokines; D020381:Interleukin-17; D010567:Pertussis Vaccine; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D022282:Vaccines, Acellular