TLR4 mediates vaccine-induced protective cellular immunity to Bordetella pertussis: role of IL-17-producing T cells

SC Higgins, AG Jarnicki, EC Lavelle… - The Journal of …, 2006 - journals.aai.org
SC Higgins, AG Jarnicki, EC Lavelle, KHG Mills
The Journal of Immunology, 2006journals.aai.org
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) …
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-γ 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-1β, and TNF-α 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.
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