[HTML][HTML] Mucosal delivery of a multistage subunit vaccine promotes development of lung-resident memory T cells and affords interleukin-17-dependent protection …

C Counoupas, KC Ferrell, A Ashhurst… - npj Vaccines, 2020 - nature.com
C Counoupas, KC Ferrell, A Ashhurst, ND Bhattacharyya, G Nagalingam, EL Stewart
npj Vaccines, 2020nature.com
The development of effective vaccines against bacterial lung infections requires the
induction of protective, pathogen-specific immune responses without deleterious
inflammation within the pulmonary environment. Here, we made use of a polysaccharide-
adjuvanted vaccine approach to elicit resident pulmonary T cells to protect against aerosol
Mycobacterium tuberculosis infection. Intratracheal administration of the multistage fusion
protein CysVac2 and the delta-inulin adjuvant Advax™(formulated with a TLR9 agonist) …
Abstract
The development of effective vaccines against bacterial lung infections requires the induction of protective, pathogen-specific immune responses without deleterious inflammation within the pulmonary environment. Here, we made use of a polysaccharide-adjuvanted vaccine approach to elicit resident pulmonary T cells to protect against aerosol Mycobacterium tuberculosis infection. Intratracheal administration of the multistage fusion protein CysVac2 and the delta-inulin adjuvant Advax™ (formulated with a TLR9 agonist) provided superior protection against aerosol M. tuberculosis infection in mice, compared to parenteral delivery. Surprisingly, removal of the TLR9 agonist did not impact vaccine protection despite a reduction in cytokine-secreting T cell subsets, particularly CD4+IFN-γ+IL-2+TNF+ multifunctional T cells. CysVac2/Advax-mediated protection was associated with the induction of lung-resident, antigen-specific memory CD4+ T cells that expressed IL-17 and RORγT, the master transcriptional regulator of Th17 differentiation. IL-17 was identified as a key mediator of vaccine efficacy, with blocking of IL-17 during M. tuberculosis challenge reducing phagocyte influx, suppressing priming of pathogen-specific CD4+ T cells in local lymph nodes and ablating vaccine-induced protection. These findings suggest that tuberculosis vaccines such as CysVac2/Advax that are capable of eliciting Th17 lung-resident memory T cells are promising candidates for progression to human trials.
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