A dendritic cell-based systemic vaccine induces long-lived lung-resident memory Th17 cells and ameliorates pulmonary mycosis

Abstract

Tissue-resident memory T cells (TRMs) are a novel nonvascular memory T cell subset. Although CD8 + TRMs are well-characterized, CD4 + TRMs-especially lung-resident memory Th17 cells-are still being defined. In this study, we characterized lung-resident memory Th17 cells (lung TRM17) and their role in protection against the highly virulent fungus Cryptococcus gattii. We found that intravenously transferred DCs preferentially migrated to lungs and attracted recipient DCs and led to the induction of long-lived Th17 cells expressing characteristic markers. This population could be clearly discriminated from circulating T cells by intravascular staining and was not depleted by the immunosuppressive agent FTY720. The C. gattii antigen re-stimulation assay revealed that vaccine-induced lung Th17 cells produced IL-17A but not IFNγ. The DC vaccine significantly increased IL-17A production and suppressed fungal burden in the lungs and improved the survival of mice infected with C. gattii. This protective effect was significantly reduced in the IL-17A knockout (KO) mice, but not in the FTY720-treated mice. The protective effect also coincided with the activation of neutrophils and multinucleated giant cells, and these inflammatory responses were suppressed in the vaccinated IL-17A KO mice. Overall, these data demonstrated that the systemic DC vaccine induced lung TRM17, which played a substantial role in anti-fungal immunity.Mucosal Immunology (2019) 12:265-276; https://doi.

Cryptococcus gattii alters immunostimulatory potential in response to the environment

“…Our recent study showed that DC-based vaccination induced lung resident memory Th17 cells, which influence the protective effects against highly virulent C . gattii infection [39]. In the DC vaccine, YPD medium-induced CAP60Δ was used as a vaccine antigen to prime BMDCs.…”

“…BMDCs were prepared as described previously [5,39]. In brief, bone marrow (BM) cells were harvested from the femurs and tibiae of C57BL/6J mice.…”

“…BMDC cytokine production was measured as described previously [5,39,42] In brief, BMDCs (2 × 10 5 cells/200 μL) were stimulated by heat-killed fungal cells in 96-well flat-bottom plates for 24 h. Culture supernatants were collected, and cytokine amounts were measured using enzyme-linked immunosorbent assay (ELISA). A MaxiSorp plate (Thermo Fisher Scientific), a BD OptEIA ELISA set for IL-6 (BD Bioscience), and a DuoSet ELISA kit for IL-23 (R&D Systems) were used according to the manufacturers’ instructions.…”

Vaccines and Protective Immune Memory against Cryptococcosis

“…Previous reviews described experimental antifungal vaccines in detail. 11,12) Several veterinary vaccines against dermatomycosis, including Insol Dermatophyton, Biocan-M, and RIVAC Mikroderm, are clinically available. 17,18) Although Cn: C. neoformans; Cg: C. gattii; HK: heat-killed; ND: not determined; ∆cna1: disruptant of gene coding calcineurin A1, avirulent temperature-sensitive mutant; ∆cda1/2/3: disruptant of three genes coding chitin deacetylase, chitosan-deficient avirulent strain; ∆sgl1: disruptant of gene coding sterylglucosidase-1, avirulent strain accumulating sterylglucosides; ∆cap59, ∆cap60: disruptant of capsule synthesis-related gene, acapsular mutant; ZNF2: gene coding the transcriptional factor, zinc finger protein (the overexpression strain forms hyphae in C. neoformans, and this strain strongly induced inflammatory response in the lungs after infection); ura5: mutant of orotidine monophosphate pyrophosphorylase which is uracil auxotrophic and can proliferate in medium containing 5-fluoroorotic acid (5-FOA) (wild-type cryptococcal cells used for immunization cannot grow in the medium and thus cryptococcal cells for immunization and challenge are distinguishable on plates containing 5-FOA); Th1: CD4 + helper T cells producing IFN-γ; Th17: CD4 + helper T cells producing IL-17A; μMT mice: B-cell deficient mice; DR4 mice: humanized mice expressing human HLA-DR4 (DRB*0401) and lacking endogenous mouse MHC class II; Aβ null mice: MHC class II-deficient mice in which CD4 + T cells are absent; Protection (+/−): +=immunization improved survival rates or reduced fungal burdens after challenge.…”

“…Previous studies developed many experimental vaccines and investigated vaccine-mediated protective immunity against cryptococcosis. 11,12) We also developed a dendritic cell (DC)-based vaccine against cryptococcosis caused by the highly virulent C. gattii. [13][14][15][16] We demonstrated that the DC vaccine improves the survival rate and ameliorates the fungal burden in the lungs after C. gattii infection and that lung resident-memory Th17 cells (lung TRM17) play a role in the vaccine-mediated protective effect.…”