Intrinsic MyD88-Akt1-mTOR Signaling Coordinates Disparate Tc17 and Tc1 Responses during Vaccine Immunity against Fungal Pneumonia

PLoS Pathog. 2015 Sep 14;11(9):e1005161. doi: 10.1371/journal.ppat.1005161. eCollection 2015 Sep.

Abstract

Fungal infections have skyrocketed in immune-compromised patients lacking CD4+ T cells, underscoring the need for vaccine prevention. An understanding of the elements that promote vaccine immunity in this setting is essential. We previously demonstrated that vaccine-induced IL-17A+ CD8+ T cells (Tc17) are required for resistance against lethal fungal pneumonia in CD4+ T cell-deficient hosts, whereas the individual type I cytokines IFN-γ, TNF-α and GM-CSF, are dispensable. Here, we report that T cell-intrinsic MyD88 signals are crucial for these Tc17 cell responses and vaccine immunity against lethal fungal pneumonia in mice. In contrast, IFN-γ+ CD8+ cell (Tc1) responses are largely normal in the absence of intrinsic MyD88 signaling in CD8+ T cells. The poor accumulation of MyD88-deficient Tc17 cells was not linked to an early onset of contraction, nor to accelerated cell death or diminished expression of anti-apoptotic molecules Bcl-2 or Bcl-xL. Instead, intrinsic MyD88 was required to sustain the proliferation of Tc17 cells through the activation of mTOR via Akt1. Moreover, intrinsic IL-1R and TLR2, but not IL-18R, were required for MyD88 dependent Tc17 responses. Our data identify unappreciated targets for augmenting adaptive immunity against fungi. Our findings have implications for designing fungal vaccines and immune-based therapies in immune-compromised patients.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Blastomyces / immunology*
  • Blastomyces / physiology
  • Blastomycosis / immunology
  • Blastomycosis / metabolism
  • Blastomycosis / microbiology
  • Blastomycosis / prevention & control*
  • Cell Proliferation
  • Cells, Cultured
  • Fungal Vaccines / therapeutic use*
  • Immunologic Memory*
  • Lymphocyte Depletion
  • Mice
  • Mice, Congenic
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Myeloid Differentiation Factor 88 / metabolism
  • Pneumonia / immunology
  • Pneumonia / metabolism
  • Pneumonia / microbiology
  • Pneumonia / prevention & control*
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Interleukin-1 Type I / metabolism
  • Signal Transduction
  • T-Lymphocytes, Cytotoxic / immunology*
  • T-Lymphocytes, Cytotoxic / metabolism
  • T-Lymphocytes, Cytotoxic / microbiology
  • T-Lymphocytes, Cytotoxic / pathology
  • TOR Serine-Threonine Kinases / metabolism
  • Th17 Cells / immunology*
  • Th17 Cells / metabolism
  • Th17 Cells / microbiology
  • Th17 Cells / pathology
  • Toll-Like Receptor 2 / metabolism

Substances

  • Fungal Vaccines
  • IL1R1 protein, mouse
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • Receptors, Interleukin-1 Type I
  • Tlr2 protein, mouse
  • Toll-Like Receptor 2
  • mTOR protein, mouse
  • Akt1 protein, mouse
  • Proto-Oncogene Proteins c-akt
  • TOR Serine-Threonine Kinases