Suppression of cell-mediated immunity following recognition of phagosome-confined bacteria

PLoS Pathog. 2009 Sep;5(9):e1000568. doi: 10.1371/journal.ppat.1000568. Epub 2009 Sep 4.

Abstract

Listeria monocytogenes is a facultative intracellular pathogen capable of inducing a robust cell-mediated immune response to sub-lethal infection. The capacity of L. monocytogenes to escape from the phagosome and enter the host cell cytosol is paramount for the induction of long-lived CD8 T cell-mediated protective immunity. Here, we show that the impaired T cell response to L. monocytogenes confined within a phagosome is not merely a consequence of inefficient antigen presentation, but is the result of direct suppression of the adaptive response. This suppression limited not only the adaptive response to vacuole-confined L. monocytogenes, but negated the response to bacteria within the cytosol. Co-infection with phagosome-confined and cytosolic L. monocytogenes prevented the generation of acquired immunity and limited expansion of antigen-specific T cells relative to the cytosolic L. monocytogenes strain alone. Bacteria confined to a phagosome suppressed the production of pro-inflammatory cytokines and led to the rapid MyD88-dependent production of IL-10. Blockade of the IL-10 receptor or the absence of MyD88 during primary infection restored protective immunity. Our studies demonstrate that the presence of microbes within a phagosome can directly impact the innate and adaptive immune response by antagonizing the signaling pathways necessary for inflammation and the generation of protective CD8 T cells.

Publication types

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

MeSH terms

  • Animals
  • CD4-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / immunology*
  • Cytokines / immunology
  • Cytokines / metabolism
  • Cytosol
  • Flow Cytometry
  • Host-Pathogen Interactions / immunology
  • Immunity, Cellular
  • Listeria monocytogenes / immunology*
  • Listeria monocytogenes / pathogenicity
  • Listeriosis / immunology*
  • Listeriosis / metabolism
  • Liver / cytology
  • Liver / immunology
  • Mice
  • Mice, Inbred C57BL
  • Myeloid Differentiation Factor 88 / biosynthesis
  • Myeloid Differentiation Factor 88 / immunology
  • Myeloid Differentiation Factor 88 / metabolism
  • Phagosomes / immunology*
  • Phagosomes / microbiology
  • Receptors, Interleukin-10 / antagonists & inhibitors
  • Receptors, Interleukin-10 / metabolism
  • Signal Transduction
  • Spleen / cytology
  • Spleen / immunology

Substances

  • Cytokines
  • Myd88 protein, mouse
  • Myeloid Differentiation Factor 88
  • Receptors, Interleukin-10