CD4 T Cell-Derived IFN-γ Plays a Minimal Role in Control of Pulmonary Mycobacterium tuberculosis Infection and Must Be Actively Repressed by PD-1 to Prevent Lethal Disease

PLoS Pathog. 2016 May 31;12(5):e1005667. doi: 10.1371/journal.ppat.1005667. eCollection 2016 May.

Abstract

IFN-γ-producing CD4 T cells are required for protection against Mycobacterium tuberculosis (Mtb) infection, but the extent to which IFN-γ contributes to overall CD4 T cell-mediated protection remains unclear. Furthermore, it is not known if increasing IFN-γ production by CD4 T cells is desirable in Mtb infection. Here we show that IFN-γ accounts for only ~30% of CD4 T cell-dependent cumulative bacterial control in the lungs over the first six weeks of infection, but >80% of control in the spleen. Moreover, increasing the IFN-γ-producing capacity of CD4 T cells by ~2 fold exacerbates lung infection and leads to the early death of the host, despite enhancing control in the spleen. In addition, we show that the inhibitory receptor PD-1 facilitates host resistance to Mtb by preventing the detrimental over-production of IFN-γ by CD4 T cells. Specifically, PD-1 suppressed the parenchymal accumulation of and pathogenic IFN-γ production by the CXCR3+KLRG1-CX3CR1- subset of lung-homing CD4 T cells that otherwise mediates control of Mtb infection. Therefore, the primary role for T cell-derived IFN-γ in Mtb infection is at extra-pulmonary sites, and the host-protective subset of CD4 T cells requires negative regulation of IFN-γ production by PD-1 to prevent lethal immune-mediated pathology.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adoptive Transfer
  • Animals
  • Blotting, Western
  • CD4-Positive T-Lymphocytes / immunology*
  • Cytokines / analysis
  • Cytokines / biosynthesis
  • Disease Models, Animal
  • Enzyme-Linked Immunosorbent Assay
  • Flow Cytometry
  • Interferon-gamma / biosynthesis*
  • Interferon-gamma / immunology
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mycobacterium tuberculosis / immunology
  • Programmed Cell Death 1 Receptor / immunology
  • Programmed Cell Death 1 Receptor / metabolism*
  • Tuberculosis, Pulmonary / immunology*
  • Tuberculosis, Pulmonary / metabolism

Substances

  • Cytokines
  • Pdcd1 protein, mouse
  • Programmed Cell Death 1 Receptor
  • Interferon-gamma