Treatment of mice with S4B6 IL-2 complex prevents lethal toxoplasmosis via IL-12- and IL-18-dependent interferon-gamma production by non-CD4 immune cells

Sci Rep. 2020 Aug 4;10(1):13115. doi: 10.1038/s41598-020-70102-1.

Abstract

Toxoplasmic encephalitis is an AIDS-defining condition. The decline of IFN-γ-producing CD4+ T cells in AIDS is a major contributing factor in reactivation of quiescent Toxoplasma gondii to an actively replicating stage of infection. Hence, it is important to characterize CD4-independent mechanisms that constrain acute T. gondii infection. We investigated the in vivo regulation of IFN-γ production by CD8+ T cells, DN T cells and NK cells in response to acute T. gondii infection. Our data show that processing of IFN-γ by these non-CD4 cells is dependent on both IL-12 and IL-18 and the secretion of bioactive IL-18 in response to T. gondii requires the sensing of viable parasites by multiple redundant inflammasome sensors in multiple hematopoietic cell types. Importantly, our results show that expansion of CD8+ T cells, DN T cells and NK cell by S4B6 IL-2 complex pre-treatment increases survival rates of mice infected with T. gondii and this is dependent on IL-12, IL-18 and IFN-γ. Increased survival is accompanied by reduced pathology but is independent of expansion of TReg cells or parasite burden. This provides evidence for a protective role of IL2C-mediated expansion of non-CD4 cells and may represent a promising lead to adjunct therapy for acute toxoplasmosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / parasitology
  • Inflammasomes / drug effects
  • Inflammasomes / metabolism
  • Interferon-gamma / biosynthesis*
  • Interleukin-12 / metabolism*
  • Interleukin-18 / metabolism*
  • Interleukin-2 / chemistry
  • Interleukin-2 / pharmacology*
  • Mice
  • Toxoplasma / drug effects
  • Toxoplasma / physiology
  • Toxoplasmosis / immunology*
  • Toxoplasmosis / metabolism
  • Toxoplasmosis / prevention & control*

Substances

  • Inflammasomes
  • Interleukin-18
  • Interleukin-2
  • Interleukin-12
  • Interferon-gamma