Histone deacetylase inhibitor MS-275 augments expression of a subset of IFN-γ-regulated genes in Toxoplasma gondii-infected macrophages but does not improve parasite control

Exp Parasitol. 2017 Sep;180:45-54. doi: 10.1016/j.exppara.2017.02.011. Epub 2017 Feb 9.

Abstract

Toxoplasma gondii is a ubiquitous apicomplexan parasite of mammals and birds and an important pathogen of humans. IFN-γ is the major mediator of host resistance against T. gondii but intriguingly, parasite-infected host cells including macrophages are severely impaired to respond to IFN-γ due to defective transcriptional activation of target genes. Here, we tested the possibility that the impaired responsiveness of T. gondii-infected macrophages to IFN-γ can be restored by inhibiting histone deacetylases (HDACs) using the class I-specific inhibitor MS-275. Treatment of RAW264.7 cells with MS-275 indeed increased MHC class II surface expression in infected and non-infected cells and largely abolished the inhibition of IFN-γ-regulated MHC class II expression exerted by T. gondii. Genome-wide transcriptome profiling revealed that MS-275 increased mean mRNA levels of IFN-γ-regulated genes particularly in non-infected macrophages. Transcript levels of 33% of IFN-γ secondary response genes but only those of a few primary response genes were also increased by MS-275 in T. gondii-infected cells. Importantly, the unresponsiveness of parasite-infected cells to IFN-γ was however not abolished by MS-275. Furthermore, MS-275 also up-regulated several anti-inflammatory cytokines or signaling molecules in T. gondii-infected macrophages. It additionally regulated expression of more than 2500 genes in non-infected macrophages expression of which was surprisingly counteracted by prior infection with T. gondii. FACS analysis and immunofluorescence microscopy revealed that MS-275 did not considerably diminish the number of parasite-positive cells or the intracellular replication in macrophages stimulated or not with IFN-γ. Thus, a supportive therapy using MS-275 appears inappropriate for treatment of toxoplasmosis.

Keywords: Histone deacetylase; Immune evasion; Interferon-gamma; MS-275; Supportive therapy; Toxoplasma gondii.

MeSH terms

  • Animals
  • Benzamides / pharmacology*
  • Flow Cytometry
  • Gene Expression / drug effects*
  • Genes, MHC Class II / drug effects
  • Histone Deacetylase Inhibitors / pharmacology*
  • Histone Deacetylases / drug effects
  • Interferon-gamma / genetics*
  • Interferon-gamma / physiology
  • Macrophages / drug effects*
  • Macrophages / immunology
  • Macrophages / parasitology
  • Mice
  • Microscopy, Fluorescence
  • Pyridines / pharmacology*
  • RAW 264.7 Cells
  • RNA, Protozoan / chemistry
  • RNA, Protozoan / isolation & purification
  • Toxoplasma / drug effects*
  • Toxoplasma / genetics
  • Toxoplasma / immunology

Substances

  • Benzamides
  • Histone Deacetylase Inhibitors
  • Pyridines
  • RNA, Protozoan
  • entinostat
  • Interferon-gamma
  • Histone Deacetylases