Type I IFNs drive hematopoietic stem and progenitor cell collapse via impaired proliferation and increased RIPK1-dependent cell death during shock-like ehrlichial infection

PLoS Pathog. 2018 Aug 6;14(8):e1007234. doi: 10.1371/journal.ppat.1007234. eCollection 2018 Aug.

Abstract

Type I interferons (IFNα/β) regulate diverse aspects of host defense, but their impact on hematopoietic stem and progenitor cells (HSC/HSPCs) during infection remains unclear. Hematologic impairment can occur in severe infections, thus we sought to investigate the impact of type I IFNs on hematopoiesis in a tick-borne infection with a virulent ehrlichial pathogen that causes shock-like disease. During infection, IFNα/β induced severe bone marrow (BM) loss, blunted infection-induced emergency myelopoiesis, and reduced phenotypic HSPCs and HSCs. In the absence of type I IFN signaling, BM and splenic hematopoiesis were increased, and HSCs derived from Ifnar1-deficient mice were functionally superior in competitive BM transplants. Type I IFNs impaired hematopoiesis during infection by both limiting HSC/HSPC proliferation and increasing HSPC death. Using mixed BM chimeras we determined that type I IFNs restricted proliferation indirectly, whereas HSPC death occurred via direct IFNαR -mediated signaling. IFNαR-dependent signals resulted in reduced caspase 8 expression and activity, and reduced cleavage of RIPK1 and RIPK3, relative to Ifnar1-deficient mice. RIPK1 antagonism with Necrostatin-1s rescued HSPC and HSC numbers during infection. Early antibiotic treatment is required for mouse survival, however antibiotic-treated survivors had severely reduced HSPCs and HSCs. Combination therapy with antibiotics and Necrostatin-1s improved HSPC and HSC numbers in surviving mice, compared to antibiotic treatment alone. We reveal two mechanisms whereby type I IFNs drive hematopoietic collapse during severe infection: direct sensitization of HSPCs to undergo cell death and enhanced HSC quiescence. Our studies reveal a strategy to ameliorate the type I IFN-dependent loss of HSCs and HSPCs during infection, which may be relevant to other infections wherein type I IFNs cause hematopoietic dysfunction.

Publication types

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

MeSH terms

  • Animals
  • Bone Marrow Cells / physiology
  • Cell Death / drug effects
  • Cell Death / genetics
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics
  • Cell Proliferation / drug effects
  • Cell Proliferation / genetics
  • Down-Regulation / genetics
  • Ehrlichia / pathogenicity
  • Ehrlichiosis / microbiology
  • Ehrlichiosis / pathology*
  • Female
  • Hematopoiesis / drug effects
  • Hematopoiesis / genetics
  • Hematopoietic Stem Cells / drug effects
  • Hematopoietic Stem Cells / physiology*
  • Interferon Type I / pharmacology
  • Interferon Type I / physiology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Transgenic
  • Receptor-Interacting Protein Serine-Threonine Kinases / genetics
  • Shock / genetics
  • Shock / microbiology
  • Shock / pathology*

Substances

  • Interferon Type I
  • Receptor-Interacting Protein Serine-Threonine Kinases
  • Ripk1 protein, mouse