Infection-adapted emergency hematopoiesis promotes visceral leishmaniasis

PLoS Pathog. 2017 Aug 7;13(8):e1006422. doi: 10.1371/journal.ppat.1006422. eCollection 2017 Aug.

Abstract

Cells of the immune system are derived from hematopoietic stem cells (HSCs) residing in the bone marrow. HSCs become activated in response to stress, such as acute infections, which adapt the bone marrow output to the needs of the immune response. However, the impact of infection-adapted HSC activation and differentiation on the persistence of chronic infections is poorly understood. We have examined here the bone marrow outcome of chronic visceral leishmaniasis and show that the parasite Leishmania donovani induces HSC expansion and skews their differentiation towards non-classical myeloid progenitors with a regulatory phenotype. Our results further suggest that emergency hematopoiesis contributes to the pathogenesis of visceral leishmaniasis, as decreased HSC expansion results in a lower parasite burden. Conversely, monocytes derived in the presence of soluble factors from the infected bone marrow environment are more permissive to infection by Leishmania. Our results demonstrate that L. donovani is able to subvert host bone marrow emergency responses to facilitate parasite persistence, and put forward hematopoiesis as a novel therapeutic target in chronic infections.

MeSH terms

  • Animals
  • Cell Differentiation / immunology*
  • Disease Models, Animal
  • Flow Cytometry
  • Hematopoiesis / immunology
  • Hematopoietic Stem Cells / immunology*
  • Hematopoietic Stem Cells / parasitology
  • Leishmaniasis, Visceral / immunology*
  • Mice
  • Mice, Inbred C57BL

Grants and funding

This work was supported by the Natural Sciences and Engineering Research Council of Canada (grant #419226-2012 to KMH) http://www.nserc-crsng.gc.ca, the Fonds de recherche du Québec – Santé (grant #32598 to KMH) http://www.frqs.gouv.qc.ca, Canadian Institutes of Health Research (grant #PJT-148614 to KMH and #MOP-123293 to SS) http://www.cihr-irsc.gc.ca, and the Canada Foundation for Innovation (CFI Leaders Fund #31377 to KMH & SS) https://www.innovation.ca. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.