CXCR4 and MIF are required for neutrophil extracellular trap release triggered by Plasmodium-infected erythrocytes

PLoS Pathog. 2020 Aug 14;16(8):e1008230. doi: 10.1371/journal.ppat.1008230. eCollection 2020 Aug.

Abstract

Neutrophil extracellular traps (NETs) evolved as a unique effector mechanism contributing to resistance against infection that can also promote tissue damage in inflammatory conditions. Malaria infection can trigger NET release, but the mechanisms and consequences of NET formation in this context remain poorly characterized. Here we show that patients suffering from severe malaria had increased amounts of circulating DNA and increased neutrophil elastase (NE) levels in plasma. We used cultured erythrocytes and isolated human neutrophils to show that Plasmodium-infected red blood cells release macrophage migration inhibitory factor (MIF), which in turn caused NET formation by neutrophils in a mechanism dependent on the C-X-C chemokine receptor type 4 (CXCR4). NET production was dependent on histone citrullination by peptidyl arginine deiminase-4 (PAD4) and independent of reactive oxygen species (ROS), myeloperoxidase (MPO) or NE. In vitro, NETs functioned to restrain parasite dissemination in a mechanism dependent on MPO and NE activities. Finally, C57/B6 mice infected with P. berghei ANKA, a well-established model of cerebral malaria, presented high amounts of circulating DNA, while treatment with DNAse increased parasitemia and accelerated mortality, indicating a role for NETs in resistance against Plasmodium infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Erythrocytes / immunology*
  • Erythrocytes / metabolism
  • Erythrocytes / parasitology
  • Extracellular Traps / immunology*
  • Extracellular Traps / metabolism
  • Extracellular Traps / parasitology
  • Humans
  • Macrophage Migration-Inhibitory Factors / metabolism*
  • Malaria / immunology*
  • Malaria / metabolism
  • Malaria / parasitology
  • Malaria / pathology
  • Mice
  • Mice, Inbred C57BL
  • Neutrophils / immunology*
  • Neutrophils / metabolism
  • Neutrophils / parasitology
  • Parasitemia / immunology
  • Parasitemia / metabolism
  • Parasitemia / parasitology
  • Parasitemia / pathology
  • Plasmodium / immunology*
  • Receptors, CXCR4 / metabolism*

Substances

  • Macrophage Migration-Inhibitory Factors
  • Receptors, CXCR4

Grants and funding

This work was financially supported by Conselho Nacional de Pesquisa (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Fundação de Amparo à Pesquisa do Rio de Janeiro (FAPERJ). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.