Cytoadhesion to gC1qR through Plasmodium falciparum Erythrocyte Membrane Protein 1 in Severe Malaria

PLoS Pathog. 2016 Nov 11;12(11):e1006011. doi: 10.1371/journal.ppat.1006011. eCollection 2016 Nov.

Abstract

Cytoadhesion of Plasmodium falciparum infected erythrocytes to gC1qR has been associated with severe malaria, but the parasite ligand involved is currently unknown. To assess if binding to gC1qR is mediated through the P. falciparum erythrocyte membrane protein 1 (PfEMP1) family, we analyzed by static binding assays and qPCR the cytoadhesion and var gene transcriptional profile of 86 P. falciparum isolates from Mozambican children with severe and uncomplicated malaria, as well as of a P. falciparum 3D7 line selected for binding to gC1qR (Pf3D7gC1qR). Transcript levels of DC8 correlated positively with cytoadhesion to gC1qR (rho = 0.287, P = 0.007), were higher in isolates from children with severe anemia than with uncomplicated malaria, as well as in isolates from Europeans presenting a first episode of malaria (n = 21) than Mozambican adults (n = 25), and were associated with an increased IgG recognition of infected erythrocytes by flow cytometry. Pf3D7gC1qR overexpressed the DC8 type PFD0020c (5.3-fold transcript levels relative to Seryl-tRNA-synthetase gene) compared to the unselected line (0.001-fold). DBLβ12 from PFD0020c bound to gC1qR in ELISA-based binding assays and polyclonal antibodies against this domain were able to inhibit binding to gC1qR of Pf3D7gC1qR and four Mozambican P. falciparum isolates by 50%. Our results show that DC8-type PfEMP1s mediate binding to gC1qR through conserved surface epitopes in DBLβ12 domain which can be inhibited by strain-transcending functional antibodies. This study supports a key role for gC1qR in malaria-associated endovascular pathogenesis and suggests the feasibility of designing interventions against severe malaria targeting this specific interaction.

MeSH terms

  • Adult
  • Carrier Proteins / metabolism*
  • Child, Preschool
  • Enzyme-Linked Immunosorbent Assay
  • Erythrocytes / parasitology
  • Female
  • Flow Cytometry
  • Humans
  • Infant
  • Malaria, Falciparum / metabolism*
  • Male
  • Mitochondrial Proteins / metabolism*
  • Plasmodium falciparum
  • Protozoan Proteins / metabolism*

Substances

  • C1QBP protein, human
  • Carrier Proteins
  • Mitochondrial Proteins
  • Protozoan Proteins
  • erythrocyte membrane protein 1, Plasmodium falciparum

Grants and funding

This work was supported by the Instituto de Salud Carlos III (PI13/01478 cofunded by the Fondo Europeo de Desarrollo Regional [FEDER], CES10/021-I3SNS to AM and CP11/00269 from the Miguel Servet program to QB). The Manhiça Health Research Centre receives core support from the Spanish Agency for International Cooperation and Development. AM, JM and JG are supported by the Departament d’Universitats i Recerca de la Generalitat de Catalunya (AGAUR; grants 2014SGR26 and 2014SGR263). AMT received financial support from the Secretaría Nacional de Ciencia, Tecnología e Innovación (Instituto para la Formación y Aprovechamiento de los Recursos Humanos, República de Panamá) and BDLS from Estrategia de Sostenibilidad 2014–2015 CODI-Universidad de Antioquia, Colombia. TL and LT received support from Danish Council of Independent research, Lundbeck Foundation and University of Copenhagen. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.