title: Hemozoin activates the innate immune system and reduces Plasmodium berghei infection in Anopheles gambiae.
abstract: BACKGROUND
  Malaria is a worldwide infectious disease caused by Plasmodium parasites and transmitted by female Anopheles mosquitoes. The malaria vector mosquito Anopheles can trigger effective mechanisms to control completion of the Plasmodium lifecycle; the mosquito immune response to the parasite involves several pathways which are not yet well characterized. Plasmodium metabolite hemozoin has emerged as a potent immunostimulator of mammalian tissues. In this study, we aim to investigate the role of this parasite's by-product as stimulator of Anopheles gambiae immunity to Plasmodium berghei.
  
  
  METHODS
  Female mosquitoes were inoculated with hemozoin and the Plasmodium infection rate and intensity were measured. Differences between treatments were detected by Zero-inflated models. Microarray transcription analysis was performed to assess gene expression response to hemozoin. Genome-wide analysis results were confirmed by stimulation of Anopheles gambiae tissues and cells with hemozoin and silencing of REL2-F and its negative regulator Caspar.
  
  
  RESULTS
  Gene expression profiles revealed that hemozoin activates several immunity genes, including pattern recognition receptors (PRRs) and antimicrobial peptides (AMPs). Importantly, we found that the Immune deficiency (Imd) pathway Nuclear Factor-kappaB (NF-κB) transcription factor REL2, in its full-length form REL2-F, was induced upon hemozoin treatment.
  
  
  CONCLUSIONS
  We have for the first time shown the impact of hemozoin treatment in Plasmodium infection, reducing both rate and intensity of the infection. We propose that hemozoin boosts the innate immunity in Anopheles, activating key effector genes involved in mosquito resistance to Plasmodium, and this activation is REL2-mediated.
authors.affiliation: UEI Parasitologia Médica, Centro de Malária e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal. maria.luisa.simoes@ihmt.unl.pt.
authors.forename: Maria L
authors.initials: ML
authors.lastname: Simões
authors.affiliation: UEI Saúde Internacional e Bioestatística, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal. luziag@ihmt.unl.pt.|CEAUL, Centro de Estatística e Aplicações da Universidade de Lisboa, Lisboa, Portugal. luziag@ihmt.unl.pt.
authors.forename: Luzia
authors.initials: L
authors.lastname: Gonçalves
authors.affiliation: UEI Parasitologia Médica, Centro de Malária e Outras Doenças Tropicais, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal. hsilveira@ihmt.unl.pt.
authors.forename: Henrique
authors.initials: H
authors.lastname: Silveira
mesh_terms: D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D002460:Cell Line; D005260:Female; D005786:Gene Expression Regulation; D006420:Hemeproteins / Q000378:metabolism / Q000494:pharmacology*; D006790:Host-Parasite Interactions; D007113:Immunity, Innate / Q000502:physiology*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D010962:Plasmodium berghei / Q000502:physiology*; D040081:Protein Array Analysis
chemical_list: D006420:Hemeproteins; D019476:Insect Proteins; C020753:hemozoin