The apicomplexan parasite Eimeria arloingi induces caprine neutrophil extracellular traps.
As a novel effector mechanism polymorphonuclear neutrophils (PMN) release neutrophil extracellular traps (NETs), which represent protein-labeled DNA matrices capable of extracellular trapping and killing of invasive pathogens. Here, we demonstrate for the first time NET formation performed by caprine PMN exposed to different stages (sporozoites and oocysts) of the goat apicomplexan protozoan parasite Eimeria arloingi. Scanning electron microscopy as well as fluorescence microscopy of sporozoites- and oocysts-PMN co-cultures revealed a fine network of DNA fibrils partially covering the parasites. Immunofluorescence analyses confirmed the co-localization of histones (H3), neutrophil elastase (NE), and myeloperoxidase (MPO) in extracellular traps released from caprine PMN. In addition, the enzymatic activity of NE was found significantly enhanced in sporozoite-exposed caprine PMN. The treatment of caprine NET structures with deoxyribonuclease (DNase) and the NADPH oxidase inhibitor diphenylene iodondium (DPI) significantly reduced NETosis confirming the classical characteristics of NETs. Caprine NETs efficiently trapped vital sporozoites of E. arloingi since 72% of these stages were immobilized-but not killed-in NET structures. As a consequence, early infection rates were significantly reduced when PMN-pre-exposed sporozoites were allowed to infect adequate host cells. These findings suggest that NETs may play an important role in the early innate host response to E. arloingi infection in goats.
ICAAM-Instituto Ciências Agrárias e Ambientais Mediterrânicas, IIFA/Universidade de Évora, Núcleo da Mitra, Apart 94, 7002-542, Évora, Portugal, lilianasilva.mv@gmail.com.
Liliana M R
LM
Silva
Tamara Muñoz
TM
Caro
Rüdiger
R
Gerstberger
Maria J M
MJ
Vila-Viçosa
Helder C E
HC
Cortes
Carlos
C
Hermosilla
Anja
A
Taubert
D000818:Animals; D002478:Cells, Cultured; D003048:Coccidiosis / Q000276:immunology / Q000662:veterinary*; D018920:Coculture Techniques; D004539:Eimeria / Q000472:pathogenicity*; D005110:Extracellular Space / Q000276:immunology; D015511:Goat Diseases / Q000276:immunology* / Q000469:parasitology; D006041:Goats / Q000469:parasitology; D006657:Histones / Q000276:immunology; D007113:Immunity, Innate; D019272:Leukocyte Elastase / Q000276:immunology / Q000378:metabolism; D008297:Male; D008855:Microscopy, Electron, Scanning; D019255:NADPH Oxidases / Q000378:metabolism; D018375:Neutrophil Activation; D009504:Neutrophils / Q000469:parasitology* / Q000648:ultrastructure; D033661:Oocysts; D009195:Peroxidase / Q000276:immunology / Q000378:metabolism; D034101:Sporozoites
D006657:Histones; D009195:Peroxidase; D019255:NADPH Oxidases; D019272:Leukocyte Elastase