Neutrophil extracellular traps in the intestinal mucosa of Eimeria-infected animals

To investigate the presence of neutrophil extracellular traps (NETs) in vivo by analysing intestinal sections from experimentally Eimeria bovis- and naturally Eimeria arloingi-infected animals. Intestinal samples of Eimeria arloingi- and Eimeria bovis-infected animals were analysed by using immunohistochemical and fluorescence approach by using monoclonal antibodies. Classical NET components were confirmed by co-localization of extracellular DNA being decorated with neutrophil elastase and histones in Eimeria-infected tissue samples. Here, extrusion of NETs was exclusively detected in intestinal polymorphonuclear neutrophils infiltrating Eimeria-infected sites. In vivo NETs were either found in close proximity or in direct contact to different Eimeria stages suggesting a stage-independent process. NETs were also found within the gut lumen driven by polymorphonuclear neutrophils that were contacting released oocysts. We postulate that NETs might play an important role in innate defence reactions in coccidiosis therefore significantly altering the outcome of infection.