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Updated: Jul 17, 2025
Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat
Published on: October 29, 2014
Cryptosporidium parvum-induced neutrophil extracellular traps in neonatal calves is a stage-independent process
Magdalena Grabbe1, Iván Conejeros1, Zahady D Velásquez1
1Institute of Parasitology, Biomedical Center Seltersberg (BFS), Justus Liebig University Giessen, Giessen, Germany.
Introduction:
Infections with the apicomplexan obligate intracellular parasite Cryptosporidium parvum lead to cryptosporidiosis-a worldwide zoonotic infection. C. parvum is one of the most common diarrheal pathogens in young calves, which are the main reservoir of the pathogen. Cryptosporidiosis leads to severe economic losses in the calf industry and being a major contributor to diarrhea morbidity and mortality in children. Polymorphonuclear neutrophils (PMN) are part of the innate immune system. Their effector mechanisms directed against invasive parasites include phagocytosis, production of antimicrobial molecules as well as the formation of so-called neutrophil extracellular traps (NETs). Like other leukocytes of the innate immune system, PMN are thus able to release chromatin fibers enriched with antimicrobial granular molecules extracellularly thereby immobilizing and partially killing invasive bacteria, viruses, fungi and parasites.
Methods:
In vitro interactions of neonatal bovine PMN and C. parvum-oocysts and sporozoites were illustrated microscopically via scanning electron microscopy- and live cell imaging 3D holotomographic microscopy analyses. C. parvum-triggered NETosis was quantified via extracellular DNA measurements as well as verified via detection of NET-typical molecules [histones, neutrophil elastase (NE)] through immunofluorescence microscopy analysis. To verify the role of ATP in neonatal-derived NETosis, inhibition experiments were performed with NF449 (purinergic receptor antagonist with high specificity to P2X1 receptor).
Results And Discussion:
Using immunofluorescence- and SEM-based analyses, we demonstrate here for the first time that neonate bovine PMN are capable of forming NETs against C. parvum-sporozoites and oocysts, thus as a stage-independent cell death process. Our data further showed that C. parvum strongly induces suicidal neonatal NETosis in a P2X1-dependent manner, suggesting anti-cryptosporidial effects not only through firm sporozoite ensnarement and hampered sporozoite excystation, but also via direct exposure to NETs-associated toxic components.
Insights
Neonatal bovine neutrophils form neutrophil extracellular traps (NETs) against Cryptosporidium parvum, a parasite causing significant calf and human illness. This process, dependent on P2X1 receptors, helps combat infection by trapping and potentially killing the parasite.
Area of Science:
- Veterinary Immunology
- Parasitology
- Innate Immunity
Background:
- Cryptosporidium parvum is a major cause of diarrhea in calves and children, leading to economic losses and health issues.
- Polymorphonuclear neutrophils (PMN) are key innate immune cells that combat pathogens using mechanisms like neutrophil extracellular traps (NETs).
Purpose of the Study:
- To investigate the interaction between neonatal bovine PMN and Cryptosporidium parvum.
- To determine if bovine PMN can form NETs against C. parvum and the underlying mechanisms.
Main Methods:
- In vitro analysis of PMN and C. parvum oocysts/sporozoites using scanning electron microscopy and 3D holotomographic microscopy.
- Quantification of NETosis via extracellular DNA and NET-specific molecules (histones, neutrophil elastase).
- Inhibition experiments using NF449 to assess the role of P2X1 receptors in NETosis.
Main Results:
- Neonatal bovine PMN form stage-independent NETs against C. parvum oocysts and sporozoites.
- C. parvum strongly induces NETosis in a P2X1 receptor-dependent manner.
- NET formation ensnares sporozoites, hinders excystation, and exposes them to toxic NET components.
Conclusions:
- Bovine PMN-derived NETs represent a crucial innate immune defense against C. parvum infection.
- Targeting the P2X1 receptor pathway may offer a novel therapeutic strategy against cryptosporidiosis.
