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Neutrophil extracellular traps: casting the NET over pathogenesis

Department of Bacteriology, Swedish Institute for Infectious Disease Control Nobelsväg 18, SE-171 82 Solna, Solna, Sweden.
Current Opinion in Microbiology (Impact Factor: 7.22). 03/2007; 10(1):52-6. DOI: 10.1016/j.mib.2006.12.005
Source: PubMed

ABSTRACT Neutrophil extracellular traps (NETs) are considered to be part of the human innate immunity because they trap and kill pathogens. NETs are formed by activated neutrophils and consist of a DNA backbone with embedded antimicrobial peptides and enzymes. They are involved in host defense during pneumococcal pneumonia, streptococcal necrotizing fasciitis, appendicitis and insemination. Recently, bacterial virulence factors that counteract NETs have been identified. These include the degradation of the NET-backbone by DNases enabling the liberation of bacteria from NETs, as well as capsule formation, which reduces bacterial trapping. Furthermore, pathogens can resist NET-mediated killing by adding positive charge to their cell surface.

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    • "In this regard, exDNA has long been known in many biological secretions including bacterial biofilms, snail mucigels, and white human blood cell matrices where it localizes with a number of antimicrobial peptides and proteins (Fahy et al. 1993; Allesen-Holm et al. 2006). In the case of human neutrophils, such a complex called also the NET " neutrophil extracellular trap " is capable of protecting the cells against pathogens at the sites of infection (Wartha et al. 2007; Guimarães-Costa et al. 2009 "
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    • "In mammals, it is now well established that exDNA from blood cells such as neutrophils, eosinophils and mast cells plays a major role in defence against microbial pathogen invasion. Upon infection, exDNA with extracellular peptides and proteins forms a complex neutrophil extracellular trap called 'NET' that aggregates and kills the pathogens (Wartha et al., 2007; Medina, 2009). In peas, the digestion of exDNA from root border-cell exudate using enzymes such as DNase I results in loss of root tip resistance to N. haematococca infection (Wen et al., 2009). "
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