Leishmania donovaniPromastigotes Evade the Antimicrobial Activity of Neutrophil Extracellular Traps

AbstractChronic granulomatous disease (CGD) patients have impaired nicotinamide adenine dinucleotide phosphate (NADPH) oxidase function, resulting in poor antimicrobial activity of neutrophils, including the inability to generate neutrophil extracellular traps (NETs). Invasive aspergillosis is the leading cause of death in patients with CGD; it is unclear how neutrophils control Aspergillus species in healthy persons. The aim of this study was to determine whether gene therapy restores NET formation in CGD by complementation of NADPH oxidase function, and whether NETs have antimicrobial activity against Aspergillus nidulans. Here we show that reconstitution of NET formation by gene therapy in a patient with CGD restores neutrophil elimination of A nidulans conidia and hyphae and is associated with rapid cure of preexisting therapy refractory invasive pulmonary aspergillosis, underlining the role of functional NADPH oxidase in NET formation and antifungal activity.

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Secreted Phosphatase and Deoxyribonuclease Are Required by Pseudomonas aeruginosa To Defend against Neutrophil Extracellular Traps

Infection and Immunity ◽

10.1128/iai.00403-18 ◽

2018 ◽

Vol 86 (9) ◽

Cited By ~ 8

Author(s):

Mike Wilton ◽

Tyler W. R. Halverson ◽

Laetitia Charron-Mazenod ◽

Michael D. Parkins ◽

Shawn Lewenza

Keyword(s):

Pseudomonas Aeruginosa ◽

Antimicrobial Activity ◽

Alkaline Phosphatase ◽

Defense Mechanism ◽

Neutrophil Extracellular Traps ◽

Immune Defense ◽

Extracellular Dna ◽

Protective Function ◽

Content Type ◽

Extracellular Traps

ABSTRACT Neutrophil extracellular traps (NETs) are produced by neutrophils as an innate immune defense mechanism to trap and kill microbial pathogens. NETs are comprised of ejected chromatin that forms a lattice structure enmeshed with numerous antimicrobial proteins. In addition to forming the structural backbone of NETs, extracellular DNA (eDNA) has membrane-disrupting antimicrobial activity that contributes to NET killing. Many pathogens produce secreted extracellular DNases to evade the antimicrobial activity of NETs. Pseudomonas aeruginosa encodes an operon of two secreted enzymes, a predicted alkaline phosphatase and a DNase. The DNase (eddB) degrades eDNA to use as a nutrient source. Here we report that both eDNA and NETs are potent inducers of this DNase-phosphatase operon. Furthermore, the secreted DNase contributes to degrading NET DNA and defends P. aeruginosa against NET-mediated killing. We demonstrate that EddA has both alkaline phosphatase and phosphodiesterase (PDase) activities and also protects against the antimicrobial activity of NETs. Although the phosphatase does not cause DNA degradation similar to that of the DNase, its protective function is likely a result of removing the cation-chelating phosphates from the eDNA phosphodiester backbone. Therefore, both the DNase and PDase contribute to defense against NET killing of P. aeruginosa, highlighting the role of DNA-manipulating enzymes in targeting the eDNA in neutrophil extracellular traps.

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Streptococcus suis DNase SsnA contributes to degradation of neutrophil extracellular traps (NETs) and evasion of NET-mediated antimicrobial activity

Microbiology ◽

10.1099/mic.0.072199-0 ◽

2014 ◽

Vol 160 (2) ◽

pp. 385-395 ◽

Cited By ~ 70

Author(s):

Nicole de Buhr ◽

Ariane Neumann ◽

Natalja Jerjomiceva ◽

Maren von Köckritz-Blickwede ◽

Christoph G. Baums

Keyword(s):

Antimicrobial Activity ◽

Streptococcus Suis ◽

Neutrophil Extracellular Traps ◽

Human Neutrophils ◽

Myristate Acetate ◽

Phenotypic Differences ◽

Extracellular Traps ◽

Partial Release ◽

Over Time

Streptococcus suis is an important cause of different pathologies in pigs and humans, most importantly fibrinosuppurative meningitis. Tissue infected with this pathogen is substantially infiltrated with neutrophils, but the function of neutrophil extracellular traps (NETs) - a more recently discovered antimicrobial strategy of neutrophils - in host defence against Strep. suis has not been investigated. The objective of this work was to investigate the interaction of Strep. suis with NETs in vitro. Strep. suis induced NET formation in porcine neutrophils and was entrapped but not killed by those NETs. As the amount of NETs decreased over time, we hypothesized that a known extracellular DNase of Strep. suis degrades NETs. Though this nuclease was originally designated Strep. suis-secreted nuclease A (SsnA), this work demonstrated surface association in accordance with an LPXTG cell wall anchor motif and partial release into the supernatant. Confirming our hypothesis, an isogenic ssnA mutant was significantly attenuated in NET degradation and in protection against the antimicrobial activity of NETs as determined in assays with phorbol myristate acetate (PMA)-stimulated human neutrophils. Though assays with PMA-stimulated porcine neutrophils suggested that SsnA also degrades porcine NETs, phenotypic differences between wt and the isogenic ssnA mutant were less distinct. As SsnA expression was crucial for neither growth in vitro nor for survival in porcine or human blood, the results indicated that SsnA is the first specific NET evasion factor to be identified in Strep. suis.

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Antimicrobial Activity of Neutrophils Against Mycobacteria

Frontiers in Immunology ◽

10.3389/fimmu.2021.782495 ◽

2021 ◽

Vol 12 ◽

Author(s):

Heather A. Parker ◽

Lorna Forrester ◽

Christopher D. Kaldor ◽

Nina Dickerhof ◽

Mark B. Hampton

Keyword(s):

Antimicrobial Activity ◽

Hypochlorous Acid ◽

Mycobacterial Infection ◽

Neutrophil Extracellular Traps ◽

Resistance Mechanisms ◽

Host Cells ◽

Bacterial Clearance ◽

Human Pathogens ◽

Extracellular Traps ◽

Reactive Oxidants

The mycobacterium genus contains a broad range of species, including the human pathogens M. tuberculosis and M. leprae. These bacteria are best known for their residence inside host cells. Neutrophils are frequently observed at sites of mycobacterial infection, but their role in clearance is not well understood. In this review, we discuss how neutrophils attempt to control mycobacterial infections, either through the ingestion of bacteria into intracellular phagosomes, or the release of neutrophil extracellular traps (NETs). Despite their powerful antimicrobial activity, including the production of reactive oxidants such as hypochlorous acid, neutrophils appear ineffective in killing pathogenic mycobacteria. We explore mycobacterial resistance mechanisms, and how thwarting neutrophil action exacerbates disease pathology. A better understanding of how mycobacteria protect themselves from neutrophils will aid the development of novel strategies that facilitate bacterial clearance and limit host tissue damage.

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