scholarly journals Capsular polysaccharides from Cryptococcus neoformans modulate production of neutrophil extracellular traps (NETs) by human neutrophils

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Juliana D. B. Rocha ◽  
Michelle T. C. Nascimento ◽  
Debora Decote-Ricardo ◽  
Suzana Côrte-Real ◽  
Alexandre Morrot ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Neutrophil Extracellular Traps ◽  
Human Neutrophils ◽  
Capsular Polysaccharides ◽  
Extracellular Traps

scholarly journals Silver Nanoparticles Induce Neutrophil Extracellular Traps Via Activation of PAD and Neutrophil Elastase

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 317
Author(s):  
HanGoo Kang ◽  
Jinwon Seo ◽  
Eun-Jeong Yang ◽  
In-Hong Choi
Keyword(s):  
Silver Nanoparticles ◽  
Neutrophil Elastase ◽  
Mammalian Cells ◽  
Antimicrobial Properties ◽  
Neutrophil Extracellular Traps ◽  
Arginine Deiminase ◽  
Human Neutrophils ◽  
Extracellular Traps ◽  
Peptidyl Arginine Deiminase ◽  
Key Factor

Silver nanoparticles (AgNPs) are widely used in various fields because of their antimicrobial properties. However, many studies have reported that AgNPs can be harmful to both microorganisms and humans. Reactive oxygen species (ROS) are a key factor of cytotoxicity of AgNPs in mammalian cells and an important factor in the immune reaction of neutrophils. The immune reactions of neutrophils include the expulsion of webs of DNA surrounded by histones and granular proteins. These webs of DNA are termed neutrophil extracellular traps (NETs). NETs allow neutrophils to catch and destroy pathogens in extracellular spaces. In this study, we investigated how AgNPs stimulate neutrophils, specifically focusing on NETs. Freshly isolated human neutrophils were treated with 5 or 100 nm AgNPs. The 5 nm AgNPs induced NET formation, but the 100 nm AgNPs did not. Subsequently, we investigated the mechanism of AgNP-induced NETs using known inhibitors related to NET formation. AgNP-induced NETs were dependent on ROS, peptidyl arginine deiminase, and neutrophil elastase. The result in this study indicates that treatment of 5 nm AgNPs induce NET formation through histone citrullination by peptidyl arginine deiminase and histone cleavage by neutrophil elastase.

Exosomal MALAT1 derived from ox-LDL-treated endothelial cells induce neutrophil extracellular traps to aggravate atherosclerosis

2020 ◽  
Vol 401 (3) ◽  
pp. 367-376 ◽  
Author(s):  
Hailai Gao ◽  
XiaoLi Wang ◽  
Chaolan Lin ◽  
Zhujun An ◽  
Jiangbo Yu ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Umbilical Vein ◽  
Low Density Lipoprotein ◽  
Atherosclerotic Lesion ◽  
Density Lipoprotein ◽  
Neutrophil Extracellular Traps ◽  
Human Neutrophils ◽  
Enzyme Linked Immunosorbent Assay ◽  
Extracellular Traps ◽  
Umbilical Vein Endothelial Cells

AbstractThe objective of this study was to reveal a novel mechanism underlying the progression of atherosclerosis (AS) associated with endothelial cells (ECs) and neutrophils. Transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) were used to observe the morphology and particle size of isolated exosomes. Western blotting was applied to examine exosomal markers, while the expression of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The production of inflammatory cytokines and reactive oxygen species (ROS) was determined by an enzyme-linked immunosorbent assay (ELISA) and a dichloro-dihydro-fluorescein diacetate (DCFH-DA) assay. Circulating neutrophil extracellular traps (NETs) were represented by myeloperoxidase (MPO)-DNA complexes. NETs formation was assessed using immunofluorescence microscopy. Atherosclerotic lesion development was measured by Oil Red O (ORO) staining. In the results, MALAT1 expression was increased in exosomes extracted from oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs). When co-cultured with human neutrophils, exosomes derived from ox-LDL-treated HUVECs were revealed to promote NETs formation, which was mediated by exosomal MALAT1. Furthermore, ox-LDL-treated HUVECs-derived exosomes were demonstrated to trigger hyperlipidemia, inflammatory response and NETs release in a mouse model of AS. In conclusion, exosomal MALAT1 derived from ox-LDL-treated ECs initiated NETs formation, which in turn deteriorated AS.

scholarly journals Nitric oxide and peroxynitrite trigger and enhance release of neutrophil extracellular traps

2019 ◽  
Vol 77 (15) ◽  
pp. 3059-3075 ◽  
Author(s):  
Aneta Manda-Handzlik ◽  
Weronika Bystrzycka ◽  
Adrianna Cieloch ◽  
Eliza Glodkowska-Mrowka ◽  
Ewa Jankowska-Steifer ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitrosative Stress ◽  
Calcium Ionophore ◽  
Neutrophil Extracellular Traps ◽  
Calcium Ionophore A23187 ◽  
Human Neutrophils ◽  
Ionophore A23187 ◽  
Inflammatory Reactions ◽  
Extracellular Traps

Abstract Despite great interest, the mechanism of neutrophil extracellular traps (NETs) release is not fully understood and some aspects of this process, e.g. the role of reactive nitrogen species (RNS), still remain unclear. Therefore, our aim was to investigate the mechanisms underlying RNS-induced formation of NETs and contribution of RNS to NETs release triggered by various physiological and synthetic stimuli. The involvement of RNS in NETs formation was studied in primary human neutrophils and differentiated human promyelocytic leukemia cells (HL-60 cells). RNS (peroxynitrite and nitric oxide) efficiently induced NETs release and potentiated NETs-inducing properties of platelet activating factor and lipopolysaccharide. RNS-induced NETs formation was independent of autophagy and histone citrullination, but dependent on the activity of phosphoinositide 3-kinases (PI3K) and myeloperoxidase, as well as selective degradation of histones H2A and H2B by neutrophil elastase. Additionally, NADPH oxidase activity was required to release NETs upon stimulation with NO, as shown in NADPH-deficient neutrophils isolated from patients with chronic granulomatous disease. The role of RNS was further supported by increased RNS synthesis upon stimulation of NETs release with phorbol 12-myristate 13-acetate and calcium ionophore A23187. Scavenging or inhibition of RNS formation diminished NETs release triggered by these stimuli while scavenging of peroxynitrite inhibited NO-induced NETs formation. Our data suggest that RNS may act as mediators and inducers of NETs release. These processes are PI3K-dependent and ROS-dependent. Since inflammatory reactions are often accompanied by nitrosative stress and NETs formation, our studies shed a new light on possible mechanisms engaged in various immune-mediated conditions.

Neutrophil Extracellular Traps Induce Platelet Adhesion and Thrombus Formation.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1345-1345 ◽  
Author(s):  
Tobias Fuchs ◽  
Alexander Brill ◽  
Daniel Dürschmied ◽  
Daphne Schatzberg ◽  
John H. Hartwig ◽  
...  
Keyword(s):  
Whole Blood ◽  
Platelet Adhesion ◽  
Conflicts Of Interest ◽  
Thrombus Formation ◽  
Neutrophil Extracellular Traps ◽  
Thrombin Inhibitor ◽  
Human Neutrophils ◽  
Dependent Manner ◽  
Extracellular Traps ◽  
Deep Vein

Abstract Abstract 1345 Introduction Thrombus stability is provided by very large polymers adhering to platelets and anchoring the thrombus to the vessel wall. The best described polymers are fibrin and von Willebrand Factor (VWF). Activated neutrophils and other leukocytes can form an extracellular fibrous network which is composed of DNA, histones, and granular proteins. These neutrophil extracellular traps (NETs) are present in various inflammatory diseases. In deep vein thrombosis (DVT) inflammation closely cooperates with thrombosis. Here we examine whether NETs provide a new means to support the adhesion and recruitment of platelets and whether NETs are present in DVT. Methods and Results: To study the interaction of platelets with NETs, we isolated human neutrophils, induced NET formation and perfused over the NETs human platelets in plasma or whole blood anticoagulated with the thrombin inhibitor PPACK. Microscopic analysis revealed that under flow platelets adhere avidly to NETs. Perfusion of whole blood at physiological shear resulted in formation of thrombi on NETs in a time dependent manner. Addition of DNase1 degraded NETs and removed all platelets and thrombi demonstrating their adhesion to NETs. Thrombus formation on NETs was absent if blood was supplemented with EDTA indicating the requirement for divalent cations. Perfusion of NETs with heparinized blood dismantled NETs and prevented thrombus formation. Incubation of NETs with heparin alone released histones from NETs, indicating that heparin destroys the chromatin backbone of NETs. Furthermore, immunocytochemistry revealed that NETs were able to bind platelet adhesion molecules VWF and fibronectin from human plasma. Immunohistochemical analysis of a baboon deep vein thrombus showed abundant extracellular chromatin which co-localized with fibronectin and VWF. Conclusions: We show that extracellular traps are able to promote thrombosis in vitro and are abundant in vivo in DVT. We propose that extracellular chromatin provides a new type of scaffold that promotes platelet adhesion, activation, and aggregation and may be important for thrombus initiation or stability. Disclosures No relevant conflicts of interest to declare.

Cisplatin Fails To Stimulate Production Of Reactive Oxygen Species and Release Of Neutrophil Extracellular Traps By Human Neutrophils In Vitro

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4714-4714
Author(s):  
Leonardo Pasalic ◽  
Campbell Heather ◽  
Shane Thomas ◽  
Vivien M Chen
Keyword(s):  
Reactive Oxygen Species ◽  
Fluorescent Microscopy ◽  
Neutrophil Extracellular Traps ◽  
Vehicle Control ◽  
Human Neutrophils ◽  
Oxygen Species ◽  
Extracellular Traps ◽  
Spontaneous Production ◽  
Confocal Fluorescent Microscopy

Background Cisplatin is a commonly used antineoplastic agent for treatment of a broad range of cancers. Cisplatin-based treatment has been associated with a significant risk of venous thromboembolism. The mechanisms through which cisplatin contributes to a prothrombotic state remain unclear. Neutrophil extracellular traps (NETs) consist of web-like DNA–histone core decorated with granule proteins and are released from activated neutrophils in a process dependent on reactive oxygen species (ROS), in particular hypochlorous acid (HOCl). Recently, NETs have been shown to play an important role in initiation and propagation of venous thrombus in a number of animal models of deep vein thrombosis. The aim of this study was to investigate whether NETs may provide a potential link between cisplatin and venous thromboembolism. Methods and Results To assess the effect of cisplatin on release of NETs by ex vivo human neutrophils isolated by positive immunomagnetic selection we visualised NETs release by confocal fluorescent microscopy and performed fluorimetric quantification of cell-free DNA (CFDNA) using either SYTOX Green nucleic acid stain (10 µM) or an ultrasensitive fluorescent assay Picogreen Quant IT (Invitrogen). In contrast to stimulation with phorbol 12-myristate 13-acetate (PMA) (25 nM),which resulted in 22 ng/104neutrophils of detectable CFDNA, neither of these two assays could detect any significant release of CFDNA by human neutrophils exposed to cisplatin (15 µM) for 2 or 4 hours above baseline similar with vehicle control. Furthermore, confocal fluorescent microscopy imaging of neutrophils stained with non-cell permeable DNA dye SYTOX Red (Invitrogen) demonstrated no difference in NET formation between control and cisplatin treated human neutrophils. Thus we could not demonstrate that NETS are produced in response to cisplatin treatment. In view of consistent reports that NET formation is ROS dependent we decided to investigate whether cisplatin exposure leads to production of ROS by human neutrophils. Few published studies into the effects of cisplatin on the production of ROS by human neutrophils in vitro offer conflicting results. We used flow cytometry and fluorescent probe hydroethidine (HE) for detection of intercellular superoxide anion radical in HL60 granulocytic cells in the presence of cisplatin (up to 50 µM). Differentiation down the granulocytic lineage after stimulation with ATRA was confirmed by light microscopy and by flow cytometry. Capacity of differentiated HL60 cells to generate NET formation after PMA stimulation was confirmed by fluorescence microscopy. Cisplatin failed to augment the spontaneous production of ROS by ATRA differentiated HL60 cells. The number of viable ethidium-high cells in cisplatin treated group did not differ from the vehicle control indicating no detectable production of ROS in response to cisplatin. In contrast, positive control treatment with PMA (25 nM) and menadione (40 µM) resulted in 4- and 20-fold increase in viable ethidium-high population respectively. ROS generation by human neutrophils was measured by a colorimetric assay for chlorination of extracellular taurine to determine if exposure to cisplatin results in the production of HOCl by human neutrophils in vitro. Treatment of resting neutrophils with cisplatin (15 µM) for 30 min or 120 min was not associated with an increase in the spontaneous production of HOCl above the baseline. Furthermore, the PMA (25 nM)-activated generation of HOCl production was not increased by pre-treating neutrophils with cisplatin indicating that there was no potentiation of ROS by pre-treatment with cisplatin. Discussion and Conclusion Our results suggest that cisplatin fails to induce release of NETs or HOCl from human neutrophils in vitro. These negative findings seem to be at odds with the well described pro-oxidative actions of cisplatin. One possible explanation centres on reported findings that the pro-oxidative effects of cisplatin are dependent on the mitochondrial generation of ROS whilst the mitochondria-generated ROS appear not to be instrumental to NET formation. Therefore, we postulate that cisplatin may not be able to induce NET formation by human neutrophils, which are known to contain few mitochondria, due to a sub-threshold ROS signal. Therefore it appears that cisplatin-associated increased risk of venous thrombosis is unlikely to be mediated through NETs. Disclosures: No relevant conflicts of interest to declare.

Effect of cell-free ascites containing mitochondrial DNA (mtDNA) from ovarian cancer (OC) patients on human neutrophils and neutrophil extracellular traps (NETs).

2014 ◽  
Vol 32 (15_suppl) ◽  
pp. e22087-e22087
Author(s):  
Kassondra S. Grzankowski ◽  
Anm Nazmul H. Khan ◽  
Melissa Grimm ◽  
Bonnie Hylander ◽  
Kelly L. Singel ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Mitochondrial Dna ◽  
Neutrophil Extracellular Traps ◽  
Human Neutrophils ◽  
Extracellular Traps

scholarly journals Extracellular Nucleic Acids Present in the Candida albicans Biofilm Trigger the Release of Neutrophil Extracellular Traps

2021 ◽  
Vol 11 ◽  
Author(s):  
Magdalena Smolarz ◽  
Marcin Zawrotniak ◽  
Dorota Satala ◽  
Maria Rapala-Kozik
Keyword(s):  
Candida Albicans ◽  
Nucleic Acids ◽  
Fungal Infection ◽  
Fungal Infections ◽  
Neutrophil Extracellular Traps ◽  
Human Neutrophils ◽  
High Concentration ◽  
First Line ◽  
Extracellular Traps ◽  
Biofilm Structure

Neutrophils, the first line of the host’s defense, use a variety of antimicrobial mechanisms to fight invading pathogens. One of the most crucial is the production of neutrophil extracellular traps (NETs) in the process called NETosis. The unique structure of NETs effectively inhibits the spread of pathogens and ensures their exposure to a high concentration of NET-embedded antimicrobial compounds. NETosis strategy is often used by the host to defend against fungal infection caused by Candida albicans. In immunocompromised patients, this microorganism is responsible for developing systemic fungal infections (candidiasis). This is correlated with the use of a vast array of virulence factors, leading to the acquisition of specific resistance to host defense factors and available drug therapies. One of the most important features favoring the development of drug resistance is a C. albicans ability to form biofilms that protect fungal cells mainly through the production of an extracellular matrix (ECM). Among the main ECM-building macromolecules extracellular nucleic acids have been identified and their role is probably associated with the stbilization of the biofilm structure. The complex interactions of immune cells with the thick ECM layer, comprising the first line of contact between these cells and the biofilm structure, are still poorly understood. Therefore, the current studies aimed to assess the release of extracellular nucleic acids by C. albicans strains at different stages of biofilm formation, and to determine the role of these molecules in triggering the NETosis. We showed for the first time that fungal nucleic acids, purified directly from mature C. albicans biofilm structure or obtained from the whole fungal cells, have the potential to induce NET release in vitro. In this study, we considered the involvement of TLR8 and TLR9 in NETosis activation. We showed that DNA and RNA molecules initiated the production of reactive oxygen species (ROS) by activation of the NADPH oxidase complex, essential for ROS-dependent NETosis. Furthermore, analysis of the cell migration showed that the nucleic acids located in the extracellular space surrounding the biofilm may be also effective chemotactic factors, driving the dynamic migration of human neutrophils to the site of ongoing fungal infection.

scholarly journals Angiopoietin 1 release from human neutrophils is independent from neutrophil extracellular traps (NETs)

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Elcha Charles ◽  
Benjamin L. Dumont ◽  
Steven Bonneau ◽  
Paul-Eduard Neagoe ◽  
Louis Villeneuve ◽  
...  
Keyword(s):  
Nuclear Dna ◽  
Neutrophil Extracellular Traps ◽  
Innate Immune ◽  
Human Neutrophils ◽  
Extracellular Traps ◽  
Pathological Conditions ◽  
Healthy Control ◽  
Angiopoietin 1

Abstract Background Neutrophils induce the synthesis and release of angiopoietin 1 (Ang1), a cytosolic growth factor involved in angiogenesis and capable of inducing several pro-inflammatory activities in neutrophils. Neutrophils also synthesize and release neutrophil extracellular traps (NETs), comprised from decondensed nuclear DNA filaments carrying proteins such as neutrophil elastase (NE), myeloperoxidase (MPO), proteinase 3 (PR3) and calprotectin (S100A8/S100A9), which together, contribute to the innate immune response against pathogens (e.g., bacteria). NETs are involved in various pathological conditions through pro-inflammatory, pro-thrombotic and endothelial dysfunction effects and have recently been found in heart failure (HF) and type 2 diabetes (T2DM) patients. The aim of the present study was to investigate the role of NETs on the synthesis and release of Ang1 by the neutrophils in patients with T2DM and HF with preserved ejection fraction (HFpEF) (stable or acute decompensated; ADHFpEF) with or without T2DM. Results Our data show that at basal level (PBS) and upon treatment with LPS, levels of NETs are slightly increased in patients suffering from T2DM, HFpEF ± T2DM and ADHF without (w/o) T2DM, whereas this increase was significant in ADHFpEF + T2DM patients compared to healthy control (HC) volunteers and ADHFpEF w/o T2DM. We also observed that treatments with PMA or A23187 increase the synthesis of Ang1 (from 150 to 250%) in HC and this effect is amplified in T2DM and in all cohorts of HF patients. Ang1 is completely released (100%) by neutrophils of all groups and does not bind to NETs as opposed to calprotectin. Conclusions Our study suggests that severely ill patients with HFpEF and diabetes synthesize and release a greater abundance of NETs while Ang1 exocytosis is independent of NETs synthesis.

scholarly journals Patients with recurrent PVL+-Staphylococcus aureus infections show enhanced sensitivity to PVL-mediated formation of atypical NETs

2021 ◽  
Author(s):  
Hina Jhelum ◽  
Dora Čerina ◽  
Christopher J Harbort ◽  
Andreas Lindner ◽  
Leif Gunnar Hanitsch ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Proteome Analysis ◽  
Neutrophil Extracellular Traps ◽  
Human Neutrophils ◽  
Proteinase 3 ◽  
Oxygen Species ◽  
Extracellular Traps ◽  
Enhanced Sensitivity ◽  
Microbial Toxin ◽  
Panton Valentine Leukocidin

Panton-Valentine leukocidin (PVL) is a Staphylococcus aureus (S. aureus) toxin that binds to and kills human neutrophils, resulting in the formation of neutrophil extracellular traps (NETs). Some individuals colonized with PVL-positive S. aureus (PVL-SA) suffer from recurring infections whereas others are asymptomatically colonized. We found that neutrophils from affected patients express higher levels of CD45, one of the PVL receptors, and are more susceptible to killing at a low concentration of recombinant PVL than control neutrophils. We verified that PVL induces the formation of NETs and provide genetic and pharmacological evidence that PVL-induced NET formation is independent of NADPH-oxidase and reactive oxygen species (ROS) production. Through NET proteome analysis we identified that the protein content of PVL-induced NETs is different from NETs induced by mitogen or the microbial toxin nigericin. The abundance of the proteins cathelicidin (CAMP), elastase (NE), and proteinase 3 (PRTN3) was lower on PVL-induced NETs, which were inefficient in killing S. aureus. Neutrophils from patients that suffer from recurring PVL-positive infections may be more sensitive to PVL-induced NET formation, which may impair their ability to combat the infection.

scholarly journals Degraded neutrophil extracellular traps promote the growth of Actinobacillus pleuropneumoniae

2019 ◽  
Vol 10 (9) ◽  
Author(s):  
Nicole de Buhr ◽  
Marta C. Bonilla ◽  
Jessica Pfeiffer ◽  
Silke Akhdar ◽  
Cornelia Schwennen ◽  
...  
Keyword(s):  
Immune Cell ◽  
Bacterial Species ◽  
Severe Pneumonia ◽  
Lavage Fluid ◽  
Neutrophil Extracellular Traps ◽  
Actinobacillus Pleuropneumoniae ◽  
Degraded Dna ◽  
Human Neutrophils ◽  
Extracellular Traps

Abstract Actinobacillus pleuropneumoniae (A.pp) causes severe pneumonia associated with enormous economic loss in pigs. Peracute diseased pigs die in <24 h with pneumonia. Neutrophils are the prominent innate immune cell in this infection that massively infiltrate the infected lung. Here we show that neutrophils release neutrophil extracellular traps (NETs) as response to A.pp infection. Numerous NET-markers were identified in bronchoalveolar lavage fluid (BALF) of A.pp-infected piglets in vivo, however, most NET fibers are degraded. Importantly, A.pp is able to enhance its growth rate in the presence of NETs that have been degraded by nucleases efficiently. A.pp itself releases no nuclease, but we identified host nucleases as sources that degrade NETs after A.pp infection. Furthermore, the nucleases of co-infecting pathogens like Streptococcus suis increase growth of A.pp in presence of porcine NETs. Thus, A.pp is not only evading the antimicrobial activity of NETs, A.pp is rather additionally using parts of NETs as growth factor thereby taking advantage of host nucleases as DNase1 or nucleases of co-infecting bacteria, which degrade NETs. This effect can be diminished by inhibiting the bacterial adenosine synthase indicating that degraded NETs serve as a source for NAD, which is required by A.pp for its growth. A similar phenotype was found for the human pathogen Haemophilus (H.) influenzae and its growth in the presence of human neutrophils. H. influenzae benefits from host nucleases in the presence of neutrophils. These data shed light on the detrimental effects of NETs during host immune response against certain bacterial species that require and/or efficiently take advantage of degraded DNA material, which has been provided by host nuclease or nucleases of other co-infecting bacteria, as growth source.

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