scholarly journals SARS-CoV-2–triggered neutrophil extracellular traps mediate COVID-19 pathology

2020 ◽  
Vol 217 (12) ◽  
Author(s):  
Flavio Protasio Veras ◽  
Marjorie Cornejo Pontelli ◽  
Camila Meirelles Silva ◽  
Juliana E. Toller-Kawahisa ◽  
Mikhael de Lima ◽  
...  
Keyword(s):  
Inflammatory Diseases ◽  
Tracheal Aspirate ◽  
Neutrophil Extracellular Traps ◽  
Angiotensin Converting Enzyme 2 ◽  
Extracellular Traps ◽  
Lung Epithelial ◽  
Activated Neutrophils ◽  
Epithelial Cell Death

Severe COVID-19 patients develop acute respiratory distress syndrome that may progress to cytokine storm syndrome, organ dysfunction, and death. Considering that neutrophil extracellular traps (NETs) have been described as important mediators of tissue damage in inflammatory diseases, we investigated whether NETs would be involved in COVID-19 pathophysiology. A cohort of 32 hospitalized patients with a confirmed diagnosis of COVID-19 and healthy controls were enrolled. The concentration of NETs was augmented in plasma, tracheal aspirate, and lung autopsies tissues from COVID-19 patients, and their neutrophils released higher levels of NETs. Notably, we found that viable SARS-CoV-2 can directly induce the release of NETs by healthy neutrophils. Mechanistically, NETs triggered by SARS-CoV-2 depend on angiotensin-converting enzyme 2, serine protease, virus replication, and PAD-4. Finally, NETs released by SARS-CoV-2–activated neutrophils promote lung epithelial cell death in vitro. These results unravel a possible detrimental role of NETs in the pathophysiology of COVID-19. Therefore, the inhibition of NETs represents a potential therapeutic target for COVID-19.

scholarly journals SARS-CoV-2 triggered neutrophil extracellular traps (NETs) mediate COVID-19 pathology

2020 ◽  
Author(s):  
Flavio Veras ◽  
Marjorie Pontelli ◽  
Camila Silva ◽  
Juliana Toller-Kawahisa ◽  
Mikhael de Lima ◽  
...  
Keyword(s):  
Lung Tissue ◽  
Tissue Damage ◽  
A549 Cells ◽  
Tracheal Aspirate ◽  
Neutrophil Extracellular Traps ◽  
Dependent Manner ◽  
Extracellular Traps ◽  
Activated Neutrophils ◽  
Tissue Specimens

AbstractSevere COVID-19 patients develop acute respiratory distress syndrome that may progress to respiratory failure. These patients also develop cytokine storm syndrome, and organ dysfunctions, which is a clinical picture that resembles sepsis. Considering that neutrophil extracellular traps (NETs) have been described as an important factors of tissue damage in sepsis, we investigated whether NETs would be produced in COVID-19 patients and participate in the lung tissue damage. A cohort of 32 hospitalized patients with a confirmed diagnosis of COVID-19 and respective healthy controls were enrolled. NETs concentration was assessed by MPO-DNA PicoGreen assay or by confocal immunofluorescence. The cytotoxic effect of SARS-CoV-2-induced NETs was analyzed in human epithelial lung cells (A549 cells). The concentration of NETs was augmented in plasma and tracheal aspirate from COVID-19 patients and their neutrophils spontaneously released higher levels of NETs. NETs were also found in the lung tissue specimens from autopsies of COVID-19 patients. Notably, viable SARS-CoV-2 can directly induce in vitro release of NETs by healthy neutrophils in a PAD-4-dependent manner. Finally, NETs released by SARS-CoV-2-activated neutrophils promote lung epithelial cell death in vitro. These results unravel a possible detrimental role of NETs in the pathophysiology of COVID-19. Therefore, the inhibition of NETs represent a potential therapeutic target for COVID-19.

scholarly journals The state of art of neutrophil extracellular traps in protozoan and helminthic infections

2019 ◽  
Vol 39 (1) ◽  
Author(s):  
César Díaz-Godínez ◽  
Julio C. Carrero
Keyword(s):  
Neutrophil Extracellular Traps ◽  
Parasitic Infections ◽  
Parasitic Diseases ◽  
Helminth Parasites ◽  
Extracellular Traps ◽  
Helminthic Infections ◽  
Bacteria And Fungi ◽  
Net Release

AbstractNeutrophil extracellular traps (NETs) are DNA fibers associated with histones, enzymes from neutrophil granules and anti-microbial peptides. NETs are released in a process denominated NETosis, which involves sequential steps that culminate with the DNA extrusion. NETosis has been described as a new mechanism of innate immunity related to defense against different pathogens. The initial studies of NETs were carried out with bacteria and fungi, but currently a large variety of microorganisms capable of inducing NETs have been described including protozoan and helminth parasites. Nevertheless, we have little knowledge about how NETosis process is carried out in response to the parasites, and about its implication in the resolution of this kind of disease. In the best case, the NETs entrap and kill parasites in vitro, but in others, immobilize the parasites without affecting their viability. Moreover, insufficient studies on the NETs in animal models of infections that would help to define their role, and the association of NETs with chronic inflammatory pathologies such as those occurring in several parasitic infections have left open the possibility of NETs contributing to pathology instead of protection. In this review, we focus on the reported mechanisms that lead to NET release by protozoan and helminth parasites and the evidence that support the role of NETosis in the resolution or pathogenesis of parasitic diseases.

scholarly journals Neutrophil extracellular traps are associated with altered human pulmonary artery endothelial barrier function

2021 ◽  
Vol 19 ◽  
pp. 205873922110623
Author(s):  
Hisatake Mori ◽  
Muhammad Aminul Huq ◽  
Md. Monirul Islam ◽  
Naoshi Takeyama
Keyword(s):  
Endothelial Cell ◽  
Pulmonary Artery ◽  
Barrier Function ◽  
Neutrophil Extracellular Traps ◽  
Endothelial Barrier ◽  
Endothelial Barrier Function ◽  
Extracellular Traps ◽  
Activated Neutrophils ◽  
Human Pulmonary Artery

Introduction: Acute respiratory response syndrome (ARDS) leads to increased permeability of the endothelial-epithelial barrier, which in turn promotes edema formation and hypoxemic respiratory failure. Although activated neutrophils are thought to play a significant role in mediating ARDS, at present the contribution of neutrophil extracellular traps (NETs) to lung endothelial barrier function is unclear. Methods: To clarify their role, we co-cultured in vitro NETs induced by phorbol myristate acetate (PMA)–activated neutrophils with lung endothelial cell monolayers and examined the barrier function of lung endothelial cells by immunofluorescence microscopy and albumin permeability in a double-chamber culture method. Results: Co-culture with stimulated neutrophils increased the albumin permeability of the human pulmonary artery endothelial cell (HPAEC) monolayer and altered cytoskeleton F-actin and vascular endothelial-cadherin in cell-cell junctions. Hyperpermeability to albumin and histological alterations were prevented by inhibition of NET formation with peptidyl arginine deiminase inhibitor or a neutrophil elastase inhibitor and were also prevented by increased degradation of NET structure with DNase. Conclusion: This in vitro experiment shows that altered HPAEC barrier function and increased albumin permeability are caused by the direct effect of PMA-induced NETs and their components. NET formation may be involved in the increased vascular permeability of the lung, which is a common feature in ARDS of various etiologies. These insights may help generate novel approaches for medical interventions.

scholarly journals The Emerging Role of Neutrophil Extracellular Traps in Arterial, Venous and Cancer-Associated Thrombosis

2021 ◽  
Vol 8 ◽  
Author(s):  
Yilu Zhou ◽  
Weimin Tao ◽  
Fuyi Shen ◽  
Weijia Du ◽  
Zhendong Xu ◽  
...  
Keyword(s):  
Current Knowledge ◽  
Neutrophil Extracellular Traps ◽  
Vital Role ◽  
Extracellular Traps ◽  
Protein Components ◽  
Cancer Associated Thrombosis ◽  
Coagulation Pathway

Neutrophils play a vital role in the formation of arterial, venous and cancer-related thrombosis. Recent studies have shown that in a process known as NETosis, neutrophils release proteins and enzymes complexed to DNA fibers, collectively called neutrophil extracellular traps (NETs). Although NETs were originally described as a way for the host to capture and kill bacteria, current knowledge indicates that NETs also play an important role in thrombosis. According to recent studies, the destruction of vascular microenvironmental homeostasis and excessive NET formation lead to pathological thrombosis. In vitro experiments have found that NETs provide skeletal support for platelets, red blood cells and procoagulant molecules to promote thrombosis. The protein components contained in NETs activate the endogenous coagulation pathway to promote thrombosis. Therefore, NETs play an important role in the formation of arterial thrombosis, venous thrombosis and cancer-related thrombosis. This review will systematically summarize and explain the study of NETs in thrombosis in animal models and in vivo experiments to provide new targets for thrombosis prevention and treatment.

scholarly journals How Neutrophil Extracellular Traps Become Visible

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Nicole de Buhr ◽  
Maren von Köckritz-Blickwede
Keyword(s):  
Electron Microscopy ◽  
Nuclear Dna ◽  
Defense Mechanism ◽  
Neutrophil Extracellular Traps ◽  
Immune Defense ◽  
Extracellular Traps ◽  
Activated Neutrophils ◽  
Microscopy Techniques

Neutrophil extracellular traps (NETs) have been identified as a fundamental innate immune defense mechanism against different pathogens. NETs are characterized as released nuclear DNA associated with histones and granule proteins, which form an extracellular web-like structure that is able to entrap and occasionally kill certain microbes. Furthermore, NETs have been shown to contribute to several noninfectious disease conditions when released by activated neutrophils during inflammation. The identification of NETs has mainly been succeeded by various microscopy techniques, for example, immunofluorescence microscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Since the last years the development and improvement of new immunofluorescence-based techniques enabled optimized visualization and quantification of NETs. On the one handin vitrolive-cell imaging led to profound new ideas about the mechanisms involved in the formation and functionality of NETs. On the other hand different intravital,in vivo, andin situmicroscopy techniques led to deeper insights into the role of NET formation during health and disease. This paper presents an overview of the main used microscopy techniques to visualize NETs and describes their advantages as well as disadvantages.

scholarly journals SOCE-inhibitor reduced human sperm-induced formation of neutrophil extracellular traps

Reproduction ◽  
2021 ◽  
Vol 161 (1) ◽  
pp. 21-29
Author(s):  
Fabiola Zambrano ◽  
Liliana Silva ◽  
Pamela Uribe ◽  
Ulrich Gärtner ◽  
Anja Taubert ◽  
...  
Keyword(s):  
Binding Capacity ◽  
Human Sperm ◽  
Neutrophil Extracellular Traps ◽  
Positive Control ◽  
Polymorphonuclear Neutrophils ◽  
Extracellular Dna ◽  
Dna Integrity ◽  
Extracellular Traps

Human spermatozoa activate neutrophil extracellular traps (NETs) in vitro. NETosis is an efficient mechanism through which polymorphonuclear neutrophils (PMN) capture sperm in vitro. The objective of this study was to establish the role of store-operated Ca+2 entry (SOCE) in human sperm-triggered NETs and its impact on sperm integrity and oocyte binding capacity. PMN isolated from donors were exposed to spermatozoa isolated from normozoospermic donors using the swim-up technique and were divided into the following groups: (1) sperm, (2) PMN, (3) PMN + sperm, (4) PMN (pretreated with 2-APB, SOCE inhibitor) + sperm, (5) (PMN + DNase) + sperm, and (6) (PMN + PMA) + sperm (positive control). NETs were quantified using PicoGreen® and visualised by scanning electron microscopy and immunofluorescence of extracellular DNA and neutrophil elastase. Plasma membrane, acrosome, and DNA integrity were analysed by flow cytometry, and oocyte binding was evaluated using the hemizona pellucida assay. Sperm-triggered NETosis negatively affected the sperm membrane and acrosome integrity and decreased the oocyte binding capacity. These effects were negated by an SOCE inhibitor, thus improving sperm function and achieving high oocyte binding capacity. The SOCE inhibitor significantly reduced NET formation compared with that in control PMN/sperm (P < 0.05). Collectively, these results advance the knowledge about the role of PMN in reproduction and will allow the development of strategies to block NET formation in situations of reduced fertilisation success.

Neutrophil extracellular traps (NETs) and the role of platelets in infection

2014 ◽  
Vol 112 (10) ◽  
pp. 659-665 ◽  
Author(s):  
Robert Andrews ◽  
Jane Arthur ◽  
Elizabeth Gardiner
Keyword(s):  
Immune Responses ◽  
Platelet Function ◽  
Inflammatory Responses ◽  
Neutrophil Extracellular Traps ◽  
Nuclear Material ◽  
Extracellular Traps ◽  
Tumour Metastasis ◽  
Activated Neutrophils ◽  
Infection And Inflammation

SummaryIn addition to playing a central role in normal haemostasis, platelets make important contributions to host inflammatory and immune responses to injury or infection. Under pathophysiological conditions where platelet function is not tightly controlled, platelets also play critical roles in pathogenic processes underlying cardiovascular disease, uncontrolled inflammation, coagulopathy and in tumour metastasis. Neutrophil extracellular traps (NETs) are webs of histone-modified nuclear material extruded from activated neutrophils during inflammatory responses and these degranulation events can be directly triggered by platelet/neutrophil engagement. Emerging research describes how NETs influence platelet function, particularly in the setting of infection and inflammation. Especially intriguing is the potential for platelet-driven coagulation to be modulated by NETs in plasma and interstitial spaces. These findings also reveal new perspectives related to improved therapy for venous thrombosis.

scholarly journals Platelet CXCL4 mediates neutrophil extracellular traps formation in ANCA-associated vasculitis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kotaro Matsumoto ◽  
Hidekata Yasuoka ◽  
Keiko Yoshimoto ◽  
Katsuya Suzuki ◽  
Tsutomu Takeuchi
Keyword(s):  
Flow Cytometric Analysis ◽  
Neutrophil Extracellular Traps ◽  
Platelet Factor ◽  
Extracellular Traps ◽  
Flow Cytometric ◽  
Anca Associated Vasculitis ◽  
Tlr Agonist ◽  
Tlr9 Signaling

AbstractNeutrophils form neutrophil extracellular traps (NETs), which are involved in the pathogenesis of ANCA-associated vasculitis (AAV). Recent reports suggest that platelets stimulated via toll-like receptor (TLR) pathways can induce NETs formation. However, the mechanism underlying the involvement of platelets in NETs formation in AAV is unknown. We investigated the role of platelets in the pathogenesis of AAV. Platelets from AAV patients and healthy controls (HCs) were co-cultured with peripheral neutrophils, and NETs formation was visualized and quantified. The expression levels of TLRs on platelets were examined by flow cytometry. Platelets were treated with a TLR agonist, platelet-derived humoral factor, CXCL4 (platelet factor 4: PF4), and/or anti-CXCL4 antibody to investigate the effects of TLR–CXCL4 signaling on NETs formation. Platelets from AAV significantly upregulated NETs formation in vitro. Flow cytometric analysis revealed that the proportion of TLR9 positive platelets was significantly higher in AAV than HCs. CXCL4 released from TLR9 agonist-stimulated platelets was significantly enhanced in AAV, which subsequently increased NETs formation. Further, neutralizing anti-CXCL4 antibody significantly inhibited NETs formation enhanced by platelets from AAV. TLR9 signaling and CXCL4 release underlie the key role that platelets play in NETs formation in the pathogenesis of AAV.

scholarly journals Neutrophil extracellular traps in cancer: not only catching microbes

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Livia Ronchetti ◽  
Nouha Setti Boubaker ◽  
Maddalena Barba ◽  
Patrizia Vici ◽  
Aymone Gurtner ◽  
...  
Keyword(s):  
Cancer Patients ◽  
White Blood Cells ◽  
Neutrophil Extracellular Traps ◽  
Neutrophil Extracellular Trap ◽  
Prognostic Role ◽  
Extracellular Traps ◽  
Activated Neutrophils ◽  
Neoplastic Process ◽  
Review Current

AbstractNeutrophils are the most abundant type of white blood cells circulating throughout the bloodstream and are often considered the frontline defenders in innate immunity. However, neutrophils are increasingly being recognized as having an important role in tumorigenesis and carcinogenesis due to their aberrant activation by molecules released into the tumor microenvironment. One defensive response of neutrophils that is aberrantly triggered during the neoplastic process is called NETosis, where activated neutrophils expel their DNA and intracellular contents in a web-like structure known as a neutrophil extracellular trap (NET). In cancer, NETosis has been linked to increased disease progression, metastasis, and complications such as venous thromboembolism. NET structures released by neutrophils can also serve as a scaffold for clot formation, shining new light on the role of neutrophils and NETosis in coagulation-mediated diseases.Here, we review current available knowledge regarding NET and the related NETosis process in cancer patients, with an emphasis on pre-clinical and clinical data fostering the identification and validation of biomarkers of NET with a predictive/prognostic role in cancer patients treated with immunotherapy agents. NETosis biomarkers, e.g., citH3, may integrate correlates of immunogenicity currently available (e.g., PD-L1 expression, TMB, TILs) and help select the subsets of patients who may most benefit from the use of the therapeutic weapons under discussion.

scholarly journals Neutrophil Extracellular Traps Affecting Cardiovascular Health in Infectious and Inflammatory Diseases

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1689
Author(s):  
Manovriti Thakur ◽  
Bryce Evans ◽  
Marc Schindewolf ◽  
Iris Baumgartner ◽  
Yvonne Döring
Keyword(s):  
Cardiovascular Health ◽  
Viral Infections ◽  
Inflammatory Diseases ◽  
Vascular Inflammation ◽  
Neutrophil Extracellular Traps ◽  
Immune Defense ◽  
Future Research ◽  
Extracellular Traps ◽  
Infection And Inflammation

Neutrophil extracellular traps (NETs) are web-like structures of decondensed extracellular chromatin fibers and neutrophil granule proteins released by neutrophils. NETs participate in host immune defense by entrapping pathogens. They are pro-inflammatory in function, and they act as an initiator of vascular coagulopathies by providing a platform for the attachment of various coagulatory proteins. NETs are diverse in their ability to alter physiological and pathological processes including infection and inflammation. In this review, we will summarize recent findings on the role of NETs in bacterial/viral infections associated with vascular inflammation, thrombosis, atherosclerosis and autoimmune disorders. Understanding the complex role of NETs in bridging infection and chronic inflammation as well as discussing important questions related to their contribution to pathologies outlined above may pave the way for future research on therapeutic targeting of NETs applicable to specific infections and inflammatory disorders.

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