901
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Abrams ST, Zhang N, Manson J, Liu T, Dart C, Baluwa F, Wang SS, Brohi K, Kipar A, Yu W, Wang G, Toh CH. Circulating histones are mediators of trauma-associated lung injury. Am J Respir Crit Care Med 2012; 187:160-9. [PMID: 23220920 DOI: 10.1164/rccm.201206-1037oc] [Citation(s) in RCA: 416] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
RATIONALE Acute lung injury is a common complication after severe trauma, which predisposes patients to multiple organ failure. This syndrome largely accounts for the late mortality that arises and despite many theories, the pathological mechanism is not fully understood. Discovery of histone-induced toxicity in mice presents a new dimension for elucidating the underlying pathophysiology. OBJECTIVES To investigate the pathological roles of circulating histones in trauma-induced lung injury. METHODS Circulating histone levels in patients with severe trauma were determined and correlated with respiratory failure and Sequential Organ Failure Assessment (SOFA) scores. Their cause-effect relationship was studied using cells and mouse models. MEASUREMENTS AND MAIN RESULTS In a cohort of 52 patients with severe nonthoracic blunt trauma, circulating histones surged immediately after trauma to levels that were toxic to cultured endothelial cells. The high levels were significantly associated with the incidence of acute lung injury and SOFA scores, as well as markers of endothelial damage and coagulation activation. In in vitro systems, histones damaged endothelial cells, stimulated cytokine release, and induced neutrophil extracellular trap formation and myeloperoxidase release. Cellular toxicity resulted from their direct membrane interaction and resultant calcium influx. In mouse models, cytokines and markers for endothelial damage and coagulation activation significantly increased immediately after trauma or histone infusion. Pathological examinations showed that lungs were the predominantly affected organ with edema, hemorrhage, microvascular thrombosis, and neutrophil congestion. An anti-histone antibody could reduce these changes and protect mice from histone-induced lethality. CONCLUSIONS This study elucidates a new mechanism for acute lung injury after severe trauma and proposes that circulating histones are viable therapeutic targets for improving survival outcomes in patients.
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Affiliation(s)
- Simon T Abrams
- National Institute of Health Research Biomedical Research Centre, Royal Liverpool University Hospital, Liverpool L7 8XP, UK
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902
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Lu T, Kobayashi SD, Quinn MT, Deleo FR. A NET Outcome. Front Immunol 2012; 3:365. [PMID: 23227026 PMCID: PMC3514450 DOI: 10.3389/fimmu.2012.00365] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 11/16/2012] [Indexed: 01/11/2023] Open
Abstract
Neutrophils constitute a critical part of innate immunity and are well known for their ability to phagocytose and kill invading microorganisms. The microbicidal processes employed by neutrophils are highly effective at killing most ingested bacteria and fungi. However, an alternative non-phagocytic antimicrobial mechanism of neutrophils has been proposed whereby microorganisms are eliminated by neutrophil extracellular traps (NETs). NETs are comprised of DNA, histones, and antimicrobial proteins extruded by neutrophils during NETosis, a cell death pathway reported to be distinct from apoptosis, phagocytosis-induced cell death, and necrosis. Although multiple laboratories have reported NETs using various stimuli in vitro, the molecular mechanisms involved in this process have yet to be definitively elucidated, and many questions regarding the formation and putative role or function of NETs in innate host defense remain unanswered. It is with these questions in mind that we provide some reflection and perspective on NETs and NETosis.
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Affiliation(s)
- Thea Lu
- Laboratory of Human Bacterial Pathogenesis, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health Hamilton, MT, USA
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903
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Hahn S, Giaglis S, Hoesli I, Hasler P. Neutrophil NETs in reproduction: from infertility to preeclampsia and the possibility of fetal loss. Front Immunol 2012. [PMID: 23205021 PMCID: PMC3506920 DOI: 10.3389/fimmu.2012.00362] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The intention of this review is to provide an overview of the potential role of neutrophil extracellular traps (NETs) in mammalian reproduction. Neutrophil NETs appear to be involved in various stages of the reproductive cycle, starting with fertility and possibly ending with fetal loss. The first suggestion that NETs may play a role in pregnancy-related disorders was in preeclampsia, where vast numbers were detected in the intervillous space of affected placentae. The induction of NETosis involved an auto-inflammatory component, mediated by the increased release of placental micro-debris in preeclampsia. This report was the first indicating that NETs may be associated with a human pathology not involving infection. Subsequently, NETs have since then been implicated in bovine or equine infertility, in that semen may become entrapped in the female reproductive tract during their passage to the oocyte. In this instance interesting species-specific differences are apparent, in that equine sperm evade entrapment via expression of a DNAse-like molecule, whereas highly motile bovine sperm, once free from seminal plasma (SP) that promotes interaction with neutrophils, appear impervious to NETs entrapment. Although still in the realm of speculation it is plausible that NETs may be involved in recurrent fetal loss mediated by anti-phospholipid antibodies, or perhaps even in fetal abortion triggered by infections with microorganisms such as L. monocytogenes or B. abortus.
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Affiliation(s)
- Sinuhe Hahn
- Department of Biomedicine, University of Basel/Laboratory for Prenatal Medicine, University Clinics, University Women's Hospital Basel, Switzerland
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904
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Anand P, Cermelli S, Li Z, Kassan A, Bosch M, Sigua R, Huang L, Ouellette AJ, Pol A, Welte MA, Gross SP. A novel role for lipid droplets in the organismal antibacterial response. eLife 2012; 1:e00003. [PMID: 23150794 PMCID: PMC3491588 DOI: 10.7554/elife.00003] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 09/05/2012] [Indexed: 01/19/2023] Open
Abstract
We previously discovered histones bound to cytosolic lipid droplets (LDs); here we show that this forms a cellular antibacterial defense system. Sequestered on droplets under normal conditions, in the presence of bacterial lipopolysaccharide (LPS) or lipoteichoic acid (LTA), histones are released from the droplets and kill bacteria efficiently in vitro. Droplet-bound histones also function in vivo: when injected into Drosophila embryos lacking droplet-bound histones, bacteria grow rapidly. In contrast, bacteria injected into embryos with droplet-bound histones die. Embryos with droplet-bound histones displayed more than a fourfold survival advantage when challenged with four different bacterial species. Our data suggests that this intracellular antibacterial defense system may function in adult flies, and also potentially in mice.DOI:http://dx.doi.org/10.7554/eLife.00003.001.
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Affiliation(s)
- Preetha Anand
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, United States
| | - Silvia Cermelli
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, United States
| | - Zhihuan Li
- Department of Biology, University of Rochester, Rochester, United States
| | - Adam Kassan
- Equip de Proliferació i Senyalització Cel.lular, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Marta Bosch
- Equip de Proliferació i Senyalització Cel.lular, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Robilyn Sigua
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, United States
| | - Lan Huang
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, United States
- Department of Physiology and Biophysics, University of California Irvine, Irvine, United States
| | - Andre J Ouellette
- Department of Pathology and Laboratory Medicine, Keck School of Medicine, University of Southern California, Los Angeles, United States
| | - Albert Pol
- Equip de Proliferació i Senyalització Cel.lular, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain
| | - Michael A Welte
- Department of Biology, University of Rochester, Rochester, United States
| | - Steven P Gross
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, United States
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905
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Cytokines induced neutrophil extracellular traps formation: implication for the inflammatory disease condition. PLoS One 2012; 7:e48111. [PMID: 23110185 PMCID: PMC3482178 DOI: 10.1371/journal.pone.0048111] [Citation(s) in RCA: 244] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Accepted: 09/20/2012] [Indexed: 12/13/2022] Open
Abstract
Neutrophils (PMNs) and cytokines have a critical role to play in host defense and systemic inflammatory response syndrome (SIRS). Neutrophil extracellular traps (NETs) have been shown to extracellularly kill pathogens, and inflammatory potential of NETs has been shown. Microbial killing inside the phagosomes or by NETs is mediated by reactive oxygen and nitrogen species (ROS/RNS). The present study was undertaken to assess circulating NETs contents and frequency of NETs generation by isolated PMNs from SIRS patients. These patients displayed significant augmentation in the circulating myeloperoxidase (MPO) activity and DNA content, while PMA stimulated PMNs from these patients, generated more free radicals and NETs. Plasma obtained from SIRS patients, if added to the PMNs isolated from healthy subjects, enhanced NETs release and free radical formation. Expressions of inflammatory cytokines (IL-1β, TNFα and IL-8) in the PMNs as well as their circulating levels were significantly augmented in SIRS subjects. Treatment of neutrophils from healthy subjects with TNFα, IL-1β, or IL-8 enhanced free radicals generation and NETs formation, which was mediated through the activation of NADPH oxidase and MPO. Pre-incubation of plasma from SIRS with TNFα, IL-1β, or IL-8 antibodies reduced the NETs release. Role of IL-1β, TNFα and IL-8 thus seems to be involved in the enhanced release of NETs in SIRS subjects.
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906
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Gardiner EE, Andrews RK. Neutrophil extracellular traps (NETs) and infection-related vascular dysfunction. Blood Rev 2012; 26:255-9. [PMID: 23021640 DOI: 10.1016/j.blre.2012.09.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The innate immune system orchestrated by leukocytes primarily neutrophils, serves to remove dead and dying host cells and to provide protection against invasion by pathogens. Failure of this system results in the onset of sepsis leading to grave consequences for the host. Together with mechanical methods to physically isolate and remove the pathogen, neutrophils also release an important set of proinflammatory biological modulators that mediate recruitment of additional cells to a site of infection and amplify the innate protective response. Additionally, neutrophils release highly charged mixtures of DNA and nuclear proteins named neutrophil extracellular traps (NETs). These electrostatically-charged adhesive networks trigger intrinsic coagulation, limit dispersion and entrap the pathogens. NETs also contain the neutrophil secretary granule-derived serine proteases, neutrophil elastase and cathepsin G, known to regulate the reactivity of both neutrophils and platelets. Since the characterization of NETs in 2004, new studies of their functional effect in vivo continue to expand upon unexpected extracellular roles for DNA, and in doing so renew attention to the haemostatic role of the leukocyte. This review will provide a basic description of NETs and examine current knowledge of this important system of defense, including recent work illustrating a role for NETs in activation of thrombosis.
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907
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Autophagy mediates the delivery of thrombogenic tissue factor to neutrophil extracellular traps in human sepsis. PLoS One 2012; 7:e45427. [PMID: 23029002 PMCID: PMC3446899 DOI: 10.1371/journal.pone.0045427] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 08/17/2012] [Indexed: 01/06/2023] Open
Abstract
Background Sepsis is associated with systemic inflammatory responses and induction of coagulation system. Neutrophil extracellular traps (NETs) constitute an antimicrobial mechanism, recently implicated in thrombosis via platelet entrapment and aggregation. Methodology/Principal Findings In this study, we demonstrate for the first time the localization of thrombogenic tissue factor (TF) in NETs released by neutrophils derived from patients with gram-negative sepsis and normal neutrophils treated with either serum from septic patients or inflammatory mediators involved in the pathogenesis of sepsis. Localization of TF in acidified autophagosomes was observed during this process, as indicated by positive LC3B and LysoTracker staining. Moreover, phosphatidylinositol 3-kinase inhibition with 3-MA or inhibition of endosomal acidification with bafilomycin A1 hindered the release of TF-bearing NETs. TF present in NETs induced thrombin generation in culture supernatants, which further resulted in protease activated receptor-1 signaling. Conclusions/Significance This study demonstrates the involvement of autophagic machinery in the extracellular delivery of TF in NETs and the subsequent activation of coagulation cascade, providing evidence for the implication of this process in coagulopathy and inflammatory response in sepsis.
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908
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Potential role of peptidylarginine deiminase enzymes and protein citrullination in cancer pathogenesis. Biochem Res Int 2012; 2012:895343. [PMID: 23019525 PMCID: PMC3457611 DOI: 10.1155/2012/895343] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/31/2012] [Accepted: 08/09/2012] [Indexed: 11/18/2022] Open
Abstract
The peptidylarginine deiminases (PADs) are a family of posttranslational modification enzymes that catalyze the conversion of positively charged protein-bound arginine and methylarginine residues to the uncharged, nonstandard amino acid citrulline. This enzymatic activity is referred to as citrullination or, alternatively, deimination. Citrullination can significantly affect biochemical pathways by altering the structure and function of target proteins. Five mammalian PAD family members (PADs 1–4 and 6) have been described and show tissue-specific distribution. Recent reviews on PADs have focused on their role in autoimmune diseases. Here, we will discuss the potential role of PADs in tumor progression and tumor-associated inflammation. In the context of cancer, increasing clinical evidence suggests that PAD4 (and possibly PAD2) has important roles in tumor progression. The link between PADs and cancer is strengthened by recent findings showing that treatment of cell lines and mice with PAD inhibitors significantly suppresses tumor growth and, interestingly, inflammatory symptoms. At the molecular level, transcription factors, coregulators, and histones are functional targets for citrullination by PADs, and citrullination of these targets can affect gene expression in multiple tumor cell lines. Next generation isozyme-specific PAD inhibitors may have therapeutic potential to regulate both the inflammatory tumor microenvironment and tumor cell growth.
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909
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Rosin DL, Okusa MD. Dying cells and extracellular histones in AKI: beyond a NET effect? J Am Soc Nephrol 2012; 23:1275-7. [PMID: 22797184 DOI: 10.1681/asn.2012060615] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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910
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Fuchs TA, Brill A, Wagner DD. Neutrophil extracellular trap (NET) impact on deep vein thrombosis. Arterioscler Thromb Vasc Biol 2012; 32:1777-83. [PMID: 22652600 DOI: 10.1161/atvbaha.111.242859] [Citation(s) in RCA: 383] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Deep vein thrombosis (DVT) is a major health problem that requires improved prophylaxis and treatment. Inflammatory conditions such as infection, cancer, and autoimmune diseases are risk factors for DVT. We and others have recently shown that extracellular DNA fibers produced in inflammation and known as neutrophil extracellular traps (NETs) contribute to experimental DVT. NETs stimulate thrombus formation and coagulation and are abundant in thrombi in animal models of DVT. It appears that, in addition to fibrin and von Willebrand factor, NETs represent a third thrombus scaffold. Here, we review how NETs stimulate thrombosis and discuss known and potential interactions of NETs with endothelium, platelets, red blood cells, and coagulation factors and how NETs could influence thrombolysis. We propose that drugs that inhibit NET formation or facilitate NET degradation may prevent or treat DVT.
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Affiliation(s)
- Tobias A Fuchs
- Immune Disease Institute, Children’s Hospital Boston, Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
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911
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De Meyer SF, Suidan GL, Fuchs TA, Monestier M, Wagner DD. Extracellular chromatin is an important mediator of ischemic stroke in mice. Arterioscler Thromb Vasc Biol 2012; 32:1884-91. [PMID: 22628431 DOI: 10.1161/atvbaha.112.250993] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Recently, a growing number of studies have revealed a prothrombotic and cytotoxic role for extracellular chromatin. Cerebral ischemia/reperfusion injury is characterized by a significant amount of cell death and neutrophil activation, both of which may result in the release of chromatin. The goal of this study was to assess the effect of extracellular chromatin in ischemic stroke using a mouse model of transient middle cerebral artery occlusion. METHODS AND RESULTS Similar to reports in stroke patients, we observed increased levels of circulating nucleosomes and DNA after ischemic stroke in mice. In addition, we observed that general hypoxia also augmented extracellular chromatin. We hypothesized that targeting extracellular chromatin components would be protective in ischemic stroke. Indeed, treatment with recombinant human DNase 1 significantly improved stroke outcome. Neutralization of histones using an antihistone antibody was also protective as evidenced by smaller infarct volumes, whereas increasing levels of extracellular histones via histone infusion exacerbated stroke outcome by increasing infarct size and worsening functional outcome. CONCLUSIONS Our results indicate that extracellular chromatin is generated and is detrimental during cerebral ischemia/reperfusion in mice. Targeting DNA and histones may be a new therapeutic strategy to limit injury resulting from ischemic stroke.
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Affiliation(s)
- Simon F De Meyer
- Immune Disease Institute, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02115, USA
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912
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Abstract
Transfusion-related acute lung injury (TRALI) is the leading cause of transfusion-related death. The biologic processes contributing to TRALI are poorly understood. All blood products can cause TRALI, and no specific treatment is available. A "2-event model" has been proposed as the trigger. The first event may include surgery, trauma, or infection; the second involves the transfusion of antileukocyte antibodies or bioactive lipids within the blood product. Together, these events induce neutrophil activation in the lungs, causing endothelial damage and capillary leakage. Neutrophils, in response to pathogens or under stress, can release their chromatin coated with granule contents, thus forming neutrophil extracellular traps (NETs). Although protective against infection, these NETs are injurious to tissue. Here we show that NET biomarkers are present in TRALI patients' blood and that NETs are produced in vitro by primed human neutrophils when challenged with anti-HNA-3a antibodies previously implicated in TRALI. NETs are found in alveoli of mice experiencing antibody-mediated TRALI. DNase 1 inhalation prevents their alveolar accumulation and improves arterial oxygen saturation even when administered 90 minutes after TRALI onset. We suggest that NETs form in the lungs during TRALI, contribute to the disease process, and thus could be targeted to prevent or treat TRALI.
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