951
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Mayadas TN, Cullere X, Lowell CA. The multifaceted functions of neutrophils. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2013; 9:181-218. [PMID: 24050624 DOI: 10.1146/annurev-pathol-020712-164023] [Citation(s) in RCA: 836] [Impact Index Per Article: 76.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neutrophils and neutrophil-like cells are the major pathogen-fighting immune cells in organisms ranging from slime molds to mammals. Central to their function is their ability to be recruited to sites of infection, to recognize and phagocytose microbes, and then to kill pathogens through a combination of cytotoxic mechanisms. These include the production of reactive oxygen species, the release of antimicrobial peptides, and the recently discovered expulsion of their nuclear contents to form neutrophil extracellular traps. Here we discuss these primordial neutrophil functions, which also play key roles in tissue injury, by providing details of neutrophil cytotoxic functions and congenital disorders of neutrophils. In addition, we present more recent evidence that interactions between neutrophils and adaptive immune cells establish a feed-forward mechanism that amplifies pathologic inflammation. These newly appreciated contributions of neutrophils are described in the setting of several inflammatory and autoimmune diseases.
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Affiliation(s)
- Tanya N Mayadas
- Center for Excellence in Vascular Biology, Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts 20115;
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952
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Abstract
In this review, we examine the evidence that neutrophil extracellular traps (NETs) play a critical role in innate immunity. We summarize how NETs are formed in response to various stimuli and provide evidence that NETosis is not universally a cell death pathway. Here we describe at least 2 different mechanisms by which NETs are formed, including a suicide lytic NETosis and a live cell or vital NETosis. We also evaluate the evidence for NETs in catching and killing pathogens. Finally, we examine how infections are related to the development of autoimmune and vasculitic diseases through unintended but detrimental bystander damage resulting from NET release.
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953
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Bosmann M, Grailer JJ, Ruemmler R, Russkamp NF, Zetoune FS, Sarma JV, Standiford TJ, Ward PA. Extracellular histones are essential effectors of C5aR- and C5L2-mediated tissue damage and inflammation in acute lung injury. FASEB J 2013; 27:5010-21. [PMID: 23982144 DOI: 10.1096/fj.13-236380] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We investigated how complement activation promotes tissue injury and organ dysfunction during acute inflammation. Three models of acute lung injury (ALI) induced by LPS, IgG immune complexes, or C5a were used in C57BL/6 mice, all models requiring availability of both C5a receptors (C5aR and C5L2) for full development of ALI. Ligation of C5aR and C5L2 with C5a triggered the appearance of histones (H3 and H4) in bronchoalveolar lavage fluid (BALF). BALF from humans with ALI contained H4 histone. Histones were absent in control BALF from healthy volunteers. In mice with ALI, in vivo neutralization of H4 with IgG antibody reduced the intensity of ALI. Neutrophil depletion in mice with ALI markedly reduced H4 presence in BALF and was highly protective. The direct lung damaging effects of extracellular histones were demonstrated by airway administration of histones into mice and rats (Sprague-Dawley), which resulted in ALI that was C5a receptor-independent, and associated with intense inflammation, PMN accumulation, damage/destruction of alveolar epithelial cells, together with release into lung of cytokines/chemokines. High-resolution magnetic resonance imaging demonstrated lung damage, edema and consolidation in histone-injured lungs. These studies confirm the destructive C5a-dependent effects in lung linked to appearance of extracellular histones.
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Affiliation(s)
- Markus Bosmann
- 1Department of Pathology, The University of Michigan Medical School, 1301 Catherine Rd., Ann Arbor, Michigan 48109-5602.
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954
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Peptidylarginine deiminases in citrullination, gene regulation, health and pathogenesis. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:1126-35. [PMID: 23860259 DOI: 10.1016/j.bbagrm.2013.07.003] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Revised: 07/03/2013] [Accepted: 07/08/2013] [Indexed: 01/17/2023]
Abstract
Peptidylarginine deiminases are a family of enzymes that mediate post-translational modifications of protein arginine residues by deimination or demethylimination to produce citrulline. In vitro, the activity of PADs is dependent on calcium and reductive reagents carrying a free sulfhydryl group. The discovery that PAD4 can target both arginine and methyl-arginine for citrullination about 10years ago renewed our interest in studying this family of enzymes in gene regulation and their physiological functions. The deregulation of PADs is involved in the etiology of multiple human diseases, including cancers and autoimmune disorders. There is a growing effort to develop isoform specific PAD inhibitors for disease treatment. However, the regulation of the activity of PADs in vivo remains largely elusive, and we expect that much will be learned about the role of these enzymes in a normal life cycle and under pathology conditions.
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955
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Spaan AN, Surewaard BGJ, Nijland R, van Strijp JAG. Neutrophils versus Staphylococcus aureus: a biological tug of war. Annu Rev Microbiol 2013; 67:629-50. [PMID: 23834243 DOI: 10.1146/annurev-micro-092412-155746] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The pathogen Staphylococcus aureus is well adapted to its human host. Neutrophil-mediated killing is a crucial defense system against S. aureus; however, the pathogen has evolved many strategies to resist killing. We first describe the discrete steps of neutrophil activation and migration to the site of infection and the killing of microbes by neutrophils in general. We then highlight the different approaches utilized by S. aureus to resist the different steps of neutrophil attack. Various molecules are discussed in their evolutionary context. Most of the molecules secreted by S. aureus to combat neutrophil attacks at the site of infection show clear human specificity. Many elements of human neutrophil defenses appear redundant, and so the evasion strategies of staphylococci display redundant functions as well. All efforts by S. aureus to resist neutrophil-mediated killing stress the importance of these mechanisms in the pathophysiology of staphylococcal diseases. However, the highly human-specific nature of most host-pathogen interactions hinders the in vivo establishment of their contribution to staphylococcal pathophysiology.
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Affiliation(s)
- András N Spaan
- Department of Medical Microbiology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands; , , ,
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956
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Branzk N, Papayannopoulos V. Molecular mechanisms regulating NETosis in infection and disease. Semin Immunopathol 2013; 35:513-30. [PMID: 23732507 PMCID: PMC3685711 DOI: 10.1007/s00281-013-0384-6] [Citation(s) in RCA: 216] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Accepted: 05/17/2013] [Indexed: 12/17/2022]
Abstract
Neutrophils are the foot soldiers of the immune system. They home in to the site of infection and kill pathogens by phagocytosis, degranulation, and the release of web-like structures called neutrophil extracellular traps (NETs) that trap and kill a variety of microbes. NETs have been shown to play a multitude of additional roles in immunity but have also been implicated in inflammatory and autoimmune disease. Here, we discuss the role of NETs in these various contexts with a particular emphasis on the molecular mechanisms that regulate NET release and clearance. We highlight the comprehensive concepts and explore the important open questions in the field.
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Affiliation(s)
- Nora Branzk
- Division of Molecular Immunology, Medical Research Council National Institute for Medical Research, Mill Hill, London, UK
| | - Venizelos Papayannopoulos
- Division of Molecular Immunology, Medical Research Council National Institute for Medical Research, Mill Hill, London, UK
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957
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Habets KLL, Huizinga TWJ, Toes REM. Platelets and autoimmunity. Eur J Clin Invest 2013; 43:746-57. [PMID: 23617819 DOI: 10.1111/eci.12101] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 04/01/2013] [Indexed: 12/12/2022]
Abstract
Vascular injury is the initial manifestation of inflammation resulting in the recruitment and activation of various cell types. The integrity of the vascular wall is monitored by platelets that become activated in the presence of exposed subendothelium. Besides their well-established role in haemostasis, ample data are now emerging on the many immunoregulatory functions of platelets. Platelets store and release a large plethora of cytokines, chemokines and growth factors. They also represent the largest circulating pool of many inflammatory mediators like P-selectin, CD40L and non-neuronal serotonin. Furthermore, complement activation occurs on the platelet surface and deposition of complement results in platelet activation. Overall, platelets have multiple functions in both innate and adaptive immunity. Further insight into the multifaceted role of platelets could therefore provide important clues into how we could implement current platelet therapy to reduce both platelet-induced thrombosis and inflammation. In this review, we discuss the current perceptions of platelet involvement in various autoimmune diseases like rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis and multiple sclerosis.
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Affiliation(s)
- Kim L L Habets
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands.
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958
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Barrientos L, Marin-Esteban V, de Chaisemartin L, Le-Moal VL, Sandré C, Bianchini E, Nicolas V, Pallardy M, Chollet-Martin S. An improved strategy to recover large fragments of functional human neutrophil extracellular traps. Front Immunol 2013; 4:166. [PMID: 23805143 PMCID: PMC3690357 DOI: 10.3389/fimmu.2013.00166] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 06/11/2013] [Indexed: 01/21/2023] Open
Abstract
Netosis is a recently described neutrophil function that leads to the release of neutrophil extracellular traps (NETs) in response to various stimuli. NETs are filaments of decondensed chromatin associated with granular proteins. In addition to their role against microorganisms, NETs have been implicated in autoimmunity, thrombosis, and tissue injury. Access to a standardized source of isolated NETs is needed to better analyze the roles of NETs. The aim of this study was to develop a procedure yielding soluble, well-characterized NET preparations from fresh human neutrophils. The calcium ionophore A23187 was chosen to induce netosis, and the restriction enzyme AluI was used to prepare large NET fragments. DNA and proteins were detected by electrophoresis and specific labeling. Some NET proteins [histone 3, lactoferrin (LF)] were quantified by western blotting, and double-stranded DNA (dsDNA) was quantified by immunofluorescence. Co-existence of dsDNA and neutrophil proteins confirmed the quality of the NET preparations. Their biological activity was checked by measuring elastase (ELA) activity and bacterial killing against various strains. Interindividual differences in histone 3, LF, ELA, and dsDNA relative contents were observed in isolated NETs. However, the reproducibility of NET preparation and characterization was validated, suggesting that this interindividual variability was rather related to donor variation than to technical bias. This standardized protocol is suitable for producing, isolating, and quantifying functional NETs that could serve as a tool for studying NET effects on immune cells and tissues.
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Affiliation(s)
- Lorena Barrientos
- INSERM, UMR-S 996, "Cytokines, Chemokines and Immunopathology", UniverSud , Paris , France ; Faculté de Pharmacie, UniverSud , Paris , France
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959
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Knight JS, Zhao W, Luo W, Subramanian V, O'Dell AA, Yalavarthi S, Hodgin JB, Eitzman DT, Thompson PR, Kaplan MJ. Peptidylarginine deiminase inhibition is immunomodulatory and vasculoprotective in murine lupus. J Clin Invest 2013; 123:2981-93. [PMID: 23722903 DOI: 10.1172/jci67390] [Citation(s) in RCA: 291] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 04/05/2013] [Indexed: 12/11/2022] Open
Abstract
Recent evidence suggests that enhanced neutrophil extracellular trap (NET) formation activates plasmacytoid dendritic cells and serves as a source of autoantigens in SLE. We propose that aberrant NET formation is also linked to organ damage and to the premature vascular disease characteristic of human SLE. Here, we demonstrate enhanced NET formation in the New Zealand mixed 2328 (NZM) model of murine lupus. NZM mice also developed autoantibodies to NETs as well as the ortholog of human cathelicidin/LL37 (CRAMP), a molecule externalized in the NETs. NZM mice were treated with Cl-amidine, an inhibitor of peptidylarginine deiminases (PAD), to block NET formation and were evaluated for lupus-like disease activity, endothelial function, and prothrombotic phenotype. Cl-amidine treatment inhibited NZM NET formation in vivo and significantly altered circulating autoantibody profiles and complement levels while reducing glomerular IgG deposition. Further, Cl-amidine increased the differentiation capacity of bone marrow endothelial progenitor cells, improved endothelium-dependent vasorelaxation, and markedly delayed time to arterial thrombosis induced by photochemical injury. Overall, these findings suggest that PAD inhibition can modulate phenotypes crucial for lupus pathogenesis and disease activity and may represent an important strategy for mitigating cardiovascular risk in lupus patients.
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Affiliation(s)
- Jason S Knight
- Division of Rheumatology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109-5680, USA
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960
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Life of neutrophil: From stem cell to neutrophil extracellular trap. Respir Physiol Neurobiol 2013; 187:68-73. [DOI: 10.1016/j.resp.2013.02.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2012] [Revised: 02/23/2013] [Accepted: 02/25/2013] [Indexed: 12/16/2022]
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961
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Pratesi F, Dioni I, Tommasi C, Alcaro MC, Paolini I, Barbetti F, Boscaro F, Panza F, Puxeddu I, Rovero P, Migliorini P. Antibodies from patients with rheumatoid arthritis target citrullinated histone 4 contained in neutrophils extracellular traps. Ann Rheum Dis 2013; 73:1414-22. [PMID: 23727635 DOI: 10.1136/annrheumdis-2012-202765] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND Histone deimination regulates gene function and contributes to antimicrobial response, allowing the formation of neutrophil extracellular traps (NETs). Deiminated proteins are target of anti-citrullinated peptides antibodies (ACPA) in rheumatoid arthritis (RA). OBJECTIVE The objective of this paper is to test the hypothesis that RA sera react with deiminated histones contained in NETs. METHODS Neutrophils from peripheral blood were stimulated with A23187 and acid treated; NETosis was induced by phorbol myristate acetate, and NET proteins were isolated. Sera were tested by immunoblot on acid extracted proteins from neutrophils and from NETs, and by ELISA on deiminated histone H4 or H4-derived peptides. Bands reactive with RA sera were excised from gels, digested with trypsin and subjected to matrix-assisted laser desorption/ionisation time of flight (MALDI-TOF) analysis, before and after derivatisation to detect citrullinated peptides. RESULTS RA sera reacted with a deiminated antigen of 11 KDa from activated neutrophils, recognised also by anti-H4 and antideiminated H4 antibodies. A similar reactivity was observed with NET proteins. The antigen from neutrophils or NETs was identified as citrullinated H4 by MALDI-TOF analysis. By ELISA, RA sera bound in vitro citrullinated H4. Citrullinated H4 14-34 and 31-50 peptides detected antibodies in 67% and 63% of RA sera and in less than 5% of controls; antibody titre was correlated with anti-CCP2. CONCLUSIONS Citrullinated H4 from activated neutrophils and NETs is a target of antibodies in RA, and synthetic citrullinated H4-derived peptides are a new substrate for ACPA detection. As NETosis can generate antigens for ACPA, these data suggest a novel connection between innate and adaptive immunity in RA.
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Affiliation(s)
- Federico Pratesi
- Clinical Immunology and Allergy Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Ilaria Dioni
- Laboratory of Peptide and Protein Chemistry and Biology, Department of Pharmaceutical Sciences, University of Florence, Florence, Italy
| | - Cristina Tommasi
- Clinical Immunology and Allergy Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | | | | | | | - Francesca Boscaro
- Mass Spectrometry Center (CISM), University of Florence, Florence, Italy
| | - Filomena Panza
- Clinical Immunology and Allergy Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Ilaria Puxeddu
- Clinical Immunology and Allergy Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Paolo Rovero
- Laboratory of Peptide and Protein Chemistry and Biology, Department of Pharmaceutical Sciences, University of Florence, Florence, Italy Toscana Biomarkers, Siena, Italy
| | - Paola Migliorini
- Clinical Immunology and Allergy Unit, Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy Toscana Biomarkers, Siena, Italy
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962
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Pang L, Hayes CP, Buac K, Yoo DG, Rada B. Pseudogout-Associated Inflammatory Calcium Pyrophosphate Dihydrate Microcrystals Induce Formation of Neutrophil Extracellular Traps. THE JOURNAL OF IMMUNOLOGY 2013; 190:6488-500. [DOI: 10.4049/jimmunol.1203215] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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963
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Neutrophil histone modification by peptidylarginine deiminase 4 is critical for deep vein thrombosis in mice. Proc Natl Acad Sci U S A 2013; 110:8674-9. [PMID: 23650392 DOI: 10.1073/pnas.1301059110] [Citation(s) in RCA: 400] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Deep vein thrombosis and pulmonary embolism are major health problems associated with high mortality. Recently, DNA-based neutrophil extracellular traps (NETs) resulting from the release of decondensed chromatin, were found to be part of the thrombus scaffold and to promote coagulation. However, the significance of nuclear decondensation and NET generation in thrombosis is largely unknown. To address this, we adopted a stenosis model of deep vein thrombosis and analyzed venous thrombi in peptidylarginine deiminase 4 (PAD4)-deficient mice that cannot citrullinate histones, a process required for chromatin decondensation and NET formation. Intriguingly, less than 10% of PAD4(-/-) mice produced a thrombus 48 h after inferior vena cava stenosis whereas 90% of wild-type mice did. Neutrophils were abundantly present in thrombi formed in both groups, whereas extracellular citrullinated histones were seen only in thrombi from wild-type mice. Bone marrow chimera experiments indicated that PAD4 in hematopoietic cells was the source of the prothrombotic effect in deep vein thrombosis. Thrombosis could be rescued by infusion of wild-type neutrophils, suggesting that neutrophil PAD4 was important and sufficient. Endothelial activation and platelet aggregation were normal in PAD4(-/-) mice, as was hemostatic potential determined by bleeding time and platelet plug formation after venous injury. Our results show that PAD4-mediated chromatin decondensation in the neutrophil is crucial for pathological venous thrombosis and present neutrophil activation and PAD4 as potential drug targets for deep vein thrombosis.
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964
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Wildeman E, Pires MM. Facile fluorescence-based detection of PAD4-mediated citrullination. Chembiochem 2013; 14:963-7. [PMID: 23640867 DOI: 10.1002/cbic.201300173] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Indexed: 11/10/2022]
Abstract
The post-translational modifications of histone proteins are highly diverse and dynamic processes. It is becoming increasingly evident that modifying histone proteins can have a direct influence on both cellular homeostasis and disease states. Protein arginine deiminase 4 (PAD4) is an enzyme that converts peptidyl-arginine to citrulline. The overexpression of PAD4 has been found in numerous types of human cancer and autoimmune diseases. We report a new, facile, fluorescence-based assay for the detection of PAD4 activity that exploits the substrate specificity of trypsin to monitor the citrullination reaction carried out by PAD4 based on the fact that, upon citrullination, the positively charged arginine side chain is converted to the neutral citrulline. We show that the assay can be performed rapidly with readily available reagents and that it responds accordingly to a known PAD4 inhibitor.
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Affiliation(s)
- Erin Wildeman
- Department of Chemistry, Lehigh University, 6 E. Packer Ave., Bethlehem, PA 18015, USA
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965
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Radic M, Marion TN. Neutrophil extracellular chromatin traps connect innate immune response to autoimmunity. Semin Immunopathol 2013; 35:465-80. [DOI: 10.1007/s00281-013-0376-6] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 03/18/2013] [Indexed: 01/08/2023]
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966
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Brooks WH. Increased polyamines alter chromatin and stabilize autoantigens in autoimmune diseases. Front Immunol 2013; 4:91. [PMID: 23616785 PMCID: PMC3627976 DOI: 10.3389/fimmu.2013.00091] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 04/04/2013] [Indexed: 11/13/2022] Open
Abstract
Polyamines are small cations with unique combinations of charge and length that give them many putative interactions in cells. Polyamines are essential since they are involved in replication, transcription, translation, and stabilization of macro-molecular complexes. However, polyamine synthesis competes with cellular methylation for S-adenosylmethionine, the methyl donor. Also, polyamine degradation can generate reactive molecules like acrolein. Therefore, polyamine levels are tightly controlled. This control may be compromised in autoimmune diseases since elevated polyamine levels are seen in autoimmune diseases. Here a hypothesis is presented explaining how polyamines can stabilize autoantigens. In addition, the hypothesis explains how polyamines can inappropriately activate enzymes involved in NETosis, a process in which chromatin is modified and extruded from cells as extracellular traps that bind pathogens during an immune response. This polyamine-induced enzymatic activity can lead to an increase in NETosis resulting in release of autoantigenic material and tissue damage.
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Affiliation(s)
- Wesley H Brooks
- Department of Chemistry, University of South Florida Tampa, FL, USA
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967
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Jaillon S, Galdiero MR, Del Prete D, Cassatella MA, Garlanda C, Mantovani A. Neutrophils in innate and adaptive immunity. Semin Immunopathol 2013; 35:377-94. [PMID: 23553214 DOI: 10.1007/s00281-013-0374-8] [Citation(s) in RCA: 197] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 03/18/2013] [Indexed: 12/23/2022]
Abstract
Neutrophils have long been viewed as short-lived cells crucial for the elimination of extracellular pathogens, possessing a limited role in the orchestration of the immune response. This dogma has been challenged by recent lines of evidence demonstrating the expression of an increasing number of cytokines and effector molecules by neutrophils. Moreover, in analogy with their "big brother" macrophages, neutrophils integrate the environmental signals and can be polarized towards an antitumoural or protumoural phenotype. Neutrophils are a major source of humoral fluid phase pattern recognition molecules and thus contribute to the humoral arm of innate immunity. Neutrophils cross talk and shape the maturation and effector functions of other leukocytes in a direct or indirect manner, through cell-cell contact or cytokine production, respectively. Therefore, neutrophils are integrated in the activation and regulation of the innate and adaptive immune system and play an important role in the resolution or exacerbation of diverse pathologies, including infections, chronic inflammation, autoimmunity and cancer.
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Affiliation(s)
- Sébastien Jaillon
- Humanitas Clinical and Research Center, via Manzoni 56, 20089 Rozzano, Milan, Italy
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968
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Mohanan S, Horibata S, McElwee JL, Dannenberg AJ, Coonrod SA. Identification of macrophage extracellular trap-like structures in mammary gland adipose tissue: a preliminary study. Front Immunol 2013; 4:67. [PMID: 23508122 PMCID: PMC3600535 DOI: 10.3389/fimmu.2013.00067] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 03/01/2013] [Indexed: 12/31/2022] Open
Abstract
PAD4-mediated hypercitrullination of histone H4 arginine 3 (H4R3) has been previously found to promote the formation of Neutrophil Extracellular Traps in inflamed tissues and the resulting histone H4 citrulline 3 (H4Cit3) modification is thought to play a key role in extracellular trap (ET) formation by promoting chromatin decondensation. In addition to neutrophils, macrophages have also recently been found to generate functional extracellular traps (METs). However, a role for PADs in ET formation in macrophages has not been previously described. Transcripts for PAD2 and PAD4 are found in mature macrophages and these cells can be induced to citrullinate proteins, thus raising the possibility that PADs may play a direct role in ET formation in macrophages via histone hypercitrullination. In breast and visceral white adipose tissue from obese patients, infiltrating macrophages are often seen to surround dead adipocytes forming characteristic “crown-like structures” (CLS) and the presence of these lesions is associated with increased levels of inflammatory mediators. In light of these observations, we have initiated studies to test whether PADs are expressed in CLS macrophages and whether these macrophages might form METs. Our preliminary findings show that PAD2 (and to a lesser extent, PAD4) is expressed in both in the macrophage cell line (RAW 264.7) and in CLS lesions. Additionally, we provide evidence that macrophage-derived extracellular histones are seen around presumptive macrophages within CLS lesions and that these histones contain the H4Cit3 modification. These initial findings support our hypothesis that obesity-induced adipose tissue inflammation promotes the formation of METs within CLS lesions via PAD-mediated histone hypercitrullination. Subsequent studies are underway to further validate these findings and to investigate the role in PAD-mediated MET formation in CLS function in the mammary gland.
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Affiliation(s)
- Sunish Mohanan
- Department of Biomedical Sciences, Baker Institute for Animal Health, Cornell University Ithaca, NY, USA
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969
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de Chaisemartin L, Hayemb G, Chollet-Martin S. When neutrophils cast their nets. Joint Bone Spine 2013; 80:124-6. [DOI: 10.1016/j.jbspin.2013.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2012] [Indexed: 11/26/2022]
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970
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Almyroudis NG, Grimm MJ, Davidson BA, Röhm M, Urban CF, Segal BH. NETosis and NADPH oxidase: at the intersection of host defense, inflammation, and injury. Front Immunol 2013; 4:45. [PMID: 23459634 PMCID: PMC3585429 DOI: 10.3389/fimmu.2013.00045] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 02/07/2013] [Indexed: 01/13/2023] Open
Abstract
Neutrophils are armed with both oxidant-dependent and -independent pathways for killing pathogens. Activation of the phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase constitutes an emergency response to infectious threat and results in the generation of antimicrobial reactive oxidants. In addition, NADPH oxidase activation in neutrophils is linked to activation of granular proteases and generation of neutrophil extracellular traps (NETs). NETosis involves the release of nuclear and granular components that can target extracellular pathogens. NETosis is activated during microbial threat and in certain conditions mimicking sepsis, and can result in both augmented host defense and inflammatory injury. In contrast, apoptosis, the physiological form of neutrophil death, not only leads to non-inflammatory cell death but also contributes to alleviate inflammation. Although there are significant gaps in knowledge regarding the specific contribution of NETs to host defense, we speculate that the coordinated activation of NADPH oxidase and NETosis maximizes microbial killing. Work in engineered mice and limited patient experience point to varying susceptibility of bacterial and fungal pathogens to NADPH oxidase versus NET constituents. Since reactive oxidants and NET constituents can injure host tissue, it is important that these pathways be tightly regulated. Recent work supports a role for NETosis in both acute lung injury and in autoimmunity. Knowledge gained about mechanisms that modulate NETosis may lead to novel therapeutic approaches to limit inflammation-associated injury.
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Affiliation(s)
- Nikolaos G Almyroudis
- Division of Infectious Diseases, Department of Medicine, University at Buffalo School of Medicine Buffalo, NY, USA ; Department of Medicine, Roswell Park Cancer Institute Buffalo, NY, USA
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971
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Neeli I, Radic M. Opposition between PKC isoforms regulates histone deimination and neutrophil extracellular chromatin release. Front Immunol 2013; 4:38. [PMID: 23430963 PMCID: PMC3576869 DOI: 10.3389/fimmu.2013.00038] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 01/31/2013] [Indexed: 11/29/2022] Open
Abstract
In response to inflammation, neutrophils deiminate histones and externalize chromatin. Neutrophil extracellular traps (NETs) are an innate immune defense mechanism, yet NETs also may aggravate chronic inflammatory and autoimmune disorders. Activation of peptidylarginine deiminase 4 (PAD4) is associated with NET release (NETosis) but the precise mechanisms of PAD4 regulation are unknown. We observed that, in human neutrophils, calcium ionophore induced histone deimination, whereas phorbol myristate acetate (PMA), an activator of protein kinase C (PKC), suppressed ionophore-induced deimination. Conversely, low doses of chelerythrine and sanguinarine, two inhibitors of PKC, reversed PMA inhibition and enhanced ionophore-stimulated deimination. In addition, a peptide inhibitor of PKCα superinduced ionophore activation of PAD4, thus identifying PKCα as the PMA-induced inhibitor of PAD4. At higher doses, chelerythrine, sanguinarine, and structurally unrelated PKC inhibitors blocked histone deimination, suggesting that a different PKC isoform activates histone deimination. We identify PKCζ as activator of PAD4 because a specific peptide inhibitor of this PKC isoform suppressed histone deimination. Confocal microscopy confirmed that, in the presence of PMA, NETosis proceeds without detectable histone deimination, and that ionophore cooperates with PMA to induce more extensive NET release. Broad inhibition of PKC by chelerythrine or specific inhibition of PKCζ suppressed NETosis. Our observations thus reveal an intricate antagonism between PKC isoforms in the regulation of histone deimination, identify a dominant role for PKCα in the repression of histone deimination, and assign essential functions to PKCζ in the activation of PAD4 and the execution of NETosis. The precise balance between opposing PKC isoforms in the regulation of NETosis affirms the idea that NET release underlies specific and vitally important evolutionary selection pressures.
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Affiliation(s)
- Indira Neeli
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center Memphis, TN, USA
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972
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Wei L, Wasilewski E, Chakka SK, Bello AM, Moscarello MA, Kotra LP. Novel Inhibitors of Protein Arginine Deiminase with Potential Activity in Multiple Sclerosis Animal Model. J Med Chem 2013; 56:1715-22. [DOI: 10.1021/jm301755q] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Lianhu Wei
- Center for Molecular Design
and Preformulations, Toronto General Research Institute, University
Health Network, Toronto, Ontario M5G 2C4, Canada
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
| | - Ewa Wasilewski
- Center for Molecular Design
and Preformulations, Toronto General Research Institute, University
Health Network, Toronto, Ontario M5G 2C4, Canada
| | - Sai Kumar Chakka
- Center for Molecular Design
and Preformulations, Toronto General Research Institute, University
Health Network, Toronto, Ontario M5G 2C4, Canada
| | - Angelica M. Bello
- Center for Molecular Design
and Preformulations, Toronto General Research Institute, University
Health Network, Toronto, Ontario M5G 2C4, Canada
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
| | - Mario A. Moscarello
- The Research Institute, Hospital
for Sick Children, Toronto, Ontario, Canada
| | - Lakshmi P. Kotra
- Center for Molecular Design
and Preformulations, Toronto General Research Institute, University
Health Network, Toronto, Ontario M5G 2C4, Canada
- Department of Pharmaceutical Sciences,
Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College
Street, Toronto, Ontario M5S 3M2, Canada
- McLaughlin Center for Molecular
Medicine, University of Toronto, Toronto, Ontario, Canada
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973
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Brinkmann V, Zychlinsky A. Neutrophil extracellular traps: is immunity the second function of chromatin? ACTA ACUST UNITED AC 2013; 198:773-83. [PMID: 22945932 PMCID: PMC3432757 DOI: 10.1083/jcb.201203170] [Citation(s) in RCA: 698] [Impact Index Per Article: 63.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neutrophil extracellular traps (NETs) are made of processed chromatin bound to granular and selected cytoplasmic proteins. NETs are released by white blood cells called neutrophils, maybe as a last resort, to control microbial infections. This release of chromatin is the result of a unique form of cell death, dubbed “NETosis.” Here we review our understanding of how NETs are made, their function in infections and as danger signals, and their emerging importance in autoimmunity and coagulation.
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Affiliation(s)
- Volker Brinkmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology, 10117 Berlin, Germany.
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974
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Abstract
Neutrophils are the first line of defense of the immune system against infection. Among their weaponry, they have the ability to mix and extrude their DNA and bactericidal molecules creating NET-like structures in a unique type of cell death called NETosis. This process is important in order to control extracellular infections limiting collateral damage. Its aberrant function has been implicated in several human diseases including sepsis and autoimmune disease. The purpose of the present paper is to give a general introduction to this concept.
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975
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van Beers JJ, Zendman AJ, Raijmakers R, Stammen-Vogelzangs J, Pruijn GJ. Peptidylarginine deiminase expression and activity in PAD2 knock-out and PAD4-low mice. Biochimie 2013; 95:299-308. [DOI: 10.1016/j.biochi.2012.09.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2012] [Accepted: 09/24/2012] [Indexed: 11/16/2022]
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976
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McDonald B, Urrutia R, Yipp BG, Jenne CN, Kubes P. Intravascular neutrophil extracellular traps capture bacteria from the bloodstream during sepsis. Cell Host Microbe 2013; 12:324-33. [PMID: 22980329 DOI: 10.1016/j.chom.2012.06.011] [Citation(s) in RCA: 538] [Impact Index Per Article: 48.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Revised: 05/27/2012] [Accepted: 06/29/2012] [Indexed: 12/11/2022]
Abstract
During the systemic inflammatory response of severe sepsis, neutrophils accumulate in the liver microcirculation, but their functional significance is largely unknown. We show that neutrophils migrate to liver sinusoids during endotoxemia and sepsis where they exert protective effects by releasing neutrophil extracellular traps (NETs), which are DNA-based structures that capture and eliminate microbes. NETs released into the vasculature ensnare bacteria from the bloodstream and prevent dissemination. NET production requires platelet-neutrophil interactions and can be inhibited by platelet depletion or disruption of integrin-mediated platelet-neutrophil binding. During sepsis, NET release increases bacterial trapping by 4-fold (beyond the basal level provided by resident intravascular macrophages). Blocking NET formation reduces the capture of circulating bacteria during sepsis, resulting in increased dissemination to distant organs. Thus, NETs ensnare circulating bacteria and provide intravascular immunity that protects against bacterial dissemination during septic infections.
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Affiliation(s)
- Braedon McDonald
- Calvin, Phoebe, and Joan Snyder Institute for Chronic Disease, Department of Physiology and Pharmacology, University of Calgary, Calgary, AB T2N 4N1, Canada
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977
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Cheng OZ, Palaniyar N. NET balancing: a problem in inflammatory lung diseases. Front Immunol 2013; 4:1. [PMID: 23355837 PMCID: PMC3553399 DOI: 10.3389/fimmu.2013.00001] [Citation(s) in RCA: 227] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 01/01/2013] [Indexed: 12/12/2022] Open
Abstract
Neutrophil extracellular traps (NETs) are beneficial antimicrobial defense structures that can help fight against invading pathogens in the host. However, recent studies reveal that NETs exert adverse effects in a number of diseases including those of the lung. Many inflammatory lung diseases are characterized with a massive influx of neutrophils into the airways. Neutrophils contribute to the pathology of these diseases. To date, NETs have been identified in the lungs of cystic fibrosis (CF), acute lung injury (ALI), allergic asthma, and lungs infected with bacteria, virus, or fungi. These microbes and several host factors can stimulate NET formation, or NETosis. Different forms of NETosis have been identified and are dependent on varying types of stimuli. All of these pathways however appear to result in the formation of NETs that contain DNA, modified extracellular histones, proteases, and cytotoxic enzymes. Some of the NET components are immunogenic and damaging to host tissue. Innate immune collectins, such as pulmonary surfactant protein D (SP-D), bind NETs, and enhance the clearance of dying cells and DNA by alveolar macrophages. In many inflammatory lung diseases, bronchoalveolar SP-D levels are altered and its deficiency results in the accumulation of DNA in the lungs. Some of the other therapeutic molecules under consideration for treating NET-related diseases include DNases, antiproteases, myeloperoxidase (MPO) inhibitors, peptidylarginine deiminase-4 inhibitors, and anti-histone antibodies. NETs could provide important biological advantage for the host to fight against certain microbial infections. However, too much of a good thing can be a bad thing. Maintaining the right balance of NET formation and reducing the amount of NETs that accumulate in tissues are essential for harnessing the power of NETs with minimal damage to the hosts.
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Affiliation(s)
- Olivia Z Cheng
- Program in Physiology and Experimental Medicine, Lung Innate Immunity Research Laboratory, SickKids Research Institute Toronto, ON, Canada ; Department of Laboratory Medicine and Pathobiology, University of Toronto Toronto, ON, Canada
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978
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Darrah E, Andrade F. NETs: the missing link between cell death and systemic autoimmune diseases? Front Immunol 2013; 3:428. [PMID: 23335928 PMCID: PMC3547286 DOI: 10.3389/fimmu.2012.00428] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Accepted: 12/26/2012] [Indexed: 12/22/2022] Open
Abstract
For almost 20 years, apoptosis and secondary necrosis have been considered the major source of autoantigens and endogenous adjuvants in the pathogenic model of systemic autoimmune diseases. This focus is justified in part because initial evidence in systemic lupus erythematosus (SLE) guided investigators toward the study of apoptosis, but also because other forms of cell death were unknown. To date, it is known that many other forms of cell death occur, and that they vary in their capacity to stimulate as well as inhibit the immune system. Among these, NETosis (an antimicrobial form of death in neutrophils in which nuclear material is extruded from the cell forming extracellular traps), is gaining major interest as a process that may trigger some of the immune features found in SLE, granulomatosis with polyangiitis (formerly Wegener’s granulomatosis) and Felty’s syndrome. Although there have been volumes of very compelling studies published on the role of cell death in autoimmunity, no unifying theory has been adopted nor have any successful therapeutics been developed based on this important pathway. The recent inclusion of NETosis into the pathogenic model of autoimmune diseases certainly adds novel insights into this paradigm, but also reveals a previously unappreciated level of complexity and raises many new questions. This review discusses the role of cell death in systemic autoimmune diseases with a focus on apoptosis and NETosis, highlights the current short comings in our understanding of the vast complexity of cell death, and considers the potential shift in the cell death paradigm in autoimmunity. Understanding this complexity is critical in order to develop tools to clearly define the death pathways that are active in systemic autoimmune diseases, identify drivers of disease propagation, and develop novel therapeutics.
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Affiliation(s)
- Erika Darrah
- Division of Rheumatology, Department of Medicine, Johns Hopkins University School of Medicine Baltimore, MD, USA
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979
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Rada B, Jendrysik MA, Pang L, Hayes CP, Yoo DG, Park JJ, Moskowitz SM, Malech HL, Leto TL. Pyocyanin-enhanced neutrophil extracellular trap formation requires the NADPH oxidase. PLoS One 2013; 8:e54205. [PMID: 23342104 PMCID: PMC3544820 DOI: 10.1371/journal.pone.0054205] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 11/26/2012] [Indexed: 11/26/2022] Open
Abstract
Beyond intracellular killing, a novel neutrophil-based antimicrobial mechanism has been recently discovered: entrapment and killing by neutrophil extracellular traps (NETs). NETs consist of extruded nuclear DNA webs decorated with granule proteins. Although NET formation is an important innate immune mechanism, uncontrolled NET release damages host tissues and has been linked to several diseases including cystic fibrosis (CF). The major CF airway pathogen Pseudomonas aeruginosa establishes chronic infection. Pseudomonas imbedded within biofilms is protected against the immune system, but maintains chronic inflammation that worsens disease symptoms. Aberrant NET release from recruited neutrophils was found in CF, but the underlying mechanisms remain unclear. One of the most important Pseudomonas virulence factors is pyocyanin, a redox-active pigment that has been associated with diminished lung function in CF. Here we show that pyocyanin promotes NET formation in a time- and dose-dependent manner. Most CF Pseudomonas clinical isolates tested produce pyocyanin in vitro. Pyocyanin-derived reactive oxygen species are required for its NET release. Inhibitor experiments demonstrated involvement of Jun N-terminal Kinase (JNK) and phosphatidylinositol 3-Kinase (PI3K) in pyocyanin-induced NET formation. Pyocyanin-induced NETs also require the NADPH oxidase because NET release in chronic granulomatous disease neutrophils was greatly reduced. Comparison of neutrophils from gp91phox- and p47phox-deficient patients revealed that pyocyanin-triggered NET formation is proportional to their residual superoxide production. Our studies identify pyocyanin as the first secreted bacterial toxin that enhances NET formation. The involvement of NADPH oxidase in pyocyanin-induced NET formation represents a novel mechanism of pyocyanin toxicity.
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Affiliation(s)
- Balázs Rada
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
- * E-mail: (TLL); (BR)
| | - Meghan A. Jendrysik
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Lan Pang
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Craig P. Hayes
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Dae-goon Yoo
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Jonathan J. Park
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Samuel M. Moskowitz
- Department of Pediatrics, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Harry L. Malech
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
| | - Thomas L. Leto
- Laboratory of Host Defenses, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, United States of America
- * E-mail: (TLL); (BR)
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980
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Tadie JM, Bae HB, Jiang S, Park DW, Bell CP, Yang H, Pittet JF, Tracey K, Thannickal VJ, Abraham E, Zmijewski JW. HMGB1 promotes neutrophil extracellular trap formation through interactions with Toll-like receptor 4. Am J Physiol Lung Cell Mol Physiol 2013; 304:L342-9. [PMID: 23316068 DOI: 10.1152/ajplung.00151.2012] [Citation(s) in RCA: 246] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Although neutrophil extracellular traps (NETs) form to prevent dissemination of pathogenic microorganisms, excessive release of DNA and DNA-associated proteins can also perpetuate sterile inflammation. In this study, we found that the danger-associated molecular pattern protein high-mobility group box 1 (HMGB1) can induce NET formation. NET formation was found after exposure of wild-type and receptor for advanced glycation end products-deficient neutrophil to HMGB1, whereas deficiency of Toll-like receptor (TLR)4 diminished the ability of neutrophils to produce NETs. Incubation of neutrophils with HMGB1 significantly increased the amount of DNA and histone 3 released as well as intracellular histone 3 citrullination, a signaling event that precedes chromatin decondensation. In vivo, neutrophils isolated from bronchoalveolar lavages of mice exposed to LPS and HMGB1 showed consistently greater ability to produce NETs compared with pulmonary neutrophils from mice that received LPS alone. In contrast, mice treated with LPS and neutralizing antibody to HMGB1 had decreased amounts of the inflammatory cytokines TNF-α and macrophage inflammatory protein 2, as well as of free DNA and histone 3 in bronchoalveolar lavage fluids. Airway neutrophils from LPS-exposed mice that had been treated with anti-HMGB1 antibodies showed decreased citrullination of histone 3. These results demonstrate that interactions between HMGB1 and TLR4 enhance the formation of NETs and provide a novel mechanism through which HMGB1 may contribute to the severity of neutrophil-associated inflammatory conditions.
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Affiliation(s)
- Jean-Marc Tadie
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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981
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Knight JS, Kaplan MJ. Lupus neutrophils: 'NET' gain in understanding lupus pathogenesis. Curr Opin Rheumatol 2013; 24:441-50. [PMID: 22617827 DOI: 10.1097/bor.0b013e3283546703] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW Historically, researchers have focused on the role of adaptive immunity in lupus pathogenesis; recently, however, there has been renewed interest in the contributions of a prototypical innate immune cell - the neutrophil. RECENT FINDINGS Neutrophil extracellular traps (NETs) are released via a novel form of cell death called NETosis. NETs, consisting of a chromatin meshwork decorated with antimicrobial peptides, play an important role in the innate response to microbial infections. Some lupus patients do not clear NETs normally, a phenotype that correlates with disease activity. Further, lupus neutrophils - and, in particular, an aberrant subset called low-density granulocytes - have an increased propensity to undergo NETosis. Both interferon alpha (IFNα) and immune complexes are potential triggers of enhanced NETosis in lupus patients. SUMMARY NETs are a potent stimulus for IFNα release by plasmacytoid dendritic cells, and, as such, may play an important role in propagation of the lupus phenotype. NETs can also directly damage tissues - including the endothelium - with implications for lupus nephritis and accelerated atherosclerosis. Whether aberrant NETosis is sufficient to trigger systemic lupus erythematosus, and whether inhibition of NETosis can ameliorate clinical manifestations of lupus, are open questions, and will be exciting topics of future research.
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Affiliation(s)
- Jason S Knight
- Division of Rheumatology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
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982
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Nakazawa D, Tomaru U, Suzuki A, Masuda S, Hasegawa R, Kobayashi T, Nishio S, Kasahara M, Ishizu A. Abnormal conformation and impaired degradation of propylthiouracil-induced neutrophil extracellular traps: implications of disordered neutrophil extracellular traps in a rat model of myeloperoxidase antineutrophil cytoplasmic antibody-associated vasculitis. ACTA ACUST UNITED AC 2013; 64:3779-87. [PMID: 22777766 DOI: 10.1002/art.34619] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Neutrophil extracellular traps (NETs) are composed of DNA and antimicrobial proteins, including myeloperoxidase (MPO). Recent studies have demonstrated that impaired regulation of NETs could trigger an autoimmune response. Propylthiouracil (PTU), an antithyroid drug, is associated with a risk of MPO antineutrophil cytoplasmic antibody (ANCA) production and MPO ANCA-associated vasculitis (MPO AAV). This study was undertaken to clarify the mechanism of MPO ANCA production, using the PTU-induced model of MPO AAV. METHODS NETs were induced by treating human neutrophils with phorbol myristate acetate (PMA) in vitro. We examined whether the addition of PTU influenced the NET formation induced by PMA and the degradation of NETs by DNase I, which is regarded as a regulator of NETs. Furthermore, we examined whether NETs generated by the combination of PMA and PTU induced MPO ANCA and MPO AAV in vivo in rats. RESULTS When NETs were induced by PMA with PTU using human neutrophils in vitro, abnormal conformation of NETs was observed. Interestingly, the abnormal NETs were hardly digested by DNase I. Moreover, rats immunized with the abnormal NETs, which had been induced by PMA with PTU using rat neutrophils, produced MPO ANCA and developed pulmonary capillaritis. When rats were given oral PTU with intraperitoneal injection of PMA, pauci-immune glomerulonephritis and pulmonary capillaritis occurred with MPO ANCA production in the serum. CONCLUSION Our findings indicate that abnormal conformation and impaired degradation of NETs induced by PTU are involved in the pathogenesis of PTU-induced MPO ANCA production and MPO AAV. These findings suggest that disordered NETs can be critically implicated in the pathogenesis of MPO AAV.
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983
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984
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Jang B, Shin SJ. Peptidylarginine Deiminase and Citrullination: Potential Therapeutic Targets for Inflammatory Diseases. ACTA ACUST UNITED AC 2013. [DOI: 10.4167/jbv.2013.43.3.159] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Byungki Jang
- Department of Microbiology and Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, Korea
| | - Sung Jae Shin
- Department of Microbiology and Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul, Korea
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985
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Abstract
Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by an overproduction of autoantibodies. The loss of self-tolerance in SLE is believed to be caused by the dysregulation of both innate and adaptive immune systems. Neutrophils, the most abundant effector cells of innate immunity, have long been shown to be associated with SLE. However, their role in the pathogenesis of SLE was not clear until recent studies discovered abnormal regulation of neutrophil extracellular traps (NETs) in SLE patients. NETs are web-like structures composed of chromatin backbones and granular molecules. They are released by activated neutrophils through a process called "NETosis". Nets were first described in 2004 as a novel host defense mechanism to trap and kill foreign pathogens. Recent evidence shows that NETs also participate in the pathogenesis of a variety of inflammatory and autoimmune diseases, including SLE. An imbalance between NET formation and clearance in SLE patients may play a prominent role in the perpetuation of autoimmunity and the exacerbation of disease, as well as the induction of end-organ manifestations. This review summarizes the current findings regarding the contribution of NETs to the pathogenesis of SLE.
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Affiliation(s)
- Yangsheng Yu
- Departments of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198, USA
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986
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987
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Neutrophil Extracellular Trap in Human Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 756:1-8. [DOI: 10.1007/978-94-007-4549-0_1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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988
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Knight JS, Carmona-Rivera C, Kaplan MJ. Proteins derived from neutrophil extracellular traps may serve as self-antigens and mediate organ damage in autoimmune diseases. Front Immunol 2012; 3:380. [PMID: 23248629 PMCID: PMC3521997 DOI: 10.3389/fimmu.2012.00380] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 11/28/2012] [Indexed: 12/19/2022] Open
Abstract
Neutrophils are the most abundant leukocytes in circulation and represent one of the first lines of defense against invading pathogens. Neutrophils possess a vast arsenal of antimicrobial proteins, which can be released from the cell by a death program termed NETosis. Neutrophil extracellular traps (NETs) are web-like structures consisting of decondensed chromatin decorated with granular and cytosolic proteins. Both exuberant NETosis and impaired clearance of NETs have been implicated in the organ damage of autoimmune diseases, such as systemic lupus erythematosus (SLE), small vessel vasculitis (SVV), and psoriasis. NETs may also represent an important source of modified autoantigens in SLE and SVV. Here, we review the autoimmune diseases linked to NETosis, with a focus on how modified proteins externalized on NETs may trigger loss of immune tolerance and promote organ damage.
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Affiliation(s)
- Jason S Knight
- Division of Rheumatology, Department of Internal Medicine, University of Michigan Medical School Ann Arbor, MI, USA
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989
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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: 428] [Impact Index Per Article: 35.7] [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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990
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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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991
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Caielli S, Banchereau J, Pascual V. Neutrophils come of age in chronic inflammation. Curr Opin Immunol 2012; 24:671-7. [PMID: 23127555 PMCID: PMC3684162 DOI: 10.1016/j.coi.2012.09.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 09/28/2012] [Accepted: 09/30/2012] [Indexed: 12/21/2022]
Abstract
Neutrophils have long been known to participate in acute inflammation, but a role in chronic inflammatory and autoimmune diseases is now emerging. These cells are key players in the recognition and elimination of pathogens, but they also sense self components, including nucleic acids and products of sterile tissue damage. While this normally contributes to tissue repair, it can also lead to the release of highly immunogenic products that can trigger and/or amplify autoimmune pathogenic loops. Understanding the mechanisms that underlie neutrophil activation, migration, survival and their various forms of death in health and disease might provide us with new approaches to treat chronic inflammatory conditions.
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Affiliation(s)
- Simone Caielli
- Baylor Institute for Immunology Research, Dallas, TX 75204, USA
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992
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Abstract
Peptidylarginine deiminases, or PADs, convert arginine residues to the non-ribosomally encoded amino acid citrulline in a variety of protein substrates. PAD4 is expressed in granulocytes and is essential for the formation of neutrophil extracellular traps (NETs) via PAD4-mediated histone citrullination. Citrullination of histones is thought to promote NET formation by inducing chromatin decondensation and facilitating the expulsion of chromosomal DNA that is coated with antimicrobial molecules. Numerous stimuli have been reported to lead to PAD4 activation and NET formation. However, how this signaling process proceeds and how PAD4 becomes activated in cells is largely unknown. Herein, we describe the various stimuli and signaling pathways that have been implicated in PAD4 activation and NET formation, including the role of reactive oxygen species generation. To provide a foundation for the above discussion, we first describe PAD4 structure and function, and how these studies led to the development of PAD-specific inhibitors. A comprehensive survey of the receptors and signaling pathways that regulate PAD4 activation will be important for our understanding of innate immunity, and the identification of signaling intermediates in PAD4 activation may also lead to the generation of pharmaceuticals to target NET-related pathogenesis.
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Affiliation(s)
- Amanda S. Rohrbach
- Department of Chemical Physiology, The Scripps Research InstituteLa Jolla, CA, USA
| | - Daniel J. Slade
- Department of Chemical Physiology, The Scripps Research InstituteLa Jolla, CA, USA
| | - Paul R. Thompson
- Department of Chemical Physiology, The Scripps Research InstituteLa Jolla, CA, USA
| | - Kerri A. Mowen
- Department of Chemical Physiology, The Scripps Research InstituteLa Jolla, CA, USA
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993
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Maruyama K, Fukasaka M, Vandenbon A, Saitoh T, Kawasaki T, Kondo T, Yokoyama KK, Kidoya H, Takakura N, Standley D, Takeuchi O, Akira S. The transcription factor Jdp2 controls bone homeostasis and antibacterial immunity by regulating osteoclast and neutrophil differentiation. Immunity 2012. [PMID: 23200825 DOI: 10.1016/j.immuni.2012.08.022] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Jdp2 is an AP-1 family transcription factor that regulates the epigenetic status of histones. Previous in vitro studies revealed that Jdp2 is involved in osteoclastogenesis. However, the roles of Jdp2 in vivo and its pleiotropic functions are largely unknown. Here we generated Jdp2(-/-) mice and discovered its crucial roles not only in bone metabolism but also in differentiation of neutrophils. Jdp2(-/-) mice exhibited osteopetrosis resulting from impaired osteoclastogenesis. Jdp2(-/-) neutrophils were morphologically normal but had impaired surface expression of Ly6G, bactericidal function, and apoptosis. We also found that ATF3 was an inhibitor of neutrophil differentiation and that Jdp2 directly suppresses its expression via inhibition of histone acetylation. Strikingly, Jdp2(-/-) mice were highly susceptible to Staphylococcus aureus and Candida albicans infection. Thus, Jdp2 plays pivotal roles in in vivo bone homeostasis and host defense by regulating osteoclast and neutrophil differentiation.
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Affiliation(s)
- Kenta Maruyama
- Laboratory of Host Defense, Osaka University, Osaka, Japan
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994
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Yipp BG, Petri B, Salina D, Jenne CN, Scott BNV, Zbytnuik LD, Pittman K, Asaduzzaman M, Wu K, Meijndert HC, Malawista SE, de Boisfleury Chevance A, Zhang K, Conly J, Kubes P. Infection-induced NETosis is a dynamic process involving neutrophil multitasking in vivo. Nat Med 2012; 18:1386-93. [PMID: 22922410 PMCID: PMC4529131 DOI: 10.1038/nm.2847] [Citation(s) in RCA: 792] [Impact Index Per Article: 66.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Accepted: 05/25/2012] [Indexed: 12/14/2022]
Abstract
Neutrophil extracellular traps (NETs) are released, as neutrophils die in vitro, in a process requiring hours, leaving a temporal gap for invasive microbes to exploit. Functional neutrophils undergoing NETosis have not been documented. During Gram-positive skin infections, we directly visualized live PMN in vivo rapidly releasing NETs, which prevented bacterial dissemination. NETosis occurred during crawling thereby casting large areas of NETs. NET-releasing PMN developed diffuse decondensed nuclei ultimately becoming devoid of DNA. Cells with abnormal nuclei displayed unusual crawling behavior highlighted by erratic pseudopods and hyperpolarization consistent with the nucleus being a fulcrum for crawling. A combined requirement of Tlr2 and complement mediated opsonization tightly regulated NET release. Additionally live human PMN developed decondensed nuclei and formed NETS in vivo and intact anuclear neutrophils were abundant in Gram-positive human abscesses. Therefore early in infection, non-cell death NETosis occurs in vivo during Gram-positive infection in mice and humans.
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Affiliation(s)
- Bryan G Yipp
- Department of Critical Care Medicine, University of Calgary, Calgary, Alberta, Canada. 2The Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Alberta, Canada
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995
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Nakazawa D, Tomaru U, Yamamoto C, Jodo S, Ishizu A. Abundant neutrophil extracellular traps in thrombus of patient with microscopic polyangiitis. Front Immunol 2012; 3:333. [PMID: 23162551 PMCID: PMC3495275 DOI: 10.3389/fimmu.2012.00333] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 10/20/2012] [Indexed: 12/18/2022] Open
Abstract
This is a case study of a patient diagnosed with microscopic polyangiitis (MPA) and complicated with deep vein thrombosis (DVT), who died of respiratory failure despite treatment. Autopsy revealed severe crescentic glomerulonephritis and massive alveolar hemorrhage. The thrombus contained abundant neutrophils. Although it is reported that patients with ANCA-associated vasculitis (AAV) have an increased risk of DVT, it remains elusive why they are prone to thrombosis. A recent study has demonstrated the presence of neutrophil extracellular traps (NETs), a newly recognized mode of neutrophil cell-death, in glomerular crescents of MPA patients. Interestingly, NETs were identified in the thrombus as well as in the glomerular crescents in the present case. When compared to other thrombi unrelated to MPA, the amount of NETs was significantly greater in the MPA patient. On the other hand, NETs are critically involved in thrombogenesis because histones within NETs can bind platelets and blood coagulants. Although this is important in regard to containment of microbes within NETs, excessive NETs could cause thrombosis. The collective findings suggest the possibility that thrombosis could be critically associated with MPA via NETs, and that NETs could be a therapeutic target in MPA patients.
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Affiliation(s)
- Daigo Nakazawa
- Department of Internal Medicine II, Hokkaido University Hospital Sapporo, Japan ; Department of Pathology, Hokkaido University Graduate School of Medicine Sapporo, Japan
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996
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Moscarello MA, Lei H, Mastronardi FG, Winer S, Tsui H, Li Z, Ackerley C, Zhang L, Raijmakers R, Wood DD. Inhibition of peptidyl-arginine deiminases reverses protein-hypercitrullination and disease in mouse models of multiple sclerosis. Dis Model Mech 2012; 6:467-78. [PMID: 23118341 PMCID: PMC3597028 DOI: 10.1242/dmm.010520] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Multiple sclerosis (MS) is the most common CNS-demyelinating disease of humans, showing clinical and pathological heterogeneity and a general resistance to therapy. We first discovered that abnormal myelin hypercitrullination, even in normal-appearing white matter, by peptidylarginine deiminases (PADs) correlates strongly with disease severity and might have an important role in MS progression. Hypercitrullination is known to promote focal demyelination through reduced myelin compaction. Here we report that 2-chloroacetamidine (2CA), a small-molecule, PAD active-site inhibitor, dramatically attenuates disease at any stage in independent neurodegenerative as well as autoimmune MS mouse models. 2CA reduced PAD activity and protein citrullination to pre-disease status. In the autoimmune models, disease induction uniformly induced spontaneous hypercitrullination with citrulline+ epitopes targeted frequently. 2CA rapidly suppressed T cell autoreactivity, clearing brain and spinal cord infiltrates, through selective removal of newly activated T cells. 2CA essentially prevented disease when administered before disease onset or before autoimmune induction, making hypercitrullination, and specifically PAD enzymes, a therapeutic target in MS models and thus possibly in MS.
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Affiliation(s)
- Mario A Moscarello
- Molecular Structure and Function, The Research Institute, Hospital For Sick Children, Toronto, ON M5G 1X8, Canada.
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997
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Leshner M, Wang S, Lewis C, Zheng H, Chen XA, Santy L, Wang Y. PAD4 mediated histone hypercitrullination induces heterochromatin decondensation and chromatin unfolding to form neutrophil extracellular trap-like structures. Front Immunol 2012; 3:307. [PMID: 23060885 PMCID: PMC3463874 DOI: 10.3389/fimmu.2012.00307] [Citation(s) in RCA: 311] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 09/17/2012] [Indexed: 12/28/2022] Open
Abstract
NETosis, the process wherein neutrophils release highly decondensed chromatin called neutrophil extracellular traps (NETs), has gained much attention as an alternative means of killing bacteria. In vivo, NETs are induced by bacteria and pro-inflammatory cytokines. We have reported that peptidylarginine deiminase 4 (PAD4), an enzyme that converts Arg or monomethyl-Arg to citrulline in histones, is essential for NET formation. The areas of extensive chromatin decondensation along the NETs were rich in histone citrullination. Here, upon investigating the effect of global citrullination in cultured cells, we discovered that PAD4 overexpression in osteosarcoma U2OS cells induces extensive chromatin decondensation independent of apoptosis. The highly decondensed chromatin is released to the extracellular space and stained strongly by a histone citrulline-specific antibody. The structure of the decondensed chromatin is reminiscent of NETs but is unique in that it occurs without stimulation of cells with pro-inflammatory cytokines and bacteria. Furthermore, histone citrullination during chromatin decondensation can dissociate heterochromatin protein 1 beta (HP1β) thereby offering a new molecular mechanism for understanding how citrullination regulates chromatin function. Taken together, our study suggests that PAD4 mediated citrullination induces chromatin decondensation, implicating its essential role in NET formation under physiological conditions in neutrophils.
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Affiliation(s)
- Marc Leshner
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, Pennsylvania State University, University Park PA, USA
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998
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Parker H, Dragunow M, Hampton MB, Kettle AJ, Winterbourn CC. Requirements for NADPH oxidase and myeloperoxidase in neutrophil extracellular trap formation differ depending on the stimulus. J Leukoc Biol 2012; 92:841-9. [DOI: 10.1189/jlb.1211601] [Citation(s) in RCA: 282] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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999
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Jang B, Ishigami A, Maruyama N, Carp RI, Kim YS, Choi EK. Peptidylarginine deiminase and protein citrullination in prion diseases: strong evidence of neurodegeneration. Prion 2012; 7:42-6. [PMID: 23022892 DOI: 10.4161/pri.22380] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The post-translational citrullination (deimination) process is mediated by peptidylarginine deiminases (PADs), which convert peptidylarginine into peptidylcitrulline in the presence of high calcium concentrations. Over the past decade, PADs and protein citrullination have been commonly implicated as abnormal pathological features in neurodegeneration and inflammatory responses associated with diseases such as multiple sclerosis, Alzheimer disease and rheumatoid arthritis. Based on this evidence, we investigated the roles of PADs and citrullination in the pathogenesis of prion diseases. Prion diseases (also known as transmissible spongiform encephalopathies) are fatal neurodegenerative diseases that are pathologically well characterized as the accumulation of disease-associated misfolded prion proteins, spongiform changes, glial cell activation and neuronal loss. We previously demonstrated that the upregulation of PAD2, mainly found in reactive astrocytes of infected brains, leads to excessive citrullination, which is correlated with disease progression. Further, we demonstrated that various cytoskeletal and energy metabolism-associated proteins are particularly vulnerable to citrullination. Our recent in vivo and in vitro studies elicited altered functions of enolase as the result of citrullination; these altered functions included reduced enzyme activity, increased protease sensitivity and enhanced plasminogen-binding affinity. These findings suggest that PAD2 and citrullinated proteins may play a key role in the brain pathology of prion diseases. By extension, we believe that abnormal increases in protein citrullination may be strong evidence of neurodegeneration.
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Affiliation(s)
- Byungki Jang
- Laboratory of Cellular Aging and Neurodegeneration, Ilsong Institute of Life Science, Hallym University, Anyang, Republic of Korea
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1000
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Farley K, Stolley JM, Zhao P, Cooley J, Remold-O'Donnell E. A serpinB1 regulatory mechanism is essential for restricting neutrophil extracellular trap generation. THE JOURNAL OF IMMUNOLOGY 2012; 189:4574-81. [PMID: 23002442 DOI: 10.4049/jimmunol.1201167] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
NETosis (neutrophil extracellular trap [NET] generation), a programmed death pathway initiated in mature neutrophils by pathogens and inflammatory mediators, can be a protective process that sequesters microbes and prevents spread of infection, but it can also be a pathological process that causes inflammation and serious tissue injury. Little is known about the regulatory mechanism. Previously, we demonstrated that serpinb1-deficient mice are highly susceptible to pulmonary bacterial and viral infections due to inflammation and tissue injury associated with increased neutrophilic death. In this study, we used in vitro and in vivo approaches to investigate whether SerpinB1 regulates NETosis. We found that serpinb1-deficient bone marrow and lung neutrophils are hypersusceptible to NETosis induced by multiple mediators in both an NADPH-dependent and -independent manner, indicating a deeply rooted regulatory role in NETosis. This role is further supported by increased nuclear expansion (representing chromatin decondensation) of PMA-treated serpinb1-deficient neutrophils compared with wild-type, by migration of SerpinB1 from the cytoplasm to the nucleus of human neutrophils that is coincident with or preceding early conversion of lobulated (segmented) nuclei to delobulated (spherical) morphology, as well as by the finding that exogenous human recombinant SerpinB1 abrogates NET production. NETosis of serpinb1-deficient neutrophils is also increased in vivo during Pseudomonas aeruginosa lung infection. The findings identify a previously unrecognized regulatory mechanism involving SerpinB1 that restricts the production of NETs.
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Affiliation(s)
- Kalamo Farley
- Immune Disease Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
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