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Söderberg D, Kurz T, Motamedi A, Hellmark T, Eriksson P, Segelmark M. Increased levels of neutrophil extracellular trap remnants in the circulation of patients with small vessel vasculitis, but an inverse correlation to anti-neutrophil cytoplasmic antibodies during remission. Rheumatology (Oxford) 2015; 54:2085-94. [PMID: 26170375 DOI: 10.1093/rheumatology/kev217] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Indexed: 12/16/2022] Open
Abstract
OBJECTIVES Neutrophil extracellular traps (NETs) have been visualized at the site of ANCA-associated vasculitis (AAV) lesions. Increased levels of NET remnants in the circulation have been reported in some AAV patients with active disease. The aim of the present study was to analyse NET remnants in a larger cohort of AAV patients with varying degrees of disease activity and to elucidate possible factors responsible for remnant variation. METHODS Levels of NET remnants in the circulation of healthy controls (HCs; n = 31) and AAV patients (n = 93) were determined with ELISA. NET remnants were then correlated with ANCA levels, spontaneous and induced cell death (NETosis/necrosis) in vitro, neutrophil count and corticosteroid therapy. RESULTS Patients with active disease showed higher levels of circulating NET remnants compared with patients in remission (P = 0.026) and HCs (P = 0.006). From patients sampled during both remission and active disease, we found increased levels during active disease (P = 0.0010). In remission, ANCA-negative patients had higher levels of NET remnants than ANCA-positive patients and a negative correlation was observed between NET remnants and PR3-ANCA (rs = -0.287, P = 0.048). NET remnants correlated with neutrophil count in HCs (rs = 0.503, P = 0.014) but not in patients during remission. Neutrophils from patients showed enhanced spontaneous cell death (P = 0.043). CONCLUSION We found increased levels of circulating NET remnants in patients with active AAV. Furthermore, AAV patients exhibited an increased propensity for spontaneous cell death. NET remnant levels seem to be positively related to disease activity and neutrophil count, but inversely related to ANCA at least during remission.
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Affiliation(s)
- Daniel Söderberg
- Department of Medical and Health Sciences, Linköping University, Linköping,
| | - Tino Kurz
- Department of Medical and Health Sciences, Linköping University, Linköping
| | - Atbin Motamedi
- Department of Medical and Health Sciences, Linköping University, Linköping
| | - Thomas Hellmark
- Department of Clinical Sciences, Section of Nephrology, Lund University, Lund
| | - Per Eriksson
- Department of Rheumatology, Department of Clinical and Experimental Medicine and
| | - Mårten Segelmark
- Department of Medical and Health Sciences, Linköping University, Linköping, Department of Nephrology, Linköping University, Linköping, Sweden
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Perobelli SM, Galvani RG, Gonçalves-Silva T, Xavier CR, Nóbrega A, Bonomo A. Plasticity of neutrophils reveals modulatory capacity. ACTA ACUST UNITED AC 2015; 48:665-75. [PMID: 26108096 PMCID: PMC4541684 DOI: 10.1590/1414-431x20154524] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/17/2015] [Indexed: 12/22/2022]
Abstract
Neutrophils are widely known as proinflammatory cells associated with tissue damage
and for their early arrival at sites of infection, where they exert their phagocytic
activity, release their granule contents, and subsequently die. However, this view
has been challenged by emerging evidence that neutrophils have other activities and
are not so short-lived. Following activation, neutrophil effector functions include
production and release of granule contents, reactive oxygen species (ROS), and
neutrophil extracellular traps (NETs). Neutrophils have also been shown to produce a
wide range of cytokines that have pro- or anti-inflammatory activity, adding a
modulatory role for this cell, previously known as a suicide effector. The presence
of cytokines almost always implies intercellular modulation, potentially unmasking
interactions of neutrophils with other immune cells. In fact, neutrophils have been
found to help B cells and to modulate dendritic cell (DC), macrophage, and T-cell
activities. In this review, we describe some ways in which neutrophils influence the
inflammatory environment in infection, cancer, and autoimmunity, regulating both
innate and adaptive immune responses. These cells can switch phenotypes and exert
functions beyond cytotoxicity against invading pathogens, extending the view of
neutrophils beyond suicide effectors to include functions as regulatory and
suppressor cells.
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Affiliation(s)
- S M Perobelli
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - R G Galvani
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - T Gonçalves-Silva
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - C R Xavier
- Departamento de Ciência da Computação, Universidade Federal de São João Del Rei, São João Del Rei, MG, Brasil
| | - A Nóbrega
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
| | - A Bonomo
- Departamento de Imunologia, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
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Mikuls TR, Reimold A, Kerr GS, Cannon GW. Insights and Implications of the VA Rheumatoid Arthritis Registry. Fed Pract 2015; 32:24-29. [PMID: 30766061 PMCID: PMC6363303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The VA Rheumatoid Arthritis Registry addresses the underrepresentation of veterans in rheumatoid arthritis research, serving as a repository that links banked serum, plasma, and DNA samples with an array of patient-level information.
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Affiliation(s)
- Ted R Mikuls
- is a staff rheumatologist and research scientist at the VA Nebraska Western-Iowa Health Care System and the Umbach Professor of Rheumatology at the University of Nebraska Medical Center, both in Omaha. is chief of the Rheumatology Section at the Dallas VAMC and associate professor at the University of Texas Southwestern Medical Center, both in Dallas. is chief of the Division of Rheumatology at the Washington DC VAMC and professor of medicine at Georgetown University, both in Washington, DC. is associate chief of staff at the George E. Wahlen VAMC and professor of medicine in the Division of Rheumatology at the University of Utah, both in Salt Lake City
| | - Andreas Reimold
- is a staff rheumatologist and research scientist at the VA Nebraska Western-Iowa Health Care System and the Umbach Professor of Rheumatology at the University of Nebraska Medical Center, both in Omaha. is chief of the Rheumatology Section at the Dallas VAMC and associate professor at the University of Texas Southwestern Medical Center, both in Dallas. is chief of the Division of Rheumatology at the Washington DC VAMC and professor of medicine at Georgetown University, both in Washington, DC. is associate chief of staff at the George E. Wahlen VAMC and professor of medicine in the Division of Rheumatology at the University of Utah, both in Salt Lake City
| | - Gail S Kerr
- is a staff rheumatologist and research scientist at the VA Nebraska Western-Iowa Health Care System and the Umbach Professor of Rheumatology at the University of Nebraska Medical Center, both in Omaha. is chief of the Rheumatology Section at the Dallas VAMC and associate professor at the University of Texas Southwestern Medical Center, both in Dallas. is chief of the Division of Rheumatology at the Washington DC VAMC and professor of medicine at Georgetown University, both in Washington, DC. is associate chief of staff at the George E. Wahlen VAMC and professor of medicine in the Division of Rheumatology at the University of Utah, both in Salt Lake City
| | - Grant W Cannon
- is a staff rheumatologist and research scientist at the VA Nebraska Western-Iowa Health Care System and the Umbach Professor of Rheumatology at the University of Nebraska Medical Center, both in Omaha. is chief of the Rheumatology Section at the Dallas VAMC and associate professor at the University of Texas Southwestern Medical Center, both in Dallas. is chief of the Division of Rheumatology at the Washington DC VAMC and professor of medicine at Georgetown University, both in Washington, DC. is associate chief of staff at the George E. Wahlen VAMC and professor of medicine in the Division of Rheumatology at the University of Utah, both in Salt Lake City
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Cooper PR, Palmer LJ, Chapple ILC. Neutrophil extracellular traps as a new paradigm in innate immunity: friend or foe? Periodontol 2000 2015; 63:165-97. [PMID: 23931060 DOI: 10.1111/prd.12025] [Citation(s) in RCA: 115] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/31/2012] [Indexed: 12/12/2022]
Abstract
The discovery of neutrophil extracellular traps in 2004 opened a fascinating new chapter in immune-mediated microbial killing. Brinkman et al. demonstrated that neutrophils, when catastrophically stimulated, undergo a novel form of programmed cell death (neutrophil extracellular trap formation) whereby they decondense their entire nuclear chromatin/DNA and release the resulting structure into the cytoplasm to mix with granule-derived antimicrobial peptides before extruding these web-like structures into the extracellular environment. The process requires the activation of the granule enzyme peptidyl arginine deiminase-4, the formation of reactive oxygen species (in particular hypochlorous acid), the neutrophil microtubular system and the actin cytoskeleton. Recent work by Yousefi et al. demonstrated that exposure to different agents for shorter stimulation periods resulted in neutrophil extracellular trap release from viable granulocytes, and that such neutrophil extracellular traps comprised mitochondrial DNA rather than nuclear DNA and were also capable of microbial entrapment and destruction. Deficiency in NADPH-oxidase production (as found in patients with chronic granulomatous disease) results in an inability to produce neutrophil extracellular traps and, along with their failure to produce antimicrobial reactive oxygen species, these patients suffer from severe, and sometimes life-threatening, infections. However, conversely the release of nuclear chromatin into tissues is also potentially autoimmunogenic and is now associated with the generation of anti-citrullinated protein antibodies in seropositive rheumatoid arthritis. Other neutrophil-derived nuclear and cytoplasmic contents are also pathogenic, either through direct effects on tissues or via autoimmune processes (e.g. autoimmune vasculitis). In this review, we discuss the plant origins of a highly conserved innate immune method of microbial killing, the history and biology of neutrophil extracellular traps and their role in defence and in human diseases. We attempt to resolve areas of controversy and propose roles for excess neutrophil extracellular trap release from hyperactive/reactive neutrophils and for the unique peptidyl arginine deiminase enzyme of Porphyromonas gingivalis in the pathogenesis of periodontitis, and subsequently a role for periodontitis/the peptidyl arginine deiminase enzyme of P. gingivalis in the causal pathway of autoimmune diseases such as rheumatoid arthritis. We propose that neutrophil extracellular trap and peptidyl arginine deiminase release may propagate tissue-destructive mechanisms rather than provide protection in susceptible individuals and that release of host-derived DNase may play an important role in the digestion and removal of neutrophil extracellular traps within tissues.
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Gonzalez SM, Payne JB, Yu F, Thiele GM, Erickson AR, Johnson PG, Schmid MJ, Cannon GW, Kerr GS, Reimold AM, Sokolove J, Robinson WH, Mikuls TR. Alveolar Bone Loss Is Associated With Circulating Anti-Citrullinated Protein Antibody (ACPA) in Patients With Rheumatoid Arthritis. J Periodontol 2015; 86:222-31. [DOI: 10.1902/jop.2014.140425] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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González-Navajas JM, Corr MP, Raz E. The immediate protective response to microbial challenge. Eur J Immunol 2014; 44:2536-49. [PMID: 24965684 DOI: 10.1002/eji.201344291] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 06/02/2014] [Accepted: 06/20/2014] [Indexed: 03/20/2024]
Abstract
The innate immune system detects infection and tissue injury through different families of pattern-recognition receptors (PRRs), such as Toll-like receptors. Most PRR-mediated responses initiate elaborate processes of signaling, transcription, translation, and secretion of effector mediators, which together require time to achieve. Therefore, PRR-mediated processes are not active in the early phases of infection. These considerations raise the question of how the host limits microbial replication and invasion during this critical period. Here, we examine the crucial defense mechanisms, such as antimicrobial peptides or extracellular traps, typically activated within minutes of the initial infection phase, which we term the "immediate protective response". Deficiencies in different components of the immediate protective response are often associated with severe and recurrent infectious diseases in humans, highlighting their physiologic importance.
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Affiliation(s)
- José M González-Navajas
- Networked Biomedical Research Center for Hepatic and Digestive Diseases (CIBERehd), Hospital General de Alicante, Alicante, Spain; Division of Rheumatology, Allergy and Immunology, Department of Medicine, University of California San Diego, La Jolla, CA, USA
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Mikuls TR, Payne JB, Yu F, Thiele GM, Reynolds RJ, Cannon GW, Markt J, McGowan D, Kerr GS, Redman RS, Reimold A, Griffiths G, Beatty M, Gonzalez SM, Bergman DA, Hamilton BC, Erickson AR, Sokolove J, Robinson WH, Walker C, Chandad F, O'Dell JR. Periodontitis and Porphyromonas gingivalis in patients with rheumatoid arthritis. Arthritis Rheumatol 2014; 66:1090-100. [PMID: 24782175 DOI: 10.1002/art.38348] [Citation(s) in RCA: 262] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 12/31/2013] [Indexed: 01/20/2023]
Abstract
OBJECTIVE To examine the degree to which shared risk factors explain the relationship of periodontitis (PD) to rheumatoid arthritis (RA) and to determine the associations of PD and Porphyromonas gingivalis with pathologic and clinical features of RA. METHODS Patients with RA (n = 287) and patients with osteoarthritis as disease controls (n = 330) underwent a standardized periodontal examination. The HLA-DRB1 status of all participants was imputed using single-nucleotide polymorphisms from the extended major histocompatibility complex. Circulating anti-P gingivalis antibodies were measured using an enzyme-linked immunosorbent assay, and subgingival plaque was assessed for the presence of P gingivalis using polymerase chain reaction (PCR). Associations of PD with RA were examined using multivariable regression. RESULTS Presence of PD was more common in patients with RA and patients with anti-citrullinated protein antibody (ACPA)-positive RA (n = 240; determined using the anti-cyclic citrullinated peptide 2 [anti-CCP-2] test) than in controls (35% and 37%, respectively, versus 26%; P = 0.022 and P = 0.006, respectively). There were no differences between RA patients and controls in the levels of anti-P gingivalis or the frequency of P gingivalis positivity by PCR. The anti-P gingivalis findings showed a weak, but statistically significant, association with the findings for both anti-CCP-2 (r = 0.14, P = 0.022) and rheumatoid factor (RF) (r = 0.19, P = 0.001). Presence of PD was associated with increased swollen joint counts (P = 0.004), greater disease activity according to the 28-joint Disease Activity Score using C-reactive protein level (P = 0.045), and higher total Sharp scores of radiographic damage (P = 0.015), as well as with the presence and levels of anti-CCP-2 (P = 0.011) and RF (P < 0.001). The expression levels of select ACPAs (including antibodies to citrullinated filaggrin) were higher in patients with subgingival P gingivalis and in those with higher levels of anti-P gingivalis antibodies, irrespective of smoking status. Associations of PD with established seropositive RA were independent of all covariates examined, including evidence of P gingivalis infection. CONCLUSION Both PD and P gingivalis appear to shape the autoreactivity of RA. In addition, these results demonstrate an independent relationship between PD and established seropositive RA.
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Affiliation(s)
- Ted R Mikuls
- Omaha VA Medical Center and University of Nebraska Medical Center, Omaha
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58
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Radic M. Clearance of Apoptotic Bodies, NETs, and Biofilm DNA: Implications for Autoimmunity. Front Immunol 2014; 5:365. [PMID: 25126089 PMCID: PMC4115591 DOI: 10.3389/fimmu.2014.00365] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2014] [Accepted: 07/15/2014] [Indexed: 12/11/2022] Open
Affiliation(s)
- Marko Radic
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center , Memphis, TN , USA
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Behnen M, Leschczyk C, Möller S, Batel T, Klinger M, Solbach W, Laskay T. Immobilized immune complexes induce neutrophil extracellular trap release by human neutrophil granulocytes via FcγRIIIB and Mac-1. THE JOURNAL OF IMMUNOLOGY 2014; 193:1954-65. [PMID: 25024378 DOI: 10.4049/jimmunol.1400478] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Canonical neutrophil antimicrobial effector mechanisms, such as degranulation, production of reactive oxygen species, and release of neutrophil extracellular traps (NETs), can result in severe pathology. Activation of neutrophils through immune complexes (ICs) plays a central role in the pathogenesis of many autoimmune inflammatory diseases. In this study, we report that immobilized ICs (iICs), which are hallmarks of several autoimmune diseases, induce the release of NETs from primary human neutrophils. The iIC-induced NET formation was found to require production of reactive oxygen species by NADPH oxidase and myeloperoxidase and to be mediated by FcγRIIIb. Blocking of the β2 integrin macrophage-1 Ag but not lymphocyte function-associated Ag-1 abolished iIC-induced NET formation. This suggests that FcγRIIIb signals in association with macrophage-1 Ag. As intracellular signaling pathways involved in iIC-induced NET formation we identified the tyrosine kinase Src/Syk pathway, which downstream regulates the PI3K/Akt, p38 MAPK, and ERK1/2 pathways. To our knowledge, the present study shows for the first time that iICs induce NET formation. Thus, we conclude that NETs contribute to pathology in autoimmune inflammatory disorders associated with surface-bound ICs.
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Affiliation(s)
- Martina Behnen
- Institute for Medical Microbiology and Hygiene, University of Lübeck, D-23538 Lübeck, Germany; and
| | - Christoph Leschczyk
- Institute for Medical Microbiology and Hygiene, University of Lübeck, D-23538 Lübeck, Germany; and
| | - Sonja Möller
- Institute for Medical Microbiology and Hygiene, University of Lübeck, D-23538 Lübeck, Germany; and
| | - Tobit Batel
- Institute for Medical Microbiology and Hygiene, University of Lübeck, D-23538 Lübeck, Germany; and
| | - Matthias Klinger
- Institute of Anatomy, University of Lübeck, D-23538 Lübeck, Germany
| | - Werner Solbach
- Institute for Medical Microbiology and Hygiene, University of Lübeck, D-23538 Lübeck, Germany; and
| | - Tamás Laskay
- Institute for Medical Microbiology and Hygiene, University of Lübeck, D-23538 Lübeck, Germany; and
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Romero V, Fert-Bober J, Nigrovic PA, Darrah E, Haque UJ, Lee DM, van Eyk J, Rosen A, Andrade F. Immune-mediated pore-forming pathways induce cellular hypercitrullination and generate citrullinated autoantigens in rheumatoid arthritis. Sci Transl Med 2014; 5:209ra150. [PMID: 24174326 DOI: 10.1126/scitranslmed.3006869] [Citation(s) in RCA: 171] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Autoantibodies to citrullinated protein antigens are specific markers of rheumatoid arthritis (RA). Although protein citrullination can be activated by numerous stimuli in cells, it remains unclear which of these produce the prominent citrullinated autoantigens targeted in RA. In these studies, we show that RA synovial fluid cells have an unusual pattern of citrullination with marked citrullination of proteins across the broad range of molecular weights, which we term cellular hypercitrullination. Although histone citrullination is a common event during neutrophil activation and death induced by different pathways including apoptosis, NETosis, and necroptosis/autophagy, hypercitrullination is not induced by these stimuli. However, marked hypercitrullination is induced by two immune-mediated membranolytic pathways, mediated by perforin and the membrane attack complex (MAC), which are active in the RA joint and of importance in RA pathogenesis. We further demonstrate that perforin and MAC activity on neutrophils generate the profile of citrullinated autoantigens characteristic of RA. These data suggest that activation of peptidylarginine deiminases during complement and perforin activity may be at the core of citrullinated autoantigen production in RA. These pathways may be amenable to monitoring and therapeutic modulation.
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Affiliation(s)
- Violeta Romero
- Division of Rheumatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA
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Dreyton CJ, Knuckley B, Jones JE, Lewallen DM, Thompson PR. Mechanistic studies of protein arginine deiminase 2: evidence for a substrate-assisted mechanism. Biochemistry 2014; 53:4426-33. [PMID: 24989433 PMCID: PMC4100781 DOI: 10.1021/bi500554b] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
Citrullination, which is catalyzed
by protein arginine deiminases
(PADs 1–4 and 6), is a post-translational modification (PTM)
that effectively neutralizes the positive charge of a guanidinium
group by its replacement with a neutral urea. Given the sequence similarity
of PAD2 across mammalian species and the genomic organization of the
PAD2 gene, PAD2 is predicted to be the ancestral homologue of the
PADs. Although PAD2 has long been known to play a role in myelination,
it has only recently been linked to other cellular processes, including
gene transcription and macrophage extracellular trap formation. For
example, PAD2 deiminates histone H3 at R26, and this PTM leads to
the increased transcription of more than 200 genes under the control
of the estrogen receptor. Given that our understanding of PAD2 biology
remains incomplete, we initiated mechanistic studies on this enzyme
to aid the development of PAD2-specific inhibitors. Herein, we report
that the substrate specificity and calcium dependence of PAD2 are
similar to those of PADs 1, 3, and 4. However, unlike those isozymes,
PAD2 appears to use a substrate-assisted mechanism of catalysis in
which the positively charged substrate guanidinium depresses the pKa of the nucleophilic cysteine. By contrast,
PADs 1, 3, and 4 use a reverse-protonation mechanism. These mechanistic
differences will aid the development of isozyme-specific inhibitors.
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Affiliation(s)
- Christina J Dreyton
- Department of Chemistry and The Kellogg School of Graduate Studies, The Scripps Research Institute-Florida , 130 Scripps Way, Jupiter, Florida 33458, United States
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Granger V, de Chaisemartin L, Chollet-Martin S. [Miraculous catch by neutrophils NETs]. Med Sci (Paris) 2014; 30:544-9. [PMID: 24939542 DOI: 10.1051/medsci/20143005018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Neutrophil extracellular traps (NET) account for a new mechanism of anti-infectious innate immunity that may lead to important tissue damages. Indeed, a growing number of studies demonstrate the involvement of NET in the pathogenesis of several human diseases as diverse as autoimmune diseases, thrombotic disorders or some inflammatory diseases. After a short description of molecular mechanisms of NETosis and its host-defense function, we will review their detrimental effects. We will then examine the potential therapeutic approaches for modulating excessive or inappropriate NETosis and thereby minimize tissue injury.
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Affiliation(s)
- Vanessa Granger
- Inserm UMR996, faculté de pharmacie, université Paris-Sud 11, 92290 Châtenay-Malabry, France - Département d'hématologie et immunologie, UF auto-immunité et hypersensibilité, hôpital Bichat-Claude Bernard, 75018 Paris, France
| | - Luc de Chaisemartin
- Inserm UMR996, faculté de pharmacie, université Paris-Sud 11, 92290 Châtenay-Malabry, France - Département d'hématologie et immunologie, UF auto-immunité et hypersensibilité, hôpital Bichat-Claude Bernard, 75018 Paris, France
| | - Sylvie Chollet-Martin
- Inserm UMR996, faculté de pharmacie, université Paris-Sud 11, 92290 Châtenay-Malabry, France - Département d'hématologie et immunologie, UF auto-immunité et hypersensibilité, hôpital Bichat-Claude Bernard, 75018 Paris, France
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Sur Chowdhury C, Giaglis S, Walker UA, Buser A, Hahn S, Hasler P. Enhanced neutrophil extracellular trap generation in rheumatoid arthritis: analysis of underlying signal transduction pathways and potential diagnostic utility. Arthritis Res Ther 2014; 16:R122. [PMID: 24928093 PMCID: PMC4229860 DOI: 10.1186/ar4579] [Citation(s) in RCA: 245] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Accepted: 05/21/2014] [Indexed: 12/12/2022] Open
Abstract
INTRODUCTION Neutrophil extracellular traps (NETs) have recently been implicated in a number of autoimmune conditions, including rheumatoid arthritis (RA). We examined the underlying signaling pathways triggering enhanced NETosis in RA and ascertained whether the products of NETosis had diagnostic implications or usefulness. METHODS Neutrophils were isolated from RA patients with active disease and from controls. Spontaneous NET formation from RA and control neutrophils was assessed in vitro with microscopy and enzyme-linked immunosorbent assay (ELISA) for NETosis-derived products. The analysis of the signal-transduction cascade included reactive oxygen species (ROS) production, myeloperoxidase (MPO), neutrophil elastase (NE), peptidyl arginine deiminase 4 (PAD4), and citrullinated histone 3 (citH3). NET formation was studied in response to serum and synovial fluid and immunoglobulin G (IgG) depleted and reconstituted serum. Serum was analyzed for NETosis-derived products, for which receiver operator characteristic (ROC) curves were calculated. RESULTS Neutrophils from RA cases exhibited increased spontaneous NET formation in vitro, associated with elevated ROS production, enhanced NE and MPO expression, nuclear translocation of PAD4, PAD4-mediated citrullination of H3, and altered nuclear morphology. NET formation in both anti-citrullinated peptide antibody (ACPA)-positive and -negative RA was abolished by IgG depletion, but restored only with ACPA-positive IgG. NETosis-derived products in RA serum demonstrated diagnostic potential, the ROC area under the curve for cell-free nucleosomes being >97%, with a sensitivity of 91% and a specificity of 92%. No significant difference was observed between ACPA-positive and -negative cases. CONCLUSIONS Signaling elements associated with the extrusion of NETs are significantly enhanced to promote NETosis in RA compared with healthy controls. NETosis depended on the presence of ACPA in ACPA-positive RA serum. The quantitation of NETosis-derived products, such as cell-free nucleosomes in serum, may be a useful complementary tool to discriminate between healthy controls and RA cases.
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64
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Mowen KA, David M. Unconventional post-translational modifications in immunological signaling. Nat Immunol 2014; 15:512-20. [DOI: 10.1038/ni.2873] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/21/2014] [Indexed: 02/07/2023]
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Allam R, Kumar SVR, Darisipudi MN, Anders HJ. Extracellular histones in tissue injury and inflammation. J Mol Med (Berl) 2014; 92:465-72. [PMID: 24706102 DOI: 10.1007/s00109-014-1148-z] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 03/16/2014] [Accepted: 03/21/2014] [Indexed: 02/07/2023]
Abstract
Neutrophil NETosis is an important element of host defense as it catapults chromatin out of the cell to trap bacteria, which then are killed, e.g., by the chromatin's histone component. Also, during sterile inflammation TNF-alpha and other mediators trigger NETosis, which elicits cytotoxic effects on host cells. The same mechanism should apply to other forms of regulated necrosis including pyroptosis, necroptosis, ferroptosis, and cyclophilin D-mediated regulated necrosis. Beyond these toxic effects, extracellular histones also trigger thrombus formation and innate immunity by activating Toll-like receptors and the NLRP3 inflammasome. Thereby, extracellular histones contribute to the microvascular complications of sepsis, major trauma, small vessel vasculitis as well as acute liver, kidney, brain, and lung injury. Finally, histones prevent the degradation of extracellular DNA, which promotes autoimmunization, anti-nuclear antibody formation, and autoimmunity in susceptible individuals. Here, we review the current evidence on the pathogenic role of extracellular histones in disease and discuss how to target extracellular histones to improve disease outcomes.
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Affiliation(s)
- Ramanjaneyulu Allam
- Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, CH-1066, Epalinges, Switzerland
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66
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Dwivedi N, Neeli I, Schall N, Wan H, Desiderio DM, Csernok E, Thompson PR, Dali H, Briand JP, Muller S, Radic M. Deimination of linker histones links neutrophil extracellular trap release with autoantibodies in systemic autoimmunity. FASEB J 2014; 28:2840-51. [PMID: 24671707 DOI: 10.1096/fj.13-247254] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Autoantibodies to nuclear antigens arise in human autoimmune diseases, but a unifying pathogenetic mechanism remains elusive. Recently we reported that exposure of neutrophils to inflammatory conditions induces the citrullination of core histones by peptidylarginine deiminase 4 (PAD4) and that patients with autoimmune disorders produce autoantibodies that recognize such citrullinated histones. Here we identify histone H1 as an additional substrate of PAD4, localize H1 within neutrophil extracellular traps, and detect autoantibodies to citrullinated H1 in 6% of sera from patients with systemic lupus erythematosus and Sjögren's syndrome. No preference for deiminated H1 was observed in healthy control sera and sera from patients with scleroderma or rheumatoid arthritis. We map binding to the winged helix of H1 and determine that citrulline 53 represents a key determinant of the autoantibody epitope. In addition, we quantitate RNA for H1 histone subtypes in mature human neutrophils and identify citrulline residues by liquid chromatography and tandem mass spectrometry. Our results indicate that deimination of linker histones generates new autoantibody epitopes with enhanced potential for stimulating autoreactive human B cells.-Dwivedi, N., Neeli, I., Schall, N., Wan, H., Desiderio, D. M., Csernok, E., Thompson, P. R., Dali, H., Briand, J.-P., Muller, S., Radic, M. Deimination of linker histones links neutrophil extracellular trap release with autoantibodies in systemic autoimmunity.
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Affiliation(s)
- Nishant Dwivedi
- Department of Microbiology, Immunology, and Biochemistry, and
| | - Indira Neeli
- Department of Microbiology, Immunology, and Biochemistry, and
| | - Nicolas Schall
- Immunopathology and Therapeutic Chemistry, Laboratory of Excellence Medalis, Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
| | - Haibao Wan
- Department of Neurology, Charles B. Stout Neuroscience Mass Spectrometry Laboratory, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Dominic M Desiderio
- Department of Neurology, Charles B. Stout Neuroscience Mass Spectrometry Laboratory, University of Tennessee Health Science Center, Memphis, Tennessee, USA
| | - Elena Csernok
- Department of Rheumatology, University of Lübeck, Klinikum Bad Bramstedt, Bad Bramstedt, Germany; and
| | | | - Hayet Dali
- Immunopathology and Therapeutic Chemistry, Laboratory of Excellence Medalis, Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
| | - Jean-Paul Briand
- Immunopathology and Therapeutic Chemistry, Laboratory of Excellence Medalis, Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
| | - Sylviane Muller
- Immunopathology and Therapeutic Chemistry, Laboratory of Excellence Medalis, Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique (CNRS), Strasbourg, France
| | - Marko Radic
- Department of Microbiology, Immunology, and Biochemistry, and
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Xiao RZ, Xiong MJ, Long ZJ, Fan RF, Lin DJ. Diagnosis of Felty's syndrome, distinguished from hematological neoplasm: A case report. Oncol Lett 2013; 7:713-716. [PMID: 24527077 PMCID: PMC3919908 DOI: 10.3892/ol.2013.1779] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Accepted: 12/13/2013] [Indexed: 01/19/2023] Open
Abstract
Felty’s syndrome (FS) is characterized by the three conditions of rheumatoid arthritis (RA), neutropenia and splenomegaly, and occurs in few cases of longstanding erosive RA. Discriminating between rare occurrences of autoimmune diseases and malignancies is crucial. The present study describes the case of a 17-year-old female with a two-year history of RA, presenting with an irregular fever, hepatosplenomegaly and enlarged lymph nodes. The antinuclear antibody titer was 1:320, while antibody results for anti-dsDNA, anti-Sm and rheumatoid factor were negative. The clinical presentation was similar to that of lymphoma. However, the fluorodeoxyglucose-positron emission tomography and biopsy examinations of the liver and cervical lymph node did not support the diagnosis of lymphoma. According to the laboratory results and clinical symptoms, the differential diagnosis indicated FS, and immunosuppressive agents were administered. Two weeks later, the patient no longer had a fever, and the transaminase levels were normal, associated with shrinkage of the liver and spleen.
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Affiliation(s)
- Ruo-Zhi Xiao
- Department of Hematology, Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China ; Sun Yat-Sen Institute of Hematology, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Mu-Jun Xiong
- Department of Hematology, Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China ; Sun Yat-Sen Institute of Hematology, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Zi-Jie Long
- Department of Hematology, Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China ; Sun Yat-Sen Institute of Hematology, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Rui-Fang Fan
- Department of Hematology, Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China ; Sun Yat-Sen Institute of Hematology, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China
| | - Dong-Jun Lin
- Department of Hematology, Third Affiliated Hospital, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China ; Sun Yat-Sen Institute of Hematology, Sun Yat-Sen University, Guangzhou, Guangdong 510630, P.R. China
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68
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Abstract
The contributions by blood cells to pathological venous thrombosis were only recently appreciated. Both platelets and neutrophils are now recognized as crucial for thrombus initiation and progression. Here we review the most recent findings regarding the role of neutrophil extracellular traps (NETs) in thrombosis. We describe the biological process of NET formation (NETosis) and how the extracellular release of DNA and protein components of NETs, such as histones and serine proteases, contributes to coagulation and platelet aggregation. Animal models have unveiled conditions in which NETs form and their relation to thrombogenesis. Genetically engineered mice enable further elucidation of the pathways contributing to NETosis at the molecular level. Peptidylarginine deiminase 4, an enzyme that mediates chromatin decondensation, was identified to regulate both NETosis and pathological thrombosis. A growing body of evidence reveals that NETs also form in human thrombosis and that NET biomarkers in plasma reflect disease activity. The cell biology of NETosis is still being actively characterized and may provide novel insights for the design of specific inhibitory therapeutics. After a review of the relevant literature, we propose new ways to approach thrombolysis and suggest potential prophylactic and therapeutic agents for thrombosis.
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69
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Dwivedi N, Radic M. Citrullination of autoantigens implicates NETosis in the induction of autoimmunity. Ann Rheum Dis 2013; 73:483-91. [PMID: 24291655 DOI: 10.1136/annrheumdis-2013-203844] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Tolerance blocks the expression of autoantibodies, whereas autoimmunity promotes it. How tolerance breaks and autoantibody production begins thus are crucial questions for understanding and treatment of autoimmune diseases. Evidence implicates cell death and autoantigen modifications in the initiation of autoimmune reactions. One form of neutrophil cell death called NETosis deserves attention because it requires the post-translational modification of histones and results in the extracellular release of chromatin. NETosis received its name from NET, the acronym given to Neutrophil Extracellular Trap. The extracellular chromatin incorporates histones in which arginines have been converted to citrullines by peptidylarginine deiminase IV (PAD4). The deiminated chromatin may function to capture or 'trap' bacterial pathogens, thus generating an extracellular complex of deiminated histones and bacterial cell adjuvants. The complex of bacterial antigens and deiminated chromatin may be internalised by host phagocytes during acute inflammatory conditions, as arise during bacterial infections or chronic autoinflammatory disorders. The uptake and processing of deiminated chromatin together with bacterial adjuvants by phagocytes may induce the presentation of modified histone epitopes and co-stimulation, thus yielding a powerful stimulus to break tolerance. Autoantibodies to deiminated histones are prevalent in Felty's syndrome patients and are present in systemic lupus erythematosus (SLE) and patients with rheumatoid arthritis (RA). These observations clearly implicate histone deimination as an epigenetic mark that can act as an autoantibody stimulant.
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Affiliation(s)
- Nishant Dwivedi
- Program in Cellular and Molecular Medicine, Boston Children's Hospital and Harvard Medical School, , Boston, Massachusetts, USA
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70
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Radic M, Muller S. Epigenetics of autoantigens: new opportunities for therapy of autoimmune diseases. GENETICS & EPIGENETICS 2013; 5:63-70. [PMID: 25512708 PMCID: PMC4222337 DOI: 10.4137/geg.s12144] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The field of epigenetics requires that traditional divisions between scientific disciplines give way to cross-fertilization of concepts and ideas from different areas of investigation. Such is the case with research in autoimmunity. Recent discoveries of stimuli that induce autoimmunity reveal that epigenetic marks of autoantigens are recognized by autoreactive B and T cell receptors. Thus, insights into the initiation of autoimmunity, its prevention and therapy will arise from understanding the biochemistry, cell biology and microbiology of autoantigen epigenetics. Here, we highlight potential benefits from the inhibition of a histone modifying enzyme and the administration of a phosphorylated, spliceosome-derived peptide, in the treatment of autoimmunity.
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Affiliation(s)
- Marko Radic
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Sylviane Muller
- Immunopathology and therapeutic chemistry/Laboratory of excellence MEDALIS, Institut de Biologie Moléculaire et Cellulaire, CNRS, Strasbourg, France
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71
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Borthakur A, Bhattacharyya S, Kumar A, Anbazhagan AN, Tobacman JK, Dudeja PK. Lactobacillus acidophilus alleviates platelet-activating factor-induced inflammatory responses in human intestinal epithelial cells. PLoS One 2013; 8:e75664. [PMID: 24130731 PMCID: PMC3794005 DOI: 10.1371/journal.pone.0075664] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 08/16/2013] [Indexed: 02/06/2023] Open
Abstract
Probiotics have been used as alternative prevention and therapy modalities in intestinal inflammatory disorders including inflammatory bowel diseases (IBD) and necrotizing enterocolitis (NEC). Pathophysiology of IBD and NEC includes the production of diverse lipid mediators, including platelet-activating factor (PAF) that mediate inflammatory responses in the disease. PAF is known to activate NF-κB, however, the mechanisms of PAF-induced inflammation are not fully defined. We have recently described a novel PAF-triggered pathway of NF-κB activation and IL-8 production in intestinal epithelial cells (IECs), requiring the pivotal role of the adaptor protein Bcl10 and its interactions with CARMA3 and MALT1. The current studies examined the potential role of the probiotic Lactobacillus acidophilus in reversing the PAF-induced, Bcl10-dependent NF-κB activation and IL-8 production in IECs. PAF treatment (5 µM×24 h) of NCM460 and Caco-2 cells significantly increased nuclear p65 NF-κB levels and IL-8 secretion (2-3-fold, P<0.05), compared to control, which were blocked by pretreatment of the cells for 6 h with L. acidophilus (LA) or its culture supernatant (CS), followed by continued treatments with PAF for 24 h. LA-CS also attenuated PAF-induced increase in Bcl10 mRNA and protein levels and Bcl10 promoter activity. LA-CS did not alter PAF-induced interaction of Bcl10 with CARMA3, but attenuated Bcl10 interaction with MALT1 and also PAF-induced ubiquitination of IKKγ. Efficacy of bacteria-free CS of LA in counteracting PAF-induced inflammatory cascade suggests that soluble factor(s) in the CS of LA mediate these effects. These results define a novel mechanism by which probiotics counteract PAF-induced inflammation in IECs.
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Affiliation(s)
- Alip Borthakur
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Sumit Bhattacharyya
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Anoop Kumar
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Arivarasu Natarajan Anbazhagan
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Joanne K. Tobacman
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Pradeep K. Dudeja
- Division of Gastroenterology and Hepatology, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
- Jesse Brown VA Medical Center, Chicago, Illinois, United States of America
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Abstract
Neutrophils have emerged as important regulators of innate and adaptive immune responses. Recent evidence indicates that neutrophils display marked abnormalities in phenotype and function in various systemic autoimmune diseases, and may play a central role in initiation and perpetuation of aberrant immune responses and organ damage in these conditions. This review discusses the putative roles that neutrophils and aberrant neutrophil cell death play in the pathogenesis of various systemic autoimmune diseases, including systemic lupus erythematosus, small vessel vasculitis and rheumatoid arthritis.
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Khandpur R, Carmona-Rivera C, Vivekanandan-Giri A, Gizinski A, Yalavarthi S, Knight JS, Friday S, Li S, Patel RM, Subramanian V, Thompson P, Chen P, Fox DA, Pennathur S, Kaplan MJ. NETs are a source of citrullinated autoantigens and stimulate inflammatory responses in rheumatoid arthritis. Sci Transl Med 2013; 5:178ra40. [PMID: 23536012 DOI: 10.1126/scitranslmed.3005580] [Citation(s) in RCA: 897] [Impact Index Per Article: 81.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The early events leading to the development of rheumatoid arthritis (RA) remain unclear, but formation of autoantibodies to citrullinated protein antigens (ACPAs) is considered a key pathogenic event. Neutrophils isolated from patients with various autoimmune diseases display enhanced neutrophil extracellular trap (NET) formation, a phenomenon that exposes autoantigens in the context of immunostimulatory molecules. We investigated whether aberrant NETosis occurs in RA, determined its triggers, and examined its deleterious inflammatory consequences. Enhanced NETosis was observed in circulating and RA synovial fluid neutrophils compared to neutrophils from healthy controls and from patients with osteoarthritis (OA). Further, netting neutrophils infiltrated RA synovial tissue, rheumatoid nodules, and skin. NETosis correlated with ACPA presence and levels and with systemic inflammatory markers. RA sera and immunoglobulin fractions from RA patients with high levels of ACPA and/or rheumatoid factor significantly enhanced NETosis, and the NETs induced by these autoantibodies displayed distinct protein content. Indeed, during NETosis, neutrophils externalized the citrullinated autoantigens implicated in RA pathogenesis, and anti-citrullinated vimentin antibodies potently induced NET formation. Moreover, the inflammatory cytokines interleukin-17A (IL-17A) and tumor necrosis factor-α (TNF-α) induced NETosis in RA neutrophils. In turn, NETs significantly augmented inflammatory responses in RA and OA synovial fibroblasts, including induction of IL-6, IL-8, chemokines, and adhesion molecules. These observations implicate accelerated NETosis in RA pathogenesis, through externalization of citrullinated autoantigens and immunostimulatory molecules that may promote aberrant adaptive and innate immune responses in the joint and in the periphery, and perpetuate pathogenic mechanisms in this disease.
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Affiliation(s)
- Ritika Khandpur
- Division of Rheumatology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
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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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75
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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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Welin A, Amirbeagi F, Christenson K, Björkman L, Björnsdottir H, Forsman H, Dahlgren C, Karlsson A, Bylund J. The human neutrophil subsets defined by the presence or absence of OLFM4 both transmigrate into tissue in vivo and give rise to distinct NETs in vitro. PLoS One 2013; 8:e69575. [PMID: 23922742 PMCID: PMC3726694 DOI: 10.1371/journal.pone.0069575] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 06/10/2013] [Indexed: 12/13/2022] Open
Abstract
Neutrophil heterogeneity was described decades ago, but it could not be elucidated at the time whether the existence of different neutrophil subsets had any biological relevance. It has been corroborated in recent years that neutrophil subsets, defined by differential expression of various markers, are indeed present in human blood, calling for renewed attention to this question. The expression of the granule protein olfactomedin 4 (OLFM4) has been suggested to define two such neutrophil subsets. We confirm the simultaneous presence of one OLFM4-positive and one OLFM4-negative neutrophil subpopulation as well as the localization of the protein to specific granules. In vitro, these neutrophil subsets displayed equal tendency to undergo apoptosis and phagocytose bacteria. In addition, the subpopulations were recruited equally to inflammatory sites in vivo, and this was true both in an experimental model of acute inflammation and in naturally occurring pathological joint inflammation. In line with its subcellular localization, only limited OLFM4 release was seen upon in vivo transmigration, and release through conventional degranulation required strong secretagogues. However, extracellular release of OLFM4 could be achieved upon formation of neutrophil extracellular traps (NETs) where it was detected only in a subset of the NETs. Although we were unable to demonstrate any functional differences between the OLFM4-defined subsets, our data show that different neutrophil subsets are present in inflamed tissue in vivo. Furthermore, we demonstrate NETs characterized by different markers for the first time, and our results open up for functions of OLFM4 itself in the extracellular space through exposure in NETs.
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Affiliation(s)
- Amanda Welin
- The Phagocyte Research Group, Department of Rheumatology and Inflammation Research, University of Gothenburg, Gothenburg, Sweden.
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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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Basic science for the clinician 59: polymorphonuclear cells: mechanisms in human defense and in the pathogenesis of autoimmune disease. J Clin Rheumatol 2013; 18:443-9. [PMID: 23211587 DOI: 10.1097/rhu.0b013e31827732f1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
When I learned about polymorphonuclear neutrophils (PMNs) in medical school, they were presented as pretty much 1-trick ponies: PMNs were phagocytes with no intrinsic specificity; their only specificity was supplied by the Fcγ receptors on their surfaces and that would then be the specificity of the bound immunoglobulin G, nothing intrinsic to the PMN. My, how simple life was in those days! And how wrong! Turns out, these circulating cells are involved in bridging the innate immune system and the acquired immune response in some very interesting ways and may play a crucial role in the immunopathogenesis of some of "our" diseases. Polymorphonuclear neutrophils are often underappreciated as drivers of inflammatory diseases, which is why I think it is time for us to turn our attention to this underappreciated component of the immune response.
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79
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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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80
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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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81
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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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82
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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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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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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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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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Cui BB, Tan CY, Schorn C, Tang HH, Liu Y, Zhao Y. Neutrophil extracellular traps in sterile inflammation: the story after dying? Autoimmunity 2012; 45:593-6. [DOI: 10.3109/08916934.2012.719952] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Kaplan MJ, Radic M. Neutrophil extracellular traps: double-edged swords of innate immunity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2012; 189:2689-95. [PMID: 22956760 PMCID: PMC3439169 DOI: 10.4049/jimmunol.1201719] [Citation(s) in RCA: 831] [Impact Index Per Article: 69.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Spectacular images of neutrophils ejecting nuclear chromatin and bactericidal proteins, in response to microbes, were first reported in 2004. As externalized chromatin could entangle bacteria, these structures were named neutrophil extracellular traps (NETs). Subsequent studies identified microorganisms and sterile conditions that stimulate NETs, as well as additional cell types that release extracellular chromatin. The release of NETs is the most dramatic stage in a cell death process called NETosis. Experimental evidence suggests that NETs participate in pathogenesis of autoimmune and inflammatory disorders, with proposed involvement in glomerulonephritis, chronic lung disease, sepsis, and vascular disorders. Exaggerated NETosis or diminished NET clearance likely increases risk of autoreactivity to NET components. The biological significance of NETs is just beginning to be explored. A more complete integration of NETosis within immunology and pathophysiology will require better understanding of NET properties associated with specific disease states and microbial infections. This may lead to the identification of important therapeutic targets.
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Affiliation(s)
- Mariana J. Kaplan
- Division of Rheumatology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Marko Radic
- Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Sciences Center, Memphis, TN 38163
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Abstract
Prevailing approaches to manage autoimmune thrombotic disorders, such as heparin-induced thrombocytopenia, antiphospholipid syndrome and thrombotic thrombocytopenic purpura, include immunosuppression and systemic anticoagulation, though neither provides optimal outcome for many patients. A different approach is suggested by the concurrence of autoantibodies and their antigenic targets in the absence of clinical disease, such as platelet factor 4 in heparin-induced thrombocytopenia and β(2)-glycoprotein-I (β(2)GPI) in antiphospholipid syndrome. The presence of autoantibodies in the absence of disease suggests that conformational changes or other alterations in endogenous protein autoantigens are required for recognition by pathogenic autoantibodies. In thrombotic thrombocytopenic purpura, the clinical impact of ADAMTS13 deficiency caused by autoantibodies likely depends on the balance between residual antigen, that is, enzyme activity, and demand imposed by local genesis of ultralarge multimers of von Willebrand factor. A corollary of these concepts is that disrupting platelet factor 4 and β(2)GPI conformation (or ultralarge multimer of von Willebrand factor oligomerization or function) might provide a disease-targeted approach to prevent thrombosis without systemic anticoagulation or immunosuppression. Validation of this approach requires a deeper understanding of how seemingly normal host proteins become antigenic or undergo changes that increase antibody avidity, and how they can be altered to retain adaptive functions while shedding epitopes prone to elicit harmful autoimmunity.
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Rohrbach AS, Hemmers S, Arandjelovic S, Corr M, Mowen KA. PAD4 is not essential for disease in the K/BxN murine autoantibody-mediated model of arthritis. Arthritis Res Ther 2012; 14:R104. [PMID: 22551352 PMCID: PMC3446481 DOI: 10.1186/ar3829] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 04/10/2012] [Accepted: 05/02/2012] [Indexed: 12/20/2022] Open
Abstract
Introduction Both murine and human genome-wide association studies have implicated peptidyl arginine deiminase (PAD4) as a susceptibility gene in rheumatoid arthritis (RA). In addition, patients with RA commonly have autoantibodies which recognize PAD4 or and/or citrullinated peptides. This study aims to evaluate the role of PAD4 in the effector phase of arthritis. Methods PAD4 knock out (KO) and wild type (WT) C57BL/6J mice were injected with K/BxN sera to induce disease. Progression of disease was monitored by measuring paw and ankle swelling and clinical indexes of disease, and pathogenesis was assessed by indexing of clinical progression on paws collected from WT and PAD4 KO mice injected with K/BxN serum. PAD4 activity was determined by visualization of neutrophil extracellular traps (NETs) and immunohistological analysis of histone citrullination. Results PAD4 activity is readily detectable in the inflamed synovium of WT but not PAD4 deficient animals, as demonstrated by histone citrullination and NET formation. However, PAD4 WT and KO animals develop K/BxN serum transfer disease with comparable severity and kinetics, with no statistically significant differences noted in clinical scores, swelling, joint erosion or joint invasion. Conclusions PAD4 WT and KO mice develop disease in the K/BxN serum transfer model of arthritis with similar severity and kinetics, indicating that PAD4 is dispensable in this effector phase model of disease.
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Affiliation(s)
- Amanda S Rohrbach
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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Neeli I, Radic M. Knotting the NETs: analyzing histone modifications in neutrophil extracellular traps. Arthritis Res Ther 2012; 14:115. [PMID: 22524286 PMCID: PMC3446426 DOI: 10.1186/ar3773] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Neutrophil extracellular chromatin traps (NETs) are a recently described mechanism of innate immune responses to bacteria and fungi. Evidence indicates that NETs are induced by inflammation, that they contribute to diverse disease pathologies, and that they associate with bactericidal substances. Genomic DNA is released in NETs, leading to a cell death that has been labeled NETosis. Although NETosis clearly differs from apoptosis, the classical form of cell death, recent experiments indicate a connection between NETosis and autophagy. The regulated deployment of NETs may require covalent modification of histones, the basic DNA-binding proteins that organize chromatin in the cell's nucleus and within NETs. Histone modification by peptidylarginine deiminase 4 (PAD4) is necessary for NET release. The functions of additional histone modifications, however, remain to be tested.
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