201
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Rao S, Schieber AMP, O'Connor CP, Leblanc M, Michel D, Ayres JS. Pathogen-Mediated Inhibition of Anorexia Promotes Host Survival and Transmission. Cell 2017; 168:503-516.e12. [PMID: 28129542 DOI: 10.1016/j.cell.2017.01.006] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 11/21/2016] [Accepted: 01/06/2017] [Indexed: 01/06/2023]
Abstract
Sickness-induced anorexia is a conserved behavior induced during infections. Here, we report that an intestinal pathogen, Salmonella Typhimurium, inhibits anorexia by manipulating the gut-brain axis. Inhibition of inflammasome activation by the S. Typhimurium effector, SlrP, prevented anorexia caused by IL-1β-mediated signaling to the hypothalamus via the vagus nerve. Rather than compromising host defenses, pathogen-mediated inhibition of anorexia increased host survival. SlrP-mediated inhibition of anorexia prevented invasion and systemic infection by wild-type S. Typhimurium, reducing virulence while increasing transmission to new hosts, suggesting that there are trade-offs between transmission and virulence. These results clarify the complex and contextual role of anorexia in host-pathogen interactions and suggest that microbes have evolved mechanisms to modulate sickness-induced behaviors to promote health of their host and their transmission at the expense of virulence.
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Affiliation(s)
- Sheila Rao
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Alexandria M Palaferri Schieber
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Carolyn P O'Connor
- Flow Cytometry Core Facility, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Mathias Leblanc
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Daniela Michel
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Janelle S Ayres
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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202
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Salicylidene Acylhydrazides and Hydroxyquinolines Act as Inhibitors of Type Three Secretion Systems in Pseudomonas aeruginosa by Distinct Mechanisms. Antimicrob Agents Chemother 2017; 61:AAC.02566-16. [PMID: 28396545 DOI: 10.1128/aac.02566-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 03/23/2017] [Indexed: 12/27/2022] Open
Abstract
Type 3 secretion systems (T3SSs) are major virulence factors in Gram-negative bacteria. Pseudomonas aeruginosa expresses two T3SSs, namely, an injectisome (iT3SS) translocating effector proteins in the host cell cytosol and a flagellum (fT3SS) ensuring bacterial motility. Inhibiting these systems is an appealing therapeutic strategy for acute infections. This study examines the protective effects of the salicylidene acylhydrazide INP0341 and of the hydroxyquinoline INP1750 (previously described as T3SS inhibitors in other species) toward cytotoxic effects of P. aeruginosain vitro Both compounds reduced cell necrosis and inflammasome activation induced by reference strains or clinical isolates expressing T3SS toxins or only the translocation apparatus. INP0341 inhibited iT3SS transcriptional activation, including in strains with constitutive iT3SS expression, and reduced the total expression of toxins, suggesting it targets iT3SS gene transcription. INP1750 inhibited toxin secretion and flagellar motility and impaired the activity of the YscN ATPase from Yersinia pseudotuberculosis (homologous to the ATPase present in the basal body of P. aeruginosa iT3SS and fT3SS), suggesting that it rather targets a T3SS core constituent with high homology among iT3SS and fT3SS. This mode of action is similar to that previously described for INP1855, another hydroxyquinoline, against P. aeruginosa Thus, although acting by different mechanisms, INP0341 and INP1750 appear as useful inhibitors of the virulence of P. aeruginosa Hydroxyquinolines may have a broader spectrum of activity by the fact they act upon two virulence factors (iT3SS and fT3SS).
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203
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Kieser KJ, Kagan JC. Multi-receptor detection of individual bacterial products by the innate immune system. Nat Rev Immunol 2017; 17:376-390. [PMID: 28461704 DOI: 10.1038/nri.2017.25] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The receptors of the innate immune system detect specific microbial ligands to promote effective inflammatory and adaptive immune responses. Although this idea is well appreciated, studies in recent years have highlighted the complexity of innate immune detection, with multiple host receptors recognizing the same microbial ligand. Understanding the collective actions of diverse receptors that recognize common microbial signatures represents a new frontier in the study of innate immunity, and is the focus of this Review. Here, we discuss examples of individual bacterial cell wall components that are recognized by at least two and as many as four different receptors of the innate immune system. These receptors survey the extracellular or cytosolic spaces for their cognate ligands and operate in a complementary manner to induce distinct cellular responses. We further highlight that, despite this genetic diversity in receptors and pathways, common features exist to explain the operation of these receptors. These common features may help to provide unifying organizing principles associated with host defence.
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Affiliation(s)
- Karen J Kieser
- Department of Pediatrics, Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, Boston, Massachusetts 02115, USA
| | - Jonathan C Kagan
- Department of Pediatrics, Harvard Medical School and Division of Gastroenterology, Boston Children's Hospital, Boston, Massachusetts 02115, USA
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204
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Pallett MA, Crepin VF, Serafini N, Habibzay M, Kotik O, Sanchez-Garrido J, Di Santo JP, Shenoy AR, Berger CN, Frankel G. Bacterial virulence factor inhibits caspase-4/11 activation in intestinal epithelial cells. Mucosal Immunol 2017; 10:602-612. [PMID: 27624779 PMCID: PMC5159625 DOI: 10.1038/mi.2016.77] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 08/01/2016] [Indexed: 02/07/2023]
Abstract
The human pathogen enteropathogenic Escherichia coli (EPEC), as well as the mouse pathogen Citrobacter rodentium, colonize the gut mucosa via attaching and effacing lesion formation and cause diarrheal diseases. EPEC and C. rodentium type III secretion system (T3SS) effectors repress innate immune responses and infiltration of immune cells. Inflammatory caspases such as caspase-1 and caspase-4/11 are crucial mediators of host defense and inflammation in the gut via their ability to process cytokines such as interleukin (IL)-1β and IL-18. Here we report that the effector NleF binds the catalytic domain of caspase-4 and inhibits its proteolytic activity. Following infection of intestinal epithelial cells (IECs) EPEC inhibited caspase-4 and IL-18 processing in an NleF-dependent manner. Depletion of caspase-4 in IECs prevented the secretion of mature IL-18 in response to infection with EPECΔnleF. NleF-dependent inhibition of caspase-11 in colons of mice prevented IL-18 secretion and neutrophil influx at early stages of C. rodentium infection. Neither wild-type C. rodentium nor C. rodentiumΔnleF triggered neutrophil infiltration or IL-18 secretion in Cas11 or Casp1/11-deficient mice. Thus, IECs have a key role in modulating early innate immune responses in the gut via a caspase-4/11-IL-18 axis, which is targeted by virulence factors encoded by enteric pathogens.
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Affiliation(s)
- Mitchell A. Pallett
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK
| | - Valerie F. Crepin
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK
| | - Nicolas Serafini
- Innate Immunity Unit, Institut Pasteur, Paris, France,Inserm U668, Paris, France
| | - Maryam Habibzay
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK
| | - Olga Kotik
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK
| | - Julia Sanchez-Garrido
- Department of Medicine, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK
| | - James P. Di Santo
- Innate Immunity Unit, Institut Pasteur, Paris, France,Inserm U668, Paris, France
| | - Avinash R. Shenoy
- Department of Medicine, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK
| | - Cedric N. Berger
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK
| | - Gad Frankel
- Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, Imperial College London, UK,Corresponding author, Gad Frankel, MRC CMBI, Flowers Building, Imperial College, London, SW7 2AZ,
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205
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Esquerdo KF, Sharma NK, Brunialti MKC, Baggio-Zappia GL, Assunção M, Azevedo LCP, Bafi AT, Salomao R. Inflammasome gene profile is modulated in septic patients, with a greater magnitude in non-survivors. Clin Exp Immunol 2017; 189:232-240. [PMID: 28369745 DOI: 10.1111/cei.12971] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/16/2017] [Indexed: 01/08/2023] Open
Abstract
Inflammasome signalling induces the processing and secretion of interleukin (IL)-1β and IL-18 which, coupled with pyroptosis, activate further the inflammatory response. In the present study we evaluated the expression of genes involved in inflammasome signalling pathways in septic patients, their interaction networks and the predicted functions modulated in survivors and non-survivors. Twenty-seven patients with sepsis secondary to community-acquired pneumonia admitted to intensive care units from three general hospitals in São Paulo were included into the study. We performed a polymerase chain reaction (PCR) array encompassing 35 genes related to the nucleotide-binding oligomerization domain and leucine-rich repeat-containing (NLR)-inflammasome in peripheral blood mononuclear cells obtained at admission and after 7 days of follow-up. Eleven healthy volunteers were used as the reference group. Increased NLRC4 and NLRP3 and decreased nucleotide-binding oligomerization domain (NOD1), and NLRP1 expression was observed in septic patients compared to healthy individuals; the IL-1β and IL-18 expression levels were also high in the patients. The gene expression changes followed the same patterns in surviving and non-surviving patients, with higher magnitudes observed in non-survivors. Functional analyses revealed, however, that activation and inhibition intensity for representing functions were different in survivors and non-survivors, as for production of reactive oxygen species, synthesis of nitric oxide and for the control of bacterial infections. Our results showed that the genes involved in the activation of the NLR-inflammasome cascades were altered substantially in septic patients, with a higher number of altered genes and a higher intensity in the disturbance of gene expression found among patients dying of sepsis.
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Affiliation(s)
- K F Esquerdo
- Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, São Paulo, Brazil
| | - N K Sharma
- Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, São Paulo, Brazil
| | - M K C Brunialti
- Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, São Paulo, Brazil
| | - G L Baggio-Zappia
- Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, São Paulo, Brazil
| | - M Assunção
- Hospital Israelita Albert Einstein, São Paulo, Brazil
| | | | - A T Bafi
- Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, São Paulo, Brazil
| | - R Salomao
- Escola Paulista de Medicina, Hospital São Paulo, Universidade Federal de Sao Paulo, São Paulo, Brazil
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206
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Barry KC, Ingolia NT, Vance RE. Global analysis of gene expression reveals mRNA superinduction is required for the inducible immune response to a bacterial pathogen. eLife 2017; 6. [PMID: 28383283 PMCID: PMC5407856 DOI: 10.7554/elife.22707] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/27/2017] [Indexed: 12/21/2022] Open
Abstract
The inducible innate immune response to infection requires a concerted process of gene expression that is regulated at multiple levels. Most global analyses of the innate immune response have focused on transcription induced by defined immunostimulatory ligands, such as lipopolysaccharide. However, the response to pathogens involves additional complexity, as pathogens interfere with virtually every step of gene expression. How cells respond to pathogen-mediated disruption of gene expression to nevertheless initiate protective responses remains unclear. We previously discovered that a pathogen-mediated blockade of host protein synthesis provokes the production of specific pro-inflammatory cytokines. It remains unclear how these cytokines are produced despite the global pathogen-induced block of translation. We addressed this question by using parallel RNAseq and ribosome profiling to characterize the response of macrophages to infection with the intracellular bacterial pathogen Legionella pneumophila. Our results reveal that mRNA superinduction is required for the inducible immune response to a bacterial pathogen.
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Affiliation(s)
- Kevin C Barry
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Nicholas T Ingolia
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Russell E Vance
- Division of Immunology and Pathogenesis, Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.,Cancer Research Laboratory, University of California, Berkeley, Berkeley, United States.,Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, United States
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207
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Morales AJ, Carrero JA, Hung PJ, Tubbs AT, Andrews JM, Edelson BT, Calderon B, Innes CL, Paules RS, Payton JE, Sleckman BP. A type I IFN-dependent DNA damage response regulates the genetic program and inflammasome activation in macrophages. eLife 2017; 6. [PMID: 28362262 PMCID: PMC5409825 DOI: 10.7554/elife.24655] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Accepted: 03/30/2017] [Indexed: 01/06/2023] Open
Abstract
Macrophages produce genotoxic agents, such as reactive oxygen and nitrogen species, that kill invading pathogens. Here we show that these agents activate the DNA damage response (DDR) kinases ATM and DNA-PKcs through the generation of double stranded breaks (DSBs) in murine macrophage genomic DNA. In contrast to other cell types, initiation of this DDR depends on signaling from the type I interferon receptor. Once activated, ATM and DNA-PKcs regulate a genetic program with diverse immune functions and promote inflammasome activation and the production of IL-1β and IL-18. Indeed, following infection with Listeria monocytogenes, DNA-PKcs-deficient murine macrophages produce reduced levels of IL-18 and are unable to optimally stimulate IFN-γ production by NK cells. Thus, genomic DNA DSBs act as signaling intermediates in murine macrophages, regulating innate immune responses through the initiation of a type I IFN-dependent DDR.
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Affiliation(s)
- Abigail J Morales
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York City, United States
| | - Javier A Carrero
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Putzer J Hung
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Anthony T Tubbs
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Jared M Andrews
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Brian T Edelson
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Boris Calderon
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Cynthia L Innes
- Environmental Stress and Cancer Group, National Institute of Environmental Health Sciences, Durham, United States.,NIEHS Microarray Group, National Institute of Environmental Health Sciences, Durham, United States
| | - Richard S Paules
- Environmental Stress and Cancer Group, National Institute of Environmental Health Sciences, Durham, United States.,NIEHS Microarray Group, National Institute of Environmental Health Sciences, Durham, United States
| | - Jacqueline E Payton
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, United States
| | - Barry P Sleckman
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York City, United States
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208
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Affiliation(s)
- Judie A. Howrylak
- Division of Pulmonary, Allergy, and Critical Care Medicine, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania 17003
| | - Kiichi Nakahira
- Division of Pulmonary and Critical Care Medicine, Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medicine, Cornell University, New York, NY 10065;
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209
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Luehong N, Khaowmek J, Wongsawan K, Chuammitri P. Preferential pattern of mouse neutrophil cell death in response to various stimulants. In Vitro Cell Dev Biol Anim 2017; 53:513-524. [DOI: 10.1007/s11626-016-0129-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 12/23/2016] [Indexed: 12/23/2022]
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210
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Abstract
Canonical activation of the inflammasome is critical to promote caspase-1-dependent maturation of the proinflammatory cytokines IL-1β and IL-18, as well as to induce pyroptotic cell death in response to pathogens and endogenous danger signals. Recent discoveries, however, are beginning to unveil new components of the inflammasome machinery as well as the full spectrum of inflammasome functions, extending their influence beyond canonical functions to regulation of eicosanoid storm, autophagy, and metabolism. In addition, the receptor components of the inflammasome can also regulate diverse biological processes, such as cellular proliferation, gene transcription, and tumorigenesis, all of which are independent of their inflammasome complex-forming capabilities. Here, we review these recent advances that are shaping our understanding of the complex biology of the inflammasome and its constituents.
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211
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Ratsimandresy RA, Indramohan M, Dorfleutner A, Stehlik C. The AIM2 inflammasome is a central regulator of intestinal homeostasis through the IL-18/IL-22/STAT3 pathway. Cell Mol Immunol 2017; 14:127-142. [PMID: 27524110 PMCID: PMC5214942 DOI: 10.1038/cmi.2016.35] [Citation(s) in RCA: 108] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 05/17/2016] [Accepted: 05/17/2016] [Indexed: 12/16/2022] Open
Abstract
Inflammasomes are important for maintaining intestinal homeostasis, and dysbiosis contributes to the pathology of inflammatory bowel disease (IBD) and increases the risk for colorectal cancer. Inflammasome defects contribute to chronic intestinal inflammation and increase the susceptibility to colitis in mice. However, the inflammasome sensor absent in melanoma 2 (AIM2) protects against colorectal cancer in an inflammasome-independent manner through DNA-dependent protein kinase and Akt pathways. Yet, the roles of the AIM2 inflammasome in IBD and the early phases of colorectal cancer remain ill-defined. Here we show that the AIM2 inflammasome has a protective role in the intestine. During steady state, Aim2 deletion results in the loss of IL-18 secretion, suppression of the IL-22 binding protein (IL-22BP) in intestinal epithelial cells and consequent loss of the STAT3-dependent antimicrobial peptides (AMPs) Reg3β and Reg3γ, which promotes dysbiosis-linked colitis. During dextran sulfate sodium-induced colitis, a dysfunctional IL-18/IL-22BP pathway in Aim2-/- mice promotes excessive IL-22 production and elevated STAT3 activation. Aim2-/- mice further exhibit sustained STAT3 and Akt activation during the resolution of colitis fueled by enhanced Reg3b and Reg3g expression. This self-perpetuating mechanism promotes proliferation of intestinal crypt cells and likely contributes to the recently described increase in susceptibility of Aim2-/- mice to colorectal cancer. Collectively, our results demonstrate a central role for the AIM2 inflammasome in preventing dysbiosis and intestinal inflammation through regulation of the IL-18/IL-22BP/IL-22 and STAT3 pathway and expression of select AMPs.
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Affiliation(s)
- Rojo A Ratsimandresy
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Mohanalaxmi Indramohan
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Andrea Dorfleutner
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Christian Stehlik
- Division of Rheumatology, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Robert H. Lurie Comprehensive Cancer Center, Interdepartmental Immunobiology Center and Skin Disease Research Center, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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212
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Borges PV, Moret KH, Raghavendra NM, Maramaldo Costa TE, Monteiro AP, Carneiro AB, Pacheco P, Temerozo JR, Bou-Habib DC, das Graças Henriques M, Penido C. Protective effect of gedunin on TLR-mediated inflammation by modulation of inflammasome activation and cytokine production: Evidence of a multitarget compound. Pharmacol Res 2017; 115:65-77. [DOI: 10.1016/j.phrs.2016.09.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 08/09/2016] [Accepted: 09/14/2016] [Indexed: 01/09/2023]
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213
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Functional and Evolutionary Analyses Identify Proteolysis as a General Mechanism for NLRP1 Inflammasome Activation. PLoS Pathog 2016; 12:e1006052. [PMID: 27926929 PMCID: PMC5142783 DOI: 10.1371/journal.ppat.1006052] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/09/2016] [Indexed: 12/19/2022] Open
Abstract
Inflammasomes are cytosolic multi-protein complexes that initiate immune responses to infection by recruiting and activating the Caspase-1 protease. Human NLRP1 was the first protein shown to form an inflammasome, but its physiological mechanism of activation remains unknown. Recently, specific variants of mouse and rat NLRP1 were found to be activated upon N-terminal cleavage by the anthrax lethal factor protease. However, agonists for other NLRP1 variants, including human NLRP1, are not known, and it remains unclear if they are also activated by proteolysis. Here we demonstrate that two mouse NLRP1 paralogs (NLRP1AB6 and NLRP1BB6) are also activated by N-terminal proteolytic cleavage. We also demonstrate that proteolysis within a specific N-terminal linker region is sufficient to activate human NLRP1. Evolutionary analysis of primate NLRP1 shows the linker/cleavage region has evolved under positive selection, indicative of pathogen-induced selective pressure. Collectively, these results identify proteolysis as a general mechanism of NLRP1 inflammasome activation that appears to be contributing to the rapid evolution of NLRP1 in rodents and primates.
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214
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Cystic fibrosis lung environment and Pseudomonas aeruginosa infection. BMC Pulm Med 2016; 16:174. [PMID: 27919253 PMCID: PMC5139081 DOI: 10.1186/s12890-016-0339-5] [Citation(s) in RCA: 229] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 11/24/2016] [Indexed: 12/20/2022] Open
Abstract
Background The airways of patients with cystic fibrosis (CF) are highly complex, subject to various environmental conditions as well as a distinct microbiota. Pseudomonas aeruginosa is recognized as one of the most important pulmonary pathogens and the predominant cause of morbidity and mortality in CF. A multifarious interplay between the host, pathogens, microbiota, and the environment shapes the course of the disease. There have been several excellent reviews detailing CF pathology, Pseudomonas and the role of environment in CF but only a few reviews connect these entities with regards to influence on the overall course of the disease. A holistic understanding of contributing factors is pertinent to inform new research and therapeutics. Discussion In this article, we discuss the deterministic alterations in lung physiology as a result of CF. We also revisit the impact of those changes on the microbiota, with special emphasis on P. aeruginosa and the influence of other non-genetic factors on CF. Substantial past and current research on various genetic and non-genetic aspects of cystic fibrosis has been reviewed to assess the effect of different factors on CF pulmonary infection. A thorough review of contributing factors in CF and the alterations in lung physiology indicate that CF lung infection is multi-factorial with no isolated cause that should be solely targeted to control disease progression. A combinatorial approach may be required to ensure better disease outcomes. Conclusion CF lung infection is a complex disease and requires a broad multidisciplinary approach to improve CF disease outcomes. A holistic understanding of the underlying mechanisms and non-genetic contributing factors in CF is central to development of new and targeted therapeutic strategies.
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215
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Wu C, Abd-el-haliem A, Bozkurt TO, Belhaj K, Terauchi R, Vossen JH, Kamoun S. NLR signaling network mediates immunity to diverse plant pathogens.. [DOI: 10.1101/090449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
Plant and animal nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins often function in pairs to mediate innate immunity to pathogens. However, the degree to which NLR proteins form signaling networks beyond genetically linked pairs is poorly understood. In this study, we discovered that a large NLR immune signaling network with a complex genetic architecture confers immunity to oomycetes, bacteria, viruses, nematodes, and insects. The network emerged over 100 million years ago from a linked NLR pair that diversified into up to one half of the NLR of asterid plants. We propose that this NLR network increases robustness of immune signaling to counteract rapidly evolving plant pathogens.
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216
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Abstract
The respiratory immune response consists of multiple tiers of cellular responses that are engaged in a sequential manner in order to control infections. The stepwise engagement of effector functions with progressively increasing host fitness costs limits tissue damage. In addition, specific mechanisms are in place to promote disease tolerance in response to respiratory infections. Environmental factors, obesity and the ageing process can alter the efficiency and regulation of this tiered response, increasing pathology and mortality as a result. In this Review, we describe the cell types that coordinate pathogen clearance and tissue repair through the serial secretion of cytokines, and discuss how the environment and comorbidity influence this response.
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217
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Deviant Behavior: Tick-Borne Pathogens and Inflammasome Signaling. Vet Sci 2016; 3:vetsci3040027. [PMID: 29056735 PMCID: PMC5606592 DOI: 10.3390/vetsci3040027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/22/2016] [Accepted: 09/23/2016] [Indexed: 12/11/2022] Open
Abstract
In the face of an assault, host cells mount an immediate response orchestrated by innate immunity. Two of the best described innate immune signaling networks are the Toll- and the Nod-like receptor pathways. Extensive work has been done characterizing both signaling cascades with several recent advances on the forefront of inflammasome biology. In this review, we will discuss how more commonly-studied pathogens differ from tick-transmitted microbes in the context of Nod-like receptor signaling and inflammasome formation. Because pathogens transmitted by ticks have unique characteristics, we offer the opinion that these microbes can be used to uncover novel principles of Nod-like receptor biology.
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218
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Kim BH, Chee JD, Bradfield CJ, Park ES, Kumar P, MacMicking JD. Interferon-induced guanylate-binding proteins in inflammasome activation and host defense. Nat Immunol 2016; 17:481-9. [PMID: 27092805 DOI: 10.1038/ni.3440] [Citation(s) in RCA: 107] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 03/16/2016] [Indexed: 02/06/2023]
Abstract
Traditional views of the inflammasome highlight the assembly of pre-existing core components shortly after infection or tissue damage. Emerging work, however, suggests that the inflammasome machinery is also subject to 'tunable' or inducible signals that might accelerate its autocatalytic properties and dictate where inflammasome assembly takes place in the cell. Many of these signals operate downstream of interferon receptors to elicit inflammasome regulators, including a new family of interferon-induced GTPases called 'guanylate-binding proteins' (GBPs). Here we investigate the critical roles of interferon-induced GBPs in directing inflammasome subtype-specific responses and their consequences for cell-autonomous immunity to a wide variety of microbial pathogens. We discuss emerging mechanisms of action and the potential effect of these GBPs on predisposition to sepsis and other infectious or inflammatory diseases.
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Affiliation(s)
- Bae-Hoon Kim
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jonathan D Chee
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Clinton J Bradfield
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Eui-Soon Park
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Pradeep Kumar
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - John D MacMicking
- Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
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219
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Wang HW, Lei J, Shi Y. Biological cryo-electron microscopy in China. Protein Sci 2016; 26:16-31. [PMID: 27534377 PMCID: PMC5192968 DOI: 10.1002/pro.3018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 08/11/2016] [Accepted: 08/11/2016] [Indexed: 12/16/2022]
Abstract
Cryo‐electron microscopy (cryo‐EM) plays an increasingly more important role in structural biology. With the construction of an arm of the Chinese National Protein Science Facility at Tsinghua University, biological cryo‐EM has entered a phase of rapid development in China. This article briefly reviews the history of biological cryo‐EM in China, describes its current status, comments on its impact on the various biological research fields, and presents future outlook.
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Affiliation(s)
- Hong-Wei Wang
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Jianlin Lei
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, 100084, China
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220
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Yen H, Karino M, Tobe T. Modulation of the Inflammasome Signaling Pathway by Enteropathogenic and Enterohemorrhagic Escherichia coli. Front Cell Infect Microbiol 2016; 6:89. [PMID: 27617233 PMCID: PMC4999430 DOI: 10.3389/fcimb.2016.00089] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 08/11/2016] [Indexed: 01/07/2023] Open
Abstract
Innate immunity is an essential component in the protection of a host against pathogens. Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC, respectively) are known to modulate the innate immune responses of infected cells. The interference is dependent on their type III secretion system (T3SS) and T3SS-dependent effector proteins. Furthermore, these cytosolically injected effectors have been demonstrated to engage multiple immune signaling pathways, including the IFN/STAT, MAPK, NF-κB, and inflammasome pathways. In this review, recent work describing the interaction between EPEC/EHEC and the inflammasome pathway will be discussed.
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Affiliation(s)
- Hilo Yen
- Department of Biomedical Informatics, Graduate School of Medicine, Osaka University Osaka, Japan
| | - Masaki Karino
- Department of Biomedical Informatics, Graduate School of Medicine, Osaka University Osaka, Japan
| | - Toru Tobe
- Department of Biomedical Informatics, Graduate School of Medicine, Osaka University Osaka, Japan
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221
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Glucosylation Drives the Innate Inflammatory Response to Clostridium difficile Toxin A. Infect Immun 2016; 84:2317-2323. [PMID: 27271747 DOI: 10.1128/iai.00327-16] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 05/25/2016] [Indexed: 02/04/2023] Open
Abstract
Clostridium difficile is a major, life-threatening hospital-acquired pathogen that causes mild to severe colitis in infected individuals. The tissue destruction and inflammation which characterize C. difficile infection (CDI) are primarily due to the Rho-glucosylating toxins A and B. These toxins cause epithelial cell death and induce robust inflammatory signaling by activating the transcription factor NF-κB, leading to chemokine and cytokine secretion. The toxins also activate the inflammasome complex, which leads to secretion of the pyrogenic cytokine IL-1β. In this study, we utilized glucosylation-deficient toxin A to show that activation of the inflammasome by this toxin is dependent on Rho glucosylation, confirming similar findings reported for toxin B. We also demonstrated that tissue destruction and in vivo inflammatory cytokine production are critically dependent on the enzymatic activity of toxin A, suggesting that inhibiting toxin glucosyltransferase activity may be effective in combating this refractory disease.
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222
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Sborgi L, Rühl S, Mulvihill E, Pipercevic J, Heilig R, Stahlberg H, Farady CJ, Müller DJ, Broz P, Hiller S. GSDMD membrane pore formation constitutes the mechanism of pyroptotic cell death. EMBO J 2016; 35:1766-78. [PMID: 27418190 PMCID: PMC5010048 DOI: 10.15252/embj.201694696] [Citation(s) in RCA: 785] [Impact Index Per Article: 98.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 06/28/2016] [Indexed: 12/18/2022] Open
Abstract
Pyroptosis is a lytic type of cell death that is initiated by inflammatory caspases. These caspases are activated within multi‐protein inflammasome complexes that assemble in response to pathogens and endogenous danger signals. Pyroptotic cell death has been proposed to proceed via the formation of a plasma membrane pore, but the underlying molecular mechanism has remained unclear. Recently, gasdermin D (GSDMD), a member of the ill‐characterized gasdermin protein family, was identified as a caspase substrate and an essential mediator of pyroptosis. GSDMD is thus a candidate for pyroptotic pore formation. Here, we characterize GSDMD function in live cells and in vitro. We show that the N‐terminal fragment of caspase‐1‐cleaved GSDMD rapidly targets the membrane fraction of macrophages and that it induces the formation of a plasma membrane pore. In vitro, the N‐terminal fragment of caspase‐1‐cleaved recombinant GSDMD tightly binds liposomes and forms large permeability pores. Visualization of liposome‐inserted GSDMD at nanometer resolution by cryo‐electron and atomic force microscopy shows circular pores with variable ring diameters around 20 nm. Overall, these data demonstrate that GSDMD is the direct and final executor of pyroptotic cell death.
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Affiliation(s)
| | | | - Estefania Mulvihill
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Basel, Switzerland
| | | | | | | | | | - Daniel J Müller
- Department of Biosystems Science and Engineering, Eidgenössische Technische Hochschule (ETH) Zurich, Basel, Switzerland
| | - Petr Broz
- Biozentrum, University of Basel, Basel, Switzerland
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223
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Loss of the DNA Damage Repair Kinase ATM Impairs Inflammasome-Dependent Anti-Bacterial Innate Immunity. Immunity 2016; 45:106-18. [PMID: 27421701 DOI: 10.1016/j.immuni.2016.06.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 01/20/2016] [Accepted: 06/15/2016] [Indexed: 01/06/2023]
Abstract
The ATM kinase is a central component of the DNA damage repair machinery and redox balance. ATM dysfunction results in the multisystem disease ataxia-telangiectasia (AT). A major cause of mortality in AT is respiratory bacterial infections. Whether ATM deficiency causes innate immune defects that might contribute to bacterial infections is not known. Here we have shown that loss of ATM impairs inflammasome-dependent anti-bacterial innate immunity. Cells from AT patients or Atm(-/-) mice exhibited diminished interleukin-1β (IL-1β) production in response to bacteria. In vivo, Atm(-/-) mice were more susceptible to pulmonary S. pneumoniae infection in a manner consistent with inflammasome defects. Our data indicate that such defects were due to oxidative inhibition of inflammasome complex assembly. This study reveals an unanticipated function of reactive oxygen species (ROS) in negative regulation of inflammasomes and proposes a theory for the notable susceptibility of AT patients to pulmonary bacterial infection.
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224
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ASC filament formation serves as a signal amplification mechanism for inflammasomes. Nat Commun 2016; 7:11929. [PMID: 27329339 PMCID: PMC4917984 DOI: 10.1038/ncomms11929] [Citation(s) in RCA: 270] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 05/11/2016] [Indexed: 12/13/2022] Open
Abstract
A hallmark of inflammasome activation is the ASC speck, a micrometre-sized structure formed by the inflammasome adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD), which consists of a pyrin domain (PYD) and a caspase recruitment domain (CARD). Here we show that assembly of the ASC speck involves oligomerization of ASCPYD into filaments and cross-linking of these filaments by ASCCARD. ASC mutants with a non-functional CARD only assemble filaments but not specks, and moreover disrupt endogenous specks in primary macrophages. Systematic site-directed mutagenesis of ASCPYD is used to identify oligomerization-deficient ASC mutants and demonstrate that ASC speck formation is required for efficient processing of IL-1β, but dispensable for gasdermin-D cleavage and pyroptosis induction. Our results suggest that the oligomerization of ASC creates a multitude of potential caspase-1 activation sites, thus serving as a signal amplification mechanism for inflammasome-mediated cytokine production. Inflammasomes regulate IL-1β family maturation and pyroptosis. Here the authors show that ASC oligomerization and the formation of ASC specks are needed for IL-1β processing, but are not required for pyroptosis, indicating distinct inflammasome regulatory pathways.
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225
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Abstract
Inflammasomes are multiprotein signalling platforms that control the inflammatory response and coordinate antimicrobial host defences. They are assembled by pattern-recognition receptors following the detection of pathogenic microorganisms and danger signals in the cytosol of host cells, and they activate inflammatory caspases to produce cytokines and to induce pyroptotic cell death. The clinical importance of inflammasomes reaches beyond infectious disease, as dysregulated inflammasome activity is associated with numerous hereditary and acquired inflammatory disorders. In this Review, we discuss the recent developments in inflammasome research with a focus on the molecular mechanisms that govern inflammasome assembly, signalling and regulation.
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Affiliation(s)
- Petr Broz
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Vishva M Dixit
- Genentech Inc., South San Francisco, California 94080, USA
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226
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Maltez VI, Miao EA. Reassessing the Evolutionary Importance of Inflammasomes. THE JOURNAL OF IMMUNOLOGY 2016; 196:956-62. [PMID: 26802061 DOI: 10.4049/jimmunol.1502060] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Inflammasomes monitor the cytosol for microbial contamination or perturbation and, thus, are predicted to provide potent defense against infection. However, the compendium of data from murine infection models suggests that inflammasomes merely delay the course of disease, allowing the host time to mount an adaptive response. Interpretations of such results are confounded by inflammasome-evasion strategies of vertebrate-adapted pathogens. Conversely, environmental opportunistic pathogens have not evolved in the context of inflammasomes and, therefore, are less likely to evade them. Indeed, opportunistic pathogens do not normally cause disease in wild-type animals. Accordantly, the extreme virulence of two opportunistic bacterial pathogens, Burkholderia thailandensis and Chromobacterium violaceum, is fully counteracted by inflammasomes in murine models. This leads us to propose a new hypothesis: perhaps animals maintain inflammasomes over evolutionary time not to defend against vertebrate-adapted pathogens but instead to counteract infection by a plethora of undiscovered opportunistic pathogens residing in the environment.
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Affiliation(s)
- Vivien I Maltez
- Department of Microbiology and Immunology, Center for Gastrointestinal Biology and Disease, and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Edward A Miao
- Department of Microbiology and Immunology, Center for Gastrointestinal Biology and Disease, and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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227
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Crystal structure of NOD2 and its implications in human disease. Nat Commun 2016; 7:11813. [PMID: 27283905 PMCID: PMC4906405 DOI: 10.1038/ncomms11813] [Citation(s) in RCA: 115] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 05/03/2016] [Indexed: 12/30/2022] Open
Abstract
Nucleotide-binding oligomerization domain-containing protein 2 (NOD2), a member of the NOD-like receptors family, are crucial for innate immune responses. Mutations of NOD2 have been associated with chronic inflammatory disorders such as Crohn's disease (CD), Blau syndrome (BS) and early-onset sarcoidosis (EOS), but little is known about its signalling mechanism and the role it plays in these diseases. Here, we report the crystal structure of rabbit NOD2 in an ADP-bound state. The structure reveals an inactive closed conformation in which the subdomains in the NOD domain are closely packed by ADP-mediated and inter-domain interactions. Mapping of the BS- or EOS-associated gain-of-function mutations reveals that most of these mutations are located in the NOD subdomain interfaces, and are likely to disrupt the inner domain interactions, facilitating a conformational change to the active form. Conversely, mutations associated with CD are distributed throughout the protein, some of which may affect oligomer formation and ligand binding. NOD2 has a role in host innate immune responses, activating the NF-κB signalling pathway and mutations have been associated with chronic inflammatory disorders. Here, Maekawa et al. solved the structure of NOD2 in its inactive form, suggesting a mechanism for autoinhibition.
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228
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Dawson HD, Smith AD, Chen C, Urban JF. An in-depth comparison of the porcine, murine and human inflammasomes; lessons from the porcine genome and transcriptome. Vet Microbiol 2016; 202:2-15. [PMID: 27321134 DOI: 10.1016/j.vetmic.2016.05.013] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 04/26/2016] [Accepted: 05/26/2016] [Indexed: 12/14/2022]
Abstract
Emerging evidence suggests that swine are a scientifically acceptable intermediate species between rodents and humans to model immune function relevant to humans. The swine genome has recently been sequenced and several preliminary structural and functional analysis of the porcine immunome have been published. Herein we provide an expanded in silico analysis using an improved assembly of the porcine transcriptome that provides an in depth analysis of genes that are related to inflammasomes, responses to Toll-like receptor ligands, and M1 macrophage polarization and Escherichia coli as a model organism. Comparisons of the expansion or contraction of orthologous gene families indicated more similar rates and classes of genes in humans and pigs than in mice; however several novel porcine or artiodactyl-specific paralogs or pseudogenes were identified. Conservation of homology and structural motifs of orthologs revealed that the overall similarity to human proteins was significantly higher for pigs compared to mouse. Despite these similarities, two out of four canonical inflammasome pathways, Absent in melanoma 2 (AIM2) and NLR family and CARD domain containing 4 (NLRC4), were found to be missing in pigs. Pig M1 Mφ polarization in response to interferon-γ (IFN-γ) and lipopolysaccharide (LPS) was assessed, via the transcriptome, using next generation sequencing. Our analysis revealed predominantly human-like responses however some, mouse-like responses were observed, as well as induction of numerous pig or artiodactyl-specific genes. This work supports using swine to model both human immunological and inflammatory responses to infection. However, caution must be exercised as pigs differ from humans in several fundamental pathways.
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Affiliation(s)
- Harry D Dawson
- Rm 224, Bld 307C, Beltsville Human Nutrition Research Center, Beltsville, MD 20705, USA; U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics and Immunology Laboratory, Beltsville, MD 20705, USA.
| | - Allen D Smith
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics and Immunology Laboratory, Beltsville, MD 20705, USA
| | - Celine Chen
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics and Immunology Laboratory, Beltsville, MD 20705, USA
| | - Joseph F Urban
- U.S. Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Diet, Genomics and Immunology Laboratory, Beltsville, MD 20705, USA
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229
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Mitchell G, Chen C, Portnoy DA. Strategies Used by Bacteria to Grow in Macrophages. Microbiol Spectr 2016; 4:10.1128/microbiolspec.MCHD-0012-2015. [PMID: 27337444 PMCID: PMC4922531 DOI: 10.1128/microbiolspec.mchd-0012-2015] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Indexed: 12/24/2022] Open
Abstract
Intracellular bacteria are often clinically relevant pathogens that infect virtually every cell type found in host organisms. However, myeloid cells, especially macrophages, constitute the primary cells targeted by most species of intracellular bacteria. Paradoxically, macrophages possess an extensive antimicrobial arsenal and are efficient at killing microbes. In addition to their ability to detect and signal the presence of pathogens, macrophages sequester and digest microorganisms using the phagolysosomal and autophagy pathways or, ultimately, eliminate themselves through the induction of programmed cell death. Consequently, intracellular bacteria influence numerous host processes and deploy sophisticated strategies to replicate within these host cells. Although most intracellular bacteria have a unique intracellular life cycle, these pathogens are broadly categorized into intravacuolar and cytosolic bacteria. Following phagocytosis, intravacuolar bacteria reside in the host endomembrane system and, to some extent, are protected from the host cytosolic innate immune defenses. However, the intravacuolar lifestyle requires the generation and maintenance of unique specialized bacteria-containing vacuoles and involves a complex network of host-pathogen interactions. Conversely, cytosolic bacteria escape the phagolysosomal pathway and thrive in the nutrient-rich cytosol despite the presence of host cell-autonomous defenses. The understanding of host-pathogen interactions involved in the pathogenesis of intracellular bacteria will continue to provide mechanistic insights into basic cellular processes and may lead to the discovery of novel therapeutics targeting infectious and inflammatory diseases.
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Affiliation(s)
- Gabriel Mitchell
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Chen Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniel A. Portnoy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA
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230
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Stewart MK, Cookson BT. Evasion and interference: intracellular pathogens modulate caspase-dependent inflammatory responses. Nat Rev Microbiol 2016; 14:346-59. [PMID: 27174147 DOI: 10.1038/nrmicro.2016.50] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pathogens have evolved to complete the virulence cycle of colonization, replication and dissemination in intimate association with a complex network of extracellular and intracellular surveillance systems that guard tissue spaces. In this Review, we discuss the strategies used by bacteria and viruses to evade or inhibit intracellular detection that is coupled to pro-inflammatory caspase-dependent protective responses. Such strategies include alterations of lipopolysaccharide (LPS) structures, the regulated expression of components of type III secretion systems, and the utilization of proteins that inhibit inflammasome formation, the enzymatic activity of caspases and cytokine signalling. Inflammation is crucial in response to exposure to pathogens, but is potentially damaging and thus tightly regulated. The threshold for the activation of pro-inflammatory caspases is determined by the immediate stimulus in the context of previous signals. Pathogen, genetic and situational factors modulate this threshold, which determines the ability of the host to resist infection while minimizing harm.
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Affiliation(s)
- Mary K Stewart
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA
| | - Brad T Cookson
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA.,Department of Laboratory Medicine, University of Washington, Seattle, Washington 98195, USA
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231
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Shaw DK, Kotsyfakis M, Pedra JHF. For Whom the Bell Tolls (and Nods): Spit-acular Saliva. CURRENT TROPICAL MEDICINE REPORTS 2016; 3:40-50. [PMID: 27547699 DOI: 10.1007/s40475-016-0072-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Having emerged during the early part of the Cretaceous period, ticks are an ancient group of hematophagous ectoparasites with significant veterinary and public health importance worldwide. The success of their life strategy can be attributed, in part, to saliva. As we enter into a scientific era where the collection of massive data sets and structures for biological application is possible, we suggest that understanding the molecular mechanisms that govern the life cycle of ticks is within grasp. With this in mind, we discuss what is currently known regarding the manipulation of Toll-like (TLR) and Nod-like (NLR) receptor signaling pathways by tick salivary proteins, and how these molecules impact pathogen transmission.
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Affiliation(s)
- Dana K Shaw
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
| | - Michail Kotsyfakis
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, Budweis, Czech Republic
| | - Joao H F Pedra
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, USA.
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232
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Rauch I, Tenthorey JL, Nichols RD, Al Moussawi K, Kang JJ, Kang C, Kazmierczak BI, Vance RE. NAIP proteins are required for cytosolic detection of specific bacterial ligands in vivo. J Exp Med 2016; 213:657-65. [PMID: 27045008 PMCID: PMC4854734 DOI: 10.1084/jem.20151809] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 03/16/2016] [Indexed: 11/16/2022] Open
Abstract
Vance et al. provide genetic proof for the specificity and essentiality of NAIP proteins for inflammasome responses to specific bacterial ligands in vivo. NLRs (nucleotide-binding domain [NBD] leucine-rich repeat [LRR]–containing proteins) exhibit diverse functions in innate and adaptive immunity. NAIPs (NLR family, apoptosis inhibitory proteins) are NLRs that appear to function as cytosolic immunoreceptors for specific bacterial proteins, including flagellin and the inner rod and needle proteins of bacterial type III secretion systems (T3SSs). Despite strong biochemical evidence implicating NAIPs in specific detection of bacterial ligands, genetic evidence has been lacking. Here we report the use of CRISPR/Cas9 to generate Naip1−/− and Naip2−/− mice, as well as Naip1-6Δ/Δ mice lacking all functional Naip genes. By challenging Naip1−/− or Naip2−/− mice with specific bacterial ligands in vivo, we demonstrate that Naip1 is uniquely required to detect T3SS needle protein and Naip2 is uniquely required to detect T3SS inner rod protein, but neither Naip1 nor Naip2 is required for detection of flagellin. Previously generated Naip5−/− mice retain some residual responsiveness to flagellin in vivo, whereas Naip1-6Δ/Δ mice fail to respond to cytosolic flagellin, consistent with previous biochemical data implicating NAIP6 in flagellin detection. Our results provide genetic evidence that specific NAIP proteins function to detect specific bacterial proteins in vivo.
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Affiliation(s)
- Isabella Rauch
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Jeannette L Tenthorey
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Randilea D Nichols
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Khatoun Al Moussawi
- Department of Medicine, Yale University School of Medicine, New Haven, CT 06510
| | - James J Kang
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Chulho Kang
- Cancer Research Laboratory, University of California, Berkeley, Berkeley, CA 94720
| | - Barbara I Kazmierczak
- Department of Medicine, Yale University School of Medicine, New Haven, CT 06510 Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510
| | - Russell E Vance
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720 Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720 Cancer Research Laboratory, University of California, Berkeley, Berkeley, CA 94720
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233
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Uncovering an Important Role for YopJ in the Inhibition of Caspase-1 in Activated Macrophages and Promoting Yersinia pseudotuberculosis Virulence. Infect Immun 2016; 84:1062-1072. [PMID: 26810037 DOI: 10.1128/iai.00843-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 01/19/2016] [Indexed: 02/06/2023] Open
Abstract
Pathogenic Yersinia species utilize a type III secretion system to translocate Yop effectors into infected host cells. Yop effectors inhibit innate immune responses in infected macrophages to promote Yersinia pathogenesis. In turn,Yersinia-infected macrophages respond to translocation of Yops by activating caspase-1, but different mechanisms of caspase-1 activation occur, depending on the bacterial genotype and the state of phagocyte activation. In macrophages activated with lipopolysaccharide (LPS) prior to Yersinia pseudotuberculosis infection, caspase-1 is activated by a rapid inflammasome-dependent mechanism that is inhibited by translocated YopM. The possibility that other effectors cooperate with YopM to inhibit caspase-1 activation in LPS-activated macrophages has not been investigated. Toward this aim, epistasis analysis was carried out in which the phenotype of aY. pseudotuberculosis yopM mutant was compared to that of a yopJ yopM, yopE yopM, yopH yopM, yopT yopM, or ypkA yopM mutant. Activation of caspase-1 was measured by cleavage of the enzyme, release of interleukin-1β (IL-1β), and pyroptosis in LPS-activated macrophages infected with wild-type or mutant Y. pseudotuberculosis strains. Results show enhanced activation of caspase-1 after infection with the yopJ yopM mutant relative to infection by any other single or double mutant. Similar results were obtained with the yopJ, yopM, and yopJ yopM mutants ofY ersinia pestis Following intravenous infection of mice, theY. pseudotuberculosis yopJ mutant was as virulent as the wild type, while the yopJ yopM mutant was significantly more attenuated than the yopM mutant. In summary, through epistasis analysis this work uncovered an important role for YopJ in inhibiting caspase-1 in activated macrophages and in promoting Yersinia virulence.
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234
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Kim SH, Qi D, Ashfield T, Helm M, Innes RW. Using decoys to expand the recognition specificity of a plant disease resistance protein. Science 2016; 351:684-7. [PMID: 26912853 DOI: 10.1126/science.aad3436] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Maintaining high crop yields in an environmentally sustainable manner requires the development of disease-resistant crop varieties. We describe a method to engineer disease resistance in plants by means of an endogenous disease resistance gene from Arabidopsis thaliana named RPS5, which encodes a nucleotide-binding leucine-rich repeat (NLR) protein. RPS5 is normally activated when a second host protein, PBS1, is cleaved by the pathogen-secreted protease AvrPphB. We show that the AvrPphB cleavage site within PBS1 can be substituted with cleavage sites for other pathogen proteases, which then enables RPS5 to be activated by these proteases, thereby conferring resistance to new pathogens. This "decoy" approach may be applicable to other NLR proteins and should enable engineering of resistance in plants to diseases for which we currently lack robust genetic resistance.
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Affiliation(s)
- Sang Hee Kim
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Dong Qi
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Tom Ashfield
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Matthew Helm
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Roger W Innes
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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235
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Pha K, Navarro L. Yersinia type III effectors perturb host innate immune responses. World J Biol Chem 2016; 7:1-13. [PMID: 26981193 PMCID: PMC4768113 DOI: 10.4331/wjbc.v7.i1.1] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 09/02/2015] [Accepted: 11/04/2015] [Indexed: 02/05/2023] Open
Abstract
The innate immune system is the first line of defense against invading pathogens. Innate immune cells recognize molecular patterns from the pathogen and mount a response to resolve the infection. The production of proinflammatory cytokines and reactive oxygen species, phagocytosis, and induced programmed cell death are processes initiated by innate immune cells in order to combat invading pathogens. However, pathogens have evolved various virulence mechanisms to subvert these responses. One strategy utilized by Gram-negative bacterial pathogens is the deployment of a complex machine termed the type III secretion system (T3SS). The T3SS is composed of a syringe-like needle structure and the effector proteins that are injected directly into a target host cell to disrupt a cellular response. The three human pathogenic Yersinia spp. (Y. pestis, Y. enterocolitica, and Y. pseudotuberculosis) are Gram-negative bacteria that share in common a 70 kb virulence plasmid which encodes the T3SS. Translocation of the Yersinia effector proteins (YopE, YopH, YopT, YopM, YpkA/YopO, and YopP/J) into the target host cell results in disruption of the actin cytoskeleton to inhibit phagocytosis, downregulation of proinflammatory cytokine/chemokine production, and induction of cellular apoptosis of the target cell. Over the past 25 years, studies on the Yersinia effector proteins have unveiled tremendous knowledge of how the effectors enhance Yersinia virulence. Recently, the long awaited crystal structure of YpkA has been solved providing further insights into the activation of the YpkA kinase domain. Multisite autophosphorylation by YpkA to activate its kinase domain was also shown and postulated to serve as a mechanism to bypass regulation by host phosphatases. In addition, novel Yersinia effector protein targets, such as caspase-1, and signaling pathways including activation of the inflammasome were identified. In this review, we summarize the recent discoveries made on Yersinia effector proteins and their contribution to Yersinia pathogenesis.
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Zhong Z, Umemura A, Sanchez-Lopez E, Liang S, Shalapour S, Wong J, He F, Boassa D, Perkins G, Ali SR, McGeough MD, Ellisman MH, Seki E, Gustafsson AB, Hoffman HM, Diaz-Meco MT, Moscat J, Karin M. NF-κB Restricts Inflammasome Activation via Elimination of Damaged Mitochondria. Cell 2016; 164:896-910. [PMID: 26919428 PMCID: PMC4769378 DOI: 10.1016/j.cell.2015.12.057] [Citation(s) in RCA: 818] [Impact Index Per Article: 102.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 11/12/2015] [Accepted: 12/29/2015] [Indexed: 12/11/2022]
Abstract
Nuclear factor κB (NF-κB), a key activator of inflammation, primes the NLRP3-inflammasome for activation by inducing pro-IL-1β and NLRP3 expression. NF-κB, however, also prevents excessive inflammation and restrains NLRP3-inflammasome activation through a poorly defined mechanism. We now show that NF-κB exerts its anti-inflammatory activity by inducing delayed accumulation of the autophagy receptor p62/SQSTM1. External NLRP3-activating stimuli trigger a form of mitochondrial (mt) damage that is caspase-1- and NLRP3-independent and causes release of direct NLRP3-inflammasome activators, including mtDNA and mtROS. Damaged mitochondria undergo Parkin-dependent ubiquitin conjugation and are specifically recognized by p62, which induces their mitophagic clearance. Macrophage-specific p62 ablation causes pronounced accumulation of damaged mitochondria and excessive IL-1β-dependent inflammation, enhancing macrophage death. Therefore, the "NF-κB-p62-mitophagy" pathway is a macrophage-intrinsic regulatory loop through which NF-κB restrains its own inflammation-promoting activity and orchestrates a self-limiting host response that maintains homeostasis and favors tissue repair.
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Affiliation(s)
- Zhenyu Zhong
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Atsushi Umemura
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Molecular Gastroenterology and Hepatology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Elsa Sanchez-Lopez
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Shuang Liang
- Division of Gastroenterology, Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Shabnam Shalapour
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Jerry Wong
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Feng He
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Daniela Boassa
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Guy Perkins
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Syed Raza Ali
- Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Matthew D McGeough
- Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Ekihiro Seki
- Division of Gastroenterology, Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Division of Gastroenterology, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Asa B Gustafsson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Hal M Hoffman
- Department of Pediatrics, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Maria T Diaz-Meco
- Sanford-Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Jorge Moscat
- Sanford-Burnham Prebys Medical Discovery Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Michael Karin
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Pathology, School of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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Li W, Chang Y, Liang S, Zhong Z, Li X, Wen J, Zhang Y, Zhang J, Wang L, Lin H, Cao X, Huang H, Zhong F. NLRP3 inflammasome activation contributes to Listeria monocytogenes-induced animal pregnancy failure. BMC Vet Res 2016; 12:36. [PMID: 26911557 PMCID: PMC4765044 DOI: 10.1186/s12917-016-0655-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 02/15/2016] [Indexed: 12/11/2022] Open
Abstract
Background Listeria monocytogenes (LM), a foodborne pathogen, can cause pregnancy failure in animals, especially in ruminants. Recent studies have shown that LM activates inflammasomes to induce IL-1β release in macrophages, however, whether the inflammasome activation regulates LM-induced pregnancy failure remains largely unknown. Here we used mouse model to investigate the molecular mechanism by which LM-induced inflammsome activation contributes to LM-associated pregnancy failure Results We showed that wild-type, but not Listeriolysin O-deficient (Δhly) LM, significantly reduced mouse embryo survival, accompanied by the increase of IL-1β release and caspase-1 activation. IL-1β neutralization significantly reduced the LM-induced embryo losses, suggesting that LM-induced pregnancy failure was associated with LLO-induced inflammasome activation. To dissect the inflammasome sensor and components responsible for LM-induced caspase-1 activation and IL-1β production, we used wild-type and NLRP3−/−, AIM2−/−, NLRC4−/−, ASC−/−, caspase-1−/− and cathepsin B−/− mouse macrophages to test the roles of these molecules in LM-induce IL-1β production. We found that NLRP3 inflammasome was the main pathway in LM-induced caspase-1 activation and IL-1β production. To explore the mechanism of LM-induced pregnancy failure, we investigated the effects of LM-infected macrophages on SM9-1 mouse trophoblasts. We found that the conditioned medium from LM-infected-macrophage or the recombinant IL-1β significantly up-regulated TNFα, IL-6 and IL-8 productions in trophoblasts, suggesting that the LM-induced macrophage inflammasome activation increased trophoblast pro-inflammatory cytokine production, which was adverse to the animal pregnancy maintenance. Conclusions Our data demonstrated that the LLO-induced NLRP3 inflammasome activation plays a key role in LM-induced pregnancy failure, and inflammasome-mediated macrophage dysregulation on trophoblasts might be involved in the pregnancy failure.
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Affiliation(s)
- Wenyan Li
- Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei; Hebei Engineering and Technology Research Center of Veterinary Biotechnology, Baoding, 071000, China. .,Department of Biology, School of Medicine, Hebei University, Baoding, 071000, China.
| | - Yumei Chang
- Department of Gynaecology and Obstetrics, 252 Hospital of Chinese PLA, Baoding, 071000, China.
| | - Shuang Liang
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Zhenyu Zhong
- Department of Pharmacology, School of Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
| | - Xiujin Li
- Department of Biotechnology, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, 066004, China.
| | - Jiexia Wen
- Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei; Hebei Engineering and Technology Research Center of Veterinary Biotechnology, Baoding, 071000, China.
| | - Yonghong Zhang
- Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei; Hebei Engineering and Technology Research Center of Veterinary Biotechnology, Baoding, 071000, China.
| | - Jianlou Zhang
- Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei; Hebei Engineering and Technology Research Center of Veterinary Biotechnology, Baoding, 071000, China.
| | - Liyue Wang
- Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei; Hebei Engineering and Technology Research Center of Veterinary Biotechnology, Baoding, 071000, China.
| | - Hongyu Lin
- Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei; Hebei Engineering and Technology Research Center of Veterinary Biotechnology, Baoding, 071000, China. .,Department of Biotechnology, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, 066004, China.
| | - Xuebin Cao
- Department of Gynaecology and Obstetrics, 252 Hospital of Chinese PLA, Baoding, 071000, China.
| | - Heling Huang
- Department of Gynaecology and Obstetrics, 252 Hospital of Chinese PLA, Baoding, 071000, China.
| | - Fei Zhong
- Laboratory of Molecular Virology and Immunology, College of Veterinary Medicine, Agricultural University of Hebei; Hebei Engineering and Technology Research Center of Veterinary Biotechnology, Baoding, 071000, China.
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Oh JY, Ko JH, Ryu JS, Lee HJ, Kim MK, Wee WR. Transcription Profiling of NOD-like Receptors in the Human Cornea with Disease. Ocul Immunol Inflamm 2016; 25:364-369. [PMID: 26902715 DOI: 10.3109/09273948.2015.1130844] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To investigate the expression of nucleotide-binding oligomerization domain-like receptors (NLRs) in human corneas with disease and corneal cells. METHODS The expression of NOD1, NOD2, NLRP1, and NLRP3 was analyzed using real-time RT-PCR in (1) corneas with active infection, history of herpetic stromal keratitis (HSK), chronic allograft rejection, and limbal stem cell deficiency (LSCD), and (2) human corneal cells after lipopolysaccharide (LPS) stimulation. Healthy corneas and cells without LPS served as controls. RESULTS The mRNA levels of NOD2 and NLRP3 were increased in corneas with infection and HSK. Conversely, the levels of NOD1, NOD2, NLRP1, and NLRP3 transcripts were decreased in corneas with LSCD. In corneas with rejection, the expression of NOD1 and NLRP1 was downregulated. Corneal endothelial cells upregulated the expression of NOD2 and NLRP3 upon LPS. CONCLUSIONS The changes in the NLR expression may reflect different susceptibility to infectious and non-infectious injuries in corneas with various diseases.
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Affiliation(s)
- Joo Youn Oh
- a Department of Ophthalmology , Seoul National University Hospital , Jongno-gu , Seoul , Korea.,b Laboratory of Ocular Regenerative Medicine and Immunology, Biomedical Research Institute , National University Hospital , Jongno-gu , Seoul , Korea
| | - Jung Hwa Ko
- b Laboratory of Ocular Regenerative Medicine and Immunology, Biomedical Research Institute , National University Hospital , Jongno-gu , Seoul , Korea
| | - Jin Suk Ryu
- b Laboratory of Ocular Regenerative Medicine and Immunology, Biomedical Research Institute , National University Hospital , Jongno-gu , Seoul , Korea
| | - Hyun Ju Lee
- b Laboratory of Ocular Regenerative Medicine and Immunology, Biomedical Research Institute , National University Hospital , Jongno-gu , Seoul , Korea
| | - Mee Kum Kim
- a Department of Ophthalmology , Seoul National University Hospital , Jongno-gu , Seoul , Korea.,b Laboratory of Ocular Regenerative Medicine and Immunology, Biomedical Research Institute , National University Hospital , Jongno-gu , Seoul , Korea
| | - Won Ryang Wee
- a Department of Ophthalmology , Seoul National University Hospital , Jongno-gu , Seoul , Korea.,b Laboratory of Ocular Regenerative Medicine and Immunology, Biomedical Research Institute , National University Hospital , Jongno-gu , Seoul , Korea
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Brahma B, Patra MC, Mishra P, De BC, Kumar S, Maharana J, Vats A, Ahlawat S, Datta TK, De S. Computational studies on receptor-ligand interactions between novel buffalo (Bubalus bubalis) nucleotide-binding oligomerization domain-containing protein 2 (NOD2) variants and muramyl dipeptide (MDP). J Mol Graph Model 2016; 65:15-26. [PMID: 26897084 DOI: 10.1016/j.jmgm.2016.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 01/25/2016] [Accepted: 02/08/2016] [Indexed: 11/19/2022]
Abstract
Nucleotide binding and oligomerization domain 2 (NOD2), a member of intracellular NOD-like receptors (NLRs) family, recognizes the bacterial peptidoglycan, muramyl dipeptide (MDP) and initiates host immune response. The precise ligand recognition mechanism of NOD2 has remained elusive, although studies have suggested leucine rich repeat (LRR) region of NOD2 as the possible binding site of MDP. In this study, we identified multiple transcripts of NOD2 gene in buffalo (buNOD2) and at least five LRR variants (buNOD2-LRRW (wild type), buNOD2-LRRV1-V4) were found to be expressed in buffalo peripheral blood mononuclear cells. The newly identified buNOD2 transcripts were shorter in lengths as a result of exon-skipping and frame-shift mutations. Among the variants, buNOD2-LRRW, V1, and V3 were expressed more frequently in the animals studied. A comparative receptor-ligand interaction study through modeling of variants, docking, and molecular dynamics simulation revealed that the binding affinity of buNOD2-LRRW towards MDP was greater than that of the shorter variants. The absence of a LRR segment in the buNOD2 variants had probably affected their affinity toward MDP. Notwithstanding a high homology among the variants, the amino acid residues that interact with MDP were located on different LRR motifs. The binding free energy calculation revealed that the amino acids Arg850(LRR4) and Glu932(LRR7) of buNOD2-LRRW, Lys810(LRR3) of buNOD2-LRRV1, and Lys830(LRR3) of buNOD2-LRRV3 largely contributed towards MDP recognition. The knowledge of MDP recognition and binding modes on buNOD2 variants could be useful to understand the regulation of NOD-mediated immune response as well as to develop next generation anti-inflammatory compounds.
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Affiliation(s)
- Biswajit Brahma
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Mahesh Chandra Patra
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Purusottam Mishra
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Bidhan Chandra De
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Sushil Kumar
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Jitendra Maharana
- Department of Bioinformatics, Orissa University of Agriculture and Technology, Bhubaneswar 751003, Odisha, India
| | - Ashutosh Vats
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Sonika Ahlawat
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Tirtha Kumar Datta
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India
| | - Sachinandan De
- Animal Genomics Lab., Animal Biotechnology Centre, National Dairy Research Institute, Karnal 132001, Haryana, India.
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Olsen I, Yilmaz Ö. Modulation of inflammasome activity by Porphyromonas gingivalis in periodontitis and associated systemic diseases. J Oral Microbiol 2016; 8:30385. [PMID: 26850450 PMCID: PMC4744328 DOI: 10.3402/jom.v8.30385] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/06/2016] [Accepted: 01/06/2016] [Indexed: 12/19/2022] Open
Abstract
Inflammasomes are large multiprotein complexes localized in the cytoplasm of the cell. They are responsible for the maturation of pro-inflammatory cytokines such as interleukin-1β (IL-1β) and IL-18 as well as for the activation of inflammatory cell death, the so-called pyroptosis. Inflammasomes assemble in response to cellular infection, cellular stress, or tissue damage; promote inflammatory responses and are of great importance in regulating the innate immune system in chronic inflammatory diseases such as periodontitis and several chronic systemic diseases. In addition to sensing cellular integrity, inflammasomes are involved in the homeostatic mutualism between the indigenous microbiota and the host. There are several types of inflammasomes of which NLRP3 is best characterized in microbial pathogenesis. Many opportunistic bacteria try to evade the innate immune system in order to survive in the host cells. One of these is the periodontopathogen Porphyromonas gingivalis which has been shown to have several mechanisms of modulating innate immunity by limiting the activation of the NLRP3 inflammasome. Among them, ATP-/P2X7- signaling is recently associated not only with periodontitis but also with development of several systemic diseases. The present paper reviews multiple mechanisms through which P. gingivalis can modify innate immunity by affecting inflammasome activity.
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Affiliation(s)
- Ingar Olsen
- Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway;
| | - Özlem Yilmaz
- Department of Oral Health Sciences, Medical University of South Carolina, Charleston, SC, USA
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241
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Mulay SR, Desai J, Kumar SV, Eberhard JN, Thomasova D, Romoli S, Grigorescu M, Kulkarni OP, Popper B, Vielhauer V, Zuchtriegel G, Reichel C, Bräsen JH, Romagnani P, Bilyy R, Munoz LE, Herrmann M, Liapis H, Krautwald S, Linkermann A, Anders HJ. Cytotoxicity of crystals involves RIPK3-MLKL-mediated necroptosis. Nat Commun 2016; 7:10274. [PMID: 26817517 PMCID: PMC4738349 DOI: 10.1038/ncomms10274] [Citation(s) in RCA: 193] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 11/20/2015] [Indexed: 12/22/2022] Open
Abstract
Crystals cause injury in numerous disorders, and induce inflammation via the NLRP3 inflammasome, however, it remains unclear how crystals induce cell death. Here we report that crystals of calcium oxalate, monosodium urate, calcium pyrophosphate dihydrate and cystine trigger caspase-independent cell death in five different cell types, which is blocked by necrostatin-1. RNA interference for receptor-interacting protein kinase 3 (RIPK3) or mixed lineage kinase domain like (MLKL), two core proteins of the necroptosis pathway, blocks crystal cytotoxicity. Consistent with this, deficiency of RIPK3 or MLKL prevents oxalate crystal-induced acute kidney injury. The related tissue inflammation drives TNF-α-related necroptosis. Also in human oxalate crystal-related acute kidney injury, dying tubular cells stain positive for phosphorylated MLKL. Furthermore, necrostatin-1 and necrosulfonamide, an inhibitor for human MLKL suppress crystal-induced cell death in human renal progenitor cells. Together, TNF-α/TNFR1, RIPK1, RIPK3 and MLKL are molecular targets to limit crystal-induced cytotoxicity, tissue injury and organ failure. Kidney stone disease is caused by accumulation of oxalate crystals, which trigger tissue injury, inflammation and cell death. Mulay et al. show that crystals induce cell death in the kidney through necroptosis, and propose that this pathway may be a target for the treatment of crystal-induced disease.
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Affiliation(s)
- Shrikant R Mulay
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Jyaysi Desai
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Santhosh V Kumar
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Jonathan N Eberhard
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Dana Thomasova
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Simone Romoli
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Melissa Grigorescu
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Onkar P Kulkarni
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Bastian Popper
- Department of Anatomy and Cell Biology, Ludwig-Maximilians Universität, Munich 80336, Germany
| | - Volker Vielhauer
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
| | - Gabriele Zuchtriegel
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Munich, Munich 81377, Germany.,Walter Brendel Center for Experimental Medicine, University of Munich, Munich 81377, Germany
| | - Christoph Reichel
- Department of Otorhinolaryngology, Head and Neck Surgery, University of Munich, Munich 81377, Germany.,Walter Brendel Center for Experimental Medicine, University of Munich, Munich 81377, Germany
| | - Jan Hinrich Bräsen
- Department of Nephropathology, Institute for Pathology, Hannover Medical School, Hannover 30625, Germany
| | - Paola Romagnani
- Excellence Centre for Research, Transfer and High Education for the Development of De Novo Therapies (DENOTHE), University of Florence, Florence 50139, Italy
| | - Rostyslav Bilyy
- Danylo Halytsky Lviv National Medical University, Lviv 79010, Ukraine
| | - Luis E Munoz
- Department for Internal Medicine, University Hospital Erlangen, Institute for Clinical Immunology, Erlangen 91054, Germany
| | - Martin Herrmann
- Department for Internal Medicine, University Hospital Erlangen, Institute for Clinical Immunology, Erlangen 91054, Germany
| | - Helen Liapis
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri 63110, USA.,Nephropath, Little Rock, Arkansas 72211, USA
| | - Stefan Krautwald
- Division of Nephrology and Hypertension, Christian-Albrechts-University, Kiel 24105, Germany
| | - Andreas Linkermann
- Division of Nephrology and Hypertension, Christian-Albrechts-University, Kiel 24105, Germany
| | - Hans-Joachim Anders
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität, München, Munich 80336, Germany
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Abstract
Inflammasomes are cytosolic protein complexes that serve as platforms for the recruitment and activation of the pro-inflammatory CASPASE-1 protease. CASPASE-1 activation leads to processing and maturation of the cytokines interleukin-1β and interleukin-18 and a lytic form of cell death termed pyroptosis. Inflammasome assembly is initiated by cytosolic sensors in response to microbial infections. Many of these sensors, including NLRP1 (NLR family, pyrin domain containing 1), are described to form an inflammasome, but until recently, the mechanism of inflammasome activation and its physiological functions in host defense have remained unclear. In the last few years, important advances in our understanding of NLRP1 biology have been achieved. In this review, we discuss the activation of NLRP1 by various stimuli, including Bacillus anthracis lethal toxin, Toxoplasma gondii, muramyl dipeptide, and host intracellular ATP depletion. The role NLRP1 plays in pathogen recognition and resistance during infection is also discussed, as is the regulation of NLRP1 by host and viral proteins. We conclude by discussing the unexpected differences in the mechanism of NLRP1 inflammasome activation, as compared to the activation of other inflammasomes, such as the NAIP (NLR family, apoptosis inhibitory protein)/NLRC4 inflammasomes.
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Affiliation(s)
- Joseph Chavarría-Smith
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
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Pachathundikandi SK, Müller A, Backert S. Inflammasome Activation by Helicobacter pylori and Its Implications for Persistence and Immunity. Curr Top Microbiol Immunol 2016; 397:117-31. [DOI: 10.1007/978-3-319-41171-2_6] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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244
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Bartok E, Kampes M, Hornung V. Measuring IL-1β Processing by Bioluminescence Sensors II: The iGLuc System. Methods Mol Biol 2016; 1417:97-113. [PMID: 27221484 DOI: 10.1007/978-1-4939-3566-6_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Inflammasomes are multimeric protein complexes that proteolytically activate caspase-1, which subsequently matures cytokines of the IL-1 family and initiates the induction of pyroptotic cell death. Although this process is central both to pathogen defense and sterile inflammatory processes, there is currently no standard readout available for inflammasome activation which would be suitable for high-throughput applications. We have recently developed a new method for measuring inflammasome activation via the use of a novel proteolytic reporter iGLuc, an IL-1β Gaussia luciferase (iGLuc) fusion protein. Here, we provide detailed protocols for the use of iGLuc in transiently transfected or stably transduced cell lines. Using these protocols, IL-1β maturation as the result of inflammasome activation or other processes can be indirectly measured via the gain of Gaussia luciferase activity of cleaved iGLuc, allowing for rapid inflammasome reconstitution assays and high-throughput screening of inflammasome activity.
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Affiliation(s)
- Eva Bartok
- Institute of Molecular Medicine, University Hospital, University of Bonn, Sigmund-Freud-Straße 25, Bonn, Germany
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Sigmund-Freud-Straße 25, Bonn, Germany
| | - Maria Kampes
- Institute of Molecular Medicine, University Hospital, University of Bonn, Sigmund-Freud-Straße 25, Bonn, Germany
| | - Veit Hornung
- Institute of Molecular Medicine, University Hospital, University of Bonn, Sigmund-Freud-Straße 25, Bonn, Germany.
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-University Munich, Feodor-Lynen-Str. 25, Munich, Germany.
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245
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Novel Immunomodulatory Flagellin-Like Protein FlaC in Campylobacter jejuni and Other Campylobacterales. mSphere 2015; 1:mSphere00028-15. [PMID: 27303676 PMCID: PMC4863622 DOI: 10.1128/msphere.00028-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 10/28/2015] [Indexed: 11/24/2022] Open
Abstract
Flagellins not only are important for bacterial motility but are major bacterial proteins that can modulate host responses via Toll-like receptor 5 (TLR5) or other pattern recognition receptors. Campylobacterales colonizing the intestinal tracts of different host species harbor a gene coding for an unusual flagellin, FlaC, that is not involved in motility but is secreted and possesses a chimeric amino acid sequence composed of TLR5-activating and non-TLR5-activating flagellin sequences. Campylobacter jejuni FlaC activates cells to increase in cytokine expression in chicken and human cells, promotes cross-tolerance to TLR4 ligands, and alters chicken cecal microbiota. We propose that FlaC is a secreted effector flagellin that has specifically evolved to modulate the immune response in the intestinal tract in the presence of the resident microbiota and may contribute to bacterial persistence. The results also strengthen the role of the flagellar type III apparatus as a functional secretion system for bacterial effector proteins. The human diarrheal pathogens Campylobacter jejuni and Campylobacter coli interfere with host innate immune signaling by different means, and their flagellins, FlaA and FlaB, have a low intrinsic property to activate the innate immune receptor Toll-like receptor 5 (TLR5). We have investigated here the hypothesis that the unusual secreted, flagellin-like molecule FlaC present in C. jejuni, C. coli, and other Campylobacterales might activate cells via TLR5 and interact with TLR5. FlaC shows striking sequence identity in its D1 domains to TLR5-activating flagellins of other bacteria, such as Salmonella, but not to nonstimulating Campylobacter flagellins. We overexpressed and purified FlaC and tested its immunostimulatory properties on cells of human and chicken origin. Treatment of cells with highly purified FlaC resulted in p38 activation. FlaC directly interacted with TLR5. Preincubation with FlaC decreased the responsiveness of chicken and human macrophage-like cells toward the bacterial TLR4 agonist lipopolysaccharide (LPS), suggesting that FlaC mediates cross-tolerance. C. jejuni flaC mutants induced an increase of cell responses in comparison to those of the wild type, which was suppressed by genetic complementation. Supplementing excess purified FlaC likewise reduced the cellular response to C. jejuni. In vivo, the administration of ultrapure FlaC led to a decrease in cecal interleukin 1β (IL-1β) expression and a significant change of the cecal microbiota in chickens. We propose that Campylobacter spp. have evolved a novel type of secreted immunostimulatory flagellin-like effector in order to specifically modulate host responses, for example toward other pattern recognition receptor (PRR) ligands, such as LPS. IMPORTANCE Flagellins not only are important for bacterial motility but are major bacterial proteins that can modulate host responses via Toll-like receptor 5 (TLR5) or other pattern recognition receptors. Campylobacterales colonizing the intestinal tracts of different host species harbor a gene coding for an unusual flagellin, FlaC, that is not involved in motility but is secreted and possesses a chimeric amino acid sequence composed of TLR5-activating and non-TLR5-activating flagellin sequences. Campylobacter jejuni FlaC activates cells to increase in cytokine expression in chicken and human cells, promotes cross-tolerance to TLR4 ligands, and alters chicken cecal microbiota. We propose that FlaC is a secreted effector flagellin that has specifically evolved to modulate the immune response in the intestinal tract in the presence of the resident microbiota and may contribute to bacterial persistence. The results also strengthen the role of the flagellar type III apparatus as a functional secretion system for bacterial effector proteins.
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246
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Fenyk S, Dixon CH, Gittens WH, Townsend PD, Sharples GJ, Pålsson LO, Takken FLW, Cann MJ. The Tomato Nucleotide-binding Leucine-rich Repeat Immune Receptor I-2 Couples DNA-binding to Nucleotide-binding Domain Nucleotide Exchange. J Biol Chem 2015; 291:1137-47. [PMID: 26601946 PMCID: PMC4714197 DOI: 10.1074/jbc.m115.698589] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Indexed: 12/19/2022] Open
Abstract
Plant nucleotide-binding leucine-rich repeat (NLR) proteins enable plants to recognize and respond to pathogen attack. Previously, we demonstrated that the Rx1 NLR of potato is able to bind and bend DNA in vitro. DNA binding in situ requires its genuine activation following pathogen perception. However, it is unknown whether other NLR proteins are also able to bind DNA. Nor is it known how DNA binding relates to the ATPase activity intrinsic to NLR switch function required to immune activation. Here we investigate these issues using a recombinant protein corresponding to the N-terminal coiled-coil and nucleotide-binding domain regions of the I-2 NLR of tomato. Wild type I-2 protein bound nucleic acids with a preference of ssDNA ≈ dsDNA > ssRNA, which is distinct from Rx1. I-2 induced bending and melting of DNA. Notably, ATP enhanced DNA binding relative to ADP in the wild type protein, the null P-loop mutant K207R, and the autoactive mutant S233F. DNA binding was found to activate the intrinsic ATPase activity of I-2. Because DNA binding by I-2 was decreased in the presence of ADP when compared with ATP, a cyclic mechanism emerges; activated ATP-associated I-2 binds to DNA, which enhances ATP hydrolysis, releasing ADP-bound I-2 from the DNA. Thus DNA binding is a general property of at least a subset of NLR proteins, and NLR activation is directly linked to its activity at DNA.
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Affiliation(s)
- Stepan Fenyk
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Christopher H Dixon
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - William H Gittens
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Philip D Townsend
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Gary J Sharples
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
| | - Lars-Olof Pålsson
- the Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom and
| | - Frank L W Takken
- the Molecular Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, 1098 XH, Amsterdam, The Netherlands
| | - Martin J Cann
- From the School of Biological and Biomedical Sciences, the Biophysical Sciences Institute, and
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247
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Stamm CE, Collins AC, Shiloh MU. Sensing of Mycobacterium tuberculosis and consequences to both host and bacillus. Immunol Rev 2015; 264:204-19. [PMID: 25703561 DOI: 10.1111/imr.12263] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mycobacterium tuberculosis (Mtb), the primary causative agent of human tuberculosis, has killed more people than any other bacterial pathogen in human history and remains one of the most important transmissible diseases worldwide. Because of the long-standing interaction of Mtb with humans, it is no surprise that human mucosal and innate immune cells have evolved multiple mechanisms to detect Mtb during initial contact. To that end, the cell surface of human cells is decorated with numerous pattern recognition receptors for a variety of mycobacterial ligands. Furthermore, once Mtb is ingested into professional phagocytes, other host molecules are engaged to report on the presence of an intracellular pathogen. In this review, we discuss the role of specific mycobacterial products in modulating the host's ability to detect Mtb. In addition, we describe the specific host receptors that mediate the detection of mycobacterial infection and the role of individual receptors in mycobacterial pathogenesis in humans and model organisms.
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Affiliation(s)
- Chelsea E Stamm
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, USA
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248
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Schieber AMP, Lee YM, Chang MW, Leblanc M, Collins B, Downes M, Evans RM, Ayres JS. Disease tolerance mediated by microbiome E. coli involves inflammasome and IGF-1 signaling. Science 2015; 350:558-63. [PMID: 26516283 DOI: 10.1126/science.aac6468] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Infections and inflammation can lead to cachexia and wasting of skeletal muscle and fat tissue by as yet poorly understood mechanisms. We observed that gut colonization of mice by a strain of Escherichia coli prevents wasting triggered by infections or physical damage to the intestine. During intestinal infection with the pathogen Salmonella Typhimurium or pneumonic infection with Burkholderia thailandensis, the presence of this E. coli did not alter changes in host metabolism, caloric uptake, or inflammation but instead sustained signaling of the insulin-like growth factor 1/phosphatidylinositol 3-kinase/AKT pathway in skeletal muscle, which is required for prevention of muscle wasting. This effect was dependent on engagement of the NLRC4 inflammasome. Therefore, this commensal promotes tolerance to diverse diseases.
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Affiliation(s)
- Alexandria M Palaferri Schieber
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Yujung Michelle Lee
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Max W Chang
- Integrative Genomics and Bioinformatics Core, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Mathias Leblanc
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Brett Collins
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Michael Downes
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Ronald M Evans
- Gene Expression Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA. Howard Hughes Medical Institute, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Janelle S Ayres
- Nomis Center for Immunobiology and Microbial Pathogenesis, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
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249
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Maltez VI, Tubbs AL, Cook KD, Aachoui Y, Falcone EL, Holland SM, Whitmire JK, Miao EA. Inflammasomes Coordinate Pyroptosis and Natural Killer Cell Cytotoxicity to Clear Infection by a Ubiquitous Environmental Bacterium. Immunity 2015; 43:987-97. [PMID: 26572063 DOI: 10.1016/j.immuni.2015.10.010] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 07/08/2015] [Accepted: 07/31/2015] [Indexed: 12/20/2022]
Abstract
Defective neutrophils in patients with chronic granulomatous disease (CGD) cause susceptibility to extracellular and intracellular infections. Microbes must first be ejected from intracellular niches to expose them to neutrophil attack, so we hypothesized that inflammasomes detect certain CGD pathogens upstream of neutrophil killing. Here, we identified one such ubiquitous environmental bacterium, Chromobacterium violaceum, whose extreme virulence was fully counteracted by the NLRC4 inflammasome. Caspase-1 protected via two parallel pathways that eliminated intracellular replication niches. Pyroptosis was the primary bacterial clearance mechanism in the spleen, but both pyroptosis and interleukin-18 (IL-18)-driven natural killer (NK) cell responses were required for liver defense. NK cells cleared hepatocyte replication niches via perforin-dependent cytotoxicity, whereas interferon-γ was not required. These insights suggested a therapeutic approach: exogenous IL-18 restored perforin-dependent cytotoxicity during infection by the inflammasome-evasive bacterium Listeria monocytogenes. Therefore, inflammasomes can trigger complementary programmed cell death mechanisms, directing sterilizing immunity against intracellular bacterial pathogens.
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Affiliation(s)
- Vivien I Maltez
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Alan L Tubbs
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Kevin D Cook
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Youssef Aachoui
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - E Liana Falcone
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA
| | - Steven M Holland
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA
| | - Jason K Whitmire
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Edward A Miao
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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250
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Fenyk S, Townsend PD, Dixon CH, Spies GB, de San Eustaquio Campillo A, Slootweg EJ, Westerhof LB, Gawehns FKK, Knight MR, Sharples GJ, Goverse A, Pålsson LO, Takken FLW, Cann MJ. The Potato Nucleotide-binding Leucine-rich Repeat (NLR) Immune Receptor Rx1 Is a Pathogen-dependent DNA-deforming Protein. J Biol Chem 2015; 290:24945-60. [PMID: 26306038 PMCID: PMC4599002 DOI: 10.1074/jbc.m115.672121] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Revised: 08/14/2015] [Indexed: 11/06/2022] Open
Abstract
Plant nucleotide-binding leucine-rich repeat (NLR) proteins enable cells to respond to pathogen attack. Several NLRs act in the nucleus; however, conserved nuclear targets that support their role in immunity are unknown. Previously, we noted a structural homology between the nucleotide-binding domain of NLRs and DNA replication origin-binding Cdc6/Orc1 proteins. Here we show that the NB-ARC (nucleotide-binding, Apaf-1, R-proteins, and CED-4) domain of the Rx1 NLR of potato binds nucleic acids. Rx1 induces ATP-dependent bending and melting of DNA in vitro, dependent upon a functional P-loop. In situ full-length Rx1 binds nuclear DNA following activation by its cognate pathogen-derived effector protein, the coat protein of potato virus X. In line with its obligatory nucleocytoplasmic distribution, DNA binding was only observed when Rx1 was allowed to freely translocate between both compartments and was activated in the cytoplasm. Immune activation induced by an unrelated NLR-effector pair did not trigger an Rx1-DNA interaction. DNA binding is therefore not merely a consequence of immune activation. These data establish a role for DNA distortion in Rx1 immune signaling and define DNA as a molecular target of an activated NLR.
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Affiliation(s)
- Stepan Fenyk
- From the School of Biological and Biomedical Sciences, Biophysical Sciences Institute
| | - Philip D Townsend
- From the School of Biological and Biomedical Sciences, Biophysical Sciences Institute
| | - Christopher H Dixon
- From the School of Biological and Biomedical Sciences, Biophysical Sciences Institute
| | - Gerhard B Spies
- From the School of Biological and Biomedical Sciences, Biophysical Sciences Institute
| | | | - Erik J Slootweg
- the Laboratory of Nematology, Department of Plant Sciences, Wageningen University, 6708 PB, Wageningen, The Netherlands, and
| | - Lotte B Westerhof
- the Laboratory of Nematology, Department of Plant Sciences, Wageningen University, 6708 PB, Wageningen, The Netherlands, and
| | - Fleur K K Gawehns
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Marc R Knight
- From the School of Biological and Biomedical Sciences, Biophysical Sciences Institute
| | - Gary J Sharples
- From the School of Biological and Biomedical Sciences, Biophysical Sciences Institute
| | - Aska Goverse
- the Laboratory of Nematology, Department of Plant Sciences, Wageningen University, 6708 PB, Wageningen, The Netherlands, and
| | - Lars-Olof Pålsson
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Frank L W Takken
- Molecular Plant Pathology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Martin J Cann
- From the School of Biological and Biomedical Sciences, Biophysical Sciences Institute,
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