101
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Caspase-8 promotes c-Rel-dependent inflammatory cytokine expression and resistance against Toxoplasma gondii. Proc Natl Acad Sci U S A 2019; 116:11926-11935. [PMID: 31147458 DOI: 10.1073/pnas.1820529116] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Caspase-8 is a key integrator of cell survival and cell death decisions during infection and inflammation. Following engagement of tumor necrosis factor superfamily receptors or certain Toll-like receptors (TLRs), caspase-8 initiates cell-extrinsic apoptosis while inhibiting RIPK3-dependent programmed necrosis. In addition, caspase-8 has an important, albeit less well understood, role in cell-intrinsic inflammatory gene expression. Macrophages lacking caspase-8 or the adaptor FADD have defective inflammatory cytokine expression and inflammasome priming in response to bacterial infection or TLR stimulation. How caspase-8 regulates cytokine gene expression, and whether caspase-8-mediated gene regulation has a physiological role during infection, remain poorly defined. Here we demonstrate that both caspase-8 enzymatic activity and scaffolding functions contribute to inflammatory cytokine gene expression. Caspase-8 enzymatic activity was necessary for maximal expression of Il1b and Il12b, but caspase-8 deficient cells exhibited a further decrease in expression of these genes. Furthermore, the ability of TLR stimuli to induce optimal IκB kinase phosphorylation and nuclear translocation of the nuclear factor kappa light chain enhancer of activated B cells family member c-Rel required caspase activity. Interestingly, overexpression of c-Rel was sufficient to restore expression of IL-12 and IL-1β in caspase-8-deficient cells. Moreover, Ripk3 -/- Casp8 -/- mice were unable to control infection by the intracellular parasite Toxoplasma gondii, which corresponded to defects in monocyte recruitment to the peritoneal cavity, and exogenous IL-12 restored monocyte recruitment and protection of caspase-8-deficient mice during acute toxoplasmosis. These findings provide insight into how caspase-8 controls inflammatory gene expression and identify a critical role for caspase-8 in host defense against eukaryotic pathogens.
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102
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Bolívar BE, Vogel TP, Bouchier-Hayes L. Inflammatory caspase regulation: maintaining balance between inflammation and cell death in health and disease. FEBS J 2019; 286:2628-2644. [PMID: 31090171 DOI: 10.1111/febs.14926] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/09/2019] [Accepted: 05/13/2019] [Indexed: 01/15/2023]
Abstract
Members of the mammalian inflammatory caspase family, including caspase-1, caspase-4, caspase-5, caspase-11, and caspase-12, are key regulators of the innate immune response. Most studies to date have focused on the role of caspase-1 in the maturation of the proinflammatory cytokine interleukin-1β and its upstream regulation by the inflammasome signaling complexes. However, an emerging body of research has supported a role for caspase-4, caspase-5, and caspase-11 in both regulating caspase-1 activation and inducing the inflammatory form of cell death called pyroptosis. This inflammatory caspase pathway appears essential for the regulation of cytokine processing. Consequently, insight into this noncanonical pathway may reveal important and, to date, understudied targets for the treatment of autoinflammatory disorders where the inflammasome pathway is dysregulated. Here, we will discuss the mechanisms of inflammasome and inflammatory caspase activation and how these pathways intersect to promote pathogen clearance.
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Affiliation(s)
- Beatriz E Bolívar
- Division of Hematology-Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.,William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX, USA
| | - Tiphanie P Vogel
- William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX, USA.,Division of Immunology, Allergy and Rheumatology, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Lisa Bouchier-Hayes
- Division of Hematology-Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.,William T. Shearer Center for Human Immunobiology, Texas Children's Hospital, Houston, TX, USA
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103
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Zhen Y, Zhang H. NLRP3 Inflammasome and Inflammatory Bowel Disease. Front Immunol 2019; 10:276. [PMID: 30873162 PMCID: PMC6403142 DOI: 10.3389/fimmu.2019.00276] [Citation(s) in RCA: 390] [Impact Index Per Article: 78.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 01/31/2019] [Indexed: 02/05/2023] Open
Abstract
NLRP3 inflammasome can be widely found in epithelial cells and immune cells. The NOD-like receptors (NLRs) family member NLRP3 contains a central nucleotide-binding and oligomerization (NACHT) domain which facilitates self-oligomerization and has ATPase activity. The C-terminal conserves a leucine-rich repeats (LRRs) domain which can modulate NLRP3 activity and sense endogenous alarmins and microbial ligands. In contrast, the N-terminal pyrin domain (PYD) can account for homotypic interactions with the adaptor protein-ASC of NLRP3 inflammasome. These characters enable it function in innate immunity. Its downstream effector proteins include caspase-1 and IL-1β etc. which exhibit protective or detrimental roles in mucosal immunity in different studies. Here, we comprehensively review the current literature regarding the physiology of NLRP3 inflammasome and its potential roles in the pathogenesis of IBD. We also discuss about the complex interactions among the NLRP3 inflammasome, mucosal immune response, and gut homeostasis as found in experimental models and IBD patients.
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Affiliation(s)
- Yu Zhen
- Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China.,The Centre of Inflammatory Bowel Disease, West China Hospital, Sichuan University, Chengdu, China
| | - Hu Zhang
- Department of Gastroenterology, West China Hospital, Sichuan University, Chengdu, China.,The Centre of Inflammatory Bowel Disease, West China Hospital, Sichuan University, Chengdu, China
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104
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Tonnus W, Meyer C, Paliege A, Belavgeni A, von Mässenhausen A, Bornstein SR, Hugo C, Becker JU, Linkermann A. The pathological features of regulated necrosis. J Pathol 2019; 247:697-707. [PMID: 30714148 DOI: 10.1002/path.5248] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/10/2019] [Accepted: 01/13/2019] [Indexed: 12/13/2022]
Abstract
Necrosis of a cell is defined by the loss of its plasma membrane integrity. Morphologically, necrosis occurs in several forms such as coagulative necrosis, colliquative necrosis, caseating necrosis, fibrinoid necrosis, and others. Biochemically, necrosis was demonstrated to represent a number of genetically determined signalling pathways. These include (i) kinase-mediated necroptosis, which depends on receptor interacting protein kinase 3 (RIPK3)-mediated phosphorylation of the pseudokinase mixed lineage kinase domain like (MLKL); (ii) gasdermin-mediated necrosis downstream of inflammasomes, also referred to as pyroptosis; and (iii) an iron-catalysed mechanism of highly specific lipid peroxidation named ferroptosis. Given the molecular understanding of the nature of these pathways, specific antibodies may allow direct detection of regulated necrosis and correlation with morphological features. Necroptosis can be specifically detected by immunohistochemistry and immunofluorescence employing antibodies to phosphorylated MLKL. Likewise, it is possible to generate cleavage-specific antibodies against epitopes in gasdermin protein family members. In ferroptosis, however, specific detection requires quantification of oxidative lipids by mass spectrometry (oxylipidomics). Together with classical cell death markers, such as TUNEL staining and detection of cleaved caspase-3 in apoptotic cells, the extension of the arsenal of necrosis markers will allow pathological detection of specific molecular pathways rather than isolated morphological descriptions. These novel pieces of information will be extraordinarily helpful for clinicians as inhibitors of necroptosis (necrostatins), ferroptosis (ferrostatins), and inflammasomes have emerged in clinical trials. Anatomical pathologists should embrace these novel ancillary tests and the concepts behind them and test their impact on diagnostic precision, prognostication, and the prediction of response to the upcoming anti-necrotic therapies. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Wulf Tonnus
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Claudia Meyer
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Alexander Paliege
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Alexia Belavgeni
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Anne von Mässenhausen
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Stefan R Bornstein
- Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Christian Hugo
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Jan Ulrich Becker
- Institute of Pathology, University Hospital Cologne, Cologne, Germany
| | - Andreas Linkermann
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
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105
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Application of immobilized ATP to the study of NLRP inflammasomes. Arch Biochem Biophys 2019; 670:104-115. [PMID: 30641048 DOI: 10.1016/j.abb.2018.12.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 12/01/2018] [Accepted: 12/17/2018] [Indexed: 01/15/2023]
Abstract
The NLRP proteins are a subfamily of the NOD-like receptor (NLR) innate immune sensors that possess an ATP-binding NACHT domain. As the most well studied member, NLRP3 can initiate the assembly process of a multiprotein complex, termed the inflammasome, upon detection of a wide range of microbial products and endogenous danger signals and results in the activation of pro-caspase-1, a cysteine protease that regulates multiple host defense pathways including cytokine maturation. Dysregulated NLRP3 activation contributes to inflammation and the pathogenesis of several chronic diseases, and the ATP-binding properties of NLRPs are thought to be critical for inflammasome activation. In light of this, we examined the utility of immobilized ATP matrices in the study of NLRP inflammasomes. Using NLRP3 as the prototypical member of the family, P-linked ATP Sepharose was determined to be a highly-effective capture agent. In subsequent examinations, P-linked ATP Sepharose was used as an enrichment tool to enable the effective profiling of NLRP3-biomarker signatures with selected reaction monitoring-mass spectrometry (SRM-MS). Finally, ATP Sepharose was used in combination with a fluorescence-linked enzyme chemoproteomic strategy (FLECS) screen to identify potential competitive inhibitors of NLRP3. The identification of a novel benzo[d]imidazol-2-one inhibitor that specifically targets the ATP-binding and hydrolysis properties of the NLRP3 protein implies that ATP Sepharose and FLECS could be applied other NLRPs as well.
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106
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Yabal M, Calleja DJ, Simpson DS, Lawlor KE. Stressing out the mitochondria: Mechanistic insights into NLRP3 inflammasome activation. J Leukoc Biol 2018; 105:377-399. [PMID: 30589456 DOI: 10.1002/jlb.mr0318-124r] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/23/2018] [Accepted: 10/24/2018] [Indexed: 12/13/2022] Open
Abstract
Inflammasomes are multimeric protein complexes that induce the cleavage and release of bioactive IL-1β and cause a lytic form of cell death, termed pyroptosis. Due to its diverse triggers, ranging from infectious pathogens and host danger molecules to environmental irritants, the NOD-like receptor protein 3 (NLRP3) inflammasome remains the most widely studied inflammasome to date. Despite intense scrutiny, a universal mechanism for its activation remains elusive, although, recent research has focused on mitochondrial dysfunction or potassium (K+ ) efflux as key events. In this review, we give a general overview of NLRP3 inflammasome activation and explore the recently emerging noncanonical and alternative pathways to NLRP3 activation. We highlight the role of the NLRP3 inflammasome in the pathogenesis of metabolic disease that is associated with mitochondrial and oxidative stress. Finally, we interrogate the mechanisms proposed to trigger NLRP3 inflammasome assembly and activation. A greater understanding of how NLRP3 inflammasome activation is triggered may reveal new therapeutic targets for the treatment of inflammatory disease.
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Affiliation(s)
- Monica Yabal
- III. Medical Department for Hematology and Oncology, Kinikum rechts der Isar, Technische Universität München, Munich, Germany
| | - Dale J Calleja
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia
| | - Daniel S Simpson
- The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia.,Department of Medical Biology, University of Melbourne, Parkville, Victoria, Australia
| | - Kate E Lawlor
- Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Molecular and Translational Science, Monash University, Clayton, Victoria, Australia
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107
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Cytosolic Recognition of Microbes and Pathogens: Inflammasomes in Action. Microbiol Mol Biol Rev 2018; 82:82/4/e00015-18. [PMID: 30209070 DOI: 10.1128/mmbr.00015-18] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Infection is a dynamic biological process underpinned by a complex interplay between the pathogen and the host. Microbes from all domains of life, including bacteria, viruses, fungi, and protozoan parasites, have the capacity to cause infection. Infection is sensed by the host, which often leads to activation of the inflammasome, a cytosolic macromolecular signaling platform that mediates the release of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18 and cleavage of the pore-forming protein gasdermin D, leading to pyroptosis. Host-mediated sensing of the infection occurs when pathogens inject or carry pathogen-associated molecular patterns (PAMPs) into the cytoplasm or induce damage that causes cytosolic liberation of danger-associated molecular patterns (DAMPs) in the host cell. Recognition of PAMPs and DAMPs by inflammasome sensors, including NLRP1, NLRP3, NLRC4, NAIP, AIM2, and Pyrin, initiates a cascade of events that culminate in inflammation and cell death. However, pathogens can deploy virulence factors capable of minimizing or evading host detection. This review presents a comprehensive overview of the mechanisms of microbe-induced activation of the inflammasome and the functional consequences of inflammasome activation in infectious diseases. We also explore the microbial strategies used in the evasion of inflammasome sensing at the host-microbe interaction interface.
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108
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Van Opdenbosch N, Van Gorp H, Verdonckt M, Saavedra PHV, de Vasconcelos NM, Gonçalves A, Vande Walle L, Demon D, Matusiak M, Van Hauwermeiren F, D'Hont J, Hochepied T, Krautwald S, Kanneganti TD, Lamkanfi M. Caspase-1 Engagement and TLR-Induced c-FLIP Expression Suppress ASC/Caspase-8-Dependent Apoptosis by Inflammasome Sensors NLRP1b and NLRC4. Cell Rep 2018; 21:3427-3444. [PMID: 29262324 PMCID: PMC5746600 DOI: 10.1016/j.celrep.2017.11.088] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/15/2017] [Accepted: 11/27/2017] [Indexed: 02/02/2023] Open
Abstract
The caspase activation and recruitment domain (CARD)-based inflammasome sensors NLRP1b and NLRC4 induce caspase-1-dependent pyroptosis independent of the inflammasome adaptor ASC. Here, we show that NLRP1b and NLRC4 trigger caspase-8-mediated apoptosis as an alternative cell death program in caspase-1-/- macrophages and intestinal epithelial organoids (IECs). The caspase-8 adaptor FADD was recruited to ASC specks, which served as cytosolic platforms for caspase-8 activation and NLRP1b/NLRC4-induced apoptosis. We further found that caspase-1 protease activity dominated over scaffolding functions in suppressing caspase-8 activation and induction of apoptosis of macrophages and IECs. Moreover, TLR-induced c-FLIP expression inhibited caspase-8-mediated apoptosis downstream of ASC speck assembly, but did not affect pyroptosis induction by NLRP1b and NLRC4. Moreover, unlike during pyroptosis, NLRP1b- and NLRC4-elicited apoptosis retained alarmins and the inflammasome-matured cytokines interleukin 1β (IL-1β) and IL-18 intracellularly. This work identifies critical mechanisms regulating apoptosis induction by the inflammasome sensors NLRP1b and NLRC4 and suggests converting pyroptosis into apoptosis as a paradigm for suppressing inflammation.
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Affiliation(s)
- Nina Van Opdenbosch
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Hanne Van Gorp
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Maarten Verdonckt
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Pedro H V Saavedra
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Nathalia M de Vasconcelos
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Amanda Gonçalves
- VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium; VIB Bioimaging Core, VIB, 9000 Ghent, Belgium
| | - Lieselotte Vande Walle
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Dieter Demon
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Magdalena Matusiak
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Filip Van Hauwermeiren
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Jinke D'Hont
- VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9000 Ghent, Belgium
| | - Tino Hochepied
- VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9000 Ghent, Belgium
| | - Stefan Krautwald
- Department of Nephrology and Hypertension, University Hospital Schleswig-Holstein, 24105 Kiel, Germany
| | | | - Mohamed Lamkanfi
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium.
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109
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Dhuriya YK, Sharma D. Necroptosis: a regulated inflammatory mode of cell death. J Neuroinflammation 2018; 15:199. [PMID: 29980212 PMCID: PMC6035417 DOI: 10.1186/s12974-018-1235-0] [Citation(s) in RCA: 384] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Accepted: 06/22/2018] [Indexed: 12/18/2022] Open
Abstract
Programmed cell death has a vital role in embryonic development and tissue homeostasis. Necroptosis is an alternative mode of regulated cell death mimicking features of apoptosis and necrosis. Necroptosis requires protein RIPK3 (previously well recognized as regulator of inflammation, cell survival, and disease) and its substrate MLKL, the crucial players of this pathway. Necroptosis is induced by toll-like receptor, death receptor, interferon, and some other mediators. Shreds of evidence based on a mouse model reveals that deregulation of necroptosis has been found to be associated with pathological conditions like cancer, neurodegenerative diseases, and inflammatory diseases. In this timeline article, we are discussing the molecular mechanisms of necroptosis and its relevance to diseases.
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Affiliation(s)
- Yogesh K Dhuriya
- Developmental Toxicology Laboratory, Systems Toxicology and Health Risk Assessment Group, CSIR-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhawan; 31, Mahatma Gandhi Marg, Lucknow, 226001, India
- Academy of Scientific and Innovative Research (AcSIR) Lucknow Campus, Lucknow, India
| | - Divakar Sharma
- Department of Biochemistry, National JALMA Institute for Leprosy and Other Mycobacterial Diseases, Tajganj, Agra, India.
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, 202002, India.
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110
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Hefele M, Stolzer I, Ruder B, He GW, Mahapatro M, Wirtz S, Neurath MF, Günther C. Intestinal epithelial Caspase-8 signaling is essential to prevent necroptosis during Salmonella Typhimurium induced enteritis. Mucosal Immunol 2018; 11:1191-1202. [PMID: 29520026 DOI: 10.1038/s41385-018-0011-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 01/03/2018] [Accepted: 01/14/2018] [Indexed: 02/04/2023]
Abstract
Although induction of host cell death is a pivotal step during bacteria-induced gastroenteritis, the molecular regulation remains to be fully characterized. To expand our knowledge, we investigated the role of the central cell death regulator Caspase-8 in response to Salmonella Typhimurium. Here, we uncovered that intestinal salmonellosis was associated with strong upregulation of members of the host cell death machinery in intestinal epithelial cells (IECs) as an early event, suggesting that elimination of infected IECs represents a host defense strategy. Indeed, Casp8∆IEC mice displayed severe tissue damage and high lethality after infection. Additional deletion of Ripk3 or Mlkl rescued epithelial cell death and lethality of Casp8∆IEC mice, demonstrating the crucial role of Caspase-8 as a negative regulator of necroptosis. While Casp8∆IECTnfr1-/- mice showed improved survival after infection, tissue destruction was similar to Casp8∆IEC mice, indicating that necroptosis partially depends on TNF-α signaling. Although there was no impairment in antimicrobial peptide secretion during the early phase of infection, functional Caspase-8 seems to be required to control pathogen colonization. Collectively, these results demonstrate that Caspase-8 is essential to prevent Salmonella Typhimurium induced enteritis and to ensure host survival by two different mechanisms: maintenance of intestinal barrier function and restriction of pathogen colonization.
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Affiliation(s)
- Manuela Hefele
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Iris Stolzer
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Barbara Ruder
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Gui-Wei He
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Mousumi Mahapatro
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Stefan Wirtz
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Markus F Neurath
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Claudia Günther
- Department of Medicine 1, University of Erlangen-Nuremberg, Erlangen, Germany.
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111
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Balakrishnan A, Karki R, Berwin B, Yamamoto M, Kanneganti TD. Guanylate binding proteins facilitate caspase-11-dependent pyroptosis in response to type 3 secretion system-negative Pseudomonas aeruginosa. Cell Death Discov 2018; 4:3. [PMID: 30062052 PMCID: PMC6060091 DOI: 10.1038/s41420-018-0068-z] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/03/2018] [Indexed: 01/10/2023] Open
Abstract
Detection of bacterial ligands is a pre-requisite for inflammasome activation. During Pseudomonas aeruginosa infection, flagellin which is secreted through the T3SS is detected by the NLRC4 inflammasome. Activation of the NLRC4 inflammasome is believed to contribute to high IL-1β production and pathogenicity in cystic fibrosis patients with chronic P. aeruginosa infection. Interestingly, the majority of P. aeruginosa isolated from cystic fibrosis patients with chronic airway infection are non-motile and T3SS-negative, suggesting that yet un-characterized inflammasome pathways regulate IL-1β production in cystic fibrosis patients. Here we demonstrate the role of guanylate-binding proteins (GBPs) in regulating bacterial proliferation and inflammasome activation in response to T3SS-negative P. aeruginosa. Bacterial ligands liberated by the action of GBP2 and IRGB10 activate caspase-11 and regulate non-canonical NLRP3 inflammasome activation and IL-1β release. Overall, our results reveal the role of caspase-11 in inhibiting bacterial proliferation and promoting IL-1β secretion during T3SS-negative P. aeruginosa infection. This study suggests that non canonical inflammasomes might have co-evolved to detect Gram-negative bacterial pathogens that have evolved to bypass detection by canonical NLRs.
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Affiliation(s)
- Arjun Balakrishnan
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105 USA
| | - Rajendra Karki
- Department of Immunology, St. Jude Children’s Research Hospital, Memphis, TN 38105 USA
| | - Brent Berwin
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756 USA
| | - Masahiro Yamamoto
- Department of Immunoparasitology, Research Institute for Microbial Diseases, Laboratory of Immunoparasitology, World Premier International Immunology Frontier Research Center, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871 Japan
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112
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Moghaddas F, Zeng P, Zhang Y, Schützle H, Brenner S, Hofmann SR, Berner R, Zhao Y, Lu B, Chen X, Zhang L, Cheng S, Winkler S, Lehmberg K, Canna SW, Czabotar PE, Wicks IP, De Nardo D, Hedrich CM, Zeng H, Masters SL. Autoinflammatory mutation in NLRC4 reveals a leucine-rich repeat (LRR)-LRR oligomerization interface. J Allergy Clin Immunol 2018; 142:1956-1967.e6. [PMID: 29778503 PMCID: PMC6281029 DOI: 10.1016/j.jaci.2018.04.033] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/22/2018] [Accepted: 04/27/2018] [Indexed: 12/28/2022]
Abstract
Background Monogenic autoinflammatory disorders are characterized by dysregulation of the innate immune system, for example by gain-of-function mutations in inflammasome-forming proteins, such as NOD-like receptor family CARD-containing 4 protein (NLRC4). Objective Here we investigate the mechanism by which a novel mutation in the leucine-rich repeat (LRR) domain of NLRC4 (c.G1965C, p.W655C) contributes to autoinflammatory disease. Methods: We studied 2 unrelated patients with early-onset macrophage activation syndrome harboring the same de novo mutation in NLRC4. In vitro inflammasome complex formation was quantified by using flow cytometric analysis of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) specks. Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 techniques and lentiviral transduction were used to generate THP-1 cells with either wild-type or mutant NLRC4 cDNA. Cell death and release of IL-1β/IL-18 were quantified by using flow cytometry and ELISA, respectively. Results The p.W655C NLRC4 mutation caused increased ASC speck formation, caspase-1–dependent cell death, and IL-1β/IL-18 production. ASC contributed to p.W655C NLRC4–mediated cytokine release but not cell death. Mutation of p.W655 activated the NLRC4 inflammasome complex by engaging with 2 interfaces on the opposing LRR domain of the oligomer. One key set of residues (p.D1010, p.D1011, p.L1012, and p.I1015) participated in LRR-LRR oligomerization when triggered by mutant NLRC4 or type 3 secretion system effector (PrgI) stimulation of the NLRC4 inflammasome complex. Conclusion This is the first report of a mutation in the LRR domain of NLRC4 causing autoinflammatory disease. c.G1965C/p.W655C NLRC4 increased inflammasome activation in vitro. Data generated from various NLRC4 mutations provides evidence that the LRR-LRR interface has an important and previously unrecognized role in oligomerization of the NLRC4 inflammasome complex.
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Affiliation(s)
- Fiona Moghaddas
- Inflammation Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Ping Zeng
- Department of Rheumatology, Guangzhou Women and Children's Medical Centre, Guangzhou, China
| | - Yuxia Zhang
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou, China
| | - Heike Schützle
- Department of Pediatrics, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Sebastian Brenner
- Department of Pediatrics, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Sigrun R Hofmann
- Department of Pediatrics, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Reinhard Berner
- Department of Pediatrics, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Yuanbo Zhao
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou, China; Department of Chemical Biology, Guizhou Medical University, Guiyang, China
| | - Bingtai Lu
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou, China
| | - Xiaoyun Chen
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou, China
| | - Li Zhang
- Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou, China
| | - Suyun Cheng
- Department of Rheumatology, Guangzhou Women and Children's Medical Centre, Guangzhou, China
| | - Stefan Winkler
- Department of Pediatrics, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Kai Lehmberg
- Division of Pediatric Stem Cell Transplantation and Immunology, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Scott W Canna
- Pediatric Rheumatology/RK Mellon Institute, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, Pa
| | - Peter E Czabotar
- Department of Medical Biology, University of Melbourne, Parkville, Australia; Structural Biology Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Ian P Wicks
- Inflammation Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia; Rheumatology Department, Royal Melbourne Hospital, Parkville, Australia
| | - Dominic De Nardo
- Inflammation Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia
| | - Christian M Hedrich
- Department of Pediatrics, University Hospital and Faculty of Medicine Carl Gustav Carus, TU Dresden, Dresden, Germany; Department of Women's & Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom; Department of Paediatric Rheumatology, Alder Hey Children's NHS Foundation Trust Hospital, Liverpool, United Kingdom
| | - Huasong Zeng
- Department of Rheumatology, Guangzhou Women and Children's Medical Centre, Guangzhou, China
| | - Seth L Masters
- Inflammation Division, Walter and Eliza Hall Institute of Medical Research, Parkville, Australia; Department of Medical Biology, University of Melbourne, Parkville, Australia; Immunology Laboratory, Guangzhou Institute of Paediatrics, Guangzhou, China.
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Kesavardhana S, Kanneganti TD. Mechanisms governing inflammasome activation, assembly and pyroptosis induction. Int Immunol 2018; 29:201-210. [PMID: 28531279 DOI: 10.1093/intimm/dxx018] [Citation(s) in RCA: 159] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 05/15/2017] [Indexed: 12/11/2022] Open
Abstract
Inflammasomes are multimeric protein complexes that regulate inflammatory responses and pyroptotic cell death to exert host defense against microbes. Intracellular pattern-recognition receptors such as nucleotide-binding domain and leucine-rich repeat receptors (NLRs) and absent in melanoma 2 like receptors (ALRs) assemble the inflammasome complexes in response to pathogens and danger or altered-self signals in the cell. Inflammasome sensors, in association with an adaptor protein-apoptosis-associated speck-like protein containing a caspase-activation and -recruitment domain (ASC)-activate inflammatory caspase-1 to enable the release of inflammatory cytokines and induce cell death, conferring host defense against pathogens. Beyond infectious diseases, the importance of inflammasomes is implicated in a variety of clinical conditions such as auto-inflammatory diseases, neuro-degeneration and metabolic disorders and the development of cancers. Understanding inflammasome activation and its molecular regulation can unveil therapeutic targets for controlling inflammasome-mediated disorders. In this review, we describe recent advances in inflammasome biology and discuss its activation, structural insights into inflammasome assembly and mechanisms for the execution of pyroptosis.
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Affiliation(s)
- Sannula Kesavardhana
- Department of Immunology, St. Jude Children's Research Hospital, MS #351, 262 Danny Thomas Place, Memphis, TN 38105-3678, USA
| | - Thirumala-Devi Kanneganti
- Department of Immunology, St. Jude Children's Research Hospital, MS #351, 262 Danny Thomas Place, Memphis, TN 38105-3678, USA
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114
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Tamai R, Kiyoura Y. Alendronate augments lipid A-induced IL-1β release and Smad3/NLRP3/ASC-dependent cell death. Life Sci 2018; 198:8-17. [DOI: 10.1016/j.lfs.2018.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 02/01/2018] [Accepted: 02/09/2018] [Indexed: 12/13/2022]
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115
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Lee BL, Mirrashidi KM, Stowe IB, Kummerfeld SK, Watanabe C, Haley B, Cuellar TL, Reichelt M, Kayagaki N. ASC- and caspase-8-dependent apoptotic pathway diverges from the NLRC4 inflammasome in macrophages. Sci Rep 2018; 8:3788. [PMID: 29491424 PMCID: PMC5830643 DOI: 10.1038/s41598-018-21998-3] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 02/14/2018] [Indexed: 11/09/2022] Open
Abstract
The NLRC4 inflammasome recognizes bacterial flagellin and components of the type III secretion apparatus. NLRC4 stimulation leads to caspase-1 activation followed by a rapid lytic cell death known as pyroptosis. NLRC4 is linked to pathogen-free auto-inflammatory diseases, suggesting a role for NLRC4 in sterile inflammation. Here, we show that NLRC4 activates an alternative cell death program morphologically similar to apoptosis in caspase-1-deficient BMDMs. By performing an unbiased genome-wide CRISPR/Cas9 screen with subsequent validation studies in gene-targeted mice, we highlight a critical role for caspase-8 and ASC adaptor in an alternative apoptotic pathway downstream of NLRC4. Furthermore, caspase-1 catalytically dead knock-in (Casp1 C284A KI) BMDMs genetically segregate pyroptosis and apoptosis, and confirm that caspase-1 does not functionally compete with ASC for NLRC4 interactions. We show that NLRC4/caspase-8-mediated apoptotic cells eventually undergo plasma cell membrane damage in vitro, suggesting that this pathway can lead to secondary necrosis. Unexpectedly, we found that DFNA5/GSDME, a member of the pore-forming gasdermin family, is dispensable for the secondary necrosis that follows NLRC4-mediated apoptosis in macrophages. Together, our data confirm the existence of an alternative caspase-8 activation pathway diverging from the NLRC4 inflammasome in primary macrophages.
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Affiliation(s)
- Bettina L Lee
- Department of Physiological Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Kathleen M Mirrashidi
- Department of Physiological Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Irma B Stowe
- Department of Physiological Chemistry, Genentech Inc., South San Francisco, California, USA
| | - Sarah K Kummerfeld
- Department of Bioinformatics, Genentech Inc., South San Francisco, California, USA
| | - Colin Watanabe
- Department of Bioinformatics, Genentech Inc., South San Francisco, California, USA
| | - Benjamin Haley
- Department of Molecular Biology, Genentech Inc., South San Francisco, California, USA
| | - Trinna L Cuellar
- Department of Molecular Biology, Genentech Inc., South San Francisco, California, USA
| | - Michael Reichelt
- Department of Pathology, Genentech Inc., South San Francisco, California, USA
| | - Nobuhiko Kayagaki
- Department of Physiological Chemistry, Genentech Inc., South San Francisco, California, USA.
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Abstract
Roles for cell death in development, homeostasis, and the control of infections and cancer have long been recognized. Although excessive cell damage results in passive necrosis, cells can be triggered to engage molecular programs that result in cell death. Such triggers include cellular stress, oncogenic signals that engage tumor suppressor mechanisms, pathogen insults, and immune mechanisms. The best-known forms of programmed cell death are apoptosis and a recently recognized regulated necrosis termed necroptosis. Of the two best understood pathways of apoptosis, the extrinsic and intrinsic (mitochondrial) pathways, the former is induced by the ligation of death receptors, a subset of the TNF receptor (TNFR) superfamily. Ligation of these death receptors can also induce necroptosis. The extrinsic apoptosis and necroptosis pathways regulate each other and their balance determines whether cells live. Integral in the regulation and initiation of death receptor-mediated activation of programmed cell death is the aspartate-specific cysteine protease (caspase)-8. This review describes the role of caspase-8 in the initiation of extrinsic apoptosis execution and the mechanism by which caspase-8 inhibits necroptosis. The importance of caspase-8 in the development and homeostasis and the way that dysfunctional caspase-8 may contribute to the development of malignancies in mice and humans are also explored.
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Affiliation(s)
- Bart Tummers
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Douglas R Green
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
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Songane M, Khair M, Saleh M. An updated view on the functions of caspases in inflammation and immunity. Semin Cell Dev Biol 2018; 82:137-149. [PMID: 29366812 DOI: 10.1016/j.semcdb.2018.01.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 12/21/2017] [Accepted: 01/02/2018] [Indexed: 12/14/2022]
Abstract
The binary classification of mammalian caspases as either apoptotic or inflammatory is now obsolete. Emerging data indicate that all mammalian caspases are intricately involved in the regulation of inflammation and immunity. They participate in embryonic and adult tissue homeostasis, control leukocyte differentiation, activation and effector functions, and mediate innate and adaptive immunity signaling. Caspases also promote host resistance by regulating anti-oxidant defense and pathogen clearance through regulation of phagosomal maturation, actin dynamics and phagosome-lysosome fusion. Beyond apoptosis, they regulate inflammatory cell death, eliciting rapid pyroptosis of infected cells, while inhibiting necroptosis-mediated tissue destruction and chronic inflammation. In this review, we describe the cellular and molecular mechanisms underlying non-apoptotic functions of caspases in inflammation and immunity and provide an updated view of their functions as central regulators of tissue homeostasis and host defense.
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Affiliation(s)
- Mario Songane
- Department of Medicine, McGill University, Montréal, Québec H3G 0B1, Canada
| | - Mostafa Khair
- Department of Medicine, McGill University, Montréal, Québec H3G 0B1, Canada
| | - Maya Saleh
- Department of Medicine, McGill University, Montréal, Québec H3G 0B1, Canada.
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118
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Ketelut-Carneiro N, Ghosh S, Levitz SM, Fitzgerald KA, da Silva JS. A Dectin-1-Caspase-8 Pathway Licenses Canonical Caspase-1 Inflammasome Activation and Interleukin-1β Release in Response to a Pathogenic Fungus. J Infect Dis 2018; 217:329-339. [PMID: 29099934 PMCID: PMC6279136 DOI: 10.1093/infdis/jix568] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 10/26/2017] [Indexed: 11/14/2022] Open
Abstract
Background Paracoccidioides brasiliensis is equipped with an arsenal of virulence factors that are crucial for causing infection. Our group previously defined the NLRP3 inflammasome as a mediator of P brasiliensis-induced cell damage recognition and induction of effective Th1 immune responses. However, deficiency of caspase-1 only partially reduced interleukin (IL)-1β levels. Methods In this study, using chemical inhibitors as well as genetically modified mice, we identify an additional pathway for IL-1β production in response to P brasiliensis infection. Results Paracoccidioides brasiliensis initiated caspase-8-mediated IL-1β production, an event that was necessary for transcriptional priming and posttranslational processing of pro-IL-1β. Caspase-8 synergizes with the canonical NLRP3 inflammasome pathway to control caspase-1 processing and IL-1β maturation, providing a regulatory role for caspase-8 in host resistance to in vivo P brasiliensis infection. Conclusions Taken together, these findings revealed an important role for caspase-8 in the innate immune response of host cells to P brasiliensis infection, demonstrating a connected network between noncanonical and canonical inflammasomes to coordinate IL-1β production during fungal challenge.
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Affiliation(s)
- Natália Ketelut-Carneiro
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Brazil
| | - Sreya Ghosh
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester
| | - Stuart M Levitz
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester
| | - Katherine A Fitzgerald
- Program in Innate Immunity, Department of Medicine, University of Massachusetts Medical School, Worcester
| | - João Santana da Silva
- Department of Biochemistry and Immunology, Ribeirão Preto Medical School, University of São Paulo, Brazil
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119
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Abstract
Inflammasome signalling is an emerging pillar of innate immunity and has a central role in the regulation of gastrointestinal health and disease. Activation of the inflammasome complex mediates both the release of the pro-inflammatory cytokines IL-1β and IL-18 and the execution of a form of inflammatory cell death known as pyroptosis. In most cases, these mediators of inflammation provide protection against bacterial, viral and protozoal infections. However, unchecked inflammasome activities perpetuate chronic inflammation, which underpins the molecular and pathophysiological basis of gastritis, IBD, upper and lower gastrointestinal cancer, nonalcoholic fatty liver disease and obesity. Studies have also highlighted an inflammasome signature in the maintenance of gut microbiota and gut-brain homeostasis. Harnessing the immunomodulatory properties of the inflammasome could transform clinical practice in the treatment of acute and chronic gastrointestinal and extragastrointestinal diseases. This Review presents an overview of inflammasome biology in gastrointestinal health and disease and describes the value of experimental and pharmacological intervention in the treatment of inflammasome-associated clinical manifestations.
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120
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Abstract
15 years ago, the fundamental biology of an inflammatory signaling complex eventually dubbed "the inflammasome" began to unravel in chronologic parallel with the discovery that many inflammatory diseases were associated with its hyperactivity. Though the genetic origins of Familial Mediterranean Fever (FMF, caused my mutations in MEFV) were discovered first, it would take nearly two decades before the mechanistic connections to a PYRIN inflammasome were made. In the interim, the intensive study of the NLRP3 inflammasome, and the diseases associated with its hyperactivation, have largely dictated the paradigm of inflammasome composition and function. Despite impressive gains, focusing on NLRP3 left gaps in our understanding of inflammasome biology. Foremost among these gaps were how inflammasomes become activated and the connections between inflammasome structure and function. Fortunately, work in another inflammasome inducer, NLRC4, grew to fill those gaps. The current understanding of the NLRC4 inflammasome is perhaps the most comprehensive illustration of the inflammasome paradigm: trigger (e.g. cytosolic flagellin), sensor (NAIP), nucleator (NLRC4), adaptor (ASC), and effector (CASP1). Detailed work has also identified observations that challenge this paradigm. Simultaneously, the features unique to each inflammasome offer a lesson in contrast, providing perspectives on inflammasome activation, regulation, and function. In this review, we endeavor to highlight recent breakthroughs related to NLRC4 inflammasome structure and activation, important in vivo work in infection and systemic inflammation, and the characterization of a spectrum of human NLRC4-associated autoinflammatory diseases.
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Affiliation(s)
- Joseph A. Duncan
- Department of Medicine, Division of Infectious diseases, University of North Carolina at Chapel Hill, NC
| | - Scott W. Canna
- Pediatric Rheumatology & RK Mellon Institute for Pediatric Research, Children’s Hospital of Pittsburgh of UPMC, Pittsburgh, PA
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121
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Sagulenko V, Vitak N, Vajjhala PR, Vince JE, Stacey KJ. Caspase-1 Is an Apical Caspase Leading to Caspase-3 Cleavage in the AIM2 Inflammasome Response, Independent of Caspase-8. J Mol Biol 2017; 430:238-247. [PMID: 29100888 DOI: 10.1016/j.jmb.2017.10.028] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 10/06/2017] [Accepted: 10/23/2017] [Indexed: 12/13/2022]
Abstract
Canonical inflammasomes are multiprotein complexes that can activate both caspase-1 and caspase-8. Caspase-1 drives rapid lysis of cells by pyroptosis and maturation of interleukin (IL)-1β and IL-18. In caspase-1-deficient cells, inflammasome formation still leads to caspase-3 activation and slower apoptotic death, dependent on caspase-8 as an apical caspase. A role for caspase-8 directly upstream of caspase-1 has also been suggested, but here we show that caspase-8-deficient macrophages have no defect in AIM2 inflammasome-mediated caspase-1 activation, pyroptosis, and IL-1β cleavage. In investigating the inflammasome-induced apoptotic pathway, we previously demonstrated that activated caspase-8 is essential for caspase-3 cleavage and apoptosis in caspase-1-deficient cells. However, here we found that AIM2 inflammasome-initiated caspase-3 cleavage was maintained in Ripk3-/-Casp8-/- macrophages. Gene knockdown showed that caspase-1 was required for the caspase-3 cleavage. Thus inflammasomes activate a network of caspases that can promote both pyroptotic and apoptotic cell death. In cells where rapid pyroptosis is blocked, delayed inflammasome-dependent cell death could still occur due to both caspase-1- and caspase-8-dependent apoptosis. Initiation of redundant cell death pathways is likely to be a strategy for coping with pathogen interference in death processes.
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Affiliation(s)
- Vitaliya Sagulenko
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Nazarii Vitak
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia
| | - Parimala R Vajjhala
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia
| | - James E Vince
- Walter and Eliza Hall Institute for Medical Research, Parkville, Vic 3052, Australia
| | - Katryn J Stacey
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia.
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122
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Abstract
Within the gut, Salmonella-infected enterocytes are expelled into the lumen, limiting pathogen replication. In this issue of Immunity, Rauch et al. (2017) expand our understanding of this cell-intrinsic response by characterizing the genetic determinants that control the expulsion and death of epithelial cells.
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123
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Anderson CJ, Kendall MM. Salmonella enterica Serovar Typhimurium Strategies for Host Adaptation. Front Microbiol 2017; 8:1983. [PMID: 29075247 PMCID: PMC5643478 DOI: 10.3389/fmicb.2017.01983] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 09/26/2017] [Indexed: 12/21/2022] Open
Abstract
Bacterial pathogens must sense and respond to newly encountered host environments to regulate the expression of critical virulence factors that allow for niche adaptation and successful colonization. Among bacterial pathogens, non-typhoidal serovars of Salmonella enterica, such as serovar Typhimurium (S. Tm), are a primary cause of foodborne illnesses that lead to hospitalizations and deaths worldwide. S. Tm causes acute inflammatory diarrhea that can progress to invasive systemic disease in susceptible patients. The gastrointestinal tract and intramacrophage environments are two critically important niches during S. Tm infection, and each presents unique challenges to limit S. Tm growth. The intestinal tract is home to billions of commensal microbes, termed the microbiota, which limits the amount of available nutrients for invading pathogens such as S. Tm. Therefore, S. Tm encodes strategies to manipulate the commensal population and side-step this nutritional competition. During subsequent stages of disease, S. Tm resists host immune cell mechanisms of killing. Host cells use antimicrobial peptides, acidification of vacuoles, and nutrient limitation to kill phagocytosed microbes, and yet S. Tm is able to subvert these defense systems. In this review, we discuss recently described molecular mechanisms that S. Tm uses to outcompete the resident microbiota within the gastrointestinal tract. S. Tm directly eliminates close competitors via bacterial cell-to-cell contact as well as by stimulating a host immune response to eliminate specific members of the microbiota. Additionally, S. Tm tightly regulates the expression of key virulence factors that enable S. Tm to withstand host immune defenses within macrophages. Additionally, we highlight the chemical and physical signals that S. Tm senses as cues to adapt to each of these environments. These strategies ultimately allow S. Tm to successfully adapt to these two disparate host environments. It is critical to better understand bacterial adaptation strategies because disruption of these pathways and mechanisms, especially those shared by multiple pathogens, may provide novel therapeutic intervention strategies.
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Affiliation(s)
- Christopher J Anderson
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine,, Charlottesville, VA, United States
| | - Melissa M Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine,, Charlottesville, VA, United States
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Mascarenhas DPA, Cerqueira DM, Pereira MSF, Castanheira FVS, Fernandes TD, Manin GZ, Cunha LD, Zamboni DS. Inhibition of caspase-1 or gasdermin-D enable caspase-8 activation in the Naip5/NLRC4/ASC inflammasome. PLoS Pathog 2017; 13:e1006502. [PMID: 28771586 PMCID: PMC5542441 DOI: 10.1371/journal.ppat.1006502] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/30/2017] [Indexed: 11/19/2022] Open
Abstract
Legionella pneumophila is a Gram-negative, flagellated bacterium that survives in phagocytes and causes Legionnaires’ disease. Upon infection of mammalian macrophages, cytosolic flagellin triggers the activation of Naip/NLRC4 inflammasome, which culminates in pyroptosis and restriction of bacterial replication. Although NLRC4 and caspase-1 participate in the same inflammasome, Nlrc4-/- mice and their macrophages are more permissive to L. pneumophila replication compared with Casp1/11-/-. This feature supports the existence of a pathway that is NLRC4-dependent and caspase-1/11-independent. Here, we demonstrate that caspase-8 is recruited to the Naip5/NLRC4/ASC inflammasome in response to flagellin-positive bacteria. Accordingly, caspase-8 is activated in Casp1/11-/- macrophages in a process dependent on flagellin, Naip5, NLRC4 and ASC. Silencing caspase-8 in Casp1/11-/- cells culminated in macrophages that were as susceptible as Nlrc4-/- for the restriction of L. pneumophila replication. Accordingly, macrophages and mice deficient in Asc/Casp1/11-/- were more susceptible than Casp1/11-/- and as susceptible as Nlrc4-/- for the restriction of infection. Mechanistically, we found that caspase-8 activation triggers gasdermin-D-independent pore formation and cell death. Interestingly, caspase-8 is recruited to the Naip5/NLRC4/ASC inflammasome in wild-type macrophages, but it is only activated when caspase-1 or gasdermin-D is inhibited. Our data suggest that caspase-8 activation in the Naip5/NLRC4/ASC inflammasome enable induction of cell death when caspase-1 or gasdermin-D is suppressed. Legionella pneumophila is the causative agent of Legionnaires’ disease, an atypical pneumophila that affects people worldwide. Besides the clinical importance, L. pneumophila is a very useful model of pathogenic bacteria for investigation of the interactions of innate immune cells with bacterial pathogens. Studies using L. pneumophila demonstrated that Naip5 and NLRC4 activate caspase-1 and this inflammasome is activated by bacterial flagellin. However, macrophages and mice deficient in NLRC4 are more susceptible for L. pneumophila replication than those deficient in caspase-1, indicating that the flagellin/Naip5/NLRC4 inflammasome triggers responses that are independent on caspase-1. Here, we used L. pneumophila to investigate this novel pathway and found that caspase-8 interacts with NLRC4 in a process that is dependent on ASC and independent of caspase-1 and caspase-11. Although caspase-8 is recruited to the Naip5/NLRC4/ASC inflammasome, it is only activated when caspase-1 or gasdermin-D is inhibited. Our data suggest that caspase-8 activation in the Naip5/NLRC4/ASC inflammasome may favor host responses during infections against pathogens that inhibit components of the pyroptotic cell death including caspase-1 and gasdermin-D.
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Affiliation(s)
- Danielle P. A. Mascarenhas
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
| | - Daiane M. Cerqueira
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
| | - Marcelo S. F. Pereira
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
| | - Fernanda V. S. Castanheira
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
| | - Talita D. Fernandes
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
| | - Graziele Z. Manin
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
| | - Larissa D. Cunha
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
| | - Dario S. Zamboni
- Department of Cell Biology, School of Medicine of Ribeirão Preto, University of São Paulo. Ribeirão Preto, Brazil
- * E-mail:
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Diamond CE, Leong KWK, Vacca M, Rivers-Auty J, Brough D, Mortellaro A. Salmonella typhimurium-induced IL-1 release from primary human monocytes requires NLRP3 and can occur in the absence of pyroptosis. Sci Rep 2017; 7:6861. [PMID: 28761045 PMCID: PMC5537352 DOI: 10.1038/s41598-017-07081-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/22/2017] [Indexed: 12/22/2022] Open
Abstract
Large molecular complexes known as inflammasomes regulate the release of IL-1β from immune cells in response to infection and injury. Salmonella typhimurium infection is reported to activate NLRP3 and NLRC4 inflammasomes which are subsequently involved in pyroptosis of the cell and pathogen clearance. However, the response to S. typhimurium in primary human monocytes has not been studied in detail. The aim of this study was to investigate the effect of S. typhimurium on inflammasomes in primary human monocytes. Much of the previous research in the field has been conducted in murine models and human THP-1 cells, which may not reflect the responses of primary human monocytes. Here, we report that inhibiting NLRP3 with the selective inhibitor MCC950, blocked release of IL-1β and the related cytokine IL-1α from primary human monocytes in response to S. typhimurium. Additionally, under these conditions S. typhimurium-induced IL-1 release occurred independently of pyroptosis. We propose that IL-1β release without pyroptosis may occur in early-recruited monocytes to regulate a maximal innate immune response to Salmonella infection, allowing a sustained inflammatory signal. This insight into the mechanisms involved in IL-1 release from primary human monocytes highlights major differences between immune cell types, and the defences they employ during bacterial infection.
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Affiliation(s)
- Catherine E Diamond
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, 138648, Singapore.,Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PT, UK
| | - Keith Weng Kit Leong
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, 138648, Singapore
| | - Maurizio Vacca
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, 138648, Singapore
| | - Jack Rivers-Auty
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PT, UK
| | - David Brough
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, M13 9PT, UK.
| | - Alessandra Mortellaro
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore, 138648, Singapore.
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126
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Inhibition of Inflammasome-Dependent Interleukin 1β Production by Streptococcal NAD +-Glycohydrolase: Evidence for Extracellular Activity. mBio 2017; 8:mBio.00756-17. [PMID: 28720729 PMCID: PMC5516252 DOI: 10.1128/mbio.00756-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Group A Streptococcus (GAS) is a common human pathogen and the etiologic agent of a large number of diseases ranging from mild, self-limiting infections to invasive life-threatening conditions. Two prominent virulence factors of this bacterium are the genetically and functionally linked pore-forming toxin streptolysin O (SLO) and its cotoxin NAD+-glycohydrolase (NADase). Overexpression of these toxins has been linked to increased bacterial virulence and is correlated with invasive GAS disease. NADase can be translocated into host cells by a SLO-dependent mechanism, and cytosolic NADase has been assigned multiple properties such as protection of intracellularly located GAS bacteria and induction of host cell death through energy depletion. Here, we used a set of isogenic GAS mutants and a macrophage infection model and report that streptococcal NADase inhibits the innate immune response by decreasing inflammasome-dependent interleukin 1β (IL-1β) release from infected macrophages. Regulation of IL-1β was independent of phagocytosis and ensued also under conditions not allowing SLO-dependent translocation of NADase into the host cell cytosol. Thus, our data indicate that NADase not only acts intracellularly but also has an immune regulatory function in the extracellular niche. In the mid-1980s, the incidence and severity of invasive infections caused by serotype M1 GAS suddenly increased. The results of genomic analyses suggested that this increase was due to the spread of clonal bacterial strains and identified a recombination event leading to enhanced production of the SLO and NADase toxins in these strains. However, despite its apparent importance in GAS pathogenesis, the function of NADase remains poorly understood. In this study, we demonstrate that NADase inhibits inflammasome-dependent IL-1β release from infected macrophages. While previously described functions of NADase pertain to its role upon SLO-mediated translocation into the host cell cytosol, our data suggest that the immune regulatory function of NADase is exerted by nontranslocated enzyme, identifying a previously unrecognized extracellular niche for NADase functionality. This immune regulatory property of extracellular NADase adds another possible explanation to how increased secretion of NADase correlates with bacterial virulence.
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127
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Patel R, Kim K, Shutinoski B, Wachholz K, Krishnan L, Sad S. Culling of APCs by inflammatory cell death pathways restricts TIM3 and PD-1 expression and promotes the survival of primed CD8 T cells. Cell Death Differ 2017; 24:1900-1911. [PMID: 28686578 DOI: 10.1038/cdd.2017.112] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 05/17/2017] [Accepted: 06/06/2017] [Indexed: 12/18/2022] Open
Abstract
We evaluated the impact of premature cell death of antigen-presenting cells (APCs) by Caspase-1- and RipK3-signaling pathways on CD8+ T-cell priming during infection of mice with Salmonella typhimurium (ST). Our results indicate that Caspase1 and RipK3 synergize to rapidly eliminate infected APCs, which does not influence the initial activation of CD8+ T cells. However, the maintenance of primed CD8+ T cells was greatly compromised when both these pathways were disabled. Caspase-1- and RipK3-signaling did not influence NF-κB signaling in APCs, but synergized to promote processing of IL-1 and IL-18. Combined deficiency of Caspase1 and RipK3 resulted in compromised innate immunity and accelerated host fatality due to poor processing of IL-18. In contrast, synergism in cell death by Caspase-1- and RipK3 resulted in restriction of PD-1 and TIM3 expression on primed CD8+ T cells, which promoted the survival of activated CD8+ T cells.
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Affiliation(s)
- Rajen Patel
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Kwangsin Kim
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Bojan Shutinoski
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Kristina Wachholz
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.,National Research Council of Canada, Ottawa, Ontario, Canada
| | - Lakshmi Krishnan
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.,National Research Council of Canada, Ottawa, Ontario, Canada
| | - Subash Sad
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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128
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Abstract
Inflammasomes are macromolecular cytoplasmic complexes that act as signaling platforms for the activation of inflammatory caspases. Their activation triggers the processing and secretion of the pro-inflammatory cytokines IL-1β and IL-18, as well as the induction of a specialized form of inflammatory cell death termed pyroptosis. Here, we review the mechanisms of inflammasome activation triggered by the intracellular pathogen Salmonella enterica serovar Typhimurium. We highlight the different inflammasome subfamilies utilized by macrophages, neutrophils, dendritic cells, and intestinal epithelial cells response to a Salmonella infection as well as the Salmonella ligands that trigger each inflammasome's formation. We also discuss the evasion strategies utilized by Salmonella to avoid inflammasome detection. Overall, inflammasomes play a key and multilayered role at distinct stages of host cell defense against Salmonella infection.
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129
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Philip NH, Zwack EE, Brodsky IE. Activation and Evasion of Inflammasomes by Yersinia. Curr Top Microbiol Immunol 2017; 397:69-90. [PMID: 27460805 DOI: 10.1007/978-3-319-41171-2_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The innate immune system plays an essential role in initiating the early response against microbial infection, as well as instructing and shaping subsequent responses. Microbial pathogens are enormously diverse in terms of the niches they occupy, their metabolic properties and requirements, and the cellular pathways that they target. Nevertheless, innate sensing of pathogens triggers a relatively stereotyped set of responses that involve transcriptional induction of key inflammatory mediators, as well as post-translational assembly and activation of a multiprotein inflammatory complex termed 'the inflammasome.' Along with classical Pattern Recognition Receptors, the inflammasome activation pathway has emerged as a key regulator of tissue homeostasis and immune defense. Components of the inflammasome generally exist within the cell in a soluble, monomeric state, and oligomerize in response to diverse enzymatic activities associated with infection or cellular stress. Inflammasome assembly triggers activation of the pro-enzyme caspase-1, resulting in the cleavage of caspase-1 targets. The most extensively studied targets are the cytokines of the IL-1 family, but the recent discovery of Gasdermin D as a novel target of caspase-1 and the related inflammatory caspase, caspase-11, has begun to mechanistically define the links between caspase-1 activation and cell death. Cell death is a hallmark of macrophage infection by many pathogens, including the gram-negative bacterial pathogens of the genus Yersinia. Intriguingly, the activities of the Yersinia-secreted effector proteins and the type III secretion system (T3SS) itself have been linked to both inflammasome activation and evasion during infection. The balance between these activating and inhibitory activities shapes the outcome of Yersinia infection. Here, we describe the current state of knowledge on interactions between Yersinia and the inflammasome system, with the goal of integrating these findings within the general framework of inflammasome responses to microbial pathogens.
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Affiliation(s)
- Naomi H Philip
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, 19104, USA.,Institute for Immunology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA.,Immunology Graduate Group, Philadelphia, PA, 19104, USA
| | - Erin E Zwack
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, 19104, USA.,Cell and Molecular Biology Graduate Group, Philadelphia, PA, 19104, USA
| | - Igor E Brodsky
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA, 19104, USA. .,Institute for Immunology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA.
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130
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Kaneko N, Ito Y, Iwasaki T, Takeda H, Sawasaki T, Migita K, Agematsu K, Koga T, Kawakami A, Yachie A, Yoshiura KI, Morikawa S, Kurata M, Masumoto J. Poly (I:C) and hyaluronic acid directly interact with NLRP3, resulting in the assembly of NLRP3 and ASC in a cell-free system. EUR J INFLAMM 2017. [DOI: 10.1177/1721727x17711047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
In the NLR family, pyrin domain containing 3 (NLRP3) is an intracellular pattern recognition receptor that activates pro-caspase-1, leading to IL-1β and IL-18 processing and activation in a large complex called the NLRP3 inflammasome. Since various pathogens or endogenous metabolites have been reported to stimulate NLRP3 inflammasome, the interaction between NLRP3 and ASC induced by these stimulants may be an attractive drug target for NLRP3-related diseases, called inflammasomopathies. However, the endogenous ligand that directly interacts with NLRP3, leading to binding to ASC, remains unclear. Therefore, we developed a cell-free system consisting of NLRP3, ASC, and pro-caspase-1 or ASC and NLRP3 with an amplified luminescent proximity homogeneous assay (ALPHA). ALPHA signals of the interaction between NLRP3 and ASC were not enhanced following an incubation without any ligand, whereas strong ALPHA signals for the interaction between NLRP3 and ASC and between NLRP3 and pro-caspase-1 with the adaptor ASC were observed upon an incubation with poly (I:C) and hyaluronic acid (HA). Poly (I:C) and HA both directly interacted with NLRP3 within a specific concentration. These results suggest that NLRP3 directly interacts with intrinsic RNA and HA, which is followed by the activation of NLRP3 inflammasome, and the cell-free system consisting of NLRP3 and ASC, or NLRP3, ASC, and pro-caspase-1 may be a useful tool for elucidating the pathogenesis of inflammasomopathies and developing target therapeutics.
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Affiliation(s)
- Naoe Kaneko
- Department of Pathology, Proteo-Science Center and Graduate School of Medicine, Ehime University, Toon, Japan
| | - Yuki Ito
- Department of Pathology, Proteo-Science Center and Graduate School of Medicine, Ehime University, Toon, Japan
| | - Tomoyuki Iwasaki
- Department of Pathology, Proteo-Science Center and Graduate School of Medicine, Ehime University, Toon, Japan
| | - Hiroyuki Takeda
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Tatsuya Sawasaki
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Kiyoshi Migita
- Department of Gastroenterology and Rheumatology, School of Medicine, Fukushima Medical University, Fukushima, Japan
| | - Kazunaga Agematsu
- Department of Infectious Immunology, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Tomohiro Koga
- Unit of Translational Medicine, Department of Immunology & Rheumatology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- Medical Education Development Center, Nagasaki University Hospital, Nagasaki, Japan
| | - Atsushi Kawakami
- Unit of Translational Medicine, Department of Immunology & Rheumatology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Akihiro Yachie
- Department of Pediatrics, School of Medicine, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Koh-ichiro Yoshiura
- Department of Human Genetics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Shinnosuke Morikawa
- Department of Pathology, Proteo-Science Center and Graduate School of Medicine, Ehime University, Toon, Japan
| | - Mie Kurata
- Department of Pathology, Proteo-Science Center and Graduate School of Medicine, Ehime University, Toon, Japan
| | - Junya Masumoto
- Department of Pathology, Proteo-Science Center and Graduate School of Medicine, Ehime University, Toon, Japan
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131
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Vajjhala PR, Ve T, Bentham A, Stacey KJ, Kobe B. The molecular mechanisms of signaling by cooperative assembly formation in innate immunity pathways. Mol Immunol 2017; 86:23-37. [PMID: 28249680 DOI: 10.1016/j.molimm.2017.02.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 02/16/2017] [Accepted: 02/19/2017] [Indexed: 12/25/2022]
Abstract
The innate immune system is the first line of defense against infection and responses are initiated by pattern recognition receptors (PRRs) that detect pathogen-associated molecular patterns (PAMPs). PRRs also detect endogenous danger-associated molecular patterns (DAMPs) that are released by damaged or dying cells. The major PRRs include the Toll-like receptor (TLR) family members, the nucleotide binding and oligomerization domain, leucine-rich repeat containing (NLR) family, the PYHIN (ALR) family, the RIG-1-like receptors (RLRs), C-type lectin receptors (CLRs) and the oligoadenylate synthase (OAS)-like receptors and the related protein cyclic GMP-AMP synthase (cGAS). The different PRRs activate specific signaling pathways to collectively elicit responses including the induction of cytokine expression, processing of pro-inflammatory cytokines and cell-death responses. These responses control a pathogenic infection, initiate tissue repair and stimulate the adaptive immune system. A central theme of many innate immune signaling pathways is the clustering of activated PRRs followed by sequential recruitment and oligomerization of adaptors and downstream effector enzymes, to form higher-order arrangements that amplify the response and provide a scaffold for proximity-induced activation of the effector enzymes. Underlying the formation of these complexes are co-operative assembly mechanisms, whereby association of preceding components increases the affinity for downstream components. This ensures a rapid immune response to a low-level stimulus. Structural and biochemical studies have given key insights into the assembly of these complexes. Here we review the current understanding of assembly of immune signaling complexes, including inflammasomes initiated by NLR and PYHIN receptors, the myddosomes initiated by TLRs, and the MAVS CARD filament initiated by RIG-1. We highlight the co-operative assembly mechanisms during assembly of each of these complexes.
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Affiliation(s)
- Parimala R Vajjhala
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Thomas Ve
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; Institute for Glycomics, Griffith University, Southport, QLD 4222, Australia
| | - Adam Bentham
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia; School of Biological Sciences, Flinders University, Adelaide, SA 5001, Australia
| | - Katryn J Stacey
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia
| | - Bostjan Kobe
- School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Centre, University of Queensland, Brisbane, QLD 4072, Australia.
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132
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Rauch I, Deets KA, Ji DX, von Moltke J, Tenthorey JL, Lee AY, Philip NH, Ayres JS, Brodsky IE, Gronert K, Vance RE. NAIP-NLRC4 Inflammasomes Coordinate Intestinal Epithelial Cell Expulsion with Eicosanoid and IL-18 Release via Activation of Caspase-1 and -8. Immunity 2017; 46:649-659. [PMID: 28410991 PMCID: PMC5476318 DOI: 10.1016/j.immuni.2017.03.016] [Citation(s) in RCA: 277] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 12/09/2016] [Accepted: 03/24/2017] [Indexed: 11/25/2022]
Abstract
Intestinal epithelial cells (IECs) form a critical barrier against pathogen invasion. By generation of mice in which inflammasome expression is restricted to IECs, we describe a coordinated epithelium-intrinsic inflammasome response in vivo. This response was sufficient to protect against Salmonella tissue invasion and involved a previously reported IEC expulsion that was coordinated with lipid mediator and cytokine production and lytic IEC death. Excessive inflammasome activation in IECs was sufficient to result in diarrhea and pathology. Experiments with IEC organoids demonstrated that IEC expulsion did not require other cell types. IEC expulsion was accompanied by a major actin rearrangement in neighboring cells that maintained epithelium integrity but did not absolutely require Caspase-1 or Gasdermin D. Analysis of Casp1-/-Casp8-/- mice revealed a functional Caspase-8 inflammasome in vivo. Thus, a coordinated IEC-intrinsic, Caspase-1 and -8 inflammasome response plays a key role in intestinal immune defense and pathology.
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Affiliation(s)
- Isabella Rauch
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Katherine A Deets
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Daisy X Ji
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jakob von Moltke
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jeannette L Tenthorey
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Angus Y Lee
- Cancer Research Laboratory and Immunotherapeutics and Vaccine Research Initiative, University of California, Berkeley, CA 94720, USA
| | - Naomi H Philip
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
| | - Janelle S Ayres
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Igor E Brodsky
- Department of Pathobiology, University of Pennsylvania School of Veterinary Medicine, Philadelphia, PA 19104, USA
| | - Karsten Gronert
- Vision Science Program, School of Optometry, University of California at Berkeley, Berkeley, CA 94720, USA
| | - Russell E Vance
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, University of California, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA; Cancer Research Laboratory and Immunotherapeutics and Vaccine Research Initiative, University of California, Berkeley, CA 94720, USA.
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133
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Abstract
Urinary tract infections (UTIs) cause a huge burden of morbidity worldwide with recurrent UTIs becoming increasingly frequent owing to the emergence of antibiotic-resistant bacterial strains. Interactions between the innate and adaptive immune responses to pathogens colonizing the urinary tract have been the focus of much research. Inflammasomes are part of the innate immune defence and can respond rapidly to infectious insult. Assembly of the multiprotein inflammasome complex activates caspase-1, processes proinflammatory cytokines IL-1β and IL-18, and induces pyroptosis. These effector pathways, in turn, act at different levels to either prevent or resolve infection, or eliminate the infectious agent itself. In certain instances, inflammasome activation promotes tissue pathology; however, the precise functions of inflammasomes in UTIs remain unexplored. An improved understanding of inflammasomes could provide novel approaches for the design of diagnostics and therapeutics for complicated UTIs, enabling us to overcome the challenge of drug resistance.
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134
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Sharma D, Sharma BR, Vogel P, Kanneganti TD. IL-1β and Caspase-1 Drive Autoinflammatory Disease Independently of IL-1α or Caspase-8 in a Mouse Model of Familial Mediterranean Fever. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:236-244. [PMID: 27998728 PMCID: PMC5389372 DOI: 10.1016/j.ajpath.2016.10.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/10/2016] [Accepted: 10/17/2016] [Indexed: 12/19/2022]
Abstract
Mutations in the gene encoding pyrin are associated with autoinflammatory disorder Familial Mediterranean Fever (FMF). A FMF-knock-in mouse strain that expresses chimeric pyrin protein with a V726A mutation (MefvV726A/V726A) was generated to model human FMF. This mouse strain shows an autoinflammatory disorder that is prevented by genetic deletion of IL-1 (IL-1) receptor or apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC). ASC-mediated cell death leads to the release of IL-1α and IL-1β, both of which signal through IL-1 receptor. Furthermore, caspase-1 and caspase-8 can interact with ASC to mediate secretion of IL-1 cytokines. The specific IL-1 cytokine instigating development of FMF and the enzymatic caspase involved in its secretion currently are unknown. In this study, we show that the autoinflammation observed in MefvV726A/V726A mice is mediated specifically by IL-1β and not IL-1α. Furthermore, the disorder is dependent on the caspase-1-ASC axis, whereas caspase-8 is dispensable. Concurrently, aberrant IL-1β release by MefvV726A/V726A monocytes in response to stimulation with lipopolysaccharide also is dependent on the caspase-1-ASC axis. In conclusion, our studies have uncovered a specific role for caspase-1-mediated IL-1β release in the manifestation of FMF.
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Affiliation(s)
- Deepika Sharma
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Bhesh Raj Sharma
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, Tennessee
| | - Peter Vogel
- Animal Resources Center and the Veterinary Pathology Core, St. Jude Children's Research Hospital, Memphis, Tennessee
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135
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Jorgensen I, Rayamajhi M, Miao EA. Programmed cell death as a defence against infection. Nat Rev Immunol 2017; 17:151-164. [PMID: 28138137 DOI: 10.1038/nri.2016.147] [Citation(s) in RCA: 656] [Impact Index Per Article: 93.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Eukaryotic cells can die from physical trauma, which results in necrosis. Alternatively, they can die through programmed cell death upon the stimulation of specific signalling pathways. In this Review, we discuss the role of different cell death pathways in innate immune defence against bacterial and viral infection: apoptosis, necroptosis, pyroptosis and NETosis. We describe the interactions that interweave different programmed cell death pathways, which create complex signalling networks that cross-guard each other in the evolutionary 'arms race' with pathogens. Finally, we describe how the resulting cell corpses - apoptotic bodies, pore-induced intracellular traps (PITs) and neutrophil extracellular traps (NETs) - promote the clearance of infection.
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Affiliation(s)
- Ine Jorgensen
- Department of Immunology, Oslo University Hospital, Sognsvannsveien 20, Rikshospitalet 0372, Oslo, Norway
| | - Manira Rayamajhi
- Camargo Pharmaceutical Services, 2505 Meridian Parkway, Suite 175, Durham, North Carolina 27713, USA
| | - Edward A Miao
- Department of Microbiology and Immunology, Lineberger Comprehensive Cancer Center, and Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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136
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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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137
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Feltham R, Vince JE, Lawlor KE. Caspase-8: not so silently deadly. Clin Transl Immunology 2017; 6:e124. [PMID: 28197335 PMCID: PMC5292560 DOI: 10.1038/cti.2016.83] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/27/2016] [Accepted: 11/29/2016] [Indexed: 12/22/2022] Open
Abstract
Apoptosis is a caspase-dependent programmed form of cell death, which is commonly believed to be an immunologically silent process, required for mammalian development and maintenance of cellular homoeostasis. In contrast, lytic forms of cell death, such as RIPK3- and MLKL-driven necroptosis, and caspase-1/11-dependent pyroptosis, are postulated to be inflammatory via the release of damage associated molecular patterns (DAMPs). Recently, the function of apoptotic caspase-8 has been extended to the negative regulation of necroptosis, the cleavage of inflammatory interleukin-1β (IL-1β) to its mature bioactive form, either directly or via the NLRP3 inflammasome, and the regulation of cytokine transcriptional responses. In view of these recent advances, human autoinflammatory diseases that are caused by mutations in cell death regulatory machinery are now associated with inappropriate inflammasome activation. In this review, we discuss the emerging crosstalk between cell death and innate immune cell inflammatory signalling, particularly focusing on novel non-apoptotic functions of caspase-8. We also highlight the growing number of autoinflammatory diseases that are associated with enhanced inflammasome function.
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Affiliation(s)
- Rebecca Feltham
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - James E Vince
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Kate E Lawlor
- Inflammation Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
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138
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Critical role of caspase-8-mediated IL-1 signaling in promoting Th2 responses during asthma pathogenesis. Mucosal Immunol 2017; 10:128-138. [PMID: 27007676 PMCID: PMC5035164 DOI: 10.1038/mi.2016.25] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 02/18/2016] [Indexed: 02/04/2023]
Abstract
Allergic asthma is a chronic inflammatory disorder of the airways that affects >300 million people worldwide. The pro-inflammatory cytokines interleukin (IL)-1α and IL-1β have essential roles in the pathogenesis of asthma. However, the mechanisms underlying the production of IL-1 cytokines in allergic asthma remain unclear. In this study, we used a mouse model of ovalbumin-induced asthma to identify a crucial role for caspase-8 in the development of allergic airway inflammation. We further demonstrated that hematopoietic cells have dominant roles in caspase-8-mediated allergic airway inflammation. Caspase-8 was required for the production of IL-1 cytokines to promote Th2 immune response, which promotes the development of pulmonary eosinophilia and inflammation. Thus, our study identifies caspase-8 as a master regulator of IL-1 cytokines that contribute to the pathogenesis of asthma and implicates caspase-8 inhibition as a potential therapeutic strategy for asthmatic patients.
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139
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Raghawan AK, Sripada A, Gopinath G, Pushpanjali P, Kumar Y, Radha V, Swarup G. A Disease-associated Mutant of NLRC4 Shows Enhanced Interaction with SUG1 Leading to Constitutive FADD-dependent Caspase-8 Activation and Cell Death. J Biol Chem 2016; 292:1218-1230. [PMID: 27974463 DOI: 10.1074/jbc.m116.763979] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 11/15/2016] [Indexed: 11/06/2022] Open
Abstract
Nod-like receptor family card containing 4 (NLRC4)/Ipaf is involved in recognition of pathogen-associated molecular patterns leading to caspase-1 activation and cytokine release, which mediate protective innate immune response. Point mutations in NLRC4 cause autoinflammatory syndromes. Although all the mutations result in constitutive caspase-1 activation, their phenotypic presentations are different, implying that these mutations cause different alterations in properties of NLRC4. NLRC4 interacts with SUG1 and induces caspase-8-mediated cell death. Here, we show that one of the autoinflammatory syndrome-causing mutants of NLRC4, H443P, but not T337A and V341A, constitutively activates caspase-8 and induces apoptotic cell death in human lung epithelial cells. Compared with wild type NLRC4, the H443P mutant shows stronger interaction with SUG1 and with ubiquitinated cellular proteins. Phosphorylation of NLRC4 at Ser533 plays a crucial role in caspase-8 activation and cell death. However, H443P mutant does not require Ser533 phosphorylation for caspase-8 activation and cell death. Caspase-8 activation by NLRC4 and its H443P mutant are dependent on the adaptor protein FADD. A phosphomimicking mutant of NLRC4, S533D does not require SUG1 activity for inducing cell death. Ubiquitin-tagged NLRC4 could induce cell death and activate caspase-8 independent of Ser533 phosphorylation. Our work suggests that SUG1-mediated signaling results in enhanced ubiquitination and regulates FADD-dependent caspase-8 activation by NLRC4. We show that the autoinflammation-associated H443P mutant is altered in interaction with SUG1 and ubiquitinated proteins, triggering constitutive caspase-8-mediated cell death dependent on FADD but independent of Ser533 phosphorylation.
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Affiliation(s)
| | - Anand Sripada
- From the CSIR-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Gayathri Gopinath
- From the CSIR-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Pendyala Pushpanjali
- From the CSIR-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Yatender Kumar
- From the CSIR-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Vegesna Radha
- From the CSIR-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
| | - Ghanshyam Swarup
- From the CSIR-Centre for Cellular and Molecular Biology, Hyderabad 500007, India
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140
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Alternative inflammasome activation enables IL-1β release from living cells. Curr Opin Immunol 2016; 44:7-13. [PMID: 27842238 DOI: 10.1016/j.coi.2016.10.007] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 10/28/2016] [Indexed: 12/11/2022]
Abstract
Classical modes of NLRP3 activation entail a priming step that enables its activation (signal 1) and a potassium efflux-dependent activation signal (signal 2) that triggers pyroptosome formation and pyroptosis, a lytic cell death necessary for IL-1β release. Opposing to that, human monocytes engage an alternative NLRP3 inflammasome pathway in response to LPS that proceeds in the absence of signal 2 activation and enables IL-1β secretion without pyroptosis. This specifically relies on Caspase-8 to propagate signaling to NLRP3, leading to inflammasome activation in absence of pyroptosome formation. Here, we summarize the current knowledge about alternative inflammasome activation, discuss potential extensions of this signaling entity beyond LPS-dependent activation, speculate about its role in tissue homeostasis and sterile inflammation and highlight the implications of pyroptosis-independent IL-1β secretion.
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141
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Philip NH, DeLaney A, Peterson LW, Santos-Marrero M, Grier JT, Sun Y, Wynosky-Dolfi MA, Zwack EE, Hu B, Olsen TM, Rongvaux A, Pope SD, López CB, Oberst A, Beiting DP, Henao-Mejia J, Brodsky IE. Activity of Uncleaved Caspase-8 Controls Anti-bacterial Immune Defense and TLR-Induced Cytokine Production Independent of Cell Death. PLoS Pathog 2016; 12:e1005910. [PMID: 27737018 PMCID: PMC5063320 DOI: 10.1371/journal.ppat.1005910] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/01/2016] [Indexed: 12/29/2022] Open
Abstract
Caspases regulate cell death programs in response to environmental stresses, including infection and inflammation, and are therefore critical for the proper operation of the mammalian immune system. Caspase-8 is necessary for optimal production of inflammatory cytokines and host defense against infection by multiple pathogens including Yersinia, but whether this is due to death of infected cells or an intrinsic role of caspase-8 in TLR-induced gene expression is unknown. Caspase-8 activation at death signaling complexes results in its autoprocessing and subsequent cleavage and activation of its downstream apoptotic targets. Whether caspase-8 activity is also important for inflammatory gene expression during bacterial infection has not been investigated. Here, we report that caspase-8 plays an essential cell-intrinsic role in innate inflammatory cytokine production in vivo during Yersinia infection. Unexpectedly, we found that caspase-8 enzymatic activity regulates gene expression in response to bacterial infection as well as TLR signaling independently of apoptosis. Using newly-generated mice in which caspase-8 autoprocessing is ablated (Casp8DA/DA), we now demonstrate that caspase-8 enzymatic activity, but not autoprocessing, mediates induction of inflammatory cytokines by bacterial infection and a wide variety of TLR stimuli. Because unprocessed caspase-8 functions in an enzymatic complex with its homolog cFLIP, our findings implicate the caspase-8/cFLIP heterodimer in control of inflammatory cytokines during microbial infection, and provide new insight into regulation of antibacterial immune defense. TLR signaling induces expression of key inflammatory cytokines and pro-survival factors that facilitate control of microbial infection. TLR signaling can also engage cell death pathways through activation of enzymes known as caspases. Caspase-8 activates apoptosis in response to infection by pathogens that interfere with NF-κB signaling, including Yersinia, but has also recently been linked to control of inflammatory gene expression. Pathogenic Yersinia can cause severe disease ranging from gastroenteritis to plague. While caspase-8 mediates cell death in response to Yersinia infection as well as other signals, its precise role in gene expression and host defense during in vivo infection is unknown. Here, we show that caspase-8 activity promotes cell-intrinsic cytokine expression, independent of its role in cell death in response to Yersinia infection. Our studies further demonstrate that caspase-8 enzymatic activity plays a previously undescribed role in ensuring optimal TLR-induced gene expression by innate cells during bacterial infection. This work sheds new light on mechanisms that regulate essential innate anti-bacterial immune defense.
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Affiliation(s)
- Naomi H. Philip
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
- University of Pennsylvania Perelman School of Medicine, Institute for Immunology, Philadelphia, Pennsylvania, United States of America
| | - Alexandra DeLaney
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
| | - Lance W. Peterson
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
- University of Pennsylvania Perelman School of Medicine, Institute for Immunology, Philadelphia, Pennsylvania, United States of America
| | - Melanie Santos-Marrero
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
- University of Pennsylvania Perelman School of Medicine, Institute for Immunology, Philadelphia, Pennsylvania, United States of America
| | - Jennifer T. Grier
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
| | - Yan Sun
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
| | - Meghan A. Wynosky-Dolfi
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
| | - Erin E. Zwack
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
| | - Baofeng Hu
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
| | - Tayla M. Olsen
- University of Washington, Department of Immunology, Seattle, Washington, United States of America
| | - Anthony Rongvaux
- Fred Hutchinson Cancer Research Center, Clinical Research Division and Program in Immunology, Seattle, Washington, United States of America
| | - Scott D. Pope
- Yale University School of Medicine, Department of Immunobiology, New Haven, Connecticut, United States of America
| | - Carolina B. López
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
- University of Pennsylvania Perelman School of Medicine, Institute for Immunology, Philadelphia, Pennsylvania, United States of America
| | - Andrew Oberst
- University of Washington, Department of Immunology, Seattle, Washington, United States of America
| | - Daniel P. Beiting
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
- University of Pennsylvania Perelman School of Medicine, Institute for Immunology, Philadelphia, Pennsylvania, United States of America
| | - Jorge Henao-Mejia
- University of Pennsylvania Perelman School of Medicine, Institute for Immunology, Philadelphia, Pennsylvania, United States of America
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania and Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, United States of America
| | - Igor E. Brodsky
- University of Pennsylvania School of Veterinary Medicine, Department of Pathobiology, Philadelphia, Pennsylvania, United States of America
- University of Pennsylvania Perelman School of Medicine, Institute for Immunology, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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142
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Pereira M, Tourlomousis P, Wright J, P. Monie T, Bryant CE. CARD9 negatively regulates NLRP3-induced IL-1β production on Salmonella infection of macrophages. Nat Commun 2016; 7:12874. [PMID: 27670879 PMCID: PMC5052644 DOI: 10.1038/ncomms12874] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 08/11/2016] [Indexed: 12/30/2022] Open
Abstract
Interleukin-1β (IL-1β) is a proinflammatory cytokine required for host control of bacterial infections, and its production must be tightly regulated to prevent excessive inflammation. Here we show that caspase recruitment domain-containing protein 9 (CARD9), a protein associated with induction of proinflammatory cytokines by fungi, has a negative role on IL-1β production during bacterial infection. Specifically, in response to activation of the nucleotide oligomerization domain receptor pyrin-domain containing protein 3 (NLRP3) by Salmonella infection, CARD9 negatively regulates IL-1β by fine-tuning pro-IL-1β expression, spleen tyrosine kinase (SYK)-mediated NLRP3 activation and repressing inflammasome-associated caspase-8 activity. CARD9 is suppressed during Salmonella enterica serovar Typhimurium infection, facilitating increased IL-1β production. CARD9 is, therefore, a central signalling hub that coordinates a pathogen-specific host inflammatory response.
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Affiliation(s)
- Milton Pereira
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Panagiotis Tourlomousis
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - John Wright
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Tom P. Monie
- Medical Research Council Human Nutrition Research, Elsie Widdowson Laboratory, 120 Fulbourn Road, Cambridge CB1 9NL, UK
| | - Clare E. Bryant
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
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143
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Carrillo I, Droguett D, Castillo C, Liempi A, Muñoz L, Maya JD, Galanti N, Kemmerling U. Caspase-8 activity is part of the BeWo trophoblast cell defense mechanisms against Trypanosoma cruzi infection. Exp Parasitol 2016; 168:9-15. [DOI: 10.1016/j.exppara.2016.06.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 06/17/2016] [Indexed: 02/08/2023]
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144
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Sharma D, Kanneganti TD. The cell biology of inflammasomes: Mechanisms of inflammasome activation and regulation. J Cell Biol 2016; 213:617-29. [PMID: 27325789 PMCID: PMC4915194 DOI: 10.1083/jcb.201602089] [Citation(s) in RCA: 500] [Impact Index Per Article: 62.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 05/27/2016] [Indexed: 02/08/2023] Open
Abstract
Over the past decade, numerous advances have been made in the role and regulation of inflammasomes during pathogenic and sterile insults. An inflammasome complex comprises a sensor, an adaptor, and a zymogen procaspase-1. The functional output of inflammasome activation includes secretion of cytokines, IL-1β and IL-18, and induction of an inflammatory form of cell death called pyroptosis. Recent studies have highlighted the intersection of this inflammatory response with fundamental cellular processes. Novel modulators and functions of inflammasome activation conventionally associated with the maintenance of homeostatic biological functions have been uncovered. In this review, we discuss the biological processes involved in the activation and regulation of the inflammasome.
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Affiliation(s)
- Deepika Sharma
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105
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145
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Shutinoski B, Alturki NA, Rijal D, Bertin J, Gough PJ, Schlossmacher MG, Sad S. K45A mutation of RIPK1 results in poor necroptosis and cytokine signaling in macrophages, which impacts inflammatory responses in vivo. Cell Death Differ 2016; 23:1628-37. [PMID: 27258786 DOI: 10.1038/cdd.2016.51] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 04/28/2016] [Accepted: 05/05/2016] [Indexed: 02/06/2023] Open
Abstract
Receptor interacting protein kinase 1 (RIPK1) participates in several cell signaling complexes that promote cell activation and cell death. Stimulation of RIPK1 in the absence of caspase signaling induces regulated necrosis (necroptosis), which promotes an inflammatory response. Understanding of the mechanisms through which RIPK1 promotes inflammation has been unclear. Herein we have evaluated the impact of a K45A mutation of RIPK1 on necroptosis of macrophages and the activation of inflammatory response. We show that K45A mutation of RIPK1 results in attenuated necroptosis of macrophages in response to stimulation with LPS, TNFα and IFNβ in the absence of caspase signaling. Impairment in necroptosis correlated with poor phosphorylation of RIPK1, RIPK3 and reduced trimerization of MLKL. Furthermore, K45A mutation of RIPK1 resulted in poor STAT1 phosphorylation (at S727) and expression of RANTES and MIP-1α following TNF-R engagement in the absence of caspase activation. Our results further indicate that in the absence of stimulation by pathogen-associated molecular patterns (PAMPs), cellular inhibitors of apoptotic proteins (cIAPs) prevent the K45-dependent auto-phosphorylation of RIPK1, leading to resistance against necroptosis. Finally, RIPK1(K45A) mice displayed attenuated inflammatory response in vivo as they were significantly resistant against endotoxin shock, but highly susceptible against a challenge with Salmonella typhimurium. This correlated with reduced expression of IL-1β and ROS, and poor processing of caspase 8 by RIPK1(K45A) macrophages. Overall, these results indicate that K45 mediated kinase activity of RIPK1 is not only important for necroptosis but it also has a key role in promoting cytokine signaling and host response to inflammatory stimuli.
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Affiliation(s)
- B Shutinoski
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada.,Program in Neuroscience and Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
| | - N A Alturki
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - D Rijal
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - J Bertin
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - P J Gough
- Pattern Recognition Receptor Discovery Performance Unit, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Collegeville, PA 19426, USA
| | - M G Schlossmacher
- Program in Neuroscience and Division of Neurology, The Ottawa Hospital, Ottawa, ON, Canada
| | - S Sad
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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146
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Vanden Berghe T, Hassannia B, Vandenabeele P. An outline of necrosome triggers. Cell Mol Life Sci 2016; 73:2137-52. [PMID: 27052312 PMCID: PMC4887535 DOI: 10.1007/s00018-016-2189-y] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 01/09/2023]
Abstract
Necroptosis was initially identified as a backup cell death program when apoptosis is blocked. However, it is now recognized as a cellular defense mechanism against infections and is presumed to be a detrimental factor in several pathologies driven by cell death. Necroptosis is a prototypic form of regulated necrosis that depends on activation of the necrosome, which is a protein complex in which receptor interacting protein kinase (RIPK) 3 is activated. The RIP homotypic interaction motif (RHIM) is the core domain that regulates activation of the necrosome. To date, three RHIM-containing proteins have been reported to activate the kinase activity of RIPK3 within the necrosome: RIPK1, Toll/IL-1 receptor domain-containing adaptor inducing IFN-β (TRIF), and DNA-dependent activator of interferon regulatory factors (DAI). Here, we review and discuss commonalities and differences of the increasing number of activators of the necrosome. Since the discovery that activation of mixed lineage kinase domain-like (MLKL) by RIPK3 kinase activity is crucial in necroptosis, interest has increased in monitoring and therapeutically targeting their activation. The availability of new phospho-specific antibodies, pharmacologic inhibitors, and transgenic models will allow us to further document the role of necroptosis in degenerative, inflammatory and infectious diseases.
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Affiliation(s)
- Tom Vanden Berghe
- Inflammation Research Center, VIB, 9000, Ghent, Belgium.
- Department of Biomedical Molecular Biology, Ghent University, 9000, Ghent, Belgium.
| | - Behrouz Hassannia
- Inflammation Research Center, VIB, 9000, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, 9000, Ghent, Belgium
- Laboratory of Eukaryotic Gene Expression and Signal Transduction, Department of Physiology, Ghent University, 9000, Ghent, Belgium
| | - Peter Vandenabeele
- Inflammation Research Center, VIB, 9000, Ghent, Belgium.
- Department of Biomedical Molecular Biology, Ghent University, 9000, Ghent, Belgium.
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147
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Vince JE, Silke J. The intersection of cell death and inflammasome activation. Cell Mol Life Sci 2016; 73:2349-67. [PMID: 27066895 PMCID: PMC11108284 DOI: 10.1007/s00018-016-2205-2] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 02/07/2023]
Abstract
Inflammasomes sense cellular danger to activate the cysteine-aspartic protease caspase-1, which processes precursor interleukin-1β (IL-1β) and IL-18 into their mature bioactive fragments. In addition, activated caspase-1 or the related inflammatory caspase, caspase-11, can cleave gasdermin D to induce a lytic cell death, termed pyroptosis. The intertwining of IL-1β activation and cell death is further highlighted by research showing that the extrinsic apoptotic caspase, caspase-8, may, like caspase-1, directly process IL-1β, activate the NLRP3 inflammasome itself, or bind to inflammasome complexes to induce apoptotic cell death. Similarly, RIPK3- and MLKL-dependent necroptotic signaling can activate the NLRP3 inflammasome to drive IL-1β inflammatory responses in vivo. Here, we review the mechanisms by which cell death signaling activates inflammasomes to initiate IL-1β-driven inflammation, and highlight the clinical relevance of these findings to heritable autoinflammatory diseases. We also discuss whether the act of cell death can be separated from IL-1β secretion and evaluate studies suggesting that several cell death regulatory proteins can directly interact with, and modulate the function of, inflammasome and IL-1β containing protein complexes.
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Affiliation(s)
- James E Vince
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3050, Australia.
| | - John Silke
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia
- Department of Medical Biology, The University of Melbourne, Parkville, VIC, 3050, Australia
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148
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de Vasconcelos NM, Van Opdenbosch N, Lamkanfi M. Inflammasomes as polyvalent cell death platforms. Cell Mol Life Sci 2016; 73:2335-47. [PMID: 27048821 PMCID: PMC11108487 DOI: 10.1007/s00018-016-2204-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 02/07/2023]
Abstract
Inflammasomes are multi-protein platforms that are organized in the cytosol to cope with pathogens and cellular stress. The pattern recognition receptors NLRP1, NLRP3, NLRC4, AIM2 and Pyrin all assemble canonical platforms for caspase-1 activation, while caspase-11-dependent inflammasomes respond to intracellular Gram-negative pathogens. Inflammasomes are chiefly known for their roles in maturation and secretion of the inflammatory cytokines interleukin-(IL)1β and IL18, but they can also induce regulated cell death. Activation of caspases 1 and 11 in myeloid cells can trigger pyroptosis, a lytic and inflammatory cell death mode. Pyroptosis has been implicated in secretion of IL1β, IL18 and intracellular alarmins. Akin to these factors, it may have beneficial roles in controlling pathogen replication, but become detrimental in the context of chronic autoinflammatory diseases. Inflammasomes are increasingly implicated in induction of additional regulated cell death modes such as pyronecrosis and apoptosis. In this review, we overview recent advances in inflammasome-associated cell death research, illustrating the polyvalent roles of these macromolecular platforms in regulated cell death signaling.
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Affiliation(s)
- Nathalia M de Vasconcelos
- NOD-like Receptor and Inflammasome Laboratory, Inflammation Research Center, VIB, Technologiepark 927, B-9052, Zwijnaarde, Belgium
- Department of Internal Medicine, Ghent University, B-9000, Ghent, Belgium
| | - Nina Van Opdenbosch
- NOD-like Receptor and Inflammasome Laboratory, Inflammation Research Center, VIB, Technologiepark 927, B-9052, Zwijnaarde, Belgium
- Department of Internal Medicine, Ghent University, B-9000, Ghent, Belgium
| | - Mohamed Lamkanfi
- NOD-like Receptor and Inflammasome Laboratory, Inflammation Research Center, VIB, Technologiepark 927, B-9052, Zwijnaarde, Belgium.
- Department of Internal Medicine, Ghent University, B-9000, Ghent, Belgium.
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149
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NLRP3 inflammasome plays a redundant role with caspase 8 to promote IL-1β-mediated osteomyelitis. Proc Natl Acad Sci U S A 2016; 113:4452-7. [PMID: 27071119 DOI: 10.1073/pnas.1601636113] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Missense mutation in the proline-serine-threonine phosphatase-interacting protein 2 (Pstpip2) gene results in the development of spontaneous chronic bone disease characterized by bone deformity and inflammation that is reminiscent of patients with chronic multifocal osteomyelitis (cmo). Interestingly, this disease is specifically mediated by IL-1β but not IL-1α. The precise molecular pathways that promote pathogenic IL-1β production inPstpip2(cmo)mice remain unidentified. Furthermore, how IL-1β provokes inflammatory bone disease inPstpip2(cmo)mice is not known. Here, we demonstrate that double deficiency of Nod like receptor family, pyrin domain containing 3 (NLRP3) and caspase 8 inPstpip2(cmo)mice provides similar protection as observed in caspase-1 and caspase-8-deficientPstpip2(cmo)mice, demonstrating redundant roles for the NLRP3 inflammasome and caspase 8 in provoking osteomyelitic disease inPstpip2(cmo)mice. Consistently, immunofluorescence studies exhibited distinct caspase-1 and caspase-8 puncta in diseasedPtpn6(spin)neutrophils. Data from our chimera studies demonstrated that IL-1β produced by hematopoietic cells is sensed by the radioresistant compartment to promote bone disease. Furthermore, our results showed that the IL-1β signaling is unidirectional and feedback signaling of IL-1β onto the hematopoietic compartment is not important for disease induction. In conclusion, our studies have uncovered the combined actions of the NLRP3 inflammasome and caspase 8 leading to IL-1β maturation and the directionality of IL-1β in driving disease inPstpip2(cmo)mice.
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150
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Huus KE, Joseph J, Zhang L, Wong A, Aaron SD, Mah TF, Sad S. Clinical Isolates of Pseudomonas aeruginosa from Chronically Infected Cystic Fibrosis Patients Fail To Activate the Inflammasome during Both Stable Infection and Pulmonary Exacerbation. THE JOURNAL OF IMMUNOLOGY 2016; 196:3097-108. [PMID: 26895832 DOI: 10.4049/jimmunol.1501642] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 01/20/2016] [Indexed: 12/13/2022]
Abstract
Immune recognition of pathogen-associated ligands leads to assembly and activation of inflammasomes, resulting in the secretion of inflammatory cytokines IL-1β and IL-18 and an inflammatory cell death called pyroptosis. Inflammasomes are important for protection against many pathogens, but their role during chronic infectious disease is poorly understood. Pseudomonas aeruginosa is an opportunistic pathogen that persists in the lungs of cystic fibrosis (CF) patients and may be responsible for the repeated episodes of pulmonary exacerbation characteristic of CF. P. aeruginosa is capable of inducing potent inflammasome activation during acute infection. We hypothesized that to persist within the host during chronic infection, P. aeruginosa must evade inflammasome activation, and pulmonary exacerbations may be the result of restoration of inflammasome activation. We therefore isolated P. aeruginosa from chronically infected CF patients during stable infection and exacerbation and evaluated the impact of these isolates on inflammasome activation in macrophages and neutrophils. P. aeruginosa isolates from CF patients failed to induce inflammasome activation, as measured by the secretion of IL-1β and IL-18 and by pyroptotic cell death, during both stable infection and exacerbation. Inflammasome evasion likely was due to reduced expression of inflammasome ligands and reduced motility and was not observed in environmental isolates or isolates from acute, non-CF infection. These results reveal a novel mechanism of pathogen adaptation by P. aeruginosa to avoid detection by inflammasomes in CF patients and indicate that P. aeruginosa-activated inflammasomes are not involved in CF pulmonary exacerbations.
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Affiliation(s)
- Kelsey E Huus
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada; Department of Biology, Faculty of Science, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Julie Joseph
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Li Zhang
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Alex Wong
- Department of Biology, Faculty of Science, Carleton University, Ottawa, Ontario K1N 6N5, Canada; and
| | - Shawn D Aaron
- Ottawa Hospital Research Institute, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Thien-Fah Mah
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada
| | - Subash Sad
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario K1H 8M5, Canada;
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