51
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Ratner D, Orning MPA, Lien E. Bacterial secretion systems and regulation of inflammasome activation. J Leukoc Biol 2016; 101:165-181. [PMID: 27810946 DOI: 10.1189/jlb.4mr0716-330r] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/19/2016] [Accepted: 09/20/2016] [Indexed: 01/03/2023] Open
Abstract
Innate immunity is critical for host defenses against pathogens, but many bacteria display complex ways of interacting with innate immune signaling, as they may both activate and evade certain pathways. Gram-negative bacteria can exhibit specialized nanomachine secretion systems for delivery of effector proteins into mammalian cells. Bacterial types III, IV, and VI secretion systems (T3SS, T4SS, and T6SS) are known for their impact on caspase-1-activating inflammasomes, necessary for producing bioactive inflammatory cytokines IL-1β and IL-18, key participants of anti-bacterial responses. Here, we discuss how these secretion systems can mediate triggering and inhibition of inflammasome signaling. We propose that a fine balance between secretion system-mediated activation and inhibition can determine net activation of inflammasome activity and control inflammation, clearance, or spread of the infection.
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Affiliation(s)
- Dmitry Ratner
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA; and
| | - M Pontus A Orning
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA; and.,Centre of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norges Teknisk-Naturvitenskapelige Universitet, Trondheim, Norway
| | - Egil Lien
- Program in Innate Immunity, Division of Infectious Diseases and Immunology, Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA; and .,Centre of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norges Teknisk-Naturvitenskapelige Universitet, Trondheim, Norway
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52
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Deviant Behavior: Tick-Borne Pathogens and Inflammasome Signaling. Vet Sci 2016; 3:vetsci3040027. [PMID: 29056735 PMCID: PMC5606592 DOI: 10.3390/vetsci3040027] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 09/22/2016] [Accepted: 09/23/2016] [Indexed: 12/11/2022] Open
Abstract
In the face of an assault, host cells mount an immediate response orchestrated by innate immunity. Two of the best described innate immune signaling networks are the Toll- and the Nod-like receptor pathways. Extensive work has been done characterizing both signaling cascades with several recent advances on the forefront of inflammasome biology. In this review, we will discuss how more commonly-studied pathogens differ from tick-transmitted microbes in the context of Nod-like receptor signaling and inflammasome formation. Because pathogens transmitted by ticks have unique characteristics, we offer the opinion that these microbes can be used to uncover novel principles of Nod-like receptor biology.
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53
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Yang J, Liu Z, Xiao TS. Post-translational regulation of inflammasomes. Cell Mol Immunol 2016; 14:65-79. [PMID: 27345727 PMCID: PMC5214939 DOI: 10.1038/cmi.2016.29] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/05/2016] [Accepted: 05/05/2016] [Indexed: 12/16/2022] Open
Abstract
Inflammasomes play essential roles in immune protection against microbial infections. However, excessive inflammation is implicated in various human diseases, including autoinflammatory syndromes, diabetes, multiple sclerosis, cardiovascular disorders and neurodegenerative diseases. Therefore, precise regulation of inflammasome activities is critical for adequate immune protection while limiting collateral tissue damage. In this review, we focus on the emerging roles of post-translational modifications (PTMs) that regulate activation of the NLRP3, NLRP1, NLRC4, AIM2 and IFI16 inflammasomes. We anticipate that these types of PTMs will be identified in other types of and less well-characterized inflammasomes. Because these highly diverse and versatile PTMs shape distinct inflammatory responses in response to infections and tissue damage, targeting the enzymes involved in these PTMs will undoubtedly offer opportunities for precise modulation of inflammasome activities under various pathophysiological conditions.
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Affiliation(s)
- Jie Yang
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106-7288, USA.,Graduate Program in Physiology and Biophysics, Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH 44106-7288, USA
| | - Zhonghua Liu
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106-7288, USA
| | - Tsan Sam Xiao
- Department of Pathology, Case Western Reserve University, Cleveland, OH 44106-7288, USA
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54
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Abstract
Inflammasomes are multiprotein signalling platforms that control the inflammatory response and coordinate antimicrobial host defences. They are assembled by pattern-recognition receptors following the detection of pathogenic microorganisms and danger signals in the cytosol of host cells, and they activate inflammatory caspases to produce cytokines and to induce pyroptotic cell death. The clinical importance of inflammasomes reaches beyond infectious disease, as dysregulated inflammasome activity is associated with numerous hereditary and acquired inflammatory disorders. In this Review, we discuss the recent developments in inflammasome research with a focus on the molecular mechanisms that govern inflammasome assembly, signalling and regulation.
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Affiliation(s)
- Petr Broz
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
| | - Vishva M Dixit
- Genentech Inc., South San Francisco, California 94080, USA
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55
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Macrophage Apoptosis Triggered by IpaD from Shigella flexneri. Infect Immun 2016; 84:1857-1865. [PMID: 27068089 DOI: 10.1128/iai.01483-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/03/2016] [Indexed: 01/24/2023] Open
Abstract
Shigellosis, a potentially severe bacillary dysentery, is an infectious gastrointestinal disease caused by Shigella spp. Shigella invades the human colonic epithelium and avoids clearance by promoting apoptosis of resident immune cells in the gut. This process is dependent on the Shigella type III secretion system (T3SS), which injects effector proteins into target cells to alter their normal cellular functions. Invasion plasmid antigen D (IpaD) is a structural component that forms a complex at the tip of the T3SS apparatus needle. Recently, IpaD has also been shown to indirectly induce apoptosis in B lymphocytes. In this study, we explored the cytotoxicity profile during macrophage infection by Shigella and discovered that the pathogen induces macrophage cell death independent of caspase-1. Our results demonstrate that IpaD triggers apoptosis in macrophages through activation of host caspases accompanied by mitochondrial disruption. Additionally, we found that the IpaD N-terminal domain is necessary for macrophage killing and SipD, a structural homologue from Salmonella, was found to promote similar cytotoxicity. Together, these findings indicate that IpaD is a contributing factor to macrophage cell death during Shigella infection.
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56
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Zhao Y, Shi J, Shi X, Wang Y, Wang F, Shao F. Genetic functions of the NAIP family of inflammasome receptors for bacterial ligands in mice. J Exp Med 2016; 213:647-56. [PMID: 27114610 PMCID: PMC4854738 DOI: 10.1084/jem.20160006] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/04/2016] [Indexed: 12/03/2022] Open
Abstract
Naip knockout mice provide genetic evidence for the specificity of NAIP1, 2, and 5 in recognizing bacterial T3SS needle protein, rod protein, and flagellin, respectively. Naip1−/−, Naip2−/−, and Naip5−/− mice underscore the physiological contribution of the NAIP proteins in innate defense against cytosolic bacteria. Biochemical studies suggest that the NAIP family of NLR proteins are cytosolic innate receptors that directly recognize bacterial ligands and trigger NLRC4 inflammasome activation. In this study, we generated Naip5−/−, Naip1−/−, and Naip2−/− mice and showed that bone marrow macrophages derived from these knockout mice are specifically deficient in detecting bacterial flagellin, the type III secretion system needle, and the rod protein, respectively. Naip1−/−, Naip2−/−, and Naip5−/− mice also resist lethal inflammasome activation by the corresponding ligand. Furthermore, infections performed in the Naip-deficient macrophages have helped to define the major signal in Legionella pneumophila, Salmonella Typhimurium and Shigella flexneri that is detected by the NAIP/NLRC4 inflammasome. Using an engineered S. Typhimurium infection model, we demonstrate the critical role of NAIPs in clearing bacterial infection and protecting mice from bacterial virulence–induced lethality. These results provide definitive genetic evidence for the important physiological function of NAIPs in antibacterial defense and inflammatory damage–induced lethality in mice.
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Affiliation(s)
- Yue Zhao
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Jianjin Shi
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Xuyan Shi
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Yupeng Wang
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Fengchao Wang
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Feng Shao
- National Institute of Biological Sciences, 102206 Beijing, China Collaborative Innovation Center for Cancer Medicine, National Institute of Biological Sciences, 102206 Beijing, China
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57
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DeLaine BC, Wu T, Grassel CL, Shimanovich A, Pasetti MF, Levine MM, Barry EM. Characterization of a multicomponent live, attenuated Shigella flexneri vaccine. Pathog Dis 2016; 74:ftw034. [PMID: 27106253 DOI: 10.1093/femspd/ftw034] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2016] [Indexed: 11/12/2022] Open
Abstract
Shigella flexneri is a leading cause of diarrheal disease in children under five in developing countries. There is currently no licensed vaccine and broad spectrum protection requires coverage of multiple serotypes. The live attenuated vaccines CVD 1213 and CVD 1215 were derived from two prominent S. flexneri serotypes: S. flexneri 3a and S. flexneri 6. To provide broad-spectrum immunity, they could be combined with CVD 1208S, a S. flexneri 2a strain that demonstrated promising results in phase I and II clinical trials. Each strain contains a mutation in the guaBA operon. These vaccine candidates were tested in vitro and in vivo and were found to be auxotrophic for guanine and defective in intracellular replication, but capable of inducing cytokine production from both epithelial cells and macrophages. Both strains were attenuated for virulence in the guinea pig Serény test and induced robust serotype-specific antibody responses following immunization. Each strain induced homologous serotype protection against challenge and a mixed inoculum of the three S. flexneri vaccines conferred protection against all three virulent wild-type strains. These data support the use of CVD 1213, CVD 1215 and CVD 1208S in a multivalent vaccine to confer broad protection against disease caused by Shigella flexneri.
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Affiliation(s)
- BreOnna C DeLaine
- Institute for Global Health, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Tao Wu
- Institute for Global Health, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Christen L Grassel
- Institute for Global Health, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Avital Shimanovich
- Institute for Global Health, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Marcela F Pasetti
- Institute for Global Health, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Myron M Levine
- Institute for Global Health, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Eileen M Barry
- Institute for Global Health, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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58
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Rauch I, Tenthorey JL, Nichols RD, Al Moussawi K, Kang JJ, Kang C, Kazmierczak BI, Vance RE. NAIP proteins are required for cytosolic detection of specific bacterial ligands in vivo. J Exp Med 2016; 213:657-65. [PMID: 27045008 PMCID: PMC4854734 DOI: 10.1084/jem.20151809] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 03/16/2016] [Indexed: 11/16/2022] Open
Abstract
Vance et al. provide genetic proof for the specificity and essentiality of NAIP proteins for inflammasome responses to specific bacterial ligands in vivo. NLRs (nucleotide-binding domain [NBD] leucine-rich repeat [LRR]–containing proteins) exhibit diverse functions in innate and adaptive immunity. NAIPs (NLR family, apoptosis inhibitory proteins) are NLRs that appear to function as cytosolic immunoreceptors for specific bacterial proteins, including flagellin and the inner rod and needle proteins of bacterial type III secretion systems (T3SSs). Despite strong biochemical evidence implicating NAIPs in specific detection of bacterial ligands, genetic evidence has been lacking. Here we report the use of CRISPR/Cas9 to generate Naip1−/− and Naip2−/− mice, as well as Naip1-6Δ/Δ mice lacking all functional Naip genes. By challenging Naip1−/− or Naip2−/− mice with specific bacterial ligands in vivo, we demonstrate that Naip1 is uniquely required to detect T3SS needle protein and Naip2 is uniquely required to detect T3SS inner rod protein, but neither Naip1 nor Naip2 is required for detection of flagellin. Previously generated Naip5−/− mice retain some residual responsiveness to flagellin in vivo, whereas Naip1-6Δ/Δ mice fail to respond to cytosolic flagellin, consistent with previous biochemical data implicating NAIP6 in flagellin detection. Our results provide genetic evidence that specific NAIP proteins function to detect specific bacterial proteins in vivo.
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Affiliation(s)
- Isabella Rauch
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Jeannette L Tenthorey
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Randilea D Nichols
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Khatoun Al Moussawi
- Department of Medicine, Yale University School of Medicine, New Haven, CT 06510
| | - James J Kang
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720
| | - Chulho Kang
- Cancer Research Laboratory, University of California, Berkeley, Berkeley, CA 94720
| | - Barbara I Kazmierczak
- Department of Medicine, Yale University School of Medicine, New Haven, CT 06510 Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510
| | - Russell E Vance
- Division of Immunology and Pathogenesis, University of California, Berkeley, Berkeley, CA 94720 Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720 Cancer Research Laboratory, University of California, Berkeley, Berkeley, CA 94720
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59
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Killackey SA, Sorbara MT, Girardin SE. Cellular Aspects of Shigella Pathogenesis: Focus on the Manipulation of Host Cell Processes. Front Cell Infect Microbiol 2016; 6:38. [PMID: 27066460 PMCID: PMC4814626 DOI: 10.3389/fcimb.2016.00038] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/17/2016] [Indexed: 01/11/2023] Open
Abstract
Shigella is a Gram-negative bacterium that is responsible for shigellosis. Over the years, the study of Shigella has provided a greater understanding of how the host responds to bacterial infection, and how bacteria have evolved to effectively counter the host defenses. In this review, we provide an update on some of the most recent advances in our understanding of pivotal processes associated with Shigella infection, including the invasion into host cells, the metabolic changes that occur within the bacterium and the infected cell, cell-to-cell spread mechanisms, autophagy and membrane trafficking, inflammatory signaling and cell death. This recent progress sheds a new light into the mechanisms underlying Shigella pathogenesis, and also more generally provides deeper understanding of the complex interplay between host cells and bacterial pathogens in general.
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Affiliation(s)
- Samuel A Killackey
- Department of Laboratory Medicine and Pathobiology, University of Toronto Toronto, ON, Canada
| | | | - Stephen E Girardin
- Department of Laboratory Medicine and Pathobiology, University of TorontoToronto, ON, Canada; Department of Immunology, University of TorontoToronto, ON, Canada
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60
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Martin BN, Wang C, Zhang CJ, Kang Z, Gulen MF, Zepp JA, Zhao J, Bian G, Do JS, Min B, Pavicic PG, El-Sanadi C, Fox PL, Akitsu A, Iwakura Y, Sarkar A, Wewers MD, Kaiser WJ, Mocarski ES, Rothenberg ME, Hise AG, Dubyak GR, Ransohoff RM, Li X. T cell-intrinsic ASC critically promotes T(H)17-mediated experimental autoimmune encephalomyelitis. Nat Immunol 2016; 17:583-92. [PMID: 26998763 DOI: 10.1038/ni.3389] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/22/2015] [Indexed: 02/07/2023]
Abstract
Interleukin 1β (IL-1β) is critical for the in vivo survival, expansion and effector function of IL-17-producing helper T (T(H)17) cells during autoimmune responses, including experimental autoimmune encephalomyelitis (EAE). However, the spatiotemporal role and cellular source of IL-1β during EAE pathogenesis are poorly defined. In the present study, we uncovered a T cell-intrinsic inflammasome that drives IL-1β production during T(H)17-mediated EAE pathogenesis. Activation of T cell antigen receptors induced expression of pro-IL-1β, whereas ATP stimulation triggered T cell production of IL-1β via ASC-NLRP3-dependent caspase-8 activation. IL-1R was detected on T(H)17 cells but not on type 1 helper T (T(H)1) cells, and ATP-treated T(H)17 cells showed enhanced survival compared with ATP-treated T(H)1 cells, suggesting autocrine action of T(H)17-derived IL-1β. Together these data reveal a critical role for IL-1β produced by a T(H)17 cell-intrinsic ASC-NLRP3-caspase-8 inflammasome during inflammation of the central nervous system.
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Affiliation(s)
- Bradley N Martin
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA.,Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Chenhui Wang
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA.,Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Cun-jin Zhang
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA.,Department of Neurology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, China.,Department of Immunology, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, China
| | - Zizhen Kang
- Shanghai Institute of Immunology, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Muhammet Fatih Gulen
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Jarod A Zepp
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Junjie Zhao
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Guanglin Bian
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Jeong-su Do
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Booki Min
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Paul G Pavicic
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Caroline El-Sanadi
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Paul L Fox
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Aoi Akitsu
- Research Institute for Biomedical Sciences, Tokyo University of Science, Yamazaki, Noda, Japan
| | - Yoichiro Iwakura
- Research Institute for Biomedical Sciences, Tokyo University of Science, Yamazaki, Noda, Japan
| | - Anasuya Sarkar
- Davis Heart and Lung Research Institute, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - Mark D Wewers
- Davis Heart and Lung Research Institute, Ohio State University College of Medicine, Columbus, Ohio, USA
| | - William J Kaiser
- Department of Microbiology and Immunology, Emory Vaccine Center, Atlanta, Georgia, USA
| | - Edward S Mocarski
- Department of Microbiology and Immunology, Emory Vaccine Center, Atlanta, Georgia, USA
| | - Marc E Rothenberg
- Division of Allergy and Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
| | - Amy G Hise
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio, USA
| | - George R Dubyak
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Richard M Ransohoff
- Department of Neurosciences, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
| | - Xiaoxia Li
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio, USA
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61
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Zhao Y, Shao F. The NAIP-NLRC4 inflammasome in innate immune detection of bacterial flagellin and type III secretion apparatus. Immunol Rev 2016; 265:85-102. [PMID: 25879286 DOI: 10.1111/imr.12293] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bacterial flagella and type III secretion system (T3SS) are evolutionarily related molecular transport machineries. Flagella mediate bacterial motility; the T3SS delivers virulence effectors to block host defenses. The inflammasome is a cytosolic multi-protein complex that activates caspase-1. Active caspase-1 triggers interleukin-1β (IL-1β)/IL-18 maturation and macrophage pyroptotic death to mount an inflammatory response. Central to the inflammasome is a pattern recognition receptor that activates caspase-1 either directly or through an adapter protein. Studies in the past 10 years have established a NAIP-NLRC4 inflammasome, in which NAIPs are cytosolic receptors for bacterial flagellin and T3SS rod/needle proteins, while NLRC4 acts as an adapter for caspase-1 activation. Given the wide presence of flagella and the T3SS in bacteria, the NAIP-NLRC4 inflammasome plays a critical role in anti-bacteria defenses. Here, we review the discovery of the NAIP-NLRC4 inflammasome and further discuss recent advances related to its biochemical mechanism and biological function as well as its connection to human autoinflammatory disease.
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Affiliation(s)
- Yue Zhao
- National Institute of Biological Sciences, Beijing, China
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62
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Abstract
Inflammasome biology is one of the most exciting and rapidly growing areas in immunology. Over the past 10 years, inflammasomes have been recognized for their roles in the host defense against invading pathogens and in the development of cancer, auto-inflammatory, metabolic, and neurodegenerative diseases. Assembly of an inflammasome complex requires cytosolic sensing of pathogen-associated molecular patterns or danger-associated molecular patterns by a nucleotide-binding domain and leucine-rich repeat receptor (NLR) or absent in melanoma 2 (AIM2)-like receptors (ALR). NLRs and ALRs engage caspase-1, in most cases requiring the adapter protein apoptosis-associated speck-like protein containing a CARD (ASC), to catalyze proteolytic cleavage of pro-interleukin-1β (pro-IL-1β) and pro-IL-18 and drive pyroptosis. Recent studies indicate that caspase-8, caspase-11, IL-1R-associated kinases (IRAK), and receptor-interacting protein (RIP) kinases contribute to inflammasome functions. In addition, post-translational modifications, including ubiquitination, deubiquitination, phosphorylation, and degradation control almost every aspect of inflammasome activities. Genetic studies indicate that mutations in NLRP1, NLRP3, NLRC4, and AIM2 are linked with the development of auto-inflammatory diseases, enterocolitis, and cancer. Overall, these findings transform our understanding of the basic biology and clinical relevance of inflammasomes. In this review, we provide an overview of the latest development of inflammasome research and discuss how inflammasome activities govern health and disease.
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Affiliation(s)
- Si Ming Man
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
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63
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Jorgensen I, Miao EA. Pyroptotic cell death defends against intracellular pathogens. Immunol Rev 2016; 265:130-42. [PMID: 25879289 DOI: 10.1111/imr.12287] [Citation(s) in RCA: 732] [Impact Index Per Article: 91.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Inflammatory caspases play a central role in innate immunity by responding to cytosolic signals and initiating a twofold response. First, caspase-1 induces the activation and secretion of the two prominent pro-inflammatory cytokines, interleukin-1β (IL-1β) and IL-18. Second, either caspase-1 or caspase-11 can trigger a form of lytic, programmed cell death called pyroptosis. Pyroptosis operates to remove the replication niche of intracellular pathogens, making them susceptible to phagocytosis and killing by a secondary phagocyte. However, aberrant, systemic activation of pyroptosis in vivo may contribute to sepsis. Emphasizing the efficiency of inflammasome detection of microbial infections, many pathogens have evolved to avoid or subvert pyroptosis. This review focuses on molecular and morphological characteristics of pyroptosis and the individual inflammasomes and their contribution to defense against infection in mice and humans.
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Affiliation(s)
- Ine Jorgensen
- Department of Microbiology and Immunology, Center for Gastrointestinal Biology and Disease, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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64
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Ashida H, Sasakawa C. Shigella IpaH Family Effectors as a Versatile Model for Studying Pathogenic Bacteria. Front Cell Infect Microbiol 2016; 5:100. [PMID: 26779450 PMCID: PMC4701945 DOI: 10.3389/fcimb.2015.00100] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 12/14/2015] [Indexed: 02/03/2023] Open
Abstract
Shigella spp. are highly adapted human pathogens that cause bacillary dysentery (shigellosis). Via the type III secretion system (T3SS), Shigella deliver a subset of virulence proteins (effectors) that are responsible for pathogenesis, with functions including pyroptosis, invasion of the epithelial cells, intracellular survival, and evasion of host immune responses. Intriguingly, T3SS effector activity and strategies are not unique to Shigella, but are shared by many other bacterial pathogens, including Salmonella, Yersinia, and enteropathogenic Escherichia coli (EPEC). Therefore, studying Shigella T3SS effectors will not only improve our understanding of bacterial infection systems, but also provide a molecular basis for developing live bacterial vaccines and antibacterial drugs. One of Shigella T3SS effectors, IpaH family proteins, which have E3 ubiquitin ligase activity and are widely conserved among other bacterial pathogens, are very relevant because they promote bacterial survival by triggering cell death and modulating the host immune responses. Here, we describe selected examples of Shigella pathogenesis, with particular emphasis on the roles of IpaH family effectors, which shed new light on bacterial survival strategies and provide clues about how to overcome bacterial infections.
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Affiliation(s)
- Hiroshi Ashida
- Division of Bacterial Infection Biology, Institute of Medical Science, University of Tokyo Tokyo, Japan
| | - Chihiro Sasakawa
- Division of Bacterial Infection Biology, Institute of Medical Science, University of TokyoTokyo, Japan; Nippon Institute for Biological ScienceTokyo, Japan; Medical Mycology Research Center, Chiba UniversityChiba, Japan
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65
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Abstract
The complementary actions of the innate and adaptive immune systems often provide effective host defense against microbial pathogens and harmful environmental agents. Germline-encoded pattern recognition receptors (PRRs) endow the innate immune system with the ability to detect and mount a rapid response against a given threat. Members of several intracellular PRR families, including the nucleotide-binding domain and leucine-rich repeat containing receptors (NLRs), the AIM2-like receptors (ALRs), and the tripartite motif-containing (TRIM) protein Pyrin/TRIM20, nucleate the formation of inflammasomes. These cytosolic scaffolds serve to recruit and oligomerize the cysteine protease caspase-1 in filaments that promote its proximity-induced autoactivation. This oligomerization occurs either directly or indirectly through intervention of the bipartite adaptor protein ASC, apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD), which is needed for the domain interaction. Caspase-1 cleaves the precursors of the inflammatory cytokines interleukin (IL)-1β and IL-18 and triggers their release into the extracellular space, where they act on effector cells to promote both local and systemic immune responses. Additionally, inflammasome activation gives rise to a lytic mode of cell death, named pyroptosis, which is thought to contribute to initial host defense against infection by eliminating replication niches of intracellular pathogens and exposing them to the immune system. Inflammasome-induced host defense responses are the subject of intense investigation, and understanding their physiological roles during infection and the regulatory circuits that are involved is becoming increasingly detailed. Here, we discuss current understanding of the activation mechanisms and biological outcomes of inflammasome activation.
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Affiliation(s)
- Hanne Dubois
- NOD-like Receptor and Inflammasome Laboratory, Inflammation Research Center, VIB, 9052, Zwijnaarde, Belgium.,Department of Internal Medicine, Ghent University, 9000, Ghent, Belgium
| | - Andy Wullaert
- NOD-like Receptor and Inflammasome Laboratory, Inflammation Research Center, VIB, 9052, Zwijnaarde, Belgium.,Department of Internal Medicine, Ghent University, 9000, Ghent, Belgium
| | - Mohamed Lamkanfi
- NOD-like Receptor and Inflammasome Laboratory, Inflammation Research Center, VIB, 9052, Zwijnaarde, Belgium. .,Department of Internal Medicine, Ghent University, 9000, Ghent, Belgium.
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The Orchestra and Its Maestro: Shigella's Fine-Tuning of the Inflammasome Platforms. Curr Top Microbiol Immunol 2016; 397:91-115. [PMID: 27460806 DOI: 10.1007/978-3-319-41171-2_5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Shigella spp. are the causative agents of bacillary dysentery, leading to extensive mortality and morbidity worldwide. These facultative intracellular bacteria invade the epithelium of the colon and the rectum, inducing a severe inflammatory response from which the symptoms of the disease originate. Shigella are human pathogens able to manipulate and subvert the innate immune system surveillance. Shigella dampens inflammasome activation in epithelial cells. In infected macrophages, inflammasome activation and IL-1β and IL-18 release lead to massive neutrophil recruitment and greatly contribute to inflammation. Here, we describe how Shigella hijacks and finely tunes inflammasome activation in the different cell populations involved in pathogenesis: epithelial cells, macrophages, neutrophils, DCs, and B and T lymphocytes. Shigella emerges as a "sly" pathogen that switches on/off the inflammasome mechanisms in order to optimize the interaction with the host and establish a successful infection.
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67
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Bryant CE, Orr S, Ferguson B, Symmons MF, Boyle JP, Monie TP. International Union of Basic and Clinical Pharmacology. XCVI. Pattern recognition receptors in health and disease. Pharmacol Rev 2015; 67:462-504. [PMID: 25829385 DOI: 10.1124/pr.114.009928] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Since the discovery of Toll, in the fruit fly Drosophila melanogaster, as the first described pattern recognition receptor (PRR) in 1996, many families of these receptors have been discovered and characterized. PRRs play critically important roles in pathogen recognition to initiate innate immune responses that ultimately link to the generation of adaptive immunity. Activation of PRRs leads to the induction of immune and inflammatory genes, including proinflammatory cytokines and chemokines. It is increasingly clear that many PRRs are linked to a range of inflammatory, infectious, immune, and chronic degenerative diseases. Several drugs to modulate PRR activity are already in clinical trials and many more are likely to appear in the near future. Here, we review the different families of mammalian PRRs, the ligands they recognize, the mechanisms of activation, their role in disease, and the potential of targeting these proteins to develop the anti-inflammatory therapeutics of the future.
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Affiliation(s)
- Clare E Bryant
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Selinda Orr
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Brian Ferguson
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Martyn F Symmons
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Joseph P Boyle
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
| | - Tom P Monie
- Departments of Veterinary Medicine (C.E.B., J.P.B., T.P.M.), Pathology (B.F.), and Biochemistry (M.F.S., J.P.B.), University of Cambridge, Cambridge, United Kingdom; and Institute of Infection and Immunity, Cardiff University, Cardiff, United Kingdom (S.O.)
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68
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Sanchez-Villamil J, Navarro-Garcia F. Role of virulence factors on host inflammatory response induced by diarrheagenic Escherichia coli pathotypes. Future Microbiol 2015; 10:1009-33. [DOI: 10.2217/fmb.15.17] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
ABSTRACT Pathogens are able to breach the intestinal barrier, and different bacterial species can display different abilities to colonize hosts and induce inflammation. Inflammatory response studies induced by enteropathogens as Escherichia coli are interesting since it has acquired diverse genetic mobile elements, leading to different E. coli pathotypes. Diarrheagenic E. coli secrete toxins, effectors and virulence factors that exploit the host cell functions to facilitate the bacterial colonization. Many bacterial proteins are delivered to the host cell for subverting the inflammatory response. Hereby, we have highlighted the specific processes used by E. coli pathotypes, by that subvert the inflammatory pathways. These mechanisms include an arrangement of pro- and anti-inflammatory responses to favor the appropriate environmental niche for the bacterial survival and growth.
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Affiliation(s)
- Javier Sanchez-Villamil
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Ap. Postal 14–740, 07000, México DF, Mexico
| | - Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Ap. Postal 14–740, 07000, México DF, Mexico
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Ashida H, Mimuro H, Sasakawa C. Shigella manipulates host immune responses by delivering effector proteins with specific roles. Front Immunol 2015; 6:219. [PMID: 25999954 PMCID: PMC4423471 DOI: 10.3389/fimmu.2015.00219] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2015] [Accepted: 04/22/2015] [Indexed: 11/30/2022] Open
Abstract
The intestinal epithelium deploys multiple defense systems against microbial infection to sense bacterial components and danger alarms, as well as to induce intracellular signal transduction cascades that trigger both the innate and the adaptive immune systems, which are pivotal for bacterial elimination. However, many enteric bacterial pathogens, including Shigella, deliver a subset of virulence proteins (effectors) via the type III secretion system (T3SS) that enable bacterial evasion from host immune systems; consequently, these pathogens are able to efficiently colonize the intestinal epithelium. In this review, we present and select recently discovered examples of interactions between Shigella and host immune responses, with particular emphasis on strategies that bacteria use to manipulate inflammatory outputs of host-cell responses such as cell death, membrane trafficking, and innate and adaptive immune responses.
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Affiliation(s)
- Hiroshi Ashida
- Division of Bacterial Infection Biology, Institute of Medical Science, University of Tokyo , Tokyo , Japan
| | - Hitomi Mimuro
- Division of Bacteriology, Department of Infectious Diseases Control, International Research Center for Infectious Diseases, The Institute of Medical Science, University of Tokyo , Tokyo , Japan
| | - Chihiro Sasakawa
- Division of Bacterial Infection Biology, Institute of Medical Science, University of Tokyo , Tokyo , Japan ; Nippon Institute for Biological Science , Tokyo , Japan ; Medical Mycology Research Center, Chiba University , Chiba , Japan
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70
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Shin S, Brodsky IE. The inflammasome: Learning from bacterial evasion strategies. Semin Immunol 2015; 27:102-10. [PMID: 25914126 DOI: 10.1016/j.smim.2015.03.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 03/12/2015] [Indexed: 01/01/2023]
Abstract
The innate immune system plays a critical role in defense against microbial infection and employs germline-encoded pattern recognition receptors to detect broadly conserved microbial structures or activities. Pattern recognition receptors of the nucleotide binding domain/leucine rich repeat (NLR) family respond to particular microbial products or disruption of cellular physiology, and mediate the activation of an arm of the innate immune response termed the inflammasome. Inflammasomes are multiprotein complexes that are inducibly assembled in response to the contamination of the host cell cytosol by microbial products. Individual NLRs sense the presence of their cognate stimuli, and initiate assembly of inflammasomes via the adaptor protein apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) and the effector pro-enzyme caspase-1. Inflammasome activation leads to rapid release of pro-inflammatory mediators of the IL-1 family as well as the release of intracellular alarmins due to a lytic form of programmed cell death termed pyroptosis. Over the past 15 years, a great deal has been learned about the mechanisms that drive inflammasome activation in response to infection by diverse pathogens. However, pathogens have also evolved mechanisms to evade or suppress host defenses, and the mechanisms by which pathogens evade inflammasome activation are not well-understood. Here, we will discuss emerging evidence on how diverse pathogens evade inflammasome activation, and what these studies have revealed about inflammasome biology. Deeper understanding of pathogen evasion of inflammasome activation has the potential to lead to development of novel classes of immunomodulatory factors that could be used in the context of human inflammatory diseases.
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Affiliation(s)
- Sunny Shin
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Igor E Brodsky
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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71
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Sellge G, Kufer TA. PRR-signaling pathways: Learning from microbial tactics. Semin Immunol 2015; 27:75-84. [PMID: 25911384 DOI: 10.1016/j.smim.2015.03.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Accepted: 03/13/2015] [Indexed: 12/13/2022]
Abstract
Recognition of bacterial pathogens by the mammalian host relies on the induction of early innate immune responses initiated by the activation of pattern-recognition receptors (PRRs) upon sensing of their cognate microbe-associated-patterns (MAMPs). Successful pathogens have evolved to intercept PRR activation and signaling at multiple steps. The molecular dissection of the underlying mechanisms revealed many of the basic mechanisms used by the immune system. Here we provide an overview of the different strategies used by bacterial pathogens and commensals to subvert and reprogram PPR-mediated innate immune responses. A particular attention is given to recent discoveries highlighting novel molecular details of the host inflammatory response in mammalian cells and current advances in our understanding of the interaction of commensals with PRR-mediated responses.
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Affiliation(s)
- Gernot Sellge
- Department of Medicine III, University Hospital Aachen, Pauwelsstraße 30, 52074 Aachen, Germany
| | - Thomas A Kufer
- Institute of Nutritional Medicine, Department of Immunology, University of Hohenheim, Fruwirthstr. 12, 70599 Stuttgart, Germany.
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72
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Vance RE. The NAIP/NLRC4 inflammasomes. Curr Opin Immunol 2015; 32:84-9. [PMID: 25621709 PMCID: PMC4336817 DOI: 10.1016/j.coi.2015.01.010] [Citation(s) in RCA: 148] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/07/2015] [Accepted: 01/13/2015] [Indexed: 01/15/2023]
Abstract
Inflammasomes comprise a family of cytosolic multi-protein complexes that sense infection, or other threats, and initiate inflammation via the recruitment and activation of the Caspase-1 protease. Although the precise molecular mechanism by which most inflammasomes are activated remains a subject of considerable debate, the NAIP/NLRC4 subfamily of inflammasomes is increasingly well understood. A crystal structure of NLRC4 was recently reported, and a domain in NAIPs that recognizes bacterial ligands was identified. In addition, gain-of-function mutations in NLRC4 have been shown to cause an auto-inflammatory syndrome in humans. Lastly, the NAIP/NLRC4 inflammasome has been shown to provide a novel form of cell intrinsic defense against Salmonella infection, involving expulsion of infected cells from the intestinal epithelium.
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Affiliation(s)
- Russell E Vance
- Howard Hughes Medical Institute, United States; Department of Molecular and Cell Biology, United States; Cancer Research Laboratory, University of California, Berkeley, Berkeley, CA 94720, United States.
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73
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Abstract
: Inflammasomes are multiprotein complexes that process procytokines into mature forms of interleukin 1β and interleukin 18 and induce pyroptotic cell death. Evidence linking NLRP3, NLRC4, and NLRP6 inflammasomes to intestinal inflammation is reviewed to provide a basis to understand how the innate immune system discriminates pathogenic bacteria from commensal bacteria and shapes microbial ecology. Inflammasomes have a direct and important role limiting colitis by directing effective immune responses against pathogenic bacterial infections in the intestine. Chronic granulomatous disease is presented to reveal a contrasting proinflammatory effect of inflammasomes. This pathogenic effect is unmasked in a state of immunodeficiency where bacterial growth is poorly controlled increasing inflammasome activity. The role of inflammasomes in inflammation associated with Crohn's disease and ulcerative colitis is discussed. Finally, mechanistic studies linking genetic polymorphisms in ATG16L and NOD2 to inflammasome activation provide a basis for new hypotheses to explain how genetic polymorphism associated with Crohn's disease modulate intestinal inflammation. A deeper understanding of the role of inflammasomes in intestinal inflammation is expected to identify new ways of treating inflammatory bowel disease.
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74
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Ashida H, Kim M, Sasakawa C. Manipulation of the host cell death pathway by Shigella. Cell Microbiol 2014; 16:1757-66. [PMID: 25264025 DOI: 10.1111/cmi.12367] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 08/11/2014] [Accepted: 08/21/2014] [Indexed: 12/25/2022]
Abstract
Host cells deploy multiple defences against microbial infection. One prominent host defence mechanism, the death of infected cells, plays a pivotal role in clearing damaged cells, eliminating pathogens, removing replicative niches, exposing intracellular bacterial pathogens to extracellular immune surveillance and presenting bacteria-derived antigens to the adaptive immune system. Although cell death can occur under either physiological or pathophysiological conditions, it acts as an innate defence mechanism against bacterial pathogens by limiting their persistent colonization. However, many bacterial pathogens, including Shigella, have evolved mechanisms that manipulate host cell death for their own benefit.
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Affiliation(s)
- Hiroshi Ashida
- Division of Bacterial Infection Biology, Institute of Medical Science, University of Tokyo, Tokyo, 108-8639, Japan
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75
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Maltez VI, Miao EA. NAIP inflammasomes give the NOD to bacterial ligands. Trends Immunol 2014; 35:503-4. [PMID: 25443492 DOI: 10.1016/j.it.2014.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 10/06/2014] [Indexed: 12/30/2022]
Abstract
NLRs are innate immune sensors that monitor the sanctity of the cytosolic compartment. In a recent paper in Molecular Cell, Tenthorey et al. reveal a novel ligand-sensing interface within regions of the oligomerization domain of the NAIPs, rather than within the leucine-rich repeats, as was anticipated.
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Affiliation(s)
- Vivien I Maltez
- Department of Microbiology and Immunology, Center for Gastrointestinal Biology and Disease, and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Edward A Miao
- Department of Microbiology and Immunology, Center for Gastrointestinal Biology and Disease, and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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76
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Shigella IpaH7.8 E3 ubiquitin ligase targets glomulin and activates inflammasomes to demolish macrophages. Proc Natl Acad Sci U S A 2014; 111:E4254-63. [PMID: 25246571 DOI: 10.1073/pnas.1324021111] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
When nucleotide-binding oligomerization domain-like receptors (NLRs) sense cytosolic-invading bacteria, they induce the formation of inflammasomes and initiate an innate immune response. In quiescent cells, inflammasome activity is tightly regulated to prevent excess inflammation and cell death. Many bacterial pathogens provoke inflammasome activity and induce inflammatory responses, including cell death, by delivering type III secreted effectors, the rod component flagellin, and toxins. Recent studies indicated that Shigella deploy multiple mechanisms to stimulate NLR inflammasomes through type III secretion during infection. Here, we show that Shigella induces rapid macrophage cell death by delivering the invasion plasmid antigen H7.8 (IpaH7.8) enzyme 3 (E3) ubiquitin ligase effector via the type III secretion system, thereby activating the NLR family pyrin domain-containing 3 (NLRP3) and NLR family CARD domain-containing 4 (NLRC4) inflammasomes and caspase-1 and leading to macrophage cell death in an IpaH7.8 E3 ligase-dependent manner. Mice infected with Shigella possessing IpaH7.8, but not with Shigella possessing an IpaH7.8 E3 ligase-null mutant, exhibited enhanced bacterial multiplication. We defined glomulin/flagellar-associated protein 68 (GLMN) as an IpaH7.8 target involved in IpaH7.8 E3 ligase-dependent inflammasome activation. This protein originally was identified through its association with glomuvenous malformations and more recently was described as a member of a Cullin ring ligase inhibitor. Modifying GLMN levels through overexpression or knockdown led to reduced or augmented inflammasome activation, respectively. Macrophages stimulated with lipopolysaccharide/ATP induced GLMN puncta that localized with the active form of caspase-1. Macrophages from GLMN(+/-) mice were more responsive to inflammasome activation than those from GLMN(+/+) mice. Together, these results highlight a unique bacterial adaptation that hijacks inflammasome activation via interactions between IpaH7.8 and GLMN.
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77
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Barbé F, Douglas T, Saleh M. Advances in Nod-like receptors (NLR) biology. Cytokine Growth Factor Rev 2014; 25:681-97. [PMID: 25070125 DOI: 10.1016/j.cytogfr.2014.07.001] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 07/03/2014] [Indexed: 12/27/2022]
Abstract
The innate immune system is composed of a wide repertoire of conserved pattern recognition receptors (PRRs) able to trigger inflammation and host defense mechanisms in response to endogenous or exogenous pathogenic insults. Among these, nucleotide-binding and oligomerization domain (NOD)-like receptors (NLRs) are intracellular sentinels of cytosolic sanctity capable of orchestrating innate immunity and inflammatory responses following the perception of noxious signals within the cell. In this review, we elaborate on recent advances in the signaling mechanisms of NLRs, operating within inflammasomes or through alternative inflammatory pathways, and discuss the spectrum of their effector functions in innate immunity. We describe the progressive characterization of each NLR with associated controversies and cutting edge discoveries.
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Affiliation(s)
- François Barbé
- Department of Microbiology and Immunology, McGill University, Montréal, Québec H3A 2B4, Canada
| | - Todd Douglas
- Department of Microbiology and Immunology, McGill University, Montréal, Québec H3A 2B4, Canada
| | - Maya Saleh
- Department of Microbiology and Immunology, McGill University, Montréal, Québec H3A 2B4, Canada; Department of Medicine, McGill University, Montréal, Québec H3G 0B1, Canada.
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78
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Zipfel C. Plant pattern-recognition receptors. Trends Immunol 2014; 35:345-51. [DOI: 10.1016/j.it.2014.05.004] [Citation(s) in RCA: 645] [Impact Index Per Article: 64.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 05/17/2014] [Accepted: 05/21/2014] [Indexed: 12/18/2022]
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