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Liao Y, Chen X, Miller‐Little W, Wang H, Willard B, Bulek K, Zhao J, Li X. The Ras GTPase-activating-like protein IQGAP1 bridges Gasdermin D to the ESCRT system to promote IL-1β release via exosomes. EMBO J 2022; 42:e110780. [PMID: 36373462 PMCID: PMC9811620 DOI: 10.15252/embj.2022110780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 09/23/2022] [Accepted: 10/18/2022] [Indexed: 11/16/2022] Open
Abstract
IL-1β can exit the cytosol as an exosomal cargo following inflammasome activation in intestinal epithelial cells (IECs) in a Gasdermin D (GSDMD)-dependent manner. The mechanistic connection linking inflammasome activation and the biogenesis of exosomes has so far remained largely elusive. Here, we report the Ras GTPase-activating-like protein IQGAP1 functions as an adaptor, bridging GSDMD to the endosomal sorting complexes required for transport (ESCRT) machinery to promote the biogenesis of pro-IL-1β-containing exosomes in response to NLPR3 inflammasome activation. We identified IQGAP1 as a GSDMD-interacting protein through a non-biased proteomic analysis. Functional investigation indicated the IQGAP1-GSDMD interaction is required for LPS and ATP-induced exosome release. Further analysis revealed that IQGAP1 serves as an adaptor which bridges GSDMD and associated IL-1β complex to Tsg101, a component of the ESCRT complex, and enables the packaging of GSDMD and IL-1β into exosomes. Importantly, this process is dependent on an LPS-induced increase in GTP-bound CDC42, a small GTPase known to activate IQGAP1. Taken together, this study reveals IQGAP1 as a link between inflammasome activation and GSDMD-dependent, ESCRT-mediated exosomal release of IL-1β.
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Affiliation(s)
- Yun Liao
- Department of Inflammation and ImmunityCleveland Clinic Lerner Research InstituteClevelandOHUSA
| | - Xing Chen
- Department of Inflammation and ImmunityCleveland Clinic Lerner Research InstituteClevelandOHUSA
| | - William Miller‐Little
- Department of Inflammation and ImmunityCleveland Clinic Lerner Research InstituteClevelandOHUSA
| | - Han Wang
- Department of Inflammation and ImmunityCleveland Clinic Lerner Research InstituteClevelandOHUSA
| | - Belinda Willard
- Proteomics and Metabolomics CoreCleveland Clinic Lerner Research InstituteClevelandOHUSA
| | - Katarzyna Bulek
- Department of Inflammation and ImmunityCleveland Clinic Lerner Research InstituteClevelandOHUSA
| | - Junjie Zhao
- Department of Inflammation and ImmunityCleveland Clinic Lerner Research InstituteClevelandOHUSA
| | - Xiaoxia Li
- Department of Inflammation and ImmunityCleveland Clinic Lerner Research InstituteClevelandOHUSA
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Alam J, Yazdanpanah G, Ratnapriya R, Borcherding N, de Paiva CS, Li D, Guimaraes de Souza R, Yu Z, Pflugfelder SC. IL-17 Producing Lymphocytes Cause Dry Eye and Corneal Disease With Aging in RXRα Mutant Mouse. Front Med (Lausanne) 2022; 9:849990. [PMID: 35402439 PMCID: PMC8983848 DOI: 10.3389/fmed.2022.849990] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 02/24/2022] [Indexed: 11/22/2022] Open
Abstract
Purpose To investigate IL-17 related mechanisms for developing dry eye disease in the Pinkie mouse strain with a loss of function RXRα mutation. Methods Measures of dry eye disease were assessed in the cornea and conjunctiva. Expression profiling was performed by single-cell RNA sequencing (scRNA-seq) to compare gene expression in conjunctival immune cells. Conjunctival immune cells were immunophenotyped by flow cytometry and confocal microscopy. The activity of RXRα ligand 9-cis retinoic acid (RA) was evaluated in cultured monocytes and γδ T cells. Results Compared to wild type (WT) C57BL/6, Pinkie has increased signs of dry eye disease, including decreased tear volume, corneal barrier disruption, corneal/conjunctival cornification and goblet cell loss, and corneal vascularization, opacification, and ulceration with aging. ScRNA-seq of conjunctival immune cells identified γδ T cells as the predominant IL-17 expressing population in both strains and there is a 4-fold increased percentage of γδ T cells in Pinkie. Compared to WT, IL-17a, and IL-17f significantly increased in Pinkie with conventional T cells and γδ T cells as the major producers. Flow cytometry revealed an increased number of IL-17+ γδ T cells in Pinkie. Tear concentration of the IL-17 inducer IL-23 is significantly higher in Pinkie. 9-cis RA treatment suppresses stimulated IL-17 production by γδ T and stimulatory activity of monocyte supernatant on γδ T cell IL-17 production. Compared to WT bone marrow chimeras, Pinkie chimeras have increased IL-17+ γδ T cells in the conjunctiva after desiccating stress and anti-IL-17 treatment suppresses dry eye induced corneal MMP-9 production/activity and conjunctival goblet cell loss. Conclusion These findings indicate that RXRα suppresses generation of dry eye disease-inducing IL-17 producing lymphocytes s in the conjunctiva and identifies RXRα as a potential therapeutic target in dry eye.
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Affiliation(s)
- Jehan Alam
- Department of Ophthalmology, Ocular Surface Center, Baylor College of Medicine, Houston, TX, United States
| | - Ghasem Yazdanpanah
- Department of Ophthalmology, Ocular Surface Center, Baylor College of Medicine, Houston, TX, United States
| | - Rinki Ratnapriya
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | - Nicholas Borcherding
- Department of Pathology, Washington University School of Medicine, St. Louis, MO, United States
| | - Cintia S. de Paiva
- Department of Ophthalmology, Ocular Surface Center, Baylor College of Medicine, Houston, TX, United States
| | - DeQuan Li
- Department of Ophthalmology, Ocular Surface Center, Baylor College of Medicine, Houston, TX, United States
| | - Rodrigo Guimaraes de Souza
- Department of Ophthalmology, Ocular Surface Center, Baylor College of Medicine, Houston, TX, United States
- Department of Ophthalmology, University of São Paulo, São Paulo, Brazil
| | - Zhiyuan Yu
- Department of Ophthalmology, Ocular Surface Center, Baylor College of Medicine, Houston, TX, United States
| | - Stephen C. Pflugfelder
- Department of Ophthalmology, Ocular Surface Center, Baylor College of Medicine, Houston, TX, United States
- *Correspondence: Stephen C. Pflugfelder
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Zhang Y, Rong H, Zhang FX, Wu K, Mu L, Meng J, Xiao B, Zamponi GW, Shi Y. A Membrane Potential- and Calpain-Dependent Reversal of Caspase-1 Inhibition Regulates Canonical NLRP3 Inflammasome. Cell Rep 2020; 24:2356-2369.e5. [PMID: 30157429 PMCID: PMC6201321 DOI: 10.1016/j.celrep.2018.07.098] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 06/06/2018] [Accepted: 07/27/2018] [Indexed: 02/06/2023] Open
Abstract
The NLRP3 inflammasome senses a range of cellular disturbances, although no consensus exists regarding a common mechanism. Canonical NLRP3 activation is blocked by high extracellular K+, regardless of the activating signal. We report here that canonical NLRP3 activation leads to Ca2+ flux and increased calpain activity. Activated calpain releases a pool of Caspase-1 sequestered by the cytoskeleton to regulate NLRP3 activation. Using electrophysiological recording, we found that resting-state eukaryotic membrane potential (MP) is required for this calpain activity, and depolarization by high extracellular K+ or artificial hyperpolarization results in the inhibition of calpain. Therefore, the MP/Ca2+/calpain/ Caspase-1 axis acts as an independent regulatory mechanism for NLRP3 activity. This finding provides mechanistic insight into high K+-mediated inhibition of NLRP3 activation, and it offers an alternative model of NLRP3 inflammasome activation that does not involve K+ efflux. Zhang et al. find that, in canonical NLRP inflammasome activation, calpain activity is essential for releasing caspase-1 from flightless-1 and the cytoskeleton. Membrane depolarization, such as under high extracellular K+ or hyperpolarization, impairs this activity. This work provides insight into extracellular K+ -mediated inhibition of the NLRP3 inflammasome.
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Affiliation(s)
- Yifei Zhang
- Institute for Immunology, Department of Basic Medical Sciences, School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Hua Rong
- Institute for Immunology, Department of Basic Medical Sciences, School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Fang-Xiong Zhang
- Department of Physiology and Pharmacology, Cumming School of Medicine and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Kun Wu
- School of Pharmaceutical Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Libing Mu
- Institute for Immunology, Department of Basic Medical Sciences, School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Junchen Meng
- Institute for Immunology, Department of Basic Medical Sciences, School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China
| | - Bailong Xiao
- School of Pharmaceutical Sciences, Tsinghua-Peking Joint Center for Life Sciences, IDG/McGovern Institute for Brain Research, Tsinghua University, Beijing 100084, China
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB T2N 4N1, Canada
| | - Yan Shi
- Institute for Immunology, Department of Basic Medical Sciences, School of Medicine, Tsinghua-Peking Joint Center for Life Sciences, Tsinghua University, Beijing 100084, China; Department of Microbiology, Immunology & Infectious Diseases and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB T2N 4N1, Canada.
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4
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Kim ML, Chae JJ, Park YH, De Nardo D, Stirzaker RA, Ko HJ, Tye H, Cengia L, DiRago L, Metcalf D, Roberts AW, Kastner DL, Lew AM, Lyras D, Kile BT, Croker BA, Masters SL. Aberrant actin depolymerization triggers the pyrin inflammasome and autoinflammatory disease that is dependent on IL-18, not IL-1β. THE JOURNAL OF EXPERIMENTAL MEDICINE 2015. [PMID: 26008898 DOI: 10.1084/jem.20142384)] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Gain-of-function mutations that activate the innate immune system can cause systemic autoinflammatory diseases associated with increased IL-1β production. This cytokine is activated identically to IL-18 by an intracellular protein complex known as the inflammasome; however, IL-18 has not yet been specifically implicated in the pathogenesis of hereditary autoinflammatory disorders. We have now identified an autoinflammatory disease in mice driven by IL-18, but not IL-1β, resulting from an inactivating mutation of the actin-depolymerizing cofactor Wdr1. This perturbation of actin polymerization leads to systemic autoinflammation that is reduced when IL-18 is deleted but not when IL-1 signaling is removed. Remarkably, inflammasome activation in mature macrophages is unaltered, but IL-18 production from monocytes is greatly exaggerated, and depletion of monocytes in vivo prevents the disease. Small-molecule inhibition of actin polymerization can remove potential danger signals from the system and prevents monocyte IL-18 production. Finally, we show that the inflammasome sensor of actin dynamics in this system requires caspase-1, apoptosis-associated speck-like protein containing a caspase recruitment domain, and the innate immune receptor pyrin. Previously, perturbation of actin polymerization by pathogens was shown to activate the pyrin inflammasome, so our data now extend this guard hypothesis to host-regulated actin-dependent processes and autoinflammatory disease.
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Affiliation(s)
- Man Lyang Kim
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jae Jin Chae
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yong Hwan Park
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Dominic De Nardo
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Roslynn A Stirzaker
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Hyun-Ja Ko
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Hazel Tye
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Louise Cengia
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Ladina DiRago
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Donald Metcalf
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Andrew W Roberts
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Daniel L Kastner
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Andrew M Lew
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Dena Lyras
- Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Benjamin T Kile
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ben A Croker
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
| | - Seth L Masters
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
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5
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Kim ML, Chae JJ, Park YH, De Nardo D, Stirzaker RA, Ko HJ, Tye H, Cengia L, DiRago L, Metcalf D, Roberts AW, Kastner DL, Lew AM, Lyras D, Kile BT, Croker BA, Masters SL. Aberrant actin depolymerization triggers the pyrin inflammasome and autoinflammatory disease that is dependent on IL-18, not IL-1β. ACTA ACUST UNITED AC 2015; 212:927-38. [PMID: 26008898 PMCID: PMC4451132 DOI: 10.1084/jem.20142384] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 04/21/2015] [Indexed: 01/27/2023]
Abstract
Kim et al. identify an autoinflammatory disease in mice that is driven by IL-18, resulting from an inactivating mutation in the actin-depolymerizing cofactor Wdr1. This alteration in actin dynamics is recognized by the pyrin inflammasome and results in exaggerated monocyte IL-18 production, whereas inflammasome activation in mature macrophages is unaltered. Gain-of-function mutations that activate the innate immune system can cause systemic autoinflammatory diseases associated with increased IL-1β production. This cytokine is activated identically to IL-18 by an intracellular protein complex known as the inflammasome; however, IL-18 has not yet been specifically implicated in the pathogenesis of hereditary autoinflammatory disorders. We have now identified an autoinflammatory disease in mice driven by IL-18, but not IL-1β, resulting from an inactivating mutation of the actin-depolymerizing cofactor Wdr1. This perturbation of actin polymerization leads to systemic autoinflammation that is reduced when IL-18 is deleted but not when IL-1 signaling is removed. Remarkably, inflammasome activation in mature macrophages is unaltered, but IL-18 production from monocytes is greatly exaggerated, and depletion of monocytes in vivo prevents the disease. Small-molecule inhibition of actin polymerization can remove potential danger signals from the system and prevents monocyte IL-18 production. Finally, we show that the inflammasome sensor of actin dynamics in this system requires caspase-1, apoptosis-associated speck-like protein containing a caspase recruitment domain, and the innate immune receptor pyrin. Previously, perturbation of actin polymerization by pathogens was shown to activate the pyrin inflammasome, so our data now extend this guard hypothesis to host-regulated actin-dependent processes and autoinflammatory disease.
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Affiliation(s)
- Man Lyang Kim
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jae Jin Chae
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Yong Hwan Park
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Dominic De Nardo
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Roslynn A Stirzaker
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Hyun-Ja Ko
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Hazel Tye
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Louise Cengia
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Ladina DiRago
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
| | - Donald Metcalf
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Andrew W Roberts
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Daniel L Kastner
- Inflammatory Disease Section, Metabolic, Cardiovascular, and Inflammatory Disease Genomics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892
| | - Andrew M Lew
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Dena Lyras
- Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Benjamin T Kile
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ben A Croker
- Division of Hematology/Oncology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115
| | - Seth L Masters
- Division of Inflammation, Division of Cancer and Hematology, Division of Immunology, and ACRF Chemical Biology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia Department of Medical Biology, The University of Melbourne, Parkville, Victoria 3010, Australia
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6
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Keestra AM, Winter MG, Auburger JJ, Frässle SP, Xavier MN, Winter SE, Kim A, Poon V, Ravesloot MM, Waldenmaier JFT, Tsolis RM, Eigenheer RA, Bäumler AJ. Manipulation of small Rho GTPases is a pathogen-induced process detected by NOD1. Nature 2013; 496:233-7. [PMID: 23542589 PMCID: PMC3625479 DOI: 10.1038/nature12025] [Citation(s) in RCA: 177] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 02/19/2013] [Indexed: 12/11/2022]
Abstract
Our innate immune system distinguishes microbes from self by detecting conserved pathogen-associated molecular patterns. However, these are produced by all microbes, regardless of their pathogenic potential. To distinguish virulent microbes from those with lower disease-causing potential the innate immune system detects conserved pathogen-induced processes, such as the presence of microbial products in the host cytosol, by mechanisms that are not fully resolved. Here we show that NOD1 senses cytosolic microbial products by monitoring the activation state of small Rho GTPases. Activation of RAC1 and CDC42 by bacterial delivery or ectopic expression of SopE, a virulence factor of the enteric pathogen Salmonella, triggered the NOD1 signalling pathway, with consequent RIP2 (also known as RIPK2)-mediated induction of NF-κB-dependent inflammatory responses. Similarly, activation of the NOD1 signalling pathway by peptidoglycan required RAC1 activity. Furthermore, constitutively active forms of RAC1, CDC42 and RHOA activated the NOD1 signalling pathway. Our data identify the activation of small Rho GTPases as a pathogen-induced process sensed through the NOD1 signalling pathway.
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Affiliation(s)
- A Marijke Keestra
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, California 95616, USA
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7
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Abstract
The microbiota of the mammalian intestinal tract represents a formidable barrier to colonization by pathogens. To overcome this resistance to colonization, bacterial pathogens use virulence factors to induce intestinal inflammation, which liberates nutrients for selective use by the infecting microbe. Studies of Salmonella enterica serovar Typhimurium (S. Typhimurium) infection in a streptomycin-treated mouse colitis model show how virulence factor-induced inflammation can produce nutrients used selectively by the pathogen. Type III secreted effectors of invading S. Typhimurium induce inflammation in the intestine (epithelial cells and lamina propria macrophages) that causes changes in the composition of the lumen. For example, neutrophils entering the intestine produce superoxide, resulting in production of tetrathionate, which S. Typhimurium in the lumen uses as an electron acceptor for anaerobic respiration. In their recent study, Lopez et al. demonstrate that S. Typhimurium strains that are lysogenized with a phage encoding type III effector SopE induce the host to produce nitric oxide synthetase (iNOS) in the intestine (C. A. Lopez et al., mBio 3:e00143-12, 2012). Nitric oxide is converted to a highly favorable electron acceptor, nitrate. As a result, growth of sopE+S. Typhimurium in the intestine lumen is boosted by nitrate respiration. This is a striking example of how acquisition of a virulence factor by horizontal gene transfer can increase the metabolic fitness of a pathogen. Interestingly, survival of the invading bacteria is probably decreased as a result of the SopE-induced immune response, and yet the S. Typhimurium bacteria that multiply in the lumen of the intestine can efficiently disseminate to another host, ensuring success for the pathogen.
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8
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Impellizzeri D, Mazzon E, Paterniti I, Esposito E, Cuzzocrea S. Effect of fasudil, a selective inhibitor of Rho kinase activity, in the secondary injury associated with the experimental model of spinal cord trauma. J Pharmacol Exp Ther 2012; 343:21-33. [PMID: 22733360 DOI: 10.1124/jpet.111.191239] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Rho kinase (ROK) may play an important role in regulating the biological events of cells, including proliferation, differentiation, and survival/death. Blockade of ROK promotes axonal regeneration and neuron survival in vivo and in vitro, thereby exhibiting potential clinical applications in spinal cord damage and stroke. The aim of this experimental study was to determine the role of ROK signaling pathways in the inflammatory response, in particular in the secondary injury associated with the experimental model of spinal cord trauma. The injury was induced by application of vascular clips to the dura via a four-level T5 to T8 laminectomy in mice. Fasudil was administered in mice (10 mg/kg i.p.) 1 and 6 h after the trauma. The treatment with fasudil significantly decreased 1) histological damage; 2) motor recovery; 3) nuclear factor-κB (NF-κB) expression; 4) ROK activity; 5) inflammasome activation (caspase-1 and NOD-like receptor family, pyrin domain-containing 3 expression); 6) production of proinflammatory cytokine such as tumor necrosis factor and interleukin-1β (IL-1β); 7) neutrophil infiltration; 8) nitrotyrosine and poly-ADP-ribose formation; 9) glial fibrillary acidic protein expression; 10) apoptosis (terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, FAS ligand expression, and Bax and Bcl-2 expression); and 11) mitogen-activated protein kinase activation (phospho-extracellular signal-regulated kinase and phospho-c-Jun NH(2)-terminal kinase expression). Our results indicate that inhibition of ROK by fasudil may represent a useful therapeutic perspective in the treatment of inflammation associated with spinal cord trauma.
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Affiliation(s)
- Daniela Impellizzeri
- Department of Clinical and Experimental Medicine and Pharmacology, School of Medicine, University of Messina, Italy
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9
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Kaiser P, Diard M, Stecher B, Hardt WD. The streptomycin mouse model for Salmonella diarrhea: functional analysis of the microbiota, the pathogen's virulence factors, and the host's mucosal immune response. Immunol Rev 2012; 245:56-83. [PMID: 22168414 DOI: 10.1111/j.1600-065x.2011.01070.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The mammalian intestine is colonized by a dense microbial community, the microbiota. Homeostatic and symbiotic interactions facilitate the peaceful co-existence between the microbiota and the host, and inhibit colonization by most incoming pathogens ('colonization resistance'). However, if pathogenic intruders overcome colonization resistance, a fierce, innate inflammatory defense can be mounted within hours, the adaptive arm of the immune system is initiated, and the pathogen is fought back. The molecular nature of the homeostatic interactions, the pathogen's ability to overcome colonization resistance, and the triggering of native and adaptive mucosal immune responses are still poorly understood. To study these mechanisms, the streptomycin mouse model for Salmonella diarrhea is of great value. Here, we review how S. Typhimurium triggers mucosal immune responses by active (virulence factor elicited) and passive (MyD88-dependent) mechanisms and introduce the S. Typhimurium mutants available for focusing on either response. Interestingly, mucosal defense turns out to be a double-edged sword, limiting pathogen burdens in the gut tissue but enhancing pathogen growth in the gut lumen. This model allows not only studying the molecular pathogenesis of Salmonella diarrhea but also is ideally suited for analyzing innate defenses, microbe handling by mucosal phagocytes, adaptive secretory immunoglobulin A responses, probing microbiota function, and homeostatic microbiota-host interactions. Finally, we discuss the general need for defined assay conditions when using animal models for enteric infections and the central importance of littermate controls.
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Affiliation(s)
- Patrick Kaiser
- Institute of Microbiology, D-BIOL, ETH Zürich, Zürich, Switzerland
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10
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Shen A. Clostridium difficile toxins: mediators of inflammation. J Innate Immun 2012; 4:149-58. [PMID: 22237401 DOI: 10.1159/000332946] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Accepted: 09/06/2011] [Indexed: 12/18/2022] Open
Abstract
Clostridium difficile is a significant problem in hospital settings as the most common cause of nosocomial diarrhea worldwide. C. difficile infections (CDIs) are characterized by an acute intestinal inflammatory response with neutrophil infiltration. These symptoms are primarily caused by the glucosylating toxins, TcdA and TcdB. In the past decade, the frequency and severity of CDIs have increased markedly due to the emergence of so-called hypervirulent strains that overproduce cytotoxic glucosylating toxins relative to historical strains. In addition, these strains produce a third toxin, binary toxin or C. difficile transferase (CDT), that may contribute to hypervirulence. Both the glucosylating toxins and CDT covalently modify target cell proteins to cause disassembly of the actin cytoskeleton and induce severe inflammation. This review summarizes our current knowledge of the mechanisms by which glucosylating toxins and CDT disrupt target cell function, alter host physiology and stimulate immune responses.
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Affiliation(s)
- Aimee Shen
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vt. 05401, USA.
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Salmonella typhimurium diarrhea: switching the mucosal epithelium from homeostasis to defense. Curr Opin Immunol 2011; 23:456-63. [PMID: 21726991 DOI: 10.1016/j.coi.2011.06.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 06/10/2011] [Accepted: 06/14/2011] [Indexed: 12/24/2022]
Abstract
The mammalian intestine is a complex biological system composed of the epithelium, the gut associated immune system, a commensal microbial community of approx. 10(10) cells per gram of content ('microbiota') and an occasional onslaught by pathogens. The mechanisms governing homeostasis and immune defense are of great importance, but incompletely understood. This is explained by the system's sheer complexity. So far, no single study has considered all relevant parameters, that is (i) innate and adaptive mucosal immune responses; (ii) mucosa cell gene expression; (iii) community composition of the microbiota; (iv) microbiota gene expression; (v) genetic profiling of the host; (vi) the virulence complement expressed by the pathogen in vivo. This exquisite complexity explains why simplified model systems have fuelled much recent progress on the system's regulating principles. Here, we focus on one particular model, the streptomycin pretreated mouse model for Salmonella diarrhea, to illustrate novel concepts in microbe-mucosa interaction, that is how this system switches from homeostasis to disease.
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Ashida H, Ogawa M, Kim M, Suzuki S, Sanada T, Punginelli C, Mimuro H, Sasakawa C. Shigella deploy multiple countermeasures against host innate immune responses. Curr Opin Microbiol 2010; 14:16-23. [PMID: 20934372 DOI: 10.1016/j.mib.2010.08.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 08/31/2010] [Indexed: 11/28/2022]
Abstract
Although the intestinal epithelium is equipped with multiple defense systems that sense bacterial components, transmit alarms to the immune system, clear the bacteria, and renew the injured epithelial lining, mucosal bacterial pathogens are capable of efficiently colonizing the intestinal epithelium, because they have evolved systems that modulate the inflammatory and immune responses of the host and exploit the harmful environments as replicative niches. In this review we highlight current topics concerning Shigella's tactics that interfere with the innate immune systems.
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Affiliation(s)
- Hiroshi Ashida
- Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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