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Zhu C, Xu S, Jiang R, Yu Y, Bian J, Zou Z. The gasdermin family: emerging therapeutic targets in diseases. Signal Transduct Target Ther 2024; 9:87. [PMID: 38584157 PMCID: PMC10999458 DOI: 10.1038/s41392-024-01801-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/03/2024] [Accepted: 03/05/2024] [Indexed: 04/09/2024] Open
Abstract
The gasdermin (GSDM) family has garnered significant attention for its pivotal role in immunity and disease as a key player in pyroptosis. This recently characterized class of pore-forming effector proteins is pivotal in orchestrating processes such as membrane permeabilization, pyroptosis, and the follow-up inflammatory response, which are crucial self-defense mechanisms against irritants and infections. GSDMs have been implicated in a range of diseases including, but not limited to, sepsis, viral infections, and cancer, either through involvement in pyroptosis or independently of this process. The regulation of GSDM-mediated pyroptosis is gaining recognition as a promising therapeutic strategy for the treatment of various diseases. Current strategies for inhibiting GSDMD primarily involve binding to GSDMD, blocking GSDMD cleavage or inhibiting GSDMD-N-terminal (NT) oligomerization, albeit with some off-target effects. In this review, we delve into the cutting-edge understanding of the interplay between GSDMs and pyroptosis, elucidate the activation mechanisms of GSDMs, explore their associations with a range of diseases, and discuss recent advancements and potential strategies for developing GSDMD inhibitors.
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Affiliation(s)
- Chenglong Zhu
- Faculty of Anesthesiology, Changhai Hospital, Naval Medical University, Shanghai, 200433, China
- School of Anesthesiology, Naval Medical University, Shanghai, 200433, China
| | - Sheng Xu
- National Key Laboratory of Immunity & Inflammation, Naval Medical University, Shanghai, 200433, China
| | - Ruoyu Jiang
- School of Anesthesiology, Naval Medical University, Shanghai, 200433, China
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Naval Medical University, Shanghai, 200433, China
| | - Yizhi Yu
- National Key Laboratory of Immunity & Inflammation, Naval Medical University, Shanghai, 200433, China.
| | - Jinjun Bian
- Faculty of Anesthesiology, Changhai Hospital, Naval Medical University, Shanghai, 200433, China.
| | - Zui Zou
- Faculty of Anesthesiology, Changhai Hospital, Naval Medical University, Shanghai, 200433, China.
- School of Anesthesiology, Naval Medical University, Shanghai, 200433, China.
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2
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Barry K, Murphy C, Mansell A. NLRP1- A CINDERELLA STORY: a perspective of recent advances in NLRP1 and the questions they raise. Commun Biol 2023; 6:1274. [PMID: 38104185 PMCID: PMC10725483 DOI: 10.1038/s42003-023-05684-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 12/06/2023] [Indexed: 12/19/2023] Open
Abstract
NLRP1, while the first inflammasome described, has only recently begun to gain significant attention in disease pathology, inflammation research, and potentially, as a therapeutic target. Recently identified human variants provide key insights into NLRP1 biology while its unique expression in barrier cells such as keratinocytes and airway epithelial cells has aligned with new, human specific agonists. This differentiates NLRP1 from other inflammasomes such as NLRP3 and identifies it as a key therapeutic target in inflammatory diseases. Indeed, recent discoveries highlight that NLRP1 may be the predominant inflammasome in human barrier cells, its primary role akin to NLRP3, to respond to cellular stress. This review focuses on recent studies identifying new human-specific NLRP1 mechanisms of activation of, gain-of-function human variants and disease, its role in responding to cellular stress, and discuss potential advances and the therapeutic potential for NLRP1.
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Affiliation(s)
- Kristian Barry
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia
- Department of Molecular and Translational Sciences, Monash University, Clayton, VIC, Australia
| | | | - Ashley Mansell
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia.
- Department of Molecular and Translational Sciences, Monash University, Clayton, VIC, Australia.
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3
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Bauernfried S, Hornung V. Human NLRP1: From the shadows to center stage. J Exp Med 2022; 219:212910. [PMID: 34910085 PMCID: PMC8679799 DOI: 10.1084/jem.20211405] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/03/2021] [Accepted: 12/03/2021] [Indexed: 12/03/2022] Open
Abstract
In response to infection or cell damage, inflammasomes form intracellular multimeric protein complexes that play an essential role in host defense. Activation results in the maturation and subsequent secretion of pro-inflammatory cytokines of the IL-1 family and a specific cell death coined pyroptosis. Human NLRP1 was the first inflammasome-forming sensor identified at the beginning of the millennium. However, its functional relevance and its mechanism of activation have remained obscure for many years. Recent discoveries in the NLRP1 field have propelled our understanding of the functional relevance and molecular mode of action of this unique inflammasome sensor, which we will discuss in this perspective.
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Affiliation(s)
- Stefan Bauernfried
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Veit Hornung
- Gene Center and Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
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4
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Tang T, Li P, Zhou X, Wang R, Fan X, Yang M, Qi K. The E3 Ubiquitin Ligase TRIM65 Negatively Regulates Inflammasome Activation Through Promoting Ubiquitination of NLRP3. Front Immunol 2021; 12:741839. [PMID: 34512673 PMCID: PMC8427430 DOI: 10.3389/fimmu.2021.741839] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/10/2021] [Indexed: 12/27/2022] Open
Abstract
The dysregulation of NLRP3 inflammasome plays a critical role in pathogenesis of various human inflammatory diseases, thus NLRP3 inflammasome activation must be tightly controlled at multiple levels. However, the underlying mechanism regulating NLRP3 inflammasome activation remains unclear. Herein, the effects of Tripartite motif-containing protein 65 (TRIM65) on NLRP3 inflammasome activation and the underlying molecular mechanism were investigated in vitro and in vivo. Inhibition or deletion of Trim65 could significantly strengthen agonist induced NLRP3 inflammasome activation in THP-1 cells and BMDMs, indicated by increased caspase-1 activation and interleukin-1β secretion. However, TRIM65 had no effect on poly (dA: dT)-induced AIM2 inflammasome activation or flagellin-induced IPAF inflammasome activation. Mechanistically, immunoprecipitation assays demonstrated that TRIM65 binds to NACHT domain of NLRP3, promotes lys48- and lys63- linked ubiquitination of NLRP3 and restrains the NEK7-NLRP3 interaction, thereby inhibiting NLRP3 inflammasome assembly, caspase-1 activation, and IL-1β secretion. In vivo, three models of inflammatory diseases were used to confirm the suppression role of TRIM65 in NLRP3 inflammasome activation. TRIM65-deficient mice had a higher production of IL-1β induced by lipopolysaccharide in sera, and more IL-1β secretion and neutrophil migration in the ascites, and more severity of joint swelling and associated IL-1β production induced by monosodium urate, suggesting that TRIM65 deficiency was susceptible to inflammation. Therefore, the data elucidate a TRIM65-dependent negative regulation mechanism of NLRP3 inflammasome activation and provide potential therapeutic strategies for the treatment of NLRP3 inflammasome-related diseases.
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Affiliation(s)
- Tiantian Tang
- Laboratory of Nutrition and Development, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Ping Li
- Laboratory of Nutrition and Development, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Xinhui Zhou
- Laboratory of Nutrition and Development, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Rui Wang
- Laboratory of Nutrition and Development, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Xiuqin Fan
- Laboratory of Nutrition and Development, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Mengyi Yang
- Laboratory of Nutrition and Development, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
| | - Kemin Qi
- Laboratory of Nutrition and Development, Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing Pediatric Research Institute, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing, China
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5
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Jing W, Lo Pilato J, Kay C, Man SM. Activation mechanisms of inflammasomes by bacterial toxins. Cell Microbiol 2021; 23:e13309. [PMID: 33426791 DOI: 10.1111/cmi.13309] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/16/2020] [Accepted: 12/12/2020] [Indexed: 12/13/2022]
Abstract
Inflammasomes are cytosolic innate immune complexes, which assemble in mammalian cells in response to microbial components and endogenous danger signals. A major family of inflammasome activators is bacterial toxins. Inflammasome sensor proteins, such as the nucleotide-binding oligomerisation domain-like receptor (NLR) family members NLRP1b and NLRP3, and the tripartite motif family member Pyrin+ efflux triggered by pore-forming toxins or by other toxin-induced homeostasis-altering events such as lysosomal rupture. Pyrin senses perturbation of host cell functions induced by certain enzymatic toxins resulting in impairment of RhoA GTPase activity. Assembly of the inflammasome complex activates the cysteine protease caspase-1, leading to the proteolytic cleavage of the proinflammatory cytokines IL-1β and IL-18, and the pore-forming protein gasdermin D causing pyroptosis. In this review, we discuss the latest progress in our understanding on the activation mechanisms of inflammasome complexes by bacterial toxins and effector proteins and explore avenues for future research into the relationships between inflammasomes and bacterial toxins.
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Affiliation(s)
- Weidong Jing
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Jordan Lo Pilato
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Callum Kay
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
| | - Si Ming Man
- Department of Immunology and Infectious Disease, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
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6
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Greaney AJ, Portley MK, O’Mard D, Crown D, Maier NK, Mendenhall MA, Mayer-Barber KD, Leppla SH, Moayeri M. Frontline Science: Anthrax lethal toxin-induced, NLRP1-mediated IL-1β release is a neutrophil and PAD4-dependent event. J Leukoc Biol 2020; 108:773-786. [PMID: 32421904 PMCID: PMC11062252 DOI: 10.1002/jlb.4hi0320-028r] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/17/2020] [Accepted: 03/28/2020] [Indexed: 12/21/2022] Open
Abstract
Anthrax lethal toxin (LT) is a protease that activates the NLRP1b inflammasome sensor in certain rodent strains. Unlike better-studied sensors, relatively little is known about the priming requirements for NLRP1b. In this study, we investigate the rapid and striking priming-independent LT-induced release of IL-1β in mice within hours of toxin challenge. We find IL-1β release to be a NLRP1b- and caspase-1-dependent, NLRP3 and caspase-11-independent event that requires both neutrophils and peptidyl arginine deiminiase-4 (PAD4) activity. The simultaneous LT-induced IL-18 response is neutrophil-independent. Bone marrow reconstitution experiments in mice show toxin-induced IL-1β originates from hematopoietic cells. LT treatment of neutrophils in vitro did not induce IL-1β, neutrophil extracellular traps (NETs), or pyroptosis. Although platelets interact closely with neutrophils and are also a potential source of IL-1β, they were unable to bind or endocytose LT and did not secrete IL-1β in response to the toxin. LT-treated mice had higher levels of cell-free DNA and HMGB1 in circulation than PBS-treated controls, and treatment of mice with recombinant DNase reduced the neutrophil- and NLRP1-dependent IL-1β release. DNA sensor AIM2 deficiency, however, did not impact IL-1β release. These data, in combination with the findings on PAD4, suggest a possible role for in vivo NETs or cell-free DNA in cytokine induction in response to LT challenge. Our findings suggest a complex interaction of events and/or mediators in LT-treated mice with the neutrophil as a central player in induction of a profound and rapid inflammatory response to toxin.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/physiology
- Animals
- Anthrax/immunology
- Antigens, Bacterial/pharmacology
- Antigens, Bacterial/toxicity
- Apoptosis Regulatory Proteins/deficiency
- Apoptosis Regulatory Proteins/physiology
- Bacillus anthracis/pathogenicity
- Bacillus anthracis/physiology
- Bacterial Toxins/pharmacology
- Bacterial Toxins/toxicity
- Extracellular Traps/physiology
- Inflammasomes/physiology
- Interleukin-1beta/metabolism
- Mice
- Mice, 129 Strain
- Mice, Congenic
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, SCID
- Monocytes/drug effects
- Monocytes/physiology
- NLR Family, Pyrin Domain-Containing 3 Protein/deficiency
- Neutrophils/drug effects
- Neutrophils/metabolism
- Protein-Arginine Deiminase Type 4/deficiency
- Protein-Arginine Deiminase Type 4/physiology
- Pyroptosis/drug effects
- Radiation Chimera
- Species Specificity
- Spores, Bacterial
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Affiliation(s)
- Allison J. Greaney
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Makayla K. Portley
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Danielle O’Mard
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Devorah Crown
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Nolan K. Maier
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Megan A. Mendenhall
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Katrin D. Mayer-Barber
- Inflammation and Innate Immunity Unit, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Stephen H. Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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7
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Chauhan D, Vande Walle L, Lamkanfi M. Therapeutic modulation of inflammasome pathways. Immunol Rev 2020; 297:123-138. [PMID: 32770571 PMCID: PMC7497261 DOI: 10.1111/imr.12908] [Citation(s) in RCA: 133] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 07/09/2020] [Accepted: 07/09/2020] [Indexed: 12/23/2022]
Abstract
Inflammasomes are macromolecular complexes formed in response to pathogen‐associated molecular patterns (PAMPs) and danger‐associated molecular patterns (DAMPs) that drive maturation of the pro‐inflammatory cytokines interleukin (IL)‐1β and IL‐18, and cleave gasdermin D (GSDMD) for induction of pyroptosis. Inflammasomes are highly important in protecting the host from various microbial pathogens and sterile insults. Inflammasome pathways are strictly regulated at both transcriptional and post‐translational checkpoints. When these checkpoints are not properly imposed, undue inflammasome activation may promote inflammatory, metabolic and oncogenic processes that give rise to autoinflammatory, autoimmune, metabolic and malignant diseases. In addition to clinically approved IL‐1‐targeted biologics, upstream targeting of inflammasome pathways recently gained interest as a novel pharmacological strategy for selectively modulating inflammasome activation in pathological conditions.
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Affiliation(s)
- Dhruv Chauhan
- Janssen Immunosciences, World Without Disease Accelerator, Pharmaceutical Companies of Johnson & Johnson, Beerse, Belgium
| | - Lieselotte Vande Walle
- Laboratory of Medical Innate Immunity, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Mohamed Lamkanfi
- Laboratory of Medical Innate Immunity, Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
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8
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The NLRP1 Inflammasome in Human Skin and Beyond. Int J Mol Sci 2020; 21:ijms21134788. [PMID: 32640751 PMCID: PMC7370280 DOI: 10.3390/ijms21134788] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/02/2020] [Accepted: 07/03/2020] [Indexed: 02/06/2023] Open
Abstract
Inflammasomes represent a group of protein complexes that contribute to host defense against pathogens and repair processes upon the induction of inflammation. However, aberrant and chronic inflammasome activation underlies the pathology of numerous common inflammatory diseases. Inflammasome assembly causes activation of the protease caspase-1 which in turn activates proinflammatory cytokines and induces a lytic type of cell death termed pyroptosis. Although NLRP1 (NACHT, leucine-rich repeat and pyrin domain containing 1) was the first inflammasome sensor, described almost 20 years ago, the molecular mechanisms underlying its activation and the resulting downstream events are incompletely understood. This is partially a consequence of the poor conservation of the NLRP1 pathway between human and mice. Moreover, recent evidence demonstrates a complex and multi-stage mechanism of NLRP1 inflammasome activation. In contrast to other inflammasome sensors, NLRP1 possesses protease activity required for proteolytic self-cleavage and activation mediated by the function-to-find domain (FIIND). CARD8 is a second FIIND protein and is expressed in humans but not in mice. In immune cells and AML (acute myeloid leukemia) cells, the anti-cancer drug talabostat induces CARD8 activation and causes caspase-1-dependent pyroptosis. In contrast, in human keratinocytes talabostat induces NLRP1 activation and massive proinflammatory cytokine activation. NLRP1 is regarded as the principal inflammasome sensor in human keratinocytes and UVB radiation induces its activation, which is believed to underlie the induction of sunburn. Moreover, gain-of-function mutations of NLRP1 cause inflammatory skin syndromes and a predisposition for the development of skin cancer. SNPs (single nucleotide polymorphisms) of NLRP1 are associated with several (auto)inflammatory diseases with a major skin phenotype, such as psoriasis or vitiligo. Here, we summarize knowledge about NLRP1 with emphasis on its role in human keratinocytes and skin. Due to its accessibility, pharmacological targeting of NLRP1 activation in epidermal keratinocytes represents a promising strategy for the treatment of the numerous patients suffering from NLRP1-dependent inflammatory skin conditions and cancer.
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Yan L, Liang J, Zhou Y, Huang J, Zhang T, Wang X, Yin H. Switch Off "Parallel Circuit": Insight of New Strategy of Simultaneously Suppressing Canonical and Noncanonical Inflammation Activation in Endotoxemic Mice. ACTA ACUST UNITED AC 2020; 4:e2000037. [PMID: 32419296 DOI: 10.1002/adbi.202000037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/21/2020] [Accepted: 04/22/2020] [Indexed: 12/29/2022]
Abstract
Sepsis is a life-threatening inflammatory disease with a high mortality rate and huge implicative costs. Lipopolysaccharide (LPS) from gram-negative bacteria activates toll-like receptor 4 (TLR4) and may trigger septic shock. However, potent TLR4 inhibitors TAK-242 and Eritoran have been terminated in phase III clinical trials because of inadequate efficacy. Inspired by the recently discovered intracellular, noncanonical LPS receptors, it is considered that TLR4-mediated canonical and caspase-mediated noncanonical inflammation can be seen as a "parallel circuit" to induce sepsis and endotoxemia. Logically, it is proposed that the dual inhibition of caspase-4/5/11 and TLR4 can be a potential novel strategy to develop new therapeutics for sepsis. To verify the strategy, two potential compounds are found: Luteolin and Diacerein with substantial antiinflammatory activity in vitro and in vivo. The results show that the survival rate of endotoxemic mice treated by these compounds is increased remarkably. LPS-induced organ damage is also prevented. Moreover, these compounds result in physical and mental recovery for endotoxemic mice. Notably, Luteolin exhibits better antiinflammatory activity than TAK-242 at comparable TLR4-inhibitory levels. These findings indicate that simultaneous inhibition of TLR4 and caspase-4/5/11 can be an anticipative strategy defeating sepsis and endotoxemia, which can be translated into significant medical and economic benefits.
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Affiliation(s)
- Lei Yan
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100082, China.,School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100082, China.,Tsinghua University-Peking University Joint Center for Life Sciences and Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100082, China
| | - Jiaqi Liang
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100082, China.,School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100082, China.,Tsinghua University-Peking University Joint Center for Life Sciences and Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100082, China
| | - Yi Zhou
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100082, China.,School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100082, China.,Tsinghua University-Peking University Joint Center for Life Sciences and Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100082, China
| | - Jian Huang
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100082, China.,School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100082, China.,Tsinghua University-Peking University Joint Center for Life Sciences and Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100082, China
| | - Tianshu Zhang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China
| | - Xiaohui Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin, 130022, China.,Department of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei, Anhui, 230026, China
| | - Hang Yin
- Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100082, China.,School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100082, China.,Tsinghua University-Peking University Joint Center for Life Sciences and Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing, 100082, China
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10
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Lacey CA, Miao EA. Programmed Cell Death in the Evolutionary Race against Bacterial Virulence Factors. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a036459. [PMID: 31501197 DOI: 10.1101/cshperspect.a036459] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Innate immune sensors can recognize when host cells are irrevocably compromised by pathogens, and in response can trigger programmed cell death (pyroptosis, apoptosis, and necroptosis). Innate sensors can directly bind microbial ligands; for example, NAIP/NLRC4 detects flagellin/rod/needle, whereas caspase-11 detects lipopolysaccharide. Other sensors are guards that monitor normal function of cellular proteins; for instance, pyrin monitors Rho GTPases, whereas caspase-8 and receptor-interacting protein kinase (RIPK)3 guards RIPK1 transcriptional signaling. Some proteins that need to be guarded can be duplicated as decoy domains, as seen in the integrated decoy domains within NLRP1 that watch for microbial attack. Here, we discuss the evolutionary battle between pathogens and host innate immune sensors/guards, illustrated by the Red Queen hypothesis. We discuss in depth four pathogens, and how they either fail in this evolutionary race (Chromobacterium violaceum, Burkholderia thailandensis), or how the evolutionary race generates increasingly complex virulence factors and host innate immune signaling pathways (Yersinia species, and enteropathogenic Escherichia coli [EPEC]).
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Affiliation(s)
- Carolyn A Lacey
- 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, North Carolina 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, North Carolina 27599, USA
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11
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Xu H, Shi J, Gao H, Liu Y, Yang Z, Shao F, Dong N. The N-end rule ubiquitin ligase UBR2 mediates NLRP1B inflammasome activation by anthrax lethal toxin. EMBO J 2019; 38:e101996. [PMID: 31268597 PMCID: PMC6600268 DOI: 10.15252/embj.2019101996] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 11/09/2022] Open
Abstract
Anthrax lethal toxin (LT) is known to induce NLRP1B inflammasome activation and pyroptotic cell death in macrophages from certain mouse strains in its metalloprotease activity-dependent manner, but the underlying mechanism is unknown. Here, we establish a simple but robust cell system bearing dual-fluorescence reporters for LT-induced ASC specks formation and pyroptotic lysis. A genome-wide siRNA screen and a CRISPR-Cas9 knockout screen were applied to this system for identifying genes involved in LT-induced inflammasome activation. UBR2, an E3 ubiquitin ligase of the N-end rule degradation pathway, was found to be required for LT-induced NLRP1B inflammasome activation. LT is known to cleave NLRP1B after Lys44. The cleaved NLRP1B, bearing an N-terminal leucine, was targeted by UBR2-mediated ubiquitination and degradation. UBR2 partnered with an E2 ubiquitin-conjugating enzyme UBE2O in this process. NLRP1B underwent constitutive autocleavage before the C-terminal CARD domain. UBR2-mediated degradation of LT-cleaved NLRP1B thus triggered release of the noncovalent-bound CARD domain for subsequent caspase-1 activation. Our study illustrates a unique mode of inflammasome activation in cytosolic defense against bacterial insults.
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Affiliation(s)
- Hao Xu
- National Institute of Biological SciencesBeijingChina
- Present address:
Molecular Pathogenesis ProgramThe Kimmel Center for Biology and Medicine of the Skirball InstituteNew York University School of MedicineNew YorkNYUSA
| | - Jianjin Shi
- National Institute of Biological SciencesBeijingChina
- Present address:
Department of BiologyStanford UniversityStanfordCAUSA
| | - Hang Gao
- State Key Laboratory of Animal NutritionCollege of Animal Science and TechnologyChina Agricultural UniversityBeijingChina
| | - Ying Liu
- State Key Laboratory of Animal NutritionCollege of Animal Science and TechnologyChina Agricultural UniversityBeijingChina
| | - Zhenxiao Yang
- National Institute of Biological SciencesBeijingChina
| | - Feng Shao
- National Institute of Biological SciencesBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical ResearchTsinghua UniversityBeijingChina
| | - Na Dong
- National Institute of Biological SciencesBeijingChina
- State Key Laboratory of Animal NutritionCollege of Animal Science and TechnologyChina Agricultural UniversityBeijingChina
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12
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Mitchell PS, Sandstrom A, Vance RE. The NLRP1 inflammasome: new mechanistic insights and unresolved mysteries. Curr Opin Immunol 2019; 60:37-45. [PMID: 31121538 DOI: 10.1016/j.coi.2019.04.015] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 04/18/2019] [Accepted: 04/19/2019] [Indexed: 11/25/2022]
Abstract
Nucleotide-binding domain, leucine-rich repeat (NLR) proteins constitute a diverse class of innate immune sensors that detect pathogens or stress-associated stimuli in plants and animals. Some NLRs are activated upon direct binding to pathogen-derived ligands. In contrast, we focus here on a vertebrate NLR called NLRP1 that responds to the enzymatic activities of pathogen effectors. We discuss a newly proposed 'functional degradation' mechanism that explains activation and assembly of NLRP1 into an oligomeric complex called an inflammasome. We also discuss how NLRP1 is activated by non-pathogen-associated triggers such as the anti-cancer drug Val-boroPro, or by human disease-associated mutations. Finally, we discuss how research on NLRP1 has led to additional biological insights, including the unexpected discovery of a new CARD8 inflammasome.
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Affiliation(s)
- Patrick S Mitchell
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, and Cancer Research Laboratory, University of California, Berkeley, CA, USA
| | - Andrew Sandstrom
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, and Cancer Research Laboratory, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Russell E Vance
- Division of Immunology & Pathogenesis, Department of Molecular & Cell Biology, and Cancer Research Laboratory, University of California, Berkeley, CA, USA; Howard Hughes Medical Institute, University of California, Berkeley, CA, USA.
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13
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Chui AJ, Okondo MC, Rao SD, Gai K, Griswold AR, Johnson DC, Ball DP, Taabazuing CY, Orth EL, Vittimberga BA, Bachovchin DA. N-terminal degradation activates the NLRP1B inflammasome. Science 2019; 364:82-85. [PMID: 30872531 PMCID: PMC6610862 DOI: 10.1126/science.aau1208] [Citation(s) in RCA: 204] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 11/02/2018] [Accepted: 03/05/2019] [Indexed: 12/29/2022]
Abstract
Intracellular pathogens and danger signals trigger the formation of inflammasomes, which activate inflammatory caspases and induce pyroptosis. The anthrax lethal factor metalloprotease and small-molecule DPP8/9 inhibitors both activate the NLRP1B inflammasome, but the molecular mechanism of NLRP1B activation is unknown. In this study, we used genome-wide CRISPR-Cas9 knockout screens to identify genes required for NLRP1B-mediated pyroptosis. We discovered that lethal factor induces cell death via the N-end rule proteasomal degradation pathway. Lethal factor directly cleaves NLRP1B, inducing the N-end rule-mediated degradation of the NLRP1B N terminus and freeing the NLRP1B C terminus to activate caspase-1. DPP8/9 inhibitors also induce proteasomal degradation of the NLRP1B N terminus but not via the N-end rule pathway. Thus, N-terminal degradation is the common activation mechanism of this innate immune sensor.
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Affiliation(s)
- Ashley J Chui
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Marian C Okondo
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sahana D Rao
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Kuo Gai
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Andrew R Griswold
- Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Darren C Johnson
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel P Ball
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Cornelius Y Taabazuing
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Elizabeth L Orth
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Brooke A Vittimberga
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel A Bachovchin
- Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
- Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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14
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Sandstrom A, Mitchell PS, Goers L, Mu EW, Lesser CF, Vance RE. Functional degradation: A mechanism of NLRP1 inflammasome activation by diverse pathogen enzymes. Science 2019; 364:science.aau1330. [PMID: 30872533 PMCID: PMC6532986 DOI: 10.1126/science.aau1330] [Citation(s) in RCA: 254] [Impact Index Per Article: 50.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 11/05/2018] [Accepted: 03/05/2019] [Indexed: 12/14/2022]
Abstract
Inflammasomes are multiprotein platforms that initiate innate immunity by recruitment and activation of caspase-1. The NLRP1B inflammasome is activated upon direct cleavage by the anthrax lethal toxin protease. However, the mechanism by which cleavage results in NLRP1B activation is unknown. In this study, we find that cleavage results in proteasome-mediated degradation of the amino-terminal domains of NLRP1B, liberating a carboxyl-terminal fragment that is a potent caspase-1 activator. Proteasome-mediated degradation of NLRP1B is both necessary and sufficient for NLRP1B activation. Consistent with our functional degradation model, we identify IpaH7.8, a Shigella flexneri ubiquitin ligase secreted effector, as an enzyme that induces NLRP1B degradation and activation. Our results provide a unified mechanism for NLRP1B activation by diverse pathogen-encoded enzymatic activities.
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Affiliation(s)
- Andrew Sandstrom
- Division of Immunology and Pathogenesis, Department of Molecular & Cell Biology, and Cancer Research Laboratory, University of California, Berkeley, CA, USA.,Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| | - Patrick S Mitchell
- Division of Immunology and Pathogenesis, Department of Molecular & Cell Biology, and Cancer Research Laboratory, University of California, Berkeley, CA, USA
| | - Lisa Goers
- Department of Microbiology, Harvard Medical School, Boston, MA, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, USA.,Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA
| | - Edward W Mu
- Division of Immunology and Pathogenesis, Department of Molecular & Cell Biology, and Cancer Research Laboratory, University of California, Berkeley, CA, USA
| | - Cammie F Lesser
- Department of Microbiology, Harvard Medical School, Boston, MA, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, USA.,Department of Medicine, Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA, USA
| | - Russell E Vance
- Division of Immunology and Pathogenesis, Department of Molecular & Cell Biology, and Cancer Research Laboratory, University of California, Berkeley, CA, USA. .,Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
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15
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Houtman J, Freitag K, Gimber N, Schmoranzer J, Heppner FL, Jendrach M. Beclin1-driven autophagy modulates the inflammatory response of microglia via NLRP3. EMBO J 2019; 38:embj.201899430. [PMID: 30617086 DOI: 10.15252/embj.201899430] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 11/28/2018] [Accepted: 12/05/2018] [Indexed: 12/18/2022] Open
Abstract
Alzheimer's disease is characterized not only by extracellular amyloid plaques and neurofibrillary tangles, but also by microglia-mediated neuroinflammation. Recently, autophagy has been linked to the regulation of the inflammatory response. Thus, we investigated how an impairment of autophagy mediated by BECN1/Beclin1 reduction, as described in Alzheimer's disease patients, would influence cytokine production of microglia. Acutely stimulated microglia from Becn1 +/- mice exhibited increased expression of IL-1beta and IL-18 compared to wild-type microglia. Becn1 +/- APPPS1 mice also contained enhanced IL-1beta levels. The investigation of the IL-1beta/IL-18 processing pathway showed an elevated number of cells with inflammasomes and increased levels of NLRP3 and cleaved CASP1/Caspase1 in Becn1 +/- microglia. Super-resolation microscopy revealed a very close association of NLRP3 aggregates and LC3-positive vesicles. Interestingly, CALCOCO2 colocalized with NLRP3 and its downregulation increased IL-1beta release. These data support the notion that selective autophagy can impact microglia activation by modulating IL-1beta and IL-18 production via NLRP3 degradation and thus present a mechanism how impaired autophagy could contribute to neuroinflammation in Alzheimer's disease.
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Affiliation(s)
- Judith Houtman
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Kiara Freitag
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, Berlin, Germany
| | - Niclas Gimber
- Core Facility Advanced Medical Bioimaging (AMBIO), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Jan Schmoranzer
- Core Facility Advanced Medical Bioimaging (AMBIO), Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Frank L Heppner
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE) within the Helmholtz Association, Berlin, Germany.,Cluster of Excellence, NeuroCure, Berlin, Germany
| | - Marina Jendrach
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
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16
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Van Opdenbosch N, Van Gorp H, Verdonckt M, Saavedra PHV, de Vasconcelos NM, Gonçalves A, Vande Walle L, Demon D, Matusiak M, Van Hauwermeiren F, D'Hont J, Hochepied T, Krautwald S, Kanneganti TD, Lamkanfi M. Caspase-1 Engagement and TLR-Induced c-FLIP Expression Suppress ASC/Caspase-8-Dependent Apoptosis by Inflammasome Sensors NLRP1b and NLRC4. Cell Rep 2018; 21:3427-3444. [PMID: 29262324 PMCID: PMC5746600 DOI: 10.1016/j.celrep.2017.11.088] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/15/2017] [Accepted: 11/27/2017] [Indexed: 02/02/2023] Open
Abstract
The caspase activation and recruitment domain (CARD)-based inflammasome sensors NLRP1b and NLRC4 induce caspase-1-dependent pyroptosis independent of the inflammasome adaptor ASC. Here, we show that NLRP1b and NLRC4 trigger caspase-8-mediated apoptosis as an alternative cell death program in caspase-1-/- macrophages and intestinal epithelial organoids (IECs). The caspase-8 adaptor FADD was recruited to ASC specks, which served as cytosolic platforms for caspase-8 activation and NLRP1b/NLRC4-induced apoptosis. We further found that caspase-1 protease activity dominated over scaffolding functions in suppressing caspase-8 activation and induction of apoptosis of macrophages and IECs. Moreover, TLR-induced c-FLIP expression inhibited caspase-8-mediated apoptosis downstream of ASC speck assembly, but did not affect pyroptosis induction by NLRP1b and NLRC4. Moreover, unlike during pyroptosis, NLRP1b- and NLRC4-elicited apoptosis retained alarmins and the inflammasome-matured cytokines interleukin 1β (IL-1β) and IL-18 intracellularly. This work identifies critical mechanisms regulating apoptosis induction by the inflammasome sensors NLRP1b and NLRC4 and suggests converting pyroptosis into apoptosis as a paradigm for suppressing inflammation.
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Affiliation(s)
- Nina Van Opdenbosch
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Hanne Van Gorp
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Maarten Verdonckt
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Pedro H V Saavedra
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Nathalia M de Vasconcelos
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Amanda Gonçalves
- VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium; VIB Bioimaging Core, VIB, 9000 Ghent, Belgium
| | - Lieselotte Vande Walle
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Dieter Demon
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Magdalena Matusiak
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Filip Van Hauwermeiren
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium
| | - Jinke D'Hont
- VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9000 Ghent, Belgium
| | - Tino Hochepied
- VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium; Department of Biomedical Molecular Biology, Ghent University, 9000 Ghent, Belgium
| | - Stefan Krautwald
- Department of Nephrology and Hypertension, University Hospital Schleswig-Holstein, 24105 Kiel, Germany
| | | | - Mohamed Lamkanfi
- Department of Internal Medicine, Ghent University, 9052 Ghent, Belgium; VIB-UGent Center for Inflammation Research, VIB, 9052 Ghent, Belgium.
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17
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Okondo MC, Rao SD, Taabazuing CY, Chui AJ, Poplawski SE, Johnson DC, Bachovchin DA. Inhibition of Dpp8/9 Activates the Nlrp1b Inflammasome. Cell Chem Biol 2018; 25:262-267.e5. [PMID: 29396289 DOI: 10.1016/j.chembiol.2017.12.013] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 12/13/2017] [Accepted: 12/22/2017] [Indexed: 12/26/2022]
Abstract
Val-boroPro (PT-100, Talabostat) induces powerful anti-tumor immune responses in syngeneic cancer models, but its mechanism of action has not yet been established. Val-boroPro is a non-selective inhibitor of post-proline-cleaving serine proteases, and the inhibition of the highly related cytosolic serine proteases Dpp8 and Dpp9 (Dpp8/9) by Val-boroPro was recently demonstrated to trigger an immunostimulatory form of programmed cell death known as pyroptosis selectively in monocytes and macrophages. Here we show that Dpp8/9 inhibition activates the inflammasome sensor protein Nlrp1b, which in turn activates pro-caspase-1 to mediate pyroptosis. This work reveals a previously unrecognized mechanism for activating an innate immune pattern recognition receptor and suggests that Dpp8/9 serve as an intracellular checkpoint to restrain Nlrp1b and the innate immune system.
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Affiliation(s)
- Marian C Okondo
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sahana D Rao
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Cornelius Y Taabazuing
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Ashley J Chui
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Sarah E Poplawski
- Department of Developmental, Chemical, & Molecular Biology, Tufts University Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, USA
| | - Darren C Johnson
- Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Daniel A Bachovchin
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Tri-institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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18
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Kawashima A, Karasawa T, Tago K, Kimura H, Kamata R, Usui-Kawanishi F, Watanabe S, Ohta S, Funakoshi-Tago M, Yanagisawa K, Kasahara T, Suzuki K, Takahashi M. ARIH2 Ubiquitinates NLRP3 and Negatively Regulates NLRP3 Inflammasome Activation in Macrophages. THE JOURNAL OF IMMUNOLOGY 2017; 199:3614-3622. [PMID: 29021376 DOI: 10.4049/jimmunol.1700184] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 09/15/2017] [Indexed: 12/12/2022]
Abstract
The nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is a molecular platform that induces caspase-1 activation and subsequent IL-1β maturation, and is implicated in inflammatory diseases; however, little is known about the negative regulation of NLRP3 inflammasome activation. In this article, we identified an E3 ligase, Ariadne homolog 2 (ARIH2), as a posttranslational negative regulator of NLRP3 inflammasome activity in macrophages. ARIH2 interacted with NLRP3 via its NACHT domain (aa 220-575) in the NLRP3 inflammasome complex. In particular, we found that while using mutants of ARIH2 and ubiquitin, the really interesting new gene 2 domain of ARIH2 was required for NLRP3 ubiquitination linked through K48 and K63. Deletion of endogenous ARIH2 using CRISPR/Cas9 genome editing inhibited NLRP3 ubiquitination and promoted NLRP3 inflammasome activation, resulting in apoptosis-associated speck-like protein containing a caspase recruitment domain oligomerization, pro-IL-1β processing, and IL-1β production. Conversely, ARIH2 overexpression promoted NLRP3 ubiquitination and inhibited NLRP3 inflammasome activation. Our findings reveal a novel mechanism of ubiquitination-dependent negative regulation of the NLRP3 inflammasome by ARIH2 and highlight ARIH2 as a potential therapeutic target for inflammatory diseases.
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Affiliation(s)
- Akira Kawashima
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan;
| | - Tadayoshi Karasawa
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Kenji Tago
- Department of Biochemistry, Jichi Medical University, Tochigi 329-0498, Japan
| | - Hiroaki Kimura
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Ryo Kamata
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Fumitake Usui-Kawanishi
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Sachiko Watanabe
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Satoshi Ohta
- Department of Biochemistry, Jichi Medical University, Tochigi 329-0498, Japan
| | | | - Ken Yanagisawa
- Department of Biochemistry, Jichi Medical University, Tochigi 329-0498, Japan
| | - Tadashi Kasahara
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Koichi Suzuki
- Department of Clinical Laboratory Science, Faculty of Medical Technology, Teikyo University, Tokyo 173-8605, Japan
| | - Masafumi Takahashi
- Division of Inflammation Research, Center for Molecular Medicine, Jichi Medical University, Tochigi 329-0498, Japan;
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19
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A Biologically-Based Computational Approach to Drug Repurposing for Anthrax Infection. Toxins (Basel) 2017; 9:toxins9030099. [PMID: 28287432 PMCID: PMC5371854 DOI: 10.3390/toxins9030099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 02/27/2017] [Accepted: 03/07/2017] [Indexed: 12/20/2022] Open
Abstract
Developing drugs to treat the toxic effects of lethal toxin (LT) and edema toxin (ET) produced by B. anthracis is of global interest. We utilized a computational approach to score 474 drugs/compounds for their ability to reverse the toxic effects of anthrax toxins. For each toxin or drug/compound, we constructed an activity network by using its differentially expressed genes, molecular targets, and protein interactions. Gene expression profiles of drugs were obtained from the Connectivity Map and those of anthrax toxins in human alveolar macrophages were obtained from the Gene Expression Omnibus. Drug rankings were based on the ability of a drug/compound’s mode of action in the form of a signaling network to reverse the effects of anthrax toxins; literature reports were used to verify the top 10 and bottom 10 drugs/compounds identified. Simvastatin and bepridil with reported in vitro potency for protecting cells from LT and ET toxicities were computationally ranked fourth and eighth. The other top 10 drugs were fenofibrate, dihydroergotamine, cotinine, amantadine, mephenytoin, sotalol, ifosfamide, and mefloquine; literature mining revealed their potential protective effects from LT and ET toxicities. These drugs are worthy of investigation for their therapeutic benefits and might be used in combination with antibiotics for treating B. anthracis infection.
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20
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Sun Q, Scott MJ. Caspase-1 as a multifunctional inflammatory mediator: noncytokine maturation roles. J Leukoc Biol 2016; 100:961-967. [PMID: 27450556 DOI: 10.1189/jlb.3mr0516-224r] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/07/2016] [Indexed: 12/19/2022] Open
Abstract
Caspase-1 is an inflammatory caspase that is activated through formation of inflammasome complexes in response to both pathogen-derived and endogenous mediators. The most well-known function of active caspase-1 is to cleave the proforms of inflammatory cytokines IL-1β and -18 into their active forms in response to inflammatory stimuli in immune cells. However, recent evidence suggests that caspase-1 has multiple functions in addition to this cytokine maturation role and that it is at the center of many cell responses to stress and inflammation. The current review focuses on roles for caspase-1, and the closely related caspase-11, in inflammatory forms of cell death and protein cleavage and also in protein secretion. These alternative caspase-1 functions can influence inflammatory responses, not just in immune cells but in other cell types, such as epithelia, where inflammatory cytokine production may not be a primary cell function.
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Affiliation(s)
- Qian Sun
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Melanie J Scott
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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21
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Zhao Y, Shao F. Diverse mechanisms for inflammasome sensing of cytosolic bacteria and bacterial virulence. Curr Opin Microbiol 2016; 29:37-42. [DOI: 10.1016/j.mib.2015.10.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 10/15/2015] [Accepted: 10/18/2015] [Indexed: 12/15/2022]
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22
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Biswas G, Bilen S, Kono T, Sakai M, Hikima JI. Inflammatory immune response by lipopolysaccharide-responsive nucleotide binding oligomerization domain (NOD)-like receptors in the Japanese pufferfish (Takifugu rubripes). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 55:21-31. [PMID: 26472618 DOI: 10.1016/j.dci.2015.10.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Revised: 10/07/2015] [Accepted: 10/07/2015] [Indexed: 06/05/2023]
Abstract
Some of NOD-like receptors (NLRs), the cytosolic pattern recognition receptors form a multi-protein complex, inflammasome consisting of one or more NLRs, the adaptor protein ASC and inflammatory caspase to generate mature inflammatory cytokines, interleukin (IL)-1β and IL-18. However, inflammasome-mediated inflammatory cascade involving any NLR member is unknown in a lower vertebrate like fish. Also, inflammatory cytokine induction pathway in response to a specific ligand, namely bacterial lipopolysaccharide (LPS) has not yet been clarified. Therefore, 13 predicted NLR sequences of the Japanese pufferfish, Fugu (Takifugu rubripes) were retrieved in silico and categorized as NLR-C1∼13. Expression analysis of these genes in Fugu head kidney (HK) cells stimulated with a heat-killed Lactobacillus paracasei spp. paracasei (Lpp), LPS, nigericin and a combination of nigericin + LPS showed consistent up-regulations of NLR-C1, 5, 7, 10 and 12 genes in both Lpp and LPS stimulations and NLR-C9 gene in LPS stimulation only. However, nigericin and nigericin + LPS caused an increased expression of NLR-C10 and 12 in HK cells and leukocytes. Fugu treated with Lpp and LPS (in vivo), and infected with Vibrio harveyi had an elevated expression of NLR-C10 and 12. Increased transcription of caspase-1, ASC, IL-1β and IL-18 was recorded in nigericin-stimulated HK cells and leukocytes. Results suggested activation of probable inflammasome-mediated inflammatory cytokine response in Fugu. Moreover, LPS may be a key ligand that induces some of the Fugu NLR-Cs (NLR-C9, 10 and 12). Further characterization and functional analysis of Fugu NLR-C10 and 12 for ligand sensing, and processing of pro-inflammatory cytokine, IL-1β would elucidate the inflammasome evolution in fish.
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Affiliation(s)
- Gouranga Biswas
- Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
| | - Soner Bilen
- Department of Basic Sciences, Faculty of Fisheries, Kastamonu University, Kastamonu 37200, Turkey
| | - Tomoya Kono
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
| | - Masahiro Sakai
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
| | - Jun-ichi Hikima
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan.
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23
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Abstract
Inflammasomes are cytosolic protein complexes that serve as platforms for the recruitment and activation of the pro-inflammatory CASPASE-1 protease. CASPASE-1 activation leads to processing and maturation of the cytokines interleukin-1β and interleukin-18 and a lytic form of cell death termed pyroptosis. Inflammasome assembly is initiated by cytosolic sensors in response to microbial infections. Many of these sensors, including NLRP1 (NLR family, pyrin domain containing 1), are described to form an inflammasome, but until recently, the mechanism of inflammasome activation and its physiological functions in host defense have remained unclear. In the last few years, important advances in our understanding of NLRP1 biology have been achieved. In this review, we discuss the activation of NLRP1 by various stimuli, including Bacillus anthracis lethal toxin, Toxoplasma gondii, muramyl dipeptide, and host intracellular ATP depletion. The role NLRP1 plays in pathogen recognition and resistance during infection is also discussed, as is the regulation of NLRP1 by host and viral proteins. We conclude by discussing the unexpected differences in the mechanism of NLRP1 inflammasome activation, as compared to the activation of other inflammasomes, such as the NAIP (NLR family, apoptosis inhibitory protein)/NLRC4 inflammasomes.
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Affiliation(s)
- Joseph Chavarría-Smith
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
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24
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Brojatsch J, Lima H, Palliser D, Jacobson LS, Muehlbauer SM, Furtado R, Goldman DL, Lisanti MP, Chandran K. Distinct cathepsins control necrotic cell death mediated by pyroptosis inducers and lysosome-destabilizing agents. Cell Cycle 2015; 14:964-72. [PMID: 25830414 DOI: 10.4161/15384101.2014.991194] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Necrotic cell death triggers a range of biological responses including a strong adaptive immune response, yet we know little about the cellular pathways that control necrotic cell death. Inhibitor studies suggest that proteases, and in particular cathepsins, drive necrotic cell death. The cathepsin B-selective inhibitor CA-074-Me blocks all forms of programmed necrosis by an unknown mechanism. We found that cathepsin B deficiency does not prevent induction of pyroptosis and lysosome-mediated necrosis suggesting that CA-074-Me blocks necrotic cell death by targeting cathepsins other than cathepsin B. A single cathepsin, cathepsin C, drives necrotic cell death mediated by the lysosome-destabilizing agent Leu-Leu-OMe (LLOMe). Here we present evidence that cathepsin C-deficiency and CA-074-Me block LLOMe killing in a distinct and cell type-specific fashion. Cathepsin C-deficiency and CA-074-Me block LLOMe killing of all myeloid cells, except for neutrophils. Cathepsin C-deficiency, but not CA-074-Me, blocks LLOMe killing of neutrophils suggesting that CA-074-Me does not target cathepsin C directly, consistent with inhibitor studies using recombinant cathepsin C. Unlike other cathepsins, cathepsin C lacks endoproteolytic activity, and requires activation by other lysosomal proteases, such as cathepsin D. Consistent with this theory, we found that lysosomotropic agents and cathepsin D downregulation by siRNA block LLOMe-mediated necrosis. Our findings indicate that a proteolytic cascade, involving cathepsins C and D, controls LLOMe-mediated necrosis. In contrast, cathepsins C and D were not required for pyroptotic cell death suggesting that distinct cathepsins control pyroptosis and lysosome-mediated necrosis.
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Affiliation(s)
- Jürgen Brojatsch
- a Department of Microbiology and Immunology; Albert Einstein College of Medicine , Bronx , NY USA
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25
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Greaney AJ, Leppla SH, Moayeri M. Bacterial Exotoxins and the Inflammasome. Front Immunol 2015; 6:570. [PMID: 26617605 PMCID: PMC4639612 DOI: 10.3389/fimmu.2015.00570] [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: 07/27/2015] [Accepted: 10/26/2015] [Indexed: 11/24/2022] Open
Abstract
The inflammasomes are intracellular protein complexes that play an important role in innate immune sensing. Activation of inflammasomes leads to activation of caspase-1 and maturation and secretion of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18. In certain myeloid cells, this activation can also lead to an inflammatory cell death (pyroptosis). Inflammasome sensor proteins have evolved to detect a range of microbial ligands and bacterial exotoxins either through direct interaction or by detection of host cell changes elicited by these effectors. Bacterial exotoxins activate the inflammasomes through diverse processes, including direct sensor cleavage, modulation of ion fluxes through plasma membrane pore formation, and perturbation of various host cell functions. In this review, we summarize the findings on some of the bacterial exotoxins that activate the inflammasomes.
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Affiliation(s)
- Allison J Greaney
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, MD , USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, MD , USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health , Bethesda, MD , USA
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26
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Zilbermintz L, Leonardi W, Jeong SY, Sjodt M, McComb R, Ho CLC, Retterer C, Gharaibeh D, Zamani R, Soloveva V, Bavari S, Levitin A, West J, Bradley KA, Clubb RT, Cohen SN, Gupta V, Martchenko M. Identification of agents effective against multiple toxins and viruses by host-oriented cell targeting. Sci Rep 2015; 5:13476. [PMID: 26310922 PMCID: PMC4550849 DOI: 10.1038/srep13476] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 07/28/2015] [Indexed: 01/25/2023] Open
Abstract
A longstanding and still-increasing threat to the effective treatment of infectious diseases is resistance to antimicrobial countermeasures. Potentially, the targeting of host proteins and pathways essential for the detrimental effects of pathogens offers an approach that may discover broad-spectrum anti-pathogen countermeasures and circumvent the effects of pathogen mutations leading to resistance. Here we report implementation of a strategy for discovering broad-spectrum host-oriented therapies against multiple pathogenic agents by multiplex screening of drugs for protection against the detrimental effects of multiple pathogens, identification of host cell pathways inhibited by the drug, and screening for effects of the agent on other pathogens exploiting the same pathway. We show that a clinically used antimalarial drug, Amodiaquine, discovered by this strategy, protects host cells against infection by multiple toxins and viruses by inhibiting host cathepsin B. Our results reveal the practicality of discovering broadly acting anti-pathogen countermeasures that target host proteins exploited by pathogens.
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Affiliation(s)
| | | | - Sun-Young Jeong
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Megan Sjodt
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095
| | - Ryan McComb
- Keck Graduate Institute, Claremont, CA 91711
| | - Chi-Lee C Ho
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095
| | - Cary Retterer
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Dima Gharaibeh
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Rouzbeh Zamani
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Veronica Soloveva
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | - Sina Bavari
- US Army Medical Research Institute of Infectious Diseases (USAMRIID), Fort Detrick, MD, 21702
| | | | - Joel West
- Keck Graduate Institute, Claremont, CA 91711
| | - Kenneth A Bradley
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA, 90095
| | - Robert T Clubb
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA, 90095
| | - Stanley N Cohen
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Vivek Gupta
- Keck Graduate Institute, Claremont, CA 91711
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27
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Greaney AJ, Maier NK, Leppla SH, Moayeri M. Sulforaphane inhibits multiple inflammasomes through an Nrf2-independent mechanism. J Leukoc Biol 2015; 99:189-99. [PMID: 26269198 DOI: 10.1189/jlb.3a0415-155rr] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 07/28/2015] [Indexed: 12/18/2022] Open
Abstract
The inflammasomes are intracellular complexes that have an important role in cytosolic innate immune sensing and pathogen defense. Inflammasome sensors detect a diversity of intracellular microbial ligands and endogenous danger signals and activate caspase-1, thus initiating maturation and release of the proinflammatory cytokines interleukin-1β and interleukin-18. These events, although crucial to the innate immune response, have also been linked to the pathology of several inflammatory and autoimmune disorders. The natural isothiocyanate sulforaphane, present in broccoli sprouts and available as a dietary supplement, has gained attention for its antioxidant, anti-inflammatory, and chemopreventive properties. We discovered that sulforaphane inhibits caspase-1 autoproteolytic activation and interleukin-1β maturation and secretion downstream of the nucleotide-binding oligomerization domain-like receptor leucine-rich repeat proteins NLRP1 and NLRP3, NLR family apoptosis inhibitory protein 5/NLR family caspase-1 recruitment domain-containing protein 4 (NAIP5/NLRC4), and absent in melanoma 2 (AIM2) inflammasome receptors. Sulforaphane does not inhibit the inflammasome by direct modification of active caspase-1 and its mechanism is not dependent on protein degradation by the proteasome or de novo protein synthesis. Furthermore, sulforaphane-mediated inhibition of the inflammasomes is independent of the transcription factor nuclear factor erythroid-derived 2-like factor 2 (Nrf2) and the antioxidant response-element pathway, to which many of the antioxidant and anti-inflammatory effects of sulforaphane have been attributed. Sulforaphane was also found to inhibit cell recruitment to the peritoneum and interleukin-1β secretion in an in vivo peritonitis model of acute gout and to reverse NLRP1-mediated murine resistance to Bacillus anthracis spore infection. These findings demonstrate that sulforaphane inhibits the inflammasomes through a novel mechanism and contributes to our understanding of the beneficial effects of sulforaphane.
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Affiliation(s)
- Allison J Greaney
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
| | - Nolan K Maier
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, U.S. National Institutes of Health, Bethesda, MD, USA
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28
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Bilen S, Biswas G, Otsuyama S, Kono T, Sakai M, Hikima JI. Inflammatory responses in the Japanese pufferfish (Takifugu rubripes) head kidney cells stimulated with an inflammasome-inducing agent, nigericin. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 46:222-230. [PMID: 24768998 DOI: 10.1016/j.dci.2014.04.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 04/15/2014] [Accepted: 04/15/2014] [Indexed: 06/03/2023]
Abstract
A cytosolic receptor complex called inflammasome is responsible for mounting inflammatory response by releasing pro-inflammatory cytokines, interleukin (IL)-1β and IL-18. However, inflammatory cascades mediated by the inflammasome are unknown in a lower vertebrate like fish. Therefore, in an in vitro experiment, in order to obtain a preliminary information, we conducted transcriptomic analysis of 18 cytokines including pro-inflammatory cytokines in the Japanese pufferfish (Takifugu rubripes) head kidney (HK) cells stimulated with an inflammasome-inducing agent, nigericin, and a combination of nigericin and LPS by a multiplex RT-PCR assay (GenomeLab Genetic Analysis System, GeXPS; Beckman Coulter Inc.). Furthermore, expression of IL-1β, IL-6, IL-18, nuclear factor (NF)-κB, nucleotide-binding oligomerization domain 2 (NOD2) and NOD-like receptor X1 (NLRX1) genes was examined in HK cells by a quantitative real-time PCR. Additionally, to confirm functionality of activated inflammatory immunity, we also assessed phagocytic activity, superoxide anion production (NBT assay) and lysozyme activity in the nigericin-stimulated HK cells. An increased gene expression of pro-inflammatory cytokines (IL-1β and IL-18), NF-κB and NOD2 was recorded in nigericin and combined nigericin+LPS- stimulated HK cells. Enhanced cellular (phagocytic activity and NBT assay) and humoral (lysozyme activity) immune parameters in the stimulated cells confirmed induction of inflammatory response. Results suggested probable activation of inflammasome components for processing of the inflammatory cytokines in the Japanese pufferfish.
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Affiliation(s)
- Soner Bilen
- Kastamonu University, Faculty of Fisheries, Department of Basic Sciences, Kastamonu 37200, Turkey
| | - Gouranga Biswas
- Interdisciplinary Graduate School of Agriculture and Engineering, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
| | - Shohei Otsuyama
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
| | - Tomoya Kono
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
| | - Masahiro Sakai
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan
| | - Jun-ichi Hikima
- Department of Biochemistry and Applied Biosciences, Faculty of Agriculture, University of Miyazaki, 1-1 Gakuenkibanadai-nishi, Miyazaki 889-2192, Japan.
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29
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Brojatsch J, Lima H, Kar AK, Jacobson LS, Muehlbauer SM, Chandran K, Diaz-Griffero F. A proteolytic cascade controls lysosome rupture and necrotic cell death mediated by lysosome-destabilizing adjuvants. PLoS One 2014; 9:e95032. [PMID: 24893007 PMCID: PMC4043491 DOI: 10.1371/journal.pone.0095032] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 03/23/2014] [Indexed: 12/22/2022] Open
Abstract
Recent studies have linked necrotic cell death and proteolysis of inflammatory proteins to the adaptive immune response mediated by the lysosome-destabilizing adjuvants, alum and Leu-Leu-OMe (LLOMe). However, the mechanism by which lysosome-destabilizing agents trigger necrosis and proteolysis of inflammatory proteins is poorly understood. The proteasome is a cellular complex that has been shown to regulate both necrotic cell death and proteolysis of inflammatory proteins. We found that the peptide aldehyde proteasome inhibitors, MG115 and MG132, block lysosome rupture, degradation of inflammatory proteins and necrotic cell death mediated by the lysosome-destabilizing peptide LLOMe. However, non-aldehyde proteasome inhibitors failed to prevent LLOMe-induced cell death suggesting that aldehyde proteasome inhibitors triggered a pleotropic effect. We have previously shown that cathepsin C controls lysosome rupture, necrotic cell death and the adaptive immune response mediated by LLOMe. Using recombinant cathepsin C, we found that aldehyde proteasome inhibitors directly block cathepsin C, which presumably prevents LLOMe toxicity. The cathepsin B inhibitor CA-074-Me also blocks lysosome rupture and necrotic cell death mediated by a wide range of necrosis inducers, including LLOMe. Using cathepsin-deficient cells and recombinant cathepsins, we demonstrate that the cathepsins B and C are not required for the CA-074-Me block of necrotic cell death. Taken together, our findings demonstrate that lysosome-destabilizing adjuvants trigger an early proteolytic cascade, involving cathepsin C and a CA-074-Me-dependent protease. Identification of these early events leading to lysosome rupture will be crucial in our understanding of processes controlling necrotic cell death and immune responses mediated by lysosome-destabilizing adjuvants.
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Affiliation(s)
- Jürgen Brojatsch
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, New York, United States of America
- * E-mail:
| | - Heriberto Lima
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, New York, United States of America
| | - Alak K. Kar
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, New York, United States of America
| | - Lee S. Jacobson
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, New York, United States of America
| | - Stefan M. Muehlbauer
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, New York, United States of America
| | - Kartik Chandran
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, New York, United States of America
| | - Felipe Diaz-Griffero
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, New York, United States of America
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30
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Selective inhibitor of endosomal trafficking pathways exploited by multiple toxins and viruses. Proc Natl Acad Sci U S A 2013; 110:E4904-12. [PMID: 24191014 DOI: 10.1073/pnas.1302334110] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Pathogenic microorganisms and toxins have evolved a variety of mechanisms to gain access to the host-cell cytosol and thereby exert virulent effects upon the host. One common mechanism of cellular entry requires trafficking to an acidified endosome, which promotes translocation across the host membrane. To identify small-molecule inhibitors that block this process, a library of 30,000 small molecules was screened for inhibitors of anthrax lethal toxin. Here we report that 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone, the most active compound identified in the screen, inhibits intoxication by lethal toxin and blocks the entry of multiple other acid-dependent bacterial toxins and viruses into mammalian cells. This compound, which we named EGA, also delays lysosomal targeting and degradation of the EGF receptor, indicating that it targets host-membrane trafficking. In contrast, EGA does not block endosomal recycling of transferrin, retrograde trafficking of ricin, phagolysosomal trafficking, or phagosome permeabilization by Franciscella tularensis. Furthermore, EGA does not neutralize acidic organelles, demonstrating that its mechanism of action is distinct from pH-raising agents such as ammonium chloride and bafilomycin A1. EGA is a powerful tool for the study of membrane trafficking and represents a class of host-targeted compounds for therapeutic development to treat infectious disease.
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31
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Jeong SY, Martchenko M, Cohen SN. Calpain-dependent cytoskeletal rearrangement exploited for anthrax toxin endocytosis. Proc Natl Acad Sci U S A 2013; 110:E4007-15. [PMID: 24085852 PMCID: PMC3801034 DOI: 10.1073/pnas.1316852110] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The protective antigen component of Bacillus anthracis toxins can interact with at least three distinct proteins on the host cell surface, capillary morphogenesis gene 2 (CMG2), tumor endothelial marker 8, and β1-integrin, and, with the assistance of other host proteins, enters targeted cells by receptor-mediated endocytosis. Using an antisense-based phenotypic screen, we discovered the role of calpains in this process. We show that functions of a ubiquitous Ca(2+)-dependent cysteine protease, calpain-2, and of the calpain substrate talin-1 are exploited for association of anthrax toxin and its principal receptor, CMG2, with higher-order actin filaments and consequently for toxin entry into host cells. Down-regulated expression of calpain-2 or talin-1, or pharmacological interference with calpain action, did not affect toxin binding but reduced endocytosis and increased the survival of cells exposed to anthrax lethal toxin. Adventitious expression of wild-type talin-1 promoted toxin endocytosis and lethality, whereas expression of a talin-1 mutant (L432G) that is insensitive to calpain cleavage did not. Disruption of talin-1, which links integrin-containing focal adhesion complexes to the actin cytoskeleton, facilitated association of toxin bound to its principal cell-surface receptor, CMG2, with higher-order actin filaments undergoing dynamic disassembly and reassembly during endocytosis. Our results reveal a mechanism by which a bacterial toxin uses constitutively occurring calpain-mediated cytoskeletal rearrangement for internalization.
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Affiliation(s)
| | | | - Stanley N. Cohen
- Departments of Genetics and
- Medicine, Stanford University School of Medicine, Stanford, CA 94305
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32
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Slater LH, Hett EC, Mark K, Chumbler NM, Patel D, Lacy DB, Collier RJ, Hung DT. Identification of novel host-targeted compounds that protect from anthrax lethal toxin-induced cell death. ACS Chem Biol 2013; 8:812-22. [PMID: 23343607 DOI: 10.1021/cb300555n] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Studying how pathogens subvert the host to cause disease has contributed to the understanding of fundamental cell biology. Bacillus anthracis, the causative agent of anthrax, produces the virulence factor lethal toxin to disarm host immunity and cause pathology. We conducted a phenotypic small molecule screen to identify inhibitors of lethal toxin-induced macrophage cell death and used an ordered series of secondary assays to characterize the hits and determine their effects on cellular function. We identified a structurally diverse set of small molecules that act at various points along the lethal toxin pathway, including inhibitors of endocytosis, natural product inhibitors of organelle acidification (e.g., the botulinum neurotoxin inhibitor, toosendanin), and a novel proteasome inhibitor, 4MNB (4-methoxy-2-[2-(5-methoxy-2-nitrosophenyl)ethyl]-1-nitrosobenzene). Many of the compounds, including three drugs approved for use in humans, also protected against the related Clostridium difficile toxin TcdB, further demonstrating their value as novel tools for perturbation and study of toxin biology and host cellular processes and highlighting potential new strategies for intervening on toxin-mediated diseases.
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Affiliation(s)
- Louise H. Slater
- Department of Molecular Biology
and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street,
Boston, Massachusetts 02114, United States
- Infectious Disease Initiative, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts
02142, United States
- Department
of Microbiology and
Immunobiology, Harvard Medical School,
77 Ave. Louis Pasteur Boston, Massachusetts 02115, United States
| | - Erik C. Hett
- Department of Molecular Biology
and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street,
Boston, Massachusetts 02114, United States
- Infectious Disease Initiative, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts
02142, United States
- Department
of Microbiology and
Immunobiology, Harvard Medical School,
77 Ave. Louis Pasteur Boston, Massachusetts 02115, United States
| | - Kevin Mark
- Department of Molecular Biology
and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street,
Boston, Massachusetts 02114, United States
- Infectious Disease Initiative, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts
02142, United States
- Department
of Microbiology and
Immunobiology, Harvard Medical School,
77 Ave. Louis Pasteur Boston, Massachusetts 02115, United States
| | - Nicole M. Chumbler
- Department of Microbiology and
Immunology, Vanderbilt University Medical Center, A-5301 Medical Center North, 1161 21st Avenue South, Nashville,
Tennessee 37232, United States
| | - Deepa Patel
- Department
of Microbiology and
Immunobiology, Harvard Medical School,
77 Ave. Louis Pasteur Boston, Massachusetts 02115, United States
| | - D. Borden Lacy
- Department of Microbiology and
Immunology, Vanderbilt University Medical Center, A-5301 Medical Center North, 1161 21st Avenue South, Nashville,
Tennessee 37232, United States
| | - R. John Collier
- Department
of Microbiology and
Immunobiology, Harvard Medical School,
77 Ave. Louis Pasteur Boston, Massachusetts 02115, United States
| | - Deborah T. Hung
- Department of Molecular Biology
and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street,
Boston, Massachusetts 02114, United States
- Infectious Disease Initiative, Broad Institute, 7 Cambridge Center, Cambridge, Massachusetts
02142, United States
- Department
of Microbiology and
Immunobiology, Harvard Medical School,
77 Ave. Louis Pasteur Boston, Massachusetts 02115, United States
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33
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Liao KC, Mogridge J. Activation of the Nlrp1b inflammasome by reduction of cytosolic ATP. Infect Immun 2013; 81:570-9. [PMID: 23230290 PMCID: PMC3553809 DOI: 10.1128/iai.01003-12] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 12/01/2012] [Indexed: 01/22/2023] Open
Abstract
The efficacy of the innate immune system depends on its ability to mount an appropriate response to diverse infections and damaging agents. Key components of this system are pattern recognition receptors that detect pathogen-associated and damage-associated molecular patterns (PAMPs and DAMPs). Nlrp1b is a pattern recognition receptor that forms a caspase-1 activation platform, known as an inflammasome, upon sensing the proteolytic activity of anthrax lethal toxin. The activation of caspase-1 leads to the release of proinflammatory cytokines that aid in the clearance of the anthrax infection. Here, we demonstrate that Nlrp1b also becomes activated in cells that are subjected to energy stress caused by metabolic inhibitors or by nutrient deprivation. Glucose starvation and hypoxia were used to correlate the level of cytosolic ATP to the degree of inflammasome activation. Because lowering the ratio of cytosolic ATP to AMP activates the main cellular energy sensor, AMP-activated protein kinase (AMPK), we assessed whether AMPK promoted inflammasome activity by using a combination of small interfering RNA (siRNA) and transfection of a dominant negative AMPK subunit. We found that AMPK promoted inflammasome activity, but activation of AMPK in the absence of ATP depletion was not sufficient for caspase-1-mediated pro-interleukin 1β (pro-IL-1β) processing. Finally, we found that mutation of the ATP-binding motif of Nlrp1b caused constitutive activation, suggesting that ATP might inhibit the Nlrp1b inflammasome instead of being required for its assembly.
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Affiliation(s)
- Kuo-Chieh Liao
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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34
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Lopez-Castejon G, Luheshi NM, Compan V, High S, Whitehead RC, Flitsch S, Kirov A, Prudovsky I, Swanton E, Brough D. Deubiquitinases regulate the activity of caspase-1 and interleukin-1β secretion via assembly of the inflammasome. J Biol Chem 2013; 288:2721-33. [PMID: 23209292 PMCID: PMC3554938 DOI: 10.1074/jbc.m112.422238] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 11/09/2012] [Indexed: 01/01/2023] Open
Abstract
IL-1β is a potent pro-inflammatory cytokine produced in response to infection or injury. It is synthesized as an inactive precursor that is activated by the protease caspase-1 within a cytosolic molecular complex called the inflammasome. Assembly of this complex is triggered by a range of structurally diverse damage or pathogen associated stimuli, and the signaling pathways through which these act are poorly understood. Ubiquitination is a post-translational modification essential for maintaining cellular homeostasis. It can be reversed by deubiquitinase enzymes (DUBs) that remove ubiquitin moieties from the protein thus modifying its fate. DUBs present specificity toward different ubiquitin chain topologies and are crucial for recycling ubiquitin molecules before protein degradation as well as regulating key cellular processes such as protein trafficking, gene transcription, and signaling. We report here that small molecule inhibitors of DUB activity inhibit inflammasome activation. Inhibition of DUBs blocked the processing and release of IL-1β in both mouse and human macrophages. DUB activity was necessary for inflammasome association as DUB inhibition also impaired ASC oligomerization and caspase-1 activation without directly blocking caspase-1 activity. These data reveal the requirement for DUB activity in a key reaction of the innate immune response and highlight the therapeutic potential of DUB inhibitors for chronic auto-inflammatory diseases.
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Affiliation(s)
| | | | | | - Stephen High
- Michael Smith Building, Faculty of Life Sciences, and
| | - Roger C. Whitehead
- School of Chemistry, University of Manchester Manchester, M13 9PT, United Kingdom and
| | - Sabine Flitsch
- School of Chemistry, University of Manchester Manchester, M13 9PT, United Kingdom and
| | - Aleksandr Kirov
- Center for Molecular Medicine, Maine Medical Centre Research Institute, Scarborough, Maine 04074
| | - Igor Prudovsky
- Center for Molecular Medicine, Maine Medical Centre Research Institute, Scarborough, Maine 04074
| | | | - David Brough
- From the AV Hill Building, Faculty of Life Sciences
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Jacobson LS, Lima H, Goldberg MF, Gocheva V, Tsiperson V, Sutterwala FS, Joyce JA, Gapp BV, Blomen VA, Chandran K, Brummelkamp TR, Diaz-Griffero F, Brojatsch J. Cathepsin-mediated necrosis controls the adaptive immune response by Th2 (T helper type 2)-associated adjuvants. J Biol Chem 2013; 288:7481-7491. [PMID: 23297415 DOI: 10.1074/jbc.m112.400655] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Immunologic adjuvants are critical components of vaccines, but it remains unclear how prototypical adjuvants enhance the adaptive immune response. Recent studies have shown that necrotic cells could trigger an immune response. Although most adjuvants have been shown to be cytotoxic, this activity has traditionally been considered a side effect. We set out to test the role of adjuvant-mediated cell death in immunity and found that alum, the most commonly used adjuvant worldwide, triggers a novel form of cell death in myeloid leukocytes characterized by cathepsin-dependent lysosome-disruption. We demonstrated that direct lysosome-permeabilization with a soluble peptide, Leu-Leu-OMe, mimics the alum-like form of necrotic cell death in terms of cathepsin dependence and cell-type specificity. Using a combination of a haploid genetic screen and cathepsin-deficient cells, we identified specific cathepsins that control lysosome-mediated necrosis. We identified cathepsin C as critical for Leu-Leu-OMe-induced cell death, whereas cathepsins B and S were required for alum-mediated necrosis. Consistent with a role of necrotic cell death in adjuvant effects, Leu-Leu-OMe replicated an alum-like immune response in vivo, characterized by dendritic cell activation, granulocyte recruitment, and production of Th2-associated antibodies. Strikingly, cathepsin C deficiency not only blocked Leu-Leu-OMe-mediated necrosis but also impaired Leu-Leu-OMe-enhanced immunity. Together our findings suggest that necrotic cell death is a powerful mediator of a Th2-associated immune response.
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Affiliation(s)
- Lee S Jacobson
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Heriberto Lima
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Michael F Goldberg
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Vasilena Gocheva
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering, New York, New York 10065
| | - Vladislav Tsiperson
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | | | - Johanna A Joyce
- Department of Cancer Biology and Genetics, Memorial Sloan-Kettering, New York, New York 10065
| | - Bianca V Gapp
- Department of Biochemistry, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Vincent A Blomen
- Department of Biochemistry, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Kartik Chandran
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Thijn R Brummelkamp
- Department of Biochemistry, Netherlands Cancer Institute, 1066 CX Amsterdam, The Netherlands
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Jürgen Brojatsch
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York 10461.
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von Moltke J, Ayres JS, Kofoed EM, Chavarría-Smith J, Vance RE. Recognition of bacteria by inflammasomes. Annu Rev Immunol 2012; 31:73-106. [PMID: 23215645 DOI: 10.1146/annurev-immunol-032712-095944] [Citation(s) in RCA: 322] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Inflammasomes are cytosolic multiprotein complexes that assemble in response to a variety of infectious and noxious insults. Inflammasomes play a critical role in the initiation of innate immune responses, primarily by serving as platforms for the activation of inflammatory caspase proteases. One such caspase, CASPASE-1 (CASP1), initiates innate immune responses by cleaving pro-IL-1β and pro-IL-18, leading to their activation and release. CASP1 and another inflammatory caspase termed CASP11 can also initiate a rapid and inflammatory form of cell death termed pyroptosis. Several distinct inflammasomes have been described, each of which contains a unique sensor protein of the NLR (nucleotide-binding domain, leucine-rich repeat-containing) superfamily or the PYHIN (PYRIN and HIN-200 domain-containing) superfamily. Here we describe the surprisingly diverse mechanisms by which NLR/PYHIN proteins sense bacteria and initiate innate immune responses. We conclude that inflammasomes represent a highly adaptable scaffold ideally suited for detecting and initiating rapid innate responses to diverse and rapidly evolving bacteria.
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Affiliation(s)
- Jakob von Moltke
- Department of Molecular & Cell Biology, Division of Immunology and Pathogenesis, University of California, Berkeley, California 94720, USA
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Cellular adaptation to anthrax lethal toxin-induced mitochondrial cholesterol enrichment, hyperpolarization, and reactive oxygen species generation through downregulating MLN64 in macrophages. Mol Cell Biol 2012; 32:4846-60. [PMID: 23028046 DOI: 10.1128/mcb.00494-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cellular adaptation to different stresses related to survival and function has been demonstrated in several cell types. Anthrax lethal toxin (LeTx) induces rapid cell death, termed "pyroptosis," by activating NLRP1b/caspase-1 in murine macrophages. We and others (S. D. Ha et al., J. Biol. Chem. 282:26275-26283, 2007; I. I. Salles et al., Proc. Natl. Acad. Sci. U. S. A. 100:12426 -12431, 2003) have shown that RAW264.7 cells preexposed to sublethal doses of LeTx become resistant to subsequent high cytolytic doses of LeTx, termed toxin-induced resistance (TIR). To date, the cellular mechanisms of pyroptosis and TIR are largely unknown. We found that LeTx caused NLRP1b/caspase-1-dependent mitochondrial dysfunction, including hyperpolarization and generation of reactive oxygen species, which was distinct from that induced by stimuli such as NLRP3-activating ATP. In TIR cells, these mitochondrial events were not detected, although caspase-1 was activated, in response to LeTx. We identified that downregulation of the late endosomal cholesterol-transferring protein MLN64 in TIR cells was involved in TIR. The downregulation of MLN64 in TIR cells was at least in part due to DNA methyltransferase 1-mediated DNA methylation. In wild-type RAW264.7 cells and primary bone marrow-derived macrophages, LeTx caused NLRP1b/caspase-1-dependent mitochondrial translocation of MLN64, resulting in cholesterol enrichment, membrane hyperpolarization, reactive oxygen species (ROS) generation, and depletion of free glutathione (GSH). This study demonstrates for the first time that MLN64 plays a key role in LeTx/caspase-1-induced mitochondrial dysfunction.
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Abstract
The extensively studied cytokine IL-1β is an important mediator of the inflammatory response. However, dysregulated release of IL-1β can be detrimental and is attributed to the progression and pathogenesis of multiple inflammatory diseases including, rhuematoid arthritis (RA), atherosclerosis, type 2 diabetes (T2D), Alzheimers disease and gout. IL-1β is encoded as a pro-protein. A multi-protein molecular scaffold termed the "Inflammasome" is responsible for the tightly controlled and coordinated processing of pro-IL-1β. The activation of several NLR (nucleotide-binding oligomerization domain (NOD)-like receptor) family members and PYHIN (pyrin and HIN domain) proteins can drive the formation of inflammasomes. However, the exact biochemical mechanisms governing their activation have been the subject of much research. Different inflammasomes have been demonstrated to respond to the same pathogen inducing a cooperative immune response accountable for the clearance of infection. Here, we review current knowledge surrounding the biochemical regulation of the NLRP1, NLRP3, NLRC4, AIM2 and IFI16 inflammasomes.
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Affiliation(s)
- Jennifer K Dowling
- Inflammation Research Group, School of Biochemistry and Immunology, Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland.
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Suppression of ribosomal function triggers innate immune signaling through activation of the NLRP3 inflammasome. PLoS One 2012; 7:e36044. [PMID: 22606244 PMCID: PMC3351443 DOI: 10.1371/journal.pone.0036044] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 03/26/2012] [Indexed: 12/12/2022] Open
Abstract
Some inflammatory stimuli trigger activation of the NLRP3 inflammasome by inducing efflux of cellular potassium. Loss of cellular potassium is known to potently suppress protein synthesis, leading us to test whether the inhibition of protein synthesis itself serves as an activating signal for the NLRP3 inflammasome. Murine bone marrow-derived macrophages, either primed by LPS or unprimed, were exposed to a panel of inhibitors of ribosomal function: ricin, cycloheximide, puromycin, pactamycin, and anisomycin. Macrophages were also exposed to nigericin, ATP, monosodium urate (MSU), and poly I:C. Synthesis of pro-IL-ß and release of IL-1ß from cells in response to these agents was detected by immunoblotting and ELISA. Release of intracellular potassium was measured by mass spectrometry. Inhibition of translation by each of the tested translation inhibitors led to processing of IL-1ß, which was released from cells. Processing and release of IL-1ß was reduced or absent from cells deficient in NLRP3, ASC, or caspase-1, demonstrating the role of the NLRP3 inflammasome. Despite the inability of these inhibitors to trigger efflux of intracellular potassium, the addition of high extracellular potassium suppressed activation of the NLRP3 inflammasome. MSU and double-stranded RNA, which are known to activate the NLRP3 inflammasome, also substantially inhibited protein translation, supporting a close association between inhibition of translation and inflammasome activation. These data demonstrate that translational inhibition itself constitutes a heretofore-unrecognized mechanism underlying IL-1ß dependent inflammatory signaling and that other physical, chemical, or pathogen-associated agents that impair translation may lead to IL-1ß-dependent inflammation through activation of the NLRP3 inflammasome. For agents that inhibit translation through decreased cellular potassium, the application of high extracellular potassium restores protein translation and suppresses activation of the NLRP inflammasome. For agents that inhibit translation through mechanisms that do not involve loss of potassium, high extracellular potassium suppresses IL-1ß processing through a mechanism that remains undefined.
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Moayeri M, Sastalla I, Leppla SH. Anthrax and the inflammasome. Microbes Infect 2012; 14:392-400. [PMID: 22207185 PMCID: PMC3322314 DOI: 10.1016/j.micinf.2011.12.005] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2011] [Revised: 12/07/2011] [Accepted: 12/08/2011] [Indexed: 01/07/2023]
Abstract
Anthrax lethal toxin (LT), a major virulence determinant of anthrax disease, induces vascular collapse in mice and rats. LT activates the Nlrp1 inflammasome in macrophages and dendritic cells, resulting in caspase-1 activation, IL-1β and IL-18 maturation and a rapid cell death (pyroptosis). This review presents the current understanding of LT-induced activation of Nlrp1 in cells and its consequences for toxin-mediated effects in rodent toxin and spore challenge models.
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Affiliation(s)
- Mahtab Moayeri
- Laboratory of Bacterial Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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41
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Proteolytic processing of Nlrp1b is required for inflammasome activity. PLoS Pathog 2012; 8:e1002659. [PMID: 22536155 PMCID: PMC3334886 DOI: 10.1371/journal.ppat.1002659] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 03/06/2012] [Indexed: 12/18/2022] Open
Abstract
Nlrp1b is a NOD-like receptor that detects the catalytic activity of anthrax lethal toxin and subsequently co-oligomerizes into a pro-caspase-1 activation platform known as an inflammasome. Nlrp1b has two domains that promote oligomerization: a NACHT domain, which is a member of the AAA+ ATPase family, and a poorly characterized Function to Find Domain (FIIND). Here we demonstrate that proteolytic processing within the FIIND generates N-terminal and C-terminal cleavage products of Nlrp1b that remain associated in both the auto-inhibited state and in the activated state after cells have been treated with lethal toxin. Functional significance of cleavage was suggested by the finding that mutations that block processing of Nlrp1b also prevent the ability of Nlrp1b to activate pro-caspase-1. By using an uncleaved mutant of Nlrp1b, we established the importance of cleavage by inserting a heterologous TEV protease site into the FIIND and demonstrating that TEV protease processed this site and induced inflammasome activity. Proteolysis of Nlrp1b was shown to be required for the assembly of a functional inflammasome: a mutation within the FIIND that abolished cleavage had no effect on self-association of a FIIND-CARD fragment, but did reduce the recruitment of pro-caspase-1. Our work indicates that a post-translational modification enables Nlrp1b to function. Inflammasomes are multi-protein complexes that respond to signals derived from microbial pathogens or damaged tissue. The function of an inflammasome is to activate pro-caspase-1, a protease that contributes to the inflammatory response by generating the cytokines IL-1β and IL-18. A common feature of inflammasomes is their ability to cluster multiple copies of pro-caspase-1 in a manner that allows inter-molecular auto-proteolysis. The Nlrp1b inflammasome assembles in response to anthrax lethal toxin by using two oligomerization regions: the NACHT domain and the FIIND-CARD region. Here, we demonstrate that the FIIND is proteolytically cleaved, but that the two fragments of Nlrp1b generated from the cleavage remain associated with one another. Cleavage within the FIIND is functionally important, however, because mutants of Nlrp1b that are not cleaved are not able to activate pro-caspase-1. Furthermore, we were able to control cleavage by inserting a heterologous protease site into Nlrp1b, which allowed us to establish that processing of Nlrp1b is required for its activity. Finally, we provide evidence that processing of Nlrp1b facilitates the recruitment of pro-caspase-1. Our work identifies a novel mechanism by which the Nlrp1b inflammasome may be regulated.
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Anthrax lethal factor cleavage of Nlrp1 is required for activation of the inflammasome. PLoS Pathog 2012; 8:e1002638. [PMID: 22479187 PMCID: PMC3315489 DOI: 10.1371/journal.ppat.1002638] [Citation(s) in RCA: 241] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2012] [Accepted: 02/24/2012] [Indexed: 01/12/2023] Open
Abstract
NOD-like receptor (NLR) proteins (Nlrps) are cytosolic sensors responsible for detection of pathogen and danger-associated molecular patterns through unknown mechanisms. Their activation in response to a wide range of intracellular danger signals leads to formation of the inflammasome, caspase-1 activation, rapid programmed cell death (pyroptosis) and maturation of IL-1β and IL-18. Anthrax lethal toxin (LT) induces the caspase-1-dependent pyroptosis of mouse and rat macrophages isolated from certain inbred rodent strains through activation of the NOD-like receptor (NLR) Nlrp1 inflammasome. Here we show that LT cleaves rat Nlrp1 and this cleavage is required for toxin-induced inflammasome activation, IL-1 β release, and macrophage pyroptosis. These results identify both a previously unrecognized mechanism of activation of an NLR and a new, physiologically relevant protein substrate of LT. Anthrax lethal toxin (LT) is a protease which can induce rapid death of macrophages accompanied by activation and release of pro-inflammatory cytokines. The previously identified cellular substrates for this toxin have not been shown to play a role in this rapid cell death. This report identifies a new substrate for LT, and demonstrates that its cleavage by the toxin is required for macrophage death. The substrate, Nlrp1, is a member of a large family of intracellular sensors of danger. These sensors, once activated, form a multiprotein complex called the inflammasome and are essential to the host innate immune response. The mechanism of activation for these sensors is not known. The demonstration of cleavage-mediated activation of Nlrp1 in this study represents the first report on a direct biochemical mechanism for inflammasome activation.
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Mankan AK, Kubarenko A, Hornung V. Immunology in clinic review series; focus on autoinflammatory diseases: inflammasomes: mechanisms of activation. Clin Exp Immunol 2012; 167:369-81. [PMID: 22288580 DOI: 10.1111/j.1365-2249.2011.04534.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
UNLABELLED OTHER THEMES PUBLISHED IN THIS IMMUNOLOGY IN THE CLINIC REVIEW SERIES Allergy, Host Responses, Cancer, Type 1 diabetes and viruses, Metabolic diseases. SUMMARY Initiation of a successful immune response requires a working set of sensors that detect any noxious agent within the cellular microenvironment and molecular platforms that process this signal to trigger an appropriate effector response. Pattern recognition receptors can engage different signalling cascades that lead to proinflammatory gene expression. At the same time, transcription-independent events such as activation of proteases and/or phagocytosis are also initiated. The inflammasome pathway constitutes a signalling platform that leads to the activation of so-called inflammatory caspases, most notably caspase-1, which plays a pivotal role in the cleavage and thus maturation of proinflammatory cytokines, but also in the induction of pyroptosis, a special type of cell death. In this review we elaborate on the currently known inflammasome complexes with a special focus on the mechanism behind their activation. Understanding these mechanisms could provide important information regarding the potential signalling nodes that might be targeted for therapeutic intervention.
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Affiliation(s)
- A K Mankan
- Institute for Clinical Chemistry and Clinical Pharmacology, Unit for Clinical Biochemistry, University Hospital, University of Bonn, Bonn, Germany
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44
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Nagarajan UM, Sikes JD, Yeruva L, Prantner D. Significant role of IL-1 signaling, but limited role of inflammasome activation, in oviduct pathology during Chlamydia muridarum genital infection. THE JOURNAL OF IMMUNOLOGY 2012; 188:2866-75. [PMID: 22331066 DOI: 10.4049/jimmunol.1103461] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
IL-1β has been implicated in the development of oviduct pathology during Chlamydia muridarum genital infection in the mouse model. The goal of this study was to characterize the role of IL-1 signaling and the inflammasome-activation pathways during genital chlamydial infection. Compared with control mice, IL-1R-deficient mice displayed delayed clearance and increased chlamydial colonization. Consistent with the role for IL-1 signaling in infection clearance, mice deficient for the IL-1R antagonist cleared infection at a faster rate. Despite increased infection, IL-1R-deficient mice had significantly reduced oviduct pathology, which was associated with decreased numbers of neutrophils, but more macrophages, in the genital tract. IL-1β secretion is dependent on caspase-1 and apoptosis-associated speck-like protein containing caspase recruitment domain (ASC) inflammasome during in vitro infection of primed macrophages with C. muridarum. To investigate the role of inflammasome components during in vivo genital infection, mice lacking NLRP3, NLRC4, and ASC were tested and found to display no reduction in oviduct pathology compared with control mice. Mice deficient for ASC displayed a prolonged course of infection, which was associated with reduced T cell recruitment and proliferation. Further, ASC-deficient mice displayed normal levels of IL-1β in genital secretions. However, a significant decrease in caspase-1-dependent IL-18 was observed in both ASC- and NLRP3-deficient mice. These data demonstrate a major role for IL-1 signaling, but a limited role for the inflammasome pathway, in IL-1β secretion and development of oviduct pathology during genital chlamydial infection. The data also suggest an IL-1-independent role for ASC in adaptive immunity during genital chlamydial infection.
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Affiliation(s)
- Uma M Nagarajan
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72202, USA.
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45
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Nour AM, Reichelt M, Ku CC, Ho MY, Heineman TC, Arvin AM. Varicella-zoster virus infection triggers formation of an interleukin-1β (IL-1β)-processing inflammasome complex. J Biol Chem 2011; 286:17921-33. [PMID: 21385879 PMCID: PMC3093867 DOI: 10.1074/jbc.m110.210575] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Innate cellular immunity is the immediate host response against pathogens, and activation of innate immunity also modulates the induction of adaptive immunity. The nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are a family of intracellular receptors that recognize conserved patterns associated with intracellular pathogens, but information about their role in the host defense against DNA viruses is limited. Here we report that varicella-zoster virus (VZV), an alphaherpesvirus that is the causative agent of varicella and herpes zoster, induces formation of the NLRP3 inflammasome and the associated processing of the proinflammatory cytokine IL-1β by activated caspase-1 in infected cells. NLRP3 inflammasome formation was induced in VZV-infected human THP-1 cells, which are a transformed monocyte cell line, primary lung fibroblasts, and melanoma cells. Absent in melanoma gene-2 (AIM2) is an interferon-inducible protein that can form an alternative inflammasome complex with caspase-1 in virus-infected cells. Experiments in VZV-infected melanoma cells showed that NLRP3 protein recruits the adaptor protein ASC and caspase-1 to form an NLRP3 inflammasome complex independent of AIM2 protein and in the absence of free radical reactive oxygen species release. NLRP3 was also expressed extensively in infected skin xenografts in the severe combined immunodeficiency mouse model of VZV pathogenesis in vivo. We conclude that NLRP3 inflammasome formation is an innate cellular response to infection with this common pathogenic human herpesvirus.
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Affiliation(s)
- Adel M Nour
- Department of Pediatrics, Stanford University School of Medicine, Stanford, California 94305, USA.
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46
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Bauernfeind F, Ablasser A, Bartok E, Kim S, Schmid-Burgk J, Cavlar T, Hornung V. Inflammasomes: current understanding and open questions. Cell Mol Life Sci 2011; 68:765-83. [PMID: 21072676 PMCID: PMC11114650 DOI: 10.1007/s00018-010-0567-4] [Citation(s) in RCA: 286] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/09/2010] [Accepted: 10/12/2010] [Indexed: 12/31/2022]
Abstract
The innate immune system relies on its capability to detect invading microbes, tissue damage, or stress via evolutionarily conserved receptors. The nucleotide-binding domain leucine-rich repeat (NLR)-containing family of pattern recognition receptors includes several proteins that drive inflammation in response to a wide variety of molecular patterns. In particular, the NLRs that participate in the formation of a molecular scaffold termed the "inflammasome" have been intensively studied in past years. Inflammasome activation by multiple types of tissue damage or by pathogen-associated signatures results in the autocatalytic cleavage of caspase-1 and ultimately leads to the processing and thus secretion of pro-inflammatory cytokines, most importantly interleukin (IL)-1β and IL-18. Here, we review the current knowledge of mechanisms leading to the activation of inflammasomes. In particular, we focus on the controversial molecular mechanisms that regulate NLRP3 signaling and highlight recent advancements in DNA sensing by the inflammasome receptor AIM2.
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Affiliation(s)
- Franz Bauernfeind
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Andrea Ablasser
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Eva Bartok
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Sarah Kim
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Jonathan Schmid-Burgk
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Taner Cavlar
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
| | - Veit Hornung
- Unit for Clinical Biochemistry, Institute for Clinical Chemistry and Clinical Pharmacology, University Hospital, University of Bonn, Sigmund-Freud-Strasse 25, 53127 Bonn, Germany
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Skeldon A, Saleh M. The inflammasomes: molecular effectors of host resistance against bacterial, viral, parasitic, and fungal infections. Front Microbiol 2011; 2:15. [PMID: 21716947 PMCID: PMC3109312 DOI: 10.3389/fmicb.2011.00015] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 01/20/2011] [Indexed: 01/01/2023] Open
Abstract
The inflammasomes are large multi-protein complexes scaffolded by cytosolic pattern recognition receptors (PRRs) that form an important part of the innate immune system. They are activated following the recognition of microbial-associated molecular patterns or host-derived danger signals (danger-associated molecular patterns) by PRRs. This recognition results in the recruitment and activation of the pro-inflammatory protease caspase-1, which cleaves its preferred substrates pro-interleukin-1β (IL-1β) and pro-IL-18 into their mature biologically active cytokine forms. Through processing of a number of other cellular substrates, caspase-1 is also required for the release of “alarmins” and the induction and execution of an inflammatory form of cell death termed pyroptosis. A growing spectrum of inflammasomes have been identified in the host defense against a variety of pathogens. Reciprocally, pathogens have evolved effector strategies to antagonize the inflammasome pathway. In this review we discuss recent developments in the understanding of inflammasome-mediated recognition of bacterial, viral, parasitic, and fungal infections and the beneficial or detrimental effects of inflammasome signaling in host resistance.
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Auranofin protects against anthrax lethal toxin-induced activation of the Nlrp1b inflammasome. Antimicrob Agents Chemother 2010; 55:1028-35. [PMID: 21149629 DOI: 10.1128/aac.00772-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Anthrax lethal toxin (LT) is the major virulence factor for Bacillus anthracis. The lethal factor (LF) component of this bipartite toxin is a protease which, when transported into the cellular cytoplasm, cleaves mitogen-activated protein kinase kinase (MEK) family proteins and induces rapid toxicity in mouse macrophages through activation of the Nlrp1b inflammasome. A high-throughput screen was performed to identify synergistic LT-inhibitory drug combinations from within a library of approved drugs and molecular probes. From this screen we discovered that auranofin, an organogold compound with anti-inflammatory activity, strongly inhibited LT-mediated toxicity in mouse macrophages. Auranofin did not inhibit toxin transport into cells or MEK cleavage but inhibited both LT-mediated caspase-1 activation and caspase-1 catalytic activity. Thus, auranofin inhibited LT-mediated toxicity by preventing activation of the Nlrp1b inflammasome and the downstream actions that occur in response to the toxin. Idebenone, an analog of coenzyme Q, synergized with auranofin to increase its protective effect. We found that idebenone functions as an inhibitor of voltage-gated potassium channels and thus likely mediates synergy through inhibition of the potassium fluxes which have been shown to be required for Nlrp1b inflammasome activation.
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49
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Newman ZL, Crown D, Leppla SH, Moayeri M. Anthrax lethal toxin activates the inflammasome in sensitive rat macrophages. Biochem Biophys Res Commun 2010; 398:785-9. [PMID: 20638366 DOI: 10.1016/j.bbrc.2010.07.039] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 07/13/2010] [Indexed: 11/29/2022]
Abstract
Anthrax lethal toxin (LT) is an important virulence factor for Bacillus anthracis. In mice, LT lyses macrophages from certain inbred strains in less than 2h by activating the Nlrp1b inflammasome and caspase-1, while macrophages from other strains remain resistant to the toxin's effects. We analyzed LT effects in toxin-sensitive and resistant rat macrophages to test if a similar pathway was involved in rat macrophage death. LT activates caspase-1 in rat macrophages from strains harboring LT-sensitive macrophages in a manner similar to that in toxin-sensitive murine macrophages. This activation of caspase-1 is dependent on proteasome activity, and sensitive macrophages are protected from LT's lytic effects by lactacystin. Proteasome inhibition also delayed the death of rats in response to LT, confirming our previous data implicating the rat Nlrp1 inflammasome in animal death. Quinidine, caspase-1 inhibitors, the cathepsin B inhibitor CA-074Me, and heat shock also protected rat macrophages from LT toxicity. These data support the existence of an active functioning LT-responsive Nlrp1 inflammasome in rat macrophages. The activation of the rat Nlrp1 inflammasome is required for LT-mediated rat macrophage lysis and contributes to animal death.
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Affiliation(s)
- Zachary L Newman
- Laboratory of Bacterial Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 33 North Drive, Building 33, Room 1W20B, Bethesda, MD 20892, USA.
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Muehlbauer SM, Lima H, Goldman DL, Jacobson LS, Rivera J, Goldberg MF, Palladino MA, Casadevall A, Brojatsch J. Proteasome inhibitors prevent caspase-1-mediated disease in rodents challenged with anthrax lethal toxin. THE AMERICAN JOURNAL OF PATHOLOGY 2010; 177:735-43. [PMID: 20595632 DOI: 10.2353/ajpath.2010.090828] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
NOD-like receptors (NLRs) and caspase-1 are critical components of innate immunity, yet their over-activation has been linked to a long list of microbial and inflammatory diseases, including anthrax. The Bacillus anthracis lethal toxin (LT) has been shown to activate the NLR Nalp1b and caspase-1 and to induce many symptoms of the anthrax disease in susceptible murine strains. In this study we tested whether it is possible to prevent LT-mediated disease by pharmacological inhibition of caspase-1. We found that caspase-1 and proteasome inhibitors blocked LT-mediated caspase-1 activation and cytolysis of LT-sensitive (Fischer and Brown-Norway) rat macrophages. The proteasome inhibitor NPI-0052 also prevented disease progression and death in susceptible Fischer rats and increased survival in BALB/c mice after LT challenge. In addition, NPI-0052 blocked rapid disease progression and death in susceptible Fischer rats and BALB/c mice challenged with LT. In contrast, Lewis rats, which harbor LT-resistant macrophages, showed no signs of caspase-1 activation after LT injection and did not exhibit rapid disease progression. Taken together, our findings indicate that caspase-1 activation is critical for rapid disease progression in rodents challenged with LT. Our studies indicate that pharmacological inhibition of NLR signaling and caspase-1 can be used to treat inflammatory diseases.
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Affiliation(s)
- Stefan M Muehlbauer
- Albert Einstein College of Medicine, Department of Microbiology and Immunology, Bronx, NY 10461, USA
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