1
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Jastrab JB, Kagan JC. Strategies of bacterial detection by inflammasomes. Cell Chem Biol 2024; 31:835-850. [PMID: 38636521 PMCID: PMC11103797 DOI: 10.1016/j.chembiol.2024.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/09/2024] [Accepted: 03/26/2024] [Indexed: 04/20/2024]
Abstract
Mammalian innate immunity is regulated by pattern-recognition receptors (PRRs) and guard proteins, which use distinct strategies to detect infections. PRRs detect bacterial molecules directly, whereas guards detect host cell manipulations by microbial virulence factors. Despite sensing infection through different mechanisms, both classes of innate immune sensors can activate the inflammasome, an immune complex that can mediate cell death and inflammation. Inflammasome-mediated immune responses are crucial for host defense against many bacterial pathogens and prevent invasion by non-pathogenic organisms. In this review, we discuss the mechanisms by which inflammasomes are stimulated by PRRs and guards during bacterial infection, and the strategies used by virulent bacteria to evade inflammasome-mediated immunity.
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Affiliation(s)
- Jordan B Jastrab
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA; Division of Infectious Diseases, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Jonathan C Kagan
- Division of Gastroenterology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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2
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Gao X, Teng T, Liu Y, Ai T, Zhao R, Fu Y, Zhang P, Han J, Zhang Y. Anthrax lethal toxin and tumor necrosis factor-α synergize on intestinal epithelia to induce mouse death. Protein Cell 2024; 15:135-148. [PMID: 37855658 PMCID: PMC10833652 DOI: 10.1093/procel/pwad050] [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: 08/16/2023] [Accepted: 09/26/2023] [Indexed: 10/20/2023] Open
Abstract
Bacillus anthracis lethal toxin (LT) is a determinant of lethal anthrax. Its function in myeloid cells is required for bacterial dissemination, and LT itself can directly trigger dysfunction of the cardiovascular system. The interplay between LT and the host responses is important in the pathogenesis, but our knowledge on this interplay remains limited. Tumor necrosis factor-α (TNF-α) is a pleiotropic pro-inflammatory cytokine induced by bacterial infections. Since LT accumulates and cytokines, predominantly TNF, amass during B. anthracis infection, co-treatment of TNF + LT in mice was used to mimic in vivo conditions for LT to function in inflamed hosts. Bone marrow transplantation and genetically engineered mice showed unexpectedly that the death of intestinal epithelial cells (IECs) rather than that of hematopoietic cells led to LT + TNF-induced lethality. Inhibition of p38α mitogen-activated protein kinase (MAPK) signaling by LT in IECs promoted TNF-induced apoptosis and necroptosis of IECs, leading to intestinal damage and mouse death. Consistently, p38α inhibition by LT enhanced TNF-mediated cell death in human colon epithelial HT-29 cells. As intestinal damage is one of the leading causes of lethality in anthrax patients, the IEC damage caused by LT + TNF would most likely be a mechanism underneath this clinical manifestation and could be a target for interventions.
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Affiliation(s)
- Xinhe Gao
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Teng Teng
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Yifei Liu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Tingting Ai
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Rui Zhao
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Yilong Fu
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Peipei Zhang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Jiahuai Han
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
- Research Unit of Cellular Stress of CAMS, Xiang’an Hospital of Xiamen University, Cancer Research Center of Xiamen University, School of Medicine, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
- Laboratory Animal Center, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
| | - Yingying Zhang
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Faculty of Medicine and Life Sciences, Xiamen University, Xiamen 361102, China
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3
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Bothra A, Perry ML, Wei E, Moayeri M, Ma Q, Biamonte MA, Siirin M, Leppla SH. S9.6-based hybrid capture immunoassay for pathogen detection. Sci Rep 2023; 13:22562. [PMID: 38110611 PMCID: PMC10728093 DOI: 10.1038/s41598-023-49881-w] [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: 10/20/2023] [Accepted: 12/13/2023] [Indexed: 12/20/2023] Open
Abstract
The detection of pathogens is critical for clinical diagnosis and public health surveillance. Detection is usually done with nucleic acid-based tests (NATs) and rapid antigen tests (e.g., lateral flow assays [LFAs]). Although NATs are more sensitive and specific, their use is often limited in resource-poor settings due to specialized requirements. To address this limitation, we developed a rapid DNA-RNA Hybrid Capture immunoassay (HC) that specifically detects RNA from pathogens. This assay utilizes a unique monoclonal antibody, S9.6, which binds DNA-RNA hybrids. Biotinylated single-stranded DNA probes are hybridized to target RNAs, followed by hybrid capture on streptavidin and detection with S9.6. The HC-ELISA assay can detect as few as 104 RNA molecules that are 2.2 kb in length. We also adapted this assay into a LFA format, where captured Bacillus anthracis rpoB RNA of 3.5 kb length was detectable from a bacterial load equivalent to 107 CFU per 100 mg of mouse tissue using either HC-ELISA or HC-LFA. Importantly, we also demonstrated the versatility of HC by detecting other pathogens, including SARS-CoV-2 and Toxoplasma gondii, showing its potential for broad pathogen detection. Notably, HC does not require amplification of the target nucleic acid and utilizes economical formats like ELISA and LFA, making it suitable for use in sentinel labs for pathogen detection or as a molecular tool in basic research laboratories. Our study highlights the potential of HC as a sensitive and versatile method for RNA-based pathogen detection.
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Affiliation(s)
- Ankur Bothra
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA.
| | - Megan L Perry
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Elena Wei
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Mahtab Moayeri
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Qian Ma
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | | | - Marina Siirin
- Drugs and Diagnostics for Tropical Diseases, San Diego, CA, USA
| | - Stephen H Leppla
- Microbial Pathogenesis Section, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
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4
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Castro LK, Daugherty MD. Tripping the wire: sensing of viral protease activity by CARD8 and NLRP1 inflammasomes. Curr Opin Immunol 2023; 83:102354. [PMID: 37311351 PMCID: PMC10528193 DOI: 10.1016/j.coi.2023.102354] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/11/2023] [Accepted: 05/14/2023] [Indexed: 06/15/2023]
Abstract
Host innate immune sensors are vital for the initial detection of pathogen infection. Such sensors thus need to constantly adapt in escalating evolutionary arms races with pathogens. Recently, two inflammasome-forming proteins, CARD8 and NLRP1, have emerged as innate immune sensors for the enzymatic activity of virus-encoded proteases. When cleaved within a rapidly evolving 'tripwire' region, CARD8 and NLRP1 assemble into inflammasomes that initiate pyroptotic cell death and pro-inflammatory cytokine release as a form of effector-triggered immunity. Short motifs in the CARD8 and NLRP1 tripwires mimic the protease-specific cleavage sites of picornaviruses, coronaviruses, and HIV-1, providing virus-specific sensing that can rapidly change between closely related hosts and within the human population. Recent work highlights the evolutionary arms races between viral proteases and NLRP1 and CARD8, including insights into the mechanisms of inflammasome activation, host diversity of viral sensing, and means that viruses have evolved to avoid tripping the wire.
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Affiliation(s)
- Lennice K Castro
- Department of Molecular Biology, School of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Matthew D Daugherty
- Department of Molecular Biology, School of Biological Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
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5
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Abstract
The biggest challenge to immune control of HIV infection is the rapid within-host viral evolution, which allows selection of viral variants that escape from T cell and antibody recognition. Thus, it is impossible to clear HIV infection without targeting "immutable" components of the virus. Unlike the adaptive immune system that recognizes cognate epitopes, the CARD8 inflammasome senses the essential enzymatic activity of the HIV-1 protease, which is immutable for the virus. Hence, all subtypes of HIV clinical isolates can be recognized by CARD8. In HIV-infected cells, the viral protease is expressed as a subunit of the viral Gag-Pol polyprotein and remains functionally inactive prior to viral budding. A class of anti-HIV drugs, the non-nucleoside reverse transcriptase inhibitors (NNRTIs), can promote Gag-pol dimerization and subsequent premature intracellular activation of the viral protease. NNRTI treatment triggers CARD8 inflammasome activation, which leads to pyroptosis of HIV-infected CD4+ T cells and macrophages. Targeting the CARD8 inflammasome can be a potent and broadly effective strategy for HIV eradication.
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Affiliation(s)
- Kolin M Clark
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
| | - Priya Pal
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
| | - Josh G Kim
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
| | - Qiankun Wang
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States
| | - Liang Shan
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, Saint Louis, MO, United States; Andrew M. and Jane M. Bursky Center for Human Immunology and Immunotherapy Programs, Washington University School of Medicine, Saint Louis, MO, United States.
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6
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Nilsson P, Ravinet M, Cui Y, Berg PR, Zhang Y, Guo R, Luo T, Song Y, Trucchi E, Hoff SNK, Lv R, Schmid BV, Easterday WR, Jakobsen KS, Stenseth NC, Yang R, Jentoft S. Polygenic plague resistance in the great gerbil uncovered by population sequencing. PNAS NEXUS 2022; 1:pgac211. [PMID: 36712379 PMCID: PMC9802093 DOI: 10.1093/pnasnexus/pgac211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 09/15/2022] [Accepted: 09/27/2022] [Indexed: 06/18/2023]
Abstract
Pathogens can elicit high selective pressure on hosts, potentially altering genetic diversity over short evolutionary timescales. Intraspecific variation in immune response is observable as variable survivability from specific infections. The great gerbil (Rhombomys opimus) is a rodent plague host with a heterogenic but highly resistant phenotype. Here, we investigate the genomic basis for plague-resistant phenotypes by exposing wild-caught great gerbils to plague (Yersinia pestis). Whole genome sequencing of 10 survivors and 10 moribund individuals revealed a subset of genomic regions showing elevated differentiation. Gene ontology analysis of candidate genes in these regions demonstrated enrichment of genes directly involved in immune functions, cellular metabolism and the regulation of apoptosis as well as pathways involved in transcription, translation, and gene regulation. Transcriptomic analysis revealed that the early activated great gerbil immune response to plague consisted of classical components of the innate immune system. Our approach combining challenge experiments with transcriptomics and population level sequencing, provides new insight into the genetic background of plague-resistance and confirms its complex nature, most likely involving multiple genes and pathways of both the immune system and regulation of basic cellular functions.
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Affiliation(s)
- Pernille Nilsson
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 0371 Oslo, Norway
| | | | | | | | | | - Rong Guo
- Xinjiang Center for Disease Control and Prevention, Urumqi 830002, China
| | - Tao Luo
- Xinjiang Center for Disease Control and Prevention, Urumqi 830002, China
| | - Yajun Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Emiliano Trucchi
- Department of Life and Environmental Sciences, Marche Polytechnic University, Via Brecce Bianche, 60131 Ancona, Italy
| | - Siv N K Hoff
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 0371 Oslo, Norway
| | - Ruichen Lv
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing 100071, China
| | - Boris V Schmid
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 0371 Oslo, Norway
| | - W Ryan Easterday
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 0371 Oslo, Norway
| | | | | | - Ruifu Yang
- To whom correspondence should be addressed:
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7
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Wei X, Xie F, Zhou X, Wu Y, Yan H, Liu T, Huang J, Wang F, Zhou F, Zhang L. Role of pyroptosis in inflammation and cancer. Cell Mol Immunol 2022; 19:971-992. [PMID: 35970871 PMCID: PMC9376585 DOI: 10.1038/s41423-022-00905-x] [Citation(s) in RCA: 217] [Impact Index Per Article: 108.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 07/11/2022] [Indexed: 12/13/2022] Open
Abstract
Pyroptosis is a form of programmed cell death mediated by gasdermin and is a product of continuous cell expansion until the cytomembrane ruptures, resulting in the release of cellular contents that can activate strong inflammatory and immune responses. Pyroptosis, an innate immune response, can be triggered by the activation of inflammasomes by various influencing factors. Activation of these inflammasomes can induce the maturation of caspase-1 or caspase-4/5/11, both of which cleave gasdermin D to release its N-terminal domain, which can bind membrane lipids and perforate the cell membrane. Here, we review the latest advancements in research on the mechanisms of pyroptosis, newly discovered influencing factors, antitumoral properties, and applications in various diseases. Moreover, this review also provides updates on potential targeted therapies for inflammation and cancers, methods for clinical prevention, and finally challenges and future directions in the field.
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Affiliation(s)
- Xiang Wei
- International Biomed-X Research Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, PR China
| | - Feng Xie
- Institutes of Biology and Medical Science, Soochow University, Suzhou, 215123, PR China
| | - Xiaoxue Zhou
- MOE Key Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, 310058, PR China
| | - Yuchen Wu
- Department of Clinical Medicine, The First School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, 325035, PR China
| | - Haiyan Yan
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, 310015, PR China
| | - Ting Liu
- Department of Cell Biology and Department of General Surgery of Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, Zhejiang, PR China
| | - Jun Huang
- Zhejiang Provincial Key Lab of Geriatrics and Geriatrics Institute of Zhejiang Province, Department of Geriatrics, Zhejiang Hospital, Hangzhou, Zhejiang, 310030, PR China.
- Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, 310058, PR China.
| | - Fangwei Wang
- MOE Key Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, 310058, PR China.
| | - Fangfang Zhou
- Institutes of Biology and Medical Science, Soochow University, Suzhou, 215123, PR China.
| | - Long Zhang
- International Biomed-X Research Center, Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, PR China.
- MOE Key Laboratory of Biosystems Homeostasis & Protection and Innovation Center for Cell Signaling Network, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang, 310058, PR China.
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8
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Activation and manipulation of inflammasomes and pyroptosis during bacterial infections. Biochem J 2022; 479:867-882. [PMID: 35438136 DOI: 10.1042/bcj20220051] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/29/2022] [Accepted: 04/04/2022] [Indexed: 12/17/2022]
Abstract
Following detection of pathogen infection and disrupted cellular homeostasis, cells can activate a range of cell death pathways, such as apoptosis, necroptosis and pyroptosis, as part of their defence strategy. The initiation of pro-inflammatory, lytic pyroptosis is controlled by inflammasomes, which respond to a range of cellular perturbations. As is true for many host defence pathways, pathogens have evolved multiple mechanisms to subvert this pathway, many of which have only recently been described. Herein, we will discuss the mechanisms by which inflammasomes sense pathogen invasion and initiate pyroptosis and the effector mechanisms used by pathogens to suppress this pathway and preserve their niche.
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9
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Churchill MJ, Mitchell PS, Rauch I. Epithelial Pyroptosis in Host Defense. J Mol Biol 2022; 434:167278. [PMID: 34627788 PMCID: PMC10010195 DOI: 10.1016/j.jmb.2021.167278] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/17/2021] [Accepted: 09/25/2021] [Indexed: 12/28/2022]
Abstract
Pyroptosis is a lytic form of cell death that is executed by a family of pore-forming proteins called gasdermins (GSDMs). GSDMs are activated upon proteolysis by host proteases including the proinflammatory caspases downstream of inflammasome activation. In myeloid cells, GSDM pore formation serves two primary functions in host defense: the selective release of processed cytokines to initiate inflammatory responses, and cell death, which eliminates a replicative niche of the pathogen. Barrier epithelia also undergo pyroptosis. However, unique mechanisms are required for the removal of pyroptotic epithelial cells to maintain epithelial barrier integrity. In the following review, we discuss the role of epithelial inflammasomes and pyroptosis in host defense against pathogens. We use the well-established role of inflammasomes in intestinal epithelia to highlight principles of epithelial pyroptosis in host defense of barrier tissues, and discuss how these principles might be shared or distinctive across other epithelial sites.
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Affiliation(s)
- Madeline J Churchill
- Department of Molecular Microbiology & Immunology, Oregon Health and Science University, Portland, OR, USA
| | | | - Isabella Rauch
- Department of Molecular Microbiology & Immunology, Oregon Health and Science University, Portland, OR, USA.
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10
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Woida PJ, Satchell KJF. Bacterial Toxin and Effector Regulation of Intestinal Immune Signaling. Front Cell Dev Biol 2022; 10:837691. [PMID: 35252199 PMCID: PMC8888934 DOI: 10.3389/fcell.2022.837691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/24/2022] [Indexed: 11/13/2022] Open
Abstract
The host immune response is highly effective to detect and clear infecting bacterial pathogens. Given the elaborate surveillance systems of the host, it is evident that in order to productively infect a host, the bacteria often coordinate virulence factors to fine-tune the host response during infection. These coordinated events can include either suppressing or activating the signaling pathways that control the immune response and thereby promote bacterial colonization and infection. This review will cover the surveillance and signaling systems for detection of bacteria in the intestine and a sample of the toxins and effectors that have been characterized that cirumvent these signaling pathways. These factors that promote infection and disease progression have also been redirected as tools or therapeutics. Thus, these toxins are enemies deployed to enhance infection, but can also be redeployed as allies to enable research and protect against infection.
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11
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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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12
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Tsu BV, Fay EJ, Nguyen KT, Corley MR, Hosuru B, Dominguez VA, Daugherty MD. Running With Scissors: Evolutionary Conflicts Between Viral Proteases and the Host Immune System. Front Immunol 2021; 12:769543. [PMID: 34790204 PMCID: PMC8591160 DOI: 10.3389/fimmu.2021.769543] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 10/08/2021] [Indexed: 12/28/2022] Open
Abstract
Many pathogens encode proteases that serve to antagonize the host immune system. In particular, viruses with a positive-sense single-stranded RNA genome [(+)ssRNA], including picornaviruses, flaviviruses, and coronaviruses, encode proteases that are not only required for processing viral polyproteins into functional units but also manipulate crucial host cellular processes through their proteolytic activity. Because these proteases must cleave numerous polyprotein sites as well as diverse host targets, evolution of these viral proteases is expected to be highly constrained. However, despite this strong evolutionary constraint, mounting evidence suggests that viral proteases such as picornavirus 3C, flavivirus NS3, and coronavirus 3CL, are engaged in molecular 'arms races' with their targeted host factors, resulting in host- and virus-specific determinants of protease cleavage. In cases where protease-mediated cleavage results in host immune inactivation, recurrent host gene evolution can result in avoidance of cleavage by viral proteases. In other cases, such as recently described examples in NLRP1 and CARD8, hosts have evolved 'tripwire' sequences that mimic protease cleavage sites and activate an immune response upon cleavage. In both cases, host evolution may be responsible for driving viral protease evolution, helping explain why viral proteases and polyprotein sites are divergent among related viruses despite such strong evolutionary constraint. Importantly, these evolutionary conflicts result in diverse protease-host interactions even within closely related host and viral species, thereby contributing to host range, zoonotic potential, and pathogenicity of viral infection. Such examples highlight the importance of examining viral protease-host interactions through an evolutionary lens.
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Affiliation(s)
| | | | | | | | | | | | - Matthew D. Daugherty
- Division of Biological Sciences, University of California, San Diego, CA, United States
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13
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Ta A, Vanaja SK. Inflammasome activation and evasion by bacterial pathogens. Curr Opin Immunol 2021; 68:125-133. [PMID: 33338767 PMCID: PMC7925435 DOI: 10.1016/j.coi.2020.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/25/2020] [Accepted: 11/22/2020] [Indexed: 12/21/2022]
Abstract
Innate immune system plays an essential role in combating infectious diseases by recognizing invading pathogens and activating host defense response. Inflammasomes complexes are a central component of the cytosolic innate immune surveillance and are vital in host defense against bacterial pathogens. Bacterial products or pathogen-induced modifications in the intracellular environment are sensed by the inflammasome receptors that form complexes that serve as a platform for caspase-1-dependent or caspase-11-dependent induction of pyroptosis and secretion of cytokines, IL-1β and IL-18. However, several pathogenic bacteria have developed strategies to evade inflammasome activation. This review highlights the recent advances in the mechanism of inflammasome activation by bacterial pathogens and some of the bacterial evasion strategies of inflammasome activation.
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Affiliation(s)
- Atri Ta
- Department of Immunology, UConn Health School of Medicine, 263 Farmington Ave, Farmington, CT 06030, USA
| | - Sivapriya Kailasan Vanaja
- Department of Immunology, UConn Health School of Medicine, 263 Farmington Ave, Farmington, CT 06030, USA.
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14
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Tsu BV, Beierschmitt C, Ryan AP, Agarwal R, Mitchell PS, Daugherty MD. Diverse viral proteases activate the NLRP1 inflammasome. eLife 2021; 10:60609. [PMID: 33410748 PMCID: PMC7857732 DOI: 10.7554/elife.60609] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 01/06/2021] [Indexed: 12/29/2022] Open
Abstract
The NLRP1 inflammasome is a multiprotein complex that is a potent activator of inflammation. Mouse NLRP1B can be activated through proteolytic cleavage by the bacterial Lethal Toxin (LeTx) protease, resulting in degradation of the N-terminal domains of NLRP1B and liberation of the bioactive C-terminal domain, which includes the caspase activation and recruitment domain (CARD). However, natural pathogen-derived effectors that can activate human NLRP1 have remained unknown. Here, we use an evolutionary model to identify several proteases from diverse picornaviruses that cleave human NLRP1 within a rapidly evolving region of the protein, leading to host-specific and virus-specific activation of the NLRP1 inflammasome. Our work demonstrates that NLRP1 acts as a 'tripwire' to recognize the enzymatic function of a wide range of viral proteases and suggests that host mimicry of viral polyprotein cleavage sites can be an evolutionary strategy to activate a robust inflammatory immune response. The immune system recognizes disease-causing microbes, such as bacteria and viruses, and removes them from the body before they can cause harm. When the immune system first detects these foreign invaders, a multi-part structure known as the inflammasome launches an inflammatory response to help fight the microbes off. Several sensor proteins can activate the inflammasome, including one in mice called NLRP1B. This protein has evolved a specialized site that can be cut by a bacterial toxin. Once cleaved, this region acts like a biological tripwire and sparks NLRP1B into action, allowing the sensor to activate the inflammasome system. Humans have a similar protein called NLRP1, but it is unclear whether this protein has also evolved a tripwire region that can sense microbial proteins. To answer this question, Tsu, Beierschmitt et al. set out to find whether NLRP1 can be activated by viruses in the Picornaviridae family, which are responsible for diseases like polio, hepatitis A, and the common cold. This revealed that NLRP1 contains a cleavage site for enzymes produced by some, but not all, of the viruses in the picornavirus family. Further experiments confirmed that when a picornavirus enzyme cuts through this region during a viral infection, it triggers NLRP1 to activate the inflammasome and initiate an immune response. The enzymes from different viruses were also found to cleave human NLRP1 at different sites, and the protein’s susceptibility to cleavage varied between different animal species. For instance, Tsu, Beierschmitt et al. discovered that NLRP1B in mice is also able to sense picornaviruses, and that different enzymes activate and cleave NLRP1B and NLRP1 to varying degrees: this affected how well the two proteins are expected to be able to sense specific viral infections. This variation suggests that there is an ongoing evolutionary arms-race between viral proteins and the immune system: as viral proteins change and new ones emerge, NLRP1 rapidly evolves new tripwire sites that allow it to sense the infection and launch an inflammatory response. What happens when NLRP1B activates the inflammasome during a viral infection is still an open question. The discovery that mouse NLRP1B shares features with human NLRP1 could allow the development of animal models to study the role of the tripwire in antiviral defenses and the overactive inflammation associated with some viral infections. Understanding the types of viruses that activate the NLRP1 inflammasome, and the outcomes of the resulting immune response, may have implications for future treatments of viral infections.
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Affiliation(s)
- Brian V Tsu
- Division of Biological Sciences, University of California San Diego, San Diego, United States
| | | | - Andrew P Ryan
- Division of Biological Sciences, University of California San Diego, San Diego, United States
| | - Rimjhim Agarwal
- Division of Immunology & Pathogenesis, University of California Berkeley, Berkeley, United States
| | - Patrick S Mitchell
- Division of Immunology & Pathogenesis, University of California Berkeley, Berkeley, United States.,Department of Microbiology, University of Washington, Seattle, United States
| | - Matthew D Daugherty
- Division of Biological Sciences, University of California San Diego, San Diego, United States
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15
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Complementary regulation of caspase-1 and IL-1β reveals additional mechanisms of dampened inflammation in bats. Proc Natl Acad Sci U S A 2020; 117:28939-28949. [PMID: 33106404 DOI: 10.1073/pnas.2003352117] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Bats have emerged as unique mammalian vectors harboring a diverse range of highly lethal zoonotic viruses with minimal clinical disease. Despite having sustained complete genomic loss of AIM2, regulation of the downstream inflammasome response in bats is unknown. AIM2 sensing of cytoplasmic DNA triggers ASC aggregation and recruits caspase-1, the central inflammasome effector enzyme, triggering cleavage of cytokines such as IL-1β and inducing GSDMD-mediated pyroptotic cell death. Restoration of AIM2 in bat cells led to intact ASC speck formation, but intriguingly resulted in a lack of caspase-1 or consequent IL-1β activation. We further identified two residues undergoing positive selection pressures in Pteropus alecto caspase-1 that abrogate its enzymatic function and are crucial in human caspase-1 activity. Functional analysis of another bat lineage revealed a targeted mechanism for loss of Myotis davidii IL-1β cleavage and elucidated an inverse complementary relationship between caspase-1 and IL-1β, resulting in overall diminished signaling across bats of both suborders. Thus we report strategies that additionally undermine downstream inflammasome signaling in bats, limiting an overactive immune response against pathogens while potentially producing an antiinflammatory state resistant to diseases such as atherosclerosis, aging, and neurodegeneration.
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16
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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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17
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Popescu NI, Keshari RS, Cochran J, Coggeshall KM, Lupu F. C3 Opsonization of Anthrax Bacterium and Peptidoglycan Supports Recognition and Activation of Neutrophils. Microorganisms 2020; 8:E1039. [PMID: 32668703 PMCID: PMC7409185 DOI: 10.3390/microorganisms8071039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/08/2020] [Accepted: 07/11/2020] [Indexed: 12/01/2022] Open
Abstract
Neutrophils are the most abundant innate cell population and a key immune player against invading pathogens. Neutrophils can kill both bacterium and spores of Bacillus anthracis, the causative anthrax pathogen. Unlike interactions with professional phagocytes, the molecular recognition of anthrax by neutrophils is largely unknown. In this study, we investigated the role of complement C3 deposition on anthrax particles for neutrophil recognition of bacterium and/or its cell wall peptidoglycan, an abundant pathogen-associated molecular pattern that supports anthrax sepsis. C3 opsonization and recognition by complement receptors accounted for 70-80% of the affinity interactions between neutrophils and anthrax particles at subphysiologic temperatures. In contrast, C3 supported up to 50% of the anthrax particle ingestion under thermophysiologic conditions. Opsonin-dependent low affinity interactions and, to a lower extent, opsonin-independent mechanisms, provide alternative entry routes. Similarly, C3 supported 58% of peptidoglycan-induced degranulation and, to a lower extent, 23% of bacterium-induced degranulation. Interestingly, an opsonin independent mechanism mediated by complement C5, likely through C5a anaphylatoxin, primes azurophilic granules in response to anthrax particles. Overall, we show that C3 deposition supports anthrax recognition by neutrophils but is dispensable for pathogen ingestion and neutrophil degranulation, highlighting immune recognition redundancies that minimize the risk of pathogen evasion.
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Affiliation(s)
- Narcis I. Popescu
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; (J.C.); (K.M.C.)
| | - Ravi S. Keshari
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA;
| | - Jackie Cochran
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; (J.C.); (K.M.C.)
| | - K. Mark Coggeshall
- Department of Arthritis and Clinical Immunology, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA; (J.C.); (K.M.C.)
| | - Florea Lupu
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA;
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18
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Taabazuing CY, Griswold AR, Bachovchin DA. The NLRP1 and CARD8 inflammasomes. Immunol Rev 2020; 297:13-25. [PMID: 32558991 PMCID: PMC7483925 DOI: 10.1111/imr.12884] [Citation(s) in RCA: 106] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/06/2020] [Accepted: 05/14/2020] [Indexed: 12/28/2022]
Abstract
Inflammasomes are multiprotein complexes that activate inflammatory cytokines and induce pyroptosis in response to intracellular danger-associated signals. NLRP1 and CARD8 are related germline-encoded pattern recognition receptors that form inflammasomes, but their activation mechanisms and biological purposes have not yet been fully established. Both NLRP1 and CARD8 undergo post-translational autoproteolysis to generate two non-covalently associated polypeptide chains. NLRP1 and CARD8 activators induce the proteasome-mediated destruction of the N-terminal fragment, liberating the C-terminal fragment to form an inflammasome. Here, we review the danger-associated stimuli that have been reported to activate NLRP1 and/or CARD8, including anthrax lethal toxin, Toxoplasma gondii, Shigella flexneri and the small molecule DPP8/9 inhibitor Val-boroPro, focusing on recent mechanistic insights and highlighting unresolved questions. In addition, we discuss the recently identified disease-associated mutations in NLRP1 and CARD8, the potential role that DPP9's protein structure plays in inflammasome regulation, and the emerging link between NLRP1 and metabolism. Finally, we summarize all of this latest research and consider the possible biological purposes of these enigmatic inflammasomes.
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Affiliation(s)
| | - Andrew R Griswold
- Weill Cornell, Rockefeller, Sloan Kettering Tri-Institutional MD-PhD Program, New York, NY, USA.,Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Daniel A Bachovchin
- Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Tri-Institutional PhD Program in Chemical Biology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.,Pharmacology Program of the Weill Cornell Graduate School of Medical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, USA
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19
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ROS-associated immune response and metabolism: a mechanistic approach with implication of various diseases. Arch Toxicol 2020; 94:2293-2317. [PMID: 32524152 DOI: 10.1007/s00204-020-02801-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 06/02/2020] [Indexed: 12/14/2022]
Abstract
The immune system plays a pivotal role in maintaining the defense mechanism against external agents and also internal danger signals. Metabolic programming of immune cells is required for functioning of different subsets of immune cells under different physiological conditions. The field of immunometabolism has gained ground because of its immense importance in coordination and balance of immune responses. Metabolism is very much related with production of energy and certain by-products. Reactive oxygen species (ROS) are generated as one of the by-products of various metabolic pathways. The amount, localization of ROS and redox status determine transcription of genes, and also influences the metabolism of immune cells. This review discusses ROS, metabolism of immune cells at different cellular conditions and sheds some light on how ROS might regulate immunometabolism.
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20
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Mazgaeen L, Gurung P. Neutro"feels" lethal toxin. J Leukoc Biol 2020; 108:769-772. [PMID: 32401416 DOI: 10.1002/jlb.4ce0320-101r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Discussion on lethal toxin-induced acute IL-1β production as dependent on NLRP1b and caspase-1, PAD4, cell-free DNA and neutrophils.
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Affiliation(s)
- Lalita Mazgaeen
- Inflammation Program, Infectious Diseases Division, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA.,Human Toxicology Graduate Program, University of Iowa, Iowa City, Iowa, USA
| | - Prajwal Gurung
- Inflammation Program, Infectious Diseases Division, Department of Internal Medicine, University of Iowa, Iowa City, Iowa, USA.,Human Toxicology Graduate Program, University of Iowa, Iowa City, Iowa, USA.,Immunology Graduate Program, University of Iowa, Iowa City, Iowa, USA.,Center for Immunology and Immune Based Diseases, University of Iowa, Iowa City, Iowa, USA
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21
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de Vasconcelos NM, Lamkanfi M. Recent Insights on Inflammasomes, Gasdermin Pores, and Pyroptosis. Cold Spring Harb Perspect Biol 2020; 12:cshperspect.a036392. [PMID: 31570336 DOI: 10.1101/cshperspect.a036392] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Inflammasomes assemble in the cytosol of myeloid and epithelial cells on sensing of cellular stress and pathogen-associated molecular patterns and serve as scaffolds for recruitment and activation of inflammatory caspases. Inflammasomes play beneficial roles in host and immune responses against diverse pathogens but may also promote inflammatory tissue damage if uncontrolled. Gasdermin D (GSDMD) is a recently identified substrate of murine caspase-1 and caspase-11, and human caspases-1, -4, and -5 that mediates a regulated lytic cell death mode termed pyroptosis. Recent studies have identified pyroptosis as a critical inflammasome effector mechanism that controls inflammasome-dependent cytokine secretion and contributes to antimicrobial defense and inflammasome-mediated autoinflammatory diseases. Here, we review recent developments on inflammasome-associated effector functions with an emphasis on the emerging roles of gasdermin pores and pyroptosis.
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Affiliation(s)
- Nathalia M de Vasconcelos
- Department of Internal Medicine and Pediatrics, Ghent University, B-9000 Ghent, Belgium.,VIB-UGhent Center for Inflammation Research, VIB, B-9052 Ghent, Belgium
| | - Mohamed Lamkanfi
- Department of Internal Medicine and Pediatrics, Ghent University, B-9000 Ghent, Belgium.,Janssen Immunosciences, World Without Disease Accelerator, Pharmaceutical Companies of Johnson & Johnson, B-2340 Beerse, Belgium
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22
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Noll KE, Whitmore AC, West A, McCarthy MK, Morrison CR, Plante KS, Hampton BK, Kollmus H, Pilzner C, Leist SR, Gralinski LE, Menachery VD, Schäfer A, Miller D, Shaw G, Mooney M, McWeeney S, Pardo-Manuel de Villena F, Schughart K, Morrison TE, Baric RS, Ferris MT, Heise MT. Complex Genetic Architecture Underlies Regulation of Influenza-A-Virus-Specific Antibody Responses in the Collaborative Cross. Cell Rep 2020; 31:107587. [PMID: 32348764 PMCID: PMC7195006 DOI: 10.1016/j.celrep.2020.107587] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 02/20/2020] [Accepted: 04/08/2020] [Indexed: 02/07/2023] Open
Abstract
Host genetic factors play a fundamental role in regulating humoral immunity to viral infection, including influenza A virus (IAV). Here, we utilize the Collaborative Cross (CC), a mouse genetic reference population, to study genetic regulation of variation in antibody response following IAV infection. CC mice show significant heritable variation in the magnitude, kinetics, and composition of IAV-specific antibody response. We map 23 genetic loci associated with this variation. Analysis of a subset of these loci finds that they broadly affect the antibody response to IAV as well as other viruses. Candidate genes are identified based on predicted variant consequences and haplotype-specific expression patterns, and several show overlap with genes identified in human mapping studies. These findings demonstrate that the host antibody response to IAV infection is under complex genetic control and highlight the utility of the CC in modeling and identifying genetic factors with translational relevance to human health and disease.
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Affiliation(s)
- Kelsey E Noll
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Alan C Whitmore
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ande West
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mary K McCarthy
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA
| | | | - Kenneth S Plante
- Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Brea K Hampton
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Heike Kollmus
- Department of Infection Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Carolin Pilzner
- Department of Infection Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Sarah R Leist
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Infection Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Lisa E Gralinski
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Vineet D Menachery
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Microbiology and Immunology, University of Texas Medical Branch at Galveston, Galveston, TX, USA
| | - Alexandra Schäfer
- Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Darla Miller
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Ginger Shaw
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Michael Mooney
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, OR, USA; OHSU Knight Cancer Center Institute, Oregon Health and Science University, Portland, OR, USA
| | - Shannon McWeeney
- Division of Bioinformatics and Computational Biology, Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science University, Portland, OR, USA; OHSU Knight Cancer Center Institute, Oregon Health and Science University, Portland, OR, USA; Oregon Clinical and Translational Research Institute, Oregon Health and Science University, Portland, OR, USA
| | - Fernando Pardo-Manuel de Villena
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Klaus Schughart
- Department of Infection Genetics, Helmholtz Centre for Infection Research, Braunschweig, Germany; University of Veterinary Medicine Hannover, Hannover, Germany; Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Thomas E Morrison
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Ralph S Baric
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Epidemiology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA
| | - Martin T Ferris
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mark T Heise
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, USA.
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23
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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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24
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Vrentas CE, Boggiatto PM, Olsen SC, Leppla SH, Moayeri M. Characterization of the NLRP1 inflammasome response in bovine species. Innate Immun 2019; 26:301-311. [PMID: 31711335 PMCID: PMC7251794 DOI: 10.1177/1753425919886649] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Inflammasomes act as sensors of infection or damage to initiate immune responses.
While extensively studied in rodents, understanding of livestock inflammasomes
is limited. The NLRP1 inflammasome sensor in rodents is activated by
Toxoplasma gondii, Bacillus anthracis
lethal toxin (LT), and potentially other zoonotic pathogens. LT activates NLRP1
by N-terminal proteolysis, inducing macrophage pyroptosis and a pro-inflammatory
cytokine response. In contrast, NLRP1 in macrophages from humans and certain
rodent strains is resistant to LT cleavage, and pyroptosis is not induced.
Evolution of NLRP1 sequences towards those leading to pyroptosis is of interest
in understanding innate immune responses in different hosts. We characterized
NLRP1 in cattle (Bos taurus) and American bison (Bison
bison). Bovine NLRP1 is not cleaved by LT, and cattle and bison
macrophages do not undergo toxin-induced pyroptosis. Additionally, we found a
predicted Nlrp1 splicing isoform in cattle macrophages lacking
the N-terminal domain. Resistance to LT in bovine and human NLRP1 correlates
with evolutionary sequence similarity to rodents. Consistent with LT-resistant
rodents, bovine macrophages undergo a slower non-pyroptotic death in the
presence of LPS and LT. Overall, our findings support the model that NLRP1
activation by LT requires N-terminal cleavage, and provide novel information on
mechanisms underlying immune response diversity.
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Affiliation(s)
- Catherine E Vrentas
- Infectious Bacterial Diseases Unit, National Animal Disease
Center, Agricultural Research Service, US Department of Agriculture, Ames,
USA
- Catherine E Vrentas, Infectious Bacterial
Diseases Unit, National Animal Disease Center, Agricultural Research Service, US
Department of Agriculture, Ames, IA 50010, USA.
| | - Paola M Boggiatto
- Infectious Bacterial Diseases Unit, National Animal Disease
Center, Agricultural Research Service, US Department of Agriculture, Ames,
USA
| | - Steven C Olsen
- Infectious Bacterial Diseases Unit, National Animal Disease
Center, Agricultural Research Service, US Department of Agriculture, Ames,
USA
| | - Stephen H Leppla
- Laboratory of Parasitic Diseases, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Bethesda, USA
| | - Mahtab Moayeri
- Laboratory of Parasitic Diseases, National Institute of Allergy
and Infectious Diseases, National Institutes of Health, Bethesda, USA
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25
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Radaelli E, Santagostino SF, Sellers RS, Brayton CF. Immune Relevant and Immune Deficient Mice: Options and Opportunities in Translational Research. ILAR J 2019; 59:211-246. [PMID: 31197363 PMCID: PMC7114723 DOI: 10.1093/ilar/ily026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/03/2018] [Indexed: 12/29/2022] Open
Abstract
In 1989 ILAR published a list and description of immunodeficient rodents used in research. Since then, advances in understanding of molecular mechanisms; recognition of genetic, epigenetic microbial, and other influences on immunity; and capabilities in manipulating genomes and microbiomes have increased options and opportunities for selecting mice and designing studies to answer important mechanistic and therapeutic questions. Despite numerous scientific breakthroughs that have benefitted from research in mice, there is debate about the relevance and predictive or translational value of research in mice. Reproducibility of results obtained from mice and other research models also is a well-publicized concern. This review summarizes resources to inform the selection and use of immune relevant mouse strains and stocks, aiming to improve the utility, validity, and reproducibility of research in mice. Immune sufficient genetic variations, immune relevant spontaneous mutations, immunodeficient and autoimmune phenotypes, and selected induced conditions are emphasized.
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Affiliation(s)
- Enrico Radaelli
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Sara F Santagostino
- Department of Safety Assessment, Genentech, Inc., South San Francisco, California
| | | | - Cory F Brayton
- Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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26
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Winsor N, Krustev C, Bruce J, Philpott DJ, Girardin SE. Canonical and noncanonical inflammasomes in intestinal epithelial cells. Cell Microbiol 2019; 21:e13079. [PMID: 31265745 DOI: 10.1111/cmi.13079] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/27/2019] [Accepted: 06/28/2019] [Indexed: 12/13/2022]
Abstract
Inflammasomes are cytosolic, multimeric protein complexes capable of activating pro-inflammatory cytokines such as IL-1β and IL-18, which play a key role in host defence. Inflammasome components are highly expressed in the intestinal epithelium. In recent years, studies have begun to demonstrate that epithelial-intrinsic inflammasomes play a critical role in regulating epithelial homeostasis, both by defending the epithelium from pathogenic insult and through the regulation of the mucosal environment. However, the majority of research regarding inflammasome activation has focused on professional immune cells, such as macrophages. Here, we present an overview of the current understanding of inflammasome function in epithelial cells and at mucosal surfaces and, in particular, in the intestine.
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Affiliation(s)
- Nathaniel Winsor
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Christian Krustev
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Jessica Bruce
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
- School of Biomedical Science and Pharmacy, University of Newcastle, Newcastle, New South Wales, Australia
| | - Dana J Philpott
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
| | - Stephen E Girardin
- Department of Immunology, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
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27
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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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28
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Platnich JM, Muruve DA. NOD-like receptors and inflammasomes: A review of their canonical and non-canonical signaling pathways. Arch Biochem Biophys 2019; 670:4-14. [PMID: 30772258 DOI: 10.1016/j.abb.2019.02.008] [Citation(s) in RCA: 240] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/11/2019] [Accepted: 02/13/2019] [Indexed: 12/16/2022]
Abstract
The NOD-like receptor (NLR) family of proteins is a group of pattern recognition receptors (PRRs) known to mediate the initial innate immune response to cellular injury and stress. The NLRP proteins represent a fourteen-member subset of the NLR family that contains an N-terminal pyrin domain. Some NLRs are known to form multi-protein complexes known as inflammasomes. Inflammasomes consist of an NLR, the adaptor protein ASC, and the effector molecule pro-caspase-1. Once activated, these inflammasomes facilitate the cleavage and activation of caspase-1, which in turn mediates the cleavage of the pro-inflammatory cytokines IL-1β and IL-18 into their active and secreted forms. Activated caspase-1 also drives the cleavage of gasdermin D, which triggers an inflammatory form of cell death known as pyroptosis. Several NLRs are also known to possess non-canonical, inflammasome-independent functions, regulating a variety of signaling pathways. In this review, a thorough overview of both inflammasome-dependent and -independent NLR signaling will be presented, with highlights from the field as well as promising future directions and postulates based on the known science.
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Affiliation(s)
- Jaye M Platnich
- Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Daniel A Muruve
- Department of Medicine, University of Calgary, Calgary, AB, Canada; Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada.
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29
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de Vasconcelos NM, Vliegen G, Gonçalves A, De Hert E, Martín-Pérez R, Van Opdenbosch N, Jallapally A, Geiss-Friedlander R, Lambeir AM, Augustyns K, Van Der Veken P, De Meester I, Lamkanfi M. DPP8/DPP9 inhibition elicits canonical Nlrp1b inflammasome hallmarks in murine macrophages. Life Sci Alliance 2019; 2:2/1/e201900313. [PMID: 30718379 PMCID: PMC6362307 DOI: 10.26508/lsa.201900313] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 01/25/2019] [Accepted: 01/25/2019] [Indexed: 11/24/2022] Open
Abstract
Activating germline mutations in the human inflammasome sensor NLRP1 causes palmoplantar dyskeratosis and susceptibility to Mendelian autoinflammatory diseases. Recent studies have shown that the cytosolic serine dipeptidyl peptidases DPP8 and DPP9 suppress inflammasome activation upstream of NLRP1 and CARD8 in human keratinocytes and peripheral blood mononuclear cells. Moreover, pharmacological inhibition of DPP8/DPP9 protease activity was shown to induce pyroptosis in murine C57BL/6 macrophages without eliciting other inflammasome hallmark responses. Here, we show that DPP8/DPP9 inhibition in macrophages that express a Bacillus anthracis lethal toxin (LeTx)-sensitive Nlrp1b allele triggered significantly accelerated pyroptosis concomitant with caspase-1 maturation, ASC speck assembly, and secretion of mature IL-1β and IL-18. Genetic ablation of ASC prevented DPP8/DPP9 inhibition-induced caspase-1 maturation and partially hampered pyroptosis and inflammasome-dependent cytokine release, whereas deletion of caspase-1 or gasdermin D triggered apoptosis in the absence of IL-1β and IL-18 secretion. In conclusion, blockade of DPP8/DPP9 protease activity triggers rapid pyroptosis and canonical inflammasome hallmarks in primary macrophages that express a LeTx-responsive Nlrp1b allele.
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Affiliation(s)
- Nathalia M de Vasconcelos
- Department of Internal Medicine, Ghent University, Ghent, Belgium.,VIB-UGhent Center for Inflammation Research, VIB, Ghent, Belgium
| | - Gwendolyn Vliegen
- Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Amanda Gonçalves
- VIB-UGhent Center for Inflammation Research, VIB, Ghent, Belgium.,VIB Bioimaging Core, VIB, Ghent, Belgium.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Emilie De Hert
- Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Rosa Martín-Pérez
- Janssen Immunosciences, World Without Disease Accelerator, Pharmaceutical Companies of Johnson & Johnson, Beerse, Belgium
| | - Nina Van Opdenbosch
- Department of Internal Medicine, Ghent University, Ghent, Belgium.,VIB-UGhent Center for Inflammation Research, VIB, Ghent, Belgium.,Janssen Immunosciences, World Without Disease Accelerator, Pharmaceutical Companies of Johnson & Johnson, Beerse, Belgium
| | - Anvesh Jallapally
- Laboratory of Medicinal Chemistry, Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | | | - Anne-Marie Lambeir
- Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Koen Augustyns
- Laboratory of Medicinal Chemistry, Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Pieter Van Der Veken
- Laboratory of Medicinal Chemistry, Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Ingrid De Meester
- Laboratory of Medical Biochemistry, Department of Pharmaceutical Sciences, University of Antwerp, Antwerp, Belgium
| | - Mohamed Lamkanfi
- Department of Internal Medicine, Ghent University, Ghent, Belgium .,VIB-UGhent Center for Inflammation Research, VIB, Ghent, Belgium.,Janssen Immunosciences, World Without Disease Accelerator, Pharmaceutical Companies of Johnson & Johnson, Beerse, Belgium
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30
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A multicomponent toxin from Bacillus cereus incites inflammation and shapes host outcome via the NLRP3 inflammasome. Nat Microbiol 2018; 4:362-374. [PMID: 30531979 DOI: 10.1038/s41564-018-0318-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Accepted: 11/07/2018] [Indexed: 12/25/2022]
Abstract
Host recognition of microbial components is essential in mediating an effective immune response. Cytosolic bacteria must secure entry into the host cytoplasm to facilitate replication and, in doing so, liberate microbial ligands that activate cytosolic innate immune sensors and the inflammasome. Here, we identified a multicomponent enterotoxin, haemolysin BL (HBL), that engages activation of the inflammasome. This toxin is highly conserved among the human pathogen Bacillus cereus. The three subunits of HBL bind to the cell membrane in a linear order, forming a lytic pore and inducing activation of the NLRP3 inflammasome, secretion of interleukin-1β and interleukin-18, and pyroptosis. Mechanistically, the HBL-induced pore results in the efflux of potassium and triggers the activation of the NLRP3 inflammasome. Furthermore, HBL-producing B. cereus induces rapid inflammasome-mediated mortality. Pharmacological inhibition of the NLRP3 inflammasome using MCC950 prevents B. cereus-induced lethality. Overall, our results reveal that cytosolic sensing of a toxin is central to the innate immune recognition of infection. Therapeutic modulation of this pathway enhances host protection against deadly bacterial infections.
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31
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Cytosolic Recognition of Microbes and Pathogens: Inflammasomes in Action. Microbiol Mol Biol Rev 2018; 82:82/4/e00015-18. [PMID: 30209070 DOI: 10.1128/mmbr.00015-18] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Infection is a dynamic biological process underpinned by a complex interplay between the pathogen and the host. Microbes from all domains of life, including bacteria, viruses, fungi, and protozoan parasites, have the capacity to cause infection. Infection is sensed by the host, which often leads to activation of the inflammasome, a cytosolic macromolecular signaling platform that mediates the release of the proinflammatory cytokines interleukin-1β (IL-1β) and IL-18 and cleavage of the pore-forming protein gasdermin D, leading to pyroptosis. Host-mediated sensing of the infection occurs when pathogens inject or carry pathogen-associated molecular patterns (PAMPs) into the cytoplasm or induce damage that causes cytosolic liberation of danger-associated molecular patterns (DAMPs) in the host cell. Recognition of PAMPs and DAMPs by inflammasome sensors, including NLRP1, NLRP3, NLRC4, NAIP, AIM2, and Pyrin, initiates a cascade of events that culminate in inflammation and cell death. However, pathogens can deploy virulence factors capable of minimizing or evading host detection. This review presents a comprehensive overview of the mechanisms of microbe-induced activation of the inflammasome and the functional consequences of inflammasome activation in infectious diseases. We also explore the microbial strategies used in the evasion of inflammasome sensing at the host-microbe interaction interface.
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32
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Carlson CJ, Getz WM, Kausrud KL, Cizauskas CA, Blackburn JK, Bustos Carrillo FA, Colwell R, Easterday WR, Ganz HH, Kamath PL, Økstad OA, Turner WC, Kolstø AB, Stenseth NC. Spores and soil from six sides: interdisciplinarity and the environmental biology of anthrax (Bacillus anthracis). Biol Rev Camb Philos Soc 2018; 93:1813-1831. [PMID: 29732670 DOI: 10.1111/brv.12420] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 03/27/2018] [Accepted: 04/03/2018] [Indexed: 12/11/2022]
Abstract
Environmentally transmitted diseases are comparatively poorly understood and managed, and their ecology is particularly understudied. Here we identify challenges of studying environmental transmission and persistence with a six-sided interdisciplinary review of the biology of anthrax (Bacillus anthracis). Anthrax is a zoonotic disease capable of maintaining infectious spore banks in soil for decades (or even potentially centuries), and the mechanisms of its environmental persistence have been the topic of significant research and controversy. Where anthrax is endemic, it plays an important ecological role, shaping the dynamics of entire herbivore communities. The complex eco-epidemiology of anthrax, and the mysterious biology of Bacillus anthracis during its environmental stage, have necessitated an interdisciplinary approach to pathogen research. Here, we illustrate different disciplinary perspectives through key advances made by researchers working in Etosha National Park, a long-term ecological research site in Namibia that has exemplified the complexities of the enzootic process of anthrax over decades of surveillance. In Etosha, the role of scavengers and alternative routes (waterborne transmission and flies) has proved unimportant relative to the long-term persistence of anthrax spores in soil and their infection of herbivore hosts. Carcass deposition facilitates green-ups of vegetation to attract herbivores, potentially facilitated by the role of anthrax spores in the rhizosphere. The underlying seasonal pattern of vegetation, and herbivores' immune and behavioural responses to anthrax risk, interact to produce regular 'anthrax seasons' that appear to be a stable feature of the Etosha ecosystem. Through the lens of microbiologists, geneticists, immunologists, ecologists, epidemiologists, and clinicians, we discuss how anthrax dynamics are shaped at the smallest scale by population genetics and interactions within the bacterial communities up to the broadest scales of ecosystem structure. We illustrate the benefits and challenges of this interdisciplinary approach to disease ecology, and suggest ways anthrax might offer insights into the biology of other important pathogens. Bacillus anthracis, and the more recently emerged Bacillus cereus biovar anthracis, share key features with other environmentally transmitted pathogens, including several zoonoses and panzootics of special interest for global health and conservation efforts. Understanding the dynamics of anthrax, and developing interdisciplinary research programs that explore environmental persistence, is a critical step forward for understanding these emerging threats.
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Affiliation(s)
- Colin J Carlson
- National Socio-Environmental Synthesis Center (SESYNC), University of Maryland, Annapolis, MD 21401, U.S.A.,Department of Biology, Georgetown University, Washington, DC 20057, U.S.A
| | - Wayne M Getz
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, U.S.A.,School of Mathematical Sciences, University of KwaZulu-Natal, PB X 54001, Durban 4000, South Africa
| | - Kyrre L Kausrud
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, N-0316, Oslo, Norway
| | - Carrie A Cizauskas
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720, U.S.A
| | - Jason K Blackburn
- Spatial Epidemiology & Ecology Research Lab, Department of Geography, University of Florida, Gainesville, FL 32611, U.S.A.,Emerging Pathogens Institute, University of Florida, Gainesville, FL, U.S.A
| | - Fausto A Bustos Carrillo
- Department of Epidemiology & Department of Biostatistics, School of Public Health, University of California, Berkeley, CA 94720-7360, U.S.A
| | - Rita Colwell
- CosmosID Inc., Rockville, MD 20850, U.S.A.,Center for Bioinformatics and Computational Biology, University of Maryland Institute for Advanced Computer Studies, University of Maryland, College Park, MD 20742, U.S.A.,Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, U.S.A
| | - W Ryan Easterday
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, N-0316, Oslo, Norway
| | - Holly H Ganz
- UC Davis Genome Center, University of California, Davis, CA 95616, U.S.A
| | - Pauline L Kamath
- School of Food and Agriculture, University of Maine, Orono, ME 04469, U.S.A
| | - Ole A Økstad
- Centre for Integrative Microbial Evolution and Section for Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, N-0316, Oslo, Norway
| | - Wendy C Turner
- Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, U.S.A
| | - Anne-Brit Kolstø
- Centre for Integrative Microbial Evolution and Section for Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, PO Box 1068 Blindern, N-0316, Oslo, Norway
| | - Nils C Stenseth
- Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, N-0316, Oslo, Norway
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33
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Ramachandran RA, Lupfer C, Zaki H. The Inflammasome: Regulation of Nitric Oxide and Antimicrobial Host Defence. Adv Microb Physiol 2018; 72:65-115. [PMID: 29778217 DOI: 10.1016/bs.ampbs.2018.01.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nitric oxide (NO) is a gaseous signalling molecule that plays diverse physiological functions including antimicrobial host defence. During microbial infection, NO is synthesized by inducible NO synthase (iNOS), which is expressed by host immune cells through the recognition of microbial pattern molecules. Therefore, sensing pathogens or their pattern molecules by pattern recognition receptors (PRRs), which are located at the cell surface, endosomal and phagosomal compartment, or in the cytosol, is key in inducing iNOS and eliciting antimicrobial host defence. A group of cytosolic PRRs is involved in inducing NO and other antimicrobial molecules by forming a molecular complex called the inflammasome. Assembled inflammasomes activate inflammatory caspases, such as caspase-1 and caspase-11, which in turn process proinflammatory cytokines IL-1β and IL-18 into their mature forms and induce pyroptotic cell death. IL-1β and IL-18 play a central role in immunity against microbial infection through activation and recruitment of immune cells, induction of inflammatory molecules, and regulation of antimicrobial mediators including NO. Interestingly, NO can also regulate inflammasome activity in an autocrine and paracrine manner. Here, we discuss molecular mechanisms of inflammasome formation and the inflammasome-mediated regulation of host defence responses during microbial infections.
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Affiliation(s)
| | | | - Hasan Zaki
- UT Southwestern Medical Center, Dallas, TX, United States.
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34
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Abstract
Inflammasomes are multimeric protein complexes that typically comprise a sensor, an adaptor and the zymogen procaspase-1. An inflammasome assembles in response to a diverse range of pathogen-associated or danger-associated molecular patterns (PAMPs or DAMPs). The inflammasome platform leads to activation of caspase-1 through proximity-induced self-cleavage, which further induces maturation of interleukins 1β and 18 (IL-1β and IL-18) through proteolytic cleavage of pro-IL-1β and pro-IL-18. Activated caspase-1 also cleaves gasdermin D, which leads to a particular form of cell death called pyroptosis. Mutations in genes that encode inflammasome components are associated with many inflammatory disorders, and studies in the past decade have highlighted the importance of appropriate activation of the inflammasome in homeostasis and disease pathogenesis. Therefore, much attention is being paid to uncover the modulators and regulators of inflammasome assembly and pyroptosis. This Cell Science at a Glance article and accompanying poster outlines the concepts in the activation of inflammasome sensors and assembly of the inflammasome platform. We also discuss recent insights into the mechanisms of regulation of inflammasome activity and the induction of cell death by pyroptosis.
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Affiliation(s)
- Ankit Malik
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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35
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Hu Z, Chai J. Structural Mechanisms in NLR Inflammasome Assembly and Signaling. Curr Top Microbiol Immunol 2017; 397:23-42. [PMID: 27460803 DOI: 10.1007/978-3-319-41171-2_2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Inflammasomes are multimeric protein complexes that mediate the activation of inflammatory caspases. One central component of inflammasomes is nucleotide-binding domain (NBD)- and leucine-rich repeat (LRR)-containing proteins (NLRs) that can function as pattern recognition receptors (PRRs). In resting cells, NLR proteins exist in an auto-inhibited, monomeric, and ADP-bound state. Perception of microbial or damage-associated signals results in NLR oligomerization, thus recruiting inflammatory caspases directly or through the adaptor molecule apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC). The assembled NLR inflammasomes serve as dedicated machinery to facilitate the activation of the inflammatory caspases. Here, we review current understanding of the structures of NLR inflammasomes with an emphasis on the molecular mechanisms of their assembly and activation. We also discuss implications of the self-propagation model derived from the NAIP-NLRC4 inflammasomes for the activation of other NLR inflammasomes and a potential role of the C-terminal LRR domain in the activation of an NLR protein.
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Affiliation(s)
- Zehan Hu
- Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
| | - Jijie Chai
- Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
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36
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Man SM, Karki R, Kanneganti TD. Molecular mechanisms and functions of pyroptosis, inflammatory caspases and inflammasomes in infectious diseases. Immunol Rev 2017; 277:61-75. [PMID: 28462526 PMCID: PMC5416822 DOI: 10.1111/imr.12534] [Citation(s) in RCA: 1089] [Impact Index Per Article: 155.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell death is a fundamental biological phenomenon that is essential for the survival and development of an organism. Emerging evidence also indicates that cell death contributes to immune defense against infectious diseases. Pyroptosis is a form of inflammatory programmed cell death pathway activated by human and mouse caspase-1, human caspase-4 and caspase-5, or mouse caspase-11. These inflammatory caspases are used by the host to control bacterial, viral, fungal, or protozoan pathogens. Pyroptosis requires cleavage and activation of the pore-forming effector protein gasdermin D by inflammatory caspases. Physical rupture of the cell causes release of the pro-inflammatory cytokines IL-1β and IL-18, alarmins and endogenous danger-associated molecular patterns, signifying the inflammatory potential of pyroptosis. Here, we describe the central role of inflammatory caspases and pyroptosis in mediating immunity to infection and clearance of pathogens.
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Affiliation(s)
- Si Ming Man
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Rajendra Karki
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
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37
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Choo MK, Sano Y, Kim C, Yasuda K, Li XD, Lin X, Stenzel-Poore M, Alexopoulou L, Ghosh S, Latz E, Rifkin IR, Chen ZJ, Stewart GC, Chong H, Park JM. TLR sensing of bacterial spore-associated RNA triggers host immune responses with detrimental effects. J Exp Med 2017; 214:1297-1311. [PMID: 28400473 PMCID: PMC5413331 DOI: 10.1084/jem.20161141] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 12/05/2016] [Accepted: 02/14/2017] [Indexed: 12/18/2022] Open
Abstract
The spores of pathogenic bacteria are involved in host entry and the initial encounter with the host immune system. How bacterial spores interact with host immunity, however, remains poorly understood. Here, we show that the spores of Bacillus anthracis (BA), the etiologic agent of anthrax, possess an intrinsic ability to induce host immune responses. This immunostimulatory activity is attributable to high amounts of RNA present in the spore surface layer. RNA-sensing TLRs, TLR7, and TLR13 in mice and their human counterparts, are responsible for detecting and triggering the host cell response to BA spores, whereas TLR2 mediates the sensing of vegetative BA. BA spores, but not vegetative BA, induce type I IFN (IFN-I) production. Although TLR signaling in itself affords protection against BA, spore RNA-induced IFN-I signaling is disruptive to BA clearance. Our study suggests a role for bacterial spore-associated RNA in microbial pathogenesis and illustrates a little known aspect of interactions between the host and spore-forming bacteria.
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Affiliation(s)
- Min-Kyung Choo
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
| | - Yasuyo Sano
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
| | | | - Kei Yasuda
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Xiao-Dong Li
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Xin Lin
- Department of Molecular and Cellular Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030
| | - Mary Stenzel-Poore
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239
| | - Lena Alexopoulou
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille Université, UM2, 13288 Marseille, France
| | - Sankar Ghosh
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Eicke Latz
- Institute of Innate Immunity, University Hospital, University of Bonn, 53127 Bonn, Germany
| | - Ian R Rifkin
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Zhijian J Chen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - George C Stewart
- Department of Veterinary Pathobiology and Bond Life Science Center, University of Missouri, Columbia, MO 65211
| | | | - Jin Mo Park
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129
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38
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Affiliation(s)
- Judie A. Howrylak
- Division of Pulmonary, Allergy, and Critical Care Medicine, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania 17003
| | - Kiichi Nakahira
- Division of Pulmonary and Critical Care Medicine, Joan and Sanford I. Weill Department of Medicine, Weill Cornell Medicine, Cornell University, New York, NY 10065;
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39
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Mayer-Barber KD, Yan B. Clash of the Cytokine Titans: counter-regulation of interleukin-1 and type I interferon-mediated inflammatory responses. Cell Mol Immunol 2017; 14:22-35. [PMID: 27264686 PMCID: PMC5214938 DOI: 10.1038/cmi.2016.25] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 04/25/2016] [Accepted: 04/26/2016] [Indexed: 02/07/2023] Open
Abstract
Over the past decades the notion of 'inflammation' has been extended beyond the original hallmarks of rubor (redness), calor (heat), tumor (swelling) and dolor (pain) described by Celsus. We have gained a more detailed understanding of the cellular players and molecular mediators of inflammation which is now being applied and extended to areas of biomedical research such as cancer, obesity, heart disease, metabolism, auto-inflammatory disorders, autoimmunity and infectious diseases. Innate cytokines are often central components of inflammatory responses. Here, we discuss how the type I interferon and interleukin-1 cytokine pathways represent distinct and specialized categories of inflammatory responses and how these key mediators of inflammation counter-regulate each other.
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Affiliation(s)
- Katrin D Mayer-Barber
- Inflammation and Innate Immunity Unit, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Bo Yan
- Inflammation and Innate Immunity Unit, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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40
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Functional and Evolutionary Analyses Identify Proteolysis as a General Mechanism for NLRP1 Inflammasome Activation. PLoS Pathog 2016; 12:e1006052. [PMID: 27926929 PMCID: PMC5142783 DOI: 10.1371/journal.ppat.1006052] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/09/2016] [Indexed: 12/19/2022] Open
Abstract
Inflammasomes are cytosolic multi-protein complexes that initiate immune responses to infection by recruiting and activating the Caspase-1 protease. Human NLRP1 was the first protein shown to form an inflammasome, but its physiological mechanism of activation remains unknown. Recently, specific variants of mouse and rat NLRP1 were found to be activated upon N-terminal cleavage by the anthrax lethal factor protease. However, agonists for other NLRP1 variants, including human NLRP1, are not known, and it remains unclear if they are also activated by proteolysis. Here we demonstrate that two mouse NLRP1 paralogs (NLRP1AB6 and NLRP1BB6) are also activated by N-terminal proteolytic cleavage. We also demonstrate that proteolysis within a specific N-terminal linker region is sufficient to activate human NLRP1. Evolutionary analysis of primate NLRP1 shows the linker/cleavage region has evolved under positive selection, indicative of pathogen-induced selective pressure. Collectively, these results identify proteolysis as a general mechanism of NLRP1 inflammasome activation that appears to be contributing to the rapid evolution of NLRP1 in rodents and primates.
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41
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Abstract
Mice and humans branched from a common ancestor approximately 80 million years ago. Despite this, mice are routinely utilized as animal models of human disease and in drug development because they are inexpensive, easy to handle, and relatively straightforward to genetically manipulate. While this has led to breakthroughs in the understanding of genotype-phenotype relationships and in the identification of therapeutic targets, translation of beneficial responses to therapeutics from mice to humans has not always been successful. In a large part, these differences may be attributed to variations in the alignment of protein expression and signaling in the immune systems between mice and humans. Well-established inbred strains of "The Laboratory Mouse" vary in their immune response patterns as a result of genetic mutations and polymorphisms arising from intentional selection for research relevant traits, and even closely related substrains vary in their immune response patterns as a result of genetic mutations and polymorphisms arising from genetic drift. This article reviews some of the differences between the mouse and human immune system and between inbred mouse strains and shares examples of how these differences can impact the usefulness of mouse models of disease.
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Affiliation(s)
- Rani S Sellers
- 1 Drug Safety Research and Development, Pfizer Inc., Pearl River, NY, USA
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42
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Maltez VI, Miao EA. Reassessing the Evolutionary Importance of Inflammasomes. THE JOURNAL OF IMMUNOLOGY 2016; 196:956-62. [PMID: 26802061 DOI: 10.4049/jimmunol.1502060] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Inflammasomes monitor the cytosol for microbial contamination or perturbation and, thus, are predicted to provide potent defense against infection. However, the compendium of data from murine infection models suggests that inflammasomes merely delay the course of disease, allowing the host time to mount an adaptive response. Interpretations of such results are confounded by inflammasome-evasion strategies of vertebrate-adapted pathogens. Conversely, environmental opportunistic pathogens have not evolved in the context of inflammasomes and, therefore, are less likely to evade them. Indeed, opportunistic pathogens do not normally cause disease in wild-type animals. Accordantly, the extreme virulence of two opportunistic bacterial pathogens, Burkholderia thailandensis and Chromobacterium violaceum, is fully counteracted by inflammasomes in murine models. This leads us to propose a new hypothesis: perhaps animals maintain inflammasomes over evolutionary time not to defend against vertebrate-adapted pathogens but instead to counteract infection by a plethora of undiscovered opportunistic pathogens residing in the environment.
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Affiliation(s)
- Vivien I Maltez
- Department of Microbiology and Immunology, Center for Gastrointestinal Biology and Disease, and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Edward A Miao
- Department of Microbiology and Immunology, Center for Gastrointestinal Biology and Disease, and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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43
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Animal Models for the Pathogenesis, Treatment, and Prevention of Infection by Bacillus anthracis. Microbiol Spectr 2016; 3:TBS-0001-2012. [PMID: 26104551 DOI: 10.1128/microbiolspec.tbs-0001-2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
This article reviews the characteristics of the major animal models utilized for studies on Bacillus anthracis and highlights their contributions to understanding the pathogenesis and host responses to anthrax and its treatment and prevention. Advantages and drawbacks associated with each model, to include the major models (murine, guinea pig, rabbit, nonhuman primate, and rat), and other less frequently utilized models, are discussed. Although the three principal forms of anthrax are addressed, the main focus of this review is on models for inhalational anthrax. The selection of an animal model for study is often not straightforward and is dependent on the specific aims of the research or test. No single animal species provides complete equivalence to humans; however, each species, when used appropriately, can contribute to a more complete understanding of anthrax and its etiologic agent.
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44
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Friebe S, van der Goot FG, Bürgi J. The Ins and Outs of Anthrax Toxin. Toxins (Basel) 2016; 8:toxins8030069. [PMID: 26978402 PMCID: PMC4810214 DOI: 10.3390/toxins8030069] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 02/28/2016] [Accepted: 03/01/2016] [Indexed: 12/21/2022] Open
Abstract
Anthrax is a severe, although rather rare, infectious disease that is caused by the Gram-positive, spore-forming bacterium Bacillus anthracis. The infectious form is the spore and the major virulence factors of the bacterium are its poly-γ-D-glutamic acid capsule and the tripartite anthrax toxin. The discovery of the anthrax toxin receptors in the early 2000s has allowed in-depth studies on the mechanisms of anthrax toxin cellular entry and translocation from the endocytic compartment to the cytoplasm. The toxin generally hijacks the endocytic pathway of CMG2 and TEM8, the two anthrax toxin receptors, in order to reach the endosomes. From there, the pore-forming subunit of the toxin inserts into endosomal membranes and enables translocation of the two catalytic subunits. Insertion of the pore-forming unit preferentially occurs in intraluminal vesicles rather than the limiting membrane of the endosome, leading to the translocation of the enzymatic subunits in the lumen of these vesicles. This has important consequences that will be discussed. Ultimately, the toxins reach the cytosol where they act on their respective targets. Target modification has severe consequences on cell behavior, in particular on cells of the immune system, allowing the spread of the bacterium, in severe cases leading to host death. Here we will review the literature on anthrax disease with a focus on the structure of the toxin, how it enters cells and its immunological effects.
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Affiliation(s)
- Sarah Friebe
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
| | - F Gisou van der Goot
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
| | - Jérôme Bürgi
- Faculty of Life Sciences, Global Health Institute, Ecole Polytechnique Fédérale de Lausanne, Lausanne 1015, Switzerland.
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45
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do Vale A, Cabanes D, Sousa S. Bacterial Toxins as Pathogen Weapons Against Phagocytes. Front Microbiol 2016; 7:42. [PMID: 26870008 PMCID: PMC4734073 DOI: 10.3389/fmicb.2016.00042] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 01/11/2016] [Indexed: 12/31/2022] Open
Abstract
Bacterial toxins are virulence factors that manipulate host cell functions and take over the control of vital processes of living organisms to favor microbial infection. Some toxins directly target innate immune cells, thereby annihilating a major branch of the host immune response. In this review we will focus on bacterial toxins that act from the extracellular milieu and hinder the function of macrophages and neutrophils. In particular, we will concentrate on toxins from Gram-positive and Gram-negative bacteria that manipulate cell signaling or induce cell death by either imposing direct damage to the host cells cytoplasmic membrane or enzymatically modifying key eukaryotic targets. Outcomes regarding pathogen dissemination, host damage and disease progression will be discussed.
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Affiliation(s)
- Ana do Vale
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Fish Immunology and Vaccinology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
| | - Didier Cabanes
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
| | - Sandra Sousa
- Host Interaction and Response, Instituto de Investigação e Inovação em Saúde, Universidade do PortoPorto, Portugal; Group of Molecular Microbiology, Instituto de Biologia Molecular e Celular, Universidade do PortoPorto, Portugal
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46
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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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47
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Abstract
Inflammasome biology is one of the most exciting and rapidly growing areas in immunology. Over the past 10 years, inflammasomes have been recognized for their roles in the host defense against invading pathogens and in the development of cancer, auto-inflammatory, metabolic, and neurodegenerative diseases. Assembly of an inflammasome complex requires cytosolic sensing of pathogen-associated molecular patterns or danger-associated molecular patterns by a nucleotide-binding domain and leucine-rich repeat receptor (NLR) or absent in melanoma 2 (AIM2)-like receptors (ALR). NLRs and ALRs engage caspase-1, in most cases requiring the adapter protein apoptosis-associated speck-like protein containing a CARD (ASC), to catalyze proteolytic cleavage of pro-interleukin-1β (pro-IL-1β) and pro-IL-18 and drive pyroptosis. Recent studies indicate that caspase-8, caspase-11, IL-1R-associated kinases (IRAK), and receptor-interacting protein (RIP) kinases contribute to inflammasome functions. In addition, post-translational modifications, including ubiquitination, deubiquitination, phosphorylation, and degradation control almost every aspect of inflammasome activities. Genetic studies indicate that mutations in NLRP1, NLRP3, NLRC4, and AIM2 are linked with the development of auto-inflammatory diseases, enterocolitis, and cancer. Overall, these findings transform our understanding of the basic biology and clinical relevance of inflammasomes. In this review, we provide an overview of the latest development of inflammasome research and discuss how inflammasome activities govern health and disease.
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Affiliation(s)
- Si Ming Man
- Department of Immunology, St. Jude Children's Research Hospital, Memphis, TN, USA
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48
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Kariminik A, Yaghobi R, Dabiri S. Innate Immunity and BK Virus: Prospective Strategies. Viral Immunol 2016; 29:74-82. [PMID: 26752693 DOI: 10.1089/vim.2015.0099] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Recent information demonstrated that BK virus reactivation is a dominant complication after kidney transplantation, which occurs because of immunosuppression. BK virus reactivation is the main reason of transplanted kidney losing. Immune response against BK virus is the major inhibitor of the virus reactivation. Therefore, improving our knowledge regarding the main parameters that fight against BK viruses can shed light on to direct new treatment strategies to suppress BK infection. Innate immunity consists of numerous cell systems and also soluble molecules, which not only suppress virus replication, but also activate adaptive immunity to eradicate the infection. Additionally, it appears that immune responses against reactivated BK virus are the main reasons for induction of BK virus-associated nephropathy (BKAN). Thus, improving our knowledge regarding the parameters and detailed mechanisms of innate immunity and also the status of innate immunity of the patients with BK virus reactivation and its complications can introduce new prospective strategies to either prevent or as therapy of the complication. Therefore, this review was aimed to collate the most recent data regarding the roles played by innate immunity against BK virus and also the status of innate immunity in the patients with reactivation BK virus and BKAN.
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Affiliation(s)
- Ashraf Kariminik
- 1 Shiraz Branch, Department of Microbiology, Islamic Azad University , Shiraz, Iran .,2 Fars Research and Science Branch, Department of Microbiology, Islamic Azad University , Fars, Iran
| | - Ramin Yaghobi
- 3 Shiraz Transplant Research Center, Shiraz University of Medical Sciences , Shiraz, Iran
| | - Shahriar Dabiri
- 4 Pathology and Stem Cell Research Center, Department of Pathology, Afzalipour School of Medicine, Kerman University of Medical Sciences , Kerman, Iran
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49
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Adenoviral Expression of a Bispecific VHH-Based Neutralizing Agent That Targets Protective Antigen Provides Prophylactic Protection from Anthrax in Mice. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:213-8. [PMID: 26740390 DOI: 10.1128/cvi.00611-15] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/27/2015] [Indexed: 01/01/2023]
Abstract
Bacillus anthracis, the causative agent of anthrax, secretes three polypeptides, which form the bipartite lethal and edema toxins (LT and ET, respectively). The common component in these toxins, protective antigen (PA), is responsible for binding to cellular receptors and translocating the lethal factor (LF) and edema factor (EF) enzymatic moieties to the cytosol. Antibodies against PA protect against anthrax. We previously isolated toxin-neutralizing variable domains of camelid heavy-chain-only antibodies (VHHs) and demonstrated their in vivo efficacy. In this work, gene therapy with an adenoviral (Ad) vector (Ad/VNA2-PA) (VNA, VHH-based neutralizing agents) promoting the expression of a bispecific VHH-based neutralizing agent (VNA2-PA), consisting of two linked VHHs targeting different PA-neutralizing epitopes, was tested in two inbred mouse strains, BALB/cJ and C57BL/6J, and found to protect mice against anthrax toxin challenge and anthrax spore infection. Two weeks after a single treatment with Ad/VNA2-PA, serum VNA2-PA levels remained above 1 μg/ml, with some as high as 10 mg/ml. The levels were 10- to 100-fold higher and persisted longer in C57BL/6J than in BALB/cJ mice. Mice were challenged with a lethal dose of LT or spores at various times after Ad/VNA2-PA administration. The majority of BALB/cJ mice having serum VNA2-PA levels of >0.1 μg/ml survived LT challenge, and 9 of 10 C57BL/6J mice with serum levels of >1 μg/ml survived spore challenge. Our findings demonstrate the potential for genetic delivery of VNAs as an effective method for providing prophylactic protection from anthrax. We also extend prior findings of mouse strain-based differences in transgene expression and persistence by adenoviral vectors.
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50
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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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