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Liu G, Lu Y, Shi L, Kong J, Hu H, Liu W. Trace endotoxin in reclaimed water is only one of the risk sources in subchronic inhalation exposure. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 285:117479. [PMID: 34090073 DOI: 10.1016/j.envpol.2021.117479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 05/12/2021] [Accepted: 05/25/2021] [Indexed: 06/12/2023]
Abstract
Pulmonary injury and inflammation have been detected in cases of subchronic inhalation exposure to reclaimed water, but the mechanism remains unclear. Endotoxin has been verified as the key risk factor in acute inhalation exposure through the TLR4 (Toll-like receptor 4) signalling pathway. In long-term exposure, endotoxin may also be a risk factor in reclaimed water, but the contribution of other health risk factors should not be underestimated. Wild-type C57BL/6J and TLR4-signalling-pathway-defective mice were used in this study to assess the risk of subchronic inhalation exposure to reclaimed water. Two types of reclaimed water, i.e., secondary effluent and MBR (membrane bioreactor) effluent, were found to induce pulmonary injury and inflammation in the wild-type mice and Tlr4-/- mutants. However, when both mice were exposed to the same concentrations of pure endotoxin in reclaimed water, only the wild-type mice that were treated with high-dose endotoxin showed pulmonary injury. In summary, non-TLR4 signalling pathways are related to lung inflammation caused by long-term exposure to reclaimed water. It is highly possible that pollutants in addition to endotoxin in the reclaimed water can induce chronic inflammation in the lung.
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Affiliation(s)
- Gang Liu
- State Environment Protection Key Laboratory of Microorganism Application and Rish Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Yun Lu
- State Environment Protection Key Laboratory of Microorganism Application and Rish Control, School of Environment, Tsinghua University, Beijing, 100084, China.
| | - Liangliang Shi
- State Environment Protection Key Laboratory of Microorganism Application and Rish Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Jiayang Kong
- State Environment Protection Key Laboratory of Microorganism Application and Rish Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Hongying Hu
- State Environment Protection Key Laboratory of Microorganism Application and Rish Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Wanli Liu
- School of Life Science, Tsinghua University, Beijing, 100084, China
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2
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Cytosolic Gram-negative bacteria prevent apoptosis by inhibition of effector caspases through lipopolysaccharide. Nat Microbiol 2019; 5:354-367. [PMID: 31873204 DOI: 10.1038/s41564-019-0620-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 10/24/2019] [Indexed: 02/08/2023]
Abstract
The cytosolic appearance and propagation of bacteria cause overwhelming cellular stress responses that induce apoptosis under normal conditions. Therefore, successful bacterial colonization depends on the ability of intracellular pathogens to block apoptosis and to safeguard bacterial replicative niches. Here, we show that the cytosolic Gram-negative bacterium Shigella flexneri stalls apoptosis by inhibiting effector caspase activity. Our data identified lipopolysaccharide (LPS) as a bona fide effector caspase inhibitor that directly binds caspases by involving its O-antigen (O Ag) moiety. Bacterial strains that lacked the O Ag or failed to replicate within the cytosol were incapable of blocking apoptosis and exhibited reduced virulence in a murine model of bacterial infection. Our findings demonstrate how Shigella inhibits pro-apoptotic caspase activity, effectively delays coordinated host-cell demise and supports its intracellular propagation. Next to the recently discovered pro-inflammatory role of cytosolic LPS, our data reveal a distinct mode of LPS action that, through the disruption of the early coordinated non-lytic cell death response, ultimately supports the inflammatory breakdown of infected cells at later time points.
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3
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Clark SE, Schmidt RL, McDermott DS, Lenz LL. A Batf3/Nlrp3/IL-18 Axis Promotes Natural Killer Cell IL-10 Production during Listeria monocytogenes Infection. Cell Rep 2019; 23:2582-2594. [PMID: 29847790 PMCID: PMC6170157 DOI: 10.1016/j.celrep.2018.04.106] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/06/2018] [Accepted: 04/25/2018] [Indexed: 11/27/2022] Open
Abstract
The bacterial pathogen Listeria monocytogenes (Lm) capitalizes on natural killer (NK) cell production of regulatory interleukin (IL)-10 to establish severe systemic infections. Here, we identify regulators of this IL-10 secretion. We show that IL-18 signals to NK cells license their ability to produce IL-10. IL-18 acts independent of IL-12 and STAT4, which co-stimulate IFNγ secretion. Dendritic cell (DC) expression of Nlrp3 is required for IL-18 release in response to the Lm p60 virulence protein. Therefore, mice lacking Nlrp3, Il18, or Il18R fail to accumulate serum IL-10 and are highly resistant to systemic Lm infection. We further show that cells expressing or dependent on Batf3 are required for IL-18-inducing IL-10 production observed in infected mice. These findings explain how Il18 and Batf3 promote susceptibility to bacterial infection and demonstrate the ability of Lm to exploit NLRP3 for the promotion of regulatory NK cell activity.
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Affiliation(s)
- Sarah E Clark
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Rebecca L Schmidt
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Daniel S McDermott
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Laurel L Lenz
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA.
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4
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Cowman SA, Jacob J, Hansell DM, Kelleher P, Wilson R, Cookson WOC, Moffatt MF, Loebinger MR. Whole-Blood Gene Expression in Pulmonary Nontuberculous Mycobacterial Infection. Am J Respir Cell Mol Biol 2019; 58:510-518. [PMID: 29206475 DOI: 10.1165/rcmb.2017-0230oc] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The factors predisposing toward the development of pulmonary nontuberculous mycobacterial (pNTM) disease and influencing disease progression remain unclear. Impaired immune responses have been reported in individuals with pNTM disease, but data are limited and inconsistent. In this study, we sought to use gene expression profiling to examine the host response to pNTM disease. Microarray analysis of whole-blood gene expression was performed on 25 subjects with pNTM disease and 27 uninfected control subjects with respiratory disease. Gene expression results were compared with phenotypic variables and survival data. Compared with uninfected control subjects, pNTM disease was associated with downregulation of 213 transcripts enriched for terms related to T cell signaling, including IFNG. Reduced IFNG expression was associated with more severe computed tomography changes and impaired lung function. Mortality was associated with the expression of transcripts related to the innate immune response and inflammation, whereas transcripts related to T and B cell function were associated with improved survival. These findings suggest that pNTM disease is associated with an aberrant immune response, which may reflect an underlying propensity to infection or result from NTM infection itself. There were important differences in the immune response associated with survival and mortality in pNTM disease.
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Affiliation(s)
- Steven A Cowman
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom.,2 Host Defence Unit and
| | - Joseph Jacob
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom.,3 Department of Radiology, Royal Brompton Hospital, London, United Kingdom
| | - David M Hansell
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom.,3 Department of Radiology, Royal Brompton Hospital, London, United Kingdom
| | - Peter Kelleher
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom.,2 Host Defence Unit and
| | - Robert Wilson
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom.,2 Host Defence Unit and
| | - William O C Cookson
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Miriam F Moffatt
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Michael R Loebinger
- 1 National Heart and Lung Institute, Imperial College London, London, United Kingdom.,2 Host Defence Unit and
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5
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Krause K, Caution K, Badr A, Hamilton K, Saleh A, Patel K, Seveau S, Hall-Stoodley L, Hegazi R, Zhang X, Gavrilin MA, Amer AO. CASP4/caspase-11 promotes autophagosome formation in response to bacterial infection. Autophagy 2018; 14:1928-1942. [PMID: 30165781 PMCID: PMC6152495 DOI: 10.1080/15548627.2018.1491494] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
CASP4/caspase-11-dependent inflammasome activation is important for the clearance of various Gram-negative bacteria entering the host cytosol. Additionally, CASP4 modulates the actin cytoskeleton to promote the maturation of phagosomes harboring intracellular pathogens such as Legionella pneumophila but not those enclosing nonpathogenic bacteria. Nevertheless, this non-inflammatory role of CASP4 regarding the trafficking of vacuolar bacteria remains poorly understood. Macroautophagy/autophagy, a catabolic process within eukaryotic cells, is also implicated in the elimination of intracellular pathogens such as Burkholderia cenocepacia. Here we show that CASP4-deficient macrophages exhibit a defect in autophagosome formation in response to B. cenocepacia infection. The absence of CASP4 causes an accumulation of the small GTPase RAB7, reduced colocalization of B. cenocepacia with LC3 and acidic compartments accompanied by increased bacterial replication in vitro and in vivo. Together, our data reveal a novel role of CASP4 in regulating autophagy in response to B. cenocepacia infection.
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Affiliation(s)
- Kathrin Krause
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Kyle Caution
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Asmaa Badr
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Kaitlin Hamilton
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Abdulmuti Saleh
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Khushbu Patel
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Stephanie Seveau
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Luanne Hall-Stoodley
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Rana Hegazi
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
| | - Xiaoli Zhang
- b Center for Biostatistics, The Ohio State University , Columbus , OH , USA
| | - Mikhail A Gavrilin
- c Department of Internal Medicine , The Ohio State University , Columbus , OH , USA
| | - Amal O Amer
- a Department of Microbial Infection and Immunity , Infectious Diseases Institute , Columbus , OH , USA
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6
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Adanitsch F, Shi J, Shao F, Beyaert R, Heine H, Zamyatina A. Synthetic glycan-based TLR4 agonists targeting caspase-4/11 for the development of adjuvants and immunotherapeutics. Chem Sci 2018; 9:3957-3963. [PMID: 29780528 PMCID: PMC5941199 DOI: 10.1039/c7sc05323a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/15/2018] [Indexed: 12/16/2022] Open
Abstract
The skewed molecular shape of the rigid α,α-(1↔1′)-linked disaccharide core of novel synthetic anionic glycan-based immunostimulants is accountable for potent and adjustable TLR4-mediated signaling which is dissociable from the induction of caspase-11 protease activity.
Gram-negative bacterial lipopolysaccharide (LPS)-induced Toll-like receptor 4 (TLR4) mediated pro-inflammatory signaling plays a key role in immunoprotection against infectious challenges and boosts adaptive immunity, whereas the activation of the cytosolic LPS receptor caspase-4/11 leads to cell death by pyroptosis and is deeply implicated in the development of sepsis. Despite tremendous advances in the understanding of the LPS–TLR4 interaction, predictably regulated TLR4 activation has not yet been achieved. The structural basis for the induction of caspase-4/11 protease activity by LPS is currently unknown. The modulation of innate and adaptive immune responses through the controlled induction of TLR4 signaling without triggering caspase-4/11 activity would open novel perspectives in the development of safe vaccine adjuvants and immunotherapeutics. We report the discovery of highly potent glycan-based immunostimulants with picomolar affinity for TLR4 which interact with caspase-4/11 and promote caspase-4/11 oligomerization while abolishing caspase-11 protease activity. The rigidity and twisted molecular shape of the α,α-(1↔1′)-linked disaccharide core of synthetic LPS mimicking anionic glycolipids accounted for both species-independent and adjustable TLR4-mediated NF-κB signaling and the modulation of caspase-4/11 activation. By the use of crystal structure based design and advanced synthetic chemistry we created a set of versatile probes for studying the structural basis of caspase-4/11 activation and established a chemical strategy for controllable TLR4 mediated cytokine release which is dissociable from the induction of caspase-11 protease activity.
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Affiliation(s)
- Florian Adanitsch
- Department of Chemistry , University of Natural Resources and Life Sciences , Muthgasse 18 , A-1190 Vienna , Austria .
| | - Jianjin Shi
- National Institute of Biological Sciences , Beijing 102206 , China
| | - Feng Shao
- National Institute of Biological Sciences , Beijing 102206 , China
| | - Rudi Beyaert
- Department for Biomedical Molecular Biology , Ghent University , Center for Inflammation Research , VIB , Ghent , Belgium
| | - Holger Heine
- Research Group Innate Immunity , Research Center Borstel , Leibniz Lung Center , Airway Research Center North (ARCN) , German Center for Lung research (DZL) , Borstel , Germany
| | - Alla Zamyatina
- Department of Chemistry , University of Natural Resources and Life Sciences , Muthgasse 18 , A-1190 Vienna , Austria .
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7
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Abstract
The coevolution of intracellular bacteria with their eukaryotic hosts has presented these pathogens with numerous challenges for their evolutionary progress and survival. Chief among these is the ability to exit from host cells, an event that is fundamentally linked to pathogen dissemination and transmission. Recent years have witnessed a major expansion of research in this area, and this chapter summarizes our current understanding of the spectrum of exit strategies that are exploited by intracellular pathogens. Clear themes regarding the mechanisms of microbial exit have emerged and are most easily conceptualized as (i) lysis of the host cell, (ii) nonlytic exit of free bacteria, and (iii) release of microorganisms into membrane-encased compartments. The adaptation of particular exit strategies is closely linked with additional themes in microbial pathogenesis, including host cell death, manipulation of host signaling pathways, and coincident activation of proinflammatory responses. This chapter will explore the molecular determinants used by intracellular pathogens to promote host cell escape and the infectious advantages each exit pathway may confer, and it will provide an evolutionary framework for the adaptation of these mechanisms.
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8
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Eldridge MJG, Sanchez-Garrido J, Hoben GF, Goddard PJ, Shenoy AR. The Atypical Ubiquitin E2 Conjugase UBE2L3 Is an Indirect Caspase-1 Target and Controls IL-1β Secretion by Inflammasomes. Cell Rep 2017; 18:1285-1297. [PMID: 28147281 PMCID: PMC5300903 DOI: 10.1016/j.celrep.2017.01.015] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 12/12/2016] [Accepted: 01/09/2017] [Indexed: 11/06/2022] Open
Abstract
Caspase-1 activation by inflammasome signaling scaffolds initiates inflammation and antimicrobial responses. Caspase-1 proteolytically converts newly induced pro-interleukin 1 beta (IL-1β) into its mature form and directs its secretion, triggering pyroptosis and release of non-substrate alarmins such as interleukin 1 alpha (IL-1α) and HMGB1. While some caspase-1 substrates involved in these events are known, the identities and roles of non-proteolytic targets remain unknown. Here, we use unbiased proteomics to show that the UBE2L3 ubiquitin conjugase is an indirect target of caspase-1. Caspase-1, but not caspase-4, controls pyroptosis- and ubiquitin-independent proteasomal degradation of UBE2L3 upon canonical and non-canonical inflammasome activation by sterile danger signals and bacterial infection. Mechanistically, UBE2L3 acts post-translationally to promote K48-ubiquitylation and turnover of pro-IL-1β and dampen mature-IL-1β production. UBE2L3 depletion increases pro-IL-1β levels and mature-IL-1β secretion by inflammasomes. These findings regarding UBE2L3 as a molecular rheostat have implications for IL-1-driven pathology in hereditary fever syndromes and in autoinflammatory conditions associated with UBE2L3 polymorphisms. Caspase-1 inflammasomes induce loss of UBE2L3 in macrophages and dendritic cells UBE2L3 loss is proteasome-dependent, ubiquitin- and pyroptosis-independent UBE2L3 participates in K48 ubiquitylation and proteasomal turnover of pro-IL-1β UBE2L3 modulates levels of pro-IL-1β available for processing by caspase-1
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Affiliation(s)
- Matthew J G Eldridge
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Julia Sanchez-Garrido
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Gil Ferreira Hoben
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Philippa J Goddard
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Avinash R Shenoy
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK.
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9
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Kader M, Alaoui-EL-Azher M, Vorhauer J, Kode BB, Wells JZ, Stolz D, Michalopoulos G, Wells A, Scott M, Ismail N. MyD88-dependent inflammasome activation and autophagy inhibition contributes to Ehrlichia-induced liver injury and toxic shock. PLoS Pathog 2017; 13:e1006644. [PMID: 29049365 PMCID: PMC5663626 DOI: 10.1371/journal.ppat.1006644] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 10/31/2017] [Accepted: 09/11/2017] [Indexed: 01/19/2023] Open
Abstract
Severe hepatic inflammation is a common cause of acute liver injury following systemic infection with Ehrlichia, obligate Gram-negative intracellular bacteria that lack lipopolysaccharide (LPS). We have previously shown that type I IFN (IFN-I) and inflammasome activation are key host-pathogenic mediators that promote excessive inflammation and liver damage following fatal Ehrlichia infection. However, the underlying signals and mechanisms that regulate protective immunity and immunopathology during Ehrlichia infection are not well understood. To address this issue, we compared susceptibility to lethal Ixodes ovatus Ehrlichia (IOE) infection between wild type (WT) and MyD88-deficient (MyD88-/-) mice. We show here that MyD88-/- mice exhibited decreased inflammasome activation, attenuated liver injury, and were more resistant to lethal infection than WT mice, despite suppressed protective immunity and increased bacterial burden in the liver. MyD88-dependent inflammasome activation was also dependent on activation of the metabolic checkpoint kinase mammalian target of rapamycin complex 1 (mTORC1), inhibition of autophagic flux, and defective mitophagy in macrophages. Blocking mTORC1 signaling in infected WT mice and primary macrophages enhanced bacterial replication and attenuated inflammasome activation, suggesting autophagy promotes bacterial replication while inhibiting inflammasome activation. Finally, our data suggest TLR9 and IFN-I are upstream signaling mechanisms triggering MyD88-mediated mTORC1 and inflammasome activation in macrophages following Ehrlichia infection. This study reveals that Ehrlichia-induced liver injury and toxic shock are mediated by MyD88-dependent inflammasome activation and autophagy inhibition. Human monocytic ehrlichiosis (HME) is the most prevalent emerging infectious disease in the United States. Ehrlichia chaffeensis, etiologic agent of HME, is a Gram negative obligate intracellular bacterium transmitted by infected tick bites and can infect different cell type. Although Ehrlichia lack lipopolysaccharide (LPS), they induce potentially life threatening HME that mimic sepsis or toxic shock associated with multi-organ failure. The clinical diagnosis of HME is difficult, and definitive diagnosis is most often retrospective. Late antibiotic treatment is frequently ineffective in preventing disease progression to fatal multi-organ failure. Liver failure is one of the most serious complications and the most frequent cause of death in patients with HME, however we only have a limited understanding of how this liver failure is caused during fatal Ehrlichia infection. The objective of this study is to determine how LPS-negative Ehrlichia activates inflammatory responses in macrophages during Ehrlichia infection to promote liver damage. We show here that MyD88-signaling causes detrimental derangement of the immune system and subsequent liver damage by regulating two key innate immune events in macrophages: autophagy and inflammasome activation. Targeting host-pathogenic pathways in ehrlichiosis can be incorporated into future design of novel therapeutic approaches for HME.
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MESH Headings
- Animals
- Autophagy/immunology
- Blotting, Western
- Disease Models, Animal
- Ehrlichia/immunology
- Ehrlichiosis/immunology
- Ehrlichiosis/metabolism
- Enzyme-Linked Immunosorbent Assay
- Female
- Flow Cytometry
- Fluorescent Antibody Technique
- Image Processing, Computer-Assisted
- In Situ Nick-End Labeling
- Inflammasomes/immunology
- Inflammasomes/metabolism
- Liver Failure, Acute/immunology
- Liver Failure, Acute/metabolism
- Liver Failure, Acute/microbiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Microscopy, Confocal
- Microscopy, Electron, Transmission
- Myeloid Differentiation Factor 88/immunology
- Myeloid Differentiation Factor 88/metabolism
- Real-Time Polymerase Chain Reaction
- Shock, Septic/immunology
- Shock, Septic/metabolism
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Affiliation(s)
- Muhamuda Kader
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Mounia Alaoui-EL-Azher
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jennie Vorhauer
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Bhushan B Kode
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Jakob Z. Wells
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Donna Stolz
- Center for Biologic Imaging, University of Pittsburgh Medical School, Pittsburgh, Pennsylvania, United States of America
| | - George Michalopoulos
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Alan Wells
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Melanie Scott
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Nahed Ismail
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Pittsburgh Liver Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Immunology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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10
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TAK1 regulates resident macrophages by protecting lysosomal integrity. Cell Death Dis 2017; 8:e2598. [PMID: 28182011 PMCID: PMC5386472 DOI: 10.1038/cddis.2017.23] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 01/04/2017] [Indexed: 12/27/2022]
Abstract
Hematopoietic cell survival and death is critical for development of a functional immune system. Here, we report that a protein kinase, TAK1, is selectively required for resident macrophage integrity during embryogenesis. Hematopoietic lineage-specific deletion of Tak1 gene (Tak1HKO) caused accumulation of cellular debris in the thymus in perinatal mice. Although no overt alteration in thymocytes and blood myeloid populations was observed in Tak1HKO mice, we found that thymic and lung macrophages were diminished. In the in vitro setting, Tak1 deficiency caused profound disruption of lysosomes and killed bone marrow-derived macrophages (BMDMs) without any exogenous stressors. Inhibition of the lysosomal protease, cathepsin B, partially blocked Tak1-deficient BMDM death, suggesting that leakage of the lysosomal contents is in part the cause of cell death. To identify the trigger of this cell death, we examined involvement of TNF and Toll-like receptor pathways. Among them, we found that deletion of Tnfr1 partially rescued cell death. Finally, we show that Tnfr1 deletion partially restored thymic and lung macrophages in vivo. These results suggest that autocrine and potentially paracrine TNF kills Tak1-deficient macrophages during development. Our results reveal that TAK1 signaling maintains proper macrophage populations through protecting lysosomal integrity.
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11
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Zhao Y, Shi J, Shi X, Wang Y, Wang F, Shao F. Genetic functions of the NAIP family of inflammasome receptors for bacterial ligands in mice. J Exp Med 2016; 213:647-56. [PMID: 27114610 PMCID: PMC4854738 DOI: 10.1084/jem.20160006] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 04/04/2016] [Indexed: 12/03/2022] Open
Abstract
Naip knockout mice provide genetic evidence for the specificity of NAIP1, 2, and 5 in recognizing bacterial T3SS needle protein, rod protein, and flagellin, respectively. Naip1−/−, Naip2−/−, and Naip5−/− mice underscore the physiological contribution of the NAIP proteins in innate defense against cytosolic bacteria. Biochemical studies suggest that the NAIP family of NLR proteins are cytosolic innate receptors that directly recognize bacterial ligands and trigger NLRC4 inflammasome activation. In this study, we generated Naip5−/−, Naip1−/−, and Naip2−/− mice and showed that bone marrow macrophages derived from these knockout mice are specifically deficient in detecting bacterial flagellin, the type III secretion system needle, and the rod protein, respectively. Naip1−/−, Naip2−/−, and Naip5−/− mice also resist lethal inflammasome activation by the corresponding ligand. Furthermore, infections performed in the Naip-deficient macrophages have helped to define the major signal in Legionella pneumophila, Salmonella Typhimurium and Shigella flexneri that is detected by the NAIP/NLRC4 inflammasome. Using an engineered S. Typhimurium infection model, we demonstrate the critical role of NAIPs in clearing bacterial infection and protecting mice from bacterial virulence–induced lethality. These results provide definitive genetic evidence for the important physiological function of NAIPs in antibacterial defense and inflammatory damage–induced lethality in mice.
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Affiliation(s)
- Yue Zhao
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Jianjin Shi
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Xuyan Shi
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Yupeng Wang
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Fengchao Wang
- National Institute of Biological Sciences, 102206 Beijing, China
| | - Feng Shao
- National Institute of Biological Sciences, 102206 Beijing, China Collaborative Innovation Center for Cancer Medicine, National Institute of Biological Sciences, 102206 Beijing, China
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12
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Boucher D, Chen KW, Schroder K. Burn the house, save the day: pyroptosis in pathogen restriction. ACTA ACUST UNITED AC 2016. [DOI: 10.1515/infl-2015-0001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractMany programmed cell death pathways are essential for organogenesis, development, immunity and the maintenance of homeostasis in multicellular organisms. Pyroptosis, a highly proinflammatory form of cell death, is a critical innate immune response to prevent intracellular infection. Pyroptosis is induced upon the activation of proinflammatory caspases within macromolecular signalling platforms called inflammasomes. This article reviews our understanding of pyroptosis induction, the function of inflammatory caspases in pyroptosis execution, and the importance of pyroptosis for pathogen clearance. It also highlights the situations in which extensive pyroptosis may in fact be detrimental to the host, leading to immune cell depletion or cytokine storm. Current efforts to understand the beneficial and pathological roles of pyroptosis bring the promise of new approaches to fight infectious diseases.
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Roberts JS, Yilmaz Ӧ. Dangerous Liaisons: Caspase-11 and Reactive Oxygen Species Crosstalk in Pathogen Elimination. Int J Mol Sci 2015; 16:23337-54. [PMID: 26426007 PMCID: PMC4632701 DOI: 10.3390/ijms161023337] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 09/23/2015] [Accepted: 09/24/2015] [Indexed: 02/07/2023] Open
Abstract
Recently, the focus of murine caspase-11 and human orthologs caspase-4, -5 research has been on their novel function to induce noncanonical inflammasome activation in direct response to Gram-negative bacterial infection. On the other hand, a new role in anti-bacterial autophagy has been attributed to caspase-11, -4 and -5, which currently stands largely unexplored. In this review, we connect lately emerged evidence that suggests these caspases have a key role in anti-bacterial autophagy and discuss the growing implications of a danger molecule—extracellular ATP—and NADPH oxidase-mediated ROS generation as novel inducers of human caspase-4, -5 signaling during infection. We also highlight the adeptness of persistent pathogens like Porphyromonas gingivalis, a Gram-negative anaerobe and successful colonizer of oral mucosa, to potentially interfere with the activated caspase-4 pathway and autophagy. While, the ability of caspase-4, -5 to promote autophagolysosomal fusion is not well understood, the abundance of caspase-4 in skin and other mucosal epithelial cells implies an important role for caspase-4 in mucosal defense, supporting the view that caspase-4, -5 may play a non-redundant part in innate immunity. Thus, this review will join the currently disconnected cutting-edge research thereby proposing a working model for regulation of caspase-4, -5 in pathogen elimination via cellular-trafficking.
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Affiliation(s)
| | - Ӧzlem Yilmaz
- Department of Periodontology, University of Florida, P.O. Box 100434, Gainesville, FL 32610, USA.
- Emerging Pathogens Institute, University of Florida, P.O. Box 100434, Gainesville, FL 32610, USA.
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A group A Streptococcus ADP-ribosyltransferase toxin stimulates a protective interleukin 1β-dependent macrophage immune response. mBio 2015; 6:e00133. [PMID: 25759502 PMCID: PMC4453525 DOI: 10.1128/mbio.00133-15] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The M1T1 clone of group A Streptococcus (GAS) is associated with severe invasive infections, including necrotizing fasciitis and septicemia. During invasive M1T1 GAS disease, mutations in the covRS regulatory system led to upregulation of an ADP-ribosyltransferase, SpyA. Surprisingly, a GAS ΔspyA mutant was resistant to killing by macrophages and caused higher mortality with impaired bacterial clearance in a mouse intravenous challenge model. GAS expression of SpyA triggered macrophage cell death in association with caspase-1-dependent interleukin 1β (IL-1β) production, and differences between wild-type (WT) and ΔspyA GAS macrophage survival levels were lost in cells lacking caspase-1, NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), or pro-IL-1β. Similar in vitro findings were identified in macrophage studies performed with pseudomonal exotoxin A, another ADP-ribosylating toxin. Thus, SpyA triggers caspase-1-dependent inflammatory cell death in macrophages, revealing a toxin-triggered IL-1β-dependent innate immune response pathway critical in defense against invasive bacterial infection. Group A Streptococcus (GAS) is a leading human pathogen capable of producing invasive infections even in healthy individuals. GAS bacteria produce a toxin called SpyA that modifies host proteins through a process called ADP ribosylation. We describe how macrophages, frontline defenders of the host innate immune system, respond to SpyA by undergoing a specialized form of cell death in which they are activated to release the proinflammatory cytokine molecule interleukin 1β (IL-1β). Release of IL-1β activates host immune cell clearance of GAS, as we demonstrated in tissue culture models of macrophage bacterial killing and in vivo mouse infectious-challenge experiments. Similar macrophage responses to a related toxin of Pseudomonas bacteria were also shown. Thus, macrophages recognize certain bacterial toxins to activate a protective immune response in the host.
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Yang Q, Stevenson HL, Scott MJ, Ismail N. Type I interferon contributes to noncanonical inflammasome activation, mediates immunopathology, and impairs protective immunity during fatal infection with lipopolysaccharide-negative ehrlichiae. THE AMERICAN JOURNAL OF PATHOLOGY 2014; 185:446-61. [PMID: 25481711 DOI: 10.1016/j.ajpath.2014.10.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/18/2014] [Accepted: 10/09/2014] [Indexed: 12/29/2022]
Abstract
Ehrlichia species are intracellular bacteria that cause fatal ehrlichiosis, mimicking toxic shock syndrome in humans and mice. Virulent ehrlichiae induce inflammasome activation leading to caspase-1 cleavage and IL-18 secretion, which contribute to development of fatal ehrlichiosis. We show that fatal infection triggers expression of inflammasome components, activates caspase-1 and caspase-11, and induces host-cell death and secretion of IL-1β, IL-1α, and type I interferon (IFN-I). Wild-type and Casp1(-/-) mice were highly susceptible to fatal ehrlichiosis, had overwhelming infection, and developed extensive tissue injury. Nlrp3(-/-) mice effectively cleared ehrlichiae, but displayed acute mortality and developed liver injury similar to wild-type mice. By contrast, Ifnar1(-/-) mice were highly resistant to fatal disease and had lower bacterial burden, attenuated pathology, and prolonged survival. Ifnar1(-/-) mice also had improved protective immune responses mediated by IFN-γ and CD4(+) Th1 and natural killer T cells, with lower IL-10 secretion by T cells. Importantly, heightened resistance of Ifnar1(-/-) mice correlated with improved autophagosome processing, and attenuated noncanonical inflammasome activation indicated by decreased activation of caspase-11 and decreased IL-1β, compared with other groups. Our findings demonstrate that IFN-I signaling promotes host susceptibility to fatal ehrlichiosis, because it mediates ehrlichia-induced immunopathology and supports bacterial replication, perhaps via activation of noncanonical inflammasomes, reduced autophagy, and suppression of protective CD4(+) T cells and natural killer T-cell responses against ehrlichiae.
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Affiliation(s)
- Qin Yang
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Heather L Stevenson
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Melanie J Scott
- Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Nahed Ismail
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania.
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