1
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Cui X, Wang YT. Function of autophagy genes in innate immune defense against mucosal pathogens. Curr Opin Microbiol 2024; 79:102456. [PMID: 38554450 DOI: 10.1016/j.mib.2024.102456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 03/05/2024] [Accepted: 03/05/2024] [Indexed: 04/01/2024]
Abstract
Mucosal immunity is posed to constantly interact with commensal microbes and invading pathogens. As a fundamental cell biological pathway affecting immune response, autophagy regulates the interaction between mucosal immunity and microbes through multiple mechanisms, including direct elimination of microbes, control of inflammation, antigen presentation and lymphocyte homeostasis, and secretion of immune mediators. Some of these physiologically important functions do not involve canonical degradative autophagy but rely on certain autophagy genes and their 'autophagy gene-specific functions.' Here, we review the relationship between autophagy and important mucosal pathogens, including influenza virus, Mycobacterium tuberculosis, Salmonella enterica, Citrobacter rodentium, norovirus, and herpes simplex virus, with a particular focus on distinguishing the canonical versus gene-specific mechanisms of autophagy genes.
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Affiliation(s)
- Xiaoyan Cui
- Center for Infectious Disease Research, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China
| | - Ya-Ting Wang
- Center for Infectious Disease Research, School of Basic Medical Sciences, Tsinghua University, Beijing 100084, China; SXMU-Tsinghua Collaborative Innovation Center for Frontier Medicine, Shanxi Medical University, Taiyuan, Shanxi 030001, China.
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2
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Bhatnagar A, Chopra U, Raja S, Das KD, Mahalingam S, Chakravortty D, Srinivasula SM. TLR-mediated aggresome-like induced structures comprise antimicrobial peptides and attenuate intracellular bacterial survival. Mol Biol Cell 2024; 35:ar34. [PMID: 38170582 PMCID: PMC10916861 DOI: 10.1091/mbc.e23-09-0347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/07/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024] Open
Abstract
Immune cells employ diverse mechanisms for host defense. Macrophages, in response to TLR activation, assemble aggresome-like induced structures (ALIS). Our group has shown TLR4-signaling transcriptionally upregulates p62/sequestome1, which assembles ALIS. We have demonstrated that TLR4-mediated autophagy is, in fact, selective-autophagy of ALIS. We hypothesize that TLR-mediated autophagy and ALIS contribute to host-defense. Here we show that ALIS are assembled in macrophages upon exposure to different bacteria. These structures are associated with pathogen-containing phagosomes. Importantly, we present evidence of increased bacterial burden, where ALIS assembly is prevented with p62-specific siRNA. We have employed 3D-super-resolution structured illumination microscopy (3D-SR-SIM) and mass-spectrometric (MS) analyses to gain insight into the assembly of ALIS. Ultra-structural analyses of known constituents of ALIS (p62, ubiquitin, LC3) reveal that ALIS are organized structures with distinct patterns of alignment. Furthermore, MS-analyses of ALIS identified, among others, several proteins of known antimicrobial properties. We have validated MS data by testing the association of some of these molecules (Bst2, IFITM2, IFITM3) with ALIS and the phagocytosed-bacteria. We surmise that AMPs enrichment in ALIS leads to their delivery to bacteria-containing phagosomes and restricts the bacteria. Our findings in this paper support hitherto unknown functions of ALIS in host-defense.
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Affiliation(s)
- Anushree Bhatnagar
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram 695551, Kerala, India
| | - Umesh Chopra
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Sebastian Raja
- Laboratory of Molecular Cell Biology, Department of Biotechnology, Indian Institute of Technology-Madras, Chennai 600036, India
| | - Krishanu Dey Das
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram 695551, Kerala, India
| | - S. Mahalingam
- Laboratory of Molecular Cell Biology, Department of Biotechnology, Indian Institute of Technology-Madras, Chennai 600036, India
| | - Dipshikha Chakravortty
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram 695551, Kerala, India
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru, Karnataka 560012, India
| | - Srinivasa Murty Srinivasula
- School of Biology, Indian Institute of Science Education and Research Thiruvananthapuram, Maruthamala PO, Vithura, Thiruvananthapuram 695551, Kerala, India
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3
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Asiatic acid and andrographolide reduce hippocampal injury through suppressing neuroinflammation caused by Salmonella typhimurium infection. Food Chem Toxicol 2023; 172:113584. [PMID: 36581090 DOI: 10.1016/j.fct.2022.113584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 12/19/2022] [Accepted: 12/21/2022] [Indexed: 12/27/2022]
Abstract
Damage caused by Salmonella is not only limited to the gastrointestinal tract, but also occurs in the central nervous system (CNS). The aim of this study was to explore the protective effects of asiatic acid (AA) and andrographolide (AD) on the CNS through simulating common infection in mice by oral administration of Salmonella typhimurium (S. typhimurium). The results showed that the neurons in the hippocampus of mice were damaged after S. typhimurium invaded CNS in mice, and the inflammation was increased, which was manifested by the increased expression of inflammatory factors interleukin (IL)-1β, tumor necrosis factor (TNF)-α, IL-6, interferon (IFN)-γ and IL-12b and the activation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasomes. The damage and inflammatory response of mouse hippocampal neurons were effectively reduced by AA or AD pretreatment. Furthermore, we observed the significant activation of microglia after S. typhimurium infection. AA and AD attenuated S. typhimurium -induced hippocampal injury by reducing the inflammatory response on microglia. The findings suggest that the AA and AD protect CNS from injury caused by S. typhimurium infection through inhibiting over expression of multiple neuroinflammatory mediators and NLRP3 inflammasome in mice.
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4
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Klein JA, Powers TR, Knodler LA. Measurement of Salmonella enterica Internalization and Vacuole Lysis in Epithelial Cells. Methods Mol Biol 2023; 2692:209-220. [PMID: 37365470 DOI: 10.1007/978-1-0716-3338-0_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
Establishment of an intracellular niche within mammalian cells is key to the pathogenesis of the gastrointestinal bacterium, Salmonella enterica serovar Typhimurium (S. Typhimurium). Here we will describe how to study the internalization of S. Typhimurium into human epithelial cells using the gentamicin protection assay. The assay takes advantage of the relatively poor penetration of gentamicin into mammalian cells; internalized bacteria are effectively protected from its antibacterial actions. A second assay, the chloroquine (CHQ) resistance assay, can be used to determine the proportion of internalized bacteria that have lysed or damaged their Salmonella-containing vacuole and are therefore residing within the cytosol. Its application to the quantification of cytosolic S. Typhimurium in epithelial cells will also be presented. Together, these protocols provide an inexpensive, rapid, and sensitive quantitative measure of bacterial internalization and vacuole lysis by S. Typhimurium.
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Affiliation(s)
- Jessica A Klein
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - TuShun R Powers
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - Leigh A Knodler
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, USA.
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5
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Wang Y, Ramos M, Jefferson M, Zhang W, Beraza N, Carding S, Powell PP, Stewart JP, Mayer U, Wileman T. Control of infection by LC3-associated phagocytosis, CASM, and detection of raised vacuolar pH by the V-ATPase-ATG16L1 axis. SCIENCE ADVANCES 2022; 8:eabn3298. [PMID: 36288298 PMCID: PMC9604538 DOI: 10.1126/sciadv.abn3298] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 07/07/2022] [Indexed: 05/29/2023]
Abstract
The delivery of pathogens to lysosomes for degradation provides an important defense against infection. Degradation is enhanced when LC3 is conjugated to endosomes and phagosomes containing pathogens to facilitate fusion with lysosomes. In phagocytic cells, TLR signaling and Rubicon activate LC3-associated phagocytosis (LAP) where stabilization of the NADPH oxidase leads to sustained ROS production and raised vacuolar pH. Raised pH triggers the assembly of the vacuolar ATPase on the vacuole membrane where it binds ATG16L1 to recruit the core LC3 conjugation complex (ATG16L1:ATG5-12). This V-ATPase-ATG16L1 axis is also activated in nonphagocytic cells to conjugate LC3 to endosomes containing extracellular microbes. Pathogens provide additional signals for recruitment of LC3 when they raise vacuolar pH with pore-forming toxins and proteins, phospholipases, or specialized secretion systems. Many microbes secrete virulence factors to inhibit ROS production and/or the V-ATPase-ATG16L1 axis to slow LC3 recruitment and avoid degradation in lysosomes.
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Affiliation(s)
- Yingxue Wang
- Norwich Medical School, University of East Anglia, Norwich, UK
- Quadram Institute Bioscience, Norwich, UK
| | - Maria Ramos
- Norwich Medical School, University of East Anglia, Norwich, UK
- Quadram Institute Bioscience, Norwich, UK
| | | | - Weijiao Zhang
- Norwich Medical School, University of East Anglia, Norwich, UK
| | | | | | - Penny P. Powell
- Norwich Medical School, University of East Anglia, Norwich, UK
| | - James P. Stewart
- Department of Infection Biology, University of Liverpool, Liverpool, UK
| | - Ulrike Mayer
- School of Biological Sciences, University of East Anglia, Norwich, UK
| | - Thomas Wileman
- Norwich Medical School, University of East Anglia, Norwich, UK
- Quadram Institute Bioscience, Norwich, UK
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6
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Luk CH, Enninga J, Valenzuela C. Fit to dwell in many places – The growing diversity of intracellular Salmonella niches. Front Cell Infect Microbiol 2022; 12:989451. [PMID: 36061869 PMCID: PMC9433700 DOI: 10.3389/fcimb.2022.989451] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 07/25/2022] [Indexed: 11/21/2022] Open
Abstract
Salmonella enterica is capable of invading different host cell types including epithelial cells and M cells during local infection, and immune cells and fibroblasts during the subsequent systemic spread. The intracellular lifestyles of Salmonella inside different cell types are remarkable for their distinct residential niches, and their varying replication rates. To study this, researchers have employed different cell models, such as various epithelial cells, immune cells, and fibroblasts. In epithelial cells, S. Typhimurium dwells within modified endolysosomes or gains access to the host cytoplasm. In the cytoplasm, the pathogen is exposed to the host autophagy machinery or poised for rapid multiplication, whereas it grows at a slower rate or remains dormant within the endomembrane-bound compartments. The swift bimodal lifestyle is not observed in fibroblasts and immune cells, and it emerges that these cells handle intracellular S. Typhimurium through different clearance machineries. Moreover, in these cell types S. Typhimurium grows withing modified phagosomes of distinct functional composition by adopting targeted molecular countermeasures. The preference for one or the other intracellular niche and the diverse cell type-specific Salmonella lifestyles are determined by the complex interactions between a myriad of bacterial effectors and host factors. It is important to understand how this communication is differentially regulated dependent on the host cell type and on the distinct intracellular growth rate. To support the efforts in deciphering Salmonella invasion across the different infection models, we provide a systematic comparison of the findings yielded from cell culture models. We also outline the future directions towards a better understanding of these differential Salmonella intracellular lifestyles.
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Affiliation(s)
- Chak Hon Luk
- Institut Pasteur, Unité « Dynamique des interactions hôte-pathogène » and CNRS UMR3691, Université de Paris Cité, Paris, France
- Host-Pathogen Interactions in Tuberculosis Laboratory, The Francis Crick Institute, London, United Kingdom
- *Correspondence: Chak Hon Luk, ; Camila Valenzuela,
| | - Jost Enninga
- Institut Pasteur, Unité « Dynamique des interactions hôte-pathogène » and CNRS UMR3691, Université de Paris Cité, Paris, France
| | - Camila Valenzuela
- Institut Pasteur, Unité « Dynamique des interactions hôte-pathogène » and CNRS UMR3691, Université de Paris Cité, Paris, France
- *Correspondence: Chak Hon Luk, ; Camila Valenzuela,
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7
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Demeter A, Jacomin AC, Gul L, Lister A, Lipscombe J, Invernizzi R, Branchu P, Macaulay I, Nezis IP, Kingsley RA, Korcsmaros T, Hautefort I. Computational prediction and experimental validation of Salmonella Typhimurium SopE-mediated fine-tuning of autophagy in intestinal epithelial cells. Front Cell Infect Microbiol 2022; 12:834895. [PMID: 36061866 PMCID: PMC9428466 DOI: 10.3389/fcimb.2022.834895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
Macroautophagy is a ubiquitous homeostasis and health-promoting recycling process of eukaryotic cells, targeting misfolded proteins, damaged organelles and intracellular infectious agents. Some intracellular pathogens such as Salmonella enterica serovar Typhimurium hijack this process during pathogenesis. Here we investigate potential protein-protein interactions between host transcription factors and secreted effector proteins of Salmonella and their effect on host gene transcription. A systems-level analysis identified Salmonella effector proteins that had the potential to affect core autophagy gene regulation. The effect of a SPI-1 effector protein, SopE, that was predicted to interact with regulatory proteins of the autophagy process, was investigated to validate our approach. We then confirmed experimentally that SopE can directly bind to SP1, a host transcription factor, which modulates the expression of the autophagy gene MAP1LC3B. We also revealed that SopE might have a double role in the modulation of autophagy: Following initial increase of MAP1LC3B transcription triggered by Salmonella infection, subsequent decrease in MAP1LC3B transcription at 6h post-infection was SopE-dependent. SopE also played a role in modulation of the autophagy flux machinery, in particular MAP1LC3B and p62 autophagy proteins, depending on the level of autophagy already taking place. Upon typical infection of epithelial cells, the autophagic flux is increased. However, when autophagy was chemically induced prior to infection, SopE dampened the autophagic flux. The same was also observed when most of the intracellular Salmonella cells were not associated with the SCV (strain lacking sifA) regardless of the autophagy induction status before infection. We demonstrated how regulatory network analysis can be used to better characterise the impact of pathogenic effector proteins, in this case, Salmonella. This study complements previous work in which we had demonstrated that specific pathogen effectors can affect the autophagy process through direct interaction with autophagy proteins. Here we show that effector proteins can also influence the upstream regulation of the process. Such interdisciplinary studies can increase our understanding of the infection process and point out targets important in intestinal epithelial cell defense.
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Affiliation(s)
- Amanda Demeter
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
- Department of Genetics, Eotvos Lorand University, Budapest, Hungary
| | | | - Lejla Gul
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
| | - Ashleigh Lister
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
| | - James Lipscombe
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
| | - Rachele Invernizzi
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Priscilla Branchu
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
| | - Iain Macaulay
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
| | - Ioannis P. Nezis
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Robert A. Kingsley
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Tamas Korcsmaros
- Earlham Institute, Norwich Research Park, Norwich, United Kingdom
- Quadram Institute Bioscience, Norwich Research Park, Norwich, United Kingdom
- Faculty of Medicine, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, United Kingdom
- *Correspondence: Tamas Korcsmaros,
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8
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Pang Y, Wu L, Tang C, Wang H, Wei Y. Autophagy-Inflammation Interplay During Infection: Balancing Pathogen Clearance and Host Inflammation. Front Pharmacol 2022; 13:832750. [PMID: 35273506 PMCID: PMC8902503 DOI: 10.3389/fphar.2022.832750] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Accepted: 01/24/2022] [Indexed: 12/11/2022] Open
Abstract
Inflammation is an essential immune response of the host against infections but is often over-activated, leading to a variety of disorders. Autophagy, a conserved degradation pathway, also protects cells by capturing intracellular pathogens that enter the cell and transporting them to the lysosome for clearance. Dysfunctional autophagy is often associated with uncontrolled inflammatory responses during infection. In recent years, more and more research has focused on the crosstalk between autophagy and inflammation. In this paper, we review the latest research advances in this field, hoping to gain insight into the mechanisms by which the body balances autophagy and inflammation in infections and how this mechanism can be used to fight infections better.
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Affiliation(s)
- Yuqian Pang
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China.,Key Laboratory for Cell Homeostasis and Cancer Research of Guangdong Higher Education Institutes, Guangzhou, China
| | - Lanxi Wu
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China.,Key Laboratory for Cell Homeostasis and Cancer Research of Guangdong Higher Education Institutes, Guangzhou, China
| | - Cheng Tang
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China.,Key Laboratory for Cell Homeostasis and Cancer Research of Guangdong Higher Education Institutes, Guangzhou, China
| | - Hongna Wang
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China.,Key Laboratory for Cell Homeostasis and Cancer Research of Guangdong Higher Education Institutes, Guangzhou, China.,GMU-GIBH Joint School of Life Sciences, Guangzhou Medical University, Guangzhou, China
| | - Yongjie Wei
- Affiliated Cancer Hospital and Institute of Guangzhou Medical University, Guangzhou, China.,Key Laboratory for Cell Homeostasis and Cancer Research of Guangdong Higher Education Institutes, Guangzhou, China.,State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, Guangzhou, China
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9
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Lau N, Thomas DR, Lee YW, Knodler LA, Newton HJ. Perturbation of ATG16L1 function impairs the biogenesis of Salmonella and Coxiella replication vacuoles. Mol Microbiol 2022; 117:235-251. [PMID: 34874584 PMCID: PMC8844213 DOI: 10.1111/mmi.14858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 02/03/2023]
Abstract
Anti-bacterial autophagy, known as xenophagy, is a host innate immune response that targets invading pathogens for degradation. Some intracellular bacteria, such as the enteric pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), utilize effector proteins to interfere with autophagy. One such S. Typhimurium effector, SopF, inhibits recruitment of ATG16L1 to damaged Salmonella-containing vacuoles (SCVs), thereby inhibiting the host xenophagic response. SopF is also required to maintain the integrity of the SCV during the early stages of infection. Here we show disruption of the SopF-ATG16L1 interaction leads to an increased proportion of cytosolic S. Typhimurium. Furthermore, SopF was utilized as a molecular tool to examine the requirement for ATG16L1 in the intracellular lifestyle of Coxiella burnetii, a bacterium that requires a functional autophagy pathway to replicate efficiently and form a single, spacious vacuole called the Coxiella-containing vacuole (CCV). ATG16L1 is required for CCV expansion and fusion but does not influence C. burnetii replication. In contrast, SopF did not affect CCV formation or replication, demonstrating that the contribution of ATG16L1 to CCV biogenesis is via its role in autophagy, not xenophagy. This study highlights the diverse capabilities of bacterial effector proteins to dissect the molecular details of host-pathogen interactions.
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Affiliation(s)
- Nicole Lau
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - David R Thomas
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Yi Wei Lee
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Leigh A Knodler
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia.,Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Hayley J Newton
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
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10
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Chu BX, Li YN, Liu N, Yuan LX, Chen SY, Zhu YH, Wang JF. Salmonella Infantis Delays the Death of Infected Epithelial Cells to Aggravate Bacterial Load by Intermittent Phosphorylation of Akt With SopB. Front Immunol 2021; 12:757909. [PMID: 34804044 PMCID: PMC8602575 DOI: 10.3389/fimmu.2021.757909] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/19/2021] [Indexed: 11/13/2022] Open
Abstract
Salmonella Infantis has emerged as a major clinical pathogen causing gastroenteritis worldwide in recent years. As an intracellular pathogen, Salmonella has evolved to manipulate and benefit from the cell death signaling pathway. In this study, we discovered that S. Infantis inhibited apoptosis of infected Caco-2 cells by phosphorylating Akt. Notably, Akt phosphorylation was observed in a discontinuous manner: immediately 0.5 h after the invasion, then before peak cytosolic replication. Single-cell analysis revealed that the second phase was only induced by cytosolic hyper-replicating bacteria at 3-4 hpi. Next, Akt-mediated apoptosis inhibition was found to be initiated by Salmonella SopB. Furthermore, Akt phosphorylation increased mitochondrial localization of Bcl-2 to prevent Bax oligomerization on the mitochondrial membrane, maintaining the mitochondrial network homeostasis to resist apoptosis. In addition, S. Infantis induced pyroptosis, as evidenced by increased caspase-1 (p10) and GSDMS-N levels. In contrast, cells infected with the ΔSopB strain displayed faster but less severe pyroptosis and had less bacterial load. The results indicated that S. Infantis SopB-mediated Akt phosphorylation delayed pyroptosis, but aggravated its severity. The wild-type strain also caused more severe diarrhea and intestinal inflammatory damage than the ΔSopB strain in mice. These findings revealed that S. Infantis delayed the cells' death by intermittent activation of Akt, allowing sufficient time for replication, thereby causing more severe inflammation.
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Affiliation(s)
| | | | | | | | | | | | - Jiu-Feng Wang
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
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11
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Tripathi-Giesgen I, Behrends C, Alpi AF. The ubiquitin ligation machinery in the defense against bacterial pathogens. EMBO Rep 2021; 22:e52864. [PMID: 34515402 PMCID: PMC8567218 DOI: 10.15252/embr.202152864] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 07/21/2021] [Accepted: 08/27/2021] [Indexed: 12/12/2022] Open
Abstract
The ubiquitin system is an important part of the host cellular defense program during bacterial infection. This is in particular evident for a number of bacteria including Salmonella Typhimurium and Mycobacterium tuberculosis which—inventively as part of their invasion strategy or accidentally upon rupture of seized host endomembranes—become exposed to the host cytosol. Ubiquitylation is involved in the detection and clearance of these bacteria as well as in the activation of innate immune and inflammatory signaling. Remarkably, all these defense responses seem to emanate from a dense layer of ubiquitin which coats the invading pathogens. In this review, we focus on the diverse group of host cell E3 ubiquitin ligases that help to tailor this ubiquitin coat. In particular, we address how the divergent ubiquitin conjugation mechanisms of these ligases contribute to the complexity of the anti‐bacterial coating and the recruitment of different ubiquitin‐binding effectors. We also discuss the activation and coordination of the different E3 ligases and which strategies bacteria evolved to evade the activities of the host ubiquitin system.
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Affiliation(s)
- Ishita Tripathi-Giesgen
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Christian Behrends
- Munich Cluster for Systems Neurology (SyNergy), Medical Faculty, Ludwig-Maximilians-University München, München, Germany
| | - Arno F Alpi
- Department of Molecular Machines and Signaling, Max Planck Institute of Biochemistry, Martinsried, Germany
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12
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Powers TR, Haeberle AL, Predeus AV, Hammarlöf DL, Cundiff JA, Saldaña-Ahuactzi Z, Hokamp K, Hinton JCD, Knodler LA. Intracellular niche-specific profiling reveals transcriptional adaptations required for the cytosolic lifestyle of Salmonella enterica. PLoS Pathog 2021; 17:e1009280. [PMID: 34460873 PMCID: PMC8432900 DOI: 10.1371/journal.ppat.1009280] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 09/10/2021] [Accepted: 08/06/2021] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Typhimurium (S. Typhimurium) is a zoonotic pathogen that causes diarrheal disease in humans and animals. During salmonellosis, S. Typhimurium colonizes epithelial cells lining the gastrointestinal tract. S. Typhimurium has an unusual lifestyle in epithelial cells that begins within an endocytic-derived Salmonella-containing vacuole (SCV), followed by escape into the cytosol, epithelial cell lysis and bacterial release. The cytosol is a more permissive environment than the SCV and supports rapid bacterial growth. The physicochemical conditions encountered by S. Typhimurium within the epithelial cytosol, and the bacterial genes required for cytosolic colonization, remain largely unknown. Here we have exploited the parallel colonization strategies of S. Typhimurium in epithelial cells to decipher the two niche-specific bacterial virulence programs. By combining a population-based RNA-seq approach with single-cell microscopic analysis, we identified bacterial genes with cytosol-induced or vacuole-induced expression signatures. Using these genes as environmental biosensors, we defined that Salmonella is exposed to oxidative stress and iron and manganese deprivation in the cytosol and zinc and magnesium deprivation in the SCV. Furthermore, iron availability was critical for optimal S. Typhimurium replication in the cytosol, as well as entC, fepB, soxS, mntH and sitA. Virulence genes that are typically associated with extracellular bacteria, namely Salmonella pathogenicity island 1 (SPI1) and SPI4, showed increased expression in the cytosol compared to vacuole. Our study reveals that the cytosolic and vacuolar S. Typhimurium virulence gene programs are unique to, and tailored for, residence within distinct intracellular compartments. This archetypical vacuole-adapted pathogen therefore requires extensive transcriptional reprogramming to successfully colonize the mammalian cytosol.
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Affiliation(s)
- TuShun R. Powers
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States of America
| | - Amanda L. Haeberle
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States of America
| | - Alexander V. Predeus
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Disa L. Hammarlöf
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Jennifer A. Cundiff
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States of America
| | - Zeus Saldaña-Ahuactzi
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States of America
| | - Karsten Hokamp
- Smurfit Institute of Genetics, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland
| | - Jay C. D. Hinton
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Leigh A. Knodler
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, United States of America
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13
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Luk CH, Valenzuela C, Gil M, Swistak L, Bomme P, Chang YY, Mallet A, Enninga J. Salmonella enters a dormant state within human epithelial cells for persistent infection. PLoS Pathog 2021; 17:e1009550. [PMID: 33930101 PMCID: PMC8115778 DOI: 10.1371/journal.ppat.1009550] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 05/12/2021] [Accepted: 04/08/2021] [Indexed: 02/06/2023] Open
Abstract
Salmonella Typhimurium (S. Typhimurium) is an enteric bacterium capable of invading a wide range of hosts, including rodents and humans. It targets different host cell types showing different intracellular lifestyles. S. Typhimurium colonizes different intracellular niches and is able to either actively divide at various rates or remain dormant to persist. A comprehensive tool to determine these distinct S. Typhimurium lifestyles remains lacking. Here we developed a novel fluorescent reporter, Salmonella INtracellular Analyzer (SINA), compatible for fluorescence microscopy and flow cytometry in single-bacterium level quantification. This identified a S. Typhimurium subpopulation in infected epithelial cells that exhibits a unique phenotype in comparison to the previously documented vacuolar or cytosolic S. Typhimurium. This subpopulation entered a dormant state in a vesicular compartment distinct from the conventional Salmonella-containing vacuoles (SCV) as well as the previously reported niche of dormant S. Typhimurium in macrophages. The dormant S. Typhimurium inside enterocytes were viable and expressed Salmonella Pathogenicity Island 2 (SPI-2) virulence factors at later time points. We found that the formation of these dormant S. Typhimurium is not triggered by the loss of SPI-2 effector secretion but it is regulated by (p)ppGpp-mediated stringent response through RelA and SpoT. We predict that intraepithelial dormant S. Typhimurium represents an important pathogen niche and provides an alternative strategy for S. Typhimurium pathogenicity and its persistence. Salmonella Typhimurium is a clinically relevant bacterial pathogen that causes Salmonellosis. It can actively or passively invade various host cell types and reside in a Salmonella-containing vacuole (SCV) within host cells. The SCV can be remodeled into a replicative niche with the aid of Salmonella Type III Secretion System 2 (T3SS2) effectors or else, the SCV is ruptured for the access of the nutrient-rich host cytosol. Depending on the infected host cell type, S. Typhimurium undertake different lifestyles that are distinct by their subcellular localization, replication rate and metabolic rate. We present here a novel fluorescent reporter system that rapidly detects S. Typhimurium lifestyles using fluorescence microscopy and flow cytometry. We identified a dormant S. Typhimurium population within enterocyte that displays capacities in host cell persistence, dormancy exit and antibiotic tolerance. We deciphered the (p)ppGpp stringent response pathway that suppresses S. Typhimurium dormancy in enterocytes while promoting dormancy in macrophages, pinpointing a divergent physiological consequence regulated by the same set of S. Typhimurium molecular mediators. Altogether, our work demonstrated the potential of fluorescent reporters in facile bacterial characterization, and revealed a dormant S. Typhimurium population in human enterocytes that are phenotypically distinct from that observed in macrophages and fibroblasts.
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Affiliation(s)
- Chak Hon Luk
- Dynamics of Host-Pathogen Interactions Unit and UMR3691 CNRS, Institut Pasteur, Paris, France
- Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Camila Valenzuela
- Dynamics of Host-Pathogen Interactions Unit and UMR3691 CNRS, Institut Pasteur, Paris, France
| | - Magdalena Gil
- Dynamics of Host-Pathogen Interactions Unit and UMR3691 CNRS, Institut Pasteur, Paris, France
| | - Léa Swistak
- Dynamics of Host-Pathogen Interactions Unit and UMR3691 CNRS, Institut Pasteur, Paris, France
- Université de Paris, Sorbonne Paris Cité, Paris, France
| | - Perrine Bomme
- Ultrastructural Bioimaging UTechS, C2RT, Institut Pasteur, Paris, France
| | - Yuen-Yan Chang
- Dynamics of Host-Pathogen Interactions Unit and UMR3691 CNRS, Institut Pasteur, Paris, France
| | - Adeline Mallet
- Ultrastructural Bioimaging UTechS, C2RT, Institut Pasteur, Paris, France
| | - Jost Enninga
- Dynamics of Host-Pathogen Interactions Unit and UMR3691 CNRS, Institut Pasteur, Paris, France
- Université de Paris, Sorbonne Paris Cité, Paris, France
- * E-mail:
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14
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Autophagy-A Story of Bacteria Interfering with the Host Cell Degradation Machinery. Pathogens 2021; 10:pathogens10020110. [PMID: 33499114 PMCID: PMC7911818 DOI: 10.3390/pathogens10020110] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Revised: 01/18/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
Autophagy is a highly conserved and fundamental cellular process to maintain cellular homeostasis through recycling of defective organelles or proteins. In a response to intracellular pathogens, autophagy further acts as an innate immune response mechanism to eliminate pathogens. This review will discuss recent findings on autophagy as a reaction to intracellular pathogens, such as Salmonella typhimurium, Listeria monocytogenes, Mycobacterium tuberculosis, Staphylococcus aureus, and pathogenic Escherichia coli. Interestingly, while some of these bacteria have developed methods to use autophagy for their own benefit within the cell, others have developed fascinating mechanisms to evade recognition, to subvert the autophagic pathway, or to escape from autophagy.
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15
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Zhuang J, Ji X, Zhu Y, Liu W, Sun J, Jiao X, Xu X. Restriction of intracellular Salmonella typhimurium growth by the small-molecule autophagy inducer A77 1726 through the activation of the AMPK-ULK1 axis. Vet Microbiol 2021; 254:108982. [PMID: 33461007 DOI: 10.1016/j.vetmic.2021.108982] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 01/05/2021] [Indexed: 11/28/2022]
Abstract
Autophagy plays an important role in restricting the growth of invading intracellular microbes. Salmonella (S) Typhimurium, an intracellular pathogen that causes gastroenteritis and food poisoning in humans, evades autophagic detection by multiple mechanisms. There has been growing interest in developing autophagy inducers as novel antimicrobial agents for treating intracellular bacterial infections. We recently reported that A77 1726, the active metabolite of the anti-inflammatory drug leflunomide, induces autophagy by activating AMP-activated protein kinase (AMPK) and Unc-51 like autophagy activating kinase 1 (ULK1). Our present study aims to determine if A77 1726 was able to restrict intracellular Salmonella growth by inducing autophagy. We first confirmed the ability of A77 1726 to induce autophagy by activating the AMPK-ULK1 axis in uninfected RAW264.7 (a murine macrophage cell line) and HeLa cells (a human cervical carcinoma cell line). A77 1726 enhanced autophagy in S. Typhimurium-infected cells, as evidenced by increased levels of LC3 lipidation and increased numbers of autophagosomes and autolysosomes. Confocal microscopy revealed that A77 1726 induced xenophagy in macrophages, as evidenced by an increased number of LC3-coated bacteria in the cytoplasm. A77 1726 significantly decreased the number of intracellular S. Typhimurium in macrophages. Taken together, our study has demonstrated the ability of A77 1726 to restrict intracellular S. Typhimurium growth in vitro by enhancing xenophagy.
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Affiliation(s)
- Jing Zhuang
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China
| | - Xiaoyue Ji
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China
| | - Yue Zhu
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China
| | - Wei Liu
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China
| | - Jing Sun
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China
| | - Xinan Jiao
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China
| | - Xiulong Xu
- Institute of Comparative Medicine, College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu Province, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, 225009, PR China.
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16
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Yang H, Mirsepasi-Lauridsen HC, Struve C, Allaire JM, Sivignon A, Vogl W, Bosman ES, Ma C, Fotovati A, Reid GS, Li X, Petersen AM, Gouin SG, Barnich N, Jacobson K, Yu HB, Krogfelt KA, Vallance BA. Ulcerative Colitis-associated E. coli pathobionts potentiate colitis in susceptible hosts. Gut Microbes 2020; 12:1847976. [PMID: 33258388 PMCID: PMC7781664 DOI: 10.1080/19490976.2020.1847976] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Ulcerative colitis (UC) is a chronic inflammatory condition linked to intestinal microbial dysbiosis, including the expansion of E. coli strains related to extra-intestinal pathogenic E. coli. These "pathobionts" exhibit pathogenic properties, but their potential to promote UC is unclear due to the lack of relevant animal models. Here, we established a mouse model using a representative UC pathobiont strain (p19A), and mice lacking single immunoglobulin and toll-interleukin 1 receptor domain (SIGIRR), a deficiency increasing susceptibility to gut infections. Strain p19A was found to adhere to the cecal mucosa of Sigirr -/- mice, causing modest inflammation. Moreover, it dramatically worsened dextran sodium sulfate-induced colitis. This potentiation was attenuated using a p19A strain lacking α-hemolysin genes, or when we targeted pathobiont adherence using a p19A strain lacking the adhesin FimH, or following treatment with FimH antagonists. Thus, UC pathobionts adhere to the intestinal mucosa, and worsen the course of colitis in susceptible hosts.
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Affiliation(s)
- Hyungjun Yang
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada,CONTACT Hong Bing Yu Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada; Karen
| | - Hengameh Chloé Mirsepasi-Lauridsen
- Department of Bacteria, Parasites and Fungi, Statens Serum Institute, Copenhagen, Denmark,Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Carsten Struve
- Department of Bacteria, Parasites and Fungi, Statens Serum Institute, Copenhagen, Denmark
| | - Joannie M. Allaire
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Adeline Sivignon
- Université Clermont Auvergne, Laboratoire Microbes Intestin Inflammation Et Susceptibilité De l’Hôte (M2ish), Inserm U1071, M2iSH, F-63000, Clermont-Ferrand, France,INRA, Unité Sous Contrat 2018, Clermont-Ferrand, France
| | - Wayne Vogl
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Else S. Bosman
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Caixia Ma
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Abbas Fotovati
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Gregor S. Reid
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Xiaoxia Li
- Department of Immunology, Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA
| | - Andreas Munk Petersen
- Department of Gastroenterology, Copenhagen University Hospital, Hvidovre, Denmark,Department of Clinical Microbiology, Copenhagen University Hospital, Hvidovre, Denmark
| | - Sébastien G. Gouin
- Université De Nantes, Chimie Et Interdisciplinarité, Synthèse, Analyse, Modélisation (CEISAM), UMR CNRS 6230, UFR Des Sciences Et Des Techniques, Nantes, France
| | - Nicolas Barnich
- Université Clermont Auvergne, Laboratoire Microbes Intestin Inflammation Et Susceptibilité De l’Hôte (M2ish), Inserm U1071, M2iSH, F-63000, Clermont-Ferrand, France,INRA, Unité Sous Contrat 2018, Clermont-Ferrand, France
| | - Kevan Jacobson
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada
| | - Hong Bing Yu
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada,CONTACT Hong Bing Yu Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada; Karen
| | - Karen Angeliki Krogfelt
- Department of Bacteria, Parasites and Fungi, Statens Serum Institute, Copenhagen, Denmark,Angeliki Krogfelt
| | - Bruce A. Vallance
- Department of Pediatrics, BC Children’s Hospital, University of British Columbia, Vancouver, BC, Canada,Lead Contact,Bruce A. Vallance
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17
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Valenzuela C, Gil M, Urrutia ÍM, Sabag A, Enninga J, Santiviago CA. SopB- and SifA-dependent shaping of the Salmonella-containing vacuole proteome in the social amoeba Dictyostelium discoideum. Cell Microbiol 2020; 23:e13263. [PMID: 32945061 DOI: 10.1111/cmi.13263] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 09/07/2020] [Accepted: 09/09/2020] [Indexed: 02/06/2023]
Abstract
The ability of Salmonella to survive and replicate within mammalian host cells involves the generation of a membranous compartment known as the Salmonella-containing vacuole (SCV). Salmonella employs a number of effector proteins that are injected into host cells for SCV formation using its type-3 secretion systems encoded in SPI-1 and SPI-2 (T3SS-1 and T3SS-2, respectively). Recently, we reported that S. Typhimurium requires T3SS-1 and T3SS-2 to survive in the model amoeba Dictyostelium discoideum. Despite these findings, the involved effector proteins have not been identified yet. Therefore, we evaluated the role of two major S. Typhimurium effectors SopB and SifA during D. discoideum intracellular niche formation. First, we established that S. Typhimurium resides in a vacuolar compartment within D. discoideum. Next, we isolated SCVs from amoebae infected with wild type or the ΔsopB and ΔsifA mutant strains of S. Typhimurium, and we characterised the composition of this compartment by quantitative proteomics. This comparative analysis suggests that S. Typhimurium requires SopB and SifA to modify the SCV proteome in order to generate a suitable intracellular niche in D. discoideum. Accordingly, we observed that SopB and SifA are needed for intracellular survival of S. Typhimurium in this organism. Thus, our results provide insight into the mechanisms employed by Salmonella to survive intracellularly in phagocytic amoebae.
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Affiliation(s)
- Camila Valenzuela
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.,Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur, Paris, France.,CNRS UMR3691, Paris, France
| | - Magdalena Gil
- Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur, Paris, France.,CNRS UMR3691, Paris, France
| | - Ítalo M Urrutia
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Andrea Sabag
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Jost Enninga
- Dynamics of Host-Pathogen Interactions Unit, Institut Pasteur, Paris, France.,CNRS UMR3691, Paris, France
| | - Carlos A Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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18
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Xie Z, Zhang Y, Huang X. Evidence and speculation: the response of Salmonella confronted by autophagy in macrophages. Future Microbiol 2020; 15:1277-1286. [PMID: 33026883 DOI: 10.2217/fmb-2020-0125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria of the Salmonella genus cause diseases ranging from self-limited gastroenteritis to typhoid fever. Macrophages are immune cells that engulf and restrict Salmonella. These cells will carry Salmonella into the circulatory system and provoke a systemic infection. Therefore, the interaction between macrophages and intracellular Salmonella is vital for its pathogenicity. As one of the immune responses of macrophages, autophagy, along with the fusion of autophagosomes with lysosomes, occupies an important position in eliminating Salmonella. However, Salmonella that can overcome cellular defensive responses and infect neighboring cells must derive strategies to escape autophagy. This review introduces novel findings on Salmonella and macrophage autophagy as a mechanism against infection and explores the strategies used by Salmonella to escape autophagy.
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Affiliation(s)
- Zhongyi Xie
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.,International Genome Center, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Ying Zhang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Xinxiang Huang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
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19
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Zhang L, Sun Y, Xu W, Geng Y, Su Y, Wang Q, Wang J. Baicalin inhibits Salmonella typhimurium-induced inflammation and mediates autophagy through TLR4/MAPK/NF-κB signalling pathway. Basic Clin Pharmacol Toxicol 2020; 128:241-255. [PMID: 32955161 DOI: 10.1111/bcpt.13497] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 08/23/2020] [Accepted: 09/13/2020] [Indexed: 01/08/2023]
Abstract
Baicalin has been reported to protect mice against Salmonella typhimurium (S. typhimurium) infection, while its molecular mechanisms are unclear. In this study, multiplicity of infection (MOI) and observation time were measured. Cell viability and LDH levels were examined in RAW264.7 cells and H9 cells. RAW264.7 cells were stimulated with S typhimurium in the presence or absence of Baicalin, and the levels of pro-inflammatory cytokines were detected by enzyme-linked immunosorbent assay (ELISA). The changes in reactive oxygen species (ROS) production were determined by fluorescence microscopy and ELISA. The autophagy and TLR4/MAPK/NF-κB signalling pathway were examined by immunofluorescence microscopy, quantitative reverse transcription-polymerase chain reaction and Western blotting. The results indicated that MOI of 30 and duration of autophagy evident at 5 h were applicable to this study. Baicalin prevented death of macrophages, promoted bactericidal activity, decreased the levels of pro-inflammatory cytokines and ROS and reduced the changes of key biomarkers in autophagy and TLR4/MAPK/NF-κB signalling pathway infected by S typhimurium. TLR4-overexpressed cells, autophagy and TLR4/MAPK/NF-κB signalling pathway were activated by S typhimurium, which was suppressed by Baicalin. Our findings indicated that Baicalin exerts anti-inflammatory and cell-protective effects, and it mediates autophagy by down-regulating the activity of TLR4 infected by S typhimurium.
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Affiliation(s)
- Ling Zhang
- School of Basic Medical Sciences, Jinzhou Medical University, Jinzhou, China
| | - Yuan Sun
- First Affiliated Hospital, Jinzhou Medical University, Jinzhou, China
| | - Wei Xu
- First Affiliated Hospital, Jinzhou Medical University, Jinzhou, China
| | - Yu Geng
- Healthcare Management School, Jinzhou Medical University, Jinzhou, China
| | - Yuhong Su
- Institute of Animal Husbandry and Veterinary Medicine, Jinzhou Medical University, Jinzhou, China
| | - Qiuning Wang
- School of Basic Medical Sciences, Jinzhou Medical University, Jinzhou, China
| | - Jinli Wang
- Institute of Animal Husbandry and Veterinary Medicine, Jinzhou Medical University, Jinzhou, China
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20
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Chu B, Zhu Y, Su J, Xia B, Zou Y, Nie J, Zhang W, Wang J. Butyrate-mediated autophagy inhibition limits cytosolic Salmonella Infantis replication in the colon of pigs treated with a mixture of Lactobacillus and Bacillus. Vet Res 2020; 51:99. [PMID: 32758277 PMCID: PMC7409499 DOI: 10.1186/s13567-020-00823-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/22/2020] [Indexed: 01/07/2023] Open
Abstract
Probiotics as an effective and safe strategy for controlling Salmonella infection are much sought after, while autophagy is a central issue in eliminating intracellular pathogens of intestinal epithelial cells. In this study, an animal model of colitis has been developed by infecting weaned pigs orally with a strain of Salmonella Infantis in order to illuminate the potential efficacy of a mixture of Lactobacillus and Bacillus (CBB-MIX) in the resistance to Salmonella infection by regulating butyrate-mediated autophagy. We found that CBB-MIX alleviated S. Infantis-induced colitis and tissue damage. Autophagy markers ATG5, Beclin-1, and the LC3-II/I ratio were significantly enhanced by S. Infantis infection, while treatment with CBB-MIX suppressed S. Infantis-induced autophagy. Additionally, S. Infantis-induced colonic microbial dysbiosis was restored by this treatment, which also preserved the abundance of the butyrate-producing bacteria and the butyrate concentration in the colon. A Caco-2 cell model of S. Infantis infection showed that butyrate had the same effect as the CBB-MIX in restraining S. Infantis-induced autophagy activation. Further, the intracellular S. Infantis load assay indicated that butyrate restricted the replication of cytosolic S. Infantis rather than that in Salmonella-containing vacuoles. Suppression of autophagy by knockdown of ATG5 also attenuated S. Infantis-induced cell injury. Moreover, hyper-replication of cytosolic S. Infantis in Caco-2 cells was significantly decreased when autophagy was inhibited. Our data demonstrated that Salmonella may benefit from autophagy for cytosolic replication and butyrate-mediated autophagy inhibition reduced the intracellular Salmonella load in pigs treated with a probiotic mixture of Lactobacillus and Bacillus.
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Affiliation(s)
- Bingxin Chu
- College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, People's Republic of China
| | - Yaohong Zhu
- College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, People's Republic of China
| | - Jinhui Su
- College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, People's Republic of China
| | - Bing Xia
- College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, People's Republic of China
| | - Yunjing Zou
- College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, People's Republic of China
| | - Jiawei Nie
- College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, People's Republic of China
| | - Wei Zhang
- Institute of Animal Husbandry and Veterinary Medicine, Beijing Academy of Agriculture and Forestry Sciences, No. 9 Shuguanghuayuan Middle Road, Beijing, 100097, People's Republic of China.
| | - Jiufeng Wang
- College of Veterinary Medicine, China Agricultural University, No. 2 Yuanmingyuan West Road, Beijing, 100193, People's Republic of China.
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21
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Mao M, Chang CC, Pickar-Oliver A, Cervia LD, Wang L, Ji J, Liton PB, Gersbach CA, Yuan F. Redirecting Vesicular Transport to Improve Nonviral Delivery of Molecular Cargo. ADVANCED BIOSYSTEMS 2020; 4:e2000059. [PMID: 33179869 PMCID: PMC7747957 DOI: 10.1002/adbi.202000059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/06/2020] [Indexed: 01/09/2023]
Abstract
Cell engineering relies heavily on viral vectors for the delivery of molecular cargo into cells due to their superior efficiency compared to nonviral ones. However, viruses are immunogenic and expensive to manufacture, and have limited delivery capacity. Nonviral delivery approaches avoid these limitations but are currently inefficient for clinical applications. This work demonstrates that the efficiency of nonviral delivery of plasmid DNA, mRNA, Sleeping Beauty transposon, and ribonucleoprotein can be significantly enhanced through pretreatment of cells with the nondegradable sugars (NDS), such as sucrose, trehalose, and raffinose. The enhancement is mediated by the incorporation of the NDS into cell membranes, causing enlargement of lysosomes and formation of large (>500 nm) amphisome-like bodies (ALBs). The changes in subcellular structures redirect transport of cargo to ALBs rather than to lysosomes, reducing cargo degradation in cells. The data indicate that pretreatment of cells with NDS is a promising approach to improve nonviral cargo delivery in biomedical applications.
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Affiliation(s)
- Mao Mao
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Chun-Chi Chang
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Adrian Pickar-Oliver
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, 27708, USA
| | - Lisa D Cervia
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Liangli Wang
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Jing Ji
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
| | - Paloma B Liton
- Department of Ophthalmology, Duke University, Durham, NC, 27708, USA
| | - Charles A Gersbach
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Center for Advanced Genomic Technologies, Duke University, Durham, NC, 27708, USA
- Department of Surgery, Duke University Medical Center, Durham, NC, 27708, USA
| | - Fan Yuan
- Department of Biomedical Engineering, Duke University, Durham, NC, 27708, USA
- Department of Ophthalmology, Duke University, Durham, NC, 27708, USA
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22
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Wu S, Shen Y, Zhang S, Xiao Y, Shi S. Salmonella Interacts With Autophagy to Offense or Defense. Front Microbiol 2020; 11:721. [PMID: 32390979 PMCID: PMC7188831 DOI: 10.3389/fmicb.2020.00721] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/27/2020] [Indexed: 12/20/2022] Open
Abstract
Autophagy is an important component of the innate immune system in mammals. Low levels of basic autophagy are sustained in normal cells, to help with the clearance of aging organelles and misfolded proteins, thus maintaining their structural and functional stability. However, when cells are faced with challenges, such as starvation or pathogenic infection, their level of autophagy increases significantly. Salmonella is a facultative intracellular pathogen, which imposes an economic burden on the poultry farming industry and human public health. Previous studies have shown that Salmonella can induce the autophagy of cells following invasion, which to a certain extent helps to protect the cells from bacterial colonization. This review summarizes the latest research in the field of Salmonella-induced autophagy, including: (i) the autophagy induction and escape mechanisms employed by Salmonella during the infection of host cells; (ii) the effect of autophagy on intracellular Salmonella; (iii) the important autophagy adaptors that recognize intracellular Salmonella in host cells; and (iv) the effect of autophagy-modulating drugs on Salmonella infection.
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Affiliation(s)
- Shu Wu
- Department of Feed and Nutrition, Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Institute of Effective Evaluation of Feed and Feed Additive (Poultry institute), Ministry of Agriculture, Yangzhou, China.,College of Animal Science and Technology, Hunan Agricultural University, Changsha, China
| | - Yiru Shen
- Department of Feed and Nutrition, Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Institute of Effective Evaluation of Feed and Feed Additive (Poultry institute), Ministry of Agriculture, Yangzhou, China
| | - Shan Zhang
- Department of Feed and Nutrition, Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Institute of Effective Evaluation of Feed and Feed Additive (Poultry institute), Ministry of Agriculture, Yangzhou, China
| | - Yunqi Xiao
- Department of Feed and Nutrition, Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Institute of Effective Evaluation of Feed and Feed Additive (Poultry institute), Ministry of Agriculture, Yangzhou, China
| | - Shourong Shi
- Department of Feed and Nutrition, Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Institute of Effective Evaluation of Feed and Feed Additive (Poultry institute), Ministry of Agriculture, Yangzhou, China.,Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, China
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23
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Jiao Y, Sun J. Bacterial Manipulation of Autophagic Responses in Infection and Inflammation. Front Immunol 2019; 10:2821. [PMID: 31849988 PMCID: PMC6901625 DOI: 10.3389/fimmu.2019.02821] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 11/15/2019] [Indexed: 01/07/2023] Open
Abstract
Eukaryotes have cell-autonomous defenses against environmental stress and pathogens. Autophagy is one of the main cellular defenses against intracellular bacteria. In turn, bacteria employ diverse mechanisms to interfere with autophagy initiation and progression to avoid elimination and even to subvert autophagy for their benefit. This review aims to discuss recent findings regarding the autophagic responses regulated by bacterial effectors. Effectors manipulate autophagy at different stages by using versatile strategies, such as interfering with autophagy-initiating signaling, preventing the recognition of autophagy-involved proteins, subverting autophagy component homeostasis, manipulating the autophagy process, and impacting other biological processes. We describe the barriers for intracellular bacteria in host cells and highlight the role of autophagy in the host-microbial interactions. Understanding the mechanisms through which bacterial effectors manipulate host responses will provide new insights into therapeutic approaches for prevention and treatment of chronic inflammation and infectious diseases.
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Affiliation(s)
- Yang Jiao
- Division of Gastroenterology and Hepatology, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Jun Sun
- Division of Gastroenterology and Hepatology, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
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24
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Xiong Q, Yang M, Li P, Wu C. Bacteria Exploit Autophagy For Their Own Benefit. Infect Drug Resist 2019; 12:3205-3215. [PMID: 31632106 PMCID: PMC6792943 DOI: 10.2147/idr.s220376] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 09/25/2019] [Indexed: 01/18/2023] Open
Abstract
Autophagy is a lysosomal degradation pathway to clear long-lived proteins, protein aggregates, and damaged organelles. Certain microorganisms can be eliminated by an autophagic degradation process termed xenophagy. However, many pathogens deploy highly evolved mechanisms to evade autophagic degradation. What is more, series of pathogens have developed different strategies to exploit autophagy to ensure their survival. These bacteria could induce autophagy and/or prevent autophagosomes fusion with lysosomes through secreted effector proteins or utilizing host components, thereby maintaining the localization of the bacteria within the autophagosomes where they replicate. Here, we review the current knowledge of the mechanisms developed by the bacteria to benefit from autophagy for their survival.
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Affiliation(s)
- Qiuhong Xiong
- Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Min Yang
- Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Ping Li
- Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, People's Republic of China
| | - Changxin Wu
- Institutes of Biomedical Sciences, Shanxi University, Taiyuan 030006, People's Republic of China
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25
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Zhang F, Chen C, Hu J, Su R, Zhang J, Han Z, Chen H, Li Y. Molecular mechanism of Helicobacter pylori-induced autophagy in gastric cancer. Oncol Lett 2019; 18:6221-6227. [PMID: 31788098 DOI: 10.3892/ol.2019.10976] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 07/26/2019] [Indexed: 12/14/2022] Open
Abstract
Helicobacter pylori (H. pylori) is a gram-negative pathogen that colonizes gastric epithelial cells. The drug resistance rates of H. pylori have dramatically increased, causing persistent infections. Chronic infection by H. pylori is a critical cause of gastritis, peptic ulcers and even gastric cancer. In host cells, autophagy is stimulated to maintain cellular homeostasis following intracellular pathogen recognition by the innate immune defense system. However, H. pylori-induced autophagy is not consistent during acute and chronic infection. Therefore, a deeper understanding of the association between H. pylori infection and autophagy in gastric epithelial cells could aid the understanding of the mechanisms of persistent infection and the identification of autophagy-associated therapeutic targets for H. pylori infection. The present review describes the role of H. pylori and associated virulence factors in the induction of autophagy by different signaling pathways during acute infection. Additionally, the inhibition of autophagy in gastric epithelial cells during chronic infection was discussed. The present review summarized H. pylori-mediated autophagy and provided insights into its mechanism of action, suggesting the induction of autophagy as a novel therapeutic target for persistent H. pylori infection.
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Affiliation(s)
- Fan Zhang
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Cong Chen
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Jike Hu
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Ruiliang Su
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Junqiang Zhang
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Zhijian Han
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Hao Chen
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
| | - Yumin Li
- Department of Oncology Surgery, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China.,Key Laboratory of Digestive System Tumors of Gansu Province, Lanzhou University Second Hospital, Lanzhou, Gansu 730030, P.R. China
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26
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Autophagy Induction by a Small Molecule Inhibits Salmonella Survival in Macrophages and Mice. Antimicrob Agents Chemother 2019:AAC.01536-19. [PMID: 31591121 PMCID: PMC6879225 DOI: 10.1128/aac.01536-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Salmonella enterica is a natural bacterial pathogen of humans and animals that causes systemic infection or gastroenteritis. During systemic infection, Salmonella generally resides within professional phagocytes, typically macrophages, whereas gastroenteritis is caused by infection of epithelial cells. We are only beginning to understand which host pathways contribute to Salmonella survival in particular cell types. Salmonella enterica is a natural bacterial pathogen of humans and animals that causes systemic infection or gastroenteritis. During systemic infection, Salmonella generally resides within professional phagocytes, typically macrophages, whereas gastroenteritis is caused by infection of epithelial cells. We are only beginning to understand which host pathways contribute to Salmonella survival in particular cell types. We therefore sought to identify compounds that perturb Salmonella-host interactions using a chemical genetics approach. We found one small molecule, D61, that reduces Salmonella load in cell line and primary macrophages but has no effect on Salmonella growth in epithelial cells or rich medium. We determined that in macrophages, D61 induces LC3II, a marker of the autophagy pathway, and promotes aggregation of LC3II near Salmonella. We found that D61 antibacterial activity depends on the VPS34 complex and on ATG5. D61 also reduced Salmonella load in the spleens and livers of infected mice. Lastly, we demonstrate that D61 antibacterial activity in macrophages is synergistic with the antibiotic chloramphenicol but that this synergy is largely independent of the known autophagy-stimulating activity of chloramphenicol. Thus, a small molecule has antibacterial activity specifically in macrophages and mice based on the promotion of bacterial degradation by autophagy. These observations demonstrate the potential therapeutic utility of stimulating autophagy in cells and animals to curb infection.
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27
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Lau N, Haeberle AL, O’Keeffe BJ, Latomanski EA, Celli J, Newton HJ, Knodler LA. SopF, a phosphoinositide binding effector, promotes the stability of the nascent Salmonella-containing vacuole. PLoS Pathog 2019; 15:e1007959. [PMID: 31339948 PMCID: PMC6682159 DOI: 10.1371/journal.ppat.1007959] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 08/05/2019] [Accepted: 07/02/2019] [Indexed: 12/19/2022] Open
Abstract
The enteric bacterial pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), utilizes two type III secretion systems (T3SSs) to invade host cells, survive and replicate intracellularly. T3SS1 and its dedicated effector proteins are required for bacterial entry into non-phagocytic cells and establishment and trafficking of the nascent Salmonella-containing vacuole (SCV). Here we identify the first T3SS1 effector required to maintain the integrity of the nascent SCV as SopF. SopF associates with host cell membranes, either when translocated by bacteria or ectopically expressed. Recombinant SopF binds to multiple phosphoinositides in protein-lipid overlays, suggesting that it targets eukaryotic cell membranes via phospholipid interactions. In yeast, the subcellular localization of SopF is dependent on the activity of Mss4, a phosphatidylinositol 4-phosphate 5-kinase that generates PI(4,5)P2 from PI(4)P, indicating that membrane recruitment of SopF requires specific phospholipids. Ectopically expressed SopF partially colocalizes with specific phosphoinositide pools present on the plasma membrane in mammalian cells and with cytoskeletal-associated markers at the leading edge of cells. Translocated SopF concentrates on plasma membrane ruffles and around intracellular bacteria, presumably on the SCV. SopF is not required for bacterial invasion of non-phagocytic cells but is required for maintenance of the internalization vacuole membrane as infection with a S. Typhimurium ΔsopF mutant led to increased lysis of the SCV compared to wild type bacteria. Our structure-function analysis shows that the carboxy-terminal seven amino acids of SopF are essential for its membrane association in host cells and to promote SCV membrane stability. We also describe that SopF and another T3SS1 effector, SopB, act antagonistically to modulate nascent SCV membrane dynamics. In summary, our study highlights that a delicate balance of type III effector activities regulates the stability of the Salmonella internalization vacuole.
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Affiliation(s)
- Nicole Lau
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States of America
| | - Amanda L. Haeberle
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States of America
| | - Brittany J. O’Keeffe
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States of America
| | - Eleanor A. Latomanski
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Jean Celli
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States of America
| | - Hayley J. Newton
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail: (LAK); (HJN)
| | - Leigh A. Knodler
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States of America
- * E-mail: (LAK); (HJN)
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28
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Liao J, Orsi RH, Carroll LM, Kovac J, Ou H, Zhang H, Wiedmann M. Serotype-specific evolutionary patterns of antimicrobial-resistant Salmonella enterica. BMC Evol Biol 2019; 19:132. [PMID: 31226931 PMCID: PMC6588947 DOI: 10.1186/s12862-019-1457-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 06/11/2019] [Indexed: 12/28/2022] Open
Abstract
Background The emergence of antimicrobial-resistant (AMR) strains of the important human and animal pathogen Salmonella enterica poses a growing threat to public health. Here, we studied the genome-wide evolution of 90 S. enterica AMR isolates, representing one host adapted serotype (S. Dublin) and two broad host range serotypes (S. Newport and S. Typhimurium). Results AMR S. Typhimurium had a large effective population size, a large and diverse genome, AMR profiles with high diversity, and frequent positive selection and homologous recombination. AMR S. Newport showed a relatively low level of diversity and a relatively clonal population structure. AMR S. Dublin showed evidence for a recent population bottleneck, and the genomes were characterized by a larger number of genes and gene ontology terms specifically absent from this serotype and a significantly higher number of pseudogenes as compared to other two serotypes. Approximately 50% of accessory genes, including specific AMR and putative prophage genes, were significantly over- or under-represented in a given serotype. Approximately 65% of the core genes showed phylogenetic clustering by serotype, including the AMR gene aac (6′)-Iaa. While cell surface proteins were shown to be the main target of positive selection, some proteins with possible functions in AMR and virulence also showed evidence for positive selection. Homologous recombination mainly acted on prophage-associated proteins. Conclusions Our data indicates a strong association between genome content of S. enterica and serotype. Evolutionary patterns observed in S. Typhimurium are consistent with multiple emergence events of AMR strains and/or ecological success of this serotype in different hosts or habitats. Evolutionary patterns of S. Newport suggested that antimicrobial resistance emerged in one single lineage, Lineage IIC. A recent population bottleneck and genome decay observed in AMR S. Dublin are congruent with its narrow host range. Finally, our results suggest the potentially important role of positive selection in the evolution of antimicrobial resistance, host adaptation and serotype diversification in S. enterica. Electronic supplementary material The online version of this article (10.1186/s12862-019-1457-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jingqiu Liao
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA.,Graduate Field of Microbiology, Cornell University, Ithaca, NY, 14853, USA
| | - Renato Hohl Orsi
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA
| | - Laura M Carroll
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA
| | - Jasna Kovac
- Department of Food Science, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Hongyu Ou
- School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Hailong Zhang
- Department of Computer Science & Engineering, Ohio State University, Columbus, OH, 43210, USA
| | - Martin Wiedmann
- Department of Food Science, 341 Stocking Hall, Cornell University, Ithaca, NY, 14853, USA.
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29
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Mishra R, Upadhyay A, Prajapati VK, Dhiman R, Poluri KM, Jana NR, Mishra A. LRSAM1 E3 ubiquitin ligase: molecular neurobiological perspectives linked with brain diseases. Cell Mol Life Sci 2019; 76:2093-2110. [PMID: 30826859 PMCID: PMC11105512 DOI: 10.1007/s00018-019-03055-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 02/13/2019] [Accepted: 02/21/2019] [Indexed: 01/01/2023]
Abstract
Cellular protein quality control (PQC) plays a significant role in the maintenance of cellular homeostasis. Failure of PQC mechanism may lead to various neurodegenerative diseases due to accumulation of aberrant proteins. To avoid such fatal neuronal conditions PQC employs autophagy and ubiquitin proteasome system (UPS) to degrade misfolded proteins. Few quality control (QC) E3 ubiquitin ligases interplay an important role to specifically recognize misfolded proteins for their intracellular degradation. Leucine-rich repeat and sterile alpha motif-containing 1 (LRSAM1) is a really interesting new gene (RING) class protein that possesses E3 ubiquitin ligase activity with promising applications in PQC. LRSAM1 is also known as RING finger leucine repeat rich (RIFLE) or TSG 101-associated ligase (TAL). LRSAM1 has various cellular functions as it modulates the protein aggregation, endosomal sorting machinery and virus egress from the cells. Thus, this makes LRSAM1 interesting to study not only in protein conformational disorders such as neurodegeneration but also in immunological and other cancerous disorders. Furthermore, LRSAM1 interacts with both cellular protein degradation machineries and hence it can participate in maintenance of overall cellular proteostasis. Still, more research work on the quality control molecular functions of LRSAM1 is needed to comprehend its roles in various protein aggregatory diseases. Earlier findings suggest that in a mouse model of Charcot-Marie-Tooth (CMT) disease, lack of LRSAM1 functions sensitizes peripheral axons to degeneration. It has been observed that in CMT the patients retain dominant and recessive mutations of LRSAM1 gene, which encodes most likely a defective protein. However, still the comprehensive molecular pathomechanism of LRSAM1 in neuronal functions and neurodegenerative diseases is not known. The current article systematically represents the molecular functions, nature and detailed characterization of LRSAM1 E3 ubiquitin ligase. Here, we review emerging molecular mechanisms of LRSAM1 linked with neurobiological functions, with a clear focus on the mechanism of neurodegeneration and also on other diseases. Better understanding of LRSAM1 neurobiological and intracellular functions may contribute to develop promising novel therapeutic approaches, which can also propose new lines of molecular beneficial targets for various neurodegenerative diseases.
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Affiliation(s)
- Ribhav Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan, 342037, India
| | - Arun Upadhyay
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan, 342037, India
| | - Vijay Kumar Prajapati
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, NH-8 Bandarsindri, Ajmer, Rajasthan, 305817, India
| | - Rohan Dhiman
- Laboratory of Mycobacterial Immunology, Department of Life Science, National Institute of Technology, Rourkela, Odisha, 769008, India
| | - Krishna Mohan Poluri
- Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India
| | - Nihar Ranjan Jana
- School of Bioscience, Indian Institute of Technology, Kharagpur, Kharagpur, 721302, India
| | - Amit Mishra
- Cellular and Molecular Neurobiology Unit, Indian Institute of Technology Jodhpur, Jodhpur, Rajasthan, 342037, India.
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30
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Masud S, Prajsnar TK, Torraca V, Lamers GE, Benning M, Van Der Vaart M, Meijer AH. Macrophages target Salmonella by Lc3-associated phagocytosis in a systemic infection model. Autophagy 2019; 15:796-812. [PMID: 30676840 PMCID: PMC6526873 DOI: 10.1080/15548627.2019.1569297] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 01/03/2019] [Accepted: 01/08/2019] [Indexed: 11/08/2022] Open
Abstract
Innate immune defense against intracellular pathogens, like Salmonella, relies heavily on the autophagy machinery of the host. This response is studied intensively in epithelial cells, the target of Salmonella during gastrointestinal infections. However, little is known of the role that autophagy plays in macrophages, the predominant carriers of this pathogen during systemic disease. Here we utilize a zebrafish embryo model to study the interaction of S. enterica serovar Typhimurium with the macroautophagy/autophagy machinery of macrophages in vivo. We show that phagocytosis of live but not heat-killed Salmonella triggers recruitment of the autophagy marker GFP-Lc3 in a variety of patterns labeling tight or spacious bacteria-containing compartments, also revealed by electron microscopy. Neutrophils display similar GFP-Lc3 associations, but genetic modulation of the neutrophil/macrophage balance and ablation experiments show that macrophages are critical for the defense response. Deficiency of atg5 reduces GFP-Lc3 recruitment and impairs host resistance, in contrast to atg13 deficiency, indicating that Lc3-Salmonella association at this stage is independent of the autophagy preinitiation complex and that macrophages target Salmonella by Lc3-associated phagocytosis (LAP). In agreement, GFP-Lc3 recruitment and host resistance are impaired by deficiency of Rubcn/Rubicon, known as a negative regulator of canonical autophagy and an inducer of LAP. We also found strict dependency on NADPH oxidase, another essential factor for LAP. Both Rubcn and NADPH oxidase are required to activate a Salmonella biosensor for reactive oxygen species inside infected macrophages. These results identify LAP as the major host protective autophagy-related pathway responsible for macrophage defense against Salmonella during systemic infection. Abbreviations: ATG: autophagy related gene; BECN1: Beclin 1; CFU: colony forming units; CYBA/P22PHOX: cytochrome b-245, alpha chain; CYBB/NOX2: cytochrome b-245 beta chain; dpf: days post fertilization; EGFP: enhanced green fluorescent protein; GFP: green fluorescent protein; hfp: hours post fertilization; hpi: hours post infection; IRF8: interferon regulatory factor 8; Lcp1/L-plastin: lymphocyte cytosolic protein 1; LAP: LC3-associated phagocytosis; MAP1LC3/LC3: microtubule-associated protein 1A/1B-light chain 3; mCherry: red fluorescent protein; mpeg1: macrophage expressed gene 1; mpx: myeloid specific peroxidase; NADPH oxidase: nicotinamide adenine dinucleotide phosphate oxidase; NCF4/P40PHOX: neutrophil cytosolic factor 4; NTR-mCherry: nitroreductase-mCherry fusion; PTU: phenylthiourea; PtdIns3K: class III phosphatidylinositol 3-kinase; PtdIns3P: phosphatidylinositol 3-phosphate; RB1CC1/FIP200: RB-1 inducible coiled coin 1; ROS: reactive oxygen species; RT-PCR: reverse transcriptase polymerase chain reaction; RUBCN/RUBICON: RUN and cysteine rich domain containing BECN1-interacting protein; SCV: Salmonella-containing vacuole; S. Typhimurium/S.T: Salmonella enterica serovar Typhimurium; TEM: transmission electron microscopy; Tg: transgenic; TSA: tyramide signal amplification; ULK1/2: unc-51-like autophagy activating kinase 1/2; UVRAG: UVRAG: UV radiation resistance associated; wt: wild type.
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Affiliation(s)
- Samrah Masud
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | | | - Vincenzo Torraca
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Gerda E.M. Lamers
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
| | - Marianne Benning
- Institute of Biology Leiden, Leiden University, Leiden, The Netherlands
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31
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Sarkar A, Tindle C, Pranadinata RF, Reed S, Eckmann L, Stappenbeck TS, Ernst PB, Das S. ELMO1 Regulates Autophagy Induction and Bacterial Clearance During Enteric Infection. J Infect Dis 2019; 216:1655-1666. [PMID: 29029244 DOI: 10.1093/infdis/jix528] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Macrophages are specialized phagocytic cells involved in clearing invading pathogens. Previously we reported that engulfment and cell motility protein 1 (ELMO1) in macrophages mediates bacterial internalization and intestinal inflammation. Here we studied the role of ELMO1 in the fate of internalized targets. ELMO1 is present in the intracellular vesicles and enhances accumulation of the protein LC3B following engulfment of Salmonella or treatment with autophagy-inducing rapamycin. The protein ATG5 and the kinase ULK1 are involved in classical autophagy, while LC3-associated phagocytosis is ULK1 independent. ATG5 but not ULK1 cooperated with ELMO1 in LC3 accumulation after infection, suggesting the ELMO1 preferentially regulated LC3-associated phagocytosis. Because LC3-associated phagocytosis delivers cargo for degradation, the contribution of ELMO1 to the lysosome degradation pathways was evaluated by studying pH and cathepsin B activity. ELMO1-depleted macrophages showed a time-dependent increase in pH and a decrease in cathepsin B activity associated with bacterial survival. Together, ELMO1 regulates LC3B accumulation and antimicrobial responses involved in the clearance of enteric pathogens. This paper investigated how innate immune pathways involving ELMO1 work in a coordinated fashion to eliminate bacterial threats. ELMO1 is present in the phagosome and enhances bacterial clearance by differential regulation of lysosomal acidification and enzymatic activity.
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Affiliation(s)
- Arup Sarkar
- Department of Pathology, University of California-San Diego
| | | | | | - Sharon Reed
- Department of Pathology, University of California-San Diego
| | - Lars Eckmann
- Department of Medicine, University of California-San Diego
| | | | - Peter B Ernst
- Department of Pathology, University of California-San Diego
| | - Soumita Das
- Department of Pathology, University of California-San Diego
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32
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Silva HM, Báfica A, Rodrigues-Luiz GF, Chi J, Santos PDA, Reis BS, Hoytema van Konijnenburg DP, Crane A, Arifa RDN, Martin P, Mendes DAGB, Mansur DS, Torres VJ, Cadwell K, Cohen P, Mucida D, Lafaille JJ. Vasculature-associated fat macrophages readily adapt to inflammatory and metabolic challenges. J Exp Med 2019; 216:786-806. [PMID: 30862706 PMCID: PMC6446877 DOI: 10.1084/jem.20181049] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 12/10/2018] [Accepted: 02/19/2019] [Indexed: 01/08/2023] Open
Abstract
Silva et al. describe and characterize a population of adipose tissue macrophages (VAMs) that are in close contact with the vasculature and powerfully uptake blood-borne macromolecules. VAMs harbor a repair/detoxifying gene signature and adapt quickly to infections and fasting. Tissue-resident macrophages are the most abundant immune cell population in healthy adipose tissue. Adipose tissue macrophages (ATMs) change during metabolic stress and are thought to contribute to metabolic syndrome. Here, we studied ATM subpopulations in steady state and in response to nutritional and infectious challenges. We found that tissue-resident macrophages from healthy epididymal white adipose tissue (eWAT) tightly associate with blood vessels, displaying very high endocytic capacity. We refer to these cells as vasculature-associated ATMs (VAMs). Chronic high-fat diet (HFD) results in the accumulation of a monocyte-derived CD11c+CD64+ double-positive (DP) macrophage eWAT population with a predominant anti-inflammatory/detoxifying gene profile, but reduced endocytic function. In contrast, fasting rapidly and reversibly leads to VAM depletion, while acute inflammatory stress induced by pathogens transiently depletes VAMs and simultaneously boosts DP macrophage accumulation. Our results indicate that ATM populations dynamically adapt to metabolic stress and inflammation, suggesting an important role for these cells in maintaining tissue homeostasis.
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Affiliation(s)
- Hernandez Moura Silva
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY
| | - André Báfica
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY.,Laboratório de Imunobiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil.,Laboratory of Mucosal Immunology, The Rockefeller University, New York, NY
| | - Gabriela Flavia Rodrigues-Luiz
- Laboratório de Imunobiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Jingyi Chi
- Laboratory of Molecular Metabolism, The Rockefeller University, New York, NY
| | - Patricia d'Emery Alves Santos
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY
| | - Bernardo S Reis
- Laboratory of Mucosal Immunology, The Rockefeller University, New York, NY
| | | | - Audrey Crane
- Laboratory of Molecular Metabolism, The Rockefeller University, New York, NY
| | - Raquel Duque Nascimento Arifa
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY
| | - Patricia Martin
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY
| | - Daniel Augusto G B Mendes
- Laboratório de Imunobiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Daniel Santos Mansur
- Laboratório de Imunobiologia, Departamento de Microbiologia, Imunologia e Parasitologia, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Victor J Torres
- Department of Microbiology, New York University School of Medicine, New York, NY
| | - Ken Cadwell
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY.,Department of Microbiology, New York University School of Medicine, New York, NY
| | - Paul Cohen
- Laboratory of Molecular Metabolism, The Rockefeller University, New York, NY
| | - Daniel Mucida
- Laboratory of Mucosal Immunology, The Rockefeller University, New York, NY
| | - Juan J Lafaille
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY .,Department of Pathology, New York University School of Medicine, New York, NY
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Lobato‐Márquez D, Krokowski S, Sirianni A, Larrouy‐Maumus G, Mostowy S. A requirement for septins and the autophagy receptor p62 in the proliferation of intracellular Shigella. Cytoskeleton (Hoboken) 2019; 76:163-172. [PMID: 29752866 PMCID: PMC6519264 DOI: 10.1002/cm.21453] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/11/2018] [Accepted: 05/09/2018] [Indexed: 12/28/2022]
Abstract
Shigella flexneri, a Gram-negative enteroinvasive pathogen, causes inflammatory destruction of the human intestinal epithelium. During infection of epithelial cells, Shigella escape from the phagosome to the cytosol, where they reroute host cell glycolysis to obtain nutrients for proliferation. Septins, a poorly understood component of the cytoskeleton, can entrap cytosolic Shigella targeted to autophagy in cage-like structures to restrict bacterial proliferation. Although bacterial entrapment by septin caging has been the subject of intense investigation, the role of septins and the autophagy machinery in the proliferation of noncaged Shigella is mostly unknown. Here, we found that intracellular Shigella fail to efficiently proliferate in SEPT2-, SEPT7-, or p62/SQSTM1-depleted cells. Consistent with a failure to proliferate, single cell analysis of bacteria not entrapped in septin cages showed that the number of metabolically active Shigella in septin- or p62-depleted cells is reduced. Targeted metabolomic analysis revealed that host cell glycolysis is dysregulated in septin-depleted cells, suggesting a key role for septins in modulation of glycolysis. Together, these results suggest that septins and the autophagy machinery may regulate metabolic pathways that promote the proliferation of intracellular Shigella not entrapped in septin cages.
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Affiliation(s)
- Damián Lobato‐Márquez
- MRC Centre for Molecular Bacteriology and Infection, Department of MedicineSection of Microbiology, Imperial College LondonLondonUnited Kingdom
- Department of Immunology and InfectionLondon School of Hygiene and Tropical Medicine, Keppel StreetLondonUnited Kingdom
| | - Sina Krokowski
- MRC Centre for Molecular Bacteriology and Infection, Department of MedicineSection of Microbiology, Imperial College LondonLondonUnited Kingdom
- Department of Immunology and InfectionLondon School of Hygiene and Tropical Medicine, Keppel StreetLondonUnited Kingdom
| | - Andrea Sirianni
- MRC Centre for Molecular Bacteriology and Infection, Department of MedicineSection of Microbiology, Imperial College LondonLondonUnited Kingdom
| | - Gerald Larrouy‐Maumus
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Faculty of Natural SciencesImperial College LondonLondonUnited Kingdom
| | - Serge Mostowy
- MRC Centre for Molecular Bacteriology and Infection, Department of MedicineSection of Microbiology, Imperial College LondonLondonUnited Kingdom
- Department of Immunology and InfectionLondon School of Hygiene and Tropical Medicine, Keppel StreetLondonUnited Kingdom
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Kim SP, Lee SJ, Nam SH, Friedman M. The composition of a bioprocessed shiitake (Lentinus edodes) mushroom mycelia and rice bran formulation and its antimicrobial effects against Salmonella enterica subsp. enterica serovar Typhimurium strain SL1344 in macrophage cells and in mice. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2018; 18:322. [PMID: 30518352 PMCID: PMC6282263 DOI: 10.1186/s12906-018-2365-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 10/29/2018] [Indexed: 02/06/2023]
Abstract
Background Human infection by pathogenic Salmonella bacteria can be acquired by consuming of undercooked meat products and eggs. Antimicrobial resistance against antibiotics used in medicine is also a major concern. To help overcome these harmful effects on microbial food safety and human health, we are developing novel antimicrobial food-compatible formulations, one of which is described in the present study. Methods The composition of a bioprocessed (fermented) rice bran extract (BPRBE) from Lentinus edodes liquid mycelia culture was evaluated using gas chromatography and mass spectrometry, and the mechanism of its antibacterial effect against Salmonella Typhimurium, strain SL1344 was investigated in macrophage cells and in mice. Results BPRBE stimulated uptake of the bacteria into RAW 264.7 murine macrophage cells. Activation of the cells was confirmed by increases in NO production resulting from the elevation of inducible nitric oxide synthase (iNOS) mRNA, and in protein expression. Salmonella infection down-regulated the expression of the following protein biomarkers of autophagy (a catabolic process for stress adaptation of cellular components): Beclin-1, Atg5, Atg12, Atg16, LC3-I and LC3-II. BPRBE promoted the upregulation of protein expressions that induced bacterial destruction in autolysosomes of RAW 264.7 cells. ELISA analysis of interferon IFN-β showed that inflammatory cytokine secretion and bactericidal activity had similar profiles, suggesting that BPRBE enhances cell-autonomous and systemic bactericidal activities via autophagic capture of Salmonella. The treatment also elicited increased excretion of bacteria in feces and their decreased translocation to internal organs (cecum, mesenteric lymph node, spleen, and liver). Conclusions The antibiotic mechanism of BPRBE involves the phagocytosis of extracellular bacteria, autophagic capture of intracellular bacteria, and prevention of translocation of bacteria across the intestinal epithelial cells. The new bioprocessing combination of mushroom mycelia and rice brans forms a potentially novel food formulation with in vivo antimicrobial properties that could serve as a functional antimicrobial food and medical antibiotic.
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Flieger A, Frischknecht F, Häcker G, Hornef MW, Pradel G. Pathways of host cell exit by intracellular pathogens. MICROBIAL CELL 2018; 5:525-544. [PMID: 30533418 PMCID: PMC6282021 DOI: 10.15698/mic2018.12.659] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Host cell exit is a critical step in the life-cycle of intracellular pathogens, intimately linked to barrier penetration, tissue dissemination, inflammation, and pathogen transmission. Like cell invasion and intracellular survival, host cell exit represents a well-regulated program that has evolved during host-pathogen co-evolution and that relies on the dynamic and intricate interplay between multiple host and microbial factors. Three distinct pathways of host cell exit have been identified that are employed by three different taxa of intracellular pathogens, bacteria, fungi and protozoa, namely (i) the initiation of programmed cell death, (ii) the active breaching of host cellderived membranes, and (iii) the induced membrane-dependent exit without host cell lysis. Strikingly, an increasing number of studies show that the majority of intracellular pathogens utilize more than one of these strategies, dependent on life-cycle stage, environmental factors and/or host cell type. This review summarizes the diverse exit strategies of intracellular-living bacterial, fungal and protozoan pathogens and discusses the convergently evolved commonalities as well as system-specific variations thereof. Key microbial molecules involved in host cell exit are highlighted and discussed as potential targets for future interventional approaches.
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Affiliation(s)
- Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch Institute, Wernigerode, Germany
| | | | - Georg Häcker
- Institute of Medical Microbiology and Hygiene, Medical Center - University of Freiburg, Germany
| | - Mathias W Hornef
- Institute of Medical Microbiology, RWTH Aachen University Hospital, Germany
| | - Gabriele Pradel
- Division of Cellular and Applied Infection Biology, Institute of Biology II, RWTH Aachen University, Germany
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Singh PK, Kapoor A, Lomash RM, Kumar K, Kamerkar SC, Pucadyil TJ, Mukhopadhyay A. Salmonella SipA mimics a cognate SNARE for host Syntaxin8 to promote fusion with early endosomes. J Cell Biol 2018; 217:4199-4214. [PMID: 30309979 PMCID: PMC6279372 DOI: 10.1083/jcb.201802155] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 08/17/2018] [Accepted: 09/18/2018] [Indexed: 01/06/2023] Open
Abstract
Intracellular pathogens can modulate host Rabs and SNAREs to support their replication and immune evasion. Singh et al. show that the Salmonella effector SipA functionally mimics an R-SNARE and recruits host Q-SNAREs to promote membrane fusion. Thus, SNARE mimicry by this intracellular pathogen effector modulates the host trafficking machinery for Salmonella survival. SipA is a major effector of Salmonella, which causes gastroenteritis and enteric fever. Caspase-3 cleaves SipA into two domains: the C-terminal domain regulates actin polymerization, whereas the function of the N terminus is unknown. We show that the cleaved SipA N terminus binds and recruits host Syntaxin8 (Syn8) to Salmonella-containing vacuoles (SCVs). The SipA N terminus contains a SNARE motif with a conserved arginine residue like mammalian R-SNAREs. SipAR204Q and SipA1–435R204Q do not bind Syn8, demonstrating that SipA mimics a cognate R-SNARE for Syn8. Consequently, Salmonella lacking SipA or that express the SipA1–435R204Q SNARE mutant are unable to recruit Syn8 to SCVs. Finally, we show that SipA mimicking an R-SNARE recruits Syn8, Syn13, and Syn7 to the SCV and promotes its fusion with early endosomes to potentially arrest its maturation. Our results reveal that SipA functionally substitutes endogenous SNAREs in order to hijack the host trafficking pathway and promote Salmonella survival.
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Affiliation(s)
| | - Anjali Kapoor
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | | | - Kamal Kumar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
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Zhang L, Hu W, Cho CH, Chan FK, Yu J, Fitzgerald JR, Cheung CK, Xiao ZG, Shen J, Li LF, Li MX, Wu JC, Ling TK, Chan JY, Ko H, Tse G, Ng SC, Yu S, Wang MH, Gin T, Ashktorab H, Smoot DT, Wong SH, Chan MT, Wu WK. Reduced lysosomal clearance of autophagosomes promotes survival and colonization of Helicobacter pylori. J Pathol 2018; 244:432-444. [PMID: 29327342 DOI: 10.1002/path.5033] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 11/20/2017] [Accepted: 01/04/2018] [Indexed: 01/25/2023]
Abstract
Evasion of autophagy is key for intracellular survival of bacteria in host cells, but its involvement in persistent infection by Helicobacter pylori, a bacterium identified to invade gastric epithelial cells, remains obscure. The aim of this study was to functionally characterize the role of autophagy in H. pylori infection. Autophagy was assayed in H. pylori-infected human gastric epithelium and the functional role of autophagy was determined via genetic or pharmacological ablation of autophagy in mouse and cell line models of H. pylori infection. Here, we showed that H. pylori inhibited lysosomal function and thereby promoted the accumulation of autophagosomes in gastric epithelial cells. Importantly, inhibiting autophagosome formation by pharmacological inhibitors or genetic ablation of BECN1 or ATG5 reduced H. pylori intracellular survival, whereas inhibition of lysosomal functions exerted an opposite effect. Further experiments demonstrated that H. pylori inhibited lysosomal acidification and the retrograde trafficking of mannose-6-phosphate receptors, both of which are known to positively regulate lysosomal function. We conclude that H. pylori subverts autophagy into a pro-survival mechanism through inhibition of lysosomal clearance of autophagosomes. Disruption of autophagosome formation offers a novel strategy to reduce H. pylori colonization in human stomachs. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Lin Zhang
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Wei Hu
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Chi H Cho
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China.,School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Francis Kl Chan
- Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Jun Yu
- Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | | | - Cynthia Ky Cheung
- Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Zhan G Xiao
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Jing Shen
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Long F Li
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Ming X Li
- Laboratory of Molecular Pharmacology, Department of Pharmacology, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan, PR China
| | - Justin Cy Wu
- Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Thomas Kw Ling
- Department of Microbiology, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Jason Yk Chan
- Department of Otorhinolaryngology, Head and Neck Surgery, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Ho Ko
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Gary Tse
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Siew C Ng
- Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Sidney Yu
- School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Maggie Ht Wang
- The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Tony Gin
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Hassan Ashktorab
- Department of Medicine, Howard University, Washington, DC, USA.,Cancer Center, Howard University, Washington, DC, USA.,Howard University Hospital, Howard University, Washington, DC, USA
| | - Duane T Smoot
- Department of Internal Medicine, Meharry Medical College, Nashville, TN, USA
| | - Sunny H Wong
- Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Department of Otorhinolaryngology, Head and Neck Surgery, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - Matthew Tv Chan
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong SAR, PR China
| | - William Kk Wu
- Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Hong Kong SAR, PR China.,Institute of Digestive Diseases, State Key Laboratory of Digestive Diseases, LKS Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, PR China
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Abstract
More than a century ago, infections by Salmonella were already associated with foodborne enteric diseases with high morbidity in humans and cattle. Intestinal inflammation and diarrhea are hallmarks of infections caused by nontyphoidal Salmonella serovars, and these pathologies facilitate pathogen transmission to the environment. In those early times, physicians and microbiologists also realized that typhoid and paratyphoid fever caused by some Salmonella serovars could be transmitted by "carriers," individuals outwardly healthy or at most suffering from some minor chronic complaint. In his pioneering study of the nontyphoidal serovar Typhimurium in 1967, Takeuchi published the first images of intracellular bacteria enclosed by membrane-bound vacuoles in the initial stages of the intestinal epithelium penetration. These compartments, called Salmonella-containing vacuoles, are highly dynamic phagosomes with differing biogenesis depending on the host cell type. Single-cell studies involving real-time imaging and gene expression profiling, together with new approaches based on genetic reporters sensitive to growth rate, have uncovered unprecedented heterogeneous responses in intracellular bacteria. Subpopulations of intracellular bacteria displaying fast, reduced, or no growth, as well as cytosolic and intravacuolar bacteria, have been reported in both in vitro and in vivo infection models. Recent investigations, most of them focused on the serovar Typhimurium, point to the selection of persisting bacteria inside macrophages or following an autophagy attack in fibroblasts. Here, we discuss these heterogeneous intracellular lifestyles and speculate on how these disparate behaviors may impact host-to-host transmissibility of Salmonella serovars.
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Singh P, Subbian S. Harnessing the mTOR Pathway for Tuberculosis Treatment. Front Microbiol 2018; 9:70. [PMID: 29441052 PMCID: PMC5797605 DOI: 10.3389/fmicb.2018.00070] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/11/2018] [Indexed: 01/23/2023] Open
Abstract
Tuberculosis (TB) remains as one of the leading killer infectious diseases of humans. At present, the standard therapeutic regimen to treat TB comprised of multiple antibiotics administered for a minimum of six months. Although these drugs are useful in controlling TB burden globally, they have not eliminated the disease. In addition, the lengthy duration of treatment with multiple drugs contributes to patient non-compliance that can result in the development of drug resistant strains (MDR and XDR) of Mycobacterium tuberculosis (Mtb), the causative agent of TB. Therefore, new and improved therapeutic strategies are urgently needed for effective control of TB worldwide. The intracellular survival of Mtb is regarded as a cumulative effect of the host immune response and the bacterial ability to resist or subvert this response. When the host innate defensive system is manipulated by Mtb for its survival and dissemination, the host develops disease conditions that are hard to overcome. The host intrinsic factors also contributes to the poor efficacy of anti-mycobacterial drugs and to the emergence of drug resistance. Hence, strengthening the immune repertoire involved in combating Mtb through host-directed therapeutics (HDT) can be one of the approaches for effective bacterial killing and clearance of infection/disease. Recently, more scientific research has been focused toward HDT strategies that empowers host cells for effective killing of Mtb, reduce the duration of treatment and/or alleviates the development of MDR/XDR, since Mtb cannot develop resistance against a drug that targets the host cell function. Autophagy is a conserved cellular process critical for maintaining cellular integrity and function. Autophagy is regulated by multiple pathways that are either dependent or independent of mTOR (mechanistic target of rapamycin; a.k.a. mammalian target of rapamycin), a master regulatory molecules that impacts several cellular functions. In this review, we summarize the role of autophagy in Mtb pathogenesis, the mTOR pathway and, modulating the mTOR pathway with inhibitors as potential adjunctive HDT, in combination with standard anti-TB antibiotics, to improve the outcome of current TB treatment.
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Affiliation(s)
- Pooja Singh
- Public Health Research Institute at New Jersey Medical School, Rutgers Biomedical and Health Sciences Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Selvakumar Subbian
- Public Health Research Institute at New Jersey Medical School, Rutgers Biomedical and Health Sciences Rutgers, The State University of New Jersey, Newark, NJ, United States
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40
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Zhang W, Zhu YH, Yang GY, Liu X, Xia B, Hu X, Su JH, Wang JF. Lactobacillus rhamnosus GG Affects Microbiota and Suppresses Autophagy in the Intestines of Pigs Challenged with Salmonella Infantis. Front Microbiol 2018; 8:2705. [PMID: 29403451 PMCID: PMC5785727 DOI: 10.3389/fmicb.2017.02705] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/29/2017] [Indexed: 12/20/2022] Open
Abstract
Salmonella enterica serovar Infantis (S. Infantis) is a common source of foodborne gastroenteritis worldwide. Here, Lactobacillus rhamnosus GG (LGG) was administrated to weaned piglets for 1 week before S. Infantis challenge. S. Infantis caused decreased ileal mucosal microbiota diversity, a dramatic Lactobacillus amylovorus bloom, and decreased abundance of Arsenicicoccus, Janibacter, Kocuria, Nocardioides, Devosia, Paracoccus, Psychrobacter, and Weissella. The beneficial effect of LGG correlated with the moderate expansion of L. amylovorus, L. agilis, and several members of the phyla Proteobacteria, Firmicutes, and Bacteroidetes. S. Infantis translocation to the liver was decreased in the LGG-pretreated piglets. An in vitro model of LGG and S. Infantis co-incubation (involving the porcine intestinal epithelial cell line IPEC-J2) was established, and nalidixic acid was used to kill the extracellular S. Infantis. LGG suppressed the initial S. Infantis invasion in the IPEC-J2 cells and deceased the rate of cell death. LGG inhibited S. Infantis-induced autophagy and promoted epidermal growth factor receptor (EGFR) and Akt phosphorylation in both the ileum and IPEC-J2 cells. Our findings suggest that LGG inhibited S. Infantis-induced autophagy by promoting EGFR-mediated activation of the negative mediator Akt, which, in turn, suppressed intestinal epithelial cell death and thus restricted systemic S. Infantis infection. LGG can restore the gut microbiota balance and preserve the autophagy-related intestinal epithelial barrier, thereby controlling infections.
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Affiliation(s)
- Wei Zhang
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Yao-Hong Zhu
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Gui-Yan Yang
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiao Liu
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Bing Xia
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Xiong Hu
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jin-Hui Su
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
| | - Jiu-Feng Wang
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, China Agricultural University, Beijing, China
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41
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Brothers KM, Kowalski RP, Tian S, Kinchington PR, Shanks RMQ. Bacteria induce autophagy in a human ocular surface cell line. Exp Eye Res 2017; 168:12-18. [PMID: 29288646 DOI: 10.1016/j.exer.2017.12.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 12/24/2017] [Indexed: 12/18/2022]
Abstract
Autophagy protects cells from intracellular pathogens, but can be exploited by some infectious agents to their benefit. Currently it is not known if bacteria induce autohpagy in cells of the cornea. The goal of this study was to develop an ocular surface autophagy reporter cell line and determine whether ocular bacterial pathogens influence host responses through autophagy induction. The cell line was made using lentivirus transduction of an LC3-GFP fusion protein in human corneal limbal epithelial (HCLE) cells. LC3-GFP puncta in HCLEs were induced by rapamycin and ammonium chloride treatments, and prevented by the autophagy inhibitors 3-methyladenine (3'MA) and bafilomycin. Importantly, secretomes from Escherichia coli, Serratia marcescens, Staphylococcus aureus, methicillin sensitive (MSSA) and resistant (MRSA), were found to induce autophagy, whereas other bacteria, including Acinetobacter baumannii, Achromobacter xylosoxidans, Enterococcus faecalis, Klebsiella pneumoniae, Moraxella sp., and Stenotrophomonas maltophilia, did not. Our data indicates differences between tested ocular isolates of MRSA and MSSA in the activation of autophagy. HCLEs treated with 3'MA were slightly more susceptible to cytotoxic factors produced by S. marcescens and MRSA keratitis isolates, by contrast, bafilomycin A1 treatment caused no difference. This work demonstrates the successful development and validation of an autophagy reporter corneal cell line and indicates differences between ocular bacterial isolates in the activation of autophagy.
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Affiliation(s)
- Kimberly M Brothers
- The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Regis P Kowalski
- The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Shenghe Tian
- The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Paul R Kinchington
- The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Robert M Q Shanks
- The Charles T. Campbell Ophthalmic Microbiology Laboratory, Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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42
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Radomski N, Rebbig A, Leonhardt RM, Knittler MR. Xenophagic pathways and their bacterial subversion in cellular self-defense - παντα ρει - everything is in flux. Int J Med Microbiol 2017; 308:185-196. [PMID: 29126745 DOI: 10.1016/j.ijmm.2017.10.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 10/24/2017] [Accepted: 10/29/2017] [Indexed: 01/09/2023] Open
Abstract
Autophagy is an evolutionarily ancient and highly conserved eukaryotic mechanism that targets cytoplasmic material for degradation. Autophagic flux involves the formation of autophagosomes and their degradation by lysosomes. The process plays a crucial role in maintaining cellular homeostasis and responds to various environmental conditions. While autophagy had previously been thought to be a non-selective process, it is now clear that it can also selectively target cellular organelles, such as mitochondria (referred to as mitophagy) and/or invading pathogens (referred to as xenophagy). Selective autophagy is characterized by specific substrate recognition and requires distinct cellular adaptor proteins. Here we review xenophagic mechanisms involved in the recognition and autolysosomal or autophagolysosomal degradation of different intracellular bacteria. In this context, we also discuss a recently discovered cellular self-defense pathway, termed mito-xenophagy, which occurs during bacterial infection of dendritic cells and depends on a TNF-α-mediated metabolic switch from oxidative phosphorylation to glycolysis.
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Affiliation(s)
- Nadine Radomski
- Institute of Immunology, Friedrich-Loeffler-Institut, Institute of Immunology, Federal Research Institute of Animal Health, D-17493 Greifswald, Isle of Riems, Germany
| | - Annica Rebbig
- Institute of Immunology, Friedrich-Loeffler-Institut, Institute of Immunology, Federal Research Institute of Animal Health, D-17493 Greifswald, Isle of Riems, Germany
| | - Ralf M Leonhardt
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Michael R Knittler
- Institute of Immunology, Friedrich-Loeffler-Institut, Institute of Immunology, Federal Research Institute of Animal Health, D-17493 Greifswald, Isle of Riems, Germany.
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43
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Castanheira S, García-Del Portillo F. Salmonella Populations inside Host Cells. Front Cell Infect Microbiol 2017; 7:432. [PMID: 29046870 PMCID: PMC5632677 DOI: 10.3389/fcimb.2017.00432] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 09/20/2017] [Indexed: 11/13/2022] Open
Abstract
Bacteria of the Salmonella genus cause diseases ranging from gastroenteritis to life-threatening typhoid fever and are among the most successful intracellular pathogens known. After the invasion of the eukaryotic cell, Salmonella exhibits contrasting lifestyles with different replication rates and subcellular locations. Although Salmonella hyper-replicates in the cytosol of certain host cell types, most invading bacteria remain within vacuoles in which the pathogen proliferates at moderate rates or persists in a dormant-like state. Remarkably, these cytosolic and intra-vacuolar intracellular lifestyles are not mutually exclusive and can co-exist in the same infected host cell. The mechanisms that direct the invading bacterium to follow the cytosolic or intra-vacuolar “pathway” remain poorly understood. In vitro studies show predominance of either the cytosolic or the intra-vacuolar population depending on the host cell type invaded by the pathogen. The host and pathogen factors controlling phagosomal membrane integrity and, as consequence, the egress into the cytosol, are intensively investigated. Other aspects of major interest are the host defenses that may affect differentially the cytosolic and intra-vacuolar populations and the strategies used by the pathogen to circumvent these attacks. Here, we summarize current knowledge about these Salmonella intracellular subpopulations and discuss how they emerge during the interaction of this pathogen with the eukaryotic cell.
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Affiliation(s)
- Sónia Castanheira
- Laboratory of Intracellular Bacterial Pathogens, Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Francisco García-Del Portillo
- Laboratory of Intracellular Bacterial Pathogens, Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
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44
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Kubori T, Bui XT, Hubber A, Nagai H. Legionella RavZ Plays a Role in Preventing Ubiquitin Recruitment to Bacteria-Containing Vacuoles. Front Cell Infect Microbiol 2017; 7:384. [PMID: 28971069 PMCID: PMC5609559 DOI: 10.3389/fcimb.2017.00384] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/14/2017] [Indexed: 01/10/2023] Open
Abstract
Bacterial pathogens like Salmonella and Legionella establish intracellular niches in host cells known as bacteria-containing vacuoles. In these vacuoles, bacteria can survive and replicate. Ubiquitin-dependent selective autophagy is a host defense mechanism to counteract infection by invading pathogens. The Legionella effector protein RavZ interferes with autophagy by irreversibly deconjugating LC3, an autophagy-related ubiquitin-like protein, from a phosphoglycolipid phosphatidylethanolamine. Using a co-infection system with Salmonella, we show here that Legionella RavZ interferes with ubiquitin recruitment to the Salmonella-containing vacuoles. The inhibitory activity is dependent on the same catalytic residue of RavZ that is involved in LC3 deconjugation. In semi-permeabilized cells infected with Salmonella, external addition of purified RavZ protein, but not of its catalytic mutant, induced removal of ubiquitin associated with Salmonella-containing vacuoles. The RavZ-mediated restriction of ubiquitin recruitment to Salmonella-containing vacuoles took place in the absence of the host system required for LC3 conjugation. These observations suggest the possibility that the targets of RavZ deconjugation activity include not only LC3, but also ubiquitin.
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Affiliation(s)
- Tomoko Kubori
- Department of Infectious Disease Control, Research Institute for Microbial Diseases, Osaka UniversitySuita, Japan.,Department of Microbiology, Graduate School of Medicine, Gifu UniversityGifu, Japan
| | - Xuan T Bui
- Department of Infectious Disease Control, Research Institute for Microbial Diseases, Osaka UniversitySuita, Japan
| | - Andree Hubber
- Department of Infectious Disease Control, Research Institute for Microbial Diseases, Osaka UniversitySuita, Japan
| | - Hiroki Nagai
- Department of Infectious Disease Control, Research Institute for Microbial Diseases, Osaka UniversitySuita, Japan.,Department of Microbiology, Graduate School of Medicine, Gifu UniversityGifu, Japan
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45
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Knuff K, Finlay BB. What the SIF Is Happening-The Role of Intracellular Salmonella-Induced Filaments. Front Cell Infect Microbiol 2017; 7:335. [PMID: 28791257 PMCID: PMC5524675 DOI: 10.3389/fcimb.2017.00335] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/10/2017] [Indexed: 11/29/2022] Open
Abstract
A common strategy among intracellular bacterial pathogens is to enter into a vacuolar environment upon host cell invasion. One such pathogen, Salmonella enterica, resides within the Salmonella-containing vacuole (SCV) inside epithelial cells and macrophages. Salmonella hijacks the host endosomal system to establish this unique intracellular replicative niche, forming a highly complex and dynamic network of Salmonella-induced filaments (SIFs). SIFs radiate outwards from the SCV upon onset of bacterial replication. SIF biogenesis is dependent on the activity of bacterial effector proteins secreted by the Salmonella-pathogenicity island-2 (SPI-2) encoded type III secretion system. While the presence of SIFs has been known for almost 25 years, their precise role during infection remains elusive. This review summarizes our current knowledge of SCV maturation and SIF biogenesis, and recent advances in our understanding of the role of SIFs inside cells.
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Affiliation(s)
- Katelyn Knuff
- Michael Smith Laboratories, University of British ColumbiaVancouver, BC, Canada.,Department of Microbiology and Immunology, University of British ColumbiaVancouver, BC, Canada
| | - B Brett Finlay
- Michael Smith Laboratories, University of British ColumbiaVancouver, BC, Canada.,Department of Microbiology and Immunology, University of British ColumbiaVancouver, BC, Canada.,Department of Biochemistry and Molecular Biology, University of British ColumbiaVancouver, BC, Canada
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46
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Ganesan R, Hos NJ, Gutierrez S, Fischer J, Stepek JM, Daglidu E, Krönke M, Robinson N. Salmonella Typhimurium disrupts Sirt1/AMPK checkpoint control of mTOR to impair autophagy. PLoS Pathog 2017; 13:e1006227. [PMID: 28192515 PMCID: PMC5325604 DOI: 10.1371/journal.ppat.1006227] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 02/24/2017] [Accepted: 02/08/2017] [Indexed: 01/25/2023] Open
Abstract
During intracellular infections, autophagy significantly contributes to the elimination of pathogens, regulation of pro-inflammatory signaling, secretion of immune mediators and in coordinating the adaptive immune system. Intracellular pathogens such as S. Typhimurium have evolved mechanisms to circumvent autophagy. However, the regulatory mechanisms targeted by S. Typhimurium to modulate autophagy have not been fully resolved. Here we report that cytosolic energy loss during S. Typhimurium infection triggers transient activation of AMPK, an important checkpoint of mTOR activity and autophagy. The activation of AMPK is regulated by LKB1 in a cytosolic complex containing Sirt1 and LKB1, where Sirt1 is required for deacetylation and subsequent activation of LKB1. S. Typhimurium infection targets Sirt1, LKB1 and AMPK to lysosomes for rapid degradation resulting in the disruption of the AMPK-mediated regulation of mTOR and autophagy. The degradation of cytosolic Sirt1/LKB1/AMPK complex was not observed with two mutant strains of S. Typhimurium, ΔssrB and ΔssaV, both compromising the pathogenicity island 2 (SPI2). The results highlight virulence factor-dependent degradation of host cell proteins as a previously unrecognized strategy of S. Typhimurium to evade autophagy. S. Typhimurium is a facultative intracellular pathogen which uses its type III secretion system to avoid cell-autonomous defense mechanisms such as autophagy. Here we show that S. Typhimurium induces energy depletion resulting in an early but transient activation of AMPK and autophagy. Salmonella virulence factors target Sirt1/LKB1/AMPK for lysosomal degradation, which enables sustained mTOR-activation and inhibition of autophagy. Activation of mTOR establishes a molecular feedback loop that enhances lysosomal degradation of Sirt1/LKB1/AMPK.
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Affiliation(s)
- Raja Ganesan
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Nina Judith Hos
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- German Center for Infection Research (DZIF), Cologne, Germany
| | - Saray Gutierrez
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Julia Fischer
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- First Department of Internal Medicine, University of Cologne, Cologne, Germany
| | - Joanna Magdalena Stepek
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Evmorphia Daglidu
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Martin Krönke
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- German Center for Infection Research (DZIF), Cologne, Germany
| | - Nirmal Robinson
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Cologne, Germany
- Cologne Cluster of Excellence in Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- * E-mail:
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47
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Singh V, Finke-Isami J, Hopper-Chidlaw AC, Schwerk P, Thompson A, Tedin K. Salmonella Co-opts Host Cell Chaperone-mediated Autophagy for Intracellular Growth. J Biol Chem 2017; 292:1847-1864. [PMID: 27932462 PMCID: PMC5290957 DOI: 10.1074/jbc.m116.759456] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Revised: 12/01/2016] [Indexed: 01/05/2023] Open
Abstract
Salmonella enterica are invasive intracellular pathogens that replicate within a membrane-bound compartment inside infected host cells known as the Salmonella-containing vacuole. How Salmonella obtains nutrients for growth within this intracellular niche despite the apparent isolation is currently not known. Recent studies have indicated the importance of glucose and related carbon sources for tissue colonization and intracellular proliferation within host cells during Salmonella infections, although none have been found to be essential. We found that wild-type Salmonella are capable of replicating within infected host cells in the absence of both exogenous sugars and/or amino acids. Furthermore, mutants defective in glucose uptake or dependent upon peptides for growth also showed no significant loss in intracellular replication, suggesting host-derived peptides can supply both carbon units and amino acids. Here, we show that intracellular Salmonella recruit the host proteins LAMP-2A and Hsc73, key components of the host protein turnover pathway known as chaperone-mediated autophagy involved in transport of cytosolic proteins to the lysosome for degradation. Host-derived peptides are shown to provide a significant contribution toward the intracellular growth of Salmonella The results reveal a means whereby intracellular Salmonella gain access to the host cell cytosol from within its membrane-bound compartment to acquire nutrients. Furthermore, this study provides an explanation as to how Salmonella evades activation of autophagy mechanisms as part of the innate immune response.
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Affiliation(s)
- Vikash Singh
- From the Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany
| | - Johannes Finke-Isami
- From the Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany
| | | | - Peter Schwerk
- From the Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany
| | - Arthur Thompson
- the Institute of Food Research, Norwich Research Park, Norwich NR4 7UA, United Kingdom
| | - Karsten Tedin
- From the Centre for Infection Medicine, Institute of Microbiology and Epizootics, Freie Universität Berlin, 14163 Berlin, Germany.
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48
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Klein JA, Powers TR, Knodler LA. Measurement of Salmonella enterica Internalization and Vacuole Lysis in Epithelial Cells. Methods Mol Biol 2017; 1519:285-296. [PMID: 27815887 DOI: 10.1007/978-1-4939-6581-6_19] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Establishment of an intracellular niche within mammalian cells is key to the pathogenesis of the gastrointestinal bacterium, Salmonella enterica serovar Typhimurium (S. Typhimurium). Here we will describe how to study the internalization of S. Typhimurium into human epithelial cells using the gentamicin protection assay. The assay takes advantage of the relatively poor penetration of gentamicin into mammalian cells; internalized bacteria are effectively protected from its antibacterial actions. A second assay, the chloroquine (CHQ) resistance assay, can be used to determine the proportion of internalized bacteria that have lysed or damaged their Salmonella-containing vacuole and are therefore residing within the cytosol. Its application to the quantification of cytosolic S. Typhimurium in epithelial cells will also be presented. Together, these protocols provide an inexpensive, rapid and sensitive quantitative measure of bacterial internalization and vacuole lysis by S. Typhimurium.
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Affiliation(s)
- Jessica A Klein
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, 647090, Pullman, WA, 99164-7090, USA
| | - TuShun R Powers
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, 647090, Pullman, WA, 99164-7090, USA
| | - Leigh A Knodler
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, 647090, Pullman, WA, 99164-7090, USA.
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49
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Scheidel J, Amstein L, Ackermann J, Dikic I, Koch I. In Silico Knockout Studies of Xenophagic Capturing of Salmonella. PLoS Comput Biol 2016; 12:e1005200. [PMID: 27906974 PMCID: PMC5131900 DOI: 10.1371/journal.pcbi.1005200] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 10/16/2016] [Indexed: 11/19/2022] Open
Abstract
The degradation of cytosol-invading pathogens by autophagy, a process known as xenophagy, is an important mechanism of the innate immune system. Inside the host, Salmonella Typhimurium invades epithelial cells and resides within a specialized intracellular compartment, the Salmonella-containing vacuole. A fraction of these bacteria does not persist inside the vacuole and enters the host cytosol. Salmonella Typhimurium that invades the host cytosol becomes a target of the autophagy machinery for degradation. The xenophagy pathway has recently been discovered, and the exact molecular processes are not entirely characterized. Complete kinetic data for each molecular process is not available, so far. We developed a mathematical model of the xenophagy pathway to investigate this key defense mechanism. In this paper, we present a Petri net model of Salmonella xenophagy in epithelial cells. The model is based on functional information derived from literature data. It comprises the molecular mechanism of galectin-8-dependent and ubiquitin-dependent autophagy, including regulatory processes, like nutrient-dependent regulation of autophagy and TBK1-dependent activation of the autophagy receptor, OPTN. To model the activation of TBK1, we proposed a new mechanism of TBK1 activation, suggesting a spatial and temporal regulation of this process. Using standard Petri net analysis techniques, we found basic functional modules, which describe different pathways of the autophagic capture of Salmonella and reflect the basic dynamics of the system. To verify the model, we performed in silico knockout experiments. We introduced a new concept of knockout analysis to systematically compute and visualize the results, using an in silico knockout matrix. The results of the in silico knockout analyses were consistent with published experimental results and provide a basis for future investigations of the Salmonella xenophagy pathway.
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Affiliation(s)
- Jennifer Scheidel
- Molecular Bioinformatics, Institute of Computer Science, Johann Wolfgang Goethe-University Frankfurt am Main, Frankfurt am Main, Germany
| | - Leonie Amstein
- Molecular Bioinformatics, Institute of Computer Science, Johann Wolfgang Goethe-University Frankfurt am Main, Frankfurt am Main, Germany
| | - Jörg Ackermann
- Molecular Bioinformatics, Institute of Computer Science, Johann Wolfgang Goethe-University Frankfurt am Main, Frankfurt am Main, Germany
| | - Ivan Dikic
- Institute of Biochemistry II, Johann Wolfgang Goethe-University Hospital Frankfurt am Main, Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences, Frankfurt am Main, Germany
| | - Ina Koch
- Molecular Bioinformatics, Institute of Computer Science, Johann Wolfgang Goethe-University Frankfurt am Main, Frankfurt am Main, Germany
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50
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Thornbrough JM, Gopinath A, Hundley T, Worley MJ. Human Genome-Wide RNAi Screen for Host Factors That Facilitate Salmonella Invasion Reveals a Role for Potassium Secretion in Promoting Internalization. PLoS One 2016; 11:e0166916. [PMID: 27880807 PMCID: PMC5120809 DOI: 10.1371/journal.pone.0166916] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/07/2016] [Indexed: 02/06/2023] Open
Abstract
Salmonella enterica can actively invade the gastro-intestinal epithelium. This frequently leads to diarrheal disease, and also gives the pathogen access to phagocytes that can serve as vehicles for dissemination into deeper tissue. The ability to invade host cells is also important in maintaining the carrier state. While much is known about the bacterial factors that promote invasion, relatively little is known about the host factors involved. To gain insight into how Salmonella enterica serovar Typhimurium is able to invade normally non-phagocytic cells, we undertook a global RNAi screen with S. Typhimurium-infected human epithelial cells. In all, we identified 633 genes as contributing to bacterial internalization. These genes fall into a diverse group of functional categories revealing that cytoskeletal regulators are not the only factors that modulate invasion. In fact, potassium ion transport was the most enriched molecular function category in our screen, reinforcing a link between potassium and internalization. In addition to providing new insights into the molecular mechanisms underlying the ability of pathogens to invade host cells, all 633 host factors identified are candidates for new anti-microbial targets for treating Salmonella infections, and may be useful in curtailing infections with other pathogens as well.
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Affiliation(s)
- Joshua M. Thornbrough
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Adarsh Gopinath
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Tom Hundley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Micah J. Worley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, 40202, United States of America
- * E-mail:
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