1
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Ernst C, Andreassen PR, Giger GH, Nguyen BD, Gäbelein CG, Guillaume-Gentil O, Fattinger SA, Sellin ME, Hardt WD, Vorholt JA. Direct Salmonella injection into enteroid cells allows the study of host-pathogen interactions in the cytosol with high spatiotemporal resolution. PLoS Biol 2024; 22:e3002597. [PMID: 38684033 PMCID: PMC11057982 DOI: 10.1371/journal.pbio.3002597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 03/21/2024] [Indexed: 05/02/2024] Open
Abstract
Intestinal epithelial cells (IECs) play pivotal roles in nutrient uptake and in the protection against gut microorganisms. However, certain enteric pathogens, such as Salmonella enterica serovar Typhimurium (S. Tm), can invade IECs by employing flagella and type III secretion systems (T3SSs) with cognate effector proteins and exploit IECs as a replicative niche. Detection of flagella or T3SS proteins by IECs results in rapid host cell responses, i.e., the activation of inflammasomes. Here, we introduce a single-cell manipulation technology based on fluidic force microscopy (FluidFM) that enables direct bacteria delivery into the cytosol of single IECs within a murine enteroid monolayer. This approach allows to specifically study pathogen-host cell interactions in the cytosol uncoupled from preceding events such as docking, initiation of uptake, or vacuole escape. Consistent with current understanding, we show using a live-cell inflammasome reporter that exposure of the IEC cytosol to S. Tm induces NAIP/NLRC4 inflammasomes via its known ligands flagellin and T3SS rod and needle. Injected S. Tm mutants devoid of these invasion-relevant ligands were able to grow in the cytosol of IECs despite the absence of T3SS functions, suggesting that, in the absence of NAIP/NLRC4 inflammasome activation and the ensuing cell death, no effector-mediated host cell manipulation is required to render the epithelial cytosol growth-permissive for S. Tm. Overall, the experimental system to introduce S. Tm into single enteroid cells enables investigations into the molecular basis governing host-pathogen interactions in the cytosol with high spatiotemporal resolution.
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Affiliation(s)
- Chantal Ernst
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | | | - Gabriel H. Giger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Bidong D. Nguyen
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | | | | | - Stefan A. Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Mikael E. Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Julia A. Vorholt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland
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2
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Dombach JL, Christensen GL, Allgood SC, Quintana JLJ, Detweiler CS. Inhibition of multiple staphylococcal growth states by a small molecule that disrupts membrane fluidity and voltage. mSphere 2024; 9:e0077223. [PMID: 38445864 PMCID: PMC10964410 DOI: 10.1128/msphere.00772-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 01/26/2024] [Indexed: 03/07/2024] Open
Abstract
New molecular approaches to disrupting bacterial infections are needed. The bacterial cell membrane is an essential structure with diverse potential lipid and protein targets for antimicrobials. While rapid lysis of the bacterial cell membrane kills bacteria, lytic compounds are generally toxic to whole animals. In contrast, compounds that subtly damage the bacterial cell membrane could disable a microbe, facilitating pathogen clearance by the immune system with limited compound toxicity. A previously described small molecule, D66, terminates Salmonella enterica serotype Typhimurium (S. Typhimurium) infection of macrophages and reduces tissue colonization in mice. The compound dissipates bacterial inner membrane voltage without rapid cell lysis under broth conditions that permeabilize the outer membrane or disable efflux pumps. In standard media, the cell envelope protects Gram-negative bacteria from D66. We evaluated the activity of D66 in Gram-positive bacteria because their distinct envelope structure, specifically the absence of an outer membrane, could facilitate mechanism of action studies. We observed that D66 inhibited Gram-positive bacterial cell growth, rapidly increased Staphylococcus aureus membrane fluidity, and disrupted membrane voltage while barrier function remained intact. The compound also prevented planktonic staphylococcus from forming biofilms and a disturbed three-dimensional structure in 1-day-old biofilms. D66 furthermore reduced the survival of staphylococcal persister cells and of intracellular S. aureus. These data indicate that staphylococcal cells in multiple growth states germane to infection are susceptible to changes in lipid packing and membrane conductivity. Thus, agents that subtly damage bacterial cell membranes could have utility in preventing or treating disease.IMPORTANCEAn underutilized potential antibacterial target is the cell membrane, which supports or associates with approximately half of bacterial proteins and has a phospholipid makeup distinct from mammalian cell membranes. Previously, an experimental small molecule, D66, was shown to subtly damage Gram-negative bacterial cell membranes and to disrupt infection of mammalian cells. Here, we show that D66 increases the fluidity of Gram-positive bacterial cell membranes, dissipates membrane voltage, and inhibits the human pathogen Staphylococcus aureus in several infection-relevant growth states. Thus, compounds that cause membrane damage without lysing cells could be useful for mitigating infections caused by S. aureus.
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Affiliation(s)
- Jamie L. Dombach
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Grace L. Christensen
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Samual C. Allgood
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Joaquin L. J. Quintana
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Corrella S. Detweiler
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
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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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Saldaña-Ahuactzi Z, Knodler LA. FoxR is an AraC-like transcriptional regulator of ferrioxamine uptake in Salmonella enterica. Mol Microbiol 2022; 118:369-386. [PMID: 35970762 DOI: 10.1111/mmi.14970] [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: 03/23/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 01/07/2023]
Abstract
Salmonella enterica spp. produce siderophores to bind iron with high affinity and can also use three xenosiderophores secreted by other microorganisms, ferrichrome, coprogen, and ferrioxamine. Here we focused on FoxA, a TonB-dependent transporter of ferrioxamines. Adjacent to foxA is a gene annotated as a helix-turn-helix (HTH) domain-containing protein, SL0358 (foxR), in the Salmonella enterica serovar Typhimurium SL1344 genome. FoxR shares homology with transcriptional regulators belonging to the AraC/XylS family. foxR is syntenic with foxA in the Enterobacteriaceae family, suggesting their functional relatedness. Both foxA and foxR are repressed by the ferric uptake regulator (Fur) under iron-rich growth conditions. When iron is scarce, FoxR acts as a transcriptional activator of foxA by directly binding to its upstream regulatory region. A point mutation in the HTH domain of FoxR abolished this binding, as did mutation of a direct repeat motif in the foxA upstream regulatory region. Desferrioxamine (DFOE) enhanced FoxR protein stability and foxA transcription but did not affect the affinity of FoxR binding to the foxA regulatory region. In summary, we have identified FoxR as a new member of the AraC/XylS family that regulates xenosiderophore-mediated iron uptake by S. Typhimurium and likely other Enterobacteriaceae members.
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Affiliation(s)
- Zeus Saldaña-Ahuactzi
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Leigh A Knodler
- Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
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5
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Lisowski C, Dias J, Costa S, Silva RJ, Mano M, Eulalio A. Dysregulated endolysosomal trafficking in cells arrested in the G 1 phase of the host cell cycle impairs Salmonella vacuolar replication. Autophagy 2021; 18:1785-1800. [PMID: 34781820 DOI: 10.1080/15548627.2021.1999561] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Modulation of the host cell cycle has emerged as a common theme among the pathways regulated by bacterial pathogens, arguably to promote host cell colonization. However, in most cases the exact benefit ensuing from such interference to the infection process remains unclear. Previously, we have shown that Salmonella actively induces G2/M arrest of host cells, and that infection is severely inhibited in cells arrested in G1. In this study, we demonstrate that Salmonella vacuolar replication is inhibited in host cells blocked in G1, whereas the cytosolic replication of the closely related pathogen Shigella is not affected. Mechanistically, we show that cells arrested in G1, but not cells arrested in G2, present dysregulated endolysosomal trafficking, displaying an abnormal accumulation of vesicles positive for late endosomal and lysosomal markers. In addition, the macroautophagic/autophagic flux and degradative lysosomal function are strongly impaired. This endolysosomal trafficking dysregulation results in sustained activation of the SPI-1 type III secretion system and lack of vacuole repair by the autophagy pathway, ultimately compromising the maturation and integrity of the Salmonella-containing vacuole. As such, Salmonella is released in the host cytosol. Collectively, our findings demonstrate that the modulation of the host cell cycle occurring during Salmonella infection is related to a disparity in the permissivity of cells arrested in G1 and G2/M, due to their intrinsic characteristics.
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Affiliation(s)
- Clivia Lisowski
- Host RNA Metabolism Group, Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
| | - Jane Dias
- RNA & Infection Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,Functional Genomics and RNA-based Therapeutics Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,PhD Programme in Experimental Biology and Biomedicine (PDBEB), Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Coimbra, Portugal
| | - Susana Costa
- RNA & Infection Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,Functional Genomics and RNA-based Therapeutics Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,PhD Programme in Experimental Biology and Biomedicine (PDBEB), Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Coimbra, Portugal
| | - Ricardo Jorge Silva
- Functional Genomics and RNA-based Therapeutics Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,PhD Programme in Experimental Biology and Biomedicine (PDBEB), Institute for Interdisciplinary Research (IIIUC), University of Coimbra, Coimbra, Portugal
| | - Miguel Mano
- Functional Genomics and RNA-based Therapeutics Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Ana Eulalio
- Host RNA Metabolism Group, Institute for Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany.,RNA & Infection Laboratory, Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, University of Coimbra, Coimbra, Portugal
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6
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Fattinger SA, Sellin ME, Hardt WD. Salmonella effector driven invasion of the gut epithelium: breaking in and setting the house on fire. Curr Opin Microbiol 2021; 64:9-18. [PMID: 34492596 DOI: 10.1016/j.mib.2021.08.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/10/2021] [Accepted: 08/17/2021] [Indexed: 12/15/2022]
Abstract
Salmonella Typhimurium (S.Tm) is a major cause of diarrheal disease. The invasion into intestinal epithelial cells (IECs) is a central step in the infection cycle. It is associated with gut inflammation and thought to benefit S.Tm proliferation also in the intestinal lumen. Importantly, it is still not entirely clear how inflammation is elicited and to which extent it links to IEC invasion efficiency in vivo. In this review, we summarize recent findings explaining IEC invasion by type-three-secretion-system-1 (TTSS-1) effector proteins and discuss their effects on invasion and gut inflammation. In non-polarized tissue culture cells, the TTSS-1 effectors (mainly SopB/E/E2) elicit large membrane ruffles fueling cooperative invasion, and can directly trigger pro-inflammatory signaling. By contrast, in the murine gut, we observe discreet-invasion (mainly via the TTSS-1 effector SipA) and a prominent pro-inflammatory role of the host?"s epithelial inflammasome(s), which sense pathogen associated molecular patterns (PAMPs). We discuss why it has remained a major challenge to tease apart direct and indirect inflammatory effects of TTSS-1 effectors and explain why further research will be needed to fully determine their inflammation-modulating role(s).
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Affiliation(s)
- Stefan A Fattinger
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland; Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Mikael E Sellin
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zurich, Zurich, Switzerland.
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7
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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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8
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Bianchi F, van den Bogaart G. Vacuolar escape of foodborne bacterial pathogens. J Cell Sci 2020; 134:134/5/jcs247221. [PMID: 32873733 DOI: 10.1242/jcs.247221] [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: 01/12/2023] Open
Abstract
The intracellular pathogens Listeria monocytogenes, Salmonella enterica, Shigella spp. and Staphylococcus aureus are major causes of foodborne illnesses. Following the ingestion of contaminated food or beverages, pathogens can invade epithelial cells, immune cells and other cell types. Pathogens survive and proliferate intracellularly via two main strategies. First, the pathogens can remain in membrane-bound vacuoles and tailor organellar trafficking to evade host-cell defenses and gain access to nutrients. Second, pathogens can rupture the vacuolar membrane and proliferate within the nutrient-rich cytosol of the host cell. Although this virulence strategy of vacuolar escape is well known for L. monocytogenes and Shigella spp., it has recently become clear that S. aureus and Salmonella spp. also gain access to the cytosol, and that this is important for their survival and growth. In this Review, we discuss the molecular mechanisms of how these intracellular pathogens rupture the vacuolar membrane by secreting a combination of proteins that lyse the membranes or that remodel the lipids of the vacuolar membrane, such as phospholipases. In addition, we also propose that oxidation of the vacuolar membrane also contributes to cytosolic pathogen escape. Understanding these escape mechanisms could aid in the identification of new therapeutic approaches to combat foodborne pathogens.
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Affiliation(s)
- Frans Bianchi
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9722GR Groningen, The Netherlands
| | - Geert van den Bogaart
- Department of Molecular Immunology and Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9722GR Groningen, The Netherlands .,Department of Tumor Immunology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, 9625GA Nijmegen, The Netherlands
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9
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Fattinger SA, Böck D, Di Martino ML, Deuring S, Samperio Ventayol P, Ek V, Furter M, Kreibich S, Bosia F, Müller-Hauser AA, Nguyen BD, Rohde M, Pilhofer M, Hardt WD, Sellin ME. Salmonella Typhimurium discreet-invasion of the murine gut absorptive epithelium. PLoS Pathog 2020; 16:e1008503. [PMID: 32365138 PMCID: PMC7224572 DOI: 10.1371/journal.ppat.1008503] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 05/14/2020] [Accepted: 03/26/2020] [Indexed: 01/15/2023] Open
Abstract
Salmonella enterica serovar Typhimurium (S.Tm) infections of cultured cell lines have given rise to the ruffle model for epithelial cell invasion. According to this model, the Type-Three-Secretion-System-1 (TTSS-1) effectors SopB, SopE and SopE2 drive an explosive actin nucleation cascade, resulting in large lamellipodia- and filopodia-containing ruffles and cooperative S.Tm uptake. However, cell line experiments poorly recapitulate many of the cell and tissue features encountered in the host’s gut mucosa. Here, we employed bacterial genetics and multiple imaging modalities to compare S.Tm invasion of cultured epithelial cell lines and the gut absorptive epithelium in vivo in mice. In contrast to the prevailing ruffle-model, we find that absorptive epithelial cell entry in the mouse gut occurs through “discreet-invasion”. This distinct entry mode requires the conserved TTSS-1 effector SipA, involves modest elongation of local microvilli in the absence of expansive ruffles, and does not favor cooperative invasion. Discreet-invasion preferentially targets apicolateral hot spots at cell–cell junctions and shows strong dependence on local cell neighborhood. This proof-of-principle evidence challenges the current model for how S.Tm can enter gut absorptive epithelial cells in their intact in vivo context. Bacterial pathogens can use secreted effector molecules to drive entry into host cells. Studies of the intestinal pathogen S.Tm have been central to uncover the mechanistic basis for the entry process. More than two decades of research have resulted in a detailed model for how S.Tm invades gut epithelial cells through effector triggering of large Rho-GTPase-dependent actin ruffles. However, the evidence for this model comes predominantly from studies in cultured cell lines. These experimental systems lack many of the architectural and signaling features of the intact gut epithelium. Our study surprisingly reveals that in the intact mouse gut, S.Tm invades absorptive epithelial cells through a process that does not require the Rho-GTPase-activating effectors and can proceed in the absence of the prototypical ruffling response. Instead, S.Tm exploits another effector, SipA, to sneak in through discreet entry structures close to cell–cell junctions. Our results challenge the current model for S.Tm epithelial cell entry and emphasizes the need of taking a physiological host cell context into account when studying bacterium–host cell interactions.
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Affiliation(s)
- Stefan A. Fattinger
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Desirée Böck
- Institute of Molecular Biology & Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Maria Letizia Di Martino
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Sabrina Deuring
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Pilar Samperio Ventayol
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Viktor Ek
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Markus Furter
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Saskia Kreibich
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Francesco Bosia
- Institute of Molecular Biology & Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | | | - Bidong D. Nguyen
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Manfred Rohde
- Central Facility for Microscopy, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Martin Pilhofer
- Institute of Molecular Biology & Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
- * E-mail: (MP); (WDH); (MES)
| | - Wolf-Dietrich Hardt
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
- * E-mail: (MP); (WDH); (MES)
| | - Mikael E. Sellin
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
- Science for Life Laboratory, Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail: (MP); (WDH); (MES)
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10
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Wang M, Qazi IH, Wang L, Zhou G, Han H. Salmonella Virulence and Immune Escape. Microorganisms 2020; 8:microorganisms8030407. [PMID: 32183199 PMCID: PMC7143636 DOI: 10.3390/microorganisms8030407] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/02/2020] [Accepted: 03/10/2020] [Indexed: 02/07/2023] Open
Abstract
Salmonella genus represents the most common foodborne pathogens causing morbidity, mortality, and burden of disease in all regions of the world. The introduction of antimicrobial agents and Salmonella-specific phages has been considered as an effective intervention strategy to reduce Salmonella contamination. However, data from the United States, European countries, and low- and middle-income countries indicate that Salmonella cases are still a commonly encountered cause of bacterial foodborne diseases globally. The control programs have not been successful and even led to the emergence of some multidrug-resistant Salmonella strains. It is known that the host immune system is able to effectively prevent microbial invasion and eliminate microorganisms. However, Salmonella has evolved mechanisms of resisting host physical barriers and inhibiting subsequent activation of immune response through their virulence factors. There has been a high interest in understanding how Salmonella interacts with the host. Therefore, in the present review, we characterize the functions of Salmonella virulence genes and particularly focus on the mechanisms of immune escape in light of evidence from the emerging mainstream literature.
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Affiliation(s)
- Mengyao Wang
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Izhar Hyder Qazi
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China;
- Department of Veterinary Anatomy and Histology, Shaheed Benazir Bhutto University of Veterinary and Animal Sciences, Sakrand 67210, Pakistan
| | - Linli Wang
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
| | - Guangbin Zhou
- Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu 611130, China;
- Correspondence: (H.H.); (G.Z.)
| | - Hongbing Han
- Beijing Key Laboratory for Animal Genetic Improvement, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.W.); (L.W.)
- Key Laboratory of Animal Genetics and Breeding of the Ministry of Agriculture, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China
- Correspondence: (H.H.); (G.Z.)
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11
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Röder J, Hensel M. Presence of SopE and mode of infection result in increased
Salmonella
‐containing vacuole damage and cytosolic release during host cell infection by
Salmonella enterica. Cell Microbiol 2020; 22:e13155. [DOI: 10.1111/cmi.13155] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 12/15/2019] [Accepted: 12/16/2019] [Indexed: 12/21/2022]
Affiliation(s)
- Jennifer Röder
- Abteilung MikrobiologieUniversitat Osnabruck Osnabrück Germany
| | - Michael Hensel
- Abteilung MikrobiologieUniversitat Osnabruck Osnabrück Germany
- CellNanOs – Center for Cellular Nanoanalytics, Fachbereich Biologie/ChemieUniversität Osnabrück Osnabrück Germany
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12
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Chong A, Starr T, Finn CE, Steele-Mortimer O. A role for the Salmonella Type III Secretion System 1 in bacterial adaptation to the cytosol of epithelial cells. Mol Microbiol 2019; 112:1270-1283. [PMID: 31370104 DOI: 10.1111/mmi.14361] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2019] [Indexed: 12/15/2022]
Abstract
Salmonella enterica serovar Typhimurium is a facultative intracellular pathogen that invades the intestinal epithelium. Following invasion of epithelial cells, Salmonella survives and replicates within two distinct intracellular niches. While all of the bacteria are initially taken up into a membrane bound vacuole, the Salmonella-containing vacuole or SCV, a significant proportion of them promptly escape into the cytosol. Cytosolic Salmonella replicates more rapidly compared to the vacuolar population, although the reasons for this are not well understood. SipA, a multi-function effector protein, has been shown to affect intracellular replication and is secreted by cytosolic Salmonella via the invasion-associated Type III Secretion System 1 (T3SS1). Here, we have used a multipronged microscopy approach to show that SipA does not affect bacterial replication rates per se, but rather mediates intra-cytosolic survival and/or initiation of replication following bacterial egress from the SCV. Altogether, our findings reveal an important role for SipA in the early survival of cytosolic Salmonella.
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Affiliation(s)
- Audrey Chong
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Tregei Starr
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Ciaran E Finn
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Olivia Steele-Mortimer
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
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13
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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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14
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Steele SP, Chamberlain Z, Park J, Kawula TH. Francisella tularensis enters a double membraned compartment following cell-cell transfer. eLife 2019; 8:e45252. [PMID: 31017571 PMCID: PMC6499538 DOI: 10.7554/elife.45252] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 04/18/2019] [Indexed: 12/26/2022] Open
Abstract
Previously, we found that phagocytic cells ingest bacteria directly from the cytosol of infected cells without killing the initially infected cell (Steele et al., 2016). Here, we explored the events immediately following bacterial transfer. Francisella tularensis bacteria acquired from infected cells were found within double-membrane vesicles partially composed from the donor cell plasma membrane. As with phagosomal escape, the F. tularensis Type VI Secretion System (T6SS) was required for vacuole escape. We constructed a T6SS inducible strain and established conditions where this strain is trapped in vacuoles of cells infected through bacterial transfer. Using this strain we identified bacterial transfer events in the lungs of infected mice, demonstrating that this process occurs in infected animals. These data and electron microscopy analysis of the transfer event revealed that macrophages acquire cytoplasm and membrane components of other cells through a process that is distinct from, but related to phagocytosis.
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Affiliation(s)
- Shaun P Steele
- School of Global Animal HealthWashington State UniversityPullmanUnited States
| | - Zach Chamberlain
- School of Global Animal HealthWashington State UniversityPullmanUnited States
| | - Jason Park
- School of Global Animal HealthWashington State UniversityPullmanUnited States
| | - Thomas H Kawula
- School of Global Animal HealthWashington State UniversityPullmanUnited States
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Martinez E, Siadous FA, Bonazzi M. Tiny architects: biogenesis of intracellular replicative niches by bacterial pathogens. FEMS Microbiol Rev 2018; 42:425-447. [PMID: 29596635 DOI: 10.1093/femsre/fuy013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/26/2018] [Indexed: 11/13/2022] Open
Abstract
Co-evolution of bacterial pathogens with their hosts led to the emergence of a stunning variety of strategies aiming at the evasion of host defences, colonisation of host cells and tissues and, ultimately, the establishment of a successful infection. Pathogenic bacteria are typically classified as extracellular and intracellular; however, intracellular lifestyle comes in many different flavours: some microbes rapidly escape to the cytosol whereas other microbes remain within vacuolar compartments and harness membrane trafficking pathways to generate their host-derived, pathogen-specific replicative niche. Here we review the current knowledge on a variety of vacuolar lifestyles, the effector proteins used by bacteria as tools to take control of the host cell and the main membrane trafficking signalling pathways targeted by vacuolar pathogens as source of membranes and nutrients. Finally, we will also discuss how host cells have developed countermeasures to sense the biogenesis of the aberrant organelles harbouring bacteria. Understanding the dialogue between bacterial and eukaryotic proteins is the key to unravel the molecular mechanisms of infection and in turn, this may lead to the identification of new targets for the development of new antimicrobials.
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Affiliation(s)
- Eric Martinez
- IRIM, University of Montpellier, CNRS, 34293 Montpellier, France
| | | | - Matteo Bonazzi
- IRIM, University of Montpellier, CNRS, 34293 Montpellier, France
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