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Hamblin M, Schade R, Narasimhan R, Monack DM. Salmonella enterica serovar Typhi uses two type 3 secretion systems to replicate in human macrophages and colonize humanized mice. mBio 2023; 14:e0113723. [PMID: 37341487 PMCID: PMC10470537 DOI: 10.1128/mbio.01137-23] [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: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 06/22/2023] Open
Abstract
Salmonella enterica serovar Typhi (S. Typhi) is a human-restricted pathogen that replicates in macrophages. In this study, we investigated the roles of the S. Typhi type 3 secretion systems (T3SSs) encoded on Salmonella pathogenicity islands (SPI)-1 (T3SS-1) and SPI-2 (T3SS-2) during human macrophage infection. We found that mutants of S. Typhi deficient for both T3SSs were defective for intramacrophage replication as measured by flow cytometry, viable bacterial counts, and live time-lapse microscopy. T3SS-secreted proteins PipB2 and SifA contributed to S. Typhi replication and were translocated into the cytosol of human macrophages through both T3SS-1 and T3SS-2, demonstrating functional redundancy for these secretion systems. Importantly, an S. Typhi mutant strain that is deficient for both T3SS-1 and T3SS-2 was severely attenuated in the ability to colonize systemic tissues in a humanized mouse model of typhoid fever. Overall, this study establishes a critical role for S. Typhi T3SSs during its replication within human macrophages and during systemic infection of humanized mice. IMPORTANCE Salmonella enterica serovar Typhi is a human-restricted pathogen that causes typhoid fever. Understanding the key virulence mechanisms that facilitate S. Typhi replication in human phagocytes will enable rational vaccine and antibiotic development to limit the spread of this pathogen. While S. Typhimurium replication in murine models has been studied extensively, there is limited information available about S. Typhi replication in human macrophages, some of which directly conflict with findings from S. Typhimurium murine models. This study establishes that both of S. Typhi's two type 3 secretion systems (T3SS-1 and T3SS-2) contribute to intramacrophage replication and virulence.
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Affiliation(s)
- Meagan Hamblin
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Ruth Schade
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Ramya Narasimhan
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
| | - Denise M. Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, USA
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Hamblin M, Schade R, Narasimhan R, Monack DM. Salmonella enterica serovar Typhi uses two type 3 secretion systems to replicate in human macrophages and to colonize humanized mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.06.543980. [PMID: 37333307 PMCID: PMC10274799 DOI: 10.1101/2023.06.06.543980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Salmonella enterica serovar Typhi ( S. Typhi) is a human-restricted pathogen that replicates in macrophages. In this study, we investigated the roles of the S. Typhi Type 3 secretion systems (T3SSs) encoded on Salmonella Pathogenicity Islands (SPI) -1 (T3SS-1) and -2 (T3SS-2) during human macrophage infection. We found that mutants of S . Typhi deficient for both T3SSs were defective for intramacrophage replication as measured by flow cytometry, viable bacterial counts, and live time-lapse microscopy. T3SS-secreted proteins PipB2 and SifA contributed to S. Typhi replication and were translocated into the cytosol of human macrophages through both T3SS-1 and -2, demonstrating functional redundancy for these secretion systems. Importantly, an S . Typhi mutant strain that is deficient for both T3SS-1 and -2 was severely attenuated in the ability to colonize systemic tissues in a humanized mouse model of typhoid fever. Overall, this study establishes a critical role for S. Typhi T3SSs during its replication within human macrophages and during systemic infection of humanized mice. Importance Salmonella enterica serovar Typhi is a human-restricted pathogen that causes typhoid fever. Understanding the key virulence mechanisms that facilitate S. Typhi replication in human phagocytes will enable rational vaccine and antibiotic development to limit spread of this pathogen. While S. Typhimurium replication in murine models has been studied extensively, there is limited information available about S. Typhi replication in human macrophages, some of which directly conflicts with findings from S. Typhimurium murine models. This study establishes that both of S. Typhi's two Type 3 Secretion Systems (T3SS-1 and -2) contribute to intramacrophage replication and virulence.
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Göser V, Sander N, Schulte M, Scharte F, Franzkoch R, Liss V, Psathaki OE, Hensel M. Single molecule analyses reveal dynamics of Salmonella translocated effector proteins in host cell endomembranes. Nat Commun 2023; 14:1240. [PMID: 36870997 PMCID: PMC9985595 DOI: 10.1038/s41467-023-36758-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 02/16/2023] [Indexed: 03/06/2023] Open
Abstract
The facultative intracellular pathogen Salmonella enterica remodels the host endosomal system for survival and proliferation inside host cells. Salmonella resides within the Salmonella-containing vacuole (SCV) and by Salmonella-induced fusions of host endomembranes, the SCV is connected with extensive tubular structures termed Salmonella-induced filaments (SIF). The intracellular lifestyle of Salmonella critically depends on effector proteins translocated into host cells. A subset of effectors is associated with, or integral in SCV and SIF membranes. How effectors reach their subcellular destination, and how they interact with endomembranes remodeled by Salmonella remains to be determined. We deployed self-labeling enzyme tags to label translocated effectors in living host cells, and analyzed their single molecule dynamics. Translocated effectors diffuse in membranes of SIF with mobility comparable to membrane-integral host proteins in endomembranes. Dynamics differ between various effectors investigated and is dependent on membrane architecture of SIF. In the early infection, host endosomal vesicles are associated with Salmonella effectors. Effector-positive vesicles continuously fuse with SCV and SIF membranes, providing a route of effector delivery by translocation, interaction with endosomal vesicles, and ultimately fusion with the continuum of SCV/SIF membranes. This mechanism controls membrane deformation and vesicular fusion to generate the specific intracellular niche for bacterial survival and proliferation.
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Affiliation(s)
- Vera Göser
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Nathalie Sander
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Marc Schulte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Felix Scharte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Rico Franzkoch
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany.,iBiOs - Integrated Bioimaging Facility Osnabrück, Osnabrück, Germany
| | - Viktoria Liss
- iBiOs - Integrated Bioimaging Facility Osnabrück, Osnabrück, Germany
| | - Olympia E Psathaki
- iBiOs - Integrated Bioimaging Facility Osnabrück, Osnabrück, Germany.,CellNanOs - Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany. .,CellNanOs - Center of Cellular Nanoanalytics Osnabrück, Osnabrück, Germany.
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Meng K, Zhu P, Shi L, Li S. Determination of the Salmonella intracellular lifestyle by the diversified interaction of Type III secretion system effectors and host GTPases. WIREs Mech Dis 2023; 15:e1587. [PMID: 36250298 DOI: 10.1002/wsbm.1587] [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: 07/22/2022] [Revised: 09/03/2022] [Accepted: 09/03/2022] [Indexed: 11/06/2022]
Abstract
Intracellular bacteria have developed sophisticated strategies to subvert the host endomembrane system to establish a stable replication niche. Small GTPases are critical players in regulating each step of membrane trafficking events, such as vesicle biogenesis, cargo transport, tethering, and fusion events. Salmonella is a widely studied facultative intracellular bacteria. Salmonella delivers several virulence proteins, termed effectors, to regulate GTPase dynamics and subvert host trafficking for their benefit. In this review, we summarize an updated and systematic understanding of the interactions between bacterial effectors and host GTPases in determining the intracellular lifestyle of Salmonella. This article is categorized under: Infectious Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Kun Meng
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Ping Zhu
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China
| | - Liuliu Shi
- School of Basic Medical Science, Hubei University of Medicine, Shiyan, Hubei, China
| | - Shan Li
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, Hubei, China.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China.,College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, Hubei, China
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Ireton K, Gyanwali GC, Herath TUB, Lee N. Exploitation of the host exocyst complex by bacterial pathogens. Mol Microbiol 2023. [PMID: 36717381 DOI: 10.1111/mmi.15034] [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: 11/17/2022] [Revised: 01/24/2023] [Accepted: 01/26/2023] [Indexed: 02/01/2023]
Abstract
Intracellular bacterial pathogens remodel the plasma membrane of eukaryotic cells in order to establish infection. A common and well-studied mechanism of plasma membrane remodelling involves bacterial stimulation of polymerization of the host actin cytoskeleton. Here, we discuss recent results showing that several bacterial pathogens also exploit the host vesicular trafficking pathway of 'polarized exocytosis' to expand and reshape specific regions in the plasma membrane during infection. Polarized exocytosis is mediated by an evolutionarily conserved octameric protein complex termed the exocyst. We describe examples in which the bacteria Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Shigella flexneri co-opt the exocyst to promote internalization into human cells or intercellular spread within host tissues. We also discuss results showing that Legionella pneumophila or S. flexneri manipulate exocyst components to modify membrane vacuoles to favour intracellular replication or motility of bacteria. Finally, we propose potential ways that pathogens manipulate exocyst function, discuss how polarized exocytosis might promote infection and highlight the importance of future studies to determine how actin polymerization and polarized exocytosis are coordinated to achieve optimal bacterial infection.
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Affiliation(s)
- Keith Ireton
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | | | - Thilina U B Herath
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Nicole Lee
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
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Weyrich A, Guerrero-Altamirano TP, Yasar S, Czirják GÁ, Wachter B, Fickel J. First Steps towards the Development of Epigenetic Biomarkers in Female Cheetahs ( Acinonyx jubatus). LIFE (BASEL, SWITZERLAND) 2022; 12:life12060920. [PMID: 35743950 PMCID: PMC9225391 DOI: 10.3390/life12060920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/10/2022] [Accepted: 06/16/2022] [Indexed: 11/16/2022]
Abstract
Free-ranging cheetahs (Acinonyx jubatus) are generally healthy, whereas cheetahs under human care, such as those in zoological gardens, suffer from ill-defined infectious and degenerative pathologies. These differences are only partially explained by husbandry management programs because both groups share low genetic diversity. However, mounting evidence suggests that physiological differences between populations in different environments can be tracked down to differences in epigenetic signatures. Here, we identified differentially methylated regions (DMRs) between free-ranging cheetahs and conspecifics in zoological gardens and prospect putative links to pathways relevant to immunity, energy balance and homeostasis. Comparing epigenomic DNA methylation profiles obtained from peripheral blood mononuclear cells (PBMCs) from eight free-ranging female cheetahs from Namibia and seven female cheetahs living in zoological gardens within Europe, we identified DMRs of which 22 were hypermethylated and 23 hypomethylated. Hypermethylated regions in cheetahs under human care were located in the promoter region of a gene involved in host-pathogen interactions (KLC1) and in an intron of a transcription factor relevant for the development of pancreatic β-cells, liver, and kidney (GLIS3). The most canonical mechanism of DNA methylation in promoter regions is assumed to repress gene transcription. Taken together, this could indicate that hypermethylation at the promoter region of KLC1 is involved in the reduced immunity in cheetahs under human care. This approach can be generalized to characterize DNA methylation profiles in larger cheetah populations under human care with a more granular longitudinal data collection, which, in the future, could be used to monitor the early onset of pathologies, and ultimately translate into the development of biomarkers with prophylactic and/or therapeutic potential.
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Affiliation(s)
- Alexandra Weyrich
- Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany; (T.P.G.-A.); (S.Y.)
- Correspondence: (A.W.); (B.W.); (J.F.)
| | - Tania P. Guerrero-Altamirano
- Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany; (T.P.G.-A.); (S.Y.)
- Program in Genetics and Genomics, Duke University, Durham, NC 27708, USA
| | - Selma Yasar
- Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany; (T.P.G.-A.); (S.Y.)
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Gábor Á. Czirják
- Department of Wildlife Diseases, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany;
| | - Bettina Wachter
- Department of Evolutionary Ecology, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany
- Correspondence: (A.W.); (B.W.); (J.F.)
| | - Jörns Fickel
- Department of Evolutionary Genetics, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315 Berlin, Germany; (T.P.G.-A.); (S.Y.)
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
- Correspondence: (A.W.); (B.W.); (J.F.)
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