1
|
Wang BX, Leshchiner D, Luo L, Tuncel M, Hokamp K, Hinton JCD, Monack DM. High-throughput fitness experiments reveal specific vulnerabilities of human-adapted Salmonella during stress and infection. Nat Genet 2024; 56:1288-1299. [PMID: 38831009 PMCID: PMC11176087 DOI: 10.1038/s41588-024-01779-7] [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: 09/12/2023] [Accepted: 04/25/2024] [Indexed: 06/05/2024]
Abstract
Salmonella enterica is comprised of genetically distinct 'serovars' that together provide an intriguing model for exploring the genetic basis of pathogen evolution. Although the genomes of numerous Salmonella isolates with broad variations in host range and human disease manifestations have been sequenced, the functional links between genetic and phenotypic differences among these serovars remain poorly understood. Here, we conduct high-throughput functional genomics on both generalist (Typhimurium) and human-restricted (Typhi and Paratyphi A) Salmonella at unprecedented scale in the study of this enteric pathogen. Using a comprehensive systems biology approach, we identify gene networks with serovar-specific fitness effects across 25 host-associated stresses encountered at key stages of human infection. By experimentally perturbing these networks, we characterize previously undescribed pseudogenes in human-adapted Salmonella. Overall, this work highlights specific vulnerabilities encoded within human-restricted Salmonella that are linked to the degradation of their genomes, shedding light into the evolution of this enteric pathogen.
Collapse
Affiliation(s)
- Benjamin X Wang
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Lijuan Luo
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Miles Tuncel
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | - Karsten Hokamp
- Department of Genetics, School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Jay C D Hinton
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Denise M Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
| |
Collapse
|
2
|
Stepien TA, Singletary LA, Guerra FE, Karlinsey JE, Libby SJ, Jaslow SL, Gaggioli MR, Gibbs KD, Ko DC, Brehm MA, Greiner DL, Shultz LD, Fang FC. Nuclear factor kappa B-dependent persistence of Salmonella Typhi and Paratyphi in human macrophages. mBio 2024; 15:e0045424. [PMID: 38497655 PMCID: PMC11005419 DOI: 10.1128/mbio.00454-24] [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: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 03/19/2024] Open
Abstract
Salmonella serovars Typhi and Paratyphi cause a prolonged illness known as enteric fever, whereas other serovars cause acute gastroenteritis. Mechanisms responsible for the divergent clinical manifestations of nontyphoidal and enteric fever Salmonella infections have remained elusive. Here, we show that S. Typhi and S. Paratyphi A can persist within human macrophages, whereas S. Typhimurium rapidly induces apoptotic macrophage cell death that is dependent on Salmonella pathogenicity island 2 (SPI2). S. Typhi and S. Paratyphi A lack 12 specific SPI2 effectors with pro-apoptotic functions, including nine that target nuclear factor κB (NF-κB). Pharmacologic inhibition of NF-κB or heterologous expression of the SPI2 effectors GogA or GtgA restores apoptosis of S. Typhi-infected macrophages. In addition, the absence of the SPI2 effector SarA results in deficient signal transducer and activator of transcription 1 (STAT1) activation and interleukin 12 production, leading to impaired TH1 responses in macrophages and humanized mice. The absence of specific nontyphoidal SPI2 effectors may allow S. Typhi and S. Paratyphi A to cause chronic infections. IMPORTANCE Salmonella enterica is a common cause of gastrointestinal infections worldwide. The serovars Salmonella Typhi and Salmonella Paratyphi A cause a distinctive systemic illness called enteric fever, whose pathogenesis is incompletely understood. Here, we show that enteric fever Salmonella serovars lack 12 specific virulence factors possessed by nontyphoidal Salmonella serovars, which allow the enteric fever serovars to persist within human macrophages. We propose that this fundamental difference in the interaction of Salmonella with human macrophages is responsible for the chronicity of typhoid and paratyphoid fever, suggesting that targeting the nuclear factor κB (NF-κB) complex responsible for macrophage survival could facilitate the clearance of persistent bacterial infections.
Collapse
Affiliation(s)
- Taylor A. Stepien
- Department of Global Health, University of Washington, Seattle, Washington, USA
| | | | - Fermin E. Guerra
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| | - Joyce E. Karlinsey
- Department of Microbiology, University of Washington, Seattle, Washington, USA
| | - Stephen J. Libby
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| | - Sarah L. Jaslow
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Margaret R. Gaggioli
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Kyle D. Gibbs
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Dennis C. Ko
- Department of Molecular Genetics and Microbiology, Duke University, Durham, North Carolina, USA
| | - Michael A. Brehm
- Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Dale L. Greiner
- Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | | | - Ferric C. Fang
- Department of Global Health, University of Washington, Seattle, Washington, USA
- Department of Microbiology, University of Washington, Seattle, Washington, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
| |
Collapse
|
3
|
Schulte M, Grotheer L, Hensel M. Bright individuals: Applications of fluorescent protein-based reporter systems in single-cell cellular microbiology. Mol Microbiol 2024; 121:605-617. [PMID: 38234267 DOI: 10.1111/mmi.15227] [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: 07/18/2023] [Revised: 12/30/2023] [Accepted: 01/02/2024] [Indexed: 01/19/2024]
Abstract
Activation and function of virulence functions of bacterial pathogens are highly dynamic in time and space, and can show considerable heterogeneity between individual cells in pathogen populations. To investigate the complex events in host-pathogen interactions, single cell analyses are required. Fluorescent proteins (FPs) are excellent tools to follow the fate of individual bacterial cells during infection, and can also be deployed to use the pathogen as a sensor for its specific environment in host cells or host organisms. This Resources describes design and applications of dual fluorescence reporters (DFR) in cellular microbiology. DFR feature constitutively expressed FPs for detection of bacterial cells, and FPs expressed by an environmentally regulated promoter for interrogation of niche-specific cues or nutritional parameters. Variations of the basic design allow the generation of DFR that can be used to analyze, on single cell level, bacterial proliferation during infection, subcellular localization of intracellular bacteria, stress response, or persister state. We describe basic considerations for DFR design and review recent applications of DFR in cellular microbiology.
Collapse
Affiliation(s)
- Marc Schulte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs-Center of Cellular Nanoanalytics Osnabrück, Universität Osnabrück, Osnabrück, Germany
| | - Luisa Grotheer
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs-Center of Cellular Nanoanalytics Osnabrück, Universität Osnabrück, Osnabrück, Germany
| |
Collapse
|
4
|
Scharte F, Franzkoch R, Hensel M. Flagella-mediated cytosolic motility of Salmonella enterica Paratyphi A aids in evasion of xenophagy but does not impact egress from host cells. Mol Microbiol 2024; 121:413-430. [PMID: 37278220 DOI: 10.1111/mmi.15104] [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: 04/29/2023] [Revised: 05/19/2023] [Accepted: 05/23/2023] [Indexed: 06/07/2023]
Abstract
Salmonella enterica is a common foodborne, facultative intracellular enteropathogen. Typhoidal serovars like Paratyphi A (SPA) are human restricted and cause severe systemic diseases, while many serovars like Typhimurium (STM) have a broad host range, and usually lead to self-limiting gastroenteritis. There are key differences between typhoidal and non-typhoidal Salmonella in pathogenesis, but underlying mechanisms remain largely unknown. Transcriptomes and phenotypes in epithelial cells revealed induction of motility, flagella and chemotaxis genes for SPA but not STM. SPA exhibited cytosolic motility mediated by flagella. In this study, we applied single-cell microscopy to analyze triggers and cellular consequences of cytosolic motility. Live-cell imaging (LCI) revealed that SPA invades host cells in a highly cooperative manner. Extensive membrane ruffling at invasion sites led to increased membrane damage in nascent Salmonella-containing vacuole, and subsequent cytosolic release. After release into the cytosol, motile bacteria showed the same velocity as under culture conditions in media. Reduced capture of SPA by autophagosomal membranes was observed by LCI and electron microscopy. Prior work showed that SPA does not use flagella-mediated motility for cell exit via the intercellular spread. However, cytosolic motile SPA was invasion-primed if released from host cells. Our results reveal flagella-mediated cytosolic motility as a possible xenophagy evasion mechanism that could drive disease progression and contributes to the dissemination of systemic infection.
Collapse
Affiliation(s)
- Felix Scharte
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Rico Franzkoch
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- Universität Osnabrück, iBiOs-Integrated Bioimaging Facility, Osnabrück, Germany
| | - Michael Hensel
- Abteilung Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- Universität Osnabrück, CellNanOs-Center of Cellular Nanoanalytics, Osnabrück, Germany
| |
Collapse
|
5
|
Zhang S, Yang H, Wang M, Mantovani D, Yang K, Witte F, Tan L, Yue B, Qu X. Immunomodulatory biomaterials against bacterial infections: Progress, challenges, and future perspectives. Innovation (N Y) 2023; 4:100503. [PMID: 37732016 PMCID: PMC10507240 DOI: 10.1016/j.xinn.2023.100503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Accepted: 08/24/2023] [Indexed: 09/22/2023] Open
Abstract
Bacterial infectious diseases are one of the leading causes of death worldwide. Even with the use of multiple antibiotic treatment strategies, 4.95 million people died from drug-resistant bacterial infections in 2019. By 2050, the number of deaths will reach 10 million annually. The increasing mortality may be partly due to bacterial heterogeneity in the infection microenvironment, such as drug-resistant bacteria, biofilms, persister cells, intracellular bacteria, and small colony variants. In addition, the complexity of the immune microenvironment at different stages of infection makes biomaterials with direct antimicrobial activity unsatisfactory for the long-term treatment of chronic bacterial infections. The increasing mortality may be partly attributed to the biomaterials failing to modulate the active antimicrobial action of immune cells. Therefore, there is an urgent need for effective alternatives to treat bacterial infections. Accordingly, the development of immunomodulatory antimicrobial biomaterials has recently received considerable interest; however, a comprehensive review of their research progress is lacking. In this review, we focus mainly on the research progress and future perspectives of immunomodulatory antimicrobial biomaterials used at different stages of infection. First, we describe the characteristics of the immune microenvironment in the acute and chronic phases of bacterial infections. Then, we highlight the immunomodulatory strategies for antimicrobial biomaterials at different stages of infection and their corresponding advantages and disadvantages. Moreover, we discuss biomaterial-mediated bacterial vaccines' potential applications and challenges for activating innate and adaptive immune memory. This review will serve as a reference for future studies to develop next-generation immunomodulatory biomaterials and accelerate their translation into clinical practice.
Collapse
Affiliation(s)
- Shutao Zhang
- Department of Bone and Joint Surgery, Department of Orthopedics, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200001, China
| | - Hongtao Yang
- School of Engineering Medicine, Beihang University, Beijing 100191, China
| | - Minqi Wang
- Department of Bone and Joint Surgery, Department of Orthopedics, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200001, China
| | - Diego Mantovani
- Laboratory for Biomaterials and Bioengineering, Canada Research Chair I in Biomaterials and Bioengineering for the Innovation in Surgery, Department of Min-Met-Materials Engineering, Research Center of CHU de Quebec, Division of Regenerative Medicine, Laval University, Quebec City, QC G1V 0A6, Canada
| | - Ke Yang
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Frank Witte
- Department of Prosthodontics, Geriatric Dentistry and Craniomandibular Disorders, Charite Medical University, Assmannshauser Strasse 4–6, 14197 Berlin, Germany
| | - Lili Tan
- Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
| | - Bing Yue
- Department of Bone and Joint Surgery, Department of Orthopedics, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200001, China
| | - Xinhua Qu
- Department of Bone and Joint Surgery, Department of Orthopedics, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai 200001, China
| |
Collapse
|
6
|
Thurston TLM, Holden DW. The Salmonella Typhi SPI-2 injectisome enigma. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001405. [PMID: 37862087 PMCID: PMC10634361 DOI: 10.1099/mic.0.001405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 10/11/2023] [Indexed: 10/21/2023]
Abstract
The Salmonella pathogenicity island 2 (SPI-2)-encoded type III secretion system (injectisome) is assembled following uptake of bacteria into vacuoles in mammalian cells. The injectisome translocates virulence proteins (effectors) into infected cells. Numerous studies have established the requirement for a functional SPI-2 injectisome for growth of Salmonella Typhimurium in mouse macrophages, but the results of similar studies involving Salmonella Typhi and human-derived macrophages are not consistent. It is important to clarify the functions of the S. Typhi SPI-2 injectisome, not least because an inactivated SPI-2 injectisome forms the basis for live attenuated S. Typhi vaccines that have undergone extensive trials in humans. Intracellular expression of injectisome genes and effector delivery take longer in the S. Typhi/human macrophage model than for S. Typhimurium and we propose that this could explain the conflicting results. Furthermore, strains of both S. Typhimurium and S. Typhi contain intact genes for several 'core' effectors. In S. Typhimurium these cooperate to regulate the vacuole membrane and contribute to intracellular bacterial replication; similar functions are therefore likely in S. Typhi.
Collapse
Affiliation(s)
- Teresa L. M. Thurston
- Department of Infectious Disease, Centre for Bacterial Resistance Biology, Imperial College London, London, SW7 2AZ, UK
| | - David W. Holden
- Department of Infectious Disease, Centre for Bacterial Resistance Biology, Imperial College London, London, SW7 2AZ, UK
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
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.
Collapse
|
9
|
Schulte M, Hensel M, Miskiewicz K. Exposure to stressors and antimicrobials induces cell-autonomous ultrastructural heterogeneity of an intracellular bacterial pathogen. Front Cell Infect Microbiol 2022; 12:963354. [DOI: 10.3389/fcimb.2022.963354] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 10/25/2022] [Indexed: 11/17/2022] Open
Abstract
Despite their clonality, intracellular bacterial pathogens commonly show remarkable physiological heterogeneity during infection of host cells. Physiological heterogeneity results in distinct ultrastructural morphotypes, but the correlation between bacterial physiological state and ultrastructural appearance remains to be established. In this study, we showed that individual cells of Salmonella enterica serovar Typhimurium are heterogeneous in their ultrastructure. Two morphotypes based on the criterion of cytoplasmic density were discriminated after growth under standard culture conditions, as well as during intracellular lifestyle in mammalian host cells. We identified environmental conditions which affect cytoplasmic densities. Using compounds generating oxygen radicals and defined mutant strains, we were able to link the occurrence of an electron-dense ultrastructural morphotype to exposure to oxidative stress and other stressors. Furthermore, by combining ultrastructural analyses of Salmonella during infection and fluorescence reporter analyses for cell viability, we provided evidence that two characterized ultrastructural morphotypes with electron-lucent or electron-dense cytoplasm represent viable cells. Moreover, the presence of electron-dense types is stress related and can be experimentally induced only when amino acids are available in the medium. Our study proposes ultrastructural morphotypes as marker for physiological states of individual intracellular pathogens providing a new marker for single cell analyses.
Collapse
|
10
|
Cohen H, Hoede C, Scharte F, Coluzzi C, Cohen E, Shomer I, Mallet L, Holbert S, Serre RF, Schiex T, Virlogeux-Payant I, Grassl GA, Hensel M, Chiapello H, Gal-Mor O. Intracellular Salmonella Paratyphi A is motile and differs in the expression of flagella-chemotaxis, SPI-1 and carbon utilization pathways in comparison to intracellular S. Typhimurium. PLoS Pathog 2022; 18:e1010425. [PMID: 35381053 PMCID: PMC9012535 DOI: 10.1371/journal.ppat.1010425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 04/15/2022] [Accepted: 03/09/2022] [Indexed: 12/21/2022] Open
Abstract
Although Salmonella Typhimurium (STM) and Salmonella Paratyphi A (SPA) belong to the same phylogenetic species, share large portions of their genome and express many common virulence factors, they differ vastly in their host specificity, the immune response they elicit, and the clinical manifestations they cause. In this work, we compared their intracellular transcriptomic architecture and cellular phenotypes during human epithelial cell infection. While transcription induction of many metal transport systems, purines, biotin, PhoPQ and SPI-2 regulons was similar in both intracellular SPA and STM, we identified 234 differentially expressed genes that showed distinct expression patterns in intracellular SPA vs. STM. Surprisingly, clear expression differences were found in SPI-1, motility and chemotaxis, and carbon (mainly citrate, galactonate and ethanolamine) utilization pathways, indicating that these pathways are regulated differently during their intracellular phase. Concurring, on the cellular level, we show that while the majority of STM are non-motile and reside within Salmonella-Containing Vacuoles (SCV), a significant proportion of intracellular SPA cells are motile and compartmentalized in the cytosol. Moreover, we found that the elevated expression of SPI-1 and motility genes by intracellular SPA results in increased invasiveness of SPA, following exit from host cells. These findings demonstrate unexpected flagellum-dependent intracellular motility of a typhoidal Salmonella serovar and intriguing differences in intracellular localization between typhoidal and non-typhoidal salmonellae. We propose that these differences facilitate new cycles of host cell infection by SPA and may contribute to the ability of SPA to disseminate beyond the intestinal lamina propria of the human host during enteric fever. Salmonella enterica is a ubiquitous, facultative intracellular animal and human pathogen. Although non-typhoidal Salmonella (NTS) and typhoidal Salmonella serovars belong to the same phylogenetic species and share many virulence factors, the disease they cause in humans is very different. While the underlying mechanisms for these differences are not fully understood, one possible reason expected to contribute to their different pathogenicity is a distinct expression pattern of genes involved in host-pathogen interactions. Here, we compared the global gene expression and intracellular phenotypes, during human epithelial cell infection of S. Paratyphi A (SPA) and S. Typhimurium (STM), as prototypical serovars of typhoidal and NTS, respectively. Interestingly, we identified different expression patterns in key virulence and metabolic pathways, cytosolic motility and increased reinvasion of SPA, following exit from infected cells. We hypothesize that these differences contribute to the invasive and systemic disease developed following SPA infection in humans.
Collapse
Affiliation(s)
- Helit Cohen
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
| | - Claire Hoede
- Université Fédérale de Toulouse, INRAE, BioinfOmics, UR MIAT, GenoToul Bioinformatics facility, 31326, Castanet-Tolosan, France
| | - Felix Scharte
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
| | - Charles Coluzzi
- INRAE, Université Paris-Saclay, MaIAGE, Jouy-en-Josas, France
| | - Emiliano Cohen
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
| | - Inna Shomer
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
| | - Ludovic Mallet
- Université Fédérale de Toulouse, INRAE, BioinfOmics, UR MIAT, GenoToul Bioinformatics facility, 31326, Castanet-Tolosan, France
| | | | | | - Thomas Schiex
- Université Fédérale de Toulouse, ANITI, INRAE, Toulouse, France
| | | | - Guntram A. Grassl
- Institute of Medical Microbiology and Hospital Epidemiology, Hannover Medical School and German Center for Infection Research (DZIF), Hanover, Germany
| | - Michael Hensel
- Abt. Mikrobiologie, Universität Osnabrück, Osnabrück, Germany
- CellNanOs–Center of Cellular Nanoanalytics Osnabrück, Universität Osnabrück, Osnabrück, Germany
- * E-mail: (MH); (HC); (OG-M)
| | - Hélène Chiapello
- Université Fédérale de Toulouse, INRAE, BioinfOmics, UR MIAT, GenoToul Bioinformatics facility, 31326, Castanet-Tolosan, France
- INRAE, Université Paris-Saclay, MaIAGE, Jouy-en-Josas, France
- * E-mail: (MH); (HC); (OG-M)
| | - Ohad Gal-Mor
- The Infectious Diseases Research Laboratory, Sheba Medical Center, Tel-Hashomer, Israel
- Department of Clinical Microbiology and Immunology, Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
- * E-mail: (MH); (HC); (OG-M)
| |
Collapse
|
11
|
Peptidoglycan editing in non-proliferating intracellular Salmonella as source of interference with immune signaling. PLoS Pathog 2022; 18:e1010241. [PMID: 35077524 PMCID: PMC8815878 DOI: 10.1371/journal.ppat.1010241] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/04/2022] [Accepted: 01/01/2022] [Indexed: 02/07/2023] Open
Abstract
Salmonella enterica causes intracellular infections that can be limited to the intestine or spread to deeper tissues. In most cases, intracellular bacteria show moderate growth. How these bacteria face host defenses that recognize peptidoglycan, is poorly understood. Here, we report a high-resolution structural analysis of the minute amounts of peptidoglycan purified from S. enterica serovar Typhimurium (S. Typhimurium) infecting fibroblasts, a cell type in which this pathogen undergoes moderate growth and persists for days intracellularly. The peptidoglycan of these non-proliferating bacteria contains atypical crosslinked muropeptides with stem peptides trimmed at the L-alanine-D-glutamic acid-(γ) or D-glutamic acid-(γ)-meso-diaminopimelic acid motifs, both sensed by intracellular immune receptors. This peptidoglycan has a reduced glycan chain average length and ~30% increase in the L,D-crosslink, a type of bridge shared by all the atypical crosslinked muropeptides identified. The L,D-transpeptidases LdtD (YcbB) and LdtE (YnhG) are responsible for the formation of these L,D-bridges in the peptidoglycan of intracellular bacteria. We also identified in a fraction of muropeptides an unprecedented modification in the peptidoglycan of intracellular S. Typhimurium consisting of the amino alcohol alaninol replacing the terminal (fourth) D-alanine. Alaninol was still detectable in the peptidoglycan of a double mutant lacking LdtD and LdtE, thereby ruling out the contribution of these enzymes to this chemical modification. Remarkably, all multiple mutants tested lacking candidate enzymes that either trim stem peptides or form the L,D-bridges retain the capacity to modify the terminal D-alanine to alaninol and all attenuate NF-κB nuclear translocation. These data inferred a potential role of alaninol-containing muropeptides in attenuating pro-inflammatory signaling, which was confirmed with a synthetic tetrapeptide bearing such amino alcohol. We suggest that the modification of D-alanine to alaninol in the peptidoglycan of non-proliferating intracellular S. Typhimurium is an editing process exploited by this pathogen to evade immune recognition inside host cells. The peptidoglycan, built as a giant polymer of glycan chains crosslinked with short peptides, is essential for cell shape and survival in most bacteria. Its unique chemistry is recognized by innate immune receptors, thereby enabling neutralization of invading microbes. A striking feature of the peptidoglycan is its constant remodeling by a plethora of endogenous enzymes. In addition, some bacterial pathogens introduce structural modifications that interfere with immune recognition. These modifications have been characterized in pathogens mostly in laboratory nutrient media. Whether facultative intracellular pathogens modify peptidoglycan structure inside host cells, was unknown. The work presented here shows that non-proliferating Salmonella enterica serovar Typhimurium remodels the peptidoglycan structure in response to intracellular cues and that some of these modifications involve unprecedented changes as the presence of an amino alcohol that hampers activation of the master immune regulator NF-κB. Peptidoglycan editing might therefore empower persistence of bacterial pathogens in the intracellular niche.
Collapse
|
12
|
Schulte M, Hensel M. Flow Cytometry-Based Single Cell Analyses of Bacterial Adaptation to Intracellular Environments. Methods Mol Biol 2022; 2427:105-117. [PMID: 35619029 DOI: 10.1007/978-1-0716-1971-1_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Since decades, flow cytometry (FC) is a powerful technique to perform single cell analyses with high accuracy and throughput. Moreover, FC is the method of choice to study bacterial cell heterogeneity and complements single-cell imaging techniques. The complex experimental approaches for FC sample preparation and the subsequent FC adjustment and gating strategy demand careful considerations to be successful when analyzing complex microbial populations, especially when liberated populations of intracellular bacterial pathogens, or bacterial pathogens inside intact host cells are analyzed. Here, we provide a set of experimental protocols for FC sample preparation of (1) in vitro cultured bacterial cells, (2) liberated intracellular bacteria from host cells, or (3) preparation of intact infected phagocytic or epithelial cells commonly used as host cells in infection biology. Since sample preparation, cytometer adjustment, and gating strategy are essential for experimental success, we aim to provide our expertise to support application of FC by other researchers.
Collapse
Affiliation(s)
- Marc Schulte
- Abteilung Mikrobiologie and CellNanOs-Center of Cellular Nanoanalytics Osnabrück, Fachbereich Biologie/Chemie, Universität Osnabrück Barbarastr, Osnabrück, Germany
| | - Michael Hensel
- Abteilung Mikrobiologie and CellNanOs-Center of Cellular Nanoanalytics Osnabrück, Fachbereich Biologie/Chemie, Universität Osnabrück Barbarastr, Osnabrück, Germany.
| |
Collapse
|