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Miner MV, Rauch I. Why put yourself on a pedestal? The pathogenic role of the A/E pedestal. Infect Immun 2024:e0048923. [PMID: 38591884 DOI: 10.1128/iai.00489-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024] Open
Abstract
Certain Escherichia coli (E. coli) strains are attaching and effacing (A/E) lesion pathogens that primarily infect intestinal epithelial cells. They cause actin restructuring and polymerization within the host cell to create an actin-rich protrusion below the site of adherence, termed the pedestal. Although there is clarity on the pathways initiating pedestal formation, the underlying purpose(s) of the pedestal remains ambiguous. The conservation of pedestal-forming activity across multiple pathogens and redundancy in formation pathways indicate a pathogenic advantage. However, few decisive conclusions have been drawn, given that the results vary between model systems. Some research argues that the pedestal increases the colonization capability of the bacterium. These studies utilize A/E pathogens specifically deficient in pedestal formation to evaluate adhesion and intestinal colonization following infection. There have been many proposed mechanisms for the colonization benefit conferred by the pedestal. One suggested benefit is that the pedestal allows for direct cytosolic anchoring through incorporation of the established host cortical actin, causing a stable link between the pathogen and cell structure. The pedestal may confer enhanced motility, as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) are better able to migrate on the surface of host cells and infect neighboring cells in the presence of the pedestal. Additionally, some research suggests that the pedestal improves effector delivery. This review will investigate the purpose of pedestal formation using evidence from recent literature and will critically evaluate the methodology and model systems. Most importantly, we will contextualize the proposed functions to reconcile potential synergistic effects.
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Affiliation(s)
- M V Miner
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
| | - I Rauch
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
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2
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Haritan N, Bouman EA, Nandi I, Shtuhin-Rahav R, Zlotkin-Rivkin E, Danieli T, Melamed-Book N, Nir-Keren Y, Aroeti B. Topology and function of translocated EspZ. mBio 2023; 14:e0075223. [PMID: 37341483 PMCID: PMC10470495 DOI: 10.1128/mbio.00752-23] [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: 03/23/2023] [Accepted: 05/05/2023] [Indexed: 06/22/2023] Open
Abstract
EspZ and Tir are essential virulence effectors of enteropathogenic Escherichia coli (EPEC). EspZ, the second translocated effector, has been suggested to antagonize host cell death induced by the first translocated effector, Tir (translocated intimin receptor). Another characteristic of EspZ is its localization to host mitochondria. However, studies that explored the mitochondrial localization of EspZ have examined the ectopically expressed effector and not the more physiologically relevant translocated effector. Here, we confirmed the membrane topology of translocated EspZ at infection sites and the involvement of Tir in confining its localization to these sites. Unlike the ectopically expressed EspZ, the translocated EspZ did not colocalize with mitochondrial markers. Moreover, no correlation has been found between the capacity of ectopically expressed EspZ to target mitochondria and the ability of translocated EspZ to protect against cell death. Translocated EspZ may have to some extent diminished F-actin pedestal formation induced by Tir but has a marked effect on protecting against host cell death and on promoting host colonization by the bacteria. Taken together, our results suggest that EspZ plays an essential role in facilitating bacterial colonization, likely by antagonizing cell death mediated by Tir at the onset of bacterial infection. This activity of EspZ, which occurs by targeting host membrane components at infection sites, and not mitochondria, may contribute to successful bacterial colonization of the infected intestine. IMPORTANCE EPEC is an important human pathogen that causes acute infantile diarrhea. EspZ is an essential virulence effector protein translocated from the bacterium into the host cells. Detailed knowledge of its mechanisms of action is, therefore, critical for better understanding the EPEC disease. We show that Tir, the first translocated effector, confines the localization of EspZ, the second translocated effector, to infection sites. This activity is important for antagonizing the pro-cell death activity conferred by Tir. Moreover, we show that translocated EspZ leads to effective bacterial colonization of the host. Hence, our data suggest that translocated EspZ is essential because it confers host cell survival to allow bacterial colonization at an early stage of bacterial infection. It performs these activities by targeting host membrane components at infection sites. Identifying these targets is critical for elucidating the molecular mechanism underlying the EspZ activity and the EPEC disease.
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Affiliation(s)
- Nir Haritan
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Etan Amse Bouman
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ipsita Nandi
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Raisa Shtuhin-Rahav
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Efrat Zlotkin-Rivkin
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Tsafi Danieli
- The Protein Production Facility, Wolfson Centre for Applied Structural Biology, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Naomi Melamed-Book
- Bioimaging Unit, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yael Nir-Keren
- The Protein Production Facility, Wolfson Centre for Applied Structural Biology, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Benjamin Aroeti
- Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
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3
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Lei M, Trivedi VD, Nair NU, Lee K, Van Deventer JA. Flow cytometric evaluation of yeast-bacterial cell-cell interactions. Biotechnol Bioeng 2023; 120:399-408. [PMID: 36259110 PMCID: PMC10072783 DOI: 10.1002/bit.28253] [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: 06/10/2022] [Revised: 09/23/2022] [Accepted: 10/09/2022] [Indexed: 01/13/2023]
Abstract
Synthetic cell-cell interaction systems can be useful for understanding multicellular communities or for screening binding molecules. We adapt a previously characterized set of synthetic cognate nanobody-antigen pairs to a yeast-bacteria coincubation format and use flow cytometry to evaluate cell-cell interactions mediated by binding between surface-displayed molecules. We further use fluorescence-activated cell sorting to enrich a specific yeast-displayed nanobody within a mixed yeast-display population. Finally, we demonstrate that this system supports the characterization of a therapeutically relevant nanobody-antigen interaction: a previously discovered nanobody that binds to the intimin protein expressed on the surface of enterohemorrhagic Escherichia coli. Overall, our findings indicate that the yeast-bacteria format supports efficient evaluation of ligand-target interactions. With further development, this format may facilitate systematic characterization and high-throughput discovery of bacterial surface-binding molecules.
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Affiliation(s)
- Ming Lei
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155
| | - Vikas D. Trivedi
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155
| | - Nikhil U. Nair
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155
| | - Kyongbum Lee
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155
| | - James A. Van Deventer
- Department of Chemical and Biological Engineering, Tufts University, Medford, Massachusetts 02155
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts 02155
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4
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Xie W, Song L, Wang X, Xu Y, Liu Z, Zhao D, Wang S, Fan X, Wang Z, Gao C, Wang X, Wang L, Qiao X, Zhou H, Cui W, Jiang Y, Li Y, Tang L. A bovine lactoferricin-lactoferrampin-encoding Lactobacillus reuteri CO21 regulates the intestinal mucosal immunity and enhances the protection of piglets against enterotoxigenic Escherichia coli K88 challenge. Gut Microbes 2021; 13:1956281. [PMID: 34369287 PMCID: PMC8354667 DOI: 10.1080/19490976.2021.1956281] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrhea in human and animal. To determine the mechanism of a bovine lactoferricin-lactoferrampin (LFCA)-encoding Lactobacillus reuteri CO21 (LR-LFCA) to enhance the intestinal mucosal immunity, we used a newborn piglet intestine model to study the intestinal response to ETEC. Pigs were chosen due to the anatomical similarity between the porcine and the human intestine.4-day-old piglets were orally administered with LR-LFCA, LR-con (L. reuteri CO21 transformed with pPG612 plasmid) or phosphate buffered saline (PBS) for three consecutive days, within 21 days after these treatments, we found that LR-LFCA can colonize the intestines of piglets, improve the growth performance, enhance immune response and is beneficial for intestinal health of piglets by improving intestinal barrier function and modulating the composition of gut microbiota. Twenty-one days after, piglets were infected with ETEC K88 for 5 days, we found that oral administration of LR-LFCA to neonatal piglets attenuated ETEC-induced the weight loss of piglets and diarrhea incidence. LR-LFCA decreased the production of inflammatory factors and oxidative stress in intestinal mucosa of ETEC-infected piglets. Additionally, LR-LFCA increased the expression of tight junction proteins in the ileum of ETEC-infected piglets. Using LPS-induced porcine intestinal epithelial cells (IPEC-J2) in vitro, we demonstrated that LR-LFCA-mediated increases in the tight junction proteins might depend on the MLCK pathway; LR-LFCA might increase the anti-inflammatory ability by inhibiting the NF-κB pathway. We also found that LR-LFCA may enhance the antioxidant capacity of piglets by activating the Nrf2/HO-1 pathway. This study demonstrates that LR-LFCA is effective at maintaining intestinal epithelial integrity and host homeostasis as well as at repairing intestinal damage after ETEC infection and is thus a promising alternative therapeutic method for intestinal inflammation.
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Affiliation(s)
- Weichun Xie
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Liying Song
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Xueying Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Yigang Xu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Zengsu Liu
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Dongfang Zhao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Shubo Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Xiaolong Fan
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Zhaorui Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Chong Gao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
| | - Xiaona Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Li Wang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Xinyuan Qiao
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Han Zhou
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Wen Cui
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Yanping Jiang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Yijing Li
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China
| | - Lijie Tang
- College of Veterinary Medicine, Northeast Agricultural University, Harbin, China,Northeastern Science Inspection Station, China Ministry of Agriculture Key Laboratory of Animal Pathogen, Harbin, China,CONTACT Lijie Tang College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
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Mannan rich fraction from yeast modulates inflammatory responses in intestinal cells (HT-29) exposed toEscherichia coli. JOURNAL OF APPLIED ANIMAL NUTRITION 2019. [DOI: 10.1017/jan.2019.5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
AbstractMannan from yeast has been demonstrated to limit infection in animals susceptible to gastrointestinal infection, including pigs, poultry and cows, by blocking the mechanism by which gram-negative bacteria adhere to and invade the intestines. EnterotoxigenicEscherichia coli(ETEC) cause post weaning diarrhoea (PWD) which results in poor weight gain and potential death at great economic cost to the farmer. A mannan rich fraction (MRF) was assessedin vitrofor its impact on ETEC infection of HT-29 intestinal cell line. Gene expression markers for inflammation (TNFαandIL-1β) and TLR4 (TICAM-1andLY96) associated recognition of bacteria were significantly elevated following exposure toE. colialone, but not in combination with MRF compared to the control. HT-29 cells exposed to MRF alone demonstrated significantly reduced expression of immune signalling genesIRAK1,IRF7andJUNwhen compared to the control. HT-29 cell protein abundance for TNFα and TLR4 associated proteins were significantly increased in response toE. coliexposure alone while no significant change was observed for MRF treatment withE. coliinfection.E. coliadhesion to HT-29 cells was significantly decreased with addition of MRF compared toE. coliinfection alone. The action of MRF demonstrated its potential capacity to limit infection on anin vitrolevel through blocking bacterial interaction with the intestines that leads to infection as marked by a reduction in proinflammatory responses. MRF on its own demonstrated potential anti-inflammatory effects on intestinal cells with the reduction of proinflammatory responses observed.
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6
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Velle KB, Campellone KG. Enteropathogenic E. coli relies on collaboration between the formin mDia1 and the Arp2/3 complex for actin pedestal biogenesis and maintenance. PLoS Pathog 2018; 14:e1007485. [PMID: 30550556 PMCID: PMC6310289 DOI: 10.1371/journal.ppat.1007485] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 12/28/2018] [Accepted: 11/23/2018] [Indexed: 12/16/2022] Open
Abstract
Enteropathogenic and enterohemorrhagic E. coli (EPEC and EHEC) are closely related extracellular pathogens that reorganize host cell actin into “pedestals” beneath the tightly adherent bacteria. This pedestal-forming activity is both a critical step in pathogenesis, and it makes EPEC and EHEC useful models for studying the actin rearrangements that underlie membrane protrusions. To generate pedestals, EPEC relies on the tyrosine phosphorylated bacterial effector protein Tir to bind host adaptor proteins that recruit N-WASP, a nucleation-promoting factor that activates the Arp2/3 complex to drive actin polymerization. In contrast, EHEC depends on the effector EspFU to multimerize N-WASP and promote Arp2/3 activation. Although these core pathways of pedestal assembly are well-characterized, the contributions of additional actin nucleation factors are unknown. We investigated potential cooperation between the Arp2/3 complex and other classes of nucleators using chemical inhibitors, siRNAs, and knockout cell lines. We found that inhibition of formins impairs actin pedestal assembly, motility, and cellular colonization for bacteria using the EPEC, but not the EHEC, pathway of actin polymerization. We also identified mDia1 as the formin contributing to EPEC pedestal assembly, as its expression level positively correlates with the efficiency of pedestal formation, and it localizes to the base of pedestals both during their initiation and once they have reached steady state. Collectively, our data suggest that mDia1 enhances EPEC pedestal biogenesis and maintenance by generating seed filaments to be used by the N-WASP-Arp2/3-dependent actin nucleation machinery and by sustaining Src-mediated phosphorylation of Tir. Microbial pathogens that rearrange the host actin cytoskeleton have made valuable contributions to our understanding of cell signaling and movement. The assembly and organization of the actin cytoskeleton is driven by proteins called nucleators, which can be manipulated by bacteria including enteropathogenic Escherichia coli (EPEC), a frequent cause of pediatric diarrhea in developing countries. After ingestion, EPEC adhere tightly to cells of the intestine and hijack the underlying cytoskeleton to create protrusions called actin pedestals. While mechanisms of pedestal assembly involving a nucleator called the Arp2/3 complex have been defined for EPEC, the contribution of additional host nucleators has not been determined. We assessed the roles of several actin nucleators in EPEC pedestals and found that in addition to Arp2/3 complex-mediated nucleation, the formin mDia1 is a key contributor to actin assembly. These findings highlight the importance of nucleator collaboration in pathogenesis, and also advance our understanding of the molecular and cellular basis of EPEC infection, which is ultimately important for the discovery of new drug targets.
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Affiliation(s)
- Katrina B. Velle
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
| | - Kenneth G. Campellone
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
- * E-mail:
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7
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Runte CS, Jain U, Getz LJ, Secord S, Kuwae A, Abe A, LeBlanc JJ, Stadnyk AW, Kaper JB, Hansen AM, Thomas NA. Tandem tyrosine phosphosites in the Enteropathogenic Escherichia coli chaperone CesT are required for differential type III effector translocation and virulence. Mol Microbiol 2018; 108:536-550. [PMID: 29509331 DOI: 10.1111/mmi.13948] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/05/2018] [Indexed: 11/29/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) use a type 3 secretion system (T3SS) for injection of effectors into host cells and intestinal colonization. Here, we demonstrate that the multicargo chaperone CesT has two strictly conserved tyrosine phosphosites, Y152 and Y153 that regulate differential effector secretion in EPEC. Conservative substitution of both tyrosine residues to phenylalanine strongly attenuated EPEC type 3 effector injection into host cells, and limited Tir effector mediated intimate adherence during infection. EPEC expressing a CesT Y152F variant were deficient for NleA effector expression and exhibited significantly reduced translocation of NleA into host cells during infection. Other effectors were observed to be dependent on CesT Y152 for maximal translocation efficiency. Unexpectedly, EPEC expressing a CesT Y153F variant exhibited significantly enhanced effector translocation of many CesT-interacting effectors, further implicating phosphosites Y152 and Y153 in CesT functionality. A mouse infection model of intestinal disease using Citrobacter rodentium revealed that CesT tyrosine substitution variants displayed delayed colonization and were more rapidly cleared from the intestine. These data demonstrate genetically separable functions for tandem tyrosine phosphosites within CesT. Therefore, CesT via its C-terminal tyrosine phosphosites, has relevant roles beyond typical type III secretion chaperones that interact and stabilize effector proteins.
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Affiliation(s)
- Cameron S Runte
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Umang Jain
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Landon J Getz
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sabrina Secord
- Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Asaomi Kuwae
- Laboratory of Bacterial Infection, Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Akio Abe
- Laboratory of Bacterial Infection, Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Jason J LeBlanc
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Medicine, Division of Infectious Diseases, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Andrew W Stadnyk
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - James B Kaper
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Anne-Marie Hansen
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Nikhil A Thomas
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Medicine, Division of Infectious Diseases, Dalhousie University, Halifax, Nova Scotia, Canada
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8
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Velle KB, Campellone KG. Extracellular motility and cell-to-cell transmission of enterohemorrhagic E. coli is driven by EspFU-mediated actin assembly. PLoS Pathog 2017; 13:e1006501. [PMID: 28771584 PMCID: PMC5557606 DOI: 10.1371/journal.ppat.1006501] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 08/15/2017] [Accepted: 06/30/2017] [Indexed: 12/20/2022] Open
Abstract
Enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC) are closely-related pathogens that attach tightly to intestinal epithelial cells, efface microvilli, and promote cytoskeletal rearrangements into protrusions called actin pedestals. To trigger pedestal formation, EPEC employs the tyrosine phosphorylated transmembrane receptor Tir, while EHEC relies on the multivalent scaffolding protein EspFU. The ability to generate these structures correlates with bacterial colonization in several animal models, but the precise function of pedestals in infection remains unclear. To address this uncertainty, we characterized the colonization properties of EPEC and EHEC during infection of polarized epithelial cells. We found that EPEC and EHEC both formed distinct bacterial communities, or "macrocolonies," that encompassed multiple host cells. Tir and EspFU, as well as the host Arp2/3 complex, were all critical for the expansion of macrocolonies over time. Unexpectedly, EspFU accelerated the formation of larger macrocolonies compared to EPEC Tir, as EspFU-mediated actin assembly drove faster bacterial motility to cell junctions, where bacteria formed a secondary pedestal on a neighboring cell and divided, allowing one of the daughters to disengage and infect the second cell. Collectively, these data reveal that EspFU enhances epithelial colonization by increasing actin-based motility and promoting an efficient method of cell-to-cell transmission.
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Affiliation(s)
- Katrina B. Velle
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
| | - Kenneth G. Campellone
- Department of Molecular and Cell Biology, Institute for Systems Genomics, University of Connecticut, Storrs, Connecticut, United States of America
- * E-mail:
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9
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Flowers LJ, Bou Ghanem EN, Leong JM. Synchronous Disease Kinetics in a Murine Model for Enterohemorrhagic E. coli Infection Using Food-Borne Inoculation. Front Cell Infect Microbiol 2016; 6:138. [PMID: 27857935 PMCID: PMC5093121 DOI: 10.3389/fcimb.2016.00138] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 10/07/2016] [Indexed: 11/29/2022] Open
Abstract
Upon colonization of the intestinal epithelium, the attaching and effacing (AE) pathogen Enterohemorrhagic Escherichia coli (EHEC) effaces microvilli and forms pedestal-like structures beneath the adherent bacterium. The production of one of its virulence factors, the phage-encoded Shiga toxin (Stx) results in systemic disease, including the development of renal failure. Although EHEC does not productively infect conventional mice, EHEC infection can be modeled in mice utilizing a derivative of the natural murine AE pathogen Citrobacter rodentium (CR). Gavage of mice with CR(ΦStx2dact), a C. rodentium lysogenized by a phage encoding an Stx variant with high potency in mice, features AE lesion formation on intestinal epithelium and Stx-mediated systemic disease, including renal damage. This model is somewhat limited by mouse-to-mouse variation in the course of disease, with the time to severe morbidity (and required euthanasia) varying by as many as 5 days, a feature that limits pathological analysis at defined stages of disease. In the current study, we altered and optimized the preparation, dose, and mode of delivery of CR(ΦStx2dact), using food-borne route of infection to generate highly synchronous disease model. We found that food-borne inoculation of as few as 3 × 104 CR(ΦStx2dact) resulted in productive colonization and severe systemic disease. Upon inoculation of 1 × 108 bacteria, the majority of infected animals suffered weight loss beginning 5 days post-infection and all required euthanasia on day 6 or 7. This enhanced murine model for EHEC infection should facilitate characterization of the pathology associated with specific phases of Stx-mediated disease.
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Affiliation(s)
- Laurice J Flowers
- Molecular Biology and Microbiology, Sackler School of Graduate Biomedical Sciences, Tufts University Boston, MA, USA
| | - Elsa N Bou Ghanem
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine Boston, MA, USA
| | - John M Leong
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine Boston, MA, USA
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10
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Abstract
Gnotobiotic (GN) rodent models have provided insight into the contributions of the gut microbiota to host health and preventing disease. However, rodent models are limited by several important physiological and metabolic differences from humans, and many rodent models do not dependably replicate the clinical manifestations of human diseases. Due to the high degree of similarity in anatomy, physiology, immunology and brain growth, the domestic pig (Sus scrofa) is considered a clinically relevant model to study factors influencing human gastrointestinal, immune, and brain development. Gnotobiotic piglet models have been developed and shown to recapitulate key aspects of GN rodent models. Human microbiota-associated (HMA) piglets have been established using inocula from infants, children, and adults. The gut microbiota of recipient HMA piglets was more similar to that of the human donor than that of conventionally reared piglets harboring a pig microbiota. Moreover, Bifidobacterium and Bacteroides, two predominant bacterial groups of infant gut, were successfully established in the HMA piglets. Thus, the HMA pig model has the potential to be a valuable model for investigating how the gut microbiota composition changes in response to environmental factors, such as age, diet, vaccination, antibiotic use and infection. The HMA also represents a robust model for screening the efficacy of pre- and probiotic interventions. Lastly, HMA piglets can be an ideal model with which to elucidate microbe-host interactions in human health and disease due to the similarities to humans in anatomy, physiology, developmental maturity at birth, and the pathophysiology of many human diseases.
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Affiliation(s)
- Mei Wang
- Mei Wang, PhD, is a research specialist and Sharon M. Donovan, PhD, RD, is a professor in the Department of Food Science & Human Nutrition, University of Illinois, Urbana, Illinois
| | - Sharon M Donovan
- Mei Wang, PhD, is a research specialist and Sharon M. Donovan, PhD, RD, is a professor in the Department of Food Science & Human Nutrition, University of Illinois, Urbana, Illinois
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11
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The Locus of Enterocyte Effacement and Associated Virulence Factors of Enterohemorrhagic Escherichia coli. Microbiol Spectr 2016; 2:EHEC-0007-2013. [PMID: 26104209 DOI: 10.1128/microbiolspec.ehec-0007-2013] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A subset of Shiga toxin-producing Escherichia coli strains, termed enterohemorrhagic E. coli (EHEC), is defined in part by the ability to produce attaching and effacing (A/E) lesions on intestinal epithelia. Such lesions are characterized by intimate bacterial attachment to the apical surface of enterocytes, cytoskeletal rearrangements beneath adherent bacteria, and destruction of proximal microvilli. A/E lesion formation requires the locus of enterocyte effacement (LEE), which encodes a Type III secretion system that injects bacterial proteins into host cells. The translocated proteins, termed effectors, subvert a plethora of cellular pathways to the benefit of the pathogen, for example, by recruiting cytoskeletal proteins, disrupting epithelial barrier integrity, and interfering with the induction of inflammation, phagocytosis, and apoptosis. The LEE and selected effectors play pivotal roles in intestinal persistence and virulence of EHEC, and it is becoming clear that effectors may act in redundant, synergistic, and antagonistic ways during infection. Vaccines that target the function of the Type III secretion system limit colonization of reservoir hosts by EHEC and may thus aid control of zoonotic infections. Here we review the features and functions of the LEE-encoded Type III secretion system and associated effectors of E. coli O157:H7 and other Shiga toxin-producing E. coli strains.
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12
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Schomberg DT, Tellez A, Meudt JJ, Brady DA, Dillon KN, Arowolo FK, Wicks J, Rousselle SD, Shanmuganayagam D. Miniature Swine for Preclinical Modeling of Complexities of Human Disease for Translational Scientific Discovery and Accelerated Development of Therapies and Medical Devices. Toxicol Pathol 2016; 44:299-314. [DOI: 10.1177/0192623315618292] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Noncommunicable diseases, including cardiovascular disease, diabetes, chronic respiratory disease, and cancer, are the leading cause of death in the world. The cost, both monetary and time, of developing therapies to prevent, treat, or manage these diseases has become unsustainable. A contributing factor is inefficient and ineffective preclinical research, in which the animal models utilized do not replicate the complex physiology that influences disease. An ideal preclinical animal model is one that responds similarly to intrinsic and extrinsic influences, providing high translatability and concordance of preclinical findings to humans. The overwhelming genetic, anatomical, physiological, and pathophysiological similarities to humans make miniature swine an ideal model for preclinical studies of human disease. Additionally, recent development of precision gene-editing tools for creation of novel genetic swine models allows the modeling of highly complex pathophysiology and comorbidities. As such, the utilization of swine models in early research allows for the evaluation of novel drug and technology efficacy while encouraging redesign and refinement before committing to clinical testing. This review highlights the appropriateness of the miniature swine for modeling complex physiologic systems, presenting it as a highly translational preclinical platform to validate efficacy and safety of therapies and devices.
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Affiliation(s)
- Dominic T. Schomberg
- Biomedical & Genomic Research Group, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | | | - Jennifer J. Meudt
- Biomedical & Genomic Research Group, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | | | | | - Folagbayi K. Arowolo
- Biomedical & Genomic Research Group, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Joan Wicks
- Alizée Pathology, LLC, Thurmont, Maryland, USA
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Smith AD, Yan X, Chen C, Dawson HD, Bhagwat AA. Understanding the host-adapted state of Citrobacter rodentium by transcriptomic analysis. Arch Microbiol 2016; 198:353-62. [PMID: 26837900 DOI: 10.1007/s00203-016-1191-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/17/2015] [Accepted: 01/12/2016] [Indexed: 12/18/2022]
Abstract
Citrobacter rodentium (Cr) is a mouse pathogen that mimics many aspects of enteropathogenic Escherichia coli infections including producing attaching and effacing (A/E) lesions. Host-adapted (HA) Cr cells that are shed at the peak of infection have been reported to be hyper-infective. The exact mechanism underlying this phenomenon has remained elusive since the pathogen loses its HA 'status' immediately upon subculturing in laboratory media. We sequenced the entire transcriptome of Cr directly from the feces of infected mice and analyzed the gene expression pattern. We observed that the entire transcriptional machinery as well as several transcriptional regulators to be differentially expressed when compared with the transcriptome of cells grown on laboratory media. Major adhesion and effector genes, tir and eae, were highly expressed in HA along with many genes located on all five loci of enterocyte effacement regions (LEE 1-5). Notable absent among the HA expressed genes were 19 fimbrial operons and non-fimbrial adhesions and several non-LEE encoded effectors. These results demonstrate that host-adapted Cr has a unique transcriptome that is associated with increased host transmission.
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Affiliation(s)
- Allen D Smith
- Diet, Genomics and Immunology Laboratory, Beltsville Human Nutrition Research Center, USDA-ARS, 10300 Baltimore Ave., B307C, Rm. 228, BARC-E, Beltsville, MD, 20705, USA.
| | - Xianghe Yan
- Environmental, Microbial, and Food Safety Laboratory, Beltsville Agriculture Research Center, USDA-ARS, Beltsville, MD, USA
| | - Celine Chen
- Diet, Genomics and Immunology Laboratory, Beltsville Human Nutrition Research Center, USDA-ARS, 10300 Baltimore Ave., B307C, Rm. 228, BARC-E, Beltsville, MD, 20705, USA
| | - Harry D Dawson
- Diet, Genomics and Immunology Laboratory, Beltsville Human Nutrition Research Center, USDA-ARS, 10300 Baltimore Ave., B307C, Rm. 228, BARC-E, Beltsville, MD, 20705, USA
| | - Arvind A Bhagwat
- Environmental, Microbial, and Food Safety Laboratory, Beltsville Agriculture Research Center, USDA-ARS, Beltsville, MD, USA
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Alteration of the Microbiota and Virulence Gene Expression in E. coli O157:H7 in Pig Ligated Intestine with and without AE Lesions. PLoS One 2015; 10:e0130272. [PMID: 26090813 PMCID: PMC4474639 DOI: 10.1371/journal.pone.0130272] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 05/19/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Previously we found that E. coli O157:H7 inoculated into ligated pig intestine formed attaching and effacing (AE) lesions in some pigs but not in others. The present study evaluated changes in the microbial community and in virulence gene expression in E. coli O157:H7 in ligated pig intestine in which the bacteria formed AE lesions or failed to form AE lesions. METHODOLOGY/PRINCIPAL FINDINGS The intestinal microbiota was assessed by RNA-based denaturing gradient gel electrophoresis (DGGE) analysis. The DGGE banding patterns showed distinct differences involving two bands which had increased intensity specifically in AE-negative pigs (AE- bands) and several bands which were more abundant in AE-positive pigs. Sequence analysis revealed that the two AE- bands belonged to Veillonella caviae, a species with probiotic properties, and Bacteroides sp. Concurrent with the differences in microbiota, gene expression analysis by quantitative PCR showed that, compared with AE negative pigs, E. coli O157:H7 in AE positive pigs had upregulated genes for putative adhesins, non-LEE encoded nleA and quorum sensing qseF, acid resistance gene ureD, and genes from the locus of enterocyte effacement (LEE). CONCLUSIONS/SIGNIFICANCE The present study demonstrated that AE-positive pigs had reduced activities or populations of Veillonella caviae and Bacterioides sp. compared with AE-negative pigs. Further studies are required to understand how the microbiota was changed and the role of these organisms in the control of E. coli O157:H7.
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15
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Mair KH, Sedlak C, Käser T, Pasternak A, Levast B, Gerner W, Saalmüller A, Summerfield A, Gerdts V, Wilson HL, Meurens F. The porcine innate immune system: an update. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 45:321-43. [PMID: 24709051 PMCID: PMC7103209 DOI: 10.1016/j.dci.2014.03.022] [Citation(s) in RCA: 175] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/30/2014] [Accepted: 03/31/2014] [Indexed: 05/21/2023]
Abstract
Over the last few years, we have seen an increasing interest and demand for pigs in biomedical research. Domestic pigs (Sus scrofa domesticus) are closely related to humans in terms of their anatomy, genetics, and physiology, and often are the model of choice for the assessment of novel vaccines and therapeutics in a preclinical stage. However, the pig as a model has much more to offer, and can serve as a model for many biomedical applications including aging research, medical imaging, and pharmaceutical studies to name a few. In this review, we will provide an overview of the innate immune system in pigs, describe its anatomical and physiological key features, and discuss the key players involved. In particular, we compare the porcine innate immune system to that of humans, and emphasize on the importance of the pig as model for human disease.
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Affiliation(s)
- K H Mair
- Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - C Sedlak
- Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - T Käser
- Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada
| | - A Pasternak
- Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada
| | - B Levast
- Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada
| | - W Gerner
- Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - A Saalmüller
- Institute of Immunology, Department of Pathobiology, University of Veterinary Medicine Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - A Summerfield
- Institute of Virology and Immunoprophylaxis (IVI), Sensemattstrasse 293, 3147 Mittelhäusern, Switzerland
| | - V Gerdts
- Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada
| | - H L Wilson
- Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada
| | - F Meurens
- Vaccine and Infectious Disease Organization-International Vaccine Centre (VIDO-InterVac), University of Saskatchewan, 120 Veterinary Road, S7N 5E3 Saskatoon, Saskatchewan, Canada.
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16
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Actin pedestal formation by enterohemorrhagic Escherichia coli enhances bacterial host cell attachment and concomitant type III translocation. Infect Immun 2014; 82:3713-22. [PMID: 24958711 DOI: 10.1128/iai.01523-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Attachment of enterohemorrhagic Escherichia coli (EHEC) to intestinal epithelial cells is critical for colonization and is associated with localized actin assembly beneath bound bacteria. The formation of these actin "pedestals" is dependent on the translocation of effectors into mammalian cells via a type III secretion system (T3SS). Tir, an effector required for pedestal formation, localizes in the host cell plasma membrane and promotes attachment of bacteria to mammalian cells by binding to the EHEC outer surface protein Intimin. Actin pedestal formation has been shown to foster intestinal colonization by EHEC in some animal models, but the mechanisms responsible for this remain undefined. Investigation of the role of Tir-mediated actin assembly promoting host cell binding is complicated by other, potentially redundant EHEC-encoded binding pathways, so we utilized cell binding assays that specifically detect binding mediated by Tir-Intimin interaction. We also assessed the role of Tir-mediated actin assembly in two-step assays that temporally segregated initial translocation of Tir from subsequent Tir-Intimin interaction, thereby permitting the distinction of effects on translocation from effects on cell attachment. In these experimental systems, we compromised Tir-mediated actin assembly by chemically inhibiting actin assembly or by infecting mammalian cells with EHEC mutants that translocate Tir but are specifically defective in Tir-mediated pedestal formation. We found that an inability of Tir to promote actin assembly resulted in a significant and striking decrease in bacterial binding mediated by Tir and Intimin. Bacterial mutants defective for pedestal formation translocated type III effectors to mammalian cells with reduced efficiency, but the decrease in translocation could be entirely accounted for by the decrease in host cell attachment.
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17
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Chagnot C, Zorgani MA, Astruc T, Desvaux M. Proteinaceous determinants of surface colonization in bacteria: bacterial adhesion and biofilm formation from a protein secretion perspective. Front Microbiol 2013; 4:303. [PMID: 24133488 PMCID: PMC3796261 DOI: 10.3389/fmicb.2013.00303] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/22/2013] [Indexed: 01/30/2023] Open
Abstract
Bacterial colonization of biotic or abiotic surfaces results from two quite distinct physiological processes, namely bacterial adhesion and biofilm formation. Broadly speaking, a biofilm is defined as the sessile development of microbial cells. Biofilm formation arises following bacterial adhesion but not all single bacterial cells adhering reversibly or irreversibly engage inexorably into a sessile mode of growth. Among molecular determinants promoting bacterial colonization, surface proteins are the most functionally diverse active components. To be present on the bacterial cell surface, though, a protein must be secreted in the first place. Considering the close association of secreted proteins with their cognate secretion systems, the secretome (which refers both to the secretion systems and their protein substrates) is a key concept to apprehend the protein secretion and related physiological functions. The protein secretion systems are here considered in light of the differences in the cell-envelope architecture between diderm-LPS (archetypal Gram-negative), monoderm (archetypal Gram-positive) and diderm-mycolate (archetypal acid-fast) bacteria. Besides, their cognate secreted proteins engaged in the bacterial colonization process are regarded from single protein to supramolecular protein structure as well as the non-classical protein secretion. This state-of-the-art on the complement of the secretome (the secretion systems and their cognate effectors) involved in the surface colonization process in diderm-LPS and monoderm bacteria paves the way for future research directions in the field.
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Affiliation(s)
- Caroline Chagnot
- UR454 Microbiologie, INRA Saint-Genès Champanelle, France ; UR370 Qualité des Produits Animaux, INRA Saint-Genès Champanelle, France
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18
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Abstract
Easy access to next generation sequencing has enabled the rapid analysis of complex microbial populations. To take full advantage of these technologies, animal models enabling the manipulation of human microbiomes and the study of the impact of such perturbations on the host are needed. To this aim we are developing experimentally tractable and clinically relevant pig models of the human adult and infant gastro-intestinal tract. The intestine of germ-free piglets was populated with human adult or infant fecal microbial populations, and the piglets were maintained on solid or milk diet, respectively. Amplicons of 16S rRNA V6 region were deep-sequenced to monitor to what extent the transplanted human microbiomes changed in the pig. Within 24 h of transfer of human fecal microbiome to pigs, bacterial microbiomes rich in Proteobacteria emerged. These populations evolved toward a more diverse composition rich in Bacteroidetes and Firmicutes. In the experiment where infant microbiome was used, the phylogenetic composition of the transplanted bacterial population converged toward that of the human inoculum. A majority of sequences belonged to a relatively small number of operational taxonomic units, whereas at the other end of the abundance spectrum, a large number of rare and transient OTUs were detected. Analysis of fecal and colonic microbiomes originating from the same animal indicate that feces closely replicate the colonic microbiome. We conclude that the pig intestine can be colonized with human fecal microbiomes to generate a realistic model of the human GI tract.
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19
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Hartland EL, Leong JM. Enteropathogenic and enterohemorrhagic E. coli: ecology, pathogenesis, and evolution. Front Cell Infect Microbiol 2013; 3:15. [PMID: 23641365 PMCID: PMC3639409 DOI: 10.3389/fcimb.2013.00015] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 04/13/2013] [Indexed: 11/13/2022] Open
Affiliation(s)
- Elizabeth L. Hartland
- Department of Microbiology and Immunology, University of MelbourneParkville, VIC, Australia
- Murdoch Children's Research Institute, Royal Children's HospitalParkville, VIC, Australia
- *Correspondence:
| | - John M. Leong
- Department of Molecular Biology and Microbiology, Tufts University School of MedicineBoston, MA, USA
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20
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Stearns-Kurosawa DJ, Oh SY, Cherla RP, Lee MS, Tesh VL, Papin J, Henderson J, Kurosawa S. Distinct renal pathology and a chemotactic phenotype after enterohemorrhagic Escherichia coli shiga toxins in non-human primate models of hemolytic uremic syndrome. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 182:1227-38. [PMID: 23402998 PMCID: PMC3620421 DOI: 10.1016/j.ajpath.2012.12.026] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 12/13/2012] [Accepted: 12/24/2012] [Indexed: 12/31/2022]
Abstract
Enterohemorrhagic Escherichia coli cause approximately 1.5 million infections globally with 176,000 cases occurring in the United States annually from ingesting contaminated food, most frequently E. coli O157:H7 in ground beef or fresh produce. In severe cases, the painful prodromal hemorrhagic colitis is complicated by potentially lethal hemolytic uremic syndrome (HUS), particularly in children. Bacterial Shiga-like toxins (Stx1, Stx2) are primarily responsible for HUS and the kidney and neurologic damage that ensue. Small animal models are hampered by the inability to reproduce HUS with thrombotic microangiopathy, hemolytic anemia, and acute kidney injury. Earlier, we showed that nonhuman primates (Papio) recapitulated clinical HUS after Stx challenge and that novel therapeutic intervention rescued the animals. Here, we present detailed light and electron microscopic pathology examination of the kidneys from these Stx studies. Stx1 challenge resulted in more severe glomerular endothelial injury, whereas the glomerular injury after Stx2 also included prominent mesangiolysis and an eosinophilic inflammatory infiltration. Both toxins induced glomerular platelet-rich thrombi, interstitial hemorrhage, and tubular injury. Analysis of kidney and other organs for inflammation biomarkers showed a striking chemotactic profile, with extremely high mRNA levels for IL-8, monocyte chemoattractant protein 1, and macrophage inflammatory protein 1α and elevated urine chemokines at 48 hours after challenge. These observations give unique insight into the pathologic consequences of each toxin in a near human setting and present potential pathways for therapeutic intervention.
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Affiliation(s)
- Deborah J. Stearns-Kurosawa
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts
| | - Sun-Young Oh
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts
| | - Rama P. Cherla
- Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, Bryan, Texas
| | - Moo-Seung Lee
- Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, Bryan, Texas
| | - Vernon L. Tesh
- Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center, Bryan, Texas
| | - James Papin
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts
| | - Joel Henderson
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts
| | - Shinichiro Kurosawa
- Department of Pathology and Laboratory Medicine, Boston University School of Medicine, Boston, Massachusetts
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21
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Chagnot C, Agus A, Renier S, Peyrin F, Talon R, Astruc T, Desvaux M. In vitro colonization of the muscle extracellular matrix components by Escherichia coli O157:H7: the influence of growth medium, temperature and pH on initial adhesion and induction of biofilm formation by collagens I and III. PLoS One 2013; 8:e59386. [PMID: 23516631 PMCID: PMC3596346 DOI: 10.1371/journal.pone.0059386] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 02/14/2013] [Indexed: 11/18/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 are responsible for repeated food-poisoning cases often caused by contaminated burgers. EHEC infection is predominantly a pediatric illness, which can lead to life-threatening diseases. Ruminants are the main natural reservoir for EHEC and food contamination almost always originates from faecal contamination. In beef meat products, primary bacterial contamination occurs at the dehiding stage of slaughtering. The extracellular matrix (ECM) is the most exposed part of the skeletal muscles in beef carcasses. Investigating the adhesion to the main muscle fibrous ECM proteins, insoluble fibronectin, collagen I, III and IV, laminin-α2 and elastin, results demonstrated that the preceding growth conditions had a great influence on subsequent bacterial attachment. In the tested experimental conditions, maximal adhesion to fibril-forming collagens I or III occurred at 25°C and pH 7. Once initially adhered, exposure to lower temperatures, as applied to meat during cutting and storage, or acidification, as in the course of post-mortem physiological modifications of muscle, had no effect on detachment, except at pHu. In addition, dense biofilm formation occurred on immobilized collagen I or III and was induced in growth medium supplemented with collagen I in solution. From this first comprehensive investigation of EHEC adhesion to ECM proteins with respect to muscle biology and meat processing, new research directions for the development of innovative practices to minimize the risk of meat contamination are further discussed.
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Affiliation(s)
- Caroline Chagnot
- INRA, UR454 Microbiologie, Clermont-Ferrand, France
- INRA, UR370 Qualité des Produits Animaux, Clermont-Ferrand, France
| | - Allison Agus
- INRA, UR454 Microbiologie, Clermont-Ferrand, France
| | | | - Frédéric Peyrin
- INRA, UR370 Qualité des Produits Animaux, Clermont-Ferrand, France
| | - Régine Talon
- INRA, UR454 Microbiologie, Clermont-Ferrand, France
| | - Thierry Astruc
- INRA, UR370 Qualité des Produits Animaux, Clermont-Ferrand, France
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22
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Mallick EM, Brady MJ, Luperchio SA, Vanguri VK, Magoun L, Liu H, Sheppard BJ, Mukherjee J, Donohue-Rolfe A, Tzipori S, Leong JM, Schauer DB. Allele- and tir-independent functions of intimin in diverse animal infection models. Front Microbiol 2012; 3:11. [PMID: 22347213 PMCID: PMC3269026 DOI: 10.3389/fmicb.2012.00011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 01/07/2012] [Indexed: 11/16/2022] Open
Abstract
Upon binding to intestinal epithelial cells, enterohemorrhagic Escherichia coli (EHEC), enteropathogenic E. coli (EPEC), and Citrobacter rodentium trigger formation of actin pedestals beneath bound bacteria. Pedestal formation has been associated with enhanced colonization, and requires intimin, an adhesin that binds to the bacterial effector translocated intimin receptor (Tir), which is translocated to the host cell membrane and promotes bacterial adherence and pedestal formation. Intimin has been suggested to also promote cell adhesion by binding one or more host receptors, and allelic differences in intimin have been associated with differences in tissue and host specificity. We assessed the function of EHEC, EPEC, or C. rodentium intimin, or a set of intimin derivatives with varying Tir-binding abilities in animal models of infection. We found that EPEC and EHEC intimin were functionally indistinguishable during infection of gnotobiotic piglets by EHEC, and that EPEC, EHEC, and C. rodentium intimin were functionally indistinguishable during infection of C57BL/6 mice by C. rodentium. A derivative of EHEC intimin that bound Tir but did not promote robust pedestal formation on cultured cells was unable to promote C. rodentium colonization of conventional mice, indicating that the ability to trigger actin assembly, not simply to bind Tir, is required for intimin-mediated intestinal colonization. Interestingly, streptomycin pre-treatment of mice eliminated the requirement for Tir but not intimin during colonization, and intimin derivatives that were defective in Tir-binding still promoted colonization of these mice. These results indicate that EPEC, EHEC, and C. rodentium intimin are functionally interchangeable during infection of gnotobiotic piglets or conventional C57BL/6 mice, and that whereas the ability to trigger Tir-mediated pedestal formation is essential for colonization of conventional mice, intimin provides a Tir-independent activity during colonization of streptomycin pre-treated mice.
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Affiliation(s)
- Emily M Mallick
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School Worcester, MA, USA
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Lai Y, Riley K, Cai A, Leong JM, Herman IM. Calpain mediates epithelial cell microvillar effacement by enterohemorrhagic Escherichia coli. Front Microbiol 2011; 2:222. [PMID: 22073041 PMCID: PMC3210503 DOI: 10.3389/fmicb.2011.00222] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 10/20/2011] [Indexed: 11/13/2022] Open
Abstract
A member of the attaching and effacing (AE) family of pathogens, enterohemorrhagic Escherichia coli (EHEC) induces dramatic changes to the intestinal cell cytoskeleton, including effacement of microvilli. Effacement by the related pathogen enteropathogenic E. coli (EPEC) requires the activity of the Ca+2-dependent host protease, calpain, which participates in a variety of cellular processes, including cell adhesion and motility. We found that EHEC infection results in an increase in epithelial (CaCo-2a) cell calpain activity and that EHEC-induced microvillar effacement was blocked by ectopic expression of calpastatin, an endogenous calpain inhibitor, or by pretreatment of intestinal cells with a cell-penetrating version of calpastatin. In addition, ezrin, a known calpain substrate that links the plasma membrane to axial actin filaments in microvilli, was cleaved in a calpain-dependent manner during EHEC infection and lost from its normal locale within microvilli. Calpain may be a central conduit through which EHEC and other AE pathogens induce enterocyte cytoskeletal remodeling and exert their pathogenic effects.
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Affiliation(s)
- Yushuan Lai
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School Worcester, MA, USA
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