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Campbell C, Kandalgaonkar MR, Golonka RM, Yeoh BS, Vijay-Kumar M, Saha P. Crosstalk between Gut Microbiota and Host Immunity: Impact on Inflammation and Immunotherapy. Biomedicines 2023; 11:294. [PMID: 36830830 PMCID: PMC9953403 DOI: 10.3390/biomedicines11020294] [Citation(s) in RCA: 31] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 01/09/2023] [Accepted: 01/18/2023] [Indexed: 01/26/2023] Open
Abstract
Gut microbes and their metabolites are actively involved in the development and regulation of host immunity, which can influence disease susceptibility. Herein, we review the most recent research advancements in the gut microbiota-immune axis. We discuss in detail how the gut microbiota is a tipping point for neonatal immune development as indicated by newly uncovered phenomenon, such as maternal imprinting, in utero intestinal metabolome, and weaning reaction. We describe how the gut microbiota shapes both innate and adaptive immunity with emphasis on the metabolites short-chain fatty acids and secondary bile acids. We also comprehensively delineate how disruption in the microbiota-immune axis results in immune-mediated diseases, such as gastrointestinal infections, inflammatory bowel diseases, cardiometabolic disorders (e.g., cardiovascular diseases, diabetes, and hypertension), autoimmunity (e.g., rheumatoid arthritis), hypersensitivity (e.g., asthma and allergies), psychological disorders (e.g., anxiety), and cancer (e.g., colorectal and hepatic). We further encompass the role of fecal microbiota transplantation, probiotics, prebiotics, and dietary polyphenols in reshaping the gut microbiota and their therapeutic potential. Continuing, we examine how the gut microbiota modulates immune therapies, including immune checkpoint inhibitors, JAK inhibitors, and anti-TNF therapies. We lastly mention the current challenges in metagenomics, germ-free models, and microbiota recapitulation to a achieve fundamental understanding for how gut microbiota regulates immunity. Altogether, this review proposes improving immunotherapy efficacy from the perspective of microbiome-targeted interventions.
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Affiliation(s)
- Connor Campbell
- Department of Physiology & Pharmacology, University of Toledo College of Medicine, Toledo, OH 43614, USA
| | - Mrunmayee R. Kandalgaonkar
- Department of Physiology & Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
| | - Rachel M. Golonka
- Department of Physiology & Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
| | - Beng San Yeoh
- Department of Physiology & Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
| | - Matam Vijay-Kumar
- Department of Physiology & Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
| | - Piu Saha
- Department of Physiology & Pharmacology, University of Toledo College of Medicine and Life Sciences, Toledo, OH 43614, USA
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Aksoyalp ZŞ, Temel A, Erdogan BR. Iron in infectious diseases friend or foe?: The role of gut microbiota. J Trace Elem Med Biol 2023; 75:127093. [PMID: 36240616 DOI: 10.1016/j.jtemb.2022.127093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 09/13/2022] [Accepted: 10/05/2022] [Indexed: 12/07/2022]
Abstract
Iron is a trace element involved in metabolic functions for all organisms, from microorganisms to mammalians. Iron deficiency is a prevalent health problem that affects billions of people worldwide, and iron overload could have some hazardous effect. The complex microbial community in the human body, also called microbiota, influences the host immune defence against infections. An imbalance in gut microbiota, dysbiosis, changes the host's susceptibility to infections by regulating the immune system. In recent years, the number of studies on the relationship between infectious diseases and microbiota has increased. Gut microbiota is affected by different parameters, including mode of delivery, hygiene habits, diet, drugs, and plasma iron levels during the lifetime. Gut microbiota may influence iron levels in the body, and iron overload and deficiency can also affect gut microbiota composition. Novel researches on microbiota shed light on the fact that the bidirectional interactions between gut microbiota and iron play a role in the pathogenesis of many diseases, especially infections. A better understanding of these interactions may help us to comprehend the pathogenesis of many infectious and metabolic diseases affecting people worldwide and following the development of more effective preventive and/or therapeutic strategies. In this review, we aimed to present the iron-mediated host-gut microbiota interactions, susceptibility to bacterial infections, and iron-targeted therapy approaches for infections.
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Affiliation(s)
- Zinnet Şevval Aksoyalp
- Izmir Katip Celebi University, Faculty of Pharmacy, Department of Pharmacology, Izmir, Turkey.
| | - Aybala Temel
- Izmir Katip Celebi University, Faculty of Pharmacy, Department of Pharmaceutical Microbiology, Izmir, Turkey.
| | - Betul Rabia Erdogan
- Izmir Katip Celebi University, Faculty of Pharmacy, Department of Pharmacology, Izmir, Turkey.
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Henrot C, Petit M. Signals triggering prophage induction in the gut microbiota. Mol Microbiol 2022; 118:494-502. [PMID: 36164818 PMCID: PMC9827884 DOI: 10.1111/mmi.14983] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/15/2022] [Accepted: 09/18/2022] [Indexed: 01/12/2023]
Abstract
Compared to bacteria of the gut microbiota, bacteriophages are still poorly characterised, and their physiological importance is far less known. Temperate phages are probably a major actor in the gut, as it is estimated that 80% of intestinal bacteria are lysogens, meaning that they are carrying prophages. In addition, prophage induction rates are higher in the gut than in vitro. However, studies on the signals leading to prophage induction have essentially focused on genotoxic agents with poor relevance for this environment. In this review, we sum up recent findings about signals able to trigger prophage induction in the gut. Three categories of signals are at play: those originating from interactions between intestinal microbes, those from the human or animal host physiology and those from external intakes. These recent results highlight the diversity of factors influencing prophage induction in the gut, and start to unveil ways by which microbiota composition may be modulated.
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Affiliation(s)
- Caroline Henrot
- Université Paris‐Saclay, INRAEAgroParisTech, Micalis InstituteJouy‐en‐JosasFrance,Master de Biologie, École Normale Supérieure de Lyon, Université Claude Bernard Lyon 1Université de LyonLyonFrance
| | - Marie‐Agnès Petit
- Université Paris‐Saclay, INRAEAgroParisTech, Micalis InstituteJouy‐en‐JosasFrance
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Izquierdo M, Lopez J, Gallardo P, Vidal RM, Ossa JC, Farfan MJ. Bacteria from gut microbiota associated with diarrheal infections in children promote virulence of Shiga toxin-producing and enteroaggregative Escherichia coli pathotypes. Front Cell Infect Microbiol 2022; 12:867205. [PMID: 36017363 PMCID: PMC9396624 DOI: 10.3389/fcimb.2022.867205] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 07/07/2022] [Indexed: 11/26/2022] Open
Abstract
Background Diarrheagenic E. coli (DEC) pathogenicity relies on the interaction of bacteria with the host’s gut environment, which is regulated by the resident microbiota. Previously, we identified indicative bacterial species of gut microbiota in DEC-positive stool samples from children. Here, we evaluated the role of two indicative species, Citrobacter werkmanii (CW) and Escherichia albertii (EA), in the virulence of two DEC pathotypes, Shiga toxin-producing (STEC) and enteroaggregative (EAEC) Escherichia coli. Methods We determined the effect of supernatants obtained from CW and EA cultures on the gene expression of STEC strain 86-24 and EAEC strain 042 by RNA-seq analysis. We evaluated IL-8 secretion from T84 cells infected with these DEC strains in the presence or absence of the supernatant from EA. The effect of the supernatant from EA on the growth and adherence of STEC and EAEC to cells was also evaluated. Finally, we studied the effect of the EA supernatant on the STEC-induced inflammation mediated by the long polar fimbriae (Lpf) in T84 cells and the expression of plasmid-encoded toxin (Pet) in EAEC. Results RNA-seq analysis revealed that several virulence factors in STEC and EAEC were upregulated in the presence of supernatants from CW and EA. Interestingly, an increase in the secretion of IL-8 was observed in cells infected with STEC or EAEC in the presence of a supernatant from EA. Similar results were observed with the supernatants obtained from clinical strains of E. albertii. The supernatant from EA had no effect on the growth of STEC and EAEC, or on the ability of these DEC strains to adhere to cells. We found that Pet toxin in EAEC was upregulated in the presence of a supernatant from EA. In STEC, using mutant strains for Lpf fimbriae, our data suggested that these fimbriae might be participating in the increase in IL-8 induced by STEC in cells in the presence of a supernatant from EA. Conclusion Supernatant obtained from an indicative species of DEC-positive diarrhea could modulate gene expression in STEC and EAEC, and IL-8 secretion induced by these bacteria. These data provide new insights into the effect of gut microbiota species in the pathogenicity of STEC and EAEC.
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Affiliation(s)
- Mariana Izquierdo
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Joaquín Lopez
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Pablo Gallardo
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Roberto M. Vidal
- Programa de Microbiología y Micología, Instituto de Ciencias Biomédicas, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Juan C. Ossa
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
| | - Mauricio J. Farfan
- Departamento de Pediatría y Cirugía Infantil, Facultad de Medicina, Universidad de Chile, Santiago, Chile
- *Correspondence: Mauricio J. Farfan,
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AB 5 Enterotoxin-Mediated Pathogenesis: Perspectives Gleaned from Shiga Toxins. Toxins (Basel) 2022; 14:toxins14010062. [PMID: 35051039 PMCID: PMC8779504 DOI: 10.3390/toxins14010062] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/12/2022] [Accepted: 01/12/2022] [Indexed: 02/01/2023] Open
Abstract
Foodborne diseases affect an estimated 600 million people worldwide annually, with the majority of these illnesses caused by Norovirus, Vibrio, Listeria, Campylobacter, Salmonella, and Escherichia coli. To elicit infections in humans, bacterial pathogens express a combination of virulence factors and toxins. AB5 toxins are an example of such toxins that can cause various clinical manifestations, including dehydration, diarrhea, kidney damage, hemorrhagic colitis, and hemolytic uremic syndrome (HUS). Treatment of most bacterial foodborne illnesses consists of fluid replacement and antibiotics. However, antibiotics are not recommended for infections caused by Shiga toxin-producing E. coli (STEC) because of the increased risk of HUS development, although there are conflicting views and results in this regard. Lack of effective treatment strategies for STEC infections pose a public health threat during outbreaks; therefore, the debate on antibiotic use for STEC infections could be further explored, along with investigations into antibiotic alternatives. The overall goal of this review is to provide a succinct summary on the mechanisms of action and the pathogenesis of AB5 and related toxins, as expressed by bacterial foodborne pathogens, with a primary focus on Shiga toxins (Stx). The role of Stx in human STEC disease, detection methodologies, and available treatment options are also briefly discussed.
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Mcc1229, an Stx2a-amplifying microcin, is produced in vivo and requires CirA for activity. Infect Immun 2021; 90:e0058721. [PMID: 34871041 PMCID: PMC8853679 DOI: 10.1128/iai.00587-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) strains, including the foodborne pathogen E. coli O157:H7, are responsible for thousands of hospitalizations each year. Various environmental triggers can modulate pathogenicity in EHEC by inducing the expression of Shiga toxin (Stx), which is encoded on a lambdoid prophage and transcribed together with phage late genes. Cell-free supernatants of the sequence type 73 (ST73) E. coli strain 0.1229 are potent inducers of Stx2a production in EHEC, suggesting that 0.1229 secretes a factor that activates the SOS response and leads to phage lysis. We previously demonstrated that this factor, designated microcin 1229 (Mcc1229), was proteinaceous and plasmid-encoded. To further characterize Mcc1229 and support its classification as a microcin, we investigated its regulation, determined its receptor, and identified loci providing immunity. The production of Mcc1229 was increased upon iron limitation, as determined by an enzyme-linked immunosorbent assay (ELISA), lacZ fusions, and quantitative real-time PCR (qRT-PCR). Spontaneous Mcc1229-resistant mutants and targeted gene deletion revealed that CirA was the Mcc1229 receptor. TonB, which interacts with CirA in the periplasm, was also essential for Mcc1229 import. Subcloning of the Mcc1229 plasmid indicated that Mcc activity was neutralized by two open reading frames (ORFs), each predicted to encode a domain of unknown function (DUF)-containing protein. In a germfree mouse model of infection, colonization with 0.1229 suppressed subsequent colonization by EHEC. Although Mcc1229 was produced in vivo, it was dispensable for colonization suppression. The regulation, import, and immunity determinants identified here are consistent with features of other Mccs, suggesting that Mcc1229 should be included in this class of small molecules.
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Béchon N, Ghigo JM. Gut biofilms: Bacteroides as model symbionts to study biofilm formation by intestinal anaerobes. FEMS Microbiol Rev 2021; 46:6440158. [PMID: 34849798 DOI: 10.1093/femsre/fuab054] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/09/2021] [Indexed: 02/06/2023] Open
Abstract
Bacterial biofilms are communities of adhering bacteria that express distinct properties compared to their free-living counterparts, including increased antibiotic tolerance and original metabolic capabilities. Despite the potential impact of the biofilm lifestyle on the stability and function of the dense community of micro-organisms constituting the mammalian gut microbiota, the overwhelming majority of studies performed on biofilm formation by gut bacteria focused either on minor and often aerobic members of the community or on pathogenic bacteria. In this review, we discuss the reported evidence for biofilm-like structures formed by gut bacteria, the importance of considering the anaerobic nature of gut biofilms and we present the most recent advances on biofilm formation by Bacteroides, one of the most abundant genera of the human gut microbiota. Bacteroides species can be found attached to food particles and colonizing the mucus layer and we propose that Bacteroides symbionts are relevant models to probe the physiology of gut microbiota biofilms.
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Affiliation(s)
- Nathalie Béchon
- Institut Pasteur, Université de Paris, UMR CNRS2001, Genetics of Biofilms Laboratory 75015 Paris, France
| | - Jean-Marc Ghigo
- Institut Pasteur, Université de Paris, UMR CNRS2001, Genetics of Biofilms Laboratory 75015 Paris, France
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Pauer H, Teixeira FL, Robinson AV, Parente TE, De Melo MAF, Lobo LA, Domingues RMCP, Allen-Vercoe E, Ferreira RBR, Antunes LCM. Bioactive small molecules produced by the human gut microbiome modulate Vibrio cholerae sessile and planktonic lifestyles. Gut Microbes 2021; 13:1-19. [PMID: 34006192 PMCID: PMC8143261 DOI: 10.1080/19490976.2021.1918993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Humans live in symbiosis with a diverse community of microorganisms, which has evolved to carry out many specific tasks that benefit the host, including protection against invading pathogens. Within the chemical diversity of the gastrointestinal tract, small molecules likely constitute chemical cues for the communication between the microbiota and pathogens. Therefore, we sought to investigate if molecules produced by the human gut microbiota show biological activity against the human pathogen Vibrio cholerae. To probe the effects of the gut metabolome on V. cholerae, we investigated its response to small-molecule extracts from human feces, from a complex bacterial community cultivated in vitro, and from culture supernatants of Enterocloster citroniae, Bacteroides thetaiotaomicron, and Bacteroides vulgatus. Using RNA sequencing, we determined the impact of the human gut metabolome on V. cholerae global gene expression. Among the genes downregulated in the presence of the fecal extract, the most overrepresented functional category was cell motility, which accounted for 39% of repressed genes. Repression of V. cholerae motility by the fecal extract was confirmed phenotypically, and E. citroniae extracts reproduced this phenotype. A complex in vitro microbial community led to increased motility, as did extracts from B. vulgatus, a species present in this community. Accordingly, mucin penetration was also repressed by fecal and E. citroniae extracts, suggesting that the phenotypes observed may have implications for host colonization. Together with previous studies, this work shows that small molecules from the gut metabolome may have a widespread, significant impact on microbe-microbe interactions established in the gut environment.
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Affiliation(s)
- Heidi Pauer
- Instituto Nacional de Ciência e Tecnologia de Inovação Em Doenças De Populações Negligenciadas, Centro De Desenvolvimento Tecnológico em Saúde, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Felipe Lopes Teixeira
- Departamento de Tecnologia Farmacêutica, Universidade Federal Fluminense, Niterói, Brazil
| | - Avery V. Robinson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Thiago E. Parente
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Marília A. F. De Melo
- Laboratório de Genômica Funcional e Bioinformática, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Leandro A. Lobo
- Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio De Janeiro, Rio de Janeiro, Brazil
| | - Regina M. C. P. Domingues
- Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio De Janeiro, Rio de Janeiro, Brazil
| | - Emma Allen-Vercoe
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Canada
| | - Rosana B. R. Ferreira
- Departamento de Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio De Janeiro, Rio de Janeiro, Brazil
| | - Luis Caetano M. Antunes
- Instituto Nacional de Ciência e Tecnologia de Inovação Em Doenças De Populações Negligenciadas, Centro De Desenvolvimento Tecnológico em Saúde, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil,Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil,Laboratório de Pesquisa Em Infecção Hospitalar, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil,CONTACT Luis Caetano Antunes Avenida Brasil, 4365, Manguinhos, Rio de Janeiro, RJ, 21040-900
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Lee KS, Jeong YJ, Lee MS. Escherichia coli Shiga Toxins and Gut Microbiota Interactions. Toxins (Basel) 2021; 13:toxins13060416. [PMID: 34208170 PMCID: PMC8230793 DOI: 10.3390/toxins13060416] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 06/03/2021] [Accepted: 06/08/2021] [Indexed: 12/19/2022] Open
Abstract
Escherichia coli (EHEC) and Shigella dysenteriae serotype 1 are enterohemorrhagic bacteria that induce hemorrhagic colitis. This, in turn, may result in potentially lethal complications, such as hemolytic uremic syndrome (HUS), which is characterized by thrombocytopenia, acute renal failure, and neurological abnormalities. Both species of bacteria produce Shiga toxins (Stxs), a phage-encoded exotoxin inhibiting protein synthesis in host cells that are primarily responsible for bacterial virulence. Although most studies have focused on the pathogenic roles of Stxs as harmful substances capable of inducing cell death and as proinflammatory factors that sensitize the host target organs to damage, less is known about the interface between the commensalism of bacterial communities and the pathogenicity of the toxins. The gut contains more species of bacteria than any other organ, providing pathogenic bacteria that colonize the gut with a greater number of opportunities to encounter other bacterial species. Notably, the presence in the intestines of pathogenic EHEC producing Stxs associated with severe illness may have compounding effects on the diversity of the indigenous bacteria and bacterial communities in the gut. The present review focuses on studies describing the roles of Stxs in the complex interactions between pathogenic Shiga toxin-producing E. coli, the resident microbiome, and host tissues. The determination of these interactions may provide insights into the unresolved issues regarding these pathogens.
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Affiliation(s)
- Kyung-Soo Lee
- Environmental Diseases Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Daejeon 34141, Korea;
- Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology (UST), 127 Gajeong-ro, Yuseong-gu, Daejeon 34113, Korea
| | - Yu-Jin Jeong
- Environmental Diseases Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Daejeon 34141, Korea;
- Correspondence: (Y.-J.J.); (M.-S.L.)
| | - Moo-Seung Lee
- Environmental Diseases Research Center, Korea Research Institute of Bioscience and Biotechnology, 125 Gwahak-ro, Daejeon 34141, Korea;
- Department of Biomolecular Science, KRIBB School of Bioscience, Korea University of Science and Technology (UST), 127 Gajeong-ro, Yuseong-gu, Daejeon 34113, Korea
- Correspondence: (Y.-J.J.); (M.-S.L.)
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A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression. Appl Environ Microbiol 2020; 86:AEM.00509-20. [PMID: 32358004 DOI: 10.1128/aem.00509-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.
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Emiola A, Zhou W, Oh J. Metagenomic growth rate inferences of strains in situ. SCIENCE ADVANCES 2020; 6:eaaz2299. [PMID: 32494636 PMCID: PMC7176420 DOI: 10.1126/sciadv.aaz2299] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 01/24/2020] [Indexed: 05/08/2023]
Abstract
We developed a method for strain-level metagenomic estimation of growth rate (SMEG) for inferring growth rates of bacterial subspecies, or strains, from complex metagenomic samples. We applied our method, which is based on both reference strains and de novo approaches, to different gut metagenomic datasets, accurately identifying an outbreak-associated Escherichia coli strain and a previously unidentified association of an Akkermansia muciniphila strain in cancer immunotherapy responders. SMEG resolves strain-specific growth rates from mixtures of commensal or pathogenic strains to provide new insights into microbial interactions and disease associations at the strain level. SMEG is available for download at https://github.com/ohlab/SMEG.
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Affiliation(s)
- Akintunde Emiola
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
| | - Wei Zhou
- The Jackson Laboratory for Genomic Medicine, Farmington, CT 06032, USA
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Koyanagi Y, Suzuki R, Ihara K, Miyagi H, Isogai H, Yoneyama H, Isogai E. Intestinal Clostridium species lower host susceptibility to enterohemorrhagic Escherichia coli O157:H7 infection. Pathog Dis 2020; 77:5538763. [PMID: 31344225 DOI: 10.1093/femspd/ftz036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 07/22/2019] [Indexed: 12/28/2022] Open
Abstract
Susceptibility to enterohemorrhagic Escherichia coli (EHEC) infection varies among humans. The intestinal microbiota seems to play an essential role in host defense against EHEC; thus, we hypothesized that indigenous bacteria, such as Clostridium ramosum and Clostridium perfringens, could influence the susceptibility to EHEC infection. To evaluate the effect of indigenous bacteria on EHEC infection, germ-free mice were precolonized with each indigenous bacterium, and then infected with EHEC O157:H7. Precolonization with C. ramosum or C. perfringens completely prevented death from EHEC infection througout a test period. Precolonization with C. ramosum also reduced the level of secreted Shiga toxin (Stx) 2 and prevented histopathological changes in the kidneys in a similar way to precolonization with Bifidobacterium longum, which is used as a model for preventing EHEC infection. In contrast, the mice precolonized with C. perfringens showed mild renal injuries. When evaluated using an in vitro co-culturing system, again C. ramosum inhibited the growth and Stx production of EHEC more potently than C. perfringens. These results indicate that C. ramosum and C. perfringens suppressed EHEC infection; however, the extent of their preventive effects differed. Therefore, the susceptibility to EHEC infection and its severity can depend on the functional bacteria present in the intestinal microbiota of individuals.
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Affiliation(s)
- Yukako Koyanagi
- Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Rie Suzuki
- Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Kohei Ihara
- Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Hikaru Miyagi
- Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Hiroshi Isogai
- Animal Research Center, Sapporo Medical University, Minami 1, Nishi 16, Sapporo 060-8556, Japan
| | - Hiroshi Yoneyama
- Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
| | - Emiko Isogai
- Laboratory of Animal Microbiology, Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, 468-1, Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
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Identification of Antibiotics That Diminish Disease in a Murine Model of Enterohemorrhagic Escherichia coli Infection. Antimicrob Agents Chemother 2020; 64:AAC.02159-19. [PMID: 32015030 DOI: 10.1128/aac.02159-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 01/27/2020] [Indexed: 11/20/2022] Open
Abstract
Infections with enterohemorrhagic Escherichia coli (EHEC) cause disease ranging from mild diarrhea to hemolytic-uremic syndrome (HUS) and are the most common cause of renal failure in children in high-income countries. The severity of the disease derives from the release of Shiga toxins (Stx). The use of antibiotics to treat EHEC infections is generally avoided, as it can result in increased stx expression. Here, we systematically tested different classes of antibiotics and found that their influence on stx expression and release varies significantly. We assessed a selection of these antibiotics in vivo using the Citrobacter rodentium ϕstx 2dact mouse model and show that stx 2d-inducing antibiotics resulted in weight loss and kidney damage despite clearance of the infection. However, several non-Stx-inducing antibiotics cleared bacterial infection without causing Stx-mediated pathology. Our results suggest that these antibiotics might be useful in the treatment of EHEC-infected human patients and decrease the risk of HUS development.
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14
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A Putative Microcin Amplifies Shiga Toxin 2a Production of Escherichia coli O157:H7. J Bacteriol 2019; 202:JB.00353-19. [PMID: 31611289 DOI: 10.1128/jb.00353-19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 10/01/2019] [Indexed: 01/15/2023] Open
Abstract
Escherichia coli O157:H7 is a foodborne pathogen implicated in various multistate outbreaks. It encodes Shiga toxin on a prophage, and Shiga toxin production is linked to phage induction. An E. coli strain, designated 0.1229, that amplified Stx2a production when cocultured with E. coli O157:H7 strain PA2 was identified. Growth of PA2 in 0.1229 cell-free supernatants had a similar effect, even when supernatants were heated to 100°C for 10 min, but not after treatment with proteinase K. The secreted molecule was shown to use TolC for export and the TonB system for import. The genes sufficient for production of this molecule were localized to a 5.2-kb region of a 12.8-kb plasmid. This region was annotated, identifying hypothetical proteins, a predicted ABC transporter, and a cupin superfamily protein. These genes were identified and shown to be functional in two other E. coli strains, and bioinformatic analyses identified related gene clusters in similar and distinct bacterial species. These data collectively suggest that E. coli 0.1229 and other E. coli strains produce a microcin that induces the SOS response in target bacteria. Besides adding to the limited number of microcins known to be produced by E. coli, this study provides an additional mechanism by which stx 2a expression is increased in response to the gut microflora.IMPORTANCE How the gut microflora influences the progression of bacterial infections is only beginning to be understood. Antibiotics are counterindicated for E. coli O157:H7 infections, limiting treatment options. An increased understanding of how the gut microflora directs O157:H7 virulence gene expression may lead to additional treatment options. This work identified E. coli strains that enhance the production of Shiga toxin by O157:H7 through the secretion of a proposed microcin. Microcins are natural antimicrobial peptides that target specific species, can act as alternatives to antibiotics, and mediate microbial competition. This work demonstrates another mechanism by which non-O157 E. coli strains may increase Shiga toxin production and adds to our understanding of microcins, a group of antimicrobials less well understood than colicins.
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Yuille S, Mackay WG, Morrison DJ, Tedford MC. Drivers of Clostridioides difficile hypervirulent ribotype 027 spore germination, vegetative cell growth and toxin production in vitro. Clin Microbiol Infect 2019; 26:941.e1-941.e7. [PMID: 31715298 DOI: 10.1016/j.cmi.2019.11.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/18/2019] [Accepted: 11/02/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVES Clostridioides difficile infection (CDI) is a considerable healthcare and economic burden worldwide. Faecal microbial transplant remains the most effective treatment for CDI, but is not at the present time the recommended standard of care. We hereby investigate which factors derived from a healthy gut microbiome might constitute the colonization resistance barrier (CRB) in the gut, inhibiting CDI. METHODS CRB drivers pH, short chain fatty acid (SCFA), and oxidation-reduction potential (ORP) were investigated in vitro using C. difficile NAP1/BI/027. Readouts for inhibitory mechanisms included germination, growth, toxin production and virulence gene expression. pH ranges (3-7.6), SCFA concentrations (25-200 mM) and ORP (-300 to 200 mV) were manipulated in brain heart infusion broth cultures under anaerobic conditions to assess the inhibitory action of these mechanisms. RESULTS A pH < 5.3 completely inhibited C. difficile growth to optical density (OD) 0.019 vs. 1.19 for control pH 7.5. Toxin production was reduced to 25 units vs. 3125 units for pH 7.6 (1 in 5 dilutions). Virulence gene expression reduced by 150-fold compared with pH 7.6 (p < 0.05). Germination and proliferation of spores below pH 6.13 yielded an average OD of 0.006 vs. 0.99 for control. SCFA were potent regulators of toxin production at 25 mM and above (p < 0.05). Acetate significantly inhibited toxin production to 25 units independent of OD (0.8733) vs. control (OD 0.6 and toxin titre 3125) (p < 0.05). ORP did not impact C. difficile growth. CONCLUSIONS This study highlights the critical role that pH has in the CRB, regulating CDI in vitro and that SCFA can regulate C. difficile function independent of pH.
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Affiliation(s)
- S Yuille
- School of Computing, Engineering & Physical Sciences, University of the West of Scotland, Paisley, UK
| | - W G Mackay
- School of Health & Life Sciences, University of the West of Scotland, Paisley, UK
| | - D J Morrison
- Scottish Universities Environmental Research Centre, University of Glasgow, East Kilbride, UK
| | - M C Tedford
- School of Computing, Engineering & Physical Sciences, University of the West of Scotland, Paisley, UK.
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16
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Wang C, Li Q, Ren J. Microbiota-Immune Interaction in the Pathogenesis of Gut-Derived Infection. Front Immunol 2019; 10:1873. [PMID: 31456801 PMCID: PMC6698791 DOI: 10.3389/fimmu.2019.01873] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 07/24/2019] [Indexed: 12/12/2022] Open
Abstract
Gut-derived infection is among the most common complications in patients who underwent severe trauma, serious burn, major surgery, hemorrhagic shock or severe acute pancreatitis (SAP). It could cause sepsis and multiple organ dysfunction syndrome (MODS), which are regarded as a leading cause of mortality in these cases. Gut-derived infection is commonly caused by pathological translocation of intestinal bacteria or endotoxins, resulting from the dysfunction of the gut barrier. In the last decades, the studies regarding to the pathogenesis of gut-derived infection mainly focused on the breakdown of intestinal epithelial tight junction and increased permeability. Limited information is available on the roles of intestinal microbial barrier in the development of gut-derived infection. Recently, advances of next-generation DNA sequencing techniques and its utilization has revolutionized the gut microecology, leading to novel views into the composition of the intestinal microbiota and its connections with multiple diseases. Here, we reviewed the recent progress in the research field of intestinal barrier disruption and gut-derived infection, mainly through the perspectives of the dysbiosis of intestinal microbiota and its interaction with intestinal mucosal immune cells. This review presents novel insights into how the gut microbiota collaborates with mucosal immune cells to involve the development of pathological bacterial translocation. The data might have important implication to better understand the mechanism underlying pathological bacterial translocation, contributing us to develop new strategies for prevention and treatment of gut-derived sepsis.
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Affiliation(s)
| | - Qiurong Li
- Research Institute of General Surgery, Jinling Hospital, Medical School, Nanjing University, Nanjing, China
| | - Jianan Ren
- Research Institute of General Surgery, Jinling Hospital, Medical School, Nanjing University, Nanjing, China
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17
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Tang C, Lu Z. Health promoting activities of probiotics. J Food Biochem 2019; 43:e12944. [PMID: 31368544 DOI: 10.1111/jfbc.12944] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 05/20/2019] [Accepted: 05/20/2019] [Indexed: 12/13/2022]
Abstract
In recent years, probiotics have received increasing attention and become one type of popular functional food because of their many biological functions. Among these desirable biological functions, the immune regulation, antioxidative activities, and antimicrobial effects are essential properties to maintain host health. Probiotics can regulate the immune system and improve the antioxidative system by producing microbial components and metabolites. Meanwhile, probiotics also possess antimicrobial abilities owing to their competition for nutrient requirements and mucus adherence, reducing pathogenic toxins, producing antimicrobial metabolites (short-chain fatty acids, bacteriocins, reuterin, linoleic acid, and secondary bile acids) and enhancing intestinal, or systemic immunity. Therefore, probiotics could be used to alleviate heavy metal toxicity and metabolic disorders by improving immunity, the antioxidative system, and intestinal micro-environment. This comprehensive review mainly highlights the potential health promoting activities of probiotics based on their antioxidative, antimicrobial, and immune regulatory effects. PRACTICAL APPLICATIONS: The antioxidative defense and the immune system are essential to maintain human health. However, many factors may result in microbial dysbiosis in the gut, which subsequently leads to pathogenic expansion, oxidative stress, and inflammatory responses. Therefore, it is important to explore beneficial foods to prevent or suppress these abnormal responses. Successful application of probiotics in the functional foods has attracted increasing attention due to their immune regulatory, antioxidative, and antimicrobial properties. The aim of this review is to introduce immune regulatory antioxidative and antimicrobial effects of probiotics, which provides some basic theories for scientific research and development of potential functional foods.
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Affiliation(s)
- Chao Tang
- Laboratory of Enzyme Engineering, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, China
| | - Zhaoxin Lu
- Laboratory of Enzyme Engineering, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, China
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18
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Inhibition of enterohemorrhagic Escherichia coli O157:H7 infection in a gnotobiotic mouse model with pre-colonization by Bacteroides strains. Biomed Rep 2019; 10:175-182. [PMID: 30906546 PMCID: PMC6403472 DOI: 10.3892/br.2019.1193] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/04/2019] [Indexed: 12/11/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 has been known to cause outbreaks of hemorrhagic colitis and hemolytic uremic syndrome. We previously demonstrated that intestinal flora contribute to the prevention of EHEC infection in a mouse model. However, it has not yet been determined whether Bacteroides, a predominant genus in the human intestine, contributes to the prevention of EHEC infection. The aim of the present study was to investigate the effect of Bacteroides fragilis (B. fragilis) and Bacteroides vulgatus (B. vulgatus) on EHEC O157:H7 infection in vivo using gnotobiotic mice. These strains were inoculated into germ-free mice to create a gnotobiotic mouse model. EHEC was inoculated into the mice, which were then monitored for 7 days for any change in symptoms. The mice that had been pre-colonized with the Bacteroides strains did not develop lethal EHEC infection, although several inflammatory symptoms were observed in the B. vulgatus pre-colonized group. However, no inflammatory symptoms were identified in the B. fragilis pre-colonized group. Moreover, B. fragilis exerted an inhibitory effect on enterocyte-like cell apoptosis. B. fragilis protected HT29 cells from apoptosis caused by Shiga toxin. In conclusion, the findings of the present study demonstrated that colonization by Bacteroides strains can inhibit EHEC infection.
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Menikpurage IP, Barraza D, Meléndez AB, Strebe S, Mera PE. The B12 receptor BtuB alters the membrane integrity of Caulobacter crescentus. MICROBIOLOGY-SGM 2019; 165:311-323. [PMID: 30628887 DOI: 10.1099/mic.0.000753] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Vitamin B12 is one of the most complex biomolecules in nature. Since few organisms can synthesize B12de novo, most bacteria utilize highly sensitive and specialized transporters to scavenge B12 and its precursors. In Gram-negative bacteria, BtuB is the outer membrane TonB-dependent receptor for B12. In the fresh water bacterium Caulobacter crescentus, btuB is among the most highly expressed genes. In this study, we characterized the function of BtuB in C. crescentus and unveiled a potential new function of this receptor involved in cellular fitness. Under standard minimal or rich growth conditions, we found that supplements of vitamin B12 to cultures of C. crescentus provided no significant advantage in growth rate. Using a B12 methionine auxotroph, we showed that BtuB in C. crescentus is capable of transporting B12 at low pico-molar range. A btuB knockout strain displayed higher sensitivity to detergents and to changes in osmotic pressure compared to the wild-type. Electron micrographs of this knockout strain revealed a morphology defect. The sensitivity observed in the btuB knockout strain was not due to changes in membrane permeability or altered S-layer levels. Our results demonstrate that btuB deletion mutants exhibit increased susceptibility to membrane stressors, suggesting a potential role of this receptor in membrane homeostasis. Because we only tested BtuB's function under laboratory conditions, we cannot eliminate the possibility that BtuB also plays a key role as a B12 scavenger in C. crescentus when growing in its highly variable and nutrient-limited natural environment.
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Affiliation(s)
- Inoka P Menikpurage
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA
| | - Daniela Barraza
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA
| | - Ady B Meléndez
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA
| | - Sierra Strebe
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA
| | - Paola E Mera
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA
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20
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Gao CH, Zhang M, Wu Y, Huang Q, Cai P. Divergent Influence to a Pathogen Invader by Resident Bacteria with Different Social Interactions. MICROBIAL ECOLOGY 2019; 77:76-86. [PMID: 29858645 DOI: 10.1007/s00248-018-1207-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
Bacterial social interaction is a potential influencing factor in determining the fate of invading pathogens in diverse environments. In this study, interactions between two representative resident species (Bacillus subtilis and Pseudomonas putida) and a leading food-borne disease causative pathogen (Vibrio parahaemolyticus) were examined. An antagonistic effect toward V. parahaemolyticus was observed for B. subtilis but not for P. putida. However, the relative richness of the pathogen remained rather high in B. subtilis co-cultures and was, unexpectedly, not sensitive to the initial inoculation ratios. Furthermore, two approaches were found to be efficient at modulating the relative richness of the pathogen. (1) The addition of trace glycerol and manganese to Luria-Bertani medium (LBGM) reduced the richness of V. parahaemolyticus in the co-culture with B. subtilis and in contrast, increased its richness in the co-culture with P. putida, although it did not affect the growth of V. parahaemolyticus by its own. (2) The relative richness of V. parahaemolyticus on semisolid medium decreased significantly as a function of an agar gradient, ranging from 0 to 2%. Furthermore, we explored the molecular basis of bacterial interaction through transcriptomic analysis. In summary, we investigated the interactions between a pathogen invader and two resident bacteria species, showing that the different influences on a pathogen by different types of interactions can be modulated by chemicals and medium fluidity.
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Affiliation(s)
- Chun-Hui Gao
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ming Zhang
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yichao Wu
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qiaoyun Huang
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China
| | - Peng Cai
- State Key Laboratory of Agricultural Microbiology, College of Resources and Environment, Huazhong Agricultural University, Wuhan, 430070, China.
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21
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Balasubramanian S, Osburne MS, BrinJones H, Tai AK, Leong JM. Prophage induction, but not production of phage particles, is required for lethal disease in a microbiome-replete murine model of enterohemorrhagic E. coli infection. PLoS Pathog 2019; 15:e1007494. [PMID: 30629725 PMCID: PMC6328086 DOI: 10.1371/journal.ppat.1007494] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 12/01/2018] [Indexed: 12/12/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) colonize intestinal epithelium by generating characteristic attaching and effacing (AE) lesions. They are lysogenized by prophage that encode Shiga toxin 2 (Stx2), which is responsible for severe clinical manifestations. As a lysogen, prophage genes leading to lytic growth and stx2 expression are repressed, whereas induction of the bacterial SOS response in response to DNA damage leads to lytic phage growth and Stx2 production both in vitro and in germ-free or streptomycin-treated mice. Some commensal bacteria diminish prophage induction and concomitant Stx2 production in vitro, whereas it has been proposed that phage-susceptible commensals may amplify Stx2 production by facilitating successive cycles of infection in vivo. We tested the role of phage induction in both Stx production and lethal disease in microbiome-replete mice, using our mouse model encompassing the murine pathogen Citrobacter rodentium lysogenized with the Stx2-encoding phage Φstx2dact. This strain generates EHEC-like AE lesions on the murine intestine and causes lethal Stx-mediated disease. We found that lethal mouse infection did not require that Φstx2dact infect or lysogenize commensal bacteria. In addition, we detected circularized phage genomes, potentially in the early stage of replication, in feces of infected mice, confirming that prophage induction occurs during infection of microbiota-replete mice. Further, C. rodentium (Φstx2dact) mutants that do not respond to DNA damage or express stx produced neither high levels of Stx2 in vitro or lethal infection in vivo, confirming that SOS induction and concomitant expression of phage-encoded stx genes are required for disease. In contrast, C. rodentium (Φstx2dact) mutants incapable of prophage genome excision or of packaging phage genomes retained the ability to produce Stx in vitro, as well as to cause lethal disease in mice. Thus, in a microbiome-replete EHEC infection model, lytic induction of Stx-encoding prophage is essential for lethal disease, but actual phage production is not.
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Affiliation(s)
- Sowmya Balasubramanian
- Department of Molecular Biology and Microbiology at Tufts University School of Medicine, Boston, MA, United States of America
| | - Marcia S. Osburne
- Department of Molecular Biology and Microbiology at Tufts University School of Medicine, Boston, MA, United States of America
| | - Haley BrinJones
- Department of Molecular Biology and Microbiology at Tufts University School of Medicine, Boston, MA, United States of America
| | - Albert K. Tai
- Department of Immunology at Tufts University School of Medicine, Boston, MA, United States of America
| | - John M. Leong
- Department of Molecular Biology and Microbiology at Tufts University School of Medicine, Boston, MA, United States of America
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22
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Modulation of Enterohaemorrhagic Escherichia coli Survival and Virulence in the Human Gastrointestinal Tract. Microorganisms 2018; 6:microorganisms6040115. [PMID: 30463258 PMCID: PMC6313751 DOI: 10.3390/microorganisms6040115] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/16/2018] [Accepted: 11/18/2018] [Indexed: 01/05/2023] Open
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) is a major foodborne pathogen responsible for human diseases ranging from diarrhoea to life-threatening complications. Survival of the pathogen and modulation of virulence gene expression along the human gastrointestinal tract (GIT) are key features in bacterial pathogenesis, but remain poorly described, due to a paucity of relevant model systems. This review will provide an overview of the in vitro and in vivo studies investigating the effect of abiotic (e.g., gastric acid, bile, low oxygen concentration or fluid shear) and biotic (e.g., gut microbiota, short chain fatty acids or host hormones) parameters of the human gut on EHEC survival and/or virulence (especially in relation with motility, adhesion and toxin production). Despite their relevance, these studies display important limitations considering the complexity of the human digestive environment. These include the evaluation of only one single digestive parameter at a time, lack of dynamic flux and compartmentalization, and the absence of a complex human gut microbiota. In a last part of the review, we will discuss how dynamic multi-compartmental in vitro models of the human gut represent a novel platform for elucidating spatial and temporal modulation of EHEC survival and virulence along the GIT, and provide new insights into EHEC pathogenesis.
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23
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Casals-Pascual C, Vergara A, Vila J. Intestinal microbiota and antibiotic resistance: Perspectives and solutions. ACTA ACUST UNITED AC 2018. [DOI: 10.1016/j.humic.2018.05.002] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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24
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Xiaoli L, Figler HM, Goswami Banerjee K, Hayes CS, Dudley EG. Non-pathogenic Escherichia coli Enhance Stx2a Production of E. coli O157:H7 Through Both bamA-Dependent and Independent Mechanisms. Front Microbiol 2018; 9:1325. [PMID: 29973923 PMCID: PMC6020778 DOI: 10.3389/fmicb.2018.01325] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 05/30/2018] [Indexed: 01/14/2023] Open
Abstract
Intestinal colonization by the foodborne pathogen Escherichia coli O157:H7 leads to serious disease symptoms, including hemolytic uremic syndrome (HUS) and hemorrhagic colitis (HC). Synthesis of one or more Shiga toxins (Stx) is essential for HUS and HC development. The genes encoding Stx, including Stx2a, are found within a lambdoid prophage integrated in the E. coli O157:H7 chromosome. Enhanced Stx2a expression was reported when specific non-pathogenic E. coli strains were co-cultured with E. coli O157:H7, and it was hypothesized that this phenotype required the non-pathogenic E. coli to be sensitive to stx-converting phage infection. We tested this hypothesis by generating phage resistant non-pathogenic E. coli strains where bamA (an essential gene and Stx phage receptor) was replaced with an ortholog from other species. Such heterologous gene replacement abolished the ability of the laboratory strain E. coli C600 to enhance toxin production when co-cultured with E. coli O157:H7 strain PA2, which belongs to the hypervirulent clade 8. The extracellular loops of BamA (loop 4, 6, 7) were further shown to be important for infection by stx2a-converting phages. However, similar gene replacement in another commensal E. coli, designated 1.1954, revealed a bamA-independent mechanism for toxin amplification. Toxin enhancement by 1.1954 was not the result of phage infection through an alternative receptor (LamB or FadL), lysogen formation by stx2a-converting phages, or the production of a secreted molecule. Collectively, these data suggest that non-pathogenic E. coli can enhance toxin production through at least two mechanisms.
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Affiliation(s)
- Lingzi Xiaoli
- Department of Food Science, The Pennsylvania State University, University Park, PA, United States
| | - Hillary M Figler
- Huck Institutes of Life Sciences, The Pennsylvania State University, University Park, PA, United States
| | - Kakolie Goswami Banerjee
- Department of Food Science, The Pennsylvania State University, University Park, PA, United States
| | - Christopher S Hayes
- Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, United States
| | - Edward G Dudley
- Department of Food Science, The Pennsylvania State University, University Park, PA, United States.,Center for Immunology and Infectious Disease, The Pennsylvania State University, University Park, PA, United States
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25
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Thanissery R, Zeng D, Doyle RG, Theriot CM. A Small Molecule-Screening Pipeline to Evaluate the Therapeutic Potential of 2-Aminoimidazole Molecules Against Clostridium difficile. Front Microbiol 2018; 9:1206. [PMID: 29928268 PMCID: PMC5997789 DOI: 10.3389/fmicb.2018.01206] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/17/2018] [Indexed: 12/19/2022] Open
Abstract
Antibiotics are considered to be the first line of treatment for mild to moderately severe Clostridium difficile infection (CDI) in humans. However, antibiotics are also risk factors for CDI as they decrease colonization resistance against C. difficile by altering the gut microbiota and metabolome. Finding compounds that selectively inhibit different stages of the C. difficile life cycle, while sparing the indigenous gut microbiota is important for the development of alternatives to standard antibiotic treatment. 2-aminoimidazole (2-AI) molecules are known to disrupt bacterial protection mechanisms in antibiotic resistant bacteria such as Pseudomonas aeruginosa, Acinetobacter baumannii, and Staphylococcus aureus, but are yet to be evaluated against C. difficile. A comprehensive small molecule-screening pipeline was developed to investigate how novel small molecules affect different stages of the C. difficile life cycle (growth, toxin, and sporulation) in vitro, and a library of commensal bacteria that are associated with colonization resistance against C. difficile. The initial screening tested the efficacy of eleven 2-AI molecules (compound 1 through 11) against C. difficile R20291 compared to a vancomycin (2 μg/ml) control. Molecules were selected for their ability to inhibit C. difficile growth, toxin activity, and sporulation. Further testing included growth inhibition of other C. difficile strains (CD196, M68, CF5, 630, BI9, M120) belonging to distinct PCR ribotypes, and a commensal panel (Bacteroides fragilis, B. thetaiotaomicron, C. scindens, C. hylemonae, Lactobacillus acidophilus, L. gasseri, Escherichia coli, B. longum subsp. infantis). Three molecules compound 1 and 2, and 3 were microbicidal, whereas compounds 4, 7, 9, and 11 inhibited toxin activity without affecting the growth of C. difficile strains and the commensal microbiota. The antimicrobial and anti-toxin effects of 2-AI molecules need to be further characterized for mode of action and validated in a mouse model of CDI.
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Affiliation(s)
- Rajani Thanissery
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States
| | - Daina Zeng
- Agile Sciences, Inc., Raleigh, NC, United States
| | - Raul G Doyle
- Agile Sciences, Inc., Raleigh, NC, United States
| | - Casey M Theriot
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, United States
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26
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Kapitan M, Niemiec MJ, Steimle A, Frick JS, Jacobsen ID. Fungi as Part of the Microbiota and Interactions with Intestinal Bacteria. Curr Top Microbiol Immunol 2018; 422:265-301. [PMID: 30062595 DOI: 10.1007/82_2018_117] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The human microbiota consists of bacteria, archaea, viruses, and fungi that build a highly complex network of interactions between each other and the host. While there are many examples for commensal bacterial influence on host health and immune modulation, little is known about the role of commensal fungi inside the gut community. Up until now, fungal research was concentrating on opportunistic diseases caused by fungal species, leaving the possible role of fungi as part of the microbiota largely unclear. Interestingly, fungal and bacterial abundance in the gut appear to be negatively correlated and disruption of the bacterial microbiota is a prerequisite for fungal overgrowth. The mechanisms behind bacterial colonization resistance are likely diverse, including direct antagonism as well as bacterial stimulation of host defense mechanisms. In this work, we will review the current knowledge of the development of the intestinal bacterial and fungal community, the influence of the microbiota on human health and disease, and the role of the opportunistic yeast C. albicans. We will furthermore discuss the possible benefits of commensal fungal colonization. Finally, we will summarize the recent findings on bacterial-fungal interactions.
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Affiliation(s)
- Mario Kapitan
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, Jena, Germany
| | - M Joanna Niemiec
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, Jena, Germany
| | - Alexander Steimle
- Interfaculty Institute for Microbiology and Infection Medicine, Tübingen, Germany
| | - Julia S Frick
- Interfaculty Institute for Microbiology and Infection Medicine, Tübingen, Germany
| | - Ilse D Jacobsen
- Research Group Microbial Immunology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knöll Institute, Jena, Germany.
- Center for Sepsis Control and Care (CSCC), Jena University Hospital, Jena, Germany.
- Institute for Microbiology, Friedrich Schiller University, Jena, Germany.
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Chiu L, Bazin T, Truchetet ME, Schaeverbeke T, Delhaes L, Pradeu T. Protective Microbiota: From Localized to Long-Reaching Co-Immunity. Front Immunol 2017; 8:1678. [PMID: 29270167 PMCID: PMC5725472 DOI: 10.3389/fimmu.2017.01678] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/15/2017] [Indexed: 12/17/2022] Open
Abstract
Resident microbiota do not just shape host immunity, they can also contribute to host protection against pathogens and infectious diseases. Previous reviews of the protective roles of the microbiota have focused exclusively on colonization resistance localized within a microenvironment. This review shows that the protection against pathogens also involves the mitigation of pathogenic impact without eliminating the pathogens (i.e., “disease tolerance”) and the containment of microorganisms to prevent pathogenic spread. Protective microorganisms can have an impact beyond their niche, interfering with the entry, establishment, growth, and spread of pathogenic microorganisms. More fundamentally, we propose a series of conceptual clarifications in support of the idea of a “co-immunity,” where an organism is protected by both its own immune system and components of its microbiota.
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Affiliation(s)
- Lynn Chiu
- University of Bordeaux, CNRS, ImmunoConcept, UMR 5164, Bordeaux, France
| | - Thomas Bazin
- University of Bordeaux, INRA, Mycoplasmal and Chlamydial Infections in Humans, EA 3671, Bordeaux, France.,Department of Hepato-Gastroenterology, Bordeaux Hospital University Center, Pessac, France
| | | | - Thierry Schaeverbeke
- University of Bordeaux, INRA, Mycoplasmal and Chlamydial Infections in Humans, EA 3671, Bordeaux, France.,Department of Rheumatology, Bordeaux Hospital University Center, Bordeaux, France
| | - Laurence Delhaes
- Department of Parasitology and Mycology, Bordeaux Hospital University Center, Bordeaux, France.,University of Bordeaux, INSERM, Cardio-Thoracic Research Centre of Bordeaux, U1045, Bordeaux, France
| | - Thomas Pradeu
- University of Bordeaux, CNRS, ImmunoConcept, UMR 5164, Bordeaux, France
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Cordonnier C, Thévenot J, Etienne-Mesmin L, Alric M, Livrelli V, Blanquet-Diot S. Probiotic and enterohemorrhagic Escherichia coli: An effective strategy against a deadly enemy? Crit Rev Microbiol 2016; 43:116-132. [PMID: 27798976 DOI: 10.1080/1040841x.2016.1185602] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) are major food-borne pathogens that constitute a serious public health threat. Currently, there is no specific treatment available for EHEC infections in human creating an urgent need for the development of alternative therapeutic strategies. Among them, one of the most promising approaches is the use of probiotic microorganisms. Even if many studies have shown the antagonistic effects of probiotic bacteria or yeast on EHEC survival, virulence, adhesion on intestinal epithelium or pathogen-induced inflammatory responses, mechanisms mediating their beneficial effects remain unclear. This review describes EHEC pathogenesis and novel therapeutic strategies, with a particular emphasis on probiotics. The interests and limits of a probiotic-based approach and the way it might be incorporated into global health strategies against EHEC infections will be discussed.
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Affiliation(s)
- Charlotte Cordonnier
- a EA 4678 CIDAM, "Conception, Ingénierie et Développement de l'Aliment et du Médicament", Centre de Recherche en Nutrition Humaine Auvergne , Université d'Auvergne , Clermont-Ferrand , France.,b M2iSH, "Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte" , UMR Inserm/Université d'Auvergne U1071, USC-INRA 2018, Centre de Recherche en Nutrition Humaine Auvergne, Université d'Auvergne , Clermont-Ferrand , France
| | - Jonathan Thévenot
- a EA 4678 CIDAM, "Conception, Ingénierie et Développement de l'Aliment et du Médicament", Centre de Recherche en Nutrition Humaine Auvergne , Université d'Auvergne , Clermont-Ferrand , France.,b M2iSH, "Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte" , UMR Inserm/Université d'Auvergne U1071, USC-INRA 2018, Centre de Recherche en Nutrition Humaine Auvergne, Université d'Auvergne , Clermont-Ferrand , France
| | - Lucie Etienne-Mesmin
- a EA 4678 CIDAM, "Conception, Ingénierie et Développement de l'Aliment et du Médicament", Centre de Recherche en Nutrition Humaine Auvergne , Université d'Auvergne , Clermont-Ferrand , France.,b M2iSH, "Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte" , UMR Inserm/Université d'Auvergne U1071, USC-INRA 2018, Centre de Recherche en Nutrition Humaine Auvergne, Université d'Auvergne , Clermont-Ferrand , France
| | - Monique Alric
- a EA 4678 CIDAM, "Conception, Ingénierie et Développement de l'Aliment et du Médicament", Centre de Recherche en Nutrition Humaine Auvergne , Université d'Auvergne , Clermont-Ferrand , France
| | - Valérie Livrelli
- b M2iSH, "Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte" , UMR Inserm/Université d'Auvergne U1071, USC-INRA 2018, Centre de Recherche en Nutrition Humaine Auvergne, Université d'Auvergne , Clermont-Ferrand , France.,c Service de Bactériologie , CHU Clermont-Ferrand , Clermont-Ferrand , France
| | - Stéphanie Blanquet-Diot
- a EA 4678 CIDAM, "Conception, Ingénierie et Développement de l'Aliment et du Médicament", Centre de Recherche en Nutrition Humaine Auvergne , Université d'Auvergne , Clermont-Ferrand , France
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29
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Counterselection employing mutated pheS for markerless genetic deletion in Bacteroides species. Anaerobe 2016; 42:81-88. [PMID: 27639596 DOI: 10.1016/j.anaerobe.2016.09.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 02/04/2023]
Abstract
Markerless gene deletion is necessary for multiple gene disruptions due to the limited number of antibiotic resistant markers for some bacteria. However, even in transformable strains, obtaining the expected mutation without a marker requires laborious screening of a large number of colonies. Previous studies had success in various bacteria with a counter-selection system where a conditional lethal gene was incorporated into the vector. We examined the efficacy of the mutated pheS gene (pheS*) as a counter-selective marker for gene deletion in Bacteroides. This mutation produces an amino acid substitution (A303G) in the alpha subunit of Bacteroides phenylalanyl tRNA synthetase, which in E. coli alters the specificity of the tRNA synthetase resulting in a conditional lethal mutation due to the incorporation of p-chloro-phenylalanine (p-Cl-Phe) into protein. B. fragilis YCH46 and B. thetaiotaomicron VPI-5482 transformed with a pheS*-harboring shuttle vector were clearly growth-inhibited in the presence of >5 mM p-Cl-Phe in liquid defined minimal media (DMM) and on DMM agar plates. A targeting plasmid was constructed to delete the genetic region for capsular polysaccharide PS2 in B. fragilis or PS1 in B. thetaiotaomicron. After counterselection, p-Cl-Phe-resistant colonies were generated at a frequency of 8.1 × 10-3 for B. fragilis and 1.7 × 10-3 for B. thetaiotaomicron. Of the p-Cl-Phe-resistant colonies, 4.2% and 72% harbored the correct genetic deletion for B. fragilis and B. thetaiotaomicron, respectively. These results indicate that mutated pheS is a useful counter-selective gene to construct markerless genetic deletions in Bacteroides.
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30
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McKenney ES, Kendall MM. Microbiota and pathogen 'pas de deux': setting up and breaking down barriers to intestinal infection. Pathog Dis 2016; 74:ftw051. [PMID: 27252177 PMCID: PMC5985477 DOI: 10.1093/femspd/ftw051] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/04/2016] [Accepted: 05/24/2016] [Indexed: 02/07/2023] Open
Abstract
The gut microbiota plays essential roles in human health and disease. In this review, we focus on the role of the intestinal microbiota in promoting resistance to infection by bacterial pathogens as well as how pathogens overcome this barrier. We discuss how the resident microbiota restricts growth and colonization of invading pathogens by limiting availability of nutrients and through generation of a hostile environment. Additionally, we examine how microbiota-derived signaling molecules interfere with bacterial virulence. In turn, we discuss how pathogens exploit non-competitive metabolites to replicate in vivo as well as to precisely control virulence and cause disease. This bacterial two step of creating and overcoming challenges important in preventing and establishing infection highlights the complexities of elucidating interactions between the commensal bacteria and pathogens. Better understanding of microbiota-pathogen interplay will have significant implications for developing novel therapeutics to treat infectious diseases.
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Affiliation(s)
- Elizabeth S McKenney
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Melissa M Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
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31
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Araos R, Tai AK, Snyder GM, Blaser MJ, D'Agata EMC. Predominance of Lactobacillus spp. Among Patients Who Do Not Acquire Multidrug-Resistant Organisms. Clin Infect Dis 2016; 63:937-943. [PMID: 27358350 DOI: 10.1093/cid/ciw426] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 06/17/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND The emergence and dissemination of multidrug-resistant organisms (MDROs) is a global threat. Characterizing the human microbiome among hospitalized patients and identifying unique microbial signatures among those patients who acquire MDROs may identify novel infection prevention strategies. METHODS Adult patients admitted to 5 general medical-surgical floors at a 649-bed, tertiary care center in Boston, Massachusetts, were classified according to in-hospital antimicrobial exposure and MDRO colonization status. Within 48 hours of hospital admission (baseline) and at discharge (follow-up), rectal swab samples were obtained, and compared with samples from an external control group of healthy persons from the community. DNA was extracted from samples, next-generation sequencing performed, and microbial community structure and taxonomic features assessed, comparing those who acquired MDROs and those who had not, and the external controls. RESULTS Hospitalized patients (n = 44) had reduced microbial diversity and a greater abundance of Escherichia spp. and Enterococcus spp. than healthy controls (n = 26). Among hospitalized patients, 25 had no MDROs at the time of the baseline sample and were also exposed to antimicrobials. Among this group, 7 (28%) acquired ≥1 MDRO; demographic and clinical characteristics were similar between MDRO-acquisition and MDRO-nonacquisition groups. Patients in the nonacquisition group had consistently higher Lactobacillus spp. abundance than those in the acquisition group (linear discriminant score, 3.97; P = .04). CONCLUSIONS The fecal microbiota of the hospitalized subjects had abnormal community composition, and Lactobacillus spp. was associated with lack of MDRO acquisition, consistent with a protective role.
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Affiliation(s)
- Rafael Araos
- Department of Medicine, Facultad de Medicina Clinica Alemana, Universidad del Desarrollo, Santiago, Chile
| | - Albert K Tai
- Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine
| | - Graham M Snyder
- Department of Medicine, Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, Massachusetts
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32
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Chopyk J, Moore RM, DiSpirito Z, Stromberg ZR, Lewis GL, Renter DG, Cernicchiaro N, Moxley RA, Wommack KE. Presence of pathogenic Escherichia coli is correlated with bacterial community diversity and composition on pre-harvest cattle hides. MICROBIOME 2016; 4:9. [PMID: 27000779 PMCID: PMC4802634 DOI: 10.1186/s40168-016-0155-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 02/10/2016] [Indexed: 05/10/2023]
Abstract
BACKGROUND Since 1982, specific serotypes of Shiga toxin-producing Escherichia coli (STEC) have been recognized as significant foodborne pathogens acquired from contaminated beef and, more recently, other food products. Cattle are the major reservoir hosts of these organisms, and while there have been advancements in food safety practices and industry standards, STEC still remains prevalent within beef cattle operations with cattle hides implicated as major sources of carcass contamination. To investigate whether the composition of hide-specific microbial communities are associated with STEC prevalence, 16S ribosomal RNA (rRNA) bacterial community profiles were obtained from hide and fecal samples collected from a large commercial feedlot over a 3-month period. These community data were examined amidst an extensive collection of prevalence data on a subgroup of STEC that cause illness in humans, referred to as enterohemorrhagic E. coli (EHEC). Fecal 16S rRNA gene OTUs (operational taxonomic units) were subtracted from the OTUs found within each hide 16S rRNA amplicon library to identify hide-specific bacterial populations. RESULTS Comparative analysis of alpha diversity revealed a significant correlation between low bacterial diversity and samples positive for the presence of E. coli O157:H7 and/or the non-O157 groups: O26, O111, O103, O121, O45, and O145. This trend occurred regardless of diversity metric or fecal OTU presence. The number of EHEC serogroups present in the samples had a compounding effect on the inverse relationship between pathogen presence and bacterial diversity. Beta diversity data showed differences in bacterial community composition between samples containing O157 and non-O157 populations, with certain OTUs demonstrating significant changes in relative abundance. CONCLUSIONS The cumulative prevalence of the targeted EHEC serogroups was correlated with low bacterial community diversity on pre-harvest cattle hides. Understanding the relationship between indigenous hide bacterial communities and populations may provide strategies to limit EHEC in cattle and provide biomarkers for EHEC risk assessment.
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Affiliation(s)
- Jessica Chopyk
- Delaware Biotechnology Institute, University of Delaware, Delaware Biotechnology Inst., 15 Innovation Way, Newark, DE, 19711, USA
| | - Ryan M Moore
- Delaware Biotechnology Institute, University of Delaware, Delaware Biotechnology Inst., 15 Innovation Way, Newark, DE, 19711, USA
| | - Zachary DiSpirito
- Delaware Biotechnology Institute, University of Delaware, Delaware Biotechnology Inst., 15 Innovation Way, Newark, DE, 19711, USA
| | - Zachary R Stromberg
- Delaware Biotechnology Institute, University of Delaware, Delaware Biotechnology Inst., 15 Innovation Way, Newark, DE, 19711, USA
| | - Gentry L Lewis
- Delaware Biotechnology Institute, University of Delaware, Delaware Biotechnology Inst., 15 Innovation Way, Newark, DE, 19711, USA
| | - David G Renter
- College of Veterinary Medicine, Kansas State University, Manhattan, KS, USA
| | | | - Rodney A Moxley
- School of Veterinary Medicine & Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - K Eric Wommack
- Delaware Biotechnology Institute, University of Delaware, Delaware Biotechnology Inst., 15 Innovation Way, Newark, DE, 19711, USA.
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Vitamin B12 Uptake by the Gut Commensal Bacteria Bacteroides thetaiotaomicron Limits the Production of Shiga Toxin by Enterohemorrhagic Escherichia coli. Toxins (Basel) 2016; 8:toxins8010014. [PMID: 26742075 PMCID: PMC4728536 DOI: 10.3390/toxins8010014] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 12/17/2015] [Accepted: 12/29/2015] [Indexed: 01/11/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) are foodborne pathogens responsible for the development of bloody diarrhea and renal failure in humans. Many environmental factors have been shown to regulate the production of Shiga toxin 2 (Stx2), the main virulence factor of EHEC. Among them, soluble factors produced by human gut microbiota and in particular, by the predominant species Bacteroides thetaiotaomicron (B. thetaiotaomicron), inhibit Stx2 gene expression. In this study, we investigated the molecular mechanisms underlying the B. thetaiotaomicron-dependent inhibition of Stx2 production by EHEC. We determined that Stx2-regulating molecules are resistant to heat treatment but do not correspond to propionate and acetate, two short-chain fatty acids produced by B. thetaiotaomicron. Moreover, screening of a B. thetaiotaomicron mutant library identified seven mutants that do not inhibit Stx2 synthesis by EHEC. One mutant has impaired production of BtuB, an outer membrane receptor for vitamin B12. Together with restoration of Stx2 level after vitamin B12 supplementation, these data highlight vitamin B12 as a molecule produced by gut microbiota that modulates production of a key virulence factor of EHEC and consequently may affect the outcome of an infection.
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Coculture of Escherichia coli O157:H7 with a Nonpathogenic E. coli Strain Increases Toxin Production and Virulence in a Germfree Mouse Model. Infect Immun 2015; 83:4185-93. [PMID: 26259815 DOI: 10.1128/iai.00663-15] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 08/05/2015] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli O157:H7 is a notorious foodborne pathogen due to its low infectious dose and the disease symptoms it causes, which include bloody diarrhea and severe abdominal cramps. In some cases, the disease progresses to hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS), due to the expression of one or more Shiga toxins (Stx). Isoforms of Stx, including Stx2a, are encoded within temperate prophages. In the presence of certain antibiotics, phage induction occurs, which also increases the expression of toxin genes. Additionally, increased Stx2 accumulation has been reported when O157:H7 was cocultured with phage-susceptible nonpathogenic E. coli. This study characterized an E. coli O157:H7 strain, designated PA2, that belongs to the hypervirulent clade 8 cluster. Stx2a levels after ciprofloxacin induction were lower for PA2 than for the prototypical outbreak strains Sakai and EDL933. However, during coculture with the nonpathogenic strain E. coli C600, PA2 produced Stx2a levels that were 2- to 12-fold higher than those observed during coculture with EDL933 and Sakai, respectively. Germfree mice cocolonized by PA2 and C600 showed greater kidney damage, increased Stx2a accumulation in feces, and more visible signs of disease than mice given PA2 or C600 alone. These data suggest one mechanism by which microorganisms associated with the colonic microbiota could enhance the virulence of E. coli O157:H7, particularly a subset of clade 8 strains.
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35
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Thévenot J, Cordonnier C, Rougeron A, Le Goff O, Nguyen HTT, Denis S, Alric M, Livrelli V, Blanquet-Diot S. Enterohemorrhagic Escherichia coli infection has donor-dependent effect on human gut microbiota and may be antagonized by probiotic yeast during interaction with Peyer's patches. Appl Microbiol Biotechnol 2015; 99:9097-110. [PMID: 26084888 DOI: 10.1007/s00253-015-6704-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 05/13/2015] [Accepted: 05/17/2015] [Indexed: 01/05/2023]
Abstract
Enterohemorrhagic Escherichia coli (EHEC) are major food-borne pathogens responsible for serious infections ranging from mild diarrhea to hemorrhagic colitis and life-threatening complications. Shiga toxins (Stxs) are the main virulence factor of EHEC. The antagonistic effect of a prophylactic treatment with the probiotic strain Saccharomyces cerevisiae against EHEC O157:H7 was investigated using complementary in vitro human colonic model and in vivo murine ileal loop assays. In vitro, the probiotic treatment had no effect on O157:H7 survival but favorably influenced gut microbiota activity through modulation of short-chain fatty acid production, increasing acetate production and decreasing that of butyrate. Both pathogen and probiotic strains had individual-dependent effects on human gut microbiota. For the first time, stx expression was followed in human colonic environment: at 9 and 12 h post EHEC infection, probiotic treatment significantly decreased stx mRNA levels. Besides, in murine ileal loops, the probiotic yeast specifically exerted a trophic effect on intestinal mucosa and inhibited O157:H7 interactions with Peyer's patches and subsequent hemorrhagic lesions. Taken together, the results suggest that S. cerevisiae may be useful in the fight against EHEC infection and that host associated factors such as microbiota could influence clinical evolution of EHEC infection and the effectiveness of probiotics.
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Affiliation(s)
- J Thévenot
- Centre de Recherche en Nutrition Humaine Auvergne, EA 4678 CIDAM, Conception Ingénierie et Développement de l'Aliment et du Médicament, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France.,Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte UMR INSERM / Université d'Auvergne U1071 USC-INRA 2018, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - C Cordonnier
- Centre de Recherche en Nutrition Humaine Auvergne, EA 4678 CIDAM, Conception Ingénierie et Développement de l'Aliment et du Médicament, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France.,Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte UMR INSERM / Université d'Auvergne U1071 USC-INRA 2018, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - A Rougeron
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte UMR INSERM / Université d'Auvergne U1071 USC-INRA 2018, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - O Le Goff
- Centre de Recherche en Nutrition Humaine Auvergne, EA 4678 CIDAM, Conception Ingénierie et Développement de l'Aliment et du Médicament, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - H T T Nguyen
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte UMR INSERM / Université d'Auvergne U1071 USC-INRA 2018, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - S Denis
- Centre de Recherche en Nutrition Humaine Auvergne, EA 4678 CIDAM, Conception Ingénierie et Développement de l'Aliment et du Médicament, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - M Alric
- Centre de Recherche en Nutrition Humaine Auvergne, EA 4678 CIDAM, Conception Ingénierie et Développement de l'Aliment et du Médicament, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - V Livrelli
- Centre de Recherche en Nutrition Humaine Auvergne, M2iSH, Microbes, Intestin, Inflammation et Susceptibilité de l'Hôte UMR INSERM / Université d'Auvergne U1071 USC-INRA 2018, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France.,Service de Bactériologie, CHU Clermont-Ferrand, Clermont-Ferrand, France
| | - S Blanquet-Diot
- Centre de Recherche en Nutrition Humaine Auvergne, EA 4678 CIDAM, Conception Ingénierie et Développement de l'Aliment et du Médicament, Clermont Université, Université d'Auvergne, Clermont-Ferrand, France.
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Chemical communication in the gut: Effects of microbiota-generated metabolites on gastrointestinal bacterial pathogens. Anaerobe 2015; 34:106-15. [PMID: 25958185 DOI: 10.1016/j.anaerobe.2015.05.002] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 04/24/2015] [Accepted: 05/04/2015] [Indexed: 01/27/2023]
Abstract
Gastrointestinal pathogens must overcome many obstacles in order to successfully colonize a host, not the least of which is the presence of the gut microbiota, the trillions of commensal microorganisms inhabiting mammals' digestive tracts, and their products. It is well established that a healthy gut microbiota provides its host with protection from numerous pathogens, including Salmonella species, Clostridium difficile, diarrheagenic Escherichia coli, and Vibrio cholerae. Conversely, pathogenic bacteria have evolved mechanisms to establish an infection and thrive in the face of fierce competition from the microbiota for space and nutrients. Here, we review the evidence that gut microbiota-generated metabolites play a key role in determining the outcome of infection by bacterial pathogens. By consuming and transforming dietary and host-produced metabolites, as well as secreting primary and secondary metabolites of their own, the microbiota define the chemical environment of the gut and often determine specific host responses. Although most gut microbiota-produced metabolites are currently uncharacterized, several well-studied molecules made or modified by the microbiota are known to affect the growth and virulence of pathogens, including short-chain fatty acids, succinate, mucin O-glycans, molecular hydrogen, secondary bile acids, and the AI-2 quorum sensing autoinducer. We also discuss challenges and possible approaches to further study of the chemical interplay between microbiota and gastrointestinal pathogens.
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38
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Iversen H, Lindbäck T, L’Abée-Lund TM, Roos N, Aspholm M, Stenfors Arnesen L. The gut bacterium Bacteroides thetaiotaomicron influences the virulence potential of the enterohemorrhagic Escherichia coli O103:H25. PLoS One 2015; 10:e0118140. [PMID: 25719195 PMCID: PMC4342160 DOI: 10.1371/journal.pone.0118140] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 12/17/2014] [Indexed: 11/18/2022] Open
Abstract
Enterohemorrhagic E. coli (EHEC) is associated with severe gastrointestinal disease. Upon entering the gastrointestinal tract, EHEC is exposed to a fluctuating environment and a myriad of other bacterial species. To establish an infection, EHEC strains have to modulate their gene expression according to the GI tract environment. In order to explore the interspecies interactions between EHEC and an human intestinal commensal, the global gene expression profile was determined of EHEC O103:H25 (EHEC NIPH-11060424) co-cultured with B. thetaiotaomicron (CCUG 10774) or grown in the presence of spent medium from B. thetaiotaomicron. Microarray analysis revealed that approximately 1% of the EHEC NIPH-11060424 genes were significantly up-regulated both in co-culture (30 genes) and in the presence of spent medium (44 genes), and that the affected genes differed between the two conditions. In co-culture, genes encoding structural components of the type three secretion system were among the most affected genes with an almost 4-fold up-regulation, while the most affected genes in spent medium were involved in chemotaxis and were more than 3-fold up-regulated. The operons for type three secretion system (TTSS) are located on the Locus of enterocyte effacement (LEE) pathogenicity island, and qPCR showed that genes of all five operons (LEE1-LEE5) were up-regulated. Moreover, an increased adherence to HeLa cells was observed in EHEC NIPH-11060424 exposed to B. thetaiotaomicron. Expression of stx2 genes, encoding the main virulence factor of EHEC, was down-regulated in both conditions (co-culture/spent medium). These results show that expression of EHEC genes involved in colonization and virulence is modulated in response to direct interspecies contact between cells, or to diffusible factors released from B. thetaiotaomicron. Such interspecies interactions could allow the pathogen to recognize its predilection site and modulate its behaviour accordingly, thus increasing the efficiency of colonization of the colon mucosa, facilitating its persistence and increasing its virulence potential.
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Affiliation(s)
- Hildegunn Iversen
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Toril Lindbäck
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Trine M. L’Abée-Lund
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Norbert Roos
- Department of Biosciences, University of Oslo, Oslo, Norway
| | - Marina Aspholm
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
| | - Lotte Stenfors Arnesen
- Department of Food Safety and Infection Biology, Norwegian University of Life Sciences, Oslo, Norway
- * E-mail:
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Mohsin M, Guenther S, Schierack P, Tedin K, Wieler LH. Probiotic Escherichia coli Nissle 1917 reduces growth, Shiga toxin expression, release and thus cytotoxicity of enterohemorrhagic Escherichia coli. Int J Med Microbiol 2014; 305:20-6. [PMID: 25465158 DOI: 10.1016/j.ijmm.2014.10.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 08/24/2014] [Accepted: 10/18/2014] [Indexed: 01/03/2023] Open
Abstract
Due to increased release or production of Shiga toxin by Enterohemorrhagic Escherichia coli (EHEC) after exposure to antimicrobial agents, the role of antimicrobial agents in EHEC mediated infections remains controversial. Probiotics are therefore rapidly gaining interest as an alternate therapeutic option. The well-known probiotic strain Escherichia coli Nissle 1917 (EcN) was tested in vitro to determine its probiotic effects on growth, Shiga toxin (Stx) gene expression, Stx amount and associated cytotoxicity on the most important EHEC strains of serotype O104:H4 and O157:H7. Following co-culture of EcN:EHEC in broth for 4 and 24 h, the probiotic effects on EHEC growth, toxin gene expression, Stx amount and cytotoxicity were determined using quantitative real time-PCR, Stx-ELISA and Vero cytotoxicity assays. Probiotic EcN strongly reduced EHEC numbers (cfu) of O104:H4 up to (68%) and O157:H7 to (72.2%) (p<0.05) in LB broth medium whereas the non-probiotic E. coli strain MG1655 had no effect on EHEC growth. The level of stx expression was significantly down-regulated, particularly for the stx2a gene. The stx down-regulation in EcN co-culture was not due to reduced numbers of EHEC. A significant inhibition in Stx amounts and cytotoxicity were also observed in sterile supernatants of EcN:EHEC co-cultures. These findings indicate that probiotic EcN displays strong inhibitory effects on growth, Shiga toxin gene expression, amount and cytotoxicity of EHEC strains. Thus, EcN may be considered as a putative therapeutic candidate, in particular against EHEC O104:H4 and O157:H7.
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Affiliation(s)
- Mashkoor Mohsin
- Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany; Institute of Microbiology, University of Agriculture, Faisalabad, Pakistan
| | - Sebastian Guenther
- Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany
| | - Peter Schierack
- Faculty of Natural Sciences, Brandenburg Technical University Cottbus-Senftenberg, Senftenberg, Germany
| | - Karsten Tedin
- Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany
| | - Lothar H Wieler
- Institute of Microbiology and Epizootics, Centre for Infection Medicine, Freie Universität Berlin, Berlin, Germany.
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Transcriptome analysis of Escherichia coli O157:H7 grown in vitro in the sterile-filtrated cecal content of human gut microbiota associated rats reveals an adaptive expression of metabolic and virulence genes. Microbes Infect 2014; 17:23-33. [PMID: 25290220 DOI: 10.1016/j.micinf.2014.09.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 09/19/2014] [Accepted: 09/19/2014] [Indexed: 12/12/2022]
Abstract
In developed countries, enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a leading cause of bloody diarrhea and renal failures in human. Understanding strategies employed by EHEC to colonize the intestine is of major importance since to date no cure exists to eradicate the pathogen. In this study, the adaptive response of EHEC to the intestinal milieu conditioned by a human microbiota was examined. A transcriptomic analysis was performed on the EHEC strain EDL933 incubated in vitro in the sterile-filtrated cecal content of human microbiota-associated rats (HMC) compared with EDL933 incubated in the sterile-filtrated cecal content of germ-free rat (GFC). EDL933 switches from a glycolytic metabolic profile in the GFC to an anaplerotic metabolic profile in HMC. The expression of several catabolism genes was strongly affected such as those involved in the utilization of sugars, glycerol, N-acetylneuraminic acid, amino acids and secondary metabolites. Interestingly, expression level of critical EHEC O157:H7 virulence genes including genes from the locus of enterocyte effacement was reduced in HMC. Altogether, these results contribute to the understanding of EHEC adaptive response to a digestive content and highlight the ability of the microbiota to repress EHEC virulence gene expression.
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Abstract
ABSTRACT
The gastrointestinal tract of mammals is home to a plethora of microbial species that comprise the microbiota. The role of the microbiota in human health is at the forefront of science in recent years, because it is now appreciated that this intricate microbe-host association shapes the host's immune response and physiology. Many diseases are associated with changes in the microbiota, called dysbiosis. Dysbiosis is associated with obesity, metabolic syndromes, inflammatory bowel-disease, inflammatory bowel syndrome, cancer, diabetes, allergies, and autism. The microbiota is largely regarded as a barrier to enteric infections, such as with enterohemorrhagic
Escherichia coli
(EHEC). However, the interactions between pathogens and the microbiota are largely unknown, as is how these interactions influence the outcome of enteric disease. The microbial composition of the gastrointestinal tract shapes the landscape in which EHEC survives within the host. This organism competes for nutrients derived from the host diet, liberates additional resources from dietary and host sources, and produces signaling molecules sensed by EHEC to direct gene expression. To successfully colonize the recto-anal junction of a ruminant, the EHEC reservoir, or the colon of a human, an accidental host, EHEC must alter its physiology to survive within the host digestive tract. In this article, we explore the classes of molecules produced or modified by the microbiota that appear to be instrumental in governing virulence gene expression of EHEC. We also explore how interaction with different microbiotas influences EHEC infectivity and host interaction.
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Yurist-Doutsch S, Arrieta MC, Vogt SL, Finlay BB. Gastrointestinal microbiota-mediated control of enteric pathogens. Annu Rev Genet 2014; 48:361-82. [PMID: 25251855 DOI: 10.1146/annurev-genet-120213-092421] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The gastrointestinal (GI) microbiota is a complex community of microorganisms residing within the mammalian gastrointestinal tract. The GI microbiota is vital to the development of the host immune system and plays a crucial role in human health and disease. The composition of the GI microbiota differs immensely among individuals yet specific shifts in composition and diversity have been linked to inflammatory bowel disease, obesity, atopy, and susceptibility to infection. In this review, we describe the GI microbiota and its role in enteric diseases caused by pathogenic Escherichia coli, Salmonella enterica, and Clostridium difficile. We discuss the central role of the GI microbiota in protective immunity, resistance to enteric pathogens, and resolution of enteric colitis.
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Affiliation(s)
- Sophie Yurist-Doutsch
- Michael Smith Laboratories, The University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4; , , ,
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43
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Differential Expression of Virulence and Stress Fitness Genes during Interaction betweenListeria monocytogenesandBifidobacterium longum. Biosci Biotechnol Biochem 2014; 76:699-704. [DOI: 10.1271/bbb.110832] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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44
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Tran SL, Billoud L, Lewis SB, Phillips AD, Schüller S. Shiga toxin production and translocation during microaerobic human colonic infection with Shiga toxin-producing E. coli O157:H7 and O104:H4. Cell Microbiol 2014; 16:1255-66. [PMID: 24612002 PMCID: PMC4231982 DOI: 10.1111/cmi.12281] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 01/31/2014] [Accepted: 02/14/2014] [Indexed: 12/30/2022]
Abstract
Haemolytic uraemic syndrome caused by Shiga toxin-producing E. coli (STEC) is dependent on release of Shiga toxins (Stxs) during intestinal infection and subsequent absorption into the bloodstream. An understanding of Stx-related events in the human gut is limited due to lack of suitable experimental models. In this study, we have used a vertical diffusion chamber system with polarized human colon carcinoma cells to simulate the microaerobic (MA) environment in the human intestine and investigate its influence on Stx release and translocation during STEC O157:H7 and O104:H4 infection. Stx2 was the major toxin type released during infection. Whereas microaerobiosis significantly reduced bacterial growth as well as Stx production and release into the medium, Stx translocation across the epithelial monolayer was enhanced under MA versus aerobic conditions. Increased Stx transport was dependent on STEC infection and occurred via a transcellular pathway other than macropinocytosis. While MA conditions had a similar general effect on Stx release and absorption during infection with STEC O157:H7 and O104:H4, both serotypes showed considerable differences in colonization, Stx production, and Stx translocation which suggest alternative virulence strategies. Taken together, our study suggests that the MA environment in the human colon may modulate Stx-related events and enhance Stx absorption during STEC infection.
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Affiliation(s)
- Seav-Ly Tran
- Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich, UK; Gut Health and Food Safety Programme, Institute of Food Research, Norwich Research Park, Norwich, UK
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45
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Iron supplementation promotes gut microbiota metabolic activity but not colitis markers in human gut microbiota-associated rats. Br J Nutr 2014; 111:2135-45. [DOI: 10.1017/s000711451400021x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The global prevalence of Fe deficiency is high and a common corrective strategy is oral Fe supplementation, which may affect the commensal gut microbiota and gastrointestinal health. The aim of the present study was to investigate the impact of different dietary Fe concentrations on the gut microbiota and gut health of rats inoculated with human faecal microbiota. Rats (8 weeks old, n 40) were divided into five (n 8 each) groups and fed diets differing only in Fe concentration during an Fe-depletion period (12 weeks) and an Fe-repletion period (4 weeks) as follows: (1) Fe-sufficient diet throughout the study period; (2) Fe-sufficient diet followed by 70 mg Fe/kg diet; (3) Fe-depleted diet throughout the study period; (4) Fe-depleted diet followed by 35 mg Fe/kg diet; (5) Fe-depleted diet followed by 70 mg Fe/kg diet. Faecal and caecal samples were analysed for gut microbiota composition (quantitative PCR and pyrosequencing) and bacterial metabolites (HPLC), and intestinal tissue samples were investigated histologically. Fe depletion did not significantly alter dominant populations of the gut microbiota and did not induce Fe-deficiency anaemia in the studied rats. Provision of the 35 mg Fe/kg diet after feeding an Fe-deficient diet significantly increased the abundance of dominant bacterial groups such as Bacteroides spp. and Clostridium cluster IV members compared with that of an Fe-deficient diet. Fe supplementation increased gut microbial butyrate concentration 6-fold compared with Fe depletion and did not affect histological colitis scores. The present results suggest that Fe supplementation enhances the concentration of beneficial gut microbiota metabolites and thus may contribute to gut health.
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Abstract
Commensal bacteria inhabit mucosal and epidermal surfaces in mice and humans, and have effects on metabolic and immune pathways in their hosts. Recent studies indicate that the commensal microbiota can be manipulated to prevent and even to cure infections that are caused by pathogenic bacteria, particularly pathogens that are broadly resistant to antibiotics, such as vancomycin-resistant Enterococcus faecium, Gram-negative Enterobacteriaceae and Clostridium difficile. In this Review, we discuss how immune- mediated colonization resistance against antibiotic-resistant intestinal pathogens is influenced by the composition of the commensal microbiota. We also review recent advances characterizing the ability of different commensal bacterial families, genera and species to restore colonization resistance to intestinal pathogens in antibiotic-treated hosts.
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Promoter sequence of Shiga toxin 2 (Stx2) is recognized in vivo, leading to production of biologically active Stx2. mBio 2013; 4:e00501-13. [PMID: 24085779 PMCID: PMC3791892 DOI: 10.1128/mbio.00501-13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Shiga toxins (Stx) are the main agent responsible for the development of hemolytic-uremic syndrome (HUS), the most severe and life-threatening systemic complication of infection with enterohemorrhagic Escherichia coli (EHEC) strains. We previously described Stx2 expression by eukaryotic cells after they were transfected in vitro with the stx2 gene cloned into a prokaryotic plasmid (pStx2). The aim of this study was to evaluate whether mammalian cells were also able to express Stx2 in vivo after pStx2 injection. Mice were inoculated by hydrodynamics-based transfection (HBT) with pStx2. We studied the survival, percentage of polymorphonuclear leukocytes in plasma, plasma urea levels, and histology of the kidneys and the brains of mice. Mice displayed a lethal dose-related response to pStx2. Stx2 mRNA was recovered from the liver, and Stx2 cytotoxic activity was observed in plasma of mice injected with pStx2. Stx2 was detected by immunofluorescence in the brains of mice inoculated with pStx2, and markers of central nervous system (CNS) damage were observed, including increased expression of glial fibrillary acidic protein (GFAP) and fragmentation of NeuN in neurons. Moreover, anti-Stx2B-immunized mice were protected against pStx2 inoculation. Our results show that Stx2 is expressed in vivo from the wild stx2 gene, reproducing pathogenic damage induced by purified Stx2 or secondary to EHEC infection. Enterohemorrhagic Shiga toxin (Stx)-producing Escherichia coli (EHEC) infections are a serious public health problem, and Stx is the main pathogenic agent associated with typical hemolytic-uremic syndrome (HUS). In contrast to the detailed information describing the molecular basis for EHEC adherence to epithelial cells, very little is known about how Stx is released from bacteria in the gut, reaching its target tissues, mainly the kidney and central nervous system (CNS). In order to develop an efficient treatment for EHEC infections, it is necessary to understand the mechanisms involved in Stx expression. In this regard, the present study demonstrates that mammals can synthesize biologically active Stx using the natural promoter associated with the Stx-converting bacteriophage genome. These results could impact the comprehension of EHEC HUS, since local eukaryotic cells transduced and/or infected by bacteriophage encoding Stx2 could be an alternative source of Stx production.
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48
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Ibarra C, Amaral MM, Palermo MS. Advances in pathogenesis and therapy of hemolytic uremic syndrome caused by Shiga toxin-2. IUBMB Life 2013; 65:827-35. [PMID: 24014500 DOI: 10.1002/iub.1206] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 08/06/2013] [Indexed: 11/12/2022]
Abstract
Shiga toxin (Stx) producing Escherichia coli (STEC) is responsible to bloody diarrhea (hemorrhagic colitis) and the hemolytic uremic syndrome (HUS). STEC strains carry inducible lambda phages integrated into their genomes that encode Stx 1 and/or 2, with several allelic variants each one. O157:H7 is the serotype that was documented in the vast majority of HUS cases although non-O157 serotypes have been increasingly reported to account for HUS cases. However, the outbreak that occurred in central Europe during late spring of 2011 showed that the pathogen was E. coli O104:H4. More than 4,000 persons were infected mainly in Germany, and it produced more than 900 cases of HUS resulting in 54 deaths. E. coli O104:H4 is a hybrid organism that combines some of the virulence genes of STEC and enteroaggregative E. coli specially production of Stx2 and the adherence mechanisms to intestinal epithelium. The differences in the epidemiology and presentation of E. coli pathogen meant a challenge for public health and scientific research to increase the knowledge of HUS-pathophysiology and to improve available therapies to treat HUS.
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Affiliation(s)
- Cristina Ibarra
- Laboratorio de Fisiopatogenia, Departamento de Fisiología, Facultad de Medicina, Universidad, de Buenos Aires, Argentina
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49
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Ichimura M, Uchida K, Nakayama-Imaohji H, Hirakawa H, Tada T, Morita H, Yasutomo K, Okazaki K, Kuwahara T. Mariner-based transposon mutagenesis forBacteroidesspecies. J Basic Microbiol 2013; 54:558-67. [DOI: 10.1002/jobm.201200763] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/26/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Minoru Ichimura
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
- Department of Immunology and Parasitology; Institute of Health Biosciences, The University of Tokushima Graduate School; Kuramoto-cho Tokushima Japan
| | - Keiko Uchida
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
- Department of Applied Bioscience; Faculty of Agriculture, Kagawa University; Miki Kagawa Japan
| | | | - Hideki Hirakawa
- Kazusa DNA Research Institute, Kazusa-Kamatari; Kisarazu Chiba Japan
| | - Tomoyo Tada
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
| | - Hidetoshi Morita
- School of Veterinary Medicine; Azabu University; Fuchinobe Sagamihara Japan
| | - Koji Yasutomo
- Department of Immunology and Parasitology; Institute of Health Biosciences, The University of Tokushima Graduate School; Kuramoto-cho Tokushima Japan
| | - Katsuichiro Okazaki
- Department of Applied Bioscience; Faculty of Agriculture, Kagawa University; Miki Kagawa Japan
| | - Tomomi Kuwahara
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
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Barnett Foster D. Modulation of the enterohemorrhagic E. coli virulence program through the human gastrointestinal tract. Virulence 2013; 4:315-23. [PMID: 23552827 PMCID: PMC3710334 DOI: 10.4161/viru.24318] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Enteric pathogens must not only survive passage through the gastrointestinal tract but must also coordinate expression of virulence determinants in response to localized microenvironments with the host. Enterohemorrhagic Escherichia coli (EHEC), a serious food and waterborne human pathogen, is well equipped with an arsenal of molecular factors that allows it to survive passage through the gastrointestinal tract and successfully colonize the large intestine. This review will explore how EHEC responds to various environmental cues associated with particular microenvironments within the host and how it employs these cues to modulate virulence factor expression, with a view to developing a conceptual framework for understanding modulation of EHEC’s virulence program in response to the host. In vitro studies offer significant insights into the role of individual environmental cues but in vivo studies using animal models as well as data from natural infections will ultimately provide a more comprehensive picture of the highly regulated virulence program of this pathogen.
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Affiliation(s)
- Debora Barnett Foster
- Department of Chemistry and Biology, Faculty of Science, Ryerson University, Toronto, ONT, Canada.
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