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Chan JL, Wu S, Geis AL, Chan GV, Gomes TAM, Beck SE, Wu X, Fan H, Tam AJ, Chung L, Ding H, Wang H, Pardoll DM, Housseau F, Sears CL. Non-toxigenic Bacteroides fragilis (NTBF) administration reduces bacteria-driven chronic colitis and tumor development independent of polysaccharide A. Mucosal Immunol 2019; 12:164-177. [PMID: 30279518 PMCID: PMC6510666 DOI: 10.1038/s41385-018-0085-5] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 08/01/2018] [Accepted: 08/16/2018] [Indexed: 02/07/2023]
Abstract
Polysaccharide A (PSA), an immunogenic capsular component of non-toxigenic Bacteroides fragilis (NTBF) strain NCTC 9343, is reported to promote mucosal immune development and suppress colitis. Contrastingly, enterotoxigenic Bacteroides fragilis (ETBF) is highly associated with inflammatory bowel disease (IBD) and colorectal cancer (CRC), rapidly inducing IL-17-dependent murine colitis and tumorigenesis. In specific-pathogen-free (SPF) C57BL/6 wild-type (WT) and multiple intestinal neoplasia (MinApc716+/-) mice, we show that sequential treatment of the NTBF strain, 9343, followed by the ETBF strain, 86-5443-2-2 (86), diminished colitis and tumorigenesis. Mice treated simultaneously with 9343 and 86 exhibited both severe colitis and tumorigenesis. Abrogated disease severity in sequentially treated mice was attributed to 9343 strain dominance and decreased IL-17A, but 86 colonization prior to or simultaneous with 9343 mitigated the anti-inflammatory effect of 9343. Remarkably, 9343-mediated protection was independent of PSA, as sequentially treated mice receiving ΔPSA 9343 exhibited similar protection. Further, SPF WT and Min mice colonized with PSA-competent or PSA-deficient 9343 exhibited similar IL-10, IL-17, and IFN-γ responses. Treatment of 86-colonized mice with 9343 failed to disrupt 86 pathogenesis. Our findings demonstrate that 9343 colonization, independent of PSA, offers prophylaxis against colitis-inducing 86 but may not be a valid therapy once colitis is established.
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Affiliation(s)
- June L Chan
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Shaoguang Wu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Abby L Geis
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Department of Microbiology and Immunology, Arkansas College of Osteopathic Medicine, Fort Smith, Arkansas, USA
| | - Gabrielle V Chan
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Talles A M Gomes
- Medical School, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil
| | - Sarah E Beck
- Department of Molecular and Comparative Pathobiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Xinqun Wu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hongni Fan
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ada J Tam
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liam Chung
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Translational Tissue Engineering Center, Wilmer Eye Institute and Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Hua Ding
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Hao Wang
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Drew M Pardoll
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Franck Housseau
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Cynthia L Sears
- Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA.
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins University, Baltimore, MD, USA.
- Bloomberg-Kimmel Institute for Cancer Immunotherapy, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Genomic Diversity of Enterotoxigenic Strains of Bacteroides fragilis. PLoS One 2016; 11:e0158171. [PMID: 27348220 PMCID: PMC4922554 DOI: 10.1371/journal.pone.0158171] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/10/2016] [Indexed: 12/12/2022] Open
Abstract
Enterotoxigenic (ETBF) strains of Bacteroides fragilis are the subset of strains that secrete a toxin called fragilysin (Bft). Although ETBF strains are known to cause diarrheal disease and have recently been associated with colorectal cancer, they have not been well characterized. By sequencing the complete genome of four ETBF strains, we found that these strains exhibit considerable variation at the genomic level. Only a small number of genes that are located primarily in the Bft pathogenicity island (BFT PAI) and the flanking CTn86 conjugative transposon are conserved in all four strains and a fifth strain whose genome was previously sequenced. Interestingly, phylogenetic analysis strongly suggests that the BFT PAI was acquired by non-toxigenic (NTBF) strains multiple times during the course of evolution. At the phenotypic level, we found that the ETBF strains were less fit than the NTBF strain NCTC 9343 and were susceptible to a growth-inhibitory protein that it produces. The ETBF strains also showed a greater tendency to form biofilms, which may promote tumor formation, than NTBF strains. Although the genomic diversity of ETBF strains raises the possibility that they vary in their pathogenicity, our experimental results also suggest that they share common properties that are conferred by different combinations of non-universal genetic elements.
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Wilson MM, Anderson DE, Bernstein HD. Analysis of the outer membrane proteome and secretome of Bacteroides fragilis reveals a multiplicity of secretion mechanisms. PLoS One 2015; 10:e0117732. [PMID: 25658944 PMCID: PMC4319957 DOI: 10.1371/journal.pone.0117732] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/31/2014] [Indexed: 01/28/2023] Open
Abstract
Bacteroides fragilis is a widely distributed member of the human gut microbiome and an opportunistic pathogen. Cell surface molecules produced by this organism likely play important roles in colonization, communication with other microbes, and pathogenicity, but the protein composition of the outer membrane (OM) and the mechanisms used to transport polypeptides into the extracellular space are poorly characterized. Here we used LC-MS/MS to analyze the OM proteome and secretome of B. fragilis NCTC 9343 grown under laboratory conditions. Of the 229 OM proteins that we identified, 108 are predicted to be lipoproteins, and 61 are predicted to be TonB-dependent transporters. Based on their proximity to genes encoding TonB-dependent transporters, many of the lipoprotein genes likely encode proteins involved in nutrient or small molecule uptake. Interestingly, protease accessibility and biotinylation experiments indicated that an unusually large fraction of the lipoproteins are cell-surface exposed. We also identified three proteins that are members of a novel family of autotransporters, multiple potential type I protein secretion systems, and proteins that appear to be components of a type VI secretion apparatus. The secretome consisted of lipoproteins and other proteins that might be substrates of the putative type I or type VI secretion systems. Our proteomic studies show that B. fragilis differs considerably from well-studied Gram-negative bacteria such as Escherichia coli in both the spectrum of OM proteins that it produces and the range of secretion strategies that it utilizes.
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Affiliation(s)
- Marlena M. Wilson
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States of America
| | - D. Eric Anderson
- Advanced Mass Spectrometry Facility, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States of America
| | - Harris D. Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States of America
- * E-mail:
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Chatzidaki-Livanis M, Coyne MJ, Comstock LE. An antimicrobial protein of the gut symbiont Bacteroides fragilis with a MACPF domain of host immune proteins. Mol Microbiol 2014; 94:1361-74. [PMID: 25339613 DOI: 10.1111/mmi.12839] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2014] [Indexed: 12/31/2022]
Abstract
Bacteroidales are the most abundant Gram-negative bacteria of the human intestinal microbiota comprising more than half of the bacteria in many individuals. Some of the factors that these bacteria use to establish and maintain themselves in this ecosystem are beginning to be identified. However, ecological competition, especially interference competition where one organism directly harms another, is largely unexplored. To begin to understand the relevance of this ecological principle as it applies to these abundant gut bacteria and factors that may promote such competition, we screened Bacteroides fragilis for the production of antimicrobial molecules. We found that the production of extracellularly secreted antimicrobial molecules is widespread in this species. The first identified molecule, described in this manuscript, contains a membrane attack complex/perforin (MACPF) domain present in host immune molecules that kill bacteria and virally infected cells by pore formation, and mutations affecting key residues of this domain abrogated its activity. This antimicrobial molecule, termed BSAP-1, is secreted from the cell in outer membrane vesicles and no additional proteins are required for its secretion, processing or immunity of the producing cell. This study provides the first insight into secreted molecules that promote competitive interference among Bacteroidales strains of the human gut.
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Affiliation(s)
- Maria Chatzidaki-Livanis
- Division of Infectious Diseases, Brigham and Women's Hospital, Harvard Medical School, 181 Longwood Avenue, Boston, MA, 02115, USA
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