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Sijmons D, Collett S, Soliman C, Guy AJ, Scott AM, Durrant LG, Elbourne A, Walduck AK, Ramsland PA. Probing the expression and adhesion of glycans involved in Helicobacter pylori infection. Sci Rep 2024; 14:8587. [PMID: 38615147 PMCID: PMC11016089 DOI: 10.1038/s41598-024-59234-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 04/08/2024] [Indexed: 04/15/2024] Open
Abstract
Helicobacter pylori infects approximately half the human population and has an unusual infective niche of the human stomach. Helicobacter pylori is a major cause of gastritis and has been classified as a group 1 carcinogen by the WHO. Treatment involves triple or quadruple antibiotic therapy, but antibiotic resistance is becoming increasingly prevalent. Helicobacter pylori expresses certain blood group related antigens (Lewis system) as a part of its lipopolysaccharide (LPS), which is thought to assist in immune evasion. Additionally, H. pylori LPS participates in adhesion to host cells alongside several adhesion proteins. This study profiled the carbohydrates of H. pylori reference strains (SS1 and 26695) using monoclonal antibodies (mAbs) and lectins, identifying interactions between two carbohydrate-targeting mAbs and multiple lectins. Atomic force microscopy (AFM) scans were used to probe lectin and antibody interactions with the bacterial surfaces. The selected mAb and lectins displayed an increased adhesive force over the surface of the curved H. pylori rods. Furthermore, this study demonstrates the ability of anti-carbohydrate antibodies to reduce the adhesion of H. pylori 26695 to human gastric adenocarcinoma cells via AFM. Targeting bacterial carbohydrates to disrupt crucial adhesion and immune evasion mechanisms represents a promising strategy for combating H. pylori infection.
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Affiliation(s)
- Daniel Sijmons
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
| | - Simon Collett
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
- Department of Paediatrics, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Caroline Soliman
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, 3000, Australia
| | - Andrew J Guy
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
- ZiP Diagnostics, Collingwood, VIC, 3066, Australia
| | - Andrew M Scott
- Olivia Newton-John Cancer Research Institute and School of Cancer Medicine, La Trobe University, Melbourne, VIC, Australia
- Department of Molecular Imaging and Therapy, Austin Health and Faculty of Medicine, The University of Melbourne, Melbourne, VIC, Australia
| | - Lindy G Durrant
- Scancell Limited, University of Nottingham Biodiscovery Institute, Nottingham, UK
- Division of Cancer and Stem Cells, School of Medicine, University of Nottingham Biodiscovery Institute, Nottingham, UK
| | - Aaron Elbourne
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia
| | - Anna K Walduck
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia.
- Rural Health Research Institute, Charles Sturt University, Orange, NSW, 2800, Australia.
| | - Paul A Ramsland
- School of Science, RMIT University, Melbourne, VIC, 3000, Australia.
- Department of Immunology, Monash University, Melbourne, VIC, 3004, Australia.
- Department of Surgery, Austin Health, The University of Melbourne, Heidelberg, VIC, 3084, Australia.
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2
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Dardelle F, Phelip C, Darabi M, Kondakova T, Warnet X, Combret E, Juranville E, Novikov A, Kerzerho J, Caroff M. Diversity, Complexity, and Specificity of Bacterial Lipopolysaccharide (LPS) Structures Impacting Their Detection and Quantification. Int J Mol Sci 2024; 25:3927. [PMID: 38612737 PMCID: PMC11011966 DOI: 10.3390/ijms25073927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/21/2024] [Accepted: 03/23/2024] [Indexed: 04/14/2024] Open
Abstract
Endotoxins are toxic lipopolysaccharides (LPSs), extending from the outer membrane of Gram-negative bacteria and notorious for their toxicity and deleterious effects. The comparison of different LPSs, isolated from various Gram-negative bacteria, shows a global similar architecture corresponding to a glycolipid lipid A moiety, a core oligosaccharide, and outermost long O-chain polysaccharides with molecular weights from 2 to 20 kDa. LPSs display high diversity and specificity among genera and species, and each bacterium contains a unique set of LPS structures, constituting its protective external barrier. Some LPSs are not toxic due to their particular structures. Different, well-characterized, and highly purified LPSs were used in this work to determine endotoxin detection rules and identify their impact on the host. Endotoxin detection is a major task to ensure the safety of human health, especially in the pharma and food sectors. Here, we describe the impact of different LPS structures obtained under different bacterial growth conditions on selective LPS detection methods such as LAL, HEK-blue TLR-4, LC-MS2, and MALDI-MS. In these various assays, LPSs were shown to respond differently, mainly attributable to their lipid A structures, their fatty acid numbers and chain lengths, the presence of phosphate groups, and their possible substitutions.
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Affiliation(s)
- Flavien Dardelle
- LPS-BioSciences, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (F.D.); (M.D.); (E.J.)
| | - Capucine Phelip
- HEPHAISTOS-Pharma, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (C.P.); (A.N.); (J.K.)
| | - Maryam Darabi
- LPS-BioSciences, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (F.D.); (M.D.); (E.J.)
| | - Tatiana Kondakova
- LPS-BioSciences, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (F.D.); (M.D.); (E.J.)
| | - Xavier Warnet
- LPS-BioSciences, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (F.D.); (M.D.); (E.J.)
| | - Edyta Combret
- LPS-BioSciences, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (F.D.); (M.D.); (E.J.)
| | - Eugenie Juranville
- LPS-BioSciences, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (F.D.); (M.D.); (E.J.)
| | - Alexey Novikov
- HEPHAISTOS-Pharma, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (C.P.); (A.N.); (J.K.)
| | - Jerome Kerzerho
- HEPHAISTOS-Pharma, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (C.P.); (A.N.); (J.K.)
| | - Martine Caroff
- LPS-BioSciences, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (F.D.); (M.D.); (E.J.)
- HEPHAISTOS-Pharma, Bâtiment 440, Université de Paris-Saclay, 91400 Orsay, France; (C.P.); (A.N.); (J.K.)
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3
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Bell A, Severi E, Owen CD, Latousakis D, Juge N. Biochemical and structural basis of sialic acid utilization by gut microbes. J Biol Chem 2023; 299:102989. [PMID: 36758803 PMCID: PMC10017367 DOI: 10.1016/j.jbc.2023.102989] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 02/01/2023] [Accepted: 02/02/2023] [Indexed: 02/10/2023] Open
Abstract
The human gastrointestinal (GI) tract harbors diverse microbial communities collectively known as the gut microbiota that exert a profound impact on human health and disease. The repartition and availability of sialic acid derivatives in the gut have a significant impact on the modulation of gut microbes and host susceptibility to infection and inflammation. Although N-acetylneuraminic acid (Neu5Ac) is the main form of sialic acids in humans, the sialic acid family regroups more than 50 structurally and chemically distinct modified derivatives. In the GI tract, sialic acids are found in the terminal location of mucin glycan chains constituting the mucus layer and also come from human milk oligosaccharides in the infant gut or from meat-based foods in adults. The repartition of sialic acid in the GI tract influences the gut microbiota composition and pathogen colonization. In this review, we provide an update on the mechanisms underpinning sialic acid utilization by gut microbes, focusing on sialidases, transporters, and metabolic enzymes.
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Affiliation(s)
- Andrew Bell
- Quadram Institute Bioscience, Gut Microbes and Health Institute Strategic Programme, Norwich, United Kingdom
| | - Emmanuele Severi
- Microbes in Health and Disease, Biosciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - C David Owen
- Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, United Kingdom
| | - Dimitrios Latousakis
- Quadram Institute Bioscience, Gut Microbes and Health Institute Strategic Programme, Norwich, United Kingdom
| | - Nathalie Juge
- Quadram Institute Bioscience, Gut Microbes and Health Institute Strategic Programme, Norwich, United Kingdom.
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4
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Sijmons D, Guy AJ, Walduck AK, Ramsland PA. Helicobacter pylori and the Role of Lipopolysaccharide Variation in Innate Immune Evasion. Front Immunol 2022; 13:868225. [PMID: 35634347 PMCID: PMC9136243 DOI: 10.3389/fimmu.2022.868225] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 04/04/2022] [Indexed: 11/30/2022] Open
Abstract
Helicobacter pylori is an important human pathogen that infects half the human population and can lead to significant clinical outcomes such as acute and chronic gastritis, duodenal ulcer, and gastric adenocarcinoma. To establish infection, H. pylori employs several mechanisms to overcome the innate and adaptive immune systems. H. pylori can modulate interleukin (IL) secretion and innate immune cell function by the action of several virulence factors such as VacA, CagA and the type IV secretion system. Additionally, H. pylori can modulate local dendritic cells (DC) negatively impacting the function of these cells, reducing the secretion of immune signaling molecules, and influencing the differentiation of CD4+ T helper cells causing a bias to Th1 type cells. Furthermore, the lipopolysaccharide (LPS) of H. pylori displays a high degree of phase variation and contains human blood group carbohydrate determinants such as the Lewis system antigens, which are proposed to be involved in molecular mimicry of the host. Lastly, the H. pylori group of outer membrane proteins such as BabA play an important role in attachment and interaction with host Lewis and other carbohydrate antigens. This review examines the various mechanisms that H. pylori utilises to evade the innate immune system as well as discussing how the structure of the H. pylori LPS plays a role in immune evasion.
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Affiliation(s)
- Daniel Sijmons
- School of Science, RMIT University, Melbourne, VIC, Australia
| | - Andrew J. Guy
- School of Science, RMIT University, Melbourne, VIC, Australia
- ZiP Diagnostics, Collingwood, VIC, Australia
| | - Anna K. Walduck
- School of Science, RMIT University, Melbourne, VIC, Australia
| | - Paul A. Ramsland
- School of Science, RMIT University, Melbourne, VIC, Australia
- Department of Immunology, Monash University, Melbourne, VIC, Australia
- Department of Surgery, Austin Health, University of Melbourne, Heidelberg, VIC, Australia
- *Correspondence: Paul A. Ramsland,
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5
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Lima de Souza Gonçalves V, Cordeiro Santos ML, Silva Luz M, Santos Marques H, de Brito BB, França da Silva FA, Souza CL, Oliveira MV, de Melo FF. From Helicobacter pylori infection to gastric cancer: Current evidence on the immune response. World J Clin Oncol 2022; 13:186-199. [PMID: 35433296 PMCID: PMC8966509 DOI: 10.5306/wjco.v13.i3.186] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/31/2021] [Accepted: 02/15/2022] [Indexed: 02/06/2023] Open
Abstract
Gastric cancer (GC) is the result of a multifactorial process whose main components are infection by Helicobacter pylori (H. pylori), bacterial virulence factors, host immune response and environmental factors. The development of the neoplastic microenvironment also depends on genetic and epigenetic changes in oncogenes and tumor suppressor genes, which results in deregulation of cell signaling pathways and apoptosis process. This review summarizes the main aspects of the pathogenesis of GC and the immune response involved in chronic inflammation generated by H. pylori.
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Affiliation(s)
| | - Maria Luísa Cordeiro Santos
- Universidade Federal da Bahia, Instituto Multidisciplinar em Saúde, Vitória da Conquista 45029-094, Bahia, Brazil
| | - Marcel Silva Luz
- Universidade Federal da Bahia, Instituto Multidisciplinar em Saúde, Vitória da Conquista 45029-094, Bahia, Brazil
| | - Hanna Santos Marques
- Universidade Estadual do Sudoeste da Bahia, Campus Vitória da Conquista, Vitória da Conquista 45083-900, Bahia, Brazil
| | - Breno Bittencourt de Brito
- Universidade Federal da Bahia, Instituto Multidisciplinar em Saúde, Vitória da Conquista 45029-094, Bahia, Brazil
| | | | - Cláudio Lima Souza
- Universidade Federal da Bahia, Instituto Multidisciplinar em Saúde, Vitória da Conquista 45029-094, Bahia, Brazil
| | - Márcio Vasconcelos Oliveira
- Universidade Federal da Bahia, Instituto Multidisciplinar em Saúde, Vitória da Conquista 45029-094, Bahia, Brazil
| | - Fabrício Freire de Melo
- Universidade Federal da Bahia, Instituto Multidisciplinar em Saúde, Vitória da Conquista 45029-094, Bahia, Brazil
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6
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The Effects of HP0044 and HP1275 Knockout Mutations on the Structure and Function of Lipopolysaccharide in Helicobacter pylori Strain 26695. Biomedicines 2022; 10:biomedicines10010145. [PMID: 35052824 PMCID: PMC8773439 DOI: 10.3390/biomedicines10010145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/06/2022] [Accepted: 01/07/2022] [Indexed: 02/07/2023] Open
Abstract
Helicobacter pylori infection is associated with several gastric diseases, including gastritis, peptic ulcer, gastric adenocarcinoma and mucosa-associated lymphatic tissue (MALT) lymphoma. Due to the prevalence and severeness of H. pylori infection, a thorough understanding of this pathogen is necessary. Lipopolysaccharide, one of the major virulence factors of H. pylori, can exert immunomodulating and immunostimulating functions on the host. In this study, the HP0044 and HP1275 genes were under investigation. These two genes potentially encode GDP-D-mannose dehydratase (GMD) and phosphomannomutase (PMM)/phosphoglucomutase (PGM), respectively, and are involved in the biosynthesis of fucose. HP0044 and HP1275 knockout mutants were generated; both mutants displayed a truncated LPS, suggesting that the encoded enzymes are not only involved in fucose production but are also important for LPS construction. In addition, these two gene knockout mutants exhibited retarded growth, increased surface hydrophobicity and autoaggregation as well as being more sensitive to the detergent SDS and the antibiotic novobiocin. Furthermore, the LPS-defective mutants also had significantly reduced bacterial infection, adhesion and internalization in the in vitro cell line model. Moreover, disruptions of the HP0044 and HP1275 genes in H. pylori altered protein sorting into outer membrane vesicles. The critical roles of HP0044 and HP1275 in LPS biosynthesis, bacterial fitness and pathogenesis make them attractive candidates for drug inventions against H. pylori infection.
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7
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Small RNA mediated gradual control of lipopolysaccharide biosynthesis affects antibiotic resistance in Helicobacter pylori. Nat Commun 2021; 12:4433. [PMID: 34290242 PMCID: PMC8295292 DOI: 10.1038/s41467-021-24689-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 06/28/2021] [Indexed: 01/19/2023] Open
Abstract
The small, regulatory RNA RepG (Regulator of polymeric G-repeats) regulates the expression of the chemotaxis receptor TlpB in Helicobacter pylori by targeting a variable G-repeat in the tlpB mRNA leader. Here, we show that RepG additionally controls lipopolysaccharide (LPS) phase variation by also modulating the expression of a gene (hp0102) that is co-transcribed with tlpB. The hp0102 gene encodes a glycosyltransferase required for LPS O-chain biosynthesis and in vivo colonization of the mouse stomach. The G-repeat length defines a gradual (rather than ON/OFF) control of LPS biosynthesis by RepG, and leads to gradual resistance to a membrane-targeting antibiotic. Thus, RepG-mediated modulation of LPS structure might impact host immune recognition and antibiotic sensitivity, thereby helping H. pylori to adapt and persist in the host. The small RNA RepG modulates expression of chemotaxis receptor TlpB in Helicobacter pylori by targeting a length-variable G-repeat in the tlpB mRNA. Here, Pernitzsch et al. show that RepG also gradually controls lipopolysaccharide biosynthesis, antibiotic susceptibility, and in-vivo colonization of the stomach, by regulating a gene that is co-transcribed with tlpB.
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8
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Wu T, Wu L. The Role and Clinical Implications of the Retinoblastoma (RB)-E2F Pathway in Gastric Cancer. Front Oncol 2021; 11:655630. [PMID: 34136392 PMCID: PMC8201093 DOI: 10.3389/fonc.2021.655630] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 05/07/2021] [Indexed: 12/24/2022] Open
Abstract
Gastric cancer is the most common malignant tumor in the digestive tract, with very high morbidity and mortality in developing countries. The pathogenesis of gastric cancer is a complex biological process mediated by abnormal regulation of proto-oncogenes and tumor suppressor genes. Although there have been some in-depth studies on gastric cancer at the molecular level, the specific mechanism has not been fully elucidated. RB family proteins (including RB, p130, and p107) are involved in cell cycle regulation, a process that largely depends on members of the E2F gene family that encode transcriptional activators and repressors. In gastric cancer, inactivation of the RB-E2F pathway serves as a core transcriptional mechanism that drives cell cycle progression, and is regulated by cyclins, cyclin-dependent kinases, cyclin-dependent kinase inhibitors, p53, Helicobacter pylori and some other upstream molecules. The E2F proteins are encoded by eight genes (i.e. E2F1 to E2F8), each of which may play a specific role in gastric cancer. Interestingly, a single E2F such as E2F1 can activate or repress transcription, and enhance or inhibit cell proliferation, depending on the cell environment. Thus, the function of the E2F transcription factor family is very complex and needs further exploration. Importantly, the presence of H. pylori in stomach mucosa may affect the RB and p53 tumor suppressor systems, thereby promoting the occurrence of gastric cancer. This review aims to summarize recent research progress on important roles of the complex RB-E2F signaling network in the development and effective treatment of gastric cancer.
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Affiliation(s)
| | - Lizhao Wu
- Department of Pathophysiology, College of Basic Medical Sciences, China Medical University, Shenyang, China
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9
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Troudi A, Pagès JM, Brunel JM. Chemical Highlights Supporting the Role of Lipid A in Efficient Biological Adaptation of Gram-Negative Bacteria to External Stresses. J Med Chem 2021; 64:1816-1834. [PMID: 33538159 DOI: 10.1021/acs.jmedchem.0c02185] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The outer membrane (OM) of Gram-negative bacteria provides an efficient barrier against external noxious compounds such as antimicrobial agents. Associated with drug target modification, it contributes to the overall failure of chemotherapy. In the complex OM architecture, Lipid A plays an essential role by anchoring the lipopolysaccharide in the membrane and ensuring the spatial organization between lipids, proteins, and sugars. Currently, the targets of almost all antibiotics are intracellularly located and require translocation across membranes. We report herein an integrated view of Lipid A synthesis, membrane assembly, a structure comparison at the molecular structure level of numerous Gram-negative bacterial species, as well as its recent use as a target for original antibacterial molecules. This review paves the way for a new vision of a key membrane component that acts during bacterial adaptation to environmental stresses and for the development of new weapons against microbial resistance to usual antibiotics.
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Affiliation(s)
- Azza Troudi
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France.,Laboratory of Microorganisms and Active Biomolecules, Department of Biology, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis 1008, Tunisia
| | - Jean Marie Pagès
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France
| | - Jean Michel Brunel
- UMR-MD1, U1261, Aix Marseille Université, INSERM, SSA, MCT, 13385 Marseille, France
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10
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Sanchez‐Garrido J, Slater SL, Clements A, Shenoy AR, Frankel G. Vying for the control of inflammasomes: The cytosolic frontier of enteric bacterial pathogen-host interactions. Cell Microbiol 2020; 22:e13184. [PMID: 32185892 PMCID: PMC7154749 DOI: 10.1111/cmi.13184] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/13/2020] [Accepted: 01/30/2020] [Indexed: 12/13/2022]
Abstract
Enteric pathogen-host interactions occur at multiple interfaces, including the intestinal epithelium and deeper organs of the immune system. Microbial ligands and activities are detected by host sensors that elicit a range of immune responses. Membrane-bound toll-like receptors and cytosolic inflammasome pathways are key signal transducers that trigger the production of pro-inflammatory molecules, such as cytokines and chemokines, and regulate cell death in response to infection. In recent years, the inflammasomes have emerged as a key frontier in the tussle between bacterial pathogens and the host. Inflammasomes are complexes that activate caspase-1 and are regulated by related caspases, such as caspase-11, -4, -5 and -8. Importantly, enteric bacterial pathogens can actively engage or evade inflammasome signalling systems. Extracellular, vacuolar and cytosolic bacteria have developed divergent strategies to subvert inflammasomes. While some pathogens take advantage of inflammasome activation (e.g. Listeria monocytogenes, Helicobacter pylori), others (e.g. E. coli, Salmonella, Shigella, Yersinia sp.) deploy a range of virulence factors, mainly type 3 secretion system effectors, that subvert or inhibit inflammasomes. In this review we focus on inflammasome pathways and their immune functions, and discuss how enteric bacterial pathogens interact with them. These studies have not only shed light on inflammasome-mediated immunity, but also the exciting area of mammalian cytosolic immune surveillance.
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Affiliation(s)
| | | | | | - Avinash R. Shenoy
- Department of Infectious Disease, MRC Centre for Molecular Bacteriology & InfectionImperial College LondonLondonUK
| | - Gad Frankel
- Department of Life SciencesImperial College LondonLondonUK
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Walduck AK, Raghavan S. Immunity and Vaccine Development Against Helicobacter pylori. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1149:257-275. [PMID: 31016627 DOI: 10.1007/5584_2019_370] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Helicobacter pylori is a highly-adapted gastrointestinal pathogen of humans and the immunology of this chronic infection is extremely complex. Despite the availability of antibiotic therapy, the global incidence of H. pylori infection remains high, particularly in low to middle-income nations. Failure of therapy and the spread of antibiotic resistance among the bacteria are significant problems and provide impetus for the development of new therapies and vaccines to treat or prevent gastric ulcer, and gastric carcinoma. The expansion of knowledge on gastric conventional and regulatory T cell responses, and the role of TH17 in chronic gastritis from studies in mouse models and patients have provided valuable insights into how gastritis is initiated and maintained. The development of human challenge models for testing candidate vaccines has meant a unique opportunity to study acute infection, but the field of vaccine development has not progressed as rapidly as anticipated. One clear lesson learned from previous studies is that we need a better understanding of the immune suppressive mechanisms in vivo to be able to design vaccine strategies. There is still an urgent need to identify practical surrogate markers of protection that could be deployed in future field vaccine trials. Important developments in our understanding of the chronic inflammatory response, progress and problems arising from human studies, and an outlook for the future of clinical vaccine trials will be discussed.
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Affiliation(s)
- Anna K Walduck
- School of Science, RMIT University, Melbourne, VIC, Australia.
| | - Sukanya Raghavan
- Department of Microbiology and Immunology, Institute of Biomedicine, University of Gothenburg, Gothenburg, Sweden
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12
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Zamyatina A. Aminosugar-based immunomodulator lipid A: synthetic approaches. Beilstein J Org Chem 2018; 14:25-53. [PMID: 29379577 PMCID: PMC5769089 DOI: 10.3762/bjoc.14.3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 10/23/2017] [Indexed: 12/11/2022] Open
Abstract
The immediate immune response to infection by Gram-negative bacteria depends on the structure of a lipopolysaccharide (LPS, also known as endotoxin), a complex glycolipid constituting the outer leaflet of the bacterial outer membrane. Recognition of picomolar quantities of pathogenic LPS by the germ-line encoded Toll-like Receptor 4 (TLR4) complex triggers the intracellular pro-inflammatory signaling cascade leading to the expression of cytokines, chemokines, prostaglandins and reactive oxygen species which manifest an acute inflammatory response to infection. The "endotoxic principle" of LPS resides in its amphiphilic membrane-bound fragment glycophospholipid lipid A which directly binds to the TLR4·MD-2 receptor complex. The lipid A content of LPS comprises a complex mixture of structural homologs varying in the acylation pattern, the length of the (R)-3-hydroxyacyl- and (R)-3-acyloxyacyl long-chain residues and in the phosphorylation status of the β(1→6)-linked diglucosamine backbone. The structural heterogeneity of the lipid A isolates obtained from bacterial cultures as well as possible contamination with other pro-inflammatory bacterial components makes it difficult to obtain unambiguous immunobiological data correlating specific structural features of lipid A with its endotoxic activity. Advanced understanding of the therapeutic significance of the TLR4-mediated modulation of the innate immune signaling and the central role of lipid A in the recognition of LPS by the innate immune system has led to a demand for well-defined materials for biological studies. Since effective synthetic chemistry is a prerequisite for the availability of homogeneous structurally distinct lipid A, the development of divergent and reproducible approaches for the synthesis of various types of lipid A has become a subject of considerable importance. This review focuses on recent advances in synthetic methodologies toward LPS substructures comprising lipid A and describes the synthesis and immunobiological properties of representative lipid A variants corresponding to different bacterial species. The main criteria for the choice of orthogonal protecting groups for hydroxyl and amino functions of synthetically assembled β(1→6)-linked diglucosamine backbone of lipid A which allows for a stepwise introduction of multiple functional groups into the molecule are discussed. Thorough consideration is also given to the synthesis of 1,1'-glycosyl phosphodiesters comprising partial structures of 4-amino-4-deoxy-β-L-arabinose modified Burkholderia lipid A and galactosamine-modified Francisella lipid A. Particular emphasis is put on the stereoselective construction of binary glycosyl phosphodiester fragments connecting the anomeric centers of two aminosugars as well as on the advanced P(III)-phosphorus chemistry behind the assembly of zwitterionic double glycosyl phosphodiesters.
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Affiliation(s)
- Alla Zamyatina
- Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria
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13
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Li H, Liao T, Debowski AW, Tang H, Nilsson HO, Stubbs KA, Marshall BJ, Benghezal M. Lipopolysaccharide Structure and Biosynthesis in Helicobacter pylori. Helicobacter 2016; 21:445-461. [PMID: 26934862 DOI: 10.1111/hel.12301] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This review covers the current knowledge and gaps in Helicobacter pylori lipopolysaccharide (LPS) structure and biosynthesis. H. pylori is a Gram-negative bacterium which colonizes the luminal surface of the human gastric epithelium. Both a constitutive alteration of the lipid A preventing TLR4 elicitation and host mimicry of the Lewis antigen decorated O-antigen of H. pylori LPS promote immune escape and chronic infection. To date, the complete structure of H. pylori LPS is not available, and the proposed model is a linear arrangement composed of the inner core defined as the hexa-saccharide (Kdo-LD-Hep-LD-Hep-DD-Hep-Gal-Glc), the outer core composed of a conserved trisaccharide (-GlcNAc-Fuc-DD-Hep-) linked to the third heptose of the inner core, the glucan, the heptan and a variable O-antigen, generally consisting of a poly-LacNAc decorated with Lewis antigens. Although the glycosyltransferases (GTs) responsible for the biosynthesis of the H. pylori O-antigen chains have been identified and characterized, there are many gaps in regard to the biosynthesis of the core LPS. These limitations warrant additional mutagenesis and structural studies to obtain the complete LPS structure and corresponding biosynthetic pathway of this important gastric bacterium.
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Affiliation(s)
- Hong Li
- West China Marshall Research Centre for Infectious Diseases, Centre of Infectious Diseases, West China Hospital of Sichuan University, Chengdu, 610041, China.,Helicobacter pylori Research Laboratory, School of Pathology & Laboratory Medicine, Marshall Centre for Infectious Disease Research and Training, The University of Western Australia, M504, L Block, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Tingting Liao
- Helicobacter pylori Research Laboratory, School of Pathology & Laboratory Medicine, Marshall Centre for Infectious Disease Research and Training, The University of Western Australia, M504, L Block, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Aleksandra W Debowski
- Helicobacter pylori Research Laboratory, School of Pathology & Laboratory Medicine, Marshall Centre for Infectious Disease Research and Training, The University of Western Australia, M504, L Block, QEII Medical Centre, Nedlands, WA 6009, Australia.,School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Hong Tang
- West China Marshall Research Centre for Infectious Diseases, Centre of Infectious Diseases, West China Hospital of Sichuan University, Chengdu, 610041, China
| | - Hans-Olof Nilsson
- Ondek Pty Ltd., School of Pathology & Laboratory Medicine, Marshall Centre for Infectious Disease Research and Training, The University of Western Australia, M504, L Block, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Keith A Stubbs
- School of Chemistry and Biochemistry, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia
| | - Barry J Marshall
- Helicobacter pylori Research Laboratory, School of Pathology & Laboratory Medicine, Marshall Centre for Infectious Disease Research and Training, The University of Western Australia, M504, L Block, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Mohammed Benghezal
- Helicobacter pylori Research Laboratory, School of Pathology & Laboratory Medicine, Marshall Centre for Infectious Disease Research and Training, The University of Western Australia, M504, L Block, QEII Medical Centre, Nedlands, WA 6009, Australia.,Swiss Vitamin Institute, Route de la Corniche 1, CH-1066, Epalinges, Switzerland
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Oh S, Kim N, Kwon JW, Shin CM, Choi YJ, Lee DH, Jung HC. Effect of Helicobacter pylori Eradication and ABO Genotype on Gastric Cancer Development. Helicobacter 2016; 21:596-605. [PMID: 27191536 DOI: 10.1111/hel.12317] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Evidence is lacking regarding how Helicobacter pylori infection status, eradication history, and ABO blood type affect the development of gastric cancer (GC) given the multifactorial and distinctive etiology according to cancer location (noncardia vs cardia) and histologic type (intestinal vs diffuse-type). We evaluated the effect of H. pylori infection status incorporated with H. pylori eradication history and ABO genotype on GC development according to cancer location and histologic type. METHODS A case-control study of 997 patients with noncardia GC (NCGC) and 1147 control subjects was performed using risk analyses with 14 factors including H. pylori infection with eradication history and ABO genotype. As final analyses, multivariable logistic regression models were fitted. Additionally, H. pylori infection status with eradication history was tested for its association with age, atrophic gastritis (AG), and intestinal metaplasia (IM). RESULTS The ABO genotype with the B allele was associated with a significantly lower risk of NCGC of both histologic types. The reduction in risk for NCGC by adding the B allele was more prominent in diffuse-type than that in the intestinal-type. H. pylori infection with eradication history was associated with a significantly lower risk of NCGC of both histologic types, compared with those without eradication history (odds ratio (OR), 0.22; 95% confidence interval (CI), 0.14-0.34) approaching that of uninfected subjects. Past infection status without an eradication history was associated with older age, AG, and IM. CONCLUSIONS H. pylori eradication and the B allele decreased the risks of the intestinal and diffuse-types of NCGC. H. pylori eradication revealed a strong association against developing NCGC. Therefore, it should be considered as a primary measure in NCGC prevention.
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Affiliation(s)
- Sooyeon Oh
- Department of Internal Medicine and Liver Research Institute, Seoul National University, College of Medicine, Seoul, Korea
| | - Nayoung Kim
- Department of Internal Medicine and Liver Research Institute, Seoul National University, College of Medicine, Seoul, Korea.,Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Jin-Won Kwon
- College of Pharmacy and Research, Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu, Korea
| | - Cheol Min Shin
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Yoon Jin Choi
- Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Dong Ho Lee
- Department of Internal Medicine and Liver Research Institute, Seoul National University, College of Medicine, Seoul, Korea.,Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Hyun Chae Jung
- Department of Internal Medicine and Liver Research Institute, Seoul National University, College of Medicine, Seoul, Korea
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15
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Chmiela M, Gajewski A, Rudnicka K. Helicobacter pylori vs coronary heart disease - searching for connections. World J Cardiol 2015; 7:187-203. [PMID: 25914788 PMCID: PMC4404374 DOI: 10.4330/wjc.v7.i4.187] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 01/16/2015] [Accepted: 02/09/2015] [Indexed: 02/07/2023] Open
Abstract
In this review, we discussed the findings and concepts underlying the potential role of Helicobacter pylori (H. pylori) infections in the initiation, development or persistence of atherosclerosis and coronary heart disease (CHD). This Gram-negative bacterium was described by Marshall and Warren in 1984. The majority of infected subjects carries and transmits H. pylori with no symptoms; however, in some individuals these bacteria may cause peptic ulcers, and even gastric cancers. The widespread prevalence of H. pylori infections and the fact that frequently they remain asymptomatic may suggest that, similarly to intestinal microflora, H. pylori may deliver antigens that stimulate not only local, but also systemic inflammatory response. Recently, possible association between H. pylori infection and extragastric disorders has been suggested. Knowledge on the etiology of atherosclerosis together with current findings in the area of H. pylori infections constitute the background for the newly proposed hypothesis that those two processes may be related. Many research studies confirm the indirect association between the prevalence of H. pylori and the occurrence of CHD. According to majority of findings the involvement of H. pylori in this process is based on the chronic inflammation which might facilitate the CHD-related pathologies. It needs to be elucidated, if the infection initiates or just accelerates the formation of atheromatous plaque.
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16
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Kondadi PK, Revez J, Hänninen ML, Rossi M. Sialylation of Helicobacter bizzozeronii lipopolysaccharides modulates Toll-like receptor (TLR) 2 mediated response. Vet Res 2015; 46:4. [PMID: 25603825 PMCID: PMC4299687 DOI: 10.1186/s13567-014-0133-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Accepted: 12/10/2014] [Indexed: 12/20/2022] Open
Abstract
Sialic acid in lipopolysaccharides (LPS) of mucosal pathogens is known to be an important virulence factor. Few strains of Helicobacter pylori express sialyl-Lewis-X and we have reported that human and canine Helicobacter bizzozeronii strains express sialyl-lactoseamine in their LPS. However, the role of sialyation of Helicobacter LPS in the interaction with the host cells is still unknown. In this study H. bizzozeronii LPS is shown to activate the TLR2 in a dose and strain dependent manner in the in vitro HEK-293 cells model expressing TLR2, but not the cells expressing TLR4. These results indicate that TLR2 is the specific receptor for H. bizzozzeronii LPS, as previously described for H. pylori. To further explore the role of sialylation of H. bizzozeronii LPS on TLR2 response, H. bizzozeronii Δhbs2 mutant strains deficient in sialyltransferase activity were constructed by homologous recombination. LPS from H. bizzozeronii Δhbs2 strains enhanced the NF-ĸB induction via TLR2 compared to the respective wild types, leading to the conclusion that the sialylation of H. bizzozeronii LPS in wild-type strains may modulate host immune response.
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Affiliation(s)
| | | | | | - Mirko Rossi
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, Agnes Sjöbergin katu 2, Helsinki, FI-00014, Finland.
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17
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18
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Host Evasion and Exploitation Schemes of Mycobacterium tuberculosis. Cell 2014; 159:1497-509. [DOI: 10.1016/j.cell.2014.11.024] [Citation(s) in RCA: 269] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Indexed: 12/20/2022]
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19
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Chionh YT, Arulmuruganar A, Venditti E, Ng GZ, Han JX, Entwisle C, Ang CS, Colaco CA, McNulty S, Sutton P. Heat shock protein complex vaccination induces protection against Helicobacter pylori without exogenous adjuvant. Vaccine 2014; 32:2350-8. [PMID: 24625340 DOI: 10.1016/j.vaccine.2014.02.051] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 01/24/2014] [Accepted: 02/12/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND The development of a vaccine against the human gastric pathogen Helicobacter pylori, the main causative agent of gastric adenocarcinoma, has been hampered by a number of issues, including the lack of a mucosal adjuvant for use in humans. Heat shock proteins (Hsp), highly conserved molecules expressed by both bacteria and mammalian species, possess a range of functions, including acting as chaperones for cellular proteins and the ability to activate innate immune receptors. Hsp complex (HspC) vaccines, containing Hsp derived from pathogenic bacteria, are immunostimulatory without addition of an exogenous adjuvant and can induce immunity against their chaperoned proteins. In this study we explored in mice the potential utility of a H. pylori HspC vaccine. RESULTS Vaccination with H. pylori HspC, by either the subcutaneous or respiratory mucosal route, induced a strong antibody response, elevated gastric cytokine levels and significant protection against subsequent live challenge with this pathogen. The level of protection induced by non-adjuvanted HspC vaccine was equivalent to that which resulted from vaccination with adjuvanted vaccines. While protection induced by immunisation with adjuvanted vaccines was associated with the development of a moderate to severe atrophic gastritis, that induced by H. pylori HspC only resulted in a mild inflammatory response, despite an increase in pro-inflammatory gastric cytokines. This reduced gastritis correlated with an increase in IL-10 and IL-13 levels in the gastric tissues of HspC vaccinated, H. pylori challenged mice. CONCLUSIONS H. pylori HspC vaccines have the potential to overcome some of the issues preventing the development of a human vaccine against this pathogen: HspC induced protective immunity against H. pylori without addition of an adjuvant and without the induction of a severe inflammatory response. However, complete protection was not obtained so further optimisation of this technology is needed if a human vaccine is to become a reality.
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Affiliation(s)
- Yok Teng Chionh
- Mucosal Immunology, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Parkville, VIC 3052, Australia; Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, VIC 3010, Australia
| | - Arthi Arulmuruganar
- Mucosal Immunology, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Parkville, VIC 3052, Australia
| | - Elena Venditti
- ImmunoBiology Ltd., Babraham Research Campus, Babraham, Cambridge, UK
| | - Garrett Z Ng
- Mucosal Immunology, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Parkville, VIC 3052, Australia
| | - Jia-Xi Han
- Mucosal Immunology, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Parkville, VIC 3052, Australia
| | - Claire Entwisle
- ImmunoBiology Ltd., Babraham Research Campus, Babraham, Cambridge, UK
| | - Ching-Seng Ang
- Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC 3010, Australia
| | - Camilo A Colaco
- ImmunoBiology Ltd., Babraham Research Campus, Babraham, Cambridge, UK
| | - Shaun McNulty
- ImmunoBiology Ltd., Babraham Research Campus, Babraham, Cambridge, UK
| | - Philip Sutton
- Mucosal Immunology, Murdoch Childrens Research Institute, Royal Children's Hospital, Melbourne, Parkville, VIC 3052, Australia; Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, VIC 3010, Australia.
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20
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Rubin EJ, O'Brien JP, Ivanov PL, Brodbelt JS, Trent MS. Identification of a broad family of lipid A late acyltransferases with non-canonical substrate specificity. Mol Microbiol 2014; 91:887-99. [PMID: 24372821 DOI: 10.1111/mmi.12501] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2013] [Indexed: 12/21/2022]
Abstract
Most Gram-negative organisms produce lipopolysaccharide (LPS), a complex macromolecule anchored to the bacterial membrane by the lipid A moiety. Lipid A is synthesized via the Raetz pathway, a conserved nine-step enzymatic process first characterized in Escherichia coli. The Epsilonproteobacterium Helicobacter pylori uses the Raetz pathway to synthesize lipid A; however, only eight of nine enzymes in the pathway have been identified in this organism. Here, we identify the missing acyltransferase, Jhp0255, which transfers a secondary acyl chain to the 3'-linked primary acyl chain of lipid A, an activity similar to that of E. coli LpxM. This enzyme, reannotated as LpxJ due to limited sequence similarity with LpxM, catalyses addition of a C12:0 or C14:0 acyl chain to the 3'-linked primary acyl chain of lipid A, complementing an E. coli LpxM mutant. Enzymatic assays demonstrate that LpxJ and homologues in Campylobacter jejuni and Wolinella succinogenes can act before the 2' secondary acyltransferase, LpxL, as well as the 3-deoxy-d-manno-octulosonic acid (Kdo) transferase, KdtA. Ultimately, LpxJ is one member of a large class of acyltransferases found in a diverse range of organisms that lack an E. coli LpxM homologue, suggesting that LpxJ participates in lipid A biosynthesis in place of an LpxM homologue.
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Affiliation(s)
- Erica J Rubin
- Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
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Abstract
Some host-adapted bacterial pathogens are capable of causing persistent infections in humans. For example, Helicobacter pylori inhabits the human gastric mucosa and persistence can be lifelong. Salmonella enterica serovar Typhi causes systemic infections that involve colonization of the reticuloendothelial system and some individuals become lifelong carriers. In this review, I compare and contrast the different lifestyles of Helicobacter and Salmonella within the host and the strategies they have evolved to persist in mammalian hosts. Persistently infected carriers serve as the reservoirs for these pathogens, and the carrier state is an essential feature that is required for survival of the bacteria within a restricted host population. Therefore, investigating the chronic carrier state should provide insight into bacterial survival strategies, as well as new therapeutic approaches for treatments.
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Affiliation(s)
- Denise M Monack
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California 94305
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22
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Ng G, Every A, McGuckin M, Sutton P. Increased Helicobacter felis colonization in male 129/Sv mice fails to suppress gastritis. Gut Microbes 2013; 2:358-60. [PMID: 22198616 DOI: 10.4161/gmic.19143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Development of the pathologies associated with Helicobacter pylori infection, most seriously gastric adenocarcinoma, are a consequence of chronic inflammation, which both host and pathogen go to some lengths to minimize. Recently, we presented evidence that H. pylori can suppress the development of inflammation in its immediate microenvironment in the gastric mucosa of 129/Sv mice. We have now extended this study by showing that H. felis, a gastric colonizing Helicobacter closely related to H. pylori, does not possess the same ability to suppress Helicobacter-induced gastritis in mice. Differences between these bacterial species may provide clues as to the mechanism behind the inflammation-regulating ability of H. pylori. Moreover, our demonstration that H. pylori but not H. felis can locally suppress inflammation in vivo may explain why H. felis infection induces superior levels of gastritis as compared with H. pylori infection of mice.
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Affiliation(s)
- Garrett Ng
- Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Parkville, VIC Australia
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Clinical characteristics and the expression profiles of inflammatory cytokines/cytokine regulatory factors in asymptomatic patients with nodular gastritis. Dig Dis Sci 2012; 57:1486-95. [PMID: 22290343 DOI: 10.1007/s10620-012-2053-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 01/05/2012] [Indexed: 12/30/2022]
Abstract
BACKGROUND Nodular gastritis (NG) has been reported in adult dyspeptic patients, whereas information on NG in asymptomatic patients is limited. AIMS To evaluate the prevalence, clinico-epidemiological characteristics, and expression profiles of inflammatory cytokines or cytokine regulatory factors of NG in asymptomatic adults. METHODS A cross-sectional study was conducted prospectively using 2,579 consecutive asymptomatic subjects who underwent screening esophagogastroduodenoscopy. The expression of inflammatory cytokines or cytokine regulatory factors in the gastric mucosa of NG patients was evaluated using immunofluorescence staining. RESULTS NG was diagnosed in 52 patients (2.0%) and showed a predilection for females (M:F = 1:1.89) and young adults (median age: 34 years; range: 25-51 years). All NG patients were positive for Helicobacter pylori infection. Based on multivariate analysis, the risk of NG was increased in patients younger than 40 years (OR, 7.57; 95% CI, 3.76-15.24) and of the female gender (OR, 2.12; 95% CI; 1.05-4.28). Immunofluorescent staining for interleukin (IL)-1β, IL-10, IL-18, IL-18 binding protein, IL-32, IL-33, and neutrophil proteinase 3 (PR3) was performed on cryosections of gastric mucosa. Interestingly, the expression of PR3 was highly increased in the gastric biopsies from asymptomatic NG patients but was expressed infrequently in the controls. CONCLUSIONS Asymptomatic NG is associated with H. pylori infection, and a predilection for this condition exists in young females. The PR3 expression of gastric mucosa might play an important role in the pathogenesis of NG.
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Identification and characterization of a lipopolysaccharide α,2,3-sialyltransferase from the human pathogen Helicobacter bizzozeronii. J Bacteriol 2012; 194:2540-50. [PMID: 22408169 DOI: 10.1128/jb.00126-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Terminal sialic acid in the lipopolysaccharides (LPSs) of mucosal pathogens is an important virulence factor. Here we report the characterization of a Helicobacter sialyltransferase involved in the biosynthesis of sialylated LPS in Helicobacter bizzozeronii, the only non-pylori gastric Helicobacter species isolated from humans thus far. Starting from the genome sequences of canine and human strains, we identified potential sialyltransferases downstream of three genes involved in the biosynthesis of N-acetylneuraminic acid. One of these candidates showed monofunctional α,2,3-sialyltransferase activity with a preference for N-acetyllactosamine as a substrate. The LPSs from different strains were shown by SDS-PAGE and high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) to contain sialic acid after neuraminidase treatment. The expression of this sialyltransferase and sialyl-LPS appeared to be a phase-variable characteristic common to both human and canine H. bizzozeronii strains. The sialylation site of the LPSs of two H. bizzozeronii strains was determined to be NeuAc-Hex-HexNAc, suggesting terminal 3'-sialyl-LacNAc. Moreover, serological typing revealed the possible presence of sialyl-Lewis X in two additional strains, indicating that H. bizzozeronii could also mimic the surface glycans of mammalian cells. The expression of sialyl-glycans may influence the adaptation process of H. bizzozeronii during the host jump from dogs to humans.
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25
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Safina G. Application of surface plasmon resonance for the detection of carbohydrates, glycoconjugates, and measurement of the carbohydrate-specific interactions: A comparison with conventional analytical techniques. A critical review. Anal Chim Acta 2012; 712:9-29. [DOI: 10.1016/j.aca.2011.11.016] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 10/07/2011] [Accepted: 11/04/2011] [Indexed: 12/16/2022]
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Sundquist M, Quiding-Järbrink M. Helicobacter pylori and its effect on innate and adaptive immunity: new insights and vaccination strategies. Expert Rev Gastroenterol Hepatol 2010; 4:733-44. [PMID: 21108593 DOI: 10.1586/egh.10.71] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Infection with the gastric bacterium Helicobacter pylori invariably leads to active chronic gastritis, and is strongly correlated to peptic ulcer disease, gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. The infection leads to local accumulation of inflammatory cells and strong activation of B- and T-cell immunity. Still, the immune response can not eliminate the bacteria, and unless antibiotic treatment is used, the infection is usually lifelong. During the last few years, several immunomodulatory properties of H. pylori have been described, which probably contribute to the inability of the immune system to eradicate the bacterium. Another factor promoting bacterial persistence is probably the induction of a substantial regulatory T-cell response by the infection. Several different immunization schedules have resulted in protective immunity in animal models, while in humans no reliable vaccine is available as yet. In this article, we describe the innate and adaptive immune responses to H. pylori, and the attempts to create an effective vaccine.
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Affiliation(s)
- Malin Sundquist
- Department of Microbiology and Immunology, The Sahlgrenska Academy at the University of Gothenburg, P.O. Box 435, 405 30 Göteborg, Sweden
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Hanson PJ, Moran AP, Butler K. Paracellular permeability is increased by basal lipopolysaccharide in a primary culture of colonic epithelial cells; an effect prevented by an activator of Toll-like receptor-2. Innate Immun 2010; 17:269-82. [PMID: 20472611 DOI: 10.1177/1753425910367813] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Lipopolysaccharide (LPS), which generally activates Toll-like receptor 4 (TLR4), is expressed on commensal colonic bacteria. In a number of tissues, LPS can act directly on epithelial cells to increase paracellular permeability. Such an effect in the colon would have an important impact on the understanding of normal homeostasis and of pathology. Our aim was to use a novel primary culture of colonic epithelial cells grown on Transwells to investigate whether LPS, or Pam(3)CSK( 4), an activator of TLR2, affected paracellular permeability. Consequently, [(14)C]-mannitol transfer and transepithelial electrical resistance (TEER) were measured. The preparation consisted primarily of cytokeratin-18 positive epithelial cells that produced superoxide, stained for mucus with periodic acid-Schiff reagent, exhibited alkaline phosphatase activity and expressed TLR2 and TLR4. Tight junctions and desmosomes were visible by transmission electron microscopy. Basally, but not apically, applied LPS from Escherichia coli increased the permeability to mannitol and to a 10-kDa dextran, and reduced TEER. The LPS from Helicobacter pylori increased paracellular permeability of gastric cells when applied either apically or basally, in contrast to colon cells, where this LPS was active only from the basal aspect. A pan-caspase inhibitor prevented the increase in caspase activity caused by basal E. coli LPS, and reduced the effects of LPS on paracellular permeability. Synthetic Pam(3)CSK(4) in the basal compartment prevented all effects of basal E. coli LPS. In conclusion, LPS applied to the base of the colonic epithelial cells increased paracellular permeability by a mechanism involving caspase activation, suggesting a process by which perturbation of the gut barrier could be exacerbated. Moreover, activation of TLR2 ameliorated such effects.
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Affiliation(s)
- Peter J Hanson
- Life and Health Sciences, Aston University, Birmingham, UK.
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Hug I, Couturier MR, Rooker MM, Taylor DE, Stein M, Feldman MF. Helicobacter pylori lipopolysaccharide is synthesized via a novel pathway with an evolutionary connection to protein N-glycosylation. PLoS Pathog 2010; 6:e1000819. [PMID: 20333251 PMCID: PMC2841628 DOI: 10.1371/journal.ppat.1000819] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Accepted: 02/09/2010] [Indexed: 01/25/2023] Open
Abstract
Lipopolysaccharide (LPS) is a major component on the surface of Gram negative bacteria and is composed of lipid A-core and the O antigen polysaccharide. O polysaccharides of the gastric pathogen Helicobacter pylori contain Lewis antigens, mimicking glycan structures produced by human cells. The interaction of Lewis antigens with human dendritic cells induces a modulation of the immune response, contributing to the H. pylori virulence. The amount and position of Lewis antigens in the LPS varies among H. pylori isolates, indicating an adaptation to the host. In contrast to most bacteria, the genes for H. pylori O antigen biosynthesis are spread throughout the chromosome, which likely contributed to the fact that the LPS assembly pathway remained uncharacterized. In this study, two enzymes typically involved in LPS biosynthesis were found encoded in the H. pylori genome; the initiating glycosyltransferase WecA, and the O antigen ligase WaaL. Fluorescence microscopy and analysis of LPS from H. pylori mutants revealed that WecA and WaaL are involved in LPS production. Activity of WecA was additionally demonstrated with complementation experiments in Escherichia coli. WaaL ligase activity was shown in vitro. Analysis of the H. pylori genome failed to detect a flippase typically involved in O antigen synthesis. Instead, we identified a homolog of a flippase involved in protein N-glycosylation in other bacteria, although this pathway is not present in H. pylori. This flippase named Wzk was essential for O antigen display in H. pylori and was able to transport various glycans in E. coli. Whereas the O antigen mutants showed normal swimming motility and injection of the toxin CagA into host cells, the uptake of DNA seemed to be affected. We conclude that H. pylori uses a novel LPS biosynthetic pathway, evolutionarily connected to bacterial protein N-glycosylation. Bacterial surfaces are decorated with glycans. The human stomach pathogen Helicobacter pylori exposes lipopolysaccharide (LPS) containing Lewis antigens that mimic human glycan structures. H. pylori alters its Lewis antigen display in adaptation to the individual host. Lewis antigens can interact with human dendritic cells, thereby inducing a suppression of the immune response and facilitating a chronic H. pylori infection. Whereas three general LPS biosynthesis pathways are known, the route of LPS assembly in H. pylori remained to be elucidated. We identified and characterized two components of the H. pylori LPS pathway, WecA and WaaL, which demonstrated that, as in other bacteria, the glycan is initially assembled onto a polyprenoid lipid carrier. This intermediate then has to cross a membrane barrier, requiring specialized translocases. H. pylori does not employ a translocase from common LPS pathways. We show that instead H. pylori uses a translocase named Wzk, which is involved in protein N-glycosylation in other bacteria. Wzk was able to translocate various glycan structures. The identification of Wzk as the H. pylori translocase involved in LPS biosynthesis indicates an evolutionary connection between LPS and glycoprotein biosynthesis pathways.
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Affiliation(s)
- Isabelle Hug
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Marc R. Couturier
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Michelle M. Rooker
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Diane E. Taylor
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Markus Stein
- Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, Alberta, Canada
| | - Mario F. Feldman
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
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Identification and characterization of a glycosyltransferase involved in Acinetobacter baumannii lipopolysaccharide core biosynthesis. Infect Immun 2010; 78:2017-23. [PMID: 20194587 DOI: 10.1128/iai.00016-10] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Although Acinetobacter baumannii has emerged as a significant cause of nosocomial infections worldwide, there have been few investigations describing the factors important for A. baumannii persistence and pathogenesis. This paper describes the first reported identification of a glycosyltransferase, LpsB, involved in lipopolysaccharide (LPS) biosynthesis in A. baumannii. Mutational, structural, and complementation analyses indicated that LpsB is a core oligosaccharide glycosyl transferase. Using a genetic approach, lpsB was compared with the lpsB homologues of several A. baumannii strains. These analyses indicated that LpsB is highly conserved among A. baumannii isolates. Furthermore, we developed a monoclonal antibody, monoclonal antibody 13C11, which reacts to an LPS core epitope expressed by approximately one-third of the A. baumannii clinical isolates evaluated to date. Previous studies describing the heterogeneity of A. baumannii LPS were limited primarily to structural analyses; therefore, studies evaluating the correlation between these surface glycolipids and pathogenesis were warranted. Our data from an evaluation of LpsB mutant 307::TN17, which expresses a deeply truncated LPS glycoform consisting of only two 3-deoxy-d-manno-octulosonic acid residues and lipid A, suggest that A. baumannii LPS is important for resistance to normal human serum and confers a competitive advantage for survival in vivo. These results have important implications for the role of LPS in A. baumannii infections.
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Wee JLK, Chionh YT, Ng GZ, Harbour SN, Allison C, Pagel CN, Mackie EJ, Mitchell HM, Ferrero RL, Sutton P. Protease-activated receptor-1 down-regulates the murine inflammatory and humoral response to Helicobacter pylori. Gastroenterology 2010; 138:573-82. [PMID: 19706295 DOI: 10.1053/j.gastro.2009.08.043] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Revised: 07/17/2009] [Accepted: 08/10/2009] [Indexed: 01/13/2023]
Abstract
BACKGROUND & AIMS Helicobacter pylori infection results in a diversity of pathologies, from asymptomatic gastritis to adenocarcinoma. The reason for these diverse outcomes is multifactorial and includes host factors that regulate severity of Helicobacter-induced gastritis. Protease-activated receptors (PAR) are environmental sensors that can detect tissue damage and pathogens. Whereas PAR-2 has proinflammatory activity and PAR-1 can protect the gastric mucosa against chemical damage, neither has previously been examined for their potential roles in regulating Helicobacter pathogenesis. METHODS PAR-1(-/-), PAR-2(-/-), and wild-type mice were infected with H pylori for up to 2 months then colonization levels determined by colony-forming assay, gastritis by histology, and serum antibody levels by enzyme-linked immunosorbent assay. Responsiveness of primary epithelial cells to PAR-1 activation was assessed by calcium mobilization assay. Primary epithelial cells, macrophages, and dendritic cells were cocultured with H pylori and nuclear factor (NF)-kappaB, and cytokine secretion was determined by enzyme-linked immunosorbent assay. RESULTS Two months postinfection, H pylori levels were significantly reduced in PAR-1(-/-) and increased in PAR-2(-/-) mice. This effect on colonization was inversely correlated with inflammation severity. Infection of PAR-1(-/-) mice induced an increased serum antibody response. Primary epithelial cells were activated by a PAR-1-activating peptide. H pylori stimulation of primary epithelial cells, but not macrophages or dendritic cells, from PAR-1(-/-) mice induced increased levels of NF-kappaB and the proinflammatory cytokine macrophage-inflammatory protein (MIP)-2. PAR-1 also down-regulated MIP-2 secretion in response to cag pathogenicity island activity. CONCLUSIONS PAR-1 protects the host against severe Helicobacter-induced gastritis. This may be mediated by suppressing the production of proinflammatory cytokines such as MIP-2.
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Affiliation(s)
- Janet L K Wee
- Centre for Animal Biotechnology, School of Veterinary Science, University of Melbourne, Melbourne, Australia
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Abstract
Both Helicobacter pylori and Campylobacter jejuni are highly prevalent Gram-negative microaerophilic bacteria which are gastrointestinal pathogens of humans; H. pylori colonizes the gastroduodenal compartment and C. jejuni the intestinal mucosa. Although H. pylori causes chronic gastric infection leading to gastritis, peptic ulcers and eventually gastric cancer while C. jejuni causes acute infection inducing diarrhoeal disease, the endotoxin molecules of both bacterial species contrastingly contribute to their pathogenesis and the autoimmune sequelae each induces. Compared with enterobacterial endotoxin, that of H. pylori has significantly lower endotoxic and immuno-activities, the molecular basis for which is the underphosphorylation and underacylation of the lipid A component that interacts with immune receptors. This induction of low immunological responsiveness by endotoxin may aid the prolongation of H. pylori infection and therefore infection chronicity. On the other hand, this contrasts with acute infection-causing C. jejuni where overt inflammation contributes to pathology and diarrhoea production, and whose endotoxin is immunologically and endotoxically active. Futhermore, both H. pylori and C. jejuni exhibit molecular mimicry in the saccharide components of their endotoxins which can induce autoreactive antibodies; H. pylori expresses mimicry of Lewis and some ABO blood group antigens, C. jejuni mimicry of gangliosides. The former has been implicated in influencing the development of inflammation and gastric atrophy (a precursor of gastic cancer), the latter is central to the development of the neurological disorder Guillain-Barré syndrome. Both diseases raise important questions concerning infection-induced autoimmunity awaiting to be addressed.
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Affiliation(s)
- Anthony P Moran
- Laboratory of Molecular Biochemistry, Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
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Abstract
Dendritic cell-specific ICAM-3-grabbing nonintegrin (DC-SIGN). DC-SIGN is a C-type lectin receptor that recognizes N-linked high-mannose oligosaccharides and branched fucosylated structures. It is now clear that the biological role of DC-SIGN is two-fold. It is primarily expressed by dendritic cells and mediates important functions necessary for the induction of successful immune responses that are essential for the clearance of microbial infections, such as the capture, destruction, and presentation of microbial pathogens to induce successful immune responses. Yet, on the other hand, pathogens may also exploit DC-SIGN to modulate DC functioning thereby skewing the immune response and promoting their own survival. This chapter presents an overview of the structure of DC-SIGN and its expression pattern among immune cells. The current state of knowledge of DC-SIGN-carbohydrate interactions is discussed and how these interactions influence dendritic cell functioning is examined. The molecular aspects that underlie the selectivity of DC-SIGN for mannose-and fucose-containing carbohydrates are detailed. Furthermore, the chapter discusses the role of DC-SIGN in dendritic cell biology and how certain bacterial pathogens exploit DC-SIGN to escape immune surveillance.
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Chiu HC, Lin TL, Yang JC, Wang JT. Synergistic effect of imp/ostA and msbA in hydrophobic drug resistance of Helicobacter pylori. BMC Microbiol 2009; 9:136. [PMID: 19594901 PMCID: PMC2719649 DOI: 10.1186/1471-2180-9-136] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 07/13/2009] [Indexed: 11/22/2022] Open
Abstract
Background Contamination of endoscopy equipment by Helicobacter pylori (H. pylori) frequently occurs after endoscopic examination of H. pylori-infected patients. In the hospital, manual pre-cleaning and soaking in glutaraldehyde is an important process to disinfect endoscopes. However, this might not be sufficient to remove H. pylori completely, and some glutaraldehyde-resistant bacteria might survive and be passed to the next patient undergoing endoscopic examination through unidentified mechanisms. We identified an Imp/OstA protein associated with glutaraldehyde resistance in a clinical strain, NTUH-C1, from our previous study. To better understand and manage the problem of glutaraldehyde resistance, we further investigated its mechanism. Results The minimal inhibitory concentrations (MICs) of glutaraldehyde andexpression of imp/ostA RNA in 11 clinical isolates from the National Taiwan University Hospital were determined. After glutaraldehyde treatment, RNA expression in the strains with the MICs of 4–10 μg/ml was higher than that in strains with the MICs of 1–3 μg/ml. We examined the full-genome expression of strain NTUH-S1 after glutaraldehyde treatment using a microarray and found that 40 genes were upregulated and 31 genes were downregulated. Among the upregulated genes, imp/ostA and msbA, two putative lipopolysaccharide biogenesis genes, were selected for further characterization. The sensitivity to glutaraldehyde or hydrophobic drugs increased in both of imp/ostA and msbA single mutants. The imp/ostA and msbA double mutant was also hypersensitive to these chemicals. The lipopolysaccharide contents decreased in individual imp/ostA and msbA mutants and dramatically reduced in the imp/ostA and msbA double mutant. Outer membrane permeability assay demonstrated that the imp/ostA and msbA double mutation resulted in the increase of outer membrane permeability. Ethidium bromide accumulation assay demonstrated that MsbA was involved in efflux of hydrophobic drugs. Conclusion The expression levels of imp/ostA and msbA were correlated with glutaraldehyde resistance in clinical isolates after glutaraldehyde treatment. Imp/OstA and MsbA play a synergistic role in hydrophobic drugs resistance and lipopolysaccharide biogenesis in H. pylori.
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Affiliation(s)
- Hung-Chuan Chiu
- Department of Microbiology, National Taiwan University College of Medicine, Taipei City 10051, Taiwan, Republic of China.
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Zhou P, Chandan V, Liu X, Chan K, Altman E, Li J. Microwave-assisted sample preparation for rapid and sensitive analysis of H. pylori lipid A applicable to a single colony. J Lipid Res 2009; 50:1936-44. [PMID: 19401599 DOI: 10.1194/jlr.d900013-jlr200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The lipid A of Gram-negative bacteria plays a major role in the pathogenesis of bacterial infections. Lipid A diversity is observed both in the number and length of fatty-acid side chains and in the presence of terminal phosphate residues and associated modifications. In this report, we describe a new sample preparation method based on microwave-assisted enzymatic digestion and detergent-free mild hydrolysis, in conjunction with a MALDI-time-of-flight (TOF)/TOF analysis, to determine the structures of lipid A from Helicobacter pylori. The total time for sample preparation and mass spectrometric analysis is within 2 h and applicable to profiling the lipid A structures from dried bacterial cells on as little as 1 microg. The reliability of the technique was further demonstrated through the analysis of the lipid A from bacterial cells of different H. pylori strains. The phosphorylation and acylation patterns of lipid A could be elucidated using material from a single colony. Furthermore, we found unusual heptaacyl lipid A species present in H. pylori mutant that have not been previously reported, although the abundance was relatively low. The present study provides the first characterization of the lipid A component from a single bacterial colony sample by mass spectrometry.
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Affiliation(s)
- Ping Zhou
- Institute for Biological Sciences, National Research Council Canada, Ottawa, Ontario, Canada
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Angelini A, Cendron L, Goncalves S, Zanotti G, Terradot L. Structural and enzymatic characterization of HP0496, a YbgC thioesterase from Helicobacter pylori. Proteins 2009; 72:1212-21. [PMID: 18338382 DOI: 10.1002/prot.22014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
YbgC proteins are bacterial acyl-CoA thioesterases associated with the Tol-Pal system. This system is important for cell envelope integrity and is part of the cell division machinery. In E. coli, YbgC associates with the cell membrane and is part of a protein network involved in lipid biogenesis. In the human pathogen Helicobacter pylori, a putative homologue of YbgC, named HP0496, was found to interact with the cytotoxin CagA by two different studies. We have determined its crystal structure and characterized its enzymatic activity. The structure of HP0496 shows that it is a member of the hot-dog family of proteins, with a epsilongamma tetrameric arrangement. Finally, enzymatic assays performed with the purified protein showed that HP0496 is an acyl-CoA thioesterase that favors long-chain substrates.
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Affiliation(s)
- Alessandro Angelini
- Macromolecular Crystallography Group, European Synchrotron Radiation Facility, B.P. 220, 6 rue Jules Horowitz, F-38043 Grenoble Cedex, France
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Nilsson C, Skoglund A, Moran AP, Annuk H, Engstrand L, Normark S. Lipopolysaccharide diversity evolving in Helicobacter pylori communities through genetic modifications in fucosyltransferases. PLoS One 2008; 3:e3811. [PMID: 19043574 PMCID: PMC2583950 DOI: 10.1371/journal.pone.0003811] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 11/04/2008] [Indexed: 01/16/2023] Open
Abstract
Helicobacter pylori persistently colonizes the gastric mucosa of half the human population. It is one of the most genetically diverse bacterial organisms and subvariants are continuously emerging within an H. pylori population. In this study we characterized a number of single-colony isolates from H. pylori communities in various environmental settings, namely persistent human gastric infection, in vitro bacterial subcultures on agar medium, and experimental in vivo infection in mice. The lipopolysaccharide (LPS) O-antigen chain revealed considerable phenotypic diversity between individual cells in the studied bacterial communities, as demonstrated by size variable O-antigen chains and different levels of Lewis glycosylation. Absence of high-molecular-weight O-antigen chains was notable in a number of experimentally passaged isolates in vitro and in vivo. This phenotype was not evident in bacteria obtained from a human gastric biopsy, where all cells expressed high-molecular-weight O-antigen chains, which thus may be the preferred phenotype for H. pylori colonizing human gastric mucosa. Genotypic variability was monitored in the two genes encoding α1,3-fucosyltransferases, futA and futB, that are involved in Lewis antigen expression. Genetic modifications that could be attributable to recombination events within and between the two genes were commonly detected and created a diversity, which together with phase variation, contributed to divergent LPS expression. Our data suggest that the surrounding environment imposes a selective pressure on H. pylori to express certain LPS phenotypes. Thus, the milieu in a host will select for bacterial variants with particular characteristics that facilitate adaptation and survival in the gastric mucosa of that individual, and will shape the bacterial community structure.
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Affiliation(s)
- Christina Nilsson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.
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O'Keeffe J, Moran AP. Conventional, regulatory, and unconventional T cells in the immunologic response to Helicobacter pylori. Helicobacter 2008; 13:1-19. [PMID: 18205661 DOI: 10.1111/j.1523-5378.2008.00559.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Infection by the gastroduodenal pathogen Helicobacter pylori elicits a complex immunologic response in the mucosa involving neutrophils, plasma cells, eosinophils, and lymphocytes, of which T cells are the principal orchestrators of immunity. While so-called classical T cells (e.g. T-helper cells) that are activated by peptide fragments presented on antigen-presenting cells have received much attention in H. pylori infection, there exists a diverse array of other T cell populations that are potentially important for the outcome of the ensuing immune response, some of which have not been extensively studied in H. pylori infection. Pathogen-specific regulatory T cells that control and prevent the development of immunopathology associated with H. pylori infection have been investigated, but these cells can also benefit the bacterium in helping to prolong the chronicity of the infection by suppressing protective immune responses. An overlooked T cell population, the more recently described Th17 cells, may play a role in H. pylori-induced inflammation, due to triggering responses that ultimately lead to the recruitment of polymorphs, including neutrophils. The so-called innate or unconventional T cells, that include two conserved T cell subsets expressing invariant antigen-specific receptors, the CD1d-restricted natural killer T cells which are activated by glycolipids, and the mucosal-associated invariant T cells which play a role in defense against orally acquired pathogens in the intestinal mucosa, have only begun to receive attention. A greater knowledge of the range of T cell responses induced by H. pylori is required for a deeper understanding of the pathogenesis of this bacterium and its ability to perpetuate chronic infection, and could reveal new strategies for therapeutic exploitation.
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Affiliation(s)
- Joan O'Keeffe
- Department of Biochemistry, National University of Ireland, Galway, Ireland
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Alipour M, Omri A, Smith MG, Suntres ZE. Prophylactic effect of liposomal N-acetylcysteine against LPS-induced liver injuries. ACTA ACUST UNITED AC 2008; 13:297-304. [PMID: 17986488 DOI: 10.1177/0968051907085062] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The aim of this study was to evaluate and compare the effectiveness of N-acetylcysteine (NAC) and liposomally-encapsulated NAC (L-NAC) in ameliorating the hepatotoxic effects of lipopolysaccharide (LPS). LPS, a major cell wall molecule of Gram-negative bacteria and the principal initiator of septic shock, causes liver injury in vivo that is dependent on neutrophils, platelets, and several inflammatory mediators, including tumour necrosis factor-alpha (TNF-alpha). Male Sprague-Dawley rats were pretreated intravenously with saline, plain liposomes (dipalmitoylphosphatidylcholine [DPPC]), NAC (25 mg/kg body weight), or L-NAC (25 mg/kg NAC body weight) and 4 h later were challenged intravenously with LPS (Escherichia coli O111:B4, 1.0 mg/kg body weight); animals were killed 20 h post-LPS challenge. Hepatic cell injury was evaluated by measuring the alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities in plasma. LPS-induced activation of the inflammatory response was evaluated by measuring the levels of myeloperoxidase activity and chloramine concentration in liver homogenates as well as TNF-alpha levels in plasma. The hepatic levels of lipid peroxidation products and non-protein thiols (NPSH) were used to assess the extent of involvement of oxidative stress mechanisms. In general, challenge of animals with LPS resulted in hepatic injuries, activation of the inflammatory response, decreases in NPSH levels and increases in the levels of lipid peroxidation products (malondialdehyde and 4-hydroxyalkenals). Pretreatment of animals with NAC or empty liposomes did not have any significant protective effect against LPS-induced hepatotoxicity. On the other hand, pretreatment of animals with an equivalent dose of L-NAC conferred protection against the liver injuries induced following LPS challenge. These data suggest that NAC when delivered as a liposomal formulation is a potentially more effective prophylactic pharmacological agent in alleviating LPS-induced liver injuries.
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Affiliation(s)
- Misagh Alipour
- The Novel Drug and Vaccine Delivery Systems Facility, Laurentian University, Sudbury, Ontario, Canada
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Moran AP. Relevance of fucosylation and Lewis antigen expression in the bacterial gastroduodenal pathogen Helicobacter pylori. Carbohydr Res 2007; 343:1952-65. [PMID: 18279843 DOI: 10.1016/j.carres.2007.12.012] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 11/23/2007] [Accepted: 12/17/2007] [Indexed: 12/12/2022]
Abstract
Helicobacter pylori is a prevalent bacterial, gastroduodenal pathogen of humans that can express Lewis (Le) and related antigens in the O-chains of its surface lipopolysaccharide. The O-chains of H. pylori are commonly composed of internal Le(x) units with terminal Le(x) or Le(y) units or, in some strains, with additional units of Le(a), Le(b), Le(c), sialyl-Le(x) and H-1 antigens, as well as blood groups A and B, thereby producing a mosaicism of antigenic units expressed. The genetic determination of the Le antigen biosynthetic pathways in H. pylori has been studied, and despite striking functional similarity, low sequence homology occurs between the bacterial and mammalian alpha(1,3/4)- and alpha(1,2)-fucosyltransferases. Factors affecting Le antigen expression in H. pylori, that can influence the biological impact of this molecular mimicry, include regulation of fucosyltransferase genes through slipped-strand mispairing, the activity and expression levels of the functional enzymes, the preferences of the expressed enzyme for distinctive acceptor molecules and the availability of activated sugar intermediates. Le mimicry was initially implicated in immune evasion and gastric adaptation by the bacterium, but more recent studies show a role in gastric colonization and bacterial adhesion with galectin-3 identified as the gastric receptor for polymeric Le(x) on the bacterium. From the host defence aspect, innate immune recognition of H. pylori by surfactant protein D is influenced by the extent of LPS fucosylation. Furthermore, Le antigen expression affects both the inflammatory response and T-cell polarization that develops after infection. Although controversial, evidence suggests that long-term H. pylori infection can induce autoreactive anti-Le antibodies cross-reacting with the gastric mucosa, in part leading to the development of gastric atrophy. Thus, Le antigen expression and fucosylation in H. pylori have multiple biological effects on pathogenesis and disease outcome.
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Affiliation(s)
- Anthony P Moran
- Department of Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
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