1
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Plum M, Tjerrild L, Raiber T, Bantleon F, Bantleon S, Miehe M, Jabs F, Seismann H, Möbs C, Pfützner W, Jakob T, Andersen GR, Spillner E. Structural and functional analyses of antibodies specific for modified core N-glycans suggest a role in T H 2 responses. Allergy 2023; 78:121-130. [PMID: 35726192 PMCID: PMC10083920 DOI: 10.1111/all.15417] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Revised: 04/19/2022] [Accepted: 05/20/2022] [Indexed: 12/29/2022]
Abstract
BACKGROUND Immune responses to N-glycan structures from allergens and parasites are often associated with pronounced, high affinity IgE reactivities. Cross-reactive carbohydrate determinants (CCDs) are constituted by modified N-glycan core structures and represent the most frequently recognized epitopes in allergic immune responses. Although recently accepted as potentially allergenic epitopes, the biological and clinical relevance as well as structural and functional characteristics of CCD-specific antibodies remain elusive. METHODS In order to gain structural insights into the recognition of CCDs, two specific antibody fragments were isolated from a leporid immune repertoire library and converted into human/leporid IgE and IgG formats. The antibody formats were assessed by ELISA and surface plasmon resonance, structural and functional analyses were performed by X-ray crystallography, mediator release, and ELIFAB assays. RESULTS The recombinant IgE exhibited highly specific interactions with different types of CCDs on numerous CCD-carrying glycoproteins. Crystal structures of two CCD-specific antibodies, one of which in complex with a CCD-derived disaccharide emphasize that mechanisms of core glycan epitope recognition are as specific as those governing protein epitope recognition. The rIgE triggered immediate cellular responses via FcεRI cross-linking and mediated facilitated antigen presentation by binding of IgE/antigen complexes to CD23, a process that also could be blocked by IgG of allergic patients. CONCLUSIONS Our study provides evidence for the relevance of N-glycan recognition in TH 2 responses and corroborates that IgE and IgG antibodies to ubiquitous carbohydrate epitopes can be equivalent to those directed against proteinaceous epitopes with implications for diagnostic and immunotherapeutic concepts.
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Affiliation(s)
- Melanie Plum
- Immunological Biotechnology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark.,Division of Clinical and Molecular Allergology, Research Center Borstel, Leibniz Lung Center, German Center for Lung Research (DZL), Borstel, Germany
| | - Luna Tjerrild
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Tim Raiber
- Immunological Biotechnology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark.,Institute of Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Hamburg, Germany
| | - Frank Bantleon
- Immunological Biotechnology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark
| | - Sara Bantleon
- Immunological Biotechnology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark.,Institute of Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Hamburg, Germany
| | - Michaela Miehe
- Immunological Biotechnology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark
| | - Frederic Jabs
- Immunological Biotechnology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark.,Institute of Biochemistry and Molecular Biology, Department of Chemistry, University of Hamburg, Hamburg, Germany
| | - Henning Seismann
- Department of Oncology and Hematology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Christian Möbs
- Clinical & Experimental Allergology, Department of Dermatology and Allergology, Philipps University Marburg, Marburg, Germany
| | - Wolfgang Pfützner
- Clinical & Experimental Allergology, Department of Dermatology and Allergology, Philipps University Marburg, Marburg, Germany
| | - Thilo Jakob
- Department of Dermatology and Allergy, University Medical Center Giessen, Justus Liebig University, Giessen, Germany
| | - Gregers R Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Edzard Spillner
- Immunological Biotechnology, Department of Biological and Chemical Engineering, Aarhus University, Aarhus, Denmark
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2
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Monoclonal Antibody to CD14, TLR4, or CD11b: Impact of Epitope and Isotype Specificity on ROS Generation by Human Granulocytes and Monocytes. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:5708692. [PMID: 33294123 PMCID: PMC7700042 DOI: 10.1155/2020/5708692] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 09/24/2020] [Accepted: 11/10/2020] [Indexed: 02/01/2023]
Abstract
Lipopolysaccharides (LPSs or endotoxins) from Gram-negative bacteria represent pathogen-associated molecular patterns (PAMPs) that are recognized by CD14 and Toll-like receptor 4 (TLR4). Lipopolysaccharides prime polymorphonuclear leukocytes (PMNs) for substantial production of reactive oxygen species (ROS) during its response to secondary stimuli such as chemoattractants or pathogens. The excessive ROS production can damage surrounding host tissues, thereby amplifying the inflammatory reaction caused by pathogens. Today, specific antibodies against CD14, TLR4, and CD11b are being used as the essential tools to elucidate the role of these receptors in acute inflammation and some of these antibodies have advised as therapeutic agents for clinical use. Because each antibody has two antigen-binding arms [F(ab′)2] and one Fc arm, its effect on cellular response is much more complicated rather than simple blockage of target receptor. In fact, IgG antibody, once bound to target receptor, engages Fc receptors γ (FcγRs) and thereby is able to activate the adaptive immune system. The consequences of antibody-dependent binary heterotypic association of CD14, TLR4, or CD11b with FcγRs as well as homotypic one on ROS production are not well elucidated. Moreover, the consequences of antigenic recognition of CD14, TLR4, or CD11b by specific F(ab′)2 fragments are not always investigated. In this review, we will discuss known mechanisms underlying the therapeutic efficiency of CD14, TLR4, and CD11b/CD18 antibodies with a focus on LPS-dependent ROS or cytokine production by PMNs or monocytes. The impacts of F(ab′)2 as well as antibody IgG subclasses (isotypes) in therapeutic efficiency or agonistic potency of known antibodies against abovementioned receptors are presented. We also pay attention to how the efficiency of different IgG antibody subclasses is modulated during LPS-induced inflammation and by production of priming agents such as interferon γ (IFN-γ). Our review reinforces the molecular targets and therapeutic approaches to amelioration of harmful consequences of excessive activation of human pattern recognition receptors.
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3
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Suster C, Baxendale IR, Mihovilovic MD, Stanetty C. Straight Forward and Versatile Differentiation of the l- glycero and d- glycero-d- manno Heptose Scaffold. Front Chem 2020; 8:625. [PMID: 32850647 PMCID: PMC7411327 DOI: 10.3389/fchem.2020.00625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 06/15/2020] [Indexed: 01/08/2023] Open
Abstract
Bacterial lipopolysaccharides (LPS) are important bio-medical structures, playing a major role in the interaction with human immune systems. Their core regions, containing multiple units of l-glycero-d-manno heptoses (l,d-heptose), are highly conserved structurally (with O3 and O7 glycosidic bonds), making them an epitope of high interest for the potential development of new antibiotics and vaccines. Research in this field has always been restricted by the limited availability of the parent l,d-heptose as well as its biochemical epimeric precursor d-glycero-d-manno heptose (d,d-heptose). This problem of availability has recently been solved by us, through a rapid and efficient practical synthesis of l,d-manno-heptose peracetate demonstrated at scale. Herein we report an optimized, technically simple and versatile synthetic strategy for the differentiation of both the l-glycero and d-glycero-d-manno heptose scaffolds. Our approach is based on an orthoester methodology for the differentiation of all three positions of the sugar core using a O6, O7-tetraisopropyl disiloxyl (TIPDS) protecting group for the exocyclic positions. Furthermore, the regioselective opening toward 7-OH acceptors (6O-FTIPDS ethers) differentiates the exocyclic diol which has been demonstrated with a broader set of substrates and for both manno-heptoses for the first time.
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Affiliation(s)
- Christoph Suster
- Faculty of Technical Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria
| | - Ian R Baxendale
- Department of Chemistry, University of Durham, Durham, United Kingdom
| | - Marko D Mihovilovic
- Faculty of Technical Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria
| | - Christian Stanetty
- Faculty of Technical Chemistry, Institute of Applied Synthetic Chemistry, TU Wien, Vienna, Austria
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4
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Lou Q, Hua Q, Zhang L, Yang Y. Dimethylformamide-Modulated Kdo Glycosylation for Stereoselective Synthesis of α-Kdo Glycosides. Org Lett 2020; 22:981-985. [PMID: 31917587 DOI: 10.1021/acs.orglett.9b04509] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A simple and direct DMF-modulated α-selective Kdo glycosylation approach for the stereoselective synthesis of the α-linked Kdo glycosides is developed. Glycosylation of the readily available peracetylated Kdo ortho-hexynylbenzoate with common acceptor alcohols using SPhosAuNTf2 as a promoter and DMF as a modulating molecule afforded a range of Kdo glycosides with good α-selectivities. Furthermore, the present method is effectively applied in the latent-active synthesis of the α-linked di-Kdo glycoside bearing a linker at the reducing end. Finally, the first observation of a Kdo imidinium ion in the low-temperature NMR provides evidence for the plausible mechanism of the DMF-modulated α-selective Kdo glycosylation.
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Affiliation(s)
- Qixin Lou
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , China
| | - Qingting Hua
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , China
| | - Liangliang Zhang
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , China
| | - You Yang
- Shanghai Key Laboratory of New Drug Design, School of Pharmacy , East China University of Science and Technology , 130 Meilong Road , Shanghai 200237 , China
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5
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Trattnig N, Blaukopf M, Bruxelle JF, Pantophlet R, Kosma P. Synthesis of an Undecasaccharide Featuring an Oligomannosidic Heptasaccharide and a Bacterial Kdo-lipid A Backbone for Eliciting Neutralizing Antibodies to Mammalian Oligomannose on the HIV-1 Envelope Spike. J Am Chem Soc 2019; 141:7946-7954. [PMID: 31010286 PMCID: PMC6524000 DOI: 10.1021/jacs.9b02872] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
Lipooligosaccharides (LOS) from the
bacterium Rhizobium
radiobacter Rv3 are structurally related to antigenic mammalian
oligomannoses on the HIV-1 envelope glycoprotein spike that are targets
for broadly neutralizing antibodies. Here, we prepared a hybrid structure
of viral and bacterial epitopes as part of a vaccine design strategy
to elicit oligomannose-specific HIV-neutralizing antibodies using
glycoconjugates based on the Rv3 LOS structure. Starting from a Kdo2GlcNAc2 tetrasaccharide precursor, a central orthogonally
protected mannose trichloroacetimidate donor was coupled to OH-5 of
the innermost Kdo residue. To assemble larger glycans, the N-acetylamino groups of the glucosamine units were converted
to imides to prevent formation of unwanted imidate byproducts. Blockwise
coupling of the pentasaccharide acceptor with an α-(1→2)-linked
mannotriosyl trichloroacetimidate donor introduced the D1-arm fragment.
Glycosylation of O-6 of the central branching mannose
with an α-(1→2)-α-(1→6)-linked mannotriosyl
trichloroacetimidate donor unit then furnished the undecasaccharide
harboring a D3-arm extension. Global deprotection yielded the 3-aminopropyl
ligand, which was activated as an isothiocyanate or adipic acid succinimidoyl
ester and conjugated to CRM197. However, representative
oligomannose-specific HIV-neutralizing antibodies bound the undecasaccharide
conjugates poorly. Possible reasons for this outcome are discussed
herein along with paths for improvement.
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Affiliation(s)
- Nino Trattnig
- Department of Chemistry , University of Natural Resources and Life Sciences , A-1190 Vienna , Austria
| | - Markus Blaukopf
- Department of Chemistry , University of Natural Resources and Life Sciences , A-1190 Vienna , Austria
| | | | | | - Paul Kosma
- Department of Chemistry , University of Natural Resources and Life Sciences , A-1190 Vienna , Austria
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6
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Human Toll-Like Receptor 4 (hTLR4): Structural and functional dynamics in cancer. Int J Biol Macromol 2019; 122:425-451. [DOI: 10.1016/j.ijbiomac.2018.10.142] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/10/2018] [Accepted: 10/18/2018] [Indexed: 12/23/2022]
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7
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Nagy E, Nagy G, Power CA, Badarau A, Szijártó V. Anti-bacterial Monoclonal Antibodies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1053:119-153. [PMID: 29549638 DOI: 10.1007/978-3-319-72077-7_7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The failing efficacy of antibiotics and the high mortality rate among high-risk patients calls for new treatment modalities for bacterial infections. Due to the vastly divergent pathogenesis of human pathogens, each microbe requires a tailored approach. The main modes of action of anti-bacterial antibodies are virulence factor neutralization, complement-mediated bacterial lysis and enhancement of opsonophagocytic uptake and killing (OPK). Gram-positive bacteria cannot be lysed by complement and their pathogenesis often involves secreted toxins, therefore typically toxin-neutralization and OPK activity are required to prevent and ameliorate disease. In fact, the success stories in terms of approved products, in the anti-bacterial mAb field are based on toxin neutralization (Bacillus anthracis, Clostridium difficile). In contrast, Gram-negative bacteria are vulnerable to antibody-dependent complement-mediated lysis, while their pathogenesis rarely relies on secreted exotoxins, and involves the pro-inflammatory endotoxin (lipopolysaccharide). Given the complexity of bacterial pathogenesis, antibody therapeutics are expected to be most efficient upon targeting more than one virulence factor and/or combining different modes of action. The improved understanding of bacterial pathogenesis combined with the versatility and maturity of antibody discovery technologies available today are pivotal for the design of novel anti-bacterial therapeutics. The intensified research generating promising proof-of-concept data, and the increasing number of clinical programs with anti-bacterial mAbs, indicate that the field is ready to fulfill its promise in the coming years.
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Affiliation(s)
- Eszter Nagy
- Arsanis Biosciences GmbH/Arsanis, Inc, Vienna, Austria.
| | - Gábor Nagy
- Arsanis Biosciences GmbH/Arsanis, Inc, Vienna, Austria
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8
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9
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Mi X, Lou Q, Fan W, Zhuang L, Yang Y. Gold(I)-catalyzed synthesis of β-Kdo glycosides using Kdo ortho-hexynylbenzoate as donor. Carbohydr Res 2017; 448:161-165. [DOI: 10.1016/j.carres.2017.04.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 04/25/2017] [Accepted: 04/25/2017] [Indexed: 11/28/2022]
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10
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Szijártó V, Guachalla LM, Hartl K, Varga C, Badarau A, Mirkina I, Visram ZC, Stulik L, Power CA, Nagy E, Nagy G. Endotoxin neutralization by an O-antigen specific monoclonal antibody: A potential novel therapeutic approach against Klebsiella pneumoniae ST258. Virulence 2017; 8:1203-1215. [PMID: 28103139 PMCID: PMC5711440 DOI: 10.1080/21505594.2017.1279778] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Klebsiella pneumoniae ST258 is a globally distributed multi-drug resistant pathogen responsible for severe invasive infections. In this study, the different virulence potential of K. pneumoniae ST258 isolates in endotoxin susceptible versus resistant animal models was shown. Furthermore, ST258 clinical isolates were found highly sensitive to the bactericidal effect of naive animal and human serum. These observations imply that LPS, released from the rapidly lysed bacteria, may contribute to the high mortality associated with ST258 bacteremia cases. A humanized version (mAb A1102) of a previously described murine mAb specific for the conserved LPS O-antigen, was tested for endotoxin neutralization. A1102 was able to neutralize TLR-4 activation by ST258-derived LPS in vitro with an efficacy exceeding that of polymyxin B by 3 orders of magnitude. Passive immunization with A1102 afforded a significant level of protection in a galactosamine-sensitized mouse model of endotoxemia, induced by ST258-derived LPS, or upon challenge with live bacteria. Efficacy was retained using an aglycosylated IgG, as well as upon complement depletion, suggesting that Fc-independent endotoxin neutralization may be the main protective mechanism in this model, in spite of the complement-dependent bactericidal and opsonic activities additionally observed for A1102 in vitro. Furthermore, rabbits that are naturally highly susceptible to endotoxin, were also significantly protected by low doses of A1102 when challenged with an ST258 strain. Given this unique mode of action and the high protective efficacy of this mAb, passive immunization, as prophylactic or adjunct therapeutic approach for the treatment of infections caused by ST258 isolates should be considered.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Eszter Nagy
- a Arsanis Biosciences GmbH , Vienna , Austria
| | - Gábor Nagy
- a Arsanis Biosciences GmbH , Vienna , Austria
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11
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Polyspecificity of Anti-lipid A Antibodies and Its Relevance to the Development of Autoimmunity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 966:181-202. [PMID: 28887790 DOI: 10.1007/5584_2017_94] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The process of natural selection favours germ-line gene segments that encode CDRs that have the ability to recognize a range of structurally related antigens. This presents an immunological advantage to the host, as it can confer protection against a common pathogen and still cope with new or changing antigens. Cross-reactive and polyspecific antibodies also play a central role in autoimmune responses, and a link has been shown to exist between auto-reactive B cells and certain bacterial infections. Bacterial DNA, lipids, and carbohydrates have been implicated in the progression of autoimmune diseases such as systemic lupus erythematosus. As well, reports of anti-lipid A antibody polyspecificity towards single-stranded DNA together with the observed sequence homology amongst isolated auto- and anti-lipid A antibodies has prompted further study of this phenomenon. Though the lipid A epitope appears cryptic during Gram-negative bacterial infection, there have been several reported instances of lipid A-specific antibodies isolated from human sera, some of which have exhibited polyspecificity for single stranded DNA. In such cases, the breakdown of negative selection through polyspecificity can have the unfortunate consequence of autoimmune disease. This review summarizes current knowledge regarding such antibodies and emphasizes the features of S1-15, A6, and S55-5, anti-lipid A antibodies whose structures were recently determined by X-ray crystallography.
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12
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Walter M, Kohout C, Blaukopf M, Kosma P. Synthesis of 3- O- and 4- O-(2-aminoethylphosphono) derivatives of methyl l- glycero-α-d- manno-heptopyranoside. MONATSHEFTE FUR CHEMIE 2016; 148:111-119. [PMID: 28127097 PMCID: PMC5225220 DOI: 10.1007/s00706-016-1868-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 10/25/2016] [Indexed: 11/06/2022]
Abstract
ABSTRACT Phosphoethanolamine derivatives of the bacterial saccharide l-glycero-d-manno-heptose have been prepared using a phosphoramidite-based coupling reaction at position 4 of a side-chain-protected 2,3-O-orthoester methyl heptoside and at position 3 of a 3,4-diol heptoside, respectively. Global deprotection afforded the corresponding 2-aminoethylphosphodiester derivatives as substrates for crystallographic and binding studies with lectins and antibodies targeting the inner core structure of bacterial lipopolysaccharides. GRAPHICAL ABSTRACT
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Affiliation(s)
- Martin Walter
- Department of Chemistry, University of Natural Resources and Life Sciences-Vienna, Vienna, Austria
| | - Claudia Kohout
- Department of Chemistry, University of Natural Resources and Life Sciences-Vienna, Vienna, Austria
| | - Markus Blaukopf
- Department of Chemistry, University of Natural Resources and Life Sciences-Vienna, Vienna, Austria
| | - Paul Kosma
- Department of Chemistry, University of Natural Resources and Life Sciences-Vienna, Vienna, Austria
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13
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Munford RS. Endotoxemia-menace, marker, or mistake? J Leukoc Biol 2016; 100:687-698. [PMID: 27418356 DOI: 10.1189/jlb.3ru0316-151r] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 06/27/2016] [Indexed: 01/19/2023] Open
Abstract
Endotoxemia is in its scientific ascendancy. Never has blood-borne, Gram-negative bacterial endotoxin (LPS) been invoked in the pathogenesis of so many diseases-not only as a trigger for septic shock, once its most cited role, but also as a contributor to atherosclerosis, obesity, chronic fatigue, metabolic syndrome, and many other conditions. Finding elevated plasma endotoxin levels has been essential supporting evidence for each of these links, yet the assays used to detect and quantitate endotoxin have important limitations. This article describes several assays for endotoxin in plasma, reviews what they do and do not measure, and discusses why LPS heterogeneity, LPS trafficking pathways, and host LPS inactivation mechanisms should be considered when interpreting endotoxin assay results.
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Affiliation(s)
- Robert S Munford
- Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, USA
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14
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Abstract
Glycosylation chemistry of 3-deoxy-D-manno-oct-2-ulosonic acid units has been considerably developed within the last decade. This review covers major achievements with respect to improved yields and anomeric selectivity as well as suppression of the elimination side reaction via selection of dedicated protecting groups and appropriate activation of the anomeric center.
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Affiliation(s)
- Paul Kosma
- University of Natural Resources and Life Sciences-Vienna, Department of Chemistry, Muthgasse 18, A-1190 Vienna, Austria
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15
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Burmann BM, Holdbrook DA, Callon M, Bond PJ, Hiller S. Revisiting the interaction between the chaperone Skp and lipopolysaccharide. Biophys J 2016; 108:1516-1526. [PMID: 25809264 DOI: 10.1016/j.bpj.2015.01.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 12/22/2014] [Accepted: 01/28/2015] [Indexed: 10/23/2022] Open
Abstract
The bacterial outer membrane comprises two main classes of components, lipids and membrane proteins. These nonsoluble compounds are conveyed across the aqueous periplasm along specific molecular transport routes: the lipid lipopolysaccharide (LPS) is shuttled by the Lpt system, whereas outer membrane proteins (Omps) are transported by chaperones, including the periplasmic Skp. In this study, we revisit the specificity of the chaperone-lipid interaction of Skp and LPS. High-resolution NMR spectroscopy measurements indicate that LPS interacts with Skp nonspecifically, accompanied by destabilization of the Skp trimer and similar to denaturation by the nonnatural detergent lauryldimethylamine-N-oxide (LDAO). Bioinformatic analysis of amino acid conservation, structural analysis of LPS-binding proteins, and MD simulations further confirm the absence of a specific LPS binding site on Skp, making a biological relevance of the interaction unlikely. Instead, our analysis reveals a highly conserved salt-bridge network, which likely has a role for Skp function.
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Affiliation(s)
| | | | | | - Peter J Bond
- Bioinformatics Institute (A(∗)STAR), Singapore; Department of Biological Sciences, National University of Singapore, Singapore
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16
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Haji-Ghassemi O, Müller-Loennies S, Rodriguez T, Brade L, Grimmecke HD, Brade H, Evans SV. The Combining Sites of Anti-lipid A Antibodies Reveal a Widely Utilized Motif Specific for Negatively Charged Groups. J Biol Chem 2016; 291:10104-18. [PMID: 26933033 DOI: 10.1074/jbc.m115.712448] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Indexed: 01/29/2023] Open
Abstract
Lipopolysaccharide dispersed in the blood by Gram-negative bacteria can be a potent inducer of septic shock. One research focus has been based on antibody sequestration of lipid A (the endotoxic principle of LPS); however, none have been successfully developed into a clinical treatment. Comparison of a panel of anti-lipid A antibodies reveals highly specific antibodies produced through distinct germ line precursors. The structures of antigen-binding fragments for two homologous mAbs specific for lipid A, S55-3 and S55-5, have been determined both in complex with lipid A disaccharide backbone and unliganded. These high resolution structures reveal a conserved positively charged pocket formed within the complementarity determining region H2 loops that binds the terminal phosphates of lipid A. Significantly, this motif occurs in unrelated antibodies where it mediates binding to negatively charged moieties through a range of epitopes, including phosphorylated peptides used in diagnostics and therapeutics. S55-3 and S55-5 have combining sites distinct from anti-lipid A antibodies previously described (as a result of their separate germ line origin), which are nevertheless complementary both in shape and charge to the antigen. S55-3 and S55-5 display similar avidity toward lipid A despite possessing a number of different amino acid residues in their combining sites. Binding of lipid A occurs independent of the acyl chains, although the GlcN-O6 attachment point for the core oligosaccharide is buried in the combining site, which explains their inability to recognize LPS. Despite their lack of therapeutic potential, the observed motif may have significant immunological implications as a tool for engineering recombinant antibodies.
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Affiliation(s)
- Omid Haji-Ghassemi
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
| | - Sven Müller-Loennies
- the Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany
| | - Teresa Rodriguez
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
| | - Lore Brade
- the Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany
| | - Hans-Dieter Grimmecke
- the Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany
| | - Helmut Brade
- the Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany
| | - Stephen V Evans
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada and
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17
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Pokorny B, Kosma P. Scope and Limitations of 3-Iodo-Kdo Fluoride-Based Glycosylation Chemistry using N-Acetyl Glucosamine Acceptors. ChemistryOpen 2015; 4:722-8. [PMID: 27308198 PMCID: PMC4906502 DOI: 10.1002/open.201500126] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Indexed: 12/11/2022] Open
Abstract
The ketosidic linkage of 3-deoxy-d-manno-octulosonic acid (Kdo) to lipid A constitutes a general structural feature of the bacterial lipopolysaccharide core. Glycosylation reactions of Kdo donors, however, are challenging due to the absence of a directing group at C-3 and elimination reactions resulting in low yields and anomeric selectivities of the glycosides. While 3-iodo-Kdo fluoride donors showed excellent glycosyl donor properties for the assembly of Kdo oligomers, glycosylation of N-acetyl-glucosamine derivatives was not straightforward. Specifically, oxazoline formation of a β-anomeric methyl glycoside, as well as iodonium ion transfer to an allylic aglycon was found. In addition, dehalogenation of the directing group by hydrogen atom transfer proved to be incompatible with free hydroxyl groups next to benzyl groups. In contrast, glycosylation of a suitably protected methyl 2-acetamido-2-deoxy-α-d-glucopyranoside derivative and subsequent deiodination proceeded in excellent yields and α-specificity, and allowed for subsequent 4-O-phosphorylation. This way, the disaccharides α-Kdo-(2→6)-α-GlcNAcOMe and α-Kdo-(2→6)-α-GlcNAcOMe-4-phosphate were obtained in good overall yields.
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Affiliation(s)
- Barbara Pokorny
- Department of ChemistryUniversity of Natural Resources and Life Sciences-ViennaMuthgasse 181190ViennaAustria
| | - Paul Kosma
- Department of ChemistryUniversity of Natural Resources and Life Sciences-ViennaMuthgasse 181190ViennaAustria
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18
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Haji-Ghassemi O, Müller-Loennies S, Rodriguez T, Brade L, Kosma P, Brade H, Evans SV. Structural Basis for Antibody Recognition of Lipid A: INSIGHTS TO POLYSPECIFICITY TOWARD SINGLE-STRANDED DNA. J Biol Chem 2015; 290:19629-40. [PMID: 26085093 DOI: 10.1074/jbc.m115.657874] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Indexed: 01/14/2023] Open
Abstract
Septic shock is a leading cause of death, and it results from an inflammatory cascade triggered by the presence of microbial products in the blood. Certain LPS from Gram-negative bacteria are very potent inducers and are responsible for a high percentage of septic shock cases. Despite decades of research, mAbs specific for lipid A (the endotoxic principle of LPS) have not been successfully developed into a clinical treatment for sepsis. To understand the molecular basis for the observed inability to translate in vitro specificity for lipid A into clinical potential, the structures of antigen-binding fragments of mAbs S1-15 and A6 have been determined both in complex with lipid A carbohydrate backbone and in the unliganded form. The two antibodies have separate germ line origins that generate two markedly different combining-site pockets that are complementary both in shape and charge to the antigen. mAb A6 binds lipid A through both variable light and heavy chain residues, whereas S1-15 utilizes exclusively the variable heavy chain. Both antibodies bind lipid A such that the GlcN-O6 attachment point for the core oligosaccharide is buried in the combining site, which explains the lack of LPS recognition. Longstanding reports of polyspecificity of anti-lipid A antibodies toward single-stranded DNA combined with observed homology of S1-15 and A6 and the reports of several single-stranded DNA-specific mAbs prompted the determination of the structure of S1-15 in complex with single-stranded DNA fragments, which may provide clues about the genesis of autoimmune diseases such as systemic lupus erythematosus, thyroiditis, and rheumatic autoimmune diseases.
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Affiliation(s)
- Omid Haji-Ghassemi
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada
| | - Sven Müller-Loennies
- the Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany, and
| | - Teresa Rodriguez
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada
| | - Lore Brade
- the Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany, and
| | - Paul Kosma
- the Department of Chemistry, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Helmut Brade
- the Research Center Borstel, Leibniz-Center for Medicine and Biosciences, Parkallee 22, Borstel D-23845, Germany, and
| | - Stephen V Evans
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 3P6, Canada,
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19
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Haji-Ghassemi O, Blackler RJ, Martin Young N, Evans SV. Antibody recognition of carbohydrate epitopes†. Glycobiology 2015; 25:920-52. [PMID: 26033938 DOI: 10.1093/glycob/cwv037] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Accepted: 05/24/2015] [Indexed: 12/14/2022] Open
Abstract
Carbohydrate antigens are valuable as components of vaccines for bacterial infectious agents and human immunodeficiency virus (HIV), and for generating immunotherapeutics against cancer. The crystal structures of anti-carbohydrate antibodies in complex with antigen reveal the key features of antigen recognition and provide information that can guide the design of vaccines, particularly synthetic ones. This review summarizes structural features of anti-carbohydrate antibodies to over 20 antigens, based on six categories of glyco-antigen: (i) the glycan shield of HIV glycoproteins; (ii) tumor epitopes; (iii) glycolipids and blood group A antigen; (iv) internal epitopes of bacterial lipopolysaccharides; (v) terminal epitopes on polysaccharides and oligosaccharides, including a group of antibodies to Kdo-containing Chlamydia epitopes; and (vi) linear homopolysaccharides.
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Affiliation(s)
- Omid Haji-Ghassemi
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8P 3P6
| | - Ryan J Blackler
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8P 3P6
| | - N Martin Young
- Human Health Therapeutics, National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6
| | - Stephen V Evans
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8P 3P6
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20
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Stanetty C, Baxendale IR. Large-Scale Synthesis of Crystalline 1,2,3,4,6,7-Hexa- O-acetyl-l- glycero-α-d- manno-heptopyranose. European J Org Chem 2015; 2015:2718-2726. [PMID: 26097405 PMCID: PMC4464551 DOI: 10.1002/ejoc.201500024] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Indexed: 01/14/2023]
Abstract
The higher-carbon sugar l-glycero-d-manno-heptose is a major constituent of the inner core region of the lipopolysaccharide (LPS) of many Gram-negative bacteria. All preparative routes used to date require multiple steps, and scalability has been rarely addressed. Here a highly practical synthesis of crystalline 1,2,3,4,6,7-hexa-O-acetyl-l-glycero-α-d-manno-heptopyranose by a simple four-step sequence starting from l-lyxose is disclosed. Only two recrystallisations are required and the process was demonstrated on a >100 mmol scale, yielding 41 g of the target compound.
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Affiliation(s)
- Christian Stanetty
- Department of Chemistry, Durham UniversitySouth Road, Durham, DH1 3LE, United Kingdom
| | - Ian R Baxendale
- Department of Chemistry, Durham UniversitySouth Road, Durham, DH1 3LE, United Kingdom
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21
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Pokorny B, Kosma P. Synthesis of chlamydia lipopolysaccharide haptens through the use of α-specific 3-iodo-Kdo fluoride glycosyl donors. Chemistry 2015; 21:305-13. [PMID: 25354167 PMCID: PMC4768360 DOI: 10.1002/chem.201405424] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Indexed: 12/20/2022]
Abstract
A scalable approach towards high-yielding and (stereo)selective glycosyl donors of the 2-ulosonic acid Kdo (3-deoxy-D-manno-oct-2-ulosonic acid) is a fundamental requirement for the development of vaccines against Gram-negative bacteria. Herein, we disclose a short synthetic route to 3-iodo Kdo fluoride donors from Kdo glycal esters that enable efficient α-specific glycosylations and significantly suppress the elimination side reaction. The potency of these donors is demonstrated in a straightforward, six-step synthesis of a branched Chlamydia-related Kdo-trisaccharide ligand without the need for protecting groups at the Kdo glycosyl acceptor. The approach was further extended to include sequential iteration of the basic concept to produce the linear Chlamydia-specific α-Kdo-(2→8)-α-Kdo-(2→4)-α-Kdo trisaccharide in a good overall yield.
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Affiliation(s)
- Barbara Pokorny
- Department of Chemistry, University of Natural Resources and Life Sciences-Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Paul Kosma
- Department of Chemistry, University of Natural Resources and Life Sciences-Vienna, Muthgasse 18, A-1190 Vienna, Austria
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22
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Nijland R, Hofland T, van Strijp JAG. Recognition of LPS by TLR4: potential for anti-inflammatory therapies. Mar Drugs 2014; 12:4260-73. [PMID: 25056632 PMCID: PMC4113827 DOI: 10.3390/md12074260] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Revised: 06/10/2014] [Accepted: 07/04/2014] [Indexed: 12/29/2022] Open
Abstract
LPS molecules of marine bacteria show structures distinct from terrestrial bacteria, due to the different environment that marine bacteria live in. Because of these different structures, lipid A molecules from marine bacteria are most often poor stimulators of the Toll-like receptor 4 (TLR4) pathway. Due to their low stimulatory potential, these lipid A molecules are suggested to be applicable as antagonists of TLR4 signaling in sepsis patients, where this immune response is amplified and unregulated. Antagonizing lipid A molecules might be used for future therapies against sepsis, therapies that currently do not exist. In this review, we will discuss these differences in lipid A structures and their recognition by the immune system. The modifications present in marine lipid A structures are described, and their potential as LPS antagonists will be discussed. Finally, since clinical trials built on antagonizing lipid A molecules have proven unsuccessful, we propose to also focus on different aspects of the TLR4 signaling pathway when searching for new potential drugs. Furthermore, we put forward the notion that bacteria probably already produce inhibitors of TLR4 signaling, making these bacterial products interesting molecules to investigate for future sepsis therapies.
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Affiliation(s)
- Reindert Nijland
- Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
| | - Tom Hofland
- Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
| | - Jos A G van Strijp
- Medical Microbiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands.
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23
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Pokorny B, Müller-Loennies S, Kosma P. Synthesis of α-d-glucosyl substituted methyl glycosides of 3-deoxy-α-d-manno- and d-glycero-α-d-talo-oct-2-ulosonic acid (Kdo/Ko) corresponding to inner core fragments of Acinetobacter lipopolysaccharide. Carbohydr Res 2014; 391:66-81. [PMID: 24785390 PMCID: PMC4019464 DOI: 10.1016/j.carres.2014.03.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 02/26/2014] [Accepted: 03/05/2014] [Indexed: 11/18/2022]
Abstract
Synthesis of Acinetobacter LPS fragments with orthogonal protecting pattern. First synthesis of Ko-glycosides substituted at position 5. α-Selective glucosylation using benzylidene trifluoroacetimidate donor. Regioselective phosphorylation at C-6 of a glucosyl substituent.
The α-d-glucopyranosyl-(1→5)-substituted methyl glycosides of 3-deoxy-α-d-manno-oct-2-ulosonic acid (Kdo), 3-deoxy-α-d-lyxo-hept-2-ulosonic acid (Kdh), and d-glycero-α-d-talo-oct-2-ulosonic acid (Ko) were prepared using orthogonally protected glycosyl acceptor derivatives via glycosylation with a torsionally disarmed 4,6-O-benzylidene protected trifluoroacetimidate glucosyl donor followed by global deprotection. The related 6-O-phosphoryl-α-d-glucopyranosyl-(1→5)-substituted Kdo and Kdh derivatives were derived from a benzylidene-protected glucosyl intermediate using phosphoramidite and phosphoryl chloride-based phosphorylation steps, respectively. The deprotected disaccharides serve as ligands to study lectin binding of Acinetobacter lipopolysaccharide core oligosaccharides.
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Affiliation(s)
- Barbara Pokorny
- Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | | | - Paul Kosma
- Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
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24
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Parker MJ, Gomery K, Richard G, MacKenzie CR, Cox AD, Richards JC, Evans SV. Structural basis for selective cross-reactivity in a bactericidal antibody against inner core lipooligosaccharide from Neisseria meningitidis†,‡. Glycobiology 2014; 24:442-9. [DOI: 10.1093/glycob/cwu009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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25
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Han JE, Wui SR, Kim KS, Cho YJ, Cho WJ, Lee NG. Characterization of the structure and immunostimulatory activity of a vaccine adjuvant, de-O-acylated lipooligosaccharide. PLoS One 2014; 9:e85838. [PMID: 24465739 PMCID: PMC3899070 DOI: 10.1371/journal.pone.0085838] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Accepted: 12/02/2013] [Indexed: 12/20/2022] Open
Abstract
Lipopolysaccharide (LPS) is a major component of the outer membrane of Gram-negative bacteria. LPS elicits strong immunopathological responses during bacterial infection, and the lipid A moiety of LPS is responsible for this immunostimulatory activity. Lipid A exerts its biological activity by sending signals via TLR4 present on immune cells, and TLR4 agonists have been a target for vaccine adjuvant. Previously, we demonstrated an adjuvant activity of deacylated lipooligosaccharide (dLOS) to viral and bacterial antigens. In this study, we characterized the chemical structure of dLOS and evaluated its immunostimulatory activity on mouse and human immune cells in comparison with monophosphoryl lipid A (MPL). dLOS consists of a core oligosaccharide lacking the terminal glucose residue, a glucosamine disaccharide with two phosphate groups, and two N-linked acyl groups. dLOS was similar to MPL in induction of cytokine production in mouse peritoneal macrophages, but was a more potent activator in human monocytes and dendritic cells (DCs). Results of an analysis of allogeneic T cell responses revealed that dLOS induces Th1, Th2, and Th17-type immune responses in a dose-dependent manner. The immunostimulatory activities of dLOS were completely abrogated in TLR4−/− mice, which confirms its TLR4-dependency. These results suggest that in the presence of the core oligosaccharide, O-linked acyl groups of LPS are dispensable for activating the TLR4 signaling pathway. dLOS did not cause any pathological effects or death at 0.25, 0.5, or 1 mg per kg body weight in mice in the acute toxicity tests. This result suggests that dLOS has a low toxicity. dLOS should be considered for further development as a safe and effective adjuvant for human vaccines.
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MESH Headings
- Acylation
- Adjuvants, Immunologic/chemistry
- Adjuvants, Immunologic/pharmacology
- Animals
- CD4-Positive T-Lymphocytes/drug effects
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- Cells, Cultured
- Cytokines/blood
- Cytokines/immunology
- Cytokines/metabolism
- Dendritic Cells/drug effects
- Dendritic Cells/immunology
- Dendritic Cells/metabolism
- Dose-Response Relationship, Drug
- Female
- Flow Cytometry
- Humans
- Immunoblotting
- Lipopolysaccharides/chemistry
- Lipopolysaccharides/immunology
- Lipopolysaccharides/pharmacology
- Macrophages, Peritoneal/drug effects
- Macrophages, Peritoneal/immunology
- Macrophages, Peritoneal/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Molecular Structure
- Monocytes/drug effects
- Monocytes/immunology
- Monocytes/metabolism
- Toll-Like Receptor 4/deficiency
- Toll-Like Receptor 4/genetics
- Toll-Like Receptor 4/immunology
- Vaccines/immunology
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Affiliation(s)
- Ji Eun Han
- Department of Bioscience & Biotechnology, College of Bioscience, Sejong University, Seoul, Republic of Korea
| | - Seo Ri Wui
- Department of Bioscience & Biotechnology, College of Bioscience, Sejong University, Seoul, Republic of Korea
| | - Kwang Sung Kim
- Research & Development Center, EyeGene, Seoul, Republic of Korea
| | - Yang Je Cho
- Research & Development Center, EyeGene, Seoul, Republic of Korea
| | - Wan Je Cho
- Yonsei University Gangnam Severance Hospital, Seoul, Republic of Korea
| | - Na Gyong Lee
- Department of Bioscience & Biotechnology, College of Bioscience, Sejong University, Seoul, Republic of Korea
- * E-mail:
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26
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Stanetty C, Walter M, Kosma P. Convergent synthesis of 4-O-phosphorylated L-glycero-D-manno-heptosyl lipopolysaccharide core oligosaccharides based on regioselective cleavage of a 6,7-O-tetraisopropyldisiloxane-1,3-diyl protecting group. J Org Chem 2014; 79:582-98. [PMID: 24359545 PMCID: PMC3898546 DOI: 10.1021/jo402312x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Indexed: 01/22/2023]
Abstract
The structurally conserved lipopolysaccharide core region of many Gram-negative bacteria is composed of trisaccharides containing 4-O-phosphorylated L-glycero-D-manno-heptose (L,D-Hep) units, which act as ligands for antibodies and lectins. The disaccharides Glc-(1→3)-Hep4P Hep-(1→3)-Hep4P and Hep-(1→7)-Hep4P and the branched trisaccharide Glc-(1→3)-[Hep-(1→7)]-Hep4P, respectively, have been synthesized from a methyl heptopyranoside acceptor in less than 10 steps. The synthetic strategy was based on the early introduction of a phosphotriester at position 4 of heptose followed by a regioselective opening of a 6,7-O-(1,1,3,3-tetraisopropyl-1,3-disiloxane-1,3-diyl) group allowing for a straightforward access to glycosylation at position 7. Perbenzylated N-phenyl trifluoroacetimidate glucosyl and heptosyl derivatives served as α-selective glycosyl donors.
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Affiliation(s)
- Christian Stanetty
- Department
of Chemistry, University of Natural Resources
and Life Sciences, A-1190 Vienna, Austria
| | - Martin Walter
- Department
of Chemistry, University of Natural Resources
and Life Sciences, A-1190 Vienna, Austria
| | - Paul Kosma
- Department
of Chemistry, University of Natural Resources
and Life Sciences, A-1190 Vienna, Austria
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27
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Abstract
Gram-negative bacterial (GNB) infections are a leading cause of serious infections both in hospitals and the community. The mortality remains high despite potent antimicrobials and modern supportive care. In the last decade invasive GNB have become increasingly resistant to commonly used antibiotics, and attempts to intervene with novel biological therapies have been unsuccessful. Earlier studies with antibodies directed against a highly conserved core region in the GNB lipopolysaccharide (LPS, or endotoxin) suggested that this approach may have therapeutic benefit, and led to the development of a subunit vaccine that has progressed to phase 1 clinical testing. Since only a few serogroups of GNB cause bacteremia, O-specific vaccines had been developed, but these were not deployed because of the availability of other therapeutic options at the time. Given the likelihood that new antibiotics will not be soon available, the development of vaccines and antibodies directed against endotoxin, both O and core antigens, deserves a “second look”.
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Affiliation(s)
- Alan S Cross
- Center for Vaccine Development; University of Maryland School of Medicine; Baltimore, MD USA
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