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Huang Y, Cao J, Zhu M, Wang Z, Jin Z, Xiong Z. Nontoxigenic Bacteroides fragilis: A double-edged sword. Microbiol Res 2024; 286:127796. [PMID: 38870618 DOI: 10.1016/j.micres.2024.127796] [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: 09/23/2023] [Revised: 04/12/2024] [Accepted: 05/31/2024] [Indexed: 06/15/2024]
Abstract
The contribution of commensal microbes to human health and disease is unknown. Bacteroides fragilis (B. fragilis) is an opportunistic pathogen and a common colonizer of the human gut. Nontoxigenic B. fragilis (NTBF) and enterotoxigenic B. fragilis (ETBF) are two kinds of B. fragilis. NTBF has been shown to affect the host immune system and interact with gut microbes and pathogenic microbes. Previous studies indicated that certain strains of B. fragilis have the potential to serve as probiotics, based on their observed relationship with the immune system. However, several recent studies have shown detrimental effects on the host when beneficial gut bacteria are found in the digestive system or elsewhere. In some pathological conditions, NTBF may have adverse reactions. This paper presents a comprehensive analysis of NTBF ecology from the host-microbe perspective, encompassing molecular disease mechanisms analysis, bacteria-bacteria interaction, bacteria-host interaction, and the intricate ecological context of the gut. Our review provides much-needed insights into the precise application of NTBF.
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Affiliation(s)
- Yumei Huang
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jiali Cao
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Mengpei Zhu
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Ziwen Wang
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Ze Jin
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Zhifan Xiong
- Department of Gastroenterology, Liyuan Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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2
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Arnolds KL, Yamada E, Neff CP, Schneider JM, Palmer BE, Lozupone CA. Disruption of Genes Encoding Putative Zwitterionic Capsular Polysaccharides of Diverse Intestinal Bacteroides Reduces the Induction of Host Anti-Inflammatory Factors. MICROBIAL ECOLOGY 2023; 85:1620-1629. [PMID: 35596750 PMCID: PMC10167101 DOI: 10.1007/s00248-022-02037-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 05/08/2022] [Indexed: 05/10/2023]
Abstract
Bacterial zwitterionic capsular polysaccharides (ZPS), such as polysaccharide A (PSA) of the intestinal commensal Bacteroides fragilis, have been shown to modulate T cells, including inducing anti-inflammatory IL-10-secreting T regulatory cells (Tregs). We previously used a genomic screen to identify diverse host-associated bacteria with the predicted genetic capacity to produce ZPSs related to PSA of B. fragilis and hypothesized that genetic disruption (KO) of a key functional gene within these operons would reduce the anti-inflammatory activity of these bacteria. We found that ZPS-KO bacteria in two common gut commensals, Bacteroides uniformis and Bacteroides cellulosilyticus, had a reduced ability to induce Tregs and IL-10 in stimulations of human peripheral blood mononuclear cells (PBMCs). Additionally, we found that macrophage stimulated with either wildtype B. fragilis or B. uniformis produced significantly more IL-10 than KOs, indicating a potentially novel function of ZPS of shifting the cytokine response in macrophages to a more anti-inflammatory state. These findings support the hypothesis that these related ZPS may represent a shared strategy to modulate host immune responses.
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Affiliation(s)
- Kathleen L Arnolds
- Department of Immunology and Microbiology, University of Colorado Anschutz, Aurora, CO, USA
| | - Eiko Yamada
- Department of Medicine, University of Colorado Anschutz, Aurora, CO, USA
| | - C Preston Neff
- Department of Medicine, University of Colorado Anschutz, Aurora, CO, USA
| | | | - Brent E Palmer
- Department of Medicine, University of Colorado Anschutz, Aurora, CO, USA
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3
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Baaity Z, von Loewenich FD, Nagy E, Orosz L, Burián K, Somogyvári F, Sóki J. Phenotypic and Molecular Characterization of Carbapenem-Heteroresistant Bacteroides fragilis Strains. Antibiotics (Basel) 2022; 11:antibiotics11050590. [PMID: 35625234 PMCID: PMC9138018 DOI: 10.3390/antibiotics11050590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/15/2022] [Accepted: 04/20/2022] [Indexed: 12/29/2022] Open
Abstract
Carbapenem-resistant Bacteroides fragilis strains usually emerge by an insertion sequence (IS) jump into the upstream region of the cfiA carbapenemase gene. However, intermediate or fully resistant cfiA-positive strains also exist. These do not have such IS element activations, but usually have heterogeneous resistance (HR) phenotypes, as detected by a disc diffusion or gradient tests. Heteroresistance is a serious antibiotic resistance problem, whose molecular mechanisms are not fully understood. We aim to characterize HR and investigate diagnostic issues in the set of cfiA-positive B. fragilis strains using phenotypic and molecular methods. Of the phenotypic methods used, the population analysis profile (PAP) and area under curve (AUC) measurements were the best prognostic markers for HR. PAP AUC, imipenem agar dilution and imipenemase production corresponded well with each other. We also identified a saturation curve parameter (quasi-PAP curves), which correlated well with these phenotypic traits, implying that HR is a stochastic process. The genes, on a previously defined ‘cfiA element’, act in a complex manner to produce the HR phenotype, including a lysine-acetylating toxin and a lysine-rich peptide. Furthermore, imipenem HR is triggered by imipenem. The two parameters that most correlate with the others are imipenemase production and ‘GNAT’ expression, which prompted us to suspect that carbapenem heteroresistance of the B. fragilis strains is stochastically regulated and is mediated by the altered imipenemase production.
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Affiliation(s)
- Zain Baaity
- Institute of Medical Microbiology, Albert Szent-Györgyi Health Centre and School of Medicine, University of Szeged, H-6725 Szeged, Hungary; (Z.B.); (E.N.); (L.O.); (K.B.); (F.S.)
| | | | - Elisabeth Nagy
- Institute of Medical Microbiology, Albert Szent-Györgyi Health Centre and School of Medicine, University of Szeged, H-6725 Szeged, Hungary; (Z.B.); (E.N.); (L.O.); (K.B.); (F.S.)
| | - László Orosz
- Institute of Medical Microbiology, Albert Szent-Györgyi Health Centre and School of Medicine, University of Szeged, H-6725 Szeged, Hungary; (Z.B.); (E.N.); (L.O.); (K.B.); (F.S.)
| | - Katalin Burián
- Institute of Medical Microbiology, Albert Szent-Györgyi Health Centre and School of Medicine, University of Szeged, H-6725 Szeged, Hungary; (Z.B.); (E.N.); (L.O.); (K.B.); (F.S.)
| | - Ferenc Somogyvári
- Institute of Medical Microbiology, Albert Szent-Györgyi Health Centre and School of Medicine, University of Szeged, H-6725 Szeged, Hungary; (Z.B.); (E.N.); (L.O.); (K.B.); (F.S.)
| | - József Sóki
- Institute of Medical Microbiology, Albert Szent-Györgyi Health Centre and School of Medicine, University of Szeged, H-6725 Szeged, Hungary; (Z.B.); (E.N.); (L.O.); (K.B.); (F.S.)
- Correspondence: author:
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4
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Kononova S, Litvinova E, Vakhitov T, Skalinskaya M, Sitkin S. Acceptive Immunity: The Role of Fucosylated Glycans in Human Host-Microbiome Interactions. Int J Mol Sci 2021; 22:ijms22083854. [PMID: 33917768 PMCID: PMC8068183 DOI: 10.3390/ijms22083854] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/04/2021] [Accepted: 04/05/2021] [Indexed: 02/07/2023] Open
Abstract
The growth in the number of chronic non-communicable diseases in the second half of the past century and in the first two decades of the new century is largely due to the disruption of the relationship between the human body and its symbiotic microbiota, and not pathogens. The interaction of the human immune system with symbionts is not accompanied by inflammation, but is a physiological norm. This is achieved via microbiota control by the immune system through a complex balance of pro-inflammatory and suppressive responses, and only a disturbance of this balance can trigger pathophysiological mechanisms. This review discusses the establishment of homeostatic relationships during immune system development and intestinal bacterial colonization through the interaction of milk glycans, mucins, and secretory immunoglobulins. In particular, the role of fucose and fucosylated glycans in the mechanism of interactions between host epithelial and immune cells is discussed.
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Affiliation(s)
- Svetlana Kononova
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
- Correspondence:
| | - Ekaterina Litvinova
- Scientific-Research Institute of Neurosciences and Medicine, 630117 Novosibirsk, Russia;
- Siberian Federal Scientific Center of Agro-BioTechnologies, Russian Academy of Sciences, Krasnoobsk, 633501 Novosibirsk, Russia
| | - Timur Vakhitov
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
| | - Maria Skalinskaya
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
- Department of Internal Diseases, Gastroenterology and Dietetics, North-Western State Medical University Named after I.I. Mechnikov, 191015 St. Petersburg, Russia
| | - Stanislav Sitkin
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
- Department of Internal Diseases, Gastroenterology and Dietetics, North-Western State Medical University Named after I.I. Mechnikov, 191015 St. Petersburg, Russia
- Institute of Perinatology and Pediatrics, Almazov National Medical Research Centre, 197341 St. Petersburg, Russia
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Affiliation(s)
- Hannah C. Carrow
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
| | - Lakshmi E. Batachari
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
| | - Hiutung Chu
- Department of Pathology, University of California San Diego, La Jolla, California, United States of America
- Chiba University-UC San Diego Center for Mucosal Immunology, Allergy, and Vaccine, La Jolla, California, United States of America
- Humans and the Microbiome Program, CIFAR, Toronto, Ontario, Canada
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6
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Yekani M, Baghi HB, Naghili B, Vahed SZ, Sóki J, Memar MY. To resist and persist: Important factors in the pathogenesis of Bacteroides fragilis. Microb Pathog 2020; 149:104506. [PMID: 32950639 DOI: 10.1016/j.micpath.2020.104506] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 07/15/2020] [Accepted: 09/15/2020] [Indexed: 02/07/2023]
Abstract
Bacteroides fragilis is a most frequent anaerobic pathogen isolated from human infections, particularly found in the abdominal cavity. Different factors contribute to the pathogenesis and persistence of B. fragilis at infection sites. The knowledge of the virulence factors can provide applicable information for finding alternative options for the antibiotic therapy and treatment of B. fragilis caused infections. Herein, a comprehensive review of the important B. fragilis virulence factors was prepared. In addition to B. fragilis toxin (BFT) and its potential role in the diarrhea and cancer development, some other important virulence factors and characteristics of B. fragilis are described including capsular polysaccharides, iron acquisition, resistance to antimicrobial agents, and survival during the prolonged oxidative stress, quorum sensing, and secretion systems.
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Affiliation(s)
- Mina Yekani
- Department of Microbiology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran; Student Research Committee,Kashan University of Medical Sciences, Kashan, Iran
| | - Hossein Bannazadeh Baghi
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Behrooz Naghili
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | | | - József Sóki
- Institute of Clinical Microbiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.
| | - Mohammad Yousef Memar
- Infectious and Tropical Diseases Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Microbiology Department, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; Students' Research Committee, Tabriz University of Medical Sciences, Tabriz, Iran.
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7
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Hossain F, Nishat S, Ghosh S, Boga S, Hymel GT, Andreana PR. Synthesis of glycoimmunogen Tn-Thr-PS A1 via hydrazone bond and stability optimization of PS A1 monosaccharide mimics under vaccine development conditions. J Carbohydr Chem 2020; 39:107-129. [PMID: 33994657 PMCID: PMC8118568 DOI: 10.1080/07328303.2019.1709975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Accepted: 12/25/2019] [Indexed: 12/18/2022]
Abstract
Previously, our group constructed several immunogens utilizing oxime linkage to conjugate a T-cell stimulatory zwitterionic polysaccharide PS A1 and tumor associated carbohydrate antigens (TACAs) in acetate buffer. Here, a semi-synthetic immunogen was synthesized using hydrazone conjugation between PS A1 and a glycopeptide hydrazide (α-d-GalNAc-l-Thr-NH-NH2) with an excellent loading in PBS buffer. To get robust immune response, the retention of zwitterionic character of PS A1 under vaccine construction conditions is essential. In this regard, the stability of embedded pyruvate acetal moiety in tetrasaccharide repeating unit of PS A1 can validate the retention of the dual charges. Therefore, rather than utilizing this highly immunogenic PS A1 fully, stability studies were performed with synthetic 1-thiophenyl-4,6-O-pyruvate acetal-d-galactopyranose in varying acetate buffer pHs and time intervals. Furthermore, 1-propyl-d-galactofuranose was synthesized to mimick the d-Galf of PS A1 to examine regioselective hydrazone and oxime formation with α-d-GalNAc-l-Thr-NH-NH2 and α-d-GalNAc-ONH2 moieties respectively.
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Affiliation(s)
- F. Hossain
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
| | - S. Nishat
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
| | - S. Ghosh
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
| | - S. Boga
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
| | - G. T. Hymel
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
| | - P. R. Andreana
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA
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Erturk-Hasdemir D, Kasper DL. Finding a needle in a haystack: Bacteroides fragilis polysaccharide A as the archetypical symbiosis factor. Ann N Y Acad Sci 2018. [PMID: 29528123 DOI: 10.1111/nyas.13660] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Starting from birth, all animals develop a symbiotic relationship with their resident microorganisms that benefits both the microbe and the host. Recent advances in technology have substantially improved our ability to direct research toward the identification of important microbial species that affect host physiology. The identification of specific commensal molecules from these microbes and their mechanisms of action is still in its early stages. Polysaccharide A (PSA) of Bacteroides fragilis is the archetypical example of a commensal molecule that can modulate the host immune system in health and disease. This zwitterionic polysaccharide has a critical impact on the development of the mammalian immune system and also on the stimulation of interleukin 10-producing CD4+ T cells; consequently, PSA confers benefits to the host with regard to experimental autoimmune, inflammatory, and infectious diseases. In this review, we summarize the current understanding of the immunomodulatory effects of B. fragilis PSA and discuss these effects as a novel immunological paradigm. In particular, we discuss recent advances in our understanding of the unique functional mechanisms of this molecule and its therapeutic potential, and we review the recent literature in the field of microbiome research aimed at discovering new commensal products and their immunomodulatory potential.
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Affiliation(s)
- Deniz Erturk-Hasdemir
- Division of Immunology, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts
| | - Dennis L Kasper
- Division of Immunology, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, Massachusetts
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9
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Evidence for a LOS and a capsular polysaccharide in Capnocytophaga canimorsus. Sci Rep 2016; 6:38914. [PMID: 27974829 PMCID: PMC5156936 DOI: 10.1038/srep38914] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 11/14/2016] [Indexed: 12/22/2022] Open
Abstract
Capnocytophaga canimorsus is a dog’s and cat’s oral commensal which can cause fatal human infections upon bites or scratches. Infections mainly start with flu-like symptoms but can rapidly evolve in fatal septicaemia with a mortality as high as 40%. Here we present the discovery of a polysaccharide capsule (CPS) at the surface of C. canimorsus 5 (Cc5), a strain isolated from a fulminant septicaemia. We provide genetic and chemical data showing that this capsule is related to the lipooligosaccharide (LOS) and probably composed of the same polysaccharide units. A CPS was also found in nine out of nine other strains of C. canimorsus. In addition, the genomes of three of these strains, sequenced previously, contain genes similar to those encoding CPS biosynthesis in Cc5. Thus, the presence of a CPS is likely to be a common property of C. canimorsus. The CPS and not the LOS confers protection against the bactericidal effect of human serum and phagocytosis by macrophages. An antiserum raised against the capsule increased the killing of C. canimorsus by human serum thus showing that anti-capsule antibodies have a protective role. These findings provide a new major element in the understanding of the pathogenesis of C. canimorsus.
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Sun L, Middleton DR, Wantuch PL, Ozdilek A, Avci FY. Carbohydrates as T-cell antigens with implications in health and disease. Glycobiology 2016; 26:1029-1040. [PMID: 27236197 DOI: 10.1093/glycob/cww062] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 05/11/2016] [Accepted: 05/23/2016] [Indexed: 12/27/2022] Open
Abstract
Glycosylation is arguably the most ubiquitous post-translational modification on proteins in microbial and mammalian cells. During the past few years, there has been intensive research demonstrating that carbohydrates, either in pure forms or in conjunction with proteins or lipids, evoke and modulate adaptive immune responses. We now know that carbohydrates can be directly recognized by T cells or participate in T-cell stimulation as components of T-cell epitopes. T-cell recognition of carbohydrate antigens takes place via their presentation by major histocompatibility complex pathways on antigen-presenting cells. In this review, we summarize studies on carbohydrates as T-cell antigens modulating adaptive immune responses. Through discussion of glycan-containing antigens, such as glycoproteins, glycolipids, zwitterionic polysaccharides and carbohydrate-based glycoconjugate vaccines, we will illustrate the key molecular and cellular interactions between carbohydrate antigens and T cells and the implications of these interactions in health and disease.
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Affiliation(s)
- Lina Sun
- Department of Biochemistry and Molecular Biology, Center for Molecular Medicine, and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Dustin R Middleton
- Department of Biochemistry and Molecular Biology, Center for Molecular Medicine, and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Paeton L Wantuch
- Department of Biochemistry and Molecular Biology, Center for Molecular Medicine, and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Ahmet Ozdilek
- Department of Biochemistry and Molecular Biology, Center for Molecular Medicine, and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Fikri Y Avci
- Department of Biochemistry and Molecular Biology, Center for Molecular Medicine, and Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
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11
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Enterobacteria-secreted particles induce production of exosome-like S1P-containing particles by intestinal epithelium to drive Th17-mediated tumorigenesis. Nat Commun 2015; 6:6956. [PMID: 25907800 PMCID: PMC4410277 DOI: 10.1038/ncomms7956] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 03/18/2015] [Indexed: 02/07/2023] Open
Abstract
Gut-associated inflammation plays a crucial role in the progression of colon cancer. Here, we identify a novel pathogen-host interaction that promotes gut inflammation and the development of colon cancer. We find that enteropathogenic bacteria-secreted particles (ET-BSPs) stimulate intestinal epithelium to produce IDENs (intestinal mucosa-derived exosome-like nanoparticles) containing elevated levels of sphingosine-1-phosphate, CCL20 and prostaglandin E2 (PGE2). CCL20 and PGE2 are required for the recruitment and proliferation, respectively, of Th17 cells, and these processes also involve the MyD88-mediated pathway. By influencing the recruitment and proliferation of Th17 cells in the intestine, IDENs promote colon cancer. We demonstrate the biological effect of sphingosine-1-phosphate contained in IDENs on tumor growth in spontaneous and transplanted colon cancer mouse models. These findings provide deeper insights into how host-microbe relationships are mediated by particles secreted from both bacterial and host cells.
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12
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Bauer M, Kölsch U, Krüger R, Unterwalder N, Hameister K, Kaiser FM, Vignoli A, Rossi R, Botella MP, Budisteanu M, Rosello M, Orellana C, Tejada MI, Papuc SM, Patat O, Julia S, Touraine R, Gomes T, Wenner K, Xu X, Afenjar A, Toutain A, Philip N, Jezela-Stanek A, Gortner L, Martinez F, Echenne B, Wahn V, Meisel C, Wieczorek D, El-Chehadeh S, Van Esch H, von Bernuth H. Infectious and immunologic phenotype of MECP2 duplication syndrome. J Clin Immunol 2015; 35:168-81. [PMID: 25721700 PMCID: PMC7101860 DOI: 10.1007/s10875-015-0129-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2013] [Accepted: 01/12/2015] [Indexed: 12/02/2022]
Abstract
MECP2 (methyl CpG binding protein 2) duplication causes syndromic intellectual disability. Patients often suffer from life-threatening infections, suggesting an additional immunodeficiency. We describe for the first time the detailed infectious and immunological phenotype of MECP2 duplication syndrome. 17/27 analyzed patients suffered from pneumonia, 5/27 from at least one episode of sepsis. Encapsulated bacteria (S.pneumoniae, H.influenzae) were frequently isolated. T-cell immunity showed no gross abnormalities in 14/14 patients and IFNy-secretion upon ConA-stimulation was not decreased in 6/7 patients. In 6/21 patients IgG2-deficiency was detected – in 4/21 patients accompanied by IgA-deficiency, 10/21 patients showed low antibody titers against pneumococci. Supra-normal IgG1-levels were detected in 11/21 patients and supra-normal IgG3-levels were seen in 8/21 patients – in 6 of the patients as combined elevation of IgG1 and IgG3. Three of the four patients with IgA/IgG2-deficiency developed multiple severe infections. Upon infections pronounced acute-phase responses were common: 7/10 patients showed CRP values above 200 mg/l. Our data for the first time show systematically that increased susceptibility to infections in MECP2 duplication syndrome is associated with IgA/IgG2-deficiency, low antibody titers against pneumococci and elevated acute-phase responses. So patients with MECP2 duplication syndrome and low IgA/IgG2 may benefit from prophylactic substitution of sIgA and IgG.
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Affiliation(s)
- Michael Bauer
- Pediatric Pneumology and Immunology, Charité University Medicine, Berlin, Germany,
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13
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The modulation of adaptive immune responses by bacterial zwitterionic polysaccharides. Int J Microbiol 2010; 2010:917075. [PMID: 21234388 PMCID: PMC3017905 DOI: 10.1155/2010/917075] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 09/15/2010] [Accepted: 10/05/2010] [Indexed: 02/06/2023] Open
Abstract
The detection of pathogen-derived molecules as foreign particles by adaptive immune cells triggers T and B lymphocytes to mount protective cellular and humoral responses, respectively. Recent immunological advances elucidated that proteins and some lipids are the principle biological molecules that induce protective T cell responses during microbial infections. Polysaccharides are important components of microbial pathogens and many vaccines. However, research concerning the activation of the adaptive immune system by polysaccharides gained interest only recently. Traditionally, polysaccharides were considered to be T cell-independent antigens that did not directly activate T cells or induce protective immune responses. Here, we review several recent advances in “carbohydrate immunobiology”. A group of bacterial polysaccharides that are known as “zwitterionic polysaccharides (ZPSs)” were recently identified as potent immune modulators. The immunomodulatory effect of ZPSs required antigen processing and presentation by antigen presenting cells, the activation of CD4 T cells and subpopulations of CD8 T cells and the modulation of host cytokine responses. In this review, we also discuss the potential use of these unique immunomodulatory ZPSs in new vaccination strategies against chronic inflammatory conditions, autoimmunity, infectious diseases, allergies and asthmatic conditions.
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15
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Meemboor S, Mertens J, Flenner E, Groneck L, Zingarelli A, Gamstätter T, Bessler M, Seeger JM, Kashkar H, Odenthal M, Kalka-Moll WM. Interleukin-6 is essential for zwitterionic polysaccharide-mediated abscess formation. Innate Immun 2009; 16:310-21. [DOI: 10.1177/1753425909346974] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Abscess formation associated with secondary peritonitis causes severe morbidity and can be fatal. Formation of abscesses requires the presence of CD4+ T-cells. Zwitterionic polysaccharides (ZPSs) represent a novel class of immunomodulatory bacterial antigens that stimulate CD4+ T-cells in a major histocompatibility complex (MHC) class II-dependent manner. The capsular polysaccharide Sp1 of Streptococcus pneumoniae serotype 1 possesses a zwitterionic charge with free amino groups and promotes T-cell-dependent abscess formation in an experimental mouse model. So far, nothing is known about the function of Interleukin (IL)-6 in intraperitoneal abscess formation. Here, we demonstrate that macrophages and dendritic cells (DCs), the most prevalent professional antigen-presenting cells involved in the formation of abscesses, secrete Interleukin (IL)-6 and are incorporated in the abscess capsule. Sp1 inhibits apoptosis of CD4 + T-cells and causes IL-17 expression by CD4+ T-cells in an IL-6-dependent manner. Abrogation of the Sp1-induced pleiotropic effects of IL-6 in IL-6-deficient mice and mice treated with an IL-6-specific neutralizing antibody results in significant inhibition of abscess formation. The data delineate the essential role of IL-6 in the linkage of innate and adaptive immunity in polysaccharide-mediated abscess formation.
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Affiliation(s)
- Sonja Meemboor
- Institute for Medical Microbiology, Immunology and Hygiene
| | - Janina Mertens
- Institute for Medical Microbiology, Immunology and Hygiene
| | - Eva Flenner
- Institute for Medical Microbiology, Immunology and Hygiene
| | - Laura Groneck
- Institute for Medical Microbiology, Immunology and Hygiene
| | | | | | | | - Jens M. Seeger
- Institute for Medical Microbiology, Immunology and Hygiene
| | - Hamid Kashkar
- Institute for Medical Microbiology, Immunology and Hygiene
| | - Margarete Odenthal
- Department of Pathology University of Cologne Medical Centre, Cologne, Germany
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Streptococcus pneumoniae serotype 1 capsular polysaccharide induces CD8CD28 regulatory T lymphocytes by TCR crosslinking. PLoS Pathog 2009; 5:e1000596. [PMID: 19779562 PMCID: PMC2742891 DOI: 10.1371/journal.ppat.1000596] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Accepted: 08/28/2009] [Indexed: 01/07/2023] Open
Abstract
Zwitterionic capsular polysaccharides (ZPS) of commensal bacteria are characterized by having both positive and negative charged substituents on each repeating unit of a highly repetitive structure that has an α-helix configuration. In this paper we look at the immune response of CD8+ T cells to ZPSs. Intraperitoneal application of the ZPS Sp1 from Streptococcus pneumoniae serotype 1 induces CD8+CD28− T cells in the spleen and peritoneal cavity of WT mice. However, chemically modified Sp1 (mSp1) without the positive charge and resembling common negatively charged polysaccharides fails to induce CD8+CD28− T lymphocytes. The Sp1-induced CD8+CD28− T lymphocytes are CD122lowCTLA-4+CD39+. They synthesize IL-10 and TGF-β. The Sp1-induced CD8+CD28− T cells exhibit immunosuppressive properties on CD4+ T cells in vivo and in vitro. Experimental approaches to elucidate the mechanism of CD8+ T cell activation by Sp1 demonstrate in a dimeric MHC class I-Ig model that Sp1 induces CD8+ T cell activation by enhancing crosslinking of TCR. The expansion of CD8+CD28− T cells is independent, of direct antigen-presenting cell/T cell contact and, to the specificity of the T cell receptor (TCR). In CD8+CD28− T cells, Sp1 enhances Zap-70 phosphorylation and increasingly involves NF-κB which ultimately results in protection versus apoptosis and cell death and promotes survival and accumulation of the CD8+CD28− population. This is the first description of a naturally occurring bacterial antigen that is able to induce suppressive CD8+CD28− T lymphocytes in vivo and in vitro. The underlying mechanism of CD8+ T cell activation appears to rely on enhanced TCR crosslinking. The data provides evidence that ZPS of commensal bacteria play an important role in peripheral tolerance mechanisms and the maintenance of the homeostasis of the immune system. One of the most difficult challenges for the mammalian immune system is to protect its host from pathogens and cancer while at the same time avoiding a self-destructive or overwhelming immune response. In addition to so-called central tolerance induced in the thymus, the immune system relies on peripheral control mechanisms. One of the most important brakes of the peripheral tolerance system is constituted by so-called regulatory T lymphocytes. The predominately investigated regulatory T lymphocytes belong to the CD4+ subset but CD8+ regulatory T lymphocytes are now also believed to play a major role in controlling immune responses. Herein, we describe for the first time a natural occurring saccharide antigen from a commensal bacterium which induces the accumulation of a defined population of CD8+ regulatory T lymphocytes. These CD8+ regulatory lymphocytes suppress inflammatory immune responses in vivo and in in vitro assays. We also describe how the bacterial antigen induces the activation of CD8+ T cells. Our findings not only describe a novel mechanism of saccharide-mediated T cell activation but also provide evidence that commensal bacteria play an important role in the induction of peripheral tolerance and maintenance of the mammalian immune system.
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Oligoclonal CD4+ T cells promote host memory immune responses to Zwitterionic polysaccharide of Streptococcus pneumoniae. Infect Immun 2009; 77:3705-12. [PMID: 19546196 DOI: 10.1128/iai.01492-08] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Zwitterionic polysaccharides of the normal flora bacteria represent a novel class of antigens in that they correct systemic CD4(+) T-cell deficiencies and direct lymphoid organogenesis during colonization of the host. Presentation of these polysaccharides to CD4(+) T cells depends on major histocompatibility complex class II- and DM-dependent retrograde transport from lysosomes to the cell surface. Yet the phenotype and clonality of the immune response to the polysaccharide in the mature host immune system have not been studied. Using the zwitterionic capsular polysaccharide Sp1 of Streptococcus pneumoniae, a transient member of the bacterial flora, in an experimental mouse model of cellular immunity, we demonstrated the accumulation of TH1- and TH17-polarized CD4(+) CD44(high) CD62(low) CD25(-) memory T cells. Subcutaneous immunization with Sp1 resulted in an increase of serum immunoglobulin G (IgG), predominantly of the IgG1 subclass, and suggested the presence of a humoral memory response to the polysaccharide. CD4(+) T cells stimulated with polysaccharide in vitro and in vivo showed a nonrestricted pattern for the T-cell receptor (TCR) beta-chain variable region, as demonstrated by semiquantitative reverse transcription-PCR and flow cytometry. Clonotype mapping of in vivo and in vitro polysaccharide-activated CD4(+) T cells revealed clonotypic TCR transcripts. Taken together, the data show the induction of clonal expansion of CD4(+) T cells by polysaccharides of commensal bacteria. Cellular and humoral memory host responses imply the ability of these polysaccharides to mediate the expansion of T cells via recognition within the CDR3 region of the TCR.
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18
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Abstract
SUMMARY Bacteroides species are significant clinical pathogens and are found in most anaerobic infections, with an associated mortality of more than 19%. The bacteria maintain a complex and generally beneficial relationship with the host when retained in the gut, but when they escape this environment they can cause significant pathology, including bacteremia and abscess formation in multiple body sites. Genomic and proteomic analyses have vastly added to our understanding of the manner in which Bacteroides species adapt to, and thrive in, the human gut. A few examples are (i) complex systems to sense and adapt to nutrient availability, (ii) multiple pump systems to expel toxic substances, and (iii) the ability to influence the host immune system so that it controls other (competing) pathogens. B. fragilis, which accounts for only 0.5% of the human colonic flora, is the most commonly isolated anaerobic pathogen due, in part, to its potent virulence factors. Species of the genus Bacteroides have the most antibiotic resistance mechanisms and the highest resistance rates of all anaerobic pathogens. Clinically, Bacteroides species have exhibited increasing resistance to many antibiotics, including cefoxitin, clindamycin, metronidazole, carbapenems, and fluoroquinolones (e.g., gatifloxacin, levofloxacin, and moxifloxacin).
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Pumbwe L, Skilbeck CA, Wexler HM. The Bacteroides fragilis cell envelope: quarterback, linebacker, coach-or all three? Anaerobe 2006; 12:211-20. [PMID: 17045496 DOI: 10.1016/j.anaerobe.2006.09.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Accepted: 09/18/2006] [Indexed: 11/27/2022]
Abstract
Bacteroides fragilis is an anaerobic commensal constituting only 1-2% of the micro-flora of the human gastrointestinal tract, yet it is the predominant anaerobic isolate in cases of intraabdominal sepsis and bacteremia. B. fragilis can play two roles in the host: in its role as friendly commensal, it must be able to establish itself in the host intestinal mucosa, to utilize and process polysaccharides for use by the host, and to resist the noxious effects of bile salts. In its role as pathogen, it must be able to attach itself to the site of infection, evade killing mechanisms by host defense, withstand antimicrobial treatment and produce factors that damage host tissue. The cell envelope of B. fragilis, likewise, must be able to function in the roles of aggressor, defender and strategist in allowing the organism to establish itself in the host--whether as friend or foe. Recent studies of the genomes and proteomes of the genus Bacteroides suggest that these organisms have evolved strategies to survive and dominate in the overcrowded gastrointestinal neighborhood. Analysis of the proteomes of B. fragilis and Bacteroides thetaiotaomicron demonstrates both a tremendous capacity to use a wide range of dietary polysaccharides, and the capacity to create variable surface antigenicities by multiple DNA inversion systems. The latter characteristic is particularly pronounced in the species B. fragilis, which is more frequently found at the mucosal surface (i.e., often the site of attack by host defenses). The B. fragilis cell envelope undergoes major protein expression and ultrastructural changes in response to stressors such as bile or antimicrobial agents. These agents may also act as signals for attachment and colonization. Thus the bacterium manages its surface characteristics to enable it to bind to its target, to use the available nutrients, and to avoid or evade hostile forces (host-derived or external) in its multiple roles.
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Affiliation(s)
- Lilian Pumbwe
- Greater Los Angeles Veterans Administration Healthcare Systems and Department of Medicine, University of California, Los Angeles, CA 90073, USA
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20
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Stephen TL, Niemeyer M, Tzianabos AO, Kroenke M, Kasper DL, Kalka-Moll WM. Effect of B7-2 and CD40 signals from activated antigen-presenting cells on the ability of zwitterionic polysaccharides to induce T-Cell stimulation. Infect Immun 2005; 73:2184-9. [PMID: 15784561 PMCID: PMC1087428 DOI: 10.1128/iai.73.4.2184-2189.2005] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Carbohydrates have been thought to stimulate immune responses independently of T cells; however, zwitterionic polysaccharides (ZPSs) from the capsules of some bacteria elicit potent CD4+-T-cell responses in vivo and in vitro. We demonstrated that HLA-DR on professional antigen-presenting cells (APCs) is required for ZPS-induced T-cell proliferation in vitro (15). Recently, it was shown that ZPSs are processed to low-molecular-weight carbohydrates by a nitric oxide-mediated mechanism in endosomes and locate in the major histocompatibility complex class II pathway (5, 15). The effect of the ZPS-mediated expression of HLA-DR and costimulatory molecules on the APC and T-cell engagement and subsequent T-cell activation has not been elucidated. Herein, we report that ZPS-mediated induction of HLA-DR-surface expression and T-cell proliferation are maximally enhanced after incubation of APCs for 8 h with ZPS. Treatment of APCs with bafilomycin A inhibits the up-regulation of ZPS-mediated HLA-DR surface expression and leads to inhibition of T-cell proliferation. Monoclonal antibodies (MAbs) to the costimulatory molecules B7-2 and CD40L specifically block ZPS-mediated T-cell activation, while a MAb to B7-1 does not. Surface expression of B7-2 and B7-1 but not of CD40 is maximally enhanced at 8 to 16 h of treatment of APCs with ZPS. The results demonstrate that the cellular immune response to ZPS depends on the translocation of HLA-DR to the cell surface and requires costimulation via B7-2 and CD40 on activated APCs. The implication is that activation of ZPS-specific T cells requires an orchestrated arrangement of both presenting and costimulatory molecules to form an immunological synapse.
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Affiliation(s)
- Tom Li Stephen
- Institute for Medical Microbiology, Immunology and Hygiene, University of Cologne, Medical Center, Goldenfelsstr. 19-21, 50935 Cologne, Germany
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21
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Brigham CJ, Malamy MH. Characterization of the RokA and HexA broad-substrate-specificity hexokinases from Bacteroides fragilis and their role in hexose and N-acetylglucosamine utilization. J Bacteriol 2005; 187:890-901. [PMID: 15659667 PMCID: PMC545704 DOI: 10.1128/jb.187.3.890-901.2005] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacteroides fragilis, a human gastrointestinal commensal and an opportunistic pathogen, utilizes simple and complex sugars and polysaccharides for growth in the large intestine and at sites of infection. Because B. fragilis lacks transport-linked sugar phosphorylation systems, cytoplasmic kinase(s) was expected to be required for the phosphorylation of hexoses and hexosamines. We have now identified two hexose kinases that are important for growth of B. fragilis on glucose, mannose, and other sugars. One kinase (RokA), a member of the ROK family of proteins, was found to be the sole kinase for activation of N-acetyl-D-glucosamine (NAG). The other kinase (HexA) is responsible for the majority of the glucose kinase activity in the cell, although a hexA deletion mutant strain was not defective for growth on any substrate tested. Deletion of both the rokA and hexA kinase genes resulted in inability of the cell to use glucose, mannose, NAG, and many other sugars. We purified RokA and determined its approximate molecular mass to be 36.5 kDa. The purified RokA protein was shown to phosphorylate several substrates, including glucose, NAG, and mannose, but not N-acetylmannosamine or N-acetylneuraminic acid. Phylogenetic analysis of RokA showed that it is most similar to kinases from the Cytophaga-Flavibacterium-Bacteroides group, while HexA was most similar to other bacterial hexokinases and eukaryotic hexokinases.
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Affiliation(s)
- Christopher J Brigham
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, MA 02111.
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Zhang G, Dai J, Lu Z, Dunaway-Mariano D. The phosphonopyruvate decarboxylase from Bacteroides fragilis. J Biol Chem 2003; 278:41302-8. [PMID: 12904299 DOI: 10.1074/jbc.m305976200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Bacteroides fragilis capsular polysaccharide complex is the major virulence factor for abscess formation in human hosts. Polysaccharide B of this complex contains a 2-aminoethylphosphonate functional group. This functional group is synthesized in three steps, one of which is catalyzed by phosphonopyruvate decarboxylase. In this paper, we report the cloning and overexpression of the B. fragilis phosphonopyruvate decarboxylase gene (aepY), purification of the phosphonopyruvate decarboxylase recombinant protein, and the extensive characterization of the reaction that it catalyzes. The homotrimeric (41,184-Da subunit) phosphonopyruvate decarboxylase catalyzes (kcat = 10.2 +/- 0.3 s-1) the decarboxylation of phosphonopyruvate (Km = 3.2 +/- 0.2 microm) to phosphonoacetaldehyde (Ki = 15 +/- 2 microm) and carbon dioxide at an optimal pH range of 7.0-7.5. Thiamine pyrophosphate (Km = 13 +/- 2 microm) and certain divalent metal ions (Mg(II) Km = 82 +/- 8 microm; Mn(II) Km = 13 +/- 1 microm; Ca(II) Km = 78 +/- 6 microm) serve as cofactors. Phosphonopyruvate decarboxylase is a member of the alpha-ketodecarboxylase family that includes sulfopyruvate decarboxylase, acetohydroxy acid synthase/acetolactate synthase, benzoylformate decarboxylase, glyoxylate carboligase, indole pyruvate decarboxylase, pyruvate decarboxylase, the acetyl phosphate-producing pyruvate oxidase, and the acetate-producing pyruvate oxidase. The Mg(II) binding residue Asp-260, which is located within the thiamine pyrophosphate binding motif of the alpha-ketodecarboxylase family, was shown by site-directed mutagenesis to play an important role in catalysis. Pyruvate (kcat = 0.05 s-1, Km = 25 mm) and sulfopyruvate (kcat approximately 0.05 s-1; Ki = 200 +/- 20 microm) are slow substrates for the phosphonopyruvate decarboxylase, indicating that this enzyme is promiscuous.
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Affiliation(s)
- Guofeng Zhang
- Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
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Kalka-Moll WM, Tzianabos AO, Bryant PW, Niemeyer M, Ploegh HL, Kasper DL. Zwitterionic polysaccharides stimulate T cells by MHC class II-dependent interactions. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6149-53. [PMID: 12444118 DOI: 10.4049/jimmunol.169.11.6149] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Polysaccharides of pathogenic extracellular bacteria commonly have negatively charged groups or no charged groups at all. These molecules have been considered classic T cell-independent Ags that do not elicit cell-mediated immune responses in mice. However, bacterial polysaccharides with a zwitterionic charge motif (ZPSs), such as the capsular polysaccharides of many strains of Bacteroides fragilis, Staphylococcus aureus, and Streptococcus pneumoniae type 1 elicit potent CD4(+) T cell responses in vivo and in vitro. The cell-mediated response to ZPS depends on the presence of both positively charged and negatively charged groups on each repeating unit of the polysaccharide. In this study, we define some of the requirements for the presentation of ZPS to CD4(+) T cells. We provide evidence that direct interactions of T cells with APCs are essential for T cell activation by ZPS. Monocytes, dendritic cells, and B cells are all able to serve as APCs for ZPS-mediated T cell activation. APCs lacking MHC class II molecules do not support this activity. Furthermore, mAb to HLA-DR specifically blocks ZPS-mediated T cell activation, while mAbs to other MHC class II and class I molecules do not. Immunoprecipitation of lysates of MHC class II-expressing cells following incubation with ZPS shows binding of ZPS and HLA-DR. Electron microscopy reveals colocalization of ZPS with HLA-DR on the cell surface and in compartments of the endocytic pathway. These results indicate that MHC class II molecules expressing HLA-DR on professional APCs are required for ZPS-induced T cell activation. The implication is that binding of ZPS to HLA-DR may be required for T cell activation.
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Affiliation(s)
- Wiltrud M Kalka-Moll
- Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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Evaluation of Genetic Relatedness of Bacteroides fragilis Strains Isolated from Different Sources by AP-PCR and Pulsed-Field Gel Electrophoresis Assays. Anaerobe 2002. [DOI: 10.1006/anae.2002.0430] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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