1
|
Lund SJ, Del Rosario PGB, Honda A, Caoili KJ, Hoeksema MA, Nizet V, Patras KA, Prince LS. Sialic Acid-Siglec-E Interactions Regulate the Response of Neonatal Macrophages to Group B Streptococcus. Immunohorizons 2024; 8:384-396. [PMID: 38809232 PMCID: PMC11150127 DOI: 10.4049/immunohorizons.2300076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 04/24/2024] [Indexed: 05/30/2024] Open
Abstract
The mammalian Siglec receptor sialoadhesin (Siglec1, CD169) confers innate immunity against the encapsulated pathogen group B Streptococcus (GBS). Newborn lung macrophages have lower expression levels of sialoadhesin at birth compared with the postnatal period, increasing their susceptibility to GBS infection. In this study, we investigate the mechanisms regulating sialoadhesin expression in the newborn mouse lung. In both neonatal and adult mice, GBS lung infection reduced Siglec1 expression, potentially delaying acquisition of immunity in neonates. Suppression of Siglec1 expression required interactions between sialic acid on the GBS capsule and the inhibitory host receptor Siglec-E. The Siglec1 gene contains multiple STAT binding motifs, which could regulate expression of sialoadhesin downstream of innate immune signals. Although GBS infection reduced STAT1 expression in the lungs of wild-type newborn mice, we observed increased numbers of STAT1+ cells in Siglece-/- lungs. To test if innate immune activation could increase sialoadhesin at birth, we first demonstrated that treatment of neonatal lung macrophages ex vivo with inflammatory activators increased sialoadhesin expression. However, overcoming the low sialoadhesin expression at birth using in vivo prenatal exposures or treatments with inflammatory stimuli were not successful. The suppression of sialoadhesin expression by GBS-Siglec-E engagement may therefore contribute to disease pathogenesis in newborns and represent a challenging but potentially appealing therapeutic opportunity to augment immunity at birth.
Collapse
MESH Headings
- Animals
- Mice
- Streptococcus agalactiae/immunology
- Animals, Newborn
- N-Acetylneuraminic Acid/metabolism
- Sialic Acid Binding Ig-like Lectin 1/metabolism
- Streptococcal Infections/immunology
- Streptococcal Infections/microbiology
- STAT1 Transcription Factor/metabolism
- STAT1 Transcription Factor/genetics
- Mice, Knockout
- Immunity, Innate
- Mice, Inbred C57BL
- Lung/immunology
- Lung/microbiology
- Lung/metabolism
- Macrophages, Alveolar/immunology
- Macrophages, Alveolar/metabolism
- Female
- Macrophages/immunology
- Macrophages/metabolism
- Lectins/metabolism
- Lectins/genetics
- Sialic Acid Binding Immunoglobulin-like Lectins/metabolism
- Sialic Acid Binding Immunoglobulin-like Lectins/genetics
- Antigens, CD/metabolism
- Antigens, CD/genetics
- Antigens, Differentiation, B-Lymphocyte
Collapse
Affiliation(s)
- Sean J. Lund
- Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | - Pamela G. B. Del Rosario
- Department of Pediatrics, University of California, San Diego, La Jolla, CA
- Rady Children’s Hospital, San Diego, CA
| | - Asami Honda
- Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | | | - Marten A. Hoeksema
- Department of Medical Biochemistry, Amsterdam University Medical Center, Amsterdam Zuidoost, the Netherlands
| | - Victor Nizet
- Department of Pediatrics, University of California, San Diego, La Jolla, CA
| | - Kathryn A. Patras
- Department of Molecular Virology and Microbiology, Alkek Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX
| | | |
Collapse
|
2
|
Jennings MP, Day CJ, Atack JM. How bacteria utilize sialic acid during interactions with the host: snip, snatch, dispatch, match and attach. MICROBIOLOGY (READING, ENGLAND) 2022; 168:001157. [PMID: 35316172 PMCID: PMC9558349 DOI: 10.1099/mic.0.001157] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/08/2022] [Indexed: 12/16/2022]
Abstract
N -glycolylneuraminic acid (Neu5Gc), and its precursor N-acetylneuraminic acid (Neu5Ac), commonly referred to as sialic acids, are two of the most common glycans found in mammals. Humans carry a mutation in the enzyme that converts Neu5Ac into Neu5Gc, and as such, expression of Neu5Ac can be thought of as a 'human specific' trait. Bacteria can utilize sialic acids as a carbon and energy source and have evolved multiple ways to take up sialic acids. In order to generate free sialic acid, many bacteria produce sialidases that cleave sialic acid residues from complex glycan structures. In addition, sialidases allow escape from innate immune mechanisms, and can synergize with other virulence factors such as toxins. Human-adapted pathogens have evolved a preference for Neu5Ac, with many bacterial adhesins, and major classes of toxin, specifically recognizing Neu5Ac containing glycans as receptors. The preference of human-adapted pathogens for Neu5Ac also occurs during biosynthesis of surface structures such as lipo-oligosaccharide (LOS), lipo-polysaccharide (LPS) and polysaccharide capsules, subverting the human host immune system by mimicking the host. This review aims to provide an update on the advances made in understanding the role of sialic acid in bacteria-host interactions made in the last 5-10 years, and put these findings into context by highlighting key historical discoveries. We provide a particular focus on 'molecular mimicry' and incorporation of sialic acid onto the bacterial outer-surface, and the role of sialic acid as a receptor for bacterial adhesins and toxins.
Collapse
Affiliation(s)
- Michael P. Jennings
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - Christopher J. Day
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
| | - John M. Atack
- Institute for Glycomics, Griffith University, Gold Coast, Queensland, Australia
- School of Environment and Science, Griffith University, Gold Coast, Queensland, Australia
| |
Collapse
|
3
|
Reduced Virulence and Enhanced Host Adaption during Antibiotics Therapy: a Story of a Within-Host Carbapenem-Resistant Klebsiella pneumoniae Sequence Type 11 Evolution in a Patient with a Serious Scrotal Abscess. mSystems 2022; 7:e0134221. [PMID: 35196132 PMCID: PMC9040587 DOI: 10.1128/msystems.01342-21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Carbapenem-resistant Klebsiella pneumoniae (CRKP) has disseminated globally and threatened human life. The sequence type (ST) 11 CRKP is a dominant clone in Asia, but how this clone evolves in vivo then adapts to the host and facilitates dissemination remains largely unknown. Here, the genomic dynamics of 4 ST11-CRKP isolates, which were sequentially collected from the urine of a patient with initial serious scrotal abscess and finally recovered without effective medication, were analyzed. Genomic differences were identified and their implications for pathogenesis and host adaptation were investigated. The related transcriptional pathways were further explored by RNA-Seq. Genomic analysis identified 4 to 24 mutations, among which 94% to 100% of them were synonymous or intergenic mutations. During 47 days of antibiotics therapy, CRKP underwent adaptive evolution, including tigecycline resistance and virulence attenuation. Tigecycline resistance was caused by a deletion within the ramR ribosomal binding site, which has been described by us previously. On the other hand, mutations associated with two genes, acyltransferase (act) and ompK26, resulted in the attenuation phenotype of ST11-CRKP. act deficiency reduced the capsular polysaccharide (CPS) production, enhanced biofilm formation, weakened capsular protection, and decreased induction of proinflammatory cytokines. Further RNA-Seq analysis revealed that act influenced the expression of ldhA, bglX, mtnK, and metE which likely participate in capsular synthesis and biofilm formation. ompK26 affected the virulence by its overexpression caused by the deletion of the upstream repressor binding site. This study presents a within-host adaption of ST11-CRKP and suggests an important role of CPS in the adaptive evolution of virulence and persistence of CRKP. IMPORTANCE Carbapenem-resistant Klebsiella pneumoniae (CRKP) has disseminated worldwide and can cause life-threatening infections, including pneumonia, bloodstream infections, urinary tract infections, intraabdominal infection, liver abscess, and meningitis. CRKP infection is the leading cause of high mortality in hospitals. The sequence type (ST) 11 CRKP is a dominant clone and accounts for 60% of CRKP infections in China. Recently, the ST11-CRKP with high transmissibility is increasingly identified. Understanding how this clone has evolved is crucial for developing strategies to control its further dissemination. The significance of our research is the identification of the in vivo genomic dynamics of ST11-CRKP and the genetic basis for ST11-CRKP that facilitate persistence and dissemination. Furthermore, our study also highlights the importance of monitoring the within-host evolution of pathogens during the treatment and developing interventions to minimize the potential impact of host adaptation on human health.
Collapse
|
4
|
Ji Y, Sasmal A, Li W, Oh L, Srivastava S, Hargett AA, Wasik BR, Yu H, Diaz S, Choudhury B, Parrish CR, Freedberg DI, Wang LP, Varki A, Chen X. Reversible O-Acetyl Migration within the Sialic Acid Side Chain and Its Influence on Protein Recognition. ACS Chem Biol 2021; 16:1951-1960. [PMID: 33769035 DOI: 10.1021/acschembio.0c00998] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
O-Acetylation is a common naturally occurring modification of carbohydrates and is especially widespread in sialic acids, a family of nine-carbon acidic monosaccharides. O-Acetyl migration within the exocyclic glycerol-like side chain of mono-O-acetylated sialic acid reported previously was from the C7- to C9-hydroxyl group with or without an 8-O-acetyl intermediate, which resulted in an equilibrium that favors the formation of the 9-O-acetyl sialic acid. Herein, we provide direct experimental evidence demonstrating that O-acetyl migration is bidirectional, and the rate of equilibration is influenced predominantly by the pH of the sample. While the O-acetyl group on sialic acids and sialoglycans is stable under mildly acidic conditions (pH < 5, the rate of O-acetyl migration is extremely low), reversible O-acetyl migration is observed readily at neutral pH and becomes more significant when the pH increases to slightly basic. Sialoglycan microarray studies showed that esterase-inactivated porcine torovirus hemagglutinin-esterase bound strongly to sialoglycans containing a more stable 9-N-acetylated sialic acid analog, but these compounds were less resistant to periodate oxidation treatment compared to their 9-O-acetyl counterparts. Together with prior studies, the results support the possible influence of sialic acid O-acetylation and O-acetyl migration to host-microbe interactions and potential application of the more stable synthetic N-acetyl mimics.
Collapse
Affiliation(s)
- Yang Ji
- Glycobiology Research and Training Center, Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093, United States
| | - Aniruddha Sasmal
- Glycobiology Research and Training Center, Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093, United States
| | - Wanqing Li
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Lisa Oh
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Saurabh Srivastava
- Glycobiology Research and Training Center, Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093, United States
| | - Audra A. Hargett
- Laboratory of Bacterial Polysaccharides, Food and Drug Administration (FDA), Silver Spring, Maryland 20993, United States
| | - Brian R. Wasik
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, United States
| | - Hai Yu
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Sandra Diaz
- Glycobiology Research and Training Center, Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093, United States
| | - Biswa Choudhury
- Glycobiology Research and Training Center, Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093, United States
| | - Colin R. Parrish
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, United States
| | - Darón I. Freedberg
- Laboratory of Bacterial Polysaccharides, Food and Drug Administration (FDA), Silver Spring, Maryland 20993, United States
| | - Lee-Ping Wang
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Ajit Varki
- Glycobiology Research and Training Center, Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, California 92093, United States
| | - Xi Chen
- Department of Chemistry, University of California, Davis, California 95616, United States
| |
Collapse
|
5
|
Abstract
Siglecs are sialic acid (Sia) recognizing immunoglobulin-like receptors expressed on the surface of all the major leukocyte lineages in mammals. Siglecs recognize ubiquitous Sia epitopes on various glycoconjugates in the cell glycocalyx and transduce signals to regulate immunological and inflammatory activities of these cells. The subset known as CD33-related Siglecs is principally inhibitory receptors that suppress leukocyte activation, and recent research has shown that a number of bacterial pathogens use Sia mimicry to engage these Siglecs as an immune evasion strategy. Conversely, Siglec-1 is a macrophage phagocytic receptor that engages GBS and other sialylated bacteria to promote effective phagocytosis and antigen presentation for the adaptive immune response, whereas certain viruses and parasites use Siglec-1 to gain entry to immune cells as a proximal step in the infectious process. Siglecs are positioned in crosstalk with other host innate immune sensing pathways to modulate the immune response to infection in complex ways. This chapter summarizes the current understanding of Siglecs at the host-pathogen interface, a field of study expanding in breadth and medical importance, and which provides potential targets for immune-based anti-infective strategies.
Collapse
Affiliation(s)
- Yung-Chi Chang
- Graduate Institute of Microbiology, College of Medicine, National Taiwan University, No. 1, Sec. 1, Jen-Ai Rd., Taipei, 10051, Taiwan.
| | - Victor Nizet
- Division of Host-Microbe Systems and Therapeutics, Department of Pediatrics, and Skaggs School of Pharmacy and Pharmaceutical Sciences, UC San Diego, 9500 Gilman Drive Mail Code 0760, La Jolla, CA, 92093, USA
| |
Collapse
|
6
|
Auger JP, Payen S, Roy D, Dumesnil A, Segura M, Gottschalk M. Interactions of Streptococcus suis serotype 9 with host cells and role of the capsular polysaccharide: Comparison with serotypes 2 and 14. PLoS One 2019; 14:e0223864. [PMID: 31600314 PMCID: PMC6786723 DOI: 10.1371/journal.pone.0223864] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 09/30/2019] [Indexed: 12/21/2022] Open
Abstract
Streptococcus suis is an important porcine bacterial pathogen and a zoonotic agent responsible for sudden death, septic shock and meningitis, of which serotype 2 is the most widespread, with serotype 14 also causing infections in humans in South-East Asia. Knowledge of its pathogenesis and virulence are almost exclusively based on these two serotypes. Though serotype 9 is responsible for the greatest number of porcine cases in Spain, the Netherlands and Germany, very little information is currently available regarding this serotype. Of the different virulence factors, the capsular polysaccharide (CPS) is required for S. suis virulence as it promotes resistance to phagocytosis and killing and masks surface components responsible for host cell activation. However, these roles have been described for serotypes 2 and 14, whose CPSs are structurally and compositionally similar, both containing sialic acid. Consequently, we evaluated herein the interactions of serotype 9 with host cells and the role of its CPS, which greatly differs from those of serotypes 2 and 14. Results demonstrated that serotype 9 adhesion to but not invasion of respiratory epithelial cells was greater than that of serotypes 2 and 14. Furthermore serotype 9 was more internalized by macrophages but equally resistant to whole blood killing. Though recognition of serotypes 2, 9 and 14 by DCs required MyD88-dependent signaling, in vitro pro-inflammatory mediator production induced by serotype 9 was much lower. In vivo, however, serotype 9 causes an exacerbated inflammatory response, which combined with persistent bacterial presence, is probably responsible for host death during the systemic infection. Though presence of the serotype 9 CPS masks surface components less efficiently than those of serotypes 2 and 14, the serotype 9 CPS remains critical for virulence as it is required for survival in blood and development of clinical disease, and this regardless of its unique composition and structure.
Collapse
Affiliation(s)
- Jean-Philippe Auger
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Servane Payen
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - David Roy
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Audrey Dumesnil
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Mariela Segura
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Marcelo Gottschalk
- Research Group on Infectious Diseases in Production Animals (GREMIP) and Swine and Poultry Infectious Diseases Research Center (CRIPA), Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| |
Collapse
|
7
|
Robinson LS, Schwebke J, Lewis WG, Lewis AL. Identification and characterization of NanH2 and NanH3, enzymes responsible for sialidase activity in the vaginal bacterium Gardnerella vaginalis. J Biol Chem 2019; 294:5230-5245. [PMID: 30723162 DOI: 10.1074/jbc.ra118.006221] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 01/29/2019] [Indexed: 11/06/2022] Open
Abstract
Gardnerella vaginalis is abundant in bacterial vaginosis (BV), a condition associated with adverse reproductive health. Sialidase activity is a diagnostic feature of BV and is produced by a subset of G. vaginalis strains. Although its genetic basis has not been formally identified, sialidase activity is presumed to derive from the sialidase A gene, named here nanH1 In this study, BLAST searches predicted two additional G. vaginalis sialidases, NanH2 and NanH3. When expressed in Escherichia coli, NanH2 and NanH3 both displayed broad abilities to cleave sialic acids from α2-3- and α2-6-linked N- and O-linked sialoglycans, including relevant mucosal substrates. In contrast, recombinant NanH1 had limited activity against synthetic and mucosal substrates under the conditions tested. Recombinant NanH2 was much more effective than NanH3 in cleaving sialic acids bearing a 9-O-acetyl ester. Similarly, G. vaginalis strains encoding NanH2 cleaved and foraged significantly more Neu5,9Ac2 than strains encoding only NanH3. Among a collection of 34 G. vaginalis isolates, nanH2, nanH3, or both were present in all 15 sialidase-positive strains but absent from all 19 sialidase-negative isolates, including 16 strains that were nanH1-positive. We conclude that NanH2 and NanH3 are the primary sources of sialidase activity in G. vaginalis and that these two enzymes can account for the previously described substrate breadth cleaved by sialidases in human vaginal specimens of women with BV. Finally, PCRs of nanH2 or nanH3 from human vaginal specimens had 81% sensitivity and 78% specificity in distinguishing between Lactobacillus dominance and BV, as determined by Nugent scoring.
Collapse
Affiliation(s)
- Lloyd S Robinson
- From the Departments of Molecular Microbiology and.,Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Jane Schwebke
- the Division of Infectious Diseases, University of Alabama, Birmingham, Alabama 35294
| | - Warren G Lewis
- From the Departments of Molecular Microbiology and.,Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110 and
| | - Amanda L Lewis
- From the Departments of Molecular Microbiology and .,Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110 and.,Obstetrics and Gynecology and
| |
Collapse
|
8
|
Linz B, Mukhtar N, Shabbir MZ, Rivera I, Ivanov YV, Tahir Z, Yaqub T, Harvill ET. Virulent Epidemic Pneumonia in Sheep Caused by the Human Pathogen Acinetobacter baumannii. Front Microbiol 2018; 9:2616. [PMID: 30459734 PMCID: PMC6232368 DOI: 10.3389/fmicb.2018.02616] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/12/2018] [Indexed: 01/12/2023] Open
Abstract
The human pathogen Acinetobacter baumannii has emerged as a frequent cause of hospital-acquired infections, but infection of animals has rarely been observed. Here we analyzed an outbreak of epidemic pneumonia killing hundreds of sheep on a farm in Pakistan and identified A. baumannii as the infecting agent. A pure culture of strain AbPK1 isolated from lungs of sick animals was inoculated into healthy sheep, which subsequently developed similar disease symptoms. Bacteria re-isolated from the infected animals were shown to be identical to the inoculum, fulfilling Koch’s postulates. Comparison of the AbPK1 genome against 2283 A. baumannii genomes from the NCBI database revealed that AbPK1 carries genes for unusual surface structures, including a unique composition of iron acquisition genes, genes for O-antigen synthesis and sialic acid-specific acetylases of cell-surface carbohydrates that could enable immune evasion. Several of these unusual and otherwise rarely present genes were also identified in genomes of phylogenetically unrelated A. baumannii isolates from combat-wounded US military from Afghanistan indicating a common gene pool in this geographical region. Based on core genome MLST this virulent isolate represents a newly emerging lineage of Global Clone 2, suggesting a human source for this disease outbreak. The observed epidemic, direct transmission from sheep to sheep, which is highly unusual for A. baumannii, has important consequences for human and animal health. First, direct animal-to-animal transmission facilitates fast spread of pathogen and disease in the flock. Second, it may establish a stable ecological niche and subsequent spread in a new host. And third, it constitutes a serious risk of transmission of this hyper-virulent clone from sheep back to humans, which may result in emergence of contagious disease amongst humans.
Collapse
Affiliation(s)
- Bodo Linz
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, United States.,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Nadia Mukhtar
- Quality Operations Laboratory, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Muhammad Zubair Shabbir
- Quality Operations Laboratory, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Israel Rivera
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, United States.,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| | - Yury V Ivanov
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, United States
| | - Zarfishan Tahir
- Quality Operations Laboratory, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Tahir Yaqub
- Quality Operations Laboratory, University of Veterinary and Animal Sciences, Lahore, Pakistan
| | - Eric T Harvill
- Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA, United States.,Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, United States
| |
Collapse
|
9
|
Robinson LS, Lewis WG, Lewis AL. The sialate O-acetylesterase EstA from gut Bacteroidetes species enables sialidase-mediated cross-species foraging of 9- O-acetylated sialoglycans. J Biol Chem 2017; 292:11861-11872. [PMID: 28526748 PMCID: PMC5512079 DOI: 10.1074/jbc.m116.769232] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 05/18/2017] [Indexed: 12/16/2022] Open
Abstract
The gut harbors many symbiotic, commensal, and pathogenic microbes that break down and metabolize host carbohydrates. Sialic acids are prominent outermost carbohydrates on host glycoproteins called mucins and protect underlying glycan chains from enzymatic degradation. Sialidases produced by some members of the colonic microbiota can promote the expansion of several potential pathogens (e.g. Clostridium difficile, Salmonella, and Escherichia coli) that do not produce sialidases. O-Acetyl ester modifications of sialic acids help resist the action of many sialidases and are present at high levels in the mammalian colon. However, some gut bacteria, in turn, produce sialylate-O-acetylesterases to remove them. Here, we investigated O-acetyl ester removal and sialic acid degradation by Bacteroidetes sialate-O-acetylesterases and sialidases, respectively, and subsequent utilization of host sialic acids by both commensal and pathogenic E. coli strains. In vitro foraging studies demonstrated that sialidase-dependent E. coli growth on mucin is enabled by Bacteroides EstA, a sialate O-acetylesterase acting on glycosidically linked sialylate-O-acetylesterase substrates, particularly at neutral pH. Biochemical studies suggested that spontaneous migration of O-acetyl esters on the sialic acid side chain, which can occur at colonic pH, may serve as a switch controlling EstA-assisted sialic acid liberation. Specifically, EstA did not act on O-acetyl esters in their initial 7-position. However, following migration to the 9-position, glycans with O-acetyl esters became susceptible to the sequential actions of bacterial esterases and sialidases. We conclude that EstA specifically unlocks the nutritive potential of 9-O-acetylated mucus sialic acids for foraging by bacteria that otherwise are prevented from accessing this carbon source.
Collapse
Affiliation(s)
- Lloyd S Robinson
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Warren G Lewis
- Department of Medicine, Center for Women's Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri 63110.
| | - Amanda L Lewis
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110.
| |
Collapse
|
10
|
Barato P, Martins E, Vasquez G, Ramirez M, Melo-Cristino J, Martínez N, Iregui C. Capsule impairs efficient adherence of Streptococcus agalactiae to intestinal epithelium in tilapias Oreochromis sp. Microb Pathog 2016; 100:30-36. [DOI: 10.1016/j.micpath.2016.08.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/30/2016] [Accepted: 08/31/2016] [Indexed: 10/21/2022]
|
11
|
Lewis AL, Robinson LS, Agarwal K, Lewis WG. Discovery and characterization of de novo sialic acid biosynthesis in the phylum Fusobacterium. Glycobiology 2016; 26:1107-1119. [PMID: 27613803 DOI: 10.1093/glycob/cww068] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 06/15/2016] [Accepted: 06/16/2016] [Indexed: 12/15/2022] Open
Abstract
Sialic acids are nine-carbon backbone carbohydrates found in prominent outermost positions of glycosylated molecules in mammals. Mimicry of sialic acid (N-acetylneuraminic acid, Neu5Ac) enables some pathogenic bacteria to evade host defenses. Fusobacterium nucleatum is a ubiquitous oral bacterium also linked with invasive infections throughout the body. We employed multidisciplinary approaches to test predictions that F. nucleatum engages in de novo synthesis of sialic acids. Here we show that F. nucleatum sbsp. polymorphum ATCC10953 NeuB (putative Neu5Ac synthase) restores Neu5Ac synthesis to an Escherichia coli neuB mutant. Moreover, purified F. nucleatum NeuB participated in synthesis of Neu5Ac from N-acetylmannosamine and phosphoenolpyruvate in vitro Further studies support the interpretation that F. nucleatum ATCC10953 NeuA encodes a functional CMP-sialic acid synthetase and suggest that it may also contain a C-terminal sialic acid O-acetylesterase. We also performed BLAST queries of F. nucleatum genomes, revealing that only 4/31 strains encode a complete pathway for de novo Neu5Ac synthesis. Biochemical studies including mass spectrometry were consistent with the bioinformatic predictions, showing that F. nucleatum ATCC10953 synthesizes high levels of Neu5Ac, whereas ATCC23726 and ATCC25586 do not express detectable levels above background. While there are a number of examples of sialic acid mimicry in other phyla, these experiments provide the first biochemical and genetic evidence that a member of the phylum Fusobacterium can engage in de novo Neu5Ac synthesis.
Collapse
Affiliation(s)
- Amanda L Lewis
- Department of Molecular Microbiology .,Department of Obstetrics and Gynecology
| | | | | | - Warren G Lewis
- Department of Medicine, Center for Women's Infectious Disease Research, 660 South Euclid Ave, Washington University School of Medicine, St. Louis, MO, USA
| |
Collapse
|
12
|
Evolutionary inactivation of a sialidase in group B Streptococcus. Sci Rep 2016; 6:28852. [PMID: 27352769 PMCID: PMC4926279 DOI: 10.1038/srep28852] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 06/10/2016] [Indexed: 11/17/2022] Open
Abstract
Group B Streptococcus (GBS) is a leading cause of bacterial sepsis and meningitis in newborns. GBS possesses a protein with homology to the pneumococcal virulence factor, NanA, which has neuraminidase (sialidase) activity and promotes blood-brain barrier penetration. However, phylogenetic sequence and enzymatic analyses indicate the GBS NanA ortholog has lost sialidase function – and for this distinction we designate the gene and encoded protein nonA/NonA. Here we analyze NonA function in GBS pathogenesis, and through heterologous expression of active pneumococcal NanA in GBS, potential costs of maintaining sialidase function. GBS wild-type and ΔnonA strains lack sialidase activity, but forced expression of pneumococcal NanA in GBS induced degradation of the terminal sialic acid on its exopolysaccharide capsule. Deletion of nonA did not change GBS-whole blood survival or brain microvascular cell invasion. However, forced expression of pneumococcal NanA in GBS removed terminal sialic acid residues from the bacterial capsule, restricting bacterial proliferation in human blood and in vivo upon mouse infection. GBS expressing pneumococcal NanA had increased invasion of human brain microvascular endothelial cells. Thus, we hypothesize that nonA lost enzyme activity allowing the preservation of an effective survival factor, the sialylated exopolysaccharide capsule.
Collapse
|
13
|
Whitfield GB, Marmont LS, Howell PL. Enzymatic modifications of exopolysaccharides enhance bacterial persistence. Front Microbiol 2015; 6:471. [PMID: 26029200 PMCID: PMC4432689 DOI: 10.3389/fmicb.2015.00471] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 04/29/2015] [Indexed: 12/25/2022] Open
Abstract
Biofilms are surface-attached communities of bacterial cells embedded in a self-produced matrix that are found ubiquitously in nature. The biofilm matrix is composed of various extracellular polymeric substances, which confer advantages to the encapsulated bacteria by protecting them from eradication. The matrix composition varies between species and is dependent on the environmental niche that the bacteria inhabit. Exopolysaccharides (EPS) play a variety of important roles in biofilm formation in numerous bacterial species. The ability of bacteria to thrive in a broad range of environmental settings is reflected in part by the structural diversity of the EPS produced both within individual bacterial strains as well as by different species. This variability is achieved through polymerization of distinct sugar moieties into homo- or hetero-polymers, as well as post-polymerization modification of the polysaccharide. Specific enzymes that are unique to the production of each polymer can transfer or remove non-carbohydrate moieties, or in other cases, epimerize the sugar units. These modifications alter the physicochemical properties of the polymer, which in turn can affect bacterial pathogenicity, virulence, and environmental adaptability. Herein, we review the diversity of modifications that the EPS alginate, the Pel polysaccharide, Vibrio polysaccharide, cepacian, glycosaminoglycans, and poly-N-acetyl-glucosamine undergo during biosynthesis. These are EPS produced by human pathogenic bacteria for which studies have begun to unravel the effect modifications have on their physicochemical and biological properties. The biological advantages these polymer modifications confer to the bacteria that produce them will be discussed. The expanding list of identified modifications will allow future efforts to focus on linking these modifications to specific biosynthetic genes and biofilm phenotypes.
Collapse
Affiliation(s)
- Gregory B Whitfield
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children Toronto, ON, Canada ; Department of Biochemistry, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - Lindsey S Marmont
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children Toronto, ON, Canada ; Department of Biochemistry, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| | - P Lynne Howell
- Program in Molecular Structure and Function, Research Institute, The Hospital for Sick Children Toronto, ON, Canada ; Department of Biochemistry, Faculty of Medicine, University of Toronto Toronto, ON, Canada
| |
Collapse
|
14
|
Bassagañas S, Allende H, Cobler L, Ortiz MR, Llop E, de Bolós C, Peracaula R. Inflammatory cytokines regulate the expression of glycosyltransferases involved in the biosynthesis of tumor-associated sialylated glycans in pancreatic cancer cell lines. Cytokine 2015; 75:197-206. [PMID: 25934648 DOI: 10.1016/j.cyto.2015.04.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 04/13/2015] [Accepted: 04/13/2015] [Indexed: 12/27/2022]
Abstract
BACKGROUND Pancreatic ductal adenocarcinoma (PDAC) is characterized by an abundant stroma containing several pro-inflammatory cytokines, which are described to modulate the expression of important genes related to tumor promotion and progression. In the present work we have investigated the potential role of these cytokines in the biosynthesis of tumor-associated carbohydrate antigens such as sialyl-Lewis(x) (SLe(x)) through the regulation of specific glycosyltransferase genes. METHODS Two human PDAC cell lines MDAPanc-3 and MDAPanc-28 were treated with pro-inflammatory cytokines IL-1β, TNFα, IL-6 or IL-8, and the content of tumor-associated carbohydrate antigens at the cell membrane was analyzed by flow cytometry. In addition, variation in the mRNA expression of sialyltransferase (ST) and fucosyltransferase (FUT) genes, which codify for the ST and FucT enzymes involved in the carbohydrate antigens' biosynthesis, was determined. The inflammatory microenvironment of PDAC tissues and the expression of Lewis-type antigens were analyzed by immunohistochemistry to find a possible correlation between inflammation status and the presence of tumor-associated carbohydrate antigens. RESULTS IL-1β stimuli increased SLe(x) and α2,6-sialic acid levels in MDAPanc-28 cells and enhanced the mRNA levels of ST3GAL3-4 and FUT5-7, which codify for ST and FucT enzymes related to SLe(x) biosynthesis, and of ST6GAL1. IL-6 and TNFα treatments increased the levels of SLe(x) and Le(y) antigens in MDPanc-3 cells and, similarly, the mRNA expression of ST3GAL3-4, FUT1-2 and FUT6, related to these Lewis-type antigens' biosynthesis, were increased. Most PDAC tissues stained for SLe(x) and SLe(a) and tended to be expressed in the tumor samples with a higher presence of inflammatory immune cells. CONCLUSIONS The inflammatory microenvironment can modulate the glycosylation pattern of PDAC cells, increasing the expression of tumor-associated sialylated antigens such as SLe(x), which contributes to pancreatic tumor malignancy.
Collapse
Affiliation(s)
- Sònia Bassagañas
- Biochemistry and Molecular Biology Unit, Department of Biology, University of Girona, Girona, Spain
| | - Helena Allende
- Department of Pathology, Vall d'Hebron University Hospital, Barcelona, Spain
| | - Lara Cobler
- Institut Hospital del Mar d'Investigacions Mèdiques (IMIM), Barcelona, Spain
| | - M Rosa Ortiz
- Department of Pathology, Dr. Josep Trueta University Hospital, Girona, Spain
| | - Esther Llop
- Biochemistry and Molecular Biology Unit, Department of Biology, University of Girona, Girona, Spain
| | - Carme de Bolós
- Department of Pathology, Vall d'Hebron University Hospital, Barcelona, Spain
| | - Rosa Peracaula
- Biochemistry and Molecular Biology Unit, Department of Biology, University of Girona, Girona, Spain.
| |
Collapse
|
15
|
Yuan HL, Liu XL, Liu YJ. Solanum Nigrum Polysaccharide (SNL) Extract Effects in Transplanted Tumor-bearing Mice - Erythrocyte Membrane Fluidity and Blocking of Functions. Asian Pac J Cancer Prev 2015; 15:10469-73. [DOI: 10.7314/apjcp.2014.15.23.10469] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
16
|
Abstract
Siglecs are mammalian sialic acid (Sia) recognizing immunoglobulin-like receptors expressed across the major leukocyte lineages, and function to recognize ubiquitous Sia epitopes on cell surface glycoconjugates and regulate immunological and inflammatory activities of these cells. A large subset referred to as CD33-related Siglecs are inhibitory receptors that limit leukocyte activation, and recent research has shown that the pathogen group B Streptococcus (GBS) binds to these Siglecs in Sia- and protein-dependent fashion to downregulate leukocyte bactericidal capacity. Conversely, sialoadhesin is a macrophage phagocytic receptor that engages GBS and other sialylated pathogens to promote effective phagocytosis and antigen presentation for the adaptive immune response. A variety of other important Siglec interactions with bacterial, viral and protozoan pathogens are beginning to be recognized. Siglec genes and binding specificities are rapidly evolving among primates, with key extant polymorphisms in human populations that may influence susceptibility to infection-associated disorders including chronic obstructive pulmonary disease and premature birth. This review summarizes current understanding of interactions between pathogens and Siglecs, a field of investigation that is likely to continue expanding in scope and medical importance.
Collapse
Affiliation(s)
- Yung-Chi Chang
- Glycobiology Research and Training Center Department of Pediatrics
| | - Victor Nizet
- Glycobiology Research and Training Center Department of Pediatrics Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| |
Collapse
|
17
|
Abstract
Fusobacterium nucleatum is a ubiquitous member of the human oral flora and is associated with the development of periodontitis and a variety of other types of polymicrobial infections of the mucosa. In the oral cavity, this species is one of the few that is prevalent in both healthy and diseased subgingival plaque. Using microarray analysis, we examined the transcriptional response of F. nucleatum subspecies nucleatum to whole blood in order to identify some of the genetic responses that might occur during the transition from health to disease. From these studies, we identified a sialic acid catabolism operon that was induced by the presence of blood. We subsequently confirmed that this operon was inducible by the presence of synthetic sialic acid, but we found no evidence suggesting sialic acid was used as a major carbon source. However, this organism was found to possess a de novo synthesized surface sialylation ability that is widely conserved among the various F. nucleatum subspecies as well as in F. periodonticum. We provide evidence that fusobacterial sialylation does occur in the oral cavity irrespective of health status. Interestingly, only a minority of fusobacterial cells exhibit surface sialylation within dental plaque, whereas most cells are uniformly sialylated when grown in pure culture. The implications of these results are discussed.
Collapse
|
18
|
Role of macrophage sialoadhesin in host defense against the sialylated pathogen group B Streptococcus. J Mol Med (Berl) 2014; 92:951-9. [PMID: 24788876 PMCID: PMC4133643 DOI: 10.1007/s00109-014-1157-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/23/2014] [Accepted: 04/14/2014] [Indexed: 12/01/2022]
Abstract
Abstract Several bacterial pathogens decorate their surfaces with sialic acid (Sia) residues within cell wall components or capsular exopolysaccharides. Sialic acid expression can promote bacterial virulence by blocking complement activation or by engagement of inhibitory sialic acid-binding immunoglobulin-like lectins (Siglecs) on host leukocytes. Expressed at high levels on splenic and lymph node macrophages, sialoadhesin (Sn) is a unique Siglec with an elongated structure that lacks intracellular signaling motifs. Sialoadhesin allows macrophage to engage certain sialylated pathogens and stimulate inflammatory responses, but the in vivo significance of sialoadhesin in infection has not been shown. We demonstrate that macrophages phagocytose the sialylated pathogen group B Streptococcus (GBS) and increase bactericidal activity via sialoadhesin-sialic-acid-mediated recognition. Sialoadhesin expression on marginal zone metallophillic macrophages in the spleen trapped circulating GBS and restricted the spread of the GBS to distant organs, reducing mortality. Specific IgM antibody responses to GBS challenge were also impaired in sialoadhesin-deficient mice. Thus, sialoadhesin represents a key bridge to orchestrate innate and adaptive immune defenses against invasive sialylated bacterial pathogens. Key message Sialoadhesin is critical for macrophages to phagocytose and clear GBS. Increased GBS organ dissemination in the sialoadhesin-deficient mice. Reduced anti-GBS IgM production in the sialoadhesin-deficient mice.
Electronic supplementary material The online version of this article (doi:10.1007/s00109-014-1157-y) contains supplementary material, which is available to authorized users.
Collapse
|
19
|
Khatua B, Roy S, Mandal C. Sialic acids siglec interaction: a unique strategy to circumvent innate immune response by pathogens. Indian J Med Res 2013; 138:648-62. [PMID: 24434319 PMCID: PMC3928697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Sialic acids (Sias) are nine-carbon keto sugars primarily present on the terminal residue of cell surface glycans. Sialic acid binding immunoglobulins (Ig)-like lectins (siglecs) are generally expressed on various immune cells. They selectively recognize different linkage-specific sialic acids and undertake a variety of cellular functions. Many pathogens either synthesize or acquire sialic acids from the host. Sialylated pathogens generally use siglecs to manipulate the host immune response. The present review mainly deals with the newly developed information regarding mechanism of acquisition of sialic acids by pathogens and their biological relevance especially in the establishment of successful infection by impairing host innate immunity. The pathogens which are unable to synthesize sialic acids might adsorb these from the host as a way to engage the inhibitory siglecs. They promote association with the immune cells through sialic acids-siglec dependent manner. Such an association plays an important role to subvert host's immunity. Detailed investigation of these pathways has been discussed in this review. Particular attention has been focused on Pseudomonas aeruginosa (PA) and Leishmania donovani.
Collapse
Affiliation(s)
- Biswajit Khatua
- Cancer Biology & Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Saptarshi Roy
- Cancer Biology & Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India
| | - Chitra Mandal
- Cancer Biology & Inflammatory Disorder Division, CSIR-Indian Institute of Chemical Biology, Kolkata, India,Reprint requests: Dr Chitra Mandal, Cancer Biology & Inflammatory Disorders Division, CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata 700 032, India e-mail: or
| |
Collapse
|
20
|
Deng L, Chen X, Varki A. Exploration of sialic acid diversity and biology using sialoglycan microarrays. Biopolymers 2013; 99:650-65. [PMID: 23765393 PMCID: PMC7161822 DOI: 10.1002/bip.22314] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Accepted: 06/04/2013] [Indexed: 12/13/2022]
Abstract
Sialic acids (Sias) are a group of α-keto acids with a nine-carbon backbone, which display many types of modifications in nature. The diversity of natural Sia presentations is magnified by a variety of glycosidic linkages to underlying glycans, the sequences and classes of such glycans, as well as the spatial organization of Sias with their surroundings. This diversity is closely linked to the numerous and varied biological functions of Sias. Relatively large libraries of natural and unnatural Sias have recently been chemically/chemoenzymatically synthesized and/or isolated from natural sources. The resulting sialoglycan microarrays have proved to be valuable tools for the exploration of diversity and biology of Sias. Here we provide an overview of Sia diversity in nature, the approaches used to generate sialoglycan microarrays, and the achievements and challenges arising.
Collapse
Affiliation(s)
- Lingquan Deng
- Departments of Medicine and Cellular & Molecular MedicineGlycobiology Research and Training Center, University of CaliforniaSan Diego, La JollaCA92093‐0687
| | - Xi Chen
- Department of ChemistryUniversity of CaliforniaDavisCA95616
| | - Ajit Varki
- Departments of Medicine and Cellular & Molecular MedicineGlycobiology Research and Training Center, University of CaliforniaSan Diego, La JollaCA92093‐0687
| |
Collapse
|
21
|
Lewis WG, Robinson LS, Gilbert NM, Perry JC, Lewis AL. Degradation, foraging, and depletion of mucus sialoglycans by the vagina-adapted Actinobacterium Gardnerella vaginalis. J Biol Chem 2013; 288:12067-79. [PMID: 23479734 DOI: 10.1074/jbc.m113.453654] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Bacterial vaginosis (BV) is a polymicrobial imbalance of the vaginal microbiota associated with reproductive infections, preterm birth, and other adverse health outcomes. Sialidase activity in vaginal fluids is diagnostic of BV and sialic acid-rich components of mucus have protective and immunological roles. However, whereas mucus degradation is believed to be important in the etiology and complications associated with BV, the role(s) of sialidases and the participation of individual bacterial species in the degradation of mucus barriers in BV have not been investigated. Here we demonstrate that the BV-associated bacterium Gardnerella vaginalis uses sialidase to break down and deplete sialic acid-containing mucus components in the vagina. Biochemical evidence using purified sialoglycan substrates supports a model in which 1) G. vaginalis extracellular sialidase hydrolyzes mucosal sialoglycans, 2) liberated sialic acid (N-acetylneuraminic acid) is transported into the bacterium, a process inhibited by excess N-glycolylneuraminic acid, and 3) sialic acid catabolism is initiated by an intracellular aldolase/lyase mechanism. G. vaginalis engaged in sialoglycan foraging in vitro, in the presence of human vaginal mucus, and in vivo, in a murine vaginal model, in each case leading to depletion of sialic acids. Comparison of sialic acid levels in human vaginal specimens also demonstrated significant depletion of mucus sialic acids in women with BV compared with women with a "normal" lactobacilli-dominated microbiota. Taken together, these studies show that G. vaginalis utilizes sialidase to support the degradation, foraging, and depletion of protective host mucus barriers, and that this process of mucus barrier degradation and depletion also occurs in the clinical setting of BV.
Collapse
Affiliation(s)
- Warren G Lewis
- Departments of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA.
| | | | | | | | | |
Collapse
|
22
|
Rouhanifard SH, Nordstrøm LU, Zheng T, Wu P. Chemical probing of glycans in cells and organisms. Chem Soc Rev 2012; 42:4284-96. [PMID: 23257905 DOI: 10.1039/c2cs35416k] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Among the four major building blocks of life, glycans play essential roles in numerous physiological and pathological processes. Due to their non-templated biosynthesis, advances towards elucidating the molecular details of glycan functions are relatively slow compared with the pace of protein and nucleic acid research. Over the past 30 years, chemical tools have emerged as powerful allies to genetics and molecular biology in the study of glycans in their native environment. This tutorial review will provide an overview of the recent technological developments in the field, as well as the progress in the application of these techniques to probe glycans in cells and organisms.
Collapse
Affiliation(s)
- Sara H Rouhanifard
- Department of Biochemistry, Yeshiva University, 1300 Morris Park Ave, Bronx, NY 10461, USA
| | | | | | | |
Collapse
|
23
|
Immune modulation by group B Streptococcus influences host susceptibility to urinary tract infection by uropathogenic Escherichia coli. Infect Immun 2012; 80:4186-94. [PMID: 22988014 DOI: 10.1128/iai.00684-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Urinary tract infection (UTI) is most often caused by uropathogenic Escherichia coli (UPEC). UPEC inoculation into the female urinary tract (UT) can occur through physical activities that expose the UT to an inherently polymicrobial periurethral, vaginal, or gastrointestinal flora. We report that a common urogenital inhabitant and opportunistic pathogen, group B Streptococcus (GBS), when present at the time of UPEC exposure, undergoes rapid UPEC-dependent exclusion from the murine urinary tract, yet it influences acute UPEC-host interactions and alters host susceptibility to persistent outcomes of bladder and kidney infection. GBS presence results in increased UPEC titers in the bladder lumen during acute infection and reduced inflammatory responses of murine macrophages to live UPEC or purified lipopolysaccharide (LPS), phenotypes that require GBS mimicry of host sialic acid residues. Taken together, these studies suggest that despite low titers, the presence of GBS at the time of polymicrobial UT exposure may be an overlooked risk factor for chronic pyelonephritis and recurrent UTI in susceptible groups, even if it is outcompeted and thus absent by the time of diagnosis.
Collapse
|
24
|
Abstract
Sialic acids have a pivotal functional impact in many biological interactions such as virus attachment, cellular adhesion, regulation of proliferation, and apoptosis. A common modification of sialic acids is O-acetylation. O-Acetylated sialic acids occur in bacteria and parasites and are also receptor determinants for a number of viruses. Moreover, they have important functions in embryogenesis, development, and immunological processes. O-Acetylated sialic acids represent cancer markers, as shown for acute lymphoblastic leukemia, and they are known to play significant roles in the regulation of ganglioside-mediated apoptosis. Expression of O-acetylated sialoglycans is regulated by sialic acid-specific O-acetyltransferases and O-acetylesterases. Recent developments in the identification of the enigmatic sialic acid-specific O-acetyltransferase are discussed.
Collapse
Affiliation(s)
- Chitra Mandal
- Cancer and Cell Biology, Council of Scientific and Industrial Research - Indian Institute of Chemical Biology, 4 Raja S.C. Mallick Road, Kolkata, 700 032 India
| | - Reinhard Schwartz-Albiez
- Department of Translational Immunology, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Reinhard Vlasak
- Department of Molecular Biology, University Salzburg, Billrothstr 11, 5020 Salzburg, Austria
| |
Collapse
|
25
|
Segura M. Fisher scientific award lecture - the capsular polysaccharides of Group B Streptococcus and Streptococcus suis differently modulate bacterial interactions with dendritic cells. Can J Microbiol 2012; 58:249-60. [PMID: 22356626 DOI: 10.1139/w2012-003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Infections with encapsulated bacteria cause serious clinical problems. Besides being poorly immunogenic, the bacterial capsular polysaccharide (CPS) cloaks antigenic proteins, allowing bacterial evasion of the host immune system. Despite the clinical significance of bacterial CPS and its suggested role in the pathogenesis of the infection, the mechanisms underlying innate and, critically, adaptive immune responses to encapsulated bacteria have not been fully elucidated. As such, we became interested in studying the CPS of two similar, but unique, streptococcal species: Group B Streptococcus (GBS) and Streptococcus suis . Both streptococci are well encapsulated, some capsular types are more virulent than others, and they can cause severe meningitis and septicemia. For both pathogens, the CPS is considered the major virulence factor. Finally, these two streptococci are the sole Gram-positive bacteria possessing sialic acid in their capsules. GBS type III is a leading cause of neonatal invasive infections. Streptococcus suis type 2 is an important swine and emerging zoonotic pathogen in humans. We recently characterized the S. suis type 2 CPS. It shares common structural elements with GBS, but sialic acid is α2,6-linked to galactose rather than α2,3-linked. Differential sialic acid expression by pathogens might result in modulation of immune cell activation and, consequently, may affect the immuno-pathogenesis of these bacterial infections. Here, we review and compare the interactions of these two sialylated encapsulated bacteria with dendritic cells, known as the most potent antigen-presenting cells linking innate and adaptive immunity. We further address differences between dendritic cells and professional phagocytes, such as macrophages and neutrophils, in their interplay with these encapsulated pathogens. Elucidation of the molecular and cellular basis of the impact of CPS composition on bacterial interactions with immune cells is critical for mechanistic understanding of anti-CPS responses. Knowledge generated will help to advance the development of novel, more effective anti-CPS vaccines and improved immunotherapies.
Collapse
Affiliation(s)
- Mariela Segura
- Laboratory of Immunology, Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, 3200 rue Sicotte, St-Hyacinthe, QC J2S 2M2, Canada.
| |
Collapse
|
26
|
Abstract
Cell surface expression of sialic acid has been reported to decrease during immune cell activation, but the significance and regulation of this phenomenon are still being investigated. The major human bacterial pathogen Streptococcus pneumoniae causes pneumonia, sepsis and meningitis, often accompanied by strong inflammatory responses. S. pneumoniae expresses a sialidase (NanA) that contributes to mucosal colonization, platelet clearance, and blood-brain barrier penetration. Using wild-type and isogenic NanA-deficient mutant strains, we showed that S. pneumoniae NanA can desialylate the surface of human THP-1 monocytes, leading to increased ERK phosphorylation, NF-κB activation, and proinflammatory cytokine release. S. pneumoniae NanA expression also stimulates interleukin-8 release and extracellular trap formation from human neutrophils. A mechanistic contribution of unmasking of inhibitory Siglec-5 from cis sialic acid interactions to the proinflammatory effect of NanA is suggested by decreased SHP-2 recruitment to the Siglec-5 intracellular domain and RNA interference studies. Finally, NanA increased production of proinflammatory cytokines in a murine intranasal challenge model of S. pneumoniae pneumonia. Importance Sialic acids decorate the surface of all mammalian cells and play important roles in physiology, development, and evolution. Siglecs are sialic acid-binding receptors on the surface of immune cells, many of which engage in cis interactions with host sialoglycan ligands and dampen inflammatory responses through transduction of inhibitory signals. Recently, certain bacterial pathogens have been shown to suppress leukocyte innate immune responses by molecular mimicry of host sialic acid structures and engagement of inhibitory Siglecs. Our present work shows that the converse can be true, i.e., that a microbial sialic acid-cleaving enzyme can induce proinflammatory responses, which are in part mediated by unmasking of an inhibitory Siglec. We conclude that host leukocytes are poised to detect and respond to microbial sialidase activity with exaggerated inflammatory responses, which could be beneficial or detrimental to the host depending on the site, stage and magnitude of infection. Sialic acids decorate the surface of all mammalian cells and play important roles in physiology, development, and evolution. Siglecs are sialic acid-binding receptors on the surface of immune cells, many of which engage in cis interactions with host sialoglycan ligands and dampen inflammatory responses through transduction of inhibitory signals. Recently, certain bacterial pathogens have been shown to suppress leukocyte innate immune responses by molecular mimicry of host sialic acid structures and engagement of inhibitory Siglecs. Our present work shows that the converse can be true, i.e., that a microbial sialic acid-cleaving enzyme can induce proinflammatory responses, which are in part mediated by unmasking of an inhibitory Siglec. We conclude that host leukocytes are poised to detect and respond to microbial sialidase activity with exaggerated inflammatory responses, which could be beneficial or detrimental to the host depending on the site, stage and magnitude of infection.
Collapse
|
27
|
Abstract
Sialic acid-binding Ig-like lectins, or Siglecs, vary in their specificity for sialic acid-containing ligands and are mainly expressed by cells of the immune system. Many Siglecs are inhibitory receptors expressed in innate immune cells that regulate inflammation mediated by damage-associated and pathogen-associated molecular patterns (DAMPs and PAMPs). This family also includes molecules involved in adhesion and phagocytosis and receptors that can associate with the ITAM-containing DAP12 adaptor. Siglecs contribute to the inhibition of immune cells both by binding to cis ligands (expressed in the same cells) and by responding to pathogen-derived sialoglycoconjugates. They can help maintain tolerance in B lymphocytes, modulate the activation of conventional and plasmacytoid dendritic cells, and contribute to the regulation of T cell function both directly and indirectly. Siglecs modulate immune responses, influencing almost every cell in the immune system, and are of relevance both in health and disease.
Collapse
Affiliation(s)
- Shiv Pillai
- Center for Cancer Research, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02129, USA.
| | | | | | | |
Collapse
|
28
|
Lartigue MF, Poulard AF, Al Safadi R, Pailhories H, Domelier-Valentin AS, van der Mee-Marquet N, Rosenau A, Quentin R. Variability of neuD transcription levels and capsular sialic acid expression among serotype III group B Streptococcus strains. Microbiology (Reading) 2011; 157:3282-3291. [DOI: 10.1099/mic.0.050013-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Serotype III group B Streptococcus (GBS) is the major cause of neonatal meningitis, but the risk of infection in the colonized neonates is variable. Capsular sialic acid (Sia), whose synthesis is encoded by neu genes, appears to be a major virulence factor in several bacterial species able to reach the cerebrospinal fluid. Therefore, variations of Sia expression related to the genetic diversity of strains may have an impact on the risk of meningitis in colonized neonates. We characterized by MLST the phylogenetic diversity of 64 serotype III GBS strains isolated from vaginal flora and randomly selected. These strains mostly belonged to three major sequence types (STs): ST1 (11 %), ST17 (39 %) and ST19 (31 %). The genetic diversity of strains of these lineages, characterized by PFGE, allowed the selection of 17 representative strains, three ST1, six ST17 and eight ST19, with NEM316 as reference, in order to evaluate (i) by quantitative RT-PCR, the level of transcription of the neuD gene as a marker for the transcription of neu genes and (ii) by enzymological analysis, the expression of Sia. The mean transcription level of neuD was higher for ST17 strains than for ST1 and ST19 strains in the early, mid- and late exponential growth phases, and was maximum in the early exponential growth phase for ST17 strains and in the mid-exponential growth phase for ST1 and ST19 strains. Mean Sia concentration was higher for ST17 than for ST1 and ST9 strains in all three growth phases. For the total population, Sia concentration varied notably in the stationary phase, from 0.38 to 9.30 nmol per 108 viable bacteria, with a median value of 2.99 nmol per 108 bacteria. All ST17 strains, only one-third of the ST19 strains and none of the ST1 strains had Sia concentrations higher than the median Sia concentration. Therefore, differences in the level of expression of Sia by strains of the major serotype III GBS phylogenetic lineages might be one of the factors that explain the leading role of ST17 strains in neonatal meningitis.
Collapse
Affiliation(s)
- Marie-Frédérique Lartigue
- Service de Bactériologie et Hygiène Hospitalière, Hôpital Trousseau, CHRU de Tours, 37044 Tours, France
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| | - Agnès Fribourg Poulard
- Service de Bactériologie et Hygiène Hospitalière, Hôpital Trousseau, CHRU de Tours, 37044 Tours, France
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| | - Rim Al Safadi
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| | - Hélène Pailhories
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| | - Anne-Sophie Domelier-Valentin
- Service de Bactériologie et Hygiène Hospitalière, Hôpital Trousseau, CHRU de Tours, 37044 Tours, France
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| | - Nathalie van der Mee-Marquet
- Service de Bactériologie et Hygiène Hospitalière, Hôpital Trousseau, CHRU de Tours, 37044 Tours, France
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| | - Agnès Rosenau
- Service de Bactériologie et Hygiène Hospitalière, Hôpital Trousseau, CHRU de Tours, 37044 Tours, France
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| | - Roland Quentin
- Service de Bactériologie et Hygiène Hospitalière, Hôpital Trousseau, CHRU de Tours, 37044 Tours, France
- Université François-Rabelais de Tours, UFR de Médecine, EA 3854 ‘Bactéries et Risque Materno-foetal’, Institut Fédératif de Recherche 136 ‘Agents Transmissibles et Infectiologie’, 37032 Tours Cedex, France
| |
Collapse
|
29
|
The immune response to group B streptococcus type III capsular polysaccharide is directed to the -Glc-GlcNAc-Gal- backbone epitope. Glycoconj J 2011; 28:557-62. [PMID: 21984010 DOI: 10.1007/s10719-011-9354-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2011] [Revised: 09/09/2011] [Accepted: 09/28/2011] [Indexed: 10/17/2022]
Abstract
The structures of the branched capsular polysaccharides of group B streptococcus type III (GBSIIIPS) and Streptococcus pneumoniae type 14 (Pn14PS) are identical apart from the (α2→3)-linked sialic acid in the side chains of GBSIIIPS. The present study tries to determine the minimal epitope in GBSIIIPS, using both a panel of anti-Pn14PS mouse sera and sera of humans vaccinated with either Pn14PS or GBSIIIPS. Type-specific Pn14PS antibodies that recognize the branched structure of Pn14PS have a low affinity for the native GBSIIIPS. Desialylation of GBSIIIPS results in dramatically higher affinity of anti-Pn14PS antibodies. Epitope specific anti-Pn14PS mouse antibodies and human sera of PCV7 vaccinees only recognized structures with the branching element -Glc-(Gal-)GlcNAc-, in particular -Gal-Glc-(Gal-)GlcNAc- in Pn14PS. On the other hand anti-GBSIIIPS human antibodies recognize predominantly the linear structure in the backbone of Pn14PS or GBSIIIPS, i.e., -Glc-GlcNAc-Gal-. This difference in antigenicity of Pn14PS and GBSIIIPS is in agreement with the difference in flexibility of the two polysaccharides caused by the presence or absence of sialic acid.
Collapse
|
30
|
NeuA O-acetylesterase activity is specific for CMP-activated O-acetyl sialic acid in Streptococcus suis serotype 2. Biochem Biophys Res Commun 2011; 410:212-7. [DOI: 10.1016/j.bbrc.2011.05.092] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Accepted: 05/15/2011] [Indexed: 11/17/2022]
|
31
|
Immune activation and suppression by group B streptococcus in a murine model of urinary tract infection. Infect Immun 2011; 79:3588-95. [PMID: 21690238 DOI: 10.1128/iai.00122-11] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Group B streptococcus (GBS) is a common commensal of the gastrointestinal and vaginal mucosa and a leading cause of serious infections in newborns, the elderly, and immunocompromised populations. GBS also causes infections of the urinary tract. However, little is known about host responses to GBS urinary tract infection (UTI) or GBS virulence factors that participate in UTI. Here we describe a novel murine model of GBS UTI that may explain some features of GBS urinary tract association in the human host. We observed high titers and heightened histological signs of inflammation and leukocyte recruitment in the GBS-infected kidney. However, extensive inflammation and leukocyte recruitment were not observed in the bladder, suggesting that GBS may suppress bladder inflammation during cystitis. Acute GBS infection induced the localized expression of proinflammatory cytokines interleukin-1α (IL-1α), macrophage inflammatory protein-1α (MIP-1α), MIP-1β, and IL-9, as well as IL-10, more commonly considered an anti-inflammatory cytokine. Using isogenic GBS strains with different capsule structures, we show that capsular sialic acid residues contribute to GBS urinary tract pathogenesis, while high levels of sialic acid O-acetylation attenuate GBS pathogenesis in the setting of UTI, particularly in direct competition experiments. In vitro studies demonstrated that GBS sialic acids participate in the suppression of murine polymorphonuclear leukocyte (PMN) bactericidal activities, in addition to reducing levels of IL-1α, tumor necrosis factor alpha, IL-1β, MIP-1α, and KC produced by PMNs. These studies define several basic molecular and cellular events characterizing GBS UTI in an animal model, showing that GBS participates simultaneously in the activation and suppression of host immune responses in the urinary tract.
Collapse
|
32
|
Cao H, Crocker PR. Evolution of CD33-related siglecs: regulating host immune functions and escaping pathogen exploitation? Immunology 2011; 132:18-26. [PMID: 21070233 PMCID: PMC3015071 DOI: 10.1111/j.1365-2567.2010.03368.x] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 09/20/2010] [Accepted: 09/21/2010] [Indexed: 12/22/2022] Open
Abstract
Sialic-acid-binding immunoglobulin-like lectins, siglecs, are important immune receptors expressed widely in mammals. A unique feature of siglecs is their ability to bind sialylated glycans and transmit signals to immune cells. The CD33-related siglecs (CD33rSiglecs) form a major subfamily of the siglecs, containing a large, rapidly evolving group of genes that expanded in mammals through an inverse duplication event involving a primordial cluster of siglec genes over 180 million years ago. Humans express a much larger set of CD33rSiglecs than mice and rats, a feature that can be explained by a dramatic loss of CD33rSiglec genes in rodents. Most CD33rSiglecs have immune receptor tyrosine-based inhibitory motifs and signal negatively. Interestingly, novel DAP-12-coupled 'activating' CD33rSiglecs have been identified, such as siglec-14 and siglec-16, which are paired with the inhibitory receptors, siglec-5 and siglec-11, respectively. The evolution of these activating receptors may have been driven in part by pathogen exploitation of inhibitory siglecs, thereby providing the host with additional pathways by which to combat these pathogens. Inhibitory siglecs seem to play important and varied roles in the regulation of host immune responses. For example, several CD33rSiglecs have been implicated in the negative regulation of Toll-like receptor signalling during innate responses; siglec-G functions as a negative regulator of B1-cell expansion and appears to suppress inflammatory responses to host-derived 'danger-associated molecular patterns'. Recent work has also shown that engagement of neutrophil-expressed siglec-9 by certain strains of sialylated Group B streptococci can suppress killing responses, thereby providing experimental support for pathogen exploitation of host CD33rSiglecs.
Collapse
Affiliation(s)
- Huan Cao
- Wellcome Trust Biocentre, Division of Cell Biology and Immunology, College of Life Sciences, University of Dundee, Dundee, UK.
| | | |
Collapse
|
33
|
Weiman S, Uchiyama S, Lin FYC, Chaffin D, Varki A, Nizet V, Lewis AL. O-Acetylation of sialic acid on Group B Streptococcus inhibits neutrophil suppression and virulence. Biochem J 2010; 428:163-8. [PMID: 20334627 PMCID: PMC3640289 DOI: 10.1042/bj20100232] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
GBS (Group B Streptococcus) requires capsular Sia (sialic acid) for virulence and partially modifies this sugar by O-acetylation. In the present paper we describe serotype-specific patterns of GBS Sia O-acetylation that can be manipulated by genetic and biochemical means. In vitro and in vivo assays demonstrate that this subtle modification attenuates GBS Sia-mediated neutrophil suppression and animal virulence.
Collapse
Affiliation(s)
- Shannon Weiman
- Department of Pediatrics, Glycobiology Research and Training Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093-0687, U.S.A
| | | | | | | | | | | | | |
Collapse
|
34
|
Abstract
Sialic acids are a subset of nonulosonic acids, which are nine-carbon alpha-keto aldonic acids. Natural existing sialic acid-containing structures are presented in different sialic acid forms, various sialyl linkages, and on diverse underlying glycans. They play important roles in biological, pathological, and immunological processes. Sialobiology has been a challenging and yet attractive research area. Recent advances in chemical and chemoenzymatic synthesis, as well as large-scale E. coli cell-based production, have provided a large library of sialoside standards and derivatives in amounts sufficient for structure-activity relationship studies. Sialoglycan microarrays provide an efficient platform for quick identification of preferred ligands for sialic acid-binding proteins. Future research on sialic acid will continue to be at the interface of chemistry and biology. Research efforts not only will lead to a better understanding of the biological and pathological importance of sialic acids and their diversity but also could lead to the development of therapeutics.
Collapse
Affiliation(s)
- Xi Chen
- Department of Chemistry, University of California, Davis, California 95616, USA.
| | | |
Collapse
|