Interactions of bacterial adhesins with the extracellular matrix.
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Adhesins, Bacterial↗
Biomedical subjects
T Wadström
Publications and source records attributed to T Wadström.
Adhesion of Helicobacter pylori strains to alpha-2,3-linked sialic acids.
Helicobacter pylori is a human pathogen associated with gastritis and peptic ulcer. Adhesion properties of H. pylori to various structures have been described in the literature, including evidence for sialic acid-binding. To study the specificity and frequency of sialic acid-binding, fourteen H. pylori strains were investigated using haemagglutination with derivatized erythrocytes carrying sialic acids only on defined glycans and using haemagglutination inhibition assays. From these studies H. pylori strains can be grouped into sialic acid-dependent and sialic acid-independent classes. The sialic acid-dependent strains require alpha-2,3-linked sialic acid for haemagglutination. The potential roles of sialic acid-dependent adhesions for H. pylori-related infections are discussed.
Asialoglycoproteins↗
Staphylococci bind heparin-binding host growth factors.
Staphylococcus aureus, which mediated binding to heparan sulfate, and also strains of coagulase-negative staphylococci (CNS) adhered in high numbers to polymers with end-point attached heparin. A characteristic feature of several cell growth factors is strong affinity for heparin. In the present study, binding of the 125I-labeled heparin-binding growth factors (HBGF), acidic and basic fibroblast growth factor (aFGF, bFGF), and platelet-derived growth factor (PDGF) by S. aureus and CNS strains was examined. Staphylococcal strains used in this study bind bFGF and PDGF, but not aFGF. The binding of bFGF and PDGF was time dependent, influenced by pH and ionic strength for S. aureus Cowan 1. Preincubation of staphylococcal cells with unlabeled bFGF enhanced bFGF binding, but heparin, protamine sulfate, poly-L-lysine, and suramin were potent inhibitors of 125I-bFGF binding to cells of S. aureus Cowan 1. Glycosaminoglycans of comparable size (chondroitin sulfate), other polysulfated polymers (lambda-carrageenan, fucoidan), and some polysulfated polysaccharides (dextran sulfate, pentosan polysulfate) inhibited binding of both GFs to various extents. The partial inhibition of binding of both GFs after protease and periodate treatments indicates that both proteinaceous and other carbohydrate moieties participate in the binding. A lysozyme cell surface extract and bacterial lysates of S. aureus Cowan 1 competitively inhibited binding of 125I-bFGF and 125I-PDGF. These results suggest that staphylococci have the ability to bind two of the HBGFs, bFGF and PDGF, but not aFGF, via more than one cell structure. These binding structures seem to be exposed on the cell surface and deeply anchored in the cytoplasmic membrane as well.
Anti-Bacterial Agents↗
The proliferation of human T lymphocytes stimulated by Helicobacter pylori antigens.
Fractionated mononuclear cells (MNCs) were obtained from peripheral blood of healthy human volunteers, seronegative for H. pylori antibodies. The MNCs were stimulated in culture with whole live or heat-killed H. pylori cells or with bacterial cell surface (SA) or cytoplasmic (CA) antigens. There was a marked proliferative response of T cells in cultures stimulated with 10(5) cells/well of live H. pylori, 5 micrograms/well of CA or 5-20 micrograms/well of SA. However, no proliferation was observed in MNC cultures containing higher "doses" of live H. pylori organisms (10(7)/well) or CA (20 micrograms/well). Moreover, higher "doses" of the bacteria or CA entirely inhibited the response of T cells to PHA.
Adhesins, Bacterial↗
Biochemical aspects of Helicobacter pylori colonization of the human gastric mucosa.
Unlike Helicobacter felis and other Helicobacter species of animal origin, Helicobacter pylori colonizes the lower gastric mucin layer of the stomach and adheres to human gastric epithelial cells. It is still an open question if H. pylori can interact with specific glycoconjugates in the gastric mucin layer. It is possible that colonization of the oral cavity is a first step of a complex infectious process. Most likely resting or slow growing cells of H. pylori interact with Lewis blood group substances in the gastric mucin layer and on the epithelium. This initial colonization is probably followed by binding to specific cell surface glycoconjugates (glycoproteins and glycolipids such as GM3) and specific sialylated or highly sulphated molecules such as cell surface sulphatides and heparan sulphate. H. pylori may also bind to specific phospholipid molecules such as phosphatidylethanolamine on the gastric cells. The adhesion process of certain strains can stimulate 'close' cell adhesion including pedestal formation similar to the phenomenon typical for a special class of enterovirulent Escherichia coli called attaching effacing E. coli. After gastric cell destruction by ammonia and H. pylori toxins (such as the vacuolating toxin) H. pylori may colonize the extracellular matrix (ECM). This phenomenon seems to include binding of cell surface sialic acid specific haemagglutinin to one ECM component, i.e. laminin. It is also likely that H. pylori may use similar events to penetrate intercellular junctions of gastric epithelial cells. These adhesion-penetration phenomena also involve coating of the microbe with host proteins to escape the host immune system and initiate a chronic lifelong infection process.
Bacterial Adhesion↗
Helicobacter pylori infections in IgA deficiency: lack of role for the secretory immune system.
During the last years considerable attention has been focused on the possibility of the development of an oral vaccine against Helicobacter pylori. However, Helicobacter infection is known to be life-long, despite a vigorous immune response, and the hypothesis that an increased local production of secretory IgA in the gastric mucosa, due to vaccination, should protect against the colonization of the bacterium may therefore be questioned. In this study, when comparing the seropositivity and titre against H. pylori in IgA-deficient patients and age-related normal blood donors, it appears that lack of secretory IgA does not seem to have any major influence on the prevalence of the infection, nor is it reflected in titres of specific IgG antibodies. These results many argue against a pivotal role for IgA in the defence against Helicobacter, and raise questions about current strategies for the development of an oral vaccine against H. pylori and may point to a need for alternative therapeutic strategies.
Adult↗
A particle agglutination assay for rapid identification of heparin binding to coagulase-negative staphylococci.
The heparin-binding properties of six different species of coagulase-negative staphylococci were examined by a particle agglutination assay. Heparin (mol. wt 4000-6000), mildly treated with sodium periodate, was covalently coupled to amino-modified latex beads (0.72 micron diameter). The particle agglutination assay was validated by comparing results with the adhesion (percentage binding of adherent cells) of coagulase-negative staphylococcal strains to heparinised microtitration plates. Of 38 different coagulase-negative staphylococcal strains tested, 30 showed agglutination reactivity with heparin-coated latex beads. Strains of different coagulase-negative staphylococcal species agglutinated heparin-coated latex beads to various extents (e.g., cells of Staphylococcus haemolyticus strains reacted more strongly than cells of S. epidermidis strains). The agglutination reaction was significantly inhibited by fucoidan, suramin, lambda-carrageenan and other sulphated compounds, but not by non-sulphated carbohydrate polymers such as hyaluronic acid. Agglutination of staphylococcal cells with heparin-coated latex beads was completely blocked by a cell-surface extract. These results suggest that structures responsible for heparin binding are exposed on the cell surface.
Agglutination Tests↗
Binding of extracellular matrix proteins to the surface of anaerobic bacteria.
The binding of fibronectin, vitronectin, collagen and sialoprotein to 65 anaerobic strains was investigated by means of latex agglutination tests. The binding of fibronectin, collagen and lactoferrin to the same strains was also tested by means of 125I-labelled proteins. The strains were isolated from abdominal infections (55%), from the faeces of healthy subjects (29%) or from the depths of tonsils removed at tonsillectomy (16%). The binding of fibronectin and collagen to Bacteroides fragilis strains, tested by the latex agglutination assay, was stronger than their binding to other species. The vitronectin binding of the strains was less common, but was always accompanied by fibronectin binding. Binding to fibronectin-coated beads was inhibited by pre-incubation of the bacterial cells with soluble fibronectin and by heat or protease treatment of the bacterial suspension. No inhibition of the binding was observed with carbohydrates. None of the 65 strains exhibited any binding to fetuin or asialofetuin; 8% of the strains had a binding site for mucin. The binding to mucin-coated beads was inhibited by pre-incubation of the cells with mucin. The radiolabelling method indicated a low binding to 125I-fibronectin. The binding of 125I-collagen-I and 125I-lactoferrin was higher for the anaerobic strains tested.
Bacteria, Anaerobic↗
Binding of human plasminogen and lactoferrin by Helicobacter pylori coccoid forms.
The interactions between Helicobacter pylori spiral and coccoid forms, extracellular matrix (ECM) and plasma proteins were studied in an 125I-labelled protein assay. The range of binding of collagen V, plasminogen, human lactoferrin (HLf) and vitronectin to coccoid forms of H. pylori NCTC 11637 was 26-48%. In contrast, binding of radiolabelled fibronectin and collagen types I and III was low (3-8%). The coccoid forms of 14 strains of H. pylori showed significant HLf binding (median 26%). With plasminogen, no significant difference was found between binding to the coccoid (median = 13%) and spiral (median = 12%) forms, of 13 of the 14 strains of H. pylori tested; the exception was strain NCTC 11637. 125I-plasminogen showed a dose-dependent binding to both the coccoid and spiral forms. Plasminogen binding to both forms was specific; the binding was inhibited by non-labelled plasminogen, plasmin, lysine, EACA (epsilon-aminocaproic acid) but not by fetuin or various carbohydrates. Similarly, HLf binding was found to be specific and was inhibited by non-labelled HLf and BLf. The coccoid forms showed either similar or enhanced ECM binding capabilities compared with the spiral forms. As the binding of ECM proteins may be an important mechanism of tissue adhesion for various pathogenic bacteria, the coccoid differentiated form of H. pylori can be considered as an infective form in the pathogenesis of helicobacter infection and type B gastritis.
Collagen↗
Gastrointestinal colonisation of BALB/cA mice by Helicobacter pylori monitored by heparin magnetic separation.
Immunocompetent and immunodeficient BALB/cA mice were fed orally with 10(8) colony forming units of 2-day-old spiral or coccoid (12 days old) Helicobacter pylori strain NCTC 11637. Immunocompetent BALB/cA mice were also fed orally with decreasing numbers of spiral or coccoid forms of H. pylori. The gastrointestinal colonisation process was monitored for 34 days post-infection by heparin magnetic separation and subsequent enzyme immunoassay (EIA) for the detection of the H. pylori cells. Both mice types were colonised with H. pylori. The coccoid form of H. pylori gave higher EIA absorbance values and more efficient colonisation in the mice than the spiral form. Immunocompetent BALB/cA mice fed with the coccoid form of H. pylori exhibited an acute inflammation process in histopathological samples from the stomachs. In conclusion, H. pylori can infect both immunocompetent as well as immunodeficient BALB/cA mice and coccoids (viable but non-culturable) obtained after 12 days of culturing can infect BALB/cA mice.
Animals↗
Seroprevalence of Helicobacter pylori in south Sweden and Iceland.
BACKGROUND: Seroepidemiologic studies on the prevalence of Helicobacter pylori infection have been reported from several European countries but not from Sweden or Iceland. METHODS: Serum samples were collected from 443 persons in Sweden and 387 persons in Iceland. All the 830 sera were tested with the same enzyme immunoassay test with an acid glycine extract of H. pylori surface proteins as antigen. RESULTS: The antibody levels were low in the young age groups in both Sweden and Iceland, with increasing levels with age. CONCLUSIONS: The results are consistent with previous studies from other comparable countries, but with important differences. The prevalence was lower in Sweden than in other, previously studied, Western European countries, but, on the other hand, the prevalence was slightly higher in Iceland.
Adolescent↗
PCR for identification and typing of Helicobacter pylori isolated from children.
From 191 children with upper gastroduodenal disease 236 gastric biopsy specimens were taken. H. pylori was detected by use of culture Gram staining histological examination and PCR technique. A segment of DNA coding protein synthesis of 26 kDa or urease A and B gene were used for PCR amplification. PCR technique was also used for determination of the presence of Cag A gene in 72 strains of H. pylori isolated from children. Genetic typing of H. pylori strains by RFLP analysis of PCR amplified urease B gene 933 bp fragment and RAPD were performed. Biopsy specimens taken from children with gastritis were in 52% H. pylori culture and PCR positive, while 18.1% PCR positive only. Similarly, specimens taken from children with duodenal ulcer were in 50% H. pylori culture and PCR positive, while 12.5% PCR positive only. Fifty one (70.8%) from 72 strains of H. pylori were Cag A positive. Molecular typing of the strains isolated during first and follow-up endoscopy allowed the differentiation between reinfection or new infection and coinfection. It was shown that RAPD typing had better discrimination power in comparison to PCR--RFLP method.
Base Sequence↗
The stimulation and inhibition of T cell proliferation by Helicobacter pylori components.
The purified T cells from peripheral blood of healthy human volunteers, seronegative for anti-Helicobacter pylori antibody were stimulated in cultures with live or heat-killed H. pylori rods or with bacterial sialic acid-specific surface haemagglutinin (sHA), a crude surface (SF) or cytoplasmic (CF) fractions. It is demonstrated that H. pylori bacteria contain both stimulatory and inhibitory components for T cells of healthy individuals. The sHA as well as SF (5-20 micrograms) induced the proliferative response of T lymphocytes. By contrast, CF inhibited in dose dependent manner, the proliferation of T cells in the cultures stimulated with H. pylori bacteria or PHA. The result suggest that in vivo, a dominance of activation or immunosuppression could depend on the concentration of the bacteria and their products in infective foci.
Adult↗
Frontiers in Helicobacter pylori research: pathogenesis, host response, vaccine development and new therapeutic approaches.
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Animals↗
Cell surface properties of Acinetobacter baumannii.
Cell surface properties of 78 strains of Acinetobacter baumannii of different origin (lower respiratory tract, wound, blood and environment) were investigated. The bacterial adhesion to collagen, fibronectin, fibrinogen and vitronectin was detected by particle agglutination assays. Salt aggregation tests were used to determine the cell surface hydrophobicity of isolated A. baumannii strains. We found that A. baumannii strains originating from patients with wound infection and bacteraemia showed significantly lower aggregative properties compared to respiratory and environmental strains. Electron microscopic investigations revealed more fimbriated bacterial cells among the highly aggregative A. baumannii strains. This study demonstrates that the investigated A. baumannii strains can be divided into two different groups according to their cell surface properties and source of isolation, whereas the majority of strains, from the lower respiratory tract and the hospital environment expressed strong adhesive properties.
Acinetobacter↗
Isolation and characterisation of a vitronectin-binding surface protein from Staphylococcus aureus.
In a previous study we demonstrated that cells of Staphylococcus aureus strain V8 bind 125I-labelled vitronectin in a receptor-ligand type of interaction, and a protein having a molecular mass of 60 kDa was identified as a putative high-affinity staphylococcal vitronectin-binding protein (Liang, O.D. et al. (1993) Biochim. Biophys. Acta 1225, 57-63). In the present communication we report on the isolation and preliminary characterisation of the 60 kDa vitronectin-binding protein. The bacterial cell surface proteins were released by stirring bacteria with 1 M LiCl at 37 degrees C for 2 h and separated on an FPLC Mono-Q column with a gradient of 0-0.5 M NaCl in 20 mM Tris buffer at pH 9.0. Fractions containing vitronectin-binding activity, assayed on microtiter plates with immobilised human vitronectin, were collected and SDS-PAGE analysis showed the content to be a single protein band at the 60 kDa position. In Western blot experiments the protein transblotted onto nitrocellulose membranes could bind soluble vitronectin. Its amino-terminal amino acid sequences showed a striking similarity with those of a 60 kDa heparan sulfate-binding protein from the same staphylococcal strain (Liang, O.D. et al. (1992) Infect. Immun. 60, 899-906), suggesting that they are identical molecules. This was supported by ligand blotting experiments where both vitronectin and heparan sulfate were shown to bind to the same protein band in parallel strips.
Amino Acid Sequence↗
[Gastrointestinal microorganisms may cause cancer. Research for a new pharmacological treatment is under way].
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Helicobacter Infections↗
Cell-surface properties of the food- and water-borne pathogen Aeromonas hydrophila when stored in buffered saline solutions.
Aeromonas hydrophila, a ubiquitous inhabitant of aquatic environments, commonly expresses several cell-surface properties that may contribute to virulence. Since many aquatic microorganisms in hostile environments can withstand starvation conditions for long periods, we examined the effect of storage under nutrient-poor conditions on the expression of cell-surface properties of this pathogen. Phenotypes studied were: (1) cell-surface hydrophobicity and charge, and (2) the ability to bind connective-tissue proteins and lactoferrin. Our results suggest that the response of A. hydrophila to nutrient-poor conditions is regimen specific. Generally, A. hydrophila cells became more hydrophobic and significantly increased their ability to bind the iron-binding glycoprotein lactoferrin when the bacterium was stored under nutrient-poor conditions; however, under these conditions, the cells seemed to lose their ability to bind connective-tissue proteins.
Aeromonas hydrophila↗