Binding of extracellular matrix proteins by microbes

Vancomycin-loaded electrospun polycaprolactone/nano-hydroxyapatite membrane for the treatment of blood infections

Nowadays, because of the resistance of bacteria to antibiotics, researchers are trying to make new antibiotics or sometimes even bring them back into the treatment cycle so that they could eliminate the bacteria's resistance. On the other hand, the use of nanofibers has become widespread in many fields for their unique properties and convenient design. The present study focuses on the production of hydrophobic nanofibers to absorb the bacteria and their toxins from the bloodstream that contains the infection. Many bacterial surfaces have hydrophobic surfactant properties due to hydrophobic surface protein. According to the principle of binding two hydrophobic molecules to each other in an aqueous medium, the nanofibers are designed to physically absorb the bacteria. The use of antibiotics in the study can remove some unattached bacteria. In addition, using nanofiber manufacturing techniques can reduce the resistance of bacteria to antibiotics. The construction of the desired membrane can be used in subsequent studies as a replacement membrane for dialysis filters.

Ecological fitness and strategies of adaptation of Bartonella species to their hosts and vectors

Bartonella spp. are facultative intracellular bacteria that cause characteristic hostrestricted hemotropic infections in mammals and are typically transmitted by blood-sucking arthropods. In the mammalian reservoir, these bacteria initially infect a yet unrecognized primary niche, which seeds organisms into the blood stream leading to the establishment of a long-lasting intra-erythrocytic bacteremia as the hall-mark of infection. Bacterial type IV secretion systems, which are supra-molecular transporters ancestrally related to bacterial conjugation systems, represent crucial pathogenicity factors that have contributed to a radial expansion of the Bartonella lineage in nature by facilitating adaptation to unique mammalian hosts. On the molecular level, the type IV secretion system VirB/VirD4 is known to translocate a cocktail of different effector proteins into host cells, which subvert multiple cellular functions to the benefit of the infecting pathogen. Furthermore, bacterial adhesins mediate a critical, early step in the pathogenesis of the bartonellae by binding to extracellular matrix components of host cells, which leads to firm bacterial adhesion to the cell surface as a prerequisite for the efficient translocation of type IV secretion effector proteins. The best-studied adhesins in bartonellae are the orthologous trimeric autotransporter adhesins, BadA in Bartonella henselae and the Vomp family in Bartonella quintana. Genetic diversity and strain variability also appear to enhance the ability of bartonellae to invade not only specific reservoir hosts, but also accidental hosts, as shown for B. henselae. Bartonellae have been identified in many different blood-sucking arthropods, in which they are typically found to cause extracellular infections of the mid-gut epithelium. Adaptation to specific vectors and reservoirs seems to be a common strategy of bartonellae for transmission and host diversity. However, knowledge regarding arthropod specificity/restriction, the mode of transmission, and the bacterial factors involved in arthropod infection and transmission is still limited.

Binding of Bartonella henselae to extracellular molecules: Identification of potential adhesins

Bartonella henselae, the etiologic agent of cat scratch disease, bacillary angiomatosis and other clinical syndromes initiates infection through a trauma or wound to the skin suggesting involvement of extracellular matrix molecules. We have demonstrated in this study that B. henselae bound strongly fibronectin, collagen IX and X, but comparatively less laminin and collagen IV. B. henselae bound primarily the N- and C-terminal heparin (Hep-1 and Hep-2, respectively) and the gelatin-binding domains of fibronectin (Fn) but not the cell-binding domain. Binding to the Hep-binding domain was significantly inhibited by Hep suggesting common binding sites on the Fn molecule. Furthermore, glycosaminoglycans-mediated binding of B. henselae to soluble Fn showed that Hep but not dextran sulfate inhibited the bacterium binding to Fn. Unlike Fn, B. henselae bound strongly vitronectin only in the presence of Hep or dextran sulfate. Also, the binding of B. henselae to host cells could be inhibited by anti-B. henselae surface-reactive antibodies, the exogenous Fn or the anti-Fn polyclonal antibodies. Ligand blots, batch affinity purification and MALDI-TOF peptide fingerprinting identified B. henselae Pap31, Omp43 and Omp89 as the three major putative Fn-binding proteins (FnBPs) in B. henselae outer membrane proteins. We hypothesized that B. henselae wound associated infections involved interactions with extracellular matrix molecules. Taken together, the above data suggest that interactions between B. henselae and ECM molecules such as Fn may play an important role in the bacterium adherence to and invasion of host cells.

A family of variably expressed outer-membrane proteins (Vomp) mediates adhesion and autoaggregation in Bartonella quintana

Bartonella species are fastidious, Gram-negative human pathogens that can persist in the host bloodstream for years and bind to and invade several types of host cells. For many pathogens, adhesion to host cells and extracellular matrix (ECM) components is a critical virulence determinant. Bacteria often vary expression of surface adhesins by phase or antigenic variation to subvert the host immune response and permit adaptive interaction with different host structures. We developed a macaque animal model for Bartonella quintana infection to detect changes in bacterial outer-membrane proteins (OMP) during prolonged bloodstream infection. We identified a gene family encoding four highly conserved, 100-kDa, variably expressed OMP (Vomp), two of which function as adhesins. The variable expression of Vomp family members appears to be mediated by deletion of one or more vomp genes during chronic bloodstream infection. vomp deletion was observed also in isolates from humans with chronic B. quintana infection. The Vomp are closely related to the afimbrial adhesin, YadA, a virulence factor of Yersinia enterocolitica. The surface-expressed Vomp contain conserved structural features of YadA, including collagen-binding motifs. We demonstrate that the B. quintana Vomp are multifunctional OMP involved in binding to collagen and autoaggregation: VompC confers the ability to bind collagen IV, and VompA is necessary and sufficient for autoaggregation. The B. quintana Vomp are members of the newly recognized family of YadA-like trimeric autotransporters; the Vomp constitute a multigene family, they are variably expressed, and different virulence properties are attributable to individual Vomp family members.

Binding of extracellular matrix molecules by probiotic bacteria

AIMS

The aim of this study was to investigate extracellular matrix (ECM) and mucin binding of selected bacterial isolates with probiotic features in comparison with commercially used probiotic bacteria.

METHODS AND RESULTS

ECM molecules were immobilized in microtitre plates (mucin and fetuin) or on the surface of latex beads. Porcine mucin was bound by all 13 probiotic strains tested with important inter-strain differences; however, fetuin binding was similar (weak) for all 14 strains tested. Strongly positive (three) binding of bovine fibrinogen was expressed by strains from fermented food (Lactobacillus rhamnosus GG, L. casei Shirota and L. johnsonii La1) as well as by L. casei L.c., Lactobacillus sp. 2I3 and by L. plantarum LP. The other strains expressed moderate (2) or weakly positive (1) binding of bovine fibrinogen. Strongly positive (3) binding of porcine fibronectin was observed only with two strains; however, all other strains also bound this molecule. Bovine lactoferrin was bound to a higher extent than transferrins.

SIGNIFICANCE AND IMPACT OF THE STUDY

Some animal strains (at least L. casei L.c. and Lactobacillus sp. 2I3) are comparable with the commercially used strains with respect to their ECM binding ability. As this feature is important for probiotic bacteria to be able to colonize intestine, these strains should be considered for their wider use in fermented feed (or probiotic preparations) for animals.

Factors involved in the early pathogenesis of bovine Staphylococcus aureus mastitis with emphasis on bacterial adhesion and invasion. A review

Staphylococcus aureus is the most important and prevalent contagious mammary pathogen; it causes clinical and subclinical intramammary infection with serious economic loss and herd management problems in dairy cows. In vitro studies have shown that Staphylococcus aureus adheres to mammary epithelial cells and extracellular matrix components and invades into mammary epithelial as well as other mammary cells. Staphylococcus aureus strains from intramammary infection produce several cell surface-associated and extracellular secretory products. The exact pathogenic roles of most of the products and their effects on adhesion and invasion are not well evaluated. It is also known that mammary epithelial cell-associated molecules and extracellular matrix components interact with S. aureus during the pathogenesis of mastitis, but their roles on adhesion and invasion have not been characterized. The adhesion of S. aureus to epithelial cells may involve non-specific physicochemical interactions and/or specific interactions between bacterial cell-associated ligands and host cell surface receptors. In vitro adhesion depends on the S. aureus strain, the growth phase of the bacteria, the growth medium and the origin of the epithelial cells. Adhesion is hypothesized to be a prerequisite and crucial early step for mammary gland infection. Staphylococcus aureus invades mammary epithelial cells. It also invades other cells such as endothelial cells and fibroblasts. Bacteria are found enclosed in membrane bound vacuoles in the cytoplasm of mammary epithelial cells. Recent observations indicate that S. aureus escapes from the phagosome into the cytoplasm and induces apoptosis. The invasion into mammary epithelial cells may occur through an endocytic process that requires involvement of elements of the cytoskeleton or by direct binding of bacteria to epithelial cells through a process mediated by specific receptors that needs de novo protein synthesis by both cells. Thus, the recurrent subclinical infection may result from this intracellular existence of bacteria that are protected from host defenses and effects of antibiotics. This review emphasizes on recent findings on S. aureus adhesion to mammary epithelial cells and extracellular matrix components and invasion into mammary epithelial cells.

Functional variation of the antigen I/II surface protein in Streptococcus mutans and Streptococcus intermedius

Although Streptococcus intermedius and Streptococcus mutans are regarded as members of the commensal microflora of the body, S. intermedius is often associated with deep-seated purulent infections, whereas S. mutans is frequently associated with dental caries. In this study, we investigated the roles of the S. mutans and S. intermedius antigen I/II proteins in adhesion and modulation of cell surface characteristics. By using isogenic mutants, we show that the antigen I/II in S. mutans, but not in S. intermedius, was involved in adhesion to a salivary film under flowing conditions, as well as in binding to rat collagen type I. Binding to human fibronectin was a common function associated with the S. mutans and S. intermedius antigen I/II. Adhesion of S. mutans or S. intermedius to human collagen types I or IV was negligible. Hydrophobicity, as measured by water contact angles, and zeta potentials were unaltered in the S. intermedius mutant. The S. mutans isogenic mutants, on the other hand, exhibited more positive zeta potentials at physiological pH values than did the wild type. The results indicate common and species-specific roles for the antigen I/II in mediating the attachment of S. mutans and S. intermedius to host components and in determining cell surface properties.

Binding of extracellular matrix proteins by lactobacilli

Ten gut and ten vaginal Lactobacillus strains were investigated for their ability to bind type I collagen (Cn-I) and four selected gut lactobacilli were investigated for their binding to other extracellular matrix (ECM) molecules. Immobilized Cn-I (100 mg/L) in wells of microtitre plates was bound by all 10 autoaggregating vaginal strains and by 3 strains of gut lactobacilli from piglets in the range of A570 readings 0.114-1.806. L. acidophilus strain SV31 was much more adherent than the rest of strains. All four gut lactobacilli tested for binding to other ECM molecules displayed good binding to porcine fibronectin and heparin and some of them bound weakly to fetuin and porcine mucin. No binding of these strains was observed to bovine mucin, bovine fibrinogen and bovine lactoferrin.

Adhesion of Streptococcus gallolyticus strains to extracellular matrix proteins

Fourteen pigeon Streptococcus gallolyticus strains of differing virulence, were tested for their ability to adhere to immobilised fibronectin, collagen types I, III and IV. Eight, 2 and 13 strains were able to bind fibronectin, collagen types III and IV, respectively. None of the strains adhered to collagen type I. Heat treatment, proteolytic digestion or periodate treatment reduced the binding of S. gallolyticus to fibronectin and collagen type IV, suggesting that surface receptors contain proteins and carbohydrates. Although binding to these extracellular matrix proteins can play a role in the pathogenesis of streptococcosis in pigeons, binding properties could not be related to virulence, indicating that other factors determine differences in virulence among pigeon S. gallolyticus strains. Adhesion to collagen type IV may account in part for the distribution pattern of the lesions observed in naturally and experimentally infected pigeons.

Binding of extracellular matrix proteins by animal strains of staphylococcal species

All 81 strains of Staphylococcus species isolated mainly from animals express high surface hydrophobicity as a stable property upon cultivation on blood agar. Bovine lactoferrin, human vitronectin, human fibronectin, heparin, human and bovine serum albumin were immobilized on latex beads to detect protein-binding cell surface components of 67 non-autoaggregating staphylococcal strains by a particle agglutination assay. Bovine lactoferrin was bound well by 22 strains (3 or 2) while 15 strains reacted weakly (1) and 30 did not react (0) with the lactoferrin-coated latex beads. The particle agglutination assay showed similar differences among staphylococcal strains in binding other proteins with the exception of human and bovine serum albumins for which 66 of 67 strains were negative (0). The specificity of the agglutination reaction was confirmed by a particle agglutination inhibition assay by preincubating bacterial cells with the protein (lactoferrin, vitronectin, etc.) used subsequently in particle agglutination assay. Autoaggregating strains together with some non-autoaggregating strains were selected for microtitre plate assay. According to absorbance at 570 nm, 14 strains were classified as non-adherent, 16 strains as weakly adherent and 18 strains as strongly adherent to bovine lactoferrin in microtitre plate assays. A direct correlation was found between the absorbance values at 570 nm of microtitre plate binding assay and test values obtained in particle agglutination assay. Binding of bovine lactoferrin to 81 staphylococcal strains as well as of human vitronectin and human fibronectin to a selected number of these strains was studied with radiolabeled (125I-labeled) proteins. Radiolabeled bovine lactoferrin was bound common by all except four strains (7 to 39%). Staphylococcal strains isolated from diseased pigs commonly bound 125I-labeled vitronectin (21 to 42% of the vitronectin added). Binding of vitronectin and lactoferrin was efficiently inhibited by preincubating of staphylococcal cells with sulphated carbohydrate compounds as heparin, dextran sulphate and fucoidan, but not by other non-sulphated highly charged glycoconjugates such as hyaluronic acid.

Specific interactions between Porphyromonas gingivalis fimbriae and human extracellular matrix proteins

The interactions of the extracellular matrix (ECM) proteins (laminin, elastin, fibronectin, type I collagen, thrombospondin and vitronectin) with the fimbriae of Porphyromonas gingivalis were analyzed based on surface plasmon resonance (SPR) spectroscopy using a biomolecular interaction analyzing system (BIAcore). The BIAcore profiles demonstrated that fimbriae specifically bound to all of the ECM proteins with significant association constants (Ka). Vitronectin showed the highest affinity to fimbriae (Ka = 3.79 x 10(6) M-1), while the affinity of laminin was lowest (Ka = 2.15 x 10(6) M-1). A synthetic peptide which is a potent inhibitor of fimbrial binding to salivary proteins was not significantly effective on the fimbrial interactions with the ECM proteins. Using polystyrene microtiter plates revealed that P. gingivalis fimbriae bound markedly to immobilized fibronectin and type I collagen, while the interaction of fimbriae with the other ECM proteins was not clearly demonstrated. These results suggest that interactions between fimbriae and the ECM proteins occur with specific affinities which are not mediated by mechanisms identical to those of salivary proteins. It was also shown that SPR spectroscopy is a useful method to analyze these specific interactions.

Molecular interactions of Porphyromonas gingivalis fimbriae with host proteins: kinetic analyses based on surface plasmon resonance

Fimbriae of Porphyromonas gingivalis are thought to play an important role in the colonization and invasion of periodontal tissues. In this study, we analyzed the interactions of P. gingivalis fimbriae with human hemoglobin, fibrinogen, and salivary components (i.e., proline-rich protein [PRP], proline-rich glycoprotein [PRG], and statherin) based on surface plasmon resonance (SPR) spectroscopy with a biomolecular interaction analyzing system (BIAcore). The real-time observation showed that the fimbriae interacted more quickly with hemoglobin and PRG than with other proteins and more intensely with fibrinogen. The significant association constant (ka) values obtained by BIAcore demonstrated that the interactions between fimbriae and these host proteins are specific. These estimated Ka values were not too different; however, the Ka values for hemoglobin (2.43 x 10(6)) and fibrinogen (2.16 x 10(6)) were statistically greater than those for the salivary proteins (1.48 x 10(6) to 1.63 x 10(6)). The Ka value of anti-fimbriae immunoglobulin G for fimbriae was estimated to be 1. 22 x 10(7), which was 6.55-fold higher than the mean Ka value of the host proteins. Peptide PRP-C, a potent inhibitor of PRP-fimbriae interaction, dramatically inhibited fimbrial association to PRP and PRG and was also inhibitory against other host proteins by BIAcore. The binding of fimbriae to these proteins was also evaluated by other methods with hydroxyapatite beads or polystyrene microtiter plates. The estimated binding abilities differed considerably, depending on the assay method that was used. It was noted that the binding capacity of PRP was strongly diminished by immobilization on a polystyrene surface. Taken together, these findings suggest that P. gingivalis fimbriae possess a strong ability to interact with the host proteins which promote bacterial adherence to the oral cavity and that SPR spectroscopy is a useful method for analyzing specific protein-fimbriae interactions.

Binding of Haemophilus ducreyi to extracellular matrix proteins

We developed an enzyme-linked immunosorbent assay-based assay to assess Haemophilus ducreyi binding to extracellular matrix (ECM) proteins. H. ducreyi 35000HP bound to fibronectin, laminin, and type I and III collagen but not to type IV, V, or VI collagen or elastin. Isogenic strains with mutations in ftpA or losB bound as well as the parent, suggesting that neither pili nor full-length lipooligosaccharide is required for H. ducreyi to bind to ECM proteins.

Isolation and characterization of two proteins from Moraxella catarrhalis that bear a common epitope

The UspA1 and UspA2 proteins of Moraxella catarrhalis are potential vaccine candidates for preventing disease caused by this organism. We have characterized both proteins and evaluated their vaccine potential using both in vitro and in vivo assays. Both proteins were purified from the O35E isolate by Triton X-100 extraction, followed by ion-exchange and hydroxyapatite chromatography. Analysis of the sequences of internal peptides, prepared by enzymatic and chemical cleavage of the proteins, revealed that UspA1 and UspA2 exhibited distinct structural differences but shared a common sequence including an epitope recognized by the monoclonal antibody 17C7. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), purified UspA1 exhibited a molecular weight of approximately 350, 000 when unheated and a molecular weight of 100,000 after being heated for 10 min at 100 degreesC. In contrast, purified UspA2 exhibited an apparent molecular weight of 240,000 by SDS-PAGE that did not change with the length of time of heating. Their sizes as determined by gel filtration were 1,150,000 and 830,000 for UspA1 and UspA2, respectively. Preliminary results indicate the proteins have separate functions in bacterial pathogenesis. Purified UspA1 was found to bind HEp-2 cells, and sera against UspA1, but not against UspA2, blocked binding of the O35E isolate to the HEp-2 cells. UspA1 also bound fibronectin and appears to have a role in bacterial attachment. Purified UspA2, however, did not bind fibronectin but had an affinity for vitronectin. Both proteins elicited bactericidal antibodies in mice to homologous and heterologous disease isolates. Finally, mice immunized with each of the proteins, followed by pulmonary challenge with either the homologous or a heterologous isolate, cleared the bacteria more rapidly than mock-immunized mice. These results suggest that UspA1 and UspA2 serve different virulence functions and that both are promising vaccine candidates.

Binding of immobilized fibronectin by biliary drain isolates

Occlusion of biliary stents, as the result of bacterial adhesion and colonization onto biliary stents, still remains a major problem. Biliary proteins, such as fibronectin (Fn) and vitronectin (Vn), have been presumed to be involved in the process of bacterial adhesion to biliary biomaterial. In the present study, Fn binding by 5 strains of E. coli isolated from biliary drains or from bile was studied. All strains did not bind detectable amounts of soluble Fn but bound to immobilized plasma Fn. Adhesion of four strains of E. coli to ovalbumin was reduced by periodate treatment of ovalbumin, but adhesion to Fn was unaffected. Adhesion was inhibited by mannose-containing saccharides, trypsin treatment of the protein, and protease treatment of the bacterial cells. Autoradiography showed that components of cell extracts from three E. coli strains bind 125I-Fn but not a 150 kD Fn fragment. The findings indicate that the adhesion of these bacteria to Fn is a protein-protein interaction, inhibited by D-mannose, and possibly mediated by fimbrial components.