Binding of extracellular matrix proteins by microbes.
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Candida yeasts are frequently isolated from patients with continuous ambulatory peritoneal dialysis peritonitis or other biomaterial-associated infections. The mouse model of candidal peritonitis was used to study the interaction of Candida cells with end-point attached heparinized polyethylene (H-PE) and with polymorphonuclear leukocytes (PMNs) or macrophages (M phi). Two Candida strains differing in cell surface hydrophobicity and in expression of fibronectin (Fn) binding were used for the study. Cells of both Candida strains adhered at higher numbers to H-PE surfaces preadsorbed with Fn or with human dialysis fluid (HDF) than to non-modified H-PE, supporting a role of Fn in mediating adhesion. C. albicans 4016 cells expressing low hydrophobicity and low binding of soluble Fn demonstrated stronger adhesion to PMNs than the more hydrophobic C. albicans 3248 yeasts, which express high binding of soluble Fn. However, C. albicans 4016 cells were more resistant to phagocytic killing and were hardly eradicated in intraperitoneally infected mice. The animals depleted in PMNs by treatment with CY were neither able to eradicate C. albicans 3248 (rapidly eliminated by normal mice) nor C. albicans 4016 yeasts (with a tendency to persist in the tissues of normal mice).
The initial adhesion of microbes to tissue and solid surfaces can be mediated by hydrophobic interaction. Expression of microbial cell surface hydrophobicity (CSH) is influenced by growth conditions, and often best expressed after growth under nutrient-poor conditions, or "starvation". In the present study, the CSH of 133 strains of Enterobacteriaceae, Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus faecalis, group A streptococcus, Pseudomonas aeruginosa, Clostridium perfringens, Bacteroides fragilis, Peptococcus magnus, and of 8 Candida albicans strains was measured by the salt aggregation test after growth on hematin agar in a 5% CO2 atmosphere, or under anaerobiosis. Cells of all but 8 strains expressed pronounced or moderate CSH, i.e., they aggregated in 0.01-2 M ammonium sulfate. When the agar surface was covered by human serum (diluted 1:5) to mimic growth conditions in a wound, 94 strains expressed higher CSH, and 44 strains the same CSH as after growth without serum. The CSH of 12 strains of different species was measured after growth on blood, hematin and PDM agar, with or without serum, and in an aerobic or a 5% CO2 atmosphere. The highest CSH was expressed after growth in 5% CO2 with serum, and the lowest growth after on blood agar in aerobic atmosphere. Identical results were obtained with native and heat-inactivated (56 C, 20 min) serum. The reduced surface tension obtained in 5% CO2, as well as yet unidentified serum factors, promotes expression of CSH.
Rabbits were immunised with stage 1 and stage 2 soluble haemagglutinins (sHA) of Helicobacter pylori strain NCTC 11637 and with rabbit erythrocytes coated with stage 1 sHA. After adsorption of stage 1 sHA on erythrocytes, SDS-PAGE analysis showed that 4 major protein bands were removed from the preparation. The anti-sHA coated erythrocyte serum had the highest HA inhibition titre of 16. Crossed immunoelectrophoresis of the stage 1 sHA, against stage 1 and 2 antisera showed multiple precipitin arcs; however, the anti-sHA coated erythrocyte serum produced only two arcs. One arc produced by the anti-stage 2 serum was absent with the anti-stage 1 serum. This arc could have been produced against a 20 kDa polypeptide which was absent in the stage 1 sHA. The other arc was stronger when compared with that produced by anti-stage 1 serum. These two arcs corresponded to the two arcs produced by the anti-sHA coated erythrocyte serum, which had the highest inhibition titre. The two arcs were markedly reduced in crossed immunoelectrophoresis with an adsorbed stage 1 sHA preparation, which indicates that these arcs were produced against the sHAs.
Adhesion of staphylococcal cells to polyethylene with end point-attached heparin was quantified by bioluminescence. Staphylococcus epidermidis 3380 and the slime-producing S. epidermidis RP12 adhered to the highest extent, and S. lugdunensis 2342 to the least extent. Preincubation of the polymer with dialysis fluid reduced adhesion of S. epidermidis 3380 and RP12 but enhanced that of S. aureus, and preadsorption of the surface with fibronectin decreased subsequent adhesion of S. epidermidis and S. haemolyticus strains. When staphylococci were grown in the presence of a biomaterial their ability to activate peritoneal cells was decreased. The bactericidal activity was impaired, whereas ingestion of opsonized coagulase-negative staphylococci (CNS) strains was unaffected. With S. epidermidis RP12 the presence of biomaterial did not influence either phagocytosis or bactericidal effect of peritoneal cells. After intra-peritoneal challenge with staphylococcal strains, the organ uptake of S. aureus Cowan 1 was increased in normal mice whereas immunosuppressed mice died. CNS strains increased mainly in the peritoneal cavity of immunosuppressed mice. The uptake of bacteria in liver and kidneys was increased with S. epidermidis 3380, S. lugdunensis 2343 and S. schleiferi 667-88. Generally, CNS strains persisted in the peritoneal cavity of both normal and immunosuppressed mice. These data indicate that host defense mechanisms, mainly polymorphonuclear neutrophils, fail to eliminate CNS infections in the peritoneum, and that initial adhesion to an implanted biomaterial may be of lesser importance in the peritoneal cavity than in e.g. catheter-associated infections. There are strain-specific virulence factors of bacteria, and slime producing strains evade the host defense mechanisms more efficiently than non-slime producing strains.
Escherichia coli strains isolated from patients with colonic disorders (n = 27) and strains isolated from the rectal mucosa of healthy subjects (n = 24) were compared with respect to expression of cell surface hydrophobicity, carriage of intestinal virulence factors, adhesion to tissue culture cells, and expression of binding of extracellular matrix proteins and plasma proteins. Strains isolated from patients with colonic disease did not express a more hydrophobic cell surface than strains from healthy subjects. Few strains from both groups carried genes encoding for recognised virulence factors of E coli. Only one strain, carrying the eae gene induced actin polymerisation in tissue culture cells. Strains from patients with colonic diseases adhered to HT29 cells, which are of intestinal origin, to a higher extent than E coli from healthy subjects. Significantly more strains from patients with colonic disorders than E coli from healthy subjects expressed binding of fibronectin, collagens, laminin, vitronectin, plasminogen, throbospondin, and fibrinogen. Expression of binding of these proteins may influence the pathogenesis of colonic disease by mediating binding to ulcerated tissue, preventing complement induced lysis of bacteria and by exerting proteolytic activity. There was no correlation between serotype, expression of cell surface hydrophobicity, and binding of extracellular matrix and plasma proteins.
BACKGROUND: Antineutrophil cytoplasmic antibodies (ANCA) have recently been demonstrated in the sera of patients with inflammatory bowel disease (IBD). METHODS: The presence of ANCA was studied in 107 sera obtained during 1 year from 48 patients with a first attack of IBD and in 33 such sera from 19 patients with infectious or infectious-type colitis (non-relapsing colitis (NRC)). RESULTS: In 65% (31 of 48) of the IBD patients positive immunofluorescence reactivity against granulocytes was observed, compared with in 5% of the NRC patients. No significant difference in granulocyte reactivity was found either between patients with colonic Crohn's disease and those with ulcerative colitis or between active and inactive phases of the disease. Most of the sera showed a perinuclear immunofluorescence staining pattern (68%), in contrast to the classical cytoplasmic staining pattern seen in Wegener's granulomatosis. In sera obtained at the first visit from the 31 IBD patients with positive granulocyte reactivity a hitherto unknown antibody against beta-glucuronidase was found in 42%, whereas in 45% the specificity was not identified. Other antibodies, rarely seen, were directed against myeloperoxidase, lactoferrin, elastase, and cathepsin G. No antibody directed against lysozyme was detected. CONCLUSIONS: Positive granulocyte reactivity practically excluded NRC and was seen in more than half of IBD patients. Antibodies against beta-glucuronidase were common, but still almost half of the antibodies remained unknown.
BACKGROUND: Biomaterials used for biliary drainage may potentially result in biomaterial-associated infections. METHODS: Foreign-body infection in the biliary tract was investigated in rats. Rubber drain pieces were implanted in the biliary tract in rats for 1-4 weeks, followed by challenges with 10(2) to 10(4) colony-forming units (cfu) Escherichia coli injected into the common bile duct. The rate of infection was calculated, the bacterial growth in the biliary tract was observed over 72 h after challenges, and the opsonic activity in bile and in sera was assessed. RESULTS: In the group with drain material, inocula as small as 10(2) cfu produced persisting infection in the common bile duct in 90% of animals, whereas the same number of E. coli infected only 30% of rats in the control and sham implantation groups (p < 0.01, chi-square test). Complement-mediated opsonic activity in bile of animals with implanted drain pieces gradually decreased with time, whereas opsonic activity in sera from the same animals remained unchanged. CONCLUSIONS: Implants in the biliary tract impair local host defense, resulting in an increased susceptibility to microbial infection.
Human serum albumin (HSA), bovine serum albumin (BSA) and human IgG were immobilized on latex beads to detect cell surface components of Helicobacter pylori binding to BSA, HSA, and IgG by a particle agglutination assay (PAA). In a total of 32 H. pylori strains tested, 16 strains interacted with BSA and 12 strains with HSA; 24 strains expressed binding of human IgG. The specificity of the agglutination reaction was studied by a particle agglutination inhibition assay performed by pre-incubating bacterial cell suspensions in buffers containing homologous proteins, unrelated glycoproteins and a number of common monosaccharides. Treatment of H. pylori cells with heat and proteolytic enzymes abolished binding to microbeads with immobilized IgG and albumin. IgG-binding surface components from cells of H. pylori strain CCUG 17875 were effectively extracted by incubating a cell suspension with 10 mM EDTA, 0.015 M sodium phosphate buffer (pH 7.2), and by washing H. pylori cells with distilled water. However, attempts to extract a fraction rich in albumin-binding components were unsuccessful. We conclude that cells of various H. pylori strains express commonly IgG-binding proteins, and that albumin-binding is probably mediated by non-specific hydrophobic interactions.
A mouse model of peritoneal staphylococcal infection in mice implanted with heparinized polyethylene (H-PE) was used in this study. The binding of staphylococci and fibronectin (Fn) to biomaterial surface was estimated in vitro and in vivo. The activity of phagocytes from the animals non-implanted or implanted for 7 days or 2 months with H-PE was determined on the basis of bactericidal activity, nitric oxide (NO) and Fn production.
The adherence of clinical isolates of staphylococci to surfaces immobilized with various glycosaminoglycans (GAGs) was studied. In general, cells of strains of coagulase-negative (CNS) staphylococci showed a greater adherence to polyethylene surfaces than did cells of Staphylococcus aureus, as studied by bioluminescence. When the surface was heparinized, the adherence of staphylococcal cells decreased, but CNS cells still adhered in greater numbers than did cells of S. aureus. The adherence of CNS to serum-coated heparinized surfaces was of the same magnitude, or increased compared with nonheparinized surfaces. When the surfaces were preadsorbed with different proteins with known heparin-binding domains, i.e., vitronectin, fibronectin, laminin, or collagen, the S. epidermidis cells showed higher binding to heparinized surfaces than to nonheparinized ones, and also in greater numbers than did other staphylococcal cells. Different CNS strains showed a greater ability to agglutinate polystyrene beads immobilized with heparin than did S. aureus. The adherence of S. epidermidis strain 3380 to polyethylene coated with various GAGs such as heparin and chondroitin, dextran, dermatan, and heparan sulfate was shown to be pH-dependent, with the highest adherence at pH 7.2. This may indicate that CNS have the ability to bind to other domains of host proteins when they are adsorbed to heparinized surfaces, versus to nonheparinized ones.
The aim of the present study was to determine the influence of splenectomy on the incidence of enteric bacterial translocation in rats with intraperitoneal rubber drain implantation. Male Sprague-Dawley rats (250-300 g) underwent splenectomy or sham operation 7 days prior to the intraperitoneal implantation of rubber drain fragments (7 cm2). Bacterial translocation was measured 2 days after rubber drain implantation. The incidence of bacterial translocation was significantly higher in the group with intraperitoneal rubber drain implantation plus sham splenectomy than in the groups with sham splenectomy plus sham implantation, splenectomy plus sham implantation or splenectomy plus rubber drain implantation. An increase in ileal permeability of 125I-human serum albumin was induced by intraperitoneal rubber drain implantation and ameliorated by splenectomy. Splenectomy also improved the impaired intestinal motility induced by intraperitoneal rubber drain implantation. Histological examination revealed a preserved normal mucosal architecture in splenectomized rats. Thus, splenectomy reduced the rate of enteric bacterial translocation induced by intraperitoneal biomaterial implantation.
Collagen type-I-binding proteins of Lactobacillus reuteri NCIB 11951 were purified. The cell surface proteins were affinity purified on collagen Sepharose and eluted with an NaCl gradient. Two protein bands were eluted from the column (29 kDa and 31 kDa), and both bound radio-labeled collagen type I. Rabbit antisera raised against the 29 kDa and 31 kDa protein reacted with the affinity-purified proteins in a Western blot with whole-cell extract used as antigen. The N-terminal sequence of the 29-kDa and 31-kDa proteins demonstrated the closest homologies with internal sequences from an Escherichia coli trigger factor protein (TIG.ECOLI). Out of nine other lactobacilli, the antisera reacted only with the L. reuteri and not with the other species tested.
Protease treatment of cells of coagulase-negative staphylococci reduced the adhesion of bacteria to heparinized polyethylene preadsorbed with serum. Fibronectin (Fn), fibrinogen (Fg), vitronectin, complement factor C3c, plasminogen, laminin and to a low extent albumin were detected on tridodecylmethylammonium chloride (TDMAC)-heparinized polyvinyl chloride (PVC) catheters extirpated from the circulation of patients. Using a perfusion model we show that during the first hours of perfusion with human plasma, Fn and Vn dominate, whereas after 22 h of perfusion Fg is the dominant protein. Field emission scanning electron microscopy and atomic force microscopy studies on TDMAC-heparinized catheters as well as on end-point attached heparinized PVC catheters indicate that quantitatively more Fg than Fn is exposed on these surfaces after prolonged exposure (> 22 h) to human plasma.
A commercial biomedical poly(ether urethane), Pellethane 2363-80AE, was surface modified through the use of amphiphilic polymeric additives, and through surface grafting with poly(ethylene glycol), PEG. Two different amphiphilic polymers, Polymer C and Pluronic PE9400, were used as additives. Polymer C, a segmented polyurethane, was prepared from PEG1500, 4,4'-diphenylmethane diisocyanate and a C16-C18 monoglyceride chain extender. Pluronic PE9400 is a propylene oxide-ethylene oxide tri-block co-polymer obtained from BASF. Adsorption of human albumin and fibrinogen to the modified surfaces was studied by means of radiolabelled proteins. By contact angle measurements and X-ray photoelectron spectra the amphiphilic polymers were shown to accumulate at the polyurethane surfaces. Adsorption of fibrinogen, in particular, was significantly reduced by the amphiphilic additives to levels similar to those obtained for Pellethane surfaces grafted with PEG 20,000. In vitro clotting times for citrate-buffered blood in contact with the amphiphilic surfaces increased as compared with the unmodified ones.
Non-specific and specific mechanisms of adherence have been examined in two collections of methicillin-resistant Staphylococcus aureus (MRSA). Determination of hydrophobicity by salt aggregation, hydrophobicity indices and of adherence to the extra-cellular matrix proteins fibronectin, vitronectin, laminin and collagen type 1 have failed to reveal any correlation with phage-type, plasmid profile or antibiogram. Further, the strain collections, made over a period of years in two countries, differ markedly in their adherence characteristics; MRSA are heterogeneous in this respect. Such heterogeneity may explain the polarization of views on the epidemicity or 'virulence' of MRSA. With the exception of adherence to collagen a small group of methicillin sensitive S. aureus had characteristics intermediate between the two groups of MRSA.
Our investigation of 61 children with persistent diarrhoea and malnutrition (PDM) aimed to characterize in them the range of enteropathogenic E. coli. Age- and sex-matched control groups consisted of 42 healthy children and 16 children with marasmus but without diarrhoea. E. coli isolates from stool cultures were serotyped, examined for Vero cells cytotoxicity, tested for enterotoxin production (LT, ST, VTI, and VTII). Synthetic oligonucleotide probes were used to test for enteroinvasivity, EPEC adherence factor, and for EAggEC. Classical E. coli serotypes commonly associated with diarrhoea (O18, O26, O119, O126) were isolated from six of 60 (10%) children with PDM. Serotype O126 was isolated from two of 42 (4.8%) healthy children and serotype O119 from one of 16 (6%) marasmic controls. Testing for Vero toxin production was negative in all isolates. Classical ETEC were confirmed in four of 60 (ST 2; LT 2) cases of PDM; no ETEC were recovered from 58 control patients. EAggEC were identified in five children with PDM and in five healthy controls without diarrhoea or malnutrition. This controlled study has shown that, in The Gambia, E. coli carrying known virulence factors are prevalent but, with the exception of enterotoxigenic E. coli, the various forms of pathogenic E. coli do not seem to be important pathogens in children with persistent diarrhoea.
Biomaterial-associated infections are a problem in the use of endoprosthetic materials in the palliative treatment of malignant obstructive jaundice. Fibronectin has been reported to mediate adherence of bacteria to host tissue and biomaterials. Adsorption of fibronectin to rubber--representing material used for biliary drainage--and subsequent adherence of Escherichia coli strain PSS1 and E. coli strain NG7C (which binds to immobilised fibronectin) were investigated. Quantitative adsorption of fibronectin to rubber slices was studied with 125I-labelled, purified human plasma fibronectin. In buffer solutions, fibronectin showed a high affinity for rubber slices. Adherence of the E. coli strains to uncoated rubber slices was similar and was significantly inhibited by the presence of plasma components and bile. Adherence of E. coli PSS1 to fibronectin-coated slices was poor. In contrast, E. coli NG7C adhered efficiently to coated slices in proportion to the amount of adsorbed fibronectin; adherence was not reduced by the presence of albumin or bile, or the fibronectin-binding ligands gelatin, heparin and fibrinogen. However, pre-digestion of coated slices with trypsin significantly reduced adherence.