N-acetylneuraminyllactose-binding fibrillar hemagglutinin of Campylobacter pylori: a putative colonization factor antigen

Construction of isogenic urease-negative mutants of Helicobacter pylori by allelic exchange

Isogenic urease-negative mutants of Helicobacter pylori were constructed by allelic replacement. A region of cloned H. pylori DNA containing the structural urease genes (ureA and ureB) was disrupted by insertion of a mini-Tn3-Km transposon. Electrotransformation of H. pylori cells with kanamycin-ureB-disrupted derivative plasmids resulted in isolation of kanamycin-resistant H. pylori transformants. Competence for electrotransformation appeared to be restricted to certain wild-type H. pylori isolates; only 1 isolate (of 10 tested) was consistently transformed. Two of the kanamycin-resistant H. pylori transformants were further studied and shown to be urease negative. Southern hybridization analyses demonstrated that the urease-negative mutants had been constructed by allelic exchange involving simultaneous replacement of the ureB gene with the kanamycin-ureB-disrupted copy and loss of the vector. Immunoblot studies of whole-cell extracts of the isogenic ureB mutants with anti-H. pylori sera indicated the absence of a polypeptide with an apparent molecular mass of 61 kDa; thus, the mutants no longer synthesized the UreB product. Generation of stable, genetically engineered urease mutants of H. pylori will be useful for addressing the role of urease in the pathogenesis of H. pylori infection.

The glycerolipid receptor for Helicobacter pylori (and exoenzyme S) is phosphatidylethanolamine

We have previously shown that Helicobacter pylori specifically binds to a glycerolipid species preferentially found in the antrum of the human stomach. We now show by high-pressure liquid chromatographic analysis that this species is a form of phosphatidylethanolamine and that H. pylori specifically binds to bona fide phosphatidylethanolamine as detected by a thin-layer chromatogram overlay procedure. Considerable variation in the binding of H. pylori to phosphatidylethanolamine from different sources was observed, however, suggesting the importance of the nature of the long-chain hydrophobic moiety. A similar binding specificity was shown by exoenzyme S from Pseudomonas aeruginosa, consistent with our hypothesis that that an exoenzyme S-like adhesin is responsible for the binding of H. pylori to its lipid receptors.

Urease-associated heat shock protein of Helicobacter pylori

Helicobacter pylori urease is an extracellular, cell-bound enzyme with a molecular weight of approximately 600,000 (600K enzyme) comprising six 66K and six 31K subunits. A 62K protein is closely associated with the H. pylori urease, both in crude preparations and after gel filtration; this protein can be removed from the urease by ion-exchange chromatography without inactivating the enzyme. We purified this urease-associated protein and determined its N-terminal amino acid sequence. The sequence is 80% homologous (identical plus conserved amino acid residues) to the Escherichia coli GroEL heat shock protein (HSP), 75% homologous to the human homolog, and 84% homologous to the HSP homolog found in species of Chlamydia. Thus, the 62K urease-associated protein of H. pylori belongs to the HSP60 family of stress proteins known as chaperonins. Evidently this protein, HSP62, participates in the extracellular assembly and/or protection of the urease against inactivation in the hostile environment of the stomach.

Adherence of Helicobacter pylori to HEp-2 cells

The adherence of 25 strains of Helicobacter pylori was evaluated in HEp-2 cells. These bacterial isolates, obtained from Chilean patients with gastric disorders, were also tested for haemagglutination of human red blood cells. Adherence of HEp-2 cells was expressed as a common property of all strains, irrespective of whether the cultures were grown on semi-solid or in liquid media. Previous reports that haemagglutinating activity was present in cells grown only on semi-solid media were confirmed. Adherence to HEp-2 cells was suppressed when bacterial cells were pretreated with homologous or heterologous whole human serum, containing specific antibodies of H. pylori. Adherence remained unaltered when bacterial cells were similarly treated with normal serum lacking specific antibodies. These observations imply that adhesions are expressed in vivo and suggest that an adherence mechanism, not depending on the expression of specific haemagglutinin antigen, operates for H. pylori.

Adherence and internalization of Helicobacter pylori by HEp-2 cells

Helicobacter pylori colonizes the mucous layer of the stomach and the surface of gastric mucous cells. Although H. pylori is not generally thought of as invasive, it has been observed in the lamina propria and within vacuoles in the cytoplasm of epithelial cells. The authors report that isolates of H. pylori can enter into the cytoplasm of tissue culture epithelial cell lines such as HEp-2 cells. Intracellular uptake of H. pylori by HEp-2 cells is rapid and appears to require both the N-acetylneuraminyllactose-binding adhesin and another factor present only in living bacteria. Uptake of H. pylori was inhibited by ammonium chloride and chloroquine at concentrations that did not effect either adherence or bacterial viability. Dansylcadaverine, an inhibitor of receptor clustering and internalization, also inhibited uptake but not adherence of H. pylori. Uptake was completely inhibited when H. pylori and HEp-2 cells were incubated at 4 degrees C under conditions that did not effect bacterial adherence. Cytochalasin B, an inhibitor of phagocytosis, did not inhibit uptake. It is concluded that H. pylori is internalized either by receptor-mediated endocytosis or by a closely related pathway.

Production of a conserved adhesin by the human gastroduodenal pathogen Helicobacter pylori

An adhesin protein with an approximate subunit molecular weight of 19,600 has been purified from the gastric pathogen Helicobacter pylori. The protein was loosely associated with the cell surface and was removed by gentle stirring or shearing. Released aggregates of the 19.6-kDa protein were removed from suspension by ultracentrifugation and separated from contaminating membranes by washing in 1.0% sodium dodecyl sulfate (SDS). The SDS-insoluble protein was purified further by Mono Q anion-exchange column chromatography. Electron microscopy of the purified adhesin demonstrated that it formed amorphous aggregates similar to the material attached to the bacterial cells and that the aggregates were morphologically distinct from typical fimbriae. Western blot (immunoblot) analysis with antiserum raised against the purified protein from one strain reacted with a protein with a similar subunit molecular weight present in all nine strains of H. pylori examined, but the protein was not present in other Helicobacter species examined. The N-terminal sequences of the 19.6-kDa protein purified from three different strains of H. pylori were identical for the first 28 amino acids, with the 10 amino-terminal residues showing limited sequence homology with the TcpA pilus protein of Vibrio cholerae. The H. pylori 19.6-kDa protein associated both with human and rabbit erythrocytes and with human buccal epithelial cells. Polystyrene microspheres coated with the protein agglutinated human, horse, and rabbit erythrocytes, suggesting that this protein species could mediate adhesion between H. pylori and eucaryotic cells. This ability to act as an adhesin may make this protein an important virulence factor for H. pylori and hence a potential target for a vaccine and therapy.

Cholesterol binding of Helicobacter pylori

H. pylori cells grown on cholesterol-free medium adsorb cholesterol from serum, egg yolk, and VDRL reagent. The binding of cholesterol does not influence the hydrophobicity of the cells. The haemagglutinating activity is slightly diminished. The cell-bound haemolytic activity is completely inhibited. The affinity of H. pylori for cholesterol probably acts as factor of chemotaxis and adherence.

Clustering of an outer membrane adhesin of Haemophilus parainfluenzae

Haemophilus parainfluenzae synthesizes an outer membrane protein adhesin which mediates binding to oral streptococci, salivary pellicle, and neuraminidase-treated erythrocytes. An indirect gold labeling technique and immunoelectron microscopy verified the location of this outer membrane protein. Further, a clustering of gold particles was observed in irregular patches at the cell surface.

Blocking of fimbria-mediated adherence of Haemophilus influenzae by sialyl gangliosides

The structure of the receptor for the fimbriae of Haemophilus influenzae on human oropharyngeal epithelial cells and erythrocytes was determined in inhibition experiments with various sugars, glycolipids, and glycoproteins. Of 30 monosaccharides and disaccharides at a concentration of 0.1 M and of 3 polysaccharides at a concentration of 1 mg/ml, none inhibited fimbria-specific adherence and hemagglutination. Inhibition was obtained with gangliosides GM1, GM2, GM3, and GD1a in nanomolar concentrations, whereas the asialo derivative of GM1, sialyl-lactose, and sialoglycoproteins were poor inhibitors. These findings indicate that sialyl-lactosylceramide (GM3) is the minimal structure for the fimbria-dependent binding of H. influenzae to its receptor on oropharyngeal epithelial cells and erythrocytes. As is the case with GM2, substitution of GM3 with N-acetylgalactosamine makes the molecule a 10-fold-better receptor analog.

High-affinity binding of the basement membrane proteins collagen type IV and laminin to the gastric pathogen Helicobacter pylori

The ability of 16 isolates of the human gastroduodenal pathogen Helicobacter pylori to bind 125I-radiolabelled tissue proteins was quantitated by liquid-phase assay. While capable of binding generally low levels of collagen types I and II, vitronectin, and fibronectin (average binding, 8%; highest binding, 23%), the various H. pylori isolates were good binders of the basement membrane proteins collagen type IV and laminin (average binding, 27%; highest binding, 60%). Campylobacter species tested bound lower levels of collagen type IV and laminin (average binding, 12%; highest binding, 17%). Trypsin and proteinase K treatment of H. pylori cells markedly reduced the binding of collagen type IV and laminin, as did heat treatment, suggesting that the binding of basement membrane proteins is mediated by bacterial surface proteins. Binding of both basement membrane proteins was rapid and saturable. 125I-collagen type IV binding to H. pylori 915 was inhibited by preincubation with unlabelled collagen type IV but was not inhibited by laminin or a number of other proteins. Once bound, radiolabelled collagen type IV but was not displaced by an excess of unlabelled collagen type IV, indicating that the binding interaction was of high affinity. Binding of laminin was partially reversible, and analysis in a solid-phase nonradiolabel assay showed that the interaction was of high affinity, with a Kd of 7.9 nM. This interaction was affected by salt, indicating the presence of a hydrophobic component in the ability of H. pylori to bind laminin.

In vitro binding of Helicobacter pylori to human gastric mucin

The in vitro binding of four Helicobacter pylori strains to human gastric mucin was studied with an enzyme-linked immunosorbent assay. All four strains were found to bind to purified mucin. Neuraminidase treatment and nonspecific oxidation of mucin decreased bacterial adherence to the macromolecule. Mucin preparations were also found to inhibit attachment of H. pylori to HEp-2 monolayers.

Flocculation of venereal disease research laboratory reagent by Helicobacter pylori

Helicobacter pylori strains flocculated with Venereal Disease Research Laboratory (VDRL) reagent in a glass slide test. Other pathogenic bacterial and fungal strains were nonreactive. The specific VDRL reaction property of Helicobacter pylori indicates an affinity of the cells for lipoidal substances, and can be used as a diagnostic aid for species identification.

High prevalence of Helicobacter pylori infection and histologic gastritis in asymptomatic Hispanics

In this study, we estimated the prevalence of Helicobacter pylori infection and histologic gastritis in 58 asymptomatic Hispanic adult volunteers (mean age, 41 years; 59% male) by endoscopic biopsy of the upper gastrointestinal tract. Forty-six subjects (79%) were found to harbor H. pylori in gastric biopsies, and all had histologic gastritis. Four other subjects were found to have gastritis in the absence of H. pylori. Similar prevalences of H. pylori and gastritis were noted in all age groups and also in American-born and immigrant Hispanics. Biopsy data and serologic studies of H. pylori antibodies correlated well. We conclude that H. pylori infection is an almost universal finding in the gastric mucosa of asymptomatic adult Hispanics, regardless of age. The clinical significance of these findings is unknown, but we speculate that H. pylori and its associated gastritis could have a role in the high incidence of gastric carcinoma in Hispanic populations.

Identification of glycolipid receptors for Helicobacter pylori by TLC-immunostaining

Helicobacter pylori has been identified as a causative agent in active chronic gastritis. The receptor for this bacteria, however, is not known. It is likely that the receptor molecules may be glycosphingolipids as shown in the cases of other bacteria. We explored this possibility by a thin-layer chromatography (TLC)-immunostaining method. Among glycosphingolipids extracted from human gastric mucosa, intact Helicobacter pylori specifically bound to I3SO3-GalCer and II3NeuAc-LacCer, whereas no specific binding to neutral glycosphingolipids, which share the same ceramide moiety with I3SO3-GalCer or II3NeuAc-LacCer, was demonstrated. Sonicated bacteria could still bind to II3NeuAc-LacCer with comparable affinity. In contrast, the binding of bacteria to I3SO3-GalCer was greatly diminished upon sonication. These results suggest that each of the oligosaccharide moieties of II3NeuAc-LacCer and I3SO3-GalCer may be specifically recognized by different ligand molecules of Helicobacter pylori.

ABO blood group, secretor status and detection of Helicobacter pylori among patients with gastric or duodenal ulcers

Patients (454) referred for gastroscopy to the General Hospital of Athens were examined to determine (1) if non-secretors were over-represented among patients with ulcers and (2) if there was an association with ABO blood group or secretor status and carriage of Helicobacter pylori. Compared with the local population, among patients with either gastric ulcer (51) or duodenal ulcer (96) there was a significant increase in the proportion of those who were blood group O (P less than 0.025); however, there were no significant differences in the proportions of non-secretors. H. pylori was identified in 62% of the 454 patients: 59.5% of those without evidence of ulcers; 62.5% of those with gastric ulcer; 88% of those with duodenal ulcer (P less than 0.0005). These bacteria were cultured more often and in higher numbers from patients with duodenal ulcer (P less than 0.025). There was no association between ABO blood group and prevalence of H. pylori. The prevalence of H. pylori among non-secretors with gastric ulcer (12.5%) was significantly lower than that for non-secretors with duodenal ulcer (100%) (P less than 0.0005). This was not observed for secretors.

Virulence and pathogenicity of Helicobacter pylori

H. pylori is a highly virulent organism as evidenced by its low infective dose and widespread high prevalence in human populations. Its virulence is achieved through its ability to survive in a moist environment and its massive urease production which allows it to survive in the acidic gastric juice long enough to colonize the gastric mucus. Gastric colonization is facilitated by cell wall associated lectins which permit the bacterium to bind to gastric mucus and the gastric epithelial cell. Once in this location, H. pylori produces several enzymes which may harm the gastric epithelium, particularly urease (through ammonia generation) and phospholipases A and C. H. pylori also weakens the gastric mucous layer by digesting its glycoproteins and lipids, making the mucus less hydrophobic and more water soluble. Helicobacter pylori attracts phagocytic cells, inducing both acute and chronic inflammation as well as an antibody response. Persistence of H. pylori in the mucosa may be enhanced by its cytotoxin and catalase production, by which it survives after phagocytosis by neutrophils.

Helicobacter pylori infection in pernicious anemia: a prospective controlled study

Although some authors believe that Helicobacter pylori is the etiologic agent in chronic nonspecific gastritis, it has also been suggested that the bacterium colonizes inflamed mucosa as a secondary event. This study documents the prevalence of H. pylori in 28 patients with pernicious anemia and compares the findings with those of a group of 28 age-, race-, and sex-matched asymptomatic control subjects. All subjects underwent endoscopy with biopsy of the gastric antrum and corpus. A sample of serum was obtained before endoscopy for determination of antibodies (immunoglobulin A and immunoglobulin G) to H. pylori. The prevalence of H. pylori (by biopsy) in patients with pernicious anemia was significantly less than that in controls (11% vs. 71%, P less than 0.0001). All patients with pernicious anemia had abnormalities of corpus histology (inflammation and/or atrophy). In addition, 50% of patients with pernicious anemia had a lymphocytic infiltration of the antrum. All controls with H. pylori had gastritis, 50% having active chronic gastritis. Atrophic changes of the corpus were more commonly found in patients with pernicious anemia (75% vs. 7%, P less than 0.0001). Serology and biopsy results correlated poorly in the patients with pernicious anemia: all 5 patients with positive serology results had negative biopsy results, whereas all 3 patients with positive cultures on biopsy had negative serological studies. In conclusion, patients with pernicious anemia are protected from infection with H. pylori, and H. pylori does not passively colonize mucosa inflamed by an unrelated process.

Comparison of isolates of Helicobacter pylori and Helicobacter mustelae

On the basis of analysis of protein profiles, isolates of Helicobacter pylori and Helicobacter mustelae were less than 40% similar. Cytotoxin produced by H. pylori was not detected in isolates of H. mustelae. Both bacterial species agglutinated human erythrocytes. These results substantiate a taxonomic difference between H. pylori and H. mustelae.

Isolation and biochemical and molecular analyses of a species-specific protein antigen from the gastric pathogen Helicobacter pylori

A protein of Mr 26,000 which was present in large quantities in extracts of cells of Helicobacter pylori was purified to homogeneity by ammonium sulfate precipitation followed by gel filtration and reversed-phase chromatography or anion-exchange chromatography. The protein appeared to be associated with the soluble fraction of the cell, and antibodies raised against the protein were reactive with whole-cell lysates of a variety of H. pylori strains in a simple immunodot blot assay. This reaction was species specific. Protein sequence determination of the amino terminus and internal cyanogen bromide fragments and amino acid composition analysis were performed. An oligonucleotide derived from these data was used to clone a fragment encoding most of the coding sequence. Expression in Escherichia coli was dependent on vector promoters. The DNA sequence of the fragment was determined. DNA probes derived from the cloned fragment hybridized to genomic DNA of all H. pylori strains tested, but not to DNAs of Helicobacter mustelae, Wolinella succinogenes, various Campylobacter species, and a panel of gram-negative enteric bacteria. The apparent uniqueness of this protein may be exploited for the development of species-specific diagnostics for this gastric pathogen.

Characterization of the Helicobacter pylori urease and purification of its subunits

Helicobacter pylori (formerly Campylobacter pylori) is the causative agent of gastritis in man. Helicobacter pylori cells contain a large amount of an extremely active urease (E.C.3.5.1.5). This enzyme is suspected to be a virulence factor since the ammonium ion produced from urea may be responsible for tissue injury and/or survival of H. pylori in the gastric environment. Helicobacter pylori urease, native relative molecular mass approximately 600,000, was purified by agarose gel filtration and ion exchange chromatography. DEAE-purified urease is highly active and has a Km of 0.48 mM for urea. The enzyme has a pI of 5.93 and is active from pH 4.0 to 10.0, with an optimum at pH 8.0. The purified urease contains nickel and is composed of two protein subunits, with relative molecular masses of 66,000 and 31,000. The subunits were separated and purified and the first 30 N-terminal amino acid residues were determined. A remarkably close relationship was found between both H. pylori urease subunits and jack bean (Canavalia ensiformis) urease, the subunit of which is a single 840 amino acid polypeptide. This subunit is also largely identical to the high molecular mass subunits of the ureases of Klebsiella aerogenes and Proteus mirabilis, evidence that these four ureases are derived from a common ancestral protein.

Helicobacter pylori

Helicobacter pylori is a unique pathogen and the leading cause of chronic gastric inflammation. For many individuals the organism is of low virulence, causing only mild inflammation and generating few, if any, dyspeptic symptoms. For those with more severe inflammation, H. pylori infection may be causal in the generation of dyspeptic symptoms. H. pylori infection appears to be the dominant factor in peptic ulcer disease. Events considered to be of importance are a disturbed gastrin homeostasis and the development of gastric metaplasia in the bulb. The most important argument in support of the dominant role of H. pylori in duodenal ulcer disease is the markedly reduced ulcer relapse after successful eradication. Eradication proves to be difficult, presumably because of the peculiar habitat of the organism. Currently the best pharmacologic approach is triple therapy, combining a bismuth salt, metronidazole, and amoxycillin or tetracycline.

Adherence of Helicobacter pylori cells and their surface components to HeLa cell membranes

Four Helicobacter pylori strains were used to develop in vitro methods to assess adherence to HeLa cells. Using direct detection by microscopy, adhesion scores increased with the initial bacteria-to-cell ratio. The urease method assessed H. pylori bound to HeLa cells by their urease activity. The percentage of the original inoculum adhering to HeLa cells remained constant for initial ratios from 10(2) to 10(5) bacteria per cell. An ELISA using anti-H. pylori serum assessed whole bacteria or components bound to HeLa cell fractions. By all three methods, the four H. pylori strains were adherent to HeLa cells or membranes whereas Campylobacter fetus and Providencia control strains were not. The adherence of H. pylori whole cells decreased following extraction with saline, water, or glycine buffer and most of the superficial adhering material (SAM) was present in the saline or water extracts. SAM bound better to HeLa membranes than to calf fetuin or bovine serum albumin (BSA); binding was inhibited by preincubation of SAM with HeLa membranes but not with fetuin or BSA or by pretreatment of HeLa membranes with neuraminidase. These data indicate that SAM has a specific receptor on the HeLa cell membranes. By gel exclusion chromatography of bacterial extracts, the most adherent components were found in the fractions which also contained the highest urease activity; these fractions included urease subunit antigens. We conclude that adherence of H. pylori can be assessed by microtiter assays and involves bacterial surface material which co-purifies with urease and is different from the N-acetyl-neuraminyl-lactose binding hemagglutinin.

Inhibition of Helicobacter pylori haemagglutination activity by human salivary mucins

Thirty isolates of Helicobacter pylori from gastric biopsies agglutinated human erythrocyte suspensions. Crude mucin preparations derived from saliva of 20 different donors were examined for their ability to inhibit haemagglutination. All mucin preparations exhibited strong inhibitory activity. Removal of sialic residues from mucin preparations by treatment with neuraminidase resulted in a substantial reduction of their inhibitory activity. The mucin preparations had no bactericidal or aggregation activity for H. pylori. These results are discussed in the context of the role of mucins in colonization of the gastric mucosa by H. pylori.

Erythrocyte gangliosides act as receptors for Neisseria subflava: identification of the Sia-1 adhesin

Neisseria gonorrhoeae was recently shown to bind to a subset of lactose-containing glycolipids (N. Strömberg, C. Deal, G. Nyberg, S. Normark, M. So, and K.-A. Karlsson, Proc. Natl. Acad. Sci. USA 85:4902-4906, 1988). A number of commensal Neisseria strains were also shown to be lactose binders. In addition, Neisseria subflava bound to immobilized gangliosides, such as hematoside and sialosyl paragloboside, carrying the NeuAc alpha 2-3Gal beta 1-4Glc sequence. To a lesser extent, N. gonorrhoeae also bound to this receptor in vitro. In N. subflava GN01, this binding property mediated agglutination of human erythrocytes in a neuraminidase-sensitive fashion. Nitrosoguanidine-induced nonhemagglutinative mutants of N. subflava GN01 had lost the ability to bind hematoside and sialosylparagloboside but remained able to bind lactosylceramide and gangliotetraosylceramide. These mutants fell into three classes with respect to their outer membrane protein profiles in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Class 1 mutants were identical to the parent strain save for the loss of a 27-kilodalton (kDa) protein. Class 2 mutants showed an outer membrane protein profile identical to that of the wild type, whereas mutants belonging to class 3 showed a number of changes, including the apparent absence of the 27-kDa protein. The 27-kDa protein from N. subflava GN01 was purified from the supernatant. A polyclonal antiserum to the purified Sia-1 protein as well as a Sia-1-specific monoclonal antibody inhibited hemagglutination by strain GN01. The purified Sia-1 protein in the presence of diluted anti-Sia-1 antiserum mediated a neuraminidase-sensitive hemagglutination. The purified Sia protein from a class 2 mutant was not able to hemagglutinate when cross-linked with antibodies, suggesting that it is a mutant form of Sia-1 affected in the receptor-binding site. Immunoelectron microscopy with a Sia-1-specific monoclonal antibody revealed that the adhesin was nonfimbrial in nature, with aggregates of the adhesin extended out from the cells in a patchy fashion.

Unusual fatty acid substitution in lipids and lipopolysaccharides of Helicobacter pylori

Cellular fatty acids, phospholipid fatty acids, and lipopolysaccharide fatty acids of four strains of Helicobacter pylori were analyzed by gas-liquid chromatography. The presence of myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, 19-carbon cyclopropane fatty acid, beta-hydroxypalmitic acid, and beta-hydroxystearic acid was confirmed. In phospholipids, myristic acid and 19-carbon cyclopropane fatty acid were the major fatty acids. Hydroxy fatty acids and unsaturated fatty acids were not detected or occurred only in small amounts. The major fatty acids of lipopolysaccharides were stearic acid, beta-hydroxypalmitic acid, and beta-hydroxystearic acid. Unsaturated fatty acids and 19-carbon cyclopropane fatty acid were not found. The unusual compositions of H. pylori phospholipid and lipopolysaccharide fatty acids may have important implications for the taxonomy, physicochemical membrane properties, and biological activity of lipopolysaccharides.

Bacterial adhesion and disease activity in Helicobacter associated chronic gastritis

Ultrastructural examination of biopsies showing Helicobacter pylori associated chronic gastritis reveals close attachment between gastric surface epithelial cells and the organism. The finding of 'adhesion pedestals', which represents a cellular response to the presence of the organism, is analogous to the response of intestinal cells to enteropathogenic E coli. Thus the development of bacterial attachment sites in H pylori associated gastritis might be an indication of pathogenicity. We have therefore explored the relationship between the proportion of organisms forming attachment sites and histological indices of disease 'activity'. Antral biopsies from 40 patients with H pylori positive gastritis were examined histologically and ultrastructurally, and the percentage of attached organisms compared with subjective assessments of epithelial degeneration, mucin depletion, polymorphonuclear and chronic inflammatory cell infiltration. We found a significant increase in the proportion of attached bacteria in cases showing histological epithelial degeneration, and a significant decrease in cases showing intraepithelial polymorph infiltration. The direct relationship between bacterial attachment and cellular degeneration lends further support to a pathogenic effect. Reduced attachment in the face of polymorph infiltration might indirectly reflect aspects of the immune response--namely, blocking of adhesion by IgA, with complement activation and generation of leucotactic factors.

Campylobacter pylori and gastroduodenal disease

Campylobacter pylori is a newly described, spiral-shaped, gram-negative bacillus that is oxidase positive, catalase positive, and urease positive and grows slowly in culture. Although observed in human tissue at the beginning of the century, it was not cultured until 1982. Because there are significant morphological and genetic differences between this organism and other species of Campylobacter, it will probably be reclassified in a new genus. Current information indicates that the organism primarily resides in the stomach tissue of humans and nonhuman primates and may occasionally spread to the esophagus or other parts of the alimentary tract under appropriate conditions. Significant evidence has accumulated in the last several years to show that it causes gastritis, and there is mounting evidence that it may participate in the development of duodenal ulcers. It may also be associated with gastric ulcers and nonulcer dyspepsia. It can be detected in patients by culture of biopsy specimens or histological staining of biopsy tissue. Indirect evidence for the presence of the organism can be obtained by detection of urease in a tissue biopsy specimen, by urea breath tests, or by detection of specific antibody. It may not be necessary to implement these procedures for routine use, however, until the role of the organism can be defined better. Ultimately, the discovery of this organism may lead to radical changes in the diagnosis and treatment of gastric disease.

Microbiological aspects of Helicobacter pylori (Campylobacter pylori)

The human gastric pathogen Campylobacter pylori has recently been reclassified as Helicobacter pylori, and a related spiral bacterium found in the stomach of ferrets has been designated Helicobacter mustelae. The general microbiological features of Helicobacter pylori are delineated here, with details of phenotypic differences between Helicobacter pylori and Helicobacter mustelae; comparisons are made with Wolinella succinogenes and Campylobacter jejuni. The Helicobacter organisms possess an external glycocalyx which can be visualised by electron microscopy, and which may be involved in bacterial adherence. The finding of soluble and cell-associated haemagglutinins of Helicobacter pylori is reported. Detection of Helicobacter pylori in clinical specimens, susceptibility of the organism to antibacterial agents, and other aspects of practical and clinical significance are briefly reviewed.

Receptor-mediated adherence of Campylobacter pylori to mouse Y-1 adrenal cell monolayers

An in vitro adherence assay was developed to study the adherence of Campylobacter pylori to mammalian cells. Strains of C. pylori were isolated from individuals with gastritis. These strains possessed the fibrillar N-acetylneuraminyllactose(neuraminlactose)-binding hemagglutinin (NLBH) and were found to adhere to monolayers of mouse Y-1 adrenal cells. Adherence was rapid, prevented by pretreatment of the Y-1 cells with Clostridium perfringens neuraminidase, and blocked by the neuraminlactose-containing protein fetuin. Electron microscopy by the immunogold technique and with anti-NLBH antibody showed that NLBH was present at the sites of interaction between C. pylori and the Y-1 cells. These results indicate that the Y-1 monolayer is a valid model for receptor-specific adherence of C. pylori.

Serum antibody responses to the N-acetylneuraminyllactose-binding hemagglutinin of Campylobacter pylori

We recently reported that Campylobacter pylori possesses a surface-associated fibrillar hemagglutinin which has an affinity for N-acetylneuraminyllactose; this hemagglutinin may function as a colonization factor for attachment to the gastric epithelium. In the present study we examined serum samples obtained from 65 C. pylori-infected individuals with gastric ulcers, duodenal ulcers, or both and from 121 asymptomatic volunteers, including 62 who were infected with C. pylori, for immunoglobulin G (IgG) specific for the C. pylori neuramin-lactose-binding hemagglutinin (NLBH). The NLBH purified from a single isolate was used as the antigen in an enzyme-linked immunosorbent assay. A positive result was obtained with serum from 81.5% (53 of 65) of the individuals with ulcers, 67.7% (42 of 62) of the C. pylori-infected volunteers, and 1.7% (1 of 59) of the C. pylori-negative volunteers. This result confirms that NLBH is produced in vivo. There are several possible explanations for the fact that only 75% of 127 C. pylori-infected individuals were positive for anti-NLBH IgG in serum. We favor the hypothesis that there are probably several antigenically distinct C. pylori NLBHs, i.e., NLBHs which would stimulate antibody that was undetectable by the antigen used in the enzyme-linked immunosorbent assay described here.

Campylobacter pylori and peptic ulcer disease

Campylobacter pylori is now known to be the most common and important cause of gastritis, and C. pylori infections have been associated with duodenal ulcer, gastric ulcer, nonulcer dyspepsia, and gastric cancer. Although it has been only possible to culture C. pylori for about 5 yr, there are already sufficient data available to allow us to develop the basic framework that relates C. pylori gastritis to the causation of peptic ulcer disease. We review the data and propose mechanisms that implicate C. pylori as an important factor in the pathogenesis of peptic ulcer disease and consider the therapeutic implications. What we now know about C. pylori begins to unravel some of the mysteries surrounding peptic ulcer disease.

Campylobacter pylori as a pathogenetic factor in duodenal ulcer: the case for

This debate addresses whether Campylobacter pylori contributes to the development and maintenance of chronic peptic ulcer disease. C. pylori may be both an aggressive factor and may also impair mucosal defence. C. pylori causes the inevitably ulcer-associated gastritis and duodenitis and eradication of the C. pylori infection is associated with resolution of the inflammation and virtual elimination of the problem of duodenal ulcer relapse. A model is suggested that requires two separate factors to combine to cause chronic duodenal ulcer disease with other environmental factors (e.g. smoking) modifying the interaction between C. pylori and genetic susceptibility. Both genetic susceptibility and C. pylori infection are required to produce duodenal ulcer disease; neither alone is sufficient. C. pylori is the most important factor in the pathogenesis of duodenal ulcer disease because it is the only pathogenetic factor that can be easily reversed by medical therapy.

Campylobacter pylori and Barrett's esophagus

Occurrence of C. pylori infection of mucosa outside of the stomach might provide an ideal opportunity to examine C. pylori-mucosal interactions apart from the effects of acid and pepsin. Techniques previously used to examine Barrett's epithelium (for example, special mucin stains or scanning and transmission electron microscopy) might be particularly useful for exploration of new associations and formulation of new hypotheses. Whether C. pylori has a role in development of Barrett's ulcer or adenocarcinoma as a complication of Barrett's esophagus remains unanswered. Most of the current data about C. pylori are primarily observational; further studies are needed for clarification of important microbegut interactions.