Helicobacter spp. Other Than Helicobacter pylori

Non- H. pylori Helicobacter species (NHPHS) are associated with several important human and animal diseases. In the past year research into this group of bacteria has continued to gain attention, and novel species have been described in new niches owing to improvements in detection methods. Polymerase chain reaction and/or sequencing remain the gold standard for the detection of this genus. New insights into the pathogenesis of the NHPHS in hepatobiliary, gastric, and intestinal diseases were gained. In particular, data revealed interaction between hepatic steatosis and infectious hepatitis in the development of hepatocellular carcinoma. Evidence of an association between hepatitis C virus and Helicobacter spp. in hepatocarcinoma development was also provided; and male sex hormone signaling appeared to influence infectious hepatitis induced by Helicobacter hepaticus . More findings support an association between Helicobacter heilmannii and gastric adenocarcinoma; and in mice, mucins MUC4 and MUC5 but not MUC1 influence the colonization and pathogenesis of Helicobacter felis . Data indicated that the roles of the adaptive immune system in H. hepaticus -induced intestinal tumorigenesis are different in the small and large intestines, and environmental factors, such as bile acids may modulate H. hepaticus carcinogenic potential. New reports in the prevention and eradication of NHPHS showed a protective response against Helicobacter suis induced by vaccine administration, and a successful cross-foster rederivation method successfully eradicated Helicobacter spp. from contaminated mice litters. Overall, the studies provided insights into the pathophysiology of Helicobacter species other than Helicobacter pylori.     

Extragastric manifestations of Helicobacter pylori infection--other Helicobacter species

Recent studies have indicated a strong link between Helicobacter pylori and idiopathic thrombocytopenic purpura and iron deficiency anemia. Interesting results have also been obtained for ischemic heart disease, though most putative associations between H. pylori infection and extragastric disease remain speculative. With regard to other Helicobacter species, Helicobacter felis has been shown to play a role in gastric carcinogenesis in mouse models. An increased susceptibility to cholesterol gallstone formation has been described in animals fed a lithogenic diet and infected with Helicobacter bilis, or co-infected with Helicobacter hepaticus and Helicobacter rodentium. Finally, enterohepatic Helicobacter species have also been exploited to better understand inflammatory bowel disease.     

Helicobacter exposed

Helicobacter pylori Protocolsedited by C.L. Clayton and H.L. Mobley, Humana Press, 1997. Hardback US $89.50 (xiii+274 pages) ISBN 0 896 033 813     

Helicobacter pylori motility

Motility is essential for Helicobacter pylori colonization. This review discusses the biochemistry, genetics and genomics of the H. pylori flagellum, and compares these features with well-characterized bacteria.     

Helicobacter pylori catalase

Helicobacter pylori is the major aetiological agent of gastroduodenitis in humans. Due to the potential importance of catalase in the growth and survival of Helicobacter pylori on the surface of inflamed mucosae, we have characterized catalase from H. pylori as a prelude to further studies on the function of the enzyme in vivo. The catalase activity of H. pylori was significantly affected by the presence of blood, serum or erythrocytes in the growth medium: the greatest activity was expressed when the bacterium was grown on medium containing serum. H. pylori catalase is a tetramer with a subunit Mr of 50,000. The enzyme had a pI of 9.0-9.3, was active over a broad pH range and was stable at 56 degrees C. It was non-competitively inhibited by sodium azide, and had no detectable peroxidase activity. The Km for the purified catalase was measured as 43 +/- 3 mM-H2O2 and the V as 60 +/- 3 mmol H2O2 min-1 (mg protein)-1. The native catalase has absorption maxima at 280 nm and 405 nm with further minor shoulders or peaks at 510 nm, 535 nm and 625 nm, consistent with the presence of an iron-porphyrin prosthetic group.     

Immunogenic proteins of Helicobacter pullorum,Helicobacter bilis and Helicobacter hepaticus identified by two-dimensional gel electrophoresis and immunoblotting

The ecological niches occupied by various species of Helicobacter are not yet known and the full spectrum of diseases associated with Helicobacter infections are not yet defined. Since these fastidious microaerofilic bacteria require special growth conditions new and improved molecular and serologic diagnostic methods have been developed to increase our understanding of their pathogenesis and virulence characteristics. Immunogenic cell surface proteins of Helicobacter pullorum, Helicobacter bilis, and Helicobacter hepaticus were characterised by proteomic techniques using two-dimensional electrophoresis and immunoblotting with antisera from immunised rabbits. Cross-reactivity between the three Helicobacter species were analysed after a four-step cross-absorption experiment. For H. pullorum, H. bilis and H. hepaticus 21, 13 and 27 specific immunogenic proteins, respectively, were identified. These proteins could be of important sero-diagnostic value for analyses of sera from humans, laboratory animals and for the veterinarian field.     

Helicobacter and Gastric Malignancies

Individuals infected with Helicobacter pylori , a stomach colonizing bacteria, have an increased risk of developing gastric malignancies. The risk for developing cancer relates to the physiologic and histologic changes that H. pylori infection induces in the stomach. In the last year numerous studies have been conducted in order to characterize the association between H. pylori infection and gastric cancer. These studies range from epidemiologic approaches aiming at the identification of environmental, host genetic, and bacterial factors associated with risk of gastric cancer, to molecular and cell biology approaches aiming at understanding the interaction between H. pylori and the transforming epithelial cell. In this review an account of the last year's research activity on the relationship between H. pylori and gastric cancer will be given.     

Detection of non-pylori Helicobacter species in "Helicobacter heilmannii"-infected humans

BACKGROUND: A small proportion of patients suffering from chronic active gastritis are diagnosed with gastric Helicobacter species other than Helicobacter pylori. Circumstantial evidence has suggested that these bacteria, also referred to as "Helicobacter heilmannii"-like organisms (HHLO), may be transmitted through animals. The isolation of a Helicobacter bizzozeronii strain from a human patient confirmed this hypothesis. It was the aim of the present study to assess the presence of animal Helicobacter species and H. pylori in humans infected with HHLO, as diagnosed by histology. METHODS: Paraffin-embedded gastric biopsy specimens of 108 HHLO-infected patients (42 women and 66 men) from three clinical centers were screened for the presence of animal gastric Helicobacter species by polymerase chain reaction (PCR), using assays targeting the 16S rDNA region of the three known canine and feline helicobacters (H. bizzozeronii, H. salomonis and H. felis), "Candidatus H. suis", and "Candidatus H. bovis". In addition, the presence of H. pylori was evaluated by multiplex PCR analysis. RESULTS: In 63.4% of the stomachs (64/101) classification of the Helicobacter infection into the above mentioned groups was achieved. Non-pylori Helicobacter species commonly colonizing the stomachs of cats and dogs were found in 48.5% (49/101) of the patients. Fourteen (13.9%) samples tested positive for "Candidatus H. suis", and "Candidatus H. bovis" was demonstrated in 1 (0.9%) patient. The presence of H. pylori was established in 13 patients (12.9%). Eleven stomachs (10.9%) were infected with at least two different Helicobacter species. CONCLUSIONS: This study identifies animal Helicobacter species in the stomach of a large series of HHLO-infected patients, which may have clinical implications in a subset of patients with gastric disease.     

Helicobacter pylori Multiplex Serology

Background:  Helicobacter pylori infection is associated with severe gastrointestinal disease including cancer. It induces complex antibody responses that might vary depending on disease state but currently cannot be assessed adequately. The objective of this work was the development of a sensitive and specific H. pylori multiplex serology assay with high-throughput capability that allows simultaneous detection of antibodies to a protein array.
Methods:  Seventeen proteins of up to three H. pylori strains (26695, G27, 151), including CagA, VacA, UreA, Catalase, Omp, and GroEL, were recombinantly expressed as glutathione- S -transferase fusion proteins, affinity-purified, and used as antigens in a fluorescent bead-based antibody-binding assay. Reference sera (n   =   317) characterized by commercial assays (screening ELISA with Western blot confirmation) were used for validation.
Results:  H. pylori seropositivity by multiplex serology defined as reactivity with at least four proteins showed good agreement (kappa: 0.70) with commercial serologic assay classification, and a sensitivity of 89% and specificity of 82%. For individual antigens, agreement with Western blot was good for CagA (kappa: 0.77), moderate for UreA (kappa: 0.53), and weak for VacA (kappa: 0.12). Of the 13 proteins expressed from two strains, only VacA showed serologic strain differences. High antibody reactivity to CagA (Type I infection) was negatively associated with antibodies to GroEL, Cad, CagM, catalase, HcpC, NapA, and UreA, suggesting type-specific differences in protein expression patterns and/or immune response.
Conclusion:  With its high-throughput and simultaneous detection abilities, H. pylori multiplex serology appears suited as tool for large seroepidemiologic studies assessing H. pylori prevalence, antibody patterns, and associations with specific diseases.