Brefeldin A enhances Helicobacter pylori vacuolating cytotoxin-induced vacuolation of epithelial cells

Intracellular VacA localises to the vacuolar (late endosome/lysosome) membrane, but little is known about the trafficking of the toxin beyond this region. We show that the Golgi-disturbing agent brefeldin A (BFA) enhances VacA-induced vacuolation of epithelial cells by Helicobacter pylori co-culture and, importantly, BFA treatment induces vacuolation by less toxic forms of VacA. The effect is BFA dose-dependent and occurs within 2.5 h. These data suggest that VacA may be routed deeper within the cell than the vacuole, and that vacuolation is minimised when this occurs efficiently. This may explain why some forms of VacA do not cause vacuolation and why vacuolation is minimal at the low bacteria:cell ratios observed in vivo.     

Antinematodal activity and the mechanism of the antimicrobial peptide, HP (2-20), against Caenorhabditis elegans

The peptide HP (2-20), derived from the N-terminal sequence of Helicobacter pylori ribosomal protein L1 (RPL1), has a nematicidal activity against eggs and worms of Caenorhabditis elegans. Eggs treated with HP (2-20) (69%) has a higher fluorescence intensity with propidium iodide staining, which was similar to that of melittin (82%) but higher than untreated cells (5.7%). Confocal microscopy showed that the peptides were located in the shell of the eggs and the inner and outer surfaces of the worms. HP (2-20) therefore may exert its antinematodal activity by disrupting the structure of the egg's shell and the cell membrane via pore formation or by direct interaction with the lipid bilayers in a detergent-like manner.     

The incidence of Helicobacter pylori acquisition in children of a Canadian First Nations community and the potential for parent-to-child transmission

BACKGROUND AND AIMS: We have previously reported that Wasagamack, a Canadian First Nations community has a seroprevalence rate of Helicobacter pylori of 95% and a prevalence rate among children aged 0-12 years as measured by stool antigen testing of 56%. We aimed to determine the rate of infection acquisition and possible modes of transmission of childhood Helicobacter pylori infection in this Canadian First Nations community. METHODS: Children who were previously negative for H. pylori by stool antigen testing in August 1999 were eligible for enrollment in August 2000; 50 (77%) eligible children underwent stool collection. H. pylori stool antigen status was tested using the Premier Platinum HpSA test. Drinking water samples, maternal saliva, breast milk, local berries and flies were tested by three complementary H. pylori-specific PCR assays. Soothers or bottle nipples, collected from 16 children whose H. pylori stool antigen status was determined, were bathed in sterile water and this water was tested by PCR. RESULTS: Stool was positive for H. pylori in 16% (8/ 50) of children retested. Five had no other siblings infected and three had infected siblings. The mothers of all children infected were positive for H. pylori. The median age of newly infected children was 6 years (range 1-13 years). By PCR, 78% (18/23) mothers' saliva samples, 69% (11/16) soother water samples and 9% (1/11) water samples from infected homes tested positive. All of 24 sequenced PCR-produced DNA fragments from samples showed 99% homology with that from ATCC type strain H. pylori. CONCLUSIONS: The rate of childhood H. pylori acquisition was 16% over 1 year, and was not dependent on number of siblings infected. The finding of homologous H. pylori DNA in saliva and in soother water suggests the possibility of human to human transmission, particularly via an oral-oral route. Thus, there is the potential for further investigations in this population and other endemic communities that are directed at prevention of infection transmission via this modality.     

The interleukin-1 RN polymorphism and Helicobacter pylori infection in the development of duodenal ulcer

BACKGROUND: The host genetic factors that determine the clinical outcomes for Helicobacter pylori-infected individuals remain unclear. AIMS: To elucidate the relations among interleukin-1 locus polymorphisms, and H. pylori infection in the development of duodenal ulcers. MATERIALS AND METHODS: In a case-control study involving 168 control subjects and 147 patients with duodenal ulcer, biallelic polymorphisms of two interleukin-1 loci, IL-1B(-511) and IL-1B(+3954), as well as the penta-allelic variable number of tandem repeats of interleukin-1 receptor antagonist IL-1RN, were genotyped, and the H. pylori states of controls and patients were examined. RESULTS: Helicobacter pylori infection, male gender and the carriage of IL-1RN*2 independently increased the risk of duodenal ulcer with odds ratios of 6.4 (95% confidence interval, 3.7-11.0), 1.9 (95% confidence interval, 1.1-3.4) and 2.7 (95% confidence interval, 1.1-6.8), respectively. Statistical analysis revealed an interaction between IL-1RN*2 and H. pylori infection with the duodenal ulcer risk conferred by the H. pylori infection substantially increased (odds ratios, 22.6; 95% confidence interval, 5.9-86.5) by the carriage of IL-1RN*2. In addition, a synergistic interaction between IL-1RN*2 and blood group O existed. The combined risk of H. pylori infection, the carriage of IL-1RN*2 and blood group O for duodenal ulcer was 27.5 (95% confidence interval, 3.1-243.6). CONCLUSIONS: This work is the first to verify IL-1RN*2 as an independent factor that governs the development of duodenal ulcers. Our data indicate that H. pylori infection and IL-1RN*2 synergistically determine susceptibility to duodenal ulcer. The blood group phenotype is possibly a crucial determinant for the outcome of the impact of an interleukin-1 locus polymorphism on H. pylori-infected individuals.     

Stool antigen test for the diagnosis of Helicobacter pylori infection: a systematic review

Our aim was to review systematically the diagnostic accuracy of the Helicobacter pylori stool antigen test. Bibliographical searches were performed in several electronic databases and abstracts from congresses up to May 2003. Eighty-nine studies (10,858 patients) evaluated the stool antigen test in untreated patients. Mean sensitivity, specificity, positive predictive value and negative predictive value were 91%, 93%, 92% and 87%, respectively. Analysis of the eight studies (1399 patients) in which pretreatment evaluation of the monoclonal stool antigen test was performed showed better (p < .001) results (96%, 97%, 96% and 97%, respectively), with a clearer distinction between positive and negative results. Thirty-nine studies (3147 patients) evaluated the stool antigen test for the confirmation of H. pylori eradication 4-8 weeks after therapy, with accuracies of 86%, 92%, 76% and 93% for mean sensitivity, specificity, positive predictive value and negative predictive value, respectively. Results were similar when a gold standard based on at least two methods was used. Relatively low accuracy was reported in some posttreatment studies with the polyclonal stool antigen test. However, excellent results (p < .001) were achieved in all the six studies evaluating the monoclonal stool antigen test 4-8 weeks posttreatment. Results evaluating the stool antigen test < 4 weeks posttreatment are contradictory. Proton-pump inhibitors seem to affect the accuracy of the stool antigen test. Sensitivity and/or specificity in patients with gastrointestinal bleeding may be suboptimal. The stool antigen test performs well in children. Finally, the stool antigen test seems to be a cost-effective method.     

Mechanism of action of low recurrence of gastritis caused by Helicobacter pylori with the type II urease B gene

Background. Low recurrence of gastritis is seen in patients infected with Helicobacter pylori carrying the type II urease B gene, compared with H. pylori carrying types I and III. The underlying mechanism has been studied in terms of the urease activity and interleukin (IL)‐8 production capacity of different strains of H. pylori. Materials and Methods. Forty‐five patients infected with different strains of H. pylori (type I; 15, type II; 15 and type III; 15) were enrolled in the study. H. pylori was isolated from gastric mucosa and cultured in the presence of urea at pH 5.5 to evaluate urease activity. The capacity of different strains of H. pylori to induce IL‐8 mRNA and IL‐8 from a human gastric cancer cell line and human peripheral blood mononuclear cells was evaluated. Results. The urease activity of type II H. pylori[523 ± 228 µg of ammonia/dl/10⁸ colony‐forming units (CFU)/ml] was significantly lower than that of type I (1355 ± 1369 µg of ammonia/dl/10⁸ CFU/ml) and type III (1442 ± 2229 µg of ammonia/dl/10⁸ CFU/ml) (p < .05). Gastric cancer cells cocultured with type II H. pylori produced lower levels of IL‐8 mRNA compared with type I and type III H. pylori. The levels of IL‐8 were also significantly lower in cultures induced by type II H. pylori compared with those induced by type I and type III H. pylori. Peripheral blood mononuclear cells also produced lower levels of IL‐8 when cocultured with type II compared with type I H. pylori. Conclusions. These results indicate that both the lower level of urease activity and the low IL‐8‐inducing capacity of type II H. pylori might underlie the lower recurrence rate of gastritis caused by type II H. pylori.     

Age at acquisition of Helicobacter pylori infection: comparison of two areas with contrasting risk of gastric cancer

Background. Helicobacter pylori infection is usually acquired during childhood and is a known risk factor for the development of gastric malignancies in adulthood. It has been reported that early age at first infection may determine a neoplastic outcome in adults. The purpose of this study was to determine the prevalence of Helicobacter pylori infection in children residing in areas with high (Pasto) and low risk (Tumaco) of gastric cancer in Colombia to evaluate whether differences in the age of acquisition of H. pylori infection were present in the two populations. Materials and Methods. The study sample was based on a census taken in 1999. Using the ¹³C‐urea breath test, we compared the prevalence of H. pylori infection among children aged 1–6 years. Results. Among 345 children in Pasto, 206 (59.7%) were H. pylori‐positive, compared with 188 (58.6%) among 321 children in Tumaco. The two populations share a common pattern of very early age at infection and marked increase in prevalence during the first 4 years of life. No differences in any one year were observed when comparing the two groups. Conclusions. The prevalence of infection was similarly high and increased with age in both populations. In these populations the age of acquisition of H. pylori after 1 year of age does not appear to be a primary factor responsible for the differences in the rates of gastric cancer incidence in adults. Previous findings in adults showed lower prevalence of the most virulent genotypes in Tumaco compared to Pasto, and bacterial virulence may play a key role in determining cancer outcome.     

Rank order of success favors longer duration of imidazole-based therapy for Helicobacter pylori in duodenal ulcer disease: a randomized pilot study

Background. Studies on eradication therapy in developing countries have shown a success rate of 70–85%, which is suboptimal. Duration of therapy may be an important factor dictating eradication success in such regions. Aim. The study was undertaken to evaluate the effect of increasing the treatment period on eradication of Helicobacter pylori in duodenal ulcer disease. Methods. A randomized trial was carried out in which 64 consecutive H. pylori‐infected patients with duodenal ulcer disease were enrolled. The patients were randomized to one of the three trial arms. Therapy consisted of lansoprazole 30 mg twice a day (b.i.d.), amoxycillin 1 g b.i.d. and tinidazole 500 mg b.i.d. The treatment period was 1 week in group I, 2 weeks in group II and 3 weeks in group III. At inclusion, patients underwent endoscopy and the presence of H. pylori was documented by a positive urease test and C14 urea breath test. Four weeks after completion of eradication therapy, the patients were subjected to repeat endoscopy to assess ulcer healing and tests for H. pylori infection. Results. Sixty‐four patients (55 male and nine female; mean age 35.5 years) were enrolled in each group. The H. pylori eradication rate for group I (1 week of therapy) was 47.6%, that for group II (2 weeks of therapy) was 80%, and that for group III (3 weeks of therapy) was 91.3% (p = .003). The ulcer healing rates were 71.4, 80 and 95.6% in groups I, II and III, respectively (p = .09). Conclusion. The 3‐week regimen significantly improved the eradication rate as compared with the 1‐week regime. Increasing the duration of therapy significantly improved the chances of eradication of H. pylori in duodenal ulcer disease.