High prevalence of cytotoxin positive Helicobacter pylori in patients unrelated to the presence of peptic ulcers in Japan

Serum VacA antibody is associated with risks of peptic ulcer and gastric cancer: A meta-analysis

BACKGROUND

Increasing studies have investigated the relationship between the status of H. pylori vacA antibody and risks of peptic ulcer disease (PUD) and gastric cancer (GC). However, the results were controversial. The aim of this meta-analysis is to clarify whether serum vacA antibody is associated with risks of PUD and GC.

METHODS

Databases including PubMed, Embase, Web of knowledge, Wanfang, Chinese National Knowledge Infrastructure (CNKI), OVID, Karger and Scopus were systematically searched for potentially eligible literature. Odds ratios (OR) and their 95% confidence interval (CI) were adopted to assess the strength of association.

RESULTS

Serum VacA antibody was associated with increased risk of PUD compared with gastritis/functional dyspepsia (FD) (OR = 1.96, 95%CI = 1.56-2.46, P < 0.001). Serum VacA antibody was significantly associated with increased risk of gastric ulcer (GU) and duodenal ulcer (DU) compared with gastritis/FD (GU: OR = 1.64, 95%CI = 1.02-2.62, P = 0.042; DU: OR = 2.06, 95%CI = 1.50-2.84, P < 0.001, respectively). Significant increased risk of GC was found in serum VacA antibody positive subjects compared with serum VacA antibody negative individuals (OR = 2.78, 95%CI = 1.98-3.89, P < 0.001). There was no significant publication bias in all of the comparisons.

CONCLUSIONS

Serum VacA antibody was significantly associated with increased risks of peptic ulcer disease, gastric ulcer and duodenal ulcer compared with gastritis and functional dyspepsia controls. Significant association was also found between serum VacA antibody and gastric cancer risk. Serum VacA antibody might be a potential biomarker for the prediction of risks of PUD and GC.

Study of the clinical relevance of Helicobacter pylori virulence genes to gastric diseases among Egyptian patients

BACKGROUND AND STUDY AIMS

Helicobacter pylori infection is common in Egypt. It has been associated with gastritis, ulcers and it is a risk factor for gastric cancer. We aimed to study the correlation between the presence of H. pylori virulence factors and the histopathological and endoscopic findings in gastric biopsies.

PATIENTS AND METHODS

Gastric biopsies from thirty seven patients scheduled for diagnostic endoscopy in Cairo University hospital were included in the study. All gastric biopsies were subjected to histopathological examination and PCR assay for detection of 16S rRNA gene to diagnose H. pylori infection, detection of H. pylori virulence factors by PCR for cagA and vacA genotypes and serological analysis of H. pylori (cagA, vacA, P25, and P19) IgG antibodies by immunoblot assay were done.

RESULTS

H. pylori infection was detected in 23 (62.2%) cases by histopathology while 28/37 (75.7%) were positive for H. pylori 16S rRNA gene by PCR. By PCR seventeen samples out of 37 (45.9%) were positive for cagA gene and five (13.5%) for cag empty site gene.

CONCLUSION

The most common vacA genotype identified was vacA s2m2 genotype in 10 (27.02%). No statistical correlation was found between IgG antibodies against different antigens of H. pylori virulence factors (cagA, vacA, p25, and p19) and the degree of gastritis except for IgG antibodies against the UreA antigen.

Assessment of gastroesophageal reflux disease by serodiagnosis of Helicobacter pylori-related chronic gastritis stage

AIM: To evaluate the association of Helicobacter pylori (H.pylori)-related chronic gastritis stage with upper gastrointestinal symptoms and gastroesophageal reflux disease (GERD).

METHODS: Subjects underwent upper gastrointestinal endoscopy, a questionnaire using a frequency scale for symptoms of GERD (FSSG), and measurements of serum H.pylori-antibody and pepsinogen (PG) levels. They were classified into the following 4 groups in terms of H.pylori-related chronic gastritis stage: Group A (n = 219), H.pylori(-)PG(-); Group B (n = 310), H.pylori(+)PG(-); Group C (n = 279), H.pylori(+)PG(+); and Group D (n = 17), H.pylori(-)PG(+).

RESULTS: Reflux esophagitis occurred in 30.6% of Group A, 14.5% of Group B, 6.8% of Group C, and 0% of Group D (P < 0.001). Scores for acid reflux symptoms decreased significantly with chronic gastritis stage (from Group A to D) (P < 0.05), while scores for dysmotility symptoms did not differ significantly. The prevalence of non-erosive reflux disease (NERD) did not differ among groups. However, in subjects with GERD, the prevalence of NERD tended to increase with chronic gastritis stage (P = 0.081).

CONCLUSION: Acid reflux symptoms and the prevalence of reflux esophagitis can be assessed by measuring both serum H.pylori-antibody and PG levels.

Prevalence of mid-gastrointestinal bleeding in patients with acute overt gastrointestinal bleeding: multi-center experience with 1,044 consecutive patients

BACKGROUND

Video capsule endoscopy (VCE) and double-balloon enteroscopy (DBE) enable the detection of small intestinal lesions.

AIM

To examine causes of acute overt gastrointestinal (GI) bleeding and the prevalence of mid-GI bleeding, defined as small intestinal bleeding from the ampulla of Vater to the terminal ileum, in a multi-center experience in Japan in the VCE/DBE era.

METHODS

Data were collected retrospectively from consecutive patients with acute overt GI bleeding in ten participating hospitals. All patients were examined by esophagogastroduodenoscopy and/or colonoscopy. When the source of bleeding was not identified after these procedures, patients suspected to have mid-GI bleeding were referred to our hospital and VCE/DBE was performed to determine the source of bleeding.

RESULTS

Of the 1044 patients with acute overt GI bleeding, 524 (50.2%) patients were diagnosed with upper GI bleeding, 442 (42.3%) with lower GI bleeding, and 13 (1.2%) with mid-GI bleeding. Gastric ulcer was the most common cause of bleeding (20.4%). Among cases of mid-GI bleeding, ulcers were found in 4 (30.8%) patients, erosions in 3 (23.1%), angiodysplasia in 3 (23.1%), submucosal tumor in 2 (15.4%), and hemangioma in one (7.7%). Seven lesions were located in the jejunum, 5 in the ileum, and one in both the jejunum and ileum. Analysis of age-related cause showed that the prevalence of mid-GI bleeding among younger patients under 40 years of age was higher (5%) than in other age groups (1-2%).

CONCLUSION

mid-GI bleeding is rare among Japanese patients with acute overt GI bleeding.

High-risk population for gastric cancer development based on serum pepsinogen status and lifestyle factors

BACKGROUND

Gastric atrophy is a major risk factor for non-cardiac gastric cancer. Serum pepsinogen status could identify people at high-risk for gastric cancer development during our previous cohort study. However, lifestyle-related factors may additionally affect this risk.

MATERIALS AND METHODS

A total of 6983 Japanese were followed up by annual endoscopy in the previous study, and 43 cases of gastric cancer including two cardiac cancers developed. In most subjects, the body length and weight were measured and a questionnaire was applied to gather information regarding life habits. The risk of non-cardiac gastric cancer development during surveillance was re-analyzed based on serum pepsinogen, sex, age, body mass index (BMI), alcohol, and smoking habit.

RESULTS

A total of 6158 subjects with 37 non-cardiac gastric cancer development (male/female = 4259/1899, mean age = 49.0, mean follow-up period = 4.79 years) were entered into analysis. In a multivariate analysis, old age (by 10 years; (odds ratio) OR, 2.8; p < .001), alcohol (weekly; OR, 2.4; p = .03), smoking (current; OR, 5.6; p = .006 and past; OR, 3.9; p = .04), and pepsinogen status ("atrophic"; OR, 6.2; p < .001) were independent risk factors, whereas BMI was not. The annual incidence of gastric cancer was 1.2% in the older subjects aged > or = 60 years with "atrophic" pepsinogen status. Moreover, it was as high as 2.9% when they had both alcohol and current smoking habits.

CONCLUSIONS

Old age, alcohol, and smoking habits additionally promoted the risk for gastric cancer in subjects with gastric atrophy.

Interleukin-10 (-819 C/T) and tumor necrosis factor-alpha (-308 G/A) gene variants influence gastritis and lymphoid follicle development

Helicobacter pylori (H. pylori) causes gastritis, development of lymphoid follicles and later monoclonal mucosa-associated lymphoid tissue (MALT) lymphoma. We evaluated the association of tumor necrosis factor (TNF)-alpha (-308 G/A) and IL-10 (-819 C/T) gene polymorphisms with gastritis and lymphoid follicle formation. H. pylori infection was detected using modified Giemsa staining and IgG anti-CagA enzyme-linked immunosorbent assay (ELISA). One hundred and thirty patients with non-ulcer dyspepsia (NUD) and 200 healthy age-matched controls were genotyped for TNF-alpha and IL-10 polymorphisms using polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP). Subjects with IL-10 -819 T allele [patients (46.5%) versus controls (35.7%), p = 0.006, OR = 1.56, 95% CI = 1.14-2.15] were at risk of gastritis. Infection with H. pylori was more often associated with lymphoid follicles formation than its absence (46% versus 22%, p = 0.009). TNF-alpha polymorphism did not influence gastritis but patients with TNF-alpha -308 A allele carriers showed >2 fold risk of lymphoid follicle formation [presence (26%) versus absence (11.25%), p = 0.029, OR = 2.8; 95% CI = 1.09-7.08]. There was a trend towards association of lymphoid follicles and TNF-alpha -308 A allele carriers with H. pylori infection than without (58.5% versus 22.2%; p = 0.064). IL-10 -819 T and TNF-alpha -308 A alleles may increase risk of gastritis and lymphoid follicle formation.

Frequencies of serum antibodies to Helicobacter pylori CagA and VacA in a Turkish population with various gastroduodenal diseases

Infection with Helicobacter pylori (H. pylori) strains secreting cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) proteins is associated with more severe gastroduodenal pathologies. However, this association varies among geographical regions and ethnic groups. We investigated the frequencies of antibodies to CagA and VacA proteins in 131 H. pylori-infected dyspeptic patients [40 duodenal ulcer (DU), 19 gastric ulcer (GU), 28 gastric cancer (GC), and 44 non-ulcer dyspepsia (NUD)] across 30 H. pylori-infected and endoscopically normal asymptomatic subjects (AS). Anti-CagA and anti-VacA antibodies were detected by Western blotting. The positivity rates of anti-CagA and anti-VacA antibodies were higher in patients with DU (92.5 and 75%), GU (89.5 and 84.2%) and GC (96.4 and 85.7%) than patients with NUD (70.5 and 50%) and AS (50 and 23.3%) (p < 0.05). CagA+ VacA+ phenotype was more frequent in patients with DU, GU and GC than patients with NUD and AS (75, 84.2, 85.7 vs. 47.7 and 20%, respectively) (p < 0.01). Our results showed that there is a significantly positive association between the presence of anti-CagA and anti-VacA antibodies and DU, GU and GC in our region.

Helicobacter pylori virulence factors in duodenal ulceration: A primary cause or a secondary infection causing chronicity

Reports from countries with a high prevalence of Helicobacter pylori (H pylori) infection do not show a proportionately high prevalence of duodenal ulceration, suggesting the possibility that H pylori cannot be a primary cause of duodenal ulceration. It has been mooted that this discrepancy might be explained by variations in the prevalence of virulence factors in different populations. The aim of this paper is to determine whether the published literature gives support to this possibility. The relevant literature was reviewed and analyzed separately for countries with a high and low prevalence of H pylori infection and virulence factors. Although virulent strains of H pylori were significantly more often present in patients with duodenal ulcer than without the disease in countries with a low prevalence of H pylori infection in the population, there was no difference in the prevalence of virulence factors between duodenal ulcer, non - ulcer dyspepsia or normal subjects in many countries, where the prevalence of both H pylori infection and of virulence factors was high. In these countries, the presence of virulence factors was not predictive the clinical outcome. To explain the association between virulence factors and duodenal ulcer in countries where H pylori prevalence is low, only two papers were found that give little support to the usual model proposed, namely that organisms with the virulence factors are more likely than those without them to initiate a duodenal ulcer. We offer an alternative hypothesis that suggests virulence factors are more likely to interfere with the healing of a previously produced ulcer. The presence of virulence factors only correlates with the prevalence of duodenal ulcer in countries where the prevalence of H pylori is low. There is very little evidence that virulence factors initiate duodenal ulceration, but they may be related to failure of the ulcer to heal.

Famotidine vs. omeprazole: a prospective randomized multicentre trial to determine efficacy in non-erosive gastro-oesophageal reflux disease

BACKGROUND

Several studies in Western countries showed that proton-pump inhibitors are superior to histamine2-receptor antagonists or placebo in the treatment of non-erosive gastro-oesophageal reflux disease. The efficacy of acid-suppressive drugs for non-erosive gastro-oesophageal reflux disease in Japan, in which the prevalence of Helicobacter pylori infection is higher compared with Western countries, is unknown.

AIM

To compare the efficacy of famotidine and omeprazole in Japanese patients with non-erosive gastro-oesophageal reflux disease by a prospective randomized multicentre trial.

METHODS

A total of 98 patients received either famotidine 20 mg b.d. (n = 48) or omeprazole once daily (n = 50). Frequency of gastro-oesophageal reflux disease symptoms and health-related quality of life were evaluated at baseline and after 4 weeks of treatment. Complete relief was defined as no gastro-oesophageal reflux disease symptoms during the 7-day interval in week 4.

RESULTS

Complete relief was achieved in 23 (48%) of patients receiving famotidine and 28 (56%) of patients treated with omeprazole. In the famotidine group, complete relief rate in H. pylori-negative patients was significantly lower than H. pylori-positive patients (35% vs. 64%). Both famotidine and omeprazole improved most scales of health-related quality of life. Omeprazole significantly improved reflux score irrespective of H. pylori infection while famotidine significantly improved reflux score in H. pylori-positive patients but not in H. pylori-negative patients.

CONCLUSIONS

Omeprazole is more effective than famotidine for the control of gastro-oesophageal reflux disease symptoms in H. pylori-negative patients, while similar efficacy is observed in H. pylori-positive patients with non-erosive gastro-oesophageal reflux disease.

Differences in clinical characteristics between patients with endoscopy-negative reflux disease and erosive esophagitis in Japan

OBJECTIVE

Helicobacter pylori infection and atrophic gastritis are inversely related to erosive esophagitis. Whether these factors affect the pathogenesis of endoscopy-negative reflux disease is not clear. We aimed to elucidate the differences in clinical characteristics between endoscopy-negative erosive disease and erosive esophagitis.

METHODS

253 subjects (89 with endoscopy-negative reflux disease and 164 with erosive esophagitis) were studied. Gastric atrophy was assessed by measurement of serum pepsinogen. Logistic regression was used to calculate the odds ratio (OR) and 95% confidence intervals (CI) of endoscopy-negative reflux disease compared with erosive esophagitis.

RESULTS

Among GERD patients, female gender (OR = 2.27, 95% CI, 1.25-4.10), smoking (OR = 0.45, 95% CI, 0.22-0.91), and the presence of hiatal hernia (OR = 0.30, 95% CI, 0.17-0.56) were significantly associated with endoscopy-negative reflux disease compared with male gender, not smoking, and absence of hiatal hernia, respectively. Body mass index (BMI) was also significantly associated with a decreased OR for endoscopy-negative reflux disease. Although H. pylori infection and gastric atrophy were significantly more common in patients with endoscopy-negative reflux disease, these associations did not persist in a multiple-adjustment model. After adjustment for gender, BMI, smoking, and hiatal hernia, a decrease in serum pepsinogen I/II ratio was significantly associated with an increased OR for endoscopy-negative reflux disease (p for trend = 0.018).

CONCLUSIONS

Female gender, low BMI, not smoking, absence of hiatal hernia, and severity of gastric atrophy were positively associated with endoscopy-negative reflux disease compared with erosive esophagitis among Japanese patients.

Effect of acid suppression therapy on development of gastric erosions after cure of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori eradication markedly improves histological inflammation and decreases peptic ulcer recurrence, but little is known about the subsequent development of gastric mucosal injury.

AIM

To investigate whether acid suppression treatment after eradication influences the development of gastric erosions.

METHODS

Eighty-one patients (gastritis or peptic ulcer) after successful H. pylori eradication were divided into two groups: 40 received an H2-blocker for 6 months (H2-blocker-positive) and 41 received no treatment (H2-blocker-negative). Endoscopy was performed before, and at 3 and 6 months after completion of eradication.

RESULTS

Cumulative prevalence of gastric erosions in the H2-blocker-positive group was significantly lower than in the H2-blocker-negative group, 25% vs. 42%, respectively. In the H2-blocker-negative group but not the H2-blocker-positive group, the cumulative prevalence of gastric erosions after eradication was higher in patients with less severe corpus atrophy or more severe corpus gastritis.

CONCLUSIONS

Development of gastric erosions after H. pylori eradication may be controlled by acid suppression treatment. Less severe atrophy or more severe gastritis in oxyntic glands before eradication may be involved in the development of gastric erosions. These results support the idea that recovery of acid secretion may be one of factors for development of gastric mucosal erosions after successful eradication.

Helicobacter pylori activates the proto-oncogene c-fos through SRE transactivation

Epidemiological studies have demonstrated a strong association between Helicobacter pylori infection and gastric cancer. However, there have been few detailed studies on the mechanism of cellular proliferation by H. pylori. Thus, we examined activation of the proto-oncogene c-fos to elucidate the underlying mechanism of cell proliferation caused by H. pylori. Activation of c-fos was evaluated in human gastric cancer cells (TMK1) by Northern blot and reporter assays with deletion analysis of the c-fos transcriptional control region. c-fos promoter activation and transcription were enhanced when cocultured with cag-positive strains. H. pylori-mediated c-fos promoter activation was inhibited by MEK1/2 inhibitor (U0126). The deletion analysis indicated that serum response element (SRE) was required for the activation of c-fos by H. pylori. In conclusion, c-fos promoter activation and transcription were enhanced through the activation of extracellular signal-regulated kinases (ERK)/mitogen-activated protein kinase (MAPK) cascade in gastric cancer cells when cocultured with H. pylori possessing intact cag PAI. SRE is required for the activation of c-fos by H. pylori. These results suggest a direct involvement of H. pylori infection in cellular proliferation, which may play a role in neoplastic transformation.

Inverse background of Helicobacter pylori antibody and pepsinogen in reflux oesophagitis compared with gastric cancer: analysis of 5732 Japanese subjects

BACKGROUND

The relationship between Helicobacter pylori and reflux oesophagitis remains controversial.

AIMS

To evaluate the relationship between H pylori and reflux oesophagitis in a large number of Japanese subjects.

SUBJECTS

A total of 5732 consecutive Japanese subjects during a health screening were enrolled.

METHODS

Gastrointestinal endoscopy was performed on all subjects. We simultaneously measured serum anti-H pylori antibody and pepsinogen as markers of H pylori infection together with gastric atrophy. The risk of reflux oesophagitis was evaluated in relation to these markers, and the results were compared with those of gastric cancer.

RESULTS

Reflux oesophagitis was found in 108 subjects. Both positivity for H pylori antibody (adjusted odds ratio (OR) 0.67 (95% confidence interval 0.45-1.0)) and "low" pepsinogen indicating gastric atrophy (OR 0.35 (0.18-0.68)) were negatively associated with reflux oesophagitis. After subjects were classified into four groups based on positivity or negativity for H pylori antibody and "low" pepsinogen, the prevalence of reflux oesophagitis showed a decreasing trend as H pylori induced gastric atrophy became more severe. The risk of gastric cancer showed an increasing trend, exactly the opposite to that of reflux oesophagitis.

CONCLUSIONS

Analysis of a large series of Japanese subjects revealed a decreasing prevalence of reflux oesophagitis in conjunction with progress of gastric atrophy induced by H pylori infection. This pattern was completely opposite to that of gastric cancer cases. A protective role of H pylori for reflux oesophagitis through the development of gastric atrophy has been suggested.

Detection of Helicobacter pylori virulence-associated genes

Helicobacter pylori is an important human pathogen and persistent colonization of the human gastric mucosa can cause severe gastrointestinal diseases. The bacterium should not be considered as a uniform organism, but as a population of closely related and yet genetically diverse bacteria. Several genes of H. pylori (such as vacA and cagA) have been identified as being virulence-associated and may have important clinical and epidemiological implications. Assessment of virulence-associated genes of H. pylori should be included in clinical and epidemiological studies as well as therapeutic trials, in order to stratify between patient groups, harboring H. pylori strains with particular virulence genotypes. Molecular determination of antibiotic resistance will be especially useful for treatment studies. Together with our increasing knowledge about the human genome, typing of H. pylori will facilitate the management of gastroenterological pathologies.

Characterization of virulence factors of mouse-adapted Helicobacter pylori strain SS1 and effects on gastric hydrophobicity

Gastric infection with Helicobacter pylori results in chronic active gastritis and in some individuals is associated with complications such as peptic ulceration and gastric cancers. A balance between bacterial factors and host responses may determine disease outcome. The mouse-adapted H. pylori strain SS1 has been utilized as a model to study disease pathogenesis. Although chronic gastritis is observed in this murine model of H. pylori infection, other complications of disease seen in the human host (such as peptic ulceration) are not identified. The objectives of this study were to characterize virulence factors of the mouse-adapted H. pylori strain SS1 and determine host responses to infection. Vacuolating cytotoxin activity of H. pylori strain SS1 was determined after incubation of HEp-2 cells with culture supernatant for 24 hr. Polymerase chain reaction was performed to detect the presence of the cagA and cagE genes. Chemokine responses from human gastric epithelial cells infected with H. pylori SS1 were assessed by measurement of the concentration of interleukin-8 in cell-free supernatants. C57BL/6 and gld mice were infected with strain SS1 or sham-infected. Eight weeks following infection, gastric tissues were obtained for histological analysis and surface hydrophobicity was measured by axisymmetric drop-shape analysis. H. pylori strain SS1 was cytotoxin negative, cagA positive, and cagE positive, but induced only a modest interleukin-8 response (684 +/- 140 pg/ml) from AGS gastric epithelial cells in comparison to a clinical isolate (4170 +/- 410 pg/ml, P < 0.0005). Increased inflammation was observed in the stomachs of H. pylori strain SS1-infected animals compared to uninfected controls. Gastritis was not associated with any disease complications. Despite mucosal inflammation, infected mice did not demonstrate alterations in gastric surface hydrophobicity (42.2 degrees +/- 2.2 degrees and 41.4 degrees +/- 3.2 degrees for C57BL/6 and gld, respectively) compared to uninfected mice (43.2 degrees +/- 2.3 degrees and 39.5 degrees +/- 1.6 degrees, respectively). In conclusion, murine infection with H. pylori SS1, which contains putative bacterial virulence factors, results in gastric inflammation. However, the mucosal changes are not associated with alterations in surface hydrophobicity. Therefore, the mouse model of infection with H. pylori, strain SS1 may not serve as an entirely appropriate model to study host factors associated with disease complications.

Neutralisation of cytotoxic vacuolating activity by serum antibodies of Helicobacter pylori-infected patients

The study involved 196 H. pylori strains and 196 serum samples taken from the same patients. H. pylori strains were investigated for the production of vacuolating cytotoxin. Antibodies to the vacuolating cytotoxin produced by H. pylori were detected in the sera samples by neutralisation assay (on Intestine 407 cells) and ELISA. Of the 196 H. pylori strains tested, 80 (40.8%) were found to express vacuolating cytotoxic activity. The titres of cytotoxic nonconcentrated broth culture filtrates ranged from 1:2 to 1:128. The vacuolating assay was positive in 37.1% strains isolated from children, and in 50% strains isolated from adults. Cytotoxin-positive H. pylori strains were found more frequently in duodenal ulcer (71%) than in chronic gastritis (35.2%) patients, and this difference was statistically significant p < 0.05. Neutralising antibodies to vacuolating cytotoxin were present in 51% and 49% of the serum samples tested by neutralisation and ELISA, respectively. Duodenal ulcer patients had antibodies to vacuolating cytotoxin more frequently (p < 0.05) than chronic gastritis patients. Antibodies to cytotoxin were detected in the serum samples from patients infected by cytotoxic (100%) and noncytotoxic (18%) H. pylori strains.

Determination of Helicobacter pylori virulence by simple gene analysis of the cag pathogenicity island

Nucleic acid amplification was performed for five loci in the cag pathogenicity island (PAI) of Helicobacter pylori (comprising cagA, the cagA promoter region, cagE, cagT, and the left end of cagII [LEC]), and gastric inflammation in patients was evaluated. Of 204 H. pylori isolates from Japanese patients (53 with peptic ulcer, 55 with gastric cancer, and 96 with chronic gastritis), 197 (96.6%) were positive for all five loci. Two isolates (1%) were negative for all five loci, and five isolates (2.4%) were positive for only cagA and LEC. These latter seven isolates were all from patients with mild chronic gastritis. Neutrophil infiltration in gastric mucosa was significantly milder in patients infected with partially or totally deleted-PAI strains than in those with intact-PAI strains. The cagE gene was a more accurate marker of an intact cag PAI than the cagA gene, and cagE seemed to be more useful in discriminating between H. pylori strains causing different rates of disease progression.

Effects of dexamethasone and FK506 on Helicobacter pylori-induced gastritis and bacterial viability in Mongolian gerbils

FK506 and dexamethasone were used to investigate whether or not immunosuppression affects H. pylori colonization and gastric mucosal damage induced by Helicobacter pylori in Mongolian gerbils. Two weeks after H. pylori infection, FK506 and dexamethasone or vehicle alone were subcutaneously administered once daily for the following 2 weeks. FK506 or vehicle alone was administered subcutaneously once daily for 5 weeks (1 week before and 4 weeks after infection). In H. pylori-infected animals for 4 weeks, hemorrhagic erosions and inflammatory responses (neutrophil infiltration and lymphoid follicle formation) were induced in gastric mucosa at an incidence of 100%. Both FK506 and dexamethasone administered for 2 weeks markedly reduced such mucosal changes. In these animals, H. pylori viability in the stomach was significantly elevated. FK506 administered for 5 weeks also significantly inhibited the hemorrhagic erosions, edema and neutrophil infiltration in the stomach. H. pylori viability was slightly elevated as compared with the control. It was concluded that the host immune responses might play dual roles both by deteriorating gastritis induced by H. pylori and by protecting against H. pylori infection in its early stage.

Virulence factors of Helicobacter pylori responsible for gastric diseases in Mongolian gerbil

Helicobacter pylori infection induces various gastroduodenal diseases. We examined the role of two genes, vacA and cagE, in the gastric pathogenesis induced by H. pylori using a long-term (62 wk) animal model. Reportedly, both genes are associated with the virulence of H. pylori: vacA encodes vacuolating cytotoxin, and cagE, with other genes in the cag pathogenicity islands, encodes a type IV secretion system. Mongolian gerbils were challenged in this study by a wild-type TN2 strain and its isogenic mutants of cagE or vacA. The wild-type and vacA mutants induced severe gastritis, whereas cagE mutants induced far milder changes. Gastric ulcer was induced at the highest rate (22/23) by the wild-type TN2, followed by the vacA mutant (19/28). No ulcer was found in the gerbils infected with the cagE mutant (0/27) or in controls (0/27). Intestinal metaplasia was also found in the gerbils infected with the wild-type (14/23) or vacA mutant (15/28). Gastric cancer developed in one gerbil with wild-type infection and in one with vacA mutant infection. In conclusion, the knocking out of the cagE gene deprived wild-type H. pylori of the pathogenicity for gastritis and gastric ulcer, suggesting that the secretion system encoded by cag pathogenicity island genes plays an essential role.

Analysis of Helicobacter pylori vacA gene and serum antibodies to VacA in Japan

Vacuolating cytotoxin, VacA, is one of the most important pathogenetic factors produced by Helicobacter pylori. However, it is not clear whether the diversity in disease outcome may be ascribed to variations in strain and/or to the host responses to virulence factors. In this study, we analyzed the vacA middle region sequence among 65 Japanese isolates to clarify the variation in strain and assayed antibody titer to VacA by ELISA using purified VacA to evaluate the host response to cytotoxin. The nucleotide sequence identities compared among Japanese isolates were 92.8 +/- 3.56%, and compared to 88.3 +/- 2.89% in tox+ strains reported in GenBank. Positive correlation was found between the antibody titers and the severity of atrophic change of the stomach. In Japan the nucleotide sequences of the vacA middle region were highly homologous and genetically closer to tox+ strains. Antibody titers and host response to cytotoxin may be associated with atrophy of the stomach.

Role of antigastric autoantibodies in chronic Helicobacter pylori infection

In recent studies a significant association between H. pylori infection and antigastric autoimmunity has been reported. Antigastric autoantibodies can be found in more than 30% of infected patients. Two distinct binding patterns of these autoantibodies have been described, first at the luminal membrane of the foveolar epithelium, and second at the canaliculi membranes of the parietal cells in the body mucosa. The latter type of autoantibodies correlates with histologic and clinical parameters of gastric mucosa atrophy. The gastric H,K-ATPase, which is known to be the autoimmune target in classical autoimmune gastritis, also represents a major autoantigen in atrophic H. pylori gastritis. Molecular mimicry between H. pylori and the host does not seem to be responsible for the generation of this type of autoreactivity. The development of antigastric autoantibodies may be a relevant host factor which contributes to the final clinical outcome of chronic H. pylori gastritis.

Recurrence of gastric ulcer dependent upon strain differences of Helicobacter pylori in urease B gene

To evaluate the role of different strains of Helicobacter pylori on the recurrence of gastric ulcer, we divided H. pylori into four types (I, II, III, and IV) according to the urease B gene using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The relationship between the recurrence of gastric ulcer and the prevalence of H. pylori types was studied in 32 patients with benign open gastric ulcers using upper gastrointestinal endoscopy. The rate of recurrence was significantly lower in patients with type II than in patients with types I, III, and IV (P<0.05). Using Mongolian gerbils, an animal model of H. pylori infection, we also showed that the occurrence of gastric ulceration following restraint water-immersion stress was significantly lower in type II compared with types I and III. These data indicate that in the context of ulcer recurrence, it is not necessary to eradicate H. pylori during infection with type II.

Vacuolating cytotoxin (vacA) alleles of Helicobacter pylori comprise two geographically widespread types, m1 and m2, and have evolved through limited recombination

Vacuolating cytotoxin (vacA) alleles of Helicobacter pylori vary, particularly in their mid region (which may be type m1 or m2) and their signal peptide coding region (type s1 or s2). We investigated nucleotide diversity among vacA alleles in strains from several locales in Asia, South America, and the USA. Phylogenetic analysis of vacA mid region sequences from 18 strains validated the division into two main groups (m1 and m2) and showed further significant divisions within these groups. Informative site analysis demonstrated one example of recombination between m1 and m2 alleles, and several examples of recombination among alleles within these groups. Recombination was not sufficiently extensive to destroy phylogenetic structure entirely. Synonymous nucleotide substitution rates were markedly different between regions of vacA, suggesting different evolutionary divergence times and implying horizontal transfer of genetic elements within vacA. Non-synonymous/synonymous rate ratios were greater between m1 and m2 sequences than among m1 sequences, consistent with m1 and m2 alleles encoding functions fitting strains for slightly different ecological niches.

CagA and VacA: virulence factors of Helicobacter pylori in Thai patients with gastroduodenal diseases

BACKGROUND

The aim of this study was to assess the seroprevalence of cytotoxin-associated gene A (cagA) and vacuolating cytotoxin gene A (vacA) of Helicobacter pylori in selected Thai populations with specific gastroduodenal diseases.

MATERIALS AND METHODS

The immunoblot assay was used to detect serum antibodies against CagA and VacA obtained from the following patients: 87 cases of nonulcer dyspepsia (NUD), 61 cases of duodenal ulcer (DU), 49 cases of gastric ulcer (GU), and 10 cases of gastric cancer (GC).

RESULTS

Serum antibodies to CagA were detected in 75.4% of all patients (70. 1% of NUD, 78.7% of DU, 77.6% of GU, and 90% of GC). Although the prevalence of CagA seropositivity in GC patients was higher than in the other three groups, the difference was not statistically significant (p >.05).

CONCLUSIONS

The high seroprevalence of the CagA-positive H. pylori strain in patients with peptic ulcer, GC, and NUD indicates that this strain is common in Thai patients with gastroduodenal diseases. Furthermore, phenotypic classification of H. pylori into type 1 (CagA-positive, VacA-positive) and type 2 (CagA-negative, VacA-negative) is not a useful marker for screening patients with severe forms of gastroduodenal diseases.

VacA genotyping directly from gastric biopsy specimens and estimation of mixed Helicobacter pylori infections in patients with duodenal ulcer and gastritis

BACKGROUND

The vacA genotypes and the cagA gene status were investigated in 80 Helicobacter pylori-infected patients with duodenal ulcer (DU) and 49 with gastritis only.

METHODS

Lysates of gastric biopsy specimens were used directly for polymerase chain reaction-based detection.

RESULTS

The ml subtype was found in 36% and 31% and the m2 in 36% and 46% of specimens from patients with DU and gastritis, respectively (P > 0.05). In 15% of samples the midregion remained unclassified. The prevalence rate of s1 subtypes was higher in cases of DU (69%) than in gastritis (43%) (P < 0.0001); the opposite correlation was observed for s2. The cagA gene was detected in 80% of patients with DU and in 52% of those with gastritis (P < 0.0001). Infections with multiple H. pylori strains exceeded 50% in both groups.

CONCLUSIONS

These results suggest that vacA s1 genotype and cagA+ status are associated with higher DU prevalence and that mixed H. pylori infections are very common in our geographic region.

Distinct variants of Helicobacter pylori cagA are associated with vacA subtypes

The diversity of the cytotoxin-associated gene (cagA) of Helicobacter pylori was analyzed in 45 isolates obtained from nine countries. We examined variation in the 5' end of the cagA open reading frame as determined by PCR and sequencing. Phylogenetic analysis revealed the existence of at least two distinct types of cagA. One variant (cagA1) was found exclusively in strains from Europe, the United States, and Australia, whereas a novel variant (cagA2) was found in strains from East Asia. The greatest diversity between cagA1 and cagA2 was found in the first 20 amino acids of the cagA open reading frame, where several consistent insertions or deletions were observed. Additional cagA sequence variants that could be classified as separate subtypes were found in two of three Peruvian and in five of seven U.S. strains tested. The calculated isoelectric point of the first 154 amino acids of the cagA1 variants (7.52 +/- 1.54) was significantly higher than that of the first 154 amino acids of the cagA2 variants (5.61 +/- 0.94; P < 0.001). Most cagA2 strains contained vacA subtype s1c (P < 0.001), and in vacA m1 strains cagA1 was more frequently observed than cagA2. These results show the epidemiological relationship between cagA and vacA at the subtype level and indicate the existence of distinct H. pylori lineages that are not uniformly distributed over the globe.

CagA and cytotoxicity of Helicobacter pylori are not markers of peptic ulcer in Japanese patients

BACKGROUND

The infection with cagA-positive Helicobacter pylori strains is reported to be associated with peptic ulcer disease in developed countries, but it is controversial in Asia. To investigate the relationship between the virulence factors of H. pylori and peptic ulcer disease in Japan, we compared these between ulcer and nonulcer patients.

MATERIALS AND METHODS

Seventy-four strains of clinically isolated H. pylori obtained from 22 gastric ulcer (GU), 23 duodenal ulcer (DU), and 29 chronic gastritis (CG) patients were studied. The presence of vacA and cagA gene was examined by polymerase chain reaction method using two different primer sets. We evaluated the proliferation-inhibiting and lethal cytotoxicity of culture supernatants using the alamarBlue assay.

RESULTS

The vacA gene was identified in all strains by the original primers. S1 strains were found in 90.9% (20/22) from GU, 95.7% (22/23) from DU, and 96.6% (28/29) from CG patients. The prevalence of cagA gene determined by the first, and second primers was 90.9% (20/22), 90.9% (20/22) in strains from GU, 87.0% (20/23), 91.3% (21/23) from DU, and 86.2% (25/29), 89.7% (26/29) from CG patients, respectively. The supernatant showed cytolethal effect in 95.5% (21/22) of strains from GU, in 100% (23/23) from DU, and in 93.1% (27/29) from CG patients. There was no significant difference in the prevalence of the virulence factors between H. pylori strains isolated from patients with peptic ulcers and those with chronic gastritis.

CONCLUSIONS

These results indicate that cagA gene status and the proliferation-inhibiting and lethal cytotoxicity of supernatant are not reliable markers of ulcerogenicity of H. pylori in Japanese patients.

Clinical relevance of the cagA, vacA, and iceA status of Helicobacter pylori

BACKGROUND & AIMS

Clinical outcome of Helicobacter pylori infection may be associated with specific virulence-associated bacterial genotypes. The aim of this study was to assess the relationships between H. pylori cagA, vacA, and iceA status and severity of disease.

METHODS

Gastric biopsy specimens from 94 patients in The Netherlands were analyzed by polymerase chain reaction and reverse hybridization.

RESULTS

cagA was present in 63 (67%) of 94 cases and was associated with peptic ulcer disease (P = 0.0019). vacA geno-types s1a/m1, s1b/m2, s1b/m1, s1b/m2, and s2/m2 were found in 36.2%, 23.4%, 2.1%, 5.3%, and 20.2%, respectively. Ten isolates (10.6%) contained multiple vacA genotypes. The presence of peptic ulcers was associated with type s1 strains (P = 0.0006) but not with the m type (P = 0.2035). cagA and vacA s1 were strongly associated (P < 10(-5)). iceA1 was found in 53 (56.4%) and iceA2 in 25 (26.6%) of the 94 cases. In 14 isolates (14.9%), both iceA alleles were found, and 2 (2.1%) were negative for both iceA1 and iceA2. iceA1 was also associated with peptic ulcer disease (P = 0.0042). The iceA allelic type was independent of the cagA and vacA status.

CONCLUSIONS

vacA s1, cagA, and iceA1 are markers of H. pylori strains that are more likely to lead to ulcer disease.

Major virulence factors, VacA and CagA, are commonly positive in Helicobacter pylori isolates in Japan

BACKGROUND

VacA and CagA proteins have been reported to be major virulence factors of Helicobacter pylori. However, antibodies against these proteins are frequently found in the sera of Japanese patients regardless of their gastroduodenal status.

AIM

To evaluate the expression of VacA and CagA proteins by H pylori strains isolated in Japan.

METHODS

By using specific antibodies raised against recombinant VacA and CagA proteins, the expression of VacA and CagA was evaluated in 68 H pylori strains isolated from Japanese patients; a vacuolating assay and genotyping of the vacA gene were also used in the evaluation. The results in analysed in relation to the gastroduodenal diseases of the hosts.

RESULTS

VacA and CagA proteins were expressed in 59/68 (87%) and in 61/68 (90%) isolates respectively. The vacuolating assay was positive in 57/68 (84%) isolates, indicating that most immunologically VacA positive strains produced active cytotoxin. The prevalence of infection with strains expressing CagA and positive for vacuolating activity (Type I) was very high, 54/68 (79%), irrespective of the gastroduodenal status of the host.

CONCLUSION

Most H pylori isolates in Japan are positive for vacuolating cytotoxin and CagA, and thus these virulence factors cannot be used as markers to discern the risk of developing serious gastroduodenal pathologies in the hosts. However, the high prevalence of infection with strains positive for vacuolating cytotoxin and CagA may contribute to the characteristics of H pylori infection in Japan.

High seropositivity of anti-CagA antibody in Helicobacter pylori-infected patients irrelevant to peptic ulcers and normal mucosa in Japan

CagA-positive H. pylori is reported to be associated with gastroduodenal disease in Western countries. To evaluate the relationship between CagA and disease, cloning of the entire cagA gene (3771 bp), insertion of a partial fragment (1272 bp) into an expression vector, purification of the recombinant protein, production of an antibody against the recombinant CagA protein through rabbits, and use of the recombinant CagA protein as an antigen, detection of the anti-CagA antibody by western blotting were all performed. Sera of 132 H. pylori-infected patients undergoing endoscopy were studied. Anti-CagA antibodies were detected in 90%, 87%, 90%, 94%, and 93% of patients with gastric ulcer (N = 34), duodenal ulcer (N = 27), chronic gastritis (N = 31), gastric cancer (N = 17), and normal mucosa (N = 15), respectively. High seropositivity of anti-CagA antibody even in individuals with normal mucosa indicated that CagA may not be a unique marker for disease by H. pylori infection in Japan.