IgG antibody titer against Helicobacter pylori correlates with presence of cytotoxin associated gene A-positive H. pylori strains

An Evaluation of Urease A Subunit Nanocapsules as a Vaccine in a Mouse Model of Helicobacter pylori Infection

Using removable silica templates, protein nanocapsules comprising the A subunit of Helicobacter pylori urease (UreA) were synthesised. The templates were of two sizes, with solid core mesoporous shell (SC/MS) silica templates giving rise to nanocapsules of average diameter 510 nm and mesoporous (MS) silica templates giving rise to nanocapsules of average diameter 47 nm. Both were shown to be highly monodispersed and relatively homogenous in structure. Various combinations of the nanocapsules in formulation were assessed as vaccines in a mouse model of H. pylori infection. Immune responses were evaluated and protective efficacy assessed. It was demonstrated that vaccination of mice with the larger nanocapsules combined with an adjuvant was able to significantly reduce colonisation.

Trends in the prevalence of atrophic gastritis and Helicobacter pylori infection over a 10‑year period in Japan: The ROAD study 2005‑2015

Few large population-based studies have examined the prevalence of atrophic gastritis (AG) and Helicobacter pylori infection in Japan. The purpose of the present study was to estimate the prevalence of AG and H. pylori infection by age, in addition to investigating their change rates from 2005 to 2016 in Japan using data from a large population-based cohort. A total of 3,596 participants [1,690 in the baseline survey (2005-2006) and 1,906 at the fourth survey (2015-2016)] aged 18 to 97 years were included in the cohort. The prevalence of AG and H. pylori infection were examined at baseline and in the fourth survey based on serological tests for the H. pylori antibody titer and pepsinogen levels. The prevalence of AG and H. pylori infection were 40.1% (men, 44.1%; women, 38.0%) and 52.2% (men, 54.8%; women, 50.8%), respectively, at baseline. AG seropositivity rates showed a significant decrease from 40.1 to 25.8% in 10 years. H. pylori seropositivity rates decreased significantly from 52.2 to 35.5% in 10 years. Stratified for age, the prevalence of AG showed an increasing trend with age, whereas the prevalence of H. pylori infection increased with aging, except for in the elderly group, showing an inverted U-shaped association. In this population-based, cross-sectional study with a 10-year interval survey, the prevalence of AG and H. pylori infection decreased significantly. This change may influence the prevalence of H. pylori-related diseases, including extra-gastric disorders associated with H. pylori-induced systemic subclinical inflammation and hypochlorhydria, such as colorectal neoplasia and arteriosclerosis.

Cancer development based on chronic active gastritis and resulting gastric atrophy as assessed by serum levels of pepsinogen and Helicobacter pylori antibody titer

Our study investigated the relationship between gastric cancer development and activity of Helicobacter pylori-associated chronic gastritis or the resulting chronic atrophic gastritis (CAG). A cohort of 4,655 healthy asymptomatic subjects, in whom serum pepsinogen (PG) and H. pylori antibody titer had been measured to assess the activity and stage of H. pylori-associated chronic gastritis, was followed for up to 16 years, and cancer development was investigated. In subjects with a serologically diagnosed healthy stomach (H. pylori-negative/CAG-negative), cancer incidence rate was low, at 16/100,000 person-years. With the establishment of H. pylori infection and progression of chronic gastritis, significant stepwise cancer risk elevations were seen from CAG-free subjects (H. pylori-positive/CAG-negative) [hazard ratio (HR) = 8.9, 95% confidence interval (CI) = 2.7-54.7] to subjects with CAG (H. pylori-positive/CAG-positive) (HR = 17.7, 95% CI = 5.4-108.6) and finally to subjects with metaplastic gastritis (H. pylori-negative/CAG-positive) (HR = 69.7, 95% CI = 13.6-502.9). In H. pylori-infected CAG-free subjects, significantly elevated cancer risk was observed in the subgroup with active inflammation-based high PG II level or potent immune response-based high H. pylori antibody titer; the former was associated with a particularly high risk of diffuse-type cancer, and both subgroups showed high cancer incidence rates of around 250/100,000 person-years, comparable to that in subjects with CAG. No such risk elevation was observed in H. pylori-infected subjects with CAG. These results clearly indicate that gastric cancer develops mainly from the gastritis-atrophy-metaplasia-cancer sequence and partly from active inflammation-based direct carcinogenesis, and that serum levels of PG and H. pylori antibody titer provide indices of cancer development in H. pylori-infected subjects.

Altered mucosal DNA methylation in parallel with highly active Helicobacter pylori-related gastritis

BACKGROUND

Chronic inflammation triggered by Helicobacter pylori causes altered DNA methylation in stomach mucosae, which is deeply involved in gastric carcinogenesis. This study aimed to elucidate the correlation between altered mucosal DNA methylation levels and activity of H. pylori-related gastritis, because inflammatory activity shows particular correlations with the development of diffuse-type cancer.

METHODS

Methylation levels in stomach mucosae of 78 healthy volunteers were determined by real-time methylation-specific PCR or bisulfite pyrosequencing. Examined loci were the promoter CpG islands of six genes (FLNc, HAND1, THBD, p41ARC, HRASLS, and LOX) and the CpG sites of non-coding repetitive elements (Alu and Satα) that are reportedly altered by H. pylori infection. Activity of H. pylori-related gastritis was evaluated using two serum markers: H. pylori antibody titer and pepsinogen II.

RESULTS

Methylation levels of the six CpG islands were consistently increased, and those of the two repetitive elements were consistently decreased in a stepwise manner with the activity of gastric inflammation as represented by serum marker levels. Each serum marker level was well correlated with the overall DNA methylation status of stomach mucosa, and these two serologic markers were additive in the detection of the mucosa with severely altered DNA methylation.

CONCLUSIONS

Alteration in mucosal DNA methylation level was closely correlated with activity of H. pylori-related gastritis as evaluated by serum markers. The observed correlation between altered DNA methylation levels and activity of H. pylori-related gastritis appears to be one of the relevant molecular mechanisms underlying the development of diffuse-type cancer.

Development of gastric cancer in nonatrophic stomach with highly active inflammation identified by serum levels of pepsinogen and Helicobacter pylori antibody together with endoscopic rugal hyperplastic gastritis

This study aimed to elucidate groups at high risk of developing cancer among patients with serologically identified Helicobacter pylori infection and nonatrophic stomach. Annual endoscopy was performed for a mean of 5.4 years in 496 asymptomatic middle-aged men who were H. pylori antibody-positive and pepsinogen (PG) test-negative. Subjects were stratified according to the activity of H. pylori-associated gastritis measured by serum levels of PG and H. pylori antibody, and/or by endoscopic findings of rugal hyperplastic gastritis (RHG), and cancer development was investigated. During the study period, seven cases of cancer developed in the cohort (incidence rate, 261/100,000 person-years), with 85.7% developing in the group showing a PGI/II ratio ≤ 3.0, reflecting active inflammation-based high PGII levels. Cancer incidence was significantly higher in this group (750/100,000 person-years) than in groups with less active gastritis. Furthermore, cancer incidence for this group was significantly higher in the subgroup with high H. pylori antibody titers than in the low-titer subgroup. Meanwhile, endoscopic findings revealed that 11.7% of subjects showed RHG reflecting localized highly active inflammation, and cancer risk was significantly higher in patients with RHG than in patients without. Combining the two serum tests and endoscopic examination for RHG allowed identification of subjects with more active gastritis and higher cancer risk. No cancer development was observed in these high-risk subjects after H. pylori eradication. Subjects with highly active gastritis identified by the two serological tests and endoscopic RHG constitute a group at high risk of cancer development with H. pylori-infected nonatrophic stomach.

Comparative study of serology and histology based detection of Helicobacter pylori infections: a large population-based study of 7,241 subjects from China

Two detection methods for H. pylori infections, i.e. serological antibody titer measurements by Hp-ELISA and histological scoring by HE staining, have been compared to investigate the relationship between the diagnosis methods, to clarify the application scope of each diagnosis method and to determine its influencing factors. In the 7,241 subjects who participated in gastric cancer screening, H. pylori infection rate was 70.14% by the Hp-HE method and 41.87% by the Hp-ELISA method when 34EIU was recognized as the cut-off value. The IgG titers increased with the elevation of HE scores; however, the two methods were not closely correlated among those in different gastric disease status. Age, gender and drinking status did not have significant impact on the relationship between the two methods; however, smoking status seemed to significantly influence the correlation of the two diagnosis methods. In conclusion, it was necessary to reevaluate the cut-off value when using ELISA test kits in different population groups. In most cases, the results of two H. pylori infection diagnosis methods show high correlation. However, this relationship can be affected by smoking and gastric diseases status. Additionally, the dynamic change of H. pylori antibody titers is an indicator of gastric disease development.

Advances in research on Helicobacter pylori virulence factors

Helicobacter pylori (H. pylori) infection is a common chronic infectious disease in the world. It can lead to several divergent clinical diseases, such as chronic gastritis, duodenal ulcer, mucosa-associated lymphoid tissue lymphoma and gastric adenocarcinoma. These divergent clinical diseases are caused through complex mechanisms involving interaction between the bacterium and host. Recent investigations of virulence pathogenic factors have provided more information to reveal the pathogenic mechanism of H. pylori infection. Here, we will review the recent advances in research on various H. pylori virulence factors, such as CagA, VacA, BabA, SabA, OipA and DupA.

Serum antibodies positivity to 12 Helicobacter pylori virulence antigens in patients with benign or malignant gastroduodenal diseases--cross-sectional study

AIM

To investigate the association of gastric histological and endoscopic findings in patients with Helicobacter pylori (H. pylori), according to presence of seropositivity to 12 bacterial virulence antigens.

METHODS

This is a cross-sectional single-center study of 360 consecutive outpatients referred in the period of one year to upper gastrointestinal endoscopy because of dyspeptic complaints. Patients sera were tested by Western blot method to determine the presence of serum antibodies to bacterial virulence antigens--p120 (CagA--cytotoxin-associated antigen), p95 (VacA - vacuolating cytotoxin), p67 (FSH--flagellar sheath protein), p66 (UreB--urease enzyme heavy subunit), p57 (HSP homologue--heath shock protein homologue), p54 (flagellin), p33, p30 (OMP--outer membrane protein), p29 (UreA--urease enzyme light subunit), p26, p19, and p17. Upper gastrointestinal endoscopy was performed, endoscopic diagnosis recorded, and 4 mucosal biopsy samples were obtained and assessed according to Updated Sydney protocol.

RESULTS

The sera of 207 patients were analyzed. Thirty patients had gastric adenocarcinoma, 126 peptic ulcers, and 51 normal finding. p120 (CagA) seropositivity was significantly more often present in patients with higher activity grade in the antrum (P = 0.025), p30 in patients with greater inflammation in the antrum (P = 0.025) and the corpus (P = 0.010), p33 in patients with greater inflammation in the corpus (P = 0.050), and p19 (OMP) in patients with lower intestinal metaplasia grades in the corpus (P = 0.025). Seroreactivity to all other bacterial proteins showed no association with the histological status of the stomach mucosa. Except for the seropositivity to protein p95 (VacA), which was more often present in patients with duodenal ulcer (P = 0.006), there was no difference in seroreactivity to other bacterial proteins and upper gastrointestinal endoscopic findings.

CONCLUSIONS

p120 (CagA), p33, p30 (OMP), and p19 (OMP) seropositivity was more often present in patients with higher grades of the histological parameters of gastritis and seropositivity to protein p95 (VacA) with endoscopic presence of duodenal ulcer. Histological parameters of gastritis are more associated with bacterial virulence than endoscopic findings.

Serum- and animal tissue-free medium for transport and growth of Helicobacter pylori

The important human gastric pathogen Helicobacter pylori is the subject of many studies, and as a consequence it is frequently being transported between national and international laboratories. Unfortunately, common bacterial growth and transport media contain serum- and animal tissue-derived materials, which carry the risk of spreading infectious diseases. We have therefore developed a growth and transport medium for H. pylori, designated 'Serum- and Animal Tissue-Free Medium' (SATFM), which does not contain serum- or animal tissue-derived components. SATFM supported growth of H. pylori isolates to similar levels as obtained with serum-supplemented Brucella medium, and SATFM with 0.5% agar supported transport and storage of H. pylori strains, as 4/4 reference strains and 11/11 clinical isolates survived for at least 3 days at room temperature in SATFM, with some strains (2/15) even surviving for up to 7 days. In conclusion, SATFM can be used both as transport and growth medium for H. pylori. The formulation of SATFM may allow its use in international transport of H. pylori, and may also allow certified use in immunization studies requiring growth of H. pylori and other bacterial pathogens.

Inhibitory effect of etodolac, a selective cyclooxygenase-2 inhibitor, on stomach carcinogenesis in Helicobacter pylori-infected Mongolian gerbils

The effect of the selective COX-2 inhibitor, etodolac, on Helicobacter pylori (Hp)-associated stomach carcinogenesis was investigated in Mongolian gerbils (MGs). Hp-infected MGs were fed for 23 weeks with drinking water containing 10 ppm N-methyl-N-nitrosourea. They were then switched to distilled water and placed on a diet containing 5-30 mg/kg/day etodolac for 30 weeks. We found that etodolac dose-dependently inhibited the development of gastric cancer, and no cancer was detected at a dose of 30 mg/kg/day. Etodolac did not affect the extent of inflammatory cell infiltration or oxidative DNA damage, but it significantly inhibited mucosal cell proliferation and dose-dependently repressed the development of intestinal metaplasia in the stomachs of Hp-infected MGs. These results suggest that COX-2 is a key molecule in inflammation-mediated stomach carcinogenesis and that chemoprevention of stomach cancer should be possible by controlling COX-2 expression or activity.

TheHelicobacter pyloriplasticity region locusjhp0947–jhp0949is associated with duodenal ulcer disease and interleukin-12 production in monocyte cells

Colonization with Helicobacter pylori always results in chronic gastritis, which is controlled by infiltration of mononuclear cells and the subsequent release of cytokines like interleukin (IL)-12. To identify H. pylori factors involved in inducing cytokine production in mononuclear cells, a random H. pylori mutant library was screened for the inability to induce IL-12 production in monocyte THP-1 cells. Of the 231 random mutants screened, one mutant (M1) showed a consistent twofold decrease in the amount of IL-12 induction compared to the parental strain 1061 (P <0.01). Further characterization of mutant M1 revealed that the kanamycin resistance cassette had integrated in the jhp0945 gene, which is situated in an H. pylori strain-specific plasticity region. Three reference strains possessing this plasticity region induced significantly higher amounts of IL-12 when compared to the H. pylori 26695 reference strain, which does not possess this plasticity region. The role in disease outcome of jhp0945 as well as the neighbouring plasticity region genes jhp0947 and jhp049 was assessed in a Dutch population cohort. Firstly, the presence of jhp0947 was completely linked with that of jhp0949 and was roughly associated with jhp0945 (P=0.072), but not with the cag pathogenicity island (PAI) (P=0.464). The presence of the jhp0947 and jhp0949 genes, but not of jhp0945, was significantly associated with duodenal ulcer disease when compared to gastritis (P=0.027). Therefore, the jhp0947-jhp0949 locus may be a novel putative H. pylori marker for disease outcome independent of the cag PAI.

The stress-induced hsp12 gene shows genetic variation among Helicobacter pylori strains

The transcriptional regulation, genetic variation and clinical relevance of the strain-specific hsp12 gene of the human gastric pathogen Helicobacter pylori were investigated. Although the transcription of the hsp12 gene in H. pylori strain 1061 was induced by growth under iron-, pH- and temperature-stress conditions, the gene was not essential for growth under these stress conditions. The locus containing the hsp12 gene showed considerable genetic variation. A total of eight different strain-specific alleles were identified, of which three are mosaic variants of the hsp12 gene and five that are unrelated to the hsp12 gene. The hsp12 locus of six paired sets of strains obtained from patients with 7-10-year time intervals remained unaltered, indicating that genetic variation does not occur during chronic infection. No significant association was found between the presence of a hsp12 gene and peptic ulcer disease in clinical isolates obtained from 26 patients. The stress-regulated, strain-specific hsp12 genes may be involved in adaptation of individual H. pylori strains to their specific hosts, and contribute to long-term colonization of the gastric niche.

Prolonged use of proton pump inhibitors, CagA status, and the outcome of Helicobacter pylori gastritis

GOALS AND BACKGROUND

To assess whether prolonged use of proton pump inhibitors (PPIs) in patients infected with Helicobacter pylori has adverse effects on gastritis.

STUDY

We studied 34 H. pylori-positive individuals with reflux esophagitis, Barrett esophagus, or nonulcer dyspepsia. Half of them were on maintenance treatment with PPIs (mean, 8 years) and half were not.H. pylori and CagA status were tested serologically. Gastric biopsies were classified histopathologically by the updated Sydney classification.

RESULTS

Proton pump inhibitors in H. pylori gastritis are associated with significantly less antral inflammation and lower H. pylori density, regardless of CagA status. There was a tendency toward more antral atrophy in patients with the CagA strain who were undergoing maintenance treatment with PPIs (p = 0.08), but there was an opposite tendency in CagA-negative individuals (p = 0.08). Intestinal metaplasia was seen more frequently in CagA-positive, treated individuals (p = 0.028).

CONCLUSIONS

These findings support the hypothesis that CagA status is important in the progression to atrophy and that maintenance treatment with PPIs accelerate this progression, while reducing inflammatory infiltration.

Colonisation density and topographic localisation of Helicobacter pylori do not depend on the cagA status

AIMS

To explore the correlation between the cagA status of Helicobacter pylori and the density and topographic localisation of H pylori.

METHODS

Gastric antral biopsy specimens were taken from 716 consecutive patients, including 293 H pylori positive patients (124 men, 169 women; mean age, 52.6 years; range, 12-87). A serum sample was taken for determination of IgG anti-CagA antibodies (sensitivity of 94.4% and specificity of 92.5%). The density of H pylori was assessed semiquantitatively (grades I-IV) in biopsy specimens stained with the modified Giemsa stain. Topographic localisation was classified as follows: score A, H pylori closely attached to the mucosa; score B, H pylori attached to the mucosa and in the mucus; and score C, H pylori solely in the mucus.

RESULTS

CagA antibodies were present in 154 (52.5%) of the patients. There was no significant difference in colonisation density and cagA status: grade I, 23 (14%); grade II, 78 (50.6%); grade III, 42 (27.5%); and grade IV, 11 (7.2%) in the cagA(+) strains and 29 (21.2%), 57 (40.8%), 38 (27%), and 15 (11%), respectively, in the cagA(-) strains. There was no difference in topographic localisation between cagA(+) and cagA(-)H pylori. Mean anti-CagA titres were 0.84, 0.84, 0.89, and 0.73 in patients with grades I-IV bacterial density, respectively.

CONCLUSION

Antibody titres do not correlate with H pylori density and there is no difference in density between cagA(+) and cagA(-)H pylori strains. In addition there is no difference in topographic localisation between cagA(+) and cagA(-) H pylori strains.