Enhanced M1 macrophage polarization in human helicobacter pylori-associated atrophic gastritis and in vaccinated mice

Background

Infection with Helicobacter pylori triggers a chronic gastric inflammation that can progress to atrophy and gastric adenocarcinoma. Polarization of macrophages is a characteristic of both cancer and infection, and may promote progression or resolution of disease. However, the role of macrophages and their polarization during H. pylori infection has not been well defined.

Methodology/Principal Findings

By using a mouse model of infection and gastric biopsies from 29 individuals, we have analyzed macrophage recruitment and polarization during H. pylori infection by flow cytometry and real-time PCR. We found a sequential recruitment of neutrophils, eosinophils and macrophages to the gastric mucosa of infected mice. Gene expression analysis of stomach tissue and sorted macrophages revealed that gastric macrophages were polarized to M1 after H. pylori infection, and this process was substantially accelerated by prior vaccination. Human H. pylori infection was characterized by a mixed M1/M2 polarization of macrophages. However, in H. pylori-associated atrophic gastritis, the expression of inducible nitric oxide synthase was markedly increased compared to uncomplicated gastritis, indicative of an enhanced M1 macrophage polarization in this pre-malignant lesion.

Conclusions/Significance

These results show that vaccination of mice against H. pylori amplifies M1 polarization of gastric macrophages, and that a similar enhanced M1 polarization is present in human H. pylori-induced atrophic gastritis.     

Involvement of Aquaporin 3 in Helicobacter pylori-Related Gastric Diseases

Background

Gastric cancer is one of the most common and lethal malignant cancers worldwide, and numerous epidemiological studies have demonstrated that Helicobacter pylori (H. pylori) infection plays a key role in the development of gastric carcinomas. Our previous studies showed that aquaporin 3 (AQP3) is overexpressed in gastric carcinoma and promotes the migration and proliferation of human gastric carcinoma cells, suggesting that AQP3 may be a potentially important determinant of gastric carcinoma. However, the role of AQP3 in H. pylori carcinogenesis is unknown.

Methods

The AQP3 protein and H. pylori were detected in human gastric tissues by immunohistochemistry and modified Giemsa staining respectively. AQP3 knockdown was obtained by small interfering (si) RNA. Western blot assays and RT-PCR were used to evaluate the change of AQP3 in the human gastric cancer AGS and SGC7901 cell lines after co-culture with H. pylori. Sprague Dawley rats were orally inoculated with H. pylori to establish a rat model colonized by H. pylori.

Results

The present study found that AQP3 expression correlated with H. pylori infection status in gastric cancer tissues and corresponding normal mucosa, and H. pylori co-culture upregulated AQP3 expression in human gastric adenocarcinoma cells in vitro via the extracellular signal-regulated kinase signaling pathway. H. pylori infection also increased AQP3 expression in gastric mucosa colonized by H. pylori in a Sprague Dawley rat model.

Conclusions

These findings provide further information to understand the mechanism of H. pylori carcinogenesis and a potential strategy for the treatment of H. pylori-associated gastric carcinoma.     

Dual roles of CagA protein in Helicobacterpylori-induced chronic gastritis in mice

Cytotoxin-associated gene A (CagA) acts directly on gastric epithelial cells. However, the roles of CagA in host adaptive immunity against Helicobacter pylori (H. pylori) infection are not fully understood. In this study, to investigate the roles of CagA in the development of H. pylori-induced chronic gastritis, we used an adoptive-transfer model in which spleen cells from C57BL/6 mice with or without H. pylori infection were transferred into RAG2^−/− mice, with gastric colonization of either CagA⁺H. pylori or CagA⁻H. pylori. Colonization of CagA⁺H. pylori but not CagA⁻H. pylori in the host gastric mucosa induced severe chronic gastritis in RAG2^−/− mice transferred with spleen cells from H. pylori-uninfected mice. In addition, when CagA⁺H. pylori-primed spleen cells were transferred into RAG2^−/− mice, CD4⁺ T cell infiltration in the host gastric mucosa were observed only in RAG2^−/− mice infected with CagA⁺H. pylori but not CagA⁻H. pylori, suggesting that colonization of CagA⁺H. pylori in the host gastric mucosa is essential for the migration of H. pylori-primed CD4⁺ T cells. On the other hand, transfer of CagA⁻H. pylori-primed spleen cells into CagA⁺H. pylori-infected RAG2^−/− mice induced more severe chronic gastritis with less Foxp3⁺ regulatory T-cell infiltration as compared to transfer of CagA⁺H. pylori-primed spleen cells. In conclusion, CagA in the stomach plays an important role in the migration of H. pylori-primed CD4⁺ T cells in the gastric mucosa, whereas CagA-dependent T-cell priming induces regulatory T-cell differentiation, suggesting dual roles for CagA in the pathophysiology of H. pylori-induced chronic gastritis.     

TLR4 and TLR2 expression in biopsy specimens from antral and corporal stomach zones in Helicobacter pylori infections

Background:

It is not yet known which types of Toll-like receptors (TLRs) are most effective in Helicobacter pylori (H. pylori) recognition. It is also not known which gastric zones have the most prominent roles in TLR-mediated bacterial recognition. The aim of this work was to analyze the expression of TLR2 and TLR4 in biopsy specimens from H. pylori-infected patients.

Methods:

Thirty-eight patients with gastrointestinal disorders were divided into four groups in this study. The groups were: (A) H. pylori infection and peptic ulcer (n=15), (B) peptic ulcer only (n=5), (C) H. pylori infection only (n=10) and (D) control, with neither H. pylori infection nor peptic ulcer (n=8). Biopsy specimens from sites of redness or atrophic mucosa from gastric antrum and body in patients with gastritis were collected. RNAs from the antrum and body specimens were isolated. TLR2 and TLR4 mRNA expression was assessed by RT-PCR and quantified as densitometric ratios of TLR2 and TLR4/β-actin mRNA.

Results:

In the antral zones of H. pylori-infected patients (Groups A and C) TLR2 and TLR4 expression was significantly greater than in uninfected patients (Groups B and D) regardless of peptic ulcers (p < 0.05). In the gastric body samples TLR2 expression was significantly greater in Group C (H. pylori infection only) than in Group B (peptic ulcer only) and TLR4 expression was significantly greater in group A (H. pylori infection and peptic ulcer) than in Group B (peptic ulcer only) (p < 0.05). No significant differences in expression of TLR4 and TLR2 were observed between samples from the antrum and body in same groups.

Conclusions:

We conclude that H. pylori infection leads to significant increase in TLR2 and TLR4 molecules expression in antral region related to the control group. Considering the stimulatory effect of H. pylori on TLRs expression in the gastric tissue, we assume that colonization of H. pylori infection might occurs more in the gastric antral region than in the gastric body.Key Words: Helicobacter pylori, Toll-like receptors, TLR4; TLR2, Peptic ulcer     

Age-Dependent Association among Helicobacter pylori Infection,Serum Pepsinogen Levels and Immune Response of Children to Live Oral Cholera Vaccine CVD 103-HgR

Background

Through its effects on gastric secretion, we hypothesized that Helicobacter pylori infection may influence oral immunization. Accordingly, we examined the association between H. pylori infection, serum pepsinogen (PG) (measures for H. pylori gastritis) and vibriocidal antibody (a correlate of protection) seroconversion following oral immunization with CVD 103-HgR live cholera vaccine among children of different ages.

Methods

Sera from 422 Chilean children who were vaccinated with a single dose of CVD 103-HgR were tested by ELISA for serum IgG antibodies to H. pylori, PG I and PG II levels and antibodies to Shigella flexneri 2a lipopolysaccharide and hepatitis A virus (as markers of low socioeconomic status and exposure to enteric pathogens).

Results

The likelihood of vibriocidal antibody seroconversion following vaccination with CVD 103-HgR was significantly decreased in H. pylori-seropositive children age 6 months to 4 years with PG II>8 µg/L (adjusted OR 0.14 (95% CI 0.03–0.61; P = 0.009), and also in H. pylori seropositives with lower PG II level (adjusted OR 0.34, 95% CI 0.14–0.83; P = 0.017), compared to H. pylori-seronegatives. H. pylori-seropositive children aged 5–9 years with serum PG I>30 µg/L (indicating more severe gastritis) had higher odds of vibriocidal seroconversion than those with lower PG I levels (adjusted OR 4.41, 95%CI 1.26–15.38; P = 0.02). There was no significant association between exposures to S. flexneri 2a or hepatitis A virus and vibriocidal seroconversion.

Conclusions

As H. pylori gastritis progresses with increasing pediatric age in developing country venues, changes in gastric secretion ensue that we believe explain the observed differences in age-related immune responses to immunization with live oral cholera vaccine. The effect of H. pylori and changes of gastric acid secretion on the immunogenicity of various oral vaccines should be studied in different developing, transitional and industrialized country settings.     

H. pylori CagL-Y58/E59 Prime Higher Integrin α5β1 in Adverse pH Condition to Enhance Hypochlorhydria Vicious Cycle for Gastric Carcinogenesis

Background/Aims

H. pylori CagL amino acid polymorphisms such as Y58/E59 can increase integrin α5β1 expression and gastric cancer risk. Hypochlorhydria during chronic H. pylori infection promotes gastric carcinogenesis. The study test whether CagL-Y58/E59 isolates may regulate integrin α5β1 to translocate CagA via the type IV secretory system even under adverse pH conditions, and whether the integrin α5β1 expression primed by H. pylori is a pH-dependent process involving hypochlorhydria in a vicious cycle to promote gastric carcinogenesis.

Methods

The expressions of integrin α5 and β1, CagA phosphorylation, IL-8, FAK, EGFR, and AKT activation of AGS cells exposed to CagL-Y58/E59 H. pylori, isogenic mutants, and different H. pylori CagL amino acid replacement mutants under different pH values were determined. Differences in the pepsinogen I/II ratio (indirectly indicating gastric acidity) and gastric integrin α5β1 expression were compared among the 172 H. pylori-infected patients with different cancer risks.

Results

Even under adversely low pH condition, H. pylori CagL-Y58/E59 still keep active integrin β1 with stronger binding affinity, CagA translocation, IL-8, FAK, EGFR, and AKT activation than the other mutants (p<0.05). The in vitro assay revealed higher priming of integrin α5β1 by H. pylori under elevated pH as hypochlorhydria (p<0.05). In the H. pylori-infected patients, the gastric integrin α5β1 expressions were higher in those with pepsinogen I/II ratio <6 than in those without (p<0.05).

Conclusions

H. pylori CagL-Y58/E59 prime higher integrin under adverse pH and may involve to enhance hypochlorhydria vicious cycle for gastric carcinogenesis, and thus require an early eradication.     

CpG Island Methylator Phenotype,Helicobacter pylori,Epstein-Barr Virus,and Microsatellite Instability and Prognosis in Gastric Cancer: A Systematic Review and Meta-Analysis

Background

The controversy of CpG island methylator phenotype (CIMP) in gastric cancer persists, despite the fact that many studies have been conducted on its relation with helicobacter pylori (H. pylori), Epstein-Barr virus (EBV), and microsatellite instability (MSI) and prognosis. To drive a more precise estimate of this postulated relationship, a meta-analysis was performed based on existing relevant studies.

Methods

We combined individual patient data from 12 studies which involved 1000 patients with gastric cancer, which met the criteria. We tabulated and analyzed parameters from each study, including H. pylori, EBV, MSI, and clinical information of patients.

Results

The overall OR for H. pylori infection in CIMP positive group vs. negative group revealed that significantly elevated risks of positive H. pylori infection in the former were achieved (OR 2.23 95% CI, 1.25–4.00; P = 0.007, P_{heterogeneity} = 0.05). Similarly, strong relation between EBV infection and CIMP was achieved by OR 51.27 (95% CI, 9.39–279.86; P<0.00001, P_{heterogeneity} = 0.39). The overall OR for MSI in CIMP positive group vs. negative group was 4.44 (95% CI, 1.17–16.88; P = 0.03, P_{heterogeneity} = 0.01). However, there did not appear to be any correlations with clinical parameters such as tumor site, pathological type, cell differentiation, TNM stage, distant metastasis, lymph node metastasis, and 5-year survival.

Conclusions

The meta-analysis highlights the strong relation of CIMP with H. pylori, EBV, and MSI, but CIMP can not be used as a prognostic marker for gastric cancer.     

Higher number of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> CagA EPIYA C phosphorylation sites increases the risk of gastric cancer,but not duodenal ulcer

Background  

Helicobacter pylori infection is one of the most common infections worldwide and is associated with gastric cancer and peptic ulcer. Bacterial virulence factors such as CagA have been shown to increase the risk of both diseases. Studies have suggested a causal role for CagA EPIYA polymorphisms in gastric carcinogenesis, and it has been shown to be geographically diverse. We studied associations between H. pylori CagA EPIYA patterns and gastric cancer and duodenal ulcer, in an ethnically admixed Western population from Brazil. CagA EPIYA was determined by PCR and confirmed by sequencing. A total of 436 patients were included, being 188 with gastric cancer, 112 with duodenal ulcer and 136 with gastritis.     

Helicobacter Pylori and Epstein-Barr Virus Co-Infection in Polish Patients with Gastric Cancer – a Pilot Study

The infectious agents may be the etiological factor of up to 15–20% of cancers. In stomach cancer, attention is paid to Helicobacter pylori and Epstein-Barr virus, both of which cause gastritis and can lead to tumor development. In co-infection, the inflammatory process is much more intense. We assessed the seroprevalence towards H. pylori and EBV in 32 patients with diagnosed gastric cancer. H. pylori antibodies were found in 69% patients, and anti-EBV – in all of them. The study confirmed that co-infection of H. pylori and EBV seems to be important in etiopathology of gastric cancer. Open in a separate window     

Infection with CagA-Positive Helicobacter Pylori Strain Containing Three EPIYA C Phosphorylation Sites is Associated with More Severe Gastric Lesions in Experimentally Infected Mongolian Gerbils (Meriones Unguiculatus)

Infection with Helicobacter pylori strains containing high number of EPIYA-C phosphorylation sites in the CagA is associated with significant gastritis and increased risk of developing pre-malignant gastric lesions and gastric carcinoma. However, these findings have not been reproduced in animal models yet. Therefore, we investigated the effect on the gastric mucosa of Mongolian gerbil (Meriones unguiculatus) infected with CagA-positive H. pylori strains exhibiting one or three EPIYA-C phosphorilation sites. Mongolian gerbils were inoculated with H. pylori clonal isolates containing one or three EPIYA-C phosphorylation sites. Control group was composed by uninfected animals challenged with Brucella broth alone. Gastric fragments were evaluated by the modified Sydney System and digital morphometry. Clonal relatedness between the isolates was considered by the identical RAPD-PCR profiles and sequencing of five housekeeping genes, vacA i/d region and of oipA. The other virulence markers were present in both isolates (vacA s1i1d1m1, iceA2, and intact dupA). CagA of both isolates was translocated and phosphorylated in AGS cells. After 45 days of infection, there was a significant increase in the number of inflammatory cells and in the area of the lamina propria in the infected animals, notably in those infected by the CagA-positive strain with three EPIYA-C phosphorylation sites. After six months of infection, a high number of EPIYA-C phosphorylation sites was associated with progressive increase in the intensity of gastritis and in the area of the lamina propria. Atrophy, intestinal metaplasia, and dysplasia were also observed more frequently in animals infected with the CagA-positive isolate with three EPIYA-C sites. We conclude that infection with H. pylori strain carrying a high number of CagA EPIYA-C phosphorylation sites is associated with more severe gastric lesions in an animal model of H. pylori infection.Key words: Gastritis, atrophy, intestinal metaplasia, dysplasia, Mongolian gerbil, cagA EPIYA C motif     

Genetic Polymorphisms of miR-146a and miR-27a,H. pylori Infection,and Risk of Gastric Lesions in a Chinese Population

Background

MicroRNAs (miRNAs) have been implicated in various human diseases. Single nucleotide polymorphisms (SNPs) in inflammation-related miRNA may play an important role in Helicobacter pylori (H. pylori)-induced gastric lesions. To evaluate the associations between miRNA SNPs, H. pylori and gastric lesions, a population-based study was conducted in Linqu County, China.

Methodology/Principal Findings

Based on serum miRNA array conducted in this population, two SNP loci (miR-146a rs2910164: G>C and miR-27a rs895819: T>C) were determined by polymerase chain reaction-restriction fragment length polymorphism in 2,380 participants with diverse gastric lesions. Using participants with superficial gastritis and mild chronic atrophic gastritis as the reference group, we found that rs2910164 CC carriers had a significantly increased risk of intestinal metaplasia [adjusted odds ratio (OR), 1.42; 95% confidence interval (CI), 1.03–1.97] and dysplasia (OR, 1.54; 95% CI, 1.05–2.25) compared to GG carriers, whereas no significant association was observed for rs895819. Stratified analysis by H. pylori infection indicated that rs2910164 C allele was associated with an increased risk of intestinal metaplasia and dysplasia only among individuals infected with H. pylori (CC vs. GG: OR, 1.53; 95% CI, 1.12–2.08, P for trend = 0.004). Participants who simultaneously carried variant alleles and H. pylori infection were more likely to develop intestinal metaplasia and dysplasia, although the interaction between genetic variants and H. pylori infection was not significant (P for interaction = 0.35 for rs2910164 and 0.92 for rs895819).

Conclusions/Significance

These findings suggest that miR-146a rs2910164 polymorphism may contribute to the evolution of H. pylori-associated gastric lesions in this high-risk population.     

Higher glucose level can enhance the H. pylori adhesion and virulence related with type IV secretion system in AGS cells

Background

Hyperglycemia increases the risk of gastric cancer in H. pylori-infected patients. High glucose could increase endothelial permeability and cancer-associated signaling. These suggest high glucose may affect H. pylori or its infected status.We used two strains to investigate whether H. pylori growth, viability, adhesion and CagA-phosphorylation level in the infected-AGS cells were influenced by glucose concentration (100, 150, and 200 mg/dL).

Results

The growth curves of both strains in 200 mg/dL of glucose were maintained at the highest optimal density after 48 h and the best viability of both strains were retained in the same glucose condition at 72 h. Furthermore, adhesion enhancement of H. pylori was significantly higher in 200 mg/dL of glucose as compared to that in 100 and 150 mg/dL (p < 0.05). CagA protein also increased in higher glucose condition. The cell-associated CagA and phosphorylated-CagA was significantly increased in 150 and 200 mg/dL of glucose concentrations as compared to that of 100 mg/dL (p < 0.05), which were found to be dose-dependent.

Conclusion

Higher glucose could maintain H. pylori growth and viability after 48 h. H. pylori adhesion and CagA increased to further facilitate the enhancement of cell-associated CagA and phosphorylated CagA in higher glucose conditions.     

Isocitrate dehydrogenase of Helicobacter pylori potentially induces humoral immune response in subjects with peptic ulcer disease and gastritis

Background

H. pylori causes gastritis and peptic ulcers and is a risk factor for the development of gastric carcinoma. Many of the proteins such as urease, porins, flagellins and toxins such as lipo-polysaccharides have been identified as potential virulence factors which induce proinflammatory reaction. We report immunogenic potentials of isocitrate dehydrogenase (ICD), an important house keeping protein of H. pylori.

Methodology/Principal Findings

Amino acid sequences of H. pylori ICD were subjected to in silico analysis for regions with predictably high antigenic indexes. Also, computational modelling of the H. pylori ICD as juxtaposed to the E. coli ICD was carried out to determine levels of structure similarity and the availability of surface exposed motifs, if any. The icd gene was cloned, expressed and purified to a very high homogeneity. Humoral response directed against H. pylori ICD was detected through an enzyme linked immunosorbent assay (ELISA) in 82 human subjects comprising of 58 patients with H. pylori associated gastritis or ulcer disease and 24 asymptomatic healthy controls. The H. pylori ICD elicited potentially high humoral immune response and revealed high antibody titers in sera corresponding to endoscopically-confirmed gastritis and ulcer disease subjects. However, urea-breath-test negative healthy control samples and asymptomatic control samples did not reveal any detectable immune responses. The ELISA for proinflammatory cytokine IL-8 did not exhibit any significant proinflammatory activity of ICD.

Conclusions/Significance

ICD of H. pylori is an immunogen which interacts with the host immune system subsequent to a possible autolytic-release and thereby significantly elicits humoral responses in individuals with invasive H. pylori infection. However, ICD could not significantly stimulate IL8 induction in a cultured macrophage cell line (THP1) and therefore, may not be a notable proinflammatory agent.     

Antral nodularity and positive CagA serology are distinct and relevant markers of severe gastric inflammation in children with Helicobacter pylori infection

Background. The aim of this study was to assess whether the endoscopic finding of antral nodularity and serum IgG antibodies to CagA are associated with higher grades of gastric inflammation. Materials and methods. The comprehensive data of two previously published trials were reanalysed. One hundred and fifty‐three children (median age 9.5 years) who underwent gastroscopy were included. Biopsy specimens from the antrum and corpus were taken to assess Helicobacter pylori status, gastritis score and lymphoid follicles. During endoscopy, antral nodularity was noted. Serum samples were assayed for IgG antibodies to CagA. Results. The presence of antral nodularity (nod+) and positive CagA serology (CagA+) were each found in 32 of the 77 (41.5%) children who had evidence of H. pylori infection. Crosstabulation showed that 20 children (26%) were nod+/CagA+, 12 (15.5%) nod+/CagA?, 12 (15.5%) nod‐/CagA+ and 33 (43%) nod?/CagA?. Gastritis score was significantly lower in nod?/CagA?children than in nod+/CagA? (p = .004), nod?/CagA+ (p = .002) and nod+/CagA+ (p < .001), both in the antrum and corpus. Completely normal gastric histology was only found in the nod?/CagA?subgroup of H. pylori‐infected children (eight of 33, 24%). Regression analysis showed that antral nodularity and positive CagA serology were related to severe gastric inflammation independently of each other and age. Separate analysis showed that inflammation (p < .001), activity (p < .001) and H. pylori density (p = .002) scores were significantly lower in nod?/CagA?children compared with nod+/CagA+ children. The number of lymphoid follicles in the gastric mucosa was related to antral nodularity (p = .003) and positive CagA serology (p = .043), independently of each other. Conclusions. Antral nodularity and positive CagA serology are distinct and relevant markers of severe gastric inflammation in children with H. pylori infection. The lack of both findings in the same child reflects low‐grade or no gastritis.     

A Comparative Study of Clinicopathological Features between Chronic Cholecystitis Patients with and without Helicobacter pylori Infection in Gallbladder Mucosa

Background

Helicobacter pylori has been isolated from 10%–20% of human chronic cholecystitis specimens but the characteristics of “Helicobacter pylori positive cholecystitis” remains unclear. This study aims to compare the clinicopathological features between chronic cholecystitis patients with and without Helicobacter pylori infection in gallbladder mucosa.

Methods

Three hundred and twenty-six chronic cholecystitis patients were divided into two groups according to whether Helicobacter pylori could be detected by culture, staining or PCR for Helicobacter 16s rRNA gene in gallbladder mucosa. Positive samples were sequenced for Helicobacter pylori-specific identification. Clinical parameters as well as pathological characteristics including some premalignant lesions and the expression levels of iNOS and ROS in gallbladder were compared between the two groups.

Results

Helicobacter pylori infection in gallbladder mucosa was detected in 20.55% of cholecystitis patients. These patients had a higher prevalence of acid regurgitation symptoms (p = 0.001), more histories of chronic gastritis (p = 0.005), gastric ulcer (p = 0.042), duodenal ulcer (p = 0.026) and higher presence of Helicobacter pylori in the stomach as compared to patients without Helicobacter pylori infection in the gallbladder mucosa. Helicobacter pylori 16s rRNA in gallbladder and gastric-duodenal mucosa from the same individual patient had identical sequences. Also, higher incidences of adenomyomatosis (p = 0.012), metaplasia (p = 0.022) and higher enhanced expressions of iNOS and ROS were detected in Helicobacter pylori infected gallbladder mucosa (p<0.05).

Conclusions

Helicobacter pylori infection in gallbladder mucosa is strongly associated with Helicobacter pylori existed in stomach. Helicobacter pylori is also correlated with gallbladder premalignant lesions including metaplasia and adenomyomatosis. The potential mechanism might be related with higher ROS/RNS production but needs further investigation.     

CD44 Plays a Functional Role in Helicobacter pylori-induced Epithelial Cell Proliferation

The cytotoxin-associated gene (Cag) pathogenicity island is a strain-specific constituent of Helicobacter pylori (H. pylori) that augments cancer risk. CagA translocates into the cytoplasm where it stimulates cell signaling through the interaction with tyrosine kinase c-Met receptor, leading cellular proliferation. Identified as a potential gastric stem cell marker, cluster-of-differentiation (CD) CD44 also acts as a co-receptor for c-Met, but whether it plays a functional role in H. pylori-induced epithelial proliferation is unknown. We tested the hypothesis that CD44 plays a functional role in H. pylori-induced epithelial cell proliferation. To assay changes in gastric epithelial cell proliferation in relation to the direct interaction with H. pylori, human- and mouse-derived gastric organoids were infected with the G27 H. pylori strain or a mutant G27 strain bearing cagA deletion (∆CagA::cat). Epithelial proliferation was quantified by EdU immunostaining. Phosphorylation of c-Met was analyzed by immunoprecipitation followed by Western blot analysis for expression of CD44 and CagA. H. pylori infection of both mouse- and human-derived gastric organoids induced epithelial proliferation that correlated with c-Met phosphorylation. CagA and CD44 co-immunoprecipitated with phosphorylated c-Met. The formation of this complex did not occur in organoids infected with ∆CagA::cat. Epithelial proliferation in response to H. pylori infection was lost in infected organoids derived from CD44-deficient mouse stomachs. Human-derived fundic gastric organoids exhibited an induction in proliferation when infected with H. pylorithat was not seen in organoids pre-treated with a peptide inhibitor specific to CD44. In the well-established Mongolian gerbil model of gastric cancer, animals treated with CD44 peptide inhibitor Pep1, resulted in the inhibition of H. pylori-induced proliferation and associated atrophic gastritis. The current study reports a unique approach to study H. pylori interaction with the human gastric epithelium. Here, we show that CD44 plays a functional role in H. pylori-induced epithelial cell proliferation.     

Associated Factors of Atrophic Gastritis Diagnosed by Double-Contrast Upper Gastrointestinal Barium X-Ray Radiography: A Cross-Sectional Study Analyzing 6,901 Healthy Subjects in Japan

Background

Double-contrast upper gastrointestinal barium X-ray radiography (UGI-XR) is one of the most widely conducted gastric cancer screening methods. It has been executed to find gastric cancer, but has not been usually executed to detect premalignant atrophic mucosa of stomach. To understand the meaning of UGI-XR-based atrophic gastritis, we analyzed its association with several causative factors including Helicobacter pylori (HP) infection.

Methods

We evaluated 6,901 healthy adults in Japan. UGI-XR-based atrophic gastritis was diagnosed based on the irregular shape of areae gastricae and its expansion in the stomach.

Results

Of the 6,433 subjects with no history of HP eradication and free from gastric acid suppressants, 1,936 were diagnosed as UGI-XR-based atrophic gastritis (mild: 234, moderate: 822, severe: 880). These were univariately associated with serum HP IgG and serum pepsinogen I/II ratio with statistical significance. The multiple logistic analysis calculating standardized coefficients (β) and odds ratio (OR) demonstrated that serum HP IgG (β = 1.499, OR = 4.48), current smoking (β = 0.526, OR = 1.69), age (β = 0.401, OR = 1.49), low serum pepsinogen I/II ratio (β = 0.339, OR = 1.40), and male gender (β = 0.306, OR = 1.36) showed significant positive association with UGI-XR-based atrophic gastritis whereas drinking and body mass index did not. Among the age/sex/smoking/drinking-matched 227 pairs derived from chronically HP-infected and successfully HP-eradicated subjects, UGI-XR-based atrophic gastritis was detected in 99.1% of the former but in only 59.5% of the latter subjects (p<0.0001). Contrastively, UGI-XR-based atrophic gastritis was detected in 13 of 14 HP-positive proton pump inhibitor users (92.9%) and 33 of 34 HP-positive histamine H₂-receptor antagonist users (97.1%), which are not significantly different from gastric acid suppressant-free subjects.

Conclusions

The presence of UGI-XR-based atrophic gastritis is positively associated with Helicobacter pylori infection, current smoking, age, decreased serum pepsinogen I/II ratio, and male gender. Eradication of Helicobacter pylori seems to superficially improve UGI-XR-based atrophic gastritis whereas intake of gastric acid suppressants does not.     

N-acetylcysteine prevents the development of gastritis induced by <Emphasis Type="Italic">Helicobacter pylori</Emphasis> infection

Helicobacter pylori (H. pylori) is a human gastric pathogen, causing various gastric diseases ranging from gastritis to gastric adenocarcinoma. It has been reported that combining N-acetylcysteine (NAC) with conventional antibiotic therapy increases the success rate of H. pylori eradication. We evaluated the effect of NAC itself on the growth and colonization of H. pylori, and development of gastritis, using in vitro liquid culture system and in vivo animal models. H. pylori growth was evaluated in broth culture containing NAC. The H. pylori load and histopathological scores of stomachs were measured in Mongolian gerbils infected with H. pylori strain 7.13, and fed with NAC-containing diet. In liquid culture, NAC inhibited H. pylori growth in a concentration-dependent manner. In the animal model, 3-day administration of NAC after 1 week from infection reduced the H. pylori load; 6-week administration of NAC after 1 week from infection prevented the development of gastritis and reduced H. pylori colonization. However, no reduction in the bacterial load or degree of gastritis was observed with a 6-week administration of NAC following 6-week infection period. Our results indicate that NAC may exert a beneficial effect on reduction of bacterial colonization, and prevents the development of severe inflammation, in people with initial asymptomatic or mild H. pylori infection.