Effect of Helicobacter pylori infection and eradication on gastric epithelial cell proliferation and apoptosis.

OBJECTIVES: the effect of Helicobacter pylori infection on gastric epithelial cell proliferation and apoptosis is still controversial. Our aim was to evaluate the effect of H. pylori infection on cell kinetic parameters in normal gastric epithelium, gastritis with/without intestinal metaplasia and gastric cancer. PATIENTS AND METHODS: antral biopsies were taken from 121 patients (61 women, 60 men, mean age 58.5+/-14.3 years of age) who underwent routine gastroscopy for upper gastrointestinal symptoms. Sections were scored for normal epithelia (n=15), gastritis without intestinal metaplasia (n=74), gastritis with intestinal metaplasia (n=24), and gastric adenocarcinoma (n=8). Fifty-two patients had H. pylori positive gastritis, and success of H. pylori eradication therapy was controlled in 12 cases, all with intestinal metaplasia. To characterize cell proliferation and assess apoptosis, immunohistochemistry [Proliferating Cell Nuclear Antigen (PCNA)], histochemistry [Argyrophil Nucleolar Organizer Regions (AgNOR)], and terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridinetriphosphate (dUTP) nick end-labeling (TUNEL) were used, respectively. RESULTS: both cell proliferation and apoptosis is was higher in chronic gastritis when compared with normal epithelia, but neither PCNA LI (54.79+/-19.1 vs. 53.20+/-20.7) nor AgNOR counts (291.43+/-44.3 vs. 277.8+/-57.54) were different in H. pylori positive versus negative chronic gastritis. A significant positive correlation (P<0.05) was found in this group between PCNA and AgNOR techniques. Apoptosis was significantly higher (P<0.05) in H. pylori positive cases only when intestinal metaplasia was not present. Cell proliferation in intestinal metaplasia decreased to the activity of normal epithelium after successful eradication of H. pylori but remained high if eradication therapy failed. CONCLUSIONS: epithelial cell proliferation does not depend on H. pylori status in chronic gastritis. H. pylori increases apoptosis only in the absence of intestinal metaplasia.     

The pathological examinations of gastric mucosa in patients with Helicobacter pylori-positive and -negative pernicious anemia

Background. The basic histopathological finding in gastric mucosa is chronic atrophic gastritis in patients with pernicious anemia.
Materials and Methods. We evaluated the frequency of Helicobacter pylori and pathological examinations of gastric mucosa in pernicious anemia (n = 30) by endoscopical findings and biopsy. The results were compared with gastric mucosa specimens of patients with H. pylori –positive nonulcer dyspepsia (n = 36) and H. pylori –negative nonulcer dyspepsia (n = 21).
Results. H. pylori was diagnosed in 12 patients (40%) with pernicious anemia. Fundal biopsy examinations showed atrophic gastritis in 30 patients (100%), intestinal metaplasia in 13 patients (43.3%), lymphoid follicle in 15 patients (50%), and dysplasia in 6 patients (20%). Antral biopsy examinations showed atrophic gastritis in 8 patients (26.6%), intestinal metaplasia in 8 patients (26.6%), lymphoid follicle in 8 patients (26.6%), and dysplasia in 3 patients (10%). The frequency of fundal inflammation, atrophy, intestinal metaplasia, lymphoid follicle, and dysplasia and antral intestinal metaplasia and mild antral dysplasia were found to be higher in those in the pernicious anemia group than in the nonulcer dyspeptic patients. Antral inflammation, atrophy, and moderate and severe antral dysplasia were found to be higher in those in the nonulcer dyspeptic group.
Conclusions. Particularly, fundal precancerous lesions were found to be more frequent in patients with pernicious anemia independent of H. pylori.     

Genetic alterations in gastric precancerous lesions

To investigate the occurrence of 17p (p53) loss of heterozygosity (LOH) and increased 4N or aneuploidy in gastric precancerous lesions (GPL), and their association with Helicobacter pylori (H pylori) infection. A total of 78 gastric mucosal biopsy specimens, including 10 normal mucosa and 68 gastric precancerous lesions [chronic atrophic gastritis (CAG, n = 20), intestinal metaplasia (IM, n = 12), low grade dysplasia (LGD, n = 15), and high grade dysplasia (HGD, n = 21)] were studied using PCR and flow cytometry. A modified Giemsa staining technique was used to detect H pylori. The study was performed in Erzurum Numune Hospital between 2007 and 2009. 17p (p53) LOH was observed in (1/20) 5% of CAG, in (2/12) 16% of IM, in (3/15) 20% of LGD and in (11/21) 53% of HGD. There was correlation between prevalence of 17p (p53) LOH and histological type of GPL (P = 0.004). Similarly, increased 4N or aneuploidy was detected in (1/20) 5% of CAG, in (1/12) 8% of IM, in (2/15) 13% of LGD and in (9/21) 43% of HGD. The correlation was found between aneuploidy and histological type of GPL (P = 0.009). However, there was no correlation between presence of H pylori infection in histological type of GPL (P = 0.921). On the other hand, a significant association was found between increased 4N or aneuploidy and 17p (p53) LOH in all of GPL (P = 0.0001). However, there was no statistically significant association between H pylori infection and 17p (p53) LOH or increased 4N/aneuplody in GPL. 17p (p53) LOH and increased 4N or aneuploidy are closely related to the early stages of gastric carcinogenesis.     

Apoptosis in different gastric lesions and gastric cancer: relationship with Helicobacter pylori, overexpression of p53 and aneuploidy

Apoptosis has an essential function in maintaining the integrity of the gastrointestinal mucosa. Its deregulation is associated with the occurrence of lesions such as in atrophic gastritis, peptic ulcers, intestinal metaplasia, and stomach tumorigenesis. Thus, the aim of the present study was to investigate the frequency of apoptotic cells (apoptotic index, AI) by using two different immunohistochemical techniques, TUNEL and anti-activated caspase-3 antibody (CPP32), in gastric dyspepsia [chronic gastritis (CG, N = 34), chronic atrophic gastritis (CAG, N = 11), gastric ulcer (GU, N = 17), and intestinal metaplasia (IM, N = 15)], normal gastric mucosae (NM, N = 8), and gastric adenocarcinoma (GC, N = 12). The relationship was investigated between the AI and Helicobacter pylori infection, diagnosed by PCR, overexpression of p53 protein determined by immunohistochemistry, and aneuploidy by fluorescence in situ hybridization, as performed by our laboratory in previous studies. No significant differences were observed in AI between the different groups, whether by the TUNEL technique (F = 1.60; p = 0.1670) or by CPP32 antibody (F = 1.70; p = 0.1420). Nonetheless, CAG and CG groups had AI statistically higher than those of normal mucosae. These two groups (CAG and CG) also showed a higher frequency of apoptosis-positive cases (TUNEL+ or CPP32+). Generally, there was no correlation between the AI detected by the TUNEL and CPP32 techniques in the groups studied, except in the GC group (r = 0.70). Moreover, there was no significant association between apoptosis and H. pylori infection, overexpression of p53 protein and aneuploidy, but the H. pylori-positive cases only of GU (p = 0.0233) and IM (p = 0.0253) groups displayed a statistically higher AI compared to H. pylori-negative NM, when the CPP32 antibody technique was used. Thus, CG and CAG have increased apoptosis, which may occur independent of an association with H. pylori infection, aneuploidy and overexpression of p53 protein.     

幽门螺杆菌相关胃癌发生不同阶段 miRNAs表达与临床研究

目的观察幽门螺杆菌(Helicobacter pylori,H.pylori)感染的慢性非萎缩性胃炎(no-atrophic gastritis,NAG)→萎缩性胃炎(chronic atrophic gastritis,CAG)→肠上皮化生(intestinal metaplasia,IM)→非典型增生(dysplasia,DYS)→胃癌(gastric cancer,GC)五个不同阶段miR-1、miR-20a、miR-34a、miR-423-5p表达变化规律及其与临床的关系。方法收集胃镜及病理证实的上述胃癌发生五个不同阶段且H.pylori感染的患者(依次为44、47、43、50、45例),胃癌无H.pylori感染者46例,胃黏膜正常(normal gastric mucose,NGM)63例的血清标本,采用Real-time PCR法检测无H.pylori感染者miR-1、miR-20a、miR-34a、miR-423-5p表达。结果 H.pylori感染NAG→GC不同阶段,miR-1、miR-20a、miR-34a、miR-423-5p表达逐渐升高(P0.05),GC阶段最高,miR-1、miR-20a CAG→GC阶段均高于NGM (P0.05),与NGM比较差异有统计学意义(P0.05);其表达程度与GC发生阶段呈正相关(P0.001);GC组H.pylori感染者较无H.pylori感染者miR-1、miR-20a、miR-34a、miR-423-5p表达升高(P0.05)。结论 H.pylori感染CAG→GC阶段miR-1、miR-20a、miR-34a、miR-423-5p表达升高,向胃癌演进中呈逐渐升高趋势,miR-1、miR-20a、miR-34a、miR-423-5p高表达可能是H.pylori感染后导致胃癌发生发展的重要机制,miR-1、miR-20a、miR-34a可作为诊断早期胃癌的标记物。     

Increased cell proliferation in chronic Helicobacter pylori positive gastritis and gastric carcinoma--correlation between immuno-histochemistry and Tv image cytometry.

BACKGOUND: Epithelial cell proliferation activity has been reported both to be unaltered and increased in Helicobacter pylori (H. pylori) associated chronic gastritis. The proliferation rate decreased following H. pylori eradication, but results are controversial whether this change is dependent on the success of eradication. We compared the cell proliferation activity of H. pylori positive and negative gastric epithelial biopsies in chronic gastritis with and without intestinal metaplasia (IM) and gastric cancer by the expression of proliferation cell nuclear antigen (PCNA) and Tv image cytometry, and assessed the effect of H. pylori eradication on the cell proliferation rate in the gastric epithelium. METHODS: Brush smears and antral biopsies were taken from 70 patients (42 men, 28 women, mean age 58+/-15 y.o.) on routine endoscopy. Patients were divided into four groups according to the histology; normal epithelia (n = 10), chronic gastritis without IM (n = 24), chronic gastritis with IM (n = 20), and gastric carcinoma (n = 16). Thirty-three patients were H. pylori positive, and success of eradication was controlled in 24 cases. Cell proliferation was measured by immunohistochemistry using PCNA labeling index (LI) and by Tv image cytometry evaluating 12 morpho- and densitometric parameters of each nuclei and 6 additional parameters of each smear. RESULTS: PCNA LI, DNA index and S + G2 ratio were all higher in chronic gastritis than in the normal epithelium, and were further increased in carcinoma. The lower PCNA LI observed in chronic gastritis with IM corresponds to the lower S phase ratio determined by Tv image analysis. In H. pylori positive cases, the proliferation activity was 69.3+/-13.05% prior to the eradication and it decreased to 55.8+/-23.31% after the successful eradication therapy. When immunohistochemistry was compared with Tv image cytometry, PCNA LI significantly correlated with the percentage of cells in GL phase (r = -0.415) and S phase (r = 0.385), Integrated Optical Density mean (r = 0.598), density maximum (r'= 0.608), surface (r = 0.670), layers (r = 0.638), diameter minimum (r = 0.619), diameter maximum (r = 0.730) and perimeter (r = 0.501), respectively (p < 0.05). CONCLUSIONS: Epithelial cell turnover is increased in chronic gastritis with or without IM, and in gastric carcinoma. The lower PCNA LI observed in chronic gastritis with IM corresponds to the lower S phase ratio determined by Tv image analysis. Cell proliferation decreases after successful H. pylori eradication. Both methods proved to be reliable for the determination of epithelial cell proliferation.     

Role of bacterial strain diversity of Helicobacter pylori in gastric carcinogenesis induced by N-methyl-N-nitrosourea in Mongolian gerbils

AIM: Helicobacter pylori is known to enhance gastric carcinogenesis induced by chemical carcinogens. We previously demonstrated that infection with H. pylori strain SS1 did not enhance such carcinogenesis in C57BL/6 mice. Whether this result was due to the bacterial strain SS1 or to the experimental host, C57BL/6 mice, should be addressed. Therefore, we examined whether H. pylori strains introduced to the same host (Mongolian gerbils) differed in carcinogenicity. MATERIALS AND METHODS: H. pylori TN2GF4 strain (CagA(+), VacA(+)) and SS1 strain (CagA functionally(-), VacA(-)) were infected to Mongolian gerbils (n = 126). In the first experiment (induction of gastritis), histologic change in gastric mucosa of gerbils infected by H. pylori (TN2GF4, SS1, vehicle) without N-methyl-N-nitrosourea (MNU) at 1 month or 6 months was assessed. In the second experiment (experimental carcinogenesis), H. pylori (TN2GF4, SS1, vehicle) was inoculated to the gerbils after administration of MNU for 10 weeks, and the number of cancers and histopathologic changes at week 54 were assessed. RESULTS: In the first experiment, activity and inflammation in the TN2GF4 group were significantly greater than in the SS1 group at 1 month, while no significant difference was noted at 6 months. On the other hand, intestinal metaplasia and atrophy were significantly greater with TN2GF4 than with SS1 at 6 months but not at 1 month. In studies on experimental carcinogenesis, microscopically, 47.8% (11/23), 26% (7/26), and 0% (0/26), of animals had gastric adenocarcinoma in the MNU + TN2GF4 group, MNU + SS1 group, and MNU alone group, respectively. CONCLUSION: Both H. pylori strains, TN2GF4 and SS1, promoted carcinogenesis in Mongolian gerbils. The severity of gastritis and destruction and restoration of gastric mucosa may be related to gastric carcinogenesis. That the SS1 strain significantly accelerated carcinogenesis only in Mongolian gerbils and not in C57BL/6 mice suggests the crucial role of host factors in carcinogenesis by H. pylori infection.     

Benign epithelial gastric polyps--frequency,location, and age and sex distribution

Prospective investigation has been undertaken with the aim to study the frequency, location and age and sex distribution of various histological types of benign gastric epithelial polyps. Histological type--adenomatous, hyperplastic and fundic gland polyps--was diagnosed on the basis of at least three histological samples taken from the polyp. Biopsy samples were also taken from the antrum and the body of the stomach so that gastritis could be graded and classified, and the presence of H. pylori could be determined by histology. All 6,700 patients, who had undergone upper gastrointestinal endoscopy in a one-year period, participated in this study. Among them 42 benign gastric epithelial polyp were found in 31 patients: adenomatous gastric polyps in 7 patients, hyperplastic gastric polyp in 21 and fundic gland polyp in 3 patients. All patients with hyperplastic polyps had chronic active superficial gastritis, whereas most of the patients with adenomatous polyps had a chronic atrophic gastritis with high prevalence of intestinal metaplasia. Among 21 patients with hyperplastic gastric polyps, 16 (76%) patients were positive for H. pylori infection in contrast to only 2 patients (29%) with adenomatous gastric polyps and 1 patient (33%) with fundic gland polyp. Presented data indicates that hyperplastic gastric polyps are the most common and they are associated with the presence of chronic active superficial gastritis and concomitant H. pylori infection. Adenomatous polyps are rarer and they tend to be associated with chronic atrophic gastritis and intestinal metaplasia. Fundic gland polyp is the rarest type of gastric polyps.     

A genetic locus of Helicobacter pylori inversely associated with gastric intestinal metaplasia

The genomic contents of Helicobacter pylori strain C1 from a patient with gastric cancer and strain 98587 from a patient with duodenal ulcer disease were compared using a rapid subtractive hybridisation approach. A total of 11 tester-specific sequences representing gene specificity, DNA rearrangement and sequence variation were identified. This included two novel sequences, clone P32 and clone F5, which have no significant homologue in the database. H. pylori strains positive for clone P32 were less prevalent in patients with gastric intestinal metaplasia (12.5%) than in duodenal ulcer (39.1%) (p=0.036), or chronic gastritis (38.1%) (p=0.036). The results suggest that H. pylori clone P32 is potentially a useful marker for distinguishing intestinal metaplasia associated strains from others.     

Sequential alterations in gastric biopsies and tumor tissues support the multistep process of carcinogenesis

Gastric cancer is the second leading cause of cancer related death worldwide. In the UAE, recent data show an increase in the number of patients with gastric cancer highlighting the need for greater understanding of its pathogenesis. Gastric cancer is generally believed to develop on a background of chronic atrophic gastritis which eventually leads to intestinal metaplasia, dysplasia and finally invasive carcinoma. Recently this multistep process of carcinogenesis has been challenged. Therefore, the aim of this study is to define alterations in antral mucosal biopsies and cancer tissues to investigate whether they could be used to assemble a tissue array supporting the multistep model of carcinogenesis. Gastric mucosal tissues were obtained from informed individuals undergoing endoscopy (for upper gastrointestinal symptoms) and gastrectomy (for adenocarcinoma) in Tawam Hospital. All tissues were processed for microscopic examination. Eighty nine antral biopsies were categorized as: normal (33%), mild superficial gastritis (34%) and severe atrophic gastritis (33%). About 5% of the latter exhibited evidence of intestinal metaplasia. Cancer tissues obtained from three patients were microscopically examined in three regions: safe resected margin, tumor edge and tumor center. Progressive changes in mucosal thickness, dysplasia and cellular transformation were observed, and when compared with alterations in biopsies, all appeared to represent a continuum of progression toward invasive adenocarcinoma. In conclusion, the tissue array presented in this study supports the multistep process of gastric carcinogenesis and will be helpful in examining the expression pattern of tumor markers or molecules that could help in the early detection of gastric cancer.     

Helicobacter pylori virulence genes and host IL-1RN and IL-1beta genes interplay in favouring the development of peptic ulcer and intestinal metaplasia

Helicobacter pylori infection outcome might depend on genotypic polymorphisms of both the bacterium and the host. We ascertained: (1) the functionality of H. pylori oipA gene; (2) the polymorphism of the hostinterleukin (IL-1beta) gene (-31 C/T) and of the IL-1RN gene (intron 2 VNTR); (3) the association between the above genes and the histological and pathological outcome of H. pylori infection. One hundred and sixty-five H. pylori positive and 137 H. pylori negative subjects (23 gastric adenocarcinoma, 58 peptic ulcer, 221 gastritis) were studied. oipA was sequenced, IL-1beta was RFLP analysed. Antral and body mucosal biopsies were histologically evaluated. Functional oipA genes were correlated with cagA gene; both genes were significantly associated with gastritis activity, peptic ulcer and gastric adenocarcinoma. In these patients heterozygousIL-1RN 1/2 and IL-1beta C/T genotypes were more frequent than in gastritis patients. Intestinal metaplasia was associated with cagA, functional oipA and IL-1RN 2 allele. In conclusion, peptic ulcer and the preneoplastic intestinal metaplasia are associated with H. pylori virulence genes and with IL-1RN 2 host allele. An interplay between bacterial virulence factors and cytokines genotypes, is probably the main route causing H. pylori infection to lead to benign mild disease, benign severe disease or preneoplastic lesions.     

a-Methylacyl coenzyme A racemase is highly expressed in the intestinal-type adenocarcinoma and high-grade dysplasia lesions of the stomach

To study a-Methylacyl coenzyme A racemase (AMACR) expression in gastric intestinal-type adenocarcinoma and its precursors, we performed an immunohistochemical assay (using an avidin-biotin-peroxidase complex method) on 106 paraffin-embedded gastric mucosal biopsy samples and 25 gastrectomy samples (37 negative for dysplasia; 30 indefinite for dysplasia; 22 low-grade dysplasia; 25 high-grade dysplasia; and 34 invasive intestinal adenocarcinoma). The results showed that AMACR staining was uniformly negative in the groups negative for dysplasia and indefinite for dysplasia. Only 1 of 22 (4.5%) low-grade dysplasia showed weak staining for AMACR. In the groups of high-grade dysplasia and invasive intestinal-type adenocarcinoma, however, 19 of 25 (76%) and 18 of 34 (52.9%) were positive for AMACR respectively. Expression of AMACR was not correlated with location, H. Pylori infection or intestinal metaplasia. These results suggested that AMACR may play a role in the intermediate stage of gastric carcinogenesis. The high level expression of AMACR in high-grade dysplasia and carcinoma suggests that it may be a useful biomarker in distinguishing high-grade dysplasia and carcinoma from low-grade dysplasia.     

Genetic Mechanisms and Aberrant Gene Expression during the Development of Gastric Intestinal Metaplasia and Adenocarcinoma

Gastric adenocarcinoma occurs via a sequence of molecular events known as the Correa’s Cascade which often progresses over many years. Gastritis, typically caused by infection with the bacterium H. pylori, is the first step of the cascade that results in gastric cancer; however, not all cases of gastritis progress along this carcinogenic route. Despite recent antibiotic intervention of H. pylori infections, gastric adenocarcinoma remains the second most common cause of cancer deaths worldwide. Intestinal metaplasia is the next step along the carcinogenic sequence after gastritis and is considered to be a precursor lesion for gastric cancer; however, not all patients with intestinal metaplasia develop adenocarcinoma and little is known about the molecular and genetic events that trigger the progression of intestinal metaplasia into adenocarcinoma. This review aims to highlight the progress to date in the genetic events involved in intestinal-type gastric adenocarcinoma and its precursor lesion, intestinal metaplasia. The use of technologies such as whole genome microarray analysis, immunohistochemical analysis and DNA methylation analysis has allowed an insight into some of the events which occur in intestinal metaplasia and may be involved in carcinogenesis. There is still much that is yet to be discovered surrounding the development of this lesion and how, in many cases, it develops into a state of malignancy.Key Words: Intestinal metaplasia, gastric cancer, aberrant gene expression, genetic markers.     

Gastric mucosal changes induced by long term infection with Helicobacter pylori in Mongolian gerbils: effects of bacteria eradication.

Helicobacter pylori infection has been reported to induce various mucosal changes, including gastric adenocarcinoma, in Mongolian gerbils 62 weeks after inoculation. Using Mongolian gerbils, this study examined whether or not eradication of the bacteria with drugs at specified times after infection prevents the development of mucosal changes. After orally inoculating with H. pylori (TN2GF4, vacA- and cagA-positive), the animals were killed 18 months later. Four or 8 months after H. pylori inoculation, eradication was performed by concurrent treatment with omeprazole+clarithromycin. Immediately after treatment ended, in both the 5 and 9 month groups, it was verified that H. pylori was completely eradicated. Autopsy performed 18 months after H. pylori inoculation revealed gastric hyperplastic polyps with erosive lesions and ulcers that were grossly visible in the non-treated control group. In addition, atrophic gastritis, intestinal metaplasia, carcinoids, and adenocarcinomas were histologically observed in the animals. In animals eradicated after 4 months and autopsied after 18 months, however, such mucosal changes were not observed. In contrast, intestinal metaplasia and mucosal atrophy was observed in animals eradicated after 8 months and autopsied after 18 months. It was concluded that early eradication of H. pylori infection with drug therapy can prevent severe gastric mucosal changes, to include adenocarcinomas, in Mongolian gerbils.     

Reactive Nitrogen Species Mediate DNA Damage in Helicobacter pylori-Infected Gastric Mucosa

Background:  Reactive oxygen species (ROS) and reactive nitrogen species (RNS) can play an important role in cellular injury and carcinogenesis of gastric epithelial cells infected with Helicobacter pylori . 8-OH-deoxy guanosine (8-OHdG) and 8-nitroguanine (8-NG) are markers for ROS- and RNS-mediated DNA oxidation, respectively. In this study, RNS-mediated DNA damage in gastric mucosa was observed directly using a newly developed antibody to 8-NG to clarify how H. pylori infection causes nitrative DNA damage to gastric epithelial cells.
Methods:  Immunohistochemistry with anti-8-OHdG and anti-8-NG antibodies was performed on gastric tissue samples from 45 patients (25 men and 20 women) with H. pylori -positive gastritis and 19 patients (11 men and 8 women) exhibiting successful H. pylori eradication. Histologic factors for gastric mucosal inflammation were graded according to the guidelines of the Updated Sydney system.
Results:  In corpus mucosa, 8-OHdG and 8-NG production were significantly associated with the degree of glandular atrophy, infiltration of chronic inflammatory cells and intestinal metaplasia in the glandular epithelial cells. Successful H. pylori eradication resulted in a significant reduction of chronic inflammatory cell infiltration and neutrophilic activity. Mean 8-OHdG production was lower after H. pylori eradication in both corpus and antral mucosa ( p  = .022 and .049, respectively). However, the reduction in 8-NG exhibited was more pronounced than the reduction of 8-OhdG ( p  = .004 and .007, respectively).
Conclusions:  Helicobacter pylori infection can induce inflammatory cells infiltration, which evokes DNA damage of gastric epithelial cells through ROS and RNS production. 8-NG might be a more sensitive biomarker than 8-OHdG for H. pylori -induced DNA damage in gastric mucosa.     

Helicobacter pylori infection‐induced H3Ser10 phosphorylation in stepwise gastric carcinogenesis and its clinical implications

Background

Our previous works have demonstrated that Helicobacter pylori (Hp) infection can alter histone H3 serine 10 phosphorylation status in gastric epithelial cells. However, whether Helicobacter pylori‐induced histone H3 serine 10 phosphorylation participates in gastric carcinogenesis is unknown. We investigate the expression of histone H3 serine 10 phosphorylation in various stages of gastric disease and explore its clinical implication.

Materials and Methods

Stomach biopsy samples from 129 patients were collected and stained with histone H3 serine 10 phosphorylation, Ki67, and Helicobacter pylori by immunohistochemistry staining, expressed as labeling index. They were categorized into nonatrophic gastritis, chronic atrophic gastritis, intestinal metaplasia, low‐grade intraepithelial neoplasia, high‐grade intraepithelial neoplasia, and intestinal‐type gastric cancer groups. Helicobacter pylori infection was determined by either ¹³C‐urea breath test or immunohistochemistry staining.

Results

In Helicobacter pylori‐negative patients, labeling index of histone H3 serine 10 phosphorylation was gradually increased in nonatrophic gastritis, chronic atrophic gastritis, intestinal metaplasia groups, peaked at low‐grade intraepithelial neoplasia, and declined in high‐grade intraepithelial neoplasia and gastric cancer groups. In Helicobacter pylori‐infected patients, labeling index of histone H3 serine 10 phosphorylation followed the similar pattern as above, with increased expression over the corresponding Helicobacter pylori‐negative controls except in nonatrophic gastritis patient whose labeling index was decreased when compared with Helicobacter pylori‐negative control. Labeling index of Ki67 in Helicobacter pylori‐negative groups was higher in gastric cancer than chronic atrophic gastritis and low‐grade intraepithelial neoplasia groups, and higher in intestinal metaplasia group compared with chronic atrophic gastritis group. In Helicobacter pylori‐positive groups, Ki67 labeling index was increased stepwise from nonatrophic gastritis to gastric cancer except slightly decrease in chronic atrophic gastritis group. In addition, we noted that histone H3 serine 10 phosphorylation staining is accompanied with its location changes from gastric gland bottom expanded to whole gland as disease stage progress.

Conclusions

These results indicate that stepwise gastric carcinogenesis is associated with altered histone H3 serine 10 phosphorylation, Helicobacter pylori infection enhances histone H3 serine 10 phosphorylation expression in these processes; it is also accompanied with histone H3 serine 10 phosphorylation location change from gland bottom staining expand to whole gland expression. The results suggest that epigenetic dysregulation may play important roles in Helicobacter pylori‐induced gastric cancer.     

Effect of Helicobacter pylori infection on the expression of DNA mismatch repair protein

BACKGROUND: Helicobacer pylori infection is a major gastric cancer risk factor. Deficient DNA mismatch repair (MMR) caused by H. pylori may underlie microsatellite instability (MSI) in the gastric epithelium and may represent a major mechanism of mutation accumulation in the gastric mucosa during the early stages of H. pylori-associated gastric carcinogenesis. In this study, we examined the expression of DNA MMR protein (hMLH1 and hMSH2) in patients with chronic H. pylori infection before and after eradication of the infection. MATERIALS AND METHODS: Gastric tissue samples were collected from 60 patients with H. pylori gastritis and peptic ulcer disease before and after eradication of the infection. The DNA MMR protein expression (hMLH1 and hMSH2) was determined by immunohistochemical staining in 60 patients before and after H. pylori eradication. The percentage of epithelial cell nuclei and intensity of staining were then compared in gastric biopsies before and after eradication. RESULTS: The percentage of hMLH1 (76.60 +/- 20.27, 84.82 +/- 12.73, p=.01) and hMSH2 (82.36 +/- 12.86, 88.11 +/- 9.27, p<.05) positive epithelial cells significantly increased in 53 patients who became H. pylori-negative after eradication therapy. However, the intensity of hMLH1 and hMSH2 staining was not significantly different. In those 7 patients, who did not respond to the eradication therapy and were still H. pylori-positive, the percent positivity and intensity of hMLH1 and hMSH2 staining did not change. CONCLUSIONS: The expression of DNA MMR proteins increased in the gastric mucosa after H. pylori eradication, indicating that H. pylori gastritis may be associated with a reduced DNA MMR system during infection. The effect of H. pylori infection on MMR protein expression appears to be at least partially reversible after H. pylori eradication. These data suggest that H. pylori gastritis might lead to a deficiency of DNA MMR in gastric epithelium that may increase the risk of mutation accumulation in the gastric mucosa cells during chronic H. pylori infection.     

Atrophic Changes of Gastric Mucosa Are Caused by Helicobacter pylori Infection Rather Than Aging: Studies in Asymptomatic Japanese Adults

Background. The current study was designed to evaluate the effect of aging and Helicobacter pylori infection on the gastric mucosa in asymptomatic Japanese adults.
Materials and Methods. Eighty-five asymptomatic healthy adults were recruited from a health-screening center in Sapporo. All subjects underwent endoscopy and gastric biopsy, and serum was obtained for IgG antibodies to H. pylori , serum gastrin, and pepsinogen levels.
Results. The prevalence of atrophic change of the gastric mucosa assessed by pathological findings increased with age (49% in the 30- to 39-year-old group compared to 89% in those 60 years and older, p < .001). The frequency of intestinal metaplasia also increased with age (38% in the 30- to 39-year-old group compared to 82% in those 60 years and older, p < .001). In contrast, the frequency of atrophic gastritis and intestinal metaplasia was extremely low in the H. pylori seronegative group regardless of age. Mean serum gastrin level in H. pylori -positive adults was significantly greater than in those who were H. pylori -negative (114.3 ± 11.2 compared to 65.8 ± 6.5 pg/ml, p < .03). The serum pepsinogen I-II ratio was significantly lower in those with H. pylori infection than in those without (3.1 compared to 6.6, p < .0001).
Conclusions. These results suggest that the chronological changes in the gastric mucosa in Japanese individuals are either entirely related to H. pylori infection or the process is greatly accelerated by H. pylori infection.