Cell proliferation in Helicobacter pylori associated gastritis and the effect of eradication therapy

Antagonizing roles of SHP1 in the pathogenesis of Helicobacter pylori infection

BACKGROUND

SHP1 has been documented as a tumor suppressor and it was thought to play an antagonistic role in the pathogenesis of Helicobacter pylori infection. In this study, the exact mechanism of this antagonistic action was studied.

MATERIALS AND METHODS

AGS, MGC803, and GES-1 cells were infected with H. pylori, intracellular distribution changes of SHP1 were first detected by immunofluorescence. SHP1 overexpression and knockdown were then constructed in these cells to investigate its antagonistic roles in H. pylori infection. Migration and invasion of infected cells were detected by transwell assay, secretion of IL-8 was examined via ELISA, the cells with hummingbird-like alteration were determined by microexamination, and activation of JAK2/STAT3, PI3K/Akt, and ERK pathways were detected by immunoblotting. Mice infection model was established and gastric pathological changes were evaluated. Finally, the SHP1 activator sorafenib was used to analyze the attenuating effect of SHP1 activation on H. pylori pathogenesis in vitro and in vivo.

RESULTS

The sub-localization of SHP1 changed after H. pylori infection, specifically that the majority of the cytoplasmic SHP1 was transferred to the cell membrane. SHP1 inhibited H. pylori-induced activation of JAK2/STAT3 pathway, PI3K/Akt pathway, nuclear translocation of NF-κB, and then reduced EMT, migration, invasion, and IL-8 secretion. In addition, SHP1 inhibited the formation of CagA-SHP2 complex by dephosphorylating phosphorylated CagA, reduced ERK phosphorylation and the formation of CagA-dependent hummingbird-like cells. In the mice infection model, gastric pathological changes were observed and increased IL-8 secretion, indicators of cell proliferation and EMT progression were also detected. By activating SHP1 with sorafenib, a significant curative effect against H. pylori infection was obtained in vitro and in vivo.

CONCLUSIONS

SHP1 plays an antagonistic role in H. pylori pathogenesis by inhibiting JAK2/STAT3 and PI3K/Akt pathways, NF-κB nuclear translocation, and CagA phosphorylation, thereby reducing cell EMT, migration, invasion, IL-8 secretion, and hummingbird-like changes.

Helicobacter pylori plus N-Methyl-N’-nitro-N-nitrosoguanidine: DNA damage and repair; malignant transformation of human esophageal epithelial cells

N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG), found in pickled foods and in chlorinated water, has been used to induce malignant transformation and gastrointestinal cancer in rats. Helicobacter pylori (HP) is implicated in human gastric cancer and possibly also in esophageal cancer. These two agents - one chemical and the other biological - might act together to induce esophageal cancer. In this study, human esophageal epithelial cells (HEECs) were divided into four groups: HP, MNNG, HP + MNNG, and control. The HP-to-HEEC ratio was 100:1. Cells were exposed for 6 h and then passaged until malignant transformation. HEEC at early, intermediate, and late stages of malignant transformation were used for proliferation, cell-cycle, and invasion assays. The alkaline comet assay was performed and expression of proteins, including γ-H2AX and PAXX, was studied by western blotting, to explore DNA damage and repair processes. Measurements of cell morphology, soft-agar clone formation, and invasiveness, and a nude mouse xenograft model, were used to examine malignancy. The effect of HP was stronger than that of MNNG. The combination HP + MNNG exerted a stronger malignant transformation effect than either HP or MNNG alone. Mechanisms of this combined carcinogenesis may include promotion of cell proliferation, perturbation of the cell cycle, promotion of invasiveness, DNA double-strand break induction, or PAXX inhibition.

Helicobacter pylori-induced chronic inflammation causes telomere shortening of gastric mucosa by promoting PARP-1-mediated non-homologous end joining of DNA

Helicobacter pylori infection leads to chronic gastritis and increased risk of gastric cancer. The mechanism involves chronic inflammation. We aimed to determine the mechanism by which H. pylori infection causes telomere shortening in inflammatory gastric mucosa. Gastric biopsy specimens were obtained from 20 patients with chronic gastritis or peptic ulcer caused by H. pylori infection. The specimens showed increased NF-κB and superoxide dismutase activities and elevated expressions of PARP-1 and γ-H2AX, all of which returned to normal levels after anti-H. pylori treatment, suggesting that oxidative DNA damage and PARP-1 overexpression might cause telomere shortening. In this report, we adopted DNA end joining assay and showed that H. pylori-infected gastric mucosa had increased alternative NHEJ (non-homologous end joining), implicating that telomere shortening was caused by inflammation-mediated overproduction of reactive oxygen species and PARP-1, leading to telomere shortening.

Morphologic and Histologic Changes in Gastric Adenomas After Helicobacter pylori Eradication: A Long-Term Prospective Analysis

BACKGROUND

Helicobacter pylori infection causes gastric neoplasia via development of chronic atrophic gastritis and intestinal metaplasia. The effect of H. pylori eradication on pre-existing gastric neoplasias is still controversial. The aim of this study was to use long-term observation to clarify morphologic and histologic changes in gastric adenomas following H. pylori eradication.

MATERIALS AND METHODS

Twenty-seven patients with gastric adenomas (revised Vienna classification category 3 or 4.1) who underwent successful H. pylori eradication between April 1996 and December 1997 were followed up at regular intervals with endoscopic and histologic examination. The association between macroscopic and histologic regressions of the lesions and the following patient and lesion characteristics was assessed with univariate analysis: follow-up period, age, sex, serum pepsinogen level, lesion size, lesion location, and histologic gastritis.

RESULTS

The mean follow-up period was 91.9 months (range 44-181 months). Twelve lesions (44.4%) showed macroscopic regression, of which 7 (25.9% of the total) also showed histologic regression, with the mean duration from H. pylori eradication to complete macroscopic and histologic regression being 19.9 months. The other 15 lesions (55.6%) remained stable macroscopically and histologically, of which 6 (22.2% of the total) progressed to malignancy during the follow-up period. Univariate analysis revealed that female sex (p = .005), smaller lesion size (p = .025), higher baseline serum pepsinogen II level (p = .041), and absence of intestinal metaplasia in the greater curvature of the corpus (p = .026) were significantly associated with complete regression.

CONCLUSIONS

Helicobacter pylori eradication may induce regression in some gastric adenomas.

Helicobacter pylori protein JHP0290 exhibits proliferative and anti-apoptotic effects in gastric epithelial cells

The influence of Helicobacter pylori infection on gastric epithelial cell proliferation, apoptosis and signaling pathways contributes to the development of infection-associated diseases. Here we report that JHP0290, which is a poorly functionally characterized protein from H. pylori, regulates multiple responses in human gastric epithelial cells. The differential expression and release of JHP0290 homologues was observed among H. pylori strains. JHP0290 existed in monomeric and dimeric forms in H. pylori cell extracts and culture broth. Recombinant purified JHP0290 (rJHP0290) also showed monomeric and dimeric forms, whereas the rJHP0290 C162A mutant exhibited only a monomeric form. The dimeric form of the protein was found to bind more efficiently to gastric epithelial cells than the monomeric form. The exposure of gastric epithelial cells to rJHP0290 induced proliferation in a dose-dependent manner. Faster progression into the cell cycle was observed in rJHP0290-challenged gastric epithelial cells. Furthermore, we detected an anti-apoptotic effect of rJHP0290 in gastric epithelial cells when the cells were treated with rJHP0290 in combination with Camptothecin (CPT), which is an inducer of apoptosis. CPT-induced caspase 3 activation was significantly reduced in the presence of rJHP0290. In addition, the activation of ERK MAPK and the transcription factor NFκB was observed in rJHP0290-challenged gastric epithelial cells lines. Our results suggest that JHP0290 may affect H. pylori-induced gastric diseases via the regulation of gastric epithelial cell proliferation and anti-apoptotic pathways.

Helicobacter pylori Infection Activates the Akt-Mdm2-p53 Signaling Pathway in Gastric Epithelial Cells

BACKGROUNDS AND AIMS

Although Helicobacter pylori is widely accepted as a causative factor of many gastric diseases, the signaling pathways affected by H. pylori and subsequent effects on cell apoptosis and proliferation remain unclear. Here, we investigated the molecular mechanisms mediating H. pylori infection in gastric epithelial cells.

METHODS

Tissues from 160 patients with various gastric diseases with or without H. pylori infection were obtained and analyzed by immunohistochemistry for Akt, pAkt, Mdm2, p53, and Bax expression. In vitro, human gastric epithelial cells, GES-1, were incubated with H. pylori culture filtrates. Cell viability was measured by MTT assay. Apoptosis was evaluated by Annexin V/PI double staining followed by flow cytometry, DNA electrophoresis, and comet assay. mRNA and protein expression was assessed by RT-PCR and Western blot analysis.

RESULTS

In patient tissues, H. pylori infection was associated with significantly elevated levels of pAkt in chronic nonatrophic gastritis (CNAG), Mdm2 in dysplasia, p53 in metaplastic atrophy (MA), and Bax in CNAG and MA. In vitro, H. pylori culture filtrates reduced GES-1 cell viability in a time- and dose-dependent manner, induced G0/G1 arrest, triggered apoptosis, and increased DNA fragmentation. Mdm2 and Bax mRNA expression and pAkt, Mdm2, p53, and Bax protein expression were significantly upregulated when treated with H. pylori culture filtrates. Akt inhibition by LY294002 decreased Mdm2 expression, upregulated p53, and enhanced H. pylori-induced growth inhibition of GES-1 cells.

CONCLUSIONS

These findings suggest that Akt-Mdm2-p53 signaling is involved in the molecular response of GES-1 cells to H. pylori infection.

Myeloid HIF-1 is protective in Helicobacter pylori-mediated gastritis

Helicobacter pylori infection triggers chronic inflammation of the gastric mucosa that may progress to gastric cancer. The hypoxia-inducible factors (HIFs) are the central mediators of cellular adaptation to low oxygen levels (hypoxia), but they have emerged recently as major transcriptional regulators of immunity and inflammation. No studies have investigated whether H. pylori affects HIF signaling in immune cells and a potential role for HIF in H. pylori-mediated gastritis. HIF-1 and HIF-2 expression was examined in human H. pylori-positive gastritis biopsies. Subsequent experiments were performed in naive and polarized bone marrow-derived macrophages from wild-type (WT) and myeloid HIF-1α-null mice (HIF-1(Δmyel)). WT and HIF-1(Δmyel) mice were inoculated with H. pylori by oral gavage and sacrificed 6 mo postinfection. HIF-1 was specifically expressed in macrophages of human H. pylori-positive gastritis biopsies. Macrophage HIF-1 strongly contributed to the induction of proinflammatory genes (IL-6, IL-1β) and inducible NO synthase in response to H. pylori. HIF-2 expression and markers of M2 macrophage differentiation were decreased in response to H. pylori. HIF-1(Δmyel) mice inoculated with H. pylori for 6 mo presented with a similar bacterial colonization than WT mice but, surprisingly, a global increase of inflammation, leading to a worsening of the gastritis, measured by an increased epithelial cell proliferation. In conclusion, myeloid HIF-1 is protective in H. pylori-mediated gastritis, pointing to the complex counterbalancing roles of innate immune and inflammatory phenotypes in driving this pathology.

Magnifying narrow-band imaging of surface maturation in early differentiated-type gastric cancers after Helicobacter pylori eradication

BACKGROUND

Even after successful Helicobacter pylori eradication, primary or metachronous gastric cancers are sometimes discovered. The endoscopic features of these cancers may be modified by controlling inflammation. Characteristic findings for such lesions in terms of narrow-band imaging with magnifying endoscopy (NBI-ME) and histopathology need to be clarified to allow accurate diagnosis.

METHODS

Distinctive NBI-ME characteristics were examined retrospectively in intramucosal or minimally submucosal and differentiated-type adenocarcinomas from a successful eradication group (42 patients, 50 lesions) and a non-eradicated control group (44 patients, 50 lesions) matched in age and sex. A "gastritis-like" appearance under NBI-ME was characterized by uniform papillae and/or tubular pits with a whitish border, regular or faint microvessels and unclear demarcation, resembling the adjacent noncancerous mucosa. Histological differentiation at the luminal surface of the cancer was evaluated according to Ki-67 immunoreactivity restricted at the middle or lower portion of the tubules. NBI-ME alteration was prospectively confirmed in 29 patients (30 lesions) after eradication therapy.

RESULTS

The frequency of a "gastritis-like" appearance was 44% (22/50) for the eradication group, which was significantly higher than the 4% (2/50) for the control group (p < 0.001). In the eradication group, the "gastritis-like" appearance was significantly correlated with histological surface differentiation (p < 0.001). In the prospective study, NBI-ME showed changes to heterogeneous papillary microstructures in 43% (10/23) of the lesions after successful eradication at short-term follow-up.

CONCLUSIONS

Identification of surface maturation under NBI-ME offers a promising approach for accurate diagnosis of early gastric cancers after successful eradication.

Helicobacter pylori infection and gastric cancer

The 2005 Nobel Prize in Physiology and Medicine was awarded to Barry Marshall and Robin Warren for their discovery of Helicobacter pylori (H. pylori). Now numerous epidemiological, clinical and experimental studies and reports emphasized the crucial role of H. pylori in the pathogenesis of gastric cancer (GC), but the specific mechanism is still unknown. In this paper, we undertake a systematic review of H. pylori infection-related GC epidemiological studies, animal models of H. pylori infection-induced GC, the relationship between the virulence genes of H. pylori and GC, the links between H. pylori infection and genes related to GC, and the correlation of H. pylori infection with gastric epithelial proliferation and apoptosis.

The specific linker phosphorylation of Smad2/3 indicates epithelial stem cells in stomach; particularly increasing in mucosae of Helicobacter-associated gastritis

BACKGROUND

The gastric corpus and antrum are believed to contain epithelial stem cells in the isthmus. However, the lack of useful markers has hindered studies of their origin. We explored whether Smad2/3, phosphorylated at specific linker threonine residues (pSmad2/3L-Thr), could serve as a marker for stem cells.

METHODS

Stomachs, small intestines, and colons from Helicobacter felis-infected and noninfected C57BL/6 mice were examined. Double immunofluorescent staining of pSmad2/3L-Thr with Ki67, cytokeratin 8, or doublecortin and calcium/calmodulin-dependent protein kinase-like-1 (DCAMKL1) was performed, and pSmad2/3L-Thr immunostaining-positive cells were counted. After immunofluorescent staining, we stained the same sections with hematoxylin-eosin and observed these cells under a light microscope.

RESULTS

In infected mice, pSmad2/3L-Thr immunostaining-positive cells were significantly increased in the corpus and antrum compared with those of noninfected mice (p < 0.0001). The number of Ki67 immunostaining-positive cells in the corpus and antrum of infected mice was also much greater than in the noninfected mice. Although pSmad2/3L-Thr immunostaining-positive cells were detected among the Ki67 cells, immunohistochemical co-localization of pSmad2/3L-Thr with Ki67 was never observed. pSmad2/3L-Thr immunostaining-positive cells showed immunohistochemical co-localization with cytokeratin 8, but some of them showed co-localization or adjacent localization with DCAMKL1 immunostaining-positive cells. Under a light microscope, pSmad2/3L-Thr immunostaining-positive cells indicated undifferentiated morphological features and were confirmed in the isthmus. In small intestines and colons, pSmad2/3L-Thr immunostaining-positive cells were detected in specific epithelial cells around crypt bases, where the respective putative stem cells are thought to exist.

CONCLUSIONS

We have identified the significant expression of pSmad2/3L-Thr in specific epithelial cells of the murine stomach and have suggested these cells to be epithelial stem cells.

Cell-cycle inhibition by Helicobacter pylori L-asparaginase

Helicobacter pylori (H. pylori) is a major human pathogen causing chronic gastritis, peptic ulcer, gastric cancer, and mucosa-associated lymphoid tissue lymphoma. One of the mechanisms whereby it induces damage depends on its interference with proliferation of host tissues. We here describe the discovery of a novel bacterial factor able to inhibit the cell-cycle of exposed cells, both of gastric and non-gastric origin. An integrated approach was adopted to isolate and characterise the molecule from the bacterial culture filtrate produced in a protein-free medium: size-exclusion chromatography, non-reducing gel electrophoresis, mass spectrometry, mutant analysis, recombinant protein expression and enzymatic assays. L-asparaginase was identified as the factor responsible for cell-cycle inhibition of fibroblasts and gastric cell lines. Its effect on cell-cycle was confirmed by inhibitors, a knockout strain and the action of recombinant L-asparaginase on cell lines. Interference with cell-cycle in vitro depended on cell genotype and was related to the expression levels of the concurrent enzyme asparagine synthetase. Bacterial subcellular distribution of L-asparaginase was also analysed along with its immunogenicity. H. pylori L-asparaginase is a novel antigen that functions as a cell-cycle inhibitor of fibroblasts and gastric cell lines. We give evidence supporting a role in the pathogenesis of H. pylori-related diseases and discuss its potential diagnostic application.

Helicobacter pylori infection generates genetic instability in gastric cells

The discovery that Helicobacter pylori is associated with gastric cancer has led to numerous studies that investigate the mechanisms by which H. pylori induces carcinogenesis. Gastric cancer shows genetic instability both in nuclear and mitochondrial DNA, besides impairment of important DNA repair pathways. As such, this review highlights the consequences of H. pylori infection on the integrity of DNA in the host cells. By down-regulating major DNA repair pathways, H. pylori infection has the potential to generate mutations. In addition, H. pylori infection can induce direct changes on the DNA of the host, such as oxidative damage, methylation, chromosomal instability, microsatellite instability, and mutations. Interestingly, H. pylori infection generates genetic instability in nuclear and mitochondrial DNA. Based on the reviewed literature we conclude that H. pylori infection promotes gastric carcinogenesis by at least three different mechanisms: (1) a combination of increased endogenous DNA damage and decreased repair activities, (2) induction of mutations in the mitochondrial DNA, and (3) generation of a transient mutator phenotype that induces mutations in the nuclear genome.

Lipopolysaccharide-induced epithelial monoamine oxidase mediates alveolar bone loss in a rat chronic wound model

Reactive oxygen species (ROS) production is an antimicrobial response to pathogenic challenge that may, in the case of persistent infection, have deleterious effects on the tissue of origin. A rat periodontal disease model was used to study ROS-induced chronic epithelial inflammation and bone loss. Lipopolysaccharide (LPS) was applied for 8 weeks into the gingival sulcus, and histological analysis confirmed the onset of chronic disease. Junctional epithelium was collected from healthy and diseased animals using laser-capture microdissection, and expression microarray analysis was performed. Of 19,730 genes changed in disease, 42 were up-regulated >/=4-fold. Three of the top 10 LPS-induced genes, monoamine oxidase B (MAO/B) and flavin-containing monooxygenase 1 and 2, are implicated in ROS signaling. LPS-associated induction of the ROS mediator H(2)O(2), as well as MAO/B and tumor necrosis factor (TNF)-alpha levels were validated in the rat histological sections and a porcine junctional epithelial cell culture model. Topical MAO inhibitors significantly counteracted LPS-associated elevation of H(2)O(2) production and TNF-alpha expression in vivo and in vitro, inhibited disease-associated apical migration and proliferation of junctional epithelium and inhibited induced systemic H(2)O(2) levels and alveolar bone loss in vivo. These results suggest that LPS induces chronic wounds via elevated MAO/B-mediated increases in H(2)O(2) and TNF-alpha activity by epithelial cells and is further associated with more distant effects on systemic oxidative stress and alveolar bone loss.

15-Deoxy-delta 12, 14,-prostaglandin J2 suppresses nuclear factor-kappaB-mediated apoptosis of Helicobacter pylori-infected gastric epithelial cells

Helicobacter pylori deregulates the genes that control homeostasis between apoptosis and cell proliferation of gastric epithelial cells. Nuclear factor-kappaB (NF-kappaB) has an important role in H. pylori-induced apoptosis in gastric epithelial cells. The peroxisome proliferator-activated receptor-gamma ligand 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) regulates growth and the signaling cascade in H. pylori-infected gastric epithelial cells. In the present study, we determined whether 15d-PGJ(2) inhibits apoptosis by regulating apoptotic gene expression and NF-kappaB activation in gastric epithelial cells infected with CagA+, VacA+H. pylori in a Korean isolate (HP99). 15d-PGJ(2) was found to inhibit H. pylori-induced DNA fragmentation and cell death. 15d-PGJ(2) induced downregulation of proapoptotic Bax and upregulation of antiapoptotic Bcl-2 as well as suppression of NF-kappaB activation caused by H. pylori in gastric epithelial cells. The results suggest that 15d-PGJ(2) inhibits apoptotic cell death by inhibiting NF-kappaB activation and apoptotic gene expression in gastric epithelial cells.

Sustained epithelial proliferation in a functionally irreversible fundic mucosa after Helicobacter pylori eradication

BACKGROUND

We recently reported the expansion of the acid-secreting mucosa following Helicobacter pylori eradication with Congo red chromoendoscopy for a short-term follow-up of up to 7 months. We aimed to extend the observation period and to clarify the characteristic features of acid-secreting and non-acid-secreting mucosa.

METHODS

In 24 H. pylori-positive patients with fundic atrophy, Congo red chromoendoscopy was performed prior to, 1 month, 7 months, and finally more than 2 years after the eradication. The areas of the acid-secreting mucosa were evaluated semiquantitatively. Two gastric biopsy specimens were taken from the acid-secreting and non-acid-secreting areas at the final chromoendoscopy and were subjected to histologic evaluation and immunohistochemistry for Ki-67 as a proliferation index.

RESULTS

After a gradual increase in acid-secreting areas for up to 7 months after eradication, they further increased in 79% subjects between 7 months and the final observation at a mean follow-up of 62 months. However, there still existed non-acid-secreting mucosa in the fundic area in all subjects, indicating that the expansion of acid-secreting mucosa remained partial. Compared with the neighboring acid-secreting area, the non-acid-secreting area was characterized histologically by higher degrees of residual inflammation, mucosal atrophy, and intestinal metaplasia, and by sustained hyperproliferation as well.

CONCLUSIONS

Functionally irreversible (non-acid-secreting) gastric mucosa after eradication was associated with extensive intestinal metaplasia and sustained hyperproliferation, suggesting that such mucosa still possesses malignant potential. Congo red chromoendoscopy may be useful for estimating the risk of subsequent development of gastric cancer following successful H. pylori eradication by determining the distribution of functionally irreversible mucosa.

Helicobacter pylori infection and expression of DNA mismatch repair proteins

AIM: To determine the expression of DNA (MMR) proteins, including hMLH1 and hMSH2, in gastric epithelial cells in the patients with or without Helicobacter pylori (H pylori)-infected gastritis.

METHODS: Fifty H pylori-positive patients and 50 H pylori-negative patients were enrolled in the study. During endoscopy of patients with non-ulcer dyspepsia, two antral and two corpus biopsies were taken for histological examination (Giemsa stain) and for immunohistochemical staining of hMLH1 and hMSH2.

RESULTS: The percentage of epithelial cell nuclei that demonstrated positivity for hMLH1 staining was 84.14 ± 7.32% in H pylori-negative patients, while it was 73.34 ± 10.10% in H pylori-positive patients (P < 0.0001). No significant difference was seen between the two groups regarding the percentage of epithelial cell nuclei that demonstrated positivity for hMSH2 staining (81.16 ± 8.32% in H pylori-negative versus 78.24 ± 8.71% in H pylori-positive patients; P = 0.09).

CONCLUSION: This study indicates that H pylori might promote development of gastric carcinoma at least in part through its ability to affect the DNA MMR system.

Role of metallothionein in Helicobacter pylori-positive gastric mucosa with or without early gastric cancer and the effect on its expression after eradication therapy

BACKGROUND AND AIM

Metallothionein (MT) has a proven relationship with various kinds of cancer and reduces tissue damage. Helicobacter pylori (H. pylori) infection is associated with the alteration of gastric epithelial cell cycle events, a condition implicated in the initiation and development of gastric cancer. This study investigates the role of MT in H. pylori-induced gastritis with or without early gastric cancer (ECG) and evaluates the effect on MT expression after eradication therapy.

METHODS

Gastric biopsy samples were immunohistochemically examined for MT expression in 36 H. pylori-negative patients without ECG and 98 positive patients with or without ECG. Real time polymerase chain reaction was performed in 14 antral biopsy samples with or without H. pylori. The severity of gastritis was also evaluated according to the updated Sydney System. In 31 successfully eradicated patients, the above assessment was repeated for two consecutive years.

RESULTS

MT expression was higher in H. pylori-negative patients than in positive patients (P < 0.01). Moreover, in the corpus it was higher in H. pylori-positive patients without ECG compared to those with ECG (P < 0.05). The MT labeling index had a negative correlation with the severity of gastritis (P < 0.01). A positive correlation was shown between the MT labeling index and apoptosis: proliferation ratio (r = 0.41, P < 0.01). The MT labeling index in H. pylori-positive patients was gradually recovered after eradication (P < 0.05).

CONCLUSION

The decrease of MT expression cannot prevent tissue damage in H. pylori-positive gastric mucosa and leads to more severe gastritis. This phenomenon may be attributed to gastric carcinogenesis. H. pylori eradication increases MT expression and may reduce the risk of ECG.

Effects of aspirin on the development of Helicobacter pylori-induced gastric inflammation and heterotopic proliferative glands in Mongolian gerbils

BACKGROUND

Helicobacter pylori infection is a major cause of gastritis and gastric carcinoma. Aspirin has anti-inflammatory and antineoplastic activity. The aim of the present study was to determine the effects of aspirin on H. pylori-induced gastritis and the development of heterotopic proliferative glands.

METHODS

H. pylori strain SS1 was inoculated into the stomachs of Mongolian gerbils. Two weeks after inoculation, the animals were fed with the powder diets containing 0 p.p.m. (n = 10), 150 p.p.m. (n = 10), or 500 p.p.m. (n = 10) aspirin. Mongolian gerbils were killed after 36 weeks of infection. Uninfected Mongolian gerbils (n = 10) were used as controls. Histologic changes, epithelial cell proliferation and apoptosis, and prostaglandin E(2) (PGE(2)) levels of gastric tissue were determined.

RESULTS

H. pylori infection induced gastric inflammation. Administration of aspirin did not change H. pylori-induced gastritis, but alleviated H. pylori-induced hyperplasia and the development of heterotopic proliferative glands. Administration of aspirin accelerated H. pylori-associated apoptosis but decreased H. pylori-associated cell proliferation. In addition, the increased gastric PGE(2) levels due to H. pylori infection were suppressed by treatment with aspirin, especially at the dose of 500 p.p.m.

CONCLUSIONS

Aspirin alleviates H. pylori-induced hyperplasia and the development of heterotopic proliferative glands. Moreover, aspirin increases H. pylori-induced apoptosis. We demonstrated the antineoplastic activities of aspirin in H. pylori-related gastric carcinogenesis.

Helicobacter pylori infection induces oxidative stress and programmed cell death in human gastric epithelial cells

Helicobacter pylori infection is associated with altered gastric epithelial cell turnover. To evaluate the role of oxidative stress in cell death, gastric epithelial cells were exposed to various strains of H. pylori, inflammatory cytokines, and hydrogen peroxide in the absence or presence of antioxidant agents. Increased intracellular reactive oxygen species (ROS) were detected using a redox-sensitive fluorescent dye, a cytochrome c reduction assay, and measurements of glutathione. Apoptosis was evaluated by detecting DNA fragmentation and caspase activation. Infection with H. pylori or exposure of epithelial cells to hydrogen peroxide resulted in apoptosis and a dose-dependent increase in ROS generation that was enhanced by pretreatment with inflammatory cytokines. Basal levels of ROS were greater in epithelial cells isolated from gastric mucosal biopsy specimens from H. pylori-infected subjects than in cells from uninfected individuals. H. pylori strains bearing the cag pathogenicity island (PAI) induced higher levels of intracellular oxygen metabolites than isogenic cag PAI-deficient mutants. H. pylori infection and hydrogen peroxide exposure resulted in similar patterns of caspase 3 and 8 activation. Antioxidants inhibited both ROS generation and DNA fragmentation by H. pylori. These results indicate that bacterial factors and the host inflammatory response confer oxidative stress to the gastric epithelium during H. pylori infection that may lead to apoptosis.

Gastric epithelial cell proliferation and cagA status in Helicobacter pylori gastritis at different gastric sites

OBJECTIVE

Helicobacter pylori infection causes hyperproliferation which is believed to predispose to the development of gastric carcinoma. The aim of this study was to analyze epithelial cell proliferation topographically in H. pylori gastritis in relationship to cagA status.

MATERIAL AND METHODS

The proliferative index (PI: Ki-67-labeled nuclei/total number of foveolar nuclei) was determined in gastric mucosa biopsies taken at the antrum (lesser and greater curvatures), incisura, and corpus (greater curvature) from 78 patients with H. pylori gastritis and 20 H. pylori-negative patients. H. pylori and cagA status were determined by polymerase chain reaction (PCR) and serology.

RESULTS

PIs were significantly higher in H. pylori- and cagA-positive patients, in comparison with H. pylori- and cagA-negative patients, at all sites (p<or=0.002 and p<or=0.009) and in the antrum in comparison to the corpus, in both H. pylori-negative (p=0.04) and positive patients (p<10(-3)). At the antral lesser curvature, PIs were higher than in all the other sites, both in H. pylori- (p<or=0.002) and cagA-positive groups (p<or=0.02). The PI correlated directly and significantly with inflammation in infected patients (r=0.45, p<10(-3)) and in cagA-positive patients (r=0.41, p=0.005). The PI was significantly higher in the antrum of infected patients with atrophy (p=0.03) and intestinal metaplasia (p=0.05) than in those without atrophy and intestinal metaplasia, respectively.

CONCLUSIONS

We demonstrated that H. pylori infection and cagA-positive strains promote epithelial proliferation that was correlated with host inflammatory reaction and mostly at the antral lesser curvature, which is recognized as the area where most carcinomas arise.

Role of proteinase-activated receptor-2 on cyclooxygenase-2 expression in H. pylori-infected gastric epithelial cells

Proteinase-activated receptor-2 (PAR-2) belongs to a novel subfamily of G protein-coupled receptors with seven-transmembrane domains. PAR-2 is activated by serine proteases, such as trypsin, mast cell tryptase, and allergic or bacterial proteases. The presence of trypsin has been shown in human stomach. Cyclooxygenase-2 (COX-2) is induced by inflammatory cytokines, growth factors, gastrin, and reactive oxygen species in gastric epithelial cells, which may lead to mutagenesis and subsequent metaplasia, dysplasia, and cancer formation. We investigated whether PAR-2 is activated in H. pylori (HP99)-infected cells, which is related to COX-2 induction in gastric epithelial cells. After treatment of H. pylori to AGS (gastric adenocarcinoma) cells at a bacteria/cell ratio of 100:1, we determine the expression and the activation of PAR-2 and the expression of COX-2. The same experiments were performed in the cells treated with PAR-2 agonist peptide. mRNA and protein expression of PAR-2 and COX-2 were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting. PAR-2 activation was assessed by increase in intracellular calcium level. As a result, H. pylori induced the activation and expression of PAR-2 as well as COX-2 expression. PAR-2 agonist peptide augmented H. pylori-induced COX-2 expression in AGS cells. H. pylori induces COX-2 expression, which is mediated by both activation and expression of PAR-2 in gastric epithelial cells.

Green Tea Polyphenols Reduce Gastric Epithelial Cell Proliferation and Apoptosis Stimulated by Helicobacter pylori Infection

Recently the finding of gastric cancer in Helicobacter pylori (H. pylori)-infected mouse models was reported. Studies of humans and animal models have shown that H. pylori infection stimulates gastric epithelial cell proliferation and apoptosis. Polyphenols contained in green tea and related compounds were reported to have a variety anti-tumor effects and bactericidal properties. We studied the effect of green tea polyphenols on gastric cell proliferation and apoptosis in an H. pylori-infected mouse model. This model was prepared by inoculating Balb/c mice with 10(8) cfu of H. pylori (NCTC 11637 strain) by gavage. Beginning 18 weeks after inoculation, 0.5% polyphenols were given in drinking water every day for 2 weeks. Mice were sacrificed 1 h after bromodeoxyuridine (BrdU) was given i.p. for preparation of paraffin-embedded specimens. Cell proliferation and apoptosis were examined by the avidin-biotin complex method using anti-BrdU antibody and the TUNEL method, respectively. H. pylori infection resulted in increased BrdU-labeled cells in both the antrum and the bodies. Administration of polyphenols suppressed this increased proliferation. H. pylori infection increased apoptotic cells in both the antrum and the corpus in comparison with controls. This increase was not seen in H. pylori-infected mice given polyphenols. We conclude the administration with polyphenols might suppress gastric carcinogenesis that is in part related to H. pylori infection.

Expression of CXCL15 (Lungkine) in murine gastrointestinal, urogenital, and endocrine organs

The ELR(+) chemokine CXCL15, which recruits neutrophils during pulmonary inflammation, is also known as lungkine due to its reported exclusive expression in the lung. We now report that CXCL15 mRNA and protein are also expressed in other mucosal and endocrine organs including the gastrointestinal and urogenital tracts and the adrenal gland. Our results indicate that CXCL15 is expressed throughout the gastrointestinal tract, with the exception of the cecum. Gastric CXCL15 protein expression is approximately 10-fold lower than pulmonary expression and primarily occurs in a specific lineage of gastric epithelial cells, the prezymogenic and zymogenic cell. Similar to the increased expression of CXCL15 during pulmonary inflammation, gastric inflammation induced by infection with Helicobacter felis caused an increase in gastric CXCL15 expression. However, colonic CXCL15 expression was not altered in two different models of colonic inflammation, the Helicobacter hepaticus T-cell transfer model and the mdr1a(-/-) model of colitis. These findings clearly demonstrate that CXCL15, previously reported to be the only lung-specific chemokine, is also highly expressed in other murine mucosal and endocrine organs. The functional role of CXCL15 in mucosal disease remains to be elucidated. This manuscript contains online supplemental material at (http://www.jhc.org). Please visit this article online to view these materials.

Apoptosis in Helicobacter pylori gastritis is related to cagA status

BACKGROUND

Helicobacter pylori infection increases gastric epithelial cell apoptosis; however, the influence of cagA status is still controversial. We aimed to investigate if cagA status is related to apoptosis in H. pylori gastritis at different anatomic sites of the gastric mucosa.

MATERIALS AND METHODS

We studied by immunohistochemistry (streptavidin-biotin method) pro-apoptotic (Bax and Bak) and antiapoptotic (Bcl-2 and Bcl-x) proteins expression, scored from 0 to 4, in gastric biopsies, at the antrum (lesser and greater curvatures), incisura, and corpus (greater curvature) from 50 patients with H. pylori gastritis (22 males, 28 females, median age 40 years) and eight non-infected patients (6 males, median age 39.6 years). H. pylori and cagA status were determined by polymerase chain reaction.

RESULTS

Apoptotic proteins were expressed in a granular pattern, in the cytoplasm of foveolar cells; Bax and Bak expression was higher than Bcl-2 and Bcl-x in most cases and was significantly higher in patients infected by cagA-positive strains than in those infected by cagA-negative strains (p = .001). Bak expression was higher at the lesser curvature (antrum and incisura) than in the other regions (p = .002) and was correlated with atrophy. Anti-apoptotic proteins were significantly more expressed at the antral lesser curvature than in the other regions of the stomach (Bcl-2: p = .02; Bcl-x: p < .001).

CONCLUSIONS

Infection with cagA-positive strains is significantly associated with overexpression of pro-apoptotic proteins in the gastric mucosa, mainly at the antral lesser curvature, which may have a role on atrophy development. Anti-apoptotic proteins were also overexpressed at the lesser curvature, which may occur to keep epithelial cell turnover or might be related to malignant transformation.

Efficacy of triple therapy plus cetraxate for the Helicobacter pylori eradication in partial gastrectomy patients

In the present study, we aimed to establish an additional standardized protocol with a higher H. pylori eradication rate in the remnant stomach. Fifty-five H. pylori-positive patients were randomly allocated to one of three regimens: LAC--lansoprazole, amoxicillin, and clarithromycin b.i.d. for 7 days (n = 17); LAC+CET--LAC b.i.d. plus cetraxate q.i.d. for 7 days (n = 20); and LEFT--LAC for 7 days in a horizontal body position on the left side for 30 min (n = 18). Patient compliance and side effects were checked via interviews. H. pylori eradication was successful in 75, 72, and 41% in LAC+CET, LEFT, and LAC, respectively. The eradication rate was significantly higher in LAC+CET than in LAC (P = 0.024) but not in LEFT (P = 0.058). Adverse events that occurred in each group were almost all mild ones. Cetraxate plus LAC for 1 week is a safe and effective regime for the eradication of H. pylori in patients after partial gastrectomy.

The relation of Helicobacter pylori to gastric adenocarcinoma and lymphoma: pathophysiology, epidemiology, screening, clinical presentation, treatment, and prevention

Helicobacter pylori infection may be the most common chronic bacterial infection worldwide; however, the prevalence varies between countries and is usually linked to socioeconomic conditions. Gastric cancer is one of the most frequent cancers in developing countries and usually about the seventh most common in developed countries. This article explores the relation of H. pylori to gastric adenocarcinoma and lymphoma. The pathophysiology, epidemiology, screening, clinical presentation, treatment, and prevention are discussed.

Gastrin and interleukin-1beta stimulate growth factor secretion from cultured rabbit gastric parietal cells

The hormone gastrin stimulates proliferation of the gastric mucosa. Inflammation of the stomach is also associated with increased proliferation. The proliferative response is important in the reparative response to injury but can be deleterious by predisposing to the development of cancer. Parietal cells, but not the cells in the proliferative zone of the gastric glands, express the appropriate gastrin receptor. Parietal cells may mediate the trophic effects of gastrin by secreting other growth factors. The role of parietal cells in the proliferative responses has been examined in this study. Rabbit parietal cells were cultured with gastrin or the cytokine interleukin-1beta for 18 hours. The conditioned medium from gastrin or IL-1beta stimulated parietal cells increased proliferation of HeLa cells in an epidermal growth factor-receptor dependant manner. Gastrin and IL-1beta stimulated the secretion of heparin-binding epidermal growth factor and amphiregulin but not transforming growth factor-alpha from parietal cells. Combinations of gastrin and IL-1beta on growth factor secretion were synergistic. The protein kinase C inhibitor staurosporine abolished these stimulatory effects of gastrin and IL-1beta. Divergent effects on histamine-stimulated acid secretion were observed; 18 hours pre-treatment with gastrin enhanced acid secretion by 50% but IL-1beta inhibited acid secretion in both control and gastrin pre-treated parietal cells. The acid-secreting parietal cell plays a central role in the regulation of mucosal proliferation in gastric inflammation. Secretion of paracrine growth factors by parietal cells may be an important point of integration between the endocrine and inflammatory stimuli in determining mucosal responses to injury and inflammation.

Helicobacter pylori and molecular mechanisms of gastric carcinogenesis: targets for prevention and therapy

Gastric cancer is still a leading cause of cancer death worldwide. It is frequently diagnosed in an advanced stage and the overall prognosis is dismal. A major improvement will only be reached with a better understanding of the genetic changes underlying gastric cancer, which may provide us with effective prevention and treatment strategies. This review will highlight the present knowledge on the role of Helicobacter pylori in gastric carcinogenesis and the molecular pathogenesis of gastric cancer, as well as provide a brief overview of possible future targets for more specific and successful treatment options.

Increased oxidative DNA damage, inducible nitric oxide synthase, nuclear factor κB expression and enhanced antiapoptosis-related proteins in Helicobacter pylori-infected non-cardiac gastric adenocarcinoma

AIM: Several epidemiological studies have demonstrated a close association between Helicobacter pylori (H Pylori) infection and non-cardiac carcinoma of the stomach. H pylori infection induces active inflammation with neutrophilic infiltrations as well as production of oxygen free radicals that can cause DNA damage. The DNA damage induced by oxygen free radicals could have very harmful consequences, leading to gene modifications that are potentially mutagenic and/or carcinogenic. The aims of the present study were to assess the effect of H pylori infection on the expression of inducible nitric oxidative synthase (iNOS) and the production of 8 -hydroxy-deoxyguanosine (8-OHdG), a sensitive marker of oxidative DNA injury in human gastric mucosa with and without tumor lesions, and to assess the possible factors affecting cell death signaling due to oxidative DNA damage.

METHODS: In this study, 40 gastric carcinoma specimens and adjacent specimens were obtained from surgical resection. We determined the level of 8-OHdG formation by HPLC-ECD, and the expression of iNOS and mechanism of cell death signaling [including nuclear factor-κB(NFκB), MEKK-1, Caspase 3, B Cell lymphomal leukemia-2 (Bcl-2), inhibitor of apoptosis protein (IAP ) and myeloid cell leukemia-1 (Mcl-1)] by Western-blot assay.

RESULTS: The concentrations of 8-OHdG, iNOS, NFκB, Mcl-1 and IAP were significantly higher in cancer tissues than in adjacent non-cancer tissues. In addition, significantly higher concentrations of 8-OHdG, iNOS, NFκB, Mcl-1 and IAP were detected in patients infected with H pylori compared with patients who were not infected with H pylori. Furthermore, 8-OHdG, iNOS, NFκB, Mcl-1 and IAP concentrations were significantly higher in stage 3 and 4 patients than in stage 1 and 2 patients.

CONCLUSION: Chronic H pylori infection induces iNOS expression and subsequent DNA damage as well as enhances anti-apoptosis signal transduction. This sequence of events supports the hypothesis that oxygen-free radical-mediated damage due to H pylori plays a pivotal role in the development of gastric carcinoma in patients with chronic gastritis.

Gastric and duodenal mucosal protein fractional synthesis and growth factor expression in patients with H. pylori-associated gastritis before and after eradication of the organism

Our purpose was to study the effect of Helicobacter pylori (HP) on mucosal protein fractional synthesis (MPFS) and growth factor expression. 14C-leucine incorporation, and TGF-alpha, beta-FGF, and EGF-receptor levels were assessed in gastric and duodenal mucosa in 20 patients with HP-associated gastritis and repeated after treatment of the gastritis, with or without eradication of the organism. At entry, MPFS in the fundus, antrum, and duodenum was 43.1, 38.2, and 28.3%/day, respectively. Following HP eradication, fundal and antral rates fell to 28.1 and 21.4%/day (P < 0.05), whereas the duodenum was unchanged. MPFS in the patient subset not eradicated remained similar to entry values (35.9, 31.6, and 25.4%/day). Expression of TGF-alpha, beta-FGF, and EGF receptors was unchanged. Eradication of HP results in reduction of gastric, but not duodenal, MPFS and has no effect on the growth factors measured. Increased MPFS associated with HP gastritis may relate to the potential for neoplastic transformation.

Cell kinetic balance in gastric mucosa with intestinal metaplasia after Helicobacter pylori eradication: 2-year follow-up study

BACKGROUND

Proliferation and apoptosis events are altered in Helicobacter pylori infection. However, whether H. pylori eradication has an effect on the disturbed kinetics in metaplastic mucosa has not been well elucidated.

AIM

To investigate the effect of eradication on the gastric cell kinetics.

SUBJECTS AND METHODS

Initially, biopsies were obtained from 74 H. pylori-infected subjects and repeated 12 and 24 months after eradication. Biopsies were immunohistochemically stained for apoptosis by single-stranded DNA, for proliferation by Ki-67 antibodies and for intestinal metaplasia MUC2, MUC5AC, MUC6 and CD10.

RESULTS

While antral apoptosis in intestinal metaplasia was significantly lower than in non-intestinal metaplasia, proliferation was significantly higher (greater and lesser curvatures, P < 0.05, respectively). This resulted in a significantly lower apoptosis/proliferation ratio in intestinal metaplasia than in non-intestinal metaplasia (antrum greater and lesser curvatures and corpus greater curvature, P < 0.05). After successful eradication, apoptosis and proliferation decreased in both intestinal metaplasia and non-intestinal metaplasia. The pattern of reduction of apoptosis and proliferation differed in these two groups. However, in the corpus, the reduction resulted in a significant increase in the apoptosis/proliferation ratio in both.

CONCLUSION

Proliferation and apoptosis are unevenly and disproportionately altered in H. pylori infection leading to an imbalance in cell kinetics. Eradication of the organism improves the balance and may possibly play a role in the prevention of malignancy transformation in the metaplastic mucosa.

Prevention of gastric cancer by Helicobacter pylori eradication

The evidence supporting the important role of Helicobacter pylori causing gastric cancer is getting stronger. The mechanisms by which H. pylori can influence the progression to severe changes in the gastric mucosa are under investigation. An increased gastric epithelial cell proliferation has been observed in individuals infected with H. pylori. This lifelong increased cell turnover is deemed to be a major risk factor for increased mutational changes and may lead to the development of gastric cancer. Successful eradication of H. pylori infection induces the healing of the gastritis and a significant decrease in gastric epithelial cell proliferation. Nevertheless, it is right now unknown at which time the point of no return, meaning at which time an eradication therapy leads to a benefit for the individual to prevent gastric cancer, has been reached. Therefore the major question that arises is to whom an eradication therapy should be offered to prevent gastric cancer. A general elimination of the infection might be worthwhile, but seems to be unrealistic now because of the high prevalence of the infection and the missing of a vaccine. This review reflects possible mechanisms of gastric cancer development induced by chronic H. pylori infection and recent investigational trials for prevention of gastric cancer by H. pylori eradication therapy will be discussed.

Altered cardia epithelial cell kinetics induced by Helicobacter pylori infection and gastro-oesophageal reflux disease: possible malignant potential?

BACKGROUND

The incidence of adenocarcinoma of the proximal stomach (cardia) is increasing. The pathophysiological processes underlying this trend are unclear. Normal cell turnover depends on cell proliferation being in balance with programmed cell death or apoptosis. It has been well documented that excessive proliferation potentiates the effects of any carcinogen that targets DNA. It is therefore accepted that excessive proliferation is a risk factor for subsequent neoplasia development.

AIMS

To compare apoptosis and proliferation in normal cardia tissue, carditis, and cardia intestinal metaplasia, and to determine the effect of Helicobacter pylori infection and gastro-oesophageal reflux disease.

METHODS

Biopsies from the cardia were obtained from consecutive dyspeptic patients and asymptomatic controls at the time of gastroscopy. Samples were assessed histologically and classified as normal, carditis, or cardia tissue with intestinal metaplasia. All samples were then examined, employing immunohistochemical techniques, for the presence of proliferating and apoptotic cells.

RESULTS

A total of 76 histological specimens were examined. There was a statistical significant difference in the proliferation index between controls and both carditis and cardia intestinal metaplasia, and also between carditis and cardia intestinal metaplasia. In contrast, there was a significant increase in the apoptotic index for carditis compared with controls, while that of intestinal metaplasia did not differ from controls. As a result, comparison of the apoptotic/proliferation ratios for each group revealed that, for both carditis and cardia intestinal metaplasia, the apoptotic index/proliferation index ratio is reduced significantly compared with controls, but as a result of different mechanisms.

CONCLUSION

This study demonstrates that individuals with carditis and cardia intestinal metaplasia have alterations in epithelial cell kinetics. In particular, it shows that there is a persistent imbalance between proliferation and apoptosis, which may represent malignant potential.

Review article: test and treat or test and scope for Helicobacter pylori infection. Any change in gastric cancer prevention?

A 'test and treat' strategy is advocated for patients with dyspepsia under the age of 45 years, with endoscopy reserved for those with alarm symptoms or aged over 45 years. One of the consequences of this strategy will be a reduction in population infection rates of Helicobacter pylori. It is now clear that H. pylori is one of the prime initiators of gastric cancer with up to 70% of gastric cancers attributable to H. pylori. What remains unclear is if H. pylori reduction will lead to a reduction in gastric cancer.

Delta (13)C-urea breath test value is a useful indicator for Helicobacter pylori eradication in patients with functional dyspepsia

BACKGROUND

Eradication of Helicobacter pylori is not routinely recommended for the symptomatic relief and the prevention of gastric cancer in patients with functional dyspepsia. The present study investigated a useful indicator of H. pylori eradication in such patients by determining the optimal cutoff value of a 13C-urea breath test (UBT).

METHODS

One hundred dyspeptic patients participated in the study. Dyspepsia was scored, and a 13C-UBT administered. A level of delta 13C-UBT of>4 per thousand was diagnosed as H. pylori-positive. After the stomach was endoscopically sprayed with phenol red, biopsy specimens were taken from the antrum, body and cardia of the stomach for the assessment of H. pylori density, and activity (neutrophil infiltration) and degree (lymphocyte infiltration) of gastritis.

RESULTS

Correlation between delta 13C-UBT and dyspepsia score was not found. Delta 13C-UBT significantly correlated with H. pylori density score in the total stomach (r = 0.53, P < 0.0001), neutrophil (r = 0.34, P = 0.0005) and lymphocyte score (r = 0.69, P < 0.0001). Twenty-six of the 100 subjects had a neutrophil score of >or=4, lymphocyte score of >or=4, and H. pylori score of >or=4. Their 95% confidence interval of mean was 58.2 per thousand, which reflects moderate to marked acute and chronic gastritis, and dense H. pylori colonization.

CONCLUSIONS

The 13C-UBT is a reliable semiquantitative test to assess H. pylori density and the activity and degree of gastritis. It is proposed that H. pylori eradication therapy might be beneficial for patients with functional dyspepsia with a delta 13C-UBT of >58.2 per thousand.

Is apoptosis in antral mucosa correlated with serum nitrite concentration in Japanese Helicobacter pylori-infected patients?

BACKGROUND AND AIM

Helicobacter pylori infection in gastric mucosa is a form of chronic active gastritis that leads to expression of inducible nitric oxide synthase in host macrophages and polymorphonuclear leukocytes. Nitric oxide produced by these cells infiltrating the gastric mucosa could damage DNA. We correlated apoptosis in H. pylori-infected antral tissue from peptic ulcer patients with serum nitrate-plus-nitrite.

METHODS

Biopsy specimens were obtained endoscopically from antrum and fundus in 17 peptic ulcer patients before and after H. pylori eradication. Tissue samples were subjected to rapid urease testing and histopathological scoring (updated Sydney system), as well as immunohistochemical detection of single-stranded DNA indicating apoptotic cells. Fasting serum samples were analyzed for combined nitrate and nitrite content.

RESULTS

In all cases atrophy was absent to mild in antral mucosa and H. pylori was eradicated successfully. A strong positive correlation was present between apoptosis and both inflammation and activity scores in infected antral mucosa. A significant positive correlation also was noted between apoptosis and H. pylori density. Serum nitrite concentrations were decreased significantly by successful eradication of H. pylori, and showed a strong positive correlation with H. pylori density. Serum nitrite concentrations showed a significant positive correlation with numbers of single-stranded DNA-positive cells.

CONCLUSIONS

High H. pylori density was associated with elevated serum nitrate-plus-nitrite (a marker of nitric oxide production in gastric mucosa). Increased apoptosis and abnormal gastric cell turnover are likely results.

Change in apoptosis in the gastric surface epithelium and glands after eradication of Helicobacter pylori

BACKGROUND

Change in apoptosis in gastric glands after eradication of Helicobacter pylori has never been reported.

AIMS

The purpose of this paper is to investigate the change in apoptosis in gastric glands after eradication of Heliobacter pylori.

PATIENTS AND METHODS

We studied 23 Heliobacter pylori-positive patients with duodenal and gastric ulcers, who were monitored for 6-12 months after eradication, and eight controls. Biopsies were taken from the antrum and body. Apoptosis was evaluated immunohistochemically using anti-single stranded DNA antibody. Apoptotic index was calculated by counting immunostained cells in surface epithelial and glandular cells.

RESULTS

In the surface epithelium, Apoptotic indexes were significantly higher in patients than in controls. In the upper portion of fundic glands, apoptotic indexes were significantly higher in patients with gastric ulcers (14.2% (9.3, 17.8)) (median (1st quartile, 3rd quartile)) than in controls (8.0% (2.0, 9.0), p < 0.01) and decreased significantly after eradication (3.4% (2.0, 5.3)), p < 0.01). In pyloric glands, apoptotic indexes were no different between patients and controls. In the lower portion of fundic glands, apoptotic indexes were very low, both in patients and in controls.

CONCLUSIONS

Our results showed that apoptosis, not only of surface epithelial cells but also of glandular cells in the upper portion of fundic glands, increased in Heliobacter pylori-positive patients with gastric ulcers and decreased to normal levels after eradication of Heliobacter pylori.

The effect of Helicobacter pylori infection on levels of DNA damage in gastric epithelial cells

BACKGROUND

Helicobacter pylori infection leads to an increased risk of developing gastric cancer. The mechanism through which this occurs is not known. We aimed to determine the effect of H. pylori and gastritis on levels of DNA damage in gastric epithelial cells.

METHODS

Epithelial cells were isolated from antral biopsies from 111 patients. DNA damage was determined using single cell gel electrophoresis and the proportion of cells with damage calculated before and 6 weeks after eradication of H. pylori. Cell suspensions generated by sequential digestions of the same biopsies were assayed to determine the effect of cell position within the gastric pit on DNA damage.

RESULTS

DNA damage was significantly higher in normal gastric mucosa than in H. pylori gastritis [median (interquartile range) 65% (58.5-75.8), n = 18 and 21% (11.9-29.8), n = 65, respectively, p <.001]. Intermediate levels were found in reactive gastritis [55.5% (41.3-71.7), n = 13] and H. pylori negative chronic gastritis [50.5% (36.3-60.0), n = 15]. DNA damage rose 6 weeks after successful eradication of H. pylori[to 39.5% (26.3-51.0), p =.007] but was still lower than in normal mucosa. Chronic inflammation was the most important histological factor that determined DNA damage. DNA damage fell with increasing digestion times (r = -.92 and -.88 for normal mucosa and H. pylori gastritis, respectively).

CONCLUSIONS

Lower levels of DNA damage in cells isolated from H. pylori infected gastric biopsies may be a reflection of increased cell turnover in H. pylori gastritis. The investigation of mature gastric epithelial cells for DNA damage is unlikely to elucidate the mechanisms underlying gastric carcinogenesis.

Review article: gastric cancer and Helicobacter pylori

Gastric cancer is the second commonest cause of death from malignancy in the world. Its pathogenesis is comparatively well understood and its aetiology multifactorial. Non-cardia gastric cancer usually arises in a stomach that has been inflamed over a long period and where atrophy and intestinal metaplasia have supervened. The commonest cause of gastric inflammation is infection with Helicobacter pylori. Colonization with this organism increases the relative risk of developing this cancer by about six [Helicobacter and Cancer Collaborative Group. Gut 2001; 49: 347-53]. Its likelihood increases with the severity and extent of the gastritis. Severity is influenced by the virulence of the infecting organism, the genetics of the host, bile reflux, dietary factors and the presence of hypochlorhydria which influences the extent, as well as the severity, of the inflammation. The only predisposing factor which can easily be manipulated is H. pylori infection, which can be successfully treated in 80-90% of cases using a 1-week therapeutic regimen.

Effect of interlukin-1beta on proliferation of gastric epithelial cells in culture

BACKGROUND

Helicobacter pylori is the main risk factor for the development of non-cardia gastric cancer. Increased proliferation of the gastric mucosa is a feature of H. pylori infection. Mucosal interkeukin-1beta production is increased in H. pylori infection and IL-1beta genotypes associated with increased pro-inflammatory activity are risk factors for the development of gastric cancer. The effect of IL-1beta on gastric epithelial cell proliferation has been examined in this study.

METHODS

AGS cells were cultured with IL-1beta. DNA synthesis was assed by [3H]thymidine incorporation and total viable cell numbers by MTT assay.

RESULTS

IL-1beta dose dependently increased DNA synthesis and cell numbers. The enhanced proliferation was blocked by interleukin-1 receptor antagonist. Addition of neutralising antibody to GM-CSF reduced IL-1beta-stimulated proliferation by 31 +/- 4 %. GM-CSF alone significantly stimulated proliferation. Addition or neutralisation of IL-8 had no effect on basal or IL-1beta-stimulated proliferation. The tyrosine kinase inhibitor genistein completely blocked IL-1beta-stimulated proliferation and inhibition of the extracellular signal related kinase pathway with PD 98059 inhibited IL-1beta stimulated proliferation by 58 +/- 5 %.

CONCLUSIONS

IL-1beta stimulates proliferation in gastric epithelial cells. Autocrine stimulation by GM-CSF contributes to this proliferative response. Signalling via tyrosine kinase activity is essential to the mitogenic response to IL-1beta. The extracellular signal related kinase pathway is involved in, but not essential to downstream signalling. IL-1beta may contribute to the hyperproliferation seen in H. pylori- infected gastric mucosa, and be involved in the carcinogenic process.

Effect of Helicobacter pylori-induced cyclooxygenase-2 on gastric epithelial cell kinetics: implication for gastric carcinogenesis

BACKGROUND

Cyclooxygenase (COX)-2 induced by Helicobacter pylori is thought to enhance gastric carcinogenesis by affecting the maintenance of epithelial homeostasis.

MATERIALS AND METHODS

Gastric biopsies from 160 subjects, 97 with nonulcer dyspepsia (47 H. pylori negative, 50 H. pylori positive) and 63 with gastric cancer were examined immunohistochemically for COX-2 expression, cell proliferation and apoptotic indices.

RESULTS

COX-2 expression in corpus was significantly higher in H. pylori positive than in negative non-ulcer dyspepsia (NUD) (p <.05). Regardless of site, gastric cancer subjects had higher COX-2 expression in both antrum and corpus compared with H. pylori negative and positive NUD (p <.005). Proliferation was higher in cancer and H. pylori positive than in negative NUD (p <.0001). Moreover, cancer had enhanced proliferation than H. pylori positive NUD in corpus greater (p =.0454) and antrum lesser (p =.0215) curvatures. Apoptosis was higher in H. pylori positive than in negative NUD (p <.05). However, both had a higher index than the cancer subjects (p <.0001). Apoptosis : proliferation ratio was higher in corpus of H. pylori negative than in positive NUD in greater (p =.0122) and lesser (p =.0009) curvatures. However, both had a higher A:P ratio than cancer cases (p =.0001). A negative correlation between COX-2 expression and A:P ratio was found in corpus greater (r = -.176, p =.0437) and lesser (r = -.188, p =.0312) curvatures.

CONCLUSION

The expression of COX-2 is associated with disruption in gastric epithelial kinetics and hence may play a role in gastric carcinogenesis.

Cyclooxygenase-2 expression is increased in early intestinal-type gastric cancer and gastric mucosa with intestinal metaplasia

OBJECTIVE

Cyclooxygenase-2 (COX-2) expression is increased in gastric cancer. We examined COX-2 expression in early stage gastric cancer and background mucosa to elucidate the role of COX-2 in gastric carcinogenesis.

METHODS

Thirty-three early gastric cancers obtained from 30 patients infected with Helicobacter pylori were studied. Twenty-three patients had an intestinal, four patients had a diffuse, and three patients had both an intestinal and a diffuse type cancer. Expression of COX-2 protein was detected by immunohistochemistry by counting the number of positive staining cells per 100 cells.

RESULTS

Mean COX-2 expression was 84.1 (SD 11.4) in 26 intestinal type cancers and was significantly higher than that in seven diffuse type cancers (23.1 +/- 9.7) (P < 0.001). In three patients who had both the intestinal and the diffuse type cancer, COX-2 expression was 92, 90 and 83 in the intestinal type cancer and only 25, 24 and 7 in the corresponding diffuse type cancer. In 18 patients who had intestinal metaplasia (15 had incomplete metaplasia), COX-2 expression was 60.2 (24.2) in the crypts with metaplasia while it was only 16.8 (10.7) in the crypts without metaplasia (P < 0.001).

CONCLUSIONS

COX-2 expression may be associated with the carcinogenesis of the intestinal type gastric cancer and, speculatively, inhibition of COX-2 might have preventative effects on the intestinal type gastric cancer.

No difference in the level of gastric mucosal cell apoptosis and proliferation in Helicobacter pylori-colonized p53 heterozygous knockout mice

BACKGROUND

We previously reported that attenuated epithelial apoptosis and enhanced proliferation in comparison with mice might link to the specific carcinogenesis in Mongolian gerbils and suggested that the difference in both strains might be due to a difference in genetic background. p53 is a well-known tumour suppressor gene, mutation of which is also known to be involved in gastric cancer formation.

AIM

The present study was designed to examine the level of gastric epithelial apoptosis and proliferation in p53 heterozygous knockout mice (p53+/-) colonized with Helicobacter pylori (Sydney strain: SS1).

METHODS

Female p53+/- mice and wild-type controls were orally inoculated with SS1 and the stomachs were examined 24 weeks later. DNA fragmentation was measured by levels of cytoplasmic mono- & oligo-nucleosomes as well as by the TUNEL method. Gastric mucosal proliferative activity was morphometrically evaluated from the PCNA-stained tissue specimens. Gastric mucosal myeloperoxidase (MPO) activity was measured to evaluate mucosal inflammation.

RESULTS

DNA fragmentation and the number of TUNEL-positive cells, as well as PCNA-positive cell number increased significantly in both groups of H. pylori-infected mice, suggesting that levels of apoptosis and proliferation may be independent of a deficiency of one p53 allele. MPO activity in p53+/- mice and wild-type controls increased to the same level.

CONCLUSION

Although H. pylori inoculation per se induces an increase in cell turnover in mice, heterozygous mutation of p53 did not significantly modify the balance in cell apoptosis and proliferation.

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.

Effect of Helicobacter pylori infection on gastric cell proliferation and genomic instability in a paediatric population of southern Italy

BACKGROUND

The incidence of gastric cancer is high in areas with a high prevalence of Helicobacter pylori infection. Cell transformation and tumour progression occur over a long period of time and markers of genomic instability usually precede morphological changes.

AIM

To evaluate the effect of Helicobacter pylori infection on cell proliferation, DNA status and oncogene expression in children.

PATIENTS AND METHODS

Morphometric and immunohistochemical techniques were used to analyse DNA content, p53 and c-myc oncogene expression and cell proliferation on gastric biopsies of 53 children (27 Helicobacter pylori-negative and 26 Helicobacter pylori-positive).

RESULTS

Gastric mucosa was normal in 11% of Helicobacter pylori-positive and in 33% of Helicobacter pylori-negative subjects. Most children had chronic non-atrophic gastritis regardless of Helicobacter pylori infection, and only a minority of children affected by Helicobacter pylori had mild atrophic gastritis. Cell proliferation was significantly higher in children with Helicobacter pylori-positive gastritis than in those with Helicobacter pylori-negative gastritis. No metaplasia, dysplasia, p53 overexpression or altered DNA content was found in any child. Interestingly, 46% of children with and 29% without Helicobacter pylori infection had c-myc overexpression closely related to the cell proliferation rate.

CONCLUSION

Helicobacter pylori infection in children may coexist with a normal gastric mucosa, and it is not associated with genomic instability markers in cases of chronic gastritis.