Global analysis of Helicobacter pylori gene expression in human gastric mucosa

BACKGROUND & AIMS: Helicobacter pylori inhabits a highly restricted ecological niche in the human gastric mucosa. Microbial gene expression in the context of persistent infection remains largely uncharacterized. METHODS: An RNA analysis method, selective capture of transcribed sequences, was used in conjunction with genomic array hybridization to characterize H. pylori complementary DNAs (cDNAs) obtained from both human and experimentally infected gerbil gastric tissue specimens. RESULTS: Bacterial cDNAs obtained by selective capture of transcribed sequences from tissues hybridized to arrayed DNA fragments representing approximately 70% of open reading frames in the H. pylori genome. RNAs for most of these open reading frames were also detected by array hybridization analyses of total RNA prepared from the isolated H. pylori strains cultured in vitro. However, a subset of H. pylori RNAs detected in gastric tissue specimens was consistently undetectable in bacteria grown in vitro. The majority of these RNAs encode factors unique to H. pylori that are potentially produced in response to interactions with mammalian gastric mucosa. CONCLUSIONS: The combination of selective capture of transcribed sequences with array hybridization has allowed a global analysis of bacterial gene expression occurring in human tissues during a natural infection.     

Effect of Helicobacter pylori infection on ghrelin expression in human gastric mucosa

OBJECTIVES: One of the counter-effects of Helicobacter pylori eradication therapy is subsequent obesity. Ghrelin is a recently discovered growth hormone releasing peptide. This endogenous secretagogue increases appetite and facilitates fat storage. The majority of circulating ghrelin is produced in the gastric mucosa. Therefore, we aimed at investigating changes in ghrelin immunoreactivity in gastric mucosa tissues of patients infected with H. pylori. METHODS: Sixty-one patients with H. pylori infection (25 cases each of duodenal and gastric ulcer, and 11 cases of gastritis) and 22 healthy controls without H. pylori infection were included in the study. H. pylori-infected patients received standard proton pump-based triple therapy followed by histological examination and (13)C-urea breath test to confirm H. pylori eradication. H. pylori was eradicated in 50 out of 61 patients. Biopsy specimens were obtained from antrum and corpus before and 3 months following eradication. Ghrelin expression was evaluated immunohistochemically with an anti-ghrelin antibody, and the number of ghrelin-positive cells determined per 1 mm(2) of the lamina propria mucosa. RESULTS: There was no relationship between ghrelin immunoreactivity and body weight or body mass index for healthy controls. The number of ghrelin-positive cells was significantly lower for H. pylori-infected patients than for healthy controls. However, the ghrelin-positive cell number increased significantly following H. pylori eradication without significant change in severity of atrophy. CONCLUSIONS: These data indicated that H. pylori infection affected ghrelin expression. After H. pylori eradication, gastric tissue ghrelin concentration increased significantly. This could lead to the increased appetite and weight gain seen following H. pylori eradication.     

幽门螺杆菌感染诱导胃黏膜上皮细胞凋亡及端粒酶逆转录酶表达

目的研究幽门螺杆菌（Hp）根除前后胃黏膜上皮细胞凋亡和端粒酶逆转录酶（hTERT）表达及其与bcl-2、c-myc蛋白表达的关系。方法采用脱氧核糖核酸末端转移酶介导的缺口末端标记（TUNEL）技术及免疫组化染色方法检测39例却Hp性患者根除治疗及21例却阴性患者对症治疗前后胃黏膜上皮细胞凋亡、hTERT、bcl-2、c—myc蛋白表达的变化。结果治疗前却阳性者胃黏膜上皮细胞凋亡指数为16．2％，显著高于却阴性者（P〈0．05）；却阳性者hTERT、c—myc蛋白表达显著高于却阴性者（53．8％比23．8％；53．8％比28．6％，P〈0．05）。邯根除者治疗后胃黏膜上皮细胞凋亡、hTERT及bcl-2、c—myc蛋白表达与根除前相比均显著下降（16．9％比9．0％；59．3％比22．2％；59．3％比25．9％；59．3％比14．8％，P〈0．01），且与却阴性对照组相比差异无统计学意义（P〈0．05）；而邯未根治组及对照组上述指标均无显著变化。治疗前bcl-2、c—myc蛋白与hTERT呈显著正相关，秩相关系数r分别为0．269、0．474（P〈0．05）。结论却感染诱导细胞凋亡及hTERT过度表达，使胃黏膜不稳定性增加。根除却可纠正细胞凋亡失调，使hTERT表达下降或消失，从而降低胃癌发生的可能性。bcl-2及c—myc蛋白对hTERT表达可能具有调控作用。     

Helicobacter pylori infection affects Toll-like receptor 4 expression in human gastric mucosa

BACKGROUND/AIMS: Toll-like receptor 4 (TLR4), which requires a helper molecule, MD-2, is a main receptor for lipopolysaccharide (LPS) from gram-negative bacteria. The expression of TLR4 in H. pylori infection in human gastric mucosa, however, is unclear. The aim of this study was to determine the effect of H. pylori infection on the TLR4 and MD-2 expression in human gastric mucosa. METHODOLOGY: Biopsy samples from the antrum and corpus were obtained from 45 patients (25 patients without H. pylori infection including 5 patients with successful eradication of H. pylori, and 20 patients with H. pylori infection). These samples were used for TLR4, MD-2 mRNA expression study and immunohistochemical study. RESULTS: In patients without H. pylori infection, the expressions of TLR4 and MD-2 were bigger in the corpus mucosa than in the antral mucosa. In patients with H. pylori infection, the expressions of TLR4 and MD-2 significantly increased in the antral and corpus mucosa. Immunohistochemical study revealed similar results as the TLR4 mRNA expression. After the eradication of H. pylori, the expressions of TLR4 and MD-2 were the same levels in both sites as those in patients without H. pylori infection. CONCLUSIONS: The results indicated that H. pylori infection significantly increased TLR4 and MD-2 expressions in the antral and corpus mucosa.     

Effect of Helicobacter pylori VacA on gene expression of gastric cancer cells

AIM: To determine the effect of Helicobacter pylori VacA on gene expression of gastric cancer cells. METHODS: Gene expression profile of a gastric cancer cell line, SGC7901, after challenged by VacA~+ and VacA~- H pylori broth culture supernatants (BCS), was detected by the cDNA microarray technique. Cytoskeleton changes of SGC7901 and HeLa cells were observed through high-resolution laser scanning confocal microscopy. RESULTS: A total of 16 000 cDNA clones were detected. The percentage of genes with heterogeneous expression in SGC7901 cells challenged by VacA~+ BCS reached 5%, compared with that challenged by VacA~- BCS. There were 865 genes/EST with 2-fold differential expression levels and 198 genes/EST with 3-fold differential expression levels. Most of these genes were involved in vital cell events including signal transduction, regulation of gene expression, cytoskeleton, apoptosis, stress response and inflammation, cell cycle and tumor development. Cells co-cultured with VacA~+ BCS showed collapsed and disrupted microtubular cytoarchitecture. CONCLUSION: VacA~+ BCS can disrupt cytoskeletal architecture, likely through affecting the expression of cytoskeleton-associated genes, directly induce the expression of tumor promoter-related genes and inhibit the expression of tumor suppressor genes, thus favoring the development of tumors. VacA~+ BCS can also alter the expression of inflammation and stress response genes. This suggests that VacA may play an important role in the pathogenicity of H pylori.     

幽门螺杆菌感染诱导胃粘膜环氧化酶-2表达

目的 探讨幽门螺杆菌（Hp)感染对胃粘膜环氧化酶－2（COX－2）表达的影响。方法 27例无任何症状健康检查者，经胃镜采取胃窦部粘膜组织，用于Hp检测、病理组织学检查及免疫组织化学检查COX－2的表达。结果 18例Hp感染者胃粘膜上皮细胞和炎症细胞表达COX－2，而9例Hp阴性者胃粘膜均不表达COX－2。结论 Hp感染诱导胃粘膜COX－2表达。     

p53 expression in gastric mucosa with Helicobacter pylori infection

Expression of p53 was examined immunohistochemically in the Japanese monkey model with Helicobacter pylori infection of the gastric mucosa to investigate the association between H. pylori infection and gastric carcinogenesis for a period of 4 years. In the course of these observations, from 3 years after H. pylori inoculation, nuclear staining for p53 was seen in the glandular cells of the mucosa infected with H. pylori, especially in the neck region of the glands. There was a gradual increase in the number of immunopositive cases among the infected animals. Three years after inoculation, three out of six cases, and 4 years after inoculation, four out of six cases exhibited positive staining for p53. Before inoculation, and up to 2 years after inoculation, the infected group showed no immunoreaction for p53. The non-infected group likewise displayed no immunostaining for p53 through 4 years of observation. These results suggest that p53 alterations occur in the H. pylori-infected gastric mucosa and that H. pylori infection may play an important role in gastric carcinogenesis.     

Helicobacter pylori infection accelerates human gastric mucosal cell proliferation

Helicobacter pylori causes chronic atrophic gastritis and intestinal type gastric cancer arises against a background of atrophic gastritis. Increased proliferation of epithelial cells is an important indicator of increased risk for gastric adenocarcinoma. We investigated gastric mucosal cell proliferation inH. pylori-associated gastritis and the effect of eradication therapy on this proliferation in 45 patients endoscopically diagnosed (31 with persistent eradication and 14 in whomH. pylori) recurred.H. pylori status was determined by culture and histology in biopsied specimens from the gastric antrum and corpus. Eradication of the infection was defined as reversal to negative on both tests. In vitro Ki-67 immunostaining of endoscopic biopsy specimens was used to measure mucosal cell proliferation inH. pylori-associated gastritis before and after therapy. The proliferative zone was defined as the distance of Ki-67-positive gastric epithelial cells between the highest and the lowest cells. In patients in whomH. pylori was eradicated, cell proliferation in both the antral and corpus mucosa had decreased 4 weeks after completion of the eradication therapy (P<0.01,P<0.001), and 6 months later, it had markedly decreased (P<0.05,P<0.05) and returned to normal. In patients in whomH. pylori recurred, only antral epithelial cell proliferation was reduced 4 weeks after eradication therapy, but whenH. pylori recurred, determined by culture and histology, cell proliferation level was the same as that before eradication. These results suggest thatH. pylori infection accelerates cell proliferation in gastric mucosa and may play a causal role in the chain of events leading to gastric carcinoma.     

幽门螺杆菌慢性感染诱导胃上皮细胞产生凋亡耐受

目的：建立幽门螺杆菌（H.pylori)慢性感染胃上皮细胞模型,并分析H.pylori慢性感染与胃上皮细胞凋亡的关系。方法：首先用H.pylori SS1与人非肿瘤性胃上皮细胞株GES－1共培养16周,建立GES－1模型细胞,然后采用流式细胞术分析这种模型细胞对H.pylori和其它肠道细菌以及抗肿瘤药物凋亡诱导剂的应答。结果：成功获得了H.pylori慢性感染胃上皮细胞模型（GES－1模型细胞）。这种模型细胞不仅对H.pylori诱导的凋亡耐受,而且对其他肠道细菌和一些凋亡诱导剂也是耐受的。结论：幽门螺杆菌慢性感染诱导胃上皮细胞产生凋亡耐受,由此可能增加了胃上皮细胞癌变的危险性。     

Apoptosis in gastric epithelium induced by Helicobacter pylori infection: implications in gastric carcinogenesis

OBJECTIVES: Helicobacter pylori is an identified carcinogen for gastric cancer, however, the underlying mechanisms remain to be defined. In this review, we sought to elucidate the role of apoptosis in gastric carcinogenesis, to determine the influence of H. pylori infection on apoptosis, and finally to provide insights into the mechanisms by which H. pylori may lead to gastric carcinogenesis. METHODS: A broad-based MEDLINE and Current Contents literature search was performed to identify relevant publications between 1966 and March 2000 addressing H. pylori infection, apoptosis, cell proliferation, gastric carcinoma, oncogenes, and tumor suppressor genes, as well as the products of these genes. Abstracts from recent major conferences that provided adequate additional data were also included. RESULTS: Apoptotic cells are rare in the glandular neck region (the generative cell zone) of normal gastric mucosa. With progression of atrophic gastritis, the generative cell zone shifts downward and a relatively large number of apoptotic cells occur. In intestinalized glands, both apoptotic cells and proliferative cells are present in deeper portions of the glands, corresponding to the generative zone. A higher frequency of apoptosis has been observed in gastric dysplasia than in coexisting gastric carcinomas, whereas the number of proliferative cells is significantly higher in gastric carcinoma than in dysplasia. Upregulation of oncogene bcl-2 in premalignant lesions and "downregulation" of the gene after malignant change is probably a common event. Accumulation of p53 protein is first detected in dysplasia, although mutation of the pS3 gene may occur in intestinal metaplasia. H. pylori infection induces apoptosis in gastric epithelial cells, which returns to normal after eradication of the infection. Numerous molecules produced by H. pylori including cytotoxin (VacA), lipopolysaccharide, monochloramine, and nitric oxide may directly induce apoptosis. Moreover, H. pylori-stimulated host inflammatory/immune responses lead to release of a large amount of cytokines. Cytokines produced by type 1 T helper cells, such as TNF-alpha and IFN-gamma, markedly potentiate apoptosis. Gastric cell proliferation is significantly higher in patients with H. pylori infection than in normal controls, and eradication of the infection leads to a reduction in cell proliferation. Apoptosis and cell proliferation are also increased in precancerous lesions such as gastric atrophy, intestinal metaplasia, and dysplasia in the presence of H. pylori infection. However, H. pylori-induced apoptosis may no longer be cell cycle-dependent in these lesions because of the occurrence of alterations and mutations of apoptosis-regulating genes, resulting in a loss of balance between apoptosis and cell proliferation. CONCLUSIONS: It is hypothesized that H. pylori-induced apoptosis may play a key role in gastric carcinogenesis by increasing cell proliferation and/or resulting in gastric atrophy.     

Helicobacter pylori infection influences tumor growth of human gastric carcinomas

BACKGROUND: Helicobacter pylori infection is considered a risk factor for gastric carcinoma. However, the effect of eradication therapy in gastric carcinoma patients is not well known. The aim of this study was to investigate the relationship between H. pylori infection and tumor growth of gastric carcinoma. METHODS: Fifty-one patients with gastric carcinoma participated in the study. Thirty-three were H. pylori-positive, 6 were H. pylori-negative, and 12 were diagnosed with gastric carcinoma after eradication of H. pylori. To investigate tumor growth of gastric carcinoma, cell proliferation and angiogenesis of the tumors were evaluated by immunohistochemical techniques using Ki-67 and CD34. RESULTS: The Ki-67 labeling index was 47.9 +/- 2.6 (mean +/- s) in the H. pylori-positive group, 38.1 +/- 3.6 in the H. pylori-eradicated group, and 22.2 +/- 5.5 in the H. pylori-negative group. It was significantly lower in the H. pylori-eradicated and H. pylori-negative groups than in the H. pylori-positive one, and a significant difference was also found between the H. pylori-positive and H. pylori-eradicated groups. The microvessel counts were 62.5 +/- 3.0, 50.2 +/- 4.0, and 66.0 +/- 9.8 in the positive, eradicated, and negative groups, respectively. A significant difference was found between the H. pylori-positive and H. pylori-eradicated groups. CONCLUSION: Our results suggest that H. pylori infection is associated with cell proliferation, and its eradication may influence tumor vascularity of gastric carcinoma. Therefore, H. pylori eradication therapy may contribute to the suppression of tumor growth.     

Glycosylation-related gene expression in HT29-MTX-E12 cells upon infection by Helicobacter pylori

AIM To identify glycosylation-related genes in the HT29 derivative cell line, HT29-MTX-E12, showing differential expression on infection with Helicobacter pylori(H. pylori).METHODS Polarised HT29-MTX-E12 cells were infected for 24 h with H. pylori strain 26695. After infection RNA was isolated from both infected and non-infected host cells. Sufficient infections were carried out to provide triplicate samples for microarray analysis and for q RTPCR analysis. RNA was isolated and hybridised to Affymetrix arrays. Analysis of microarray data identified genes significantly differentially expressed upon infection. Genes were grouped into gene ontology functional categories. Selected genes associated with host glycan structure(glycosyltransferases, hydrolases, lectins, mucins) were validated by real-time q RT-PCR analysis.RESULTS Infection of host cells was confirmed by the isolation of live bacteria after 24 h incubation and by PCR amplification of bacteria-specific genes from the host cell RNA. H. pylori do not survive incubation under the adopted culture conditions unless they associate with the adherent mucus layer of the host cell. Microarray analysis identified a total of 276 genes that were significantly differentially expressed(P 0.05) upon H. pylori infection and where the fold change in expression was greater than 2. Six of these genes are involved in glycosylation-related processes. Real-time q RT-PCR demonstrated significant downregulation(1.8-fold, P 0.05) of the mucin MUC20. REG4 was heavily expressed and significantly downregulated(3.1-fold, P 0.05) upon infection. Gene ontology analysis was consistent with previous studies on H. pylori infection.CONCLUSION Gene expression data suggest that infection with H. pylori causes a decrease in glycan synthesis, resulting in shorter and simpler glycan structures.     

Helicobacter pylori infection and gastric cancer

Gastric cancer remains a major health burden on many societies claiming hundreds of thousands of lives every year. The discovery of Helicobacter pylori has no doubt revolutionised our understanding of this malignancy, which is now regarded as a paradigm for infection-induced chronic inflammation-mediated cancer. In this paper, we discuss the evidence for the association between H. pylori and gastric adenocarcinoma and MALT lymphoma. We also discuss the pathogenesis of these two forms of cancer and the factors that determine their outcome. There is no doubt that the knowledge accumulated over the past two decades will be translated into eventual victory over this killer cancer, largely because we now appreciate that the best way to prevent the cancer is by preventing acquisition of the infection in the first place, or by eradicating the infection in infected subjects. Defining the optimal timing of intervention is going to be the challenge facing us over the next two decades.     

Helicobacter pylori infection and gastric cancer

According to several prospective controlled epidemiologic studies, the positive rate of H. pylori antibody was shown to be higher in the patients with gastric cancer than in the control group. Retrospective studies on the association between gastric cancer and H. pylori have been conducted in a large number of subjects and the results can be classified broadly into two categories, i.e., findings affirming an association and others denying it. Research concerning the association between gastric cancer and H. pylori has achieved great progress over time, leading to the recognition of this relationship by the WHO. One of the greatest concerns is to ascertain whether the final outcome of H. pylori-induced gastritis may lead to gastric cancer. The onset of gastric cancer can be explained as being caused not only by H. pylori infection, but also by a combination of various factors such as food and the environment. However, the possibility that the occurrence of gastric cancer, like the recurrence of peptic ulcer, can be prevented by eradication of H. pylori has also been suggested. Further progress in clinical research is needed to resolve this issue.     

Helicobacter pylori infection induces antibodies cross-reacting with human gastric mucosa

The authors' previous observation that many of the monoclonal antibodies against Helicobacter pylori cross-react with the cells of the human gastric mucosa prompted them to investigate the possibility that gastric self-antigens cross-reacting with H. pylori could be involved in the immune response against this organism. It was found that three antibodies against H. pylori, CB-4, CB-10, and CB-14, that cross-react with the human gastric mucosa also intensely cross-reacted with murine gastric epithelial cells. A strong reaction against autologous mucosa was also evident in the sera of mice immunized with H. pylori but not with other bacteria. A serological study performed in a group of 82 patients undergoing gastroscopy showed that the presence of seropositivity against H. pylori was strongly correlated with the presence of autoantibodies against human antral gastric mucosa. This activity was neutralized after absorption of the sera with H. pylori but not with other gram-negative bacteria. The antibodies in the mouse and in the human did not react with other segments of the gastrointestinal tract or with most of the other organs. Mice bearing hybridomas secreting a cross-reacting antibody (CB-4) had histopathologic abnormalities in their stomachs. These lesions were absent in the stomachs of mice bearing hybridomas secreting a non-cross-reacting antibody (CB-26). It was concluded that H. pylori infection can stimulate antibodies cross-reacting with gastric autoantigens and that this immunologic mechanism may represent a pathogenic link between H. pylori and gastritis.     

Helicobacter pylori infection potentiates aspirin induced gastric mucosal injury in Mongolian gerbils

BACKGROUND: Helicobacter pylori infection and non-steroidal anti-inflammatory drugs are two major causes of gastric ulceration but interactions between H pylori and these drugs in gastric mucosal injury are unclear. AIMS: We studied the influence of experimental H pylori infection on gastric mucosal injury induced by aspirin. SUBJECTS: Male Mongolian gerbils free of specific pathogens were used. METHODS: H pylori ATCC43504 culture broth was administered by oral gavage at seven weeks of age. After three weeks, acidified aspirin (400 mg/kg) was administered orally, and three hours later the total area of gastric erosions, myeloperoxidase (MPO) activity (an index of neutrophil accumulation), thiobarbituric acid reactive substances (TBARS, an index of lipid peroxidation), and KC/GRO (a chemoattractive cytokine in rodents) were measured in gastric mucosa. To determine the role of neutrophils in these circumstances, antigerbil neutrophil rabbit serum (ANS) was administered to some animals 18 hours before aspirin. RESULTS: Aspirin caused more extensive haemorrhagic erosions (33.1 (12.3) mm2) associated with greater MPO activity (1887.7 (598.5) microU/mg protein) and TBARS (0.33 (0.14) nmol/mg protein) and KC/GRO concentrations (28.3 (9.5) pg/mg protein) in infected than in uninfected gerbils (13.7 (2.3); 204.0 (68.9); 0.12 (0.06); 3.1 (0.8), respectively) Pretreatment with ANS inhibited the increases in gastric erosions, MPO activity, and TBARS but not KC/GRO concentration. The reduction in aspirin induced mucosal injury by administration of ANS was much greater in H pylori infected animals (65%) than in uninfected animals (31%). CONCLUSIONS: H pylori infection potentiates aspirin induced gastric mucosal injury by mechanisms that include accumulation of activated neutrophils.     

Roles of Helicobacter pylori infection and cyclooxygenase-2 expression in gastric carcinogenesis

AIM: Cyclooxygenase (COX)-2 is over expressed in gastrointestinal neoplasm. Helicobacter pylori (H pylori) infection is causally linked to gastric cancer. However, the expression of COX-2 in various stages of H pylori-associated gastric carcinogenesis pathway has not been elucidated. Therefore, the aim of this study was to clarify the role of H pylori induced COX-2 expression during carcinogenesis in the stomach. METHODS: Gastric biopsies from 138 subjects (30 cases of chronic superficial gastritis (CSG), 28 cases of gastric glandular atrophy (GA), 45 cases of gastric mucosal intestinal metaplasia (IM), 12 cases of moderate gastric epithelial dysplasia and 23 cases of gastric cancer) were enrolled. H pylori infection was assessed by a rapid urease test and histological examination (modified Giemsa staining). The expression of COX-1 and COX-2 in human gastric mucosa was detected by immunohistochemical staining. RESULTS: H pylori infection rate was 64.3% in GA and 69.5% in gastric cancer, which was significantly higher than that (36.7%) in CSG (P<0.05). The positive expression rates of COX-2 were 10.0%, 35.7%, 37.8%, 41.7% and 69.5% in CSG, GA, IM, dysplasia and gastric cancer, respectively. From CSG to GA, IM, dysplasia and finally to gastric cancer, expression of COX-2 showed an ascending tendency, whereas COX-1 expression did not change significantly in the gastric mucosa. The level of COX-2 expression in IM and dysplasia was significantly higher in H pylori-positive than in H pylori-negative subjects (P<0.01). CONCLUSION: COX-2 expression induced by H pylori infection is a relatively early event during carcinogenesis in the stomach.