HLA polymorphisms are associated with Helicobacter pylori infected gastric cancer in a high risk population, China

Helicobacter pylori is one of the most common bacterial infections associated with an increased risk of gastric cancer, but its association with host factors, particularly polymorphisms of the immune response genes, such as human leukocyte antigen (HLA) genes, is still unclear. To investigate the role of HLA polymorphisms in the risk of gastric cancer among subjects with H. pylori infection, a case-control study involving 52 gastric cancer patients and 139 non-cancer controls was conducted in Linqu County, China, an area with a high incidence of gastric cancer. Polymorphisms of HLA class I and class II alleles were determined by PCR with sequence-specific primers (PCR-SSP). The information about H. pylori infection was obtained from previous records. Among 48 class I and 19 class II HLA alleles detected in this study, two alleles, CW*03 and DRB1*01, were found to be distributed significantly differently between patients and controls [odds ratio(OR)=1.95, 95% confidence interval (CI)=1.13–3.35, P=0.017 and OR=4.39, 95% CI=1.39–13.84, P=0.012, respectively). The OR of gastric cancer risk in individuals carrying CW*03/CW*03 or CW*03/CW*N was 2.06, 95% CI=1.05–4.02, P=0.035, while the OR was 3.49, 95% CI=1.0–12.4, P=0.04 for DRB1*01/DRB1*01 or DRB1*01/DRB1*N carriers. The analysis of the interaction between H. pylori infection and HLA risk genotypes of CW*03 or DRB1*01 revealed that the effect of CW*03 and DRB1*01 genotypes on gastric cancer risk was manifested stronger in H. pylori-positive individuals (OR=5.30, 95% CI=1.73–16.29, P=0.004 and OR=13.38, 95% CI=2.52–70.98, P=0.002, respectively) than in H. pylori-negative ones (OR=1.25, 95% CI=0.25–6.12, P=0.785 and OR=2.26, 95% CI=0.18–28.88, P=0.531, respectively). The combined effect of the two risk HLA genotypes on gastric cancer risk was also analysed. The result showed that the individuals carrying both the CW*03 and DRB1*01 alleles could only be found in cancer patients (5/52), and not in controls (0/139), further suggesting that CW*03 and DRB1*01 are risk alleles advancing the progression of tumorigenesis. These observations demonstrate that host HLA genotypes may play an important role in the risk of gastric cancer, especially among persons with H. pylori infection.     

Helicobacter pylori infection influences expression of genes related to angiogenesis and invasion in human gastric carcinoma cells

Infection with Helicobacter pylori (H. pylori) is considered a risk factor for gastric carcinoma. The purpose of this study was to clarify whether H. pylori infection plays a role in progression of gastric carcinoma. We examined the expression of genes encoding angiogenic factors and proteases by human gastric carcinoma cell lines (MKN-1 and TMK-1) co-cultured with or without H. pylori by cDNA microarray analysis. Co-culture with H. pylori increased expression of mRNAs encoding interleukin (IL)-8, vascular endothelial growth factor (VEGF), angiogenin, urokinase-type plasminogen activator (uPA), and metalloproteinase (MMP)-9 by gastric carcinoma cells. Up-regulation of these genes at the mRNA and protein levels was confirmed by Northern blot analysis, semi-quantitative RT-PCR analysis, and ELISA. In vitro angiogenic and collagenase activities of conditioned medium from the gastric carcinoma cells were also stimulated by co-culture with H. pylori. These results indicate that H. pylori infection may regulate angiogenesis and invasion of human gastric carcinoma.     

A model for the study of Helicobacter pylori interaction with human gastric acid secretion

We present a comprehensive mathematical model describing Helicobacter pylori interaction with the human gastric acid secretion system. We use the model to explore host and bacterial conditions that allow persistent infection to develop and be maintained. Our results show that upon colonization, there is a transient period (day 1-20 post-infection) prior to the establishment of persistence. During this period, changes to host gastric physiology occur including elevations in positive effectors of acid secretion (such as gastrin and histamine). This is promoted by reduced somatostatin levels, an inhibitor of acid release. We suggest that these changes comprise compensatory mechanisms aimed at restoring acid to pre-infection levels. We also show that ammonia produced by bacteria sufficiently buffers acid promoting bacteria survival and growth.     

Accumulation of 8-nitroguanine in human gastric epithelium induced by Helicobacter pylori infection

Helicobacter pylori infection causes chronic inflammation, which can lead to gastric carcinoma. A double immunofluorescence labeling study demonstrated that the level of 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) apparent in gastric gland epithelium was significantly higher in gastritis patients with H. pylori infection than in those without infection. A significant accumulation of proliferating cell nuclear antigen, a prognostic factor for gastric cancer, was observed in gastric gland epithelial cells in patients with H. pylori infection as compared to those without infection, and its accumulation was closely correlated with the formation of 8-nitroguanine and 8-oxodG. These results suggest that nitrosative and oxidative DNA damage in gastric epithelial cells and their proliferation by H. pylori infection may lead to gastric carcinoma. 8-Nitroguanine could be not only a promising biomarker for inflammation but also a useful indicator of the risk of gastric cancer development in response to chronic H. pylori infection.     

Survival of Helicobacter pylori in well water

The mortality of a clinical Helicobacter pylori strain was assessed by inoculating it in untreated well water, filtered well water, and autoclaved well water. Two different temperatures (5 and 25 °C) were used during the experimental period. Because Escherichia coli is commonly used as indicator of faecal pollution of water, we compared the survival of H. pylori using E. coli as indicator of its persistence. H. pylori was not culturable 48 h after inoculation, whereas the population of E. coli, monitored at the same temperature, decreased slowly, especially in filtered water. In untreated water, both H. pylori and E. coli survived less well than in filtered and autoclaved water. In general the survival of H. pylori and E. coli was better in filtered water than in autoclaved water and the ability of H. pylori to survive several days in water at 5 °C is reported, supporting the observation that H. pylori survives better at 5 °C than at higher temperature. This suggests a possible faecal–oral transmission of H. pylori in the presence of a contaminated water.     

幽门螺杆菌相关miRNA与胃癌关系的研究进展

微小核糖核酸(microRNA,miRNA)是一种由内源基因编码长度约为22个核苷酸的非编码RNA,其能抑制靶基因蛋白质表达,有多种生物学功能。越来越多的研究表明,miRNA在多种肿瘤中异常表达,参与肿瘤发生、发展过程。幽门螺杆菌(Helicobacter pylori,Hp)作为胃癌的主要致病因素,可通过调节miRNA的表达,在胃癌中起促进或抑制作用。现就Hp相关miRNA在胃癌中的作用作一概述。     

Alkylhydroperoxide reductase of Helicobacter pylori as a biomarker for gastric patients with different pathological manifestations

The development of various gastrointestinal diseases was suggested to be associated with chronic inflammation as a consequence of Helicobacter pylori (H. pylori) infection. Our previous studies showed that an antioxidant protein alkylhydroperoxide reductase (AhpC) is an abundant and important antioxidant protein present in H. pylori. In this study we have explored the potential of utilizing antibodies to AhpC for detection of patients who are at high risks of evolving into severe outcomes of gastric malignancies after H. pylori infection. The correlation between AhpC and extents of inflammatory damage in tissues was demonstrated by immunoblotting assays and endoscopic examinations. Oxidative stress-induced high-molecular-weight (HMW) AhpC with chaperone activity in vivo was further investigated by co-immunoprecipitation, 2-dimensional gel electrophoresis (2-DE) followed by nano-liquid chromatography coupled tandem mass spectrometry (nanoLC-MS/MS). We found AhpC was consistently expressed in higher amounts in H. pylori strains isolated from patients with gastric cancer (GC) than gastritis (GA). Immunological analysis of seropositivity for AhpC indicated that positive diagnostic rates for H. pylori-infected patients with GA, gastric ulcer (GU) and GC were 68% (15/22), 100% (50/50) and 100% (50/50), respectively. In great contrast to low-molecular-weight (LMW) AhpC, HMW AhpC with chaperone function was found to distribute inside of H. pylori cells. We also found that LMW forms of AhpC were recognized by serum antibodies from GA patients whereas HMW forms of AhpC reacted mainly with those from GU and GC patients. Based on the significant difference between AhpC isolated from strains of GC and GA, it is conceivable that AhpC of H. pylori may prove to be useful as a prognostic or diagnostic protein marker to monitor varied clinical manifestations of gastrointestinal patients infected with H. pylori.     

胃黏膜菌群与幽门螺杆菌的相关性

除幽门螺杆菌之外,胃黏膜内还定居着大量细菌,占主导地位的是厚壁菌门、变形菌门、拟杆菌门、放线菌门和梭杆菌门。幽门螺杆菌和胃黏膜菌群之间可通过竞争营养和空间、扰乱抑菌肽的分泌以及改变宿主胃生理环境等直接或间接相互影响。本研究总结了胃内正常菌群的组成特征,分析了胃黏膜菌群与幽门螺杆菌之间的相互关系及其潜在机制,并进一步探讨了胃黏膜菌群对幽门螺杆菌相关胃部疾病的影响,有利于深入理解慢性胃病的发病机制,为疾病预防及治疗提供理论依据。     

Helicobacter pylori antibodies and gastric cancer: a gender-related difference

Helicobacter pylori has been proposed as a causative agent of gastric cancer. The aim of this study was to define serum antibodies response against different H. pylori antigens in patients with gastric cancer. Serum samples were collected from 115 Lithuanian patients with non-cardia gastric cancer and 110 age- and sex-matched controls without cancer. Heat-stable, low-molecular-mass, and outer membrane proteins were used as antigens to analyze serum IgG antibody response against H. pylori by enzyme-linked immunosorbent assay. Seroprevalence of H. pylori using low-molecular-mass antigen was significantly higher in gastric cancer patients, compared to controls (77% versus 57%, p<0.05). Significant differences in the prevalence of H. pylori infection between gastric cancer patients and controls were found in females using all three studied antigens: heat-stable (98% versus 84%, p<0.05), low-molecular-mass (88% versus 48%, p<0.05) and outer membrane proteins (78% versus 57%, p<0.05). In males, no significant differences were revealed between gastric cancer patients and controls. There may be other cofactors in addition to H. pylori that are important for the development of gastric cancer. H. pylori seems, however, to be a more important for development of gastric cancer in females than in males or males may have more confounding risk factors for gastric cancer than females.     

Genome-wide DNA methylation profiles in noncancerous gastric mucosae with regard to Helicobacter pylori infection and the presence of gastric cancer

Background and Aims: To determine genome‐wide DNA methylation profiles induced by Helicobacter pylori (H. pylori) infection and to identify methylation markers in H. pylori‐induced gastric carcinogenesis. Methods: Gastric mucosae obtained from controls (n = 20) and patients with gastric cancer (n = 28) were included. A wide panel of CpG sites in cancer‐related genes (1505 CpG sites in 807 genes) was analyzed using Illumina bead array technology. Validation of the results of Illumina bead array technique was performed using methylation‐specific PCR method for four genes (MOS, DCC, CRK, and PTPN6). Results: The Illumina bead array showed that a total of 359 CpG sites (269 genes) were identified as differentially methylated by H. pylori infection (p < .0001). The correlation between methylation‐specific PCR and bead array analysis was significant (p < .0001, Spearman coefficient = 0.5054). Methylation profiles in noncancerous gastric mucosae of the patients with gastric cancer showed quite distinct patterns according to the presence or absence of the current H. pylori infection; however, 10 CpG sites were identified to be hypermethylated and three hypomethylated in association with the presence of gastric cancer regardless of H. pylori infection (p < .01). Conclusions: Genome‐wide methylation profiles showed a number of genes differentially methylated by H. pylori infection. Methylation profiles in noncancerous gastric mucosae from the patients with gastric cancer can be affected by H. pylori‐induced gastritis. Differentially methylated CpG sites in this study needs to be validated in a larger population using quantitative methylation‐specific PCR method.     

Aldobiouronic acid domains in Helicobacter pylori

Helicobacter pylori cell-surface glycans exert strong influences in host–microbe interplays and define the strain’s immunological signature. Envisaging the development of a carbohydrate-based vaccine against the gastroduodenal pathogen H. pylori, several clinical isolates are being screened for their cell-surface glycan profile. The present work concerns H. pylori clinical specimen PTAV79 that abundantly expressed amylose-like glycans. These polysaccharides were isolated in glycan-rich fractions resultant from phenol–water extractions and purified by Bio-Gel P2. Structural studies showed that the glycans are linked to glycerol and present aldobiouronic acid domains composed of [→3)-α-d-GlcA-(1→4)-α-d-Glc-(1→] repeating units. The amylose domains were constituted by an average of 19 Glc residues and the acidic moieties had an average number of 10 aldobiouronic acid repeating units. These polysaccharides were isolated in fractions that, although hydrophilic, were rich in stearic acid, strongly suggesting that they are present as glycerolipids anchored to cell-surface.     

Helicobacter pylori infection can modulate the susceptibility of gastric mucosa cells to MNNG

The pathogenesis of stomach cells can be associated with their susceptibility to exogenous dietary irritants, like nitrosamines such as dimethylnitrosamines (DMNA), and to the effects of non-dietary factors, including Helicobacter pylori infection. We used N-methyl-N’-nitro N-nitrosoguanidyne (MNNG) as a surrogate agent that induces a spectrum of DNA damage similar to DMNA. Using the alkaline comet assay, we showed that antioxidants — vitamins C and E, quercetin, and melatonin — reduced the genotoxic effect of MNNG in H. pylori-infected and non-infected human gastric mucosa cells (GMCs). To compare the sensitivity of the stomach and the blood, the experiment was also carried out in peripheral blood. We observed a higher level of DNA damage induced by MNNG in H. pylori-infected than in noninfected GMCs. We did not note any difference in the efficacy of the repair of the damage in either type of GMC. H. pylori infection may play an important role in the pathogenesis of GMCs, as it can modulate their susceptibility to dietary mutagens/carcinogens, thus contributing to gastric cancer.     

Quantitation of Helicobacter pylori ureC gene and its comparison with different diagnostic techniques and gastric histopathology

Numerous diagnostic assays for Helicobacter pylori detection are available. However, these techniques have their own advantages as well as limitations. Here we tried to develop a real-time quantitative (Q) PCR assay to measure ureC copy number to detect H. pylori, based on the fact that there is only one copy of the ureC gene per bacterium. We enrolled 120 adult patients [non-ulcer dyspepsia (NUD) 60, peptic ulcer disease (PUD) 20, gastric cancer (GC) 40] undergoing upper gastrointestinal endoscopies. During each endoscopic examination, antral biopsies from normal region of the antrum were obtained and subjected to the following tests: RUT, culture, histopathology, H. pylori-specific ureC PCR and ureC Q-PCR. Calculation of H. pylori copy number was based on the standard curve generated using 10-fold dilutions of DNA extracted from the H. pylori control strain varying from 10⁵ to 10¹ copies. The prevalence of H. pylori infection in our study population was 54% with no significant difference among disease and control population. The sensitivity of Q-PCR was found to be 100% which was highest among all diagnostic tests. The established Q-PCR is around 10 times more sensitive than the conventional PCR method. The copy number of H. pylori DNA was significantly increased when overall gastritis, H. pylori density, chronic inflammation and intestinal metaplasia were present. In summary, we developed a rapid and sensitive Q-PCR method for detecting H. pylori. This technique offers a significant improvement over other available methods for detecting H. pylori in clinical and research samples.     

Prevalence of Helicobacter pylori genotypes (vacA, cagA, cagE and virB11) in gastric cancer in Brazilian's patients: an association with histopathological parameters

Purpose: To investigate the frequency and the association of vacA alleles, cagA, cagE and virB11 genes of Helicobacter pylori from patients with gastric cancer, considering the clinic histopathological parameters. Methods: One hundred and one gastric adenocarcinoma tissues were assessed by PCR to detect H. pylori and vacA alleles, cagA, cagE and virB11. Results: The distribution of cases according to the presence of the genes studied showed that the group containing vacA s1m1, cagA, cagE and virB11 H. pylori genes was significantly more frequent, followed by the group with at least one marker on the right side and left of the island. They were also present in the early stages and were the most frequent in nearly all histopathological grades. Conclusions: This study verified that vacAs1m1 and cag-PAI genes, cagA, cagE and virB11 are important H. pylori markers for gastric cancer development. Also, this study corroborates the importance of cagE and cagA together as cag-PAI marker.     

Analysis of outer membrane vesicle protein involved in biofilm formation of Helicobacter pylori

Helicobacter pylori is one of the most common causes of bacterial infection in humans. Infection with H. pylori is closely associated with gastritis and peptic ulcers and is a risk factor for gastric cancer and mucosa-associated lymphoid tissue lymphoma. H. pylori forms biofilms on glass surfaces at the air–liquid interface in in-vitro batch cultures. We previously reported that strain TK1402 showed a strong biofilm-forming ability in vitro. We also suggested the outer membrane vesicles (OMV) produced by strain TK1402 might be related to its biofilm forming ability. In the present study, we analyzed the protein profile of the OMV produced by strain TK1402 and found a unique 22-kDa protein in TK1402 OMV cultured for 2–3 days. In addition, this protein could not be detected in the OMVs produced by other H. pylori strains. These results suggest that the 22-kDa protein is involved in effective biofilm formation by strain TK1402.     

Comparative Genome Analysis of Helicobacter pylori Strains

DNA macroarrays were used to characterize 17 Helicobacter pylori strains isolated in four geographic regions of Russia (Moscow, St. Petersburg, Kazan, and Novosibirsk). Of all genes, 1272 (81%) proved to occur in all strains and to constitute a functional core of the genome, and 293 (18.7%) were strain-specific and greatly varied among the H. pylori strains. Most (71%) of the latter had unknown functions; the remainder included restriction–modification genes (3–9%), transposition genes (2–4%), and genes coding for outer membrane proteins (2–4%). The Russian H. pylori strains did not differ in genome organization or in the number and distribution of strain-specific genes from strains isolated in other countries.     

Antimicrobial effects of antioxidants with and without clarithromycin on Helicobacter pylori

Increasing resistance to currently used antimicrobials has resulted in the evaluation of other agents that have antimicrobial activity against Helicobacter pylori. H. pylori American Type Culture Collection (ATCC) strain 49503 (a toxin-producing strain known to be associated with gastric cancer) was grown, a cell suspension prepared in 2 mL PBS and diluted 10-fold. One hundred L of this cell suspension was added to vitamin C 0.5%, vitamin E 0.5%, garcinol 100 g/mL, Protykin® (containing 50% rans-resveratrol) 100 g/mL and garcinol + Protykin® 100 g/mL in Lennox broth, and incubated for 16 h under microaerophilic conditions. Three replicates of 10 L from each 10^–7 dilution tube were plated, colonies were counted after 16 h, and growth of H. pylori was confirmed by the CLO® test. These colony counts were compared to control cultures without the addition of any antioxidants. The experiments were then repeated with the addition of 15 g/mL of clarithromycin to experimental and control samples. Enhanced killing of H. pylori by 37.6% was noted when vitamin C was added, which increased to 66% when clarithromycin was added, compared to controls (p < 0.05). With garcinol and Protykin® alone there was 91.4 and 87% killing of H. pylori, respectively, while a combination of garcinol + Protykin® resulted in 90.8% killing compared to controls (p < 0.05). When clarithromycin was added, there was 76.3% increased killing with garcinol alone, 55.3% with Protykin® alone, and 73.7% with garcinol + Protykin® compared to controls (containing clarithromycin) (p < 0.05). Vitamin E had no effect on H. pylori growth compared to controls. We conclude from this study that some antioxidants such as vitamin C, garcinol and Protykin®, but not vitamin E, may have potential as antimicrobial agents against H. pylori. (Mol Cell Biochem 270: 125–130, 2005)     

Cloning of Helicobacter pylori urease subunit B gene and its expression in tobacco (Nicotiana tabacum L.)

Vaccines produced by transgenic plants would have the potential to change the traditional means of production and inoculation of vaccines, and to reduce the cost of vaccine production. In the present study, an UreB antigen gene from a new Helicobacter pylori strain ZJC02 was cloned into the binary vector pBI121 which contains a CaMV35S promoter and a kanamycin resistance gene, and then transformed UreB into tobacco leaf-disc by Agrobacterium-mediated method. A total of 50 regenerated plants with kanamycin resistance were obtained in the selection media. The 35 putative transgenic individuals were tested and verified the presence and integration of the UreB into the nuclear genome of tobacco plants by PCR, PCR-southern, and Southern analyses. Expression of UreB gene in the tobacco plants was confirmed by RT-PCR and Western Blot analysis using polyclonal human antiserum. To our knowledge, this is the first report of the expression of Helicobacter pylori UreB antigen gene in a plant system, suggesting a major step in the production of plant-based vaccines for Helicobacter pylori.