Cloning and expression of a high-molecular-mass major antigen of Helicobacter pylori: evidence of linkage to cytotoxin production

A new lexicon in the age of microbiome research

At a rapid pace, biologists are learning the many ways in which resident microbes influence, and sometimes even control, their hosts to shape both health and disease. Understanding the biochemistry behind these interactions promises to reveal completely novel and targeted ways of counteracting disease processes. However, in our protocols and publications, we continue to describe these new results using a language that originated in a completely different context. This language developed when microbial interactions with hosts were perceived to be primarily pathogenic, as threats that had to be vanquished. Biomedicine had one dominating thought: winning this war against microorganisms. Today, we know that beyond their defensive roles, host tissues, especially epithelia, are vital to ensuring association with the normal microbiota, the communities of microbes that persistently live with the host. Thus, we need to adopt a language that better encompasses the newly appreciated importance of host-microbiota associations. We also need a language that frames the onset and progression of pathogenic conditions within the context of the normal microbiota. Such a reimagined lexicon should make it clear, from the very nature of its words, that microorganisms are primarily vital to our health, and only more rarely the cause of disease. This article is part of the theme issue 'Sculpting the microbiome: how host factors determine and respond to microbial colonization'.

Helicobacter pylori CagA-mediated ether lipid biosynthesis promotes ferroptosis susceptibility in gastric cancer

Helicobacter pylori, particularly cytotoxin-associated gene A (CagA)-positive strains, plays a key role in the progression of gastric cancer (GC). Ferroptosis, associated with lethal lipid peroxidation, has emerged to play an important role in malignant and infectious diseases, but the role of CagA in ferroptosis in cancer cells has not been determined. Here, we report that CagA confers GC cells sensitivity to ferroptosis both in vitro and in vivo. Mechanistically, CagA promotes the synthesis of polyunsaturated ether phospholipids (PUFA-ePLs), which is mediated by increased expression of alkylglycerone phosphate synthase (AGPS) and 1-acylglycerol-3-phosphate O-acyltransferase 3 (AGPAT3), leading to susceptibility to ferroptosis. This susceptibility is mediated by activation of the MEK/ERK/SRF pathway. SRF is a crucial transcription factor that increases AGPS transcription by binding to the AGPS promoter region. Moreover, the results demonstrated that CagA-positive cells are more sensitive to apatinib than are CagA-negative cells, suggesting that detecting the H. pylori CagA status may aid patient stratification for treatment with apatinib.

The Helicobacter pylori cag pathogenicity island as a determinant of gastric cancer risk

Helicobacter pylori strains can be broadly classified into two groups based on whether they contain or lack a chromosomal region known as the cag pathogenicity island (cag PAI). Colonization of the human stomach with cag PAI-positive strains is associated with an increased risk of gastric cancer and peptic ulcer disease, compared to colonization with cag PAI-negative strains. The cag PAI encodes a secreted effector protein (CagA) and components of a type IV secretion system (Cag T4SS) that delivers CagA and non-protein substrates into host cells. Animal model experiments indicate that CagA and the Cag T4SS stimulate a gastric mucosal inflammatory response and contribute to the development of gastric cancer. In this review, we discuss recent studies defining structural and functional features of CagA and the Cag T4SS and mechanisms by which H. pylori strains containing the cag PAI promote the development of gastric cancer and peptic ulcer disease.

A comprehensive study of Helicobacter pylori infection: molecular analysis, antibacterial susceptibility, and histopathological examination

Helicobacter pylori is a pathogen associated with gastroduodenal diseases. This study aimed; (i) to investigate H. pylori presence by invasive tests in adult dyspeptic patients, (ii) to determine antibiotic susceptibility and genotypic characteristics of the H. pylori isolates, and (iii) to investigate the relationship between the H. pylori genotypes and the histopathological findings. In this cross-sectional study, gastric biopsy samples from 208 adult dyspeptic patients were used for culture, tissue Polymerase Chain Reaction (PCR), and histopathological analysis. Antibiotic susceptibility of the H. pylori isolates was analyzed by gradient method. Analysis of the virulence genes was performed by monoplex PCR. Genetic profiles (from A to H) were created based on the virulence genes presence. Enterobacterial Repetitive Intergenic Consensus-PCR (ERIC-PCR) was used for the genotyping of the H. pylori isolates. The mean age of the patients was 46 (± 15) years and 128 (61.5%) of them were female. H. pylori positivity was detected by culture, tissue PCR and histopathological examination in 59 (28.4%), 114 (54.8%) and 81 (38.9%) patients, respectively. The overall prevalence of H. pylori was found to be 63% (131/208). All H. pylori isolates were susceptible to tetracycline and amoxicillin. The resistance rates for metronidazole, clarithromycin, levofloxacin, and rifampicin were 67.2%, 27.9%, 34.4% and 13.11%, respectively. Multi drug resistance (MDR) was detected at the rate of 45.9% (28/61). While the most common virulence gene was cagA (93.44%), the least common was vacAm1 (23%). The predominant genetic profile was profile A (47.5%). ERIC-PCR results revealed a total of 26 different patterns. A high prevalence of H. pylori was detected in adult dyspeptic patients as in developing countries. It was observed significant genotypic heterogeneity and virulence gene diversity within the isolates. A considerable resistance rate detected against antibiotics such as clarithromycin, metronidazole, and levofloxacin, which are frequently used in the eradication of H. pylori, should be taken into consideration when creating regional empirical treatment regimens.

Current status of gastric and oral infection/diseases caused by Helicobacter pylori

Helicobacter pylori is found in the stomach, which is its optimal habitat, and is considered an important factor in various serious diseases, including stomach cancer. The World Health Organization has identified H. pylori as a causative agent of gastric cancer, as confirmed by animal experiments in rodents. The fact that H. pylori can live in the harsh environment of stomach acid was the greatest hindrance to the discovery of H. pylori. It was not so long ago, in 1983, that it was successfully isolated and cultured. Subsequently, H. pylori eradication therapy was established, and it became possible to control gastric cancer to some extent. However, the mechanism, route, and mode of H. pylori infection still remain unclear. Furthermore, currently, the prevention of first‐episode gastric cancer and control of recurrent gastric cancer are not perfect. One of the reasons for this may be that the status of H. pylori in the oral cavity, which is the entry point for the organism (the beginning of the digestive system: the first route of infection), is still unknown. Therefore, we reviewed the current status of H. pylori infection in the stomach and oral cavity, focusing on (1) the mechanism of infection, (2) pathogenic factors, (3) the actual status of eradication therapy, and (4) control strategies.

How Long Will It Take to Launch an Effective Helicobacter pylori Vaccine for Humans?

Helicobacter pylori infection often occurs in early childhood, and can last a lifetime if not treated with medication. H. pylori infection can also cause a variety of stomach diseases, which can only be treated with a combination of antibiotics. Combinations of antibiotics can cure H. pylori infection, but it is easy to relapse and develop drug resistance. Therefore, a vaccine is a promising strategy for prevention and therapy for the infection of H. pylori. After decades of research and development, there has been no appearance of any H. pylori vaccine reaching the market, unfortunately. This review summarizes the aspects of candidate antigens, immunoadjuvants, and delivery systems in the long journey of H. pylori vaccine research, and also introduces some clinical trials that have displayed encouraging or depressing results. Possible reasons for the inability of an H. pylori vaccine to be available over the counter are cautiously discussed and some propositions for the future of H. pylori vaccines are outlined.

Susceptibility patterns and virulence genotypes of Helicobacter pylori affecting eradication therapy outcomes among Egyptian patients with gastroduodenal diseases

BACKGROUND

Helicobacter pylori (H. pylori) is a significant human pathogen that is responsible for a variety of illnesses, including mucosa-associated lymphoid tissue lymphoma, gastric cancer, peptic ulcers, and gastritis.

AIM

To investigate the frequency of H. pylori infection and its resistance patterns among Egyptian patients and to determine the influence of H. pylori virulence genetic determinants on the eradication success of 14-d triple therapy regimen.

METHODS

H. pylori infections were investigated in 72 patients with gastroduodenal complications suggestive of H. pylori infection. The cagA and vacA genotypes of cultured strains were studied using polymerase chain reaction. The patients underwent 14 d of triple-therapy treatment. The treatment response was examined using histology and a rapid urease test 6 wk after therapy discontinuation.

RESULTS

The intention-to-treat eradication rate was 59.2% (95%CI: 48.2%-70.3%). Rates of H. pylori resistance to clarithromycin, amoxicillin, and metronidazole were 52.8%, 81.9%, and 100%, respectively. Successful eradication of H. pylori was more significantly associated with vacA s1-positive strains [adjusted odds ratio (aOR) = 0.507, 95%CI: 0.175-0.822]. A significant association was found between failed eradication rate and H. pylori strains resistant to clarithromycin (aOR = 0.204, 95%CI: -0.005 to 0.412) and amoxicillin (aOR = 0.223, 95%CI: 0.026-0.537).

CONCLUSION

This study's low H. pylori eradication rate following 14-d triple therapy is concerning and worrying. H. pylori pan-resistance to metronidazole followed by the high resistance to ciprofloxacin, amoxicillin, and clarithromycin in this research is challenging and of great concern.

Virulence determinants and genotypes of <i>Helicobacter pylori</i> clinical isolates

Background. H. pylori is the principal causative agent of gastroduodenal disorders in humans. The development and severity of lesions in infected individuals depend on the virulence of H. pylori strains. Aims: Detection of virulence determinants and comparative analysis of H. pylori genotypes in patients with chronic gastritis (CG) and duodenal ulcer (DU). Materials and methods. The 53 H. pylori strains were isolated in St. Petersburg from patients with CG (n = 34) and DU (n = 19). The genetic determinants of virulence cagA, iceA, vacA and H. pylori genotypes in patients with CG and UC were determined using the standard PCR method. Results. The cagA gene was found in 64.1% of H. pylori strains. The proportions of cagA+ isolates from patients with CG and DU was 55.8% (15/34) and 78.9% (15/19), respectively (p 0.05). The iceA1 allele of H. pylori was detected in 47.4% of patients with DU, the iceA2 in 47.1% of patients with CG (p 0.05). The vacAs1 allele was significantly dominant in patients with DU 94.7% versus 70.6% in CG (p 0.05). No significant difference in vacA m1 and m2 alleles was found in H. pylori from different groups of patients (p 0.05). All cagA+ strains were carriers of the vacA s1 allele. The vast majority of strains (10 out of 11) of the cagA/vacAs2 genotype were isolated from patients with CG. Conclusion. The significant association between vacAs1, vacAs2 allelic variants, as well as vacA s1/m2, vacA s2/m2 genotypes of the pathogen and severity of clinical manifestations of H. pylori infection has been established in our study. The vacAs1 and vacA s1/m2 genotypes of the pathogen are associated with duodenal ulcer.

Insights into the Orchestration of Gene Transcription Regulators in Helicobacter pylori

Bacterial pathogens employ a general strategy to overcome host defenses by coordinating the virulence gene expression using dedicated regulatory systems that could raise intricate networks. During the last twenty years, many studies of Helicobacter pylori, a human pathogen responsible for various stomach diseases, have mainly focused on elucidating the mechanisms and functions of virulence factors. In parallel, numerous studies have focused on the molecular mechanisms that regulate gene transcription to attempt to understand the physiological changes of the bacterium during infection and adaptation to the environmental conditions it encounters. The number of regulatory proteins deduced from the genome sequence analyses responsible for the correct orchestration of gene transcription appears limited to 14 regulators and three sigma factors. Furthermore, evidence is accumulating for new and complex circuits regulating gene transcription and H. pylori virulence. Here, we focus on the molecular mechanisms used by H. pylori to control gene transcription as a function of the principal environmental changes.

The Microbiome in Gastrointestinal Cancers

The human microbiome has been recognized as increasingly important to health and disease. This is especially prescient in the development of various cancers, their progression, and the microbiome's modulation of various anticancer therapeutics. Mechanisms behind these interactions have been increasingly well described through modulation of the host immune system as well as induction of genetic changes and local inactivation of cancer therapeutics. Here, we review these associations for a variety of gastrointestinal malignancies as well as contemporary strategies proposed to leverage these associations to improve cancer treatment outcomes.

The Association Between Oral Helicobacter pylori and Gastric Complications: A Comprehensive Review

Helicobacter pylori (H. pylori) is linked to chronic gastritis, duodenal or gastric ulcers, and gastric cancer (GC). Because the oral cavity is the first component of the gastrointestinal tract (GIT) and the entrance point for H. pylori, it has been proposed as a possible reservoir of H. pylori. As a result, a putative oral-oral transmission pathway of H. pylori poses the possibility of whether personal contact, such as kissing or sharing a meal, might trigger H. pylori transmission. As a result, several investigations have been done on this issue using various approaches for detecting H. pylori in oral and stomach samples. Furthermore, the relationship between H. pylori and gastrointestinal disorders has yet to be studied. The evidence for the association between H. pylori and gastric diseases and their complications is still a controversial subject due to the existing literature in this review. The goal of this comprehensive review was to collect all available published articles and critically evaluate existing investigations looking into the relationship between oral H. pylori contamination and the danger of gastric complications. Few studies indicated an association between H. pylori and gastric diseases. Furthermore, more longitudinal randomized clinical studies to further investigate the association between H. pylori and gastric diseases are warranted.

CagA+Helicobacter pylori, Not CagA–Helicobacter pylori, Infection Impairs Endothelial Function Through Exosomes-Mediated ROS Formation

Background

Helicobacter pylori (H. pylori) infection increases the risk for atherosclerosis, and ROS are critical to endothelial dysfunction and atherosclerosis. CagA is a major H. pylori virulence factor associated with atherosclerosis. The present study aimed to test the hypothesis that CagA+H. pylori effectively colonizes gastric mucosa, and CagA+H. pylori, but not CagA–H. pylori, infection impairs endothelial function through exosomes-mediated ROS formation.

Methods

C57BL/6 were used to determine the colonization ability of CagA+H. pylori and CagA–H. pylori. ROS production, endothelial function of thoracic aorta and atherosclerosis were measured in CagA+H. pylori and CagA–H. pylori infected mice. Exosomes from CagA+H. pylori and CagA–H. pylori or without H. pylori infected mouse serum or GES-1 were isolated and co-cultured with bEND.3 and HUVECs to determine how CagA+H. pylori infection impairs endothelial function. Further, GW4869 was used to determine if CagA+H. pylori infection could lead to endothelial dysfunction and atherosclerosis through an exosomes-mediated mechanism.

Results

CagA+H. pylori colonized gastric mucosa more effectively than CagA–H. pylori in mice. CagA+H. pylori, not CagA–H. pylori, infection significantly increased aortic ROS production, decreased ACh-induced aortic relaxation, and enhanced early atherosclerosis formation, which were prevented with N-acetylcysteine treatment. Treatment with CagA-containing exosomes significantly increased intracellular ROS production in endothelial cells and impaired their function. Inhibition of exosomes secretion with GW4869 effectively prevented excessive aortic ROS production, endothelial dysfunction, and atherosclerosis in mice with CagA+H. pylori infection.

Conclusion

These data suggest that CagA+H. pylori effectively colonizes gastric mucosa, impairs endothelial function, and enhances atherosclerosis via exosomes-mediated ROS formation in mice.

<i>Helicobacter pylori</i>-associated comorbidity

Helicobacter pylori (H. pylori) infection is known to lead to various diseases such as gastric and duodenal ulcers, chronic gastritis and malignant diseases, including MALT lymphoma and stomach cancer. To date, various factors of pathogenicity and virulence of the H. pylori bacterium have been studied. The interaction of infection with host cells leads to the induction of inflammatory responses through the release of cytokines, activation of apoptosis or proliferation, which leads to inflammation and dysfunction of the epithelial barrier. This process can facilitate the movement of H. pylori virulence factors and inflammatory mediators into the bloodstream and promote or enhance the development of a systemic inflammatory response and the possible clinical effects of H. pylori infections outside the stomach. The purpose of this review is to clarify the available data on H. pylori-associated comorbidity with diseases of the cardiovascular, nervous, endocrine systems, autoimmune diseases and some other pathologies outside the digestive system.

Helicobacter pylori infection causes both protective and deleterious effects in human health and disease

Infection with Helicobacter pylori (H. pylori) is necessary but not sufficient for the development of gastric cancer, the third leading cause of cancer death globally. H. pylori infection affects over half of people globally; however, it does not affect populations uniformly. H. pylori infection rates are declining in western industrialized countries but are plateauing in developing and newly industrialized countries where gastric cancer is most prevalent. Despite H. pylori infection being the primary causative agent for gastric cancer, H. pylori infection can also cause other effects, detrimental or beneficial, throughout an individual's life, with the beneficial effects often being seen in childhood and the deleterious effects in adulthood. H. pylori is an ancient bacterium and its likelihood of affecting disease or health is dependent on both human and bacterial genetics that have co-evolved over millennia. In this review, we focus on the impact of infection and its genetic bases in different populations and diseases throughout an individual's lifespan, highlighting the benefits of individualized treatment and argue that universal eradication of H. pylori in its host may cause more harm than good for those infected with H. pylori.

EPIYA motifs of Helicobacter pylori cagA genotypes and gastrointestinal diseases in the Iranian population: a systematic review and meta-analysis

Helicobacter pylori is one of the best risk factors for gastric cancer. Recent studies have examined the relationship between virulence factors, in particular CagA toxin, and the development of gastrointestinal diseases. According to the literature, there is a significant relationship between the polymorphism of cagA-EPIYA motifs and progression to severe clinical outcomes. The main goal of our study was to determine the possible association between cagA genotypes and the risk of severe clinical outcomes in the Iranian population. We investigated these ambiguities using a comprehensive meta-analysis study, in which we evaluated data from 1762 Iranian patients for a potential correlation between all cagA gene genotypes and gastrointestinal diseases. According to statistical analysis, the frequencies of cagA genotypes including ABC, ABCC, AB and ABCCC in the Iranian population were estimated at 80.18%, 22.81%, 5.52% and 2.76%, respectively; the ABD genotype was not detected in these PCR-based studies. There was a significant relationship between cagA genotypes ABCC and ABCCC and severe clinical outcomes of infection such as peptic ulcer and gastric cancer. Overall, it can be concluded that there is a positive correlation with the number of copies of EPIYA-C and the increase of gastric cancer. Therefore, according to our results, it seems that the EPIYA-ABCCC motif has a strong positive relationship with gastric cancer in the Iranian population.

Metformin attenuates synergic effect of diabetes mellitus and Helicobacter pylori infection on gastric cancer cells proliferation by suppressing PTEN expression

It has been reported that CagA of Helicobacter pylori reduced PTEN expression by enhancing its promoter methylation. Furthermore, diabetes mellitus (DM) may also promote the methylation status of PTEN, a tumour suppressor gene in gastric cancer (GC). It is intriguing to explore whether DM may strengthen the tumorigenic effect of H pylori (HP) by promoting the methylation of PTEN promoter and whether the administration of metformin may reduce the risk of GC by suppressing the methylation of PTEN promoter. In this study, we enrolled 107 GC patients and grouped them as HP(-)DM(-) group, HP(+)DM(-) group and HP(+)DM(+) group. Bisulphite sequencing PCR evaluated methylation of PTEN promoter. Quantitative real-time PCR, immunohistochemistry and Western blot, immunofluorescence, flow cytometry and MTT assay were performed accordingly. DNA methylation of PTEN promoter was synergistically enhanced in HP(+)DM(+) patients, and the expression of PTEN was suppressed in HP(+)DM(+) patients. Cell apoptosis was decreased in HP(+)DM(+) group. Metformin showed an apparent effect on restoring CagA-induced elevation of PTEN promoter methylation, thus attenuating the PTEN expression. The reduced PTEN level led to increased proliferation and inhibited apoptosis of HGC-27 cells. In this study, we collected GC tumour tissues from GC patients with or without DM/HP to compare their PTEN methylation and expression while testing the effect of metformin on the methylation of PTEN promoter. In summary, our study suggested that DM could strengthen the tumorigenic effect of HP by promoting the PTEN promoter methylation, while metformin reduces GC risk by suppressing PTEN promoter methylation.

Helicobacter pylori CagA Interacts with SHP-1 to Suppress the Immune Response by Targeting TRAF6 for K63-Linked Ubiquitination

Helicobacter pylori is the major etiological agent for most gastric cancer. CagA has been reported to be an important virulence factor of H. pylori, but its effect on the immune response is not yet clear. In this study, wild-type C57BL/6 mice and Ptpn6^me-v/me-v mice were randomly assigned for infection with H. pylori We demonstrated that CagA suppressed H. pylori-stimulated expression of proinflammatory cytokines in vivo. Besides, we infected mouse peritoneal macrophages RAW264.7 and AGS with H. pylori Our results showed that CagA suppressed expression of proinflammatory cytokines through inhibiting the MAPKs and NF-κB pathways activation in vitro. Mechanistically, we found that CagA interacted with the host cellular tyrosine phosphatase SHP-1, which facilitated the recruitment of SHP-1 to TRAF6 and inhibited the K63-linked ubiquitination of TRAF6, which obstructed the transmission of signal downstream. Taken together, these findings reveal a previously unknown mechanism by which CagA negatively regulates the posttranslational modification of TRAF6 in innate antibacterial immune response and provide molecular basis for new therapeutics to treat microbial infection.

Determination of CagA EPIYA motif in Helicobacter pylori strains isolated from patients with digestive disorder

This study was conducted to identify patterns of cagA EPIYA motifs in H. pylori strains isolated from patients with gastrointestinal diseases in Hospitals of Shahrekord, and investigate the association between these biomarkers and clinical outcomes of gastrointestinal diseases due to H. pylori. In this study, 253 patients with gastrointestinal diseases were studied within 1395-1396. Histopathological investigations and urease test showed that 207 isolates were H. pylori-positive. Then, screening using a molecular technique, PCR, confirmed that 159 isolates had cagA. Finally, the pattern and prevalence of the motifs were determined by PCR and identified a number of motifs were sequenced. Results of this study showed that the pattern of motifs was as follows: ABC (140 isolates) (93/7%), ABCC (6 isolates) (3/77%), ABCCC (4 isolates) (2/5%), AB (7 isolates) (4/4%), AC (1 isolate) (0/6%), and BC (1 isolate) (0/6%). Sequencing results showed the presence of changed EPIYA motif in some isolates. CM motif sequence was also seen in all isolates. In this study, no significant association was seen between the prevalence rate of different patterns and clinical symptoms (p = 0.71). There is a slight association between the presence of ABC motifs and the type of digestive disorder (p = 0.056). Results indicated that ABC was the most frequently seen pattern however, in such that positive cases of ABC motifs were more common in gastritis. All isolates had kinase phosphorylation region, and the observed pattern in this region was a generally western type (ABC).

The Helicobacter pylori Cag Type IV Secretion System

Colonization of the human stomach with Helicobacter pylori strains containing the cag pathogenicity island is a risk factor for development of gastric cancer. The cag pathogenicity island contains genes encoding a secreted effector protein (CagA) and components of a type IV secretion system (Cag T4SS). The molecular architecture of the H. pylori Cag T4SS is substantially more complex than that of prototype T4SSs in other bacterial species. In this review, we discuss recent discoveries pertaining to the structure and function of the Cag T4SS and its role in gastric cancer pathogenesis.

Epitope peptides of Helicobacter pylori CagA antibodies from sera by whole-peptide mapping

BACKGROUND

Helicobacter pylori CagA has been found to be immuno-dominant protein and utilized for the diagnosis of the infection with cagA-positive strains. It is important to characterize the peptide epitopes capable of detecting serum anti-CagA antibodies to understand CagA immunogenicity.

METHODS

Sera from 171 Japanese patients were subjected for the epitope mapping study. Eighty seven peptides were designed from the CagA consensus sequence and were used for ELISA protocol to test the serum samples. The reacting anti-CagA IgG amounts to specific peptides were measured and compared.

RESULTS

The study revealed a strong reactivity of two peptides (c7-NNTEPIYAQVNKKKAGQAT and c8-AGQATSPEEPIYAQVAKKV) in H. pylori-infected group. Interestingly, these two peptides contained the well-known EPIYA-A and EPIYA-B region, respectively, which are two out of three CagA phosphorylation domains. Tyrosine-phosphorylation of these peptides reduced their reactivity in most sera. Moreover, additional peptides' mapping and chimeric-peptides' experiments indicated that the amino acids (QV and KK) accommodated in right-side flanking regions of both EPIYA-motifs were essential for their strong reactivity, whereas the third EPIYA-motif containing peptide (c12-GRSASPEPIYATIDFDEA) with differing flanking amino acids was not reactive in most cases.

CONCLUSIONS

Our results suggest that the amino acid sequences constituted in the two reactive peptides are the important immunogenic regions of CagA which would be useful to develop next-generation peptide-based diagnostic assays.

Hepatocyte Growth Factor in Blood and Gastric Cancer Risk: A Nested Case-Control Study

BACKGROUND

Potential of hepatocyte growth factor (HGF)-stimulating signaling pathways related to cytotoxin-associated gene A (CagA) to predict gastric cancer development has not been fully investigated.

METHODS

We conducted a nested case-control study consisting of 238 gastric cancer cases and 238 matched controls within the Korean Multicenter Cancer Cohort. Plasma HGF concentrations were measured with a human HGF ELISA. Odds ratios (OR) and 95% confidence intervals (CI) for gastric cancer development according to HGF level were calculated using conditional logistic regression model.

RESULTS

Sequential elevation of gastric cancer risk according to HGF level increase was observed (OR, 10.99; 95% CI, 4.91-24.62) for highest quartile HGF (≥364 pg/mL) versus lowest quartile HGF (<167 pg/mL). A significantly increased gastric cancer risk associated with high HGF level measured even 6 or more years prior to cancer diagnosis was also found. The group with both high risk of HGF and CagA-related genetic variants was associated with highest gastric cancer risk compared with the group with both low risk of HGF and genetic variants (P _interaction = 0.05). Model performance using HGF and CagA-related genetic variants to discriminate gastric cancer was fair [area under the curve of receiver operating characteristic (AUC-ROC), 0.71; 95% CI, 0.64-0.78] and significantly higher than that of model not including those biomarkers.

CONCLUSIONS

Our results suggest HGF as a potential biomarker to predict gastric cancer development.

IMPACT

These findings suggest HGF as a useful biomarker to predict gastric cancer risk. Further research to assess gastric cancer risk based on useful biomarkers, including HGF, may contribute to primary prevention of gastric cancer.

Activity and Functional Importance of Helicobacter pylori Virulence Factors

Helicobacter pylori is a very successful Gram-negative pathogen colonizing the stomach of humans worldwide. Infections with this bacterium can generate pathologies ranging from chronic gastritis and peptic ulceration to gastric cancer. The best characterized H. pylori virulence factors that cause direct cell damage include an effector protein encoded by the cytotoxin-associated gene A (CagA), a type IV secretion system (T4SS) encoded in the cag-pathogenicity island (cag PAI), vacuolating cytotoxin A (VacA), γ-glutamyl transpeptidase (GGT), high temperature requirement A (HtrA, a serine protease) and cholesterol glycosyl-transferase (CGT). Since these H. pylori factors are either surface-exposed, secreted or translocated, they can directly interact with host cell molecules and are able to hijack cellular functions. Studies on these bacterial factors have progressed substantially in recent years. Here, we review the current status in the characterization of signaling cascades by these factors in vivo and in vitro, which comprise the disruption of cell-to-cell junctions, induction of membrane rearrangements, cytoskeletal dynamics, proliferative, pro-inflammatory, as well as, pro-apoptotic and anti-apoptotic responses or immune evasion. The impact of these signal transduction modules in the pathogenesis of H. pylori infections is discussed.

Characterization of a novel Helicobacter pylori East Asian-type CagA ELISA for detecting patients infected with various cagA genotypes

Currently, Western-type CagA is used in most commercial Helicobacter pylori CagA ELISA kits for CagA detection rather than East Asian-type CagA. We evaluated the ability of the East Asian-type CagA ELISA developed by our group to detect anti-CagA antibody in patients infected with different cagA genotypes of H. pylori from four different countries in South Asia and Southeast Asia. The recombinant CagA protein was expressed and later purified using GST-tag affinity chromatography. The East Asian-type CagA-immobilized ELISA was used to measure the levels of anti-CagA antibody in 750 serum samples from Bhutan, Indonesia, Myanmar, and Bangladesh. The cutoff value of the serum antibody in each country was determined via Receiver-Operating Characteristic (ROC) analysis. The cutoff values were different among the four countries studied (Bhutan, 18.16 U/mL; Indonesia, 6.01 U/mL; Myanmar, 10.57 U/mL; and Bangladesh, 6.19 U/mL). Our ELISA had better sensitivity, specificity, and accuracy of anti-CagA antibody detection in subjects predominantly infected with East Asian-type CagA H. pylori (Bhutan and Indonesia) than in those infected with Western-type CagA H. pylori predominant (Myanmar and Bangladesh). We found positive correlations between the anti-CagA antibody and antral monocyte infiltration in subjects from all four countries. There was no significant association between bacterial density and the anti-CagA antibody in the antrum or the corpus. The East Asian-type CagA ELISA had improved detection of the anti-CagA antibody in subjects infected with East Asian-type CagA H. pylori. The East Asian-type CagA ELISA should, therefore, be used in populations predominantly infected with East Asian-type CagA.

Helicobacter pylori vacA, cagA and iceA genotypes in dyspeptic patients from southwestern region, Saudi Arabia: distribution and association with clinical outcomes and histopathological changes

Background

The aim of this study was to identify the common H. pylori virulence genes among dyspeptic Southwestern Saudi patients and their association with clinical outcomes and histopathological findings to help practitioners and researchers in the region for better management of infections caused by such bacteria.

Methods

Four hundred two gastric biopsy specimens were analyzed using histopathological examination and real time-PCR. The positive 187 specimens by RT-PCR were genotyped using PCR targeting cagA, vacA and iceA genes.

Results

One hundred twenty-eight gastric biopsy specimens were positive in genotyping PCRs. The cagA, vacA, iceA1 and iceA2 genes were detected in rates of 49.2% (63/128), 100%(128/128), 42.2% (54/128), 32.8% (42/128), respectively. The vacA s1as1bm2 subtype was the highest 23.4% (30/128), followed by m2 and s1a1b subtypes which were equally detected [16.4% (21/128) for each]. The iceA genes were significantly associated with gastritis and gastric ulcer. Overall, vacA genotypes were significantly associated with gastritis, gastric and duodenal ulcers. The vacA subtypes: s1as1bm2, s1a1b and s2 m2 showed chronic active gastritis in percentages of 90.0, 81, and 84.2%, respectively. All vacA mixed genotypes showed chronic active gastritis.

Conclusions

H. pylori virulence genes are highly prevalent and diverse among patients with dyspepsia in Southwestern region of Saudi Arabia. The iceA genes and the different vacA subtypes are significantly associated with the clinical outcomes and histopathological changes especially chronic active gastritis.

Role of NOD1 and ALPK1/TIFA Signalling in Innate Immunity Against Helicobacter pylori Infection

The human pathogen Helicobacter pylori interacts intimately with gastric epithelial cells to induce inflammatory responses that are a hallmark of the infection. This inflammation is a critical precursor to the development of peptic ulcer disease and gastric cancer. A major driver of this inflammation is a type IV secretion system (T4SS) encoded by the cag pathogenicity island (cagPAI), present in a subpopulation of more virulent H. pylori strains. The cagPAI T4SS specifically activates signalling pathways in gastric epithelial cells that converge on the transcription factor, nuclear factor-κB (NF-κB), which in turn upregulates key immune and inflammatory genes, resulting in various host responses. It is now clear that H. pylori possesses several mechanisms to activate NF-κB in gastric epithelial cells and, moreover, that multiple signalling pathways are involved in these responses. Two of the dominant signalling pathways implicated in NF-κB-dependent responses in epithelial cells are nucleotide-binding oligomerisation domain 1 (NOD1) and a newly described pathway involving alpha-kinase 1 (ALPK1) and tumour necrosis factor (TNF) receptor-associated factor (TRAF)-interacting protein with forkhead-associated domain (TIFA). Although the relative roles of these two pathways in regulating NF-κB-dependent responses still need to be clearly defined, it is likely that they work cooperatively and non-redundantly. This chapter will give an overview of the various mechanisms and pathways involved in H. pylori induction of NF-κB-dependent responses in gastric epithelial cells, including a 'state-of-the-art' review on the respective roles of NOD1 and ALPK1/TIFA pathways in these responses.

Tipping the Scale Toward Gastric Disease: A Host-Pathogen Genomic Mismatch?

PURPOSE OF REVIEW

Chronic infection with Helicobacter pylori infection is necessary but not sufficient to initiate development of intestinal-type gastric adenocarcinoma. It is not clear what additional factors tip the scale from commensal bacteria towards a pathogen that facilitates development of gastric cancer. Genetic variants in both the pathogen and host have been implicated, but neither alone explains a substantial portion of disease risk.

RECENT FINDINGS

In this review, we consider studies that address the important role of human and bacterial genetics, ancestry and their interactions in determining gastric disease risk. We observe gaps in the current literature that should guide future work to confirm the hypothesis of the interacting roles of host and bacterial genetics that will be necessary to translate these findings into clinically relevant information.

SUMMARY

We summarize genetic risk factors for gastric disease in both H. pylori and human hosts. However, genetic variation of one or the other organism in isolation insufficiently explains gastric disease risk. The most promising models of gastric disease risk simultaneously consider the genetic variation of both the H. pylori and human host, under a co-evolution model.

Association of oral Helicobacter pylori with gastric complications

AIM

This study was aimed to identify the presence of Helicobacter pylori (H. pylori) genes in oral mucosa and find out their relationship between oral H. pylori infection and gastric complications.

METHODS

This study is a case control study consists of 567 subjects with periodontal infection (278 gastric complication cases and 289 controls normal gastric intestinal mucosa) with age range of 20-80 years. Oral health status was recorded by calculating oral hygiene index (OHI), probing depths (PD) and clinical attachment loss (CAL). Each participant provided gastric biopsy and plaque samples which were subjected to H. pylori detection. Polymerase chain reaction (PCR) with different primers specifically β globulin, 16SrRNA, babA, cagA, ureA, ureC and vacA gene was performed which were then analyzed using gel electrophoresis.

RESULTS

No significant differences (χ² = 11.873, p value > 0.05) were observed between oral H. pylori and gastric infections/complications. However, H. pylori increase the risk of developing gastro-esophageal reflux grade II (OR = 1.458, 95%CI = 0.659-3.226), normal upper GIT mucosa with lax esophageal sphincters (OR = 1.215, 95%CI = 0.285-5.181) and duodenal ulcer/duodenitis (OR = 2.187, 95%CI = 0.225-21.278). This study also showed a significant increased risk of gastritis with babA gene.

CONCLUSION

Oral pathogenic H. pylori genes may enhance the severity of the gastric infection.

When is Helicobacter pylori acquired in populations in developing countries? A birth-cohort study in Bangladeshi children

Helicobacter pylori colonization is prevalent throughout the world, and is predominantly acquired during childhood. In developing countries, >70% of adult populations are colonized with H. pylori and >50% of children become colonized before the age of 10 years. However, the exact timing of acquisition is unknown. We assessed detection of H. pylori acquisition among a birth cohort of 105 children in Mirzapur, Bangladesh. Blood samples collected at time 0 (cord blood), and at 6, 12, 18, and 24 months of life were examined for the presence of IgG and IgA antibodies to whole cell H. pylori antigen and for IgG antibodies to the CagA antigen using specific ELISAs and immunoblotting. Breast milk samples were analyzed for H. pylori-specific IgA antibodies. Cord blood was used to establish maternal colonization status. H. pylori seroprevalence in the mothers was 92.8%. At the end of the two-year follow-up period, 50 (47.6%) of the 105 children were positive for H. pylori in more than one assay. Among the colonized children, CagA prevalence was 78.0%. A total of 58 children seroconverted: 50 children showed persistent colonization and 8 (7.6%) children showed transient seroconversion, but immunoblot analysis suggested that the transient seroconversion observed by ELISA may represent falsely positive results. Acquisition of H. pylori was not influenced by the mother H. pylori status in serum or breastmilk. In this population with high H. pylori prevalence, we confirmed that H. pylori in developing countries is detectable mainly after the first year of life.

Inhibition of TNFα-interacting protein α (Tipα)-associated gastric carcinogenesis by BTG2/TIS21 via downregulating cytoplasmic nucleolin expression

To understand the regulation of Helicobacter pylori (H. pylori)-associated gastric carcinogenesis, we examined the effect of B-cell translocation gene 2 (BTG2) expression on the biological activity of Tipα, an oncoprotein secreted from H. pylori. BTG2, the human ortholog of mouse TIS21 (BTG2/TIS21), has been reported to be a primary response gene that is transiently expressed in response to various stimulations. Here, we report that BTG2 is constitutively expressed in the mucous epithelium and parietal cells of the gastric gland in the stomach. Expression was increased in the mucous epithelium following H. pylori infection in contrast to its loss in human gastric adenocarcinoma. Indeed, adenoviral transduction of BTG2/TIS21 significantly inhibited Tipα activity in MKN-1 and MGT-40, human and mouse gastric cancer cells, respectively, thereby downregulating tumor necrosis factor-α (TNFα) expression and Erk1/2 phosphorylation by reducing expression of nucleolin, a Tipα receptor. Chromatin immunoprecipitation proved that BTG2/TIS21 inhibited Sp1 expression and its binding to the promoter of the nucleolin gene. In addition, BTG2/TIS21 expression significantly reduced membrane-localized nucleolin expression in cancer cells, and the loss of BTG2/TIS21 expression induced cytoplasmic nucleolin availability in gastric cancer tissues, as evidenced by immunoblotting and immunohistochemistry. Higher expression of BTG2 and lower expression of nucleolin were accompanied with better overall survival of poorly differentiated gastric cancer patients. This is the first report showing that BTG2/TIS21 inhibits nucleolin expression via Sp1 binding, which might be associated with the inhibition of H. pylori-induced carcinogenesis. We suggest that BTG2/TIS21 is a potential inhibitor of nucleolin in the cytoplasm, leading to inhibition of carcinogenesis after H. pylori infection.

Genetic populations and virulence factors of Helicobacter pylori

Helicobacter pylori is a bacterium that has infected more than half of the human population worldwide. This bacterium is closely associated with serious human diseases, such as gastric cancer, and identifying and understanding factors that predict bacterial virulence is a priority. In addition, this pathogen shows high genetic diversity and co-evolution with human hosts. H. pylori population genetics, therefore, has emerged as a tool to track human demographic history. As the number of genome sequences available is increasing, studies on the evolution and virulence of H. pylori are gaining momentum. This review article summarizes the most recent findings on H. pylori virulence factors and population genetics.

Helicobacter pylori infection perturbs iron homeostasis in gastric epithelial cells

The iron deficiency anaemia that often accompanies infection with Helicobacter pylori may reflect increased uptake of iron into gastric epithelial cells. Here we show an infection-associated increase in total intracellular iron levels was associated with the redistribution of the transferrin receptor from the cell cytosol to the cell surface, and with increased levels of ferritin, an intracellular iron storage protein that corresponded with a significant increase in lysosomal stores of labile iron. In contrast, the pool of cytosolic labile iron was significantly decreased in infected cells. These changes in intracellular iron distribution were associated with the uptake and trafficking of H. pylori through the cells, and enhanced in strains capable of expressing the cagA virulence gene. We speculate that degradation of lysosomal ferritin may facilitate H. pylori pathogenesis, in addition to contributing to bacterial persistence in the human stomach.

The Middle Fragment of Helicobacter pylori CagA Induces Actin Rearrangement and Triggers Its Own Uptake into Gastric Epithelial Cells

Cytotoxin-associated gene product A (CagA) is a major virulence factor secreted by Helicobacter pylori. CagA activity in the gastric epithelium is associated with higher risk of gastric cancer development. Bacterial type IV secretion system (T4SS)-mediated translocation of CagA into the cytosol of human epithelial cells occurs via a poorly understood mechanism that requires CagA interaction with the host membrane lipid phosphatidylserine (PS) and host cell receptor integrin α₅β₁. Here we have characterized the isolated recombinant middle fragment of CagA (CagA-M) that contains the positively-charged PS-binding region (aa 613–636) and a putative β₁ integrin binding site, but lacks the EPIYA region, secretion signal peptide and the CagA multimerization motif. We show that CagA-M, when immobilized on latex beads, is capable of binding to, and triggering its own uptake into, gastric epithelial cells in the absence of infection with cagA-positive H. pylori. Using site-directed mutagenesis, fluorescent and electron microscopy, and highly-specific inhibitors, we demonstrate that the cell-binding and endocytosis-like internalization of CagA-M are dependent on (1) binding to PS; (2) β₁ integrin activity; and (3) actin dynamics. Interaction of CagA-M with the host cells is accompanied by the development of long filopodia-like protrusions (macrospikes). This novel morphology is different from the hummingbird phenotype induced by the translocation of full-length CagA. The determinants within CagA-M and within the host that are important for endocytosis-like internalization into host cells are very similar to those observed for T4SS-mediated internalization of full-length CagA, suggesting that the latter may involve an endocytic pathway.

Variations in the multimerization region of the Helicobacter pylori cytotoxin CagA affect virulence

Helicobacter pylori colonizes the human stomach by infecting gastric epithelial cells. It is the primary cause of peptic ulcer disease and gastric cancer (GC). Cytotoxin-associated gene A (CagA) is a virulence factor produced by H. pylori. Strains positive for the CagA protein are associated with more severe gastric diseases. The 3' region of the cagA gene exhibits heterogeneity with respect to tyrosine phosphorylation motifs (EPIYA) and CagA multimerization motifs (CM). CagA proteins are categorized as either Western or Eastern based on EPIYA sequences. CM motifs are also identified as Western and Eastern based on CM sequences identified in Western and East Asian countries. It has been suggested that CagA proteins possessing an Eastern CM type are associated with less severe gastric disorders. In the present study, the effects of two CagA peptides with different CM motifs on cell function were compared: CagA with a Western and Eastern CM motif (CagA-WE), and CagA with two Western CM motifs (CagA-WW). CagA sequences were fused with green fluorescent protein (GFP) to form GFP-CagA fusion proteins. GFP-CagA and GFP control constructs were transfected into human gastric adenocarcinoma cells (AGS). GFP-CagA expression was verified by immunoblotting and immunofluorescence. The results demonstrated that, following 18 h, the CagA-WE-transfected cells were less adherent compared with the CagA-WW transfected cells. CagA has also been reported to cause cell elongation in AGS cells. In the current study, cell elongation was more frequent in the CagA-WW-transfected cells compared with the CagA-WE transfected cells (8.34 vs. 3.97% cells, respectively). The CagA peptides did not affect proliferation or apoptosis rates. These results suggest that different CM motif types may affect CagA virulence.

Structure and function of Helicobacter pylori CagA, the first-identified bacterial protein involved in human cancer

Chronic infection with Helicobacter pylori cagA-positive strains is the strongest risk factor of gastric cancer. The cagA gene-encoded CagA protein is delivered into gastric epithelial cells via bacterial type IV secretion, where it undergoes tyrosine phosphorylation at the Glu-Pro-Ile-Tyr-Ala (EPIYA) motifs. Delivered CagA then acts as a non-physiological scaffold/hub protein by interacting with multiple host signaling molecules, most notably the pro-oncogenic phosphatase SHP2 and the polarity-regulating kinase PAR1/MARK, in both tyrosine phosphorylation-dependent and -independent manners. CagA-mediated manipulation of intracellular signaling promotes neoplastic transformation of gastric epithelial cells. Transgenic expression of CagA in experimental animals has confirmed the oncogenic potential of the bacterial protein. Structural polymorphism of CagA influences its scaffold function, which may underlie the geographic difference in the incidence of gastric cancer. Since CagA is no longer required for the maintenance of established gastric cancer cells, studying the role of CagA during neoplastic transformation will provide an excellent opportunity to understand molecular processes underlying "Hit-and-Run" carcinogenesis.

Helicobacter pylori vacA and cagA genotype diversity and interferon gamma expression in patients with chronic gastritis and patients with gastric cancer

BACKGROUND

Helicobacter pylori (H. pylori) is the main risk factor for the development of chronic gastritis, gastric ulcer, and gastric cancer. In H. pylori-infected individuals, the clinical result is dependent on various factors, among which are bacterial components, the immune response, and environmental influence.

AIMS

To compare IFN-γ expression with the H. pylori vacA and cagA genotypes in patients with chronic gastritis and patients with gastric cancer.

METHODS

Ninety-five patients diagnosed with chronic gastritis and 20 with gastric cancer were included in the study. Three gastric biopsies were taken; one was used for the molecular detection and genotyping of H. pylori; another was fixed in absolute alcohol and histologic sections were made for determining IFN-γ expression through immunohistochemistry.

RESULTS

No differences were found in the cells that expressed IFN-γ between the patients with chronic gastritis (median percentage of positive cells: 82.6% in patients without H. pylori and 82% in infected persons) and those with gastric cancer (70.5% in H. pylori-negative patients and 78.5% in infected persons). IFN-γ expression was 69% in chronic gastritis patients infected with H. pylori vacAs2m2/cagA⁻ it was 86.5% in patients infected with H. pylori vacAs1m2/cagA⁻, 86.5% in vacAs1m1/cagA⁻, and 82% in vacAs1m1/cagA⁺. Similar data were found in the patients with gastric cancer.

CONCLUSIONS

IFN-γ expression varied depending on the H. pylori vacA and cagA genotype, but not in accordance with the presence of chronic gastritis or gastric cancer.

Helicobacter pylori Strains from Duodenal Ulcer Patients Exhibit Mixed babA/B Genotypes with Low Levels of BabA Adhesin and Lewis b Binding

BACKGROUND

BabA is a Helicobacter pylori cell surface adhesin, which binds to the ABO/Le(b) histo-blood group antigens (Le(b)) and serves as a virulence factor.

METHODS

H. pylori single colonies were isolated from 156 [non-ulcer dyspepsia (NUD) = 97, duodenal ulcer (DU) = 34, gastric cancer (GC) = 25)] patients. babA and babB genes were evaluated by gene/locus-specific PCR. BabA protein expression and Le(b) binding activity were determined by immunoblotting and ELISA, respectively.

RESULTS

The combined categorization of H. pylori strains based on high, low or no levels of BabA expression and Le(b) binding, produced 4 groups: (I) BabA-high/Le(b)-high (36 %), (II) BabA-low/Le(b)-low (26 %), (III) BabA-neg/Le(b)-low (30 %) and (IV) BabA-neg/Le(b)-neg (8 %) strains. The majority (63 %) of the BabA-low/Le(b)-low strains exhibited mixed babA/B genotypes as compared to merely 18 % of the BabA-high/Le(b)-high, 15 % of the BabA-neg/Le(b)-neg and 11 % of the BabA-neg/Le(b)-low (P = 0.0001) strains. In contrast to NUD strains, the great majority (70 %) of DU strains were BabA-low/Le(b)-low (11 %, P = 0.0001), which compared to NUD strains, enhanced the risk of DU by 18.8-fold. In parallel, infection with babA/B mixed genotype strains amplified the risk of DU by 3.6-fold (vs. babA-positive: P = 0.01) to 6.9-fold (vs. babA-negative: P = 0.007).

CONCLUSIONS

Here, we show higher prevalence of mixed babA/B genotypes among BabA-low/Le(b)-low clinical strains. Recombination of babA and babB genes across their loci may yield lower BabA expression and lower Le(b) binding activity. We conclude that H. pylori strains with lower Le(b) binding activity are better adapted for colonization of the gastric metaplastic patches in the duodenum and enhance the risk of duodenal ulcers.

Preferential Tim-3 expression on Treg and CD8(+) T cells, supported by tumor-associated macrophages, is associated with worse prognosis in gastric cancer

While infection with H. pylori is a strong risk factor for gastric cancer, most H. pylori-colonized individuals, even those with the high-risk CagA(+)VacA(+) strain, remain asymptomatic over their lifetime. We hypothesized that the discordant outcomes were due to differences in the host immune responses. Previously, Tim-3-mediated immune modulation was observed in H. pylori-challenged mice. In this study, we compared Tim-3-related responses in CagA(+)VacA(+) H. pylori-infected asymptomatic individuals and H. pylori-associated gastric adenocarcinoma patients. We showed that compared to H. pylori-uninfected individuals, both H. pylori-infected asymptomatic and gastric cancer patients upregulated Tim-3 overall. However, the Tim-3 upregulation was enriched on Th1 cells in asymptomatic patients and on Treg and CD8(+) T cells in gastric cancer patients, with respective differences in T cell subset functions. In gastric cancer patients, high Tim-3 expression on Treg and CD8(+) T cells, but not on Th1 cells, was associated with worse prognosis. H. pylori-antigen presentation by tumor-associated macrophages upregulated Tim-3 expression more effectively than by blood monocyte-derived macrophages in vitro. The upregulation of Tim-3 in vitro depended on the concentration of H. pylori antigen but not on whether the cells were from asymptomatic or cancer patients. These data suggest that the discrepancy in Tim-3 upregulation in asymptomatic and cancer subjects is induced by cancer but not the other way around. Once gastric cancer is developed, Tim-3 expression is associated with worse prognosis.

HELICOBACTER PYLORI INFECTION IN PATIENTS WITH DIFFERENT GASTROINTESTINAL DISEASES FROM NORTHERN BRAZIL

BACKGROUND

The mechanisms whereby Helicobacter pylori produces different pathological manifestations in the stomach and duodenum are not fully understood. Considering the geographic diversity in the prevalence of virulence factors of this microorganism and their association with the development of different diseases, the search for pathogenicity markers such as CagA and VacA alleles by molecular techniques has intensified.

OBJECTIVES

To investigate the presence of H. pylori infection and the frequency of different genotypes of this bacterium in patients with gastrointestinal diseases from Northern Brazil, and to establish their association with the histopathological findings.

METHODS

In a prospective study, samples were collected from 554 patients with different gastrointestinal diseases (gastritis, duodenal ulcer, gastric ulcer, and gastric cancer) seen at a referral hospital attending the entire State of Pará, located in the metropolitan region of Belém. Data such as gender and age obtained with an epidemiological questionnaire were analyzed. The presence of H. pylori and the bacterial genotype were investigated by PCR. Gastric biopsies were assessed histologically.

RESULTS

The prevalence of H. pylori infection was 91%. Infection was more frequent among patients with gastric ulcer and gastric cancer. In these groups, there was a predominance of men and older patients when compared to the other two groups studied. The predominant bacterial genotype was s1m1cagA+, which was more frequent among patients with gastric ulcer, duodenal ulcer and gastric cancer. A significant association was observed between s1m1cagA+ strains and a higher degree of inflammation, neutrophil activity and development of intestinal metaplasia.

CONCLUSION

The present study demonstrates a high incidence of H. pylori infection in the patients analyzed, especially among those with gastric ulcer and gastric cancer. Virulent s1m1cagA+ strains predominated and were associated with more severe lesions.

Helicobacter pylori isolated from Iranian drinking water: vacA, cagA, iceA, oipA and babA2 genotype status and antimicrobial resistance properties

Despite the clinical importance of Helicobacter pylori in human gastric disorders, its exact route of transmission is still uncertain. Based on the contentious hypothesis and findings of previous investigations, water may play an important role in the transmission of H. pylori to humans. This study was carried out to investigate the vacA, cagA, oipA, iceA and babA2 genotype status and antimicrobial resistance properties of H. pylori strains isolated from the drinking water samples of four major provinces in Iran. A total of 400 drinking water samples were cultured and tested. H. pylori-positive strains were analyzed for the presence of various genotypes and antimicrobial resistance. Twelve of 400 (3%) water samples were positive for H. pylori. Samples from Isfahan province had the highest, while those from Shiraz had the lowest prevalence of H. pylori. The seasonal distribution was also determined, with the highest prevalence of bacteria in the summer season (7.36%). H. pylori strains harbored the highest levels of resistance against ampicillin (100%), erythromycin (75%), clarithromycin (75%), and trimethoprim (58.3%). The most commonly detected genotypes were vacAs1a (83.3%), vacAm1a (66.6%), vacAs2 (50%) and cagA (50%). The presence of similar genotypes in the H. pylori strains of drinking water and those of human clinical samples suggest that contaminated water maybe the sources of bacteria. Spiramycin and furazolidone are suggested for the treatment of cases of H. pylori infection.

The Intestinal Microbiome and Estrogen Receptor-Positive Female Breast Cancer

The huge communities of residential microbes, including bacteria, viruses, Archaea, and Eukaryotes, that colonize humans are increasingly recognized as playing important roles in health and disease. A complex populous ecosystem, the human gastrointestinal (GI) tract harbors up to 10(11) bacterial cells per gram of luminal content, whose collective genome, the gut metagenome, contains a vastly greater number of individual genes than the human genome. In health, the function of the microbiome might be considered to be in dynamic equilibrium with the host, exerting both local and distant effects. However, 'disequilibrium' may contribute to the emergence of disease, including malignancy. In this review, we discuss how the intestinal bacterial microbiome and in particular how an 'estrobolome,' the aggregate of enteric bacterial genes capable of metabolizing estrogens, might affect women's risk of developing postmenopausal estrogen receptor-positive breast cancer. Estrobolome composition is impacted by factors that modulate its functional activity. Exploring variations in the composition and activities of the estrobolome in healthy individuals and in women with estrogen-driven breast cancer may lead to development of microbiome-based biomarkers and future targeted interventions to attenuate cancer risk.

Helicobacter pylori in bottled mineral water: genotyping and antimicrobial resistance properties

BACKGROUND

Up to now, fecal-oral and oral-oral are the most commonly known routes for transmission of H. pylori, therefore, contaminated water can play an important role in transmission of H. pylori to humans. Genotyping using virulence markers of H. pylori is one of the best approaches to study the correlations between H. pylori isolates from different samples. The present research was carried out to study the vacA, cagA, cagE, oipA, iceA and babA2 genotyping and antimicrobial resistance properties of H. pylori isolated from the bottled mineral water samples of Iran.

RESULTS

Of 450 samples studied, 8 samples (1.77%) were contaminated with H. pylori. Brand C of bottled mineral water had the highest prevalence of H. pylori (3.63%). The bottled mineral water samples of July month had the highest levels of H. pylori-contamination (50%). H. pylori strains had the highest levels of resistance against metronidazole (62.5%), erythromycin (62.5%), clarithromycin (62.5%), amoxicillin (62.5%) and trimethoprim (62.5%). Totally, 12.5% of strains were resistant to more than 6 antibiotics. VvacAs1a (100%), vacAm1a (87.5%), cagA (62.5%), iceA1 (62.5%), oipA (25%), babA2 (25%) and cagE (37.5%) were the most commonly detected genotypes. M1as1a (62.5%), m1as2 (37.5%), m2s2 (37.5%) and S1a/cagA+/IceA2/oipA-/babA2-/cagE- (50%) were the most commonly detected combined genotypes.

CONCLUSIONS

Contaminated bottled mineral water maybe the sources of virulent and resistant strains H. pylori. Careful monitoring of bottled mineral water production may reduce the risk of H. pylori transmission into the human population.