The pathogenesis of Helicobacter pylori-induced gastro-duodenal diseases

Insights from paleomicrobiology into the indigenous peoples of pre-colonial America - a review

This review investigates ancient infectious diseases in the Americas dated to the pre-colonial period and considers what these findings can tell us about the history of the indigenous peoples of the Americas. It gives an overview, but focuses on four microbial pathogens from this period: Helicobacter pylori, Mycobacterium tuberculosis, Trypanosoma cruzi and Coccidioides immitis, which cause stomach ulceration and gastric cancer, tuberculosis, Chagas disease and valley fever, respectively. These pathogens were selected as H. pylori can give insight into ancient human migrations into the Americas, M. tuberculosis is associated with population density and urban development, T. cruzi can elucidate human living conditions and C. immitis can indicate agricultural development. A range of methods are used to diagnose infectious disease in ancient human remains, with DNA analysis by polymerase chain reaction one of the most reliable, provided strict precautions are taken against cross contamination. The review concludes with a brief summary of the changes that took place after European exploration and colonisation.

Upregulation of Soluble HLA-G5 and HLA-G6 Isoforms in the Milder Histopathological Stages of Helicobacter pylori Infection: A Role for Subverting Immune Responses?

The subversion mechanisms employed by Helicobacter pylori (H. pylori) to escape from immune surveillance and to establish persistent infection are poorly understood. Growing evidence indicates that expression of HLA-G, a non-classical major histocompatibility complex molecule, negatively regulates immune responses in pathological conditions, including infectious diseases. In this context, we aimed to evaluate HLA-G expression in the gastric microenvironment of individuals harbouring H. pylori and to correlate it with histological variables. Fifty-four gastric specimens from patients harbouring H. pylori infection were evaluated by immunohistochemistry using anti-HLA-G monoclonal antibody. As a result, HLA-G expression was detected in 43 of 54 specimens harbouring H. pylori. The presence of HLA-G was significantly associated with milder colonization by H. pylori (P < 0.02), milder inflammatory activity (P < 0.02) and bacterium histological location in the gastric antrum. This study is the first to explore HLA-G expression in the context of bacterial infection. Whether the biological role of HLA-G during H. pylori infection is beneficial or hazardous for patients remains to be defined.

Vacuolating cytotoxin A (VacA) - A multi-talented pore-forming toxin from Helicobacter pylori

Helicobacter pylori is associated with severe and chronic diseases of the stomach and duodenum such as peptic ulcer, non-cardial adenocarcinoma and gastric lymphoma, making Helicobacter pylori the only bacterial pathogen which is known to cause cancer. The worldwide rate of incidence for these diseases is extremely high and it is estimated that about half of the world's population is infected with H. pylori. Among the bacterial virulence factors is the vacuolating cytotoxin A (VacA), which represents an important determinant of pathogenicity. Intensive characterization of VacA over the past years has provided insight into an ample variety of mechanisms contributing to host-pathogen interactions. The toxin is considered as an important target for ongoing research for several reasons: i) VacA displays unique features and structural properties and its mechanism of action is unrelated to any other known bacterial toxin; ii) the toxin is involved in disease progress and colonization by H. pylori of the stomach; iii) VacA is a potential and promising candidate for the inclusion as antigen in a vaccine directed against H. pylori and iv) the vacA gene is characterized by a high allelic diversity, and allelic variants contribute differently to the pathogenicity of H. pylori. Despite the accumulation of substantial data related to VacA over the past years, several aspects of VacA-related activity have been characterized only to a limited extent. The biologically most significant effect of VacA activity on host cells is the formation of membrane pores and the induction of vacuole formation. This review discusses recent findings and advances on structure-function relations of the H. pylori VacA toxin, in particular with a view to membrane channel formation, oligomerization, receptor binding and apoptosis.

A systematic review on the association between the Helicobacter pylori vacA i genotype and gastric disease

Helicobacter pylori (H. pylori) has been recognized as a cause of gastrointestinal diseases and progress of the pathology of gastrointestinal diseases is related to the genotype of H. pylori. Published studies have indicated that the H. pylori vacuolating cytotoxin gene A (vacA) i1/i2 genotype is associated with peptic ulcer disease (PUD) and gastric cancer (GC), but their conclusions are inconsistent. This study aimed to further assess the risk of vacA i gene for PUD and/or GC. A systematic search was conducted across three main electronic databases (PubMed, Web of Science, and CNKI). A meta-analysis was then performed on the pooled data of the published articles to estimate the overall influence of vacA i polymorphisms on PUD and/or GC by crude odds ratio (OR) with 95% confidence intervals (CI). The reliability of the results were confirmed by publication bias and sensitivity analysis of included studies. A total of 14 studies were selected according to the specific inclusion and exclusion criteria. The pooled results revealed that patients with GC were more vulnerable to infection by H. pylori i1 genotype (OR = 5.12; 95% CI: 2.66-9.85; P < 0.001) than those with chronic gastritis or nonulcer disease. Moreover, the results of subgroup analysis indicated that the i1 genotype of H. pylori was associated with an increased GC risk (OR = 10.89; 95% CI: 4.11-20.88; P < 0.001) in the Middle Asian population. The H. pylori vacA i1 genotype is associated with an increased GC risk, especially in the Middle Asian population.

Galectin-3 Plays an Important Role in Innate Immunity to Gastric Infection by Helicobacter pylori

We studied the role of galectin-3 (Gal3) in gastric infection by Helicobacter pylori We first demonstrated that Gal3 was selectively expressed by gastric surface epithelial cells and abundantly secreted into the surface mucus layer. We next inoculated H. pylori Sydney strain 1 into wild-type (WT) and Gal3-deficient mice using a stomach tube. At 2 weeks postinoculation, the bacterial cells were mostly trapped within the surface mucus layer in WT mice. In sharp contrast, they infiltrated deep into the gastric glands in Gal3-deficient mice. Bacterial loads in the gastric tissues were also much higher in Gal3-deficient mice than in WT mice. At 6 months postinoculation,H. pylori had successfully colonized within the gastric glands of both WT and Gal3-deficient mice, although the bacterial loads were still higher in the latter. Furthermore, large lymphoid clusters mostly consisting of B cells were frequently observed in the gastric submucosa of Gal3-deficient mice.In vitro, peritoneal macrophages from Gal3-deficient mice were inefficient in killing engulfed H. pylori Furthermore, recombinant Gal3 not only induced rapid aggregation of H. pylori but also exerted a potent bactericidal effect on H. pylori as revealed by propidium iodide uptake and a morphological shift from spiral to coccoid form. However, a minor fraction of bacterial cells, probably transient phase variants of Gal3-binding sugar moieties, escaped killing by Gal3. Collectively, our data demonstrate that Gal3 plays an important role in innate immunity to infection and colonization of H. pylori.

Vaccine against Helicobacter pylori: Inevitable approach

Over three decades have passed since the discovery of Helicobacter pylori (H. pylori), and yet many questions about its treatment remain unanswered. For example, there is no certainty regarding continued use of current antibiotic therapy against H. pylori. The bad news is that even combined regimens are also unable to eradicate bacterial colonization. The worst problem with H. pylori chemotherapy is that even if we identify the most successful regimen, it cannot eliminate the risk of re-infection. This problem is further complicated by the fact that clinicians have no information as to whether probiotics are useful or not. Moreover, to date, we have no large scale produced vaccine effective against H. pylori. Due to the relatively rapid and abundant dissemination of guidelines globally reported concerning management of gastric cancer prevention and therapeutic regimens, clinicians may choose a vaccine as better effective weapon against H. pylori. Therefore, a radical shift in adopted strategies is needed to guide ultimate decisions regarding H. pylori management. In light of failures in vaccine projects, we should identify better vaccine design targeting conserved/essential genes. The unique character and persistence of H. pylori pose obstacles to making an effective vaccine. Preferably, in developing countries, the best reasonable and logical approach is to recommend prophylactic H. pylori vaccine among children as an obligatory national program to limit primary colonization. Trying to produce a therapeutic vaccine would be postponed until later. In reality, we should not forget to prescribe narrow spectrum antibiotics. In the current review, I draw a route to define the best adopted strategy against this rogue bacterium.

Identification of a Latin American-specific BabA adhesin variant through whole genome sequencing of Helicobacter pylori patient isolates from Nicaragua

Background

Helicobacter pylori (H. pylori) is one of the most common bacterial infections in humans and this infection can lead to gastric ulcers and gastric cancer. H. pylori is one of the most genetically variable human pathogens and the ability of the bacterium to bind to the host epithelium as well as the presence of different virulence factors and genetic variants within these genes have been associated with disease severity. Nicaragua has particularly high gastric cancer incidence and we therefore studied Nicaraguan clinical H. pylori isolates for factors that could contribute to cancer risk.

Methods

The complete genomes of fifty-two Nicaraguan H. pylori isolates were sequenced and assembled de novo, and phylogenetic and virulence factor analyses were performed.

Results

The Nicaraguan isolates showed phylogenetic relationship with West African isolates in whole-genome sequence comparisons and with Western and urban South- and Central American isolates using MLSA (Multi-locus sequence analysis). A majority, 77 % of the isolates carried the cancer-associated virulence gene cagA and also the s1/i1/m1 vacuolating cytotoxin, vacA allele combination, which is linked to increased severity of disease. Specifically, we also found that Nicaraguan isolates have a blood group-binding adhesin (BabA) variant highly similar to previously reported BabA sequences from Latin America, including from isolates belonging to other phylogenetic groups. These BabA sequences were found to be under positive selection at several amino acid positions that differed from the global collection of isolates.

Conclusion

The discovery of a Latin American BabA variant, independent of overall phylogenetic background, suggests hitherto unknown host or environmental factors within the Latin American population giving H. pylori isolates carrying this adhesin variant a selective advantage, which could affect pathogenesis and risk for sequelae through specific adherence properties.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-016-0619-y) contains supplementary material, which is available to authorized users.

Correlation of Helicobacter pylori and interleukin-8 mRNA expression in high risk gastric cancer population prediction

AIM: To evaluate (1) the association of the Helicobacter pylori (H. pylori) test and interleukin-8 (IL-8) mRNA expression alone and the severity of gastric cancer (GC); (2) the association of both tests were added to patients' characteristics to identifli Thai suspected patients of gastric cancer who would receive the most benefit; and (3) diagnostic value of levels of IL-8 mRNA expression for gastric cancer.

METHODS: A cross-sectional analytical study was completed with 220 patients with 86 GC patients who underwent endoscopy with gastric surgery divided into non-metastasis and metastasis groups, and 134 patients with benign lesions who underwent endoscopic examination, at the Gastrointestinal Surgery and Endoscopy Unit, Chiang Mai University Hospital between 2006 and 2010. Of 220 patients, 86 cases of diagnosed gastric adenocarcinoma were in an advanced stage and 134 cases were non-cancer patients.

RESULTS: The IL-8 mRNA expression showed predominant association with advanced GC when compared to H. pylori infection alone [OR (95%CI); 0.86 (0.49-1.53) vs 5.44 (3.08-9.62)] when including the patients’ characteristics the highest of the area under the receiver operating characteristic curves (AuROC) of the model were males older than 40 years of age [AuROC (95%CI); 0.81 (0.75-0.86)]. However, preliminary testing for diagnostic indices of four cut-off points of IL-8 mRNA expression to predict the severity of GC cases found an increasing suboptimal trend from the likelihood ratio of positive to differentiate the severity in the GC group. The IL-8 mRNA expression showed a predominant association with GC when compared to H. pylori infection, especially in males older than 40 years of age who may benefit most from this test.

CONCLUSION: The future research of IL-8 mRNA expression to predict severity in the gastric cancer group should be warranted.

Molecular and Structural Analysis of the Helicobacter pylori cag Type IV Secretion System Core Complex

Bacterial type IV secretion systems (T4SSs) can function to export or import DNA, and can deliver effector proteins into a wide range of target cells. Relatively little is known about the structural organization of T4SSs that secrete effector proteins. In this report, we describe the isolation and analysis of a membrane-spanning core complex from the Helicobacter pylori cag T4SS, which has an important role in the pathogenesis of gastric cancer. We show that this complex contains five H. pylori proteins, CagM, CagT, Cag3, CagX, and CagY, each of which is required for cag T4SS activity. CagX and CagY are orthologous to the VirB9 and VirB10 components of T4SSs in other bacterial species, and the other three Cag proteins are unique to H. pylori. Negative stain single-particle electron microscopy revealed complexes 41 nm in diameter, characterized by a 19-nm-diameter central ring linked to an outer ring by spoke-like linkers. Incomplete complexes formed by Δcag3 or ΔcagT mutants retain the 19-nm-diameter ring but lack an organized outer ring. Immunogold labeling studies confirm that Cag3 is a peripheral component of the complex. The cag T4SS core complex has an overall diameter and structural organization that differ considerably from the corresponding features of conjugative T4SSs. These results highlight specialized features of the H. pylori cag T4SS that are optimized for function in the human gastric mucosal environment.

Type IV secretion systems (T4SSs) are versatile macromolecular machines that are present in many bacterial species. In this study, we investigated a T4SS found in the bacterium Helicobacter pylori. H. pylori is an important cause of stomach cancer, and the H. pylori T4SS contributes to cancer pathogenesis by mediating entry of CagA (an effector protein regarded as a “bacterial oncoprotein”) into gastric epithelial cells. We isolated and analyzed the membrane-spanning core complex of the H. pylori T4SS and showed that it contains unique proteins unrelated to components of T4SSs in other bacterial species. These results constitute the first structural analysis of the core complex from this important secretion system.

Cdx2 Expression and Intestinal Metaplasia Induced by H. pylori Infection of Gastric Cells Is Regulated by NOD1-Mediated Innate Immune Responses

Chronic infection with the bacterial Helicobacter pylori is a major cause of gastric and duodenal ulcer disease, gastric mucosal atrophy, and cancer. H. pylori-induced expression of the intestinal epithelial-specific transcription factor caudal-related homeobox 2 (Cdx2) contributes to intestinal metaplasia, a precursor event to gastric cancer. Given a role for the bacterial pattern recognition molecule nucleotide-binding oligomerization domain 1 (NOD1) in the innate immune response to bacterial infection, we investigated mechanisms used by NOD1 to regulate H. pylori infection and its propensity towards the development of intestinal metaplasia. We found that Cdx2 was induced by H. pylori infection in both normal and neoplastic gastric epithelial cells in a manner that was inversely related to NOD1 signaling. Mechanistic investigations revealed that Cdx2 induction relied upon activation of NF-κB but was suppressed by NOD1-mediated activation of TRAF3, a negative regulator of NF-κB. In vivo, prolonged infection of NOD1-deficient mice with H. pylori led to increased Cdx2 expression and intestinal metaplasia. Furthermore, gastric epithelial cells from these mice exhibited increased nuclear expression of the NF-κB p65 subunit and decreased expression of TRAF3. Overall, our findings illuminated a role for NOD1 signaling in attenuating H. pylori-induced Cdx2 expression in gastric epithelial cells, suggesting a rationale to augment NOD1 signaling in H. pylori-infected patients to limit their risks of accumulating precancerous gastric lesions.

[Unpleasant Journey from Helicobacter pylori-associated Gastritis to Gastric Cancer: Cancer Prevention by Taking a Detour]

As a commensal or a pathogen, Helicobacter pylori can change the balance of a complex interaction that exists among gastric epithelial cells, microbes, and their environment. Therefore, unraveling this complex relationship of these mixtures can be expected to help prevent cancer as well as troublesome unmet medical needs of H. pylori infection. Though gastric carcinogenesis is a multi-step process, precancerous lesion can be reversible in the early phase of mucosal damage before reaching the stage of no return. However, biomarkers to predict rejuvenation of precancerous atrophic gastritis have not been identified yet and gastric cancer prevention is still regarded as an impregnable fortress. However, when we take the journey from H. pylori-associated gastritis to gastric cancer, it provides us with the clue for prevention since there are two main preventive strategies: eradication and anti-inflammation. The evidence supporting the former strategy is now ongoing in Japan through a nation-wide effort to eradicate H. pylori in patients with chronic gastritis, but suboptimal apprehension to increasing H. pylori resistance to antibiotics and patient non-compliance still exists. The latter strategy has been continued in the author'sresearch center under siTRP (short-term intervention to revert premalignant lesion) strategy. By focusing on the role of inflammation in the development of H. pylori-associated gastric carcinogenesis, this review is intended to explain the connection between inflammation and gastric cancer. Strategies on H. pylori eradication, removal of inflammation, and reverting preneoplastic lesion will also be introduced. In the end, we expect to be able to prevent gastric cancer by take a detour from the unpleasant journey, i.e. from H. pylori-associated gastritis to gastric cancer.

Evolution of Helicobacter: Acquisition by Gastric Species of Two Histidine-Rich Proteins Essential for Colonization

Metal acquisition and intracellular trafficking are crucial for all cells and metal ions have been recognized as virulence determinants in bacterial pathogens. Virulence of the human gastric pathogen Helicobacter pylori is dependent on nickel, cofactor of two enzymes essential for in vivo colonization, urease and [NiFe] hydrogenase. We found that two small paralogous nickel-binding proteins with high content in Histidine (Hpn and Hpn-2) play a central role in maintaining non-toxic intracellular nickel content and in controlling its intracellular trafficking. Measurements of metal resistance, intracellular nickel contents, urease activities and interactomic analysis were performed. We observed that Hpn acts as a nickel-sequestration protein, while Hpn-2 is not. In vivo, Hpn and Hpn-2 form homo-multimers, interact with each other, Hpn interacts with the UreA urease subunit while Hpn and Hpn-2 interact with the HypAB hydrogenase maturation proteins. In addition, Hpn-2 is directly or indirectly restricting urease activity while Hpn is required for full urease activation. Based on these data, we present a model where Hpn and Hpn-2 participate in a common pathway of controlled nickel transfer to urease. Using bioinformatics and top-down proteomics to identify the predicted proteins, we established that Hpn-2 is only expressed by H. pylori and its closely related species Helicobacter acinonychis. Hpn was detected in every gastric Helicobacter species tested and is absent from the enterohepatic Helicobacter species. Our phylogenomic analysis revealed that Hpn acquisition was concomitant with the specialization of Helicobacter to colonization of the gastric environment and the duplication at the origin of hpn-2 occurred in the common ancestor of H. pylori and H. acinonychis. Finally, Hpn and Hpn-2 were found to be required for colonization of the mouse model by H. pylori. Our data show that during evolution of the Helicobacter genus, acquisition of Hpn and Hpn-2 by gastric Helicobacter species constituted a decisive evolutionary event to allow Helicobacter to colonize the hostile gastric environment, in which no other bacteria persistently thrives. This acquisition was key for the emergence of one of the most successful bacterial pathogens, H. pylori.

Helicobacter pylori is a bacterium that persistently colonizes the stomach of half of the human population. Infection by H. pylori is associated with gastritis, peptic ulcer disease and adenocarcinoma. To resist gastric acidity and proliferate in the stomach, H. pylori relies on urease, an enzyme that contains a nickel-metallocenter at its active site. Thus, nickel is a virulence determinant for H. pylori. Our aim is to characterize how H. pylori controls the intracellular nickel concentration to avoid toxicity, which protein partners are involved, and how they impact urease activity and virulence. We characterized two H. pylori proteins, Hpn and Hpn-2 that are rich in Histidine residues. We demonstrated that Hpn is involved in nickel sequestration, that the two proteins interact with each other and that their combined activities participate in a nickel transfer pathway to urease. Hpn is only expressed in gastric Helicobacter species able to colonize the stomach and Hpn-2 is restricted to the H. pylori and its close relative H. acinonychis. We found that both proteins are essential for colonization of a mouse model by H. pylori. We conclude that during evolution, the acquisition of Hpn and Hpn-2 by gastric Helicobacter species was decisive for their capacity to colonize the stomach.

Identification of novel scaffolds for potential anti-Helicobacter pylori agents based on the crystal structure of H. pylori 3-deoxy-d-manno-octulosonate 8-phosphate synthase (HpKDO8PS)

The crystal structure of 3-deoxy-d-manno-octulosonate-8-phosphate synthase (KDO8PS) from Helicobacter pylori (HpKDO8PS) was determined alone and within various complexes, revealing an extra helix (HE) that is absent in the structures of KDO8PS from other organisms. In contrast to the metal coordination of the KDO8PS enzyme from Aquifex aeolicus, HpKDO8PS is specifically coordinated with Cd(2+) or Zn(2+) ions, and isothermal titration calorimetry (ITC) and differential scanning fluorimetry (DSF) revealed that Cd(2+) thermally stabilizes the protein structure more efficiently than Zn(2+). In the substrate-bound structure, water molecules play a key role in fixing residues in the proper configuration to achieve a compact structure. Using the structures of HpKDO8PS and API [arabinose 5-phosphate (A5P) and phosphoenolpyruvate (PEP) bisubstrate inhibitor], we generated 21 compounds showing potential HpKDO8PS-binding properties via in silico virtual screening. The capacity of three, avicularin, hyperin, and MC181, to bind to HpKDO8PS was confirmed through saturation transfer difference (STD) experiments, and we identified their specific ligand binding modes by combining competition experiments and docking simulation analysis. Hyperin was confirmed to bind to the A5P binding site, primarily via hydrophilic interaction, whereas MC181 bound to both the PEP and A5P binding sites through hydrophilic and hydrophobic interactions. These results were consistent with the epitope mapping by STD. Our results are expected to provide clues for the development of HpKDO8PS inhibitors.

Role of Helicobacter pylori infection in gastric carcinogenesis: Current knowledge and future directions

Helicobacter pylori (H. pylori) plays a role in the pathogenesis of gastric cancer. The outcome of the infection depends on environmental factors and bacterial and host characteristics. Gastric carcinogenesis is a multistep process that is reversible in the early phase of mucosal damage, but the exact point of no return has not been identified. Therefore, two main therapeutic strategies could reduce gastric cancer incidence: (1) eradication of the already present infection; and (2) immunization (prior to or during the course of the infection). The success of a gastric cancer prevention strategy depends on timing because the prevention strategy must be introduced before the point of no return in gastric carcinogenesis. Although the exact point of no return has not been identified, infection should be eradicated before severe atrophy of the gastric mucosa develops. Eradication therapy rates remain suboptimal due to increasing H. pylori resistance to antibiotics and patient noncompliance. Vaccination against H. pylori would reduce the cost of eradication therapies and lower gastric cancer incidence. A vaccine against H. pylori is still a research challenge. An effective vaccine should have an adequate route of delivery, appropriate bacterial antigens and effective and safe adjuvants. Future research should focus on the development of rescue eradication therapy protocols until an efficacious vaccine against the bacterium becomes available.

Efficacy, safety, and immunogenicity of an oral recombinant Helicobacter pylori vaccine in children in China: a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Helicobacter pylori is one of the most common gastric pathogens, affecting at least half the world's population, and is strongly associated with gastritis, peptic ulcer, gastric adenocarcinoma, and lymphoma. We aimed to assess the efficacy, safety, and immunogenicity of a three-dose oral recombinant H pylori vaccine in children in China.

METHODS

We did this randomised, double-blind, placebo-controlled, phase 3 trial at one centre in Ganyu County, Jiangsu Province, China. Healthy children aged 6-15 years without past or present H pylori infection were randomly assigned (1:1), via computer-generated randomisation codes in blocks of ten, to receive the H pylori vaccine or placebo. Participants, their guardians, and study investigators were masked to treatment allocation. The primary efficacy endpoint was the occurrence of H pylori infection within 1 year after vaccination. We did analysis in the per-protocol population. This trial is registered with ClinicalTrials.gov, number NCT02302170.

FINDINGS

Between Dec 2, 2004, and March 19, 2005, we randomly assigned 4464 participants to either the vaccine group (n=2232) or the placebo group (n=2232), of whom 4403 (99%) participants completed the three-dose vaccination schedule and were included in the per-protocol efficacy analysis. We extended follow-up to 3 years. We recorded 64 events of H pylori infection within the first year (14 events in 2074·3 person-years at risk in the vaccine group vs 50 events in 2089·6 person-years at risk in the placebo group), resulting in a vaccine efficacy of 71·8% (95% CI 48·2-85·6). 157 (7%) participants in the vaccine group and 161 (7%) participants in the placebo group reported at least one adverse reaction. Serious adverse events were reported in five (<1%) participants in the vaccine group and seven (<1%) participants in the placebo group, but none was considered to be vaccination related.

INTERPRETATION

The oral recombinant H pylori vaccine was effective, safe, and immunogenic in H pylori-naive children. This vaccine could substantially reduce the incidence of H pylori infection; however, follow up over a longer period is needed to confirm the protection of the vaccine against H pylori-associated diseases.

FUNDING

Chongqing Kangwei Biological Technology.

A Creative Helicobacter pylori Diagnosis Scheme Based on Multiple Genetic Analysis System: Qualification and Quantitation

BACKGROUND

Currently, several diagnostic assays for Helicobacter pylori (H. pylori) are available, but each has some limitations. Further, a high-flux quantitative assay is required to assist clinical diagnosis and monitor the effectiveness of therapy and novel vaccine candidates.

METHODS

Three hundred and eighty-seven adult patients [nonulcer dyspepsia (NUD) 295, peptic ulcer disease (PUD) 77, gastric cancer (GC) 15] were enrolled for gastrointestinal endoscopies. Three biopsy samples from gastric antrum were collected for the following tests: culture, rapid urease test (RUT), histopathology, conventional polymerase chain reaction (PCR), and Multiple Genetic Analysis System (MGAS). The diagnostic capability of H. pylori for all methods was evaluated through the receiver operating characteristic (ROC) curves.

RESULTS

Based on the gold standard, the sensitivity and specificity of MGAS were 92.9 and 92.4%, and positive predict value (PPV) and negative predict value (NPV) were 96.0 and 87.1%, respectively. All the above parameters of MGAS were higher than that of culture (except its specificity), RUT and histopathology, and nearly closed to that of conventional PCR. The area under curve (AUC) was 0.7575 (Culture), 0.8870 (RUT), 0.9000 (Histopathology), 0.9496 (Conventional PCR), and 0.9277 (MGAS). No significant statistical difference was observed for the H. pylori DNA load in different disease groups (p = .067). In contrast, a statistically significant difference in the H. pylori DNA copy number was observed based on age (p = .043) and gender (p = .021).

CONCLUSIONS

The data showed that MGAS performed well in detecting H. pylori infection. Furthermore, the quantitative analysis showed that the load of H. pylori was significantly different within both age and gender groups. These results suggested that MGAS could be a potential alternative method for clinical detection and monitoring of the effectiveness of H. pylori therapy.

Expansion of the tetracycline-dependent regulation toolbox for Helicobacter pylori

In an effort to gain greater understanding of the biology and infection processes of Helicobacter pylori, we have expanded the functionality of the tetracycline-dependent gene regulation (tet) system to provide more improved and versatile genetic control and facilitate the generation of conditional mutants to study essential genes. Second-generation tetracycline-responsive H. pylori uPtetO5 promoters were based on the mutated core ureA promoter. Single point mutations at either the ribosomal binding site or the start codon were introduced to shift the regulatory range of three uPtetO5 derivatives. All promoters were tested for regulation by TetR and revTetR using dapD, a gene essential to peptidoglycan biosynthesis, as a reporter. All tet promoters were effectively regulated by both TetR and revTetR, and their regulation windows overlapped so as to cover a broad range of expression levels. tet promoters uPtetO5m1 and uPtetO5m2 could be sufficiently silenced by both TetR and revTetR so that the conditional mutants could not grow in the absence of diaminopimelic acid (DAP). Furthermore, through the use of these inducible promoters, we reveal that insufficient DAP biosynthesis results in viable cells with altered morphology. Overall, the development and optimization of tet regulation for H. pylori will not only permit the study of essential genes but also facilitate investigations into gene dosage effects on H. pylori physiology.

Helicobacter pylori virulence factors in development of gastric carcinoma

Helicobacter pylori plays a vital role in the pathogenesis of gastric carcinoma. However, only a relatively small proportion of individuals infected with H. pylori develop gastric carcinoma. Differences in the incidence of gastric carcinoma among infected individuals can be explained, at least partly, by the different genotypes of H. pylori virulence factors. Thus far, many virulence factors of H. pylori, such as Cag PAI, VacA, OMPs and DupA, have been reported to be involved in the development of gastric cancer. The risk of developing gastric cancer during H. pylori infection is affected by specific host-microbe interactions that are independent of H. pylori virulence factors. In this review, we discuss virulence factors of H. pylori and their role in the development of gastric carcinoma that will provide further understanding of the biological interactions of H. pylori with the host.

Gastroprotective activity of the hydroethanolic extract and isolated compounds from the leaves of Solanum cernuum Vell

ETHNOPHARMACOLOGICAL RELEVANCE

Solanum cernuum Vell. (Solanaceae) is a Brazilian medicinal plant, traditionally known as "panaceia". Its folk name is probably due to its wide range of applications in traditional medicine including the treatment of ulcers.

AIM OF THE STUDY

To evaluate the gastroprotective activities of the hydroethanolic extract (ESC) of S. cernuum and its major isolated compounds using in vivo gastric ulcer models.

MATERIAL AND METHODS

The ESC extract was obtained by maceration followed by percolation of the dried and powdered leaves of S. cernuum in ethanol:water (7:3). The major compounds in the extract were isolated by applying various preparative chromatographic techniques. The gastroprotective activity was evaluated in mice using different gastric ulcer-induced models. The anti-Helicobacter pylori activity was performed using the agar-well diffusion and broth microdilution methods.

RESULTS

The ESC extract showed gastroprotective effects in the assay of acute gastric ulcer-induced by HCl/EtOH, nonsteroidal anti-inflammatory drug, and acetic acid-induced chronic ulcer protocols. The results also demonstrated that the gastroprotection induced by ESC extract is related to the activity of nitric oxide and endogenous sulfhydryls, which are important gastroprotective factors. The ESC extract and the alkaloid cernumidine did not show activity against H. pylori in the concentrations tested.

CONCLUSIONS

The present study showed that the crude extract of S. cernuum possessed gastroprotective activity which corroborating the traditional use of this plant for the treatment of gastric ulcers. The isolated flavonoids, quercitrin and afzelin as well as the phenylpropanoid, isoferulic acid are suggested to be the compounds responsible for the gastroprotective activity of S. cernuum extract.

Differential inflammatory response to Helicobacter pylori infection: etiology and clinical outcomes

The bacterial pathogen Helicobacter pylori commonly colonizes the human gastric mucosa during early childhood and persists throughout life. The organism has evolved multiple mechanisms for evading clearance by the immune system and, despite inducing inflammation in the stomach, the majority of infections are asymptomatic. H. pylori is the leading cause of peptic ulcer disease and gastric cancer. However, disease outcomes are related to the pattern and severity of chronic inflammation in the gastric mucosa, which in turn is influenced by both bacterial and host factors. Despite over 2 decades of intensive research, there remains an incomplete understanding of the circumstances leading to disease development, due to the fascinating complexity of the host-pathogen interactions. There is accumulating data concerning the virulence factors associated with increased risk of disease, and the majority of these have pro-inflammatory activities. Despite this, only a small proportion of those infected with virulent strains develop disease. Several H. pylori virulence factors have multiple effects on different cell types, including the induction of pro- and anti-inflammatory, immune stimulatory, and immune modulatory responses. The expression of multiple virulence factors is also often linked, making it difficult to assess the meaning of their effects in isolation. Overall, H. pylori is thought to usually modulate inflammation and limit acute damage to the mucosa, enabling the bacteria to persist. If this delicate balance is disturbed, disease may then develop.

Patterns of EPIYA motifs among cagA-positive Helicobacter pylori strains: a case-control study in a Turkish population with Eurasian geographical features

Geographical variation in the frequency of various gastroduodenal pathologies was shown to be related to the geographical diversity of H. pylori CagA Glu-Pro-Ile-Tyr-Ala (EPIYA) patterns. We examined the EPIYA patterns of H. pylori and the association of EPIYA patterns with gastric cancer (GC) for the first time, to the best of our knowledge, in Turkey. The patient group (PG) contained 60 patients [38 GC and 22 duodenal ulcer (DU) patients]. The control group (CG) was 110 individuals [94 gastritis patients and 16 persons with a normal gastrointestinal system (NGIS)]. Specific primers were used for the detection of cagA including empty-site-positive and EPIYA-A, -B, -C, -D PCR. Bands of EPIYA-A, -B, -C were confirmed by DNA sequencing. One hundred and forty-two (83.5 %) strains [60 in the PG (38 GC, 22 DU), 82 in the CG (72 gastritis, 10 NGIS)] were positive for the cagA gene. EPIYA-C with multiple repeats was detected in 34 (23.9 %) strains, and 22 (64.7 %) were from GC patients. EPIYA-C with one repeat was detected in 89 (62.7 %) strains, and 54 (60.7 %) were from gastritis patients. EPIYT was detected in 10 strains, and EPIYA-D was not detected. The number of EPIYA-C with multiple repeats was significantly higher for the PG than for the CG (P < 0.0001). In GC patients, the number of EPIYA-C with multiple repeats was significantly higher than one repeat (P < 0.0001). In conclusion, our study showed that multiple EPIYA-C repeats increases the GC risk by 30.6-fold and the DU risk by 8.9-fold versus the CG. This indicates that Western-type H. pylori strains in Turkey have similar EPIYA motifs to those of neighbouring countries and Western populations.

Virulence genes of Helicobacter pylori in gastritis, peptic ulcer and gastric cancer in Laos

BACKGROUND

Helicobacter pylori (H. pylori) infection is an established cause of peptic ulcers and gastric cancer. The aim of this study was to identify H. pylori genotypes and to examine their associations with geographical regions and gastritis, peptic ulcers and gastric cancer in Laos.

MATERIALS AND METHODS

A total of 329 Lao dyspeptic patients who underwent gastroscopy at Mahosot Hospital, Vientiane, Laos during December 2010--March 2012 were enrolled. Two biopsy specimens (one each from the antrum and corpus) were obtained for CLO testing and only CLO test-positive gastric tissue were used to extract DNA. PCR and sequencing were identified for variants of the cagA and vacA genotypes.

RESULTS

Some 119 Laos patients (36.2%) were found to be infected with H. pylori including 83 with gastritis, 13 with gastric ulcers (GU), 20 with duodenal ulcers (DU) and 3 with gastric cancer. cagA was detected in 99.2%. East-Asian-type cagA (62%) and vacA s1c (64.7%) were predominant genotypes in Laos. vacA s1c-m1b was significantly higher in GU than gastritis (53.8% vs. 24.1%; P-value=0.04) whereas vacA s1a-m2 was significantly higher in DU than gastritis (40.0% vs. 16.9%; P-value=0.03). East-Asian-type cagA and vacA s1c were significantly higher in highland than lowland Lao (100% vs. 55.8%; P-value=0.001 and 88.2% vs. 61.5%, P-value=0.03 respectively).

CONCLUSIONS

H. pylori is a common infection in Laos, as in other countries in Southeast Asia. The cagA gene was demonstrated in nearly all Laos patients, cagA and vacA genotypes being possible important factors in explaining H. pylori infection and disease outcomes in Laos.

Instrumental Role of Helicobacter pylori γ-Glutamyl Transpeptidase in VacA-Dependent Vacuolation in Gastric Epithelial Cells

Helicobacter pylori causes cellular vacuolation in host cells, a cytotoxic event attributed to vacuolating cytotoxin (VacA) and the presence of permeant weak bases such as ammonia. We report here the role of γ-glutamyl transpeptidase (GGT), a constitutively expressed secretory enzyme of H. pylori, in potentiating VacA-dependent vacuolation formation in H. pylori-infected AGS and primary gastric cells. The enhancement is brought about by GGT hydrolysing glutamine present in the extracellular medium, thereby releasing ammonia which accentuates the VacA-induced vacuolation. The events of vacuolation in H. pylori wild type (WT)- and Δggt-infected AGS cells were first captured and visualized by real-time phase-contrast microscopy where WT was observed to induce more vacuoles than Δggt. By using semi-quantitative neutral red uptake assay, we next showed that Δggt induced significantly less vacuolation in AGS and primary gastric epithelial cells as compared to the parental strain (P<0.05) indicating that GGT potentiates the vacuolating effect of VacA. Notably, vacuolation induced by WT was significantly reduced in the absence of GGT substrate, glutamine (P<0.05) or in the presence of a competitive GGT inhibitor, serine-borate complex. Furthermore, the vacuolating ability of Δggt was markedly restored when co-incubated with purified recombinant GGT (rGGT), although rGGT itself did not induce vacuolation independently. Similarly, the addition of exogenous ammonium chloride as a source of ammonia also rescued the ability of Δggt to induce vacuolation. Additionally, we also show that monoclonal antibodies against GGT effectively inhibited GGT activity and successfully suppressed H. pylori-induced vacuolation. Collectively, our results clearly demonstrate that generation of ammonia by GGT through glutamine hydrolysis is responsible for enhancing VacA-dependent vacuolation. Our findings provide a new perspective on GGT as an important virulence factor and a promising target in the management of H. pylori-associated gastric diseases.

New NCI-N87-derived human gastric epithelial line after human telomerase catalytic subunit over-expression

AIM: To establish a cellular model correctly mimicking the gastric epithelium to overcome the limitation in the study of Helicobacter pylori (H. pylori) infection.

METHODS: Aiming to overcome this limitation, clones of the heterogenic cancer-derived NCI-N87 cell line were isolated, by stably-transducing it with the human telomerase reverse-transcriptase (hTERT) catalytic subunit gene. The clones were first characterized regarding their cell growth pattern and phenotype. For that we measured the clones’ adherence properties, expression of cell-cell junctions’ markers (ZO-1 and E-cadherin) and ability to generate a sustained transepithelial electrical resistance. The gastric properties of the clones, concerning expression of mucins, zymogens and glycan contents, were then evaluated by haematoxylin and eosin staining, Periodic acid Schiff (PAS) and PAS/Alcian Blue-staining, immunocytochemistry and Western blot. In addition, we assessed the usefulness of the hTERT-expressing gastric cell line for H. pylori research, by performing co-culture assays and measuring the IL-8 secretion, by ELISA, upon infection with two H. pylori strains differing in virulence.

RESULTS: Compared with the parental cell line, the most promising NCI-hTERT-derived clones (CL5 and CL6) were composed of cells with homogenous phenotype, presented higher relative telomerase activities, better adhesion properties, ability to be maintained in culture for longer periods after confluency, and were more efficient in PAS-reactive mucins secretion. Both clones were shown to produce high amounts of MUC1, MUC2 and MUC13. NCI-hTERT-CL5 mucins were shown to be decorated with blood group H type 2 (BG-H), Lewis-x (Le^x), Le^y and Le^a and, in a less extent, with BG-A antigens, but the former two antigens were not detected in the NCI-hTERT-CL6. None of the clones exhibited detectable levels of MUC6 nor sialylated Le^x and Le^a glycans. Entailing good gastric properties, both NCI-hTERT-clones were found to produce pepsinogen-5 and human gastric lipase. The progenitor-like phenotype of NCI-hTERT-CL6 cells was highlighted by large nuclei and by the apical vesicular-like distribution of mucin 5AC and Pg5, supporting the accumulation of mucus-secreting and zymogens-chief mature cells functions.

CONCLUSION: These traits, in addition to resistance to microaerobic conditions and good responsiveness to H. pylori co-culture, in a strain virulence-dependent manner, make the NCI-hTERT-CL6 a promising model for future in vitro studies.

Helicobacter pylori Activates and Expands Lgr5(+) Stem Cells Through Direct Colonization of the Gastric Glands

BACKGROUND & AIMS

Helicobacter pylori infection is the main risk factor for gastric cancer. We characterized the interactions of H pylori with gastric epithelial progenitor and stem cells in humans and mice and investigated how these interactions contribute to H pylori-induced pathology.

METHODS

We used quantitative confocal microscopy and 3-dimensional reconstruction of entire gastric glands to determine the localizations of H pylori in stomach tissues from humans and infected mice. Using lineage tracing to mark cells derived from leucine-rich repeat-containing G-protein coupled receptor 5-positive (Lgr5(+)) stem cells (Lgr5-eGFP-IRES-CreERT2/Rosa26-TdTomato mice) and in situ hybridization, we analyzed gastric stem cell responses to infection. Isogenic H pylori mutants were used to determine the role of specific virulence factors in stem cell activation and pathology.

RESULTS

H pylori grow as distinct bacterial microcolonies deep in the stomach glands and interact directly with gastric progenitor and stem cells in tissues from mice and humans. These gland-associated bacteria activate stem cells, increasing the number of stem cells, accelerating Lgr5(+) stem cell proliferation, and up-regulating expression of stem cell-related genes. Mutant bacteria with defects in chemotaxis that are able to colonize the stomach surface but not the antral glands in mice do not activate stem cells. In addition, bacteria that are unable to inject the contact-dependent virulence factor CagA into the epithelium colonized stomach glands in mice, but did not activate stem cells or produce hyperplasia to the same extent as wild-type H pylori.

CONCLUSIONS

H pylori colonize and manipulate the progenitor and stem cell compartments, which alters turnover kinetics and glandular hyperplasia. Bacterial ability to alter the stem cells has important implications for gastrointestinal stem cell biology and H pylori-induced gastric pathology.

Epigenetic silencing of microRNA-149 in cancer-associated fibroblasts mediates prostaglandin E2/interleukin-6 signaling in the tumor microenvironment

Tumor initiation and growth depend on its microenvironment in which cancer-associated fibroblasts (CAFs) in tumor stroma play an important role. Prostaglandin E2 (PGE2) and interleukin (IL)-6 signal pathways are involved in the crosstalk between tumor and stromal cells. However, how PGE2-mediated signaling modulates this crosstalk remains unclear. Here, we show that microRNA (miR)-149 links PGE2 and IL-6 signaling in mediating the crosstalk between tumor cells and CAFs in gastric cancer (GC). miR-149 inhibited fibroblast activation by targeting IL-6 and miR-149 expression was substantially suppressed in the CAFs of GC. miR-149 negatively regulated CAFs and their effect on GC development both in vitro and in vivo. CAFs enhanced epithelial-to-mesenchymal transition (EMT) and the stem-like properties of GC cells in a miR-149-IL-6-dependent manner. In addition to IL-6, PGE2 receptor 2 (PTGER2/EP2) was revealed as another potential target of miR-149 in fibroblasts. Furthermore, H. pylori infection, a leading cause of human GC, was able to induce cyclooxygenase-2 (COX-2)/PGE2 signaling and to enhance PGE2 production, resulting in the hypermethylation of miR-149 in CAFs and increased IL-6 secretion. Our findings indicate that miR-149 mediates the crosstalk between tumor cells and CAFs in GC and highlight the potential of interfering miRNAs in stromal cells to improve cancer therapy.

Helicobacter pylori-Mediated Protection against Extra-Gastric Immune and Inflammatory Disorders: The Evidence and Controversies

A large number of studies link H. pylori infection with a reduced risk of developing extra-gastric conditions such as allergy, asthma, inflammatory bowel disease, coeliac disease and multiple sclerosis. The strength of the evidence for these protective associations is quite variable, and published studies often do not agree. This review article discusses some of the reasons for these discrepancies, and the difficulties faced when designing studies. Examples of some protective disease associations are described in detail, where the evidence is most abundant and thought to be more reliable. The most convincing of these are supported by published mechanistic data, for example with animal models, or incidence of disease exacerbation in humans following H. pylori eradication. Although controversial, this field is very important as the prevalence of H. pylori is decreasing throughout the world whilst many chronic diseases are becoming more common. These trends are likely to continue in the future, therefore it is important that we fully understand if and how H. pylori confers protection.

Antisecretory, gastroprotective, antioxidant and anti-Helicobcter pylori activity of zerumbone from Zingiber zerumbet (L.) Smith

BACKGROUND

Zingiber zerumbet Smith is a perennial herb, broadly distributed in many tropical areas. In Malaysia, it's locally known among the Malay people as "lempoyang" and its rhizomes, particularly, is widely used in traditional medicine for the treatment of peptic ulcer disease beyond other gastric disorders.

AIM OF THE STUDY

The aim of the current study is to evaluate the gastroprotective effect of zerumbone, the main bioactive compound of Zingiber zerumbet rhizome, against ethanol-induced gastric ulcer model in rats.

MATERIALS AND METHODS

Rats were pre-treated with zerumbone and subsequently exposed to acute gastric ulcer induced by absolute ethanol administration. Following treatment, gastric juice acidity, ulcer index, mucus content, histological analysis (HE and PAS), immunohistochemical localization for HSP-70, prostaglandin E2 synthesis (PGE2), non-protein sulfhydryl gastric content (NP-SH), reduced glutathione level (GSH), and malondialdehyde level (MDA) were evaluated in ethanol-induced ulcer in vivo. Ferric reducing antioxidant power assay (FRAP) and anti-H. pylori activity were investigated in vitro.

RESULTS

The results showed that the intragastric administration of zerumbone protected the gastric mucosa from the aggressive effect of ethanol-induced gastric ulcer, coincided with reduced submucosal edema and leukocyte infiltration. This observed gastroprotective effect of zerumbone was accompanied with a significant (p <0.05) effect of the compound to restore the lowered NP-SH and GSH levels, and to reduce the elevated MDA level into the gastric homogenate. Moreover, the compound induced HSP-70 up-regulation into the gastric tissue. Furthermore, zerumbone significantly (p <0.05) enhanced mucus production, showed intense PAS stain and maintained PG content near to the normal level. The compound exhibited antisecretory activity and an interesting minimum inhibitory concentration (MIC) against H. pylori strain.

CONCLUSION

The results of the present study revealed that zerumbone promotes ulcer protection, which might be attributed to the maintenance of mucus integrity, antioxidant activity, and HSP-70 induction. Zerumbone also exhibited antibacterial action against H. pylori.

Elevated levels of adaption in Helicobacter pylori genomes from Japan; a link to higher incidences of gastric cancer?

Helicobacter pylori is a bacterium that lives in the human stomach and is a major risk factor for gastric cancer and ulcers. H.pylori is host dependent and has been carried with human populations around the world after their departure from Africa. We wished to investigate how H.pylori has coevolved with its host during that time, focusing on strains from Japanese and European populations, given that gastric cancer incidence is high in Japanese populations, while low in European. A positive selection analysis of eight H.pylori genomes was conducted, using maximum likelihood based pairwise comparisons in order to maximize the number of strain-specific genes included in the study. Using the genic Ka/Ks ratio, comparisons of four Japanese H.pylori genomes suggests 25–34 genes under positive selection, while four European H.pylori genomes suggests 16–21 genes; few of the genes identified were in common between lineages. Of the identified genes which were annotated, 38% possessed homologs associated with pathogenicity and / or host adaptation, consistent with their involvement in a coevolutionary ‘arms race’ with the host. Given the efficacy of identifying host interaction factors de novo, in the absence of functionally annotated homologs our evolutionary approach may have value in identifying novel genes which H.pylori employs to interact with the human gut environment. In addition, the larger number of genes inferred as being under positive selection in Japanese strains compared to European implies a stronger overall adaptive pressure, potentially resulting from an elevated immune response which may be linked to increased inflammation, an initial stage in the development of gastric cancer.

Duodenal ulcer promoting gene 1 (dupA1) is associated with A2147G clarithromycin-resistance mutation but not interleukin-8 secretion from gastric mucosa in Iraqi patients

Helicobacter pylori causes peptic ulceration and gastric adenocarcinoma. The aims were to study the influence of dupA1 positivity upon interleukin-8 (IL-8) secretion from gastric mucosa and determine the prevalence of mutations responsible for clarithromycin and fluoroquinolone resistance. DNA was extracted from 74 biopsies and the virulence factors were studied. Levels of IL-8 in gastric mucosa were measured using ELISA and the mutations responsible for clarithromycin and fluoroquinolone resistance were determined using a GenoType-HelicoDR assay. The prevalence of cagA in strains isolated from gastric ulcer (GU) and duodenal ulcer (DU) was significantly higher than those isolated from non-ulcer disease (NUD) (90% and 57.9% versus 33.3%; p 0.01). The vacA s1m1 genotype was more prevalent in patients with DU (73.7%) and GU (70%) than in those with NUD (13.3%) (p 0.01). The prevalence of dupA1 was higher in DU patients (36.8%) than those with GU (10%) and NUD (8.9%) (p 0.01). Multivariate analysis showed that a cagA+/vacA s1i1m2 virulence gene combination was independently associated with the developing peptic ulcer disease (PUD) with increased odds of developing PUD (p 0.03; OR = 2.1). We found no significant difference in the levels of IL-8 secretion in gastric mucosa infected with H. pylori dupA-negative and H. pylori dupA1-positive strains (dupA-negative: mean ± median: 28 ± 26 versus 30 ± 27.1 for dupA1; p 0.6). While 12 strains were clarithromycin resistant, only three isolates were levofloxacin resistant. A significant association was found between dupA1 genotype and A2147G clarithromycin resistance mutation (p <0.01). Further study is needed to explore the relationship between virulence factors and disease process and treatment failure.

Helicobacter pylori infection reduces disease severity in an experimental model of multiple sclerosis

Recent research has demonstrated that infection with the bacterial pathogen Helicobacter pylori is less common amongst patients with multiple sclerosis (MS), an inflammatory demyelinating disease of the central nervous system (CNS). We aimed to compare the prevalence of H. pylori amongst MS patients and healthy controls, and also investigated the impact of this infection on an animal model for MS, experimental autoimmune encephalomyelitis (EAE). The H. pylori status of 71 MS patients and 42 healthy controls was determined by serology. Groups of C57BL/6 mice were infected with H. pylori, or given diluent alone as a placebo, prior to inducing EAE. Clinical scores were assessed for all mice, and spleens and spinal cord tissue were harvested. CD4⁺ T cell subsets were quantified by flow cytometry, and T cell proliferation assays were performed. In MS patients the seroprevalence of H. pylori was half that of healthy controls (p = 0.018). Over three independent experiments, prior H. pylori infection had a moderate effect in reducing the severity of EAE (p = 0.012). In line with this, the antigen-specific T cell proliferative responses of infected animals were significantly reduced (p = 0.001), and there was a fourfold reduction in the number of CD4⁺ cells in the CNS. CD4⁺ populations in both the CNS and the spleens of infected mice also contained greatly reduced proportions of IFNγ⁺, IL-17⁺, T-bet⁺, and RORγt⁺ cells, but the proportions of Foxp3⁺ cells were equivalent. There were no differences in the frequency of splenic CD4⁺cells expressing markers of apoptosis between infected and uninfected animals. H. pylori was less prevalent amongst MS patients. In mice, the infection exerted some protection against EAE, inhibiting both Th1 and Th17 responses. This could not be explained by the presence of increased numbers of Foxp3⁺ regulatory T cells, or T cell apoptosis. This is the first direct experimental evidence showing that H. pylori may provide protection against inflammatory demyelination in the CNS.

Helicobacter pylori: Genomic Insight into the Host-Pathogen Interaction

The advent of genomic analyses has revolutionized the study of human health. Infectious disease research in particular has experienced an explosion of bacterial genomic, transcriptomic, and proteomic data complementing the phenotypic methods employed in traditional bacteriology. Together, these techniques have revealed novel virulence determinants in numerous pathogens and have provided information for potential chemotherapeutics. The bacterial pathogen, Helicobacter pylori, has been recognized as a class 1 carcinogen and contributes to chronic inflammation within the gastric niche. Genomic analyses have uncovered remarkable coevolution between the human host and H. pylori. Perturbation of this coevolution results in dysregulation of the host-pathogen interaction, leading to oncogenic effects. This review discusses the relationship of H. pylori with the human host and environment and the contribution of each of these factors to disease progression, with an emphasis on features that have been illuminated by genomic tools.

Differential expression of microRNAs in preneoplastic gastric mucosa

Gastric carcinogenesis is a multifactorial H.pylori-triggered dynamic process that goes through a cascade of preneoplastic conditions. The expression of miRNAs in the stomach with regard to preneoplastic precursor conditions and H.pylori infection has not been investigated systematically. In this prospective proof-of-principle study, we evaluated the miRNA expression in gastric antrum and corpus mucosa from patients with chronic non-atrophic gastritis (CNAG), atrophic gastritis (AG), and GC compared to controls. Gastric normal mucosa shows a unique expression pattern for miR-21, miR-155 and miR-223, which is specific for different regions. In correlation with progression of Correa's cascade and H.pylori infection, we observed a gradual increase in miR-155 and miR-223 both in corpus and antrum and miR-21 only in the antrum mucosa. Using miRNA expression we calculated a score that allowed us to discriminate patients with AG from subjects with normal mucosa with high diagnostic accuracy in testing and validation cohorts reproducibly. In summary, the expression pattern of miRNAs in the gastric mucosa is gradually increased with progression of Correa's cascade and H.pylori infection, suggesting miRNAs as potential biomarkers for preneoplastic precursor conditions. However, differences of miRNA expression between the gastric antrum and the corpus need to be considered in future studies.

Reduction of urease activity by interaction with the flap covering the active site

With the increasing appreciation for the human microbiome coupled with the global rise of antibiotic resistant organisms, it is imperative that new methods be developed to specifically target pathogens. To that end, a novel computational approach was devised to identify compounds that reduce the activity of urease, a medically important enzyme of Helicobacter pylori, Proteus mirabilis, and many other microorganisms. Urease contains a flexible loop that covers its active site; Glide was used to identify small molecules predicted to lock this loop in an open conformation. These compounds were screened against the model urease from Klebsiella aerogenes, and the natural products epigallocatechin and quercetin were shown to inhibit at low and high micromolar concentrations, respectively. These molecules exhibit a strong time-dependent inactivation of urease that was not due to their oxygen sensitivity. Rather, these compounds appear to inactivate urease by reacting with a specific Cys residue located on the flexible loop. Substitution of this cysteine by alanine in the C319A variant increased the urease resistance to both epigallocatechin and quercetin, as predicted by the computational studies. Protein dynamics are integral to the function of many enzymes; thus, identification of compounds that lock an enzyme into a single conformation presents a useful approach to define potential inhibitors.

Helicobacter pylori virulence genes and host genetic polymorphisms as risk factors for peptic ulcer disease

Helicobacter pylori infection plays an important role in the pathogenesis of peptic ulcer disease (PUD). Several factors have been proposed as possible H. pylori virulence determinants; for example, bacterial adhesins and gastric inflammation factors are associated with an increased risk of PUD. However, differences in bacterial virulence factors alone cannot explain the opposite ends of the PUD disease spectrum, that is duodenal and gastric ulcers; presumably, both bacterial and host factors contribute to the differential response. Carriers of the high-producer alleles of the pro-inflammatory cytokines IL-1B, IL-6, IL-8, IL-10, and TNF-α who also carry low-producer allele of anti-inflammatory cytokines have severe gastric mucosal inflammation, whereas carriers of the alternative alleles have mild inflammation. Recent reports have suggested that the PSCA and CYP2C19 ultra-rapid metabolizer genotypes are also associated with PUD.

The atypical response regulator HP1021 controls formation of the Helicobacter pylori replication initiation complex

The replication of a bacterial chromosome is initiated by the DnaA protein, which binds to the specific chromosomal region oriC and unwinds duplex DNA within the DNA-unwinding element (DUE). The initiation is tightly regulated by many factors, which control either DnaA or oriC activity and ensure that the chromosome is duplicated only when the conditions favor the survival of daughter cells. The factors controlling oriC activity often belong to the protein families of two-component systems. Here, we found that Helicobacter pylori oriC activity is controlled by HP1021, a member of the atypical response regulator family. HP1021 protein specifically interacts with H. pylori oriC at HP1021 boxes (5'-TGTT[TA]C[TA]-3'), which overlap with three modules important for oriC function: DnaA boxes, the hypersensitivity (hs) region and the DUE. Consequently, HP1021 binding to oriC precludes DnaA-oriC interactions and inhibits DNA unwinding at the DUE. Thus, HP1021 constitutes a negative regulator of the H. pylori orisome assembly in vitro. Furthermore, HP1021 boxes were found upstream of at least 70 genes, including those encoding CagA and Fur proteins. We postulate that HP1021 might coordinate chromosome replication, and thus bacterial growth, with other cellular processes and conditions in the human stomach.

Gastrokine 1 inhibits the carcinogenic potentials of Helicobacter pylori CagA

Helicobacter pylori CagA directly injected by the bacterium into epithelial cells via a type IV secretion system, leads to cellular changes such as morphology, apoptosis, proliferation and cell motility, and stimulates gastric carcinogenesis. We investigated the effects of cytotoxin-associated gene A (CagA) and gastrokine 1 (GKN1) on cell proliferation, apoptosis, reactive oxygen species (ROS) production, epithelial-mesenchymal transition (EMT) and cell migration in CagA- or GKN1-transfected gastric epithelial cells and mucosal tissues from humans and mice infected with H.pylori. On the molecular level, H.pylori CagA induced increased cell proliferation, ROS production, antiapoptotic activity, cell migration and invasion. Moreover, CagA induced activation of NF-κB and PI3K/Akt signaling pathways and EMT-related proteins. In addition, H.pylori CagA reduced GKN1 gene copy number and expression in gastric cells and mucosal tissues of humans and mice. However, GKN1 overexpression successfully suppressed the carcinogenic effects of CagA through binding to CagA. These results suggest that GKN1 might be a target to inhibit the effects from H.pylori CagA.

Evaluating the potential for a Helicobacter pylori drinking water guideline

Helicobacter pylori is a microaerophilic, gram-negative bacterium that is linked to adverse health effects including ulcers and gastrointestinal cancers. The goal of this analysis is to develop the necessary inputs for a quantitative microbial risk assessment (QMRA) needed to develop a potential guideline for drinking water at the point of ingestion (e.g., a maximum contaminant level, or MCL) that would be protective of human health to an acceptable level of risk while considering sources of uncertainty. Using infection and gastric cancer as two discrete endpoints, and calculating dose-response relationships from experimental data on humans and monkeys, we perform both a forward and reverse risk assessment to determine the risk from current reported surface water concentrations of H. pylori and an acceptable concentration of H. pylori at the point of ingestion. This approach represents a synthesis of available information on human exposure to H. pylori via drinking water. A lifetime risk of cancer model suggests that a MCL be set at <1 organism/L given a 5-log removal treatment because we cannot exclude the possibility that current levels of H. pylori in environmental source waters pose a potential public health risk. Research gaps include pathogen occurrence in source and finished water, treatment removal rates, and determination of H. pylori risks from other water sources such as groundwater and recreational water.

Antibacterial Activities of Oxyprenylated Chalcones and Napthtoquinone against Helicobacter pylori

In this study, we synthesized and characterized the antibacterial activity of three naturally occurring oxyprenylated chalcones {xinjiachalcone A (1), (2 E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-(4-hydroxyphenyl)prop-2-en-1-one (2), (2 E)-1-{2,6-dihydroxy-4-[(3-methylbut-2-enyl)oxy]phenyl}-3-phenylprop-2-en-1-one (3), and lawsone 2-isopentenyl ether (4)}. Using several strains of Helicobacter pylori, including clinical ones, minimum inhibitory concentration (MIC) values and bactericidal activities of these compounds were determined. Xinjiachalcone A (1), active principle of Glycyrrhiza inflata Batalin, was the most effective compound, showing both a low MIC and a strong bactericidal activity against H. pylori. This study suggests that these compounds represent potential natural molecules for the prevention and treatment of H. pylori associated diseases.

Circulating mitochondrial DNA level, a noninvasive biomarker for the early detection of gastric cancer

BACKGROUND

Gastric cancer represents a major health burden worldwide and is often diagnosed at an advanced stage. Biomarkers for screening and prevention of gastric cancer are missing. Changes in peripheral blood mitochondrial DNA (mtDNA) have emerged as a potential preventive/diagnosis biomarker for cancer risk. We aimed to determine whether peripheral leukocytes mtDNA levels are associated with stages of the gastric carcinogenesis cascade.

METHODS

We measured mtDNA by quantitative real-time PCR assay in peripheral leukocytes of 28 patients with non-atrophic gastritis (NAG), 74 patients with gastric cancer, and 48 matched asymptomatic controls. In parallel, the serologic level of IL8 was determined.

RESULTS

Mean mtDNA level was higher in patients with gastric cancer (P = 0.0095) than in controls, with values >8.46 significantly associated with gastric cancer (OR, 3.93). Three ranges of mtDNA values were identified: interval I, <2.0; interval II, 2.0-20; and interval III, >20. Interval I included mainly NAG cases, and few gastric cancer samples and interval III corresponded almost exclusively to patients with gastric cancer. All controls fell in interval II, together with some NAG and gastric cancer cases. IL8 levels were significantly higher in patients with gastric cancer (P < 0.05), with levels >50 pg/mL observed exclusively in patients with gastric cancer, allowing to distinguish them within interval II. We validated mtDNA results in a second cohort of patients, confirming that mtDNA was significantly higher in gastric cancer than in patients with preneoplasia.

CONCLUSIONS

Circulating levels of mtDNA and IL8 constitute a potential biomarker for the early detection of gastric cancer.

IMPACT

Our findings lead us to propose a new noninvasive method to detect patients with gastric cancer risk.

Gastroretentive drug delivery systems for the treatment of Helicobacter pylori

Helicobacter pylori (H. pylori) is one of the most common pathogenic bacterial infections and is found in the stomachs of approximately half of the world's population. It is the primary known cause of gastritis, gastroduodenal ulcer disease and gastric cancer. However, combined drug therapy as the general treatment in the clinic, the rise of antibiotic-resistant bacteria, adverse reactions and poor patient compliance are major obstacles to the eradication of H. pylori. Oral site-specific drug delivery systems that could increase the longevity of the treatment agent at the target site might improve the therapeutic effect and avoid side effects. Gastroretentive drug delivery systems potentially prolong the gastric retention time and controlled/sustained release of a drug, thereby increasing the concentration of the drug at the application site, potentially improving its bioavailability and reducing the necessary dosage. Recommended gastroretentive drug delivery systems for enhancing local drug delivery include floating systems, bioadhesive systems and expandable systems. In this review, we summarize the important physiological parameters of the gastrointestinal tract that affect the gastric residence time. We then focus on various aspects useful in the development of gastroretentive drug delivery systems, including current trends and the progress of novel forms, especially with respect to their application for the treatment of H. pylori infections.

Pattern-recognition receptors and gastric cancer

Chronic inflammation has been associated with an increased risk of several human malignancies, a classic example being gastric adenocarcinoma (GC). Development of GC is known to result from infection of the gastric mucosa by Helicobacter pylori, which initially induces acute inflammation and, in a subset of patients, progresses over time to chronic inflammation, gastric atrophy, intestinal metaplasia, dysplasia, and finally intestinal-type GC. Germ-line encoded receptors known as pattern-recognition receptors (PRRs) are critical for generating mature pro-inflammatory cytokines that are crucial for both Th1 and Th2 responses. Given that H. pylori is initially targeted by PRRs, it is conceivable that dysfunction within genes of this arm of the immune system could modulate the host response against H. pylori infection, and subsequently influence the emergence of GC. Current evidence suggests that Toll-like receptors (TLRs) (TLR2, TLR3, TLR4, TLR5, and TLR9), nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) (NOD1, NOD2, and NLRP3), a C-type lectin receptor (DC-SIGN), and retinoic acid-inducible gene (RIG)-I-like receptors (RIG-I and MDA-5), are involved in both the recognition of H. pylori and gastric carcinogenesis. In addition, polymorphisms in genes involved in the TLR (TLR1, TLR2, TLR4, TLR5, TLR9, and CD14) and NLR (NOD1, NOD2, NLRP3, NLRP12, NLRX1, CASP1, ASC, and CARD8) signaling pathways have been shown to modulate the risk of H. pylori infection, gastric precancerous lesions, and/or GC. Further, the modulation of PRRs has been suggested to suppress H. pylori-induced inflammation and enhance GC cell apoptosis, highlighting their potential relevance in GC therapeutics. In this review, we present current advances in our understanding of the role of the TLR and NLR signaling pathways in the pathogenesis of GC, address the involvement of other recently identified PRRs in GC, and discuss the potential implications of PRRs in GC immunotherapy.