Carcinogenic Helicobacter pylori Strains Selectively Dysregulate the In Vivo Gastric Proteome, Which May Be Associated with Stomach Cancer Progression

Genetic Markers of Helicobacter pylori Resistance to Clarithromycin and Levofloxacin in Moscow, Russia

The Maastricht VI/Florence consensus recommends, as one of the measures to enhance the efficacy of Helicobacter pylori infection eradication, a personalized treatment approach involving the selection of an antimicrobial agent based on the pre-determined resistance of H. pylori. To address the need to develop test systems for personalized drug selection, this study was designed to analyze the molecular resistance of H. pylori using a newly developed Sanger sequencing test platform. The characteristics of the test system were determined on 25 pure culture samples of H. pylori with known resistance. Sensitivity and specificity for detecting resistance to clarithromycin was 100% and those to levofloxacin were 93% and 92%, respectively. The test system has been tested in real clinical practice on 112 H. pylori-positive patients who had not previously received proton pump inhibitors (PPIs) or antibacterial drugs. Mutations indicating resistance to clarithromycin were found in 27 (24%) samples and those indicating resistance to levofloxacin were found in 26 (23%) samples. Double resistance was observed in 16 (14%) samples. The most common mutations leading to clarithromycin resistance were 2143G and 2142G and to levofloxacin resistance-261A and 271A in the gyrA gene, which account for 69% of all identified genetic determinants in levofloxacin-resistant bacteria. Thus, a personalized approach to the selection of H. pylori eradication therapy based on the detection of bacterial resistance before prescribing first-line therapy could help to avoid the prescription of ineffective H. pylori eradication therapies and, overall, contribute to the control of antibiotic resistance of H. pylori.

Establishment and Application of a Novel Genetic Detection Panel for SNPs in Mongolian Gerbils

The Mongolian gerbil is a distinctive experimental animal in China, as its genetic qualities possess significant value in the field of medical biology research. Here, we aimed to establish an economical and efficient panel for genetic quality detection in Mongolian gerbils using single-nucleotide polymorphism (SNP) markers. To search for SNPs, we conducted whole-genome sequencing (WGS) in 40 Mongolian gerbils from outbred populations. Reliable screening criteria were established to preliminarily select SNPs with a wide genome distribution and high levels of polymorphism. Subsequently, a multiple-target regional capture detection system based on second-generation sequencing was developed for SNP genotyping. Based on the results of WGS, 219 SNPs were preliminarily selected, and they were established and optimized in a multiple-amplification system that included 206 SNP loci by genotyping three outbred populations. PopGen.32 analysis revealed that the average effective allele number, Shannon index, observed heterozygosity, expected heterozygosity, average heterozygosity, polymorphism information content, and other population genetic parameters of the Capital Medical University (CMU) gerbils were the highest, followed by those of Zhejiang gerbils and Dalian gerbils. Through scientific screening and optimization, we successfully established a novel, robust, and cost-effective genetic detection system for Mongolian gerbils by utilizing SNP markers for the first time.

Targeting hypoxia-inducible factor-1 alpha suppresses Helicobacter pylori-induced gastric injury via attenuation of both cag-mediated microbial virulence and proinflammatory host responses

Helicobacter pylori-induced inflammation is the strongest known risk factor for gastric adenocarcinoma. Hypoxia-inducible factor-1 (HIF-1α) is a key transcriptional regulator of immunity and carcinogenesis. To examine the role of this mediator within the context of H. pylori-induced injury, we first demonstrated that HIF-1α levels were significantly increased in parallel with the severity of gastric lesions in humans. In interventional studies targeting HIF-1α, H. pylori-infected mice were treated ± dimethyloxalylglycine (DMOG), a prolyl hydroxylase inhibitor that stabilizes HIF-1α. H. pylori significantly increased proinflammatory chemokines/cytokines and inflammation in vehicle-treated mice; however, this was significantly attenuated in DMOG-treated mice. DMOG treatment also significantly decreased function of the H. pylori type IV secretion system (T4SS) in vivo and significantly reduced T4SS-mediated NF-κB activation and IL-8 induction in vitro. These results suggest that prolyl hydroxylase inhibition protects against H. pylori-mediated pathologic responses, and is mediated, in part, via attenuation of H. pylori cag-mediated virulence and suppression of host proinflammatory responses.

Transcriptional analysis of Helicobacter pylori cytotoxic-associated gene-pathogenicity island in response to different pH levels and proton pump inhibitor exposure

BACKGROUND

Long-term use of proton pump inhibitors (PPIs) can increase the risk of gastric cancer in Helicobacter pylori-infected patients; nevertheless, there is no data about their impact on the pathogenicity of H. pylori. This study aimed at investigating the transcriptional alteration of key gene mediators of cytotoxin-associated gene-pathogenicity island (cag-PAI) among clinical H. pylori isolates in response to omeprazole at different pH levels.

METHODS

Accordingly, H. pylori isolates with the same virulence genotypes selected from the gastric biopsies of patients and transcriptional alteration in the cag-PAI genes studied in the presence or absence of omeprazole (2 mg/mL) at pH 2.0, 4.0 and 7.0 after 30 and 90 minutes of the treatment. Relative changes in the transcriptional levels were recorded in each assay, separately.

RESULTS

Of 18 H. pylori isolates, the cag-PAI empty site was detected in four strains, while the presence of cagA, cagL and cagY was characterized in 77.7%, 83.3% and 83.3% of the cag-PAI-positive strains, respectively. Transcriptional analysis of the selected strains showed up-regulation of cagA and cagL, mainly at pH 2.0 and 4.0 after 30 and 90-minute exposure. A diversity in the expression levels of cag-PAI genes was seen among the strains at the extent and time of induction.

CONCLUSION

Our results showed that omeprazole could increase the expression of H. pylori cagA and cagL at acidic pH. Heterogeneity among the strains probably has an impact on the extent of their interplay with PPIs. Further studies are needed to establish this correlation.

Helicobacter pylori Antibiotic Resistance: Molecular Basis and Diagnostic Methods

Helicobacter pylori is one of the most common cause of human infections. Infected patients develop chronic active gastritis in all cases, which can lead to peptic ulcer, atrophic gastritis, gastric cancer and gastric MALT-lymphoma. The prevalence of H. pylori infection in the population has regional characteristics and can reach 80%. Constantly increasing antibiotic resistance of H. pylori is a major cause of treatment failure and a major problem. According to the VI Maastricht Consensus, two main strategies for choosing eradication therapy are recommended: individualized based on evaluating sensitivity to antibacterial drugs (phenotypic or molecular genetic method) prior to their appointment, and empirical, which takes into account data on local H. pylori resistance to clarithromycin and monitoring effectiveness schemes in the region. Therefore, the determination of H. pylori resistance to antibiotics, especially clarithromycin, prior to choosing therapeutic strategy is extremely important for the implementation of these treatment regimens.

A comprehensive evaluation of an animal model for Helicobacter pylori-associated stomach cancer: Fact and controversy

Even though Helicobacter pylori infection was the most causative factor of gastric cancer, numerous in vivo studies failed to induce gastric cancer using H. pylori infection only. The utilization of established animal studies in cancer research is crucial as they aim to investigate the coincidental association between suspected oncogenes and pathogenesis as well as generate models for the development and testing of potential treatments. The methods to establish gastric cancer using infected animal models remain limited, diverse in methods, and showed different results. This study investigates the differences in animal models, which highlight different pathological results in gaster by literature research. Electronic databases searched were performed in PubMed, Science Direct, and Cochrane, without a period filter. A total of 135 articles were used in this study after a full-text assessment was conducted. The most frequent animal models used for gastric cancer were Mice, while Mongolian gerbils and Transgenic mice were the most susceptible model for gastric cancer associated with H. pylori infection. Additionally, transgenic mice showed that the susceptibility to gastric cancer progression was due to genetic and epigenetic factors. These studies showed that in Mongolian gerbil models, H. pylori could function as a single agent to trigger stomach cancer. However, most gastric cancer susceptibilities were not solely relying on H. pylori infection, and numerous factors are involved in cancer progression. Further study using Mongolian gerbils and Transgenic mice is crucial to conduct and establish the best models for gastric cancer associated H. pylori.

Clinical Pathogenesis, Molecular Mechanisms of Gastric Cancer Development

The human pathogen Helicobacter pylori is the strongest known risk factor for gastric disease and cancer, and gastric cancer remains a leading cause of cancer-related death across the globe. Carcinogenic mechanisms associated with H. pylori are multifactorial and are driven by bacterial virulence constituents, host immune responses, environmental factors such as iron and salt, and the microbiota. Infection with strains that harbor the cytotoxin-associated genes (cag) pathogenicity island, which encodes a type IV secretion system (T4SS) confer increased risk for developing more severe gastric diseases. Other important H. pylori virulence factors that augment disease progression include vacuolating cytotoxin A (VacA), specifically type s1m1 vacA alleles, serine protease HtrA, and the outer-membrane adhesins HopQ, BabA, SabA and OipA. Additional risk factors for gastric cancer include dietary factors such as diets that are high in salt or low in iron, H. pylori-induced perturbations of the gastric microbiome, host genetic polymorphisms, and infection with Epstein-Barr virus. This chapter discusses in detail host factors and how H. pylori virulence factors augment the risk of developing gastric cancer in human patients as well as how the Mongolian gerbil model has been used to define mechanisms of H. pylori-induced inflammation and cancer.

Characterization of the interactome profiling of Mycoplasma fermentans DnaK in cancer cells reveals interference with key cellular pathways

Chaperone proteins are redundant in nature and, to achieve their function, they bind a large repertoire of client proteins. DnaK is a bacterial chaperone protein that recognizes misfolded and aggregated proteins and drives their folding and intracellular trafficking. Some Mycoplasmas are associated with cancers, and we demonstrated that infection with a strain of Mycoplasma fermentans isolated in our lab promoted lymphoma in a mouse model. Its DnaK is expressed intracellularly in infected cells, it interacts with key proteins to hamper essential pathways related to DNA repair and p53 functions and uninfected cells can take-up extracellular DnaK. We profile here for the first time the eukaryotic proteins interacting with DnaK transiently expressed in five cancer cell lines. A total of 520 eukaryotic proteins were isolated by immunoprecipitation and identified by Liquid Chromatography Mass Spectrometry (LC-MS) analysis. Among the cellular DnaK-binding partners, 49 were shared between the five analyzed cell lines, corroborating the specificity of the interaction of DnaK with these proteins. Enrichment analysis revealed multiple RNA biological processes, DNA repair, chromatin remodeling, DNA conformational changes, protein-DNA complex subunit organization, telomere organization and cell cycle as the most significant ontology terms. This is the first study to show that a bacterial chaperone protein interacts with key eukaryotic components thus suggesting DnaK could become a perturbing hub for the functions of important cellular pathways. Given the close interactions between bacteria and host cells in the local microenvironment, these results provide a foundation for future mechanistic studies on how bacteria interfere with essential cellular processes.

CagA and VacA inhibit gastric mucosal epithelial cell autophagy and promote the progression of gastric precancerous lesions

Cytotoxin-associated gene A (CagA) and vacuolating cytotoxin A (VacA) are the keys to the pathogenic role of Helicobacter pylori and the high-risk factors for the progression of gastric precancerous lesions. Autophagy can stabilize the intracellular environment, resist Helicobacter pylori infection, prevent the accumulation of damaged DNA, and inhibit the proliferation of gastric precancerous variant cells. However, CagA and VacA can inhibit the activation of upstream signals of autophagy and the maturation of autophagy-lysosomes in various ways, thus inhibiting the autophagy of gastric mucosal cells in precancerous lesions of gastric cancer. This change can cause Helicobacter pylori to be unable to be effectively cleared by autophagy, so CagA and VacA can persist and promote the inflammation, oxidative stress, apoptosis of gastric mucosal tissue cells, and the glycolytic activity and proliferation of variant cells in gastric precancerous lesions and a series of malignant biological processes. In recent years, the research on drugs specifically inhibiting the activities of CagA and VacA has become a new direction for the prevention and treatment of Helicobacter pylori-related severe gastric diseases, and a variety of drugs or components that can precisely and effectively regulate the factors for the treatment of gastric precancerous lesions are emerged, which opens a new strategy for the treatment of gastric precancerous lesions in the future.

Animal Models and Helicobacter pylori Infection

Helicobacter pylori colonize the gastric mucosa of at least half of the world’s population. Persistent infection is associated with the development of gastritis, peptic ulcer disease, and an increased risk of gastric cancer and gastric-mucosa-associated lymphoid tissue (MALT) lymphoma. In vivo studies using several animal models have provided crucial evidence for understanding the pathophysiology of H. pylori-associated complications. Numerous animal models, such as Mongolian gerbils, transgenic mouse models, guinea pigs, and other animals, including non-human primates, are being widely used due to their persistent association in causing gastric complications. However, finding suitable animal models for in vivo experimentation to understand the pathophysiology of gastric cancer and MALT lymphoma is a complicated task. In this review, we summarized the most appropriate and latest information in the scientific literature to understand the role and importance of H. pylori infection animal models.

Iron deficiency linked to altered bile acid metabolism promotes Helicobacter pylori-induced inflammation-driven gastric carcinogenesis

Gastric carcinogenesis is mediated by complex interactions among Helicobacter pylori, host, and environmental factors. Here, we demonstrate that H. pylori augmented gastric injury in INS-GAS mice under iron-deficient conditions. Mechanistically, these phenotypes were not driven by alterations in the gastric microbiota; however, discovery-based and targeted metabolomics revealed that bile acids were significantly altered in H. pylori-infected mice with iron deficiency, with significant upregulation of deoxycholic acid (DCA), a carcinogenic bile acid. The severity of gastric injury was further augmented when H. pylori-infected mice were treated with DCA, and, in vitro, DCA increased translocation of the H. pylori oncoprotein CagA into host cells. Conversely, bile acid sequestration attenuated H. pylori-induced injury under conditions of iron deficiency. To translate these findings to human populations, we evaluated the association between bile acid sequestrant use and gastric cancer risk in a large human cohort. Among 416,885 individuals, a significant dose-dependent reduction in risk was associated with cumulative bile acid sequestrant use. Further, expression of the bile acid receptor transmembrane G protein-coupled bile acid receptor 5 (TGR5) paralleled the severity of carcinogenic lesions in humans. These data demonstrate that increased H. pylori-induced injury within the context of iron deficiency is tightly linked to altered bile acid metabolism, which may promote gastric carcinogenesis.

Racial Differences in Helicobacter pylori Prevalence in the US: A Systematic Review

BACKGROUND AND AIMS:

Helicobacter pylori remains an important risk factor for noncardia gastric cancer and a spectrum of disease from H. pylori infection to gastric cancer. As a step toward improved clinical strategies for gastric cancer prevention, we assessed racial differences in prevalence of H. pylori from studies across the United States. This systematic review provides a comprehensive evaluation of the literature regarding racial differences in H. pylori in the United States.

METHODS:

MEDLINE, Embase, and Web of Science database searches were performed through May 26, 2021. Ultimately, 25 studies that reported H. pylori infection prevalence by race were included.

RESULTS:

All studies included in the review documented higher H. pylori prevalence in Blacks and Hispanics than in whites. The ratio of H. pylori prevalence for Blacks compared to non-Hispanic whites ranged from 1.3 to 5.4, and the ratio for Hispanics compared to non-Hispanic whites ranged from 1.8 to 4.4. Of the 5 studies that examined H. pylori CagA prevalence by race, 4 found higher prevalence among Blacks and Hispanics compared to whites, with CagA prevalence ranging from 19% to 77% in whites, 62% to 90% in Blacks, and 64% to 74% in Hispanics.

CONCLUSION:

In this review, across 25 studies, varying in underlying population, time period, and geographic location, Blacks and Hispanics appeared to have a higher prevalence of H. pylori infection than whites. This increased prevalence of H. pylori among populations also at a higher risk of gastric cancer is relevant in the clinical setting for decision-making related to H. pylori testing and gastric cancer prevention.

Role of Bacterial and Viral Pathogens in Gastric Carcinogenesis

Simple Summary

Stomach cancer is one of the most common cancers in the world, with over one million new cases diagnosed in 2020. Despite recent advances in cancer treatments, gastric cancer remains a serious clinical problem. This disease is tightly linked to gastric infections with Helicobacter pylori bacterium, Epstein–Barr virus, and some other less known pathogens. Here, we discuss how gastric pathogens induce tumorigenic changes in the stomach.

Abstract

Gastric cancer (GC) is one of the deadliest malignancies worldwide. In contrast to many other tumor types, gastric carcinogenesis is tightly linked to infectious events. Infections with Helicobacter pylori (H. pylori) bacterium and Epstein–Barr virus (EBV) are the two most investigated risk factors for GC. These pathogens infect more than half of the world’s population. Fortunately, only a small fraction of infected individuals develops GC, suggesting high complexity of tumorigenic processes in the human stomach. Recent studies suggest that the multifaceted interplay between microbial, environmental, and host genetic factors underlies gastric tumorigenesis. Many aspects of these interactions still remain unclear. In this review, we update on recent discoveries, focusing on the roles of various gastric pathogens and gastric microbiome in tumorigenesis.

Hypusination Orchestrates the Antimicrobial Response of Macrophages

Innate responses of myeloid cells defend against pathogenic bacteria via inducible effectors. Deoxyhypusine synthase (DHPS) catalyzes the transfer of the N-moiety of spermidine to the lysine-50 residue of eukaryotic translation initiation factor 5A (EIF5A) to form the amino acid hypusine. Hypusinated EIF5A (EIF5A^Hyp) transports specific mRNAs to ribosomes for translation. We show that DHPS is induced in macrophages by two gastrointestinal pathogens, Helicobacter pylori and Citrobacter rodentium, resulting in enhanced hypusination of EIF5A. EIF5A^Hyp was also increased in gastric macrophages from patients with H. pylori gastritis. Furthermore, we identify the bacteria-induced immune effectors regulated by hypusination. This set of proteins includes essential constituents of antimicrobial response and autophagy. Mice with myeloid cell-specific deletion of Dhps exhibit reduced EIF5A^Hyp in macrophages and increased bacterial burden and inflammation. Thus, regulation of translation through hypusination is a critical hallmark of the defense of eukaryotic hosts against pathogenic bacteria.

Gobert et al. demonstrate that hypusination, a specific mechanism regulating translation, is induced in macrophages by bacteria. Hypusination is required for the translation of inducible antimicrobial effectors. Mice that specifically lack hypusination in macrophages are highly susceptible to Helicobacter pylori and Citrobacter rodentium, two pathogens of the gastrointestinal tract.

Serum proteome profiling reveals SOX3 as a candidate prognostic marker for gastric cancer

Searching for the novel tumour biomarkers is pressing for gastric cancer diagnostication and prognostication. The serum specimens from patients diagnosed with locally advanced gastric carcinoma before operation and 4 week after surgery were collected, respectively, and serum proteome profiling was conducted by liquid chromatography–mass spectrometry (MS)/MS. Fifty‐five proteins were identified to be up‐regulated and 16 proteins were down‐regulated, and these differentially expressed proteins participated in various biological processes. Serum levels of SOX3, one of down‐regulated proteins, in stomach cancer patients were higher than in healthy controls. SOX3 levels in cancer tissues were remarkably related to tumour differentiation, lymph node metastasis, primary tumour invasion and pTNM (pathological TNM) stage. Analysis with The Cancer Genome Atlas database indicated that SOX3 level and pTNM stage were the independent risk factors for the patient survival and that the overall survival was negatively associated with the SOX3 levels. Loss‐of‐function showed that SOX3 promoted gastric cancer cell invasion and migration in vitro and in vivo. SOX3 silence inhibits the expression of MMP9, and SOX3 is responsible for MMP9 expression transcriptionally. Our study highlights the potentiality of the paired pre‐ and post‐operation serum proteome signatures for the detection of biomarkers and reveals that SOX3 may serve as a candidate prognosis marker for gastric cancer.

Quantitative proteomics analysis of differentially expressed proteins induced by astragaloside IV in cervical cancer cell invasion

Background

Cervical cancer remains the second leading cause of mortality in women in developing countries. While surgery, chemotherapy, radiotherapy, and vaccine therapy are being applied for its treatment, individually or in combination, the survival rate in advanced cervical cancer patients is still very low. Traditional Chinese medicine has been found to be effective in the treatment of cervical cancer. Astragaloside IV (AS-IV), a compound belonging to Astragalus polysaccharides, shows anticancer activity through several cell signaling pathways. However, the detailed molecular mechanism governing the anticancer activity of AS-IV remains unknown.

Material and methods

In our study, we performed tumor xenograft analysis, transwell cell migration and invasion assay, Western blot analysis, and iTRAQ combination by parallel reaction monitoring (PRM) analysis to study the molecular mechanism of AS-IV in the suppression of cervical cancer cell invasion.

Results

Our results showed that AS-IV suppressed cervical cancer cell invasion and induced autophagy in them, with the tumor growth curve increasing slowly. We also identified 32 proteins that were differentially expressed in the SiHa cells when treated with AS-IV, with 16 of them involved in the upregulation and 16 in the downregulation of these cells. These differentially expressed proteins, which were predominantly actin–myosin complexes, controlled cell proliferation and cell development by steroid binding and altering the composition of the cell cytoskeleton. DCP1A and TMSB4X, the two proteins regulating autophagy, increased in cervical cancer cells when treated with AS-IV.

Conclusions

We conclude that AS-IV could inhibit cervical cancer invasion by inducing autophagy in cervical cancer cells. Since iTRAQ combination by PRM has been observed to be useful in identifying macromolecular target compounds, it may be considered as a novel strategy in the screening of anticancer compounds used in the treatment of cervical cancer.

UHMK1 promotes gastric cancer progression through reprogramming nucleotide metabolism

UHMK1 is a nuclear serine/threonine kinase recently implicated in carcinogenesis. However, the functions and action mechanisms of UHMK1 in the pathogenesis of human gastric cancer (GC) are unclear. Here, we observed that UHMK1 was markedly upregulated in GC. UHMK1 silencing strongly inhibited GC aggressiveness. Interestingly, UHMK1-induced GC progression was mediated primarily via enhancing de novo purine synthesis because inhibiting purine synthesis reversed the effects of UHMK1 overexpression. Mechanistically, UHMK1 activated ATF4, an important transcription factor in nucleotide synthesis, by phosphorylating NCOA3 at Ser (S) 1062 and Thr (T) 1067. This event significantly enhanced the binding of NCOA3 to ATF4 and the expression of purine metabolism-associated target genes. Conversely, deficient phosphorylation of NCOA3 at S1062/T1067 significantly abrogated the function of UHMK1 in GC development. Clinically, Helicobacter pylori and GC-associated UHMK1 mutation induced NCOA3-S1062/T1067 phosphorylation and enhanced the activity of ATF4 and UHMK1. Importantly, the level of UHMK1 was significantly correlated with the level of phospho-NCOA3 (S1062/T1067) in human GC specimens. Collectively, these results show that the UHMK1-activated de novo purine synthesis pathway significantly promotes GC development.

iTRAQ-based quantitative proteomic analysis of the inhibition of cervical cancer cell invasion and migration by metformin

In recent years the anti-diabetic drug metformin has been shown to inhibit tumor growth, but the underlying mechanism is unclear. Our previous results showed that metformin can destroy the sponge effect of long-chain non-coding RNA MALAT1/miR-142-3p and inhibit the proliferation of cervical cancer cells. Metformin can inhibit the PI3K/Akt signaling pathway and synergizes with Nelfinavir to inhibit the proliferation and invasion of cervical cancer cells. In this study, we used iTRAQ-based proteomics, mass spectrometry-based targeted proteomics, immunoblotting, and bioinformatics to analyze the molecular mechanism by which metformin inhibits the proliferation and invasion of cervical cancer cells. We found that 53 proteins were differentially expressed in cervical cancer cells after metformin treatment, of which 20 were up-regulated and 33 were down-regulated. Bioinformatics analysis showed that the 53 differentially expressed proteins are negative regulators of receptor signaling that inhibit cell growth and are mainly enriched in cell growth and apoptosis signaling pathways. We performed PRM verification on 11 of the differentially expressed proteins and found that they were all associated with apoptosis. We also found that metformin up-regulated the expression of the tumor suppressor IGFBP7 to inhibit the proliferation and invasion of cervical cancer cells. Our results indicate that metformin mainly regulates the insulin signaling pathway and interferes with cell proliferation and apoptosis to inhibit proliferation and invasion of cervical cancer cells. These differentially expressed proteins may become new targets for the treatment of cervical cancer.

Review: Pathogenesis of Helicobacter pylori infection

In this review, we shall focus on the last year progression understanding the pathogenesis of Helicobacter pylori infection in the light of recent data related to adaptation of H pylori to the harsh acidic environment in the stomach, colonization of gastric mucosa via interaction with mucin 5 (MUC5AC) and other host cell receptors, the ability to form biofilm, interference with the host metabolic pathways, and induction of neuroimmune cross-talk as well as downregulation of gastric barrier homeostasis and its consequences for the disease development. The role of the membrane vesicles of these bacteria has been emphasized as an important source of virulence factors. Furthermore, we shall describe molecular and functional studies on new aspects of VacA and CagA virulence, including the role of urease in the upregulation of VacA toxicity, an epithelial-mesenchymal transition mediated by CagA, and the role of interaction of HopQ adhesin with carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) in CagA translocation into the host cells by the type IV secretion system (T4SS). The role of molecular mimicry between a common sequence (ATVLA) of H pylori heat shock protein (Hsp) B and human Hsp60 in the induction of potentially autoreactive antibodies is discussed. All these new data illustrate further progress in understanding H pylori pathogenicity and facilitate the search for new therapeutic targets as well as development of immunoprophylaxis methods based on new chimeric UreB and HpA proteins.