Pathogenesis of Helicobacter pylori infection

Helicobacter pylori infection

Helicobacter pylori infection causes chronic gastritis, which can progress to severe gastroduodenal pathologies, including peptic ulcer, gastric cancer and gastric mucosa-associated lymphoid tissue lymphoma. H. pylori is usually transmitted in childhood and persists for life if untreated. The infection affects around half of the population in the world but prevalence varies according to location and sanitation standards. H. pylori has unique properties to colonize gastric epithelium in an acidic environment. The pathophysiology of H. pylori infection is dependent on complex bacterial virulence mechanisms and their interaction with the host immune system and environmental factors, resulting in distinct gastritis phenotypes that determine possible progression to different gastroduodenal pathologies. The causative role of H. pylori infection in gastric cancer development presents the opportunity for preventive screen-and-treat strategies. Invasive, endoscopy-based and non-invasive methods, including breath, stool and serological tests, are used in the diagnosis of H. pylori infection. Their use depends on the specific individual patient history and local availability. H. pylori treatment consists of a strong acid suppressant in various combinations with antibiotics and/or bismuth. The dramatic increase in resistance to key antibiotics used in H. pylori eradication demands antibiotic susceptibility testing, surveillance of resistance and antibiotic stewardship.

Bioactive components of Banxia Xiexin Decoction for the treatment of gastrointestinal diseases based on flavor-oriented analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Banxia Xiexin Decoction (BXD) was first recorded in a Chinese medical classic, Treatise on Febrile Diseases and Miscellaneous Diseases, which was written in the Eastern Han dynasty of China. This ancient prescription consists of seven kinds of Chinese herbal medicine, namely, Pinellia ternata, Rhizoma Coptidis, Radix scutellariae, Rhizoma Zingiberis, Ginseng, Jujube, and Radix Glycyrrhizaepreparata. In clinic practice, its original application in China mainly has focused on the treatment of chronic gastritis for several hundred years. BXD is also effective in treating other gastrointestinal diseases (GIDs) in modern medical application. Despite available literature support and clinical experience, the treatment mechanisms or their relationships with the bioactive compounds in BXD responsible for its pharmacological actions, still need further explorations in more diversified channels. According to the analysis based on the five-flavor theory of TCM, BXD is traditionally viewed as the most representative prescription for pungent-dispersion, bitter-purgation and sweet-tonification. Consequently, based on the flavor-oriented analysis, the compositive herbs in BXD can be divided into three flavor groups, namely, the pungent, bitter, and sweet groups, each of which has specific active ingredients that are possibly relevant to GID treatment.

AIM OF THE REVIEW

This paper summarized recent literatures on BXD and its bioactive components used in GID treatment, and provided the pharmacological or chemical basis for the further exploration of the ancient prescription and the relative components.

METHOD

ology: Relevant literature was collected from various electronic databases such as Pubmed, Web of Science, and China National Knowledge Infrastructure (CNKI). Citations were based on peer-reviewed articles published in English or Chinese during the last decade.

RESULTS

Multiple components were found in the pungent, bitter, and sweet groups in BXD. The corresponding bioactive components include gingerol, shogaol, stigmasterol, and β-sitosterol in the pungent group; berberine, palmatine, coptisine, baicalein, and baicalin in the bitter group; and ginsenosides, polysaccharides, liquiritin, and glycyrrhetinic acid in the sweet group. These components have been found directly or indirectly responsible for the remarkable effects of BXD on GID.

CONCLUSION

This review provided some valuable reference to further clarify BXD treatment for GID and their possible material basis, based on the perspective of the flavor-oriented analysis.

Helicobacter pylori: Commensal, symbiont or pathogen?

This review considers the data on Helicobacter pylori (H. pylori), which have been accumulated over 40 years since its description as an etiological factor in gastrointestinal diseases. The majority of modern publications are devoted to the study of the pathogenic properties of the microorganism in the development of chronic gastritis, peptic ulcer disease, and gastric cancer, as well as methods for its eradication. However, in recent years, there have been more and more studies which have suggested that H. pylori has a beneficial, or potentially positive, effect on the human body. The authors have attempted to objectively analyze the information accumulated in the literature on H. pylori. Some studies consider it as one of the recently identified human bacterial pathogens, and special attention is paid to the evidence suggesting that it is probably part of the composition of the human microbiome as a commensal (commensal from French to English is a table companion) or even a symbiont. The presented data discussing the presence or absence of the effect of H. pylori on human health suggest that there is an apparent ambiguity of the problem. The re-assessment of the data available on H. pylori infection is important in order to answer the question of whether it is necessary to create a program of mass H. pylori eradication or to apply a more personalized approach to treating patients with H. pylori-associated gastrointestinal diseases and to perform eradication therapy.

Metal homeostasis in pathogenic Epsilonproteobacteria: mechanisms of acquisition, efflux, and regulation

Epsilonproteobacteria are a diverse class of eubacteria within the Proteobacteria phylum that includes environmental sulfur-reducing bacteria and the human pathogens, Campylobacter jejuni and Helicobacter pylori. These pathogens infect and proliferate within the gastrointestinal tracts of multiple animal hosts, including humans, and cause a variety of disease outcomes. While infection of these hosts provides nutrients for the pathogenic Epsilonproteobacteria, many hosts have evolved a variety of strategies to either sequester metals from the invading pathogen or exploit the toxicity of metals and drive their accumulation as an antimicrobial strategy. As a result, C. jejuni and H. pylori have developed mechanisms to sense changes in metal availability and regulate their physiology in order to respond to either metal limitation or accumulation. In this review, we will discuss the challenges of metal availability at the host-pathogen interface during infection with C. jejuni and H. pylori and describe what is currently known about how these organisms alter their gene expression and/or deploy bacterial virulence factors in response to these environments.

N-terminal region of Helicobacter pylori CagA induces IL-8 production in gastric epithelial cells via the β1 integrin receptor

Introduction. Helicobacter pylori is associated with gastrointestinal disease, most notably gastric cancer. Cytotoxin-associated antigen A (CagA), an important virulence factor for H. pylori pathogenicity, induces host cells to release inflammatory factors, especially interleukin-8 (IL-8). The mechanism by which C-terminal CagA induces IL-8 production has been studied extensively, but little is known about the role of the N-terminus.

Aim. To investigate the effect of CagA303–456aa (a peptide in the N-terminal CagA) on IL-8 production by gastric epithelial cells.

Methodology. CagA303-456aa was produced by a prokaryotic expression system and purified by Strep-tag affinity chromatography. An integrin β1 (ITGB1)-deficient AGS cell line was constructed using the CRISPR/Cas9 technique, and NCTC 11637 cagA and/or cagL knockout mutants were constructed via homologous recombination. The levels of IL-8 production were determined by enzyme-linked immunosorbent assay (ELISA), and p38 and ERK1/2 phosphorylation were examined by Western blot.

Results. CagA303-456aa induced IL-8 expression by AGS cells. IL-8 induction by CagA303-456aawas specifically inhibited by ITGB1 deficiency. Notably, CagA303-456aa activated the phosphorylation of both p38 and ERK1/2, and blocking p38 and ERK1/2 activity significantly reduced IL-8 induction by CagA303-456aa. ITGB1 deficiency also inhibited the activation of p38 phosphorylation by CagA303-456aa. Finally, experiments in CagA and/or CagL knockout bacterial lines demonstrated that extracellular CagA might induce IL-8 production by AGS cells.

Conclusion. Residues 303–456 of the N-terminal region of CagA induce IL-8 production via a CagA303-456–ITGB1–p38–IL-8 pathway, and ERK1/2 is also involved in the release of IL-8. Extracellular CagA might induce IL-8 production before translocation into AGS cells.

Investigation on the role of gene hp0788 in Helicobacter pylori in infecting gastric epithelial cells

Helicobacter pylori infection can cause a wide range of digestive diseases. Gene hp0788 encodes an outer membrane protein HofF, which can reduce the bacterial adherence to the GES-1 cells and affect pathogenesis of H. pylori. In this study, the role of hp0788 in H. pylori infection was further analyzed. RNA-seq data showed that two genes (hp0523 and hp0539), located on the cagPAI, were down-regulated in Δ0788 mutant. The changes were confirmed through qRT-PCR, and the expression of these two genes will be almost recovered to the normal level in complemented strain. These two genes, hp0523 and hp0539, are known to be necessary for integrated T4SS, which related to CagA translocation and IL-8 induction. In H. pylori infected assay, lower amount of phosphorylated CagA and lower induction of IL-8 were both detected in GES-1 cells infected by Δ0788 mutant, compared with the wild type strain. Meanwhile, these reductions almost recovered to the wild-type level in complemented strain. These results reveal that there is a correlation between hp0788 disruption and CagA/IL-8 decline. Deletion of CagA-encoding gene (hp0547) in Δ0788 mutant was further constructed. The double deleted mutant shows lower IL-8-inducing capability than Δ0788 mutant, indicated the correlation between deficiency of CagA and reduced IL-8 production. These results together imply that disruption of hp0788 might affect the efficiency of T4SS and CagA injection, then weaken the induction of IL-8 in infected GES-1 cells.

Characterization of gastric cells infection by diverse Helicobacter pylori strains through Fourier-transform infrared spectroscopy

The infection of Helicobacter pylori, covering 50% of the world-population, leads to diverse gastric diseases as ulcers and cancer along the life-time of the human host. To promote the discovery of biomarkers of bacterial infection, in the present work, Fourier-transform infrared spectra were acquired from adenocarcinoma gastric cells, incubated with H. pylori strains presenting different genotypes concerning the virulent factors cytotoxin associated gene A and vacuolating cytotoxin A. Defined absorbance ratios were evaluated by diverse methods of statistical inference, according to the fulfillment of the tests assumptions. It was possible to define from the gastric cells, diverse absorbance ratios enabling to discriminate: i) The infection; ii) the bacteria genotype; and iii) the gastric disease of the patients from which the bacteria were isolated. These biomarkers could fasten the knowledge of the complex infection process while promoting a platform for a new diagnostic method, rapid but also specific and sensitive towards the diagnosis of both infection and bacterial virulence.

Prevalence of Helicobacter pylori and its CagA subtypes in gastric cancer and duodenal ulcer at an Austrian tertiary referral center over 25 years

Background and aims

The prevalence of Helicobacter pylori (H. pylori) tends to be lower in Western countries such as central Europe compared with Asia. The virulence of H. pylori is influenced by its subtype composition, most importantly by the presence or absence of different types of cytotoxin-associated gene A(CagA). This study aimed to assess the prevalence of H. pylori and its respective CagA phenotype in a large retrospective cohort of patients with gastric cancer or duodenal ulcer at a Western tertiary referral institution.

Methods

H. pylori positive gastric biopsy samples from patients diagnosed with the afore mentioned diseases within the past 25 years were re-evaluated by histology for H. pylori and status of gastritis. Confirmed H. pylori positive cases were processed for immunohistochemistry (IHC) for H. pylori,CagA, and EastAsiantype CagA.

Results

The prevalence of H. pylori positive gastric biopsy samples decreased from 20.7% to 2.3% within the study period. Among the gastric cancer patients, the H. pylori positive rate was 16.6%, and didn’t show significant changes over time (p = 0.38). Contrary, the H. pylori positive rate of duodenal ulcer decreased significantlyfrom 40% to 5% (p = 0.01). Within H. pylori positive groups ofboth diseases, CagA was highly detected at IHC (86% and 78%, respectively). Except for a few patients originating from East Asian countries, all CagA detected in this study were of Western type.

Conclusion

In this first Western investigation on the chronological prevalence of H. pylori and its most relevant subtypes, Western type of CagA was highly detected in two important index diseases of the pathogen. This raises further questions about the virulence of this subtype.

Systematic identification of immunodominant CD4+ T cell responses to HpaA in Helicobacter pylori infected individuals

In mice, antigen-specific CD4⁺ T cell response is indispensible for the protective immunity against Helicobacter pylori (H. pylori). It has been demonstrated that neuraminyllactose-binding hemagglutinin (HpaA) immunization protected mice from H. pylori infection in a CD4⁺ T cell dependent manner. However, much remains unclear concerning the human CD4⁺ T cell responses to HpaA. We conducted a systematic study here to explore the immunodominant, HpaA-specific CD4⁺ T cell responses in H. pylori infected individuals. We found that HpaA-specific CD4⁺ T cell responses varied remarkably in their magnitude and had broad epitope-specificity. Importantly, the main responses focused on two regions: HpaA76-105 and HpaA130-159. The HLA-DRB1*0901 restricted HpaA142-159 specific CD4⁺ T cell response was the most immunodominant response at a population level. The immunodominant epitope HpaA142-159 was naturally presented and highly conserved. We also demonstrated that it was not the broad peptide specificity, but the strength of HpaA specific CD4⁺ T cell responses associated with gastric diseases potentially caused by H. pylori infection. Such investigation will aid development of novel vaccines against H. pylori infection.

Helicobacter pylori moderates the association between 5-MTHF concentration and cognitive function in older adults

Objective

To explore potential interactions between folate-cycle factors and Helicobacter pylori seropositivity in the prediction of cognitive function.

Methods

We used data obtained from the 1999–2000 continuous National Health and Nutrition Examination Survey produced by the United States’ Centers for Disease Control and Prevention. Using Ordinary Least Squares regression, we tested for associations between multiple folate-cycle factors, Helicobacter pylori seropositivity, and cognitive function assessed by the digit symbol coding subtest of the Wechsler Adult Intelligence Scale-III. We then tested for interactions between each of the folate-cycle factors and Helicobacter pylori in the prediction of cognitive function.

Results

Although Helicobacter pylori seropositivity, 5-methyltetrahydrofolate, vitamin B-12, and homocysteine were not associated with performance on the digit symbol coding task, Helicobacter pylori seropositivity interacted with 5-methyltetrahydrofolate concentration to predict performance on the digit symbol coding task. The Helicobacter pylori seropositive group performed worse on the digit symbol coding task as 5-methyltetrahydrofolate concentration decreased.

Conclusion

The interaction between Helicobacter pylori seropositivity and reduced folate-cycle factor 5-methyltetrahydrofolate might impair aspects of cognitive function.

Eudesmin attenuates Helicobacter pylori-induced epithelial autophagy and apoptosis and leads to eradication of H. pylori infection

Eudesmin has been proven to possess anti-inflammatory effects. In the present study, the effects of eudesmin on Helicobacter pylori (H. pylori)-mediated autophagy, apoptosis, immune response and inflammation were determined in human gastric adenocarcinoma (AGS) cells in vitro and in C57BL/6 mice in vivo. Detection of the production of interleukin (IL)-8, IL-1β and immunoglobulin M (IgM) was performed using ELISA. Identification of the activation of apoptosis-associated caspase-3, -8 and -9 proteins, Bcl-2-associated X protein (Bax) and BH3 interacting domain death agonist (Bid) protein, was determined through western blot analysis. Autophagy microtubule-associated protein 1A/1B-light chain 3, isoform B (LC-3B) expression was measured using immunostaining. The results of the present study demonstrated that eudesmin inhibited the growth of H. pylori, with increased inhibition activity against antibiotic resistant strains compared with the reference strain. In addition, H. pylori-induced IL-8 secretion, LC-3B expression and apoptosis-associated protein (caspase-3, -8 and -9, Bax and Bid) activation in AGS cells was suppressed by eudesmin. Furthermore, eudesmin suppressed IL-1β and IgM production in H. pylori-infected C57BL/6 mice in vivo. In conclusion, eudesmin may be developed as a promising therapeutic agent to prevent and/or treat H. pylori-associated gastric inflammation.

Diagnosis and Assessment of Microbial Infections with Host and Microbial MicroRNA Profiles

MicroRNAs (miRNAs) encoded by viral genome or host have been found participating in host-microbe interactions. Differential expression profiles of miRNAs were shown linking to specific disease pathologies which indicated its potency as diagnostic/prognostic biomarkers of infectious disease. This was emphasized by the discovery of circulating miRNAs which were found to be remarkably stable in mammalian biofluids. Standardized methods of miRNA quantification including RNA isolation should be established before they will be ready for use in clinical practice.

Application of FLP-FRT System to Construct Unmarked Deletion in Helicobacter pylori and Functional Study of Gene hp0788 in Pathogenesis

Helicobacter pylori is a Gram-negative, microaerophilic bacterium associated with human gastric diseases. Further investigations on virulence genes are still required to clarify the pathogenic mechanism of H. pylori and the heterogeneous problem of infection. In order to develop an efficient and accurate method to study gene functions in H. pylori pathogenesis, an unmarked deletion method for both a single gene and a large fragment was established based on the FLP-FRT recombination system. Using this method, the gene hp0788, encoding an outer membrane protein (HofF), was deleted. Deletion of hp0788 did not affect growth or motility of H. pylori, but reduced the adherence of the bacteria to gastric epithelial cells. The apoptosis of GES-1 cells caused by H. pylori infection was also reduced by the defection of hp0788. These suggest that hp0788 takes part in the bacterium-host interaction and plays an important role in H. pylori infection. Furthermore, a large genomic fragment deletion from hp0541 to hp0547 in cag pathogenicity island was also successfully achieved using FLP-FRT method. The innovative application of the FLP-FRT recombination system in H. pylori to construct unmarked deletion would provide a helpful tool for further function research of putative pathogenic genes and contribute to the understanding of H. pylori pathogenesis.

Functional study of gene hp0169 in Helicobacter pylori pathogenesis

Many virulence genes have been reported to play important roles in Helicobacter pylori pathogenesis. However the detailed mechanisms of many of them have not been completely clear. In this study, we found gene hp0169, encoding a putative collagenase (HpPrtC), was involved in pathogenesis of H. pylori. Recombinant HpPrtC shows activities to both native and heat-denatured collagens. This result indicated that HpPrtC may act as a virulence factor to help the bacterium colonize in their host stomach by degrading surrounding collagens. hp0169 was deleted by homologous recombination to study its function in bacterium-host cell interaction. For the pathogenic functions on the host cells, the hp0169 mutant exhibits no significant changes on inducing apoptosis of GES-1 cells. However, the viability and proliferation rate of GES-1 cells infected with mutant strain were higher than the cells infected with wild-type strain. These results indicated that except for its collagenolytic activity, HpPrtC might participate in H. pylori pathogenesis through an additional pathway. Functional studies on hp0169 involved in pathogenesis would shed light on deep understanding of the pathogenic mechanism of H. pylori.

Detection of Helicobacter pylori DNA in Formalin-Fixed Paraffin-Embedded Gastric Biopsies Using Laser Microdissection and qPCR

Molecular detection and analysis of virulence factors of Helicobacter pylori depends on the specificity of cell selection in the gastric biopsies. The laser microdissection (LM) instruments combine microscopy with laser cut sectioning. This combination allows one to choose only the bacteria that are in direct contact with epithelial cells in the gastric biopsy sample, avoiding those microorganisms attached to the mucus layer in the sample. The average concentration of DNA isolated from 25 cuts with selected bacteria is around 1.94 ng/μL, which is enough DNA to perform a qPCR protocol using real-time instruments to amplify 16sDNA or virulence factors like cagA or vacA. Consequently, the application of these technologies in the molecular analysis of Helicobacter pylori directly in contact with the surface of gastric epithelial cells is more precise and could yield better insights about the complex mechanisms of interactions between pathogen and host. Insights derived from research using the techniques described herein may in future facilitate prevention of infection or improved therapeutic options.

Sequence Analysis of Hypothetical Proteins from Helicobacter pylori 26695 to Identify Potential Virulence Factors

Helicobacter pylori is a Gram-negative bacteria that is responsible for gastritis in human. Its spiral flagellated body helps in locomotion and colonization in the host environment. It is capable of living in the highly acidic environment of the stomach with the help of acid adaptive genes. The genome of H. pylori 26695 strain contains 1,555 coding genes that encode 1,445 proteins. Out of these, 340 proteins are characterized as hypothetical proteins (HP). This study involves extensive analysis of the HPs using an established pipeline which comprises various bioinformatics tools and databases to find out probable functions of the HPs and identification of virulence factors. After extensive analysis of all the 340 HPs, we found that 104 HPs are showing characteristic similarities with the proteins with known functions. Thus, on the basis of such similarities, we assigned probable functions to 104 HPs with high confidence and precision. All the predicted HPs contain representative members of diverse functional classes of proteins such as enzymes, transporters, binding proteins, regulatory proteins, proteins involved in cellular processes and other proteins with miscellaneous functions. Therefore, we classified 104 HPs into aforementioned functional groups. During the virulence factors analysis of the HPs, we found 11 HPs are showing significant virulence. The identification of virulence proteins with the help their predicted functions may pave the way for drug target estimation and development of effective drug to counter the activity of that protein.

Expression of CDX2 in gastric cardia adenocarcinoma and its correlation with H. pylori and cell proliferation

BACKGROUND

Gastric cardia cancer (GCC) is located in the distal stomach, and strongly correlates with atrophic gastritis and Helicobacter pylori (H.pylori) infection. Caudal-related homeobox transcription factor 2 (CDX2) is homeobox gene encoding an intestine-specific transcription factor usually expressed in the intestinal epithelium cells. However, in several recent published papers, CDX2 was found to be aberrantly expressed in gastric, thyroid and ovarian cancer.

RESULTS

Higher expression of CDX2 was found in GCC tissues in comparison with non-malignant cardia mucosa (p<0.05). Moreover, immunohistochemical analysis demonstrated that CDX2 expression correlated with lymphatic metastasis. In addition, we found that CDX2 expression progressively increased with the level of H. pylori infection (p<0.05), and also correlated with cell proliferation, based on Ki67 staining.

METHODS

To investigate the relationship between CDX2, cell proliferation and H. pylori infection, we detected CDX2, Ki62 and H.pylori expression in 83 non-malignant gastric cardia mucosacases and 60 GCC specimens in the Chaoshan area, a high-risk region for esophageal and gastric cardia cancer.

CONCLUSION

These findings provide pathological evidence that H. pylori infectionis a driving force of gastric cardia carcinogenesis by upregulating CDX2 and inducing inflammation. These results provide new pathological evidence that H. pylori infection induces GCC tumorigenesis.

Lipopolysaccharide modification in Gram-negative bacteria during chronic infection

The Gram-negative bacterial lipopolysaccharide (LPS) is a major component of the outer membrane that plays a key role in host-pathogen interactions with the innate immune system. During infection, bacteria are exposed to a host environment that is typically dominated by inflammatory cells and soluble factors, including antibiotics, which provide cues about regulation of gene expression. Bacterial adaptive changes including modulation of LPS synthesis and structure are a conserved theme in infections, irrespective of the type or bacteria or the site of infection. In general, these changes result in immune system evasion, persisting inflammation and increased antimicrobial resistance. Here, we review the modifications of LPS structure and biosynthetic pathways that occur upon adaptation of model opportunistic pathogens (Pseudomonas aeruginosa, Burkholderia cepacia complex bacteria, Helicobacter pylori and Salmonella enterica) to chronic infection in respiratory and gastrointestinal sites. We also discuss the molecular mechanisms of these variations and their role in the host-pathogen interaction.

Helicobacter pylori therapy: a paradigm shift

Helicobacter pylori (H. Pylori) is a leading cause of gastroduodenal disease, including gastric cancer. H. pylori eradication therapies and their efficacy are summarized. A number of current treatment regimens will reliably yield >90% or 95% cure rates with susceptible strains. None has proven to be superior. We show how to predict the efficacy of a regimen in any population provided one knows the prevalence of antibiotic resistance. As with other infectious diseases, therapy should always be susceptibility-based. Susceptibility testing should be demanded. We provide recommendations for empiric therapies when that is the only option and describe how to distinguish studies providing misinformation from those providing reliable and interpretable data. When treated as an infectious disease, high H. pylori cure rates are relatively simple to reliably achieve.

Lactobacilli Reduce Helicobacter pylori Attachment to Host Gastric Epithelial Cells by Inhibiting Adhesion Gene Expression

The human gastrointestinal tract, including the harsh environment of the stomach, harbors a large variety of bacteria, of which Lactobacillus species are prominent members. The molecular mechanisms by which species of lactobacilli interfere with pathogen colonization are not fully characterized. In this study, we aimed to study the effect of lactobacillus strains upon the initial attachment of Helicobacter pylori to host cells. Here we report a novel mechanism by which lactobacilli inhibit adherence of the gastric pathogen H. pylori In a screen with Lactobacillus isolates, we found that only a few could reduce adherence of H. pylori to gastric epithelial cells. Decreased attachment was not due to competition for space or to lactobacillus-mediated killing of the pathogen. Instead, we show that lactobacilli act on H. pylori directly by an effector molecule that is released into the medium. This effector molecule acts on H. pylori by inhibiting expression of the adhesin-encoding gene sabA Finally, we verified that inhibitory lactobacilli reduced H. pylori colonization in an in vivo model. In conclusion, certain Lactobacillus strains affect pathogen adherence by inhibiting sabA expression and thereby reducing H. pylori binding capacity.

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.

Expression of cagA, virB/D Complex and/or vacA Genes in Helicobacter pylori Strains Originating from Patients with Gastric Diseases

In order to better understand pathogenicity of Helicobacter pylori, particularly in the context of its carcinogenic activity, we analysed expression of virulence genes: cagA, virB/D complex (virB4, virB7, virB8, virB9, virB10, virB11, virD4) and vacA in strains of the pathogen originating from persons with gastric diseases. The studies were conducted on 42 strains of H. pylori isolated from patients with histological diagnosis of non-atrophic gastritis—NAG (group 1, including subgroup 1 containing cagA⁺ isolates and subgroup 2 containing cagA^- strains), multifocal atrophic gastritis—MAG (group 2) and gastric adenocarcinoma—GC (group 3). Expression of H. pylori genes was studied using microarray technology. In group 1, in all strains of H. pylori cagA⁺ (subgroup 1) high expression of the gene as well as of virB/D was disclosed, accompanied by moderate expression of vacA. In strains of subgroup 2 a moderate expression of vacA was detected. All strains in groups 2 and 3 carried cagA gene but they differed in its expression: a high expression was detected in isolates of group 2 and its hyperexpression in strains of group 3 (hypervirulent strains). In both groups high expression of virB/D and vacA was disclosed. Our results indicate that chronic active gastritis may be induced by both cagA⁺ strains of H. pylori, manifesting high expression of virB/D complex but moderate activity of vacA, and cagA^- strains with moderate expression of vacA gene. On the other hand, in progression of gastric pathology and carcinogenesis linked to H. pylori a significant role was played by hypervirulent strains, manifesting a very high expression of cagA and high activity of virB/D and vacA genes.

Infectious Aetiology of Marginal Zone Lymphoma and Role of Anti-Infective Therapy

Marginal zone lymphomas have been associated with several infectious agents covering both viral and bacterial pathogens and in some cases a clear aetiological role has been established. Pathogenetic mechanisms are currently not completely understood. However, the role of chronic stimulation of the host immune response with persistent lymphocyte activation represents the most convincing explanation for lymphoproliferation. Gastric MALT lymphoma is strictly associated with Helicobacter pylori infection and various eradicating protocols, developed due to increasing antibiotic resistance, represent the first line therapy for gastric MALT. The response rate to eradication is good with 80% of response at 1 year; this finding is also noteworthy because it recapitulates cancer cured only by the antibacterial approach and it satisfies the Koch postulates of causation, establishing a causative relationship between Hp and gastric MALT lymphoma. Patients with chronic HCV infection have 5 times higher risk to develop MZL, in particular, an association with splenic and nodal MZL has been shown in several studies. Moreover, there is evidence of lymphoma regression after antiviral therapy with interferon+ribavirin, thus raising hope that newly available drugs, extremely efficient against HCV replication, could improve outcome also in HCV-driven lymphomas. Another case-study are represented by those rare cases of MZL localized to orbital fat and eye conjunctivas that have been associated with Chlamydophila psittaci infection carried by birds. Efficacy of antibacterial therapy against C. psittaci are conflicting and generally poorer than gastric MALT. Finally, some case reports will cover the relationship between primary cutaneous B-cell Lymphomas and Borrelia Burgdorferi.

Meta-analysis of relationship between Helicobacter pylori infection and level of insulin resistance

AIM: To investigate the association between Helicobacter pylori (H. pylori) infection and level of insulin resistance (IR).

METHODS: The articles on the association of H. pylori with IR level were retrieved by searching databases from the inception of each database to July 2015. Data extraction and quality assessment were completed by two authors. Meta-analysis was performed using RevMan 5.3 software.

RESULTS: Seven papers with nine studies were included for meta-analysis. A total of 3097 patients, including 1718 H. pylori (+) subjects, were involved. The results of Meta-analysis showed that there was a significant difference in insulin resistance levels between patients with H. pylori infection and those without in the overall population (WMD = 0.38, 95%CI: 0.13-0.64, P < 0.05). Subgroup analysis indicated that the significant difference in insulin resistance levels between patients with H. pylori infection and those without existed in patients aged < 45 years (WMD = 0.63, 95%CI: 0.40-0.86, P < 0.05), those who underwent endoscopic biopsy (WMD = 0.70, 95%CI: 0.46-0.94, P < 0.05), those who had a body mass index (BMI) < 25 kg/m² (WMD = 0.72, 95%CI:0.49-0.96, P < 0.05), and Asian patients (WMD = 0.66, 95%CI: 0.44-0.87, P < 0.05), but not in patients aged ≥ 45 years, those who underwent serum H. pylori-IgG antibody testing, those who had a BMI ≥ 25 kg/m², or American patients. The results of publication bias and sensitivity analysis confirmed the reliability and stability of this Meta-analysis.

CONCLUSION: H. pylori infection is associated with elevated insulin resistance.

Metalloregulation of Helicobacter pylori physiology and pathogenesis

Helicobacter pylori is a Gram-negative spiral-shaped bacterium that colonizes over half of the world's population. Chronic H. pylori infection is associated with increased risk for numerous disease outcomes including gastritis, dysplasia, neoplasia, B-cell lymphoma of mucosal-associated lymphoid tissue (MALT lymphoma), and invasive adenocarcinoma. The complex interactions that occur between pathogen and host are dynamic and exquisitely regulated, and the relationship between H. pylori and its human host are no exception. To successfully colonize, and subsequently persist, within the human stomach H. pylori must temporally regulate numerous genes to ensure localization to the gastric lumen and coordinated expression of virulence factors to subvert the host's innate and adaptive immune response. H. pylori achieves this precise gene regulation by sensing subtle environmental changes including host-mediated alterations in nutrient availability and responding with dramatic global changes in gene expression. Recent studies revealed that the presence or absence of numerous metal ions encountered in the lumen of the stomach, or within host tissues, including nickel, iron, copper and zinc, can influence regulatory networks to alter gene expression in H. pylori. These expression changes modulate the deployment of bacterial virulence factors that can ultimately influence disease outcome. In this review we will discuss the environmental stimuli that are detected by H. pylori as well as the trans regulatory elements, specifically the transcription regulators and transcription factors, that allow for these significant transcriptional shifts.

Bacterial Genotoxins: Merging the DNA Damage Response into Infection Biology

Bacterial genotoxins are unique among bacterial toxins as their molecular target is DNA. The consequence of intoxication or infection is induction of DNA breaks that, if not properly repaired, results in irreversible cell cycle arrest (senescence) or death of the target cells. At present, only three bacterial genotoxins have been identified. Two are protein toxins: the cytolethal distending toxin (CDT) family produced by a number of Gram-negative bacteria and the typhoid toxin produced by Salmonella enterica serovar Typhi. The third member, colibactin, is a peptide-polyketide genotoxin, produced by strains belonging to the phylogenetic group B2 of Escherichia coli. This review will present the cellular effects of acute and chronic intoxication or infection with the genotoxins-producing bacteria. The carcinogenic properties and the role of these effectors in the context of the host-microbe interaction will be discussed. We will further highlight the open questions that remain to be solved regarding the biology of this unusual family of bacterial toxins.

Detection of Helicobacter pylori glmM gene in bovine milk using Nested polymerase chain reaction

Aim:

The aim was to detect the glmM gene of Helicobacter pylori (H. pylori) in cow’s milk from different dairy farms in Khartoum State using Nested polymerase chain reaction (PCR).

Materials and Methods:

A total of 50 milk samples were collected from different dairy farms in Khartoum State (13 from Khartoum, 24 Khartoum North, and 13 from Omdurman Provinces).

Results:

The generated results showed that 11/50 (22%) were harboring the investigated H. pylori glmM gene in Khartoum State (1/13 [7.7%] Khartoum, 9/24 [37.5%] Khartoum North, and 1/13 [7.7%] Omdurman provinces, respectively).

Conclusion:

To the best of our knowledge, this was the first report on the detection of H. pylori glmM gene in cattle milk in Khartoum State. Nonetheless, the high percentages of H. pylori DNA detection in milk opened new avenues toward exploring the risk of human infection with H. pylori through the consumption of raw milk.

Immune thrombocytopenia associated with solid cancer

We describe a case of immune thrombocytopenia (ITP) associated with ovarian cancer. At the patient's first visit to hospital, high platelet-associated IgG and low platelet count (74 × 10(9)/L) were noted on blood test. She was diagnosed as having ITP complicated by ovarian cancer. Four days after surgery, the platelet count had increased to within the normal range. This is the first report of a patient with ITP complicated by ovarian cancer in which the platelet count reverted to normal soon after surgery for the ovarian cancer. We also investigated the characteristics of similar solid cancers with ITP at National Kyushu Cancer Center, Fukuoka, Japan.

The Influence of the Gut Microbiome on Obesity, Metabolic Syndrome and Gastrointestinal Disease

There is a fine balance in the mutual relationship between the intestinal microbiota and its mammalian host. It is thought that disruptions in this fine balance contribute/account for the pathogenesis of many diseases. Recently, the significance of the relationship between gut microbiota and its mammalian host in the pathogenesis of obesity and the metabolic syndrome has been demonstrated. Emerging data has linked intestinal dysbiosis to several gastrointestinal diseases including inflammatory bowel disease, irritable bowel syndrome, nonalcoholic fatty liver disease, and gastrointestinal malignancy. This article is intended to review the role of gut microbiota maintenance/alterations of gut microbiota as a significant factor as a significant factor discriminating between health and common diseases. Based on current available data, the role of microbial manipulation in disease management remains to be further defined and a focus for further clinical investigation.

Polymorphisms in TLR9 but not in TLR5 increase the risk for duodenal ulcer and alter cytokine expression in the gastric mucosa

Colonization of the gastric mucosa by Helicobacter pylori can lead to peptic ulcer and gastric adenocarcinoma. TLRs are signaling receptors involved in the recognition of microorganisms, and polymorphisms in their genes may influence the innate and adaptive immune response to H. pylori, affecting the clinical outcomes of the infection. We assessed the association between single nucleotide polymorphisms in TLR9 and TLR5 and gastroduodenal diseases. All patients were genotyped by allelic discrimination in regions 1174C>T and 1775A>G of TLR5 and -1237T>C and 2848G>A of TLR9. The 2848A allele of TLR9 was more frequent in duodenal ulcer and showed an association of risk with this pathology. Polymorphisms in TLR5 were not found to be associated with disease. Patients with polymorphisms in TLR9 and TLR5 expressed significantly lower levels of IL-1β and TNF-α, whereas polymorphisms in TLR5 also decreased the expression of IL-6 and IL-10. Our findings suggest that 2848G>A polymorphism in TLR9 increases the risk for the development of duodenal ulcer probably by modifying the inflammatory response to H. pylori infection. This is the first study to show an association of 2848A allele of TLR9 with duodenal ulcer and with altered expression of inflammatory cytokines in the gastric mucosa.

Chemical composition and anti-Helicobacter pylori effect of Satureja bachtiarica Bunge essential oil

Resistance of H. pylori strains to common antibiotics has been developed in different parts of the world and continues to increase. It is important to investigate the novel and efficient anti-H. pylori drugs, among which the plants would be suitable sources. Satureja bachtiarica Bunge is traditionally used as antimicrobial agent. In this study, we evaluated the antibacterial activity of S. bachtiarica Bunge essential oil against 10 clinical isolates of Helicobacter pylori by disc diffusion and agar dilution methods. The chemical composition of essential oil was analyzed by GC and GC-MS. Carvacrol (45.5%) and thymol (27.9%) were the primary constituents of oil, followed by p-cymene (4.4%), and γ-terpinene (4.0%). S. bachtiarica essential oil showed strong antibacterial activity against clinical isolates of H. pylori (17.6 ± 1.1 mm and 0.035 ± 0.13 μl/ml). Carvacrol, as the first main component, had a significant role in this effect, whereas in the presence of thymol, the antibacterial effect of carvacrol was reduced. Therefore, S. bachtiarica essential oil can be applied as an alternative agent for treatment of H. pylori infections. More studies would be required to better clarify its mechanism of action on H. pylori.

Association between Helicobacter pylori genotypes and severity of chronic gastritis, peptic ulcer disease and gastric mucosal interleukin-8 levels: Evidence from a study in the Middle East

Background

The varied clinical presentations of Helicobacter pylori (H. pylori) infection are most likely due to differences in the virulence of individual strains, which determines its ability to induce production of interleukin-8 (IL-8) in the gastric mucosa. The aim of this study was to examine association between cagA, vacA-s1 and vacA-s2 genotypes of H. pylori and severity of chronic gastritis and presence of peptic ulcer disease (PUD), and to correlate these with IL-8 levels in the gastric mucosa.

Methods

Gastric mucosal biopsies were obtained from patients during esophagogastroduodenoscopy. The severity of chronic gastritis was documented using the updated Sydney system. H. pylori cagA and vacA genotypes were detected by PCR. The IL-8 levels in the gastric mucosa were measured by ELISA.

Results

H. pylori cagA and/or vacA genotypes were detected in 99 patients (mean age 38.4±12.9; 72 males), of whom 52.5% were positive for cagA, 44.4% for vacA-s1 and 39.4% for vacA-s2; and 70.7% patients had PUD. The severity of inflammation in gastric mucosa was increased with vacA-s1 (p=0.017) and decreased with vacA-s2 (p=0.025), while cagA had no association. The degree of neutrophil activity was not associated with either cagA or vacA-s1, while vacA-s2 was significantly associated with decreased neutrophil activity (p=0.027). PUD was significantly increased in patients with cagA (p=0.002) and vacA-s1 (p=0.031), and decreased in those with vacA-s2 (p=0.011). The level of IL-8 was significantly increased in patients with cagA (p=0.011) and vacA-s1 (p=0.024), and lower with vacA-s2 (p=0.004). Higher levels of IL-8 were also found in patients with a more severe chronic inflammation (p=0.001), neutrophil activity (p=0.007) and those with PUD (p=0.001).

Conclusions

Presence of vacA-s1 genotype of H. pylori is associated with more severe chronic inflammation and higher levels of IL-8 in the gastric mucosa, as well as higher frequency of PUD. Patients with vacA-s2 have less severe gastritis, lower levels of IL-8, and lower rates of PUD. The presence of cagA genotype is not associated with the severity of gastritis or IL-8 induction in the gastric mucosa. The association of cagA with PUD may be a reflection of its presence with vacA-s1 genotype.