Pathogenesis of Helicobacter pylori infection

Pangenome Analysis of Helicobacter pylori Isolates from Selected Areas of Africa Indicated Diverse Antibiotic Resistance and Virulence Genes

The challenge facing Helicobacter pylori (H. pylori) infection management in some parts of Africa is the evolution of drug-resistant species, the lack of gold standard in diagnostic methods, and the ineffectiveness of current vaccines against the bacteria. It is being established that even though clinical consequences linked to the bacteria vary geographically, there is rather a generic approach to treatment. This situation has remained problematic in the successful fight against the bacteria in parts of Africa. As a result, this study compared the genomes of selected H. pylori isolates from selected areas of Africa and evaluated their virulence and antibiotic drug resistance, those that are highly pathogenic and are associated with specific clinical outcomes and those that are less virulent and rarely associated with clinical outcomes. 146 genomes of H. pylori isolated from selected locations of Africa were sampled, and bioinformatic tools such as Abricate, CARD RGI, MLST, Prokka, Roary, Phandango, Google Sheets, and iTOLS were used to compare the isolates and their antibiotic resistance or susceptibility. Over 20 k virulence and AMR genes were observed. About 95% of the isolates were genetically diverse, 90% of the isolates harbored shell genes, and 50% harbored cloud and core genes. Some isolates did not retain the cagA and vacA genes. Clarithromycin, metronidazole, amoxicillin, and tinidazole were resistant to most AMR genes (vacA, cagA, oip, and bab). Conclusion. This study found both virulence and AMR genes in all H. pylori strains in all the selected geographies around Africa with differing quantities. MLST, Pangenome, and ORF analyses showed disparities among the isolates. This in general could imply diversities in terms of genetics, evolution, and protein production. Therefore, generic administration of antibiotics such as clarithromycin, amoxicillin, and erythromycin as treatment methods in the African subregion could be contributing to the spread of the bacterium's antibiotic resistance.

Global and regional prevalence of Helicobacter pylori in drinking waters: A sustainable, human development and socio-demographic indices based meta-regression-modelling

Helicobacter pylori (Hp) transmission dynamics via drinking water (DW) has a far much higher direct and indirect public health disease burden than previously thought. This study aimed to assess the global prevalence of Hp in DW, distributions across regions and socioeconomic indices (continent, world bank income, Human Development Index (HDI), Sustainable Development Index (SuDI), Socio-Demographic Index (SDI) quintile, and WHO regions). Hp-DW related data mined from five databases until 10/12/2022 according to PRISMA standard were quality-appraised and fitted to a generalized linear mixed-effects model. Sub-group analysis and meta-regression-modelling coupled with a 1000-permutation test (_⁎) were conducted. The global prevalence of Hp in DW was 15.7% (95% confidence interval [CI]: 7.98-27.5), which varied significantly by sampling methods (Moore swabbing (61.0% [0.00-100.0]) vs. grab sampling (13.68%[6.99-25.04])) and detection technique (non-culture (21.35%[9.13-42.31]) vs. cultured-based methods (Psubgroup < 0.01)). The period 1990-99 had the highest prevalence (41.24% [0.02-99.97]). Regarding regional designations, Hp prevalence in DW was significantly different being highest in North America (61.82% [41.03-79.02]) by continents, AMR (42.66% [20.81-67.82]) by WHO group, high HDI (24.64% [10.98-46.43]) by HDI group and North America (61.90% [2.79-98.93]) by world bank region (Psubgroup < 0.01). Generally, sample preparation, SuDI grouping, and detection/confirmation techniques, have significant effects on the detection/prevalence of Hp in DW (Psubgroup < 0.01). Hp prevalence in DW was not significantly different among rural and urban DW (Psubgroup = 0.90), world bank income groups (Psubgroup = 0.15), and SDI quintiles (Psubgroup = 0.07). Among the predictors examined, only sample size (p < 0.1, R_∗²(coefficient of determinant) = 15.29%), continent (p_∗val = 0.04), HDI (p_∗val = 0.02), HDI group (p_∗val = 0.05), and microbiological methods (p < 0.1; R_∗²=28.09 %) predicted Hp prevalence in DW robustly. In conclusion, Hp prevalence is still endemic in DW regardless of the regional designations/improve DW supplies.

The Importance of Accurate Early Diagnosis and Eradication in Helicobacter pylori Infection: Pictorial Summary Review in Children and Adults

Among the most widespread childhood infections, Helicobacter pylori (H. pylori) develops potentially life-threatening conditions in adults if not appropriately treated. Helicobacter pylori is a common human pathogen that was first described in the stomach many years ago. The discovery of H. pylori was crucial in gastroenterology; this bacterium is associated with chronic gastritis, peptic ulcers, gastric cancer, and lymphoid tissue lymphoma related to the gastric mucosa. Studies published so far estimate that approximately 10% of subjects infected with H. pylori develop a peptic ulcer, and 1-3% of subjects develop gastric cancer. The clinical manifestations are variable and characteristically depend on the individual factors of the host. Various methods of detection and diagnosis of H. pylori infection have been developed, each with advantages, disadvantages, and/or limitations. Available diagnostic tests are usually performed using invasive (endoscopy, biopsy, rapid urease test, cultures, and molecular tests) and noninvasive methods (urea breath test, stool antigen examination, and serological and molecular tests). Although there is extensive accessibility for diagnosing and treating H. pylori infection, the prevalence of antibiotic resistance is not negligible. Thus, numerous studies and meta-analyses are focused on a new orientation of gastroenterologists in diagnosing and treating H. pylori infections. A fascinating perspective hypothesis is the administration of probiotics to reduce H. pylori adhesion to gastric epithelial cells, preventing H. pylori colonization, especially in children, or reinfection with H. pylori in high-risk adult patients.

H. pylori-associated chronic gastritis: status update on the problem

Chronic gastritis is a group of chronic diseases that are morphologically characterized by persistent inflammatory infiltrate and impaired cellular turnover with the development of intestinal metaplasia, atrophy, and epithelial dysplasia in the gastric mucosa. Numerous studies have shown that Helicobacter pylori (H. pylori) infection is the absolutely dominant etiological factor of CG worldwide. Given this fact, the Expert Council of the latest Maastricht VI 2022 consensus recommended that H. pylori is to be treated as a pathogen, which always results in the development of CG. The prevalence of H. pylori-associated CG is about 44.3–48.5%, however 80–90% of cases are asymptomatic. In H. pylori­infected patients with dyspepsia and no other pathology of the gastroduodenal region, which has been confirmed endoscopically, clinical manifestations can be interpreted as part of H. pylori­associated CG if a long-lasting remission of symptoms has been achieved after successful eradication therapy. While patients with persistent dyspeptic symptoms can be considered as patients with functional dyspepsia, despite successful eradication therapy. Advanced endoscopic techniques (narrow band imaging (NBI) endoscopy, high resolution endoscopy, chromoendoscopy, laser confocal endomicroscopy) are precise and reproducible methods for diagnosing precancerous changes in the mucous membrane. However, the diagnosis of CG requires that inflammatory cells have been histologically detected in the lamina propria. The CG therapy aims to reach a persistent relief of dyspeptic symptoms of the disease (if any), as well as resolution of inflammatory processes and prevention of the progression of precancerous changes in the gastric mucosa. The achievement of these goals is primarily determined by the timely diagnosis of H. pylori infection and successful eradication therapy.

Zuojin Pill attenuates Helicobacter pylori-induced chronic atrophic gastritis in rats and improves gastric epithelial cells function in GES-1 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Zuojin pill (ZJP), a classical Chinese medicine formula, has been widely applied in Chinese clinical practice for the treatment of gastric injury such as acute gastric lesion, acute gastric mucosal injury, chronic unpredictable mild stress, gastroesophageal reflux disease, etc, thereby exerting anti-chronic atrophic gastritis (CAG) effects in traditional Chinese herbal medicine.

AIM OF THE STUDY

This study was aimed to explore the therapeutic effects and molecular mechanisms of ZJP on Helicobacter pylori (H. pylori)-induced CAG based on the comprehensive approaches.

MATERIALS AND METHODS

Sprague-Dawley rats were infected with H. pylori for 8 weeks to establish CAG model. Then, rats in the ZJP groups received doses of 0.63, 1.26, and 2.52 g/kg ZJP for 4 weeks. Therapeutic effects of ZJP on serum indices and the histopathology of the gastric were analyzed in vivo. Moreover, GES-1 cells were infected with H. pylori to establish gastric epithelial cell injury model in vitro. Cell viability and gastric epithelial cell morphology were detected by a high-content screening (HCS) assay. Furthermore, the relative mRNA and protein expression of JMJD2B/COX-2/VEGF axis and HMGB1/NF-κB signaling pathway in vivo and in vitro were determined by RT-PCR and Western Blotting, respectively.

RESULTS

The results showed that the therapeutic effects of ZJP on CAG rats were presented in down-regulation serum biochemical indices and alleviating histological damage of gastric tissue. ZJP could dose-dependently decrease the serum IL-6, MCP-1, PGE2, TNF-α, and VEGF level and significantly improved gastric tissue inflammatory lesions. Besides, ZJP has an effect on increasing cell proliferation of GES-1 cells, ameliorating H. pylori-induced gastric epithelial cell damage. It was found that ZJP has a down-regulating effect on inflammatory reaction and could inhibit the relative mRNA and protein expression of JMJD2B/COX-2/VEGF axis and HMGB1/NF-κB signaling pathway in vivo and in vitro, including JMJD2B, COX-2, VEGF, VEGFR1, and VEGFR2, which in turn reduced the damage of gastric mucosal cells.

CONCLUSIONS

The results suggested that ZJP exerts therapeutic effects on H. pylori-induced CAG by inhibiting the JMJD2B/COX-2/VEGF axis and HMGB1/NF-κB signaling pathway. These findings deeply explained why ZJP could be used to treat CAG clinically and clarified its pharmacological effect and potential mechanism in the treatment of CAG.

Helicobacter pylori-Mediated Oxidative Stress and Gastric Diseases: A Review

Gastric cancer is considered to be a type of gastrointestinal tumor and is mostly accompanied by Helicobacter pylori (HP) infection at the early stage. Hence, the long-term colonization of the gastric mucosa by HP as a causative factor for gastrointestinal diseases cannot be ignored. The virulence factors secreted by the bacterium activate the signaling pathway of oxidative stress and mediate chronic inflammatory response in the host cells. The virulence factors also thwart the antibacterial effect of neutrophils. Subsequently, DNA methylation is induced, which causes continuous cell proliferation and evolution toward low-grade-differentiated gastric cells. This process provides the pathological basis for the occurrence of progressive gastric cancer. Therefore, this review aims to summarize the oxidative stress response triggered by HP in the gastric mucosa and the subsequent signaling pathways. The findings are expected to help in the formulation of new targeted drugs for preventing the occurrence of early gastric cancer and its progression to middle and advanced cancer.

Helicobacter pylori Pathogenicity Islands and Giardia lamblia Cysteine Proteases in Role of Coinfection and Pathogenesis

Helicobacter pylori is a well-known human-specific stomach pathogen that infects more than half of the world’s population. The infection with this bacterium can cause a variety of gastrointestinal problems, including chronic gastritis, peptic ulcers, and even cancer. H. pylori is a highly infectious bacterium. H. pylori causes an increase in gastric mucosa pH or gastric mucosa intestinal metaplasia. These modifications in the stomach environment are necessary for G. lamblia colonization to occur. Giardia lamblia is a flagellate protozoan parasite that can cause giardiasis in humans and other mammals. It dwells in the duodenum and upper jejunum. Globally, over 280 million cases of human giardiasis are predicted to occur each year. Simultaneous human colonization by G. lamblia and H. pylori is a typical occurrence since the viruses’ predisposing factors are similar in both groups. Giardiasis is a parasitic infection that affects both children and adults worldwide. Infection with Giardia is more common in underdeveloped countries. Globally, more than 200 million cases of giardiasis are detected each year. In contrast, the presence of G. lamblia in the host body triggers an immunological response comparable to that of H. pylori, with lymphocytes strongly polarized towards Th1. As a result, their combined presence exacerbates host tissue damage. The major goal of this seminar is to describe the pathophysiology, immunology, and clinical aspects of G. lamblia and H. pylori coinfection using a comprehensive search of PubMed, Lancet, and Google Scholar sources. Upper gastrointestinal problems such as upper abdominal pain, abdominal bloating, nausea, vomiting, epigastric pain/burning, and belching are all caused by both organisms. Differentiation by physical examination is impossible in people infected with both bacteria. For this coinfection distinction, a laboratory diagnosis is required. G. lamblia and H. pylori, when present together, have a synergistic effect on the host and can cause serious damage. As a result, researchers should delve deeper into the mechanics underlying this potential microbial interaction.

Clinical relevance of virulence genes in Helicobacter pylori isolates recovered from adult dyspeptic patients in Turkey

PURPOSE

Bacterial virulence factors play a major role in the pathogenesis of Helicobacter pylori infection. The aims of this study were to evaluate virulence genes in H. pylori isolates and to compare the presence of these genes and associated clinical pathologies.

METHODS

A total of 148 H. pylori isolates, recovered from adult dyspeptic patients, were used. The patients, from whom the isolates were obtained, were assigned to two groups by their endoscopic findings, which manifested as chronic gastritis or peptic ulcer. The presence of gastric atrophy and intestinal metaplasia was recorded for each patient, based on histopathological examination. Analyses of the virulence genes were performed by the polymerase chain reaction technique.

RESULTS

The patients had a mean age of 47 ​± ​15 years and 86 (58%) of them were female. Based on endoscopic examination, 103 (69.6%) patients were diagnosed with chronic gastritis and 45 (30.4%) with peptic ulcer. Histopathological examination revealed intestinal metaplasia in 30 (20%) patients and gastric atrophy in 12 (8%) patients. The prevalence rates of cagA, cagE, iceA1, iceA2, and babA2 were determined to be 87%, 74%, 58%, 26%, and 95%, respectively. The most prevalent vacA alleles were s1/s1a (82%/97%) and the least prevalent allele was s2 (20%). A new vacA genotype (s1as1bs1c) was detected, for the first time, in 18 (12%) isolates. No significant difference was found between the patient groups with chronic gastritis and peptic ulcer for the prevalences of the virulence genes (p ​> ​0.05). Furthermore, intestinal metaplasia and gastric atrophy showed no significant correlation with the virulence genes (p ​> ​0.05).

CONCLUSIONS

It is thoughted that H. pylori isolates with predominant cagA, cagE, VacA (s1, s1a), and babA2 virulence genes are associated with gastroduodenal diseases. However, there is no correlation between gastric premalignant lesions and virulence genes.

Probing Transferrin Receptor Overexpression in Gastric Cancer Mice Models

Exposure to carcinogenic chemicals, Helicobacter pylori infection, and high dietary salt are the risk factors associated with gastric cancer. Mice models of gastric cancer are key to understanding the cancer mechanism, to discerning the role played by different factors, and to determining therapeutic effects of different treatments. The goal has been to find targets which are only expressed with cancer so that they can be targeted specifically without harming normal cells. One such target could be the transferrin receptor, a glycoprotein receptor that is expressed many-folds on rapidly growing cells due to the greater demand of iron. In this study, gastric cancer was developed in mice (BALB/c) with human cancer-associated risk factors by feeding them with tumor-inducing concentration of methyl nitrosourea, dietary salt, and H. pylori along with normal feed and water. Three strategies were adopted to induce gastric cancer; (1) use of N-methyl-N-nitrosourea (MNU) with high dietary salt (NaCl), (2) infection with H. pylori (isolated from human gastric tissue), and (3) use of MNU along with high concentration of NaCl after H. pylori infection. Mice were dissected after induction, and histological study of gastric tissue was done with Hematoxylin and Eosin staining. A diagnostic probe comprising transferrin conjugated with cadmium sulfide quantum dots was prepared and characterized. It was used to study the transferrin receptor overexpression in gastric tissue of cancer-induced mice relative to the normal mice. Mice of group 3 showed the highest rate of the cancer incidence ratio (96%) along with a high expression of transferrin receptors among the three groups. Histochemical studies showed that different types of gastric cancer depend upon the cancer-induction conditions. The mouse model of group 3 has the potential to be used in the future to study the therapeutic effects of cancer medicines, and overexpression of transferrin receptors could be identified through the designed probe to be used as diagnostics.

Recent Advances on Functional Nucleic-Acid Biosensors

In the past few decades, biosensors have been gradually developed for the rapid detection and monitoring of human diseases. Recently, functional nucleic-acid (FNA) biosensors have attracted the attention of scholars due to a series of advantages such as high stability and strong specificity, as well as the significant progress they have made in terms of biomedical applications. However, there are few reports that systematically and comprehensively summarize its working principles, classification and application. In this review, we primarily introduce functional modes of biosensors that combine functional nucleic acids with different signal output modes. In addition, the mechanisms of action of several media of the FNA biosensor are introduced. Finally, the practical application and existing problems of FNA sensors are discussed, and the future development directions and application prospects of functional nucleic acid sensors are prospected.

Whole-Genome Sequencing and Comparative Genomics of Three Helicobacter pylori Strains Isolated from the Stomach of a Patient with Adenocarcinoma

Helicobacter pylori is a common pathogen associated with several severe digestive diseases. Although multiple virulence factors have been described, it is still unclear the role of virulence factors on H. pylori pathogenesis and disease progression. Whole genome sequencing could help to find genetic markers of virulence strains. In this work, we analyzed three complete genomes from isolates obtained at the same point in time from a stomach of a patient with adenocarcinoma, using multiple available bioinformatics tools. The genome analysis of the strains B508A-S1, B508A-T2A and B508A-T4 revealed that they were cagA, babA and sabB/hopO negative. The differences among the three genomes were mainly related to outer membrane proteins, methylases, restriction modification systems and flagellar biosynthesis proteins. The strain B508A-T2A was the only one presenting the genotype vacA s1, and had the most distinct genome as it exhibited fewer shared genes, higher number of unique genes, and more polymorphisms were found in this genome. With all the accumulated information, no significant differences were found among the isolates regarding virulence and origin of the isolates. Nevertheless, some B508A-T2A genome characteristics could be linked to the pathogenicity of H. pylori.

Anti-microbial and anti-inflammatory effects of Cheonwangbosim-dan against Helicobacter pylori-induced gastritis

Background

There are various Helicobacter species colonizing the stomachs of animals. Although Helicobacter species usually cause asymptomatic infection in the hosts, clinical signs can occur due to gastritis associated with Helicobacter in animals. Among them, Helicobacter pylori is strongly associated with chronic gastritis, gastric ulcers, and gastric cancers. As the standard therapies used to treat H. pylori have proven insufficient, alternative options are needed to prevent and eradicate the diseases associated with this bacterium. Cheonwangbosim-dan (CBD), a traditional herbal formula that is popular in East Asia, has been commonly used for arterial or auricular flutter, neurosis, insomnia, and cardiac malfunction-induced disease.

Objectives

The present study investigated the antimicrobial effect of CBD on H. pylori-infected human gastric carcinoma AGS cells and model mice.

Methods

AGS cells were infected with H. pylori and treated with a variety of concentrations of CBD or antibiotics. Mice were given 3 oral inoculations with H. pylori and then dosed with CBD (100 or 500 mg/kg) for 4 weeks or with standard antibiotics for 1 week. One week after the last treatment, gastric samples were collected and examined by histopathological analysis, real-time quantitative polymerase chain reaction, and immunoblotting.

Results

Our results showed that CBD treatment of AGS cells significantly reduced the H. pylori-induced elevations of interleukin-8, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). In the animal model, CBD treatment inhibited the colonization of H. pylori and the levels of malondialdehyde, inflammation, proinflammatory cytokines, iNOS, and COX-2 in gastric tissues. CBD also decreased the phosphorylation levels of p38 mitogen-activated protein kinase family.

Conclusions

This study suggests that CBD might be a prospective candidate for treating H. pylori-induced gastric injury.

Helicobacter pylori-Derived Outer Membrane Vesicles (OMVs): Role in Bacterial Pathogenesis?

Persistent infections with the human pathogen Helicobacter pylori (H. pylori) have been closely associated with the induction and progression of a wide range of gastric disorders, including acute and chronic gastritis, ulceration in the stomach and duodenum, mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric adenocarcinoma. The pathogenesis of H. pylori is determined by a complicated network of manifold mechanisms of pathogen–host interactions, which involves a coordinated interplay of H. pylori pathogenicity and virulence factors with host cells. While these molecular and cellular mechanisms have been intensively investigated to date, the knowledge about outer membrane vesicles (OMVs) derived from H. pylori and their implication in bacterial pathogenesis is not well developed. In this review, we summarize the current knowledge on H. pylori-derived OMVs.

Dyslipidemia and Associated Factors Among Patients Suspected to Have Helicobacter pylori Infection at Jimma University Medical Center, Jimma, Ethiopia

BACKGROUND

Dyslipidemia is a group of plasma lipid and lipoprotein abnormality that is metabolically associated, and it is categorized by low HDL-C and increased LDL-C, TGs, and total cholesterol (TC) levels. Colonization of the stomach by Helicobacter pylori (H. pylori) causes chronic inflammation of the stomach wall which can change some biochemical factors in the patient. On the association of H. pylori infection and its contributions to change in serum lipid profile, different studies reported varying outcomes.

OBJECTIVE

To assess the prevalence of dyslipidemia and associated factors among patients suspected for H. pylori infection in the outpatient department of Jimma University Medical Center, Jimma, Ethiopia.

MATERIALS AND METHODS

A hospital-based cross-sectional study was conducted from January 03 to April 05, 2019, at Jimma University Medical Center on 369 H. pylori suspected patients. The study subjects were selected by convenient sampling technique. About 5mL of blood was collected from an overnight fasting individual. Data were edited, coded, and entered into Epidata version 3.1 and exported to (SPSS) version 25 for analysis. Bivariate analysis was used to screen those variables which were candidates for multivariate analysis.

RESULTS

From the total study subjects 77.5% had at least one abnormality in lipid profile and 87.2% of H. pylori positive patients had at least one abnormality in lipid profile. Our study demonstrated that there was significant increase of mean ± SD of TC, TG, and LDL-C in H. pylori positive patients than H. pylori negative patients (P-value < 0.05). After adjusting for traditional dyslipidemia risk factors, H. pylori infection was an independent predictor of dyslipidemia (AOR 2.628, 95% CI 1.477-4.678, P=0.001).

CONCLUSION

An increase in prevalence of dyslipidemia among H. pylori positive patients indicates H. pylori infected patients have a possibility of altered lipid profile, therefore assessment of lipid profile in H. pylori infected patients is recommended.

Lead Molecules for Targeted Urease Inhibition: An Updated Review from 2010 -2018

The field of enzyme inhibition is a tremendous and quickly growing territory of research. Urease a nickel containing metalloenzyme found in bacteria, algae, fungi, and plants brings hydrolysis of urea and plays important role in environmental nitrogen cycle. Apart from this it was found to be responsible for many pathological conditions due to its presence in many microorganisms such as H. Pylori, a ureolytic bacteria having urease which elevates pH of gastric medium by hydrolyzing urea present in alimentary canal and help the bacteria to colonize and spread infection. Due to the infections caused by the various bacterial ureases such as Bacillus pasteurii, Brucella abortus, H. pylori, H. mustelae, Klebsiella aerogenes, Klebsiella tuberculosis, Mycobacterium tuberculosis, Pseudomonas putida, Sporosarcina pasteurii and Yersinia enterocolitica, it has been the current topic of today's research. About a wide range of compounds from the exhaustive literature survey has been discussed in this review which is enveloped into two expansive classes, as Inhibitors from synthetic origin and Inhibitors from natural origin. Moreover active site details of enzyme, mechanism of catalysis of substrate by enzyme, uses of plant urease and its pathogenic behavior has been included in the current review. So, overall, this review article diagrams the current landscape of the developments in the improvements in the thriving field of urease inhibitory movement in medicinal chemistry from year 2010 to 2018, with an emphasis on mechanism of action of inhibitors that may be used for more development of recent and strong urease inhibitors and open up new doors for assist examinations in a standout amongst the most lively and promising regions of research.

Tailor-Made Detection of Individual Phosphorylated and Non-Phosphorylated EPIYA-Motifs of Helicobacter pylori Oncoprotein CagA

The gastric pathogen and carcinogen Helicobacter pylori(H. pylori) encodes a type IV secretion system for translocation of the effector protein CagA into host cells. Injected CagA becomes tyrosine-phosphorylated at the five amino acid residue Glutamate-Proline- Isoleucine-Tyrosine-Alanine (EPIYA)-sequence motifs. These phosphorylated EPIYA-sites represent recognition motifs for binding of multiple host factors, which then manipulate signaling pathways to trigger gastric disease. Thus, efficient detection of single phosphorylated EPIYA-motifs in CagA is required. Detection of phospho-CagA is primarily performed using commercial pan-phosphotyrosine antibodies. However, those antibodies were originally generated to recognize many phosphotyrosines in various mammalian proteins and are not optimized for use in bacteria. To address this important limitation, we synthesized 11-mer phospho- and non-phospho-peptides from EPIYA-motifs A, B, and C, and produced three phospho-specific and three non-phospho-specific rabbit polyclonal CagA antibodies. These antibodies specifically recognized the corresponding phosphorylated and non-phosphorylated EPIYA-motifs, while the EPIYA-C antibodies also recognized the related East-Asian EPIYA-D motif. Otherwise, no cross-reactivity of the antibodies among EPIYAs was observed. Western blotting demonstrated that each EPIYA-motif can be predominantly phosphorylated during H. pylori infection. This represents the first complete set of phospho-specific antibodies for an effector protein in bacteria, providing useful tools to gather information for the categorization of CagA phosphorylation, cancer signaling, and gastric disease progression.

Role of abnormal microRNA expression in Helicobacter pylori associated gastric cancer

Epidemiological studies have shown that Helicobacter pylori (HP) infection is a risk factor for gastric cancer (GC). HP infection may induce the release of pro-inflammatory mediators, and abnormally increase the level of reactive oxygen species (ROS), nitric oxide (NO), and cytokines in mucosal epithelial cells of the stomach. However, the specific mechanism underlying the pathogenesis of HP-associated GC is still poorly understood. Recent studies have revealed that abnormal microRNA expression may affect the proliferation, differentiation, and apoptosis of mucosal epithelial cells of the stomach to further influence GC occurrence, development, and metastasis. Herein, we summarize the role of abnormal microRNAs in the regulation of HP-associated GC progression. Abnormal microRNA expression in HP-positive GC may be a biomarker for GC diagnosis, occurrence, and development as well as its targeted treatment and prognosis.

Unusual Manifestation of Live Staphylococcus saprophyticus, Corynebacterium urinapleomorphum, and Helicobacter pylori in the Gallbladder with Cholecystitis

Culture-independent studies have identified DNA of bacterial pathogens in the gallbladder under pathological conditions, yet reports on the isolation of corresponding live bacteria are rare. Thus, it is unclear which pathogens, or pathogen communities, can colonize the gallbladder and cause disease. Using light microscopy, scanning electron microscopy, culture techniques, phylogenetic analysis, urease assays and Western blotting, we investigated the presence of live bacterial communities in the gallbladder of a cholecystitis patient after cholecystectomy. 16S rRNA gene sequencing of isolated bacterial colonies revealed the presence of pathogens most closely resembling Corynebacterium urinapleomorphum nov. sp., Staphylococcus saprophyticus and Helicobacter pylori. The latter colonies were confirmed as H. pylori by immunohistochemistry and biochemical methods. H. pylori cultured from the gallbladder exhibited both the same DNA fingerprinting and Western cagA gene sequence with ABC-type EPIYA (Glu-Pro-Ile-Tyr-Ala) phosphorylation motifs as isolates recovered from the gastric mucus of the same patient, suggesting that gastric H. pylori can also colonize other organs in the human body. Taken together, here we report, for the first time, the identification and characterization of a community consisting of live S. saprophyticus; C. urinapleomorphum, and H. pylori in the gallbladder of a patient with acute cholecystitis. Their potential infection routes and roles in pathogenesis are discussed.

Colonic Abnormalities in Manitoban Children with Helicobacter pylori Gastritis

Objectives

Association between Helicobacter pylori (H. pylori) and colonic pathology is underinvestigated. The aim of this work was to examine the prevalence and nature of colonic changes in children diagnosed with H. pylori gastritis.

Methods

A comprehensive retrospective review of the medical records for all Manitoban children (≤17 years) diagnosed with H. pylori gastritis from January 1996 to May 2015 was conducted. Children with H. pylori gastritis who had colonoscopy were identified. Patients' demographics, indications for colonoscopy, laboratory and endoscopic findings, and colonic histopathological abnormalities were documented.

Results

A total of 231 children were found to have H. pylori gastritis. The mean age at diagnosis was 12.3 ± 4.1 years; 108 (46.6%) were girls. Of the 231 patients, 37 (16%) patients were found to have colonoscopy performed. Indications for colonoscopy included bleeding per rectum, significant weight loss, and hypoalbuminemia. Twenty-two (59%) of 37 children who had colonoscopy had significant endoscopic and histopathological findings on colonoscopy including polyposis and colitis. Boys with colonic changes were diagnosed at an earlier age compared to those without (11.5 ± 7.0 versus 15.0 ± 2.0, p < 0.049).

Conclusions

Our study may suggest a possible association between H. pylori and a subset of colonic changes in children.

Amino-Terminal Processing of Helicobacter pylori Serine Protease HtrA: Role in Oligomerization and Activity Regulation

The HtrA family of serine proteases is found in most bacteria, and plays an essential role in the virulence of the gastric pathogen Helicobacter pylori. Secreted H. pylori HtrA (HtrA ^Hp ) cleaves various junctional proteins such as E-cadherin disrupting the epithelial barrier, which is crucial for bacterial transmigration across the polarized epithelium. Recent studies indicated the presence of two characteristic HtrA ^Hp forms of 55 and 52 kDa (termed p55 and p52, respectively), in worldwide strains. In addition, p55 and p52 were produced by recombinant HtrA ^Hp , indicating auto-cleavage. However, the cleavage sites and their functional importance are yet unclear. Here, we determined the amino-terminal ends of p55 and p52 by Edman sequencing. Two proteolytic cleavage sites were identified (H46/D47 and K50/D51). Remarkably, the cleavage site sequences are conserved in HtrA ^Hp from worldwide isolates, but not in other Gram-negative pathogens, suggesting a highly specific assignment in H. pylori. We analyzed the role of the amino-terminal cleavage sites on activity, secretion and function of HtrA ^Hp . Three-dimensional modeling suggested a trimeric structure and a role of amino-terminal processing in oligomerization and regulation of proteolytic activity of HtrA ^Hp . Furthermore, point and deletion mutants of these processing sites were generated in the recently reported Campylobacter jejuni ΔhtrA/htrA^Hp genetic complementation system and the minimal sequence requirements for processing were determined. Polarized Caco-2 epithelial cells were infected with these strains and analyzed by immunofluorescence microscopy. The results indicated that HtrA ^Hp processing strongly affected the ability of the protease to disrupt the E-cadherin-based cell-to-cell junctions. Casein zymography confirmed that the amino-terminal region is required for maintaining the proteolytic activity of HtrA ^Hp . Furthermore, we demonstrated that this cleavage influences the secretion of HtrA ^Hp in the extracellular space as an important prerequisite for its virulence activity. Taken together, our data demonstrate that amino-terminal cleavage of HtrA ^Hp is conserved in this pathogen and affects oligomerization and thus, secretion and regulatory activities, suggesting an important role in the pathogenesis of H. pylori.

Bartonella Species, an Emerging Cause of Blood-Culture-Negative Endocarditis

Since the reclassification of the genus Bartonella in 1993, the number of species has grown from 1 to 45 currently designated members. Likewise, the association of different Bartonella species with human disease continues to grow, as does the range of clinical presentations associated with these bacteria. Among these, blood-culture-negative endocarditis stands out as a common, often undiagnosed, clinical presentation of infection with several different Bartonella species. The limitations of laboratory tests resulting in this underdiagnosis of Bartonella endocarditis are discussed. The varied clinical picture of Bartonella infection and a review of clinical aspects of endocarditis caused by Bartonella are presented. We also summarize the current knowledge of the molecular basis of Bartonella pathogenesis, focusing on surface adhesins in the two Bartonella species that most commonly cause endocarditis, B. henselae and B. quintana. We discuss evidence that surface adhesins are important factors for autoaggregation and biofilm formation by Bartonella species. Finally, we propose that biofilm formation is a critical step in the formation of vegetative masses during Bartonella-mediated endocarditis and represents a potential reservoir for persistence by these bacteria.

Store-operated Ca2+ Entry Facilitates the Lipopolysaccharide-induced Cyclooxygenase-2 Expression in Gastric Cancer Cells

Helicobacter pylori has been identified as one of the major causes of chronic gastritis, gastric and duodenal ulcers, and gastric cancer. Lipopolysaccharide (LPS) is a major component of the outer membrane of gram-negative bacteria, and H. pylori LPS might play an exclusively important role in activating inflammatory pathways in monocytes and macrophages. To study the role of LPS in the underlying mechanism of inflammatory responses, we established an in vitro model using the human AGS gastric cancer cell line. We found that LPS mediates inflammation through setting off a cascade of events: activation of the store-operated calcium (SOC) channel, initiation of downstream NF-κB signaling, and phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2). Phosphorylated ERK1/2 promotes the nuclear translocation of NF-κB, and eventually elevates the expression level of COX-2, a major inflammatory gene.

Pathogen-induced ubiquitin-editing enzyme A20 bifunctionally shuts off NF-κB and caspase-8-dependent apoptotic cell death

The human pathogen Helicobacter pylori infects more than half of the world’s population and is a paradigm for persistent yet asymptomatic infection but increases the risk for chronic gastritis and gastric adenocarcinoma. For successful colonization, H. pylori needs to subvert the host cell death response, which serves to confine pathogen infection by killing infected cells and preventing malignant transformation. Infection of gastric epithelial cells by H. pylori provokes direct and fast activation of the proinflammatory and survival factor NF-κB, which regulates target genes, such as CXCL8, BIRC3 and TNFAIP3. However, it is not known how H. pylori exploits NF-κB activation and suppresses the inflammatory response and host apoptotic cell death, in order to avert the innate immune response and avoid cell loss, and thereby enhance colonization to establish long-term infection. Here we assign for the first time that H. pylori and also Campylobacter jejuni-induced ubiquitin-editing enzyme A20 bifunctionally terminates NF-κB activity and negatively regulates apoptotic cell death. Mechanistically, we show that the deubiquitinylase activity of A20 counteracts cullin3-mediated K63-linked ubiquitinylation of procaspase-8, therefore restricting the activity of caspase-8. Interestingly, another inducible NF-κB target gene, the scaffold protein p62, ameliorates the interaction of A20 with procaspase-8. In conclusion, pathogen-induced de novo synthesis of A20 regulates the shut-off of the survival factor NF-κB but, on the other hand, also impedes caspase-8-dependent apoptotic cell death so as to promote the persistence of pathogens.

Usefulness of Housekeeping Genes for the Diagnosis of Helicobacter pylori Infection, Strain Discrimination and Detection of Multiple Infection

BACKGROUND

Helicobacter pylori infects human stomachs of over half the world's population, evades the immune response and establishes a chronic infection. Although most people remains asymptomatic, duodenal and gastric ulcers, MALT lymphoma and progression to gastric cancer could be developed. Several virulence factors such as flagella, lipopolysaccharide, adhesins and especially the vacuolating cytotoxin VacA and the oncoprotein CagA have been described for H. pylori. Despite the extensive published data on H. pylori, more research is needed to determine new virulence markers, the exact mode of transmission or the role of multiple infection.

MATERIALS AND METHODS

Amplification and sequencing of six housekeeping genes (amiA, cgt, cpn60, cpn70, dnaJ, and luxS) related to H. pylori pathogenesis have been performed in order to evaluate their usefulness for the specific detection of H. pylori, the genetic discrimination at strain level and the detection of multiple infection. A total of 52 H. pylori clones, isolated from 14 gastric biopsies from 11 patients, were analyzed for this purpose.

RESULTS

All genes were specifically amplified for H. pylori and all clones isolated from different patients were discriminated, with gene distances ranged from 0.9 to 7.8%. Although most clones isolated from the same patient showed identical gene sequences, an event of multiple infection was detected in all the genes and microevolution events were showed for amiA and cpn60 genes.

CONCLUSIONS

These results suggested that housekeeping genes could be useful for H. pylori detection and to elucidate the mode of transmission and the relevance of the multiple infection.

Helicobacter pylori infection in nonsteroidal anti-inflammatory drug users

NSAID-induced upper gastrointestinal (GI) damage occurs easily in people with a prior history of complicated or uncomplicated ulcers. Many recent clinical studies have proved the benefit of Helicobacter pylori eradication in NSAID users; however, the exact pathophysiologic relationship between concomitant H. pylori infection and NSAID use has not yet been fully elucidated. Testing and eradication of H. pylori are generally recommended in patients who are at a high risk for NSAID-induced GI damage. However, in high-risk patients, ulcer prophylaxis with proton pump inhibitor or misoprostol is needed even if H. pylori has been successfully eradicated. In low-risk patients, it is still questionable whether or not eradication of H. pylori can reduce upper GI damage. However, in western countries, due to its cost effectiveness, testing and eradication of H. pylori is recommended before starting aspirin or NSAID irrespective of the risk level. In regions with a high prevalence of H. pylori infection (>20%), the usefulness of testing and eradication of H. pylori has not yet been determined.

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.

Role of Helicobacter pylori infection in pathogenesis of gastric carcinoma

Gastric cancer (GC) is one of the most common carcinoma and the second leading cause of cancer-related deaths worldwide. Helicobacter pylori (H. pylori) infection causes a series of precancerous lesions like gastritis, atrophy, intestinal metaplasia and dysplasia, and is the strongest known risk factor for GC, as supported by epidemiological, preclinical and clinical studies. However, the mechanism of H. pylori developing gastric carcinoma has not been well defined. Among infected individuals, approximately 10% develop severe gastric lesions such as peptic ulcer disease, 1%-3% progresses to GC. The outcomes of H. pylori infection are determined by bacterial virulence, genetic polymorphism of hosts as well as environmental factors. It is important to gain further understanding of the pathogenesis of H. pylori infection for developing more effective treatments for this common but deadly malignancy. The recent findings on the bacterial virulence factors, effects of H. pylori on epithelial cells, genetic polymorphism of both the bacterium and its host, and the environmental factors for GC are discussed with focus on the role of H. pylori in gastric carcinogenesis in this review.

Aggravation of Helicobacter pylori stomach infections in stressed military recruits

Objective

To investigate the effect of military stress on immune response and Helicobacter pylori stomach infections.

Methods

In this prospective, observational study, the Symptom Checklist-90 questionnaire was completed by military recruits before and following a 3-month basic training programme. H. pylori immunoglobulin (Ig)G levels, C¹⁴-urea breath-test values and levels of cortisol, catecholamine, and certain humoral and cellular immune responses were measured before and after the basic training.

Results

For 60 military recruits, somatization, depression and paranoid ideation scores were significantly increased after, compared with before, basic training. Post-training H. pylori IgG detection revealed three additional cases of H. pylori infection. Post-training C¹⁴-urea breath-test values were significantly higher compared with before training – thus suggesting higher levels of H. pylori colonization in the stomach. Post-training cortisol and catecholamine levels were increased, while serum IgG levels were decreased; complement component (C)3 and C4 levels remained unchanged. Post-training CD4⁺ and CD8⁺ T-cell percentages and the CD4⁺/CD8⁺ ratio were significantly reduced compared with before training. Serum interleukin (IL)-2 levels were lower and IL-10 levels were higher following training and there was a significant decrease in the IL-2/IL-10 ratio.

Conclusion

Military stress may reduce humoral and cellular immune responses and may aggravate the severity of H. pylori infection.

Passive Immunization

Whereas active immunity refers to the process of exposing the individual to an antigen to generate an adaptive immune response, passive immunity refers to the transfer of antibodies from one individual to another. Passive immunity provides immediate but short-lived protection, lasting several weeks up to 3 or 4 months. Passive immunity can occur naturally, when maternal antibodies are transferred to the fetus through the placenta or from breast milk to the gut of the infant. It can also be produced artificially, when antibody preparations derived from sera or secretions of immunized donors or, more recently, different antibody producing platforms are transferred via systemic or mucosal route to nonimmune individuals. Passive immunization has recently become an attractive approach because of the emergence of new and drug-resistant microorganisms, diseases that are unresponsive to drug therapy and individuals with an impaired immune system who are unable to respond to conventional vaccines. This chapter addresses the contributions of natural and artificial acquired passive immunity in understanding the concept of passive immunization. We will mainly focus on administration of antibodies for protection against various infectious agents entering through mucosal surfaces.

Expression, purification and X-ray crystallographic analysis of the Helicobacter pylori blood group antigen-binding adhesin BabA

Helicobacter pylori is a human pathogen that colonizes about 50% of the world's population, causing chronic gastritis, duodenal ulcers and even gastric cancer. A steady emergence of multiple antibiotic resistant strains poses an important public health threat and there is an urgent requirement for alternative therapeutics. The blood group antigen-binding adhesin BabA mediates the intimate attachment to the host mucosa and forms a major candidate for novel vaccine and drug development. Here, the recombinant expression and crystallization of a soluble BabA truncation (BabA(25-460)) corresponding to the predicted extracellular adhesin domain of the protein are reported. X-ray diffraction data for nanobody-stabilized BabA(25-460) were collected to 2.25 Å resolution from a crystal that belonged to space group P21, with unit-cell parameters a = 50.96, b = 131.41, c = 123.40 Å, α = 90.0, β = 94.8, γ = 90.0°, and which was predicted to contain two BabA(25-460)-nanobody complexes per asymmetric unit.

Helicobacter pylori infection introduces DNA double-strand breaks in host cells

Gastric cancer is an inflammation-related malignancy related to long-standing acute and chronic inflammation caused by infection with the human bacterial pathogen Helicobacter pylori. Inflammation can result in genomic instability. However, there are considerable data that H. pylori itself can also produce genomic instability both directly and through epigenetic pathways. Overall, the mechanisms of H. pylori-induced host genomic instabilities remain poorly understood. We used microarray screening of H. pylori-infected human gastric biopsy specimens to identify candidate genes involved in H. pylori-induced host genomic instabilities. We found upregulation of ATM expression in vivo in gastric mucosal cells infected with H. pylori. Using gastric cancer cell lines, we confirmed that the H. pylori-related activation of ATM was due to the accumulation of DNA double-strand breaks (DSBs). DSBs were observed following infection with both cag pathogenicity island (PAI)-positive and -negative strains, but the effect was more robust with cag PAI-positive strains. These results are consistent with the fact that infections with both cag PAI-positive and -negative strains are associated with gastric carcinogenesis, but the risk is higher in individuals infected with cag PAI-positive strains.

Beyond the stomach: An updated view of Helicobacter pylori pathogenesis, diagnosis, and treatment

Helicobacter pylori (H. pylori) is an extremely common, yet underappreciated, pathogen that is able to alter host physiology and subvert the host immune response, allowing it to persist for the life of the host. H. pylori is the primary cause of peptic ulcers and gastric cancer. In the United States, the annual cost associated with peptic ulcer disease is estimated to be $6 billion and gastric cancer kills over 700000 people per year globally. The prevalence of H. pylori infection remains high (> 50%) in much of the world, although the infection rates are dropping in some developed nations. The drop in H. pylori prevalence could be a double-edged sword, reducing the incidence of gastric diseases while increasing the risk of allergies and esophageal diseases. The list of diseases potentially caused by H. pylori continues to grow; however, mechanistic explanations of how H. pylori could contribute to extragastric diseases lag far behind clinical studies. A number of host factors and H. pylori virulence factors act in concert to determine which individuals are at the highest risk of disease. These include bacterial cytotoxins and polymorphisms in host genes responsible for directing the immune response. This review discusses the latest advances in H. pylori pathogenesis, diagnosis, and treatment. Up-to-date information on correlations between H. pylori and extragastric diseases is also provided.

Helicobacter pylori infection activates Src homology-2 domain-containing phosphatase 2 to suppress IFN-γ signaling

Helicobacter pylori infection not only induces gastric inflammation but also increases the risk of gastric tumorigenesis. IFN-γ has antimicrobial effects; however, H. pylori infection elevates IFN-γ-mediated gastric inflammation and may suppress IFN-γ signaling as a strategy to avoid immune destruction through an as-yet-unknown mechanism. This study was aimed at investigating the mechanism of H. pylori-induced IFN-γ resistance. Postinfection of viable H. pylori decreased IFN-γ-activated signal transducers and activators of transcription 1 and IFN regulatory factor 1 not only in human gastric epithelial MKN45 and AZ-521 but also in human monocytic U937 cells. H. pylori caused an increase in the C-terminal tyrosine phosphorylation of Src homology-2 domain-containing phosphatase (SHP) 2. Pharmacologically and genetically inhibiting SHP2 reversed H. pylori-induced IFN-γ resistance. In contrast to a clinically isolated H. pylori strain HP238, the cytotoxin-associated gene A (CagA) isogenic mutant strain HP238(CagAm) failed to induce IFN-γ resistance, indicating that CagA regulates this effect. Notably, HP238 and HP238(CagAm) differently caused SHP2 phosphorylation; however, imaging and biochemical analyses demonstrated CagA-mediated membrane-associated binding with phosphorylated SHP2. CagA-independent generation of reactive oxygen species (ROS) contributed to H. pylori-induced SHP2 phosphorylation; however, ROS/SHP2 mediated IFN-γ resistance in a CagA-regulated manner. This finding not only provides an alternative mechanism for how CagA and ROS coregulate SHP2 activation but may also explain their roles in H. pylori-induced IFN-γ resistance.

Epigenetic silencing of miR-210 increases the proliferation of gastric epithelium during chronic Helicobacter pylori infection

Persistent colonization of the gastric mucosa by Helicobacter pylori (Hp) elicits chronic inflammation and aberrant epithelial cell proliferation, which increases the risk of gastric cancer. Here we examine the ability of microRNAs to modulate gastric cell proliferation in response to persistent Hp infection and find that epigenetic silencing of miR-210 plays a key role in gastric disease progression. Importantly, DNA methylation of the miR-210 gene is increased in Hp-positive human gastric biopsies as compared with Hp-negative controls. Moreover, silencing of miR-210 in gastric epithelial cells promotes proliferation. We identify STMN1 and DIMT1 as miR-210 target genes and demonstrate that inhibition of miR-210 expression augments cell proliferation by activating STMN1 and DIMT1 . Together, our results highlight inflammation-induced epigenetic silencing of miR-210 as a mechanism of induction of chronic gastric diseases, including cancer, during Hp infection.

Chronic infection with the bacterium Helicobacter pylori is associated with inflammation and increased risk of gastric cancer. Kiga et al. show that methylation and silencing of the microRNA gene miR-210 is associated with infection in humans, and promotes proliferation of gastric epithelial cells in culture.

Repetitive sequence variations in the promoter region of the adhesin-encoding gene sabA of Helicobacter pylori affect transcription

The pathogenesis of diseases elicited by the gastric pathogen Helicobacter pylori is partially determined by the effectiveness of adaptation to the variably acidic environment of the host stomach. Adaptation includes appropriate adherence to the gastric epithelium via outer membrane protein adhesins such as SabA. The expression of sabA is subject to regulation via phase variation in the promoter and coding regions as well as repression by the two-component system ArsRS. In this study, we investigated the role of a homopolymeric thymine [poly(T)] tract -50 to -33 relative to the sabA transcriptional start site in H. pylori strain J99. We quantified sabA expression in H. pylori J99 by quantitative reverse transcription-PCR (RT-PCR), demonstrating significant changes in sabA expression associated with experimental manipulations of poly(T) tract length. Mimicking the length increase of this tract by adding adenines instead of thymines had similar effects, while the addition of other nucleotides failed to affect sabA expression in the same manner. We hypothesize that modification of the poly(T) tract changes DNA topology, affecting regulatory protein interaction(s) or RNA polymerase binding efficiency. Additionally, we characterized the interaction between the sabA promoter region and ArsR, a response regulator affecting sabA expression. Using recombinant ArsR in electrophoretic mobility shift assays (EMSA), we localized binding to a sequence with partial dyad symmetry -20 and +38 relative to the sabA +1 site. The control of sabA expression by both ArsRS and phase variation at two distinct repeat regions suggests the control of sabA expression is both complex and vital to H. pylori infection.

Helicobacter pylori TlyA agglutinates liposomes and induces fusion and permeabilization of the liposome membranes

Helicobacter pylori TlyA is a pore-forming hemolysin with potent cytotoxic activity. To explore the potential membrane-damaging activity of H. pylori TlyA, we have studied its interaction with the synthetic liposome vesicles. In our study, H. pylori TlyA shows a prominent ability to associate with the liposome vesicles without displaying an obligatory requirement for any protein receptor on the liposome membranes. Interaction of TlyA triggers agglutination of the liposome vesicles. Such agglutinating activity of TlyA could also be observed with erythrocytes before the induction of its pore-forming hemolytic activity. In addition to its agglutinating activity against liposomes, TlyA also induces fusion and disruption of the liposome membranes. Altogether, our study highlights novel membrane-damaging properties of H. pylori TlyA that have not been documented previously with any other TlyA family protein.

Seroprevalence of Helicobacter pylori infection in Polish children and adults depending on socioeconomic status and living conditions

PURPOSE

Helicobacter pylori (H. pylori) is one of the causes of gastritis, peptic ulcer disease, gastric cancer and MALT-lymphoma. The frequency of H. pylori infection is different in various regions of the world and dependent on age, socioeconomic and hygiene status. The objective of this study was to assess seroprevalence and the associated socioeconomic and sociodemographic characteristics influencing H. pylori infection in children and adults in Polish population.

MATERIAL/METHODS

In multicenter epidemiological studies, H. pylori infection occurrence was assessed in Poland in the years 2002 and 2003. The seroprevalence of H. pylori infection diagnosis was based on IgG anti-H. pylori antibodies concentration above 24 UI/ml, which was measured using ELISA test. The study included 6565 subjects: 3307 adults (50.37%) and 3258 children (49.63%).

RESULTS

Positive result was observed in 3827 subjects (58.29%), i.e. 1043 children (32.01%) and 2784 adults (84.19%). H. pylori infection prevalence was greater in children of poor economic status, who were born in a rural area, lived in crowded houses with no running tap water and with toilet outside the house, and who did not observe hygiene rules. In adults, the factors predisposing to higher probability of being H. pylori infected included: being born in a rural area, having low family income and elementary education, smoking tobacco, drinking high proof alcohols as well as not observing of hygiene rules.

CONCLUSIONS

Improvement of socioeconomic status, sanitary and hygienic conditions and the education of the society might decrease H. pylori infection prevalence in children and in adults.

Probiotic screening and safety evaluation of Lactobacillus strains from plants, artisanal goat cheese, human stools, and breast milk

The aim of this study was to select autochthonous strains of Lactobacillus from stools of healthy infants and adults, human milk, artisanal goat cheese, and fruits and vegetables according to their probiotic properties and safety. From 421 strains of Lactobacillus isolated, 102 (24.2%) were shown to be tolerant to gastric pH and bile salts; they were used to determine their anti-Helicobacter pylori (agar diffusion assay), antioxidant (oxygen radical absorption capacity), and anti-inflammatory (inhibition of interleukin-8 release by tumor necrosis factor-α-stimulated HT-29 cells) activities as well as their ability to adhere to intestinal (Caco-2) and gastric (AGS) epithelial cells. Results obtained were compared with three commercial probiotic Lactobacillus rhamnosus GG, L. plantarum 299v, and L. johnsonii NCC533. The five strains most efficient according to these activities were subsequently identified by sequencing their 16S rRNA gene, their susceptibility to antibiotics was determined, and their safety evaluated in mice. One strain of L. plantarum was discarded due to the higher prevalence of liver bacterial translocation observed in the animals fed this strain. In conclusion, four autochthonous strains of L. rhamnosus were finally selected with probiotic properties and safety allowing their eventual use in human studies. These results contribute to increase the diversity of probiotic strains available for the development of nutraceuticals and functional foods.

Functional characterization of Helicobacter pylori TlyA: pore-forming hemolytic activity and cytotoxic property of the protein

Helicobacter pylori is a human specific gastric pathogen. H. pylori pathogenesis process involves a number of well-studied virulence factors that include the 'vacuolating cytotoxin' and the 'cytotoxin associated gene A'. Analysis of the H. pylori genome, however, indicates presence of additional virulence factors that are yet to be characterized in molecular detail. For example, H. pylori genome harbors a gene that has potential to encode a protein with sequence similarity to those of the TlyA-like proteins of several pathogenic bacteria. Earlier studies have indicated potential association of this H. pylori tlyA gene in the virulence mechanism of the organism. Despite such notions, however, the TlyA-like protein of H. pylori has not been studied previously in molecular detail. In particular, purified form of H. pylori TlyA has never been studied before toward exploring its functional properties. Here, we report characterization of the H. pylori TlyA protein purified from the recombinant over-expression system in Escherichia coli. Purified form of the recombinant TlyA exhibits prominent hemolytic activity against human erythrocytes, presumably via formation of pores of specific diameter in the cell membrane. Purified TlyA also triggers prominent cytotoxic responses in human gastric adenocarcinoma cells. Altogether, our study establishes H. pylori TlyA as a potential virulence factor of the organism.

Mechanism and structure of the bacterial type IV secretion systems

The bacterial type IV secretion systems (T4SSs) translocate DNA and protein substrates to bacterial or eukaryotic target cells generally by a mechanism dependent on direct cell-to-cell contact. The T4SSs encompass two large subfamilies, the conjugation systems and the effector translocators. The conjugation systems mediate interbacterial DNA transfer and are responsible for the rapid dissemination of antibiotic resistance genes and virulence determinants in clinical settings. The effector translocators are used by many Gram-negative bacterial pathogens for delivery of potentially hundreds of virulence proteins to eukaryotic cells for modulation of different physiological processes during infection. Recently, there has been considerable progress in defining the structures of T4SS machine subunits and large machine subassemblies. Additionally, the nature of substrate translocation sequences and the contributions of accessory proteins to substrate docking with the translocation channel have been elucidated. A DNA translocation route through the Agrobacterium tumefaciens VirB/VirD4 system was defined, and both intracellular (DNA ligand, ATP energy) and extracellular (phage binding) signals were shown to activate type IV-dependent translocation. Finally, phylogenetic studies have shed light on the evolution and distribution of T4SSs, and complementary structure-function studies of diverse systems have identified adaptations tailored for novel functions in pathogenic settings. This review summarizes the recent progress in our understanding of the architecture and mechanism of action of these fascinating machines, with emphasis on the 'archetypal' A. tumefaciens VirB/VirD4 T4SS and related conjugation systems. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.

Association between Helicobacter pylori infection and pathological changes in the gastric mucosa in Chinese children

OBJECTIVE

H. pylori infection in children has a high prevalence worldwide. The disease can cause progressive gastric mucosal inflammation, as verified in animal models. However, data from large-scale clinical studies are limited.

METHODS

We examined 1,634 Chinese children with upper gastrointestinal discomfort using endoscopy. The clinical and pathological data of the patients were analyzed.

RESULTS

A total of 524 (32.1%) patients were infected with H. pylori, and the prevalence of H. pylori infection increased with age. The H. pylori-infected patients exhibited a significantly higher prevalence of active inflammation (26.9% vs. 4.1%), lymphoid follicle formation (18.5% vs. 4.6%) and marked lymphocyte infiltration (19.7% vs. 5.6%). The H. pylori-infected patients also exhibited a significantly higher prevalence of moderate to marked chronic superficial gastritis (41.9% vs. 9.2%) and moderate chronic atrophic gastritis (21.7% vs. 2.6%) than the uninfected patients (p<0.01).

CONCLUSION

H. pylori infection is associated with the degree of gastric mucosal inflammation and the severity of different types of chronic gastritis.

Host genetic factors respond to pathogenic step-specific virulence factors of Helicobacter pylori in gastric carcinogenesis

The interindividual differences in risk of Helicobacter pylori (H. pylori)-associated gastric cancer involve significant heterogeneities of both host genetics and H. pylori strains. Several recent studies proposed a distinct sequence for H. pylori exerting its virulence in the host stomach: (i) adhering to and colonizing the surface of gastric epithelial cells, (ii) evading and attenuating the host defense, and (iii) invading and damaging the gastric mucosa. This review focuses on several key issues that still need to be clarified, such as which virulence factors of H. pylori are involved in the three pathogenic steps, which host genes respond to the step-specific virulence factors, and whether and/or how the corresponding host genetic variations influence the risk of gastric carcinogenesis. Urease, BabA and SabA in the adhesion-step, PGN and LPS in the immune evasion-step, and CagA, VacA and Tipα in the mucosal damage-step were documented to play an important role in step-specific pathogenicity of H. pylori infection. There is evidence further supporting a role of potentially functional polymorphisms of host genes directly responding to these pathogenic step-specific virulence factors in the susceptibility of gastric carcinogenesis, especially for urease-interacting HLA class II genes, BabA-interacting MUC1, PGN-interacting NOD1, LPS-interacting TLR4, and CagA-interacting PTPN11 and CDH1. With the continuous improvement of understanding the genetic profile of H. pylori-associated gastric carcinogenesis, a person at increased risk for gastric cancer may benefit from several aspects of efforts: (i) prevent H. pylori infection with a vaccine targeting certain step-specific virulence factor; (ii) eradicate H. pylori infection by blocking step-specific psychopathological characteristics of virulence factors; and (iii) adjust host physiological function to resist the carcinogenic role of step-specific virulence factors or interrupt the cellular signal transduction of the interplay between H. pylori and host in each pathogenic step, especially for the subjects with precancerous lesions in the stomach.