Pathogenesis of Helicobacter pylori infection

Integrin-Linked Kinase in the Development of Gastric Tumors Induced by Helicobacter pylori: Regulation and Prevention Potential

BACKGROUND

Integrin-linked kinase (ILK) is crucial in solid tumors by regulating the Hippo-Yes-associated protein 1 (YAP) pathway. This study aimed to uncover how Helicobacter pylori influences ILK levels and its role in regulating YAP during H. pylori-induced gastric cancer.

MATERIALS AND METHODS

GES-1 cells with stable Ilk knockdown and overexpression and a mouse carcinogenesis model for H. pylori infection were constructed. And ILK, the phosphorylated mammalian STE20-like protein kinase 1 (MST1), large tumor suppressor 1 (LATS1; S909, T1079), and YAP (S109, S127) were detected in cells, and mice by western blotting, as well as fluorescence intensity of YAP were assayed by immunofluorescence. YAP downstream genes Igfbp4 and Ctgf, the pathological changes and tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), interleukin-1beta (IL-1β), and nitric oxide (NO) levels in mice gastric tissues were detected by real-time PCR, H&E, and ELISA assays.

RESULTS

In this study, stable Ilk knockdown cells exhibited significantly higher phosphorylated levels of MST1, LATS1, and YAP, as well as increased YAP in the nuclei of GES-1 cells. Conversely, cells with Ilk overexpression showed opposite results. H. pylori infection led to decreased ILK levels in gastric epithelial cells but increased ILK levels in gastric cancer cell lines (MGC803, SGC7901) and gastric cancer tissues in mice. Treatment with the ILK inhibitor OST-T315 elevated the phosphorylated MST, LATS1, and YAP levels, and inhibited the mRNA levels of Igfbp4 and Ctgf at 44, 48 week-aged mice. OST-T315 also reduced the release of TNF-α, IL-6, IL-1β, and NO, as well as the progression of gastric cancer caused by H. pylori and N-Nitroso-N-methylurea (NMU) treatment.

CONCLUSION

Upon initiation of gastric tumorigenesis signals, H. pylori increases ILK levels and suppresses Hippo signaling, thereby promoting YAP activation and gastric cancer progression. ILK can serve as a potential prevention target to impede H. pylori-induced gastric cancer.

An M cell-targeting recombinant L. lactis vaccine against four H. pylori adhesins

The acidic environment and enzyme degradation lead to oral vaccines often having little immune effect. Therefore, it is an attractive strategy to study an effective and safe oral vaccine delivery system that can promote gastrointestinal mucosal immune responses and inhibit antigen degradation. Moreover, the antigens uptake by microfold cells (M cells) is the determining step in initiating efficient immune responses. Therefore, M cell-targeting is one promising approach for enhancing oral vaccine potency. In the present study, an M cell-targeting L. lactis surface display system (plSAM) was built to favor the multivalent epitope vaccine antigen (FAdE) to achieve effective gastrointestinal mucosal immunity against Helicobacter pylori. Therefore, a recombinant Lactococcus lactic acid vaccine (LL-plSAM-FAdE) was successfully prepared, and its immunological properties and protective efficacy were analyzed. The results showed that LL-plSAM-FAdE can secretively express the recombinant proteins SAM-FAdE and display the SAM-FAdE on the bacterial cell surface. More importantly, LL-plSAM-FAdE effectively promoted the phagocytosis and transport of vaccine antigen by M cells in the gastrointestinal tract of mice, and simulated high levels of cellular and humoral immune responses against four key H. pylori adhesins (Urease, CagL, HpaA, and Lpp20) in the gastrointestinal tract, thus enabling effective prevention of H. pylori infection and to some extent eliminating H. pylori already present in the gastrointestinal tract. KEY POINTS: • M-cell-targeting L. lactis surface display system LL- plSAM was designed • This system displays H. pylori vaccine-promoted phagocytosis and transport of M cell • A promising vaccine candidate for controlling H. pylori infection was verified.

Chloroquine inhibited Helicobacter pylori-related gastric carcinogenesis by YAP-β-catenin-autophagy axis

YAP participates in autophagy associated with many diseases. In this study, we demonstrate that YAP promotes autophagy by interacting with beclin 1, upregulating beclin 1 and LC3B-II protein expression, and promoting autophagosome formation after H. pylori infection in a vacuolating cytotoxin A-dependent manner. The protein levels of β-catenin in the cytoplasm and nuclei of GES-1 cells and the mRNA levels of Axin2, Myc, Lgr5, and Ccnd1 were increased in H. pylori-infected cells or YAP-overexpressed cells, but were decreased in YAP-silenced cells. The β-catenin inhibitor XAV939 significantly downregulated autophagy, whereas the activator LiCl showed opposite effects. An H. pylori-infected mouse model of gastric carcinoma was successfully established. The mouse model showed that H. pylori infection, when combined with NMU, promoted the tumorigenesis of gastric tissues; increased IL-1β, IL-6, and TNF-α levels; promoted NO release; and increased the expression of beclin 1, LC3B-II more than NMU alone. Chloroquine inhibited these phenomena, but did not completely attenuate the effects of H. pylori. These results demonstrate that chloroquine can be used as a drug for the treatment of H. pylori-related gastric cancer, but the treatment should simultaneously remove H. pylori.

Advanced Sensing Strategies Based on Different Types of Biomarkers toward Early Diagnosis of H. pylori

Helicobacter pylori (H. pylori) is a bacterium that can colonize human gastric epithelial cells and cause H. pylori infection, closely related to many gastric diseases. Compared with conventional H. pylori detection methods, emerging diagnostic approaches (such as biosensors) have become potentially more effective alternatives due to their high sensitivity, good selectivity and noninvasiveness. This review begins with a brief overview of H. pylori infection, the processes that lead to diseases, and current diagnostic methods. Subsequently, advanced biosensors in different target-based for diagnosing H. pylori infection are focused, including the detection of H. pylori-related nucleic acid, H. pylori-related protein (such as the cytotoxin, urease), and intact H. pylori. In addition, prospects for the development of H. pylori detection methods are also discussed in the end.

A Novel Gastric Spheroid Co-culture Model Reveals Chemokine-Dependent Recruitment of Human Dendritic Cells to the Gastric Epithelium

BACKGROUND & AIMS

Gastric dendritic cells (DCs) control the adaptive response to infection with Helicobacter pylori, a major risk factor for peptic ulcer disease and gastric cancer. We hypothesize that DC interactions with the gastric epithelium position gastric DCs for uptake of luminal H pylori and promote DC responses to epithelial-derived mediators. The aim of this study was to determine whether the gastric epithelium actively recruits DCs using a novel co-culture model of human gastric epithelial spheroids and monocyte-derived DCs.

METHODS

Spheroid cultures of primary gastric epithelial cells were infected with H pylori by microinjection. Co-cultures were established by adding human monocyte-derived DCs to the spheroid cultures and were analyzed for DC recruitment and antigen uptake by confocal microscopy. Protein array, gene expression polymerase chain reaction array, and chemotaxis assays were used to identify epithelial-derived chemotactic factors that attract DCs. Data from the co-culture model were confirmed using human gastric tissue samples.

RESULTS

Human monocyte-derived DCs co-cultured with gastric spheroids spontaneously migrated to the gastric epithelium, established tight interactions with the epithelial cells, and phagocytosed luminally applied H pylori. DC recruitment was increased upon H pylori infection of the spheroids and involved the activity of multiple chemokines including CXCL1, CXCL16, CXCL17, and CCL20. Enhanced chemokine expression and DC recruitment to the gastric epithelium also was observed in H pylori-infected human gastric tissue samples.

CONCLUSIONS

Our results indicate that the gastric epithelium actively recruits DCs for immunosurveillance and pathogen sampling through chemokine-dependent mechanisms, with increased recruitment upon active H pylori infection.

Expression of tryptophan hydroxylase in gastric mucosa in symptomatic and asymptomatic Helicobacter pylori infection

INTRODUCTION

Helicobacter pylori infection induces clinical symptoms in 15-20% of subjects, and the reason for this variation is still not clear. The aim of the present study is to evaluate the expression of tryptophan hydroxylase (TpH-1) in gastric mucosa of patients with symptomatic and asymptomatic H. pylori infection in relation to the intensity of bacterial colonization and severity of dyspeptic symptoms.

MATERIAL AND METHODS

Ninety subjects (aged 35-49 years) were enrolled in the study and separated into 3 groups of 30 subjects each. Group I - healthy volunteers without H. pylori infection, group II - subjects with asymptomatic H. pylori infection, group III - H. pylori-infected patients with dyspeptic symptoms, mainly fasting and nocturnal epigastric pain. To diagnose H. pylori infection the urea breath test (UBT-13C) and histological analysis were performed. The level of mRNA expression of tryptophan hydroxylase (TpH-1) was estimated in gastric mucosa with RT-PCR.

RESULTS

The expression of this enzyme in antral mucosa was 2.69 ±0.97 in group I, 2.28 ±0.69 in group II (p > 0.05) and 4.40 ±1.64 in group III (p < 0.001). The levels of expression of TpH-1 in gastric body mucosa were 2.16 ±0.70, 1.57 ±0.52 (p > 0.05) and 3.40 ±1.51 (p < 0.001), respectively. In group III a positive correlation was found between intensity of H. pylori colonization and TpH-1 expression as well as between TpH-1 expression and severity of dyspeptic symptoms.

CONCLUSIONS

Increased expression of TpH-1 in gastric mucosa plays a role in pathogenesis of chronic dyspepsia.

Regulatory Effects of Black Rice Extract on Helicobacter pylori Infection-Induced Apoptosis

SCOPE

Black rice extract (BRE) contains cyanidin 3-O-glucoside (C3G), an anthocyanin, as the major component. In this study, we found that BRE inhibits the mRNA and protein expression of genes encoding cytotoxin-associated protein A (cagA) and vacuolating protein A (vacA) in Helicobacter pylori 60190 strain.

METHODS AND RESULTS

We performed RT-PCR and western blotting to show that BRE inhibits the mRNA and protein expression of SecA. Because SecA is involved in VacA export in bacteria, our result suggests a positive correlation between BRE-induced inhibition of secA expression and VacA secretion. Further, we perform MTT assay and flow cytometry to show that BRE decreases the apoptosis of H. pylori-infected KATO III cells. Finally, we perform western blotting to show that the cell-protective effect of BRE is associated with decreased levels of active proapoptotic proteins caspases and PARP and increased levels of antiapoptotic proteins survivin and XIAP in H. pylori-infected cells.

CONCLUSION

Thus, our results indicate that BRE acts as a potent inhibitor of the biogenesis of H. pylori virulence proteins and decreases the apoptosis of H. pylori-infected cells. Moreover, our results suggest that BRE can be used to exert beneficial effects in patients with gastroduodenal diseases caused by H. pylori.

Helicobacter pylori antigenic Lpp20 is a structural homologue of Tipα and promotes epithelial-mesenchymal transition

BACKGROUND

Helicobacter pylori is a bacterium that affects about 50% of the world population and, despite being often asymptomatic, it is responsible of several gastric diseases, from gastritis to gastric cancer. The protein Lpp20 (HP1456) plays an important role in bacterium survival and host colonization, but the possibility that it might be involved in the etiology of H. pylori-related disorders is an unexplored issue. Lpp20 is a lipoprotein bound to the external membrane of the bacterium, but it is also secreted inside vesicles along with other two proteins of the same operon, i.e. HP1454 and HP1457.

RESULTS

In this study we determined the crystal structure of Lpp20 and we found that it has a fold similar to a carcinogenic factor released by H. pylori, namely Tipα. We demonstrate that Lpp20 promotes cell migration and E-cadherin down-regulation in gastric cancer cells, two events recalling the epithelial-mesenchymal transition (EMT) process. Differently from Tipα, Lpp20 also stimulates cell proliferation.

CONCLUSIONS

This identifies Lpp20 as a new pathogenic factor produced by H. pylori that promotes EMT and thereby the progression of cancer to the metastatic state.

Effects of anti-Helicobacter pylori concomitant therapy and probiotic supplementation on the throat and gut microbiota in humans

The microbiota within humans maintains homeostasis and plays important roles in human health. However, some situations such as the use of antibiotics may disrupt the microbiota balance and result in a series of adverse effects. This study aimed to investigate the effects of a commonly used anti-Helicobacter pylori concomitant therapy on the composition of the gut and throat microbiota and any antibiotic resistance that may develop. In addition to the standard regimen, two different supplementary probiotic regimens that both used Saccharomyces boulardii were included. Microbiological culture-based techniques were used to analyse the microbiota composition and antibiotic resistance. Our results showed marked quantitative and qualitative alterations in both the gut and throat microbiota after treatment with not only the standard concomitant therapy but also with either supplementary probiotic regimen. Nevertheless, most of the changes in the gut microbiota (except for yeast and Bacteroides spp. counts) reverted by Day 71, whereas the alterations in the throat microbiota appeared to persist. Patients treated with the eradication therapy in the absence of probiotic supplementation experienced the most pronounced disturbances in the throat microbiota, whereas changes in the throat microbiota appeared to stabilize in the groups that received probiotic supplementation. We also detected higher antibiotic resistance rates for Enterobacteriaceae, Enterococcus spp. and Bacteroides spp. after treatment with the eradication therapy. Co-administration of probiotics is likely to be more effective than post-antibiotic supplementation, and although some beneficial effects were observed, the probiotic combination did not exert significant effects on the unbalanced commensal gut and throat microbiota composition.

Microbial strain-level population structure and genetic diversity from metagenomes

Among the human health conditions linked to microbial communities, phenotypes are often associated with only a subset of strains within causal microbial groups. Although it has been critical for decades in microbial physiology to characterize individual strains, this has been challenging when using culture-independent high-throughput metagenomics. We introduce StrainPhlAn, a novel metagenomic strain identification approach, and apply it to characterize the genetic structure of thousands of strains from more than 125 species in more than 1500 gut metagenomes drawn from populations spanning North and South American, European, Asian, and African countries. The method relies on per-sample dominant sequence variant reconstruction within species-specific marker genes. It identified primarily subject-specific strain variants (<5% inter-subject strain sharing), and we determined that a single strain typically dominated each species and was retained over time (for >70% of species). Microbial population structure was correlated in several distinct ways with the geographic structure of the host population. In some cases, discrete subspecies (e.g., for Eubacterium rectale and Prevotella copri) or continuous microbial genetic variations (e.g., for Faecalibacterium prausnitzii) were associated with geographically distinct human populations, whereas few strains occurred in multiple unrelated cohorts. We further estimated the genetic variability of gut microbes, with Bacteroides species appearing remarkably consistent (0.45% median number of nucleotide variants between strains), whereas P. copri was among the most plastic gut colonizers. We thus characterize here the population genetics of previously inaccessible intestinal microbes, providing a comprehensive strain-level genetic overview of the gut microbial diversity.

Peptic Ulcer Disease and Helicobacter pylori Infection in Different Siberian Ethnicities

BACKGROUND

The high prevalence of Helicobacter pylori (H. pylori) infection in eastern Siberia is consistently established. In the same geographic area, however, fragmentary information is available on the epidemiology of the peptic ulcer disease (PUD).

AIM

To assess the prevalence of H. pylori infection (including CagA status) and PUD in different eastern Siberian ethnicities.

PATIENTS AND METHODS

An endoscopy population of 3149 eastern Siberian dyspeptic patients was considered [1727 Europoids and 1422 Mongoloids (Evenks = 792; Khakases = 630)]. H. pylori status was assessed by urease test and/or serum anti-H. pylori IgG and/or histology. CagA status was serologically assessed (anti-CagA antibodies).

RESULTS

All the Siberian ethnicities featured high rates of H. pylori infection (Europoids = 87.1%, Evenks = 88.6%, Khakases = 85.4%). Among the 1504 H. pylori-positive Europoids, the prevalence of CagA-positive status (68.7%) was significantly higher than that featured by the 1240 H. pylori-positive Mongoloid ethnicities (46.9%; p < .001 for both comparisons). Peptic ulcer disease significantly prevailed among Europoids (prevalence among Europoid Evenks and Khakases: 8.9% and 8.3%, respectively; prevalence among Mongoloid Evenks and Khakases = 1.0% and 4.4%, respectively).

CONCLUSIONS

eastern Siberian populations feature consistent high rates of H. pylori infection, but different prevalence of peptic ulcer disease. In particular, Europoids featured a prevalence of both CagA-positive status and peptic ulcer disease significantly higher than that of the Mongoloid ethnicities. These results suggest that both environmental factors (coexisting with the H. pylori infection) and host-related variables modulate the clinicopathological expression of the H. pylori -associated gastric diseases.

The Role of H. pylori CagA in Regulating Hormones of Functional Dyspepsia Patients

Helicobacter pylori (H. pylori, Hp) colonizes the stomachs of approximately 20%–80% of humans throughout the world. The Word Healthy Organization (WHO) classified H. pylori as a group 1 carcinogenic factor in 1994. Recently, an increasing number of studies has shown an association between H. pylori infection and various extragastric diseases. Functional dyspepsia (FD) is considered a biopsychosocial disorder with multifactorial pathogenesis, and studies have shown that infection with CagA-positive H. pylori strains could explain some of the symptoms of functional dyspepsia. Moreover, CagA-positive H. pylori strains have been shown to affect the secretion of several hormones, including 5-HT, ghrelin, dopamine, and gastrin, and altered levels of these hormones might be the cause of the psychological disorders of functional dyspepsia patients. This review describes the mutual effects of H. pylori and hormones in functional dyspepsia and provides new insight into the pathogenesis of functional dyspepsia.

Clarithromycin resistance and prevalence of Helicobacter pylori virulent genotypes in patients from Southern México with chronic gastritis

In developing countries, clarithromycin resistance and frequency of re-infection are factors that contribute to high prevalence of Helicobacter pylori infection. The aim of this research was determine the prevalence of clarithromycin resistance and its relation with A2142G, A2142C and A2143G mutations in the domain V of the 23S rRNA gene of H. pylori isolates in patients from Southern Mexico with chronic gastritis. Another purpose of this work was to study the prevalence of virulent genotypes and distribution of resistant strains according to the vacA/cagA/babA2 H. pylori genotypes. One hundred forty-four patients with chronic gastritis were studied. Forty-five H. pylori strains were isolated and clarithromycin susceptibility was determined by the disk-diffusion method. The 82.2% of the strains had the combination of alleles vacA s1 m1 and the cagA gene was detected in 77.8% and 40% of the strains were babA2 positive. The vacA s1 m1 genotype was detected more frequently in cagA(+) strains, vacA s1m1/cagA(+)/babA2(-) genotype was more frequent than vacA s1m1/cagA(+)/babA2(+), 37.8% and 33.3%, respectively. Eight strains were clarithromycin resistant, in three of these, point mutations were identified, but only in one strain the A2143G mutation associated with clarithromycin resistance was found. Other point mutations (A1821G, G1826A, T1830C, A2089G, T1600C, C1601T, C1602T, T1610C, A1611C and T1633G) that have not been associated with clarithromycin resistance were identified. The highest proportion of resistant strains was vacA s1m1/cagA(+) (62.5%). In patients from southern Mexico with chronic gastritis, the prevalence of clarithromycin resistance is within internationally accepted range (17.8%) and allows continued use of triple therapy for H. pylori eradication. However, it is necessary to monitor the evolution of clarithromycin resistance in this area. The largest proportion of resistant H. pylori strains is not harboring the A2142G, A2142C and A2143G mutations in the 23S rRNA gene (87.5%). The vacA s1m1/cagA(+) genotype was the most prevalent and among clarithromycin-resistant strains, this was the predominant.

Gastric adenocarcinoma: the role of Helicobacter pylori in pathogenesis and prevention efforts

Gastric cancer is the third most common cause of cancer deaths in the world, prompting high-risk countries like South Korea and Japan to establish nationwide screening programmes. Helicobacter pylori is linked to the majority of gastric adenocarcinoma cases and to the vast majority of non-cardia gastric adenocarcinomas. Several studies have demonstrated the effectiveness of 'test-and-treat' programmes for H. pylori infection to prevent gastric cancer in high-risk populations. While this strategy has gained momentum, providers in low-risk developed countries may be unaware of the risk individual patients face, particularly those who have emigrated from high-risk regions and members of economically disadvantaged minority groups. Rapidly evolving science in recent years has made it difficult for clinicians to keep up with the current best practices. This article reviews the epidemiology of H. pylori and gastric cancer, screening and diagnostic tests and the current treatment regimens for clinicians.

Vaccine against Helicobacter pylori: Inevitable approach

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

Novel anti-Helicobacter pylori therapies

Helicobacter pylori is a ubiquitous gastropathogen infecting more than half of the world population. It is associated with dyspepsia, gastritis, gastroduodenal ulcers, mucus-associated lymphoid tissue lymphoma and gastric carcinoma. Current recommended therapy does not eradicate infection in all treated cases and at least 20% post-treatment patients continue to suffer. Salvage therapy helps some of these nonresponders, but resistance to available antibiotics is mounting. Hence, its treatment still remains a daunting task for the practicing physician. Novel medications with improved efficacy and tolerability and with less chances of resistance are required. The present review attempts to discuss the newer patents in this field, which demonstrate a promising future role in the management of H. pylori infection and its consequent problems.

Noncoding Genomics in Gastric Cancer and the Gastric Precancerous Cascade: Pathogenesis and Biomarkers

Gastric cancer is the fifth most common cancer and the third leading cause of cancer-related death, whose patterns vary among geographical regions and ethnicities. It is a multifactorial disease, and its development depends on infection by Helicobacter pylori (H. pylori) and Epstein-Barr virus (EBV), host genetic factors, and environmental factors. The heterogeneity of the disease has begun to be unraveled by a comprehensive mutational evaluation of primary tumors. The low-abundance of mutations suggests that other mechanisms participate in the evolution of the disease, such as those found through analyses of noncoding genomics. Noncoding genomics includes single nucleotide polymorphisms (SNPs), regulation of gene expression through DNA methylation of promoter sites, miRNAs, other noncoding RNAs in regulatory regions, and other topics. These processes and molecules ultimately control gene expression. Potential biomarkers are appearing from analyses of noncoding genomics. This review focuses on noncoding genomics and potential biomarkers in the context of gastric cancer and the gastric precancerous cascade.

Molecular Mechanisms of Helicobacter pylori Pathogenesis

Helicobacter pylori infects 50% of mankind. The vast majority of H. pylori infection occurs in the developing countries where up to 80% of the middle-aged adults may be infected. Bacterial infection causes an inflammatory response that proceeds through a series of intermediated stages of precancerous lesions (gastritis, atrophy, intestinal metaplasia, and dysplasia). Among infected individuals, approximately 10% develops severe gastric lesions such as peptic ulcer disease, 1-3% progresses to gastric cancer (GC) with a low 5-year survival rate, and 0.1% develops mucosa-associated lymphoid tissue (MALT). GC is one of the most common cancer and the third leading cause of cancer-related deaths worldwide. In this review, we have summarized the most recent papers about molecular mechanisms of H. pylori pathogenesis. The main important steps of H. pylori infection such as adhesion, entry in epithelial gastric cells, activation of intracellular pathways until epigenetic modifications have been described.

Helicobacter pylori virulence factor CagA promotes tumorigenesis of gastric cancer via multiple signaling pathways

Helicobacter pylori (H. pylori) infection is strongly associated with the development of gastric diseases but also with several extragastric diseases. The clinical outcomes caused by H. pylori infection are considered to be associated with a complex combination of host susceptibility, environmental factors and bacterial isolates. Infections involving H. pylori strains that possess the virulence factor CagA have a worse clinical outcome than those involving CagA-negative strains. It is remarkable that CagA-positive H. pylori increase the risk for gastric cancer over the risk associated with H. pylori infection alone. CagA behaves as a bacterial oncoprotein playing a key role in H. pylori-induced gastric cancer. Activation of oncogenic signaling pathways and inactivation of tumor suppressor pathways are two crucial events in the development of gastric cancer. CagA shows the ability to affect the expression or function of vital protein in oncogenic or tumor suppressor signaling pathways via several molecular mechanisms, such as direct binding or interaction, phosphorylation of vital signaling proteins and methylation of tumor suppressor genes. As a result, CagA continuously dysregulates of these signaling pathways and promotes tumorigenesis. Recent research has enriched our understanding of how CagA effects on these signaling pathways. This review summarizes the results of the most relevant studies, discusses the complex molecular mechanism involved and attempts to delineate the entire signaling pathway.

The crystal structure of Helicobacter pylori HP1029 highlights the functional diversity of the sialic acid-related DUF386 family

The proteins of the YhcH/YjgK/YiaL (DUF386) family have been implicated in the bacterial metabolism of host-derived sialic acids and biofilm formation, although their precise biochemical function remains enigmatic. We present here the crystal structure of protein HP1029 from Helicobacter pylori. The protein is a homodimer, in which each monomer comprises a molecular core formed by 12 antiparallel β-strands arranged in two β-sheets flanked by helices. The sandwich formed by the sheets assumes the shape of a funnel opened at one end, with a zinc ion present at the bottom of the funnel. The crystal structure unequivocally shows that HP1029 belongs to the DUF386 family. Although no bioinformatics evidence has been found for sialic acid catabolism in H. pylori, the genomic context of HP1029 in Helicobacter and related organisms suggests a possible role in the metabolism of bacterial surface saccharides, such as pseudaminic acid and its derivatives.

Application of recombinant Helicobacter pylori outer inflammatory protein A peptide for diagnosis of high virulent Helicobacter pylori infection

AIM: To evaluate the feasibility of recombinant Helicobacter pylori (H. pylori) outer inflammatory protein A (OipA) peptide as a clinical diagnostic agent for high virulent H. pylori infection.

METHODS: Serum and gastric mucosa biopsy specimens were obtained from 285 patients who underwent gastroscopy. H. pylori strains were isolated from urease positive samples and some urease negative samples. Isolated strains were identified by microscopy, urease test and 16S rRNA PCR. OipA and cytotoxin-associated gene A (cagA) of the isolates were obtained by PCR and the oipA signal region was analyed after sequencing. OipA antibody in serum specimen was detected using purified recombinant OipA6 peptide, and CagA antibody was detected by indirect ELISA using a commercial kit. The results of oipA gene and OipA antibody as well as OipA antibody and CagA antibody were compared. The feasibility of OipA6 as a diagnostic agent for high virulent H. pylori infection was evaluated.

RESULTS: A total of 83 isolated H. pylori were obtained, of which 66 was positive for oipA signal region (signal region was on in 62, and undefined in 4), and 59 was positive for cagA. The sensitivity, specificity and consistency rate of recombination antigen OipA6 were 95.16%, 95.83% and 95.28%, respectively, which were all higher than those of CagA (77.97%, 87.50% and 80.72%).

CONCLUSION: Recombinant OipA peptide may be used as an antigen for detection of high virulent H. pylori infection.

Association between Helicobacter pylori and extra-gastric diseases

Helicobacter pylori (H. pylori) is confirmed to be associated with many diseases such as gastric cancer, peptic ulcer, gastritis and mucosa-associated lymphoid tissue lymphoma. Recent studies found that H. pylori is associated with many extra-gastric diseases. The underlying mechanism involves autoimmunity, inflammation and oxidative stress. Here we review the association between H. pylori and extra-gastric diseases.

Review: prospects for the use of extracts and polysaccharides from marine algae to prevent and treat the diseases caused by Helicobacter pylori

Helicobacter pylori possesses a broad spectrum of pathogenic factors that allow it to survive and colonize the gastric mucosa, and thus, the pathogenetic targets, which have the same diversity, require search for and the development of alternative, effective, and innocuous means for the eradication of H. pylori. In recent years, fucoidans have been extensively studied due to the numerous interesting biological activities, including the anti-adhesive, anti-oxidative, antitoxic, immunomodulatory, anticoagulant, and anti-infection effects. This review summarizes the data on the effects of extracts and sulfated polysaccharides of marine algae, mainly fucoidans, on pathogenic targets in Helicobacter infection. The pathogenetic targets for therapeutic agents after H. pylori infection, such as flagellas, urease, and other enzymes, including adhesins, cytotoxin A (VacA), phospholipase, and L-8, are characterized here. The main target for the sulfated polysaccharides of seaweed is cell receptors of the gastric mucosa. This review presents the published data about the pleiotropic anti-inflammatory effects of polysaccharides on the gastric mucosa. It is known that fucoidan and other sulfated polysaccharides from algae have anti-ulcer effects, prevent the adhesion of H. pylori to, and reduce the formation of biofilm. The authors speculate that the effect of sulfated polysaccharides on the infectious process caused by H. pylori is related to their action on innate and adaptive immunity cells, and also anti-oxidant and antitoxic potential. Presented in the review are materials indicated for the study of extracts and sulfated polysaccharides from seaweed during H. pylori infection, as these compounds are characterized by multimodality actions. Based on the analysis of literary materials in recent years, the authors concluded that fucoidan can be attributed to the generation of new candidates to create drugs intended for the inclusion in the scheme of eradication therapy of H. pylori infection.

Helicobacter pylori γ-glutamyl transpeptidase-induced Ca(2+) release via PLC-IP3 receptors in AGS cells

In our previous study, γ-glutamyl transpeptidase (GGT) isolated from Helicobacter pylori induced apoptosis of AGS cells. Here, we investigate Ca(2+) effects on GGT-induced apoptosis. The GGT transiently and significantly increased intracellular Ca(2+) concentration ([Ca(2+)]i) in AGS cells in a dose-dependent manner (P < 0.05). The GGT-induced Ca(2+) increase resulted from Ca(2+) influx and release through the phospholipase C - inositol 1,4,5-trisphosphate (PLC-IP3) pathway. The GGT-induced apoptosis was significantly reduced by treatment with U73122 (a PLC inhibitor) and xestospongin (an IP3 receptor antagonist) (P < 0.05). These results indicate that GGT could induce apoptosis of AGS cells by high levels of [Ca(2+)]i.

H. pylori infection, inflammation and gastric cancer

INTRODUCTION

A strong association between chronic infection, inflammation, and cancer has been suggested.

DISCUSSION

Helicobacter pylori, a microaerophilic gram negative bacterium, infects about half the world's population. It has been defined as a definitive carcinogen in the pathogenesis of gastric cancer. H. pylori evades the host immune responses and persists in the stomach leading to gastritis gastric atrophy and sometimes gastric cancer.

CONCLUSION

Chronic H. pylori infection causes gastric cancer via two mechanisms: the presence of virulence factors and the induction of chronic inflammation which ultimately leads to neoplastic transformation.

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.

Occurrence of Helicobacter pylori and Epstein-Barr virus infection in endoscopic and gastric cancer patients from Northern Brazil

BACKGROUND

Helicobacter pylori (HP) and Epstein-Barr virus (EBV) have been associated with cancer development. We evaluated the prevalence of HP, HP CagA+ and EBV infection in gastric cancer (GC) samples from adults and in gastric tissues from patients who underwent upper endoscopy (UE).

METHODS

Samples from UE and GC were collected to investigate the presence of HP infection and the HP virulence factor CagA by a urease test and PCR. The presence of EBV was detected by Eber-1 in situ hybridization.

RESULTS

In UE, 85.5% of juvenile patients showed some degree of gastritis (45.3% of patients with mild gastritis and 54.7% with moderate/severe gastritis) and patients with mild gastritis were younger than patients with moderate/severe gastritis. Among adults, 48.7% presented mild gastritis and 51.3% moderate/severe gastritis. HP infection was detected in 0% of normal mucosa, 58.5% of juvenile gastritis patients, 69.2% of adult gastritis patients and 88% of GC patients. In these same groups, HP CagA+ was detected in 0%, 37.7%, 61.5% and 67.2% of tissue samples, respectively. In juvenile patients, HP infection was more common in those with gastritis than in normal samples (p = 0.004). The patients with either HP or HP CagA+ were older than patients without these pathogens (p < 0.05). In juvenile patients, HP infection was more frequent in cases of moderate/severe gastritis than in cases of mild gastritis (p = 0.026). Moreover, in patients with GC, HP infection was more frequent in males than in females (p = 0.023). GC patients with HP CagA+ were older than patients with HP CagA- (p = 0.027). HP CagA+ was more common in intestinal-type than diffuse-type GC (p = 0.012). HP CagA+ was also associated with lymph-node (p = 0.024) and distal (p = 0.005) metastasis. No association between EBV infection and HP infection or any clinicopathological variable was detected.

CONCLUSIONS

Our results suggest that HP is involved in the pathophysiology of severe gastric lesions and in the development of GC, particularly when CagA+ is present. EBV was not the primary pathogenic factor in our samples.

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.

Comparison of standard triple therapy, sequential therapy and moxifloxacin-based triple therapy for Helicobacter pylori infection: Patients' compliance and bacterial eradication rates

OBJECTIVE

To compare the patients' compliance with and the efficacy of existing treatments for Helicobacter pylori eradication, including moxifloxacin-based triple therapy, sequential treatment and the standard treatment.

METHODS

Patients with H. pylori infection were randomly assigned to three therapy groups. The triple therapy (MML) group was given moxifloxacin 400 mg/day, metronidazole 500 mg b.i.d. and lansoprazole 30 mg b.i.d. for 10 days. The sequential treatment (AL-CML) group was administrated amoxicillin 1 g b.i.d. and lansoprazole 30 mg b.i.d. for the first 5 days, followed by clarithromycin 500 mg b.i.d., metronidazole 500 mg b.i.d. and lansoprazole 30 mg b.i.d. for the second 5 days. The standard treatment (CAL) group received amoxicillin 1 g b.i.d., clarithromycin 500 mg b.i.d. and lansoprazole 30 mg b.i.d. for 14 days. The eradication rates were evaluated by per-protocol (PP) analysis and intention-to-treat (ITT) analysis.

RESULTS

The eradication rates were 87.1, 85.9 and 85.2% by PP analysis and 87.1, 84.9 and 84.2% by ITT analysis in the MML, AL-CML and CAL group, respectively, and patients' compliance rates were 98.2, 96.5 and 97.1%, respectively. There were no significant differences in treatment efficacy and compliance rates in the MML, AL-CML and CAL groups (P > 0.05).

CONCLUSIONS

The present study revealed that standard triple therapy, sequential therapy and moxifloxacin-based triple therapy are all effective treatment regimens in terms of H. pylori eradication rates and compliance with therapy in Turkey.

Outer membrane inflammatory protein A, a new virulence factor involved in the pathogenesis of Helicobacter pylori

Outer membrane proteins (OMPs) represent an important class of proteins that are observed in gram-negative bacteria, mitochondria and chloroplasts. These proteins play diverse biological roles in protein translocation, cell-cell communication and signal transduction. A variety of OMPs have been identified in the gastrointestinal pathogen Helicobacter pylori (H. pylori) since it was first isolated in 1983. Among these proteins, outer membrane inflammatory protein A (OipA), which is encoded by hopH and unique to this pathogen, is a differentially expressed outer membrane protein that has been confirmed to be directly linked to H. pylori colonization, as well as to the pathogenesis of H. pylori and disease outcome. In this review, we will describe the progress of recent studies on OipA, particularly those on the functions and biological significance of this unique protein.

Prevalence of the Helicobacter pylori babA2 gene and correlation with the degree of gastritis in infected Slovenian children

The aims of our study were to determine the prevalence of the babA2 gene within Helicobacter pylori strains circulating in the Slovenian pediatric population, to further clarify its significance in causing inflammation of gastric mucosa in children and to verify whether cagA, vacA, iceA and babA genes work independently or synergistically in causing gastritis. A total of 163 H. pylori isolates obtained from the same number of children were tested for the presence of cagA, vacA and iceA genes using previously established methods, while the babA2 gene was determined using novel polymerase chain reaction assay targeting a 139-bp fragment of the central region of babA2. The babA2 gene was detected in 47.9% of H. pylori samples. The presence of the babA2 gene was strongly associated with cagA, vacA s1 and vacA m1 genotype. The babA2 status correlated positively with bacterial density score, activity of inflammation and chronic inflammation of gastric mucosa. No significant correlation was found between the babA2 status and the presence of atrophy or intestinal metaplasia. In addition, the activity of gastric inflammation and density score were significantly associated with the coexpression of the cagA, vacA s1, vacA m1 and babA2 genes. The study, which included the largest number of pediatric H. pylori samples to date, confirmed that babA2 gene plays an important role in the pathogenesis of H. pylori gastritis in children. Furthermore, our results suggest that babA2, cagA and vacA s1 and m1 gene products may work synergistically in worsening the inflammation of gastric mucosa.

An association between Helicobacter pylori and upper respiratory tract disease: Fact or fiction?

Helicobacter pylori (H. pylori) is a major cause of chronic gastritis and gastric ulcers and considerable evidence supports the notion that infection with this bacterium is also associated with gastric malignancy in addition to various other conditions including pulmonary, vascular and autoimmune disorders. Gastric juice infected with H. pylori might play an important role in upper respiratory tract infection. Although direct and/or indirect mechanisms might be involved in the association between H. pylori and upper respiratory tract diseases, the etiological role of H. pylori in upper respiratory tract disorders has not yet been fully elucidated. Although various studies over the past two decades have suggested a relationship between H. pylori and upper respiratory tract diseases, the findings are inconsistent. The present overview describes the outcomes of recent investigations into the impact of H. pylori on upper respiratory tract and adjacent lesions.

Serum antibody against Helicobacter pylori FlaA and risk of gastric cancer

BACKGROUND

Helicobacter pylori (H. pylori) infection is a major risk factor for gastric cancer (GC); however, only a minority of infected individuals develops GC. We aim to assess the association between serostatus of antibody against H. pylori flagellin A (FlaA) and risk of GC and to evaluate the value of serum FlaA antibody as a novel screening biomarker for GC risk.

METHODS

A hospital-based case-control study including 232 cases and 264 controls was conducted. Logistic regression was adopted to analyze the association between the serostatus of FlaA antibody and risk of GC. Serum FlaA antibody was measured by an enzyme-linked immunosorbent assay (ELISA). Receiver operating characteristic (ROC) curve was used to evaluate the screening efficacy and to identify a cutoff point of serum FlaA antibody level.

RESULTS

Helicobacter pylori infection was associated with an increased risk of GC (p = .007). A positive association between serum FlaA antibody and GC risk was observed in overall subjects and H. pylori-positive subjects (OR [95% CI]: 6.8 [4.3-10.7] and 6.9 [3.6-13.4], respectively; p < .001). The seropositivity of FlaA antibody was strongly related to GC risk in a dose-dependent manner (p for trend < .001). The optimal cutoff value (OD) was 0.1403, providing a sensitivity of 74.1% and a specificity of 64.4%. The area under the ROC curve (AUC) was 0.74 in overall subjects and 0.73 in H. pylori-positive subjects, respectively.

CONCLUSIONS

FlaA was an independent risk factor for H. pylori-related GC. Serum FlaA antibody may serve as a novel noninvasive biomarker for early detection of GC.

Is esophagogastroduodenoscopy before Roux-en-Y gastric bypass or sleeve gastrectomy mandatory?

BACKGROUND

Roux-Y Gastric Bypass is a frequently used technique in bariatric surgery. Postoperative anatomy is altered by exclusion of the stomach, which makes this organ inaccessible for future esophagogastroduodenoscopy (EGD). The value of preoperative assessment of the stomach is unclear. Some institutions choose to investigate the future remnant stomach by EGD, others do not. Aim of the present study is to quantify the yield of preoperative EGD in our institution.

METHODS

Patients, planned for primary laparoscopic Roux-Y Gastric Bypass (LRYGB) or laparoscopic sleeve gastrectomy from December 2007 until August 2012, were screened by EGD in advance. Results of EGD and patient characteristics were retrospectively analyzed and categorized according to a classification system based on intervention needed.

RESULTS

523 patients (122 male, 401 female, mean age 44.3 years, average BMI 46.6) underwent preoperative EGD. In 257 patients (48.9%) no abnormality was found (group A), 117 patients (17.2%) had abnormalities without treatment consequences (B1), 84 patients (of the 326 tested [comment #1, reviewer #1, 26.8%] were H. Pylori positive (B2), in 75 (14.3%) treatment with proton pump inhibitors was required (B3), 6 (1.1%) required follow up EGD before surgery (C). For1 patient (0.2%) the operation was canceled because preoperative EGD presented with Barrett's esophagus with carcinoma (D). When all abnormalities were taken into account, baselines did show a significant difference for age, gender and reflux symptoms.

CONCLUSION

Standard preoperative assessment by EGD in patients who are planned for bariatric surgery is not indicated. The number needed to screen to find clinically significant abnormalities is high.

Association of presence/absence and on/off patterns of Helicobacter pylori oipA gene with peptic ulcer disease and gastric cancer risks: a meta-analysis

BACKGROUND

There are increasing studies examining the relationship between the status of H. pylori oipA gene and peptic ulcer disease (PUD) and gastric cancer (GC) but the results turn out to be controversial. We attempted to clarify whether oipA gene status is linked with PUD and/or GC risks.

METHODS

A systematically literature search was performed through four electronic databases. According to the specific inclusion and exclusion criteria, seven articles were ultimately available for the meta-analysis of oipA presence/absence with PUD and GC, and eleven articles were included for the meta-analysis of oipA on/off status with PUD and GC.

RESULTS

For the on/off functional status analysis of oipA gene, the "on" status showed significant associations with increased risks of PUD (OR = 3.97, 95% CI: 2.89, 5.45; P < 0.001) and GC (OR = 2.43, 95% CI: 1.45, 4.07; P = 0.001) compared with gastritis and functional dyspepsia controls. Results of the homogeneity test indicated different effects of oipA "on" status on PUD risk between children and adult subgroups and on GC risk between PCR-sequencing and immunoblot subgroups. For the presence/absence analysis of oipA gene, we found null association of the presence of oipA gene with the risks of PUD (OR = 1.93, 95% CI: 0.60, 6.25; P = 0.278) and GC (OR = 2.09, 95% CI: 0.51, 8.66; P = 0.308) compared with gastritis and functional dyspepsia controls.

CONCLUSIONS

To be concluded, when oipA exists, the functional "on" status of this gene showed association with increased risks for PUD and GC compared with gastritis and FD controls. However, merely investigating the presence/absence of oipA would overlook the importance of its functional on/off status and would not be reliable to predict risks of PUD and GC. Further large-scale and well-designed studies concerning on/off status of oipA are required to confirm our meta-analysis results.

Helicobacter pylori-Induced Chronic Gastritis and Assessing Risks for Gastric Cancer

Chronic gastritis is an inflammation of the gastric mucosa and has multiple etiologies. Here we discuss the pathological alterations induced by Helicobacter pylori (HP) leading to chronic gastritis and the epigenetic bases underlying these changes. We review the histology of the normal gastric mucosa and overview the role of HP in the multistep cascade of GC. We attempt to define the role of the Operative Link for Gastritis Assessment (OLGA) staging system in assessing the risk of GC. The epigenetic bases of chronic gastritis, mainly DNA methylation, are presented through examples such as (i) the methylation of the promoter region of E-cadherin in HP-induced chronic gastritis and its reversion after HP eradication and (ii) the association of methylation of the promoter region of Reprimo, a p53-mediated cell cycle arrest gene, with aggressive HP strains in high risk areas for GC. In addition, we discuss the finding of RPRM as a circulating cell-free DNA, offering the opportunity for noninvasive risk assessment of GC. Finally, the integration of OLGA and tissue biomarkers, by systems pathology approach, suggests that severe atrophy has a greater risk for GC development if, in addition, overexpressed p73. This trial is registered with ClinicalTrials.gov NCT01774266.

Inhibitory effects of anthocyanins on secretion of Helicobacter pylori CagA and VacA toxins

Anthocyanins have been studied as potential antimicrobial agents against Helicobacter pylori. We investigated whether the biosynthesis and secretion of cytotoxin-associated protein A (CagA) and vacuolating cytotoxin A (VacA) could be suppressed by anthocyanin treatment in vitro. H. pylori reference strain 60190 (CagA(+)/VacA(+)) was used in this study to investigate the inhibitory effects of anthocyanins; cyanidin 3-O-glucoside (C3G), peonidin 3-O-glucoside (Peo3G), pelargonidin 3-O-glucoside (Pel3G), and malvidin 3-O-glucoside (M3G) on expression and secretion of H. pylori toxins. Anthocyanins were added to bacterial cultures and Western blotting was used to determine secretion of CagA and VacA. Among them, we found that C3G inhibited secretion of CagA and VacA resulting in intracellular accumulation of CagA and VacA. C3G had no effect on cagA and vacA expression but suppressed secA transcription. As SecA is involved in translocation of bacterial proteins, the down-regulation of secA expression by C3G offers a mechanistic explanation for the inhibition of toxin secretion. To our knowledge, this is the first report suggesting that C3G inhibits secretion of the H. pylori toxins CagA and VacA via suppression of secA transcription.