Pattern of transcription factor activation in Helicobacter pylori-infected Mongolian gerbils

Binding of YY1/CREB to an Enhancer Region Triggers Claudin 6 Expression in H. pylori LPS-Stimulated AGS Cells

Aberrant expression of the tight junction protein claudin 6 (CLDN6) is a hallmark of gastric cancer progression. Its expression is regulated by the cAMP response element-binding protein (CREB). In gastric cancer induced by Helicobacter pylori (H. pylori) there is no information regarding what transcription factors induce/upregulate the expression of CLDN6. We aimed to identify whether CREB and Yin Yang1 (YY1) regulate the expression of CLDN6 and the site where they bind to the promoter sequence. Bioinformatics analysis, H. pylori lipopolysaccharide (LPS), YY1 and CREB silencing, Western blot, luciferase assays, and chromatin immunoprecipitation experiments were performed using the stomach gastric adenocarcinoma cell line AGS. A gen reporter assay suggested that the initial 2000 bp contains the regulatory sequence associated with CLDN6 transcription; the luciferase assay demonstrated three different regions with transcriptional activity, but the -901 to -1421 bp region displayed the maximal transcriptional activity in response to LPS. Fragment 1279-1421 showed CREB and, surprisingly, YY1 occupancy. Sequential Chromatin Immunoprecipitation (ChIP) experiments confirmed that YY1 and CREB interact in the 1279-1421 region. Our results suggest that CLDN6 expression is regulated by the binding of YY1 and CREB in the 901-1421 enhancer, in which a non-described interaction of YY1 with CREB was established in the 1279-1421 region.

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

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

Animal Models and Helicobacter pylori Infection

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

The role of toll-like receptors in peptic ulcer disease

Helicobacter pylori (HP) is the primary etiologic factor that induces events in the immune system that lead to peptic ulcers. Toll-like receptors (TLRs) are an important part of the innate immune system, as they play pivotal roles in pathogen-associated molecular pattern (PAMP) recognition of HP as well host-associated damage-associated molecular patterns (DAMPs). Recent advancements such as COX-2 production, LPS recognition through TLR2, CagL, and CagY protein of HP activating TLR5, TLR9 activation via type IV secretion system (T4SS) using DNA transfer, TLR polymorphisms, their adaptor molecules, cytokines, and other factors play a significant role in PUD. Thus, some novel PUD treatments including Chuyou Yuyang granules, function by TLR4/NF-κB signaling pathway suppression and TNF-α and IL-18 inhibition also rely on TLR signaling. Similarly glycyrrhetinic acid (GA) treatment activates TLR-4 in Ana-1 cells not via TRIF, but via MYD88 expression, which is significantly upregulated to cure PUD. Therefore, understanding TLR signaling complexity and its resultant immune modulation after host-pathogen interactions is pivotal to drug and vaccine development for other diseases as well including cancer and recent pandemic COVID-19. In this review, we summarize the TLRs and HP interaction; its pathophysiology-related signaling pathways, polymorphisms, and pharmaceutical approaches toward PUD.

Investigation of Aryl Hydrocarbon Receptor, Zinc, and Vitamin B12 Levels in Chronic Gastritis with Helicobacter pylori Infection

Helicobacter pylori (H. pylori) infection is known as the most common cause of worldwide common chronic gastritis. Pathogenic mechanisms caused by H. pylori in diseases are still not fully understood. In addition, it has been reported that H. pylori can alter gene expressions in infected tissues and affect transcription factor activation. It is reported that aryl hydrocarbon receptor (AhR), which is a cytoplasmic transcription factor, functions in the immune system and plays a role in immune cells in barrier organs such as the gastrointestinal system, skin, and lungs. H. pylori infection affects the absorption of micronutrients such as trace elements, minerals, and vitamins by disrupting gastric secretion and acidification functions. Zinc (Zn) trace element is thought to be able to modulate the induction of AhR-responsive genes in endothelial cells. Although it is emphasized that trace elements are related with gastritis, relationship between Zn and AhR is not fully known, especially in chronic gastritis accompanied by H. pylori infection. In this study, serum levels of AhR, Zn, and AhR antagonist vitamin B12 were determined in chronic gastritis with H. pylori infection. Fifty volunteers diagnosed with H. pylori positive and negative chronic gastritis were included in this study. Collected from individuals participating were 5 ml of venous blood samples, and their serums were separated. AhR serum level of the study group was determined using enzyme-linked immunosorbent assay method. Zn concentrations in serum samples were measured using inductively coupled plasma atomic emission spectroscopy. When AhR and Zn serum levels were compared in H. pylori positive and negative chronic gastritis patients, it was found that AhR serum level of H. pylori positive chronic gastritis patients increased but it was not statistically significant (p = 0.595). However it was determined Zn and B12 serum levels were statistically significantly decreased (p < 0.001). This study has a crucial importance since to be the first one investigating relationship between serum AhR, Zn, and vitamin B12 levels in the pathogenesis of H. pylori gastritis in adults. Examination of AhR, Zn and B12 levels in H. pylori positive gastritis patients contributes to elucidating molecular mechanism of the disease.

Role of NOD1 and ALPK1/TIFA Signalling in Innate Immunity Against Helicobacter pylori Infection

The human pathogen Helicobacter pylori interacts intimately with gastric epithelial cells to induce inflammatory responses that are a hallmark of the infection. This inflammation is a critical precursor to the development of peptic ulcer disease and gastric cancer. A major driver of this inflammation is a type IV secretion system (T4SS) encoded by the cag pathogenicity island (cagPAI), present in a subpopulation of more virulent H. pylori strains. The cagPAI T4SS specifically activates signalling pathways in gastric epithelial cells that converge on the transcription factor, nuclear factor-κB (NF-κB), which in turn upregulates key immune and inflammatory genes, resulting in various host responses. It is now clear that H. pylori possesses several mechanisms to activate NF-κB in gastric epithelial cells and, moreover, that multiple signalling pathways are involved in these responses. Two of the dominant signalling pathways implicated in NF-κB-dependent responses in epithelial cells are nucleotide-binding oligomerisation domain 1 (NOD1) and a newly described pathway involving alpha-kinase 1 (ALPK1) and tumour necrosis factor (TNF) receptor-associated factor (TRAF)-interacting protein with forkhead-associated domain (TIFA). Although the relative roles of these two pathways in regulating NF-κB-dependent responses still need to be clearly defined, it is likely that they work cooperatively and non-redundantly. This chapter will give an overview of the various mechanisms and pathways involved in H. pylori induction of NF-κB-dependent responses in gastric epithelial cells, including a 'state-of-the-art' review on the respective roles of NOD1 and ALPK1/TIFA pathways in these responses.

Anti-bacterial effects of enzymatically-isolated sialic acid from glycomacropeptide in a Helicobacter pylori-infected murine model

BACKGROUND/OBJECTIVES

Helicobacter pylori (H. pylori) colonization of the stomach mucosa and duodenum is the major cause of acute and chronic gastroduodenal pathology in humans. Efforts to find effective anti-bacterial strategies against H. pylori for the non-antibiotic control of H. pylori infection are urgently required. In this study, we used whey to prepare glycomacropeptide (GMP), from which sialic acid (G-SA) was enzymatically isolated. We investigated the anti-bacterial effects of G-SA against H. pylori in vitro and in an H. pylori-infected murine model.

MATERIALS/METHODS

The anti-bacterial activity of G-SA was measured in vitro using the macrodilution method, and interleukin-8 (IL-8) production was measured in H. pylori and AGS cell co-cultures by ELISA. For in vivo study, G-SA 5 g/kg body weight (bw)/day and H. pylori were administered to mice three times over one week. After one week, G-SA 5 g/kg bw/day alone was administered every day for one week. Tumor necrosis factor-α (TNF-α), IL-1β, IL-6, and IL-10 levels were measured by ELISA to determine the anti-inflammatory effects of G-SA. In addition, real-time PCR was performed to measure the genetic expression of cytotoxin-associated gene A (cagA).

RESULTS

G-SA inhibited the growth of H. pylori and suppressed IL-8 production in H. pylori and in AGS cell co-cultures in vitro. In the in vivo assay, administration of G-SA reduced levels of IL-1β and IL-6 pro-inflammatory cytokines whereas IL-10 level increased. Also, G-SA suppressed the expression of cagA in the stomach of H. pylori-infected mice.

CONCLUSION

G-SA possesses anti-H. pylori activity as well as an anti-H. pylori-induced gastric inflammatory effect in an experimental H. pylori-infected murine model. G-SA has potential as an alternative to antibiotics for the prevention of H. pylori infection and H. pylori-induced gastric disease prevention.

Anti-Inflammatory Effects of Capsaicin and Piperine on Helicobacter pylori-Induced Chronic Gastritis in Mongolian Gerbils

BACKGROUND

Spices have been used for thousands of years, and recent studies suggest that certain spices confer beneficial effects on gastric disorders. The purpose of this study was to evaluate possible chemopreventive effects of spice-derived compounds on Helicobacter pylori (H. pylori)-induced gastritis.

METHODS

We examined the inhibitory effects of curcumin, capsaicin, and piperine on H. pylori in vitro by determining the colony-forming units and real-time RT-PCR in H. pylori stimulated AGS gastric cancer cells. For in vivo analysis, 6-week-old SPF male Mongolian gerbils were infected with H. pylori, fed diets containing 5000 ppm curcumin, 100 ppm capsaicin, or 100 ppm piperine, and sacrificed after 13 weeks.

RESULTS

All three compounds inhibited in vitro proliferation of H. pylori, with curcumin being the most effective. Infiltration of neutrophils and mononuclear cells was suppressed by piperine both in the antrum and corpus of H. pylori-infected gerbils. Capsaicin also decreased neutrophils in the antrum and corpus and mononuclear cell infiltration and heterotopic proliferative glands in the corpus. mRNA expression of Tnf-α and formation of phospho-IκB-α in the antrum were reduced by both capsaicin and piperine. In addition, piperine suppressed expression of Il-1β, Ifn-γ, Il-6, and iNos, while H. pylori UreA and other virulence factors were not significantly attenuated by any compounds.

CONCLUSION

These results suggest that capsaicin and piperine have anti-inflammatory effects on H. pylori-induced gastritis in gerbils independent of direct antibacterial effects and may thus have potential for use in the chemoprevention of H. pylori-associated gastric carcinogenesis.

Interleukin-1B signalling leads to increased survival of gastric carcinoma cells through a CREB-C/EBPβ-associated mechanism

BACKGROUND

Polymorphisms in inflammation-related genes have been associated with a risk of gastric carcinoma (GC). However, the biological mechanisms underlying these associations are still elusive. Our objective was to determine whether chronic inflammation-associated IL1Β signalling, as seen in the context of Helicobacter pylori infection, could be linked to gastric carcinogenesis by modulating the behaviour of gastric epithelial cells.

METHODS

The effect of IL1B was assessed by studying the expression and activation status of the IL1Β-activated transcription factors C/EBPβ and CREB in GC cell lines. Interaction between CREB and C/EBPβ was explored through interference RNA, chromatin immunoprecipitation and chemical inhibition. CREB and C/EBPβ expression was analysed in 66 samples of primary GC and in normal gastric mucosa. GC cell growth was analysed in vitro by BrdU incorporation and in vivo employing a chicken embryo chorioallantoic membrane model.

RESULTS

We found that IL1B regulates the expression/activation status of both C/EBPβ and CREB in GC cells through an ERK1/2-dependent mechanism. Our results show that CREB is a direct transactivator of CEBPB, acting as an upstream effector in this regulatory mechanism. Furthermore, we found CREB to be overexpressed in 94 % of GC samples and significantly associated with C/EBPβ expression (P < 0.05). Finally, we demonstrated both in vitro and in vivo that CREB can mediate IL1B-induced GC cell proliferation.

CONCLUSIONS

Our results support the hypothesis that the effect of chronic inflammation on gastric carcinogenesis, as seen in the context of genetically susceptible individuals infected with Helicobacter pylori, includes the modulation of signalling pathways that regulate survival mechanisms in epithelial cells. IL1B is able to increase the expression/activation status of CREB and its target gene C/EBPβ, which are mandatory for GC cell survival. Our results may help inform new strategies for the prevention and treatment of GC, including the control of chronic inflammation.

Investigation of association between oipA and iceA1/iceA2 genotypes of Helicobacter pylori and gastric cancer in Iran

BACKGROUND

H pylori is the main causative agent of Gastric cancer and chronic gastritis. Genetic diversity of H. pylori has major contribution in its pathogenesis. We investigated the prevalence of oipA and iceA1/iceA2 positive strains of H. pylori among patients with gastric cancer and gastritis.

MATERIALS AND METHODS

Sampling performed by means of endoscopy from 86 patients. DNA was extracted from tissue samples using DNA extraction kit. PCR assay was performed and products were monitored by Agarose Gel Electrophoresis.

RESULTS

Urease Test and 16S rRNA PCR did not show significant differences in detection of H. pylori. The frequency of iceA1 allele in patients with gastric cancer was significantly higher than those with gastritis (p<0.05). However, there was no significant difference in prevalence of oipA and iceA2 genes among the two groups of patients (p>0.05).

CONCLUSIONS

The iceA1 gene, but the oipA and iceA2 genes , is associated with H. pylori-induced gastric cancer. However, confirmatory studies must be performed in future.

Helicobacter pylori virulence and cancer pathogenesis

Helicobacter pylori is human gastric pathogen that causes chronic and progressive gastric mucosal inflammation and is responsible for the gastric inflammation-associated diseases, gastric cancer and peptic ulcer disease. Specific outcomes reflect the interplay between host-, environmental- and bacterial-specific factors. Progress in understanding putative virulence factors in disease pathogenesis has been limited and many false leads have consumed scarce resources. Few in vitro-in vivo correlations or translational applications have proved clinically relevant. Reported virulence factor-related outcomes reflect differences in relative risk of disease rather than specificity for any specific outcome. Studies of individual virulence factor associations have provided conflicting results. Since virulence factors are linked, studies of groups of putative virulence factors are needed to provide clinically useful information. Here, the authors discuss the progress made in understanding the role of H. pylori virulence factors CagA, vacuolating cytotoxin, OipA and DupA in disease pathogenesis and provide suggestions for future studies.

Helicobacter pylori infection, gastrin and cyclooxygenase-2 in gastric carcinogenesis

Gastric cancer is one of the most frequent neoplasms and a main cause of death worldwide, especially in China and Japan. Numerous epidemiological, animal and experimental studies support a positive association between chronic Helicobacter pylori (H. pylori) infection and the development of gastric cancer. However, the exact mechanism whereby H. pylori causes gastric carcinogenesis remains unclear. It has been demonstrated that expression of cyclooxygenase-2 (COX-2) is elevated in gastric carcinomas and in their precursor lesions. In this review, we present the latest clinical and experimental evidence showing the role of gastrin and COX-2 in H. pylori-infected patients and their possible association with gastric cancer risk.

Potential mechanism of corpus-predominant gastritis after PPI therapy in Helicobacter pylori-positive patients with GERD

The long-term use of proton pump inhibitors (PPIs) exacerbates corpus atrophic gastritis in patients with Helicobacter pylori (H. pylori) infection. To identify a potential mechanism for this change, we discuss interactions between pH, bile acids, and H. pylori. Duodenogastric reflux, which includes bile, occurs in healthy individuals, and bile reflux is increased in patients with gastroesophageal reflux disease (GERD). Diluted human plasma and bile acids have been found to be significant chemoattractants and chemorepellents, respectively, for the bacillus H. pylori. Although only taurine conjugates, with a pKa of 1.8-1.9, are soluble in an acidic environment, glycine conjugates, with a pKa of 4.3-5.2, as well as taurine-conjugated bile acids are soluble in the presence of PPI therapy. Thus, the soluble bile acid concentrations in the gastric contents of patients with GERD after continuous PPI therapy are considerably higher than that in those with intact acid production. In the distal stomach, the high concentration of soluble bile acids is likely to act as a bactericide or chemorepellent for H. pylori. In contrast, the mucous layer in the proximal stomach has an optimal bile concentration that forms chemotactic gradients with plasma components required to direct H. pylori to the epithelial surface. H. pylori may then colonize in the stomach body rather than in the pyloric antrum, which may explain the occurrence of corpus-predominant gastritis after PPI therapy in H. pylori-positive patients with GERD.

Identification of the genes that contribute to lactate utilization in Helicobacter pylori

Helicobacter pylori are Gram-negative, spiral-shaped microaerophilic bacteria etiologically related to gastric cancer. Lactate utilization has been implicated although no corresponding genes have been identified in the H. pylori genome. Here, we report that gene products of hp0137–0139 (lldEFG), hp0140–0141 (lctP), and hp1222 (dld) contribute to D- and L-lactate utilization in H. pylori. The three-gene unit hp0137–0139 in H. pylori 26695 encodes L-lactate dehydrogenase (LDH) that catalyzes the conversion of lactate to pyruvate in an NAD-dependent manner. Isogenic mutants of these genes were unable to grow on L-lactate-dependent medium. The hp1222 gene product functions as an NAD-independent D-LDH and also contributes to the oxidation of L-lactate; the isogenic mutant of this gene failed to grow on D-lactate-dependent medium. The parallel genes hp0140–0141 encode two nearly identical lactate permeases (LctP) that promote uptake of both D- and L-lactate. Interestingly an alternate route must also exist for lactate transport as the knockout of genes did not completely prevent growth on D- or L-lactate. Gene expression levels of hp0137–0139 and hp1222 were not enhanced by lactate as the carbon source. Expression of hp0140–0141 was slightly suppressed in the presence of L-lactate but not D-lactate. This study identified the genes contributing to the lactate utilization and demonstrated the ability of H. pylori to utilize both D- and L-lactate.

Inhibitory effect of Raphanobrassica on Helicobacter pylori-induced gastritis in Mongolian gerbils

Helicobacter pylori (H. pylori) infection is well known to be associated with chronic gastritis and also development of gastric cancer. Raphanobrassica (RB) is an intergeneric hybrid of the genera Raphanus (radish) and Brassica (cabbages) containing appreciable amounts of glucoraphanin (GR) and glucoraphenin (GRe), which are actively hydrolyzed by the enzyme myrosinase to sulforaphane and sulforaphene, respectively. Both of these metabolites exert antimicrobial and anti-inflammatory activity. The purpose of the present study was to investigate the effect of two freeze-dried products of RB (RB1 and RB2) on H. pylori-induced gastritis in Mongolian gerbils. Six-week-old male Mongolian gerbils were inoculated orally with H. pylori (ATCC 43504), and 2weeks later were fed diets containing no additives or diets supplemented with 2% RB1 (containing both GR and GRe) or 2% RB2 (containing GR only) for 10weeks. In the RB1, but not the RB2 group, mononuclear cell infiltration, mRNA expression of IL-6, and cell proliferation in the gastric mucosa were significantly suppressed. These results indicate that RB1 containing both GR and GRe exerted significant inhibitory effects on H. pylori-induced gastritis in Mongolian gerbils apparently mediated via suppression of IL-6 expression and chronic inflammation.

Helicobacter bilis gamma-glutamyltranspeptidase enhances inflammatory stress response via oxidative stress in colon epithelial cells

Helicobacter bilis (H. bilis) infection is associated with cases of inflammatory bowel Disease, thyphlocolitis, hepatitis and cholecystitis. However, little is known about the bacterial virulence determinants or the molecular mechanisms involved. Recently, H. bilis γ-glutamyltranspeptidase (HBgGT) was shown to be a virulence factor decreasing host cell viability. Bacterial gGTs play a key role in synthesis and degradation of glutathione and enables the bacteria to utilize extracellular glutamine and glutathione as sources of glutamate. gGT-mediated loss of cell viability has so far been linked to DNA damage via oxidative stress, but the signaling cascades involved herein have not been described. In this study, we identified enhanced ROS production induced by HBgGT as a central factor involved in the activation of the oxidative stress response cascades, which finally activate CREB, AP-1 and NF-κB in H. bilis infected colon cancer cells. IL-8, an important pro-inflammatory chemokine that is a common downstream target of these transcription factors, was up-regulated upon H. bilis infection in an HBgGT dependent manner. Moreover, the induction of these signaling responses and inflammatory cytokine production in host cells could be linked to HBgGT-mediated glutamine deprivation. This study implicates for the first time HBgGT as an important regulator of signaling cascades regulating inflammation in H. bilis infected host epithelial cells that could be responsible for induction of inflammatory disorders by the bacterium.

The significance of virulence factors in Helicobacter pylori

Helicobacter pylori (H. pylori) infection is linked to various gastroduodenal diseases; however, only a small fraction of these patients develop associated diseases. Despite the high prevalence of H. pylori infection in Africa and South Asia, the incidence of gastric cancer in these areas is much lower than those in other countries. The incidence of gastric cancer tends to decrease from north to south in East Asia. Such geographical differences in the pathology can be explained, at least in part, by the presence of different types of H. pylori virulence factors in addition to host and environmental factors. Virulence factors of H. pylori, such as CagA, VacA, DupA, IceA, OipA and BabA, have been demonstrated to be the predictors of severe clinical outcomes. Interestingly, a meta-analysis showed that CagA seropositivity was associated with gastric cancer compared with gastritis, even in East Asian countries where almost the strains possess cagA. Another meta-analysis also confirmed the significance of vacA, dupA and iceA. However, it is possible that additional important pathogenic genes may exist because H. pylori consists of approximately 1600 genes. Despite the advances in our understanding of the development of H. pylori infection-related diseases, further work is required to clarify the roles of H. pylori virulence factors.

Sequence determination of the heavy-chain constant region in four immunoglobulin classes of Mongolian gerbils (Meriones unguiculatus)

We determined partial cDNA sequences of four immunoglobulin (Ig) classes-IgM, IgG1, IgE, and IgA-of Mongolian gerbil (Meriones unguiculatus). Each deduced Ig heavy-chain constant (IGHC) region-Cµ, Cγ1, Cε, and Cα-is structurally similar to its counterparts in the mouse and rat, and phylogenetic analysis suggests that the gerbil Igs are evolutionarily close to their counterparts. In spite of the high sequence homology to the other rodent Cγ sequences, the gerbil Cγ1 sequence differs from our previously reported Cγ2. This result indicates that the gerbil has at least two IgG subclasses. These four gerbil IGHC cDNA sequences will be useful for determining gerbil Ig isotypes and examining the expression of gerbil Ig mRNAs in response to parasitic and bacterial infections.

Comparison of lafutidine and rabeprazole in 7-day second-line amoxicillin- and metronidazole-containing triple therapy for Helicobacter pylori: a pilot study

BACKGROUND

Lafutidine is an H2-receptor antagonist with gastroprotective action through capsaicin-sensitive afferent neurons and relatively inexpensive compare to proton-pump inhibitors (PPIs). A 7-day course of PPIs-amoxicillin-metronidazole is recommended as standard second-line Helicobacter pylori therapy and is covered by national health insurance in Japan. The aim of this study was to determine the efficacy and safety of second-line eradication using the H2-receptor antagonist lafutidine as a substitute for a PPI.

MATERIALS AND METHODS

 Fifty-two patients who failed in first-line eradication using PPI-amoxicillin-clarithromycin were randomly assigned to a 7-day course of rabeprazole at 10 mg b.i.d., amoxicillin at 750 mg b.i.d., and metronidazole at 250 mg b.i.d. (RPZ-AM) or a 7-day course of lafutidine at 10 mg t.i.d., amoxicillin at 750 mg b.i.d., and metronidazole at 250 mg b.i.d. (LFT-AM) as second-line therapy. Eradication was assessed by the (13) C urea breath test. A drug susceptibility test was performed before the second-line therapy.

RESULTS

  Prior to second-line H. pylori eradication, the rate of resistance to clarithromycin was 86.5% and the rate of resistance to metronidazole was 3.8%. The eradication rates for both LFT-AM and RPZ-AM groups were 96% (95%CI = 88.6-100%). There were no severe adverse events in either group.

CONCLUSIONS

Lafutidine plus metronidazole-amoxicillin as second-line therapy provided a high eradication rate and safe treatment similar to a PPI-based regimen. Lafutidine-based eradication therapy is therefore considered to be a promising alternative and is also expected to reduce health care costs in H. pylori eradication.

Pathogenesis of Helicobacter pylori-Related Gastroduodenal Diseases from Molecular Epidemiological Studies

Helicobacter pylori is a major human pathogen that infects the stomach and produces inflammation that is responsible for various gastroduodenal diseases. Despite the high prevalence of H. pylori infections in Africa and South Asia, the incidence of gastric cancer in these areas is much lower than in other countries. The incidence of gastric cancer also tends to decrease from north to south in East Asia. Data from molecular epidemiological studies show that this variation in different geographic areas could be explained in part by different types of H. pylori virulence factors, especially CagA, VacA, and OipA. H. pylori infection is thought to be involved in both gastric cancer and duodenal ulcer, which are at opposite ends of the disease spectrum. This discrepancy can also be explained in part by another H. pylori factor, DupA, as well as by CagA typing (East Asian type versus Western type). H. pylori has a genome of approximately 1,600 genes; therefore, there might be other novel virulence factors. Because genome wide analyses using whole-genome sequencing technology give a broad view of the genome of H. pylori, we hope that next-generation sequencers will enable us to efficiently investigate novel virulence factors.

Helicobacter pylori outer membrane proteins on gastric mucosal interleukin 6 and 11 expression in Mongolian gerbils

BACKGROUND AND AIM

The levels of interleukin (IL)-6 and IL-11 in the gastric mucosa are related to mucosal inflammation; however, the chronological changes in cytokine expression during different phases of Helicobacter pylori infection and the effects of H. pylori virulence factors, particularly those of outer membrane proteins, remain obscure. The aim of this study was to clarify the chronological changes in cytokine levels in relation to several H. pylori outer membrane proteins.

METHODS

We studied Mongolian gerbils inoculated with wild-type H. pylori 7.13 for up to 48 weeks and then examined animals infected with oipA, babA, or alpAB isogenic mutants for 12 weeks. Mucosal IL-6 and IL-11 mRNA levels were measured using real-time reverse transcription-polymerase chain reactions.

RESULTS

High levels of gastric mucosal IL-6 and IL-11 mRNA in gerbils infected with wild-type H. pylori were observed during the chronic phase of infection, reaching maximums at 12 and 6 months, respectively. Infection with oipA and babA mutants resulted in significantly reduced cytokine levels and inflammatory cell infiltrations compared to gerbils infected with wild-type strains, and this persisted throughout the observation period. The alpAB mutants did not infect gerbils. Mucosal IL-6 and IL-11 levels were significantly associated with the grade of inflammatory cell infiltration.

CONCLUSIONS

OipA and BabA result in more severe H. pylori infection and increased IL-6 and IL-11 levels, which in turn may increase the risk of developing H. pylori-induced gastrointestinal diseases.

Arginine and polyamines in Helicobacter pylori-induced immune dysregulation and gastric carcinogenesis

L-arginine (L-Arg) is metabolized by nitric oxide synthase and arginase enzymes. The gastric pathogen Helicobacter pylori causes peptic ulcer disease and gastric cancer. We have shown that alterations in L-Arg availability and metabolism into polyamines contribute significantly to the dysregulation of the host immune response to this infection. Nitric oxide (NO) derived from inducible NO synthase (iNOS) can kill H. pylori. There are multiple mechanisms leading to failure of this process, including competition for L-Arg substrate by H. pylori arginase, and induction of host macrophage arginase II (Arg2) and ornithine decarboxylase (ODC). Generation of spermine by ODC inhibits iNOS translation and NO-mediated H. pylori killing. Expression of ODC is dependent on formation of a unique AP-1 complex, leading to upregulation of c-Myc as a transcriptional enhancer. Macrophage apoptosis is mediated by oxidation of spermine via the enzyme spermine oxidase (SMO) that generates hydrogen peroxide (H(2)O(2)), and thus oxidative stress-induced mitochondrial membrane polarization. Our studies have demonstrated that apoptosis occurs through a pERK → pc-Fos/c-Jun → c-Myc → ODC → SMO pathway. In gastric epithelial cells, activation of oxidative stress by H. pylori is dependent on SMO induction and results in both apoptosis and DNA damage, such that inhibition or knockdown of SMO markedly attenuates these events. In summary, L-Arg metabolism by the arginase-ODC pathway and the activation of SMO leads to H. pylori-induced DNA damage and immune dysregulation through polyamine-mediated oxidative stress and impairment of antimicrobial NO synthesis. Our studies indicate novel targets for therapeutic intervention in H. pylori-associated diseases, including gastritis, ulcer disease, and gastric cancer.

Increased genetic susceptibility to intestinal-type gastric cancer is associated with increased activity of the RUNX3 distal promoter

BACKGROUND

The runt-related transcription factor RUNX3 plays essential roles in various types of tumors, including gastric cancer. Epigenetic changes in the methylation of the RUNX3 proximal promoter, but not common genetic changes in RUNX3, have been associated with both changes in the gene expression and development of the cancer.

METHODS

A case-control association study was conducted by genotyping 865 unrelated Korean subjects. Subsequent functional studies were performed to reveal functional implication of genetic association.

RESULTS

Several single-nucleotide polymorphisms (SNPs) in RUNX3 were significantly associated with susceptibility to intestinal-type gastric cancer (.0028 ≤ P ≤ .022) but not diffuse-type gastric cancer (.70 ≤ P ≤ .96). The risk-associated, minor variant of an intestinal-type gastric cancer-associated SNP in the RUNX3 distal promoter (rs7528484) significantly increased promoter activity in a CREB1-dependent manner. The distal promoter-derived, 33 kDa isoform of RUNX3 increased the activity of transcription factor nuclear factor kappa B (NF-κB), which had been activated by Helicobacter pylori infection, a risk factor for intestinal-type gastric cancer, and the expression of the interleukin-1β gene (IL1B), an NF-κB target genetically and functionally associated with gastric cancer. In contrast, the proximal promoter-derived, 44 kDa isoform of RUNX3 decreased both NF-κB activity and IL1B expression.

CONCLUSIONS

In addition to epigenetic changes in the RUNX3 proximal promoter, genetic changes in the distal promoter may be associated with susceptibility to intestinal-type gastric cancer by increasing promoter activity. Functionally, 2 RUNX3 isoforms may contribute differentially to intestinal-type gastric cancer susceptibility, at least in part through regulating NF-κB activity and IL1B expression.

Effects of blood group antigen-binding adhesin expression during Helicobacter pylori infection of Mongolian gerbils

Helicobacter pylori outer membrane proteins, such as the blood group antigen-binding adhesin (BabA), are associated with severe pathological outcomes. However, the in vivo role of BabA during long-term infection is not clear. In this study, Mongolian gerbils were infected with H. pylori and necropsied continuously during 18 months. Bacterial clones were recovered and analyzed for BabA expression, Leb-binding activity, and adhesion to gastric mucosa. BabA expression was completely absent by 6 months post-infection. Loss of BabA expression was attributable to nucleotide changes within the babA gene that resulted in a truncated BabA. In response to the infection, changes in the epithelial glycosylation pattern were observed that were similar to responses observed in humans and monkeys. Furthermore, infections with BabA-expressing and BabA-nonexpressing H. pylori showed no differences in colonization, but infection with the BabA-expressing strain exhibited histological changes and increased inflammatory cell infiltration. This suggests that BabA expression contributes to severe mucosal injury.

Mechanisms of disease: Helicobacter pylori virulence factors

Helicobacter pylori plays an essential role in the development of various gastroduodenal diseases; however, only a small proportion of people infected with H. pylori develop these diseases. Some populations that have a high prevalence of H. pylori infection also have a high incidence of gastric cancer (for example, in East Asia), whereas others do not (for example, in Africa and South Asia). Even within East Asia, the incidence of gastric cancer varies (decreasing in the south). H. pylori is a highly heterogeneous bacterium and its virulence varies geographically. Geographic differences in the incidence of gastric cancer can be explained, at least in part, by the presence of different types of H. pylori virulence factor, especially CagA, VacA and OipA. However, it is still unclear why the pathogenicity of H. pylori increased as it migrated from Africa to East Asia during the course of evolution. H. pylori infection is also thought to be involved in the development of duodenal ulcer, which is at the opposite end of the disease spectrum to gastric cancer. This discrepancy can be explained in part by the presence of H. pylori virulence factor DupA. Despite advances in our understanding of the development of H. pylori-related diseases, further work is required to clarify the roles of H. pylori virulence factors.

Mechanisms of disease: Helicobacter pylori virulence factors

Helicobacter pylori plays an essential role in the development of various gastroduodenal diseases; however, only a small proportion of people infected with H. pylori develop these diseases. Some populations that have a high prevalence of H. pylori infection also have a high incidence of gastric cancer (for example, in East Asia), whereas others do not (for example, in Africa and South Asia). Even within East Asia, the incidence of gastric cancer varies (decreasing in the south). H. pylori is a highly heterogeneous bacterium and its virulence varies geographically. Geographic differences in the incidence of gastric cancer can be explained, at least in part, by the presence of different types of H. pylori virulence factor, especially CagA, VacA and OipA. However, it is still unclear why the pathogenicity of H. pylori increased as it migrated from Africa to East Asia during the course of evolution. H. pylori infection is also thought to be involved in the development of duodenal ulcer, which is at the opposite end of the disease spectrum to gastric cancer. This discrepancy can be explained in part by the presence of H. pylori virulence factor DupA. Despite advances in our understanding of the development of H. pylori-related diseases, further work is required to clarify the roles of H. pylori virulence factors.

Helicobacter pylori induction of the gastrin promoter through GC-rich DNA elements

BACKGROUND

Helicobacter pylori (H. pylori) infection has been linked to the development of chronic gastritis, duodenal ulcer disease, and gastric cancer. Helicobacter pylori- infected patients and animal models develop hypergastrinemia, chronic gastritis, and gastric atrophy. Since gastrin is an important regulator of gastric acid secretion and cell growth, H. pylori regulation of this hormone has been implicated in its pathogenesis.

OBJECTIVES

To investigate the effect of H. pylori on gastrin gene expression in mice and of human bacterial isolates on gastrin mRNA expressed in a human cell line.

METHODS

Gastrin mRNA was measured by qRT-PCR in H. pylori-infected mice. H. pylori were co-cultured with AGS cells to study regulation of human gastrin gene expression. Various MAP kinases were implicated in signal transduction from the bacteria using specific inhibitors. Gastrin reporter constructs and gel shift assays were used to map DNA responsive elements.

RESULTS

In addition to an increase in gastrin mRNA in H. pylori-infected mice, H. pylori induced the endogenous human gastrin gene through MAP kinase-dependent signaling but not NFκB-dependent signaling. Activation of gastrin through MAPK signaling did not require CagA or VacA virulence factors. Transfection studies demonstrated that a GC-rich motif mediated H. pylori-induction of the gastrin promoter and that the motif inducibly binds Sp1 and Sp3 transcription factors.

CONCLUSIONS

Direct contact of live H. pylori bacteria with human cells is sufficient to induce gastrin gene expression.

Helicobacter pylori induces ERK-dependent formation of a phospho-c-Fos c-Jun activator protein-1 complex that causes apoptosis in macrophages

Macrophages are essential components of innate immunity, and apoptosis of these cells impairs mucosal defense to microbes. Helicobacter pylori is a gastric pathogen that infects half of the world population and causes peptic ulcer disease and gastric cancer. The host inflammatory response fails to eradicate the organism. We have reported that H. pylori induces apoptosis of macrophages by generation of polyamines from ornithine decarboxylase (ODC), which is dependent on c-Myc as a transcriptional enhancer. We have now demonstrated that expression of c-Myc requires phosphorylation and nuclear translocation of ERK, which results in phosphorylation of c-Fos and formation of a specific activator protein (AP)-1 complex. Electromobility shift assay and immunoprecipitation revealed a previously unrecognized complex of phospho-c-Fos (pc-Fos) and c-Jun in the nucleus. Fluorescence resonance energy transfer demonstrated the interaction of pc-Fos and c-Jun. The capacity of this AP-1 complex to bind to putative AP-1 sequences was demonstrated by oligonucleotide pulldown and fluorescence polarization. Binding of the pc-Fos.c-Jun complex to the c-Myc promoter was demonstrated by chromatin immunoprecipitation. A dominant-negative c-Fos inhibited H. pylori-induced expression of c-Myc and ODC and apoptosis. H. pylori infection of mice induced a rapid infiltration of macrophages into the stomach. Concomitant apoptosis depleted these cells, and this was associated with formation of a pc-Fos.c-Jun complex. Treatment of mice with an inhibitor of ERK phosphorylation attenuated phosphorylation of c-Fos, expression of ODC, and apoptosis in gastric macrophages. A unique AP-1 complex in gastric macrophages contributes to the immune escape of H. pylori.

Clinical relevance of cagPAI intactness in Helicobacter pylori isolates from Vietnam

The purpose of this paper is to investigate the relationship between clinical outcome and the intactness of cagPAI in Helicobacter pylori strains from Vietnam. The presence or absence of 30 cagPAI genes was investigated by polymerase chain reaction (PCR) and dot-blotting. H. pylori-induced interleukin-8 secretion and hummingbird phenotype, and H. pylori adhesion to gastric epithelial cells were examined. The serum concentration of pepsinogen 1, pepsinogen 2, and gastrin was also measured in all patients. cagPAI was present in all 103 Vietnamese H. pylori isolates, of which 91 had intact cagPAI and 12 contained only a part of cagPAI. Infection with the partial cagPAI strains was less likely to be associated with peptic ulcer and chronic gastric mucosal inflammation than infection with strains possessing intact cagPAI. The partial cagPAI strains lacked almost all ability to induce interleukin-8 secretion and the hummingbird phenotype in gastric cells. Their adhesion to epithelial cells was significantly decreased in comparison with intact cagPAI strains. Moreover, for the first time, we found an association between cagPAI status and the serum concentration of pepsinogens 1 and 2 in infected patients. H. pylori strains with internal deletion within cagPAI are less virulent and, thus, less likely to be associated with severe clinical outcomes.

H. pylori-induced promoter hypermethylation downregulates USF1 and USF2 transcription factor gene expression

Helicobacter pylori infection is associated with the development of gastric adenocarcinoma. Upstream stimulatory factors USF1 and USF2 regulate the transcription of genes related to immune response, cell cycle and cell proliferation. A decrease in their expression is observed in human gastric epithelial cells infected with H. pylori, associated to a lower binding to their DNA E-box recognition site as shown by electrophoretic mobility shift assay. DNA methylation leads to gene silencing. The treatment of cells with 5'-azacytidine, an inhibitor of DNA methylation, restored the USF1 and USF2 gene expression in the presence of infection. Using promoter PCR methylation assay, a DNA hypermethylation was shown in the promoter region of USF1 and USF2 genes, in infected cells. The inhibition of USF1 and USF2 expression by H. pylori and the DNA hypermethylation in their gene promoter region was confirmed in gastric tissues isolated from 12 to 18 months infected mice. Our study demonstrated the involvement of USF1 and USF2 as molecular targets of H. pylori and the key role of DNA methylation in their regulation. These mechanisms occurred in the context of metaplastic lesions, suggesting that alteration of USF1 and USF2 levels could participate in the promotion of neoplastic process during H. pylori infection.

Anti-inflammatory effects of caffeic acid phenethyl ester (CAPE), a nuclear factor-kappaB inhibitor, on Helicobacter pylori-induced gastritis in Mongolian gerbils

Nuclear factor-kappaB (NF-kappaB) plays a major role in host inflammatory responses and carcinogenesis and as such is an important drug target for adjuvant therapy. In this study, we examined the effect of caffeic acid phenethyl ester (CAPE), an NF-kappaB inhibitor, on Helicobacter pylori (H. pylori)-induced NF-kappaB activation in cell culture and chronic gastritis in Mongolian gerbils. In AGS gastric cancer cells, CAPE significantly inhibited H. pylori-stimulated NF-kappaB activation and mRNA expression of several inflammatory factors in a dose-dependent manner, and prevented degradation of IkappaB-alpha and phosphorylation of p65 subunit. To evaluate the effects of CAPE on H. pylori-induced gastritis, specific pathogen-free male, 6-week-old Mongolian gerbils were intragastrically inoculated with H. pylori, fed diets containing CAPE (0-0.1%) and sacrificed after 12 weeks. Infiltration of neutrophils and mononuclear cells and expression of NF-kappaB p50 subunit and phospho-IkappaB-alpha were significantly suppressed by 0.1% CAPE treatment in the antrum of H. pylori-infected gerbils. Labeling indices for 5'-bromo-2'-deoxyuridine both in the antrum and corpus and lengths of isolated pyloric glands were also markedly reduced at the highest dose, suggesting a preventive effect of CAPE on epithelial proliferation. Furthermore, in the pyloric mucosa, mRNA expression of inflammatory mediators including tumor necrosis factor-alpha, interferon-gamma, interleukin (IL)-2, IL-6, KC (IL-8 homologue), and inducible nitric oxide synthase was significantly reduced. These results suggest that CAPE has inhibitory effects on H. pylori-induced gastritis in Mongolian gerbils through the suppression of NF-kappaB activation, and may thus have potential for prevention and therapy of H. pylori-associated gastric disorders.

Regulation of the Helicobacter pylori cellular receptor decay-accelerating factor

Chronic gastritis induced by Helicobacter pylori is the strongest known risk factor for peptic ulceration and distal gastric cancer, and adherence of H. pylori to gastric epithelial cells is critical for induction of inflammation. One H. pylori constituent that increases disease risk is the cag pathogenicity island, which encodes a secretion system that translocates bacterial effector molecules into host cells. Decay-accelerating factor (DAF) is a cellular receptor for H. pylori and a mediator of the inflammatory response to this pathogen. H. pylori induces DAF expression in human gastric epithelial cells; therefore, we sought to define the mechanism by which H. pylori up-regulates DAF and to extend these findings into a murine model of H. pylori-induced injury. Co-culture of MKN28 gastric epithelial cells with the wild-type H. pylori cag(+) strain J166 induced transcriptional expression of DAF, which was attenuated by disruption of a structural component of the cag secretion system (cagE). H. pylori-induced expression of DAF was dependent upon activation of the p38 mitogen-activated protein kinase pathway but not NF-kappaB. Hypergastrinemic INS-GAS mice infected with wild-type H. pylori demonstrated significantly increased DAF expression in gastric epithelium versus uninfected controls or mice infected with an H. pylori cagE(-) isogenic mutant strain. These results indicate that H. pylori cag(+) strains induce up-regulation of a cognate cellular receptor in vitro and in vivo in a cag-dependent manner, representing the first evidence of regulation of an H. pylori host receptor by the cag pathogenicity island.

Protective effects of traditional Chinese medicine Wenweishu and Yangweishu against gastric mucosal lesions induced by Helicobacter pylori concentrated culture supernatant in mice

AIM: To evaluate the effect of traditional Chinese medicine Wenweishu and Yangweishu on gastric mucosal injury induced by H. pylori concentrated culture supernatant (CCS) in BALB/c mice.

METHODS: Seventy-five BALB/c mice were divided into group A, B, C, D and E. The mice in group A and B were treated with normal saline, and those in group C, D and E were treated intragastrically with sucralfate, Wenweishu and Yangweishu, respectively, in advance. Then the mice in group A served as normal controls, and gastric mucosal lesions were induced by intragastric administration of H. pylori CCS in the other four groups. The gastric mucosal changes were assessed by microscopic examination, quantitative histology and electron microscopy.

RESULTS: Histology and ultrastructure were remarkably damaged in group B, but they were obviously alleviated in group C, D and E. The epithelial damage scores (EDS) were 1.18 ± 0.31, 2.47 ± 0.58, 1.72 ± 0.73, 1.61 ± 0.73 and 1.56 ± 0.67 in group A, B, C, D and E, respectively. The value of EDS in group B was markedly higher than that in group A (P < 0.05); the values of EDS in group C, D and E were significantly lower than those in group B (all P < 0.05). There were no evident difference between group C, D and E (P > 0.05).

CONCLUSION: Wenweishu and Yangweishu as well as sucralfate can reduce gastric mucosal lesions induced by H. pylori CCS in mice.