The pathogenesis of Helicobacter pylori-induced gastro-duodenal diseases

Circulating mitochondrial DNA level, a noninvasive biomarker for the early detection of gastric cancer

BACKGROUND

Gastric cancer represents a major health burden worldwide and is often diagnosed at an advanced stage. Biomarkers for screening and prevention of gastric cancer are missing. Changes in peripheral blood mitochondrial DNA (mtDNA) have emerged as a potential preventive/diagnosis biomarker for cancer risk. We aimed to determine whether peripheral leukocytes mtDNA levels are associated with stages of the gastric carcinogenesis cascade.

METHODS

We measured mtDNA by quantitative real-time PCR assay in peripheral leukocytes of 28 patients with non-atrophic gastritis (NAG), 74 patients with gastric cancer, and 48 matched asymptomatic controls. In parallel, the serologic level of IL8 was determined.

RESULTS

Mean mtDNA level was higher in patients with gastric cancer (P = 0.0095) than in controls, with values >8.46 significantly associated with gastric cancer (OR, 3.93). Three ranges of mtDNA values were identified: interval I, <2.0; interval II, 2.0-20; and interval III, >20. Interval I included mainly NAG cases, and few gastric cancer samples and interval III corresponded almost exclusively to patients with gastric cancer. All controls fell in interval II, together with some NAG and gastric cancer cases. IL8 levels were significantly higher in patients with gastric cancer (P < 0.05), with levels >50 pg/mL observed exclusively in patients with gastric cancer, allowing to distinguish them within interval II. We validated mtDNA results in a second cohort of patients, confirming that mtDNA was significantly higher in gastric cancer than in patients with preneoplasia.

CONCLUSIONS

Circulating levels of mtDNA and IL8 constitute a potential biomarker for the early detection of gastric cancer.

IMPACT

Our findings lead us to propose a new noninvasive method to detect patients with gastric cancer risk.

Gastroretentive drug delivery systems for the treatment of Helicobacter pylori

Helicobacter pylori (H. pylori) is one of the most common pathogenic bacterial infections and is found in the stomachs of approximately half of the world's population. It is the primary known cause of gastritis, gastroduodenal ulcer disease and gastric cancer. However, combined drug therapy as the general treatment in the clinic, the rise of antibiotic-resistant bacteria, adverse reactions and poor patient compliance are major obstacles to the eradication of H. pylori. Oral site-specific drug delivery systems that could increase the longevity of the treatment agent at the target site might improve the therapeutic effect and avoid side effects. Gastroretentive drug delivery systems potentially prolong the gastric retention time and controlled/sustained release of a drug, thereby increasing the concentration of the drug at the application site, potentially improving its bioavailability and reducing the necessary dosage. Recommended gastroretentive drug delivery systems for enhancing local drug delivery include floating systems, bioadhesive systems and expandable systems. In this review, we summarize the important physiological parameters of the gastrointestinal tract that affect the gastric residence time. We then focus on various aspects useful in the development of gastroretentive drug delivery systems, including current trends and the progress of novel forms, especially with respect to their application for the treatment of H. pylori infections.

Pattern-recognition receptors and gastric cancer

Chronic inflammation has been associated with an increased risk of several human malignancies, a classic example being gastric adenocarcinoma (GC). Development of GC is known to result from infection of the gastric mucosa by Helicobacter pylori, which initially induces acute inflammation and, in a subset of patients, progresses over time to chronic inflammation, gastric atrophy, intestinal metaplasia, dysplasia, and finally intestinal-type GC. Germ-line encoded receptors known as pattern-recognition receptors (PRRs) are critical for generating mature pro-inflammatory cytokines that are crucial for both Th1 and Th2 responses. Given that H. pylori is initially targeted by PRRs, it is conceivable that dysfunction within genes of this arm of the immune system could modulate the host response against H. pylori infection, and subsequently influence the emergence of GC. Current evidence suggests that Toll-like receptors (TLRs) (TLR2, TLR3, TLR4, TLR5, and TLR9), nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) (NOD1, NOD2, and NLRP3), a C-type lectin receptor (DC-SIGN), and retinoic acid-inducible gene (RIG)-I-like receptors (RIG-I and MDA-5), are involved in both the recognition of H. pylori and gastric carcinogenesis. In addition, polymorphisms in genes involved in the TLR (TLR1, TLR2, TLR4, TLR5, TLR9, and CD14) and NLR (NOD1, NOD2, NLRP3, NLRP12, NLRX1, CASP1, ASC, and CARD8) signaling pathways have been shown to modulate the risk of H. pylori infection, gastric precancerous lesions, and/or GC. Further, the modulation of PRRs has been suggested to suppress H. pylori-induced inflammation and enhance GC cell apoptosis, highlighting their potential relevance in GC therapeutics. In this review, we present current advances in our understanding of the role of the TLR and NLR signaling pathways in the pathogenesis of GC, address the involvement of other recently identified PRRs in GC, and discuss the potential implications of PRRs in GC immunotherapy.

Resistotype of Helicobacter pylori isolates: the impact on eradication outcome

Antibiotic resistance is increasing worldwide, and it has been regarded as the main factor reducing the efficacy of Helicobacter pylori therapy. The aim of this study was to determine the phenotype and genotype of antibiotic-resistant strains of H. pylori in the Malaysian population and to evaluate the impact of antibiotic resistance to eradication outcome. One hundred and sixty-one H. pylori isolates were analysed in this study. Metronidazole, clarithromycin, fluoroquinolone, amoxicillin and tetracycline susceptibilities were determined by Etest. PCR followed by DNA sequencing was carried out to determine mutations. The medical records of the patients infected with resistant strains were reviewed to determine the eradication outcome. Metronidazole resistance was encountered in 36.6 % of H. pylori isolates, whereas clarithromycin and fluoroquinolone resistance was observed in 1.2  and 1.9 % of isolates, respectively. All strains tested were susceptible to amoxicillin and tetracycline. Frameshift and nonsense mutations in rdxA and frxA genes resulting in stop codons contributed to metronidazole resistance, which leads to reduced eradication efficacy. A2142G and A2143G mutations of 23S rRNA were identified as causing failure of the eradication therapy. Mutation at either codon 87 or 91 of the gyrA gene was identified in fluoroquinolone-resistant strains. However, the effect of resistance could not be assessed. This study showed that frameshift and nonsense mutations in rdxA or frxA genes and point mutations in the 23S rRNA affected the efficacy of H. pylori eradication therapy.

Critical pathogenic steps to high risk Helicobacter pylori gastritis and gastric carcinogenesis

Helicobacter pylori (H. pylori) gastritis may progress to high risk gastropathy and cancer. However, the pathological progression has not been characterized in detail. H. pylori induce persistent inflammatory infiltration. Neutrophils are unique in that they directly infiltrate into foveolar epithelium aiming the proliferative zone specifically. Neutrophilic proliferative zone foveolitis is a critical pathogenic step in H. pylori gastritis inducing intensive epithelial damage. Epithelial cells carrying accumulated genomic damage and mutations show the Malgun (clear) cell change, characterized by large clear nucleus and prominent nucleolus. Malgun cells further undergo atypical changes, showing nuclear folding, coarse chromatin, and multiple nucleoli. The atypical Malgun cell (AMC) change is a novel premalignant condition in high risk gastropathy, which may progress and undergo malignant transformation directly. The pathobiological significance of AMC in gastric carcinogenesis is reviewed. A new diagnosis system of gastritis is proposed based on the critical pathologic steps classifying low and high risk gastritis for separate treatment modality. It is suggested that the regulation of H. pylori-induced neutrophilic foveolitis might be a future therapeutic goal replacing bactericidal antibiotics approach.

The effect of Helicobacter pylori CagA on the HER-2 copy number and expression in gastric cancer

We investigated whether Helicobacter pylori (H. pylori) CagA contributes to the DNA copy change and mRNA transcript expression of the HER-2 gene and, consequently, affects HER-2 protein expression to evaluate the significance of CagA and HER-2 amplification in gastric cancer. We used the AGS and MKN1 gastric cancer and HFE-145 immortalized non-neoplastic gastric mucosa cell lines. We also confirmed the effects of CagA on HER-2 expression in human gastric cancer tissues and gastric mucosal tissues of H. pylori infected C57BL/6 mice. Ectopic CagA expression in AGS, MKN1 and HFE-145 cells showed a significant increase in HER-2 gene copy number and expression. The gastric mucosae of H. pylori infected C57BL/6 mice also showed increased HER-2 DNA copy number and protein expression. In addition, CagA expression was detected in 17 (56.7%) of 30 gastric cancer tissues, and eight (47%) of them showed HER-2 DNA amplification of more than two-fold. In immunohistochemistry, HER-2 overexpression was detected in 12 (40%) of 30 gastric cancers and a positive correlation was observed among DNA copy number, the mRNA transcript, and protein expression of the HER-2 gene in gastric cancer (P<0.05). These results suggest that H. pylori CagA may induce overexpression of the HER-2 protein by increasing HER-2 DNA and mRNA copy number.

Uptake of Helicobacter pylori vesicles is facilitated by clathrin-dependent and clathrin-independent endocytic pathways

Bacteria shed a diverse set of outer membrane vesicles that function as transport vehicles to deliver effector molecules and virulence factors to host cells. Helicobacter pylori is a gastric pathogen that infects half of the world’s population, and in some individuals the infection progresses into peptic ulcer disease or gastric cancer. Here we report that intact vesicles from H. pylori are internalized by clathrin-dependent endocytosis and further dynamin-dependent processes, as well as in a cholesterol-sensitive manner. We analyzed the uptake of H. pylori vesicles by gastric epithelial cells using a method that we refer to as quantification of internalized substances (qIS). The qIS assay is based on a near-infrared dye with a cleavable linker that enables the specific quantification of internalized substances after exposure to reducing conditions. Both chemical inhibition and RNA interference in combination with the qIS assay showed that H. pylori vesicles enter gastric epithelial cells via both clathrin-mediated endocytosis and additional endocytic processes that are dependent on dynamin. Confocal microscopy revealed that H. pylori vesicles colocalized with clathrin and dynamin II and with markers of subsequent endosomal and lysosomal trafficking. Interestingly, however, knockdown of components required for caveolae had no significant effect on internalization and knockdown of components required for clathrin-independent carrier (CLIC) endocytosis increased internalization of H. pylori vesicles. Furthermore, uptake of vesicles by both clathrin-dependent and -independent pathways was sensitive to depletion, but not sequestering, of cholesterol in the host cell membrane suggesting that membrane fluidity influences the efficiency of H. pylori vesicle uptake.

Bacterial vesicles act as long-distance tools to deliver toxins and effector molecules to host cells. Vesicles can cause a variety of host cell responses via cell surface-induced cell signaling or internalization. Vesicles of diverse bacterial species enter host cells via different endocytic pathways or via membrane fusion. With the combination of a fluorescence-based quantification assay that quantifies internalized vesicles in a large number of cells and either chemical inhibition or RNA interference, we show that clathrin-mediated endocytosis is the major pathway for uptake of Helicobacter pylori vesicles and that lipid microdomains of the host cell membrane affect uptake of vesicles via clathrin-independent pathways. Our results provide important insights about membrane fluidity and its important role in the complex process that directs the H. pylori vesicle to a specific endocytic pathway. Understanding the mechanisms that operate in vesicle-host interactions is important to fully recognize the impact of vesicles in pathogenesis.

Novel insights on the role of CD8+ T cells and cytotoxic responses during Helicobacter pylori infection

Helicobacter pylori chronically persists in 50% of the human population and causes serious gastric and duodenal pathologies in 15% of infected people. Research on the immune response to the infection has mainly focused on the induction of CD4+ T cell responses. Human studies emphasize the potential clinical relevance of CD8+ cytotoxic T lymphocytes, however this cell type has barely been reported in studies employing mouse or gerbil models. Traditionally characterized as an extracellular bacterium, H. pylori has been identified inside epithelial and immune cells. Similarly to other intracellular bacteria, H. pylori infection of macrophages can alter autophagy and phagosome processing. A novel animal model of H. pylori infection demonstrates for the first time the induction of cytotoxic CD8+ T cell responses in pigs and localization of intracellular H. pylori within lymphoid aggregates. Here, we discuss novel mechanisms of host-H. pylori interactions that could lead to the induction of cytotoxic responses.

Role of gene polymorphisms in gastric cancer and its precursor lesions: Current knowledge and perspectives in Latin American countries

Latin America shows one of the highest incidence rates of gastric cancer in the world, with variations in mortality rates among nations or even within countries belonging to this region. Gastric cancer is the result of a multifactorial complex process, for which a multistep model of carcinogenesis is currently accepted. Additionally to the infection with Helicobacter pylori, that plays a major role, environmental factors as well as genetic susceptibility factors are significant players at different stages in the gastric cancer process. The differences in population origin, demographic structure, socio-economic development, and the impact of globalization lifestyles experienced in Latin America in the last decades, all together offer opportunities for studying in this context the influence of genetic polymorphisms in the susceptibility to gastric cancer. The aim of this article is to discuss current trends on gastric cancer in Latin American countries and to review the available published information about studies of association of gene polymorphisms involved in gastric cancer susceptibility from this region of the world. A total of 40 genes or genomic regions and 69 genetic variants, 58% representing markers involved in inflammatory response, have been used in a number of studies in which predominates a low number of individuals (cases and controls) included. Polymorphisms of IL-1B (-511 C/T, 14 studies; -31 T/C, 10 studies) and IL-1RN (variable number of tandem repeats, 17 studies) are the most represented ones in the reviewed studies. Other genetic variants recently evaluated in large meta-analyses and associated with gastric cancer risk were also analyzed in a few studies [e.g., prostate stem cell antigen (PSCA), CDH1, Survivin]. Further and better analysis centered in gene polymorphisms linked to other covariates, epidemiological studies and the information provided by meta-analyses and genome-wide association studies should help to improve our understanding of gastric cancer etiology in order to develop appropriate health programs in Latin America.

Human immune responses to H. pylori HLA Class II epitopes identified by immunoinformatic methods

H. pylori persists in the human stomach over decades and promotes several adverse clinical sequelae including gastritis, peptic ulcers and gastric cancer that are linked to the induction and subsequent evasion of chronic gastric inflammation. Emerging evidence indicates that H. pylori infection may also protect against asthma and some other immune-mediated conditions through regulatory T cell effects outside the stomach. To characterize the complexity of the CD4+ T cell response generated during H. pylori infection, computational methods were previously used to generate a panel of 90 predicted epitopes conserved among H. pylori genomes that broadly cover HLA Class II diversity for maximum population coverage. Here, these sequences were tested individually for their ability to induce in vitro responses in peripheral blood mononuclear cells by interferon-γ ELISpot assay. The average number of spot-forming cells/million PBMCs was significantly elevated in H. pylori-infected subjects over uninfected persons. Ten of the 90 peptides stimulated IFN-γ secretion in the H. pylori-infected group only, whereas two out of the 90 peptides elicited a detectable IFN-γ response in the H. pylori-uninfected subjects but no response in the H. pylori-infected group. Cytokine ELISA measurements performed using in vitro PBMC culture supernatants demonstrated significantly higher levels of TNF-α, IL-2, IL-4, IL-6, IL-10, and TGF-β1 in the H. pylori-infected subjects, whereas IL-17A expression was not related to the subjects H. pylori-infection status. Our results indicate that the human T cell responses to these 90 peptides are generally increased in actively H. pylori-infected, compared with H. pylori-naïve, subjects. This information will improve understanding of the complex immune response to H. pylori, aiding rational epitope-driven vaccine design as well as helping identify other H. pylori epitopes with potentially immunoregulatory effects.

Sequence and apoptotic activity of VacA cytotoxin cloned from a Helicobacter pylori Thai clinical isolate

The vacuolating cytotoxin VacA produced by Helicobacter pylori induces the formation of large cytoplasmic vacuoles in host gastric epithelial cells as well as a release of cytochrome C from mitochondria resulting in cell apoptosis. Considerable sequence diversity in VacA relating to different degrees of disease severity is observed with clinical samples from a multitude of geographic places. In this study we describe expression in Escherichia coli, purification to homogeneity and in vitro assay of its apoptotic activity of a VacA toxin from a H. pylori isolate of a Thai patient with gastrointestinal lymphoma. Sequencing revealed that the deduced amino acid sequence of the cloned Thai isolate VacA is similar to H. pylori s1/m2 type strains. The percent sequence similarity to the model strain 60190 was lower due to the presence of extra amino acids in the mid (m) region. The purified VacA toxin exhibited significant apoptotic activity on both T84 and MDCK epithelial cell lines, as revealed by DAPI staining, whereby the observed activity was significantly higher on MDCK cells. These findings could relate to a modulation of VacA activity on host cells in the Thai isolate-VacA toxin that may differ from those of the model strain.

Anti-inflammatory properties of gastric-derived Lactobacillus plantarum XB7 in the context of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori colonization of the gastric epithelium induces interleukin-8 (IL-8) production and inflammation leading to host cell damage. We searched for gastric-derived Lactobacillus with the ability to suppress H. pylori-induced inflammation.

MATERIALS AND METHODS

Conditioned media from gastric-derived Lactobacillus spp. were tested for the ability to suppress H. pylori-induced IL-8 production in AGS gastric epithelial cells. IL-8 protein and mRNA levels were measured by ELISA and qPCR, respectively. The changes on host cell signaling pathway were analyzed by Western blotting and the anti-inflammatory effect was tested in a Sprague-Dawley rat model.

RESULTS

Conditioned media from L. salivarius B101, L. rhamnosus B103, and L. plantarum XB7 suppressed IL-8 production and IL-8 mRNA expression in H. pylori-induced AGS cells without inhibiting H. pylori growth. Conditioned media from LS-B101, LR-B103, and LP-XB7 suppressed the activation of NF-κB in AGS cells, while strain LP-XB7 also suppressed c-Jun activation. The anti-inflammatory effect of LP-XB7 was further assessed in vivo using a H. pylori-infected Sprague-Dawley rat model. Strain LP-XB7 contributed to a delay in the detection and colonization of H. pylori in rat stomachs, attenuated gastric inflammation, and ameliorated gastric histopathology. Additionally, the administration of LP-XB7 correlated with the suppression of TNF-α and CINC-1 in sera, and suppression of CINC-1 in the gastric mucosa of H. pylori-infected rats.

CONCLUSIONS

These results suggest that L. plantarum XB7 produces secreted factors capable of modulating inflammation during H. pylori infection, and this probiotic Lactobacillus strain shows promise as an adjunctive therapy for treating H. pylori-associated disease.

Helicobacter pylori vacA d1 genotype predicts risk of gastric adenocarcinoma and peptic ulcers in northwestern Iran

BACKGROUND

There is a close relationship between Helicobacter pylori (H pylori)-specific factors and different gastroduodenal diseases. The present study aimed to investigate the prevalence of vacA d1, d2 genotypes in the H pylori isolates from patients with gastric adenocarcinoma, peptic ulcer disease (PUD) and gastritis in East Azerbaijan region, where the incidence of gastric cancer (GC) is high. Strains isolated from this area are likely to be of European ancestry.

MATERIALS AND METHODS

In this study, genotyping of the vacA d region of 115 isolates obtained from patients with different gastrodoudenal diseases was accomplished by PCR methods. In addition to PCR amplification of H pylori 16S rDNA, rapid urease tests or histological examination were used to confirm the presence of H pylori in biopsy specimens. Data were collected and analyzed using SPSS version 19.

RESULTS

Of the total of 83 H pylori isolates, 36 (43.4%) contained the d1 allele and 47 (56.6%) were subtype d2. The results of the multiple linear/logistic regression analysis showed high correlation between allele d1 and gastric adenocarcinoma or PUD.

CONCLUSIONS

This study suggests that the H pylori vacA d1 genotype helps predict risk for gastric adenocarcinoma and PUD in East Azerbaijan, Iran.

A role for the vacuolating cytotoxin, VacA, in colonization and Helicobacter pylori-induced metaplasia in the stomach

Carriage of Helicobacter pylori strains producing more active (s1/i1) forms of VacA is strongly associated with gastric adenocarcinoma. To our knowledge, we are the first to determine effects of different polymorphic forms of VacA on inflammation and metaplasia in the mouse stomach. Bacteria producing the less active s2/i2 form of VacA colonized mice more efficiently than mutants null for VacA or producing more active forms of it, providing the first evidence of a positive role for the minimally active s2/i2 toxin. Strains producing more active toxin forms induced more severe and extensive metaplasia and inflammation in the mouse stomach than strains producing weakly active (s2/i2) toxin. We also examined the association in humans, controlling for cagPAI status. In human gastric biopsy specimens, the vacA i1 allele was strongly associated with precancerous intestinal metaplasia, with almost complete absence of intestinal metaplasia in subjects infected with i2-type strains, even in a vacA s1, cagA⁺ background.

Helicobacter pylori infection: A brief overview on alternative natural treatments to conventional therapy

Helicobacter pylori is a human gastric pathogen considered as the etiologic agent of several gastric disorders, that may range from chronic gastritis to more severe outcomes, including gastric cancer. The current therapeutic scheme relies on the combination of several pharmacological substances, namely antibiotics and proton pump inhibitors. However, the cure rates obtained have been declining over the years, mostly due to bacterial resistance to antibiotics. In this context, the use of non-antibiotic substances is of the utmost importance regarding H. pylori eradication. In this review, we present different classes of compounds obtained from natural sources that have shown to present anti-H. pylori potential; we briefly highlight their possible use in the context of developing new therapeutic approaches.

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

PURPOSE

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

MATERIAL/METHODS

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

RESULTS

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

CONCLUSIONS

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

Nickel-dependent metalloenzymes

This review describes the functions, structures, and mechanisms of nine nickel-containing enzymes: glyoxalase I, acireductone dioxygenase, urease, superoxide dismutase, [NiFe]-hydrogenase, carbon monoxide dehydrogenase, acetyl-coenzyme A synthase/decarbonylase, methyl-coenzyme M reductase, and lactate racemase. These enzymes catalyze their various chemistries by using metallocenters of diverse structures, including mononuclear nickel, dinuclear nickel, nickel-iron heterodinuclear sites, more complex nickel-containing clusters, and nickel-tetrapyrroles. Selected other enzymes are active with nickel, but the physiological relevance of this metal specificity is unclear. Additional nickel-containing proteins of undefined function have been identified.

Evidence of the anti-Helicobacter pylori, gastroprotective and anti-inflammatory activities of Cuphea aequipetala infusion

ETHNOPHARMACOLOGICAL RELEVANCE

Cuphea aequipetala (Lythraceae) is a medicinal plant highly appreciated in Mexico to treat stomach ailments such as pain and burning sensation, stomach infections, ulcers, diarrhea, dysentery, and different types of tumors and bruises. In this work, the infusion of aerial parts of this plant (CAI) was investigated for its polypharmacological potential.

MATERIALS AND METHODS

In vitro anti-Helicobacter pylori activity was assessed by broth dilution method. Pharmacological studies included acute toxicity in mice using Lorke´s model, anti-inflammatory activity by xylene and TPA induced ear edema assay, as well as gastroprotection with ethanol-induced gastric ulcer model. DPPH and ABTS assays were used to determine antioxidant capacity. Polyphenols and flavonoid contents were determined by Folin-Ciocalteu method and AlCl3 reaction, respectively.

RESULTS

CAI showed good anti-Helicobacter pylori activity with a MIC of 125μg/mL. The infusion was not toxic according to Lorke's model with a LD50 greater than 5g/kg. CAI exhibited low anti-edematogenic action in the models assayed. Oral administration of 300mg/kg CAI significantly reduced gastric lesions by 87.9%. The effect was reversed only by indomethacin and N-ethylmaleimide demonstrating the role of endogenous prostaglandins and sulfhydryl compounds in gastroprotection. Total phenolic and flavonoid contents of CAI were 109.9mg GAE/g DW and 28.1mg QE/g DW, respectively, and the infusion exhibited a good antioxidant activity that is thought to play a role in its biological activity. The analysis of a preliminary fractionation of the infusion indicates that the complete extract conserves all its pharmacological activities in contrast to fractionated extracts.

CONCLUSIONS

Cuphea aequipetala is a promising native herb in an integral therapy for the treatment of bacterial or non-bacterial gastric ulcer because it possesses some anti-inflammatory properties, as well as exhibits good gastroprotective and antibacterial effects. It represents an important source for the isolation of anti-Helicobacter pylori compounds. This work provides ethnopharmacological evidence that supports the traditional use of this species.

The impact of digestive and colon drugs on the human hormones profile

Hormones play an important role in the digestive system. The main hormones that control digestion are gastrin, secretin, and cholecystokinin. Herein, the current study is concerned with assessing the effect of spasmo canulase and librax drugs on the human hormones profile. Blood samples were withdrawn from adult patients to measure serum FSH, E2, LH, prolactin, progesterone, DHEAS, testosterone, TSH, T3, T4, fasting insulin, and cortisol. All hormone concentrations were determined quantitatively using ELISA procedure. Intriguingly, the present study showed putative changes including thyroid and sex hormonal profiles. Eventually, we concluded that the prospective study could be important in drug dose optimization and providing new medical guidelines to avoid side effects that could harm patients.

Age-dependent association among Helicobacter pylori infection, serum pepsinogen levels and immune response of children to live oral cholera vaccine CVD 103-HgR

Background

Through its effects on gastric secretion, we hypothesized that Helicobacter pylori infection may influence oral immunization. Accordingly, we examined the association between H. pylori infection, serum pepsinogen (PG) (measures for H. pylori gastritis) and vibriocidal antibody (a correlate of protection) seroconversion following oral immunization with CVD 103-HgR live cholera vaccine among children of different ages.

Methods

Sera from 422 Chilean children who were vaccinated with a single dose of CVD 103-HgR were tested by ELISA for serum IgG antibodies to H. pylori, PG I and PG II levels and antibodies to Shigella flexneri 2a lipopolysaccharide and hepatitis A virus (as markers of low socioeconomic status and exposure to enteric pathogens).

Results

The likelihood of vibriocidal antibody seroconversion following vaccination with CVD 103-HgR was significantly decreased in H. pylori-seropositive children age 6 months to 4 years with PG II>8 µg/L (adjusted OR 0.14 (95% CI 0.03–0.61; P = 0.009), and also in H. pylori seropositives with lower PG II level (adjusted OR 0.34, 95% CI 0.14–0.83; P = 0.017), compared to H. pylori-seronegatives. H. pylori-seropositive children aged 5–9 years with serum PG I>30 µg/L (indicating more severe gastritis) had higher odds of vibriocidal seroconversion than those with lower PG I levels (adjusted OR 4.41, 95%CI 1.26–15.38; P = 0.02). There was no significant association between exposures to S. flexneri 2a or hepatitis A virus and vibriocidal seroconversion.

Conclusions

As H. pylori gastritis progresses with increasing pediatric age in developing country venues, changes in gastric secretion ensue that we believe explain the observed differences in age-related immune responses to immunization with live oral cholera vaccine. The effect of H. pylori and changes of gastric acid secretion on the immunogenicity of various oral vaccines should be studied in different developing, transitional and industrialized country settings.

Ni2+chemistry in pathogens – a possible target for eradication

Nickel homeostasis inHelicobacter pyloriand potential histidine-rich binding sites from various bacterial and fungal pathogens are discussed.

Intracellular locations of replication proteins and the origin of replication during chromosome duplication in the slowly growing human pathogen Helicobacter pylori

We followed the position of the replication complex in the pathogenic bacterium Helicobacter pylori using antibodies raised against the single-stranded DNA binding protein (HpSSB) and the replicative helicase (HpDnaB). The position of the replication origin, oriC, was also localized in growing cells by fluorescence in situ hybridization (FISH) with fluorescence-labeled DNA sequences adjacent to the origin. The replisome assembled at oriC near one of the cell poles, and the two forks moved together toward the cell center as replication progressed in the growing cell. Termination and resolution of the forks occurred near midcell, on one side of the septal membrane. The duplicated copies of oriC did not separate until late in elongation, when the daughter chromosomes segregated into bilobed nucleoids, suggesting sister chromatid cohesion at or near the oriC region. Components of the replication machinery, viz., HpDnaB and HpDnaG (DNA primase), were found associated with the cell membrane. A model for the assembly and location of the H. pylori replication machinery during chromosomal duplication is presented.

Sequence divergence and conservation in genomes of Helicobacter cetorum strains from a dolphin and a whale

Background and Objectives

Strains of Helicobacter cetorum have been cultured from several marine mammals and have been found to be closely related in 16 S rDNA sequence to the human gastric pathogen H. pylori, but their genomes were not characterized further.

Methods

The genomes of H. cetorum strains from a dolphin and a whale were sequenced completely using 454 technology and PCR and capillary sequencing.

Results

These genomes are 1.8 and 1.95 mb in size, some 7–26% larger than H. pylori genomes, and differ markedly from one another in gene content, and sequences and arrangements of shared genes. However, each strain is more related overall to H. pylori and its descendant H. acinonychis than to other known species. These H. cetorum strains lack cag pathogenicity islands, but contain novel alleles of the virulence-associated vacuolating cytotoxin (vacA) gene. Of particular note are (i) an extra triplet of vacA genes with ≤50% protein-level identity to each other in the 5′ two-thirds of the gene needed for host factor interaction; (ii) divergent sets of outer membrane protein genes; (iii) several metabolic genes distinct from those of H. pylori; (iv) genes for an iron-cofactored urease related to those of Helicobacter species from terrestrial carnivores, in addition to genes for a nickel co-factored urease; and (v) members of the slr multigene family, some of which modulate host responses to infection and improve Helicobacter growth with mammalian cells.

Conclusions

Our genome sequence data provide a glimpse into the novelty and great genetic diversity of marine helicobacters. These data should aid further analyses of microbial genome diversity and evolution and infection and disease mechanisms in vast and often fragile ocean ecosystems.

Role of connexin 43 in Helicobacter pylori VacA-induced cell death

Helicobacter pylori colonizes the human stomach and confers an increased risk for the development of peptic ulceration, noncardia gastric adenocarcinoma, and gastric lymphoma. A secreted H. pylori toxin, VacA, can cause multiple alterations in gastric epithelial cells, including cell death. In this study, we sought to identify host cell factors that are required for VacA-induced cell death. To do this, we analyzed gene trap and short hairpin RNA (shRNA) libraries in AZ-521 human gastric epithelial cells and selected for VacA-resistant clones. Among the VacA-resistant clones, we identified multiple gene trap library clones and an shRNA library clone with disrupted expression of connexin 43 (Cx43) (also known as gap junction protein alpha 1 [GJA1]). Further experiments with Cx43-specific shRNAs confirmed that a reduction in Cx43 expression results in resistance to VacA-induced cell death. Immunofluorescence microscopy experiments indicated that VacA did not colocalize with Cx43. We detected production of the Cx43 protein in AZ-521 cells but not in AGS, HeLa, or RK-13 cells, and correspondingly, AZ-521 cells were the most susceptible to VacA-induced cell death. When Cx43 was expressed in HeLa cells, the cells became more susceptible to VacA. These results indicate that Cx43 is a host cell constituent that contributes to VacA-induced cell death and that variation among cell types in susceptibility to VacA-induced cell death is attributable at least in part to cell type-specific differences in Cx43 production.

Diet, microbial virulence, and Helicobacter pylori-induced gastric cancer

Gastric adenocarcinoma is a leading cause of cancer-related death worldwide, and Helicobacter pylori infection is one of the strongest known risk factors for this malignancy. H. pylori strains exhibit a high level of genetic diversity, and the risk of gastric cancer is higher in persons carrying certain strain types (for example, those that contain a cag pathogenicity island or type s1 vacA alleles) than in persons carrying other strain types. Additional risk factors for gastric cancer include specific human genetic polymorphisms and specific dietary preferences (for example, a high-salt diet or a diet deficient in fruits and vegetables). Finally, iron-deficiency anemia is a risk factor for gastric cancer. Recent studies have provided evidence that several dietary risk factors for gastric cancer directly impact H. pylori virulence. In this review article, we discuss mechanisms by which diet can modulate H. pylori virulence and thereby influence gastric cancer risk.

Analysis of the microbial ecology between Helicobacter pylori and the gastric microbiota of Mongolian gerbils

Animal models are essential for in vivo analysis of Helicobacter-related diseases. Mongolian gerbils are used frequently to study Helicobacter pylori-induced gastritis and its consequences. The presence of some gastric microbiota with a suppressive effect on H. pylori suggests inhibitory gastric bacteria against H. pylori infection. The aim of the present study was to analyse the microbial ecology between H. pylori and the gastric microbiota of Mongolian gerbils. Gastric mucosa samples of H. pylori-negative and -positive gerbils were orally inoculated to five (Group 1) and six (Group 2) gerbils, respectively, and the gerbils were challenged with H. pylori infection. The colonization rate (40 %) of H. pylori in Group 1 gerbils was lower than the rate (67 %) in Group 2 gerbils. Culture filtrate of the gastric mucosa samples of Group 1 gerbils inhibited the in vitro growth of H. pylori. Three lactobacilli species, Lactobacillus reuteri, Lactobacillus johnsonii and Lactobacillus murinus, were isolated by anaerobic culture from the gerbils in Groups 1 and 2, and identified by genomic sequencing. It was demonstrated that the three different strains of lactobacilli exhibited an inhibitory effect on the in vitro growth of H. pylori. The results suggested that lactobacilli are the dominant gastric microbiota of Mongolian gerbils and the three lactobacilli isolated from the gastric mucosa samples with an inhibitory effect on H. pylori might have an anti-infective effect against H. pylori.

Development of a tetracycline-inducible gene expression system for the study of Helicobacter pylori pathogenesis

Deletion mutants and animal models have been instrumental in the study of Helicobacter pylori pathogenesis. Conditional mutants, however, would enable the study of the temporal gene requirement during H. pylori colonization and chronic infection. To achieve this goal, we adapted the Escherichia coli Tn10-derived tetracycline-inducible expression system for use in H. pylori. The ureA promoter was modified by inserting one or two tet operators to generate tetracycline-responsive promoters, named uPtetO, and these promoters were then fused to the reporter gfpmut2 and inserted into different loci. The expression of the tetracycline repressor (tetR) was placed under the control of one of three promoters and inserted into the chromosome. Conditional expression of green fluorescent protein (GFP) in strains harboring tetR and uPtetO-GFP was characterized by measuring GFP activity and by immunoblotting. The two tet-responsive uPtetO promoters differ in strength, and induction of these promoters was inducer concentration and time dependent, with maximum expression achieved after induction for 8 to 16 h. Furthermore, the chromosomal location of the uPtetO-GFP construct and the nature of the promoter driving expression of tetR influenced the strength of the uPtetO promoters upon induction. Integration of uPtetO-GFP and tetR constructs at different genomic loci was stable in vivo and did not affect colonization. Finally, we demonstrate tetracycline-dependent induction of GFP expression in vivo during chronic infection. These results open new experimental avenues for dissecting H. pylori pathogenesis using animal models and for testing the roles of specific genes in colonization of, adaptation to, and persistence in the host.

Diversity of Helicobacter pylori genotypes in Iranian patients with different gastroduodenal disorders

AIM

To investigate the diversity of Helicobacter pylori (H. pylori) genotypes and correlations with disease outcomes in an Iranian population with different gastroduodenal disorders.

METHODS

Isolates of H. pylori from patients with different gastroduodenal disorders were analyzed after culture and identification by phenotypic and genotypic methods. Genomic DNA was extracted with the QIAamp DNA mini kit (Qiagen, Germany). After DNA extraction, genotyping was done for cagA, vacA (s and m regions), iceA (iceA1 , iceA2 ) and babA with specific primers for each allele using polymerase chain reaction (PCR). All patients' pathologic and clinical data and their relation with known genotypes were analyzed by using SPSS version 19.0 software. χ² test and Fisher's exact test were used to assess relationships between categorical variables. The level of statistical significance was set at P < 0.05.

RESULTS

A total of 71 isolates from 177 patients with different gastroduodenal disorders were obtained. Based on analysis of the cagA gene (positive or negative), vacA s-region (s1 or s2), vacA m-region (m1 or m2), iceA allelic type (iceA1 and iceA2 ) and babA gene (positive or negative), twenty different genotypic combinations were recognized. The prevalence of cagA, vacA s1 , vacA s2 , vacA m1 , vacA m2 , iceA1 , iceA2 , iceA1+iceA2 and babA were 62%, 78.9%, 19.7%, 21.1%, 78.9%, 15.5%, 22.5%, 40.8% and 95.8%, respectively. Interestingly, evaluation of PCR results for cagA in 6 patients showed simultaneous existence of cagA variants according to their size diversities that proposed mixed infection in these patients. The most prevalent genotype in cagA-positive isolates was cagA⁺/vacAs1m2 /iceA1 +A2 /babA+ and in cagA-negative isolates was cagA⁻/vacAs1m2 /iceA-/babA+. There were no relationships between the studied genes and histopathological findings (H. pylori density, neutrophil activity, lymphoid aggregation in lamina propria and glandular atrophy). The strains which carry cagA, vacAs1/m1 , iceA2 and babA genes showed significant associations with severe active chronic gastritis (P = 0.011, 0.025, 0.020 and 0.031, respectively). The vacAs1 genotype had significant correlation with the presence of the cagA gene (P = 0.013). Also, babA genotype showed associations with cagA (P = 0.024). In the combined genotypes, only cagA⁺/vacAs1m1 /iceA2 /babA+ genotype showed correlation with severe active chronic gastritis (P = 0.025).

CONCLUSION

This genotyping panel can be a useful tool for detection of virulent H. pylori isolates and can provide valuable guidance for prediction of the clinical outcomes.

Experimentally validated novel inhibitors of Helicobacter pylori phosphopantetheine adenylyltransferase discovered by virtual high-throughput screening

Helicobacter pylori is a major etiologic agent associated with the development and maintenance of human gastritis. The goal of this study was to develop novel antibiotics against H. pylori, and we thus targeted H. pylori phosphopantetheine adenylyltransferase (HpPPAT). PPAT catalyzes the penultimate step in coenzyme A biosynthesis. Its inactivation effectively prevents bacterial viability, making it an attractive target for antibacterial drug discovery. We employed virtual high-throughput screening and the HpPPAT crystal structure to identify compounds in the PubChem database that might act as inhibitors of HpPPAT. d-amethopterin is a potential inhibitor for blocking HpPPAT activity and suppressing H. pylori viability. Following treatment with d-amethopterin, H. pylori exhibited morphological characteristics associated with cell death. d-amethopterin is a mixed inhibitor of HpPPAT activity; it simultaneously occupies the HpPPAT 4'-phosphopantetheine- and ATP-binding sites. Its binding affinity is in the micromolar range, implying that it is sufficiently potent to serve as a lead compound in subsequent drug development. Characterization of the d-amethopterin and HpPPAT interaction network in a docked model will allow us to initiate rational drug optimization to improve the inhibitory efficacy of d-amethopterin. We anticipate that novel, potent, and selective HpPPAT inhibitors will emerge for the treatment of H. pylori infection.

Isolation and characterization of bacteriophages of Helicobacter pylori isolated from Egypt

Aim: The aim of this work was to isolate and characterize bacteriophages from wastewater for the pathogenic bacteria Helicobacter pylori. Materials & methods: In this study, we isolated and characterized two phages against H. pylori isolated from gastric biopsies. The specific phages were isolated by the single plaque isolation technique, propagated by the liquid enrichment method and purified by the polyethylene glycol–dextran sulfate two-phase system. Results: The phages were designated as φHPE1 and φHPE2; φHPE1 had a head with a diameter of approximately 62 nm and short noncontractile tail with a length and width of approximately 12 × 6 nm and φHPE2 had an isometric head with a diameter of approximately 92.5 nm and a tail with a length of approximately 180 nm and width of approximately 15 nm. The host ranges were investigated with four strains of Helicobacter and all strains were susceptible to either φHPE1 or φHPE2. Conclusion: These results suggest that it may be possible to use this phage to control the disease caused by H. pylori.

Helicobacter pylori cagL amino acid polymorphisms and its association with gastroduodenal diseases

CagL is a pilus protein of Helicobacter pylori that interacts with host cellular α5β1 integrins through its arginine-glycine-aspartate (RGD) motif, guiding proper positioning of the T4SS and translocation of CagA. Deletion or sequence variations of cagL significantly diminished the ability of H. pylori to induce secretion of IL-8 by the host cell. Therefore, this study was undertaken to investigate the association of cagL and its amino acid sequence polymorphisms with gastric cancer (GC), peptic ulcer disease (PUD), and non-ulcer dyspepsia (NUD) as there are no such studies from India. In total, 200 adult patients (NUD 120, PUD 30, GC 50) who underwent an upper gastrointestinal endoscopy were enrolled. H. pylori infection was diagnosed by rapid urease test, culture, histopathology, and PCR. The collected isolates were screened for cagL genotype by PCR and assessed for amino acid sequence polymorphisms using sequence translation. The prevalence of H. pylori infection in study population was 52.5%. Most of the isolates were cagL genopositive (86.6%), and all had RGD motif in their amino acid sequences. D58 and K59 polymorphisms in cagL-genopositive strains were significantly higher in GC patients (P < 0.05). Combined D58K59 polymorphism was associated with higher risk of GC (3.8-fold) when compared to NUD. In conclusion, H. pylori cagL amino acid polymorphisms such as D58K59 are correlated with a higher risk of GC in the Indian population. Further studies are required to know the exact role of particular cagL amino acid polymorphisms in the pathogenicity of H. pylori infection.

Amino acid polymorphisms flanking the EPIYA-A motif of Helicobacter pylori CagA C-terminal region is associated with gastric cancer in east China: experience from a single center

OBJECTIVE

The study aimed to investigate the relationship between gastroduodenal disease and the diversity of the cagA 3' variable region and the amino acid polymorphisms in the Glu-Pro-Ile-Tyr-Ala (EPIYA) segments of the CagA C-terminal region of Helicobacter pylori (H. pylori).

METHODS

Gastric mucosal specimens from 170 patients in our center (Nanjing, Jiangsu Province, China) were collected and the genomic DNA of the H. pylori strains was extracted directly from biopsied specimens. Polymerase chain reaction (PCR) was used to amplify the cagA gene, and diversity in its 3' variable region was assessed by direct sequencing.

RESULTS

A total of 154 (90.6%) H. pylori isolates were cagA-positive, but the presence of this gene alone was not associated with the type of gastroduodenal disease. A total of 151 (88.8%) strains had the East Asian type EPIYA-D sequence, most of which were of ABD subtype. Three isolates from patients with chronic gastritis possessed the EPIYA-C segment. The sequences flanking the EPIYA motifs contained polymorphisms at seven residues, among which amino acid positions 878 and 879 had a statistically significant association with gastric cancer (P = 0.021). Amino acid change from glycine to aspartic acid at residue 968 was present only in patients with gastric cancer (4/20) (P < 0.001).

CONCLUSIONS

Most H. pylori strains present in our study are of the CagA-ABD subtype. Polymorphisms at amino acids 878 and 879 flanking the EPIYA-A motif are statistically associated with gastric cancer.

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.

Trend analysis of gastric cancer incidence in Iran and its six geographical areas during 2000-2005

OBJECTIVE

Gastric cancer is the fourth most common cancer worldwide. While it is one of the most common cancers in Iran, there are only limited data regarding incidence trends in the country. This study is the first of its type to investigate trends across six geographical areas during 2000-2005 using cancer registry data.

MATERIALS AND METHODS

The registered data for gastric cancer cases in National Cancer Registry System were extracted from the Ministry of Health and Medical Education, Center for Disease Control and Management, code C16. First, according to WHO population, the sex-standardized incidence rate in both sexes and then the trends of incidence rate during 2000-2005 were investigated separately for different geographical areas of the country.

RESULTS

The incidence rates of gastric cancer in Iran and its six geographical areas during 2000-2005 were increasing albeit with differences in their slopes. The overall incidence rate increased from 2.8 in 2000 to 9.1 per 100,000 persons per year in 2005, rising from 4.1 to 13.2 in men. The average six-year incidence of gastric cancer in the central and northwestern border of Caspian Sea was 7.8 per 100,000 persons per year, while it was 0.9 per 100,000 persons per year in the border of the Persian Gulf. Generally the incidence rate in men was higher than in women.

CONCLUSION

Iran is one of the high-risk areas for gastric cancer. Increase in incidence might continue in the future partly because of improvement in cancer registry systems as well as increase in risk of this cancer.

A mutagenesis method for the addition and deletion of highly repetitive DNA regions: the paradigm of EPIYA motifs in the cagA gene of Helicobacter pylori

BACKGROUND

CagA protein of Western origin Helicobacter pylori isolates contains at its carboxyl-terminal end repeating types of EPIYA motifs, depending on the surrounding sequence, which dictate hierarchic tyrosine phosphorylation. To produce, in an isogenic background, mutant strains expressing CagA protein with variable numbers of EPIYA-C terminal motifs, we have adopted a mutagenesis assay using a megaprimer approach.

MATERIALS AND METHODS

The H. pylori P12 reference strain containing two terminal EPIYA-C motifs was utilized. Initially, we cloned, full-length cagA gene, next to the Campylobacter jejuni kanamycin-resistance cassette, followed by the 1200-bp region located immediately after cagA gene (metacagA region). Then, we generated a megaprimer consisting of three consecutive copies of the EPIYA-C coding sequence of cagA gene, followed by the 140-bp region of the cagA genomic sequence present immediately after the second EPIYA-C repeat. We utilized these two products to perform a QuikChange mutagenesis assay and were able to obtain all desired combinations of EPIYA-C motifs, followed by Kan(r) cassette and metacagA region. These constructions were used to perform natural transformation of the P12 parental strain, by directional homologous recombination.

RESULTS

We produced isogenic H. pylori strains that express CagA with variable number of EPIYA-C motifs (AB, ABC, ABCCC) and their phosphorylation-deficient counterparts. They exhibited similar growth characteristics to the parental strain, adhered equally well to gastric cells and successfully translocated CagA, following pilus induction.

CONCLUSIONS

Our method can be used in other cases where highly repetitive sequences need to be reproduced.

The distribution of cagA and dupA genes in Helicobacter pylori strains in Kurdistan region, northern Iraq

BACKGROUND AND OBJECTIVES

Helicobacter pylori is a Gram negative bacteria that causes peptic ulceration and gastric adenocarcinoma. H pylori virulence factors, such as cagA and dupA, are important to study in populations as they contribute to disease risk. This study aimed to look at the distribution of the cagA and dupA genes in H pylori strains isolated from patients suffering from gastroduodenal diseases in Kurdistan region, Iraq.

DESIGN AND SETTINGS

A cross-sectional study conducted between June 2011 and January 2012. Biopsies were collected from the Endoscopy Department in Duhok and Sulaimania hospitals, Kurdistan region, northern Iraq.

PATIENTS AND METHODS

Upper gastrointestinal (GI) endoscopy examination was performed and 4 gastric biopsies (2 from the antrum and 2 from the corpus) were obtained from 204 patients. H pylori positivity was examined by CLO test; then the association between disease status and virulence factors was assessed by polymerase chain reaction.

RESULTS

154 (75%) of our samples were found to be H pylori + by CLO test. Endoscopic diagnoses for those who were positive were as follows: peptic ulcer disease (PUD) including duodenal ulcer, 45; gastric ulcer, 23; and no ulcer (NPUD), 86. The overall prevalence rates of cagA and dupA were 72.7% and 18.8%, respectively. While a significant association between cagA and PUD was observed (P. ≤.017; OR=0.4; CI=0.18–0.85), no relationship between dupA and PUD could be seen.

CONCLUSION

These data suggested that the presence of cagA may be a predictor of clinical outcome in Kurdistan region, northern Iraq.

Optimising the quantification of cytokines present at low concentrations in small human mucosal tissue samples using Luminex assays

Sensitive measurement of multiple cytokine profiles from small mucosal tissue biopsies, for example human gastric biopsies obtained through an endoscope, is technically challenging. Multiplex methods such as Luminex assays offer an attractive solution but standard protocols are not available for tissue samples. We assessed the utility of three commercial Luminex kits (VersaMAP, Bio-Plex and MILLIPLEX) to measure interleukin-17A (IL-17) and interferon-gamma (IFNγ) concentrations in human gastric biopsies and we optimised preparation of mucosal samples for this application. First, we assessed the technical performance, limits of sensitivity and linear dynamic ranges for each kit. Next we spiked human gastric biopsies with recombinant IL-17 and IFNγ at a range of concentrations (1.5 to 1000 pg/mL) and assessed kit accuracy for spiked cytokine recovery and intra-assay precision. We also evaluated the impact of different tissue processing methods and extraction buffers on our results. Finally we assessed recovery of endogenous cytokines in unspiked samples. In terms of sensitivity, all of the kits performed well within the manufacturers' recommended standard curve ranges but the MILLIPLEX kit provided most consistent sensitivity for low cytokine concentrations. In the spiking experiments, the MILLIPLEX kit performed most consistently over the widest range of concentrations. For tissue processing, manual disruption provided significantly improved cytokine recovery over automated methods. Our selected kit and optimised protocol were further validated by measurement of relative cytokine levels in inflamed and uninflamed gastric mucosa using Luminex and real-time polymerase chain reaction. In summary, with proper optimisation Luminex kits (and for IL-17 and IFNγ the MILLIPLEX kit in particular) can be used for the sensitive detection of cytokines in mucosal biopsies. Our results should help other researchers seeking to quantify multiple low concentration cytokines in small tissue samples.

Caffeic acid phenethyl ester (CAPE), an active component of propolis, inhibits Helicobacter pylori peptide deformylase activity

Helicobacter pylori (H. pylori) is a major causative factor for gastrointestinal illnesses, H. pylori peptide deformylase (HpPDF) catalyzes the removal of formyl group from the N-terminus of nascent polypeptide chains, which is essential for H. pylori survival and is considered as a promising drug target for anti-H. pylori therapy. Propolis, a natural antibiotic from honeybees, is reported to have an inhibitory effect on the growth of H. pylori in vitro. In addition, previous studies suggest that the main active constituents in the propolis are phenolic compounds. Therefore, we evaluated a collection of phenolic compounds derived from propolis for enzyme inhibition against HpPDF. Our study results show that Caffeic acid phenethyl ester (CAPE), one of the main medicinal components of propolis, is a competitive inhibitor against HpPDF, with an IC50 value of 4.02 μM. Furthermore, absorption spectra and crystal structural characterization revealed that different from most well known PDF inhibitors, CAPE block the substrate entrance, preventing substrate from approaching the active site, but CAPE does not have chelate interaction with HpPDF and does not disrupt the metal-dependent catalysis. Our study provides valuable information for understanding the potential anti-H. pylori mechanism of propolis, and CAPE could be served as a lead compound for further anti-H. pylori drug discovery.

Caveolin-1 protects B6129 mice against Helicobacter pylori gastritis

Caveolin-1 (Cav1) is a scaffold protein and pathogen receptor in the mucosa of the gastrointestinal tract. Chronic infection of gastric epithelial cells by Helicobacter pylori (H. pylori) is a major risk factor for human gastric cancer (GC) where Cav1 is frequently down-regulated. However, the function of Cav1 in H. pylori infection and pathogenesis of GC remained unknown. We show here that Cav1-deficient mice, infected for 11 months with the CagA-delivery deficient H. pylori strain SS1, developed more severe gastritis and tissue damage, including loss of parietal cells and foveolar hyperplasia, and displayed lower colonisation of the gastric mucosa than wild-type B6129 littermates. Cav1-null mice showed enhanced infiltration of macrophages and B-cells and secretion of chemokines (RANTES) but had reduced levels of CD25⁺ regulatory T-cells. Cav1-deficient human GC cells (AGS), infected with the CagA-delivery proficient H. pylori strain G27, were more sensitive to CagA-related cytoskeletal stress morphologies (“humming bird”) compared to AGS cells stably transfected with Cav1 (AGS/Cav1). Infection of AGS/Cav1 cells triggered the recruitment of p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1) to Cav1 and counteracted CagA-induced cytoskeletal rearrangements. In human GC cell lines (MKN45, N87) and mouse stomach tissue, H. pylori down-regulated endogenous expression of Cav1 independently of CagA. Mechanistically, H. pylori activated sterol-responsive element-binding protein-1 (SREBP1) to repress transcription of the human Cav1 gene from sterol-responsive elements (SREs) in the proximal Cav1 promoter. These data suggested a protective role of Cav1 against H. pylori-induced inflammation and tissue damage. We propose that H. pylori exploits down-regulation of Cav1 to subvert the host's immune response and to promote signalling of its virulence factors in host cells.

Infection with the bacterium Helicobacter pylori (H. pylori) mainly affects children in the developing countries who are at risk to progress to gastric cancer (GC) as adults after many years of persistent infection, especially with strains which are positive for the oncogenic virulence factor CagA. Eradication of H. pylori by antibiotics is a treatment of choice but may also alter the susceptibility to allergies and other tumor types. Thus, novel diagnostic or prognostic markers are needed which detect early molecular changes in the stomach mucosa during the transition of chronic inflammation to cancer. In our study, we found that the tumor suppressor caveolin-1 (Cav1) is reduced upon infection with H. pylori, and CagA was sufficient but not necessary for this down-regulation. Loss of Cav1 was caused by H. pylori-dependent activation of sterol-responsive element-binding protein-1 (SREBP1), and this event abolished the interaction of Cav1 with p120 RhoGTPase-activating protein/deleted in liver cancer-1 (p120RhoGAP/DLC1), a second bona fide tumor suppressor in gastric tissue. Conclusively, Cav1 and DLC1 may constitute novel molecular markers in the H. pylori-infected gastric mucosa before neoplastic transformation of the epithelium.

Helicobacter pylori infection and lung cancer: a review of an emerging hypothesis

Helicobacter pylori (Hp) is one of the most common bacteria infecting humans. Recently, certain extragastric manifestations, linked to Hp infection, have been widely investigated, suggesting that Hp infection might be a 'systemic' disease. Accumulating, yet limited, evidence points to a potential association between Hp infection and lung cancer risk. Epidemiologic studies have shown that odds ratios (estimated relative risks) of lung cancer with Hp infection range from 1.24 to 17.78 compared with the controls, suggesting an increased lung cancer risk in the population exposed to Hp infection although far from supporting a causal relationship between Hp and lung cancer. Many studies have demonstrated the existence of Hp in the mucosa of the upper respiratory tract with no direct evidence of Hp-localization in lung tissue in the published literatures, rendering the possible functional mechanism underlying the association an open question. We followed the classic hypothesis-generating path, where we have thoroughly reviewed the publications on lung cancer and Hp infection from serological association to possible mechanisms as: (i) p130cas activated by Src kinase following Hp-host communication and p130cas-related carcinogenesis as in various malignancies; and (ii) gastroesophageal reflux and inhalation of urease or gastrin, which are Hp-related carcinogenic factors and present in lung tissues. We propose rigorous investigations regarding the Hp-lung cancer association and, if confirmed, the mechanisms of Hp infection leading to lung cancer development and progression. Clarification on Hp-lung cancer association is important for the understanding of lung cancer beyond tobacco-smoking-related carcinogenesis.

Determination of Helicobacter pylori CagA EPIYA types in Iranian isolates with different gastroduodenal disorders

Helicobacter pylori (H. pylori) cytotoxin-associated gene A protein (CagA) is the first bacterial oncoprotein identified in human gastric cancer. The carboxy terminus (C-terminus) of CagA may undergo polymorphisms to give different types of EPIYA motifs, which may exist in single or combination form within the infected host. Sequence variations in the 3' region of the cagA impose a functional impact to the translated CagA protein. In this study, we characterize the diversity of the H. pylori CagA EPIYA types, their associations with their hosts' clinical status, and the potential of using the whole 3' region of cagA as a genetic marker for the identification of Iranian isolates from different geographic locations. H. pylori was detected in 71 out of 177 examined Iranian patients with different gastroduodenal disorders. Genotyping of the cagA variable EPIYA motif was screened by polymerase chain reaction and gene sequencing was performed for all the detected cagA positive isolates. Out of 44 cagA-positive isolates, there were EPIYA motifs of ABC (30 isolates), ABCC (4 isolates), ABCCC (1 isolate), mixed types (6 isolates) and new types (3 isolates). We termed the newly identified EPIYA segment as EPIYA- A-B/C. Sequence analysis also showed the presence of uncommon EPIYA-like motifs (EPIYT and QPIYP) in some isolates. It is postulated that EPIYA type conversion through the presence of different repetitive sequences give rise to these new strains. We also identified 3 sequence motifs which may be applied as genetic markers for Iranian strains. Furthermore, EPIYA types ABCC and EPIYA- A-B/C showed association with duodenitis and gastric cancer, respectively. Further study with a larger number of strains is necessary to confirm the proposed associations and the identified sequence motifs as genetic markers. In conclusion, our study demonstrates the dominancy of Western type cagA gene and the diversity of the CagA C-terminal region in the tested Iranian strains.

Proteome variability among Helicobacter pylori isolates clustered according to genomic methylation

AIMS

To understand whether the variability found in the proteome of Helicobacter pylori relates to the genomic methylation, virulence and associated gastric disease.

METHODS AND RESULTS

We applied the Minimum-Common-Restriction-Modification (MCRM) algorithm to genomic methylation data of 30 Portuguese H. pylori strains, obtained by genome sensitivity to Type II restriction enzymes' digestion. All the generated dendrograms presented three clusters with no association with gastric disease. Comparative analysis of two-dimensional gel electrophoresis (2DE) maps obtained for total protein extracts of 10 of these strains, representative of the three main clusters, revealed that among 70 matched protein spots (in a universe of 300), 16 were differently abundant (P < 0·05) among clusters. Of these, 13 proteins appear to be related to the cagA genotype or gastric disease. The abundance of three protein species, DnaK, GlnA and HylB, appeared to be dictated by the methylation status of their gene promoter.

CONCLUSIONS

Variations in the proteome profile of strains with common geographic origin appear to be related to differences in cagA genotype or gastric disease, rather than to clusters organized according to strain genomic methylation.

SIGNIFICANCE AND IMPACT OF THE STUDY

The simultaneous study of the genomic methylation and proteome is important to correlate epigenetic modifications with gene expression and pathogen virulence.