Bacterial factors that mediate colonization of the stomach and virulence of Helicobacter pylori

Membrane lipid remodeling eradicates Helicobacter pylori by manipulating the cholesteryl 6'-acylglucoside biosynthesis

BACKGROUND

Helicobacter pylori, the main cause of various gastric diseases, infects approximately half of the human population. This pathogen is auxotrophic for cholesterol which it converts to various cholesteryl α-glucoside derivatives, including cholesteryl 6'-acyl α-glucoside (CAG). Since the related biosynthetic enzymes can be translocated to the host cells, the acyl chain of CAG likely comes from its precursor phosphatidylethanolamine (PE) in the host membranes. This work aims at examining how the acyl chain of CAG and PE inhibits the membrane functions, especially bacterial adhesion.

METHODS

Eleven CAGs that differ in acyl chains were used to study the membrane properties of human gastric adenocarcinoma cells (AGS cells), including lipid rafts clustering (monitored by immunofluorescence with confocal microscopy) and lateral membrane fluidity (by the fluorescence recovery after photobleaching). Cell-based and mouse models were employed to study the degree of bacterial adhesion, the analyses of which were conducted by using flow cytometry and immunofluorescence staining, respectively. The lipidomes of H. pylori, AGS cells and H. pylori-AGS co-cultures were analyzed by Ultraperformance Liquid Chromatography-Tandem Mass Spectroscopy (UPLC-MS/MS) to examine the effect of PE(10:0)2, PE(18:0)2, PE(18:3)2, or PE(22:6)2 treatments.

RESULTS

CAG10:0, CAG18:3 and CAG22:6 were found to cause the most adverse effect on the bacterial adhesion. Further LC-MS analysis indicated that the treatment of PE(10:0)2 resulted in dual effects to inhibit the bacterial adhesion, including the generation of CAG10:0 and significant changes in the membrane compositions. The initial (1 h) lipidome changes involved in the incorporation of 10:0 acyl chains into dihydro- and phytosphingosine derivatives and ceramides. In contrast, after 16 h, glycerophospholipids displayed obvious increase in their very long chain fatty acids, monounsaturated and polyunsaturated fatty acids that are considered to enhance membrane fluidity.

CONCLUSIONS

The PE(10:0)2 treatment significantly reduced bacterial adhesion in both AGS cells and mouse models. Our approach of membrane remodeling has thus shown great promise as a new anti-H. pylori therapy.

Characterization of cytotoxic Citrobacter braakii isolated from human stomach

Citrobacter braakii (C. braakii) is an anaerobic, gram-negative bacterium that has been isolated from the environment, food, and humans. Infection by C. braakii has been associated with acute mucosal inflammation in the intestine, respiratory tract, and urinary tract. However, the pathogenesis of C. braakii in the gastric mucosa has not yet been clarified. In this study, the bacterium was detected in 35.5% (61/172) of patients with chronic gastritis (CG) and was closely associated with the severity of mucosal inflammation. Citrobacter braakii P1 isolated from a patient with CG exhibited urease activity and acid resistance. It contained multiple secretion systems, including a complete type I secretion system (T1SS), T5aSS and T6SS. We then predicted the potential pilus-related adhesins. Citrobacter braakii P1 diffusely adhered to AGS cells and significantly increased lactate dehydrogenase (LDH) release; the adhesion rate and LDH release were much lower in HEp-2 cells. Strain P1 also induced markedly increased mRNA and protein expression of IL-8 and TNF-α in AGS cells, and the fold increase was much higher than that in HEp-2 cells. Our results demonstrate proinflammatory and cytotoxic role of C. braakii in gastric epithelial cells, indicating the bacterium is potentially involved in inducing gastric mucosa inflammation.

Searching for serum biomarkers linking coronary heart disease and Helicobacter pylori infection using infrared spectroscopy and artificial neural networks

Helicobacter pylori (Hp) Gram-negative bacteria cause gastritis or gastric ulcers. They may be involved in the development of systemic diseases i.e. coronary heart disease (CHD). Both Hp infection and CHD are related to inflammation accompanied by C-reactive protein (CRP), tumor necrosis factor alfa (TNF-α) and homocysteine. Low density lipoprotein (LDL) and triglicerides are a classic risk factors of CHD. Infrared spectroscopy has been introduced for monitoring chronic infections or endogenous disorders using specific absorption bands for biocomponents typed as diagnostic markers. In this study we selected specific motives of infrared radiation (IR) spectra for the sera from CHD patients infected with Hp. In total 141 sera were used: 90 from patients with CHD, all Hp positive, and 51 from healthy donors, 32 Hp negative and 21 Hp positive. Hp status was evaluated by anti-Hp IgG antibodies and/or ¹³C urea breath testing. IR spectra were measured using FT-IR/FT-NIR Spectrum 400 spectrometer (PerkinElmer) chemometrically analyzed using artificial neural networks and they showed differences in absorption bands corresponding to triglicerides, CRP, homocysteine, LDL and TNF-α, and selected component groups between CHD patients infected with Hp vs healthy uninfected donors (96.15% accuracy). Triglicerides and CRP were the best biomarkers linking Hp infection with CHD.

Helicobacter pylori, Protected from Antibiotics and Stresses Inside Candida albicans Vacuoles, Cause Gastritis in Mice

Due to (i) the simultaneous presence of Helicobacter pylori (ulcer-induced bacteria) and Candida albicans in the stomach and (ii) the possibility of prokaryotic–eukaryotic endosymbiosis (intravacuolar H. pylori in the yeast cells) under stresses, we tested this symbiosis in vitro and in vivo. To that end, intravacuolar H. pylori were induced by the co-incubation of C. albicans with H. pylori under several stresses (acidic pH, non-H. pylori-enrichment media, and aerobic environments); the results were detectable by direct microscopy (wet mount) and real-time polymerase chain reaction (PCR). Indeed, intravacuolar H. pylori were predominant under all stresses, especially the lower pH level (pH 2–3). Interestingly, the H. pylori (an amoxicillin-sensitive strain) inside C. albicans were protected from the antibiotic (amoxicillin), while extracellular H. pylori were neutralizable, as indicated by the culture. In parallel, the oral administration of intravacuolar H. pylori in mice caused H. pylori colonization in the stomach resulting in gastritis, as indicated by gastric histopathology and tissue cytokines, similar to the administration of free H. pylori (extra-Candida bacteria). In conclusion, Candida protected H. pylori from stresses and antibiotics, and the intravacuolar H. pylori were able to be released from the yeast cells, causing gastric inflammation with neutrophil accumulations.

Impact of Helicobacter pylori infection on fluid duodenal microbial community structure and microbial metabolic pathways

Background

The bioactivities of commensal duodenal microbiota greatly influence the biofunction of hosts. We investigated the role of Helicobacter pylori infection in extra-gastroduodenal diseases by determining the impact of H. pylori infection on the duodenal microbiota. We sequenced 16 S rRNA genes in samples aspirated from the descending duodenum of 47 (male, 20; female, 27) individuals who were screened for gastric cancer. Samples were analysed using 16 S rRNA gene amplicon sequencing, and the LEFSe and Kyoto Encyclopaedia of Genes and Genomes methods were used to determine whether the duodenal microflora and microbial biofunctions were affected using H. pylori infection.

Results

Thirteen and 34 participants tested positive and negative for H. pylori, respectively. We identified 1,404 bacterial operational taxonomic units from 23 phyla and 253 genera. H. pylori infection changed the relative mean abundance of three phyla (Proteobacteria, Actinobacteria, and TM7) and ten genera (Neisseria, Rothia, TM7-3, Leptotrichia, Lachnospiraceae, Megasphaera, F16, Moryella, Filifactor, and Paludibacter). Microbiota features were significantly influenced in H. pylori-positive participants by 12 taxa mostly classified as Gammaproteobacteria. Microbial functional annotation revealed that H. pylori significantly affected 12 microbial metabolic pathways.

Conclusions

H. pylori disrupted normal bacterial communities in the duodenum and changed the biofunctions of commensal microbiota primarily by upregulating specific metabolic pathways. Such upregulation may be involved in the onset of diseases associated with H. pylori infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02437-w.

Evaluation and Differential Diagnosis of a Genetic Marked Brucella Vaccine A19ΔvirB12 for Cattle

Brucella abortus is an important zoonotic pathogen that causes severe economic loss to husbandry and poses a threat to human health. The B. abortus A19 live vaccine has been extensively used to prevent bovine brucellosis in China. However, it is difficult to distinguish the serological response induced by A19 from that induced by natural infection. In this study, a novel genetically marked vaccine, A19ΔvirB12, was generated and evaluated. The results indicated that A19ΔvirB12 was able to provide effective protection against B. abortus 2308 (S2308) challenge in mice. Furthermore, the safety and protective efficacy of A19ΔvirB12 have been confirmed in natural host cattle. Additionally, the VirB12 protein allowed for serological differentiation between the S2308 challenge/natural infection and A19ΔvirB12 vaccination. However, previous studies have found that the accuracy of the serological detection based on VirB12 needs to be improved. Therefore, we attempted to identify potential supplementary antigens with differential diagnostic functions by combining label-free quantitative proteomics and protein chip technology. Twenty-six proteins identified only in S2308 were screened; among them, five proteins were considered as potential supplementary antigens. Thus, the accuracy of the differential diagnosis between A19ΔvirB12 immunization and field infection may be improved through multi-antigen detection. In addition, we explored the possible attenuation factors of Brucella vaccine strain. Nine virulence factors were downregulated in A19ΔvirB12. The downregulation pathways of A19ΔvirB12 were significantly enriched in quorum sensing, ATP-binding cassette transporter, and metabolism. Several proteins related to cell division were significantly downregulated, while some proteins involved in transcription were upregulated in S2308. In conclusion, our results contribute to the control and eradication of brucellosis and provide insights into the mechanisms underlying the attenuation of A19ΔvirB12.

Lactobacillus reuteri versus triple therapy for the eradication of Helicobacter pylori in functional dyspepsia

Background and aim

The eradication of H. pylori infection using PPI associated with different combinations of two or three antibiotics entails high risks of side effects and non- adherence. Therefore probiotics have been proposed for H. pylori eradication.We tested the efficacy of Lactobacillus reuteri plus Pantoprazole compared to a triple regimen based on Pantoprazole plus Amoxicillin plus Clarithromycin in patients with H. pylori infection and functional dyspepsia.

Methods

In a prospective design, 46 patients (M: 13, F: 33, mean age 48.80 ± 13.82 years) fulfilled the following inclusion criteria: age at least 18, documented informed consent, positive H. pylori finding by histology, no morphological changes of the gastric mucosa at upper gastrointestinal endoscopy and complaints of functional dyspepsia according to the Rome III criteria. Exclusion criteria were: presence of any other chronic organic diseases that required drug treatment, use of antibiotics, PPIs or H2 antagonists in the previous 3 months; pregnancy or lactation. Patients were randomly divided into two equal groups (23 patients each group). One group received the standard therapy in our area: Pantoprazole 40 mg bid for 30 days associated with Amoxicillin 2×1000 mg/day and Clarithromycin 500 mg bid for 14 days. The other group received Pantoprazole 40 mg/day plus L. reuteri DSMZ 17648 twice a day for 8 weeks. Post-treatment eradication was tested by H. pylori antigen stool assay at 30 days after therapy.

Results

The group on L. reuteri plus Pantoprazole presented 65.22% eradication rate compared to 73.91% cure rate in the group that received the Pantoprazole and Amoxicillin and Clarithromycin therapy, with no statistically significant difference in eradication rate between the two groups (p=0.75). The total adherence was good and eradication of H. pylori was associated with improvement of dyspeptic symptoms for both eradication regimens.

Conclusion

L. reuteri is a good alternative for patients with chronic dyspepsia for the eradication of H. pylori infection. Its efficacy is similar to the triple therapy.

Synergistic effect of anti-Helicobacter pylori urease immunoglobulin Y from egg yolk of immunized hens and Lactobacillus johnsonii No.1088 to inhibit the growth of Helicobacter pylori in vitro and in vivo

Helicobacter pylori is a pathogenic bacterium that infects the stomach, causing chronic gastritis; and it is also considered to be related to the occurrence of gastric cancers. Although some eradication regimens including multiple antibiotics have been developed, the emergence of resistance to antibiotics becomes problematic. Therefore, other approaches to compensate or augment the effects of standard regimens are needed. In this study, we examined the possible synergistic effects of anti-H. pylori urease IgY and Lactobacillus johnsonii No.1088 (LJ88) both in vitro and in vivo. Anti-H. pylori urease IgY was purified from egg yolks laid by the hens immunized with urease purified from H. pylori. LJ88 is a unique strain of lactic acid bacterium isolated from human gastric juice, and it has been reported to inhibit H. pylori both in vitro and in vivo. The in vitro mixed culture study showed that anti-H. pylori urease IgY augmented the anti-H. pylori activity of LJ88 against both clarithromycin-sensitive and -resistant H. pylori strains. In a germ-free mice infection model, combined administration of daily anti-H. pylori urease IgY and weekly living LJ88 significantly reduced H. pylori infections, whereas either monotherapy did not. In an in vivo human gut microbiota-associated mice model, not only daily administration of living LJ88 but also heat-killed one significantly reduced an H. pylori infection in the stomach when combined with anti-H. pylori urease IgY. The extent of reduction of the stomach H. pylori by such a combination therapy was larger than that reported for LJ88 monotherapy. These results taken together revealed a synergistic effect of anti-H. pylori urease IgY and living or heat-killed LJ88, thus suggesting that such a combination might be a promising therapy to possibly compensate and/or augment standard anti-H. pylori regimens.

Helicobacter pylori outer membrane vesicles involvement in the infection development and Helicobacter pylori-related diseases

Helicobacter pylori - (H. pylori) play a role in the pathogenesis of gastritis, gastric and duodenal ulcers as well as gastric cancer. A possible involvement of outer membrane vesicles (OMVs) produced by H. pylori in the distribution of bacterial antigens through the gastric epithelial barrier and their role in the development of local and systemic host inflammatory and immune responses has been suggested. OMVs contain various biologically active compounds, which internalize into host cells affecting signaling pathways and promoting apoptosis of gastric epithelial and immunocompetent cells. OMVs-associated H. pylori virulence factors may strengthen or downregulate the immune responses leading to disease development. This review describes the biological importance of H. pylori OMVs and their role in the course of H. pylori infections, as well as H. pylori related local and systemic effects.

Global Fecal and Plasma Metabolic Dynamics Related to Helicobacter pylori Eradication

Background:Helicobacter pylori colonizes the gastric mucosa of more than half of the world's population. There is increasing evidence H. pylori protects against the development of obesity and childhood asthma/allergies in which the development of these diseases coincide with transient dysbiosis. However, the mechanism underlying the association of H. pylori eradication with human metabolic and immunological disorders is not well-established. In this study, we aimed to investigate the local and systemic effects of H. pylori eradication through untargeted fecal lipidomics and plasma metabolomics approaches by liquid chromatography mass spectrometry (LC-MS).

Results: Our study revealed that eradication of H. pylori eradication (i.e., loss of H. pylori and/or H. pylori eradication therapy) changed many global metabolite/lipid features, with the majority being down-regulated. Our findings primarily show that H. pylori eradication affects the host energy and lipid metabolism which may eventually lead to the development of metabolic disorders.

Conclusion: These predictive metabolic signatures of metabolic and immunological disorders following H. pylori eradication can provide insights into dynamic local and systemic metabolism related to H. pylori eradication in modulating human health.

The inhibitory effect of flavonoids on interleukin-8 release by human gastric adenocarcinoma (AGS) cells infected with cag PAI (+) Helicobacter pylori

Introduction

It is well known that the presence of Helicobacter pylori in the stomach induces gastritis and causes an immune response. Exposure of gastric epithelial cell lines to this germ induces the secretion of interleukin-8 (IL-8), which is a potent PMN-activating chemotactic cytokine. Interleukin-8 is usually elevated in gastric biopsy samples of patients with H. pylori-associated gastritis and significantly increases in the supernatant of in vitro cultivated biopsy samples of gastric mucosa with active H. pylori gastritis. Interleukin-8 is an activating factor for leucocytes and other pro-inflammatory factors, free radicals, and proteolytic enzymes. That is why natural compounds potentially useful in therapy are still investigated – among them flavonoids. They reveal anti-oxidative and anti-inflammatory activities and significantly inhibit the gastric mucosa damage.

The aim of the study

Was the estimation of the anti-inflammatory effects of flavonoids on H. pylori-induced activation of human gastric adenocarcinoma cells (AGS). After infection of AGS cells by cag PAI (+) H. pylori in vitro, secretion of IL-8, effects of flavonoids on viability of AGS cells, and effects of flavonoids on increase of H. pylori were determined. Such flavones as chrysin, quercetin, kaemferide, flavanone, galangin, and kaempferol were examined.

Results

This study has shown an inhibitory effect of flavonoids on the release of IL-8 through infected AGS cells (except chrysin), and no toxic effects to AGS cells were observed. Galangin revealed antibacterial effects against H. pylori. Flavonoids limit the inflammatory process through the inhibition of IL-8 release in infected AGS cells with H. pylori. The strongest inhibitor of IL-8 was galangin.

Helicobacter pylori Eradication Causes Perturbation of the Human Gut Microbiome in Young Adults

Background

Accumulating evidence shows that Helicobacter pylori protects against some metabolic and immunological diseases in which the development of these diseases coincide with temporal or permanent dysbiosis. The aim of this study was to assess the effect of H. pylori eradication on the human gut microbiome.

Methods

As part of the currently on-going ESSAY (Eradication Study in Stable Adults/Youths) study, we collected stool samples from 17 H. pylori-positive young adult (18–30 years-old) volunteers. The same cohort was followed up 6, 12 and 18 months-post H. pylori eradication. The impact of H. pylori on the human gut microbiome pre- and post-eradication was investigated using high throughput 16S rRNA gene (V3-V4 region) sequencing using the Illumina Miseq followed by data analysis using Qiime pipeline.

Results

We compared the composition and diversity of bacterial communities in the fecal microbiome of the H. pylori-positive volunteers, before and after H. pylori eradication therapy. The 16S rRNA gene was sequenced at an average of 150,000–170,000 reads/sample. The microbial diversity were similar pre- and post-H. pylori eradication with no significant differences in richness and evenness of bacterial species. Despite that the general profile of the gut microbiome was similar pre- and post-eradication, some changes in the bacterial communities at the phylum and genus levels were notable, particularly the decrease in relative abundance of Bacterioidetes and corresponding increase in Firmicutes after H. pylori eradication. The significant increase of short-chain fatty acids (SCFA)-producing bacteria genera could also be associated with increased risk of metabolic disorders.

Conclusions

Our preliminary stool metagenomics study shows that eradication of H. pylori caused perturbation of the gut microbiome and may indirectly affect the health of human. Clinicians should be aware of the effect of broad spectrum antibiotics used in H. pylori eradication regimen and be cautious in the clinical management of H. pylori infection, particularly in immunocompromised patients.

Changes in Metabolic Hormones in Malaysian Young Adults following Helicobacter pylori Eradication

BACKGROUND

More than half of the world's adults carry Helicobacter pylori. The eradication of H. pylori may affect the regulation of human metabolic hormones. The aim of this study was to evaluate the effect of H. pylori eradication on meal-associated changes in appetite-controlled insulinotropic and digestive hormones, and to assess post-eradication changes in body mass index as part of a currently on-going multicentre ESSAY (Eradication Study in Stable Adults/Youths) study.

METHODS

We enrolled 29 H. pylori-positive young adult (18-30 year-old) volunteer subjects to evaluate the effect of H. pylori eradication on meal-associated changes on eight gastrointestinal hormones, using a multiplex bead assay. Changes in body mass index and anthropometric measurements were recorded, pre- and post-eradication therapy.

RESULTS

Pre-prandial active amylin, total peptide YY (PYY) and pancreatic polypeptide (PP) levels were significantly elevated 12 months post-eradication compared with baseline (n = 18; Wilcoxon's signed rank test, p<0.05). Four of the post-prandial gut metabolic hormones levels (GLP-1, total PYY, active amylin, PP) were significantly higher 12 months post-eradication compared to baseline (n = 18; p<0.05). Following H. pylori eradication, the BMI and anthropometric values did not significantly change.

CONCLUSIONS

Our study indicates that H. pylori eradication was associated with long-term disturbance in three hormones (active amylin, PP and total PYY) both pre- and post-prandially and one hormone (GLP-1) post-prandially. Longer post-eradication monitoring is needed to investigate the long-term impact of the observed hormonal changes on metabolic homeostasis.

Exploring alternative treatments for Helicobacter pylori infection

Helicobacter pylori (H. pylori) is a successful pathogen that can persist in the stomach of an infected person for their entire life. It provokes chronic gastric inflammation that leads to the development of serious gastric diseases such as peptic ulcers, gastric cancer and Mucosa associated lymphoid tissue lymphoma. It is known that these ailments can be avoided if the infection by the bacteria can be prevented or eradicated. Currently, numerous antibiotic-based therapies are available. However, these therapies have several inherent problems, including the appearance of resistance to the antibiotics used and associated adverse effects, the risk of re-infection and the high cost of antibiotic therapy. The delay in developing a vaccine to prevent or eradicate the infection has furthered research into new therapeutic approaches. This review summarises the most relevant recent studies on vaccine development and new treatments using natural resources such as plants, probiotics and nutraceuticals. In addition, novel alternatives based on microorganisms, peptides, polysaccharides, and intragastric violet light irradiation are presented. Alternative therapies have not been effective in eradicating the bacteria but have been shown to maintain low bacterial levels. Nevertheless, some of them are useful in preventing the adverse effects of antibiotics, modulating the immune response, gastroprotection, and the general promotion of health. Therefore, those agents can be used as adjuvants of allopathic anti-H. pylori eradication therapy.

Motility is crucial for the infectious life cycle of Borrelia burgdorferi

The Lyme disease spirochete, Borrelia burgdorferi, exists in a zoonotic cycle involving an arthropod tick and mammalian host. Dissemination of the organism within and between these hosts depends upon the spirochete's ability to traverse through complex tissues. Additionally, the spirochete outruns the host immune cells while migrating through the dermis, suggesting the importance of B. burgdorferi motility in evading host clearance. B. burgdorferi's periplasmic flagellar filaments are composed primarily of a major protein, FlaB, and minor protein, FlaA. By constructing a flaB mutant that is nonmotile, we investigated for the first time the absolute requirement for motility in the mouse-tick life cycle of B. burgdorferi. We found that whereas wild-type cells are motile and have a flat-wave morphology, mutant cells were nonmotile and rod shaped. These mutants were unable to establish infection in C3H/HeN mice via either needle injection or tick bite. In addition, these mutants had decreased viability in fed ticks. Our studies provide substantial evidence that the periplasmic flagella, and consequently motility, are critical not only for optimal survival in ticks but also for infection of the mammalian host by the arthropod tick vector.

Expression of CagL from Helicobacter pylori and Preliminary Study of its Biological Function

Helicobacter pylori (H. pylori) is a highly successful human-specific gastric pathogen, infecting over half the world's population. Virulent H. pylori isolates harbour the cytotoxin-associated genes pathogenicity island (cag-PAI), the majority of which have no known function. In this study, we used cell infection assay and reverse transcriptase PCR, identified that CagL recombinant protein, one of the cag-PAI proteins, induced GES-1 cells to express cytokine IL-8. Then we performed western blot and translocation assay. Our result showed CagL polyclonal antibody counteracted translocation of CagA. This will provide a foundation for the further studies on its biological function.

In silico prediction of exposure amino acid sequences of outer inflammatory protein A of Helicobacter pylori for surface display on Eschierchia coli

BACKGROUND:

Outer inflammatory protein A (OipA) is an outer membrane protein of Helicobacter pylori that is involved in inducing IL-8 and intracellular signaling. In this study, we have predicted exposure amino acid sequences of OipA for insertion in permissive sites of CstH subunit of Eschierchia coli CS3 pilli for bacterial surface display.

MATERIALS AND METHODS:

Databases: National Center for Biotechnology Institute and Protein Data Bank. Servers: PHD, SABLE, GOR 4, SignalP3.0, TBBpred, PRODIV-TMHMM, TMRPres2D, CPH Models, PHYRE, GETAREA, VADAR, Pep state and pep window. Software: Swiss PDB viewer and Discovery studio.

RESULTS:

In silico prediction of exposure amino acid sequences of OipA led to detection of six sequences of amino acid, 76-87, 106-112, 170-182, 222-230, 242-258, and 278-290. These sequences inserted between amino acid sequences 66-67, 100-101, and 109-110 of CstH that were predicted by Eskandari et al. as permissive sites of CstH.

CONCLUSION:

OipA has the ability to induce IL-8 from gastric epithelial cells and some papers are mentioned that this outer membrane protein involve to attachment and intracellular signaling. Receptor of OipA and adhesion motifs on this protein is unknown. Detection of exposure motifs aids to recognition of adhesion motifs and receptor of OipA on gastric epithelial cells. In this study, we have predicted exposure amino acid sequences for insert to subunit CstH of CS3 pilli E. coli for surface display.

Helicobacter pylori in dental plaque and stomach of patients from Northern Brazil

AIM: To establish whether virulence factor genes vacA and cagA are present in Helicobacter pylori (H. pylori) retrieved from gastric mucosa and dental plaque in patients with dyspepsia.

METHODS: Cumulative dental plaque specimens and gastric biopsies were submitted to histological examination, rapid urease test and polymerase chain reaction (PCR) assays to detect the presence of cagA and vacA polymorphisms.

RESULTS: Detection of H. pylori from dental plaque and gastric biopsy samples was greater by PCR compared to histological examination and the rapid urease test. DNA from H. pylori was detected in 96% of gastric mucosa samples and in 72% of dental plaque samples. Sixty-three (89%) of 71 dental plaque samples that were H. pylori-positive also exhibited identical vacA and cagA genotypes in gastric mucosa. The most common genotype was vacAs1bm1 and cagA positive, either in dental plaque or gastric mucosa. These virulent H. pylori isolates were involved in the severity of clinical outcome.

CONCLUSION: These pathogenic strains were found simultaneously in dental plaque and gastric mucosa, which suggests that gastric infection is correlated with the presence of H. pylori in the mouth.

Helicobacter pylori and gastric adenocarcinoma

Gastric cancer is the second most common cause of cancer death worldwide. A large body of evidence supports a causal role of Helicobacter pylori in the majority of gastric malignancies. Great strides have been made in understanding the pathogenesis of this relationship, but much remains to be learned. Moreover, because of the high prevalence of infection, the lack of definitive trials, and the challenges of H. pylori treatment, there remains no consensus on the role of routine screening and treatment of this infection to prevent cancer. This article reviews the current knowledge on H. pylori and gastric cancer and presents some of the clinical and public health challenges associated with this pathogen.

Structural and mechanistic insights into Helicobacter pylori NikR activation

NikR is a transcriptional metalloregulator central in the mandatory response to acidity of Helicobacter pylori that controls the expression of numerous genes by binding to specific promoter regions. NikR/DNA interactions were proposed to rely on protein activation by Ni(II) binding to high-affinity (HA) and possibly secondary external (X) sites. We describe a biochemical characterization of HpNikR mutants that shows that the HA sites are essential but not sufficient for DNA binding, while the secondary external (X) sites and residues from the HpNikR dimer–dimer interface are important for DNA binding. We show that a second metal is necessary for HpNikR/DNA binding, but only to some promoters. Small-angle X-ray scattering shows that HpNikR adopts a defined conformation in solution, resembling the cis-conformation and suggests that nickel does not trigger large conformational changes in HpNikR. The crystal structures of selected mutants identify the effects of each mutation on HpNikR structure. This study unravels key structural features from which we derive a model for HpNikR activation where: (i) HA sites and an hydrogen bond network are required for DNA binding and (ii) metallation of a unique secondary external site (X) modulates HpNikR DNA binding to low-affinity promoters by disruption of a salt bridge.

Helicobacter pylori colonization of the human gastric epithelium: a bug's first step is a novel target for us

After Helicobacter pylori enters the stomach, three steps are vital for infection: (i) establishing colonization; (ii) evading host immunity; and (iii) invading gastric mucosa; the last step is what is associated with diverse outcomes. Urease activity and motility mediated by the flagella of H. pylori are important in harboring colonies beneath the gastric mucus in niches adjacent to the epithelium. Several putative adhesins attach the organism to the gastric epithelium and prompt the succeeding processes for evading host immunity and invading the mucosa. Successful colonization is thus the leading and critical step. From another point of view, this can be a novel target to control this common and important infection. This review summarizes the putative adhesins that influence the evasion of host immunity, and how these could determine different clinico-pathologic outcomes. The putative adhesins include the interplay between bacterial and host Lewis antigens (type I: Le(a) and Le(b); type II: Le(x) and Le(y)), the dominant pathway between BabA and Le(b), the SabA adhesin binding to sialylated Le(x) that is upregulated in inflamed gastric tissue or those with weak-Le(b), the CagL apparatus to adapt with the alpha5beta1 integrin to mediate a type IV secretory system for CagA translocation into the epithelium; and other outer membrane proteins as HopZ, AlpA/AlpB, or OipA, without known corresponding receptors. This review implicates the adhesins vital for bugs that could be alternatively provided as novel targets for us to overcome the colonization.

Helicobacter pylori urease activates blood platelets through a lipoxygenase-mediated pathway

The bacterium Helicobacter pylori causes peptic ulcers and gastric cancer in human beings by mechanisms yet not fully understood. H. pylori produces urease which neutralizes the acidic medium permitting its survival in the stomach. We have previously shown that ureases from jackbean, soybean or Bacillus pasteurii induce blood platelet aggregation independently of their enzyme activity by a pathway requiring platelet secretion, activation of calcium channels and lipoxygenase-derived eicosanoids. We investigated whether H. pylori urease displays platelet-activating properties and defined biochemical pathways involved in this phenomenon. For that the effects of purified recombinant H. pylori urease (HPU) added to rabbit platelets were assessed turbidimetrically. ATP secretion and production of lipoxygenase metabolites by activated platelets were measured. Fluorescein-labelled HPU bound to platelets but not to erythrocytes. HPU induced aggregation of rabbit platelets (ED(50) 0.28 microM) accompanied by ATP secretion. No correlation was found between platelet activation and ureolytic activity of HPU. Platelet aggregation was blocked by esculetin (12-lipoxygenase inhibitor) and enhanced approximately 3-fold by indomethacin (cyclooxygenase inhibitor). A metabolite of 12-lipoxygenase was produced by platelets exposed to HPU. Platelet responses to HPU did not involve platelet-activating factor, but required activation of verapamil-inhibitable calcium channels. Our data show that purified H. pylori urease activates blood platelets at submicromolar concentrations. This property seems to be common to ureases regardless of their source (plant or bacteria) or quaternary structure (single, di- or tri-chain proteins). These properties of HPU could play an important role in pathogenesis of gastrointestinal and associated cardiovascular diseases caused by H. pylori.

Helicobacter pylori: phenotypes, genotypes and virulence genes

Helicobacter pylori is a Gram-negative, microaerophilic bacterium that colonizes the gastric mucus overlying the epithelium of the stomach in more than 50% of the world's population. This gastric colonization induces chronic gastric inflammation in all infected individuals, but only induces clinical diseases in 10-20% of infected individuals. These include peptic ulcers, acute and atrophic gastritis, intestinal metaplasia, gastric adenocarcinoma and gastric B-cell lymphoma. Various bacterial virulence factors are associated with the development of such gastric diseases, and the characterization of these markers could aid medical prognosis, which could be extremely important in predicting clinical outcomes. The purpose of this review is to summarize the role of the phenotypes, virulence-related genes and genotypes of H. pylori in the establishment of gastric colonization and the development of associated diseases.

Lessons from nature: "Pathogen-Mimetic" systems for mucosal nano-medicines

Mucosal surfaces establish an interface with external environments that provide a protective barrier with the capacity to selectively absorb and secrete materials important for homeostasis of the organism. In man, mucosal surfaces such as those in the gastrointestinal tract, respiratory tree and genitourinary system also represent significant barrier to the successful administration of certain pharmaceutical agents and the delivery of newly designed nano-scale therapeutic systems. This review examines morphological, physiological and biochemical aspects of these mucosal barriers and presents currently understood mechanisms used by a variety of virulence factors used by pathogenic bacteria to overcome various aspects of these mucosal barriers. Such information emphasizes the impediments that biologically active materials must overcome for absorption across these mucosal surfaces and provides a template for strategies to overcome these barriers for the successful delivery of nano-scale bioactive materials, also known as nano-medicines.

Genome sequencing and analysis reveals possible determinants of Staphylococcus aureus nasal carriage

Background

Nasal carriage of Staphylococcus aureus is a major risk factor in clinical and community settings due to the range of etiologies caused by the organism. We have identified unique immunological and ultrastructural properties associated with nasal carriage isolates denoting a role for bacterial factors in nasal carriage. However, despite extensive molecular level characterizations by several groups suggesting factors necessary for colonization on nasal epithelium, genetic determinants of nasal carriage are unknown. Herein, we have set a genomic foundation for unraveling the bacterial determinants of nasal carriage in S. aureus.

Results

MLST analysis revealed no lineage specific differences between carrier and non-carrier strains suggesting a role for mobile genetic elements. We completely sequenced a model carrier isolate (D30) and a model non-carrier strain (930918-3) to identify differential gene content. Comparison revealed the presence of 84 genes unique to the carrier strain and strongly suggests a role for Type VII secretion systems in nasal carriage. These genes, along with a putative pathogenicity island (SaPIBov) present uniquely in the carrier strains are likely important in affecting carriage. Further, PCR-based genotyping of other clinical isolates for a specific subset of these 84 genes raise the possibility of nasal carriage being caused by multiple gene sets.

Conclusion

Our data suggest that carriage is likely a heterogeneic phenotypic trait and implies a role for nucleotide level polymorphism in carriage. Complete genome level analyses of multiple carriage strains of S. aureus will be important in clarifying molecular determinants of S. aureus nasal carriage.

Targeting focal adhesions:Helicobacter pylori-host communication in cell migration

Highly dynamic integrin-based focal adhesions provide an important structural basis for anchoring the cellular actin cytoskeleton to the surrounding extracellular matrix. The human pathogen Helicobacter pylori (H. pylori) directly targets integrins with drastic consequences on the epithelial cell morphology and migration, which might contribute to the disruption of the gastric epithelium in vivo. In this review, we summarize the recent findings concerning the complex mechanism through which H. pylori interferes with host integrin signaling thereby deregulating focal adhesions and the actin cytoskeleton of motile epithelial cells.

Parallels between pathogens and gluten peptides in celiac sprue

Pathogens are exogenous agents capable of causing disease in susceptible organisms. In celiac sprue, a disease triggered by partially hydrolyzed gluten peptides in the small intestine, the offending immunotoxins cannot replicate, but otherwise have many hallmarks of classical pathogens. First, dietary gluten and its peptide metabolites are ubiquitous components of the modern diet, yet only a small, genetically susceptible fraction of the human population contracts celiac sprue. Second, immunotoxic gluten peptides have certain unusual structural features that allow them to survive the harsh proteolytic conditions of the gastrointestinal tract and thereby interact extensively with the mucosal lining of the small intestine. Third, they invade across epithelial barriers intact to access the underlying gut-associated lymphoid tissue. Fourth, they possess recognition sequences for selective modification by an endogenous enzyme, transglutaminase 2, allowing for in situ activation to a more immunotoxic form via host subversion. Fifth, they precipitate a T cell–mediated immune reaction comprising both innate and adaptive responses that causes chronic inflammation of the small intestine. Sixth, complete elimination of immunotoxic gluten peptides from the celiac diet results in remission, whereas reintroduction of gluten in the diet causes relapse. Therefore, in analogy with antibiotics, orally administered proteases that reduce the host's exposure to the immunotoxin by accelerating gluten peptide destruction have considerable therapeutic potential. Last but not least, notwithstanding the power of in vitro methods to reconstitute the essence of the immune response to gluten in a celiac patient, animal models for the disease, while elusive, are likely to yield fundamentally new systems-level insights.

Sodium chloride affects Helicobacter pylori growth and gene expression

Epidemiological evidence links high-salt diets and Helicobacter pylori infection with increased risk of developing gastric maladies. The mechanism by which elevated sodium chloride content causes these manifestations is unclear. Here we characterize the response of H. pylori to temporal changes in sodium chloride concentration and show that growth, cell morphology, survival, and virulence factor expression are all altered by increased salt concentration.

Relevance of MUC1 mucin variable number of tandem repeats polymorphism in H pylori adhesion to gastric epithelial cells

AIM: To evaluate the influence of MUC1 mucin variable number of tandem repeats (VNTR) variability on H pylori adhesion to gastric cells.

METHODS: Enzyme linked immunosorbent assay (ELISA)-based adhesion assays were performed to measure the adhesion of different H pylori strains (HP26695 and HPTx30a) to gastric carcinoma cell lines (GP202 and MKN45) and GP202 clones expressing recombinant MUC1 with different VNTR lengths.

RESULTS: Evaluation of adhesion results shows that H pylori pathogenic strain HP26695 has a significantly higher (P < 0.05) adhesion to all the cell lines and clones tested, when compared to the non-pathogenic strain HPTx30a. Bacteria showed a significantly higher (P < 0.05) adhesion to the GP202 cell line, when compared to the MKN45 cell line. Furthermore, both strains showed a significantly higher (P < 0.05) adhesion to GP202 clones with larger MUC1 VNTR domains.

CONCLUSION: This work shows that MUC1 mucin variability conditions H pylori binding to gastric cells. The extent of bacterial adhesion depends on the size of the MUC1 VNTR domain. The adhesion is further dependent on bacterial pathogenicity and the gastric cell line. MUC1 mucin variability may contribute to determine H pylori colonization of the gastric mucosa.

Prevention of cancer through immunization: Prospects and challenges for the 21st century

Persistent infection by several microbial agents is responsible for at least 15% of cancer globally, including most cancers of the liver, stomach, and cervix. The recent development of vaccines that can prevent infection and premalignant disease caused by human papillomaviruses (HPV), which cause virtually all cases of cervical cancer as well as some other cancers, has focused renewed attention on infection control as a means of reducing the global cancer burden. For vaccines to prevent cancer-causing infection with hepatitis C virus, Helicobacter pylori, or Epstein Barr virus, new vaccine technologies to induce more effective protective responses are required. For the two available cancer control vaccines, designed to prevent infection with HPV and hepatitis B virus, the major challenge is to promote effective vaccine deployment through education programs and increased affordability/accessibility for underserved populations, particularly in the developing world, where the cancer burden attributable to infection by these two viruses is greatest.