Genetic microheterogeneity and phenotypic variation of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> arginase in clinical isolates

Background  

Clinical isolates of the gastric pathogen Helicobacter pylori display a high level of genetic macro- and microheterogeneity, featuring a panmictic, rather than clonal structure. The ability of H. pylori to survive the stomach acid is due, in part, to the arginase-urease enzyme system. Arginase (RocF) hydrolyzes L-arginine to L-ornithine and urea, and urease hydrolyzes urea to carbon dioxide and ammonium, which can neutralize acid.     

Unraveling the <Emphasis Type="Italic">Helicobacter pylori</Emphasis> UreG zinc binding site using X-ray absorption spectroscopy (XAS) and structural modeling

Abstract  

The pathogenicity of Helicobacter pylori depends on the activity of urease for pH modification. Urease activity requires assembly of a dinickel active site that is facilitated in part by GTP hydrolysis by UreG. The proper functioning of Helicobacter pylori UreG (HpUreG) is dependent on Zn(II) binding and dimerization. X-ray absorption spectroscopy and structural modeling were used to elucidate the structure of the Zn(II) site in HpUreG. These studies independently indicated a site at the dimer interface that has trigonal bipyramidal geometry and is composed of two axial cysteines at 2.29(2) ?, two equatorial histidines at 1.99(1) ?, and a solvent-accessible coordination site. The final model for the Zn(II) site structure was determined by refining multiple-scattering extended X-ray absorption fine structure fits using the geometry predicted by homology modeling and ab initio calculations.     

Immunological features and the ability of inhibitory effects on enzymatic activity of an epitope vaccine composed of cholera toxin B subunit and B cell epitope from <Emphasis Type="Italic">Helicobacter pylori</Emphasis> urease A subunit

Epitope vaccine based on urease of Helicobacter pylori is a promising option for prophylactic and therapeutic vaccination against H. pylori infection. In this study, we constructed an epitope vaccine with mucosal adjuvant cholera toxin B subunit (CTB) and an epitope (UreA_183-203) of H. pylori urease A subunit named CTB-UA. The CTB-UA fusion protein was expressed in Escherichia coli, and the purified protein was used for intraperitoneal immunization experiments in BALB/c mice. The experimental results indicated that anti-CTB-UA antibody could recognize both H. pylori urease A subunit (UreA) and urease B subunit (UreB). Besides, the CTB-UA epitope vaccine had good immunogenicity and immunoreactivity and could induce specific neutralizing antibodies which showed effectively inhibitory effect on the enzymatic activity of H. pylori urease. CTB-UA is a promising molecule to be investigated as H. pylori vaccine antigen candidate.     

Expression and display of UreA of <Emphasis Type="Italic">Helicobacter acinonychis</Emphasis> on the surface of <Emphasis Type="Italic">Bacillus subtilis</Emphasis> spores

Background  

The bacterial endospore (spore) has recently been proposed as a new surface display system. Antigens and enzymes have been successfully exposed on the surface layers of the Bacillus subtilis spore, but only in a few cases the efficiency of expression and the effective surface display and have been determined. We used this heterologous expression system to produce the A subunit of the urease of the animal pathogen Helicobater acinonychis. Ureases are multi-subunit enzymes with a central role in the virulence of various bacterial pathogens and necessary for colonization of the gastric mucosa by the human pathogen H. pylori. The urease subunit UreA has been recognized as a major antigen, able to induce high levels of protection against challenge infections.     

Beneficial effect of Burdock complex on asymptomatic Helicobacter pylori‐infected subjects: A randomized,double‐blind placebo‐controlled clinical trial

Background

Burdock complex (BC) constitutes of burdock (Arctium lappa), angelica (Angelica sinensis), gromwell (Lithospermum erythrorhizon), and sesame (Sesamum indicum) oil, which are commonly used in traditional Chinese medicine (TCM) for treating various disorders. This study intended to examine the anti‐H. pylori activity of BC on AGS cell model as well as in asymptomatic H. pylori‐infected subjects.

Materials and Methods

AGS cell incubated with H. pylori and treated with BC to evaluate the minimum inhibition concentration (MIC), cell viability (MTT) anti‐adhesion activity, and inflammatory markers. In case of clinical trial, H. pylori‐positive subjects (urea breath test [UBT] >10%, n = 36) were enrolled and requested to intake BC (n = 19) or placebo (n = 17) for 8 weeks. Antioxidant capacity, total phenol, UBT, inflammatory markers were analyzed at the initial, 4th, 8th, and 10th weeks. Moreover, the endoscopic examination was carried out on baseline and 10th week.

Results

In vitro studies showed that BC treatment significantly inhibited (P < .05) the inflammatory markers and adhesion of H. pylori to AGS cell. However, H. pylori‐infected subject ingested with BC for 8 weeks significantly decreased (P < .05) the UBT value, inflammatory markers with improved antioxidant activity, and phenolic levels as compared to placebo. Also, consumption of BC considerably healed the ulcer wound.

Conclusion

Overall, the BC could attenuate H. pylori infection by inhibiting H. pylori adhesion and subsequent inflammatory response on the gastric epithelial cell (AGS) as well as clinically ameliorated UBT, antioxidant capacity, and alleviated inflammation to display its anti‐H. pylori activity.     

A meta‐analysis of the association between Helicobacter pylori (H. pylori) infection and hyperemesis gravidarum

Background

Hyperemesis gravidarum remains a common, distressing, and significant yet poorly understood disorder during pregnancy. The association between maternal Helicobacter pylori (H. pylori) infection and hyperemesis gravidarum has been increasingly recognized and investigated. This study thus aimed to provide an updated review and meta‐analysis of the topic.

Methods

Using the search terms (H. pyloriOR Helicobacter ORHelicobacter pyloriOR infection) AND (pregnancy OR emesis OR hyperemesis gravidarum OR nausea OR vomiting), a preliminary search on the PubMed, Ovid, Web of Science, Google Scholar, and WanFang database yielded 372 papers published in English between January 1st, 1960 and June 1st, 2017.

Results

A total of 38 cross‐sectional and case‐control studies, with a total of 10 289 patients were eligible for review. Meta‐analysis revealed a significant association between H. pylori infection and hyperemesis gravidarum during pregnancy, with a pooled odds ratio of 1.348 (95% CI: 1.156‐1.539, P < .001). Subgroup analysis found that serologic and stool antigen tests were comparable methods of detecting H. pylori as they yielded similar odds ratios.

Limitations

Although the studies did not have high heterogeneity (I² = 28%), publication bias was observed, and interstudy discrepancies in the diagnostic criteria adopted for hyperemesis gravidarum limit the reliability of findings. Also, 15 of the included studies were from the same country (Turkey), which could limit the generalizability of current findings. The prevalence of H. pylori infection varies throughout the world, and there may also be pathogenic differences as most strains of H. pylori in East Asia carry the cytotoxin‐associated gene A gene.

Conclusion

H. pylori infection was associated with an increased likelihood of hyperemesis gravidarum during pregnancy. Given the high prevalence of H. pylori infections worldwide, detecting H. pylori infection and the eradication of maternal H. pylori infection could be part of maternal hyperemesis gravidarum management. Further confirmation with robust longitudinal studies and mechanistic investigations are needed.     

Prophylactic immunization to Helicobacter pylori infection using spore vectored vaccines

Background

Helicobacter pylori infection remains a major public health threat leading to gastrointestinal illness and increased risk of gastric cancer. Mostly affecting populations in developing countries no vaccines are yet available and the disease is controlled by antimicrobials which, in turn, are driving the emergence of AMR.

Materials and Methods

We have engineered spores of Bacillus subtilis to display putative H. pylori protective antigens, urease subunit A (UreA) and subunit B (UreB) on the spore surface. Following oral dosing of mice with these spores, we evaluated immunity and colonization in animals challenged with H. pylori.

Results

Oral immunization with spores expressing either UreA or UreB showed antigen-specific mucosal responses (fecal sIgA) including seroconversion and hyperimmunity. Following challenge, colonization by H. pylori was significantly reduced by up to 1-log.

Conclusions

This study demonstrates the utility of bacterial spores for mucosal vaccination to H. pylori infection. The heat stability and robustness of Bacillus spores coupled with their existing use as probiotics make them an attractive solution for either protection against H. pylori infection or potentially for therapy and control of active infection.     

The human gastric pathogen <Emphasis Type="Italic">Helicobacter pylori</Emphasis> has a potential acetone carboxylase that enhances its ability to colonize mice

Background  

Helicobacter pyloricolonizes the human stomach and is the etiological agent of peptic ulcer disease. All threeH. pyloristrains that have been sequenced to date contain a potential operon whose products share homology with the subunits of acetone carboxylase (encoded byacxABC) fromXanthobacter autotrophicusstrain Py2 andRhodobacter capsulatusstrain B10. Acetone carboxylase catalyzes the conversion of acetone to acetoacetate. Genes upstream of the putativeacxABCoperon encode enzymes that convert acetoacetate to acetoacetyl-CoA, which is metabolized further to generate two molecules of acetyl-CoA.     

Enzymatic,immunological and phylogenetic characterization of <Emphasis Type="Italic">Brucella suis</Emphasis> urease

Background  

The sequenced genomes of the Brucella spp. have two urease operons, ure-1 and ure-2, but there is evidence that only one is responsible for encoding an active urease. The present work describes the purification and the enzymatic and phylogenomic characterization of urease from Brucella suis strain 1330. Additionally, the urease reactivity of sera from patients diagnosed with brucellosis was examined.     

The HP0256 gene product is involved in motility and cell envelope architecture of <Emphasis Type="Italic">Helicobacter pylori</Emphasis>

Background  

Helicobacter pylori is the causative agent for gastritis, and peptic and duodenal ulcers. The bacterium displays 5-6 polar sheathed flagella that are essential for colonisation and persistence in the gastric mucosa. The biochemistry and genetics of flagellar biogenesis in H. pylori has not been fully elucidated. Bioinformatics analysis suggested that the gene HP0256, annotated as hypothetical, was a FliJ homologue. In Salmonella, FliJ is a chaperone escort protein for FlgN and FliT, two proteins that themselves display chaperone activity for components of the hook, the rod and the filament.     

Superoxide dismutase from Helicobacter pylori suppresses the production of pro‐inflammatory cytokines during in vivo infection

Background

Helicobacter pylori has undergone considerable adaptation to allow chronic persistence within the gastric environment. While H. pylori‐associated diseases are driven by an excessive inflammation, severe gastritis is detrimental to colonization by this pathogen. Hence, H. pylori has developed strategies to minimize the severity of gastritis it triggers in its host. Superoxide dismutase (SOD) is well known for its role in protecting against oxidative attack; less recognized is its ability to inhibit immunity, shown for SOD from mammalian sources and those of some bacterial species. This study examined whether H. pylori SOD (HpSOD) has the ability to inhibit the host immune response to these bacteria.

Materials and Methods

The ability of recombinant HpSOD to modify the response to LPS was measured using mouse macrophages. A monoclonal antibody against HpSOD was generated and injected into H. pylori‐infected mice.

Results

Addition of HpSOD to cultures of mouse macrophages significantly inhibited the pro‐inflammatory cytokine response to LPS stimulation. A monoclonal antibody was generated that was specific for SOD from H. pylori. When injected into mice infected with H. pylori for 3 months, this antibody was readily detected in both sera and gastric tissues 5 days later. While treatment with anti‐HpSOD had no effect on H. pylori colonization at this time point, it significantly increased the levels of a range of pro‐inflammatory cytokines in the gastric tissues. This did not occur with antibodies against other antioxidant enzymes.

Conclusions

SOD from H. pylori can inhibit the production of pro‐inflammatory cytokine during in vivo infection.     

Analysis of a β-helical region in the p55 domain of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> vacuolating toxin

Background  

Helicobacter pylori is a gram-negative bacterium that colonizes the human stomach and contributes to the development of gastric cancer and peptic ulcer disease. VacA, a toxin secreted by H. pylori, is comprised of two domains, designated p33 and p55. Analysis of the crystal structure of the p55 domain indicated that its structure is predominantly a right-handed parallel β-helix, which is a characteristic of autotransporter passenger domains. Substitution mutations of specific amino acids within the p33 domain abrogate VacA activity, but thus far, it has been difficult to identify small inactivating mutations within the p55 domain. Therefore, we hypothesized that large portions of the p55 domain might be non-essential for vacuolating toxin activity. To test this hypothesis, we introduced eight deletion mutations (each corresponding to a single coil within a β-helical segment spanning VacA amino acids 433-628) into the H. pylori chromosomal vacA gene.     

<Emphasis Type="Italic">Helicobacter pylori</Emphasis> genome variability in a framework of familial transmission

Background  

Helicobacter pylori infection is exceptionally prevalent and is considered to be acquired primarily early in life through person-to-person transmission within the family. H. pylori is a genetically diverse bacterial species, which may facilitate adaptation to new hosts and persistence for decades. The present study aimed to explore the genetic diversity of clonal isolates from a mother and her three children in order to shed light on H. pylori transmission and host adaptation.     

Anti‐Helicobacter pylori therapy in localized gastric mucosa‐associated lymphoid tissue lymphoma: A prospective,nationwide, multicenter study in Japan

Background

Helicobacter pylori eradication therapy was approved in Japan for the first‐line, standard treatment of H. pylori‐positive gastric mucosa‐associated lymphoid tissue (MALT) lymphoma. Although several retrospective studies or small‐scale single‐center studies have been reported, a prospective, large‐scale, nationwide, multicenter study has not been reported from Japan.

Materials and Methods

We conducted a prospective, nationwide, multicenter study to evaluate the clinical efficacy of rabeprazole‐based triple H. pylori eradication therapy for patients with localized gastric MALT lymphoma in practice‐based clinical trial. A total of 108 H. pylori‐positive patients with stage I/II₁ gastric MALT lymphoma underwent H. pylori eradication therapy. The primary endpoints were complete remission (CR) rate and the rate of transfer to secondary treatment. The secondary endpoints were CR maintenance duration and overall survival (OS).

Results

CR of lymphoma was achieved in 84 of 97 patients (86.6%), during the period 2.0‐44.7 months (median, 5.3 months) after starting H. pylori eradication treatment. CR was maintained in 77 of 81 patients (95.1%) for 0.4‐53.2 months (median, 33.1 months). Secondary treatments (radiotherapy, rituximab, or gastrectomy) for gastric MALT lymphoma were needed in 10 of the 97 patients (10.31%). During follow‐up, OS rate was 96.9% (94/97) and the causes of 3 deaths were not related to lymphoma.

Conclusions

Rabeprazole‐based H. pylori eradication therapy demonstrated a high CR rate, long CR maintenance, and a good OS for patients with localized gastric MALT lymphoma in this prospective, practice‐based, multicenter study.     

Synthesis, molecular docking and biological evaluation of metronidazole derivatives as potent Helicobacter pylori urease inhibitors

Fourteen metronidazole derivatives (compounds 3a–f and 4b–h) have been synthesized by coupling of metronidazole and salicylic acid derivatives. All of them are reported for the first time. Their chemical structures are characterized by ¹H NMR, MS, and elemental analysis. The inhibitory activities against Helicobacter pylori urease have been investigated in vitro and many compounds have showed promising potential inhibitory activities of H. pylori urease. The effect of compounds 4b (IC₅₀ = 26 μM) and 4g (IC₅₀ = 12 μM) was comparable with that of acetohydroxamic acid, a well known H. pylori urease inhibitor used as a positive control. The experimental values of IC₅₀ showed that inhibitor was potent urease inhibitor. A docking analysis using the autodock 4.0 program could explain the inhibitory activities of compound 4g against H. pylori urease.     

Prevalence of Helicobacter pylori among Alaskans: Factors associated with infection and comparison of urea breath test and anti‐Helicobacter pylori IgG antibodies

Background

Helicobacter pylori is one of the most common human infections in the world, and studies in Alaska Native people, as well as other Indigenous peoples, have shown a high prevalence of this gastric infection. This study was undertaken to determine the prevalence of H. pylori infection by urea breath test (UBT) and anti‐ H. pylori IgG among Alaskans living in four regions of the state and to identify factors associated with infection.

Methods

A convenience sample of persons > 6 months old living in five rural and one urban Alaskan community were recruited from 1996 to 1997. Participants were asked about factors possibly associated with infection. Sera were collected and tested for anti‐ H. pylori IgG antibodies; a UBT was administered to participants > 5 years old.

Results

We recruited 710 people of whom 571 (80%) were Alaska Native and 467 (66%) were from rural communities. Rural residents were more likely to be Alaska Native compared with urban residents (P < .001). Of the 710 people, 699 (98%) had a serum sample analyzed, and 634 (97%) persons > 5 years old had a UBT performed. H. pylori prevalence was 69% by UBT and 68% by anti‐ H. pylori IgG. Among those with a result for both tests, there was 94% concordance. Factors associated with H. pylori positivity were Alaska Native racial status, age ≥ 20 years, rural region of residence, living in a crowded home, and drinking water that was not piped or delivered.

Conclusions

Helicobacter pylori prevalence is high in Alaska, especially in Alaska Native persons and rural residents. Concordance between UBT and serology was also high in this group. Two socioeconomic factors, crowding and drinking water that was not piped or delivered, were found to be associated with H. pylori positivity.     

Presence of gastric Helicobacter species in children suffering from gastric disorders in Southern Turkey

Background

Infections with gastric Helicobacter spp. are associated with gastritis, peptic ulceration, and malignancies. Helicobacter pylori is the most prevalent Helicobacter species colonizing the human stomach. Other gastric non‐H. pylori helicobacters (NHPHs) have been described in 0.2%‐6% of human patients with gastric disorders. Nevertheless, due to difficulties in the diagnosis of NHPH infections and lack of routine screening, this is most likely an underestimation of their true prevalence. To the best of our knowledge, no studies have been performed in the presence of Helicobacter spp. in children suffering from gastric disorders in Southern Turkey.

Materials and methods

In total, 110 children with gastric complaints were examined at the Cukurova University Balcali hospital, Turkey. Gastroscopy was performed to evaluate the presence of gastric mucosal lesions. Biopsies of the pyloric gland zone were taken for histopathological analysis, rapid urease testing, and presence of Helicobacter spp. DNA by PCR.

Results

Based on the PCR results, the prevalence of Helicobacter spp. was 32.7% (36/110). H. pylori was found in 30.9% (34/110), H. suis in 1.8% (2/110), and H. heilmannii/H. ailurogastricus in 0.9% (1/110) of the human patients. A mixed infection with H. pylori and H. suis was present in one patient. The presence of mucosal abnormalities, such as nodular inflammation, ulceration, and hyperemia, as well as gastritis, was significantly higher in Helicobacter spp. positive patients.

Conclusion

Helicobacter pylori, H. suis, and H. heilmannii/H. ailurogastricus were present in children with gastric complaints. Infection with these pathogens may be involved in the development of gastritis and ulceration.     

Brief report: Lactobacillus bulgaricus GLB44 (Proviotic™) plus esomeprazole for Helicobacter pylori eradication: A pilot study

Background

Recent studies of Lactobacillus delbrueckii subsp. bulgaricus GLB44 plus a proton‐pump inhibitor (PPI) reported cures of more than 90% of patients with active Helicobacter pylori infections.

Aim

To confirm the high H. pylori cure rates reported previously.

Method

A pilot study was done in healthy H. pylori‐infected volunteers using 3‐gram sachet (3 billion cells) of L. delbrueckii GLB44 plus 22.3 mg of esomeprazole b.i.d., for 14 days. The result was determined by urea breath testing 4 weeks after therapy. Stopping rules required for ending enrollment if less than 3 of the first 10 subjects were cured.

Results

Nine subjects were entered and because all failed to achieve negative urea breath test, the stopping rule required the study to end.

Conclusion

We were unable to confirm reports of achieving a high H. pylori cure rate with L. delbrueckii GLB44 plus a PPI.     

Growth of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> in a long spiral form does not alter expression of immunodominant proteins

Background  

We have previously reported that altered culture conditions (a broth media with shaking) could induce a strain of Helicobacter pylori to assume a long spiral morphology resembling that described for Helicobacter heilmannii. The present study was initiated to determine if other strains of H. pylori could be induced to assume that morphology and if doing so would alter the expression of immunodominant proteins.     

Real‐time PCR for Helicobacter pylori diagnosis. The best tools available

Background

Knowledge of antimicrobial susceptibility, especially to macrolides, has become crucial for the management of Helicobacter pylori infection. Our aim was to evaluate two new PCR kits able to detect H. pylori in gastric biopsies as well as the mutations associated with macrolide resistance.

Materials and Methods

Two hundred successive biopsies (received from gastroenterologists all over France) were used. The two new kits tested were Amplidiag H. pylori+Clari^R from Mobidiag Espoo, Finland, and RIDA^®GENE H. pylori from R‐Biopharm, Darmstadt, Germany. Culture and a validated in‐house real‐time PCR were also performed, and in the case of a positive culture, Etest for clarithromycin was carried out. Discrepancies were solved by looking at the pathologic data.

Results

Culture was positive in 68 cases (34%), and with our in‐house real‐time PCR in these 68 cases plus 5 others (N = 73, 36%). All were also detected by the two new kits. In addition, RIDA^®GENE H. pylori detected one more positive also detected by Amplidiag H. pylori+Clari^R, and Amplidiag detected two other positives. Of these three additional cases, pathology confirmed the positivity for two. Only one case diagnosed by Amplidiag could be considered as a false positive. With regard to clarithromycin resistance, 22 cases were detected. The corresponding mutations (A2142/43G) were all identified with the three PCRs.

Conclusions

These two new kits which have an excellent sensitivity and specificity are convenient to use, adaptable to different thermocyclers, provide quick results, and deserve to be used in H. pylori diagnosis for a better choice of treatment regimen.