H. pylori is one of the most common bacterial infections in human beings, and its discovery 20 years ago altered the diagnosis and treatment of gastroduodenal disease. This review considers current knowledge about the epidemiology and transmission of H. pylori, as well as the role of this infectious agent in the pathogenesis of upper gastrointestinal tract disease. Diagnostic approaches, indications for therapy, and measures of therapeutic efficacy are reviewed.

Helicobacter pylori infection.

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.

Pathogenesis of Helicobacter pylori Infection

Bacterial ureases in infectious diseases

Helicobacter pylori infection induces the appearance of inflammatory infiltrates, consisting mainly of neutrophils and monocytes, in the human gastric mucosa. A bacterial protein with neutrophil activating activity (HP-NAP) has been previously identified, but its role in infection and immune response is still largely unknown. Here, we show that vaccination of mice with HP-NAP induces protection against H. pylori challenge, and that the majority of infected patients produce antibodies specific for HP-NAP, suggesting an important role of this factor in immunity. We also show that HP-NAP is chemotactic for human leukocytes and that it activates their NADPH oxidase to produce reactive oxygen intermediates, as demonstrated by the translocation of its cytosolic subunits to the plasma membrane, and by the lack of activity on chronic granulomatous disease leukocytes. This stimulating effect is strongly potentiated by tumor necrosis factor α and interferon γ and is mediated by a rapid increase of the cytosolic calcium concentration. The activation of leukocytes induced by HP-NAP is completely inhibited by pertussis toxin, wortmannin, and PP1. On the basis of these results, we conclude that HP-NAP is a virulence factor important for the H. pylori pathogenic effects at the site of infection and a candidate antigen for vaccine development.

/pdf/the-neutrophil-activating-protein-hp-nap-of-helicobacter-3ztj7yvkud.pdf

The neutrophil-activating protein (HP-NAP) of Helicobacter pylori is a protective antigen and a major virulence factor.

Background An association was previously established between facial nerve paralysis (Bell's palsy) and intranasal administration of an inactivated influenza virosome vaccine containing an enzymatically active Escherichia coli Heat Labile Toxin (LT) adjuvant. The individual component(s) responsible for paralysis were not identified, and the vaccine was withdrawn. Methodology/Principal Findings Subjects participating in two contemporaneous non-randomized Phase 1 clinical trials of nasal subunit vaccines against Human Immunodeficiency Virus and tuberculosis, both of which employed an enzymatically inactive non-toxic mutant LT adjuvant (LTK63), underwent active follow-up for adverse events using diary-cards and clinical examination. Two healthy subjects experienced transient peripheral facial nerve palsies 44 and 60 days after passive nasal instillation of LTK63, possibly a result of retrograde axonal transport after neuronal ganglioside binding or an inflammatory immune response, but without exaggerated immune responses to LTK63. Conclusions/Significance While the unique anatomical predisposition of the facial nerve to compression suggests nasal delivery of neuronal-binding LT–derived adjuvants is inadvisable, their continued investigation as topical or mucosal adjuvants and antigens appears warranted on the basis of longstanding safety via oral, percutaneous, and other mucosal routes.

/pdf/transient-facial-nerve-paralysis-bell-s-palsy-following-1cwqdsa92j.pdf

Transient facial nerve paralysis (Bell's palsy) following intranasal delivery of a genetically detoxified mutant of Escherichia coli heat labile toxin.

https://www.gastrojournal.org/article/S0016-5085(99)70063-6/pdf

Oral immunization with urease and Escherichia coli heat-labile enterotoxin is safe and immunogenic in Helicobacter pylori-infected adults.

Low dose E. coli enterotoxin for urease-based oral immunization against H. pylori in healthy volunteers: Can it be safe and effective

Background and aims: Escherichia coli heat labile enterotoxin (LT) at doses of 5 μg or 10 μg has adjuvant activity for oral immunisation in humans infected with Helicobacter pylori, but causes severe diarrhoea. This study was undertaken to establish a safe and effective dose of LT, to confirm the safety of recombinant urease, and to compare the immunogenicity of orally compared with enterically delivered urease. Methods: 42 healthy adults without present or past H pylori infection were randomised to receive 60 mg recombinant H pylori urease in soluble or in encapsulated form, given with doses of LT ranging from 0 μg to 2.5 μg. Four oral doses were administered at day 1, 8, 29, and 57. Specific IgG, IgA, and antibody secreting cells were measured as well as total α4β7 integrin positive lymphocyte responses. Results: Enterically delivered urease was well tolerated and no serious adverse events occurred. Mild diarrhoea (one to four loose stools) occurred after the first immunisation in 50% (6 of 12) of the volunteers exposed to 2.5 μg LT (p=0.06; paired t test, compared with baseline) but not in volunteers exposed to lower LT doses. Immune responses occurred in five (p=0.048; Fisher’s exact test), one, two, and one of six subjects exposed to 2.5 μg, 0.5 μg, 0.1 μg, and no LT, respectively. Significant CD4 + , CD69 + , and CD45RO hi responses occurred over time among α4β7 hi lymphocytes in volunteers receiving 2.5 μg LT. Enterically delivered urease induced higher lymphocyte responses than soluble urease. Conclusions: The safety of H pylori urease is confirmed. Oral LT may conserve its adjuvant activity at low doses with minimal side effects.

https://gut.bmj.com/content/gutjnl/51/5/634.full.pdf

Safety and efficacy of low dose Escherichia coli enterotoxin adjuvant for urease based oral immunisation against Helicobacter pylori in healthy volunteers.

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Joseph Simon

Author Tools

Chat about Author

Papers

Oral immunization with urease and Escherichia coli heat-labile enterotoxin is safe and immunogenic in Helicobacter pylori-infected adults.

Low dose E. coli enterotoxin for urease-based oral immunization against H. pylori in healthy volunteers: Can it be safe and effective

Safety and efficacy of low dose Escherichia coli enterotoxin adjuvant for urease based oral immunisation against Helicobacter pylori in healthy volunteers.