Name: h. pylori and stomach ulcers
Uploaded: 2026-03-12T13:35:58.000Z
Duration: 1 min 27 s
Channel: JoVE

Peptic ulcers are erosions in the stomach or duodenal lining.Most of these ulcers are caused by infections of Helicobacter pylori, a Gram-negative, spiral-shaped bacterium.H. pylori survives the acidic environment of the stomach by producing urease, an enzyme that converts urea in the gastric juices into ammonia.The ammonia neutralizes the acidity around the bacteria.The bacteria penetrate the protective mucus layer, attach to epithelial cells, and multiply.The bacteria also produce virulence factors such as VacA and CagA.VacA induces apoptosis in epithelial cells, while CagA triggers the release of pro-inflammatory cytokines, attracting neutrophils to the site of infection.Neutrophils fail to clear bacteria that persist beneath the mucus layer, leading to chronic inflammation.This inflammation compromises the mucus barrier, exposing epithelial cells to highly acidic gastric juice.Acid damages these cells and the underlying tissue, creating ulcers.As the ulcer deepens, damage may extend into blood vessels, causing bleeding and further complications.

peptic ulcer

Peptic Ulcer

Peptic ulcers are erosive lesions of the gastric or duodenal lining, most commonly caused by Helicobacter pylori infection. This Gram-negative, helical bacterium has adapted to survive the stomach&#8217;s acidic environment by producing urease, which converts urea into ammonia and carbon dioxide. The ammonia neutralizes gastric acid in the bacterium&#8217;s immediate environment, allowing colonization of the gastric mucosa. H. pylori attaches to mucus-secreting epithelial cells, penetrates the mucus barrier, and initiates a cascade of pathogenic processes.Virulence Factors and Mucosal DamageThe pathogenicity of H. pylori is mediated by a set of virulence factors. Urease is central to acid neutralization, while adhesins facilitate binding to epithelial surfaces. Two major exotoxins&#8212;VacA and CagA&#8212;amplify tissue damage. VacA induces apoptosis in epithelial cells, while CagA activates pro-inflammatory signaling pathways, notably through cytokine release and recruitment of neutrophils. These responses lead to chronic inflammation, erosion of the protective mucus layer, reduction of bicarbonate secretion and direct cellular injury. Over time, the exposure of epithelial surfaces to gastric acid and pepsin results in the formation of ulcers, which may penetrate deeper tissue layers and damage blood vessels, leading to gastrointestinal bleeding.Transmission and EpidemiologyH. pylori is typically acquired during childhood, likely through oral transmission. It is rarely associated with common vectors such as food or animals, suggesting that person-to-person spread, especially within families, is the primary mode of infection. Prevalence is significantly higher in developing countries, correlating with poor sanitation and crowded living conditions. Chronic H. pylori infections are also associated with increased risk of gastric malignancies, including MALT (Mucosa-Associated Lymphoid Tissue) lymphomas and gastric carcinoma. These outcomes stem from persistent inflammation and the resulting disruption of mucosal immunity and cellular regulation.Clinical Presentation and ComplicationsUlcers often present with abdominal pain and may lead to serious complications such as gastrointestinal bleeding, perforation, and obstruction. Vomiting of coffee-ground material, weight loss, and black, tarry stools may indicate advanced disease. Untreated ulcers, particularly those complicated by vascular involvement or mucosal perforation, represent medical emergencies requiring prompt intervention.

Peptic ulcers are erosive lesions of the gastric or duodenal lining, most commonly caused by Helicobacter pylori infection. This Gram-negative, helical ...

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h. pylori and stomach ulcers

H. pylori and stomach ulcers are linked through damage to the stomach and duodenal lining. A peptic ulcer is an erosive lesion in the gastric or duodenal wall. The most common cause is Helicobacter pylori infection, a Gram-negative, helical bacterium that can live in the stomach’s acidic environment.

H. pylori survives acid by making urease, an enzyme that breaks urea into ammonia and carbon dioxide. The ammonia helps neutralize gastric acid around the bacterium, which supports colonization of the gastric mucosa. The bacterium also attaches to mucus-secreting epithelial cells and moves through the mucus barrier.

Several virulence factors drive tissue injury. Adhesins help H. pylori bind to epithelial surfaces. VacA, one major exotoxin, can trigger apoptosis, or programmed cell death, in epithelial cells. CagA, the other major exotoxin, activates pro-inflammatory signaling and leads to cytokine release and neutrophil recruitment.

These changes weaken the stomach’s protective lining. Chronic inflammation erodes the mucus layer, reduces bicarbonate secretion, and causes direct cell injury. As acid and pepsin continue to contact exposed tissue, ulcers can form and deepen into lower layers. If blood vessels are damaged, gastrointestinal bleeding can occur.

H. pylori infection is usually acquired during childhood, likely through oral transmission. It is rarely linked to food or animals, so spread from person to person, especially within families, is thought to be the main route. Infection is more common in developing countries, where poor sanitation and crowded living conditions increase exposure.

Long-term infection can also raise the risk of gastric malignancies. These include MALT, or mucosa-associated lymphoid tissue, lymphoma and gastric carcinoma. Persistent inflammation appears to disrupt mucosal immunity and normal cell regulation, which contributes to these outcomes. Ulcers may also cause abdominal pain, perforation, obstruction, vomiting of coffee-ground material, weight loss, and black, tarry stools. Severe ulcers, especially those with vessel damage or perforation, are medical emergencies.

H. pylori and Stomach Ulcers

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key terms and concepts

Learn how H. pylori survives stomach acid, damages the gastric lining, and can lead to ulcers, bleeding, and long-term stomach disease.

H. pylori and Stomach Ulcers | JoVE K12

JoVE Core Microbiology provides an engaging introduction to the microbial world and its influence on health, industry, and the environment. This comprehensive collection covers key concepts such as microbial structure, metabolism, genetics, and ecology. It introduces essential laboratory techniques and microscopy methods through visually engaging animations. Corresponding scientist-in-action videos bridge classroom concepts with real-world research and applications.

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H. pylori and Stomach Ulcers

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