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Cytotoxic isolates of Helicobacter pylori from peptic ulcer diseases decrease K+-dependent ATPase activity in HeLa
Awasthi Shanjana1, Ayyagari Archana
1Department of Microbiology, Sanjay Gandhi P,G, Institute of Medical Sciences, Lucknow, UP, India. awasthis@uthscsa.edu
Background:
Helicobacter pylori is a Gram negative bacterium that plays a central role in the etiology of chronic gastritis and peptic ulcer diseases. However, not all H. pylori positive cases develop advanced disease. This discriminatory behavior has been attributed to the difference in virulence of the bacteria. Among all virulence factors, cytotoxin released by H. pylori is the most important factor. In this work, we studied variation in H. pylori isolates from Indian dyspeptic patients on the basis of cytotoxin production and associated changes in K+-dependent ATPase (one of its targets) enzyme activity in HeLa cells.
Methods:
The patients were retrospectively grouped on the basis of endoscopic and histopathological observation as having gastritis or peptic ulcer. The HeLa cells were incubated with the broth culture filtrates (BCFs) of H. pylori isolates from patients of both groups and observed for the cytopathic effects: morphological changes and viability. In addition, the K+-dependent ATPase activity was measured in HeLa cells extracts.
Results:
The cytotoxin production was observed in 3/7 (gastritis) and 4/4 (peptic ulcer) H. pylori isolates. The BCFs of cytotoxin producing H. pylori strains reduced the ATPase activity of HeLa cells to 40% of that measured with non-cytotoxin producing H. pylori strains (1.33 micromole Pi/mg protein and 3.36 micromole Pi/mg protein, respectively, p < 0.05). The decreased activity of ATPase enzyme or the release of cytotoxin also correlated with the increased pathogenicity indices of the patients.
Conclusions:
Our results suggest that the isolation of cytotoxic H. pylori is more common in severe form of acid peptic diseases (peptic ulcer) than in gastritis patients from India. Also the cytotoxin released by H. pylori impairs the ion-transporting ATPase and is a measure of cytotoxicity.
Insights
Cytotoxic Helicobacter pylori strains are more prevalent in Indian peptic ulcer patients than gastritis patients. This cytotoxin impairs ion-transporting ATPase activity, indicating its role in disease severity.
Area of Science:
- Microbiology
- Gastroenterology
- Cell Biology
Background:
- Helicobacter pylori is a Gram-negative bacterium linked to chronic gastritis and peptic ulcers.
- Disease severity in H. pylori infections varies, potentially due to bacterial virulence factors.
- Cytotoxin production by H. pylori is a key virulence factor influencing disease outcomes.
Purpose of the Study:
- To investigate variations in H. pylori isolates from Indian dyspeptic patients based on cytotoxin production.
- To assess the impact of H. pylori cytotoxin on K+-dependent ATPase enzyme activity in HeLa cells.
- To correlate cytotoxin production with disease severity (gastritis vs. peptic ulcer).
Main Methods:
- Patients were classified as having gastritis or peptic ulcer based on endoscopic and histopathological findings.
- HeLa cells were exposed to broth culture filtrates (BCFs) of H. pylori isolates.
- Cytopathic effects (morphological changes, viability) and K+-dependent ATPase activity in HeLa cells were measured.
Main Results:
- Cytotoxin production was detected in a higher proportion of H. pylori isolates from peptic ulcer patients (4/4) compared to gastritis patients (3/7).
- BCFs from cytotoxic H. pylori strains significantly reduced HeLa cell K+-dependent ATPase activity by approximately 60% compared to non-cytotoxic strains.
- Reduced ATPase activity and cytotoxin release correlated with increased patient pathogenicity indices.
Conclusions:
- Cytotoxic H. pylori strains are more frequently isolated from Indian patients with severe acid peptic diseases like peptic ulcers than from gastritis patients.
- H. pylori cytotoxin impairs ion-transporting ATPase activity, serving as a marker of bacterial cytotoxicity.
- These findings highlight the role of cytotoxin in the pathogenesis of severe H. pylori-associated gastrointestinal diseases.
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