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Mutagenicity from neutrophils after challenge with Helicobacter pylori and bile
M Hagman1, P Loogna, D Danielsson
1Department of Clinical Microbiology & Immunology, Orebro Medical Centre Hospital, Sweden.
Objective:
To study some mechanisms involved in Helicobacter pylori (H. pylori)-induced gastric carcinogenesis.
Design:
In vitro study.
Setting:
Medical centre hospital, Sweden.
Interventions:
Mutagenicity in Ames' test of neutrophils challenged for 2 hours or more by two different strains of H. pylori. One strain designated NCTC 11637 by the National College of Type Cultures activated neutrophils to an oxidative burst and producing vacuolating cytotoxin, the other strain C-7050 lacked these abilities. Mutagenicity was also studied with sterile human gall bladder bile alone added to neutrophils or in combination with both neutrophils and H. pylori.
Results:
There was no increase in the number of revertants with the crude suspension or the supernatant of neutrophils challenged for 1 hour or less with H. pylori, bile, or the combination of both. However, in 5 out of 19 experiments there was significant mutagenicity after challenge of neutrophils for 2 hours or more with either strain of H. pylori, bile, or the combination of the two. The strongest mutagenicity was obtained after challenge over night (18 hours) with the combination of H. pylori and bile.
Conclusion:
Mutagenicity occurs when neutrophils are challenged with H. pylori and bile. Factors other than reactive oxygen metabolites seem to be responsible.
Insights
Helicobacter pylori and bile can cause mutagenicity in neutrophils, particularly after prolonged exposure. This suggests factors beyond reactive oxygen metabolites contribute to gastric carcinogenesis.
Area of Science:
- Gastroenterology
- Microbiology
- Carcinogenesis research
Background:
- Helicobacter pylori (H. pylori) infection is a major risk factor for gastric cancer.
- The mechanisms underlying H. pylori-induced gastric carcinogenesis are not fully understood.
- Neutrophils play a role in the inflammatory response within the gastric mucosa.
Purpose of the Study:
- To investigate the mutagenic potential of neutrophils challenged with H. pylori and human bile.
- To explore mechanisms involved in H. pylori-associated gastric carcinogenesis.
Main Methods:
- In vitro study using the Ames test to assess mutagenicity.
- Neutrophils were challenged with two different strains of H. pylori (one cytotoxic, one not) and sterile human gallbladder bile.
- Challenges involved varying durations, including prolonged exposure (overnight).
Main Results:
- No significant mutagenicity was observed with short-term challenges (≤1 hour) of neutrophils with H. pylori or bile.
- Significant mutagenicity occurred in 5 out of 19 experiments after prolonged neutrophil challenge (≥2 hours) with H. pylori, bile, or their combination.
- The highest mutagenicity was detected after overnight challenge with the combination of H. pylori and bile.
Conclusions:
- Neutrophil challenge with H. pylori and bile can induce mutagenicity.
- The findings suggest that factors other than reactive oxygen metabolites are involved in H. pylori-induced mutagenicity and potentially gastric carcinogenesis.