Related Experiment Videos
[Studies on gastric mucosal cell injury induced by Helicobacter pylori]
1Third Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
Abstract:
The cause of gastric mucosal cell injury induced by Helicobacter pylori (H. pylori) was investigated in vitro using gastric mucosal cells derived from the stomach of male Japanese white rabbits. In order to evaluate the contribution of potent urease activity of H. pylori to gastric mucosal cell injury, supernatant of H. pylori bacterial pellet solubilized in a 1.0% solution of n-octyl-glucoside, the H. pylori extracts, was added to the rabbit gastric mucosal cell suspension. Cell injury was expressed by LDH release into the extracellular fluid of gastric mucosal cell suspension after 30 minutes incubation at 37 degrees C. Treatment of cells by H. pylori extracts (final concentration of 0.54 mg/ml) together with urea (final concentration at 50 mM) showed a high LDH release into the extracellular fluid suggesting definite gastric mucosal cell injury. Elevation of ammonia concentration and that of extracellular fluid pH were also observed by the treatment, whereas H. pylori extracts alone and urea solution alone did not. The ammonia concentration of extracellular fluid and LDH release were distinctly elevated in accord with increasing amount of H. pylori extracts under the existence of 50 mM urea. The degree of LDH release from gastric mucosal cell by H. pylori extracts under the existence of urea was similar to that induced by the administration of the same amount of exogenous ammonia. The addition of acetohydroxamic acid (AHA), a potent specific urease inhibitor, remarkably inhibited dose dependently the ammonia production, the elevation of pH of extracellular fluid and LDH release induced by H. pylori extracts under the presence of urea. These results suggest that the ammonia produced by potent urease activity of H. pylori under the presence of urea played an important role in the pathogenesis of gastric mucosal cell injury.
Insights
Helicobacter pylori urease activity, when combined with urea, causes gastric mucosal cell injury by producing ammonia. Acetohydroxamic acid, a urease inhibitor, significantly reduced this injury.
Area of Science:
- Gastroenterology
- Microbiology
- Cell Biology
Background:
- Helicobacter pylori (H. pylori) infection is a major cause of gastric diseases.
- The urease activity of H. pylori is implicated in its pathogenicity.
- Understanding the precise mechanisms of H. pylori-induced gastric injury is crucial.
Purpose of the Study:
- To investigate the role of H. pylori urease activity in gastric mucosal cell injury in vitro.
- To determine if ammonia produced by H. pylori contributes to cell damage.
Main Methods:
- Gastric mucosal cells from rabbits were exposed to H. pylori extracts and urea.
- Cell injury was quantified by lactate dehydrogenase (LDH) release.
- Ammonia concentration and pH of the extracellular fluid were measured.
- The effect of acetohydroxamic acid (AHA), a urease inhibitor, was assessed.
Main Results:
- H. pylori extracts combined with urea significantly increased LDH release, indicating cell injury.
- This treatment also elevated extracellular ammonia concentration and pH.
- Ammonia production and cell injury correlated with the amount of H. pylori extract.
- Exogenous ammonia mimicked the cell injury caused by H. pylori extracts plus urea.
- AHA dose-dependently inhibited ammonia production, pH increase, and LDH release.
Conclusions:
- The potent urease activity of H. pylori, leading to ammonia production in the presence of urea, plays a significant role in gastric mucosal cell injury.
- Ammonia is a key mediator in the pathogenesis of H. pylori-induced gastric damage.