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Neutrophil-mediated injury to gastric mucosal surface cells
R Kozol1, A Kopatsis, S E Fligiel
1Department of Surgery, Veterans Administration, Allen Park, Michigan 48101.
Abstract:
Neutrophils (PMNs) have been implicated in the pathogenesis of gastritis. This study evaluates the magnitude and mode of PMN-mediated damage to gastric mucosal surface cells (GSC) in a system independent of vascular and neural factors. Rabbit GSC were freshly isolated and preloaded with 51Cr. GSC were then incubated for 1 hr or 4 hr with freshly isolated human PMNs at varying effector-to-target cell ratios. Injury to GSC was assessed as percent specific 51Cr released and by electron microscopy. We found minimal GSC injury using nonactivated PMNs. Incubation with PMNs activated with formylmethionyl-leucyl-phenylalanine (FMLP), however, resulted in significant GSC injury at the 20:1 PMN/GSC ratio, 33.2 +/- 1.8% 51Cr release (P < 0.001 compared to nonactivated PMNs). Electron microscopy revealed well-preserved gastric surface cells after exposure to nonstimulated PMNs. GSC exposed to activated PMNs (20:1 PMN/GSC ratio) were severely injured. Proteinase inhibitors and dimethylsulfoxide failed to diminish PMN-mediated GSC injury. Conversely, superoxide dismutase (SOD) inhibited GSC injury by more than 50% (P < 0.001). In addition, glutathione peroxidase inhibited injury by 84% (P < 0.001). These data suggest that neutrophil-mediated injury to gastric surface cells in vitro involves superoxide anion and hypochlorous acid and not neutral trypsinlike proteinases or hydroxyl radicals.
Insights
Activated neutrophils (PMNs) cause significant damage to gastric mucosal surface cells (GSC) via reactive oxygen species. This study reveals superoxide anion and hypochlorous acid as key mediators of this neutrophil-induced gastric injury.
Area of Science:
- Gastroenterology
- Immunology
- Cell Biology
Background:
- Neutrophils (PMNs) play a role in gastritis pathogenesis.
- Understanding PMN-induced gastric mucosal damage is crucial for treating inflammatory conditions.
Purpose of the Study:
- To evaluate the extent and mechanism of PMN-mediated damage to gastric surface cells (GSC) in an in vitro system.
- To identify the specific reactive species involved in this damage.
Main Methods:
- Isolated rabbit GSC were labeled with 51Cr and incubated with human PMNs at various ratios.
- Cell injury was quantified by 51Cr release and confirmed by electron microscopy.
- The role of reactive oxygen species and proteinases was assessed using specific inhibitors.
Main Results:
- Activated PMNs, but not nonactivated PMNs, caused significant GSC injury.
- Electron microscopy confirmed severe GSC damage upon exposure to activated PMNs.
- Superoxide dismutase (SOD) and glutathione peroxidase significantly inhibited PMN-mediated GSC injury, implicating superoxide anion and hypochlorous acid.
Conclusions:
- Neutrophil-mediated injury to GSC involves reactive oxygen species, specifically superoxide anion and hypochlorous acid.
- Neutral proteinases and hydroxyl radicals are not the primary mediators of this damage.
- These findings provide insight into the mechanisms of gastritis and potential therapeutic targets.