ALCOHOL METABOLISM IN HELICOBACTER PYLORI-INFECTED STOMACH

Studies in our laboratory have revealed that Helicobacter pylori exhib its significant cytosolic alcohol dehydrogenase activity and that the enzyme is fully active at ethanol concentrations prevailing in the sto mach during alcohol consumption or after alcohol is completely absorbe d from the stomach and is available through blood circulation only. Mo reover, even the low levels of endogenous ethanol found in the stomach can be oxidized to acetaldehyde by H. pylori alcohol dehydrogenase. T he metabolic significance of the enzyme remains as yet unresolved. Und er microaerobic conditions, however, the enzyme could be of importance in the energy metabolism of the organism. In the presence of excess e thanol, H. pylori alcohol dehydrogenase produces significant amounts o f acetaldehyde. Acetaldehyde is a toxic and reactive compound and coul d theoretically be a pathogenetic factor in H. pylori-associated gastr ic injury. Preliminary studies have indicated that acetaldehyde inhibi ts gastric mucosal regeneration and forms stable adducts with mucosal proteins. Both of these mechanisms could cause gastric injury. The rol e of H. pylori-related acetaldehyde formation in vivo, however, needs to be established in future studies. In antral human gastric mucosa, H ,pylori infection is associated with a significant decrease in alcohol dehydrogenase activity. Similarly, in specific pathogen-free mice wit h a prolonged infection, gastric alcohol dehydrogenase activity is dec reased; however, this Is not clearly reflected in the bioavailability of ethanol or the amount of its first pass metabolism.