[Digestion of human gastric mucous by extracellular Helicobacter pylori enzyme]

Helicobacter pylori (Hp) is a causative pathogen of chronic gastritis and strongly associated with recurrence of duodenal ulcers, but the mechanism is not known. We studied the possible digestion of gastric mucus by Hp extracellular enzyme in human stomach. Hp was isolated from biopsy specimens taken from peptic ulcer patients or normal individuals and its extracellular enzyme was collected. Incubation of human gastric mucosa with Hp extracellular enzyme resulted in a significant decrease of PAS-positive staining, indicating digestion of gastric mucus. Analysis of protein profile of extracellular enzyme revealed no difference among Hp strains. Subsequent zymography showed 2 bands; 97 K and 20 K, indicating existence glycosyl-hydrase. These results suggest that Hp weakens gastric mucosal defense by digesting carbohydrates in the protective mucus layer.