Helicobacter pylori colonization in children with gastritis and peptic ulcer. I. The colonization rate and effects of colonization on mucin content and mucosal inflammation in the antrum

Inhibition of gastric mucin synthesis by Helicobacter pylori

BACKGROUND & AIMS

Mucins are high-molecular-weight glycoproteins that protect the gastric epithelium. Previous data suggested that gastric surface-type mucin is decreased in Helicobacter pylori-infected patients and restored after eradication of the infection. Our aim was to determine the effect of H. pylori on mucin synthesis in cultured gastric epithelial cells.

METHODS

Mucin synthesis was measured by labeling with [(3)H]glucosamine and size-exclusion chromatography. Expression of MUC5AC and MUC1 mucin protein antigens was quantitated by Western blot analysis.

RESULTS

Mucin synthesis was inhibited more than 80% when KATO III cells were incubated with H. pylori, with no effect on mucin secretion or degradation. Inhibition was rapid (4 hours), partially reversible, dependent on concentration of bacteria, and associated with the insoluble membrane fraction. H. pylori decreased levels of MUC5AC and MUC1 mucins. MUC1 inhibition was half-maximal by 4 hours and partially reversed by 24 hours, but the decrease in MUC5AC was less rapid and not reversible within 24 hours.

CONCLUSIONS

H. pylori inhibits total mucin synthesis in vitro and decreases the expression of MUC5AC and MUC1. A decrease in gastric mucin synthesis in vivo may disrupt the protective surface mucin layer.

Helicobacter pylori-dependent intragastric urea biodegradation in children: diagnostic and pathogenetic importance

The objective of the present work was to study the relationship between intragastric urea hydrolysis generated by Helicobacter pylori urease and acid-peptic disease in childhood. Intragastric urease activity was examined by urea and ammonia concentration measurement in gastric juice in 91 children with upper abdominal complaints. Helicobacter pylori infection was detected from 70 (76.9%) of 91 patients, including all of the 15 subjects with peptic ulcer disease. Helicobacter pylori-related gastritis in children was associated with a decrease of urea and an increase of ammonia in gastric juice (P < 0.001) in comparison with H. pylori-negative children. The gastritis score was correlated with the concentrations of urea and ammonia in the gastric juice of patients infected with H. pylori. There was a significant correlation between the histologically detected dissemination of organisms and gastric ammonia levels. Similar results were obtained concerning correlation between gastric juice ammonia and anti-H. pylori specific immunoglobulin G versus highly purified antigen of H. pylori containing urease. Present findings prove that H. pylori plays an essential role in the pathogenesis of gastritis and that ammonia is one of the main pathogenic factors of acid-peptic disease.

Helicobacter pylori colonization in children with gastritis and peptic ulcer. II. Ultrastructural change of the gastric mucosa

To evaluate the role of Helicobacter pylori in the pathogenesis of gastritis and peptic ulcer in children, ultrastructural changes of the gastric mucosa with H. pylori colonization were studied in two pediatric patients with duodenal ulcers. The study demonstrated that H. pylori: (i) colonized the mucous layer covering normal gastric epithelium; (ii) lay atop short, irregular microvilli and at the intercellular junctions of damaged cells; and (iii) adhered firmly by specific junction zone (firm connection) and loosely by filamentous appendages to the epithelial surfaces of cells which lacked evidence of a protective mucous layer. The ultrastructural changes, which become progressively worse from patterns (i) to (iii) mentioned above, suggest that these patterns represent distinct and successive stages of the infection. These findings, therefore, lend support to the notion that H. pylori infection is quite common and may relate to the pathogenesis of gastritis and peptic ulcer in children as well as in adults.