Temporal increase in the gastric colonization of Helicobacter pylori after healing of acetic acid-induced gastric ulcer in a miniature pig.

While the eradication of Helicobacter pylori has been reported to reduce the frequency of ulcer relapse, the preventative mechanism remains unknown. We investigated the changes in the level of gastric colonization 140 days after inducing gastric ulcer by acetic acid in the antral mucosa of a miniature pig infected with H. pylori. The gastric ulcer was induced endoscopically with 1 mL of 40% acetic acid 12 days after inoculation of H. pylori in a 3-month-old miniature pig. Gastric ulcer was healed by 30 days after ulcer induction and the levels of H. pylori in cardiac and antral mucosa increased gradually from 30 to 71 days. The peak bacterial counts in the cardia and antrum were 6.1 and 6.6 log10 cfu/g, respectively, or about 100-fold higher than the initial levels. The levels of H. pylori in cardiac and antral mucosa steadily decreased until reaching the initial levels at 127 days, while that in the fundic mucosa remained constant throughout the observation period. No ulcer recurrence was detected by endoscopy. These results suggested that the levels of H. pylori colonization increased temporally after healing of the acetic acid-induced gastric ulcer in the miniature pig.

Essential role of magnesium ion in water for colonization of Helicobacter pylori in 2-week-old miniature pigs.

This study was designed to determine whether magnesium ion in water would influence the colonization of Helicobacter pylori in 2-week-old miniature pigs. Groups A (2 pigs) and B (1 pig) were both fed a milk diet dissolved in drinking water, Group C (2 pigs) was fed a milk diet dissolved in deionized distilled water (DDW), and Group D (1 pig) was fed a milk diet dissolved in DDW supplemented with MgCl2. Groups B, C, and D were all challenged with H. pylori, and Group A was not. Necropsy was performed on the pigs on postinfection Day 5, and biopsy specimens were taken from 16 sites of the stomach. H. pylori were recovered from 11 of 16 sites in Group B, 1 of 32 sites in Group C, and 13 of 16 sites in Group D. On the other hand, the degree of lymphocyte infiltration increased in the order of Group A < Group B < Group C < Group D. These observations suggest that magnesium ion in drinking water is essential for the colonization of H. pylori in the pig stomach. Possible mechanisms for the lymphocyte infiltration are discussed.

Contribution of ferrous iron to maintenance of the gastric colonization of Helicobacter pylori in miniature pigs.

Our previous study showed that the colonization levels of Helicobacter pylori were higher in the stomachs of 5-day-old miniature pigs than in 2-week-old ones. As dietary factors can cause these differences, we compared two diets, i.e., Weanymilk and a similar formula with a higher concentration of Fe(II), Weanylobulin. The colonization levels in the fundic mucosa were significantly higher in 2-week-old pigs fed Weanylobulin than in those fed Weanymilk. Supplementing Weanylobulin with an iron chelator, deferoxamine mesylate, significantly lowered the bacteria counts in the gastric mucosa. Normal diets supplemented with Fe(II) in 2-month-old pigs caused significantly more sites of bacteria in the antrum compared with normal diets alone. In addition, ranitidine, an inhibitor of gastric acid secretion that reduces Fe(III) to Fe(II) in the stomach, decreased the bacteria counts in 10-month-old pigs. These results suggested that Fe(II) maintained the colonization levels of H. pylori in the stomach of the miniature pigs.