In situ expression of cagA and risk of gastroduodenal disease in Helicobacter pylori-infected children

Abstract

Background and aim: Gastroduodenal disease is more common among adults and children with cagA+ Helicobacter pylori infection, but disease severity varies among those infected with cagA+ strains. We examined whether cagA in situ expression can predict disease manifestations among H pylori-infected children.

Patients and methods: Fifty-one children were selected from 805 patients with abdominal symptoms who underwent esophagogastroduodenoscopy with gastric biopsies. Endoscopic and histologic gastritis were scored and H pylori colonization was quantified by Genta stain and in situ hybridization expression of 16S rRNA and cagA.

Results: Endoscopy was either normal (n = 14) or demonstrated nodularity (n = 18), gastric ulcer (n = 8) or duodenal ulcer (n = 11). H pylori was present in 7, 18, 6, and 10 children, respectively. Expression of 16S rRNA and cagA were significantly higher in children with ulcer compared with normal children. The fraction of H pylori bacteria expressing cagA in situ was higher in children with ulcer compared to those with endoscopic nodularity (P < 0.05).

Conclusions: Thus, cagA in situ expression is increased in H pylori-infected children with peptic ulcers and may play a role in the pathogenesis of peptic ulcer disease during childhood. Determination of in situ expression of cagA complements traditional isolation and in vitro testing of single-colony isolates.

Figure 1. H. pylori colonization in the antral gland of a child with duodenal ulcer in two successive 5-μm-thick serial sections (Original magnification ×1000). A is a picture of the first serial section and B, C, and D are three pictures of the second serial section with three different epi-fluorescence filters. Because the two serial sections are 5-μm apart, the H. pylori observed in A are not the same as the ones observed in B, C, and D, whereas B, C, and D represent different pictures of the same bacteria. Corresponding inserts show higher magnification of bacterial clusters (white arrows)

A. Genta stain of a gastric gland, first serial section; insert: H. pylori colony adherent to superficial epithelial cells. B, C, and D: FISH of second serial section illustrating 16S rRNA expression (red fluorescence) (B); cagA expression (green fluorescence) (C); and merge of pictures B and C showing co-localization of 16S rRNA and cagA (yellow fluorescence, multiband filter) (D).

Figure 2. Genta stained paraffin sections of a patient with duodenal ulcer (Original magnification ×1,000)

A. Illustration of the presence of dense colonies in the adherent mucus that covers the superficial mucosa of the antral lumen and foveola. B. Enlargement detail of an antral gland, illustrating the presence of H. pylori colonizing the mucus with characteristic denser colonies at an intercellular junction on the left of the picture; note that H. pylori density overlying each cell is higher near the tallest epithelial cells, when the mucus is being released, and that some H. pylori are adjacent to mucus secretory granules while other bacteria congregate at the apex of the cells.