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Virulence and colonization-associated properties of Helicobacter pylori isolated from children and adolescents
1Swedish Institute of Infectious Disease Control, and Department of Women and Child Health, St. Göran's Children's Hospital, Stockholm.
Abstract:
Helicobacter pylori isolates from 32 children and adolescents were characterized with respect to putative virulence and colonization-associated properties. Only 3 of the subjects had duodenal ulcer. All but 2 of the remaining 29 had various degrees of chronic gastric inflammation. No significant correlation between degree of inflammation and presence of the cag-pathogenicity island, cytotoxin production, vacA alleles associated with cytotoxin expression, and binding ability to the Lewis(b) (Le[b]) oligosaccharide was found. Only 4 isolates expressed the Le(b)-specific adhesin, of which 3 were also cag region-positive. This is in contrast to adults with gastritis or peptic ulcer disease (or both), in whom most of the H. pylori isolates bind Le(b). In an in situ binding assay H. pylori were less able to adhere to gastric surface mucous cells in biopsies taken from children compared with adults, suggesting a lower expression of the Le(b) oligosaccharide in the children.
Insights
Helicobacter pylori in children showed fewer virulence factors and less binding to Lewis b (Le[b]) oligosaccharides compared to adults. This suggests a lower Le(b) expression in children, potentially impacting H. pylori colonization and associated gastric inflammation.
Area of Science:
- Microbiology
- Pediatric Gastroenterology
- Infectious Diseases
Background:
- Helicobacter pylori is a common pathogen causing gastric inflammation and ulcers.
- Virulence factors and colonization properties of H. pylori can vary between host age groups.
- Lewis b (Le[b]) oligosaccharide binding is a key H. pylori colonization factor in adults.
Purpose of the Study:
- To characterize virulence and colonization factors of H. pylori isolates from children and adolescents.
- To investigate the correlation between H. pylori virulence factors and gastric inflammation in pediatric subjects.
- To compare H. pylori binding to gastric cells and Le(b) expression in children versus adults.
Main Methods:
- Characterization of H. pylori isolates for cag-pathogenicity island, cytotoxin production, vacA alleles, and Le(b) binding.
- Assessment of gastric inflammation in pediatric subjects.
- In situ binding assays using pediatric and adult gastric biopsies.
Main Results:
- Most pediatric H. pylori isolates were associated with chronic gastric inflammation, but not duodenal ulcers.
- No significant correlation was found between inflammation severity and H. pylori virulence factors (cag, cytotoxin, vacA, Le[b) binding).
- H. pylori isolates from children showed significantly less Le(b) binding and adherence to gastric cells compared to adult isolates, suggesting lower Le(b) expression in children.
Conclusions:
- H. pylori virulence factor expression and colonization mechanisms may differ in pediatric populations.
- Lower Lewis b (Le[b]) expression in children's gastric mucosa could explain reduced H. pylori adherence and binding.
- Further research is needed to understand the long-term implications of H. pylori infection in children with differing virulence factor profiles.