Helicobacter pylori in vivo causes structural changes in the adherent gastric mucus layer but barrier thickness is not compromised.

BACKGROUND It has been proposed that a pathogenic effect of Helicobacter pylori is a weakening of the protective mucus barrier; however, this remains controversial. AIMS To clarify the effects of H pylori infection on the mucus gel barrier in vivo. METHODS Mucus gel polymeric structure and the thickness of the adherent mucus barrier were measured in endoscopic biopsy samples in subjects with and without H pylori infection. RESULTS There was a significant 18% reduction in the proportion of polymeric gel forming mucin in the adherent mucus layer in H pylori positive compared with negative subjects. There was no change in the adherent mucus thickness between H pylori positive and negative subjects without gastric atrophy (mean (SD): 104 (26) micron, 106 (30) micron, respectively). There was however a significant reduction in mucus thickness in those H pylori positive subjects with underlying gastric atrophy (84 (13) micron, p=0.03) compared with those without atrophy. CONCLUSIONS A partial breakdown in gel forming structure of the gastric mucus barrier does occur in H pylori infection per se but this is insufficient to cause a collapse of the mucus barrier.