The long-term use of
proton pump inhibitors (PPIs) exacerbates corpus
atrophic gastritis in patients with Helicobacter pylori (H. pylori)
infection. To identify a potential mechanism for this change, we discuss interactions between pH,
bile acids, and H. pylori.
Duodenogastric reflux, which includes bile, occurs in healthy individuals, and
bile reflux is increased in patients with
gastroesophageal reflux disease (
GERD). Diluted human plasma and
bile acids have been found to be significant
chemoattractants and chemorepellents, respectively, for the bacillus H. pylori. Although only
taurine conjugates, with a pKa of 1.8-1.9, are soluble in an acidic environment,
glycine conjugates, with a pKa of 4.3-5.2, as well as
taurine-conjugated
bile acids are soluble in the presence of PPI
therapy. Thus, the soluble
bile acid concentrations in the gastric contents of patients with
GERD after continuous PPI
therapy are considerably higher than that in those with intact
acid production. In the distal stomach, the high concentration of soluble
bile acids is likely to act as a bactericide or chemorepellent for H. pylori. In contrast, the mucous layer in the proximal stomach has an optimal bile concentration that forms chemotactic gradients with plasma components required to direct H. pylori to the epithelial surface. H. pylori may then colonize in the stomach body rather than in the pyloric antrum, which may explain the occurrence of corpus-predominant
gastritis after PPI
therapy in H. pylori-positive patients with
GERD.