Persistent oxidative stress in the corpus mucosa is evoked by long-term treatment of H. pylori-infected patients with proton pump inhibitors

Background/Aims: To examine the influence of long-term treatment of H. pylori-infected patients with proton pump inhibitors (PPI) on the toxic oxidant production in the stomach. Methodology: Eight H. pylori-positive patients with gastric ulcer were enrolled, and tissue samples were obtained endoscopically from the antrum and corpus. The tissue contents of neutrophil myeloperoxidase (MPO) and oxygen-derived free radicals were quantified by ELISA and chemiluminescence (ChL) assay. The H. pylori density in the tissue specimens was scored by immunohistochemistry and the mucosal infiltration by neutrophils and monocytes was scored by histopathology. The effects of PPI on these parameters were evaluated by oral administration of lansoprazole (LPZ) at the dose of 30mg od for 8 weeks, followed by 15mg for 24 weeks. Results: Eight-week treatment with LPZ significantly increased the corpus ChL by 400%, which remained unchanged at this level during the subsequent 24 weeks, but the antrum ChL decreased slightly following LPZ-treatment. No significant changes in the mucosal MPO activity or the histologically determined parameters of H. pylori density and neutrophil/monocyte infiltration were observed in either portion of the stomach. Conclusions: The mucosal oxidative stress level significantly increased in the corpus mucosa after long-term treatment with LPZ, which may be independent of inflammatory cell infiltration.