Production of reactive oxygen species by gastric cells in association with Helicobacter pylori.

Reactive oxygen species (ROS) and Helicobacter pylori have been identified as pathogenic factors in several gastrointestinal disorders. Since little information is available regarding the mechanistic pathways of H. pylori-induced gastric injury, the potential role of ROS was investigated. The induction of ROS in gastric cells (GC) by H. pylori was assessed using chemiluminescence, cytochrome c reduction, nitrobluetetrazolium (NBT) reduction and lactate dehydrogenase (LDH) leakage. The dose-dependent protective abilities of selected ROS scavengers on LDH leakage were determined. Following incubation of GC with three strains of H. pylori (1:1), approximately 5.7-8.0 and 3.8-4.3 fold increases were observed in cytochrome c and NBT reduction, respectively, demonstrating production of ROS. Enhanced chemiluminescence responses of 2.1- and 3.7-fold were observed following incubation of GC with H. pylori (ATCC 43504) at ratios of 1:1 and 1:10, respectively. Approximately 2.2- and 3.5-fold increases in LDH leakage were observed at GC:H. pylori (ATCC 43504) ratios of 1:1 and 1:10, respectively. Substantial inhibition of LDH leakage from GC in the presence of H. pylori was observed following co-incubations with selected ROS scavengers with cimetidine serving as the best chemoprotectant. The antioxidants and H2-receptor antagonists had no effect on growth of H. pylori cells. This study demonstrates that H. pylori induces enhanced production of ROS in GC, and enhances membrane damage.