Gastric mucosal superoxide dismutases in Helicobacter pylori infection

Background-The mucosal pathology of Helicobacter pylori infection may in part be due to excessive production of reactive oxygen metabolites (ROMs) by phagocytes. The influence of H pylori infection on mucosal superoxide dismutases, some major scavenger enzymes of ROM was investigated. In humans superoxidase dismutase is present in at least two forms that is, mitochondrial manganese (Mn)-superoxide dismutase and cytoplasmic copper-zinc (CuZn)-superoxide dismutase. Methods-The amount and activity of both superoxide dismutases were measured, respectively by enzyme linked immunosorbent assay (ELISA) and spectrophotometrical enzyme activity assay, in gastric biopsy homogenates of patients with normal mucosa (n=39) and in patients with H pylori related gastritis (n=71). Infection and gastritis were confirmed by a combination of culture, serology, and histology. Results-The amount (p<0.001) and activity (p less than or equal to 0.05) of Mn-superoxide dismutase were increased by about twofold to threefold, whereas the amount and activity of CuZn-superoxide dismutase showed a slight decrease in gastric mucosa of patients with H pylori gastritis, in both antrum and corpus, compared with normal mucosa of patients without H pylori infection. Mn-superoxide dismutase concentrations in biopsy specimens of histologically normal corpus from patients with an inflamed antrum were significantly higher (p<0.01) than that of patients with a histologically normal antrum. Conclusion-H pylori infection has a differential effect on mitochondrial and cytoplasmic superoxide dismutase in the gastric mucosa, reflected by a pronounced increase in the cytokine inducible Mn-superoxide dismutase and a marginal decrease in the constitutive CuZn-superoxide dismutase.