p53 expression in the gastric mucosa before and after eradication of Helicobacter pylori.

Background. Accumulation of p53 has been recognized in the gastric mucosa infected with Helicobacter pylori. We investigated the prevalence of p53-positive cells in the gastric mucosa before and one month after eradication of H. pylori and the relationship between p53 positivity and inflammation and cell proliferation. Methods. The subjects included 24 H. pylori-positive patients. They achieved eradication one month after anti-H. pylori therapy. Biopsies were taken from the greater curvatures of the antrum and middle body. H. pylori status was assessed using culture and tissue section (Giemsa stain). Serial sections were used for examination of gastritis (hematoxylin and eosin stain) and for immunostaining of p53, Ki-67 and myeloperoxidase (MPO). p53 index and Ki-67 labeling index (LI) were calculated by counting p53-positive and Ki-67-positive cells in the entire gastric pits longitudinally sectioned and expressing them as a percentage of the total cells in a gastric pit. In the neck regions with and without p53-positive cells, polymorphonuclear leukocytes (PMNs) were counted in the corresponding area (/50 × 50 µm2) of the sections stained both with p53 and MPO. Results. p53-positive cells decreased significantly after eradication of H. pylori. Before eradication, the number of PMNs was significantly higher in the neck regions with p53-positive cells than in those without. Conclusions. In the gastric mucosa infected with H. pylori, p53-positive cells were found in the neck region infiltrated with PMNs. p53 expression decreased significantly one month after eradication of H. pylori.