Expression of cyclooxygenase-2 and nitrotyrosine in human gastric mucose before and after Helicobacter pylori eradication

To determine whether cure of Helicobacter pylori infection influences the e xpression of COX-2 and nitrotyrosine in the distal stomach of humans, biops y specimens were examined immunohistochemically. H. pylori infection was de termined using a rapid urease test, culture and histology. Positive stainin g of COX-2/nitrotyrosine in the epithelium was expressed as the percentage of stained cells to the total epithelial cells. There was a significant increase in COX-2/nitrotyrosine staining in H. pylo ri-positive subjects compared with H. pylori-negative subjects. Cure of the infection resulted in a sig nificant decrease in both COX-2/nitrotyrosine staining in all patients (52.1 +/- 12.1 % vs 15.4 +/- 7.2 %, P < 0.001; and 57.3 +/- 13.6 % vs 36.1 +/- 18.0 %, P < 0.01, respectively). However, immu noreactivity of COX-2/nitrotyrosine was observed in all cases with intestin al metaplasia even after the cure of H. pylori infection. Thus, cure of H. pylori infection may decrease the risk of gastric carcinog enesis due to COX-2 and NO-related compounds in gastric mucosa but not in t hose patients with intestinal metaplasia. (C) 2000 Harcourt Publishers Ltd.