Cyclooxygenase expression during Helicobacter pylori infection in Mongolian gerbils.

We investigated the expression of cyclooxygenase-2 (COX-2) and COX-1 mRNAs during longterm Helicobacter pylori infection of the Mongolian gerbil (18 months) as well as the effect of eradication therapy and the cag pathogenicity island on COX mRNA expression. COX mRNA levels were determined by reverse transcription-polymerase chain reaction. Pyloric channel ulcers were noted in one of 10 gerbils (10%) at 3 months, 33% at 6 months, 50% at 9 months, 17% at 10 months, 40% at 12 months and 25% at 18 months after inoculation of parental strains. Nineteen of 21 gerbils had successful H. pylori eradication and showed significant reduction of inflammation and no ulcerations. There were no significant differences in COX-1 mRNA expression between the groups. COX-2 mRNA expression was significantly increased 1 and 3 months after inoculation and then decreased to basal levels. In control animals, COX-2 mRNA expression was significantly higher at 12 and 18 months compared to younger animals. cagE knockout mutants did not induce gastric inflammation and induced significantly lower COX-2 mRNA expression compared to parental strains. COX-2 mRNA was induced early in H. pylori infection and then declined. COX-2 mRNA expression was also induced with aging.