ENHANCED EXPRESSION OF INDUCIBLE NITRIC-OXIDE SYNTHASE IN CHRONIC GASTRITIS WITH INTESTINAL METAPLASIA

Nitric oxide produced by inducible nitric oxide synthase (iNOS) has be en claimed to be involved in gastritis; however, its characteristics a re largely unknown. We assessed (1) iNOS expression in the human gastr ic mucose in chronic gastritis and (2) the cytokines associated with i NOS expression. Gastric biopsy specimens were obtained from patients w ith chronic gastritis. Total RNA was isolated and reverse transcriptio n-polymerase chain reaction (PCR) was performed semiquantitatively usi ng specific primer sets for iNOS, interleukin (IL)-1 beta, IL-8, IL-6, interferon-gamma, tumor necrosis factor-alpha (TNF-alpha), TNF recept ors, IL-6 receptors, and sucrase, respectively. Helicobacter pylori in fection was examined by the PCR assay. Reverse transcription-PCR analy sis showed that expression of iNOS was detected in 10 of 23 samples. E xpression of iNOS mRNA was closely correlated with expression of TNF-a lpha and was observed frequently in subjects with intestinal metaplasi a. The Helicobacter pylori gene was detected by PCR assay in all iNOS- positive cases. These results indicate that iNOS is predominantly expr essed in the gastric mucosa with intestinal metaplasia and H. pylori i nfection. TNF-alpha is thought to be an important cytokine associated with iNOS expression.