76 COMPARISON OF INDUCIBLE NITRIC OXIDE SYNTHASE (iNOS) mRNA IN INFLAMED ESOPHAGEAL AND COLONIC MUCOSA.

Abstract

Introduction: iNOS mRNA expression is induced in colonic mucosal biopsies of patients with active ulcerative colitis (UC). We queried if this finding was specific for UC or a reflection of active mucosal inflammation, and examined iNOS mRNA expression in both inflamed esophageal and colonic (UC) mucosa. We chose esophageal mucosa because of epithelial differences compared to colonic epithelium. Aim: To examine a potential cause-effect relationship between iNOS mRNA expression and mucosal inflammation. Methods: Esophageal mucosal biopsies were obtained from 6 children with active esophagitis (mean age 7.8 years) and 4 children with UC (mean age 11.1 years). RNA was isolated from these mucosal biopsies and RT-PCR performed (35 PCR cycles) using two primers that amplified a 372-bp conserved iNOS fragment. Results: iNOS mRNA was amplified in 3 of 4 colonic mucosal biopsies, and in none of the esophageal biopsies (0 of 6). Conclusions: Upregulation of iNOS mRNA accompanies UC in children but not esophagitis. Further studies are needed to determine the specificity for UC-mucosal involvement (vs Crohn, pseudomembranous or acute bacterial colitis), and the site specificity of this observation (i.e. colitis vs gastritis or enteritis). Identification of the cellular source of iNOS mRNA upregulation in UC mucosal biopsies using in situ hybridization techniques might further illuminate the pathophysiology.