THE DETECTION AND LOCALIZATION OF INDUCIBLE NITRIC-OXIDE SYNTHASE PRODUCTION IN THE SMALL-INTESTINE OF PATIENTS WITH CELIAC-DISEASE

Objectives To investigate whether there are increased numbers of induc ible nitric oxide synthase (iNOS) containing cells in the small intest ine of patients with coeliac disease and the localization of nitric ox ide synthase production.Design Small intestinal biopsy specimens from patients with coeliac disease (11 untreated, 10 treated) and nine dise ase controls were studied. Methods Histochemical staining of sections for NADPH-diaphorase activity was performed, which gives an indication of NOS activity. iNOS protein was detected with immunohistochemistry and iNOS mRNA expression was detected using in situ hybridization with an oligonucleotide probe cocktail for iNOS. Cell phenotype was detect ed using monoclonal antibodies to CD3 (T-lymphocytes) and CD45 (total inflammatory cell infiltrate). Results there was significantly greater NADPH diaphorase staining in the lamina propria of patients with untr eated coeliac disease (P < 0.005). The same pattern was found for immu nohistochemical and in situ hybridization methods of staining for iNOS in each of the patient groups (P < 0.005) but no epithelial staining was seen with any method. The pattern of iNOS staining in the lamina p ropria appeared in a similar distribution to that of the inflammatory cell infiltrate. At least 80% of the significantly increased total inf lammatory cell infiltrate (CD45) in the lamina propria of patients wit h untreated coeliac disease was lymphocytic (CD3) whilst the iNOS stai ning cells made up less than 15% of the total inflammatory cell infilt rate. Conclusions There is a significant increase in the number of NOS staining cells of the inducible isoform in the lamina propria of pati ents with untreated coeliac disease. The lamina propria and not the ep ithelium is the site of iNOS production in coeliac disease. It appears that inflammatory cells other than T-lymphocytes are likely to be the cellular sources of iNOS production within the lamina propria. This i s the first study to demonstrate increased numbers of iNOS producing c ells in the small intestine of patients with untreated coeliac disease and suggests a role for nitric oxide in the pathogenesis of the histo logical changes seen in coeliac disease although it may be a non-speci fic inflammatory response to immune activation by gluten in susceptibl e individuals. (C) 1998 Lippincott Williams & Wilkins.