COLONIC VASOACTIVE INTESTINAL POLYPEPTIDE (VIP) IN ULCERATIVE-COLITIS- A RADIOIMMUNOASSAY AND IMMUNOHISTOCHEMICAL STUDY

Background/Aims: In this study, we present radioimmunoassay data descr ibing the concentration of Vasoactive Intestinal Polypeptide (VIP) in both plasma and colonic biopsies, as well as immunostaining of VIPergi c innervation in mucosal biopsies of normal subjects and patients with ulcerative colitis (UC). Patients and Methods: Thirty three patients with UC and 17 healthy subjects were investigated. All UC patients suf fered from active disease. Fasting circulating levels of VIP in plasma as well as tissue concentrations were measured by radioimmunoassay. F or the immunohistochemistry, polyclonal antibody against VIP and the s treptavidin-biotin peroxidase complex technique were carried out. Resu lts: Overall plasma VIP concentrations in the UC patients were similar to those in the controls. Significantly decreased concentrations of V IP were found in UC of rectum compared to the normal tissue. However, both plasma VIP values and tissue concentrations were found to be sign ificantly lower in patients expressing minimal or mild active disease according to clinical activity index (AI) and histological activity in dex (HAI), but marked increase of plasma VIP was clear in UC patients with moderate or severe AI and HAI. There was a trend towards increase d tissue concentrations of VIP in the group of patients with moderate or severe AI and HAI. Our immunohistochemical analysis of VIP fibers a nd nerve cell bodies revealed consistently weaker VIP-immunoreactivity in the rectum in UC patients with minimal or mild HAI. Simultaneously , in the rectal biopsies from UC patients with moderate and severe dis ease, the fibers in the lamina propria and ganglion cells in the submu cous plexus were markedly increased in density and in degree of immuno staining. Very strong immunoreactivity was also found in inflammatory cells of the lamina propria as well as in the epithelial layer of the biopsies from UC patients with obvious disease. Conclusions: Our study shows clearly the heterogeneity in the response of VIP plasma level a s well as rectum concentration and distribution in UC patients at diff erent stages of the active disease. The possible role of VIP in the VI P in the colon suggests that further studies of the alterations of thi s gut peptide may be useful in the understanding of UC pathophysiology .