Mo1689 Nicotine Significantly Affects the Expression of Vascular Endothelial Adhesion Molecules and Ameliorates DSS Induced Colitis

Abstract

Introduction Anti-adhesion molecule therapy is useful for inflammatory bowel diseases. Smoking has been reported to have a harmful effect on Crohn's disease, but it is still controversial in ulcerative colitis. Although effect of nicotine on adhesion molecules of cardiovascular system has been well recognized, it has not been studied in the intestine. We investigated effect of nicotine on murine colitis induced by dextran sodium sulfate (DSS) and compared expression of adhesion molecules in vitro in several conditions including preconditioning exposure. Involvement of nicotinic acetylcholine receptor (nAChR) was also examined. Method In in vivo study C57BL/6J mice were treated with 3% DSS and 0.1mg/ ml nicotine in drinking water for 7 days. Disease activity of colitis was assessed by DAI score. mRNA expressions of ICAM-1, VCAM-1 and MAdCAM-1 in colonic tissues were measured by qPCR. Microvascular endothelial cell line, bEnd3, was used for in vitro study. The cultured cells (2x105/ml) were treated with 5ng/ml TNF-α and 200μg/ml nicotine for 12 hours. mRNA expressions of ICAM-1, VCAM-1 and MAdCAM-1 in cells were measured by qPCR. Various concentrations of nicotine (0.01-1000μM) were tested. In pre-treatment protocol, cells were treated with nicotine for 3 days, and after 12 hours interval without nicotine, exposed to TNF-α and nicotine for 12 hours as treatment. In some experiments cells were cultured with TNF-α and nicotine under the presence of 0.01μM mecamylamine (Meca, nonselective nAChR antagonist) or 0.01μM methyllycaconitine (MLA, selective α7nAChR antagonist). Result In in vivo study, nicotine treatment decreased DAI score induced by DSS. Although nicotine alone did not affect expression of ICAM-1, VCAM-1 and MAdCAM-1 in control mice, addition of nicotine to DSS mice significantly attenuated the increased expression of VCAM-1 and MAdCAM-1 induced by DSS, and tended to inhibit ICAM-1. In in vitro study, expression of ICAM-1, VCAM-1 and MAdCAM-1 was increased by TNF-α. Increased expression of MAdCAM-1 was significantly attenuated by simultaneous administration of nicotine. In dose-response study, degree of ICAM-1 inhibition by nicotine was only observed at high doses, whereas that of MAdCAM-1 was observed in a low dose already. Interestingly pretreatment with nicotine before TNF-α decreased inhibitory effect of nicotine. These inhibitory effects tended to be attenuated by Meca or MLA, but not