P075 Epithelial Toll-like receptor 3-dependent synthesis of complement factor B and local complement activation in inflammatory bowel disease

presence of myofibroblasts in all layers of the intestinal wall. Ulcerative colitis (UC) is classically considered to be a purely mucosal disease although rarely transmural complications such as strictures and stenosis develop. Fibrogenesis in UC has not been studied systematically yet and may be a neglected phenomenon. We therefore investigated whether there is a different fibrotic load in acute vs longstanding UC and whether the degree of fibrosis in UC correlates with the severity of inflammation. Methods: Colectomy specimens from all UC patients operated at the AMC between 2007 2012 were reviewed. Specimens from patients with recent onset refractory therapy UC (diagnosis 10 years) were selected. Patients operated for colon cancer without UC served as controls. On HE 29% vs 33% vs 54%, p = 0.009). Between acute and late UC there was no difference in collagen deposition, however between UC together and controls there was more collagen I expression in the mucosa, MM and muscularis externa (50% vs 10%, p = 0.02; 28% vs 10%, p = 0.048; 71% vs 20%, p = 0.003). In both early and long UC duration, we did not find a correlation between inflammation or collagen deposition or MM thickness. There was a negative correlation between inflammation and aSMA positivity in the submucosa (R = 0.51, p = 0.003) and MM (R = 0.37, p = 0.04). Conclusions: In our series of colectomy specimens, there is more collagen deposition in UC than in controls. No association between disease duration and increased collagen deposition could be found. Expression of aSMA however is lower in UC and correlates with inflammation. Fibrosis in UC does not appear to increase significantly over time.