Mucosal barrier in ulcerative colitis and Crohn's disease

Background. The mucus layer in the gastrointestinal tract plays important role in host innate defense, regulation of secretion, and absorption processes, maintaining colonization resistance, which composes the integrity of protective mucus barrier in the large intestine. Investigations of mucin expression in the colon mucosa can improve the understanding of protective function of mucosal barrier in ulcerative colitis (UC) and Crohn's disease (CD). Materials and Methods. 77 patients with UC and CD were examined. Histological analysis of colon mucosa was done by standard method (haematoxylin-eosin, alcian blue at pH 1.0 and 2.5 to determine sulfated and nonsulfated glycosaminoglycans and glycoproteins, and goblet cells). To characterize the mucus production the PAS-reaction was performed. Immunohistochemistry was performed using monoclonal mouse antibodies raised against MUC2, MUC3, MUC4, and TFF3 (USBiological, USA). Results. The moderate expression of MUC2 and MUC3 (50.0% and 32.1%, P = 0.03) and high expression of MUC4 and TFF3 in the colon mucosa were observed in all patients with CD. The intensive labeling of MUC4 and TFF3 occurred more often (42.9% and 57.1%, P = 0.03) in patients with CD. The level of expression of secretory MUC2 and transmembrane MUC3 and MUC4 in all patients with UC was low, up to its complete absence (59.2% and 53.1% cases, P = 0.05). TFF3 expression had high and medium staining intensity in patients with UC. Conclusions. Different types of mucins synthesis, secretion, and expression were found in patients with UC and CD. The expression of mucin MUC2, MUC3, MUC4, and TFF3 correlated with the activity of disease and the extent of the inflammatory process in the large intestine. The most pronounced alteration of mucins expression was observed in patients with severe UC and CD.