The loss of αSNAP downregulates the expression of occludin in the intestinal epithelial cell of acute pancreatitis model

Background and objective: Intestinal barrier damage is an important event during the occurrence and progression of severe acute pancreatitis. The expression of occludin, one of the main components of the intestinal barrier proteins, is regulated by various factors related to intestinal barrier formation and the remodeling process. The alpha SNAP, as a novel membrane protein, is ubiquitously expressed in intestinal epithelial cells. This study aimed to investigate the role of alpha SNAP in acute pancreatitis and the relationship between occludin and alpha SNAP. Methods: Mild and severe acute pancreatitis models were established by retrograde injections of 0.5% and 3.8% sodium taurocholate solutions, respectively, into rat pancreaticobiliary ducts. The animals were killed at 1, 2, and 3 days after the injection, and the pathological changes of the pancreas and intestinal mucosa, the changes in intestinal permeability, and the protein expression of occludin and alpha SNAP were assessed. Cultured epithelial IEC-6 cells were further infected with lentiviral alpha SNAP shRNA, cell apoptosis was determined with flow cytometry (FCM), and any changes in occludin expression were detected by Western blotting and immunofluorescent staining. Results: This pathologic study of a rat acute pancreatitis model indicated pancreatic tissue necrosis and inflammatory cell infiltration; the intestinal villi in the severe acute pancreatitis (SAP) group demonstrated edema, lodging, atrophy, and intestinal epithelial cell necrosis, and shedding. The intestinal permeability in rats with pancreatitis increased significantly. The SAP group showed significantly increased levels of serum TNF-alpha and endotoxins. The results of immunofluorescent staining and Western blotting revealed that compared with the SO (sham operation) and MAP (mild acute pancreatitis) groups, the SAP group displayed significantly downregulated protein expressions Of alpha SNAP and occludin in the intestinal epithelial cells. After the lentiviral transduction of alpha SNAP shRNA, apoptosis in IEC-6 cells was drastically increased, whereas the expression of occludin was decreased significantly. Conclusion: The downregulated expression of aSNAP in intestinal epithelial cells leads to reduced occludin expression and enhanced apoptosis of intestinal epithelial cells. Hence, the permeability of the intestinal barrier may be increased in a severe acute pancreatitis model. Copyright (C) 2014, IAP and EPC. Published by Elsevier India, a division of Reed Elsevier India Pvt. Ltd. All rights reserved.