title: The loss of αSNAP downregulates the expression of occludin in the intestinal epithelial cell of acute pancreatitis model.
abstract: 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 αSNAP, as a novel membrane protein, is ubiquitously expressed in intestinal epithelial cells. This study aimed to investigate the role of αSNAP in acute pancreatitis and the relationship between occludin and αSNAP.
  
  
  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 αSNAP were assessed. Cultured epithelial IEC-6 cells were further infected with lentiviral αSNAP 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-α 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 αSNAP and occludin in the intestinal epithelial cells. After the lentiviral transduction of αSNAP shRNA, apoptosis in IEC-6 cells was drastically increased, whereas the expression of occludin was decreased significantly.
  
  
  CONCLUSIONS
  The downregulated expression of αSNAP 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.
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Daixing
authors.initials: D
authors.lastname: Chen
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Lili
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yan
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: You
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. Electronic address: oliveofcq@hotmail.com.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Department of Gastroenterology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. Electronic address: lingxianlong@yeah.net.
authors.forename: Xianlong
authors.initials: X
authors.lastname: Ling
mesh_terms: D000208:Acute Disease; D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D015153:Blotting, Western; D002460:Cell Line; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D005455:Fluorescent Antibody Technique; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D008297:Male; D062793:Occludin / Q000378:metabolism*; D010195:Pancreatitis / Q000378:metabolism* / Q000473:pathology; D010539:Permeability; D051381:Rats; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D062793:Occludin; D052067:Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
keywords: Acute pancreatitis; Intestinal barrier; Occludin; Rat; Tight junction; αSNAP