title: Pancreatic stellate cell activation and MMP production in experimental pancreatic fibrosis.
abstract: BACKGROUND
  The early events in pancreatic fibrosis are poorly understood. We examined the production of collagen and matrix metalloproteinases as well as the activation of pancreatic stellate cells in a rodent model of pancreatic fibrosis.
  
  
  METHODS
  Pancreatitis was induced in rats by hyperstimulation with cerulein (50 microg/kg/day ip) and concurrent pancreatic duct obstruction (SHOP model) for 96 h (n = 48). Sham animals were injected with saline and underwent laparotomy and manipulation of the pancreas with no duct obstruction (n = 28). Rats were sacrificed daily for 18 days. Serial pancreatic sections were stained with H&E [histology], trichrome [collagen], and alpha smooth muscle actin (alpha-SMA) antibodies [activated stellate cells]. Total pancreatic matrix metalloproteinase (MMP)-2 and 9 were determined by gelatin zymography. MMP-1 production was examined using Western blotting.
  
  
  RESULTS
  There were occasional alpha-SMA-positive cells in the pancreatic parenchyma of normal and sham animals. Within 48 h of pancreatitis induction in SHOP animals, histologic evidence of pancreatic inflammation was present, and stellate cells (alpha-SMA-positive cells) appeared surrounding pancreatic acini. The appearance of these cells was followed by collagen deposition in the same area. MMP-1 and 2 proteins increased significantly during pancreatitis while MMP-9 did not. The pancreatic architecture returned to normal by 18 days after the induction of pancreatitis.
  
  
  CONCLUSIONS
  Acute pancreatic inflammation results in stellate cell activation and collagen deposition in the same area. Collagen is then resorbed at a time when MMP-1 and 2 peak. The fibrosis of acute pancreatic inflammation in this model completely resolves with restoration of normal architecture.
authors.affiliation: Division of Gastrointestinal and Endocrine Surgery, Department of Surgery, Northwestern University School of Medicine, Chicago, Illinois 60611, USA.
authors.forename: Tokuyasu
authors.initials: T
authors.lastname: Yokota
authors.forename: Woody
authors.initials: W
authors.lastname: Denham
authors.forename: Kenric
authors.initials: K
authors.lastname: Murayama
authors.forename: Carolyn
authors.initials: C
authors.lastname: Pelham
authors.forename: Raymond
authors.initials: R
authors.lastname: Joehl
authors.forename: Richard H
authors.initials: RH
authors.lastname: Bell
mesh_terms: D000199:Actins / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D002108:Ceruletide; D003094:Collagen / Q000032:analysis / Q000378:metabolism; D003250:Constriction; D004487:Edema; D005355:Fibrosis; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000096:biosynthesis; D020778:Matrix Metalloproteinase 2 / Q000096:biosynthesis; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D008666:Metalloendopeptidases / Q000096:biosynthesis*; D009130:Muscle, Smooth / Q000201:enzymology; D010179:Pancreas / Q000201:enzymology* / Q000473:pathology*; D010183:Pancreatic Ducts / Q000737:chemistry / Q000473:pathology; D010195:Pancreatitis / Q000201:enzymology* / Q000209:etiology / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
chemical_list: D000199:Actins; D002108:Ceruletide; D003094:Collagen; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D020781:Matrix Metalloproteinase 1