Oleic acid-induced Pancreatitis alters expression of transforming growth factor-β1 and Extracellular matrix components in rats

Introduction and Aims Extracellular matrix (ECM) components participate in the process of tissue repair and development of fibrosis in the pancreas. We studied the production kinetics of ECM components and transforming growth factor (TGF)–β1 and identified their production sites in the pancreas following pancreatitis. Methodology Pancreatitis was induced in rats by a single intraductal infusion of oleic acid. Gene expression of TGF-βs and ECM components was studied by northern blotting. Pancreatic stellate cell activation was assessed by immunostaining for α-smooth muscle actin (αSMA) and desmin. Results Gene expression of TGF-βs and ECM components was increased in association with pancreatic fibrosis after 1–2 weeks and remained higher than the control levels for the ensuing 12 weeks. Both αSMA and desmin were strongly immunostained around small vessels and faintly stained in mesenchymal cells and tubular complexes at 1 week. The combination of staining for αSMA plus in situ hybridization for procollagen type III mRNA revealed that procollagen type III mRNA was expressed in both αSMA-positive and αSMA-negative cells in the mesenchyma. Conclusions Our findings demonstrate that expression of genes for both TGF-βs and ECM components was increased and that both αSMA-positive myofibroblasts and mesenchymal cells are the major sources of ECM components after pancreatitis.