Cerulein-induced pancreatic fibrosis is modulated by Smad7, the major negative regulator of transforming growth factor-β signaling

Chronic pancreatitis is the most common disease of the exocrine pancreas, characterized by progressive inflammation, acinar atrophy and fibrosis. Transforming growth factor-β signaling (TGFβ) is the most potent fibrogenic cytokine known, and its increased expression is a common denominator for fibrosis in chronic pancreatitis. Smad7 is induced by the TGFβ superfamily members as an intracellular inhibitory feedback antagonizing TGFβ signaling. To investigate the functional role of Smad7 in vivo, we induced chronic pancreatitis by repeated administration of cerulein in mice that are deficient in exon-I of Smad7. The response to chronic pancreatitis induction was significantly more severe in Smad7 mutant mice as indicated by a stronger accumulation of extracellular matrix, increased levels of inflammatory cells and an elevated number of mesenchymal cells/myofibroblasts in Smad7 mutant pancreata. Taken together, we conclude that lack of a functional Smad7 gene results in more severe damage in chronic pancreatitis. Therefore, Smad7 could be envisaged as a promising target in antifibrotic therapy of the pancreas.