Inhibitory effects of interferon-γ on activation of rat pancreatic stellate cells are mediated by STAT1 and involve down-regulation of CTGF expression

Pancreatic stellate cells (PSCs) are the main source of extracellular matrix proteins in pancreatic fibrosis, a pathological feature of chronic pancreatitis and pancreatic cancer. Interferon-gamma (IFN-gamma) is an antifibrotic cytokine, but how precisely it exerts its effects on PSCs is largely unknown. Here, we have focussed on the role of STAT I as well as target genes of IFN-gamma signalling. Our data indicate that IFN-gamma regulates the expression of two autocrine mediators of PSC activation, connective tissue growth factor and endothelin-1, in a transforming growth factor-beta 1-antagonistic manner. STAT I overexpression under the control of a tetracycline-dependent promoter revealed a close correlation between STAT I expression and activation, the biological effects of IFN-gamma (growth inhibition, induction of apoptosis), and target gene expression. Our data further support the hypothesis that IFN-gamma interferes with stellate cell activation in the pancreas and suggest activated STAT1 as an inductor of a quiescent PSC phenotype. (c) 2006 Elsevier Inc. All rights reserved.