A blocking peptide for transforming growth factor-β1 activation prevents hepatic fibrosis in vivo

Background/Aims: Thrombospondin-1 is a major activator of transforming growth factor-beta1 (TGF-beta1), and a peptide derived from the latency-associated peptide, Leu-Ser-Lys-Leu (LSKL), inhibits the activation of TGF-beta1. In this study, the effects of LSKL on the hepatocyte damage and fibrogenesis in dimethylnitrosamine (DMN)-induced rat liver fibrosis were examined. Methods: Animals were given an intraperitoneal (i.p.) injection of DMN or saline three times per week for 4 weeks, and treated with LSKL, a control peptide, or saline i.p. daily. Results: Liver atrophy caused by DMN-injection was significantly inhibited in the DMN + LSKL group. The degrees of necrosis/degeneration and fibrosis scores were significantly lower in the DMN + LSKL group than in the control groups. The hydroxyproline content was significantly higher in the control groups than in the DMN + LSKL group. The amount of active TGF-beta1 was less in the DMN + LSKL group than in the control groups, and the active/total TGF-beta1 ratio in the DMN + LSKL group was suppressed in the control groups. Phosphorylation of Smad 2 in the liver was significantly decreased in the DMN + LSKL group. Conclusions: The LSKL peptide prevented the progression of hepatic damage and fibrosis through the inhibition of TGF-beta1 activation and its signal transduction in vivo. (C) 2003 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.