Inhibition of Transforming Growth Factor β Signaling by Halofuginone as a Modality for Pancreas Fibrosis Prevention

Objectives: Chronic pancreatitis is characterized by inflammation and fibrosis. We evaluated the efficacy of halofuginone, an inhibitor of collagen synthesis and myofibroblast activation, in preventing cerulein-induced pancreas fibrosis. Methods: Collagen synthesis was evaluated by in situ hybridization and staining. Levels of prolyl 4-hydroxylase beta (P4H beta A), cytoglobin/stellate cell activation-associated protein (Cygb/STAP), transgelin, tissue inhibitors of metalloproteinases, serum response factor, transforming growth factor beta (TGF beta), Smad3, and pancreatitis-associated protein 1 (PAP-1) were determined by immunohistochemistry. Metalloproteinase activity was evaluated by zymography. Results: Halofuginone prevented cerulein-dependent increase in collagen synthesis, collagen cross-linking enzyme P4H beta, Cygb/STAP, and tissue inhibitors of metalloproteinase 2. Halofuginone did not affect TGF beta levels in cerulein-treated mice but inhibited serum response factor synthesis and Smad3 phosphorylation. In culture, halofuginone inhibited pancreatic stellate cell (PSC) proliferation and TGF beta-dependent increase in Cygb/STAP and transgelin synthesis and metalloproteinase 2 activity. Halofuginone increased c-Jun N-terminal kinase phosphorylation in PSCs derived from cerulein-treated mice. Halofuginone prevented the increase in acinar cell proliferation and further increased the cerulein-dependent PAP-1 synthesis. Conclusions: Halofuginone inhibits Smad3 phosphorylation and increases c-Jun N-terminal kinase phosphorylation, leading to the inhibition of PSC activation and consequent prevention of fibrosis. Halofuginone increased the synthesis of PAP-1, which further reduces pancreas fibrosis. Thus, halofuginone might serve as a novel therapy for pancreas fibrosis.