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Hedgehog-mediated Epithelial-to-mesenchymal Transition and Fibrogenic Repair in Nonalcoholic Fatty Liver Disease

Abstract

Background & Aims: Repair responses define the ultimate outcomes of liver disease. This study evaluated the hypothesis that fibrogenic repair in nonalcoholic fatty liver disease (NAFLD) is mediated by Hedgehog (Hh) pathway activation and consequent induction of epithelial-to-mesenchymal transitions (EMT) in ductular-type progenitors.

Methods: Immature ductular cells were exposed to Sonic hedgehog (Shh) in the presence or absence of the Hh inhibitor cyclopamine to determine whether Hh-pathway activation directly modulates EMT in liver progenitors. Potential biologic correlates of progenitor cell EMT were assessed using mice fed methionine-choline-deficient + ethionine (MCDE) diets with or without cyclopamine. The effects of increased Hh signaling on EMT and fibrogenic repair during diet-induced NAFLD were also compared in wild-type (WT) and Patched haplo-insufficient (Ptc(+/-)) mice. Finally, evidence of Hh-pathway activation and EMT was examined in liver sections from patients with NAFLD.

Results: In cultured progenitors, Shh repressed expression of epithelial genes and EMT inhibitors but induced genes that are expressed by myofibroblasts. Cyclopamine reversed these effects. In mouse NAFLD models, Hh-pathway activation, EMT, expansion of myofibroblastic populations, and liver fibrosis occurred. Cyclopamine inhibited Hh-pathway activation and induction of EMT. Ptc(+/-) mice, which have an overactive Hh pathway, exhibited sustained overinduction of Hh target genes and more EMT, myofibroblast accumulation, and fibrosis than WT mice. Numbers of Shh-producing cells and Hh-responsive ductular cells that expressed EMT markers increased in parallel with liver fibrosis in patients with NAFLD.

Conclusions: Hh-mediated EMT in ductular cells contributes to the pathogenesis of cirrhosis in NAFLD.

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References
1.
Derynck R, Zhang Y . Smad-dependent and Smad-independent pathways in TGF-beta family signalling. Nature. 2003; 425(6958):577-84. DOI: 10.1038/nature02006. View

2.
Richardson M, Jonsson J, Powell E, Brunt E, Neuschwander-Tetri B, Bhathal P . Progressive fibrosis in nonalcoholic steatohepatitis: association with altered regeneration and a ductular reaction. Gastroenterology. 2007; 133(1):80-90. DOI: 10.1053/j.gastro.2007.05.012. View

3.
Caldwell S, Oelsner D, Iezzoni J, Hespenheide E, Battle E, Driscoll C . Cryptogenic cirrhosis: clinical characterization and risk factors for underlying disease. Hepatology. 1999; 29(3):664-9. DOI: 10.1002/hep.510290347. View

4.
Yang L, Wang Y, Mao H, Fleig S, Omenetti A, Brown K . Sonic hedgehog is an autocrine viability factor for myofibroblastic hepatic stellate cells. J Hepatol. 2007; 48(1):98-106. PMC: 2196213. DOI: 10.1016/j.jhep.2007.07.032. View

5.
Kowanetz M, Valcourt U, Bergstrom R, Heldin C, Moustakas A . Id2 and Id3 define the potency of cell proliferation and differentiation responses to transforming growth factor beta and bone morphogenetic protein. Mol Cell Biol. 2004; 24(10):4241-54. PMC: 400464. DOI: 10.1128/MCB.24.10.4241-4254.2004. View