Osteopontin is a proximal effector of leptin-mediated non-alcoholic steatohepatitis (NASH) fibrosis

Research output: Contribution to journalArticle

Authors

  • Jason D Coombes
  • Steve S Choi
  • Marzena Swiderska-Syn
  • Paul Manka
  • Danielle T Reid
  • Elena Palma
  • Marco A Briones-Orta
  • Guanhua Xie
  • Rasha Younis
  • Naoto Kitamura
  • Marco Della Peruta
  • Shanna Bitencourt
  • Laurent Dollé
  • Zhiyong Mi
  • Paul C Kuo
  • Roger Williams
  • Shilpa Chokshi
  • Ali Canbay
  • Lee C Claridge
  • Bertus Eksteen
  • Anna Mae Diehl

Abstract

INTRODUCTION: Liver fibrosis develops when hepatic stellate cells (HSC) are activated into collagen-producing myofibroblasts. In non-alcoholic steatohepatitis (NASH), the adipokine leptin is upregulated, and promotes liver fibrosis by directly activating HSC via the hedgehog pathway. We reported that hedgehog-regulated osteopontin (OPN) plays a key role in promoting liver fibrosis. Herein, we evaluated if OPN mediates leptin-profibrogenic effects in NASH.

METHODS: Leptin-deficient (ob/ob) and wild-type (WT) mice were fed control or methionine-choline deficient (MCD) diet. Liver tissues were assessed by Sirius-red, OPN and αSMA IHC, and qRT-PCR for fibrogenic genes. In vitro, HSC with stable OPN (or control) knockdown were treated with recombinant (r)leptin and OPN-neutralizing or sham-aptamers. HSC response to OPN loss was assessed by wound healing assay. OPN-aptamers were also added to precision-cut liver slices (PCLS), and administered to MCD-fed WT (leptin-intact) mice to determine if OPN neutralization abrogated fibrogenesis.

RESULTS: MCD-fed WT mice developed NASH-fibrosis, upregulated OPN, and accumulated αSMA+ cells. Conversely, MCD-fed ob/ob mice developed less fibrosis and accumulated fewer αSMA+ and OPN+ cells. In vitro, leptin-treated HSC upregulated OPN, αSMA, collagen 1α1 and TGFβ mRNA by nearly 3-fold, but this effect was blunted by OPN loss. Inhibition of PI3K and transduction of dominant negative-Akt abrogated leptin-mediated OPN induction, while constitutive active-Akt upregulated OPN. Finally, OPN neutralization reduced leptin-mediated fibrogenesis in both PCLS and MCD-fed mice.

CONCLUSION: OPN overexpression in NASH enhances leptin-mediated fibrogenesis via PI3K/Akt. OPN neutralization significantly reduces NASH fibrosis, reinforcing the potential utility of targeting OPN in the treatment of patients with advanced NASH.

Details

Original languageEnglish
Pages (from-to)135-144
Number of pages10
JournalBiochimica et Biophysica Acta
Volume1862
Issue number1
Early online date31 Oct 2015
Publication statusPublished - Jan 2016

Keywords

  • fibrosis, hepatic, adipokine, signaling