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Hepatology
Original article
Signalling via the osteopontin and high mobility group box-1 axis drives the fibrogenic response to liver injury
  1. Elena Arriazu1,
  2. Xiaodong Ge1,2,
  3. Tung-Ming Leung1,
  4. Fernando Magdaleno1,2,
  5. Aritz Lopategi1,
  6. Yongke Lu1,
  7. Naoto Kitamura1,
  8. Raquel Urtasun1,
  9. Neil Theise3,
  10. Daniel J Antoine4,
  11. Natalia Nieto1,2
  1. 1Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA
  2. 2Department of Pathology, University of Illinois at Chicago, Chicago, Illinois, USA
  3. 3Division of Digestive Diseases, Mount Sinai Beth Israel Medical Center, New York, New York, USA
  4. 4Medical Research Council Centre for Drug Safety Science, Molecular and Clinical Pharmacology, University of Liverpool, Liverpool, UK
  1. Correspondence to Dr Natalia Nieto, Department of Pathology, University of Illinois at Chicago, 840 S. Wood St., Suite 130 CSN, MC 847, Chicago IL 60612, USA; nnieto{at}uic.edu

Abstract

Objective Liver fibrosis is associated with significant collagen-I deposition largely produced by activated hepatic stellate cells (HSCs); yet, the link between hepatocyte damage and the HSC profibrogenic response remains unclear. Here we show significant induction of osteopontin (OPN) and high-mobility group box-1 (HMGB1) in liver fibrosis. Since OPN was identified as upstream of HMGB1, we hypothesised that OPN could participate in the pathogenesis of liver fibrosis by increasing HMGB1 to upregulate collagen-I expression.

Design and results Patients with long-term hepatitis C virus (HCV) progressing in disease stage displayed enhanced hepatic OPN and HMGB1 immunostaining, which correlated with fibrosis stage, whereas it remained similar in non-progressors. Hepatocyte cytoplasmic OPN and HMGB1 expression was significant while loss of nuclear HMGB1 occurred in patients with HCV-induced fibrosis compared with healthy explants. Well-established liver fibrosis along with marked induction of HMGB1 occurred in CCl4-injected OpnHep transgenic yet it was less in wild type and almost absent in Opn−/− mice. Hmgb1 ablation in hepatocytes (Hmgb1ΔHep) protected mice from CCl4-induced liver fibrosis. Coculture with hepatocytes that secrete OPN plus HMGB1 and challenge with recombinant OPN (rOPN) or HMGB1 (rHMGB1) enhanced collagen-I expression in HSCs, which was blunted by neutralising antibodies (Abs) and by Opn or Hmgb1 ablation. rOPN induced acetylation of HMGB1 in HSCs due to increased NADPH oxidase activity and the associated decrease in histone deacetylases 1/2 leading to upregulation of collagen-I. Last, rHMGB1 signalled via receptor for advanced glycation end-products and activated the PI3K–pAkt1/2/3 pathway to upregulate collagen-I.

Conclusions During liver fibrosis, the increase in OPN induces HMGB1, which acts as a downstream alarmin driving collagen-I synthesis in HSCs.

  • BASIC SCIENCES
  • HEPATIC STELLATE CELL
  • HEPATIC FIBROSIS
  • HEPATOCYTE
  • SIGNALING

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/gutjnl-2015-310752

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