NKT-associated hedgehog and osteopontin drive fibrogenesis in non-alcoholic fatty liver disease
- Wing-Kin Syn1,2,3,
- Kolade M Agboola1,
- Marzena Swiderska1,
- Gregory A Michelotti1,
- Evaggelia Liaskou2,
- Herbert Pang4,
- Guanhua Xie1,
- George Philips1,
- Isaac S Chan1,
- Gamze F Karaca1,
- Thiago de Almeida Pereira1,5,
- Yuping Chen1,
- Zhiyong Mi6,
- Paul C Kuo6,
- Steve S Choi1,7,
- Cynthia D Guy8,
- Manal F Abdelmalek1,
- Anna Mae Diehl1
- 1Division of Gastroenterology, Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA
- 2Centre for Liver Research, University of Birmingham, Edgbaston, Birmingham, UK
- 3Foundation for Liver Research, Institute of Hepatology, London, UK
- 4Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, North Carolina, USA
- 5Nucleo de Deoncas Infecciosas, Centro de Ciencias da Caude, Universidade Federal do Espirito Santo, Espirito Santo, Brazil
- 6Department of Surgery, Loyola University Chicago, Chicago, Illinois, USA
- 7Section of Gastroenterology, Department of Medicine, Durham Veteran Affairs Medical Center, Durham, North Carolina, USA
- 8Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
- Correspondence to Professor Anna Mae Diehl, Florence McAlister Professor & Chief, Division of Gastroenterology, Duke University, Snyderman Bldg, Suite 1073, 595 LaSalle Street, Durham, NC 27710, USA; Dr Wing-Kin Syn, Physician-Scientist, Head of Regeneration and Repair, Institute of Hepatology Harold Samuel House, 69-75 Chenies Mews, London WC1E 6HX
Contributors Wing-Kin Syn performed the majority of experimental and human studies. All other authors also conducted other relevant experiments. Anna Mae Diehl is the senior author and guarantor for the paper.
- Revised 17 January 2012
- Accepted 25 January 2012
- Published Online First 17 March 2012
Objective Immune responses are important in dictating non-alcoholic steatohepatitis (NASH) outcome. We previously reported that upregulation of hedgehog (Hh) and osteopontin (OPN) occurs in NASH, that Hh-regulated accumulation of natural killer T (NKT) cells promotes hepatic stellate cell (HSC) activation, and that cirrhotic livers harbour large numbers of NKT cells.
Design The hypothesis that activated NKT cells drive fibrogenesis during NASH was evaluated by assessing if NKT depletion protects against NASH fibrosis; identifying the NKT-associated fibrogenic factors; and correlating plasma levels of the NKT cell-associated factor OPN with fibrosis severity in mice and humans.
Results When fed methionine-choline-deficient (MCD) diets for 8 weeks, wild type (WT) mice exhibited Hh pathway activation, enhanced OPN expression, and NASH-fibrosis. Ja18‒/‒ and CD1d‒/‒ mice which lack NKT cells had significantly attenuated Hh and OPN expression and dramatically less fibrosis. Liver mononuclear cells (LMNCs) from MCD diet fed WT mice contained activated NKT cells, generated Hh and OPN, and stimulated HSCs to become myofibroblasts; neutralising these factors abrogated the fibrogenic actions of WT LMNCs. LMNCs from NKT-cell-deficient mice were deficient in fibrogenic factors, failing to activate collagen gene expression in HSCs. Human NASH livers with advanced fibrosis contained more OPN and Hh protein than those with early fibrosis. Plasma levels of OPN mirrored hepatic OPN expression and correlated with fibrosis severity.
Conclusion Hepatic NKT cells drive production of OPN and Hh ligands that promote fibrogenesis during NASH. Associated increases in plasma levels of OPN may provide a biomarker of NASH fibrosis.
- natural killer T cells
- non-alcoholic steatohepatitis
- non-alcoholic steatohepatitis
- partial hepatectomy
- liver disease in pregnancy
- liver regeneration
- liver cirrhosis
- molecular genetics
- liver metabolism
- gene expression
- cancer genetics
- cell biology
- hepatocellular carcinoma
- carcinogen metabolism
- hepatic fibrosis
- molecular biology
- fatty liver
- liver immunology
- basic sciences
Funding This work was supported by grants from the National Institute of Health, RO1 DK053792 (AMD) and RO1 DK077794 (AMD), and by the EASL fellowship (WKS) and BRET grant (WKS).
Competing interests None.
Patient consent The study involved the use of archived liver sections from which local ethics and informed consent had been obtained previously for the sampling of liver samples. For the isolation and FACS analysis of liver lymphocytes, informed consent was obtained from the patient undergoing liver resection (for the use of the resected livers for research).
Ethics approval Ethics approval was provided by Duke University and the South Birmingham Research Ethics Committee, UK (Birmingham local ethical approval 04/Q2708/41 and REC 2003/242).
Provenance and peer review Not commissioned; externally peer reviewed.