title: Astaxanthin prevents TGFβ1-induced pro-fibrogenic gene expression by inhibiting Smad3 activation in hepatic stellate cells.
abstract: BACKGROUND
  Non-alcoholic steatohepatitis (NASH) is a subset of non-alcoholic fatty liver disease, the most common chronic liver disease in the U.S. Fibrosis, a common feature of NASH, results from the dysregulation of fibrogenesis in hepatic stellate cells (HSCs). In this study, we investigated whether astaxanthin (ASTX), a xanthophyll carotenoid, can inhibit fibrogenic effects of transforming growth factor β1 (TGFβ1), a key fibrogenic cytokine, in HSCs.
  
  
  METHODS
  Reactive oxygen species (ROS) accumulation was measured in LX-2, an immortalized human HSC cell line. Quantitative realtime PCR, Western blot, immunocytochemical analysis, and in-cell Western blot were performed to determine mRNA and protein of fibrogenic genes, and the activation of Smad3 in TGFβ1-activated LX-2 cells and primary mouse HSCs.
  
  
  RESULTS
  In LX-2 cells, ROS accumulation induced by tert-butyl hydrogen peroxide and TGFβ1 was abolished by ASTX. ASTX significantly decreased TGFβ1-induced α-smooth muscle actin (α-SMA) and procollagen type 1, alpha 1 (Col1A1) mRNA as well as α-SMA protein levels. Knockdown of Smad3 showed the significant role of Smad3 in the expression of α-SMA and Col1A1, but not TGFβ1, in LX-2 cells. ASTX attenuated TGFβ1-induced Smad3 phosphorylation and nuclear translocation with a concomitant inhibition of Smad3, Smad7, TGFβ receptor I (TβRI), and TβRII expression. The inhibitory effect of ASTX on HSC activation was confirmed in primary mouse HSCs as evidenced by decreased mRNA and protein levels of α-SMA during activation.
  
  
  CONCLUSIONS
  Taken together, ASTX exerted anti-fibrogenic effects by blocking TGFβ1-signaling, consequently inhibiting the activation of Smad3 pathway in HSCs.
  
  
  CONCLUSIONS
  This study suggests that ASTX may be used as a preventive/therapeutic agent to prevent hepatic fibrosis.
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Bohkyung
authors.initials: B
authors.lastname: Kim
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Young-Ki
authors.initials: YK
authors.lastname: Park
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Sung I
authors.initials: SI
authors.lastname: Koo
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA. Electronic address: ji-young.lee@uconn.edu.
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Lee
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005343:Fibrinolytic Agents / Q000494:pharmacology; D005355:Fibrosis / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D055166:Hepatic Stellate Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008810:Mice, Inbred C57BL; D009130:Muscle, Smooth / Q000737:chemistry; D010766:Phosphorylation / Q000187:drug effects; D034622:RNA Interference; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D024341:Xanthophylls / Q000494:pharmacology
chemical_list: D000199:Actins; D024042:Collagen Type I; D005343:Fibrinolytic Agents; D051900:Smad3 Protein; D053773:Transforming Growth Factor beta1; D024341:Xanthophylls; C005948:astaxanthine
keywords: Astaxanthin; Hepatic stellate cell; Liver fibrosis; Non-alcoholic steatohepatitis; Smad3; Transforming growth factor β1