title: Hepatocyte senescence predicts progression in non-alcohol-related fatty liver disease.
abstract: OBJECTIVE
  Models of non-alcohol-related fatty liver disease (NAFLD) reveal features of accelerated ageing, such as impaired regeneration, and an increased risk of hepatocellular carcinoma. The relation between accelerated ageing, disease progression and clinical outcome has not been previously investigated and is the subject of the current study.
  
  
  METHODS
  Liver sections from 70 patients with NAFLD (105 biopsies) and 60 controls were studied for telomere length, nuclear area, DNA damage and cell cycle phase markers, using quantitative fluorescent in situ hybridization and immunohistochemistry.
  
  
  RESULTS
  Hepatocyte telomeres were shorter in NAFLD than controls (p <0.0001). Hepatocytes in NAFLD demonstrated lack of cell cycle progression beyond G1/S phase and high-level expression of p21, the universal cell cycle inhibitor (p=0.001). γ-H(2)AX expression increased with steatosis (p=0.01), indicating DNA damage, and was associated with shorter hepatocyte telomeres (p <0.0001). Hepatocyte p21 expression correlated with fibrosis stage and diabetes mellitus, independently (p <0.001 and p=0.002, respectively). Further analysis revealed that an adverse liver-related outcome was strongly associated with higher hepatocyte p21 expression and greater hepatocyte nuclear area (p=0.02 and p=0.006), but not with telomere length. In paired biopsies, changes in hepatocyte p21 expression and nuclear area mirrored changes in fibrosis stage (p=0.01 and p=0.006, respectively).
  
  
  CONCLUSIONS
  These findings are consistent with hepatocyte senescence and permanent cell cycle arrest in NAFLD. Hepatocyte senescence correlated closely with fibrosis stage, diabetes mellitus, and clinical outcome. Hepatocyte p21 expression could be used as a prognostic marker and for stratification in clinical studies.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Medicine, University of Cambridge, Cambridge CB2 0QQ, UK.
authors.forename: Aloysious
authors.initials: A
authors.lastname: Aravinthan
authors.forename: Cinzia
authors.initials: C
authors.lastname: Scarpini
authors.forename: Phaedra
authors.initials: P
authors.lastname: Tachtatzis
authors.forename: Suman
authors.initials: S
authors.lastname: Verma
authors.forename: Sue
authors.initials: S
authors.lastname: Penrhyn-Lowe
authors.forename: Rebecca
authors.initials: R
authors.lastname: Harvey
authors.forename: Susan E
authors.initials: SE
authors.lastname: Davies
authors.forename: Michael
authors.initials: M
authors.lastname: Allison
authors.forename: Nick
authors.initials: N
authors.lastname: Coleman
authors.forename: Graeme
authors.initials: G
authors.lastname: Alexander
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D002467:Cell Nucleus / Q000473:pathology; D016922:Cellular Senescence; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000032:analysis; D018450:Disease Progression; D005234:Fatty Liver / Q000473:pathology*; D005260:Female; D022781:Hepatocytes / Q000473:pathology*; D006657:Histones / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease; D016615:Telomere
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; C468783:H2AX protein, human; D006657:Histones