title: Diabetes is a progression factor for hepatic fibrosis in a high fat fed mouse obesity model of non-alcoholic steatohepatitis.
abstract: OBJECTIVE
  While type 2 diabetes is an independent risk factor for worsening of human non-alcoholic steatohepatitis (NASH) in clinical studies, it has not been systematically reported in any model whether diabetes exacerbates NASH. The study aim was to determine if diabetes causes NASH progression in a mouse model of diet induced obesity.
  
  
  METHODS
  C57BL/6 mice were fed a high fat diet (HFD: 45% kcal fat) or standard chow (CHOW: 12% kcal fat) for 20 weeks and some animals (HFD+DM or CHOW+DM) were also rendered diabetic by low dose streptozotocin for the final 5 weeks, to model type 2 diabetes. Serum assays included circulating insulin, triglyceride, ALT and AST, glucose, and ultrasensitive CRP and results of insulin tolerance tests. Intrahepatic lipid, triglyceride, macrophage infiltration, and fibrosis were determined. Fibrosis markers collagen-I, collagen-III, CTGF, TIMP-1, and FAP were assessed by qPCR and CTGF and collagen-I by immunostaining.
  
  
  RESULTS
  HFD mice were obese, insulin resistant and hyperinsulinaemic, with NASH features of elevated intrahepatic lipid and macrophages, but without fibrosis. In contrast, the HFD+DM mice exhibited fibrosis in addition to these NASH features. By ANOVA, Sirius red staining at perisinusoidal, portal tract and central vein sites, collagen-I, collagen-III, FAP, and TIMP-1 transcripts and collagen-I and CTGF protein were each significantly increased in HFD+DM, compared with CHOW alone. In a further experiment, insulin treatment protected against fibrosis and CRP increases in HFD+DM, showing that diabetes, not streptozotocin, causes the fibrosis.
  
  
  CONCLUSIONS
  This novel model indicates that diet-induced NASH fibrosis is exacerbated by diabetes and attenuated by insulin therapy.
authors.affiliation: Discipline of Medicine and the Bosch Institute, NSW 2006, Australia.
authors.forename: Lisa
authors.initials: L
authors.lastname: Lo
authors.forename: Susan V
authors.initials: SV
authors.lastname: McLennan
authors.forename: Paul F
authors.initials: PF
authors.lastname: Williams
authors.forename: James
authors.initials: J
authors.lastname: Bonner
authors.forename: Sumaiya
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: McCaughan
authors.forename: Mark D
authors.initials: MD
authors.lastname: Gorrell
authors.forename: Dennis K
authors.initials: DK
authors.lastname: Yue
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Twigg
mesh_terms: D000818:Animals; D003094:Collagen / Q000235:genetics / Q000378:metabolism; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000188:drug therapy; D004041:Dietary Fats / Q000008:administration & dosage; D004195:Disease Models, Animal; D018450:Disease Progression; D005234:Fatty Liver / Q000209:etiology* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007328:Insulin / Q000627:therapeutic use; D050356:Lipid Metabolism; D008112:Liver Glycogen / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D065626:Non-alcoholic Fatty Liver Disease; D009765:Obesity / Q000150:complications; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: C526318:CCN2 protein, mouse; D004041:Dietary Fats; D007328:Insulin; D008112:Liver Glycogen; D012333:RNA, Messenger; D055513:Connective Tissue Growth Factor; D003094:Collagen