title: High fat diet feeding results in gender specific steatohepatitis and inflammasome activation.
abstract: OBJECTIVE
  To develop an animal model that encompasses the different facets of non-alcoholic steatohepatitis (NASH), which has been a challenge.
  
  
  METHODS
  In this study, we used a high fat diet (HFD) feeding supplemented with fructose and sucrose in the water mimicking the high-fructose corn syrup that is abundant in the diet in the United States. We used C57Bl/6 wild-type mice for short and long-term feedings of 6 and 16 wk respectively, and evaluated the extent of liver damage, steatosis, and inflammasome activation. Our methods included histopathological analysis to assess liver damage and steatosis, which involved H and E and oil-red-o staining; biochemical studies to look at ALT and triglyceride levels; RNA analysis using quantitative polymerase chain reaction; and cytokine analysis, which included the enzyme-linked immunosorbent assay method to look at interleukin (IL)-1β and tumor necrosis factor-α (TNFα) levels. Furthermore, at each length of feeding we also looked at insulin resistance and glucose tolerance using insulin tolerance tests (ITT) and glucose tolerance tests.
  
  
  RESULTS
  There was no insulin resistance, steatosis, or inflammasome activation at 6 wk. In contrast, at 16 wk we found significant insulin resistance demonstrated by impaired glucose and ITT in male, but not female mice. In males, elevated alanine aminotransferase and triglyceride levels, indicated liver damage and steatosis, respectively. Increased liver TNFα and monocyte chemoattractant protein-1 mRNA and protein, correlated with steatohepatitis. The inflammasome components, adaptor molecule, Aim2, and NOD-like receptor 4, increased at the mRNA level, and functional inflammasome activation was indicated by increased caspase-1 activity and IL-1β protein levels in male mice fed a long-term HFD. Male mice on HFD had increased α-smooth muscle actin and pro-collagen-1 mRNA indicating evolving fibrosis. In contrast, female mice displayed only elevated triglyceride levels, steatosis, and no fibrosis.
  
  
  CONCLUSIONS
  Our data indicate gender differences in NASH. Male mice fed a long-term HFD display steatohepatitis and inflammasome activation, whereas female mice have steatosis without inflammation.
authors.affiliation: Michal Ganz, Timea Csak, Gyongyi Szabo, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, United States.
authors.forename: Michal
authors.initials: M
authors.lastname: Ganz
authors.affiliation: Michal Ganz, Timea Csak, Gyongyi Szabo, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, United States.
authors.forename: Timea
authors.initials: T
authors.lastname: Csak
authors.affiliation: Michal Ganz, Timea Csak, Gyongyi Szabo, Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, United States.
authors.forename: Gyongyi
authors.initials: G
authors.lastname: Szabo
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism; D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D020170:Caspase 1 / Q000378:metabolism; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D059305:Diet, High-Fat / Q000009:adverse effects*; D019422:Dietary Sucrose / Q000009:adverse effects; D005260:Female; D005632:Fructose / Q000009:adverse effects; D058847:Inflammasomes / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance; D053583:Interleukin-1beta / Q000378:metabolism; D008099:Liver / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D008103:Liver Cirrhosis / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D008297:Male; D008810:Mice, Inbred C57BL; D065626:Non-alcoholic Fatty Liver Disease / Q000209:etiology* / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D011347:Procollagen / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012737:Sex Factors; D013997:Time Factors; D014280:Triglycerides / Q000097:blood; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D015430:Weight Gain
chemical_list: C558396:Acta2 protein, mouse; D000199:Actins; C540422:Aim2 protein, mouse; D001786:Blood Glucose; C491768:Ccl2 protein, mouse; D018932:Chemokine CCL2; D024042:Collagen Type I; D004268:DNA-Binding Proteins; D019422:Dietary Sucrose; C587672:IL1B protein, mouse; D058847:Inflammasomes; D018836:Inflammation Mediators; D007328:Insulin; D053583:Interleukin-1beta; D011347:Procollagen; D012333:RNA, Messenger; D014280:Triglycerides; D014409:Tumor Necrosis Factor-alpha; D005632:Fructose; D000410:Alanine Transaminase; D020170:Caspase 1
keywords: Gender differences; High fat diet; Inflammasome; Non-alcoholic steatohepatitis