title: Irisin is inversely associated with intrahepatic triglyceride contents in obese adults.
abstract: OBJECTIVE
  Obesity is closely related to non-alcoholic fatty liver disease (NAFLD), which has become an important public health problem because of its high prevalence and association with metabolic syndromes. Irisin was recently identified as a novel peptide to improve obesity and glucose homeostasis, and considered to be therapeutic for human metabolic diseases. The aim of this study was to examine the association of serum irisin concentration and liver triglyceride contents in obese Chinese adults.
  
  
  METHODS
  Serum irisin levels were measured and liver fat contents determined by (1)H MRS in 296 obese adults. Anthropometric parameters and blood biochemical indexes including liver enzymes, glucose, and lipid profiles were detected. The liver triglyceride contents of subjects were measured by (1)H MRS. The protein levels of irisin were determined by quantitative ELISA.
  
  
  RESULTS
  We found that serum irisin levels were reduced in obese adults with NAFLD. By dividing the distribution of intrahepatic triglyceride (IHTG) contents into quartiles, serum irisin levels were reduced gradually with the increase of IHTG contents (p<0.01). Higher serum irisin levels were associated with preferable TG levels. Serum ALT and AST concentrations were inversely correlated with serum irisin levels. Multivariate linear regression analysis demonstrated that serum irisin levels were independently associated with liver fat (p<0.01). By logistic regression analysis, the odds ratio for higher IHTG contents was reduced by 12.4% per 1 SD increase in serum irisin concentrations after adjustment for multivariate metabolic factors [OR (95% CI); 0.876 (0.777-0.987)].
  
  
  CONCLUSIONS
  These results demonstrated that serum irisin concentrations were inversely associated with the triglyceride contents in the liver and liver enzymes in obese Chinese adults.
authors.affiliation: Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Key Laboratory of Endocrine Tumor, Shanghai Institute of Endocrinology and Metabolism, Rui-Jin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Rui-Jin 2nd Road, Shanghai 200025, China.
authors.forename: Hui-Jie
authors.initials: HJ
authors.lastname: Zhang
authors.forename: Xian-Feng
authors.initials: XF
authors.lastname: Zhang
authors.forename: Zhi-Min
authors.initials: ZM
authors.lastname: Ma
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Pan
authors.forename: Zheng
authors.initials: Z
authors.lastname: Chen
authors.forename: Hai-Wei
authors.initials: HW
authors.lastname: Han
authors.forename: Cheng-Kun
authors.initials: CK
authors.lastname: Han
authors.forename: Xiong-Jie
authors.initials: XJ
authors.lastname: Zhuang
authors.forename: Yan
authors.initials: Y
authors.lastname: Lu
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Li
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Yang
authors.forename: Xiao-Ying
authors.initials: XY
authors.lastname: Li
mesh_terms: D000328:Adult; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood; D044466:Asian People; D001219:Aspartate Aminotransferases / Q000097:blood; D002681:China; D003430:Cross-Sectional Studies; D005234:Fatty Liver / Q000097:blood / Q000150:complications / Q000378:metabolism; D005260:Female; D005353:Fibronectins / Q000097:blood*; D006801:Humans; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease; D009765:Obesity / Q000097:blood* / Q000150:complications / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism*
chemical_list: C577593:FNDC5 protein, human; D005353:Fibronectins; D014280:Triglycerides; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase
keywords: Intrahepatic triglyceride content; Irisin; Non-alcoholic fatty liver disease; Obesity