From the metabolic syndrome to NAFLD or vice versa?
The metabolic syndrome encompasses metabolic and cardiovascular risk factors which predict diabetes and cardiovascular disease (CVD) better than any of its individual components. Nonalcoholic fatty liver disease (NAFLD) comprises a disease spectrum which includes variable degrees of simple steatosis (nonalcoholic fatty liver, NAFL), nonalcoholic steatohepatitis (NASH) and cirrhosis. NAFLD is the hepatic manifestation of the metabolic syndrome, with insulin resistance as the main pathogenetic mechanism. Recent data indicate that hyperinsulinemia is probably the consequence rather than cause of NAFLD and NAFLD can be considered an independent predictor of cardiovascular disease. Serum free fatty acids derived from lipolysis of visceral adipose tissue are the main source of hepatic triglycerides in NAFLD, although hepatic de novo lipogenesis and dietary fat supply contribute to the pathogenesis of NAFLD. Approximately 10-25% NAFLD patients develop NASH, the evolutive form of hepatic steatosis. Presumably in a genetically predisposed environment, this increased lipid overload overwhelms the oxidative capacity and reactive oxygen species are generated, leading to lipid peroxidation, cytokine induction, chemoattraction of inflammatory cells, hepatic stellate cell activation and finally fibrogenesis with extracellular matrix deposition. No currently available therapies for NAFLD and NASH exist. Recently nuclear receptors have emerged as key regulators of lipid and carbohydrate metabolism for which specific pharmacological ligands are available, making them attractive therapeutic targets for NAFLD and NASH.
Vanni
Ester
E
Division of Gastro-Hepatology, San Giovanni Battista Hospital, University of Turin, C. so Bramante 88, 10126 Turin, Italy.
Bugianesi
Elisabetta
E
Kotronen
Anna
A
De Minicis
Samuele
S
Yki-Järvinen
Hannele
H
Svegliati-Baroni
Gianluca
G
D000273:Adipose Tissue / Q000503:physiopathology; D005234:Fatty Liver / Q000150:complications / Q000235:genetics / Q000503:physiopathology*; D020022:Genetic Predisposition to Disease; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D024821:Metabolic Syndrome / Q000150:complications / Q000503:physiopathology*; D047492:Peroxisome Proliferator-Activated Receptors / Q000502:physiology
D047492:Peroxisome Proliferator-Activated Receptors