Figure 3.

Fatty acid oxidation system in NAFLD. The fatty acid oxidation system consists of peroxisome, mitochondria and microsomes. Mitochondria play a vital role in fatty acid oxidation and energy supply. Glucose enhanced glycolysis and increased pyruvate content through the de novo lipogenesis (DNL) pathway. Pyruvate enters mitochondria and is converted into acetyl-CoA. Part of acetyl-CoA enters tricarboxylic acid cycle (TCA) and then synthesizes free fatty acids (FFAs) through the DNL pathway. The synthesized FFAs enter mitochondria together with the plasma FFAs through carnitine palmitoyltransferase 1 (CPT1) and are converted into acyl-CoA. Acyl-CoA is converted into acetyl-CoA by β-oxidation and enters the TCA to generate energy. The components of the mitochondrial respiratory chain are abnormally reduced by electrons and react with oxygen, producing a large number of reactive oxygen species (ROS). ROS further oxidize lipid deposition to form lipid peroxide, which leads to inflammatory reaction. Abbreviations: ETC, electron transport chain; PPAR, peroxisome proliferation-activated receptor.