Mechanisms explaining the relationship in non-alcoholic fatty liver disease (NAFLD), obesity, and insulin resistance are poorly understood. A genetic basis has been suggested. We studied the associati Show more
Mechanisms explaining the relationship in non-alcoholic fatty liver disease (NAFLD), obesity, and insulin resistance are poorly understood. A genetic basis has been suggested. We studied the association between the genes patatin-like phospholipase domain-containing protein 3 (PNPLA3) and apolipoprotein C3 (APOC3) and metabolic and histological parameters of NAFLD in obese patients. Overweight and obese patients underwent a metabolic and liver assessment. If NAFLD was suspected, liver biopsy was proposed. APOC3 variant rs2854117 and PNPLA3 variant rs738409 were genotyped. Four hundred seventy patients were included (61.1% had liver biopsy). The percentage of patients with non-alcoholic steatohepatitis (NASH) was significantly different according to the PNPLA3 variant. After adjustment for age and body mass index, the PNPLA3 variant was associated with alanine aminotransferase (P < 0.001) and aspartate aminotransferase (P < 0.001). The PNPLA3 variant was associated with more severe features of steatohepatitis: steatosis (P < 0.001), lobular inflammation (P < 0.001), and ballooning (P = 0.002), but not with liver fibrosis, anthropometry, or insulin resistance. No significant difference in liver histology, anthropometric, or metabolic parameters was found between carriers and non-carriers of the APOC3 variant. PNPLA3 polymorphism rs738409 was associated with NASH and the severity of necroinflammatory changes independently of metabolic factors. No association between APOC3 gene variant rs2854117 and histological or metabolic parameters of NAFLD was found. Show less
Hypertriglyceridemia and fatty liver are common in patients with type 2 diabetes, but the factors connecting alterations in glucose metabolism with plasma and liver lipid metabolism remain unclear. Ap Show more
Hypertriglyceridemia and fatty liver are common in patients with type 2 diabetes, but the factors connecting alterations in glucose metabolism with plasma and liver lipid metabolism remain unclear. Apolipoprotein CIII (apoCIII), a regulator of hepatic and plasma triglyceride metabolism, is elevated in type 2 diabetes. In this study, we analyzed whether apoCIII is affected by altered glucose metabolism. Liver-specific insulin receptor-deficient mice display lower hepatic apoCIII mRNA levels than controls, suggesting that factors other than insulin regulate apoCIII in vivo. Glucose induces apoCIII transcription in primary rat hepatocytes and immortalized human hepatocytes via a mechanism involving the transcription factors carbohydrate response element-binding protein and hepatocyte nuclear factor-4α. ApoCIII induction by glucose is blunted by treatment with agonists of farnesoid X receptor and peroxisome proliferator-activated receptor-α but not liver X receptor, ie, nuclear receptors controlling triglyceride metabolism. Moreover, in obese humans, plasma apoCIII protein correlates more closely with plasma fasting glucose and glucose excursion after oral glucose load than with insulin. Glucose induces apoCIII transcription, which may represent a mechanism linking hyperglycemia, hypertriglyceridemia, and cardiovascular disease in type 2 diabetes. Show less