Very low density lipoprotein and low density lipoprotein isolated from patients with hepatitis C infection induce altered cellular lipid metabolism

2007 ◽  
Vol 79 (3) ◽  
pp. 254-258 ◽  
Author(s):  
Mariarosaria Napolitano ◽  
Alessandro Giuliani ◽  
Tonino Alonzi ◽  
Carmine Mancone ◽  
Gianpiero D'Offizi ◽  
...  
2001 ◽  
Vol 100 (5) ◽  
pp. 517-527 ◽  
Author(s):  
Jason M. R. GILL ◽  
Keith N. FRAYN ◽  
Stephen A. WOOTTON ◽  
George J. MILLER ◽  
Adrianne E. HARDMAN

Moderate exercise reduces postprandial triacylglycerol concentrations, which are a risk marker for coronary heart disease. The present study sought to determine the qualitative nature of exercise-induced changes in lipid metabolism and their association (if any) with changes in factor VII activation. Eleven normotriglyceridaemic men, aged 51.7±6.1 years (mean±S.D.), participated in two oral fat tolerance tests after different pre-conditions: control (no exercise), and exercise (90 min of brisk walking the day before). Venous blood samples were obtained in the fasted state and for 8 h after ingestion of a high-fat meal (1.32 g of fat, 1.36 g of carbohydrate, 0.30 g of protein and 10 mg of [1,1,1-13C] tripalmitin·kg-1 body mass). Prior exercise reduced postprandial plasma triacylglycerol concentrations by 25±3% (mean±S.E.M.), with lower concentrations in the Svedberg flotation rate (Sf) 20–400 (very-low-density lipoprotein) fraction accounting for 79±10% of this reduction. There was no effect on plasma factor VII coagulant activity or on the concentration of the active form of factor VIIa. Prior exercise increased postprandial serum 3-hydroxybutyrate and plasma fatty acid concentrations, decreased serum postprandial insulin concentrations and increased exogenous (8 h 13C breath excretion of 15.1±0.9% of ingested dose compared with 11.9±0.8%; P = 0.00001) and endogenous postprandial fat oxidation. These data raise the possibility that reduced hepatic secretion of very-low-density lipoprotein plays a role in the attenuation of plasma triacylglycerol concentrations seen after exercise, although it is possible that increased triacylglycerol clearance also contributes to this effect.


Endocrinology ◽  
2009 ◽  
Vol 150 (5) ◽  
pp. 2169-2174 ◽  
Author(s):  
Wan Huang ◽  
Anantha Metlakunta ◽  
Nikolas Dedousis ◽  
Heidi K. Ortmeyer ◽  
Maja Stefanovic-Racic ◽  
...  

It is well established that leptin increases the sensitivity of carbohydrate metabolism to the effects of insulin. Leptin and insulin also have potent effects on lipid metabolism. However, the effects of leptin on the regulation of liver lipid metabolism by insulin have not been investigated. The current study addressed the effects of leptin on insulin-regulated hepatic very low-density lipoprotein (VLDL) metabolism in vivo in rats. A 90-min hyperinsulinemic/euglycemic clamp (4 mU/kg · min−1) reduced plasma VLDL triglyceride (TG) by about 50% (P < 0.001 vs. saline control). Importantly, a leptin infusion (0.2 μg/kg · min−1) in combination with insulin reduced plasma VLDL-TG by about 80% (P < 0.001 vs. insulin alone). These effects did not require altered skeletal muscle lipoprotein lipase activity but did include differential effects of insulin and leptin on liver apolipoprotein (apo) B and TG metabolism. Thus, insulin decreased liver and plasma apoB100/B48 levels (∼50%, P < 0.01), increased liver TGs (∼20%, P < 0.05), and had no effect on fatty acid oxidation. Conversely, leptin decreased liver TGs (∼50%, P < 0.01) and increased fatty acid oxidation (∼50%, P < 0.01) but had no effects on liver or plasma apoB levels. Importantly, the TG-depleting and prooxidative effects of leptin were maintained in the presence of insulin. We conclude that leptin additively increases the suppressive effects of insulin on hepatic and systemic VLDL metabolism by stimulating depletion of liver TGs and increasing oxidative metabolism. The net effect of the combined actions of insulin and leptin is to decrease the production and TG content of VLDL particles.


2020 ◽  
Vol 318 (2) ◽  
pp. E262-E275 ◽  
Author(s):  
Jing Zhang ◽  
Ferdous Rastgar Jazii ◽  
Mahdi Montazer Haghighi ◽  
Danielle Alvares ◽  
Lipei Liu ◽  
...  

miR-130b is a microRNA whose expression is particularly elevated within adipose tissue and in the circulation in diabetic states. Hepatic miR-130b expression has been linked to hepatocellular carcinoma and changes in lipid metabolism. Here, we investigated the role of miR-130b in hepatic lipid homeostasis and lipoprotein export. We observed that overexpression of miR-130b-3p or -5p in HepG2 cells markedly enhanced the secretion of very-low-density lipoprotein (VLDL) particles, enhanced the secretion of [3H]glycerol metabolically labeled triglyceride (TG), and significantly increased the number or the average size of lipid droplets (LDs), respectively. Overexpression of miR-130b also altered the expression of key genes involved in lipid metabolism and in particular markedly increased both mRNA and protein expression levels of microsomal triglyceride transfer protein (MTP). Conversely, the miR-130b inhibitor decreased mRNA levels of MTP and fatty acid synthase ( FAS) in HepG2 cells. However, dual-luciferase reporter assays indicated that MTP is not a direct target of miR-130b-3p. miR-130b overexpression did not alter de novo synthesized TG or the stability and secretion of apolipoprotein B 100. Interestingly, knockdown of phosphatase and tensin homolog ( PTEN) blocked the upregulation of MTP mRNA induced by miR-130b. Finally, miR-130b-induced stimulation of VLDL secretion was also observed in a second hepatocyte cell culture model, immortalized human hepatocytes, confirming the effects observed in HepG2 cells. Overall, these data suggest a potential role for miR-130b in promoting hepatic VLDL assembly and secretion mediated by marked stimulation of MTP expression and TG mobilization. Thus miR-130b overexpression corrects the defect in VLDL production in HepG2 cells.


2015 ◽  
Vol 52 (3) ◽  
pp. 210-215 ◽  
Author(s):  
Lílian BASSANI ◽  
Sabrina Alves FERNANDES ◽  
Fabiana Viegas RAIMUNDO ◽  
Daniele Lazzarotto HARTER ◽  
Maria Cristina GONZALEZ ◽  
...  

BackgroundIn cirrhosis the production of cholesterol and lipoproteins is altered.ObjectiveEvaluate the lipid profile by measuring total cholesterol, very low-density lipoprotein, low-density lipoprotein, high-density lipoprotein and triglyceride levels in patients with cirrhosis caused by alcoholism and/or hepatitis C virus infection and determine its association with Child-Pugh and MELD scores.MethodsCross-sectional retrospective study of patients treated at the outpatient clinic in Porto Alegre, Brazil, from 2006 to 2010.ResultsIn total, 314 records were reviewed, and 153 (48.7%) met the inclusion criteria, of which 82 (53.6%) had cirrhosis that was due to hepatitis C virus infection, 50 (32.7%) were due to alcoholism, and 21 (13.7%) were due to alcoholism and hepatitis C virus infection. The total cholesterol levels diminished with a Child-Pugh progression (P<0.001). Child-Pugh C was significantly associated with lover levels of low-density lipoprotein (<70 mg/dL; P<0.001), high-density lipoprotein (<40 mg/dL; P<0.001) and triglyceride (<70 mg/dL; P=0.003). MELD>20 was associated with lower total cholesterol levels (<100mg/dL; P<0.001), very low-density lipoprotein (<16 mg/dL; P=0.006), and low-density lipoprotein (<70 mg/dL; P=0.003). Inverse and statistically significant correlations were observed between Child-Pugh and all the lipid fractions analyzed (P<0.001). The increase in MELD was inversely correlated with reduced levels intotal cholesterol (P<0.001), high-density lipoprotein (P<0.001), low-density lipoprotein (P<0.001), very low-density lipoprotein (P=0.030) and triglyceride (P=0.003).ConclusionA reduction in the lipid profile in patients with cirrhosis due to hepatitis C virus infection and/or alcoholism was significantly associated with the Child-Pugh and MELD prognostic markers. These results suggest that the lipid profile may be used as a tool to assist in evaluating liver disease.


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