High Protein/Fish Oil Diet Prevents Hepatic Steatosis in NONcNZO10 Mice; Association with Diet/Genetics-regulated Micro-RNAs

Abstract

Objective NONcNZO10 (NZ10) mice are predisposed to obesity and develop type 2 diabetes (T2D) and hepatic steatosis even when maintained on a control diet (CD) of 6% fat. Studies were designed to determine whether this extreme susceptibility phenotype could be alleviated by diet and if so the molecular targets of diet. Methods NZ10 and SWR/J (SWR) control mice were fed a CD or a test diet of high protein and fish oil (HPO) for 19 weeks and then analyzed for steatosis, blood chemistry, hepatic gene and micro-RNA expression. Results HPO diet prevented steatosis, significantly increased serum adiponectin and reduced serum cholesterol and triglycerides only in NZ10 mice. The HPO diet repressed hepatic expression of fatty acid metabolic regulators including PPAR-γ, sterol regulatory element-binding protein-c1, peroxisome proliferator-activated receptor gamma co-activator-1, fatty acid synthase, fatty acid binding protein-4, and apolipoprotein A4 genes only in NZ10 mice. Also repressed by a HPO diet were adiponectinR2 receptor, leptin-R, PPAR-α, pyruvate dehydrogenase kinase isoforms 2 and 4, AKT2 and GSK3β. Micro-RNA (miR) arrays identified miRs that were diet and/or genetics regulated. QRTPCR confirmed increased expression of miR-205 and suppression of a series of miRs including miRs-411, 155, 335 and 21 in the NZ10-HPO group, each of which are implicated in the progression of diabetes and/or steatosis. Evidence is presented that miR-205 co-regulates with PPARγ and may regulate fibrosis and EMT during the progression of steatosis in the livers of NZ10-CD mice. The dietary responses of miR-205 are tissue-specific with opposite effects in adipose and liver. Conclusion The results confirm that a HPO diet overrides the genetic susceptibility of NZ10 mice and this correlates with the suppression of key genes and perhaps micro-RNAs involved in hyperglycemia, dyslipidemia and inflammation including master PPAR regulators, adiponectin and leptin receptors.

A Hypocaloric High-Protein Diet Supplemented with β-Cryptoxanthin Improves Non-Alcoholic fatty liver disease: A randomized controlled trial

“…Furthermore, our observations are in accordance with a substantial body of evidence from experimental animal research suggesting that HP-diets with or without calorie restriction signi cantly improve hepatic steatosis in animal models of NAFLD [13][14][15][16][17][18]23]. Moreover, results of the present study are supported by those from a couple of experimental works in animals indicating that administration of a normocaloric diet with 0.003% β-cryptoxanthin to mice with diet-induced non-alcoholic steatohepatitis for 12 weeks leads to signi cant improvement of hepatic steatosis and circulating liver aminotransferase levels [24,25].…”

“…In this respect, the potential bene cial effects of high dietary intakes of protein and carotenoids, particularly β-cryptoxanthin (i.e., a major dietary provitamin A carotenoid largely found in citrus fruits and relatively abundant in human blood and tissues), on NAFLD has recently received lots of attention [10,12]. In fact, the role of high protein (HP)-diets in improvement of liver enzymes and hepatic steatosis in NAFLD is supported by substantial animal data and a few quasi-experimental studies in humans [13][14][15][16][17][18][19][20][21][22][23]. Similarly, ndings of a couple of experimental works in animals suggest that β-cryptoxanthin plays a preventive and even therapeutic role against NAFLD [24,25].…”

A hypocaloric high-protein diet supplemented with β-cryptoxanthin improves non-alcoholic fatty liver disease: a randomized controlled trial

“…However, greater improvements in NAFLD in the HP-diet and β-cryptoxanthin group as compared to the control group in this study is in line with findings of a few quasi-experimental studies in humans indicating that the prescription of a hypocaloric HP-diet (providing 35-47% of daily energy intake as protein) for 2-11 weeks in NAFLD patients significantly reduces hepatic fat concentration and/or circulating liver enzyme levels [21][22][23][24]. Furthermore, our observations are in accordance with a substantial body of evidence from experimental animal research suggesting that HP-diets with or without calorie restriction significantly improve hepatic steatosis in animal models of NAFLD [15][16][17][18][19][20]25]. Moreover, results of the present study are supported by those from a couple of experimental works in animals indicating that administration of a normocaloric diet with 0.003% β-cryptoxanthin to mice with diet-induced non-alcoholic steatohepatitis for 12 weeks leads to significant improvement of hepatic steatosis and circulating liver aminotransferase levels [26,27].…”

“…In this respect, the potential beneficial effects of high dietary intakes of protein and carotenoids, particularly β-cryptoxanthin (i.e., a major dietary provitamin A carotenoid largely found in citrus fruits and relatively abundant in human blood and tissues), on NAFLD has recently received lots of attention [12,14]. In fact, the role of high protein (HP)diets in improvement of liver enzymes and hepatic steatosis in NAFLD is supported by substantial animal data and a few quasi-experimental studies in humans [15][16][17][18][19][20][21][22][23][24][25]. Similarly, findings of a couple of experimental works in animals suggest that β-cryptoxanthin plays a preventive and even therapeutic role against NAFLD [26,27].…”

The Interplay Between Diet and the Epigenome in the Pathogenesis of Type-1 Diabetes

“…Another study showed enhanced expression of miR-122 accompanied with downregulation of insulin-like growth factor 1 receptor (IGF-1R) in the liver of diabetic rats given high fat diet ( 93 ). Furthermore, in mice susceptible of developing obesity and diabetes, a diet rich with protein and fish oil has been found to override this genetic susceptibility ( 94 ). It has been shown that certain miRNAs (miRs-411, 155, 335, and 21) involved in inflammation, dyslipidemia, and hyperglycemia were downregulated in mice fed with high protein and fish oil diet ( 94 ).…”