Liver Lipid Content Research Articles

Lonicera Caerulea Juice Alleviates Alcoholic Liver Disease by Regulating Intestinal Flora and the FXR-FGF15 Signaling Pathway.

Alcoholic liver disease (ALD) is a growing public health issue with high financial, social, and medical costs. Lonicera caerulea, which is rich in polyphenolic compounds, has been shown to exert anti-oxidative and anti-inflammatory effects. This study aimed to explore the effects and mechanisms of concentrated Lonicera caerulea juice (LCJ) on ALD in mice. ALD was established in mice via gradient alcohol feeding for 30 days. The mice in the experimental group were given LCJ by gavage. The reduction of aspartate transaminase (AST) and alanine transaminase (ALT) in the serum of mice indicated that LCJ has a liver-protective effect. LCJ improved the expression of AMPK, PPARα, and CPT1b in ALD mice to reduce the liver lipid content. Additionally, LCJ increased the expression of farnesoid X receptor (FXR), fibroblast growth factor 15 (FGF15), and fibroblast growth factor receptor 4 (FGFR4), which lowers the expression of cytochrome P450 7A1 (CYP7A1) and lessens bile acid deposition in the liver. In mice, LCJ improved the intestinal barrier by upregulating the expression of mucins and tight junction proteins in the small intestine. Moreover, it accelerated the restoration of microbial homeostasis in both the large and small intestines and increased short-chain fatty acids in the cecum. In conclusion, LCJ alleviates ALD by reducing liver and serum lipid accumulation and modulating the FXR-FGF15 signaling pathway mediated by gut microbes.

Effect of Sub-Lethal, Carbaryl and Cartap Exposures on Lipid and Cholesterol Contents in Liver, Kidney and Gills of Channa Punctatus (BLOCH)

Channa punctatus were exposed for 24, 48, 72 and 96 h to sub-lethal concentration (30% of LC50 for 96h) of carbaryl and cartap (carbamate pesticides) in order to record their effect on total lipid and cholesterol contents in liver, kidney and gills. The normal lipid content in liver, kidney and gills ranged from 17.95±0.41 to18.21±0.38 mg/g, 15.55i-0.51 to16.21±0.35 mg/g and 8.53±0.39 to 9.58±0.33 mg/g, whereas cholesterol contents varied between 3.60±0.06 to 3.81±0.04 mg/g, 1.61±0.05 to 1.72±0.02 mg/g and 0.71±0.02 to 0.77±0.10 mg/g, respectively. The treatment elicited significant decline in lipid and cholesterol contents throughout the exposure period suggesting response of the fish to the pesticide intoxication.

Replacement of Vitamin E by an Extract from an Olive Oil by-Product, Rich in Hydroxytyrosol, in Broiler Diets: Effects on Liver Traits, Oxidation, Lipid Profile, and Transcriptome.

The study examines the effect of replacing vitamin E (VE) with a liquid obtained from alpeorujo, an olive oil by-product rich in hydroxytyrosol (HT), as an antioxidant in broiler chicken feeds on the gene expression, lipid profile, and oxidation in the liver. There were five diets that differed only in the substitution of supplemental VE (0 to 40 mg/kg with differences of 10 mg/kg) by HT (30 to 0 mg/kg with differences of 7.5 mg/kg). A linear decrease (p < 0.05) in α-tocopherol concentration in the liver was observed with the replacement of VE by HT. There were no significant changes in triglyceride, cholesterol, or TBARS concentrations. The hepatic transcriptome showed 378 differentially expressed genes between broilers fed HT15 (20 mg/kg VE and 15 mg/kg HT) and HT0 (40 mg/kg VE) diets (p < 0.05 and fold change less or higher than 1.3). Significant changes in cell cycle, cell nucleus activity, neuroactivity, and necroptosis pathways and functions were observed. It is concluded that the olive oil by-product, rich in HT, could be used to spare VE as an antioxidant in broiler diets without affecting liver lipid and TBARS concentrations. The differential gene expression analysis showed a potential role of olive polyphenols in enhancing the chicken immune response.

Left ventricular hypertrophy and metabolic resetting in the Notch3-deficient adult mouse heart

The heart depends on a functional vasculature for oxygenation and transport of nutrients, and it is of interest to learn how primary impairment of the vasculature can indirectly affect cardiac function and heart morphology. Notch3-deficiency causes vascular smooth muscle cell (VSMC) loss in the vasculature but the consequences for the heart remain largely elusive. Here, we demonstrate that Notch3-/- mice have enlarged hearts with left ventricular hypertrophy and mild fibrosis. Cardiomyocytes were hypertrophic but not hyperproliferative, and the expression of several cardiomyocyte markers, including Tnt2, Myh6, Myh7 and Actn2, was altered. Furthermore, expression of genes regulating the metabolic status of the heart was affected: both Pdk4 and Cd36 were downregulated, indicating a metabolic switch from fatty acid oxidation to glucose consumption. Notch3-/- mice furthermore showed lower liver lipid content. Notch3 was expressed in heart VSMC and pericytes but not in cardiomyocytes, suggesting that a perturbation of Notch signalling in VSMC and pericytes indirectly impairs the cardiomyocytes. In keeping with this, Pdgfbret/ret mice, characterized by reduced numbers of VSMC and pericytes, showed left ventricular and cardiomyocyte hypertrophy. In conclusion, we demonstrate that reduced Notch3 or PDGFB signalling in vascular mural cells leads to cardiomyocyte dysfunction.

Protective Effects of Gnetin C from Melinjo Seed Extract against High-Fat Diet-Induced Hepatic Steatosis and Liver Fibrosis in NAFLD Mice Model.

Nonalcoholic fatty liver disease (NAFLD), the most common form of chronic liver disease, can progress to hepatic steatosis, inflammation, and advanced fibrosis, increasing the risk of cirrhosis. Resveratrol, a natural polyphenol with antioxidant and anti-inflammatory properties, is beneficial in treating multiple metabolic diseases. Gnetin C, a resveratrol derivative obtained from Melinjo seed extract (MSE), shares similar health-promoting properties. We investigated the role of gnetin C in preventing NAFLD in a mouse model and compared it with resveratrol. Male C57BL/6J mice were fed a control diet (10% calories from fat), a high-fat choline-deficient (HFCD) diet (46% calories from fat) and HFCD diet supplemented with gnetin C (150 mg/kg BW·day-1) or resveratrol (150 mg/kg BW·day-1) for 12 weeks. Gnetin C supplementation reduced body and liver weight, and improved blood glucose levels and insulin sensitivity. Both gnetin C- and resveratrol reduced hepatic steatosis, with gnetin C also decreasing liver lipid content. Gnetin C and resveratrol ameliorated HFCD diet-induced hepatic fibrosis. The mRNA expression results, and western blot analyses showed that gnetin C and, to some extent, resveratrol downregulated fibrosis markers in the TGF-β1 signaling pathway, indicating a possible safeguarding mechanism against NAFLD. These results suggest that gnetin C supplementation may protect against lipid deposition and hepatic fibrosis.

Limited role for hyperammonemia in the progression of diet-induced nonalcoholic steatohepatitis.

To determine whether hyperammonemia has a direct impact on steatohepatitis in mice fed with a high-fat diet (HFD). Male C57BL/6 mice were divided into two groups receiving either chow diet or HFD. After 12-week NASH modeling, hyperammonemia was induced by intragastric administration of ammonium chloride solution (NH4 Cl) or liver-specific carbamoyl phosphate synthetase 1 (Cps1) knockdown. In vitro experiments were performed in HepG2 cells induced by free fatty acid (FFA) and NH4 Cl. NH4 Cl administration led to increased levels of plasma and hepatic ammonia in NASH mice. NH4 Cl-induced hyperammonemia did not influence liver histological changes in mice fed with HFD; however, elevated plasma cholesterol level, and an increasing trend of liver lipid content were observed. No significant effect of hyperammonemia on hepatic inflammation and fibrosis in NASH mice was found. In vitro cell experiments showed that NH4 Cl treatment failed to increase the lipid droplet content and the expressions of de novo lipogenesis genes in HepG2 cells induced by FFA. The knockdown of Cps1 in HFD-fed mice resulted in elevated plasma ammonia levels but did not cause histological change in the liver. Our study revealed a limited role of ammonia in aggravating the progression of NASH. Further studies are needed to clarify the role and mechanism of ammonia in NASH development.

Dietary oleic acid supplementation improves feed efficiency and modulates fatty acid profile and cell signaling pathway in European sea bass (Dicentrarchus labrax) juveniles fed high-lipid diets

Diets with high-lipid levels may reduce fish growth, feed intake and increase fat deposition, jeopardizing fillet quality and shelf-life, which may be of major concern for the final consumer. To mitigate these potentially harmful effects, several nutritional strategies have been applied, including the use of functional ingredients. In this study, European sea bass (initial body weight 21.4 g) were fed six isonitrogenous (45% crude protein) diets with 16% and 22% lipid levels and supplemented with oleic acid (OA) at 0, 1, and 2% as a functional ingredient.Increasing dietary lipid levels did not affect fish growth performance, feed intake, and feed utilization. Independently of lipid level, dietary OA supplementation decreased feed intake and increased feed efficiency and Nitrogen (N) retention (% N Intake). Whole-body composition, hepatosomatic and visceral somatic indexes were not affected by dietary composition. The liver and muscle lipid contents were also not affected by dietary composition.The liver fatty acid profile was not affected by dietary lipid level, but monounsaturated fatty acid (MUFA) content decreased while polyunsaturated fatty acid (PUFA) content decreased with dietary OA supplementation. In the muscle, PUFA content decreased with dietary lipid levels, particularly C18:2n-6 (LA) and C20:2n-6. Dietary OA supplementation increased muscle MUFA, particularly OA (C18:1n-9), and reduced PUFA content. Compared to fish fed with 1OA diets, fish fed with 2OA diets presented a decreased area covered by lipids in the liver.Dietary OA supplementation increased hepatic glucose-6-phosphate dehydrogenase (G6PDH) activity and decreased malic enzyme (ME) activity, while no differences were observed in the activity of fatty acid synthase (FAS) and enzymes related to β-oxidation. Moreover, dietary OA supplementation decreased mechanistic target of rapamycin (mTOR) protein levels, while protein kinase B (Akt) and the phosphorylated state levels of both Akt and mTOR were not affected by dietary composition. Overall, dietary OA supplementation decreased feed intake and improved feed efficiency, without affecting growth performance, contributing to mitigate the potentially harmful effects of high-lipid diets in European sea bass.

1596-P: Homozygous Mutations in MFN2 Aggravated Fat Deposition in Mouse Hepatocytes

Objective: Studies had found that homozygous mutations at p.R707W in the mitofusin-2 (MFN2) gene cause severe lipids metabolic abnormalities, and the mechanism has not been elucidated. In this study, we aim to explore the effect of the mutant protein on hepatocyte lipids deposition. Methods: Primary hepatocytes of wild-type (WT), heterozygous and homozygous mutation were isolated from 8 weeks old mice. Hepatocytes were treated with 600μmol/L free fat acid (FFA) of oleic acid/palmitic acid (2︰1) mixture for 12 hours to establish a NAFLD model in vitro. The lipid accumulation of hepatocytes was observed by Oil red O staining and the contents of triglyceride (TG). Results: Mutant mice carrying a novel p.R707W (CGA to TGG) mutation and silent mutation (p.D708=(GAT to GAC)) were identified (Fig. 1A). The results of Oil Red O staining and TG content measurement before FFA treating showed that more lipid was deposited in the homozygous hepatocyte than in WT cells (Fig. 1B, Fig. 1C) (*P&amp;lt;0.05), revealing that different genotypes of mice already have varied liver lipid contents at 8 weeks. After stimulation with FFA, TG content and lipidosis area in homozygous hepatocytes were significantly higher than those in WT (**P&amp;lt;0.01). And there was no significant difference between heterozygote and WT hepatocytes with or without FFA stimulation. Conclusion: Homozygous mutation at p.R707W in MFN2 aggravated lipid deposition in mouse. Disclosure Y.Yu: None. Y.Luo: None. X.Zhou: None. L.Ji: Other Relationship; Eli Lilly and Company, Novo Nordisk, Merck &amp; Co., Inc., Bayer Inc., Sanofi-Aventis U.S., Roche Pharmaceuticals, MSD Life Science Foundation, AstraZeneca, Boehringer Ingelheim Inc., Abbott, Metronics. Funding China International Medical Foundation (2021-N-03)

Low-carbohydrate diet in the treatment of type 2 diabetes mellitus (LoCaT): study protocol for a multicenter, randomized controlled trial

BackgroundLow-carbohydrate diet (LCD) is an emerging therapy for type 2 diabetes mellitus (T2DM). Although its effect on glucose control has been confirmed in previous clinical trials, most of those studies have focused on comparing calorie-restricted LCD to iso-caloric low-fat diets. In this study, we aim to compare the effects of LCD and canagliflozin, a sodium-glucose cotransporter 2 inhibitor, in patients with T2DM.MethodsThis is a multicenter, randomized controlled trial. We will recruit 120 patients with poor-controlled T2DM. Participants will be randomly divided into canagliflozin and LCD groups in a 1:1 ratio. The primary outcome is the change in hemoglobin A1C levels after the 3-month intervention. The secondary outcomes are the time in range and cost of antihyperglycemic agents. Exploratory outcomes include physical examination, body composition, glucose variability, appetite, glycolipid metabolism, liver lipid content, and urine glucose threshold.DiscussionNo previous study has compared an LCD with antihyperglycemic agents. In LoCaT, participants’ metabolism will be assessed from multiple perspectives. It is believed that the finding obtained from this trial will optimize the treatments for patients with T2DM.Trial registrationChinese Clinical Trial Registry ChiCTR1900027592. Registered on November 20, 2019.

Digestible protein levels and metabolic responses in juvenile piapara (Megaleporinus obtusidens)

The piapara (Megaleporinus obtusidens) is an omnivorous fish with great market potential. However, little is known about its dietary requirements. This study aimed to determine the effects of dietary protein on growth and physiological indicators in piapara. Three hundred piapara juveniles (24.0 ± 1.3 g) were distributed in 20 tanks of 130-L (15 fish/tank) provided with continuous aeration and water. Five isoenergetic diets (14.0 MJ/kg) were formulated to contain increasing levels of digestible protein (21, 24, 27, 30, and 33% DP). After 77 days, weight gain and ammonia concentration in water were found to increase linearly with increasing digestible protein (DP) level (p&lt;0.05). Protein productive value (PPV) reached a maximum at 28.4% DP. No relationship was found between DP level and serum ammonia, liver alanine aminotransferase (ALT) activity, hepatosomatic index (HSI), liver glycogen (GL) or liver lipid (LL) content (p&gt;0.05). Mesenteric fat index (MFI) and liver malic enzyme (ME) activity followed a quadratic pattern (p&lt;0.05) and reached a maximum at 25.8% and 27.1% DP, respectively. Muscle lipid (ML) content decreased linearly with increasing DP level (p&lt;0.05), whereas liver glucose-6-phosphate dehydrogenase (G6PD) activity decreased linearly as DP level increased (p&lt;0.05). Results showed that a diet containing 28.4% PD provides better crude protein retention efficiency and reduces amino acid deamination in M. obtusidens. Low protein diets increased energy retention efficiency, whereas fish fed high protein diets had higher ammonia excretion.

Effects of defatted yellow mealworm (Tenebrio molitor) on growth performance, intestine, and liver health of turbot (Scophthalmus maximus)

Yellow mealworm Tenebrio molitor is an emerging feed ingredient with several key advantages. However, research on the T. molitor as a fishmeal substitute reported discrepancies in feasibility in different fish species, with a particular need for T. molitor products to be widely evaluated. In this research, an eight-week feeding trial was conducted to evaluate the effect of T. molitor on turbot Scophthalmus maximus mainly from the perspective of growth performance and health status of the intestine and liver. Turbot with an initial weight of approximately 150 g were randomly assigned six isonitrogenous and isolipidic diets, including fishmeal-based control diet or diets with gradually increasing level of defatted T. molitor meal (TM) to replace 15 % (TM15), 30 %, 45 %, 60 % and 75 % of fishmeal compared to the control diet. Weight gain of turbot increased significantly at the 30 % replacement level (P < 0.05). However, TM in 45 %, 60 % and 75 % of fishmeal replacement level impaired overall growth performance. There was no obvious impairment in the assayed levels of TM towards the intestine from the view of structure, activities of brush border enzymes, antioxidant conditions, or immunity of proximal, middle and distal segments. However, the amount of goblet cells was significantly decreased by TM (P < 0.05). Similarly, TM in the assayed levels did not induce any negative effects on the antioxidant and immune status of the liver. But TM45, TM60 and TM75 diets induced weight loss in the liver and smaller hepatocytes, accompanied by a decrease of liver lipid content as well as decreases in levels of triglyceride and cholesterol in plasma. In conclusion, the optimal dietary level of TM for turbot was 24.5 %, corresponding to a 30 % substitution of fishmeal from the control group. Dietary TM can improve the antioxidant and immune function of the intestine and liver, but excess TM will disturb lipid metabolisms.

Detection and Quantification of Some Ethanol-Producing Bacterial Strains in the Gut of Mouse Model of Non-Alcoholic Fatty Liver Disease: Role of Metformin.

Ethanol-producing dysbiotic gut microbiota could accelerate the progress of non-alcoholic fatty liver disease (NAFLD). Metformin demonstrated some benefits in NAFLD. In the present study, we tested the ability of metformin to modify ethanol-producing gut bacterial strains and, consequently, retard the progress of NAFLD. This 12-week study included forty mice divided into four groups (n = 10); normal diet, Western diet, Western diet with intraperitoneal metformin, and Western diet with oral metformin. Oral metformin has a slight advantage over intraperitoneal metformin in ameliorating the Western diet-induced changes in liver function tests and serum levels of different cytokines (IL-1β, IL-6, IL-17, and TNF-α). Changes in liver histology, fibrosis, lipid content, Ki67, and TNF-α were all corrected as well. Faecal ethanol contents were increased by the Western diet but did not improve after treatment with metformin although the numbers of ethanol-producing Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli) were decreased by oral metformin. Metformin did not affect bacterial ethanol production. It does not seem that modification of ethanol-producing K. pneumoniae and E. coli bacterial strains by metformin could have a significant impact on the therapeutic potentials of metformin in this experimental model of NAFLD.

Essential fatty acid requirement of juvenile meagre (Argyrosomus regius)

Meagre (Argyrosomus regius) is a fast-growing marine teleost and a promising candidate for the diversification of the Mediterranean aquaculture industry. Information on specific dietary requirements is necessary to improve the competitiveness of meagre farming. While the essential fatty acids (EFA) requirement of meagre fingerlings was previously estimated, knowledge regarding the EFA requirement of on-growing meagre juveniles is still lacking. To assess the EFA requirement of juvenile meagre, six isolipidic, isoproteic, semi-purified diets with different levels of n-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) contents 0.0%, 0.3%, 0.6%, 0.9%, 1.2%, and 1.5% of diet dry matter (DM) were formulated and fed three times daily to triplicate groups of juvenile meagres of 35.6 ± 0.3 g for twelve weeks. Growth rates, whole body composition and fatty acid profile, liver lipid content as well as fatty acid profiles were assessed. In addition, the incidence of hepatic steatosis and granulomatosis was evaluated. Juvenile meagre fed the 0.0% n-3 LC-PUFA diet showed significantly lower growth and final body weight compared to all other treatments. There was an increase in growth of meagre with increasing dietary n-3 LC-PUFA levels and weight gain plateaued at levels above 0.9% n-3 LC-PUFA. Occurrence of granulomas examined in the liver supported the data on growth as the hepatic granulomatosis incidence in the groups fed <0.9% n-3 LC-PUFA were greater compared to fish fed diets containing higher levels of n-3 LC-PUFA. The findings of this study showed that the dietary n-3 LC-PUFA requirement of juvenile meagre for optimal growth and liver health status lays between 0.7 and 0.8% of the dietary dry matter.

PNPLA3 rs738409 risk genotype decouples TyG index from HOMA2-IR and intrahepatic lipid content

BackgroundRecent reports suggested a different predictive value for TyG index compared to HOMA-IR in coronary artery calcification (CAC) and other atherosclerotic outcomes, despite that both indices are proposed as surrogate markers of insulin resistance. We hypothesized a key role for liver pathology as an explanation and therefore assessed the relationship among the two indices and the intrahepatic lipid content stratified by PNPLA3 rs738409 genotypes as a known non-alcoholic fatty liver disease (NAFLD) genetic risk.MethodsThirty-nine women from a prior GDM-genetic study were recalled with PNPLA3 rs738409 CC and GG genotypes for metabolic phenotyping and to assess hepatic triglyceride content (HTGC). 75 g OGTT was performed, fasting lipid, glucose, insulin levels and calculated insulin resistance indices (TyG and HOMA2-IR) were used. HTGC was measured by MR based methods. Mann–Whitney-U, χ2 and for the correlation analysis Spearman rank order tests were applied.ResultsThe PNPLA3 rs738409 genotype had a significant effect on the direct correlation between the HOMA2-IR and TyG index: the correlation (R = 0.52, p = 0.0054) found in the CC group was completely abolished in those with the GG (NAFLD) risk genotype. In addition, the HOMA2-IR correlated with HTGC in the entire study population (R = 0.69, p < 0.0001) and also separately in both genotypes (CC R = 0.62, p = 0.0006, GG: R = 0.74, p = 0.0058). In contrast, the correlation between TyG index and HTGC was only significant in rs738409 CC genotype group (R = 0.42, p = 0.0284) but not in GG group. A similar pattern was observed in the correlation between TG and HTGC (CC: R = 0.41, p = 0.0335), when the components of the TyG index were separately assessed.ConclusionsPNPLA3 rs738409 risk genotype completely decoupled the direct correlation between two surrogate markers of insulin resistance: TyG and HOMA2-IR confirming our hypothesis. The liver lipid content increased in parallel with the HOMA2-IR independent of genotype, in contrast to the TyG index where the risk genotype abolished the correlation. This phenomenon seems to be related to the nature of hepatic fat accumulation and to the different concepts establishing the two insulin resistance markers.

Dietary docosahexaenoic acid reduces fat deposition and alleviates liver damage induced by D-galactosamine and lipopolysaccharides in Nile tilapia (Oreochromis niloticus)

Liver health is important to maintain survival and growth of fish. Currently, the role of dietary docosahexaenoic acid (DHA) in improving fish liver health is largely unknown. This study investigated the role of DHA supplementation in fat deposition and liver damage caused by D-galactosamine (D-GalN) and lipopolysaccharides (LPS) in Nile tilapia (Oreochromis niloticus). Four diets were formulated as control diet (Con), Con supplemented with 1 % DHA, 2 % DHA and 4 % DHA diets, respectively. The diets were fed to 25 Nile tilapia (2.0 ± 0.1 g, average initial weight) in triplicates for four weeks. After the four weeks, 20 fish in each treatment were randomly selected and injected with a mixture of 500 mg D-GalN and 10 μL LPS per mL to induce acute liver injury. The results showed that the Nile tilapia fed on DHA diets decreased visceral somatic index, liver lipid content and serum and liver triglyceride concentrations than those fed on the Con diet. Moreover, after D-GalN/LPS injection, the fish fed on DHA diets decreased alanine aminotransferase and aspartate transaminase activities in the serum. The results of liver qPCR and transcriptomics assays together showed that the DHA diets feeding improved liver health by downregulating the expression of the genes related to toll-like receptor 4 (TLR4) signaling pathway, inflammation and apoptosis. This study indicates that DHA supplementation in Nile tilapia alleviates the liver damage caused by D-GalN/LPS through increasing lipid catabolism, decreasing lipogenesis, TLR4 signaling pathway, inflammation, and apoptosis. Our study provides novel knowledge on the role of DHA in improving liver health in cultured aquatic animals for sustainable aquaculture.

Effects of dietary arachidonic acid supplementation in high plant protein diets on growth, feed utilization, and immunity of olive flounder, Paralichthys olivaceus

This study was designed to evaluate the effects of graded levels of arachidonic acid (ARA) in low fish meal diets (30% fish meal, 30% plant protein blends) on growth, feed utilization, and immunity of olive flounder (Paralichthys olivaceus). The control diet was formulated with 3% fish oil and 5.1% soybean oil (ARA0.0). Five other diets were formulated incorporating different levels of ARA into the ARA0.0 diet at the expense of soybean oil; that is, 0.3, 0.6, 0.9, 1.2, and 1.5% ARA (ARA0.3, ARA0.6, ARA0.9, ARA1.2, and ARA1.5), respectively. Three replicate groups of fish (88.24 ± 0.06 g) were placed into 18 polyvinyl circular tanks (215 L), with 24 fish each and fed an experimental diet twice a day for nine weeks. Overall, significantly improved growth performance was observed in the ARA0.6 group. Liver C18:2n-6 was significantly reduced, and liver ARA content was significantly increased with the increase in dietary ARA levels. Nitroblue tetrazolium activity was significantly higher in the ARA0.6 group, and significantly higher superoxide dismutase and myeloperoxidase activities were observed in the ARA0.9 group. Further, immunoglobulin level and lysozyme activity were significantly improved in the ARA0.3 group, antiprotease activity was increased in the ARA0.6 and ARA0.9 groups, and the ARA0.3 group showed lower liver lipid content than the ARA0.0 group. Serum prostaglandin E2 level was significantly increased with 1.5% ARA inclusion. Pro-inflammatory gene expressions of interleukin (IL)-6, IL-8, IL-10, perforin, and tumor necrosis factor in the intestine were significantly downregulated, and anti-inflammatory gene expression of transforming growth factor-β2 gene expression was significantly upregulated with higher dietary ARA supplementation (0.9–1.5%). These results indicate that 0.3–0.9% supplemented ARA may improve the growth, immune, and hematological parameters of olive flounder.

Dietary Monounsaturated and Polyunsaturated Fatty Acids are Comparable in their Effects on Hepatic Apolipoprotein mRNA Abundance and Liver Lipid Concentrations when Substituted for Saturated Fatty Acids in Cynomolgus Monkeys

Although studies have shown that saturated and polyunsaturated fats can mediate plasma lipid and apolipoprotein (apo) concentrations at the mRNA level, there is little data on the role of monounsaturated fats. We determined hepatic lipid and apo mRNA levels in 10 cynomolgus monkeys fed three diets that provided 30% of energy as fat with 0.1% cholesterol by weight and differed solely by the substitution of saturated, mono- and polyunsaturated fats as 60% of total fat energy. Total, LDL, and HDL cholesterol, as well as LDL apo B, HDL apo A-I and HDL total apo C concentrations, were reduced with the mono- and polyunsaturated fat diets relative to the saturated fat diet. Although fat saturation did not significantly affect hepatic apo A-I, B, C-II, or E mRNA abundance, hepatic apo C-III mRNA concentrations were uniformly lower (-23%, P < 0.01) with the mono- and polyunsaturated fat diets than with the saturated fat diet. Interestingly, liver triglycerides were significantly elevated with the monounsaturated fat diet relative to the saturated fat diet, but no other differences in hepatic lipids were noted among diets. Hepatic triglyceride composition was shown to reflect dietary fatty acid composition, with liver triglycerides enriched in myristic and palmitic fatty acids during the saturated fat diet, oleic acid during the monounsaturated fat diet and linoleic acid during the polyunsaturated fat diet. We conclude that dietary monounsaturated fats are comparable to polyunsaturated fats in their effects on hepatic lipid and apo mRNA levels in this species, with both unsaturated fats significantly reducing only hepatic apo C-III mRNA abundance relative to saturated fat.

A New In Vivo Zebrafish Bioassay Evaluating Liver Steatosis Identifies DDE as a Steatogenic Endocrine Disruptor, Partly through SCD1 Regulation.

Non-alcoholic fatty liver disease (NAFLD), which starts with liver steatosis, is a growing worldwide epidemic responsible for chronic liver diseases. Among its risk factors, exposure to environmental contaminants, such as endocrine disrupting compounds (EDC), has been recently emphasized. Given this important public health concern, regulation agencies need novel simple and fast biological tests to evaluate chemical risks. In this context, we developed a new in vivo bioassay called StAZ (Steatogenic Assay on Zebrafish) using an alternative model to animal experimentation, the zebrafish larva, to screen EDCs for their steatogenic properties. Taking advantage of the transparency of zebrafish larvae, we established a method based on fluorescent staining with Nile red to estimate liver lipid content. Following testing of known steatogenic molecules, 10 EDCs suspected to induce metabolic disorders were screened and DDE, the main metabolite of the insecticide DDT, was identified as a potent inducer of steatosis. To confirm this and optimize the assay, we used it in a transgenic zebrafish line expressing a blue fluorescent liver protein reporter. To obtain insight into DDE's effect, the expression of several genes related to steatosis was analyzed; an up-regulation of scd1 expression, probably relying on PXR activation, was found, partly responsible for both membrane remodeling and steatosis.

Tcf7l2 in hepatocytes regulates de novo lipogenesis in diet-induced non-alcoholic fatty liver disease in mice

Aims/hypothesisNon-alcoholic fatty liver disease (NAFLD) associated with type 2 diabetes may more easily progress towards severe forms of non-alcoholic steatohepatitis (NASH) and cirrhosis. Although the Wnt effector transcription factor 7-like 2 (TCF7L2) is closely associated with type 2 diabetes risk, the role of TCF7L2 in NAFLD development remains unclear. Here, we investigated how changes in TCF7L2 expression in the liver affects hepatic lipid metabolism based on the major risk factors of NAFLD development.MethodsTcf7l2 was selectively ablated in the liver of C57BL/6N mice by inducing the albumin (Alb) promoter to recombine Tcf7l2 alleles floxed at exon 5 (liver-specific Tcf7l2-knockout [KO] mice: Alb-Cre;Tcf7l2f/f). Alb-Cre;Tcf7l2f/f and their wild-type (Tcf7l2f/f) littermates were fed a high-fat diet (HFD) or a high-carbohydrate diet (HCD) for 22 weeks to reproduce NAFLD/NASH. Mice were refed a standard chow diet or an HCD to stimulate de novo lipogenesis (DNL) or fed an HFD to provide exogenous fatty acids. We analysed glucose and insulin sensitivity, metabolic respiration, mRNA expression profiles, hepatic triglyceride (TG), hepatic DNL, selected hepatic metabolites, selected plasma metabolites and liver histology.ResultsAlb-Cre;Tcf7l2f/f essentially exhibited increased lipogenic genes, but there were no changes in hepatic lipid content in mice fed a normal chow diet. However, following 22 weeks of diet-induced NAFLD/NASH conditions, liver steatosis was exacerbated owing to preferential metabolism of carbohydrate over fat. Indeed, hepatic Tcf7l2 deficiency enhanced liver lipid content in a manner that was dependent on the duration and amount of exposure to carbohydrates, owing to cell-autonomous increases in hepatic DNL. Mechanistically, TCF7L2 regulated the transcriptional activity of Mlxipl (also known as ChREBP) by modulating O-GlcNAcylation and protein content of carbohydrate response element binding protein (ChREBP), and targeted Srebf1 (also called SREBP1) via miRNA (miR)-33-5p in hepatocytes. Eventually, restoring TCF7L2 expression at the physiological level in the liver of Alb-Cre;Tcf7l2f/f mice alleviated liver steatosis without altering body composition under both acute and chronic HCD conditions.Conclusions/interpretationIn mice, loss of hepatic Tcf7l2 contributes to liver steatosis by inducing preferential metabolism of carbohydrates via DNL activation. Therefore, TCF7L2 could be a promising regulator of the NAFLD associated with high-carbohydrate diets and diabetes since TCF7L2 deficiency may lead to development of NAFLD by promoting utilisation of excess glucose pools through activating DNL.Data availabilityRNA-sequencing data have been deposited into the NCBI GEO under the accession number GSE162449 (www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE162449).Graphical abstract

Paradoxical reduction of plasma lipids and atherosclerosis in mice with adenine-induced chronic kidney disease and hypercholesterolemia.

Atherosclerotic cardiovascular disease is prevalent among patients with chronic kidney disease (CKD). In this study, we initially aimed to test whether vascular calcification associated with CKD can worsen atherosclerosis. However, a paradoxical finding emerged from attempting to test this hypothesis in a mouse model of adenine-induced CKD. We combined adenine-induced CKD and diet-induced atherosclerosis in mice with a mutation in the low-density lipoprotein receptor gene. In the first study, mice were co-treated with 0.2% adenine in a western diet for 8 weeks to induce CKD and atherosclerosis simultaneously. In the second study, mice were pre-treated with adenine in a regular diet for 8 weeks, followed by a western diet for another 8 weeks. Co-treatment with adenine and a western diet resulted in a reduction of plasma triglycerides and cholesterol, liver lipid contents, and atherosclerosis in co-treated mice when compared with the western-only group, despite a fully penetrant CKD phenotype developed in response to adenine. In the two-step model, renal tubulointerstitial damage and polyuria persisted after the discontinuation of adenine in the adenine-pre-treated mice. The mice, however, had similar plasma triglycerides, cholesterol, liver lipid contents, and aortic root atherosclerosis after being fed a western diet, irrespective of adenine pre-treatment. Unexpectedly, adenine pre-treated mice consumed twice the calories from the diet as those not pre-treated without showing an increase in body weight. The adenine-induced CKD model does not recapitulate accelerated atherosclerosis, limiting its use in pre-clinical studies. The results indicate that excessive adenine intake impacts lipid metabolism.