Identification of alternative splicing events related to fatty liver formation in duck using full-length transcripts.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is one of most common diseases in the world. Recently, alternative splicing (AS) has been reported to play a key role in NAFLD processes in mammals. Ducks can quickly form fatty liver similar to human NAFLD after overfeeding and restore to normal liver in a short time, suggesting that ducks are an excellent model to unravel molecular mechanisms of lipid metabolism for NAFLD. However, how alternative splicing events (ASEs) affect the fatty liver process in ducks is still unclear. RESULTS: Here we identify 126,277 unique transcripts in liver tissue from an overfed duck (77,237 total transcripts) and its sibling control (69,618 total transcripts). We combined these full-length transcripts with Illumina RNA-seq data from five pairs of overfed ducks and control individuals. Full-length transcript sequencing provided us with structural information of transcripts and Illumina RNA-seq data reveals the expressional profile of each transcript. We found, among these unique transcripts, 30,618 were lncRNAs and 1,744 transcripts including 155 lncRNAs and 1,589 coding transcripts showed significantly differential expression in liver tissues between overfed ducks and control individuals. We also detected 27,317 ASEs and 142 of them showed significant relative abundance changes in ducks under different feeding conditions. Full-length transcript profiles together with Illumina RNA-seq data demonstrated that 10 genes involving in lipid metabolism had ASEs with significantly differential abundance in normally fed (control) and overfed ducks. Among these genes, protein products of five genes (CYP4F22, BTN, GSTA2, ADH5, and DHRS2 genes) were changed by ASEs. CONCLUSIONS: This study presents an example of how to identify ASEs related to important biological processes, such as fatty liver formation, using full-length transcripts alongside Illumina RNA-seq data. Based on these data, we screened out ASEs of lipid-metabolism related genes which might respond to overfeeding. Our future ability to explore the function of genes showing AS differences between overfed ducks and their sibling controls, using genetic manipulations and co-evolutionary studies, will certainly extend our knowledge of genes related to the non-pathogenic fatty liver process.

High-protein compound yogurt with quinoa improved clinical features and metabolism of high-fat diet-induced nonalcoholic fatty liver disease in mice.

Gut microbiota dysbiosis plays a crucial role in the occurrence and progression of nonalcoholic fatty liver disease (NAFLD), which may be influenced by nutritional supplementation. Quinoa, a type of pseudocereal, has gained prominence due to its high nutritional value and diverse applications. This study aimed to determine whether yogurt containing quinoa can ameliorate NAFLD and alleviate metabolic disorders by protecting against the divergence of gut microbiota. Our findings suggested that quinoa yogurt could significantly reduce the body weight gain and fat tissue weight of high-fat diet (HFD)-fed obese mice. In addition, quinoa yogurt significantly reduced liver steatosis and enhanced glucose homeostasis and insulin sensitivity. Additional research indicates that quinoa yogurt can reduce the levels of proinflammatory cytokines (i.e., tumor necrosis factor α, IL-1ß, and IL-6) and inhibit endotoxemia and systemic inflammation. The characteristics of the gut microbiota were then determined by analyzing 16S rRNA. In addition, we discovered that the gut microbiota was disturbed by HFD consumption. Particularly, intestinal probiotics and beneficial intestinal secretions were increased, leading to the expression of glucagon-like peptide-1 in the colon, contributing to NAFLD. Furthermore, endotoxemia and systemic inflammation in HFD-fed mice were restored to the level of control mice when they were fed yogurt and quinoa. Therefore, yogurt containing quinoa can effectively alleviate NAFLD symptoms and may exert its effects via microbiome-gut-liver axis mechanisms. According to some research, the role of the enteric-liver axis may also influence metabolic disorders to reduce the development of NAFLD.

Tandem mass tag-based quantitative proteomics analysis reveals the effects of the α-lactalbumin peptides GINY and DQW on lipid deposition and oxidative stress in HepG2 cells.

The objective of this study was to investigate the mechanism by which the α-lactalbumin peptides Gly-Ile-Asn-Tyr (GINY) and Asp-Gln-Trp (DQW) ameliorate free fatty acid-induced lipid deposition in HepG2 cells. The results show that GINY and DQW reduced triglyceride, total cholesterol, and free fatty acid levels significantly in free fatty acid-treated HepG2 cells. Based on proteomic analysis, GINY and DQW alleviated lipid deposition and oxidative stress mainly through the peroxisome proliferator-activated receptor (PPAR) pathway, fatty acid metabolism, oxidative phosphorylation, and response to oxidative stress. In vitro experiments confirmed that GINY and DQW upregulated the mRNA and protein expression of fatty acid ß-oxidation-related and oxidative stress-related genes, and downregulated the mRNA and protein expression of lipogenesis-related genes by activating peroxisome proliferator-activated receptor α (PPARα). Meanwhile, GINY and DQW reduced free fatty acid-induced lipid droplet accumulation and reactive oxygen species generation, and enhanced the mitochondrial membrane potential and ATP levels. Furthermore, GINY and DQW enhanced carnitine palmitoyl-transferase 1a (CPT-1a) and superoxide dismutase activities, and diminished acetyl-coenzyme A carboxylase 1 (ACC1) and fatty acid synthase (FASN) activities in a PPARα-dependent manner. Interestingly, GW6471 (a PPARα inhibitor) weakened the effects of GINY and DQW on the PPARα pathway. Hence, our findings suggest that GINY and DQW have the potential to alleviate nonalcoholic fatty liver disease by activating the PPARα pathway.

Beneficial effects of Lactobacillus rhamnosus hsryfm 1301 fermented milk on rats with nonalcoholic fatty liver disease.

A growing stream of research suggests that probiotic fermented milk has a good effect on nonalcoholic fatty liver disease. This work aimed to study the beneficial effects of Lactobacillus rhamnosus hsryfm 1301 fermented milk (fermented milk) on rats with nonalcoholic fatty liver disease induced by a high-fat diet. The results showed that the body weight and the serum levels of total cholesterol, total glyceride, low-density lipoprotein, alanine transaminase, aspartate aminotransferase, free fatty acid, and reactive oxygen species were significantly increased in rats fed a high-fat diet (M) for 8 wk, whereas high-density lipoprotein cholesterol and superoxide dismutase were significantly decreased. However, the body weight and the serum levels of total cholesterol, total glyceride, alanine transaminase, aspartate aminotransferase, free fatty acid, reactive oxygen species, interleukin-8, tumor necrosis factor-α, and interleukin-6 were significantly decreased with fermented milk (T) for 8 wk, and the number of fat vacuoles in hepatocytes was lower than that in the M group. There were significant differences in 19 metabolites in serum between the M group and the C group (administration of nonfermented milk) and in 17 metabolites between the T group and the M group. The contents of 7 different metabolites, glycine, glycerophosphocholine, 1,2-dioleoyl-sn-glycero-3-phosphocholine, thioetheramide-PC, d-aspartic acid, oleic acid, and l-glutamate, were significantly increased in the M group rat serum, and l-palmitoyl carnitine, N6-methyl-l-lysine, thymine, and 2-oxadipic acid were significantly decreased. In the T group rat serum, the contents of 8 different metabolites-1-O-(cis-9-octadecenyl)-2-O-acetyl-sn-glycero-3-phosphocholine, acetylcarnitine, glycine, glycerophosphocholine, 1,2-dioleoyl-sn-glycero-3-phosphocholine, d-aspartic acid, oleic acid, and l-glutamate were significantly decreased, whereas creatinine and thymine were significantly increased. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that 50 metabolic pathways were enriched in the M/C group and T/M group rat serum, of which 12 metabolic pathways were significantly different, mainly distributed in lipid metabolism, amino acid, and endocrine system metabolic pathways. Fermented milk ameliorated inflammation, oxygenation, and hepatocyte injury by regulating lipid metabolism, amino acid metabolic pathways, and related metabolites in the serum of rats with nonalcoholic fatty liver disease.

Polysaccharide extract from pomelo fruitlet ameliorates diet-induced nonalcoholic fatty liver disease in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀).

Nonalcoholic fatty liver disease (NAFLD) is common in farmed fish fed a high-fat diet (HFD), which disrupts lipid metabolism, inhibits growth performance, and poses a serious threat to sustainable aquaculture. This study explored the anti-NAFLD effect and hepatoprotective mechanism of YZW-A, a water-soluble heteroglycan extracted from the pomelo fruitlet (Citrus maxima), in hybrid grouper (Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus♀). Hybrid grouper were fed an HFD, with 15% lipid, supplemented with YZW-A for 56 days. In vivo, addition of YZW-A resulted in improved growth performance and feed utilization, while it reduced whole body and muscle lipid content, viscerosomatic and hepatosomatic indexes, and lipid deposition in the hepatocytes. Lipogenesis-related genes were downregulated while lipolysis-related genes were upregulated in grouper supplemented with YZW-A. Additionally, destructive morphological changes in the liver tissue cells detected in HFD-fed grouper were normalized after treatment with YZW-A. In vitro, YZW-A improved lipid emulsion-induced hepatic steatosis by modulating key factors of lipid metabolism, achieved by triggering the AMP-activated protein kinase (AMPK) pathway in the hepatocytes and activating the AMPK/Nrf2/ARE axis. These results demonstrated the therapeutic effect of YZW-A on diet-induced NAFLD in hybrid grouper and elucidated a possible mechanism underlying NAFLD prevention and suppression of further deterioration by YZW-A.

Bioactive Peptide Improves Diet-Induced Hepatic Fat Deposition and Hepatocyte Proinflammatory Response in SAMP8 Ageing Mice.

BACKGROUND/AIMS: High-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) poses therapeutic challenges in elderly subjects. Due to lack of efficient drug therapy, plant-based bioactive peptides have been studied as alternative strategy in NAFLD and for less toxicity in elderly. To mimic fatty liver in aging conditions, researchers highly commended the genetically engineered strains SAMP8 (senescence-accelerated mice prone 8). However, there is a paucity of reports about the anti-steatosis effects of bioactive peptides against fatty liver development under a combined action of high-fat diet exposure and aging process. This study was conducted to evaluate the activity of DIKTNKPVIF peptide synthesized from alcalase-generated potato protein hydrolysate (PH), on reducing HFD-driven and steatosis-associated proinflammatory reaction in ageing model. METHODS: Five groups of six-month-old SAMP8 mice (n=4, each) were fed either a normal chow (NC group) for 14 weeks upon sacrifice, or induced with a 6-week HFD feeding, then treated without (HCO group) or with an 8-week simultaneous administration of peptide (HPEP group), protein (HPH group) or probucol (HRX group). Liver organs were harvested from each group for histological analysis and immunoblot assay. RESULTS: In contrast to NC, extensive fat accumulation was visualized in the liver slides of HCO. Following the trends of orally administered PH, intraperitoneally injected peptide reduces hepatic fat deposition and causes at protein level, a significant decrease in HFD-induced proinflammatory mediators p-p38 MAPK, FGF-2, TNF-α, IL-6 with concomitant reactivation of AMPK. However, p-Foxo1 and PPAR-α levels were slightly changed. CONCLUSION: Oral supplementation of PH and intraperitoneal injection of derived bioactive peptide alleviate proinflammatory reaction associated with hepatosteatosis development in elderly subjects, through activation of AMPK.

Regulatory Role of Endothelial PHD2 in the Hepatic Steatosis.

BACKGROUND/AIMS: Liver disease is a leading cause of high mortality and morbidity worldwide. The aim of the present study is to investigate the regulatory role of prolyl hydroxylase-2 (PHD2)-hypoxia-inducible factor-2a (HIF-2α) axis on nonalcoholic fatty liver disease (NAFLD) and to explore the potential mechanisms by which endothelial (EC)-specific PHD2 deficiency regulates hepatic steatosis and fibrosis. METHODS: In the endothelial-specific PHD2 knockout (PHD2ECKO) mouse fed with normal diet or high fat diet (HFD), liver lipid accumulation and fibrosis were measured by Oil Red O and Masson trichrome staining. The fat and body weight (FW/BW) ratio and glucose tolerance were measured. The expression of HIF-2α, atrial natriuretic peptide (ANP), angiopoietin-2 (Ang-2), and transforming growth factor-b (TGF-ß) were analyzed by western blot analysis. RESULTS: The steatosis and fibrosis were significantly increased in the PHD2ECKO mice. FW/BW ratio was significantly increased in the PHD2ECKO mice. Moreover, knockout of endothelial PHD2 resulted in an impairment of glucose tolerance in mice. Western blot analysis showed that the expression of HIF-2α in liver tissues was not significantly increased. Interestingly, the expression of ANP was decreased, and Ang-2 and TGF-ß levels were significantly increased in the liver of PHD2ECKO mice. The FW/BW ratio was also significantly increased in the PHD2ECKO mice fed with HFD for 16 weeks. Feeding HFD resulted in a significant increase in hepatic steatosis in the control PHD2f/f mice, but did not further enhance hepatic steatosis in the PHD2ECKO mice. CONCLUSIONS: We concluded that the endothelial PHD2 plays a critical role in hepatic steatosis and fibrosis, which may be involved in the regulation of ANP and Ang-2/TGF-ß signaling pathway, but not the HIF-2α expression.

Evaluation of High Dosages of Oral Meloxicam in American Kestrels ( Falco sparverius ).

To evaluate the toxicity of short-term high doses of meloxicam in American kestrels ( Falco sparverius ), 32 male captive-born, 1- to 4-year-old American kestrels were randomly assigned to 4 groups: 3 groups treated with meloxicam (n = 9 per group) and a control group (n = 5). Meloxicam was administered orally via feeding tube in the proventriculus at 2, 10, and 20 mg/kg every 12 hours for 7 days for the treatment groups, while the control group received saline solution. The birds were evaluated for the presence of clinical signs, abnormalities in the complete blood cell count and in the plasma biochemical panel for the 20-mg/kg group, and gross and histopathologic lesions. No clinical signs or mortality were observed in any group. No significant differences of clinical relevance were found in results of the packed cell volume, total solids, and biochemical panel, and no evidence of renal toxicity was found in the treatment or control groups. A significant correlation was found between hepatic lipidosis and meloxicam dose (P = .02). Two of 9 birds in the 20-mg/kg group developed gastric ulcers, although this result was not significant. None of the birds in the 2- and 10-mg/kg groups had similar lesions. Finally, meloxicam dosages up to 20 mg/kg did not result in nephrotoxicity in American kestrels. Further toxicologic studies to evaluate hepatotoxicity and gastrotoxicity of meloxicam in avian species are needed.

Loss of LBP triggers lipid metabolic disorder through H3K27 acetylation-mediated C/EBPß- SCD activation in non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is associated with mutations in lipopolysaccharide-binding protein ( LBP), but the underlying epigenetic mechanisms remain understudied. Herein, LBP -/- rats with NAFLD were established and used to conduct integrative targeting-active enhancer histone H3 lysine 27 acetylation (H3K27ac) chromatin immunoprecipitation coupled with high-throughput and transcriptomic sequencing analysis to explore the potential epigenetic pathomechanisms of active enhancers of NAFLD exacerbation upon LBP deficiency. Notably, LBP -/- reduced the inflammatory response but markedly aggravated high-fat diet (HFD)-induced NAFLD in rats, with pronounced alterations in the histone acetylome and regulatory transcriptome. In total, 1 128 differential enhancer-target genes significantly enriched in cholesterol and fatty acid metabolism were identified between wild-type (WT) and LBP -/- NAFLD rats. Based on integrative analysis, CCAAT/enhancer-binding protein ß (C/EBPß) was identified as a pivotal transcription factor (TF) and contributor to dysregulated histone acetylome H3K27ac, and the lipid metabolism gene SCD was identified as a downstream effector exacerbating NAFLD. This study not only broadens our understanding of the essential role of LBP in the pathogenesis of NAFLD from an epigenetics perspective but also identifies key TF C/EBPß and functional gene SCD as potential regulators and therapeutic targets.

Dietary bile acids supplementation improves the growth performance and alleviates fatty liver in broilers fed a high-fat diet via improving the gut microbiota.

This experiment aims to evaluate the effect of bile acids (BAs) in alleviating fatty liver disease induced by a high-fat diet (HFD) in broilers, and the modulation of the gut microbiota involved in this process. A total of 192 one-day-old Arbor Acres (AA) commercial male broilers were randomly divided into 4 groups and treated with the following diet: a basal-fat diet (BFD), a basal-fat diet plus bile acids (BFD + BAs), an HFD, and a high-fat diet plus bile acids (HFD + BAs). Bile acids were supplemented at the early growth stage (3-7 d), middle stage (17-21 d), and late stage (31-35 d). Results showed that BAs treatment had a significant effect on body weight on 14 d and 35 d, and increased the breast muscle weight and its index, but decreased the liver weight and abdominal fat weight on 35 d (P < 0.05). The supplementation of BAs significantly improved the serum lipid profile and decreased the level of triglycerides (TG), total cholesterol (TCHO), and nonesterified fatty acids (NEFA) on 35 d (P < 0.05). Dietary BAs supplementation significantly alleviated the hepatic TG deposition induced by HFD (P < 0.05), which was accompanied by upregulation of peroxisome proliferator-activated receptor gamma (PPARγ) and lipoprotein lipase (LPL) gene expression (P < 0.05). Moreover, the expression levels of hepatic gene adipose triglyceride lipase (ATGL), peroxisome proliferator-activated receptor α (PPARα), and apolipoprotein B (APOB) were greatly increased by BAs treatment. The analysis of 16S rRNA sequencing showed that the microbial diversity of the cecal digesta was increased by BAs in broilers with elevated abundances of Firmicutes, Lactobacillus, Anaerostipes, Sellimonas, and CHKCI002 and decreased abundances of Barnesiella and Akkermansia genus (P < 0.05). Hepatic TG content was positively correlated with the abundance of Oscillospiraceae, but it was negatively correlated with the abundance of Lactobacillus in cecal digesta (P < 0.05). These results indicate that dietary BAs can improve growth performance and alleviate fatty liver disease induced by an HFD via modulating gut microbiota in broilers.

Development of fatty liver disease model using high cholesterol and low choline diet in white leghorn chickens.

Nonalcoholic fatty liver disease (NAFLD), which shows similar symptoms as fatty liver hemorrhage syndrome (FLHS) in chickens, is the most common cause of chronic liver disease and cancer in humans. NAFLD patients and FLHS in chickens have demonstrated severe liver disorders when infected by emerging strains of human hepatitis E virus (HEV) and avian HEV, respectively. We sought to develop a fatty liver disease chicken model by altering the diet of 3-week-old white leghorn chickens. The high cholesterol, and low choline (HCLC) diet included 7.6% fat with additional 2% cholesterol and 800 mg/kg choline in comparison to 5.3% fat, and 1,300 mg/kg choline in the regular diet. Our diet induced fatty liver avian model successfully recapitulates the clinical features seen during NAFLD in humans and FLHS in chickens, including hyperlipidemia and hepatic steatosis, as indicated by significantly higher serum triglycerides, serum cholesterol, liver triglycerides, cholesterol, and fatty acids. By developing this chicken model, we expect to provide a platform to explore the role of lipids in the liver pathology linked with viral infections and contribute to the development of prophylactic interventions.

Melatonin alleviates cadmium-induced nonalcoholic fatty liver disease in ducks by alleviating autophagic flow arrest via PPAR-α and reducing oxidative stress.

Cadmium (Cd) is an important environmental pollutant that causes liver damage and induces nonalcoholic fatty liver disease (NAFLD). NAFLD is a fat accumulation disease and has significant effects on the body. Melatonin (Mel) is an endogenous protective molecule with antioxidant, anti-inflammatory, antiobesity, and antiaging effects. However, whether Mel can alleviate Cd-induced NAFLD and its mechanism remains unclear. First, in vivo, we found that Mel maintained mitochondrial structure and function, inhibited oxidative stress, and reduced Cd-induced liver injury. In addition, Mel alleviated lipid accumulation in the liver induced by Cd. In this process, Mel inhibits fatty acid production and promotes fatty acid oxidation. Interestingly, Mel regulated PPAR-α expression and alleviated Cd-induced autophagy blockade. In vitro model, the oil Red O staining, and WB results showed that Mel alleviated Cd-induced lipid accumulation. In addition, RAPA was used to activate autophagy to alleviate Cd-induced lipid accumulation, and TG was used to block autophagy flux to aggravate Cd-induced autophagy accumulation. After knocking down PPAR-α, the autophagosome fusion with lysosomes, and autophagic flux was inhibited and increased Cd-induced lipid accumulation. Mel alleviates mitochondrial damage and oxidative stress, and attenuates Cd-induced NAFLD by restoring the expression of PPAR-α and restoring autophagy flux.

Role of Plin5 Deficiency in Progression of Non-Alcoholic Fatty Liver Disease Induced by a High-Fat Diet in Mice.

Characterized by steatosis, inflammation and fibrosis, non-alcoholic fatty liver disease (NAFLD) is a metabolic disorder. As a major lipid droplet-binding protein, Plin5 has been reported to have multiple effects on metabolism, but the effect of Plin5 deficiency on NAFLD is unknown. Plin5 knockout mice and wild-type mice were used to investigate the role of Plin5 in the progression of NAFLD by feeding a high-fat diet (HFD) for 20 weeks. Plin5 deficiency improved obesity induced by the HFD and altered glucose tolerance. Histological examination revealed that Plin5 deficiency alleviated hepatic steatosis and fibrosis induced by the HFD. Plin5 deficiency was also associated with a significant change in lipid metabolism-associated molecules. Further studies of these molecules indicated that Plin5 deficiency activated the expression of AMP-activated protein kinase and inhibited the core regulator of lipogenesis, sterol regulatory element binding protein 1 and its downstream lipid synthesis-related genes. These findings suggest that Plin5 deficiency ameliorates NAFLD by regulating lipid metabolism and inhibiting lipogenesis, and may provide a new strategy for the treatment of NAFLD.

Complement C3 participates in the development of goose fatty liver potentially by regulating the expression of FASN and ETNK1.

Non-alcoholic fatty liver disease (NAFLD) occurs in humans, domestic animals and poultry. Different from upregulation of complement C3 in human NAFLD, C3 expression is inhibited in goose fatty liver (GFL), implying a specific role of C3 in GFL. This study was mainly focused on uncovering the uniqueness of goose liver cells in the regulation of C3 expression and identifying the downstream genes of C3 to improve understanding on the specific role of C3 in GFL. The results showed that C3 expression was inhibited in the liver, muscle and fat tissues of the overfed versus control (normally fed) geese. Oleate and insulin could inhibit C3 expression in goose primary hepatocytes but induce it in mouse primary hepatocytes. A total of 1,123 differentially expressed genes (DEGs) were affected by C3 overexpression and were mainly enriched in immune response/inflammation and catabolism-related KEGG pathways. Additionally, the representative downstream genes (FASN and ETNK1) of C3 could mediate the role of C3 in the development of GFL. In conclusion, the suppression of C3 in GFL is at least partially attributed to hyperinsulinemia, hyperlipidemia and uniqueness of goose liver cells. Complement C3 does not only affect hepatic steatosis but also affect inflammation/immune response in GFL.

Based on network pharmacology method to discovered the targets and therapeutic mechanism of Paederia scandens against nonalcoholic fatty liver disease in chicken.

The aim of the study is to determine the target of Paeteria scandens in nonalcoholic fatty liver disease (NAFLD). The Chinese herbal medicine pharmacology data and analysis platform were used to search and screen for the effective components of the Paeteria scandens compounds and to analyze the possible therapeutic targets based on network topology. In addition, various known disease target databases were enrolled, the therapeutic target proteins in NAFLD were screened, and a protein-protein interaction network was constructed. Enrichment analysis was performed on key nodes. Finally, the inhibitory effect of Paeteria scandens on NAFLD was verified by experiments. We identified 33 major candidate targets of Paeteria scandens and successfully constructed a "drug-compound-target-disease" network. Abovementioned targets revealed by gene enrichment analysis have played a significant role in the cell cycle, apoptosis, and related signal pathways. We demonstrated that Paeteria scandens downregulated serum triglyceride and lipopolysaccharides levels in NAFLD chickens by feeding with a high-capacity diet and endotoxin of Salmonella enteritidis was given by gavage. Paeteria scandens may regulate the hepatic cell cycle and apoptosis through the Salmonella infection pathway, Toll-like receptor signaling pathway, and apoptosis pathway. For NAFLD, Paeteria scandens may be a promising, long-lasting treatment strategy.

Greater liver PNPLA3 protein abundance in vivo and in vitro supports lower triglyceride accumulation in dairy cows.

Fatty liver syndrome is a prevalent metabolic disorder in peripartum dairy cows that unfavorably impacts lactation performance and health. Patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a lipase that plays a central role in human non-alcoholic fatty liver disease etiology but has received limited attention in bovine fatty liver research. Thus, we investigated the relationship between tissue PNPLA3 expression and liver triglyceride accumulation in vivo via a ketosis induction protocol in multiparous dairy cows peripartum, as well as in vitro via small interfering RNA knockdown of PNPLA3 mRNA expression in bovine primary hepatocytes. Results demonstrated a negative association (P = 0.04) between liver PNPLA3 protein abundance and liver triglyceride content in peripartum dairy cows, while adipose PNPLA3 protein abundance was not associated with liver triglyceride content or blood fatty acid concentration. Knockdown of PNPLA3 mRNA resulted in reduced PNPLA3 protein abundance (P < 0.01) and greater liver triglyceride content (P < 0.01). Together, these results suggest greater liver PNPLA3 protein abundance may directly limit liver triglyceride accumulation peripartum, potentially preventing bovine fatty liver or accelerating recovery from fatty liver syndrome.

Exchanging dietary fat source with extra virgin olive oil does not prevent progression of diet-induced non-alcoholic fatty liver disease and insulin resistance.

Dietary fat is discussed to be critical in the development of non-alcoholic fatty liver disease. Here, we assess the effect of exchanging dietary fat source from butterfat to extra virgin olive oil on the progression of an already existing diet-induced non-alcoholic fatty liver disease in mice. Female C57BL/6J mice were fed a liquid butterfat-, fructose- and cholesterol-rich diet (BFC, 25E% from butterfat) or control diet (C, 12%E from soybean oil) for 13 weeks. In week 9, fat sources of some BFC- and C-fed mice were switched either to 25E% or 12E% olive oil (OFC and CO). Glucose and insulin tolerance tests were performed, and markers of liver damage and glucose metabolism were assessed. After 6 weeks of feeding, BFC-fed mice had developed marked signs of insulin resistance, which progressed to week 12 being not affected by the exchange of fat sources. Liver damage was similar between BFC- and OFC-fed mice. Markers of lipid metabolism and lipid peroxidation in liver and of insulin signaling in liver and muscle were also similarly altered in BFC- and OFC-fed mice. Taken together, our data suggest that exchanging butterfat with extra virgin olive oil has no effect on the progression of non-alcoholic fatty liver disease and glucose tolerance in mice.

Interactions between the cecal microbiota and non-alcoholic steatohepatitis using laying hens as the model.

Chronic liver disease has caused increasing numbers of deaths worldwide. Fatty liver hemorrhagic syndrome, one of the chronic liver diseases in laying hens, has great similarity to non-alcoholic fatty liver disease (NAFLD) in humans. It is characterized by the pathological accumulation of liver fat. Non-invasive techniques are needed for early identification of fibrosis. As primary de novo lipogenesis in the liver of chicken is similar to that of humans, mature chicken is an ideal animal model for the understanding of NAFLD. This study was aimed to evaluate the relationships between gut microbiota and natural chronic liver disease (i.e., non-alcoholic steatohepatitis [NASH] and fibrosis stages) in a well-characterized laying hen population. One hundred 20-wk-old Hy-Line Brown laying hens were used and fed with basal diets until 52 wk of age. At the end of the experiment, birds were killed for sampling blood, liver, and cecal contents, and then classified by liver histology measurement into different groups. We investigated microbial community structure of cecum using 16S rRNA gene sequencing. Subjects in stage 0 fibrosis without NASH were classified as low NAFLD (Group A), subjects in stage 1-2 fibrosis with mild to moderate NASH were defined as low NASH (Group B), and subjects in stage 3 fibrosis were defined as severe NASH (Group C). The abundance of Firmicutes was reduced in Groups B and C (P < 0.001), whereas opposite results were observed for the abundance of Bacteroidetes. Additionally, the families Bacteroidaceae, Ruminococcaceae Lachnospiraceae, and lactobacillae were significantly different between groups of differing fibrosis stages (P < 0.001), driven entirely by alterations of Bacteroides and lactobacillus and lachnospiraceae genera (P < 0.001), were observed. Results indicated that cecal dysbiosis was linked with the severity of fibrosis and NASH; importantly, increased levels of serum AST, alkaline phosphatase, and uric acid were accompanied with liver fibrosis and NASH severity. Collectively, these data highlight the role of gut-liver axis and associations between the gut microbiota and fibrosis and NASH severity.

CYP3A suppression during diet-induced nonalcoholic fatty liver disease is independent of PXR regulation.

Cytochrome P450 3A (CYP3A) activity is inhibited, and its expression is suppressed during many diseases, including nonalcoholic fatty liver disease (NAFLD). However, the mechanism is controversial. Here, we report that PXR may not take part in the downregulation of CYP3A during NAFLD. Hepatic CYP3A11 (major subtype of mouse CYP3A) mRNA and protein expression was significantly decreased in both mice fed a high-fat diet (HFD) for 8 weeks and palmitate (PA)-treated mouse primary hepatocytes. Similarly, in HepG2 cells, PA treatment significantly suppressed the CYP3A4 (major subtype of human CYP3A) mRNA level and promoter transcription activity. However, Western blotting analysis found an induction of PXR nuclear translocation during NAFLD in both in vivo and in vitro models. Moreover, immunofluorescence determination also found nuclear translocation effect of PXR by PA stimulation in HepG2 cells. In addition, the siRNA knockdown of PXR did not affect the suppressive effects of PA on the CYP3A4 promoter transcription activity and mRNA levels in HepG2 cells. Similarly, PXR knockdown also did not affect the suppressive effects of PA on CYP3A11 mRNA and protein expression levels in mouse primary hepatoctyes. Taken together, the results showed that the suppressive effect of CYP3A transcription was independent of PXR regulation.

Improved quantitative fatty acid values with correction of T2 relaxation time in terminal methyl group: In vivo proton magnetic resonance spectroscopy at ultra high field in hepatic steatosis.

Proton magnetic resonance spectroscopy (MRS) with optimized relaxation time is an effective method to quantify hepatic fatty acid values and characterize steatosis. The aim of this study is to quantify the difference in hepatic lipid content with metabolic changes during the progression of steatosis by using localized MRS sequence with T2 relaxation time determination. Fatty liver disease was induced in C57BL/6N mice through a high-fat diet (HFD) of pellets containing 60% fat, 20% protein, and 20% carbohydrates. We used stimulated echo acquisition mode (repetition time: 3500 ms; mixing time: 10 ms; echo time: 20 ms) sequence. Using enhanced and mono exponential curve-fitting methods, the lipid relaxation time in mice was estimated at a fixed repetition time of 5000 ms and echo time ranging from 20 to 70 ms. The calculated lipid contents with incorrect and correct relaxation times were as follows: total saturated fatty acid (4.00 ±â€¯2.90 vs 6.74 ±â€¯2.25, p < 0.05 at week 0; 15.23 ±â€¯9.94 vs 25.53 ±â€¯10.49, p < 0.05 at week 4); total unsaturated fatty acid (0.40 ±â€¯0.49 vs 0.56 ±â€¯0.47, p < 0.05 at week 4; 0.33 ±â€¯0.26 vs 0.60 ±â€¯0.21, p < 0.01 at week 7); total unsaturated bond (0.48 ±â€¯0.52 vs 1.05 ±â€¯0.58, p < 0.05 at week 10). Furthermore, we determined that the correct relaxation times of triglycerides between 0 and 10 weeks were significantly altered in the resonances (∼2.03 ppm: 31.07 ±â€¯1.00 vs 27.62 ±â€¯1.20, p < 0.01; ∼2.25 ppm: 29.10 ±â€¯1.52 vs 26.39 ±â€¯1.08, p < 0.05; ∼2.78 ppm: 37.67 ±â€¯2.92 vs 29.37 ±â€¯2.64, p < 0.001). The work presented focused on the significance of the J-coupling effect. The selection of an appropriate relaxation time considering the J-coupling effect provides an effective method for quantifying lipid contents and characterizing hepatic steatosis.