Aerobic training with moderate or high doses of vitamin D improve liver enzymes, LXRα and PGC-1α levels in rats with T2DM.

Dysregulation of key transcription factors involved in hepatic energy metabolism, such as peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) and liver X receptor alpha (LXRα), has been observed in T2DM. The present study aims to investigate the effects of aerobic training and vitamin D supplementation on liver enzyme levels and the levels of PGC-1α and LXRα proteins in hepatocytes, in a rat model of T2DM. The study involved 56 male Wistar rats, divided into two groups: one was non-diabetic and acted as a control group (n = 8), and the other had induced diabetes (n = 48). The diabetic rats were then split into six subgroups: two groups received high or moderate doses of vitamin D and aerobic training (D + AT + HD and D + AT + MD); two groups received high or moderate doses of vitamin D alone (D + HD and D + MD); one group underwent aerobic training with vehicle (sesame oil; D + AT + oil), and one group was a diabetic control receiving only sesame oil (oil-receiving). The D + AT + HD and D + HD groups received 10,000 IU of vitamin D, while the D + AT + MD and D + MD groups received 5000 IU of vitamin D once a week by injection. The D + AT + oil group and the sham group received sesame oil. After eight weeks of treatment, body weight, BMI, food intake, serum insulin, glucose, 25-hydroxyvitamin D, ALT, AST, and visceral fat were measured. The levels of PGC-1α and LXRα proteins in the liver was assessed by western blotting. Statistical analysis was performed using the paired t-test, one-way analysis of variance (ANOVA), and the Tukey post hoc test at a significance level of P < 0.05. Body weight, food intake, and BMI decreased significantly in the D + AT + HD, D + AT + MD, D + AT + oil, D + HD, and D + MD groups with the highest reduction being observed in body weight and BMI in the D + AT + HD group. The D + AT + HD group exhibited the lowest levels of insulin, glucose, and HOMA-IR while the D + C group exhibited the highest levels among the diabetic groups. The D + AT + HD and D + AT + MD groups had lower levels of ALT and AST enzymes compared to the other groups with no significant difference between D + AT + HD and D + AT + MD. D + AT + HD (p = 0.001), D + AT + MD (p = 0.001), D + HD (p = 0.023), D + MD (p = 0.029), and D + AT + oil (p = 0.011) upregulated LXRα compared to D + C. Among these groups, D + AT + HD exhibited a more profound upregulation of LXRα than D + AT + MD, D + AT + oil, D + HD, and D + MD (p = 0.005; p = 0.002, p = 0.001, and p = 0.001, respectively). Similarly, D + AT + HD showed a more notable upregulation of PGC-1α compared to D + AT + oil, D + HD, and D + MD (p = 0.002; p = 0.001, and p = 0.001, respectively). Pearson correlation tests showed significant and negative correlations between serum 25-hydroxyvitamin levels and both visceral fat (r = - 0.365; p = 0.005) and HOMA-IR (r = - 0.118; p = 0.009); while positive and significant correlations between the liver-to-bodyweight ratio with both ALT and AST enzymes and also between QUICKI levels with LXRα (r = 0.578; p = 0.001) and PGC-1α (r = 0.628; p = 0.001). Combined administration of aerobic training and vitamin D supplementation potentially improves liver enzymes in type-2 diabetic rats that were simultaneous with upregulating the levels of PGC-1α and LXRα proteins in hepatocytes. These improvements were more significant when combining exercise with high-dose vitamin D supplementation. This study highlights the potential of this combination therapy as a new diabetes treatment strategy.

Cornelian Cherry (Cornus mas L.) Fruit Extract Lowers SREBP-1c and C/EBPα in Liver and Alters Various PPAR-α, PPAR-γ, LXR-α Target Genes in Cholesterol-Rich Diet Rabbit Model.

Cornelian cherry (Cornus mas L.) fruits, abundant in iridoids and anthocyanins, are natural products with proven beneficial impacts on the functions of the cardiovascular system and the liver. This study aims to assess and compare whether and to what extent two different doses of resin-purified cornelian cherry extract (10 mg/kg b.w. or 50 mg/kg b.w.) applied in a cholesterol-rich diet rabbit model affect the levels of sterol regulatory element-binding protein 1c (SREBP-1c) and CCAAT/enhancer binding protein α (C/EBPα), and various liver X receptor-α (LXR-α), peroxisome proliferator-activated receptor-α (PPAR-α), and peroxisome proliferator-activated receptor-γ (PPAR-γ) target genes. Moreover, the aim is to evaluate the resistive index (RI) of common carotid arteries (CCAs) and aortas, and histopathological changes in CCAs. For this purpose, the levels of SREBP-1c, C/EBPα, ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), fatty acid synthase (FAS), endothelial lipase (LIPG), carnitine palmitoyltransferase 1A (CPT1A), and adiponectin receptor 2 (AdipoR2) in liver tissue were measured. Also, the levels of lipoprotein lipase (LPL), visceral adipose tissue-derived serine protease inhibitor (Vaspin), and retinol-binding protein 4 (RBP4) in visceral adipose tissue were measured. The RI of CCAs and aortas, and histopathological changes in CCAs, were indicated. The oral administration of the cornelian cherry extract decreased the SREBP-1c and C/EBPα in both doses. The dose of 10 mg/kg b.w. increased ABCA1 and decreased FAS, CPT1A, and RBP4, and the dose of 50 mg/kg b.w. enhanced ABCG1 and AdipoR2. Mitigations in atheromatous changes in rabbits' CCAs were also observed. The obtained outcomes were compared to the results of our previous works. The beneficial results confirm that cornelian cherry fruit extract may constitute a potentially effective product in the prevention and treatment of obesity-related disorders.

Activation of Liver X Receptors and Peroxisome Proliferator-Activated Receptors by Lipid Extracts of Brown Seaweeds: A Potential Application in Alzheimer's Disease?

The nuclear liver X receptors (LXRα/ß) and peroxisome proliferator-activated receptors (PPARα/γ) are involved in the regulation of multiple biological processes, including lipid metabolism and inflammation. The activation of these receptors has been found to have neuroprotective effects, making them interesting therapeutic targets for neurodegenerative disorders such as Alzheimer's Disease (AD). The Asian brown seaweed Sargassum fusiforme contains both LXR-activating (oxy)phytosterols and PPAR-activating fatty acids. We have previously shown that dietary supplementation with lipid extracts of Sargassum fusiforme prevents disease progression in a mouse model of AD, without inducing adverse effects associated with synthetic pan-LXR agonists. We now determined the LXRα/ß- and PPARα/γ-activating capacity of lipid extracts of six European brown seaweed species (Alaria esculenta, Ascophyllum nodosum, Fucus vesiculosus, Himanthalia elongata, Saccharina latissima, and Sargassum muticum) and the Asian seaweed Sargassum fusiforme using a dual luciferase reporter assay. We analyzed the sterol and fatty acid profiles of the extracts by GC-MS and UPLC MS/MS, respectively, and determined their effects on the expression of LXR and PPAR target genes in several cell lines using quantitative PCR. All extracts were found to activate LXRs, with the Himanthalia elongata extract showing the most pronounced efficacy, comparable to Sargassum fusiforme, for LXR activation and transcriptional regulation of LXR-target genes. Extracts of Alaria esculenta, Fucus vesiculosus, and Saccharina latissima showed the highest capacity to activate PPARα, while extracts of Alaria esculenta, Ascophyllum nodosum, Fucus vesiculosus, and Sargassum muticum showed the highest capacity to activate PPARγ, comparable to Sargassum fusiforme extract. In CCF-STTG1 astrocytoma cells, all extracts induced expression of cholesterol efflux genes (ABCG1, ABCA1, and APOE) and suppressed expression of cholesterol and fatty acid synthesis genes (DHCR7, DHCR24, HMGCR and SREBF2, and SREBF1, ACACA, SCD1 and FASN, respectively). Our data show that lipophilic fractions of European brown seaweeds activate LXRs and PPARs and thereby modulate lipid metabolism. These results support the potential of brown seaweeds in the prevention and/or treatment of neurodegenerative diseases and possibly cardiometabolic and inflammatory diseases via concurrent activation of LXRs and PPARs.

Juniper Berries Regulate Diabetes and Obesity Markers Through Modulating PPARα, PPARγ, and LXR: In Vitro and In Vivo Effects.

The berries of Juniperus communis have been traditionally used for therapeutic purposes. They have been reported to possess various pharmacological effects such as anti-inflammatory, hypoglycemic and hypolipidemic activities. In this study, a methanolic extract of J. communis berries (JB) was evaluated for its effects on peroxisome proliferator-activated receptors alpha and gamma (PPARα and PPARγ), liver X receptor (LXR), glucose uptake and lipid accumulation using various cellular systems. At a concentration of 25 µg/mL, JB caused 3.77-fold activation of PPARα, 10.90-fold activation of PPARγ, and 4.43-fold activation of LXR in hepatic cells. JB inhibited (11%) the adipogenic effect induced by rosiglitazone in adipocytes and increased glucose uptake (90%) in muscle cells. In high-fat diet (HFD) fed mice, JB at a dose of 25 mg/kg body weight exhibited a 21% decrease in body weight. Fasting glucose levels in mice treated with 12.5 mg/kg of JB were significantly decreased (39%) indicating its efficacy in regulating hyperglycemia and obesity induced by HFD thus ameliorating the symptoms of type 2 diabetes. A series of energy metabolic genes, including Sirt1 (2.00-fold) and RAF1 (2.04-fold), were upregulated by JB, while rosiglitazone regulated the hepatic PPARγ only. Phytochemical analysis of JB indicated presence of a number of flavonoids and biflavonoids which seem to be responsible for the observed activity. It was concluded that JB acted as a multiple agonist of PPARα, PPARγ and LXR without the undesired effect of adipogenesis and exhibited the property of enhancing glucose uptake. The regulation of PPARα, PPARγ and LXR seems to be through Sirt1 and RAF1. In vivo results confirmed the antidiabetic and antiobesity potential of JB and indicated its utility in metabolic disorder and type 2 diabetes.

Qingluotongbi formula regulates the LXRα-ERS-SREBP-1c pathway in hepatocytes to alleviate the liver injury caused by Tripterygium wilfordii Hook. f.

ETHNOPHARMACOLOGICAL RELEVANCE: Tripterygium wilfordii Hook. f. (TW) is widely used to treat autoimmune and inflammatory diseases; however, its development and application is limited by its significant association with liver injury. The compound formula Qingluotongbi (QLT) employs TW as its main component and is used to treat rheumatoid arthritis with no adverse reactions, suggesting that QLT may reduce the liver toxicity of TW. AIM OF THE STUDY: We examined whether TW interferes with lipid metabolism to induce liver injury, and evaluated the protective effect of QLT in in vivo and in vitro experiments. MATERIALS AND METHODS: After administration of QLT and its ingredients, HepaRG cells and SD rats were tested for biochemical indicators, hepatocytes lipid changes, and rat liver pathological changes, and then we analyzed for the gene expression of liver X receptor α (LXRα), endoplasmic reticulum stress (ERS) key proteins, sterol regulatory element binding protein-1c (SREBP-1c), and lipid-synthesizing enzymes. In HepaRG cells, the protein expression of glucose-regulated protein 78 kDa (GRP78) and LXRα was detected after addition of an LXRα inhibitor, LXRα agonist, and ERS inhibitor. RESULTS: TW caused significant elevation of biochemical indicators and lipid droplet deposition in hepatocytes, as well as upregulated the gene expression of LXRα, ERS key proteins, SREBP-1c, and lipid-synthesizing enzymes in both in vitro and in vivo settings, and caused liver injury in rats. QLT can alleviate the lipotoxic liver injury caused by TW. LXRα agonist further activated ERS induced by TW, whereas LXRα inhibitor significantly reduced ERS and lipotoxic injury induced by TW in HepaRG cells. CONCLUSIONS: TW upregulated LXRα to activate ERS and increased the gene expression of SREBP-1c and lipid-synthesizing enzymes, leading to increased lipid synthesis in hepatocytes to result in liver injury. QLT inhibited the LXRα-ERS-SREBP-1c pathway and reduced abnormal lipid synthesis in hepatocytes and the hepatotoxicity of TW.

Effects of Danhong injection on dyslipidemia and cholesterol metabolism in high-fat diets fed rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Danhong injection (DHI) is a Chinese medical injection applied to the clinical treatment of cardiovascular diseases that has anti-inflammatory, antiplatelet aggregation and antithrombotic effects. This study aimed to explore the effects of DHI on dyslipidemia and cholesterol metabolism in high-fat diet-fed rats. METHODS: Sprague Dawley (SD) rats were randomly divided into six groups: normal group (Normal); hyperlipidemia model group (Model); DHI-treated groups at doses of 1.0 mL/kg, 2.0 mL/kg, 4.0 mL/kg; and simvastatin positive control group (2.0 mg/kg). The hypolipidemic effects of DHI were evaluated by measuring serum lipid levels, hepatic function and oxidative stress, respectively. And pathological changes in liver tissues were determined using hematoxylin-eosin (H&E) and oil red O staining. Moreover, the mRNA and protein expression levels of cholesterol metabolism related genes were detected by real-time PCR (RT-PCR) and Western blot. RESULTS: Compared with the Model group, DHI treatment markedly decreased the liver index and improved the pathological morphology of liver tissues. DHI treatment dose-dependently decreased the levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), malondialdehyde (MDA), and free fatty acids (FFA) in serum or liver tissues (P < 0.01 or P < 0.05), and increased the high-density lipoprotein cholesterol (HDL-C) and tripeptide glutathione (GSH) (P < 0.01 or P < 0.05). The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were increased in the DHI-treated groups (P < 0.01 or P < 0.05), while the alanine transaminase (ALT) and aspartate transaminase (AST) were decreased (P < 0.01 or P < 0.05). Furthermore, the expression levels of LDL receptor (LDLR), cholesterol 7-α-hydroxylase (CYP7A1), liver X receptor α (LXRα), and peroxisome proliferator-activated receptor α (PPARα) were dose-dependently upregulated in the DHI-treated groups, whereas the expression of sterol regulatory element-binding protein-2 (SREBP-2) was downregulated. CONCLUSIONS: Our study demonstrated that DHI markedly ameliorated hyperlipidemia rats by regulating serum lipid levels, inhibiting hepatic lipid accumulation and steatosis, improving hepatic dysfunction, and reducing oxidative stress. The potential mechanism was also tentatively investigated and may be related to the promotion of bile acid synthesis via activation of the PPARα-LXRα-CYP7A1 pathway. Therefore, DHI could be regarded as a potential hypolipidemic drug for the treatment of hyperlipidemia.

Myristica fragrans promotes ABCA1 expression and cholesterol efflux in THP-1-derived macrophages.

Myristica fragrans is a traditional herbal medicine and has been shown to alleviate the development of atherosclerosis. However, the anti-atherogenic mechanisms of M. fragrans are still to be addressed. In this study, we explored the effect of M. fragrans on lipid metabolism and inflammation and its mechanisms in THP-1-derived macrophages. The quantitative polymerase chain reaction and western blot analysis results showed that M. fragrans promotes cholesterol efflux from THP-1-derived macrophages and reduces intracellular total cholesterol, cholesterol ester, and free cholesterol contents in a dose- and a time-dependent manner. Further study found that liver X receptor alpha (LXRα) antagonist GGPP significantly blocked the upregulation of ABCA1 expression with M. fragrans treatment. In addition, chromatin immunoprecipitation assay confirmed that GATA binding protein 3 (GATA3) can bind to the LXRα promoter, and inhibition of GATA3 led to the downregulation of LXRα and ATP-binding cassette subfamily A member 1 expression. Furthermore, M. fragrans reduced lipid accumulation, followed by decreasing tumor necrosis factor-α, interleukin (IL)-6, and IL-1ß and increasing IL-10 produced by THP-1-derived macrophages. Therefore, M. fragrans is identified as a valuable therapeutic medicine for atherosclerotic cardiovascular disease.

L-carnitine exerts a nutrigenomic effect via direct modulation of nuclear receptor signaling in adipocytes, hepatocytes and SKMC, demonstrating its nutritional impact.

L-carnitine is an indispensable metabolite facilitating the transport of fatty acids into the mitochondrial matrix and has been previously postulated to exert a nutrigenomic effect. However, the underlying molecular mechanisms remain mostly unclear. We hypothesized that L-carnitine interacts with nuclear receptors involved in metabolic regulation, thereby modulating downstream targets of cellular metabolism. Therefore, we investigated the effect of L-carnitine supplementation on protein activity, mRNA expression, and binding affinities of nuclear receptors as well as mRNA expression of downstream targets in skeletal muscle cells, hepatocytes, and differentiated adipocytes. L-carnitine supplementation to hepatocytes increased the protein activity of multiple nuclear receptors (RAR, RXR, VDR, PPAR, HNF4, ER, LXR). Diverging effects on the mRNA expression of PPAR-α, PPAR-δ, PPAR-γ, RAR-ß, LXR-α, and RXR-α were observed in adipocytes, hepatocytes, and skeletal muscle cells. mRNA levels of PPAR-α, a key regulator of lipolysis and ß-oxidation, were significantly upregulated, emphasizing a role of L-carnitine as a promoter of lipid catabolism. L-carnitine administration to hepatocytes modulated the transcription of key nuclear receptor target genes, including ALDH1A1, a promoter of adipogenesis, and OGT, a contributor to insulin resistance. Electrophoretic mobility shift assays proved L-carnitine to increase binding affinities of nuclear receptors to their promoter target sequences, suggesting a molecular mechanism for the observed transcriptional modulation. Overall, these findings indicate that L-carnitine modulates the activity and expression of nuclear receptors, thereby promoting lipolytic gene expression and decreasing transcription of target genes linked to adipogenesis and insulin resistance.

Suppression of up-regulated LXRα by silybin ameliorates experimental rheumatoid arthritis and abnormal lipid metabolism.

BACKGROUND: As dysregulation of immunometabolism plays a key role in the immunological diseases, dyslipidemia frequently observed in rheumatoid arthritis (RA) patients (60%) is associated with the disease activity and has been considered as the potential target of anti-inflammatory strategy. However, targeting of metabolic events to develop novel anti-inflammatory therapeutics are far from clear as well as the mechanism of dyslipidemia in RA. PURPOSE: To explore the therapeutic potential and mechanisms of silybin again RA through the regulation of lipid metabolism. METHODS: Adjuvant-induced arthritis (AIA) rat model was used to examine the effects of silybin on modulating dysregulated lipid metabolism and arthritis. Metabolomics, docking technology, and biochemical methods such as western blots, qRT-PCR, immunofluorescence staining were performed to understanding the underlying mechanisms. Moreover, knock-down of LXRα and LXRα agonist were used on LO2 cell lines to understand the action of silybin. RESULTS: We are the first to demonstrate that silybin can ameliorate dyslipidemia and arthritis in AIA rats. Overexpression of LXRα and several key lipogenic enzymes regulated by LXRα, including lipoprotein lipase (LPL), cholesterol 7α and 27α hydroxylase (CYP7A, CYP27A), adipocyte fatty acid-binding protein (aP2/FABP4) and fatty acid translocase (CD36/FAT), were observed in AIA rats, which mostly accounted for dyslipidemia during arthritis development. Metabolomics, docking technology, and biochemical results indicated that anti-arthritis effects of silybin related to suppressing the up-regulated LXRα and abnormal lipid metabolism. Notably, activation of LXRα could potentiate cell inflammatory process induced by LPS through the regulation of NF-κB pathway, however, suppression of LXRα agonism by siRNA or silybin reduced the nuclear translocation of NF-κB as well as the induction of downstream cytokines, indicating LXRα agonism is the important factor for the arthritis development and could be a potential target. CONCLUSION: The up-regulation of LXRα can activate lipogenesis enzymes to worsen the inflammatory process in AIA rats as well as the development of dyslipidemia, therefore, rectifying lipid disorder via suppression of LXRα agonism pertains the capacity of drug target, which enables to discover and develop new drugs to treat rheumatoid arthritis with dyslipidaemia.

Network pharmacology of bioactives from Sorghum bicolor with targets related to diabetes mellitus.

BACKGROUND: Sorghum bicolor (SB) is rich in protective phytoconstituents with health benefits and regarded as a promising source of natural anti-diabetic substance. However, its comprehensive bioactive compound(s) and mechanism(s) against type-2 diabetes mellitus (T2DM) have not been exposed. Hence, we implemented network pharmacology to identify its key compounds and mechanism(s) against T2DM. METHODS: Compounds in SB were explored through GC-MS and screened by Lipinski's rule. Genes associated with the selected compounds or T2DM were extracted from public databases, and the overlapping genes between SB-compound related genes and T2DM target genes were identified using Venn diagram. Then, the networking between selected compounds and overlapping genes was constructed, visualized, and analyzed by RStudio. Finally, affinity between compounds and genes was evaluated via molecular docking. RESULTS: GC-MS analysis of SB detected a total of 20 compounds which were accepted by the Lipinski's rule. A total number of 16 compounds-related genes and T2DM-related genes (4,763) were identified, and 81 overlapping genes between them were selected. Gene set enrichment analysis exhibited that the mechanisms of SB against T2DM were associated with 12 signaling pathways, and the key mechanism might be to control blood glucose level by activating PPAR signaling pathway. Furthermore, the highest affinities were noted between four main compounds and six genes (FABP3-Propyleneglyco monoleate, FABP4-25-Oxo-27-norcholesterol, NR1H3-Campesterol, PPARA-ß-sitosterol, PPARD-ß-sitosterol, and PPARG-ß-sitosterol). CONCLUSION: Our study overall suggests that the four key compounds detected in SB might ameliorate T2DM severity by activating the PPAR signaling pathway.

Yin and Yang Regulation of Liver X Receptor α Signaling Control of Cholesterol Metabolism by Poly(ADP-ribose) polymerase 1.

Liver X receptor α (LXRα) controls a set of key genes involved in cholesterol metabolism. However, the molecular mechanism of this regulation remains unknown. The regulatory role of poly(ADP-ribose) polymerase 1 (PARP1) in cholesterol metabolism in the liver was examined. Activation of PARP1 in the liver suppressed LXRα sensing and prevented upregulation of genes involved in HCD-induced cholesterol disposal. Mechanistically, LXRα was poly(ADP-ribosyl)ated by activated PARP1, which decreased DNA binding capacity of LXRα, thus preventing its recruitment to the target promoter. Intriguingly, we found that unactivated PARP1 was indispensable for LXRα transactivation and target expression. Further exploration identified unactivated PARP1 as an essential component of the LXRα-promoter complex. Taken together, the results indicate that activated PARP1 suppresses LXRα activation through poly(ADP-ribosyl)ation, while unactivated PARP1 promotes LXRα activation through physical interaction. PARP1 is a pivotal regulator of LXRα signaling and cholesterol metabolism in the liver.

Ganoderma lucidum spore ethanol extract attenuates atherosclerosis by regulating lipid metabolism via upregulation of liver X receptor alpha.

CONTEXT: Ganoderma lucidum (Leyss.ex Fr.) Karst (Ganodermataceae) is a fungus that has been used in traditional Chinese medicine. OBJECTIVE: This is the first investigation of the lipid-lowering and anti-atherosclerotic effects of Ganoderma lucidum spore ethanol extract (EEG) in hyperlipidemic rabbits. MATERIALS AND METHODS: Fifty-four Japanese rabbits were randomly divided into six groups (n = 9): control, model, atorvastatin and three EEG groups (6, 24 and 96 mg/kg/day, p.o.). Control group was administered a normal diet and other groups were administered a high-fat diet to induce hyperlipidaemia and atherosclerosis for 14 weeks. During this time, lipid profiles were recorded; lipid testing and histopathological examination of aorta and liver were conducted. LXRα and its downstream genes expression in the liver and small intestine were examined. The effect of EEG on macrophage cholesterol efflux and ABCA1/G1 expression was observed under silenced LXRα expression. RESULTS: EEG reduced serum cholesterol (20.33 ± 3.62 mmol/L vs 34.56 ± 8.27 mmol/L for the model group) and LDL-C, reduced the area of arterial plaques (24.8 ± 10% vs 53.9 ± 15.2% for the model group) and Intima/Medium thickness ratio, increased faecal bile acid content, upregulated LXRα, CYP7A1, ABCA1/G1, ABCG5/G8 expression in the liver, small intestine and macrophages. After silencing LXRα in macrophages, the ability of EEG to promote cholesterol efflux was inhibited. DISCUSSION AND CONCLUSION: EEG exert lipid-lowering and anti-atherosclerotic effects via upregulating expression of LXRα and downstream genes associated with reverse cholesterol transport and metabolism. However, whether PPARα/γ are involved in the up-regulation of LXR expression by EEG remains to be elucidated.

Sophoricoside is a selective LXRß antagonist with potent therapeutic effects on hepatic steatosis of mice.

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease characterized by the accumulation of triglycerides and associated with obesity, hyperlipidemia and insulin resistance. Currently, there is no therapy for NAFLD. Emerging evidences suggest that the inhibition of liver X receptor (LXR) activity may be a potential therapy for hepatic steatosis. Here, we identified that sophoricoside is a selective antagonist of LXRß. Sophoricoside protected against obesity and glucose tolerance, and inhibited lipid accumulation in the liver of high-fat diet-induced obesity (DIO) mice and methionine and choline-deficient diet-induced nonalcoholic steatohepatitis mice. Furthermore, sophoricoside inhibited malondialdehyde, and increased superoxide dismutase and glutathione in the liver of the mice. In HepG2 cells, pretreatment with sophoricoside rescued GSH concentration decrease induced by H2 O2 treatment. Our data suggest that sophoricoside is a novel LXRß selective antagonist and may improve glucose and lipid dysfunction, and attenuate lipid accumulation in the liver of DIO mice via anti-oxidant properties, which may be developed as a therapy for NAFLD.

Mulberry Fruit Extract Promotes Serum HDL-Cholesterol Levels and Suppresses Hepatic microRNA-33 Expression in Rats Fed High Cholesterol/Cholic Acid Diet.

Serum high-density lipoprotein cholesterol (HDL-C) levels and cholesterol excretion are closely associated with the risk of cardiovascular complications. The specific aim of the present study was to investigate the cholesterol lowering effect of mulberry fruit in rats fed a high cholesterol/cholic acid diet. Four-week supplementation with mulberry fruit extract significantly decreased serum and hepatic cholesterol (TC), serum low-density lipoprotein cholesterol (LDL-C), and fecal bile acid levels without changes in body weight and food intake (p < 0.05). Mulberry fruit extract significantly inhibited hepatic sterol-regulatory element binding protein (Srebp) 2 gene expression and upregulated hepatic mRNA levels of liver X receptor alpha (Lxr-α), ATP-binding cassette transporter 5 (Abcg5), and cholesterol 7 alpha-hydroxylase (Cyp7a1), which are involved in hepatic bile acid synthesis and cholesterol metabolism (p < 0.05). In addition, hepatic microRNA-33 expression was significantly inhibited by supplementation of mulberry fruit extract (p < 0.05). These results suggest the involvement of miR-33, its associated hepatic bile acid synthesis, HDL formation, and cholesterol metabolism in mulberry fruit-mediated beneficial effects on serum and hepatic lipid abnormalities.

Reduction of Hepatic Lipogenesis by Loliolide and Pinoresinol from Lysimachia vulgaris via Degrading Liver X Receptors.

The liver X receptors (LXRs) are major regulators of lipogenesis, and their reduced activation by an inhibitor could be a treatment strategy for fatty liver disease. Small molecules originating from dietary food are considered suitable and attractive drug candidates for humans in terms of safety. In this study, an edible plant, Lysimachia vulgaris (LV), used as a traditional and medicinal food in East Asia was evaluated for lipogenesis decreasing effects. Activity-guided fractionation was performed, and the isolated compounds were identified using spectroscopic methods. We conducted in vitro real-time polymerase chain reaction (PCR) and Western blotting as well as histological and biochemical analyses following in vivo treatments. Using a high-fat diet animal model, we confirmed that LV extracts (LVE) decreased lipogenic metabolism and restored liver function to control levels. To identify active components, we conducted activity-guided fractionation and then isolated compounds. Two compounds, loliolide and pinoresinol, were identified in the dichloromethane fraction, and they significantly attenuated the expression levels of lipogenic factors including sterol regulatory element-binding protein (SREBP)-1, stearoyl-CoA desaturase 1 (SCD1), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC). Importantly, loliolide and pinoresinol significantly accelerated the protein degradation of LXRs by enhanced ubiquitination, which inhibited lipogenesis. These results suggest that loliolide and pinoresinol might be potential candidate supplementary treatments for nonalcoholic fatty liver disease (NAFLD) by reducing lipogenesis through increased ubiquitination of LXRs.

Regulation of calcific vascular and valvular disease by nuclear receptors.

PURPOSE OF REVIEW: This review addresses recent developments in studies of lipid regulation of calcific disease of arteries and cardiac valves, including the role of nuclear receptors. The role of lipid-soluble signals and their receptors is timely given the recent evidence and concerns that lipid-lowering treatment may increase the rate of progression of coronary artery calcification, which has been long associated with increased cardiovascular risk. Understanding the mechanisms will be important for interpreting such clinical information. RECENT FINDINGS: New findings support regulation of calcific vascular and valvular disease by nuclear receptors, including the vitamin D receptor, glucocorticoid receptor, nutrient-sensing nuclear receptors (liver X receptor, farnesoid X receptor, and peroxisome proliferator-activated receptors), and sex hormone (estrogen and androgen) receptors. There were two major unexpected findings: first, vitamin D supplementation, which was previously believed to prevent or reduce vascular calcification, showed no cardiovascular benefit in large randomized, controlled trials. Second, both epidemiological studies and coronary intravascular ultrasound studies suggest that treatment with HMG-CoA reductase inhibitors increases progression of coronary artery calcification, raising a question of whether there are mechanically stable and unstable forms of coronary calcification. SUMMARY: For clinical practice and research, these new findings offer new fundamental mechanisms for vascular calcification and provide new cautionary insights for therapeutic avenues.

The fucoidan from the brown seaweed Ascophyllum nodosum ameliorates atherosclerosis in apolipoprotein E-deficient mice.

Hyperlipidemia is a major cause of atherosclerosis. Reverse cholesterol transport (RCT) is believed to attenuate hyperlipidemia and the progression of atherosclerosis. Although fucoidans are reported to have hypolipidemic effects, the underlying mechanisms are unclear. Furthermore, few reports have revealed the anti-atherosclerotic effects and the underlying mechanisms of fucoidans. This study was designed to investigate the anti-atherosclerotic effect and mechanisms of the fucoidan from seaweed A. nodosum. Our results demonstrated that the fucoidan administration ameliorated atherosclerotic lesion and lipid profiles in a dose-dependent manner in the apolipoprotein E-deficient (apoE-/-) mice fed a high-fat diet. In the apoE-/- mice liver, the fucoidan treatment significantly increased the expression of scavenger receptor B type 1 (SR-B1), peroxisome proliferator-activated receptor (PPAR) α and ß, liver X receptor (LXR) α, ATP-binding cassette transporter (ABC) A1 and ABCG8; and markedly decreased the expression of PPARγ and sterol regulatory element-binding protein (SREBP) 1c, but not low-density lipoprotein receptor, proprotein convertase subtilisin/kexin type 9, cholesterol 7 alpha-hydroxylase A1, LXRß and ABCG1. In the small intestine of the apoE-/- mice, the fucoidan treatment significantly reduced the expression of Niemann-Pick C1-like 1 (NPC1L1) and dramatically improved ABCG8 levels. These results demonstrated for the first time that the fucoidan from A. nodosum attenuated atherosclerosis by regulating RCT-related genes and proteins expression in apoE-/- mice. In summary, this fucoidan from A. nodosum may be explored as a potential compound for prevention or treatment of hyperlipidemia-induced atherosclerosis.

Hyperlipidemia Determines Dysfunctional HDL Production and Impedes Cholesterol Efflux in the Small Intestine: Alleviation by Ginger Extract.

SCOPE: To assess the impact of ginger extract (GIN) in stimulating the production of quality HDL and the cholesterol efflux in the small intestine (SI), key processes in the management of hyperlipidemia (HL)-induced hepatic steatosis, and atherosclerosis. METHODS AND RESULTS: Three groups of hamsters are used: (i) N, fed standard diet, (ii) HL, fed high-fat diet for 21 weeks, and (iii) HL-GIN, HL treated with GIN for the last 5 weeks of diet. Apolipoprotein A-I (apoA-I), malondialdehyde-apoA-I (MDA-apoA-I), paraoxonase1 (PON1), and myeloperoxidase (MPO) are measured in plasma and SI. ATP-binding cassette A1 transporter (ABCA1), ABCG5/G8, liver X receptor α/ß (LXRα/ß), peroxisome proliferator-activated receptor γ (PPARγ), and sirtuin1 (SIRT1) are assessed in the SI. Results show that in HL plasma, GIN decreases MDA-apoA-I, MPO/PON1 ratio and increases HDL-cholesterol/total cholesterol. In HL-SI, GIN decreases MDA-apoA-I and MPO, increases ApoA-I, PON1, and ABCA1, and restores cholesterol efflux disturbed by HL (SIRT1-LXRα/ß-PPARγ-ABCG8). GIN administration is associated with the reduction of the aortic valves lipid-deposits. CONCLUSION: In HL conditions, GIN stimulates the functional HDL production by restoring apoA-I quality and quantity through inhibition of the oxidative stress, and increases cholesterol efflux in the SI. These effects are associated with the restoration of SIRT1-LXRα/ß-PPARγ pathway.

Dietary high calories from sunflower oil, sucrose and fructose sources alters lipogenic genes expression levels in liver and skeletal muscle in rats.

INTRODUCTION AND OBJECTIVES: The objectives of this study were to investigate the underlying mechanism of PPARα, LXRα, ChREBP, and SREBP-1c at the level of gene and protein expression with high-energy diets in liver and skeletal muscle. MATERIALS AND METHODS: Metabolic changes with consumption of high fat (Hfat), high sucrose (Hsuc) and high fructose (Hfru) diets were assessed. Levels of mRNA and protein of PPARα, LXRα, ChREBP, and SREBP-1c were investigated. Body weight changes, histological structure of liver and plasma levels of some parameters were also examined. RESULTS: In Hfru group, body weights were higher than other groups (P<0.05). In liver, LXRα levels of Hsuc and Hfru groups were upregulated as 1.87±0.30 (P<0.05) and 2.01±0.29 (P<0.01). SREBP-1c levels were upregulated as 4.52±1.25 (P<0.05); 4.05±1.11 (P<0.05) and 3.85±1.04 (P<0.05) in Hfat, Hsuc, and Hfru groups, respectively. In skeletal muscle, LXRα and SREBP-1c were upregulated as 1.77±0.30 (P<0.05) and 2.71±0.56 (P<0.05), in the Hfru group. Protein levels of ChREBP (33.92±8.84ng/mg protein (P<0.05)) and SREBP-1c (135.16±15.57ng/mg protein (P<0.001)) in liver were higher in Hfru group. In skeletal muscle, LXRα, ChREBP and SREBP-1c in Hfru group were 6.67±0.60, 7.11±1.29 and 43.17±6.37ng/mg, respectively (P<0.05; P<0.01; P<0.05). The rats in Hfru group had the most damaged livers. CONCLUSION: Besides liver, fructose consumption significantly effects skeletal muscle and leads to weight gain, triggers lipogenesis and metabolic disorders.

Moxibustion at CV4 alleviates atherosclerotic lesions through activation of the LXRα/ABCA1 pathway in apolipoprotein-E-deficient mice.

OBJECTIVES: To investigate the anti-atherogenic effect of moxibustion and whether it is mediated through the reverse cholesterol transport process. METHODS: 8-week-old male apolipoprotein E deficient (ApoE-/- knockout) mice were randomly divided into two groups (n=10 per group): atherosclerosis (AS) and AS plus moxibustion (AS+M). C57BL/6J mice of the same background (n=10) were selected as controls. Mice in the AS+M group received indirect moxibustion with an ignited moxa stick held over CV4. Mice of the AS and control groups were restrained in the same holder with an unlit moxa stick held over CV4. All treatments were performed for 20 min per day, 6 days per week for 12 weeks. After the treatment, the mice were euthanased and their serum lipids were measured. The aortic roots and thoracic aortas were collected for haematoxylin and eosin and red oil O staining, respectively, to analyse the atherosclerotic lesions. Expression of adenosine triphosphate binding cassette (ABCA)A1/G1 and liver X receptor α (LXRα) in the thoracic aorta were examined with Western blotting. RESULTS: The moxibustion-treated (AS+M) mice showed a significantly lower plaque area percentage in the aortic root and thoracic aorta, and higher expression of LXRα and ABCA1 in the thoracic aorta compared with the AS mice. No significant differences were found in average lipid area percentage in the thoracic aorta, or ABCG1 expression in the thoracic aorta, between mice in the AS+M and AS groups. CONCLUSION: Moxibustion treatment at CV4 suppressed the progression of atherosclerotic lesions in ApoE-/- mice. The anti-atherogenic effect of moxibustion may be achieved by: (1) regulation of lipid metabolism, and thus prevention of lipid accumulation; and (2) upregulation of LXRα- and ABCA1-mediated cholesterol efflux in the lesion area.