Dehydroepiandrosterone protects against oleic acid-triggered mitochondrial dysfunction to relieve oxidative stress and inflammation via activation of the AMPK-Nrf2 axis by targeting GPR30 in hepatocytes.

Fatty liver hemorrhage syndrome (FLHS) seriously threatens the health and performance of laying hens, and the occurrence and development of FLHS are closely related to oxidative damage and inflammation; thus, diets supplemental with activated substances to relive the oxidative stress and inflammation maybe effectively control the occurrences of FLHS. Dehydroepiandrosterone (DHEA) has beneficial effects in fat-reduction, anti-oxidation and anti-inflammation, and it was widely applied to alleviate multiple metabolic-related diseases; however, there are few reports on whether DHEA can prevent against metabolic-related diseases by modulating oxidative stress and inflammation, especially FLHS in laying hens. Herein, present study aimed to investigate the regulatory actions and potential molecular mechanism of DHEA on inflammation and oxidative stress triggered by oleic acid (OA)-stimulation in primary chicken hepatocytes and chicken hepatocellular carcinoma cell line (LMH). The results showed that DHEA significantly alleviated oxidative stress challenged by OA-stimulation via activation of AMP-activated protein kinase (AMPK)-nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling pathway in hepatocytes, which led to relieving effect of DHEA on inflammatory by inhibiting mitogen-activated protein kinases (MAPKs) and nuclear factor κB (NF-κB) signaling pathways. Mechanistically, we found that the activation of AMPK-Nrf2 signaling pathway by DHEA treatment was mediated by G-protein coupled estrogen receptor (GPR30/GPER) in OA-stimulated hepatocytes. Further investigation found that DHEA activated the GPR30-mediated AMPK-Nrf2 signaling pathways to increase antioxidant capacity and inhibit mitochondrial reactive oxygen species (ROS) overproduction, which thereby inhibiting the activation of ROS-induced MAPK and NF-κB signaling pathways in OA-stimulated hepatocytes. Overall, these data demonstrated that DHEA attenuates the oxidative stress and inflammation triggered by OA-stimulation, and these beneficial effects of DHEA are achieved by activating the GPR30-mediated AMPK-Nrf2 signaling to prevent the impairment of mitochondrial function, and thereby inhibiting the activation of ROS-induced MAPK and NF-κB signaling pathways in hepatocytes. These results revealed the effects and mechanisms of DHEA on oxidative stress and inflammation, and also provide substantial information to support it as a potential nutritional supplement in preventing the occurrences of FLHS in laying hens and other metabolic-related diseases in animals and humans.

Influence of additives on swelling and mucoadhesion properties of glyceryl monooleate liquid crystals

Abstract Liquid crystalline systems of glyceryl monooleate/water are used as drug delivery systems due to their complex structure that controls drug diffusion. Mucoadhesive properties of glyceryl monooleate suggest it can be used for buccal delivery. Using additives is a strategy to modify physical and chemical properties of liquid crystalline systems and optimize their performance as a drug delivery system. However, the presence of additives can significantly alter properties such as phase behavior, swelling and mucoadhesion. Our aim is to investigate the influence of additives on swelling and mucoadhesion of glyceryl monooleate-based liquid crystals, intending them to be used as buccal drug delivery systems. The systems were characterized regarding their mesophases, swelling rate, and mucoadhesion. All the systems studied were able to absorb water and presented mucoadhesion, which is interesting for the development of buccal drug delivery systems. Additives induced phase transitions and affected the swelling performance, while mucoadhesive properties were poorly affected. Propylene glycol increased water uptake, while oleic acid induced the phase transition to the hexagonal phase and reduced the swelling rate. The association of oleic acid (5%) and propylene glycol (10%) resulted in a cubic phase system with strong mucoadhesive properties that can be a potential drug carrier for buccal delivery.

Nicotinamide Mononucleotide Prevents Free Fatty Acid-Induced Reduction in Glucose Tolerance by Decreasing Insulin Clearance.

The NAD-dependent deacetylase SIRT1 improves ß cell function. Accordingly, nicotinamide mononucleotide (NMN), the product of the rate-limiting step in NAD synthesis, prevents ß cell dysfunction and glucose intolerance in mice fed a high-fat diet. The current study was performed to assess the effects of NMN on ß cell dysfunction and glucose intolerance that are caused specifically by increased circulating free fatty acids (FFAs). NMN was intravenously infused, with or without oleate, in C57BL/6J mice over a 48-h-period to elevate intracellular NAD levels and consequently increase SIRT1 activity. Administration of NMN in the context of elevated plasma FFA levels considerably improved glucose tolerance. This was due not only to partial protection from FFA-induced ß cell dysfunction but also, unexpectedly, to a significant decrease in insulin clearance. However, in conditions of normal FFA levels, NMN impaired glucose tolerance due to decreased ß cell function. The presence of this dual action of NMN suggests caution in its proposed therapeutic use in humans.

Intracellular Exposure Dose-Associated Susceptibility of Steatotic Hepatocytes to Metallic Nanoparticles.

Non-alcoholic fatty liver disease (NAFLD), mainly characterized by the accumulation of excess fat in hepatocytes, is the most prevalent liver disorder afflicting ~25% of adults worldwide. In vivo studies have shown that adult rodents with NAFLD were more sensitive to metallic nanoparticles (MNPs) than healthy MNPs. However, due to the complex interactions between various cell types in a fatty liver, it has become a major challenge to reveal the toxic effects of MNPs to specific types of liver cells such as steatotic hepatocytes. In this study, we reported the susceptibility of steatotic hepatocytes in cytotoxicity and the induction of oxidative stress to direct exposures to MNPs with different components (silver, ZrO2, and TiO2 NPs) and sizes (20-30 nm and 125 nm) in an oleic acid (OA) -induced steatotic HepG2 (sHepG2) cell model. Furthermore, the inhibitory potential of MNPs against the process of fatty acid oxidation (FAO) were obvious in sHepG2 cells, even at extremely low doses of 2 or 4 µg/mL, which was not observed in non-steatotic HepG2 (nHepG2) cells. Further experiments on the differential cell uptake of MNPs in nHepG2 and sHepG2 cells demonstrated that the susceptibility of steatotic hepatocytes to MNP exposures was in association with the higher cellular accumulation of MNPs. Overall, our study demonstrated that it is necessary and urgent to take the intracellular exposure dose into consideration when assessing the potential toxicity of environmentally exposed MNPs.

Kaempferol and Kaempferide Attenuate Oleic Acid-Induced Lipid Accumulation and Oxidative Stress in HepG2 Cells.

Nonalcoholic fatty liver disease (NAFLD) is one of the most common liver diseases which lacks ideal treatment options. Kaempferol and kaempferide, two natural flavonol compounds isolated from Hippophae rhamnoides L., were reported to exhibit a strong regulatory effect on lipid metabolism, for which the mechanism is largely unknown. In the present study, we investigated the effects of kaempferol and kaempferide on oleic acid (OA)-treated HepG2 cells, a widely used in vitro model of NAFLD. The results indicated an increased accumulation of lipid droplets and triacylglycerol (TG) by OA, which was attenuated by kaempferol and kaempferide (5, 10 and 20 µM). Western blot analysis demonstrated that kaempferol and kaempferide reduced expression of lipogenesis-related proteins, including sterol regulatory element-binding protein 1 (SREBP1), fatty acid synthase (FAS) and stearoyl-CoA desaturase 1 (SCD-1). Expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT enhancer binding proteins ß (C/EBPß), two adipogenic transcription factors, was also decreased by kaempferol and kaempferide treatment. In addition, western blot analysis also demonstrated that kaempferol and kaempferide reduced expression of heme oxygenase-1 (HO-1) and nuclear transcription factor-erythroid 2-related factor 2 (Nrf2). Molecular docking was performed to identify the direct molecular targets of kaempferol and kaempferide, and their binding to SCD-1, a critical regulator in lipid metabolism, was revealed. Taken together, our findings demonstrate that kaempferol and kaempferide could attenuate OA-induced lipid accumulation and oxidative stress in HepG2 cells, which might benefit the treatment of NAFLD.

Lipotoxic stress alters the membrane lipid profile of extracellular vesicles released by Huh-7 hepatocarcinoma cells.

Extracellular vesicles (EVs) are well-known mediators in intercellular communication playing pivotal roles in promoting liver inflammation and fibrosis, events associated to hepatic lipotoxicity caused by saturated free fatty acid overloading. However, despite the importance of lipids in EV membrane architecture which, in turn, affects EV biophysical and biological properties, little is known about the lipid asset of EVs released under these conditions. Here, we analyzed phospholipid profile alterations of EVs released by hepatocarcinoma Huh-7 cells under increased membrane lipid saturation induced by supplementation with saturated fatty acid palmitate or Δ9 desaturase inhibition, using oleate, a nontoxic monounsaturated fatty acid, as control. As an increase of membrane lipid saturation induces endoplasmic reticulum (ER) stress, we also analyzed phospholipid rearrangements in EVs released by Huh-7 cells treated with thapsigargin, a conventional ER stress inducer. Results demonstrate that lipotoxic and/or ER stress conditions induced rearrangements not only into cell membrane phospholipids but also into the released EVs. Thus, cell membrane saturation level and/or ER stress are crucial to determine which lipids are discarded via EVs and EV lipid cargos might be useful to discriminate hepatic lipid overloading and ER stress.

A network pharmacology approach: Inhibition of the NF-κB signaling pathway contributes to the NASH preventative effect of an Oroxylum indicum seed extract in oleic acid-stimulated HepG2 cells and high-fat diet-fed rats.

BACKGROUND: The incidence of nonalcoholic fatty liver disease (NAFLD), especially nonalcoholic steatohepatitis (NASH), has significantly increased in recent years and has become an important public health issue. However, no U.S. Food and Drug Administration (FDA)-approved first-line drug is currently available for the treatment of NAFLD and NASH; therefore, research on new drugs is currently a hot topic. Oroxylum indicum (Linn.) Kurz is extensively distributed in South China and South Asia and has many biological activities. However, its effects on NAFLD or even NASH and the corresponding mechanisms are still not clear. PURPOSE: To investigate the effect and mechanism of O. indicum seed extract (OISE) on preventing anti-inflammatory action in the progression from simple nonalcoholic fatty liver (NAFL) to NASH. METHODS: A network pharmacology method to construct ingredient-target networks and the protein-protein interaction (PPI) network of OISE in NASH were constructed for topological analyses and hub-target screening. Enrichment analyses were performed to identify the critical biological processes and signaling pathways. Simultaneously, in vitro and in vivo experiments investigated the effect and mechanism of OISE, baicalein, and chrysin on inflammation by biochemical indicator detection, luciferase reporters, pathological staining, and immunoblotting in oleic acid-stimulated HepG2 cells or in high-fat diet-fed rats. RESULTS: The network pharmacology showed that OISE prevented the development and progression of NAFL into NASH through various pathways and targets and that the nuclear factor NF-κB (NF-κB) pathway regulated by baicalein and chrysin played an important role in the treatment of NASH. In in vitro experiments, we further showed that OISE and its ingredients, namely, baicalein and chrysin, all improved the inflammatory status in oleic acid-stimulated HepG2 cells, inhibited the nuclear transcriptional activities of NF-κB, increased the IκB level, and decreased the phosphorylation level of NF-κB. Furthermore, in a high-fat diet-induced NASH model in rats, we also showed that OISE prevented the development and progression of NASH by inhibiting the nuclear transcriptional activity of NF-κB. CONCLUSION: OISE suppressed inflammatory responses and prevented the development and progression of NAFL into NASH through inhibition of the nuclear transcriptional activity of NF-κB. OISE may be used to treat NAFLD through many functions, including an increase in insulin sensitivity, a decrease in lipid accumulation in the liver, suppression of inflammation, and clearance of free radicals.

Isosorbide Di-(Linoleate/Oleate) Stimulates Prodifferentiation Gene Expression to Restore the Epidermal Barrier and Improve Skin Hydration.

The breakdown of the epidermal barrier and consequent loss of skin hydration is a feature of skin aging and eczematous dermatitis. Few treatments, however, resolve these underlying processes to provide full symptomatic relief. In this study, we evaluated isosorbide di-(linoleate/oleate) (IDL), which was generated by esterifying isosorbide with sunflower fatty acids. Topical effects of IDL in skin were compared with those of ethyl linoleate/oleate, which has previously been shown to improve skin barrier function. Both IDL and ethyl linoleate/oleate downregulated inflammatory gene expression, but IDL more effectively upregulated the expression of genes associated with keratinocyte differentiation (e.g., KRT1, GRHL2, SPRR4). Consistent with this, IDL increased the abundance of epidermal barrier proteins (FLG and involucrin) and prevented cytokine-mediated stratum corneum degradation. IDL also downregulated the expression of unhealthy skin signature genes linked to the loss of epidermal homeostasis and uniquely repressed an IFN-inducible coexpression module activated in multiple skin diseases, including psoriasis. In a double-blind, placebo-controlled trial enrolling females with dry skin, 2% IDL lotion applied over 2 weeks significantly improved skin hydration and decreased transepidermal water loss (NCT04253704). These results demonstrate mechanisms by which IDL improves skin hydration and epidermal barrier function, supporting IDL as an effective intervention for the treatment of xerotic pruritic skin.

(-)-Hydroxycitric Acid Alleviates Oleic Acid-Induced Steatosis, Oxidative Stress, and Inflammation in Primary Chicken Hepatocytes by Regulating AMP-Activated Protein Kinase-Mediated Reactive Oxygen Species Levels.

Nonalcoholic fatty liver disease (NAFLD) is one of the most complex liver diseases in the world, which is characterized by hepatic steatosis, oxidative stress, inflammation, and apoptosis. (-)-Hydroxycitric acid [(-)-HCA] can regulate obesity in different animals, while whether this beneficial effect of (-)-HCA can alleviate the NAFLD and its mechanism is unclear. Hence, this study aimed to determine the potential actions and mechanisms of (-)-HCA on NAFLD in oleic acid (OA)-induced hepatocytes. We found that (-)-HCA effectively improved OA-induced hepatic steatosis by regulating the expression level of fat metabolism key factors, which was achieved by activating AMP-activated protein kinase (AMPK) signaling in hepatocytes. Importantly, activated AMPK alleviates mitochondrial disorder via the peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α)-nuclear transcription factor 1 (NRF-1)-mitochondrial transcription factor A (TFAM) pathway, then reduces reactive oxygen species production, and blocks the activation of p38 MAPK-NF-κB pathway in OA-induced hepatocytes. These results not only provide a theoretical basis for the occurrence and development of NAFLD but also offer compelling evidence for prevention of NAFLD supplemental with (-)-HCA.

S-petasin inhibits lipid accumulation in oleic acid-induced HepG2 cells through activation of the AMPK signaling pathway.

Nonalcoholic fatty liver disease (NAFLD) has become one of the most common medical problems. Inhibition of lipogenesis and promotion of lipolysis are two ways to prevent NAFLD. In this study, oleic acid-induced HepG2 cells are used as a NAFLD cell model to test whether s-petasin exerts inhibition of lipogenesis and promotion of the lipolysis effect. The results showed that s-petasin significantly inhibited the lipid level in oleic acid-induced HepG2 cells. Moreover, results showed that the triacylglycerol level was reduced by s-petasin in oleic acid-induced HepG2 cells. Western blot assay revealed that s-petasin stimulated phosphorylation of AMPKα and ACCα. The results also demonstrated that s-petasin can inhibit lipogenesis and enhance triacylglycerol turnover by down-regulation of FAS and SCD-1 and up-regulation of ATGL and HSL through the AMPK signaling-dependent regulation of transcriptional factors, FKHR and SREBP-1. This in vitro study indicates that s-petasin has potential as a candidate compound for NAFLD therapy.

Docosahexaenoic acid and oleic acid induce altered DNA methylation of individual CpG loci in Jurkat T cells.

Docosahexaenoic acid (DHA, 22:6n-3) and oleic acid (18:1n-9) can alter the DNA methylation of individual CpG loci in vivo and in vitro, although the targeting mechanism is unknown. We tested the hypothesis that the targeting of altered methylation is associated with putative transcription factor response elements (pTREs) proximal to modified loci. Jurkat cells were treated with 22:6n-3 or 18:1n-9 (both 15 µM) for eight days and DNA methylation measured using the MethylationEPIC 850K array. 1596 CpG loci were altered significantly (508 hypermethylated) by 22:6n-3 and 563 CpG loci (294 hypermethylated) by 18:1n-9. 78 loci were modified by both fatty acids. Induced differential methylation was not modified by the PPARα antagonist GW6471. DNA sequences proximal to differentially methylated CpG loci were enriched in zinc-finger pTREs. These findings suggest that zinc-finger-containing transcription factors may be involved in targeting altered DNA methylation modifying processes induced by fatty acids to individual CpG loci.

Histopathological Evidence of Multiple Organ Damage After Simulated Aeromedical Evacuation in a Swine Acute Lung Injury Model.

INTRODUCTION: Rapid aeromedical evacuation (AE) is standard of care in current conflicts. However, not much is known about possible effects of hypobaric conditions. We investigated possible effects of hypobaria on organ damage in a swine model of acute lung injury. METHODS: Lung injury was induced in anesthetized swine via intravenous oleic acid infusion. After a stabilization phase, animals were subjected to a 4 hour simulated AE at 8000 feet (HYPO). Control animals were kept at normobaria. After euthanasia and necropsy, organ damage was assessed by combined scores for hemorrhage, inflammation, edema, necrosis, and microatelectasis. RESULTS: Hemodynamic, neurological, or hematologic measurements were similar prior to transport. Hemodynamic instability became apparent during the last 2 hours of transport in the HYPO group. Histological injury scores in the HYPO group were higher for all organs (lung, kidney, liver, pancreas, and adrenal glands) except the brain, with the largest difference in the lungs (P < 0.001). CONCLUSIONS: Swine with mild acute lung injury subjected to a 4 hour simulated AE showed more injury to most organs and, in particular, to the lungs compared with ground transport. This may exacerbate otherwise subclinical pathology and, eventually, manifest as abnormalities in gas exchange or possibly end-organ function.

Associations between dietary oleic acid and linoleic acid and depressive symptoms in perimenopausal women: The Study of Women's Health Across the Nation.

OBJECTIVES: The aim of this study was to review the association of dietary intake of oleic and linoleic acids (OA and LA, respectively) with depressive symptoms in perimenopausal women. METHODS: This cross-sectional study used data from the Study of Women's Health Across the Nation (SWAN). Linear and logistic regressions and restricted cubic spline models were performed to examine the association of intake of OA and LA with depression. RESULTS: We included 2793 women 42 to 52 y of age in the present study. Intake of the two acids was positively associated with the Center for Epidemiologic Studies Depression Scale (CES-D) scores in unadjusted and age-, race/ethnicity-, total family income- and education-adjusted linear regression model. The fully adjusted regression coefficients were ß = 0.089 and ß = 0.145 for oleic and linoleic acid intake, respectively. OA and LA intake was positively associated with depressive symptoms (CES-D score ≥16) in unadjusted and age-, race/ethnicity-, total family income- and education-adjusted logistic regression model. The fully adjusted odds ratios (ORs) with 95% confidence intervals (CIs) of depressive symptoms were 1.994 (1.298-3.063) and 1.592 (1.047-2.421) for the highest versus lowest quartile of intake of OA and LA, respectively. CONCLUSION: Intake of OA and LA may be positively associated with depressive symptoms in perimenopausal women.

Effects of Eriobotrya japonica Water Extract on Alcoholic and Nonalcoholic Fatty Liver Impairment.

The aim of this study was to investigate the potential protective effects of the hot water extract of Eriobotrya japonica (EJW) on EtOH- or free fatty acid (FFA)-induced fatty liver injury in vitro. HepG2/2E1 cells were exposed to EtOH and HepG2 cells were exposed to a mixture of FFAs (oleic acid:palmitic acid, 2:1) to stimulate oxidative stress and to induce lipid accumulation, respectively. Antioxidant activity was significantly increased and lipid accumulation was inhibited in cells pretreated with EJW compared to those in cells exposed to EtOH or FFA only. Also, 5'adenosine monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC) phosphorylations were considerably increased, indicating activation of AMPK. Furthermore, EJW reduced the messenger RNA (mRNA) expression of lipogenesis-associated factors such as ACC, sterol regulatory element binding protein-1c (SREBP-1c), and fatty acid synthase (FAS), and increased mRNA expression related to components of the fatty acid ß-oxidation pathway, such as AMPK, carnitine palmitoyltransferase 1 (CPT-1), and peroxisome proliferator-activated receptor alpha (PPARα). These results suggest that EJW possessed potential preventive effects against both EtOH- and FFA-induced fatty liver disease by alleviation of oxidative stress and lipid accumulation in hepatocytes.

MicroRNA-205 ameliorates lipid accumulation in non-alcoholic fatty liver disease through targeting NEU1.

OBJECTIVE: The aim of this study was to explore the role of miR-205 in non-alcoholic fatty liver disease (NAFLD) and explore the underlying mechanism. MATERIALS AND METHODS: High-fat diet (HFD) mice were used as an in vitro model of NAFLD. HepG2 and primary hepatocytes (PH) cells were treated with oleic acid (OA) and considered as in vitro models of NAFLD. qRT-PCR (quantitative real time polymerase chain reaction) and Western blot were respectively employed to investigate mRNA expression and protein expression level. Further analysis was then applied to analyze the underlying mechanisms. Livers were histologically examined using hematoxylin and eosin (H&E) and Oil Red O staining. TargetScan analysis and Luciferase assay were used to identify the target of miR-205. RESULTS: MiR-205 was upregulated and NEU1 was downregulated in both HFD-fed mice and OA-treated HepG2 and PH cells. The overexpression of miR-205 caused the decreased weight of body and liver, downregulation of liver triglyceride, and resulted in the enhancement of glycerol concentration, and finally suppressed lipid accumulation. In addition, the TargetScan analysis and Luciferase assay identified neuraminidase 1 (NEU1) as a novel target of miR-205. In vivo study suggested that the knockdown of NEU1 ameliorated lipid accumulation. Finally, the in vitro investigation showed that the overexpression of miR-205 alleviated lipid accumulation in OA-induced HepG2 and PH cells by targeting NEU1. CONCLUSIONS: Results revealed that miR-205 facilitated lipid accumulation by inhibiting NEU1 in NAFLD, suggesting that miR-205 might be a potential target for the therapeutic strategy for NAFLD.

Evaluation of cytotoxicity and genotoxicity induced by oleic acid-coated iron oxide nanoparticles in human astrocytes.

Iron oxide nanoparticles (ION) are gaining importance as diagnostic and therapeutic tool of central nervous system diseases. Although oleic acid-coated ION (O-ION) have been described as stable and biocompatible, their potential neurotoxicity was scarcely evaluated in human nervous cells so far. The primary aim of this work was to assess the molecular and cellular effects of O-ION on human astrocytes (A172 cells) under different experimental conditions. An extensive set of cyto- and genotoxicity tests was carried out, including lactate dehydrogenase release assay, cell cycle alterations, and cell death production, as well as comet assay, γH2AX assay, and micronucleus (MN) test, considering also iron ion release capacity and alterations in DNA repair ability. Results showed a moderate cytotoxicity related to cell cycle arrest and cell death promotion, regardless of serum presence. O-ION induced genotoxic effects, namely primary DNA damage, as detected by the comet assay and H2AX phosphorylation, but A172 cells were able to repair this particular damage because no chromosome alterations were found (confirmed by MN test results). Accordingly, no effects on the DNA repair ability were observed. The presence of serum proteins did not influence O-ION toxicity. Iron ions released from the O-ION surface seemed not to be responsible for the cytotoxic and genotoxic effects observed. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

12-hydroxy oleic acid impairs endothelium-dependent vasorelaxation.

Diesel and biodiesel emissions exposures reduce vascular responsiveness in vivo, but the components of PM responsible for this effect are poorly understood. Fatty acids (FAs) represent a significant fraction of the compounds that make up organic combustion by-products, and may be involved in vascular responses following inhalation. It was hypothesized that vascular tissue exposed to a model FA might impair responses to vasoactive agonists ex vivo. Rat aortic rings were exposed to oleic acid or 12-hydroxy oleic acid and responses determined by myography. 12-Hydroxy oleic acid was found to significantly reduce endothelium-dependent vasodilation at sub-cytotoxic concentrations. This approach demonstrates the potential for FAs, especially oxidized forms, to play a role in the vascular responses observed following air pollution exposure.

Tetrahydrocurcumin ameliorates free fatty acid-induced hepatic steatosis and improves insulin resistance in HepG2 cells.

Elevated levels of free fatty acids (FFAs) in the liver, resulting from either increased lipolysis or imbalanced FFAs flux, is a key pathogenic factor of hepatic steatosis. This study was conducted to examine the therapeutic effect of tetrahydrocurcumin (THC), a naturally occurring curcuminoid and a metabolite of curcumin, on oleic acid (OA)-induced steatosis in human hepatocellular carcinoma cells and to elucidate the underlying mechanism. HepG2 cells were incubated with OA to induce steatosis, and then treated with various concentrations of THC. The results showed that THC treatment significantly decreased lipid accumulation in OA-treated HepG2 cells, possibly, by inhibiting the expression of the lipogenic proteins, sterol regulatory element-binding protein 1 (SREBP-1c), peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid synthase (FAS), and fatty acid-binding protein 4 (FABP4). Moreover, THC attenuated OA-induced hepatic lipogenesis in an adenosine monophosphate-activated protein kinase (AMPK)-dependent manner, which was reversed by pretreatment with an AMPK inhibitor. THC promoted lipolysis and upregulated the expression of genes involved in ß-oxidation. Glucose uptake and insulin signaling impaired in HepG2 cells incubated with OA were abated by THC treatment, including phosphorylation of the insulin receptor substrate 1 (IRS-1)/phosphoinositide 3-kinase (PI3K)/Akt and downstream signaling pathways, forkhead box protein O1 (FOXO1) and glycogen synthase kinase 3 ß (GSK3ß), which are involved in gluconeogenesis and glycogen synthesis, respectively. Altogether, these results demonstrated the novel therapeutic benefit of THC against hepatic steatosis and, consequently, a potential treatment for non-alcoholic fatty liver disease (NAFLD).

Oral administration of lipid oil-in-water emulsions performed with synthetic or protein-type emulsifiers differentially affects post-prandial triacylglycerolemia in rats.

In this study, we compared the impact of administration of size-calibrated lipid emulsions prepared with either synthetic or natural emulsifiers on the post-absorptive plasma triacylglycerol responses in rats. We did this using four types of size-calibrated (10 µm diameter) and metastable (3 days) emulsions with 20% of an oleic acid-rich sunflower oil and 1% of either synthetic emulsifiers (Tween 80 or sodium 2-stearoyl-lactylate) or two proteins (ß-lactoglobulin or sodium caseinate). An oral fat tolerance test was performed in fasted rats by oral administration of each of these formulations in continuous or emulsified forms. Kinetic parameters (AUC0-inf., AUC0-6h, Cmax, Tmax, and T1/2) for the description of the plasma triacylglycerol responses were calculated. AUC0-6h and AUC0-inf. calculated for the protein groups were significantly lower than those of the control and the synthetic groups. These lower values were associated with significant decreases in the Cmax, exacerbated by the emulsion form and with marked decreases in the Tmax as compared to the control group. T1/2 values were differentially affected by the lipid administration forms and by the nature of the emulsifiers. As compared with the control group, T1/2 was largely increased in the sodium stearoyl-2-lactylate group, but on the contrary, largely lowered in the casein group. We concluded that the use of proteins as natural emulsifiers in lipid emulsions decreased the magnitude of post-prandial triacylglycerolemia for the same amount of ingested lipids, when the emulsion size is controlled for. Proteins could be a promising alternative to the widespread use of synthetic emulsifiers in the food industry.

Discovery of Potential Inhibitors of Squalene Synthase from Traditional Chinese Medicine Based on Virtual Screening and In Vitro Evaluation of Lipid-Lowering Effect.

Squalene synthase (SQS), a key downstream enzyme involved in the cholesterol biosynthetic pathway, plays an important role in treating hyperlipidemia. Compared to statins, SQS inhibitors have shown a very significant lipid-lowering effect and do not cause myotoxicity. Thus, the paper aims to discover potential SQS inhibitors from Traditional Chinese Medicine (TCM) by the combination of molecular modeling methods and biological assays. In this study, cynarin was selected as a potential SQS inhibitor candidate compound based on its pharmacophoric properties, molecular docking studies and molecular dynamics (MD) simulations. Cynarin could form hydrophobic interactions with PHE54, LEU211, LEU183 and PRO292, which are regarded as important interactions for the SQS inhibitors. In addition, the lipid-lowering effect of cynarin was tested in sodium oleate-induced HepG2 cells by decreasing the lipidemic parameter triglyceride (TG) level by 22.50%. Finally. cynarin was reversely screened against other anti-hyperlipidemia targets which existed in HepG2 cells and cynarin was unable to map with the pharmacophore of these targets, which indicated that the lipid-lowering effects of cynarin might be due to the inhibition of SQS. This study discovered cynarin is a potential SQS inhibitor from TCM, which could be further clinically explored for the treatment of hyperlipidemia.