Triglyceride Accumulation In Hepatocytes Research Articles

The role of differentially expressed genes and immune cell infiltration in the progression of nonalcoholic steatohepatitis (NASH) to hepatocellular carcinoma (HCC): a new exploration based on bioinformatics analysis

Nonalcoholic fatty liver disease (NAFLD) is a spectrum of chronic liver disease characterized. The condition ranges from isolated excessive hepatocyte triglyceride accumulation and steatosis (nonalcoholic fatty liver (NAFL), to hepatic triglyceride accumulation plus inflammation and hepatocyte injury (nonalcoholic steatohepatitis (NASH)) and finally to hepatic fibrosis and cirrhosis and/or hepatocellular carcinoma (HCC). However, the mechanism driving this process is not yet clear. Obtain sample microarray from the GEO database. Extract 6 healthy liver samples, 74 nonalcoholic hepatitis samples, 8 liver cirrhosis samples, and 53 liver cancer samples from the GSE164760 dataset. We used the GEO2R tool for differentially expressed genes (DEGs) analysis of disease progression (nonalcoholic hepatitis healthy group, cirrhosis nonalcoholic hepatitis group, and liver cancer cirrhosis group) and necroptosis gene set. Gene set variation analysis (GSVA) is used to evaluate the association between biological pathways and gene features. The STRING database and Cytoscape software were used to establish and visualize protein-protein interaction (PPI) networks and identify the key functional modules of DEGs, drawn factor-target genes regulatory network. Gene Ontology (GO) and KEGG pathway enrichment analyses of DEGs were also performed. Additionally, immune infiltration patterns were analyzed using the cibersort, and the correlation between immune cell-type abundance and DEGs expression was investigated. We further screened and obtained a total of 152 intersecting DEGs from three groups. 23 key genes were obtained through the MCODE plugin. Transcription factors regulating common differentially expressed genes were obtained in the hTFtarget database, and a TF target network diagram was drawn. There are 118 nodes, 251 edges, and 4 clusters in the PPI network. The key genes of the four modules include METAP2, RPL14, SERBP1, EEF2; HR4A1; CANX; ARID1A, UBE2K. METAP2, RPL14, SERBP1 and EEF2 was identified as the key hub genes. CREB1 was identified as the hub TF interacting with those gens by taking the intersection of potential TFs. The types of key gene changes were genetic mutations. It can be seen that the incidence of key gene mutations is 1.7% in EEF2, 0.8% in METAP2, and 0.3% in RPL14, respectively. Finally, We found that the most significant expression differences of the immune infiltrating cells among the three groups, were Tregs and M2, M0 type macrophages. We identified four hub genes METAP2, RPL14, SERBP1 and EEF2 being the most closely with the process from NASH to cirrhosis to HCC. It is beneficial to examine and understand the interaction between hub DEGs and potential regulatory molecules in the process. This knowledge may provide a novel theoretical foundation for the development of diagnostic biomarkers and gene-related therapy targets in the process.

ALDH2 deficiency exacerbates MCD-diet induced MASLD by modulating bile acid metabolism

Aldehyde dehydrogenase 2 (ALDH2), an acetaldehyde dehydrogenase in mitochondria, is primarily responsible for metabolizing alcohol-derived acetaldehyde and other endogenous aldehydes. Inactivating ALDH2 rs671 polymorphism is found in up to 8 % of the global population and 40 % of the East Asian population. Recent studies have shown that rs671 SNP mutation in the human ALDH2 gene is associated with an increased risk of metabolic dysfunction-associated steatotic liver diseases (MASLD), but the mechanism remains unclear. Here, we identify the role of ALDH2 in MASLD. Firstly, ALDH2 activity was lower in MASLD patients and the methionine-choline deficiency (MCD) diet induced MASLD model. Secondly, activation of ALDH2 activity with Alda-1 (ALDH2 agonist) attenuated MCD-diet induced hepatic triglyceride (TG) accumulation and steatosis, whereas the opposite result was observed with cyanamide (CYA, ALDH2 inhibitor). Furthermore, ALDH2 deficiency exacerbated hepatic steatosis, inflammation, and fibrosis in the MCD-diet induced mice. RNA sequencing (RNA-seq) revealed that oxysterol 7-α hydroxylase (Cyp7b1) and the related metabolic pathway significantly changed in the MCD-diet challenged ALDH2−/− mice. In ALDH2−/− mice, the expression of Cyp7b1 was downregulated and FXR/SHP signaling was inhibited, reducing the alternative bile acid (BA) synthetic pathway. In our in vitro experiments, knockdown of ALDH2 exacerbated TG accumulation in hepatocytes, whereas the opposite result was observed with overexpression of ALDH2. Moreover, chenodeoxycholic acid (CDCA) rescued ALDH2 downregulation induced TG accumulation in hepatocytes. Our study reveals that ALDH2 attenuates hepatocyte steatosis by regulating the alternative BA synthesis pathway, and ALDH2 may serve as a potential target for the treatment of MASLD.

Thermoneutrality or standard temperature: is there an ideal housing temperature to study the antisteatotic effects of green tea in obese mice?

Metabolic-associated fatty liver disease (MAFLD) is a condition characterized by excessive accumulation of triglycerides in hepatocytes, currently considered the number one cause of chronic liver disease. MAFLD is strongly associated with obesity, type 2 diabetes, hyperlipidaemia, and hypertension. Emphasis has been placed on the use of green tea (GT), produced from the Camellia sinensis plant, rich in antioxidants as polyphenols and catechins, on obesity and MAFLD treatment/prevention. Studies carried out in rodent models housed at a standard temperature (ST, 22°C) are being questioned as ST is a determining factor on generating changes in the physiology of immune response, and energy metabolism. On the other hand, it seems that thermoneutrality (TN, 28°C) represents a closer parallel to human physiology. In this perspective, we investigated the effects of GT (500 mg/kg of body weight, over 12 weeks, 5 days/week) by comparing mice housed at ST or TN in a model of MAFLD of diet-induced obese males C57Bl/6 mice. We show that the liver phenotype at TN exhibits a more severe MAFLD while GT ameliorates this condition. In parallel, GT restores the expression of genes involved in the lipogenic pathway, regardless of temperature, with slight modifications in lipolysis/fatty acid oxidation. We observed an increase promoted by GT in PPARα and PPARγ proteins independently of housing temperature and a dual pattern of bile acid synthesis. Thus, animals' conditioning temperature is a key factor that can interfere in the results involving obesity and MAFLD, although GT has beneficial effects against MAFLD independently of the housing temperature of mice.

A Comprehensive Insight into the Effect of Berberine on Nonalcoholic Fatty Liver Disease (NAFLD): A Systematic Review

Hepatic dysfunction is primarily caused by nonalcoholic fatty liver disease (NAFLD). Recently, berberine (BBR) has attracted researchers’ interest with its hepatic protective property. A systematic review was conducted to evaluate the effects of BBR and its mechanisms of action in the management of NAFLD and its complications. The guidelines of the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) statements were applied to perform the study. Embase, Web of Science, Google Scholar, Science Direct, PubMed, ProQuest, and Scopus databases were searched up until March 2023. According to the inclusion criteria, finally, 65 studies were entered into the study. The evidence provided in the study revealed that BBR could regulate the development of NAFLD via several mechanisms of action namely lowering body weight, modulating lipid and glucose metabolism, and reducing inflammation and oxidative stress (OS). The current systematic review demonstrated the beneficial effects of BBR on NAFLD and its associated metabolic disorders including dyslipidemia, obesity, and insulin resistance through regulating lipid metabolism, facilitating β-oxidation of fatty acids, and mitigating the accumulation of triglycerides in hepatocytes. These beneficial effects make BBR a potential therapeutic approach and an efficient agent in the management of NAFLD and its related risk factors. There is an insufficient number of clinical trials addressing the effects of BBR in humans, so conducting more human research in the future is recommended.

Hepatic triglyceride content is intricately associated with numerous metabolites and biochemical pathways.

Non-alcoholic fatty liver disease (NAFLD) is characterized by the pathological accumulation of triglycerides in hepatocytes and is associated with insulin resistance, atherogenic dyslipidaemia and cardiometabolic diseases. Thus far, the extent of metabolic dysregulation associated with hepatic triglyceride accumulation has not been fully addressed. In this study, we aimed to identify metabolites associated with hepatic triglyceride content (HTGC) and map these associations using network analysis. To gain insight in the spectrum of metabolites associated with hepatic triglyceride accumulation, we performed a comprehensive plasma metabolomics screening of 1363 metabolites in apparently healthy middle aged (age 45-65) individuals (N = 496) in whom HTGC was measured by proton magnetic resonance spectroscopy. An atlas of metabolite-HTGC associations, based on univariate results, was created using correlation-based Gaussian graphical model (GGM) and genome scale metabolic model network analyses. Pathways associated with the clinical prognosis marker fibrosis 4 (FIB-4) index were tested using a closed global test. Our analyses revealed that 118 metabolites were univariately associated with HTGC (p-value <6.59 × 10-5 ), including 106 endogenous, 1 xenobiotic and 11 partially characterized/uncharacterized metabolites. These associations were mapped to several biological pathways including branched amino acids (BCAA), diglycerols, sphingomyelin, glucosyl-ceramide and lactosyl-ceramide. We also identified a novel possible HTGC-related pathway connecting glutamate, metabolonic lactone sulphate and X-15245 using the GGM network. These pathways were confirmed to be associated with the FIB-4 index as well. The full interactive metabolite-HTGC atlas is provided online: https://tofaquih.github.io/AtlasLiver/. The combined network and pathway analyses indicated extensive associations between BCAA and the lipids pathways with HTGC and the FIB-4 index. Moreover, we report a novel pathway glutamate-metabolonic lactone sulphate-X-15245 with a potential strong association with HTGC. These findings can aid elucidating HTGC metabolomic profiles and provide insight into novel drug targets for fibrosis-related outcomes.

Rhynchophylline relieves nonalcoholic fatty liver disease by activating lipase and increasing energy metabolism.

Hepatic fat metabolism may be altered in the context of overnutrition and obesity, often resulting in the accumulation of triglycerides in hepatocytes and leading to nonalcoholic fatty liver disease (NAFLD). Natural plant alkaloids have demonstrated great potential for the prevention and treatment of NAFLD. However, the role of rhynchophylline (RHY) in lipid metabolism is not clear. We explored the role of RHY in lipid metabolism in cells treated with oleic and palmitic acids to mimic high-fat diet (HFD) conditions. RHY attenuated oleic and palmitic acid-induced increases in triglyceride accumulation in HepG2, AML12, and LMH cells. RHY also increased energy metabolism and reduced oxidative stress. We further investigated the effect of RHY on hepatic lipid metabolism in mice fed an HFD including 40mg/kg RHY. RHY alleviated hepatic steatosis, reduced fat deposition, promoted energy metabolism, and improved glucose metabolism. We investigated the mechanism responsible for this activity by docking with key proteins of lipid metabolism disorders using Discovery Studio software, which showed that RHY interacted well with lipases. Finally, we found that adding RHY promoted lipase activity and lipolysis. In conclusion, RHY ameliorated HFD-induced NAFLD and its complications by increasing lipase activity.

Rewiring of catecholamine-induced calcium signalling is an early event in non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is a global health problem without approved pharmacological treatment (Riazi et al., 2022). Mechanistically, excessive accumulation of triglycerides in hepatocytes due to increased de novo lipogenesis and decreased β-oxidation constitutes an early defining feature in the pathogenesis of NAFLD. Emerging evidence of the last 20 years assigned a central role in the regulation of hepatic energy homeostasis to calcium signalling (Oliva-Vilarnau et al., 2018). However, information about molecular events preceding the onset of hepatic steatosis are limited. The study by Brumer et al. (2023) convincingly demonstrates changes in catecholamine-induced inositol 1,4,5-trisphosphate (IP3) production and calcium signalling in mouse liver after short-term exposure to high fat diet (HFD) before the apparition of histological changes. Lying at the root of these early changes are liver-resident alpha-1B adrenergic receptors (α1BARs) that play a role in glycaemic control, as well as carbohydrate and lipid homeostasis. α1BARs are G protein-coupled receptors (GPCRs) that activate Gαq/11 following the binding of catecholamines such as norepinephrine. Once active, Gαq/11 kicks off a signalling cascade involving phospholipase C (PLC) that is directly involved in the production of IP3 and diacylglycerol (DAG) from phosphatidylinositol 4,5-bisphosphate. Then, IP3 diffuses to the endoplasmic reticulum where it binds the IP3 receptor resulting in the mobilization of calcium, an important second messenger in human physiology. The reduction in calcium mobilization upon HFD did not result from an inhibition of the sarco/endoplasmic reticulum calcium ATPase (SERCA) or store-operated Ca2⁺ channel (SOC) activity. Nor was any difference observed in the expression or distribution of the key signalling components α1BAR, Gαq, PLCβ3, IP3R, SERCA. Instead, Brumer et al. (2023) showed that short-term exposure to HFD affected the amount of IP3 that is generated by PLC, which results in lower IP3R activity and limited release of calcium from intracellular stores. Taken together, these findings shed new light on the early events that lead to NAFLD and may facilitate the development of therapeutics that rescue this hormone-induced calcium signalling axis. However, further work is needed to address the molecular basis for the decrease in IP3 production. One possibility could be a reduced ability of α1BARs to efficiently activate Gαq/11. Although the expression and distribution of α1BARs and Gαq/11 remained unchanged after short-term HFD, differences in membrane fatty acid composition can allosterically affect the ability of GPCRs to effectively exchange the GDP in the Gα subunit with GTP (Dawaliby et al., 2016). This would result in fewer active GTPGαq/11 available to bind PLC. Similarly, membrane lipid composition can affect the localization of PLC and the availability of calcium can affect its catalytic activity. Yet another explanation could come from the generation of DAG through hepatic lipogenesis that activates novel protein kinase C (PKC) isoforms in the absence of calcium mobilization, resulting in PKC-dependent desensitization of GPCR-dependent calcium signalling. Moving forward, it will be important to show that the observed phenomena also occur in human hepatocytes in order to narrow the translational gap. Of relevance in this context could be the wealth of organotypic hepatocyte culture methods that have emerged in recent years, which allow the accurate emulation of hepatic steatosis and its progression to inflammation and fibrosis (Ramos et al., 2022). Although not specifically evaluated yet, their overall phenotypic and molecular resemblance to steatotic liver fuels hopes that also hormonally controlled Ca2⁺ oscillations are preserved in these systems. Combined, the finding that high-fat diet rapidly curbs GPCR-dependent PLC activation, resulting in perturbed Ca2⁺ transients and suppressed propagation of trans-lobular Ca2⁺ waves, opens new avenues for the pharmacological exploration of new mechanisms that target NAFLD onset. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. VML is co-founder, CEO and a shareholder of HepaPredict AB, as well as chairman of the board and shareholder of PersoMedix AB. SCW declares no competing interests. S.W. and V.L. were responsible for the conception or design of the work, drafting the work or revising it critically for important intellectual content, and final approval of the version to be published. Both authors agree to be accountable for all aspects of the work. S.C.W. is supported by a fellowship from the Swedish Society for Medical Research (P18-0098; PD20-0153). V.M.L. is supported by the Swedish Research Council (grant agreement numbers 2019-01837 and 2021-02801), by the EU/EFPIA/OICR/McGill/KTH/Diamond Innovative Medicines Initiative 2 Joint Undertaking (EUbOPEN grant number 875510), by the Swedish Strategic Research Programme in Diabetes (SFO Diabetes) and Stem Cells and Regenerative Medicine (SFO StratRegen), and by the Robert Bosch Foundation, Stuttgart, Germany.

Role of Nutrition in the Etiopathogenesis and Prevention of Nonalcoholic Fatty Liver Disease (NAFLD) in a Group of Obese Adults.

Nonalcoholic fatty liver disease (NAFLD) is liver damage characterized by an accumulation of triglycerides in hepatocytes of >5% (due to an alteration of the balance of the lipid metabolism in favour of lipogenesis compared to lipolysis) that is not induced by the consumption of alcohol. The pathology includes simple steatosis and nonalcoholic steatohepatitis, or NASH (steatosis associated with microinflammatory activities), which can evolve in 15% of subjects with hepatic fibrosis to cirrhosis and the development of hepatocellular carcinoma. The aim of this study is to report the role of macro- and micronutrients in the pathogenesis and prevention of NAFLD in obese subjects. A total of 22 obese or overweight patients with hepatic steatosis were monitored periodically, evaluating their eating habits, fasting glycaemia, lipid picture, liver enzymes, anthropometric parameters, nutrition status, liver ultrasound, oxidative stress, and adherence to the Mediterranean diet. A statistical analysis shows a significant positive relationship between total cholesterol and the Mediterranean adequacy index (MAI) (r = -0.57; p = 0.005) and a significant negative relationship between ALT transaminases and the MAI (r = -0.56; p = 0.007). Nutrition and diet are important factors in the pathogenesis and prevention of NAFLD. The dietary model, based on the canons of the Mediterranean diet, prevents and reduces the accumulation of fat in hepatocytes. Therefore, in agreement with other studies in the literature, we can state that a dietary model characterized by foods rich in fibre, carotenoids, polyphenols, ω3 fatty acids, folic acid, and numerous other molecules is inversely correlated with the serum levels of ALT transaminases, an enzyme whose level increases when the liver is damaged and before the most obvious symptoms of organ damage appear.

PS-BPB03-5: DEVELOPMENT OF A THERAPEUTIC VACCINE FOR DYSLIPIDEMIA AND RELATED DISEASES TARGETING ANGIOPOIETIN-LIKE PROTEIN 3 (ANGPTL3).

Background: Dyslipidemia is a major factor in the development and progression of atherosclerotic diseases. Among dyslipidemias, familial hypercholesterolemia (FH) is a genetic disorder affecting approximately 34 million people worldwide, with 300,000 patients in Japan. Since homozygous FH in particular is resistant to existing therapies, there is an urgent need to develop new therapies to reduce the risk of cardiovascular disease (CVD) in patients with FH. Design and Method: We focused on angiopoietin-like protein 3 (ANGPTL3) as a novel therapeutic target for dyslipidemia. ANGPTL3 is known to inhibit lipoprotein lipase as well as angiogenesis. Mutations of this gene in humans were reported to have no apparent pathogenic effects and have been reported to reduce triglyceride (TG) and LDL cholesterol (LDL-C) levels in the blood and the risk of developing CVD. We have developed a peptide vaccine that induces anti-ANGPTL3 antibodies and produces a potent therapeutic effect on dyslipidemia. We vaccinated ob/ob mice, an obese mouse model of type 2 diabetes, with a total of three doses of vaccine every two weeks and analyzed the results. Results: The vaccine group (n = 12) showed significant reductions in blood TG concentration by 52%, LDL-C concentration by 41%, and small dense LDL-C concentration by 49% compared to the control group (n = 10). In addition, histologically fatty liver was improved, and analysis of TG accumulation in hepatocytes showed a 47% reduction in the vaccine group. Furthermore, vaccination reduced dyslipidemia and atherosclerosis in ApoE function-deficient mice, a model of severe familial hypercholesterolemia. Notability, the vaccine did not induce cytotoxic immunity against the mouse liver and ANGPTL3-producing organs. Conclusions: Based on these results, this vaccine is expected to be one of the effective treatments for atherosclerotic diseases.

The tetraspanin transmembrane protein CD53 mediates dyslipidemia and integrates inflammatory and metabolic signaling in hepatocytes

Tetraspanins are transmembrane signaling and proinflammatory proteins. Prior work demonstrates that the tetraspanin, CD53/TSPAN25/MOX44, mediates B-cell development and lymphocyte migration to lymph nodes and is implicated in various inflammatory diseases. However, CD53 is also expressed in highly metabolic tissues, including adipose and liver; yet its function outside the lymphoid compartment is not defined. Here, we show that CD53 demarcates the nutritional and inflammatory status of hepatocytes. High-fat exposure and inflammatory stimuli induced CD53 in vivo in liver and isolated primary hepatocytes. In contrast, restricting hepatocyte glucose flux through hepatocyte glucose transporter 8 deletion or through trehalose treatment blocked CD53 induction in fat- and fructose-exposed contexts. Furthermore, germline CD53 deletion in vivo blocked Western diet-induced dyslipidemia and hepatic inflammatory transcriptomic activation. Surprisingly, metabolic protection in CD53 KO mice was more pronounced in the presence of an inciting inflammatory event. CD53 deletion attenuated tumor necrosis factor alpha-induced and fatty acid + lipopolysaccharide-induced cytokine gene expression and hepatocyte triglyceride accumulation in isolated murine hepatocytes. In vivo, CD53 deletion in nonalcoholic steatohepatitis diet-fed mice blocked peripheral adipose accumulation and adipose inflammation, insulin tolerance, and liver lipid accumulation. We then defined a stabilized and trehalase-resistant trehalose polymer that blocks hepatocyte CD53 expression in basal and over-fed contexts. The data suggest that CD53 integrates inflammatory and metabolic signals in response to hepatocyte nutritional status and that CD53 blockade may provide a means by which to attenuate pathophysiology in diseases that integrate overnutrition and inflammation, such as nonalcoholic steatohepatitis and type 2 diabetes.

Proteomic analysis of the effect of high-fat-diet and voluntary physical activity on mouse liver.

Nonalcoholic fatty liver disease (NALFD), characterized by an abnormal accumulation of triglycerides in hepatocytes, is closely linked to insulin resistance, metabolic syndrome, and changes in lipogenesis in the liver. The accumulation of hepatic lipids can lead to a range of pathologies from mild steatosis to severe cirrhosis. Endurance exercise is known to ameliorate the adverse health effects of NAFLD. Therefore, we aimed to investigate the effect of voluntary wheel running (VWR) on the metabolic changes in the livers of high-fat diet (HFD)-induced NAFLD mice and used LC-MS/MS (Liquid chromatography–mass spectrometry) to determine whether the tested intervention affected the protein expression profiles of the mouse livers. Male C57BL/6 mice were randomly divided into three groups: control (CON), high-fat diet sedentary group (HFD), high-fat diet VWR group (HFX). HFX group performed voluntary wheel running into individually cages, given a high-fat diet for 12 weeks. Food consumption, body weight, and running distance were measured every week. Using 2D (2-dimensional)-gel electrophoresis, we detected and quantitatively analyzed the protein expression with >2.0-fold change in the livers of HFD-fed mice, HFD-fed exercise (HFX) mice, and chow-fed mice. Body weight was significantly increased in HFD compared to CON (P < 0.05). The 2D-gel electrophoresis analysis indicated that there was a difference between CON and HFD groups, showing 31 increased and 27 decreased spots in the total 302 paired spots in the HFD group compared to CON. The analysis showed 43 increased and 17 decreased spots in the total 258 spots in the HFX group compared to CON. Moreover, 12 weeks of VWR showed an increase of 35 and a decrease of 8 spots in a total of 264 paired spots between HFD and HFX. LC-MS/MS of HFD group revealed that proteins involved in ketogenesis, lipid metabolism, and the metabolism of drugs and xenobiotics were upregulated, whereas detoxifying proteins, mitochondrial precursors, transport proteins, proteasomes, and proteins involved in amino acid metabolism were downregulated. On the other hand, VWR counteracted the protein expression profile of HFD-fed mice by upregulating molecular chaperones, gluconeogenesis-, detoxification-, proteasome-, and energy metabolism-related proteins. This study provided a molecular understanding of the HFD- and exercise-induced protein marker expression and presented the beneficial effects of exercise during pathophysiological conditions.

Silymarin diminishes oleic acid-induced lipid accumulation in HepG2 cells by modulating the expression of endoplasmic reticulum stress markers

Background and objectivesNon-alcoholic fatty liver disease (NAFLD) is a common metabolic disorder which presents with the accumulation of triglycerides in hepatocytes due to imbalances in the uptake, synthesis, export, and oxidation of fatty acids. Silymarin is a flavonolignan derived from milk thistle, a herbal medicine that has been used for centuries to treat liver disease. In this study, the effect of silymarin on genes involved in lipogenesis and endoplasmic reticulum (ER) stress was investigated in the cellular NAFLD model. Materials and methodsHepG2 cells were treated with 0.5 mM oleic acid (OA) in the presence or absence of silymarin for 24 h, and subsequently, lipid accumulation was assessed by staining the cells with Oil red O as well as the measurement of intracellular triglyceride (TG) content with an enzymatic method. Real-time reverse transcription polymerase chain reaction (RT-PCR) was used to measure the expression of sterol regulatory element-binding protein-1 (SREBP-1), fatty acid synthase (FAS), Sirtuin 1 (SIRT1), TRB3, and ATF4. ResultsLipid accumulation was increased in OA-treated hepatocytes, an effect that was attenuated by silymarin. The expression of FAS, SREBP-1, TRB3, and ATF4 was significantly increased in OA-treated HepG2 cells, while the expression of SIRT1 was decreased. Treatment with silymarin could successfully diminish SREBP-1, FAS, TRB3, and ATF4 gene expression while augmenting the expression of SIRT1. ConclusionsSilymarin not only efficiently reduces lipogenesis but also decreases ER stress, which is a critical parameter in lipogenesis. Therefore, silymarin might be considered an effective supplementary option in the treatment of liver steatosis.

Comprehensive Transcriptome Profiling of NAFLD- and NASH-Induced Skeletal Muscle Dysfunction.

Nonalcoholic fatty liver disease (NAFLD), characterized by extensive triglyceride accumulation in hepatocytes, may progress to nonalcoholic steatohepatitis (NASH) with liver fibrosis and inflammation and increase the risk of cirrhosis, cancer, and death. It has been reported that physical exercise is effective in ameliorating NAFLD and NASH, while skeletal muscle dysfunctions, including lipid deposition and weakness, are accompanied with NAFLD and NASH. However, the molecular characteristics and alterations in skeletal muscle in the progress of NAFLD and NASH remain unclear. In the present study, we provide a comprehensive analysis on the similarity and heterogeneity of quadriceps muscle in NAFLD and NASH mice models by RNA sequencing. Importantly, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway functional enrichment analysis revealed that NAFLD and NASH led to impaired glucose and lipid metabolism and deteriorated functionality in skeletal muscle. Besides this, we identified that myokines possibly mediate the crosstalk between muscles and other metabolic organs in pathological conditions. Overall, our analysis revealed a comprehensive understanding of the molecular signature of skeletal muscles in NAFLD and NASH, thus providing a basis for physical exercise as an intervention against liver diseases.

MiR-23a/b-3p promotes hepatic lipid accumulation by regulating Srebp-1c and Fas.

miR-23a-3p and miR-23b-3p are members of the miR-23~27~24-2 superfamily. The role of miR-23a/b-3p in regulating hepatic lipid accumulation is still unknown. Here, we found that increased miR-23a-3p and miR-23b-3p levels were accompanied by an increase in the protein levels of the sterol regulatory element-binding protein-1 (SREBP-1) and fatty acid synthase (FAS) in the steatotic livers of mice fed a high-fat diet and leptin receptor-deficient type 2 diabetic mice (db/db). Importantly, overexpression of miR-23a/b-3p in Hep1-6 cells elevated the intracellular triglyceride level and upregulated the expression of Srebp-1c and Fas. Taken together, these results suggested that miR-23a/b-3p enhanced mRNA stability by binding the 5'-UTR of Srebp-1c and Fas mRNA, thereby promoting triglyceride accumulation in hepatocytes.

Upregulation of adiponectin by Ginsenoside Rb1 contributes to amelioration of hepatic steatosis induced by high fat diet

BackgroundGinsenoside Rb1 (GRb1) is capable of regulating lipid and glucose metabolism through its action on adipocytes. However, the beneficial role of GRb1-induced up-regulation of adiponectin in liver steatosis remains unelucidated. Thus, we tested whether GRb1 ameliorates liver steatosis and insulin resistance by promoting the expression of adiponectin. Methods3T3-L1 adipocytes and hepatocytes were used to investigate GRb1's action on adiponectin expression and triglyceride (TG) accumulation. Wild type (WT) mice and adiponectin knockout (KO) mice fed high fat diet were treated with GRb1 for 2 weeks. Hepatic fat accumulation and function as well as insulin sensitivity was measured. The activation of AMPK was also detected in the liver and hepatocytes. ResultsGRb1 reversed the reduction of adiponectin secretion in adipocytes. The conditioned medium (CM) from adipocytes treated with GRb1 reduced TG accumulation in hepatocytes, which was partly attenuated by the adiponectin antibody. In the KO mice, the GRb1-induced significant decrease of TG content, ALT and AST was blocked by the deletion of adiponectin. The elevations of GRb1-induced insulin sensitivity indicated by OGTT, ITT and HOMA-IR were also weakened in the KO mice. The CM treatment significantly enhanced the phosphorylation of AMPK in hepatocytes, but not GRb1 treatment. Likewise, the phosphorylation of AMPK in liver of the WT mice was increased by GRb1, but not in the KO mice. ConclusionsThe up-regulation of adiponectin by GRb1 contributes to the amelioration of liver steatosis and insulin resistance, which further elucidates a new mechanism underlying the beneficial effects of GRb1 on obesity.

CHANGING TRENDS IN AETIOLOGY OF LIVER DISEASES IN IMMIGRANTS IN SOUTHERN ITALY: FATTY LIVER, AN OBSERVATIONAL RETROSPECTIVE STUDY

The rate of migration in Italy is constantly growing with immigrants making up about 8.7% of the country's population and 4.8% in our district (Foggia-Puglia, Southern Italy) (1). These are people who are both already resident in Italy for one or more generations, and new arrivals. Migrants in our geographical area mainly come from Eastern Europe, Sub-Saharan Africa, Middle-East and South Asia. Such a high number of immigrants result in a minor change in the epidemiological pattern of diseases with an increase in certain infections, which are imported or contracted in our country such as HIV, TB and viral hepatitis (2), but can also include cancers, cardio-cerebrovascular and autoimmune diseases (3-4). Other major health concerns mainly include metabolic syndrome (5), as well as problems related to social discomfort such as alcoholism (6). The incidences of hyperlipidaemia, obesity and diabetes mellitus amongst immigrants, has increased signicantly over the years due to social and economic progression, and lifestyle changes, which in some cases are due to high-fat and highsugar diets and a lack of physical exercise (5-7). One of the most common clinical problems is fatty liver (FL): a metabolic disorder characterized by an excessive accumulation of triglycerides in hepatocytes that can be induced by multiple causes. Chronic alcohol intake is certainly one of the main causes (ALD), while another important reason is NAFLD (Non-Alcoholic Fatty Liver Disease), which represents the hepatic component of metabolic syndrome (8). FL has now become a major cause of liver related morbidity and mortality, with an incidence of around 20-25% worldwide. It is present mainly in native populations of developed countries, but its prevalence is also increasing amongst immigrants (8-10).

Loss and gain of function of Grp75 or mitofusin 2 distinctly alter cholesterol metabolism, but all promote triglyceride accumulation in hepatocytes

In the liver, contact sites between the endoplasmic reticulum (ER) and mitochondria (named MAMs) may be crucial hubs for the regulation of lipid metabolism, thus contributing to the exacerbation or prevention of fatty liver. We hypothesized that tether proteins located at MAMs could play a key role in preventing triglyceride accumulation in hepatocytes and nonalcoholic fatty liver disease (NAFLD) occurrence. To test this, we explored the role of two key partners in building MAM integrity and functionality, the glucose-regulated protein 75 (Grp75) and mitofusin 2 (Mfn2), which liver contents are altered in obesity and NAFLD. Grp75 or Mfn2 expression was either silenced using siRNA or overexpressed with adenoviruses in Huh7 cells.Silencing of Grp75 and Mfn2 resulted in decreased ER-mitochondria interactions, mitochondrial network fusion state and mitochondrial oxidative capacity, while overexpression of the two proteins induced mirror impacts on these parameters. Furthermore, Grp75 or Mfn2 silencing decreased cellular cholesterol content and enhanced triglyceride secretion in ApoB100 lipoproteins, while their overexpression led to reverse effects. Cellular phosphatidylcholine/phosphatidylethanolamine ratio was decreased only upon overexpression of the proteins, potentially contributing to altered ApoB100 assembly and secretion. Despite the opposite differences, both silencing and overexpression of Grp75 or Mfn2 induced triglyceride storage, although a fatty acid challenge was required to express the alteration upon protein silencing. Among the mechanisms potentially involved in this phenotype, ER stress was closely associated with altered triglyceride metabolism after Grp75 or Mfn2 overexpression, while blunted mitochondrial FA oxidation capacity may be the main defect causing triglyceride accumulation upon Grp75 or Mfn2 silencing. Further studies are required to decipher the link between modulation of Grp75 or Mfn2 expression, change in MAM integrity and alteration of cholesterol content of the cell.In conclusion, Grp75 or Mfn2 silencing and overexpression in Huh7 cells contribute to altering MAM integrity and cholesterol storage in opposite directions, but all promote triglyceride accumulation through distinct cellular pathways. This study also highlights that besides Mfn2, Grp75 could play a central role in hepatic lipid and cholesterol metabolism in obesity and NAFLD.

SLAMF1 Mediates Hepatocyte Death in a Model of Non‐Alcoholic Steatohepatitis

Non-alcoholic fatty liver disease (NAFLD) is one of the most common forms of chronic liver disease. NAFLD's initial phase involves hepatic stea­tosis (triglyceride accumulation in hepatocytes). NAFLD can rapidly progress to non-alcoholic steatohepatitis (NASH). NASH is characterized by increased oxidative stress, lipid peroxidation, inflammation, mitochondria dysfunction, and hepatocyte death and fibrosis. If untreated, NASH leads to cirrhosis, and in some cases, hepatocellular carcinoma. Besides lifestyle modifications (e.g., diet and exercise), we still do not have effective treatment for NASH today. Therefore, it is critical to understand the mechanisms responsible for NAFLD progression to NASH to develop efficient therapies and find disease progression biomarkers. Signaling lymphocytic activation molecule 1 (SLAMF1) protein is a self-ligand receptor involved in regulating the immune response to viruses and cancer. In the present project, we found that hepatocytes from NASH liver samples from humans and mice express high levels of SLAMF1. To confirm these findings, we used palmitic acid-treated HepG2 hepatocytes as an “in vitro” model of NASH. We found that palmitic acid treatment of HepG2 hepatocytes leads to significant increases in SLAMF1 mRNA and protein levels, which correlated with an increased hepatocyte death in response to palmitic acid treatment. To investigate the potential role of SLAMF1 in mediating the toxic effects of palmitic acid treatment, we partially blocked SLAMF1 with siRNA. Our results showed that downregulation of SLAMF1 levels in hepatocytes significantly improved cell viability and reduced the expression of the cytotoxicity and proapoptotic markers such as cleaved caspase 3 and vimentin V by hepatocytes. We also found that palmitic acid-treated hepatocytes secrete SLAMF1 in the culture medium. Our data suggest that SLAMF1, both membrane-bound and soluble form, are upregulated by palmitic acid treatment and may mediate its cytotoxic effects. SLAMF1 could be used as a potential therapeutic or diagnostic target (soluble form) for NASH.

TSH attenuates fatty acid oxidation in hepatocytes by reducing the mitochondrial distribution of miR-449a/449b-5p/5194

The elevated thyroid-stimulating hormone (TSH) levels contribute to the abnormal expression/activity of several key hepatic lipid metabolism enzymes. Although miRNAs have been shown to play key roles in hepatic lipid metabolism and are found in isolated mitochondria, very little is known about the pathological and physiological significance of their mitochondrial distributions in regulating liver lipid metabolism. Here, we found that TSH significantly reduced the distribution of some miRNAs in mitochondria of hepatocytes, especially miR-449a, miR-449b-5p, and miR-5194. These three miRNAs inhibited their target genes PGC1B, ABCD1, ADIPOR1 and the downstream molecule PPARA. These effects synergistically suppressed fatty acid (FA) β-oxidation in mitochondria and peroxisomes and decreased the translocation of cytosolic very long chain fatty acids to peroxisomes, which noticeably reduced FA catabolism and promoted triglyceride accumulation in hepatocytes. This study reveals the functional significance of changed miRNA mitochondrial-cytoplasmic distribution in the regulation of hepatic lipid metabolism.

Serum Acylcarnitines Associated with High Short-Term Mortality in Patients with Alcoholic Hepatitis.

Alcohol-related liver disease is one of the most prevalent liver diseases in the United States. Early stages of alcohol-related liver disease are characterized by accumulation of triglycerides in hepatocytes. Alcoholic hepatitis is a severe form of alcohol-related liver disease associated with significant morbidity and mortality. We sought to identify patients who are at greatest risk of death using serum lipids. First, we performed lipidomics analysis on serum samples collected from 118 patients with alcoholic hepatitis to identify lipid markers that are associated with high risk of death. Next, we performed gene set enrichment analysis on liver transcriptomics data to identify dysregulated lipid metabolism in patients who received liver transplantation. Finally, we built a random forest model to predict 30-day mortality using serum lipids. A total of 277 lipids were annotated in the serum of patients with alcoholic hepatitis, among which 25 were significantly different between patients in the deceased and alive groups. Five chemical clusters were significantly altered between the two groups. In particular, acylcarnitine cluster was enriched in the deceased group. Several hepatic lipid metabolism pathways were dysregulated in patients with alcoholic hepatitis who received liver transplantation. The mRNA expression of genes involved in the fatty acid transport into mitochondria and β-oxidation were also dysregulated. When predicting 30-day mortality in alcoholic hepatitis patients using serum lipids, we found that the area under the curve achieved 0.95. Serum lipids such as acylcarnitines may serve as biomarkers to identify alcoholic hepatitis patients at the greatest risk of death.