Is Nrf2-ARE a potential target in NAFLD mitigation?

Antioxidant Peptides from Miiuy Croaker Swim Bladders: Ameliorating Effect and Mechanism in NAFLD Cell Model through Regulation of Hypolipidemic and Antioxidant Capacity

In this work, the hypolipidemic and antioxidative capacity of FSGLR (S7) and GIEWA (S10) from miiuy croaker swim bladders was explored systematically in an oleic acid (OA)-induced nonalcoholic fatty liver disease (NAFLD) model of HepG2 cells. Moreover, the hypolipidemic activity of S7 and S10 and their antioxidative abilities were preliminarily investigated in combination with molecular docking technology. The results indicated that S7 and S10 could decrease the amount of lipid accumulation and the content of triglycerides (TG) and total cholesterol (TC) in the OA-induced NAFLD cell model in a dose-dependent manner. In addition, S7 and S10 exhibited better bile salt binding, pancreatic lipase (PL) inhibition, and cholesterol esterase (CE) inhibition capacities. The hypolipidemic mechanisms of S7 and S10 were connected with the downregulation of the mRNA expression levels of adipogenic factors, including sterol-regulatory element-binding protein-1c (SREBP-1c), acetyl-CoA carboxylase (ACC), sterol-regulatory element-binding protein (SREBP)-2, hydroxymethylglutaryl-CoA reductase (HMGR), and fatty acid synthase (FAS) (p < 0.01), and the upregulation of the mRNA expression of β-oxidation-related factors, including carnitine palmitoyltransferase 1 (CPT-1), acyl-CoA oxidase 1 (ACOX-1), and peroxisome proliferator-activated receptor α (PPARα). Moreover, FSGLR (S7) and GIEWA (S10) could significantly protect HepG2 cells against OA-induced oxidative damage, and their antioxidant mechanisms were related to the increased activity of intracellular antioxidant proteases (superoxide dismutase, SOD; glutathione peroxidase, GSH-PX; catalase, CAT) to remove excess reactive oxygen species (ROS) and decrease the production of malondialdehyde (MDA). The presented findings indicate that the hypolipidemic and antioxidant functions and mechanisms of S7 and S10 could make them potential hypolipidemic and antioxidant candidates for the treatment of NAFLD.

Carthamus tinctorius L. (Safflower) Flower Extract Attenuates Hepatic Injury and Steatosis in a Rat Model of Type 2 Diabetes Mellitus via Nrf2-Dependent Hypoglycemic, Antioxidant, and Hypolipidemic Effects

This study aimed to examine the hepatic and anti-steatotic protective effects of methanolic extract from Carthamus tinctorius (safflower) flowers (SFFE), using a rat model of type 2 diabetes mellitus (T2DM), and to examine the molecular mechanisms underlying these effects. Adult male Wistar rats were used for this study. First, T2DM was induced in some rats by feeding them a high-fat diet (HFD) for 4 weeks, followed by a single dose of streptozotocin (STZ) (35 mg/kg, i.p.). Experimental groups included the following five groups (n = 8 in each): control, control + SFFE, T2DM, T2DM + SFFE, and T2DM + SFFE + brusatol (an Nrf2 inhibitor, 2 mg/kg, i.p.). SFFE was administered at a concentration of 300 mg/kg, and all experiments concluded after 8 weeks. Treatments with SFFE significantly reduced fasting blood glucose levels, free fatty acids (FFAs), cholesterol, triglycerides, and low-density lipoprotein cholesterol in both the control and T2DM rats, but they failed to reduce fasting insulin levels in these groups. SFFE treatments also improved the liver structure and reduced hepatocyte vacuolization and hepatic levels of triglycerides and cholesterol in T2DM rats, in addition to increasing the hepatic mRNA levels of keap1 and the cytoplasmic levels and nuclear activities of Nrf2 in both the control and T2DM rats. SFFE also stimulated the expression levels of PPARα and CPT-1 but reduced the malondialdehyde (MDA), mRNA levels of SREBP1, fatty acid synthase, and acetyl CoA carboxylase in both the control and T2DM rats; meanwhile, it reduced hepatic mRNA and the nuclear activities of NF-κB and increased levels of glutathione, superoxide dismutase, and heme oxygenase-1 in the livers of both groups of treated rats. Furthermore, SFFE suppressed the levels of caspase-3, Bax, tumor necrosis factor-α, and interleukin-6 in the T2DM rats. Treatment with brusatol prevented all of these effects of SFFE. In conclusion, SFFE suppresses liver damage and hepatic steatosis in T2DM through Nrf2-dependent hypoglycemic, antioxidant, anti-inflammatory, and hypolipidemic effects.

Vaccinium spp. Berries in the Prevention and Treatment of Non-Alcoholic Fatty Liver Disease: A Comprehensive Update of Preclinical and Clinical Research

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disorder marked by the buildup of triacylglycerols (TGs) in the liver. It includes a range of conditions, from simple steatosis to more severe forms like non-alcoholic steatohepatitis (NASH), which can advance to fibrosis, cirrhosis, and hepatocellular carcinoma. NAFLD's prevalence is rising globally, estimated between 10% and 50%. The disease is linked to comorbidities such as obesity, type 2 diabetes, insulin resistance, and cardiovascular diseases and currently lacks effective treatment options. Therefore, researchers are focusing on evaluating the impact of adjunctive herbal therapies in individuals with NAFLD. One herbal therapy showing positive results in animal models and clinical studies is fruits from the Vaccinium spp. genus. This review presents an overview of the association between consuming fruits, juices, and extracts from Vaccinium spp. and NAFLD. The search used the following keywords: ((Vaccinium OR blueberry OR bilberry OR cranberry) AND ("non-alcoholic fatty liver disease" OR "non-alcoholic steatohepatitis")). Exclusion criteria included reviews, research notes, book chapters, case studies, and grants. The review included 20 studies: 2 clinical trials and 18 studies on animals and cell lines. The findings indicate that juices and extracts from Vaccinium fruits and leaves have significant potential in addressing NAFLD by improving lipid and glucose metabolism and boosting antioxidant and anti-inflammatory responses. In conclusion, blueberries appear to have the potential to alleviate NAFLD, but more clinical trials are needed to confirm these benefits.

The Coumarin-Derivative Esculetin Protects against Lipotoxicity in Primary Rat Hepatocytes via Attenuating JNK-Mediated Oxidative Stress and Attenuates Free Fatty Acid-Induced Lipid Accumulation

Coumarin derivates have been proposed as a potential treatment for metabolic-dysfunction-associated fatty liver disease (MAFLD). However, the mechanisms underlying their beneficial effects remain unclear. In the present study, we explored the potential of the coumarin derivate esculetin in MAFLD, focusing on hepatocyte lipotoxicity and lipid accumulation. Primary cultures of rat hepatocytes were exposed to palmitic acid (PA) and palmitic acid plus oleic acid (OA/PA) as models of lipotoxicity and lipid accumulation, respectively. Esculetin significantly reduced oxidative stress in PA-treated hepatocytes, as shown by decreased total reactive oxygen species (ROS) and mitochondrial superoxide production and elevated expression of antioxidant genes, including Nrf2 and Gpx1. In addition, esculetin protects against PA-induced necrosis. Esculetin also improved lipid metabolism in primary hepatocytes exposed to nonlipotoxic OA/PA by decreasing the expression of the lipogenesis-related gene Srebp1c and increasing the expression of the fatty acid β-oxidation-related gene Ppar-α. Moreover, esculetin attenuated lipid accumulation in OA/PA-treated hepatocytes. The protective effects of esculetin against lipotoxicity and lipid accumulation were shown to be dependent on the inhibition of JNK and the activation of AMPK, respectively. We conclude that esculetin is a promising compound to target lipotoxicity and lipid accumulation in the treatment of MAFLD.

Identification and validation of potential diagnostic signature and immune cell infiltration for NAFLD based on cuproptosis-related genes by bioinformatics analysis and machine learning

BACKGROUND AND AIMS

Cuproptosis has been identified as a key player in the development of several diseases. In this study, we investigate the potential role of cuproptosis-related genes in the pathogenesis of nonalcoholic fatty liver disease (NAFLD).

METHOD

The gene expression profiles of NAFLD were obtained from the Gene Expression Omnibus database. Differential expression of cuproptosis-related genes (CRGs) were determined between NAFLD and normal tissues. Protein-protein interaction, correlation, and function enrichment analyses were performed. Machine learning was used to identify hub genes. Immune infiltration was analyzed in both NAFLD patients and controls. Quantitative real-time PCR was employed to validate the expression of hub genes.

RESULTS

Four datasets containing 115 NAFLD and 106 control samples were included for bioinformatics analysis. Three hub CRGs (NFE2L2, DLD, and POLD1) were identified through the intersection of three machine learning algorithms. The receiver operating characteristic curve was plotted based on these three marker genes, and the area under the curve (AUC) value was 0.704. In the external GSE135251 dataset, the AUC value of the three key genes was as high as 0.970. Further nomogram, decision curve, calibration curve analyses also confirmed the diagnostic predictive efficacy. Gene set enrichment analysis and gene set variation analysis showed these three marker genes involved in multiple pathways that are related to the progression of NAFLD. CIBERSORT and single-sample gene set enrichment analysis indicated that their expression levels in macrophages, mast cells, NK cells, Treg cells, resting dendritic cells, and tumor-infiltrating lymphocytes were higher in NAFLD compared with control liver samples. The ceRNA network demonstrated a complex regulatory relationship between the three hub genes. The mRNA level of these hub genes were further confirmed in a mouse NAFLD liver samples.

CONCLUSION

Our study comprehensively demonstrated the relationship between NAFLD and cuproptosis, developed a promising diagnostic model, and provided potential targets for NAFLD treatment and new insights for exploring the mechanism for NAFLD.

Bean Leaves Ameliorate Lipotoxicity in Fatty Liver Disease

Bioactive compounds in plant-based food have protective effects against metabolic alterations, including non-alcoholic fatty liver disease (NAFLD). Bean leaves are widely cultivated in the world and are a source of dietary fiber and polyphenols. High fat/high fructose diet animal models promote deleterious effects in adipose and non-adipose tissues (lipotoxicity), leading to obesity and its comorbidities. Short-term supplementation of bean leaves exhibited anti-diabetic, anti-hyperlipidemic, and anti-obesity effects in high-fat/high-fructose diet animal models. This study aimed to evaluate the effect of bean leaves supplementation in the prevention of lipotoxicity in NAFLD and contribute to elucidating the possible mechanism involved for a longer period of time. During thirteen weeks, male Wistar rats (n = 9/group) were fed with: (1) S: Rodent Laboratory Chow 5001^® (RLC); (2) SBL: 90% RLC+ 10% dry bean leaves; (3) H: high-fat/high-fructose diet; (4) HBL: H+ 10% of dry bean leaves. Overall, a HBL diet enhanced impaired glucose tolerance and ameliorated obesity, risk factors in NAFLD development. Additionally, bean leaves exerted antioxidant (↑serum GSH) and anti-inflammatory (↓mRNA TNFα in the liver) effects, prevented hepatic fat accumulation by enhanced ↑mRNA PPARα (β oxidation), and enhanced lipid peroxidation (↓liver MDA). These findings suggest that bean leaves ameliorated hepatic lipotoxicity derived from the consumption of a deleterious diet.

Antioxidant Peptides from Monkfish Swim Bladders: Ameliorating NAFLD In Vitro by Suppressing Lipid Accumulation and Oxidative Stress via Regulating AMPK/Nrf2 Pathway

In this study, we investigate the ameliorating functions of QDYD (MSP2), ARW (MSP8), DDGGK (MSP10), YPAGP (MSP13) and DPAGP (MSP18) from monkfish swim bladders on an FFA-induced NAFLD model of HepG2 cells. The lipid-lowering mechanisms revealed that these five oligopeptides can up-regulate the expression of phospho-AMP-activated protein kinase (p-AMPK) proteins to inhibit the expression of the sterol regulatory element binding protein-1c (SREBP-1c) proteins on increasing lipid synthesis and up-regulating the expression of the PPAP-α and CPT-1 proteins on promoting the β-oxidation of fatty acids. Moreover, QDYD (MSP2), ARW (MSP8), DDGGK (MSP10), YPAGP (MSP13) and DPAGP (MSP18) can significantly inhibit reactive oxygen species' (ROS) production, promote the activities of intracellular antioxidases (superoxide dismutase, SOD; glutathione peroxidase, GSH-PX; and catalase, CAT) and bring down the content of malondialdehyde (MDA) derived from lipid peroxidation. Further investigations revealed that the regulation of these five oligopeptides on oxidative stress was achieved through activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway to raise the expression levels of the heme oxygenase 1 (HO-1) protein and downstream antioxidant proteases. Therefore, QDYD (MSP2), ARW (MSP8), DDGGK (MSP10), YPAGP (MSP13) and DPAGP (MSP18) could serve as candidate ingredients to develop functional products for treating NAFLD.

Marine Bioactive Peptides-Structure, Function and Application

Marine organisms live in harsh marine habitats, causing them to have significantly different and more diverse proteins than those of terrestrial organisms [...].

Betulin prevents high fat diet-induced non-alcoholic fatty liver disease by mitigating oxidative stress and upregulating Nrf2 and SIRT1 in rats

Non-alcoholic fatty liver disease (NAFLD) is a common chronic hepatic disorder characterized by hepatic lipid accumulation. This study explored the effect of betulin (BE), a terpenoid with promising antioxidant, anti-inflammatory and insulin sensitizing effects, on NAFLD induced by high fat diet (HFD). Rats received HFD and BE (15 and 30 mg/kg) for 12 weeks and blood and liver samples were collected for analyses. HFD caused hyperlipidemia, cholesterol and triglycerides accumulation in the liver, hepatocellular ballooning, fibrosis, insulin resistance (IR), lipid peroxidation (LPO), and NF-kB p65 upregulation. BE ameliorated serum and liver lipids, blood glucose, and insulin, liver LPO, prevented steatosis and fibrosis, suppressed NF-kB p65 and enhanced antioxidants in HFD-fed rats. BE downregulated ACC1 and FAS, and upregulated Nrf2, HO-1 and SIRT1 in the liver of HFD-fed rats. In silico investigations revealed the binding affinity of BE towards NF-kB, Keap1, HO-1 and SIRT1. In conclusion, BE attenuated HFD-induced NAFLD by ameliorating hyperlipidemia, IR, lipogenesis, liver lipid accumulation, and oxidative stress. The protective effect of BE was associated with enhanced Nrf2/HO-1 signaling and SIRT1.

Olanzapine-induced nonalcoholic fatty liver disease: The effects of differential food pattern and the involvement of PGRMC1 signaling

Detrimental dietary habits with high-fat food are common in the psychiatric population, leading to higher obesity rate. Olanzapine (OLZ), as one of the mainstream antipsychotic drugs, shows superior efficacy in treating schizophrenia but limited by adverse effects such as obesity, dyslipidemia and liver injury, which are risk factors for the development of nonalcoholic fatty liver disease (NAFLD). Progesterone receptor component 1 (PGRMC1) is a key regulator associated with antipsychotic drug-induced metabolic disorders. Our study aims to investigate whether high-fat supplementation worsens OLZ-induced NAFLD and to validate the potential role of PGRMC1 pathway. In vivo, eight-week OLZ treatment successfully induced hepatic steatosis in female C57BL/6 mice fed with either a high-fat or normal diet, which is independent of body weight gain. Likewise, in vitro, OLZ markedly led to hepatocyte steatosis along with enhanced oxidative stress, which was aggravated by free fatty acids. Moreover, in vivo and in vitro, high-fat supplementation aggravated OLZ-induced hepatic lipid accumulation and oxidative stress via inhibition of hepatic PGRMC1-AMPK-mTORC1/Nrf2 pathways. Inspiringly, PGRMC1 overexpression effectively reversed OLZ-induced hepatocyte steatosis in vitro. Hence, hepatic PGRMC1 is attributable to OLZ-induced NAFLD especially with high-fat supplementation and potentially serves as a novel therapeutic target.

Tetrastigma hemsleyanum leaf extracts ameliorate NAFLD in mice with low-grade colitis via the gut-liver axis

Nonalcoholic fatty liver disease (NAFLD) is a complex metabolic disorder, manifested as oxidative stress, lipid accumulation, and inflammation of the liver. Tetrastigma hemsleyanum leaves (THL), which are rich in flavonoids and phenolic acids, have good anti-inflammatory, antioxidant, and hepatoprotective effects. However, it is unknown whether THL extracts can improve NAFLD and the underlying mechanisms are unknown. Hence, this study was designed to investigate the effects of THL extracts on NAFLD and perform a preliminary inquiry into the underlying mechanism based on the gut-liver axis. The results showed that THL extracts could reverse NAFLD-related oxidative stress, lipid accumulation, and inflammation. Additionally, the protective effect of THL extracts on the gut includes the maintenance of the intestinal barrier and the regulation of gut microbiota, which may be one of the mechanisms by which THL improves NAFLD. To be specific, in our study, THL extracts alleviated hepatic lipid accumulation and oxidative stress by regulating the expression of lipid synthesis/catabolism and the oxidative stress genes (SREBP-1c/ACC-1/PPAR-α/PPAR-γ/Keap1/Nrf2). In addition, THL extracts reduced damage to the intestinal barrier (ZO-1/Mucin2/occludin) and increased the relative abundance of Lactobacillales, Ruminococcaceae, and Bifidobacteriales in NAFLD mice. In short, THL extracts alleviated NAFLD-related oxidative stress, lipid accumulation, and inflammation in NAFLD mice which may be via the gut-liver axis (gut barrier integrity and gut microbiota).

Antioxidant Peptides From Protein Hydrolysate of Marine Red Algae Eucheuma cottonii: Preparation, Identification, and Cytoprotective Mechanisms on H2O2 Oxidative Damaged HUVECs

To screen, prepare, identify, and evaluate the activities of natural antioxidants for treating chronic diseases caused by oxidative stress. Two algal proteins, namely ZD10 and ZD60, precipitated with 10 and 60% (NH₄)₂SO₄ were extracted from red algae Eucheuma cottonii (E. cottonii) and hydrolyzed using five proteolytic enzymes. The results showed that ZD60 played the most significant role in the enhancement of 2,2-diphenyl-1-picrylhydrazyl radical (DPPH⋅) scavenging activity (25.91 ± 0.24%) among all protein hydrolysates. Subsequently, six antioxidant peptides (EP1-EP6) were isolated from the papain hydrolysate of ZD60 by ultrafiltration and chromatography methods. Their amino acid sequences were identified as Thr-Ala (EP1), Met-Asn (EP2), Tyr-Ser-Lys-Thr (EP3), Tyr-Ala-Val-Thr (EP4), Tyr-Leu-Leu (EP5), and Phe-Tyr-Lys-Ala (EP6) with molecular weights of 190.21, 263.33, 497.55, 452.51, 407.51, and 527.62 Da, respectively. Of which, EP3, EP4, EP5, and EP6 showed strong scavenging activities on DPPH⋅, hydroxyl radical (HO⋅), and superoxide anion radical (O- 2⋅). Moreover, EP4 and EP5 could significantly protect human umbilical vein endothelial cells (HUVECs) from H₂O₂-induced oxidative damage by increasing the levels of antioxidant enzyme systems including superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) to reduce the levels of reactive oxygen species (ROS) (60.51 and 51.74% of model group) and malondialdehyde (MDA) (75.36 and 64.45% of model group). In addition, EP4 and EP5 could effectively inhibit H₂O₂-induced apoptosis by preventing HUVECs from early apoptosis to late apoptosis. These results indicated that the antioxidant peptides derived from E. cottonii, especially EP4 and EP5, could serve as the natural antioxidants applied in pharmaceutical products to treat chronic cardiovascular diseases caused by oxidative damage, such as coronary heart disease, atherosclerosis, etc.

Investigation of the Effect of Curcumin on Protein Targets in NAFLD Using Bioinformatic Analysis

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a prevalent metabolic disorder. Defects in function/expression of genes/proteins are critical in initiation/progression of NAFLD. Natural products may modulate these genes/proteins. Curcumin improves steatosis, inflammation, and fibrosis progression. Here, bioinformatic tools, gene−drug and gene-disease databases were utilized to explore targets, interactions, and pathways through which curcumin could impact NAFLD. METHODS: Significant curcumin−protein interaction was identified (high-confidence:0.7) in the STITCH database. Identified proteins were investigated to determine association with NAFLD. gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were analyzed for significantly involved targets (p < 0.01). Specificity of obtained targets with NAFLD was estimated and investigated in Tissue/Cells−gene associations (PanglaoDB Augmented 2021, Mouse Gene Atlas) and Disease−gene association-based EnrichR algorithms (Jensen DISEASES, DisGeNET). RESULTS: Two collections were constructed: 227 protein−curcumin interactions and 95 NAFLD-associated genes. By Venn diagram, 14 significant targets were identified, and their biological pathways evaluated. Based on gene ontology, most targets involved stress and lipid metabolism. KEGG revealed chemical carcinogenesis, the AGE-RAGE signaling pathway in diabetic complications and NAFLD as the most common significant pathways. Specificity to diseases database (EnrichR algorithm) revealed specificity for steatosis/steatohepatitis. CONCLUSION: Curcumin may improve, or inhibit, progression of NAFLD through activation/inhibition of NAFLD-related genes.

A double-edged sword: The Kelch-like ECH-associated protein 1-nuclear factor erythroid-derived 2-related factor 2-antioxidant response element pathway targeted pharmacological modulation in nonalcoholic fatty liver disease

Nutraceuticals activating the Kelch-like epichlorohydrin (ECH)-associated protein 1 (Keap1)-nuclear factor erythroid-derived 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway are widely used for nonalcoholic fatty liver disease (NAFLD) because no specific drugs are approved yet. The pathology of NAFLD is summarized as the 'two-hit' hypothesis. The 'first hit' includes insulin resistance and lipid accumulation. Oxidative stress, lipid peroxidation, and inflammation are regarded as the 'second hit'. Now there is controversial evidence about the roles of the Keap1-Nrf2-ARE pathway and its activators in NAFLD. When the 'first hit' occurs, the hepatocyte-specific Nrf2 deficiency reduces insulin resistance and significantly attenuates lipid accumulation. However, when the 'second hit' occurs, Nrf2 activation reduces oxidative stress and combats inflammation. We reviewed the roles of the Keap1-Nrf2-ARE pathway as a double-edged sword in the development of NAFLD, its inhibitors as a novel therapeutic approach for early NAFLD, and the nutraceutical character of its activators.

Epigenetics in NAFLD/NASH: Targets and therapy

Recently non-alcoholic fatty liver disease (NAFLD) has grabbed considerable scientific attention, owing to its rapid increase in prevalence worldwide and growing burden on end-stage liver diseases. Metabolic syndrome including obesity, diabetes, and hypertension poses a grave risk to NAFLD etiology and progression. With no drugs available, the mainstay of NAFLD management remains lifestyle changes with exercise and dietary modifications. Nonselective drugs such as metformin, thiazolidinediones (TZDs), ursodeoxycholic acid (UDCA), silymarin, etc., are also being used to target the interrelated pathways for treating NAFLD. Considering the enormous disease burden and the unmet need for drugs, fresh insights into pathogenesis and drug discovery are required. The emergence of the field of epigenetics offers a convincing explanation for the basis of lifestyle, environmental, and other risk factors to influence NAFLD pathogenesis. Therefore, understanding these epigenetic modifications to target the primary cause of the disease might prove a rational strategy to prevent the disease and develop novel therapeutic interventions. Apart from describing the role of epigenetics in the pathogenesis of NAFLD as in other reviews, this review additionally provides an elaborate discussion on exploiting the high plasticity of epigenetic modifications in response to environmental cues, for developing novel therapeutics for NAFLD. Besides, this extensive review provides evidence for epigenetic mechanisms utilized by several potential drugs for NAFLD.

Differentially expressed proteins obtained by label-free quantitative proteomic analysis reveal affected biological processes and functions in Western diet-induced steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a pathological manifestation with a progressive incidence in response to the epidemic of hepatic steatosis caused primarily by excessive energy intake. The present study unravels affected biological processes and functions by the presence of NASH in rats using a label-free quantitative proteomic strategy. NASH was induced by a Western high-sugar and high-fat diet for 20 weeks. The liver tissue was collected for histology and for a mass spectrometry-based proteomic protocol. The NASH group showed severe lipidosis, hepatocyte ballooning, and the presence of collagen deposition. Among upregulated proteins in NASH perilipin-2 (Plin-2; F6QBA3; difference [diff]: 2.29), ferritin heavy (Fth1; Q66HI5; diff: 2.19) and light (Ftl1; P02793; diff: 1.75) chains, macrophage migration inhibitory factor 1 (Mif; P30904; diff: 1.69), and fibronectin (Fn1; F1LST1; diff: 0.35) were observed, whereas among downregulated proteins, plectin (Q6S399; diff: -3.34), some Cyp2 family proteins of the cytochrome P450 complex, glutathione S-transferases, flavin-containing monooxygenase 1 (Fmo1; P36365; diff: -2.08), acetyl-CoA acetyltransferase 2 (Acat2; Q5XI22; diff: -2.25), acyl-CoA oxidase 2 (Acox2; F1LNW3; diff: -1.59), and acyl-CoA oxidase 3 (Acox3; F1M9A7; diff: -2.41) were observed. Also, biological processes and functions such as LPS/IL-1 inhibition of RXR, fatty acid metabolism, Nrf2-mediated oxidative stress response, xenobiotic metabolism, and PXR/RXR and CAR/RXR activations were predicted to be affected. In conclusion, the liver of rats with NASH induced by Western diet shows a decreased capacity of metabolizing lipids, fatty acids, and xenobiotic compounds that predispose fibrosis development.

Changes in Glutathione Content in Liver Diseases: An Update

Glutathione (GSH), a tripeptide particularly concentrated in the liver, is the most important thiol reducing agent involved in the modulation of redox processes. It has also been demonstrated that GSH cannot be considered only as a mere free radical scavenger but that it takes part in the network governing the choice between survival, necrosis and apoptosis as well as in altering the function of signal transduction and transcription factor molecules. The purpose of the present review is to provide an overview on the molecular biology of the GSH system; therefore, GSH synthesis, metabolism and regulation will be reviewed. The multiple GSH functions will be described, as well as the importance of GSH compartmentalization into distinct subcellular pools and inter-organ transfer. Furthermore, we will highlight the close relationship existing between GSH content and the pathogenesis of liver disease, such as non-alcoholic fatty liver disease (NAFLD), alcoholic liver disease (ALD), chronic cholestatic injury, ischemia/reperfusion damage, hepatitis C virus (HCV), hepatitis B virus (HBV) and hepatocellular carcinoma. Finally, the potential therapeutic benefits of GSH and GSH-related medications, will be described for each liver disorder taken into account.

Hepatocyte-specific Nrf2 deficiency mitigates high-fat diet-induced hepatic steatosis: Involvement of reduced PPARγ expression

Non-alcoholic fatty liver disease (NAFLD) is an emerging global disease with increasing prevalence. However, the mechanism of NAFLD development is not fully understood. To elucidate the cell-specific role of nuclear factor erythroid-derived 2-like 2 (NRF2) in the pathogenesis of NAFLD, we utilized hepatocyte- and macrophage-specific Nrf2-knockout [Nrf2(L)-KO and Nrf2(Mϕ)-KO] mice to examine the progress of NAFLD induced by high-fat diet (HFD). Compared to Nrf2-LoxP littermates, Nrf2(L)-KO mice showed less liver enlargement, milder inflammation and less hepatic steatosis after HFD feeding. In contrast, Nrf2(Mϕ)-KO mice displayed no significant difference in HFD-induced hepatic steatosis from Nrf2-LoxP control mice. Mechanistic investigations revealed that Nrf2 deficiency in hepatocytes dampens the expression of peroxisome proliferator-activated receptor γ (PPARγ) and its downstream lipogenic genes in the liver and/or primary hepatocytes induced by HFD and palmitate exposure, respectively. While PPARγ agonists augmented PPARγ expression and its transcriptional activity in primary hepatocytes in a NRF2-dependent manner, forced overexpression of PPARγ1 or γ2 distinctively reversed the decreased expression of their downstream genes fatty acid binding protein 4, lipoprotein lipase and/or fatty acid synthase caused by Nrf2 deficiency. We conclude that NRF2-dependent expression of PPARγ in hepatocytes is a critical initiating process in the development of NAFLD, suggesting that inhibition of NRF2 specifically in hepatocytes may be a valuable approach to prevent the disease.

Prunus Mahaleb Fruit Extract Prevents Chemically Induced Colitis and Enhances Mitochondrial Oxidative Metabolism via the Activation of the Nrf2 Pathway

SCOPE

Polyphenols exhibit their antioxidant activity downstream the activation of the nuclear factor erythroid 2-related factor 2 pathway (Nrf2), but the connection between lipid metabolism and the Nrf2 pathway is still unknown. Flavonoid-rich concentrated extract from Prunus mahaleb (mahaleb concentrated fruit extract; MCFE) may act on oxido-reductive homeostasis and hepatic lipid metabolism via Nrf2.

METHODS & RESULTS

MCFE ability to enhance the activity of Nrf2-mediated antioxidant/detoxifying enzymes is investigated in liver and colon of BALB/c mice. After a 4-week supplementation, macroscopic, histological, and biochemical signs of colitis are examined in mouse colon pulsed with 5% (w/v) dextran sodium sulfate (DSS). Untreated or DSS-supplemented mice are used as negative or positive control. MCFE effect on liver lipid metabolism and its possible link with the Nrf2 pathway is investigated. MCFE intake increases antioxidant defenses in mice colon and its pretreatment blunts pathological signs of colitis, as compared to positive control. In the liver, the increase in antioxidant defenses is associated with enhanced oxidative metabolism and with higher levels of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and of hemeoxygenase-1 (HO-1), in comparison with negative controls.

CONCLUSION

Cytoprotective and hypolipidemic effect produced by MCFE intake results, at least in part, by the activation of the Nrf2 pathway.