Role of oxidative stress in alcohol-induced liver injury

Nicotinamide Adenine Dinucleotide Metabolome Is Functionally Depressed in Patients Undergoing Liver Transplantation for Alcohol-Related Liver Disease

Nicotinamide adenine dinucleotide (NAD⁺) and related coenzymes play critical roles in liver function. Although hepatic alcohol metabolism depresses NAD⁺, current understanding of the NAD⁺ metabolome in alcohol‐related liver disease (ArLD) is based on animal models. We used human liver samples to quantify the NAD⁺ metabolome in ArLD with samples obtained at the time of liver transplantation or resection at University Hospitals Birmingham National Health Service Foundation Trust. The severity of steatohepatitis in liver from patients with ArLD was assessed with standard liver function tests and histology. NAD‐targeted quantitative metabolomic analysis of liver tissue was performed by liquid chromatography–tandem mass spectrometry. Seventy‐two human liver specimens were analyzed, including 43 with ArLD. The NAD⁺ metabolome differed significantly between different types of liver disease (two‐way analysis of variance [ANOVA], P = 0.001). ArLD liver tissue showed markedly depressed concentrations of NAD⁺ (432 μM vs. 616 μM in normal liver) and precursor molecules nicotinic acid and nicotinamide riboside. There was a significant overall difference in the NAD⁺ metabolome between ArLD samples with and without steatohepatitis (two‐way ANOVA, P = 0.018). After correcting for multiple comparisons, a significant difference for individual components of the metabolome was observed for the concentration of NAD⁺ (mean, 462 μM vs. 322 μM; P < 0.01 in nonsevere vs. severe alcoholic steatohepatitis, respectively). NAD⁺ concentration was inversely related to serum bilirubin concentration (r² = −0.127; P = 0.04) and positively correlated with myeloperoxidase activity (r² = 0.31; P = 0.003). The concentration of NAD⁺ and its precursor molecules are significantly reduced in ArLD and are associated with disease activity. Conclusion: Liver samples from people with ArLD show depressed NAD⁺ and precursor levels as well as depressed myeloperoxidase activity.

Komagataeibacter hansenii CGMCC 3917 alleviates alcohol-induced liver injury by regulating fatty acid metabolism and intestinal microbiota diversity in mice

The potential effects of Komagataeibacter hansenii CGMCC 3917 cells on alcohol-induced liver injury and their probable mechanisms were investigated. Male Kunming mice were orally administered with alcohol (10 mL per kg BW) alone or in combination with administration of K. hansenii CGMCC 3917 cells at 2 × 10⁸ and 2 × 10⁶ CFUs for 10 weeks. Administration of strain CGMCC 3917 cells, especially high dose administration, decreased the liver weights, fat gain, and fatty-acid metabolism-related enzyme SCD-1, ACC and FAS expressions and endotoxin release, which were elevated by alcohol treatment. Furthermore, the total contents of long chain fatty acids of the liver and serum in alcohol-treated mice supplemented with a high dose of strain CGMCC 3917 cells were decreased to 5.44 ± 0.19 μg mL^-1 and 3.66 ± 0.15 μg mL^-1 from 6.65 ± 0.31 μg mL^-1 and 4.52 ± 0.21 μg mL^-1, respectively. Conversely, the SCFAs decreased by ethanol treatment, particularly the acetic acid, propionic acid and butyric acid, were obviously enhanced in the faeces, colon and cecum of the mice supplemented with strain CGMCC 3917 cells. Moreover, strain CGMCC 3917 cells could regulate gut microbiome by significantly decreasing the abundance of Actinobacteria, Proteobacteria and Firmicutes, and dramatically increasing the abundance of Bacteroidetes in alcohol-treated mice. These findings suggest that K. hansenii CGMCC 3917 cells alleviate alcohol-induced liver damage via regulating fatty acid metabolism and intestinal microbiota diversity in mice.

The Functions of Mitochondrial 2',3'-Cyclic Nucleotide-3'-Phosphodiesterase and Prospects for Its Future

2′,3′-cyclic nucleotide-3′-phosphodiesterase (CNPase) is a myelin-associated enzyme that catalyzes the phosphodiester hydrolysis of 2’,3’-cyclic nucleotides to 2’-nucleotides. However, its presence is also found in unmyelinated cells and other cellular structures. Understanding of its specific physiological functions, particularly in unmyelinated cells, is still incomplete. This review concentrates on the role of mitochondrial CNPase (mtCNPase), independent of myelin. mtCNPase is able to regulate the functioning of the mitochondrial permeability transition pore (mPTP), and thus is involved in the mechanisms of cell death, both apoptosis and necrosis. Its participation in the development of various diseases and pathological conditions, such as aging, heart disease and alcohol dependence, is also reviewed. As such, mtCNPase can be considered as a potential target for the development of therapeutic strategies in the treatment of mitochondria-related diseases.

A Dual-Emissive Phosphorescent Polymeric Probe for Exploring Drug-Induced Liver Injury via Imaging of Peroxynitrite Elevation In Vivo

Drug-induced liver injury (DILI) is a widespread clinical problem. The pathophysiological mechanisms of DILI are complicated, and the traditional diagnostic methods for DILI have their limitations. Owing to its convenient operation, high sensitivity, and high specificity, luminescent sensing and imaging as an indispensable tool in biological research and clinical trials may provide an important means for DILI study. Herein, we report the rational design and preparation of a near-infrared dual-phosphorescent polymeric probe (P-ONOO) for exploring the DILI via specific imaging of peroxynitrite (ONOO^-) elevation in vivo, which was one of early markers of DILI and very difficult to be detected due to its short half-life and high reactive activity. With the utilization of P-ONOO, the raised ONOO^- was visualized successfully in the drug-treated hepatocytes with a high signal-to-noise ratio via ratiometric and time-resolved photoluminescence imaging. Importantly, the ONOO^- boost in the acetaminophen-induced liver injury in real time was verified, and the direct observation of the elevated ONOO^- production in ketoconazole-induced liver injury was achieved for the first time. Our findings may contribute to understanding the exact mechanism of ketoconazole-induced hepatotoxicity that is still ambiguous. Notably, this luminescent approach for revealing the liver injury works fast and conveniently.

Probiotic potential of lyophilized Lactobacillus plantarum GP

Purpose

Freeze drying of Lactobacillus plantarum GP in the presence of wall materials to achieve improved survival and retention of probiotic functionality during storage.

Methods

L. plantarum cells were lyophilized in the presence of inulin, fructooligosaccharides, lactulose, and/or skim milk. The lyophilized vials were stored at 8–10 °C up to 6 months and cells from these vials were evaluated for their probiotic functionality.

Results

L. plantarum GP freeze dried in the presence of wall material lactulose displayed viability of 98 ± 2.8% promising survival rate in the stress conditions of human digestive tract. The freeze dried cells of Lactobacilli retained the ability to adhere intestinal mucin layer, form biofilm, inhibit food spoilage and enteropathogens, produce β-galactosidase, bile salt hydrolase and γ-amino butyric acid, remove cholesterol, and scavenge DPPH radical.

Conclusion

Lyophilized cells of L. plantarum GP retained all the functional characteristics without any significant loss during storage, which prompts to incorporate prebiotics for the development of stable functional food products.

p-Coumaric acid attenuates alcohol exposed hepatic injury through MAPKs, apoptosis and Nrf2 signaling in experimental models

Overconsumption of alcohol could lead to severe liver injury that connects with oxidative stress, apoptosis, and inflammatory response. Previously, we proved that p-coumaric acid prevents ethanol induced reproductive toxicity; however, p-coumaric acid (PCA) on ethanol mediated hepatotoxicity has not been examined yet. In our work, we sought to study the potential of PCA in contradiction of ethanol induced hepatoxicity which linking with MAPKs, apoptosis, oxidative stress, and Nrf2 signaling. Foremost, we found that PCA could protect ethanol induced both L-02 and HepG2 hepatic cells by inhibiting cytotoxicity, ROS production, mitochondrial depolarization, and nuclear fragmentation. Also, in vivo experiments showed that the ethanol increasing the lipid markers (TBARS, CD) and depletes the antioxidants thereby increased phosphorylation of JNK, ERK, and p38 in rat liver tissues. Interestingly, PCA treatments inhibit ethanol exposed lipid markers and depletion of antioxidants, which directs the inhibition of MAPKs activation in rat liver tissues. We also noticed that the PCA protected ethanol induced apoptosis and liver markers by inhibiting the expression of Bax, caspases; AST, ALT, ALS, and LDH in liver tissue. Overall, the ameliorative consequence of PCA on ethanol induced oxidative stress and apoptosis was achieved by suppressing the expression of CYP2E1 and overexpressing Nrf2 and its target protein HO-1 in rat liver tissue. As a result, PCA was marked to be an effective antioxidant with notable hepatoprotection by inhibiting MAPKs and apoptosis signaling via enhancing Nrf2 signaling.

The Effect of Liver Hydrolysate on Chronic Ethanol-Induced Hepatic Injury in Normal Rats

The mechanism underlying the improvement in hepatic function by liver hydrolysate (LH) after ethanol-induced hepatic injury is unclear. Therefore, we investigated the effects of LH administration on chronic ethanol-induced hepatic injury in normal rats and the mechanism underlying the improvement of its symptoms by LH. LH attenuated liver damage and reduced oxidative stress after chronic ethanol-induced hepatic injury in normal rats. LH treatment reduced hepatic injury biomarkers of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT). LH treatment also decreased levels of 8-hydroxy-deoxyguanosine (8-OHdG) as oxidative stress marker. LH may prove beneficial to prevent the liver damage of chronic ethanol, at least in part, by alleviating oxidative stress.

Evaluation of the hepatoprotective effect of Yigan mingmu oral liquid against acute alcohol-induced liver injury in rats

Background

Yigan mingmu oral liquid (YGMM) is a herbal medicine based on a famous Chinese herbal formula that has been used for sore eyes for more than 400 years. Eye health is closely associated with the liver based on TCM. This study aimed to investigate the hepatoprotective effect of YGMM against acute liver injury induced by alcohol in rats.

Methods

Experimental rats were administered with silymarin and YGMM through the gastric gavage during the entire experiment. Starting from the 11th day, the rats were administered orally with 14 ml/kg Red Star Erguotou Liquor, a popular brand, at 4 h after the dose of silymarin (100 mg/kg) and YGMM (1, 2.5 and 5 ml/kg in low, middle and high dosage group, respectively) once a day for 4 weeks except for the rats in the normal group. Biochemical parameters, including ALT, AST, TB, TG, T-SOD, GSH, and MDA were detected to evaluate the protective effect of YGMM. Pathological changes were observed through histopathological examination.

Results

Treatment with YGMM exhibited a significant protective effect by reversing the biochemical parameters (ALT, AST, TB, TG, and GSH) and histopathological changes. Histopathological examination by Oil Red O Staining Solution showed that lipid droplets were significantly reduced in the silymarin and YGMM groups (p < 0.001) when compared to alcohol group.

Conclusions

YGMM exhibits a significant hepatoprotective activity against acute liver injury induced by alcohol in rats.

Impaired Glycolysis Promotes AlcoholExposure-Induced Apoptosis in HEI-OC1 Cells via Inhibition of EGFR Signaling

Glucose metabolism is an important metabolic pathway in the auditory system. Chronic alcohol exposure can cause metabolic dysfunction in auditory cells during hearing loss. While alcohol exposure has been linked to hearing loss, the mechanism by which impaired glycolysis promotes cytotoxicity and cell death in auditory cells remains unclear. Here, we show that the inhibition of epidermal growth factor receptor (EGFR)-induced glycolysis is a critical mechanism for alcohol exposure-induced apoptosis in HEI-OC1 cells. The cytotoxicity via apoptosis was significantly increased by alcohol exposure in HEI-OC1 cells. The glycolytic activity and the levels of hexokinase 1 (HK1) were significantly suppressed by alcohol exposure in HEI-OC1 cells. Mechanistic studies showed that the levels of EGFR and AKT phosphorylation were reduced by alcohol exposure in HEI-OC1 cells. Notably, HK1 expression and glycolytic activity was suppressed by EGFR inhibition in HEI-OC1 cells. These results suggest that impaired glycolysis promotes alcohol exposure-induced apoptosis in HEI-OC1 cells via the inhibition of EGFR signaling.

Aronia melanocarpa Prevents Alcohol-Induced Chronic Liver Injury via Regulation of Nrf2 Signaling in C57BL/6 Mice

Aronia melanocarpa (AM), which is rich in anthocyanins and procyanidins, has been reported to exert antioxidative and anti-inflammatory effects. This study aimed to systematically analyze the components of AM and explore its effects on alcohol-induced chronic liver injury in mice. A component analysis of AM revealed 17 types of fatty acids, 17 types of amino acids, 8 types of minerals, and 3 types of nucleotides. Chronic alcohol-induced liver injury was established in mice via gradient alcohol feeding over a period of 6 months, with test groups orally receiving AM in the last 6 weeks. AM administration yielded potential hepatoprotective effects by alleviating weight gain and changes in organ indexes, decreasing the ratio of alanine aminotransferase/aspartate aminotransferase, reducing lipid peroxidation, enhancing antioxidant activities, decreasing oxidation-related factor levels, and regulating inflammatory cytokine levels. Histological analyses suggest that AM treatment markedly prevented organ damage in alcohol-exposed mice. Furthermore, AM activated nuclear factor erythroid 2-like 2 (Nrf2) by downregulating the expression of Kelch-like ECH-associated protein 1, resulting in elevated downstream antioxidative enzyme levels. AM activated Nrf2 via modulation of the phosphatidylinositol-3-hydroxykinase/protein kinase B signaling pathway. Altogether, AM prevented alcohol-induced liver injury, potentially by suppressing oxidative stress via the Nrf2 signaling pathway.

An inverse agonist of estrogen-related receptor γ regulates 2-arachidonoylglycerol synthesis by modulating diacylglycerol lipase expression in alcohol-intoxicated mice

Chronic alcohol feeding increases the levels of 2-arachidonoylglycerol (2-AG) in the liver, which activates hepatic cannabinoid receptor type 1 (CB1R), leading to oxidative liver injury. 2-AG biosynthesis is catalyzed by diacylglycerol lipase (DAGL). However, the mechanisms regulating hepatic DAGL gene expression and 2-AG production are largely unknown. In this study, we show that CB1R-induced estrogen-related receptor γ (ERRγ) controls hepatic DAGL gene expression and 2-AG levels. Arachidonyl-2'-chloroethylamide (ACEA), a synthetic CB1R agonist, significantly upregulated ERRγ, DAGLα, and DAGLβ, and increased 2-AG levels in the liver (10 mg/kg) and hepatocytes (10 μM) of wild-type (WT) mice. ERRγ overexpression upregulated DAGLα and DAGLβ expressions and increased 2-AG levels, whereas ERRγ knockdown abolished ACEA-induced DAGLα, DAGLβ, and 2-AG in vitro and in vivo. Promoter assays showed that ERRγ positively regulated DAGLα and DAGLβ transcription by binding to the ERR response element in the DAGLα and DAGLβ promoters. Chronic alcohol feeding (27.5% of total calories) induced hepatic steatosis and upregulated ERRγ, leading to increased DAGLα, DAGLβ, or 2-AG in WT mice, whereas these alcohol-induced effects did not occur in hepatocyte-specific CB1R knockout mice or in those treated with the ERRγ inverse agonist GSK5182 (40 mg/kg in mice and 10 μM in vitro). Taken together, these results indicate that suppression of alcohol-induced DAGLα and DAGLβ gene expressions and 2-AG levels by an ERRγ-specific inverse agonist may be a novel and attractive therapeutic approach for the treatment of alcoholic liver disease.

Carotenoids and fatty liver disease: Current knowledge and research gaps

Carotenoids form an important part of the human diet, consumption of which has been associated with many health benefits. With the growing global burden of liver disease, increasing attention has been paid on the possible beneficial role that carotenoids may play in the liver. This review focuses on carotenoid actions in non-alcoholic fatty liver disease (NAFLD), and alcoholic liver disease (ALD). Indeed, many human studies have suggested an association between decreased circulating levels of carotenoids and increased incidence of NAFLD and ALD. The literature describing supplementation of individual carotenoids in rodent models of NAFLD and ALD is reviewed, with particular attention paid to β-carotene and lycopene, but also including β-cryptoxanthin, lutein, zeaxanthin, and astaxanthin. The effect of beta-carotene oxygenase 1 and 2 knock-out mice on hepatic lipid metabolism is also discussed. In general, there is evidence to suggest that carotenoids have beneficial effects in animal models of both NAFLD and ALD. Mechanistically, these benefits may occur via three possible modes of action: 1) improved hepatic antioxidative status broadly attributed to carotenoids in general, 2) the generation of vitamin A from β-carotene and β-cryptoxanthin, leading to improved hepatic retinoid signaling, and 3) the generation of apocarotenoid metabolites from β-carotene and lycopene, that may regulate hepatic signaling pathways. Gaps in our knowledge regarding carotenoid mechanisms of action in the liver are highlighted throughout, and the review ends by emphasizing the importance of dose effects, mode of delivery, and mechanism of action as important areas for further study. This article is part of a Special Issue entitled Carotenoids recent advances in cell and molecular biology edited by Johannes von Lintig and Loredana Quadro.

Therapeutic potency of fermented field water-dropwort (Oenanthe javanica (Blume) DC.) in ethanol-induced liver injury

Alcohol overconsumption and abuse leads to alcoholic liver disease (ALD), which is a major chronic liver disease worldwide. Field water-dropwort (Oenanthe javanica (Blume) DC.) is a small perennial herb and has been cultivated in Asia for thousands of years and traditionally used to treat various diseases including hepatitis, jaundice, hypertension and polydipsia, as well as its therapeutic benefits have been recognized for centuries in Asia. Although several studies have reported that water-dropwort extracts have pharmacological effects on various diseases, the pharmacological ability of fermented field water-dropwort in ALD is not reported yet. Thus, we investigated the effect of fermented field water-dropwort extracts (FDE) on chronic plus binge ethanol-induced liver injury. C57BL/6 male mice (9 weeks old) were fed on a Lieber–DeCarli diet containing 6.6% ethanol for 10 days with parallel saline or FDE orally administered each day. Ethanol-induced hepatic triglyceride (TG) levels and the mRNA levels of TG synthesis-related genes such as sterol regulatory element binding protein 1 (SREBP1), acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS) were decreased in the liver of mice with FDE administration. Moreover, FDE administered mice showed decreasing ethanol-induced oxidative stress such as increasing oxidised glutathione and lipid peroxidation in the liver. In primary hepatic cells, FDE treated cells exhibited decreased ethanol-induced lipid accumulation and the mRNA levels of TG synthesis-related genes, SREBP-1, ACC and FAS. In conclusions, FDE has the potential to be explored as a candidate treatment agent for ALD by inhibiting TG synthesis and blocking of oxidative stress.

Alcohol overconsumption and abuse leads to alcoholic liver disease (ALD), which is a major chronic liver disease worldwide.

Redox Control of the Immune Response in the Hepatic Progenitor Cell Niche

The liver commonly self-regenerates by a proliferation of mature cell types. Nevertheless, in case of severe or protracted damage, the organ renewal is mediated by the hepatic progenitor cells (HPCs), adult progenitors capable of differentiating toward the biliary and the hepatocyte lineages. This regeneration process is determined by the formation of a stereotypical niche surrounding the emerging progenitors. The organization of the HPC niche microenvironment is crucial to drive biliary or hepatocyte regeneration. Furthermore, this is the site of a complex immunological activity mediated by several immune and non-immune cells. Indeed, several cytokines produced by monocytes, macrophages and T-lymphocytes may promote the activation of HPCs in the niche. On the other side, HPCs may produce pro-inflammatory cytokines induced by liver inflammation. The inflamed liver is characterized by high generation of reactive oxygen and nitrogen species, which in turn lead to the oxidation of macromolecules and the alteration of signaling pathways. Reactive species and redox signaling are involved in both the immunological and the adult stem cell regeneration processes. It is then conceivable that redox balance may finely regulate the immune response in the HPC niche, modulating the regeneration process and the immune activity of HPCs. In this perspective article, we summarize the current knowledge on the role of reactive species in the regulation of hepatic immunity, suggesting future research directions for the study of redox signaling on the immunomodulatory properties of HPCs.

Effects of Ethyl Pyruvate on Bile Duct Ligation-Induced Liver Fibrosis by Regulating Nrf2 Pathway and Proinflammatory Cytokines in Rats

Aim

The aim of this paper is to investigate the effects of ethyl pyruvate (EP) on experimental liver fibrosis induced by bile duct ligation (BDL) and explore the underlying molecular mechanisms.

Material and Method

Rats were randomly divided into three groups: the sham group, the BDL group, and the BDL+EP group. Liver fibrosis was induced by common bile duct ligation and was evaluated by serum biochemical parameter levels, Masson's trichrome staining, α-SMA expression, and collagen I deposition. The levels of Nrf2 signaling pathway-related antioxidant genes (Nrf2, SOD2, NQO1, and GSH-Px) in liver tissues were also measured. Meanwhile, the mRNA expression levels of HMGB1, IL-1β, TNF-α, and HSP27 were analyzed. In BDL-induced liver fibrosis rats, the successfully established model was confirmed by the significant increase of serum ALT and AST levels, the high liver fibrosis score, α-SMA expression, and collagen deposition.

Results

Compared with the BDL group, EP administration could diminish fibrosis level and substantially increase the expression of Nrf2 signaling pathway-related antioxidant genes. Furthermore, EP significantly suppressed the mRNA expression levels of HMGB1, IL-1β, TNF-α, and HSP27.

Conclusions

The results suggested that EP administration could effectively inhibit the liver fibrosis induced by BDL in rat, which may be associated with the enhanced activity of Nrf2 to mediate antioxidant enzyme system and downregulate the inflammatory genes.

Compound ammonium glycyrrhizin protects hepatocytes from injury induced by lipopolysaccharide/florfenicol through oxidative stress and a MAPK pathway

Compound ammonium glycyrrhizin (CAG) protects hepatocytes from injury induced by lipopolysaccharide (LPS)/florfenicol (FFC) through a mitochondrial pathway. On this basis, the research was aimed to investigate whether CAG protects hepatocytes from injury induced by LPS/FFC through oxidative stress and the MAPK pathway. For liver injury induced by LPS/FFC, not only CAG can protect hepatocytes and prevent membrane permeability from being increased, but also the activities of ALT and AST were decreased significantly by CAG. Flow cytometry analysis indicated that the apoptosis rate (35.65 ± 2.48%) of LPS/FFC group was significantly higher than that of the control group (8.60 ± 0.32%). CAG (concentration of 0.01 μg/mL, 0.1 μg/mL, 1 μg/mL) significantly decreased the apoptosis rate (23.69 ± 0.54%, 14.92 ± 2.45% and 9.47 ± 1.28%) for the liver injury induced by LPS/FFC. The activities of SOD and GSH were increased with the increased concentration of CAG, and the activity of MDA was decreased with the increased concentration of CAG. All the mRNA and proteins expression levels were increased by LPS/FFC-induced liver injury which associated with the MAPK pathway, and those of the CAG group were decreased with the increased concentration of CAG. And the change of caspase-3 activity was consistent with that of proteins and mRNA. It is suggested that LPS/FFC can induce liver injury through apoptosis and the CAG can protect hepatocytes from injury through the MAPK pathway and oxidative stress.

The protective effect of quercetin in the alcohol-induced liver and lymphoid tissue injuries in newborns

Recently published experimental and clinical studies indicate that oxidative stress leads to the pathogenesis and progression of alcohol-induced tissue injuries. Quercetin is a type of flavonoid compound that influences antioxidant and anti-inflammatory activities have protective and therapeutic effects for treating various diseases including diabetes mellitus and neuro-degenerative diseases. In this study, fetal alcohol syndrome was tested in rat models, with the aim of verifying the protective effect of quercetin in preventing alcohol-induced liver and lymphoid tissue (thymus, spleen, and lymph nodes) injuries on the 21st day for the offspring of alcohol treated mother rats. The pregnant rats were randomly assigned into four groups. The control group (C) (n = 3) of pregnant rats received only physiological saline intraperitoneally (i.p.) throughout the pregnancy (1 to 21 days gestation) and during lactation until postnatal day 21. The quercetin positive control group (QT) of pregnant rats (n = 3) received quercetin at 50 mg/kg/days i.p. for the same period. The ethanol treatment group (E) (n = 3) of pregnant rats received 1 ml/day of 40% v/v ethanol (4 g/kg) intragastrically (i.g) for the same period. The model group of pregnant rats (EQ) received ethanol + quercetin (n = 3) with a dose of 1 ml/day of v/v ethanol (4 g/kg i.g.) and quercetin at 50 mg/kg body weight per day i.p. for the same period. Ten offspring were used in each of the C, QT, E and EQ groups. Malondialdehyde (MDA), protein carbonyl content (PC) and chemiluminescence levels (CL) in liver and lymphoid tissues significantly increased in group E versus the C group (P < 0.05-P < 0.001) whereas glutathione levels (GSH), glutathione reductase (GR), glutathione peroxidase (GP), superoxide dismutase (SOD), and catalase (CAT) activities significantly decreased in group E compared to the C group (P < 0.05-< 0.001). However, tissue MDA, PC, and CL levels decreased in the EQ group compared to group E. GSH level, GP, GR, SOD, and CAT activity were significantly increased by quercetin (P < 0.05-P < 0.001). The plasma TNFα, IL-1β, and IL-6 levels and NF-κB activation significantly increased in group E compared to the C and QT groups, but IL-10 significantly decreased in group E compared to the C and QT groups. The TNFα, IL-1β, and IL-6 levels and NF-κB activation significantly decreased in group EQ compared to group E. In conclusion, quercetin has a protective effect against maternal alcohol-induced oxidative and inflammatory damage in the liver and lymphoid tissues of newborn rats.

Digoxin improves steatohepatitis with differential involvement of liver cell subsets in mice through inhibition of PKM2 transactivation

The cardiac glycoside digoxin was identified as a potent suppressor of pyruvate kinase isoform 2-hypoxia-inducible factor-α (PKM2-HIF-1α) pathway activation in liver injury mouse models via intraperitoneal injection. We have assessed the therapeutic effects of digoxin to reduce nonalcoholic steatohepatitis (NASH) by the clinically relevant oral route in mice and analyzed the cellular basis for this effect with differential involvement of liver cell subsets. C57BL/6J male mice were placed on a high-fat diet (HFD) for 10 wk and started concurrently with the gavage of digoxin (2.5, 0.5, 0.125 mg/kg twice a week) for 5 wk. Digoxin significantly reduced HFD-induced hepatic damage, steatosis, and liver inflammation across a wide dosage range. The lowest dose of digoxin (0.125 mg/kg) showed significant protective effects against liver injury and sterile inflammation. Consistently, digoxin attenuated HIF-1α sustained NLRP3 inflammasome activation in macrophages. We have reported for the first time that PKM2 is upregulated in hepatocytes with hepatic steatosis, and digoxin directly improved hepatocyte mitochondrial dysfunction and steatosis. Mechanistically, digoxin directly bound to PKM2 and inhibited PKM2 targeting HIF-1α transactivation without affecting PKM2 enzyme activation. Thus, oral digoxin showed potential to therapeutically inhibit liver injury in NASH through the regulation of PKM2-HIF-1α pathway activation with involvement of multiple cell types. Because of the large clinical experience with oral digoxin, this may have significant clinical applicability in human NASH.NEW & NOTEWORTHY This study is the first to assess the therapeutic efficacy of oral digoxin on nonalcoholic steatohepatitis (NASH) in a high-fat diet (HFD) mouse model and to determine the divergent of cell type-specific effects. Oral digoxin reduced liver damage, steatosis, and inflammation in HFD mice. Digoxin attenuated hypoxia-inducible factor (HIF)-1α axis-sustained inflammasome activity in macrophages and hepatic oxidative stress response in hepatocytes via the regulation of PKM2-HIF-1α axis pathway activation. Oral digoxin may have significant clinical applicability in human NASH.

Beneficial Role of ROS in Cell Survival: Moderate Increases in H2O2 Production Induced by Hepatocyte Isolation Mediate Stress Adaptation and Enhanced Survival

High levels of reactive oxygen species (ROS) can lead to impairment of cell structure, biomolecules' loss of function and cell death and are associated with liver diseases. Cells that survive increased ROS often undergo malignant transformation. Many cancer cells tolerate high levels of ROS. Here we report a transiently increased production of H₂O₂ and concomitant upregulation of antioxidative enzymes triggered by hepatocyte isolation; the H₂O₂ levels revert in about two days in culture. Three-day survival rate of the isolated cells in the presence of 2.5-fold increase of H₂O₂ is almost 80%. Apoptosis activation through the mitochondrial pathway is meanwhile reduced by inhibition of caspase-9 triggering. This reduction depends on the amount of H₂O₂ production, as decreased production of H₂O₂ in the presence of an antioxidant results in increased apoptosis triggering. These stress adaptations do not influence urea production, which is unchanged throughout the normal and stress adapted phases. We conclude that hepatocytes' stress adaptation is mediated by increased ROS production. In this case, high ROS improve cell survival.

Antigenotoxic and antimutagenic effects of Myrciaria dubia juice in mice submitted to ethanol 28-day treatment

Myrciaria dubia is a native plant from the Amazon region which produces red-purplish fruit rich in antioxidant compounds such as ascorbic acid, carotenoids, and phenolic. M. dubia fruit is used to prepare juices considered to possess high nutritional content providing health benefits. The aim of this study was to examine the ability of M. dubia juice to protect DNA against genomic instability induced by sub-acute ethanol consumption attributed to oxidative stress. Mice were treated for 28 days with juice at 25% and 50% diluted in distilled water or with the diluted combination juice plus ethanol (5 g/kg). The genotoxic/antigenotoxic and mutagenic/antimutagenic effects were assessed using comet assay in blood, liver, and kidney and micronucleus (MN) test with bone marrow. In addition, the mutagenicity was also evaluated using Salmonella/microsome assay. Phytochemical compounds were determined using HPLC/PDA/MS/MS. The juice did not induce genotoxic effects in blood, kidney, and liver cells at both doses. In combination with ethanol, the juice reduced the alcohol-mediated DNA damage in all tissues analyzed. Further, the juice did not produce mutagenic effects and decreased mutagenicity induced by ethanol in the bone marrow. The anthocyanins were major compounds detected by HPLC/PDA/MS/MS, which modulated genotoxic and mutagenic effects initiated by ethanol and at least in part appeared responsible for the observed antigenotoxic and antimutagenic effects of M. dubia juice.

Betulin attenuated liver damage by prevention of hepatic mitochondrial dysfunction in rats with alcoholic steatohepatitis

Betulin, a pentacyclic triterpene, possesses antioxidant, anti-inflammatory and hepatoprotective properties. The aim of this study was to evaluate the impact of liver mitochondria in hepatoprotection of betulin using a rat model of alcoholic steatohepatitis induced by ethanol administration (4 g/kg, intragastric) for 8 weeks. The treatment with betulin (50 and 100 mg/kg b.w., intragastric) during this period attenuated the histological signs of steatohepatitis and lowered the serum and liver triglyceride contents, as well as the serum activities of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase. Betulin (100 mg/kg) decreased the liver/body weight ratio and inhibited the increase in the serum levels of TNFα, IL-1β, TGFβ, and hyaluronic acid, demonstrating hepatoprotective, anti-inflammatory, and antifibrotic potential. Betulin also inhibited the formation of superoxide anions in mitochondria and the end-products of lipid peroxidation in liver tissue, the amount of which was significantly increased in ethanol-treated rats. The disturbances in mitochondrial respiration, uncoupling of oxidative phosphorylation and decreasing of mitochondrial complex I, II, and IV activities in rats with steatohepatitis, were reverted by betulin administration. The increased susceptibility of mitochondria to Ca2+-induced permeability transition pore formation in the hepatitis group was improved in rats treated with betulin. In conclusion, betulin, having antioxidant properties, exerts a beneficial effect in the rat model of alcoholic steatohepatitis via prevention of liver mitochondria dysfunction, which may be attributed to the inhibition of mitochondrial permeability transition.

The SGLT2 inhibitor dapagliflozin attenuates the activity of ROS-NLRP3 inflammasome axis in steatohepatitis with diabetes mellitus

Background

Diabetes mellitus (DM) is considered as a risk factor for the progress of liver diseases. After tissue damage, there is the highest amplitude of ubiquitously sterile inflammatory response in the liver, resulting in a major clinical consequence concerning a high prevalence of steatohepatitis in DM patients. This study aimed to investigate the inhibitory efficacy of dapagliflozin (DAPA), a sodium glucose cotransporter-2 (SGLT2) inhibitor, on experimental steatohepatitis with DM.

Methods

DM-steatohepatitis model was established by dual intraperitoneal injection of streptozotocin (STZ) and feeding with the high-fat diet (HFD) in apolipoprotein E-deficient (ApoE^-/-) mice (n=40). The mice were concurrently treated with DAPA (1 mg/kg/d) by gavage for 12 weeks.

Results

In ApoE^-/- mice, dual HFD/STZ dramatically induced hepatic damage and inflammation as compared with HFD alone. DAPA treatment was effective to protect from hepatic damage and inflammation in dual HFD/STZ treated ApoE^-/- mice. DAPA also significantly the probability decreased the blood glucose, hepatic lipid accumulation, liver steatosis, and fibrotic response in dual HFD/STZ treated ApoE^-/- mice. Further mechanistic investigations indicated that the protection of DAPA on diabetic liver injury was associated with the suppressed production of hepatic reactive oxygen species (ROS) and malondialdehyde (MDA) and the inhibited activation of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome.

Conclusions

These data demonstrate the efficacy of DAPA for protecting liver damage, inflammation and steatosis from experimental steatohepatitis with DM, and indicate a possible involvement of the inhibited activity of ROS-NLRP3 inflammasome.

Low dose of chronic ethanol exposure in adult zebrafish induces hepatic steatosis and injury

Chronic alcohol consumption is a major cause of chronic liver disease worldwide. Adult zebrafish have emerged as a new vertebrate model of alcoholic liver disease. In previous research, a high dose of chronic ethanol treatment induced characteristic features of steatosis and hepatic injury in adult zebrafish, yet the ethanol concentration in that study was significantly higher than the lethal dose in humans. In the current study, we examined whether a low dose of chronic ethanol exposure in adult zebrafish induced the metabolic and pathological features seen in alcoholic liver disease. We found that chronic ethanol treatment at 0.2% ethanol (v/v) concentration for 4 weeks induced a significant elevation of serum glucose and triacylglycerol in adult zebrafish. In addition, serum alanine aminotransferase activity was significantly elevated after ethanol treatment. Histological analysis revealed steatosis and hepatocyte ballooning phenotype. Gene expression analysis using quantitative real-time PCR suggested that ethanol treatment induced inflammation, apoptosis, and fibrosis. In addition, we found significant increases in gene expression involved in glucose and lipid metabolism as well as mitochondrial biogenesis and function. Importantly, expression of genes involved in oxidative and endoplasmic reticulum stress, two major stress signaling pathways underlying hepatic injury in alcoholic liver disease, were highly upregulated in the livers of adult zebrafish after chronic ethanol treatment. In conclusion, we found that 4 weeks of low dose ethanol exposure leads to typical ethanol-induced liver disease, with pathological and gene expression patterns.

A comprehensive review of cytochrome P450 2E1 for xenobiotic metabolism

Cytochrome P450 2E1 (CYP2E1) plays a vital role in drug-induced hepatotoxicity and cancers (e.g. lung and bladder cancer), since it is responsible for metabolizing a number of medications and environmental toxins to reactive intermediate metabolites. CYP2E1 was recently found to be the highest expressed CYP enzyme in human livers using a proteomics approach, and CYP2E1-related toxicity is strongly associated with its protein level that shows significant inter-individual variability related to ethnicity, age, and sex. Furthermore, the expression of CYP2E1 demonstrates regulation by extensive genetic polymorphism, endogenous hormones, cytokines, xenobiotics, and varying pathological states. Over the past decade, the knowledge of pharmacology, toxicology, and biology about CYP2E1 has grown remarkably, but the research progress has yet to be summarized. This study presents a timely systematic review on CYP2E1's xenobiotic metabolism, genetic polymorphism, and inhibitors, with the focus on their clinical relevance for the efficacy and toxicity of various CYP2E1 substrates. Moreover, several knowledge gaps have been identified towards fully understanding the potential interactions among different CYP2E1 substrates in clinical settings. Through in-depth analyses of these knowns and unknowns, we expect this review will aid in future drug development and improve management of CYP2E1 related clinical toxicity.

Targeting of oxidative stress and inflammation through ROS/NF-kappaB pathway in phosphine-induced hepatotoxicity mitigation

AIMS

Poisoning with aluminium phosphide (AlP) commonly has a high rate of mortality and morbidities. Phosphine gas is the main cause of AlP poisoning that has deleterious effect on multi-organs especially heart, kidney, and liver. Furthermore, several studies reported that resveratrol has cytoprotective effects through its pleiotropic property. The purpose of this study was to estimate the dose-dependent role of resveratrol on phosphine induced acute hepatic toxicity in rat model.

MAIN METHODS

The rats have been exposed to LD₅₀ of AlP (12 mg/kg) by gavage, and resveratrol doses (20, 40, and 80 mg/kg) were injected 30 min after intoxication. After 24 h, the serum and liver tissue were collected for present study.

KEY FINDINGS

The results indicated that phosphine causes an alteration in oxidative stress markers including elevation of ROS, and GSH level, MPO activity, reduction in SOD, catalase and G6PD activity as well as reduction in SOD1 and catalase expression. Furthermore, phosphine significantly induced phosphorylation of IkappaB, NF-kappaB and up-regulation of TNF-α, IL-1β, IL-6, and ICAM-1 expression. Also, phosphine induces markedly reduced hepatocytes lives cell and elevated apoptosis and necrosis. Co-treatment of resveratrol in a dose-dependent manner reversed aforementioned alterations. All in all, histological analysis indicated a deleterious effect of phosphine on the liver, which is mitigated by resveratrol administration.

SIGNIFICANCE

The results of the present study suggest targeting ROS/NF-kappaB signalling pathway by resveratrol may have a significant effect on the improvement of hepatic injury induced by phosphine. It also may be a possible candidate for the treatment of phosphine-poisoning.

Mangiferin improves hepatic damage-associated molecular patterns, lipid metabolic disorder and mitochondrial dysfunction in alcohol hepatitis rats

This study was conducted to investigate the beneficial effects and possible mechanism of action of mangiferin (MF) in alcohol hepatitis (AH) rats. Building on our previous study, the damage-associated molecular patterns (DAMPs), lipid metabolic disorder and mitochondrial dysfunction were investigated. MF effectively regulated the abnormal liver function, the levels of alcohol, FFAs and metal elements in serum. More importantly, MF improved the expression levels of mRNA and protein of PPAR-γ, OPA-1, Cav-1, EB1, NF-κB p65, NLRP3, Cas-1 and IL-1β, and decreased the positive protein expression rates of HSP90, HMGB1, SYK, CCL20, C-CAS-3, C-PARP and STARD1. Additionally, MF decreased the levels of fumarate, cAMP, xanthurenic acid and d-glucurone-6,3-lactone, and increased the levels of hippuric acid and phenylacetylglycine, and then adjusted the changes of phenylalanine metabolism, TCA cycle and ascorbate and aldarate metabolic pathways. The above results suggested that MF can effectively prevent AH by modulating specific AH-associated genes, potential biomarkers and metabolic pathways in AH rats, etc.

Activation of the p38/MAPK pathway regulates autophagy in response to the CYPOR-dependent oxidative stress induced by zearalenone in porcine intestinal epithelial cells

Zearalenone (ZEA) can widely contaminate crops and agricultural products. The ingestion of ZEA-contaminated food or feed affects the integrity and functions of the intestines. In this study, we aimed to find the potential protective mechanism against ZEA ingestion. We found that ZEA induced cell death in IPEC-J2 cells. Meanwhile, the cytoprotective autophagy was activated in ZEA-treated cells. Further studies demonstrated that a p38/MAPK inhibitor down-regulated autophagy and increased cell death compared to those of the controls. Furthermore, ZEA could induce the accumulation of ROS, and eliminating ROS with NAC resulted in a decline in cell death, p38/MAPK phosphorylation, and the expression of LC3-II compared to those of ZEA-group. In addition, cytochrome P450 reductase (CYPOR) was significantly increased in ZEA-treated cells compared to that in the controls, and an inhibitor of CYPOR decreased ROS levels and mitigated cell death compared to those of the ZEA-group. More importantly, we found that blocking both p38/MAPK signalling and autophagy could enhance CYPOR expression and elevate ROS levels. Overall, our study indicated that the p38/MAPK pathway could activate protective autophagy in response to the CYPOR-dependent oxidative stress that was induced by ZEA in IPEC-J2 cells.

Chitinase-3-like-1 deficiency attenuates ethanol-induced liver injury by inhibition of sterol regulatory element binding protein 1-dependent triglyceride synthesis

OBJECTIVE

Alcohol overconsumption and abuse lead to alcoholic liver disease (ALD), which is a major chronic liver disease worldwide. Chitinase-3-like protein 1 (CHI3L1) have an important role in the pathogenesis of inflammatory disease. However, the role of CHI3L1 in ALD has not yet been reported. In the present study, we investigated the effect of CHI3L1 on chronic plus binge ethanol-induced liver injury.

METHODS

CHI3L1 knock out (KO) mice and their littermate control mice based on C57BL/6 (10-12 weeks old) were fed on a Lieber-DeCarli diet containing 6.6% ethanol for 10 days. And, CHI3L1 siRNA or CHI3L1 expressing vector was transfected HepG2 cells were treated with ethanol or without.

RESULTS

Ethanol-induced hepatic triglyceride (TG) levels and the mRNA levels of TG synthesis-related genes such as acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS) and stearoyl-CoA desaturase-1 (SCD1) were decreased in the liver of CHI3L1 knock out (KO) mice and the HepG2 cells transfected with CHI3L1 siRNA. Increased mRNA level and activation of SREBP1 which is transcription factor of ACC, FAS and SCD1 by ethanol feeding were reduced in the liver of ethanol-fed CHI3L1 KO mice. Moreover, ethanol-induced SREBP1 luciferase activity and mRNA level of SREBP1, ACC, FAS and SCD1 were also decreased in the HepG2 cells transfected with CHI3L1 siRNA, while those were further increased in the HepG2 cells treated with recombinant human CHI3L1. Furthermore, oxidative stress and up-regulated pro-inflammatory cytokines by ethanol were recovered in the liver of ethanol-fed CHI3L1 KO mice.

CONCLUSION

Our finding suggest that inhibition of CHI3L1 suppressed ethanol-induced liver injury through inhibition of TG synthesis, and the blocking of oxidative stress and hepatic inflammation induced SREBP1 activity could be significant.

Probiotics for Alleviating Alcoholic Liver Injury

Many animal experiments and clinical trials showed that probiotics are effective for the treatment of alcoholic liver disease. Alcohol disrupts the composition of intestinal flora; probiotics modulate the gut microbiota and reverse alcohol-associated intestinal barrier dysfunction by decreasing intestinal mucosal permeability and preventing intestinal bacteria from translocating. Probiotics enhance immune responses and reduce the levels of alcohol-induced inflammatory cytokines and reactive oxygen species (ROS) production in the liver and intestine. Probiotics also increase fatty acid β-oxidation and reduce lipogenesis, combating alcohol-induced hepatic steatosis. In this review, we summarize the current knowledge regarding the mechanism of action of probiotics for reducing the effects of alcoholic liver disease.

Modulatory effects of Viola odorata flower and leaf extracts upon oxidative stress-related damage in an experimental model of ethanol-induced hepatotoxicity

Ethanol is the most widely abused drug in the world and its long-term use induces oxidative stress in the liver tissue. The aim of this study was to evaluate protective effect of Viola odorata against ethanol-induced hepatotoxicity in Wistar rat. Animals were divided into 9 groups as follows: control (normal saline), ethanol (10 mg/kg, intraperitoneally), ethanol with 3 doses (125, 250, and 500 mg/kg) of ethyl acetate flower and leaf extracts, and positive control (vitamin E 80 mg/kg). Animals were gavaged 30 min before ethanol injection for 28 days. Then, animals were killed and the livers were separated. Oxidative stress parameters, including reactive oxygen species, lipid peroxidation, and protein carbonyl as well as glutathione content, were evaluated. Also, histopathological examination was performed and assessment of blood alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and total antioxidant capacity were evaluated. Ethanol significantly increased oxidative stress markers in liver. Interestingly, administration of both extracts significantly decreased oxidative stress markers in liver tissue and biochemical parameters in the plasma. In addition, abnormal pathological features were improved after treatment with flower and leaf extracts. These results suggested that V. odorata can be considered a candidate for improving conditions due to ethanol-induced tissue oxidative damage because of its antioxidant activity.

Investigation of the phytochemical composition and antioxidant properties of chinar (Platanus orientalis L.) leaf infusion against ethanol-induced oxidative stress in rats

Chinar (Platanus orientalis L.) is used in folk medicine against tooth and knee pain, wounds, inflammation, and stomach discomfort; however, the effects of P. orientalis leaf (PO-leaf) infusion on the liver and kidney are unknown. The aim of this study was to investigate the phytochemical composition and antioxidant properties of an infusion obtained from dried P. orientalis leaves against ethanol-induced oxidative stress (OS) in rats. After a toxicity test, thirty male Wistar rats were divided into five groups: Control, Ethanol 20%, Ethanol 20% + Silymarin (10 mg/kg), Ethanol 20% + PO-20 mg/mL infusion, and Ethanol 20% + PO-60 mg/mL infusion. The PO-leaf infusion doses were given ad libitum during 28 days to test the biochemical and antioxidant enzyme levels. According to the results, the PO-leaf contained rich compounds such as benzaldehyde, palmitic acid, 2,4-ditert-butylphenol, stearic acid, octadecanoic acid, linoleic acid, linolenic acid, kaempferol, and kaempferol derivatives. In the Ethanol group, AST, ALT, LDH, GGT, UA, and urea in the serum and GST and malondialdehyde (MDA) in the liver and erythrocyte tissues showed a significant increase compared to the Control group. AST, LDH, GGT, UA, and LDL-C levels in the serum and MDA (all tissues) significantly decreased in the Ethanol + PO-60 mg/mL group compared to the Ethanol group. SOD, GPx, and CAT activities in the kidney tissue of the Ethanol group showed a significant decrease compared to the Control group, whereas the GPx activity in kidney tissue in all of the treatment groups increased significantly compared to the Ethanol group. These findings suggest that the administration of the determined PO-leaf infusion doses might have a protective role against ethanol-induced liver and kidney damage in rats.

Suppressed hepatocyte proliferation via a ROS-HNE-P21 pathway is associated with nicotine- and cotinine-enhanced alcoholic fatty liver in mice

CYP2A5 is a major enzyme responsible for nicotine and cotinine metabolism in mice. Nicotine and cotinine enhance alcoholic fatty liver in wild type (WT) mice but not in CYP2A5 knockout (KO) mice, and reactive oxygen species (ROS) generated during the CYP2A5-mediated metabolism contributes to the enhancing effect. In combination with ethanol, nicotine and cotinine increased lipid peroxidation end product 4-hydroxynonenal (HNE) in WT mice but not in KO mice. In ethanol-fed KO mice, only 5 and 10 genes were regulated by nicotine and cotinine, respectively. However, in ethanol-fed WT mice, 59 and 104 genes were regulated by nicotine and cotinine, respectively, and 7 genes were up-regulated by both nicotine and cotinine. Plin 2 and Cdkn1a are among the 7 genes. Plin2 encodes adipose differentiation-related protein (ADRP), a lipid droplet-associated protein, which was confirmed to be increased by nicotine and cotinine in WT mice but not in KO mice. Cdkn1a encodes P21 and elevated P21 in nuclei was also confirmed. HNE can increase P21 and P21 inhibit cell proliferation. Consistently, hepatocyte proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67 were decreased in WT mice but not in KO mice by nicotine/ethanol and cotinine/ethanol, respectively. These results suggest that inhibition of liver proliferation via a ROS-HNE-P21 pathway is involved in nicotine- and cotinine-enhanced alcoholic fatty liver.

Protective effect of inducible aldo-keto reductases on 4-hydroxynonenal- induced hepatotoxicity

4-Hydroxynonenal (HNE), an end-product of lipid peroxidation generated in response to oxidative stress, has been implicated in the pathophysiology of chronic liver diseases. HNE is very reactive that forms Michael adducts with nucleophilic sites in DNA, lipids and proteins. At high concentrations, HNE causes rapid cell death associated with depletion of sulfhydryl groups and inhibition of key metabolic enzymes. At low concentrations, HNE stimulates expression of genes that are part of an adaptive response. In this study, we show that sub-lethal concentrations of HNE induce mRNA expression levels of heme oxygenase-1 (HO-1) (2.5-fold), NADPH:quinone oxidoreductase (NQO1) (4.5-fold), AKR1C3 (2-fold) and AKR7A2 (3-fold) enzymes. Protein expression levels of AKR1C and AKR7A2 are induced by 2- and 1.5-fold following exposure to HNE. The role of AKR1C3 and AKR7A2 in protecting HepG2 cells against HNE toxicity was investigated through using RNAi. Results show that AKR7A2, but not AKR1C3 contributes to the protection against HNE toxicity in HepG2 cells. Moreover, transcriptional factor nuclear factor erythroid 2 p45-related factor 2 (Nrf2) is activated by HNE through translocation to the nucleus. Overexpressing AKR7A2 could rescue the effect of knocking down Nrf2 on HNE-induced cytotoxicity. Furthermore, a natural compound 7-hydroxycoumain, an AKR7A2 inducer, shows hepatoprotection against HNE via AKR7A2 induction. Hence, the inducible AKR7A2 has provided a new therapeutic target to treat chronic liver disease.

Role of CYP2E1 in Mitochondrial Dysfunction and Hepatic Injury by Alcohol and Non-Alcoholic Substances

Alcoholic fatty liver disease (AFLD) and non-alcoholic fatty liver disease (NAFLD) are two pathological conditions that are spreading worldwide. Both conditions are remarkably similar with regard to the pathophysiological mechanism and progression despite different causes. Oxidative stressinduced mitochondrial dysfunction through post-translational protein modifications and/or mitochondrial DNA damage has been a major risk factor in both AFLD and NAFLD development and progression. Cytochrome P450-2E1 (CYP2E1), a known important inducer of oxidative radicals in the cells, has been reported to remarkably increase in both AFLD and NAFLD. Interestingly, CYP2E1 isoforms expressed in both endoplasmic reticulum (ER) and mitochondria, likely lead to the deleterious consequences in response to alcohol or in conditions of NAFLD after exposure to high fat diet (HFD) and in obesity and diabetes. Whether CYP2E1 in both ER and mitochondria work simultaneously or sequentially in various conditions and whether mitochondrial CYP2E1 may exert more pronounced effects on mitochondrial dysfunction in AFLD and NAFLD are unclear. The aims of this review are to briefly describe the role of CYP2E1 and resultant oxidative stress in promoting mitochondrial dysfunction and the development or progression of AFLD and NAFLD, to shed a light on the function of the mitochondrial CYP2E1 as compared with the ER-associated CYP2E1. We finally discuss translational research opportunities related to this field.

Role and mechanisms of autophagy in alcohol-induced liver injury

Alcoholic liver disease (ALD) is one of the major causes of chronic liver disease worldwide. Currently, no successful treatments are available for ALD. The pathogenesis of ALD is characterized as simple steatosis, fibrosis, cirrhosis, alcoholic hepatitis (AH), and eventually hepatocellular carcinoma (HCC). Autophagy is a highly conserved intracellular catabolic process, which aims at recycling cellular components and removing damaged organelles in response to starvation and stresses. Therefore, autophagy is considered as an important cellular adaptive and survival mechanism under various pathophysiological conditions. Recent studies from our lab and others suggest that chronic alcohol consumption may impair autophagy and contribute to the pathogenesis of ALD. In this chapter, we summarize recent progress on the role and mechanisms of autophagy in the development of ALD. Understanding the roles of autophagy in ALD may offer novel therapeutic avenues against ALD by targeting these pathways.

Associations of Oxidative Stress and Postoperative Outcome in Liver Surgery with an Outlook to Future Potential Therapeutic Options

Several types of surgical procedures have shown to elicit an inflammatory stress response, leading to substantial cytokine production and formation of oxygen-based or nitrogen-based free radicals. Chronic liver diseases including cancers are almost always characterized by increased oxidative stress, in which hepatic surgery is likely to potentiate at least in the short term and hereby furthermore impair the hepatic redox state. During liver resection, intermittent inflow occlusion is commonly applied to prevent excessive blood loss but resulting ischemia and reperfusion of the liver have been linked to increased oxidative stress, leading to impairment of cell functions and subsequent cell death. In the field of liver transplantation, ischemia/reperfusion injury has extensively been investigated in the last decades and has recently been in the scientific focus again due to increased use of marginal donor organs and new machine perfusion concepts. Therefore, given the intriguing role of oxidative stress in the pathogenesis of numerous diseases and in the perioperative setting, the interest for a therapeutic antioxidative agent has been present for several years. This review is aimed at giving an introduction to oxidative stress in surgical procedures in general and then examines the role of oxidative stress in liver surgery in particular, discussing both transplantation and resection. Results from studies in the animal and human settings are included. Finally, potential therapeutic agents that might be beneficial in reducing the burden of oxidative stress in hepatic diseases and during surgery are presented. While there is compelling evidence from animal models and a limited number of clinical studies showing that oxidative stress plays a major role in both liver resection and transplantation and several recent studies have suggested a potential for antioxidative treatment in chronic liver disease (e.g., steatosis), the search for effective antioxidants in the field of liver surgery is still ongoing.

Pathogenesis of Alcoholic Liver Disease: An Update

Apart from the classic knowledge that ethanol mediates its hepatotoxicity through its metabolism to acetaldehyde, a well-known hepatotoxic molecule, recent research has elucidated several key mechanisms that potentiate ethanol's damage to the liver parenchyma, such as generation of free radicals, activation of Kupffer cells, and alterations to the human bacterial and fungal microbiome. Genetic studies have suggested the role of PNPLA3 and TM6SF2 gene mutations in the progression of alcoholic liver disease.

Alcoholic liver disease and intestinal microecology

Alcoholic liver disease (ALD) is damage to the liver that occurs after excessive alcohol use over a long period of time, which is mainly characterized by hepatocyte steatosis and fat storage, and the disease spectrum includes steatosis, steatohepatitis, alcoholic fibrosis, and cirrhosis. Steatosis and early steatohepatitis are reversible after cessation of alcohol use. Although the pathogenesis of ALD is not yet fully understood, many studies have shown that the intestinal microecological dysbiosis is closely related to the occurrence and development of ALD. Chronic alcohol use may cause intestinal microecological dysbiosis by leading to increased intestinal mucosal permeability, intestinal flora imbalance, and bacterial translocation, which can then activate immune response, induce an inflammatory response in the liver, and thus lead to liver damage. Based on this situation, we can adjust the intestinal flora imbalance to achieve the goal of treating ALD by using various methods such as supplementing probiotics or prebiotics, properly using antibiotics, and performing fecal microbiota transplantation. In addition, targeted therapy for intestinal bacterial imbalance has also become a hotspot in current research.