Chronic Ethanol-induced Liver Research Articles

Differential contribution of complement receptor C5aR in myeloid and non-myeloid cells in chronic ethanol-induced liver injury in mice.

Complement is implicated in the development of alcoholic liver disease. C3 and C5 contribute to ethanol-induced liver injury; however, the role of C5a receptor (C5aR) on myeloid and non-myeloid cells to progression of injury is not known. C57BL/6 (WT), global C5aR-/-, myeloid-specific C5aR-/-, and non-myeloid-specific C5aR-/- mice were fed a Lieber-DeCarli diet (32%kcal EtOH) for 25 days. Cultured hepatocytes were challenged with ethanol, TNFα, and C5a. Chronic ethanol feeding increased expression of pro-inflammatory mediators in livers of WT mice; this response was completely blunted in C5aR-/- mice. However, C5aR-/- mice were not protected from other measures of hepatocellular damage, including ethanol-induced increases in hepatic triglycerides, plasma alanine aminotransferase and hepatocyte apoptosis. CYP2E1 and 4-hydroxynonenal protein adducts were induced in WT and C5aR-/- mice. Myeloid-specific C5aR-/- mice were protected from ethanol-induced increases in hepatic TNFα, whereas non-myeloid-specific C5aR-/- displayed increased hepatocyte apoptosis and inflammation after chronic ethanol feeding. In cultured hepatocytes, cytotoxicity induced by challenge with ethanol and TNFα was completely eliminated by treatment with C5a in cells from WT, but not C5aR-/- mice. Further, treatment with C5a enhanced activation of pro-survival signal AKT in hepatocytes challenged with ethanol and TNFα. Taken together, these data reveal a differential role for C5aR during ethanol-induced liver inflammation and injury, with C5aR on myeloid cells contributing to ethanol-induced inflammatory cytokine expression, while non-myeloid C5aR protects hepatocytes from death after chronic ethanol feeding.

Gynura procumbens Reverses Acute and Chronic Ethanol-Induced Liver Steatosis through MAPK/SREBP-1c-Dependent and -Independent Pathways.

The present study aimed to evaluate the hepatoprotective effect and mechanism of action of Gynura procumbens on acute and chronic ethanol-induced liver injuries. Ethanol extract from G. procumbens stems (EEGS) attenuated acute ethanol-induced serum alanine aminotransferase levels and hepatic lipid accumulation. Therefore, EEGS was successively extracted by petroleum, ethyl acetate, and n-butyl alcohol. The results showed that the n-butyl alcohol extract was the active fraction of EEGS, and hence it was further fractionated on a polyamide glass column. The 60% ethanol-eluted fraction that contained 13.6% chlorogenic acid was the most active fraction, and its effect was further evaluated using a chronic model. Both the n-butyl alcohol extract and the 60% ethanol-eluted fraction inhibited chronic ethanol-induced hepatic lipid accumulation by modulating lipid metabolism-related regulators through MAPK/SREBP-1c-dependent and -independent signaling pathways and ameliorated liver steatosis. Our findings suggest that EEGS and one of its active ingredients, chlorogenic acid, may be developed as potential effective agents for ethanol-induced liver injury.

Hepatoprotective effect of a polysaccharide from Crassostrea gigas on acute and chronic models of liver injury

A water-soluble polysaccharide was isolated from Crassostrea gigas (CGPS-1) by hot-water extraction, isoelectric precipitation, hydrolysis and ultrafiltration without using ethanol. Based on the calibration with Dextran, CGPS-1 had a molecular weight of approximately 6.5×106Da. CGPS-1 was analyzed using high-performance liquid chromatography, Fourier-transform infrared spectroscopy and 1H and 13C nuclear magnetic resonance spectroscopy. Based on the data, CGPS-1 was found to be a uniform glucose polymer. The protective effect of CGPS-1 on acute carbon tetrachloride- and chronic ethanol-induced liver injury was investigated in mice. Treatment with CGPS-1 decreased serum aspartate aminotransferase (AST), serum alanine aminotransferase (ALT), and malondialdehyde (MDA) levels; increased superoxide dismutase (SOD) activity; and improved hepatic injury in both the acute and chronic models of liver injury in mice. These results suggest that CGPS-1 possesses potent hepatoprotective activity.

Curcumin attenuates chronic ethanol-induced liver injury by inhibition of oxidative stress via mitogen-activated protein kinase/nuclear factor E2-related factor 2 pathway in mice.

Objective:This study aimed to investigate the protective effect of curcumin on chronic ethanol-induced liver injury in mice and to explore its underlying mechanisms.Materials and Methods:Ethanol-exposed Balb/c mice were simultaneously treated with curcumin for 6 weeks. Liver injury was evaluated by biochemical and histopathological examination. Lipid peroxidation and anti-oxidant activities were measured by spectrophotometric method. Anti-oxidative genes expression such as NAD(P)H quinone oxidoreductase 1 (NQO1), heme oxygenase-1 (HO-1), and superoxide dismutase (SOD) were determined by real-time polymerase chain reaction. The nuclear factor E2-related factor 2 (Nrf2) and the phosphorylation states of specific proteins central to intracellular signaling cascades were measured by western blotting.Results:Curcumin treatment protected liver from chronic ethanol-induced injury through reducing serum alanine aminotransferase and aspartate aminotransferase activities, improving liver histological architecture, and reversing lipid disorders indicated by decrease of triglyceride, total cholesterol and low-density lipoprotein-cholesterol levels and increase of High-density lipoprotein-cholesterol levels. Meanwhile, curcumin administration attenuated oxidative stress via up-regulating SOD and glutathione peroxidase activities, leading to a reduction of lipid hydroperoxide production. In addition, curcumin increased Nrf2 activation and anti-oxidative genes expressions such as NQO1, HO-1, and SOD through inducing extracellular signal-regulated kinase (ERK) and p38 phosphorylation.Conclusion:Our data suggested that curcumin protected the liver from chronic-ethanol induced injury through attenuating oxidative stress, at least partially, through ERK/p38/Nrf2-mediated anti-oxidant signaling pathways.

Protective effects of Penthorum chinense Pursh against chronic ethanol-induced liver injury in mice

Ethnopharmacological relevancePenthorum chinense Pursh (Penthoraceae) has been used as a Miao ethnomedicine for the treatment of jaundice, cholecystitis, edema, infectious hepatitis and anti-drunk hangover in China. The aim of present study is to investigate the possible protective effects of Penthorum chinense against chronic ethanol-induced liver injury. Material and methodsMice were fed a Lieber-DeCarli liquid diet containing alcohol or isocaloric maltose dextrin as control diet with or without aqueous extract of Penthorum chinense (PCP, 5.15 and 10.30g/kg/BW) for 4 weeks. Silymarin (86mg/kg) was used as positive control to compare the efficacy of PCP against chronic ethanol-induced hepatotoxicity. ResultsTreatment with PCP (10.30g/kg) significantly reduced the increases in serum ALT and AST levels, hepatic lipid accumulation and inflammatory cytokines (i.e. TNF-α, IL-6), which were induced by chronic ethanol exposure. PCP was also found to attenuate reactive oxygen species (ROS) generation and malondialdehyde (MDA) level, restore the glutathione (GSH) depletion, and increase the superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities. In addition, PCP supplementation (10.30g/kg) inhibited the induction of hepatic cytochrome P450 2E1 (CYP2E1), a major contributor to ethanol-mediated oxidative stress, and up-regulated the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream anti-oxidant protein heme oxygenase-1 (HO-1) in ethanol-treated mice. ConclusionsThese results indicate that the co-treatment with aqueous extract of Penthorum chinense (10.30g/kg) protects against chronic ethanol-induced liver injury, possibly through suppressing CYP2E1-mediated oxidative stress and enhancing the oxidant defense systems via the activation of Nrf2/HO-1 pathway.

Inhibition of cytochrome P4502E1 by chlormethiazole attenuated acute ethanol-induced fatty liver

Cytochrome P4502E1 (CYP2E1) has been demonstrated to play crucial roles in chronic ethanol-induced fatty liver, while its role in acute ethanol-induced fatty liver remains unclear. The current study was designed to evaluate the effects of chlormethiazole (CMZ), a specific inhibitor of CYP2E1, on acute ethanol-induced fatty liver, and to explore the mechanisms. Mice were pretreated with single dose of CMZ (50mg/kg body weight) by intraperitoneal injection or equal volume of saline, and then exposed to three doses of ethanol (5g/kg body weight, 25%, w/v) by gavage with 12h intervals. The mice were sacrificed at 4h after the last ethanol dosing. It was found that CMZ significantly attenuated acute ethanol-induced increase of the hepatic and serum triglyceride levels, and reduced fat droplets accumulation in mice liver. Acute ethanol-induced increase of the hepatic malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE) levels (two biomarkers for oxidative stress) and decrease of glutathione (GSH) level was significantly suppressed by CMZ. CMZ also suppressed ethanol-induced decline of serum adiponectin level, but did not significantly affect the serum tumor necrosis factor-α (TNF-α) and ethanol levels. Furthermore, a significant decline of p62 protein level was observed in CMZ/ethanol group mice liver compared with that of the ethanol group mice. However, acute ethanol-induced increase of peroxisome proliferator-activated receptor α (PPAR-α) protein level was suppressed by CMZ, while the protein levels of sterol regulatory element-binding protein-1c (SREBP-1) and diacylglycerol acyltransferase 2 (DGAT2) were not significantly affected by ethanol or CMZ. Collectively, the results of the current study demonstrated that CMZ could effectively attenuate acute ethanol-induced fatty liver possibly by suppressing oxidative stress and adiponectin decline, and activating autophagy, which suggest that CYP2E1 might also play important roles in acute ethanol-induced fatty liver.

Impairment of autophagosome-lysosome fusion contributes to chronic ethanol-induced liver injury

The pathogenic mechanism underlying alcoholic fatty liver (AFL) is not clear. Autophagy is a self-digestion process that is critical for the maintenance of cellular homeostasis and regulation of lipid metabolism. We investigated the role of autophagy and autophagic flux in hepatic injury induced by chronic ethanol feeding in mice. C57BL/6 mice were fed a Lieber-DeCarli ethanol diet (ED) to induce AFL or an isocaloric control diet for 6 weeks. Chloroquine (CQ, 10 mg/kg, intra-peritoneally [i.p.]) or rapamycin (Rapa, 5 mg/kg, i.p.) were administered during the last 2 weeks of the experimental period. Chronic ethanol feeding induced AFL with focal necrosis associated with increased levels of hepatic triglyceride. This phenomenon was aggravated by CQ, an inhibitor of autophagy, and attenuated by Rapa, an inducer of autophagy. Expression of microtubule-associated protein 1 light chain 3 (LC3)-II and sequestosome1/p62 significantly increased in the ED group. Moreover, accumulation of autophagosomes was observed by transmission electron microscopy in chronic ethanol-treated mice. Chronic ethanol consumption decreased protein expression of LC3 lipidation-related proteins Atg3 and Atg7, and the lysosomal proteins lysosome-associated membrane protein-2 and Rab7, and increased the protein expression of calpain 1 and phosphorylated mammalian target of rapamycin. Taken together, these findings suggest that chronic ethanol consumption leads to impairment of autophagic flux, which contributes to ethanol-induced liver injury.

Protective role of HO-1 and carbon monoxide in ethanol-induced hepatocyte cell death and liver injury in mice

Alcoholic liver disease is associated with inflammation and cell death. Heme oxygenase-1 (HO-1) is a stress-inducible enzyme with anti-apoptotic and anti-inflammatory properties. Here we tested the hypothesis that induction of HO-1 or treatment with a carbon monoxide releasing molecule (CORM) during chronic ethanol exposure protects and/or reverses ethanol-induced liver injury. Female C57BL/6J mice were allowed free access to a complete liquid diet containing ethanol or to pair-fed control diets for 25days. Mice were treated with cobalt protoporphyrin (CoPP) to induce HO-1 expression during ethanol feeding or once liver injury had been established. Mice were also treated with CORM-A1, a CO-releasing molecule (CORM), after ethanol-induced liver injury was established. The impact of HO-1 induction on ethanol-induced cell death was investigated in primary cultures of hepatocytes. Induction of HO-1 during or after ethanol feeding, as well as treatment with CORM-A1, ameliorated ethanol-induced increases in AST and expression of mRNAs for inflammatory cytokines. Treatment with CoPP or CORM-A1 also reduced hepatocyte cell death, indicated by decreased accumulation of CK18 cleavage products and reduced RIP3 expression in hepatocytes. Exposure of primary hepatocyte cultures to ethanol increased their sensitivity to TNFα-induced cell death; this response was attenuated by necrostatin-1, an inhibitor of necroptosis, but not by caspase inhibitors. Induction of HO-1 with CoPP or CORM-3 treatment normalized the sensitivity of hepatocytes to TNFα-induced cell death after ethanol exposure. Therapeutic strategies to increase HO-1 and/or modulate CO availability ameliorated chronic ethanol-induced liver injury in mice, at least in part by decreasing hepatocellular death.

헛개열매추출액발효물이 흰쥐의 에탄올 경구투여에 의한 간손상 지표와 체중 감량 완화에 미치는 영향

This study was performed to investigate the effect of fermented Hovenia dulcis Thunb fruit water extract on biomarkers for acute (a) ethanol-induced hangover and chronic (c) ethanol-induced liver injury in rats. For acute ethanol-induced hangover, the rats were administered distilled water (D.W., 10 mL/kg body wt.), Hovenia dulcis Thunb fruit water extract (HWE, 400 mg/10 mL/kg body wt.) and fermented HWE (FHWE, 400 mg/10 mL/kg body wt.), respectively, before 40% ethanol (5 g/kg body wt.) was administered. For chronic ethanol-induced liver injury, the rats were randomly divided into the normal control (cNC), ethanol (cET), cET-HWE and cET-FHWE groups. The cNC and cET groups were administered D.W. (10 mL/kg body wt.) before 40% alcohol (5 g/kg body wt.) was administrered for 21 days. The cET-HWE and cET-FHWE groups were administered HWE (400 mg/10 mL/kg body wt.) and FHWE (400 mg/10 mL/kg body wt.), respectively before 40% ethanol (5 g/kg body wt.) administration for 21 days. For acute ethanol-induced hangover, the serum alcohol and acetaldehyde concentrations were more significantly reduced in the aHWE and aFHWE groups than in the aET group. Moreover, the effect of FHWE was greater than that of HWE. For chronic ethanol-induced liver injury, the serum ethanol, acetaldehyde, γ-glutamyl transpeptidase (γ-GTP) levels and the hepatic lipids concentration more significantly dropped in the cET-HWE and cET-FHWE groups than in the cET group. The FHWE administration showed faster recovery of the serum glucose concentration than in the cET and cET-HWE groups. The body weight reduction tended to normalize in the cET-HWE and cET-FHWE groups, which is ideal for chronic ethanol administration. These results suggest that FHWE has a protective effect against ethanol-induced liver damage, as evidenced by its ability to lower the serum ethanol and acetaldehyde concentrations after alcohol administration, and by its ability to decrease the level of γ-GTP and hepatic lipids. FHWE also elevated serum glucose concentration. Therefore, FHWE is effective in reducing ethanol-induced hangover and can play a beneficial role in the treatment of ethanol-induced liver damage as well as body weight reduction.

Proteomic analysis of 4-hydroxynonenal (4-HNE) modified proteins in liver mitochondria from chronic ethanol-fed rats

Chronic ethanol-mediated oxidative stress and lipid peroxidation increases the levels of various reactive lipid species including 4-hydroxynonenal (4-HNE), which can subsequently modify proteins in the liver. It has been proposed that 4-HNE modification adversely affects the structure and/or function of mitochondrial proteins, thereby impairing mitochondrial metabolism. To determine whether chronic ethanol consumption increases levels of 4-HNE modified proteins in mitochondria, male rats were fed control and ethanol-containing diets for 5 weeks and mitochondrial samples were analyzed using complementary proteomic methods. Five protein bands (approx. 35, 45, 50, 70, and 90kDa) showed strong immunoreactivity for 4-HNE modified proteins in liver mitochondria from control and ethanol-fed rats when proteins were separated by standard 1D SDS-PAGE. Using high-resolution proteomic methods (2D IEF/SDS-PAGE and BN-PAGE) we identified several mitochondrial proteins immunoreactive for 4-HNE, which included mitofilin, dimethylglycine dehydrogenase, choline dehydrogenase, electron transfer flavoprotein α, cytochrome c1, enoyl CoA hydratase, and cytochrome c. The electron transfer flavoprotein α consistently showed increased 4-HNE immunoreactivity in mitochondria from ethanol-fed rats as compared to mitochondria from the control group. Increased 4-HNE reactivity was also detected for dimethylglycine dehydrogenase, enoyl CoA hydratase, and cytochrome c in ethanol samples when mitochondria were analyzed by BN-PAGE. In summary, this work identifies new targets of 4-HNE modification in mitochondria and provides useful information needed to better understand the molecular mechanisms underpinning chronic ethanol-induced mitochondrial dysfunction and liver injury.

Natural killer T cells play an important role in chronic plus binge ethanol-induced liver injury

Natural killer T cells play an important role in chronic plus binge ethanol-induced liver injury

Macrophage migration inhibitory factor contributes to ethanol-induced liver injury by mediating cell injury, steatohepatitis, and steatosis

Macrophage migration inhibitory factor (MIF), a multipotent protein that exhibits both cytokine and chemotactic properties, is expressed by many cell types, including hepatocytes and nonparenchymal cells. We hypothesized that MIF is a key contributor to liver injury after ethanol exposure. Female C57BL/6 or MIF-/- mice were fed an ethanol-containing liquid diet or pair-fed control diet for 4 (11% total kcal;early response) or 25 (32% kcal; chronic response) days. Expression of MIF messenger RNA (mRNA) was induced at both 4 days and 25 days of ethanol feeding. After chronic ethanol, hepatic triglycerides and plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were increased in wildtype, but not MIF-/-, mice. In order to understand the role of MIF in chronic ethanol-induced liver injury, we investigated the early response of wildtype and MIF-/- to ethanol. Ethanol feeding for 4 days increased apoptosis of hepatic macrophages and activated complement in both wildtype and MIF-/- mice. However, tumor necrosis factor alpha (TNF-α) expression was increased only in wildtype mice. This attenuation of TNF-α expression was associated with fewer F4/80+ macrophages in liver of MIF-/- mice. After 25 days of ethanol feeding, chemokine expression was increased in wildtype mice, but not MIF-/- mice. Again, this protection was associated with decreased F4/80+ cells in MIF-/- mice after ethanol feeding. Chronic ethanol feeding also sensitized wildtype, but not MIF-/-, mice to lipopolysaccharide, increasing chemokine expression and monocyte recruitment into the liver. Taken together, these data indicate that MIF is an important mediator in the regulation of chemokine production and immune cell infiltration in the liver during ethanol feeding and promotes ethanol-induced steatosis and hepatocyte damage.

Antihepatotoxic activity of a quantified Desmodium adscendens decoction and d-pinitol against chemically-induced liver damage in rats

Ethnopharmacological relevanceThe isolation of d-pinitol (or 3-O-methyl-d-chiro-inositol) from an aqueous decoction of Desmodium adscendens (Fabaceae) leaves and twigs is reported. The protective and curative effect of this decoction, in which d-pinitol was quantified, and of pure d-pinitol, against chemically-induced liver damage in rats has been evaluated. Materials and methodsEnzyme levels of aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP), which are among the usual biomarkers for liver damage, were determined in serum samples of experimental animals. The protective effects against d-galactosamine-induced and ethanol-induced liver damage of a decoction of D. adscendens, quantified on its main constituent d-pinitol, was investigated in rats. In addition, the curative effects of pure d-pinitol and D. adscendens against chronic d-galactosamine-induced and acute acetaminophen-induced hepatotoxicity in rats was studied. Silymarin was used as positive control. ResultsIn a first experiment evaluating the protective effect against acute d-galactosamine-induced liver damage in rats, a significant decrease of AST and ALT was observed for the D. adscendens decoction at a dose equivalent to 5mg/kg/day and 20mg/kg/day d-pinitol, as well as 20mg/kg/day pure d-pinitol. With respect to chronic ethanol-induced liver damage in rats, the protective effects of D. adscendens at doses equivalent to 2mg/kg/day and 10mg/kg/day d-pinitol, were not observed for serum AST and ALT levels. However, with respect to reduced mortality of animals, statistical analysis showed a trend towards significance for the Desmodium group receiving a dose equivalent to 10mg/kg/day d-pinitol, versus the untreated hepatotoxic animals. Additional experiments in rat models of acute acetaminophen-induced and chronic d-galactosamine-induced liver damage indicated that D. adscendens decoction and pure d-pinitol had no curative effect when given in a dose equivalent to 10mg/kg/day d-pinitol, or up to 20mg/kg/day as a pure compound daily, respectively. ConclusionsThe aqueous decoction of D. adscendens showed a protective effect in rats against liver damage induced by d-galactosamine and ethanol, and this effect is at least in part due to the presence of d-pinitol. However, no curative effect of D. adscendens decoction or d-pinitol on liver damage induced by the tested chemicals could be demonstrated.

CYP2E1 potentiates toxicity in obesity and after chronic ethanol treatment

CYP2E1 activates several hepatotoxins and contributes to alcoholic liver damage. In this report, we review our studies on whether induction of CYP2E1 can potentiate liver injury in obesity. Acetone- or pyrazole-induced severe liver injury in obese mice as compared to obese controls and lean mice. Severe liver injury was associated with elevated oxidative and nitrosative stress and could be blunted by inhibitors of CYP2E1 and inducible nitric oxide synthase (iNOS). S-Adenosyl-L-methionine (SAM) lowered the elevated oxidative and nitrosative stress, steatosis, liver injury and mitochondrial dysfunction in the pyrazole-treated obese mice. The protection by SAM may have therapeutic applications against metabolic complications caused by obesity. The role of CYP2E1 in chronic ethanol-induced liver injury was studied using wild-type (WT) mice, CYP2E1 knockout (KO) mice and humanized CYP2E1 knockin (KI) mice. Ethanol produced fatty liver and oxidant stress in WT mice; these effects were blunted in the CYP2E1 KO mice but restored in the CYP2E1 KI mice. Significant liver injury was produced in the ethanol-fed KI mice in association with elevated oxidant stress and levels of human CYP2E1. Collectively, these studies show that CYP2E1 contributes to ethanol-induced and obesity-induced oxidant stress and liver injury.

Cytochrome P4502E1, oxidative stress, JNK, and autophagy in acute alcohol-induced fatty liver

Binge alcohol drinking induces hepatic steatosis. Recent studies showed that chronic ethanol-induced fatty liver was, at least in part, CYP2E1 dependent. The mechanism of acute alcohol-induced steatosis and whether CYP2E1 plays any role are still unclear. Increasing oxidative stress by alcohol can activate the JNK MAP kinase signaling pathway, suggesting that JNK might be a target for prevention of alcohol-induced steatosis. We used CYP2E1 knockout (KO) mice, a JNK inhibitor, and JNK1 or JNK2 knockout mice to test the role of CYP2E1, JNK, and the individual role of JNK1 and JNK2 in acute alcohol-induced steatosis. In wild-type (WT) mice, acute alcohol activates CYP2E1 and increases oxidative stress, which reciprocally increases activation of the JNK signaling pathway. Acute alcohol-induced fatty liver and oxidative stress were blunted in CYP2E1 KO mice and by the JNK inhibitor in WT mice. The antioxidant N-acetylcysteine decreased the acute alcohol-induced oxidative stress, the activation of JNK, and the steatosis but not the activation of CYP2E1. Acute alcohol decreased autophagy and increased expression of SREBP, effects blocked by the JNK inhibitor. Acute alcohol-induced fatty liver was the same in JNK1 and JNK2 KO mice as in WT mice; thus either JNK1 or JNK2 per se is sufficient for induction of steatosis by acute alcohol. The results show that acute alcohol elevation of CYP2E1, oxidative stress, and activation of JNK interact to lower autophagy and increase lipogenic SREBP resulting in fatty liver.

Argininosuccinate synthase conditions the response to acute and chronic ethanol-induced liver injury in mice

Argininosuccinate synthase (ASS) is the rate-limiting enzyme in both the urea and the L-citrulline/nitric oxide (NO·) cycles regulating protein catabolism, ammonia levels, and NO· generation. Because a proteomics analysis identified ASS and nitric oxide synthase-2 (NOS2) as coinduced in rat hepatocytes by chronic ethanol consumption, which also occurred in alcoholic liver disease (ALD) and in cirrhosis patients, we hypothesized that ASS could play a role in ethanol binge and chronic ethanol-induced liver damage. To investigate the contribution of ASS to the pathophysiology of ALD, wildtype (WT) and Ass(+/-) mice (Ass(-/-) are lethal due to hyperammonemia) were exposed to an ethanol binge or to chronic ethanol drinking. Compared with WT, Ass(+/-) mice given an ethanol binge exhibited decreased steatosis, lower NOS2 induction, and less 3-nitrotyrosine (3-NT) protein residues, indicating that reducing nitrosative stress by way of the L-citrulline/NO· pathway plays a significant role in preventing liver damage. However, chronic ethanol-treated Ass(+/-) mice displayed enhanced liver injury compared with WT mice. This was due to hyperammonemia, lower phosphorylated AMP-activated protein kinase alpha (pAMPKα) to total AMPKα ratio, decreased sirtuin-1 (Sirt-1) and peroxisomal proliferator-activated receptor coactivator-1α (Pgc1α) messenger RNAs (mRNAs), lower fatty acid β-oxidation due to down-regulation of carnitine palmitoyl transferase-II (CPT-II), decreased antioxidant defense, and elevated lipid peroxidation end-products in spite of comparable nitrosative stress but likely reduced NOS3. Partial Ass ablation protects only in acute ethanol-induced liver injury by decreasing nitrosative stress but not in a more chronic scenario where oxidative stress and impaired fatty acid β-oxidation are key events.

Agrimonia eupatoria protects against chronic ethanol-induced liver injury in rats

This study examined the hepatoprotective effects of Agrimonia eupatoria water extract (AE) against chronic ethanol-induced liver injury. Rats were fed a Lieber–DeCarli liquid diet for 8weeks. Animals were treated orally with AE at 10, 30, 100, and 300mg/kg/day. After chronic consumption of ethanol, serum aminotransferase activities and pro-inflammatory cytokines markedly increased, and those increases were attenuated by AE. The cytochrome P450 2E1 activity and lipid peroxidation increased after chronic ethanol consumption, while reduced glutathione concentration decreased. Those changes were attenuated by AE. Chronic ethanol consumption increased the levels of Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 protein expression, inducible nitric oxide synthase and cyclooxygenase-2 protein and mRNA expression, and nuclear translocation of nuclear factor-kappa B, which was attenuated by AE. Our results suggest that AE ameliorates chronic ethanol-induced liver injury, and that protection is likely due to the suppression of oxidative stress and TLR-mediated inflammatory signaling.

Role of CYP2E1 in Ethanol-Induced Oxidant Stress, Fatty Liver and Hepatotoxicity

Background/Aims: Several pathways contribute to mechanisms by which ethanol induces oxidant stress. While some studies support a role for cytochrome P450 2E1 (CYP2E1), others do not. There is a need to develop oral models of significant ethanol-induced liver injury and to evaluate the possible role of CYP2E1 in ethanol actions in such models. Methods: We evaluated chronic ethanol-induced liver injury, steatosis and oxidant stress in wild-type (WT) mice, CYP2E1 knockout (KO) mice and in humanized CYP2E1 knockin (KI) mice, where the human 2E1 was added back to mice deficient in the mouse 2E1. WT mice and CYP2E1 KO and KI mice (both provided by Dr. F. Gonzalez, NCI) were fed a high-fat Lieber-DeCarli liquid diet for 3 weeks; pair-fed controls received dextrose. Results: Ethanol produced fatty liver and oxidant stress in WT mice, but liver injury (transaminases, histopathology) was minimal. Ethanol-induced steatosis and oxidant stress were blunted in the KO mice (no liver injury) but restored in the KI mice. Significant liver injury was produced in the ethanol-fed KI mice with elevated transaminases and necrosis. This liver injury in the KI mice was associated with elevated oxidant stress and elevated levels of the human CYP2E1 compared to levels of the mouse 2E1 in WT mice. Activation of JNK was observed in the ethanol-fed KI mice compared to the other groups. Fatty liver in WT and KI mice was associated with lower levels of lipolytic PPAR-α. No such changes were found in the ethanol-fed KO mice. Conclusions: These results show that CYP2E1 plays a major role in ethanol-induced fatty liver and oxidant stress. Restoring CYP2E1 in the CYP2E1 KO mice restores ethanol-induced fatty liver and oxidant stress.

Peroxisome proliferator‐activated receptor agonist treatment of alcohol‐induced hepatic insulin resistance

Chronic ethanol exposure impairs insulin signaling in the liver. Peroxisome-proliferator activated receptor (PPAR) agonists function as insulin sensitizers and are used to treat type 2 diabetes mellitus. We examined the therapeutic effectiveness of PPAR agonists in reducing alcoholic hepatitis and hepatic insulin resistance in a model of chronic ethanol feeding. Adult male Long Evans rats were pair fed with isocaloric liquid diets containing 0% (control) or 37% ethanol (caloric content; 9.2% v/v) for 8 weeks. After 3 weeks on the diets, the rats were treated with vehicle, or a PPAR-α, PPAR-δ or PPAR-γ agonist twice weekly by i.p. injection. Livers were harvested for histopathological, gene expression (reverse transcription polymerase chain reaction), protein (western and ELISA) and receptor binding studies. Ethanol-fed rats developed steatohepatitis with disordered hepatic chord architecture, increased hepatocellular apoptosis, reduced binding to the insulin, insulin-like growth factor (IGF)-1 and IGF-2 receptors, and decreased expression of glyceraldehyde-3-phosphate dehydrogenase and aspartyl-(asparaginyl)-β-hydroxylase (mediating remodeling), which are regulated by insulin/IGF signaling. PPAR-α, PPAR-δ or PPAR-γ agonist treatments reduced the severity of ethanol-mediated liver injury, including hepatic architectural disarray and steatosis. In addition, PPAR-δ and PPAR-γ agonists reduced insulin/IGF resistance and increased insulin/IGF-responsive gene expression. PPAR agonists may help reduce the severity of chronic ethanol-induced liver injury and insulin/IGF resistance, even in the context of continued high-level ethanol consumption.

Co-Treatment with Shengmai San-Derived Herbal Product Ameliorates Chronic Ethanol-Induced Liver Damage in Rats

Wei Kang Su (WKS) is an antioxidant-enriched herbal product manufactured on the basis of Shengmai San, a well-known traditional Chinese herbal formula. In the present study, we investigated the effects of WKS co-treatment on chronic ethanol toxicity in rats. WKS co-treatment protected against chronic ethanol-induced hepatotoxicity, as evidenced by the suppression of plasma enzyme activities and reactive oxygen metabolite levels, as well as the inhibition of hepatic mitochondrial malondialdehyde production in chronic ethanol-intoxicated rats. The hepatoprotection afforded by WKS co-treatment in chronic ethanol-intoxicated rats was associated with a reversal of altered hepatic mitochondrial antioxidant status and adenosine triphosphate (ATP) generation capacity, as well as heat shock protein 25/70 production. Therefore, WKS may offer the prospect of preventing ethanol-associated liver damage by increasing the resistance of mitochondria to oxidative stress.