Alcoholic Liver Disease Model Research Articles

Rectification of impaired adipose tissue methylation status and lipolytic response contributes to hepatoprotective effect of betaine in a mouse model of alcoholic liver disease.

Overactive lipolysis in adipose tissue contributes to the pathogenesis of alcoholic liver disease (ALD); however, the mechanisms involved have not been elucidated. We previously reported that chronic alcohol consumption produces a hypomethylation state in adipose tissue. In this study we investigated the role of hypomethylation in adipose tissue in alcohol-induced lipolysis and whether its correction contributes to the well-established hepatoprotective effect of betaine in ALD. Male C57BL/6 mice were divided into four groups and started on one of four treatments for 5 weeks: isocaloric pair-fed (PF), alcohol-fed (AF), PF supplemented with betaine (BT/AF) and AF supplemented with betaine (BT/AF). Betaine, 0.5% (w v(-1) ), was added to the liquid diet. Both primary adipocytes and mature 3T3-L1 adipocytes were exposed to demethylation reagents and their lipolytic responses determined. Betaine alleviated alcohol-induced pathological changes in the liver and rectified the impaired methylation status in adipose tissue, concomitant with attenuating lipolysis. In adipocytes, inducing hypomethylation activated lipolysis through a mechanism involving suppression of protein phosphatase 2A (PP2A), due to hypomethylation of its catalytic subunit, leading to increased activation of hormone-sensitive lipase (HSL). In line with in vitro observations, reduced PP2A catalytic subunit methylation and activity, and enhanced HSL activation, were observed in adipose tissue of alcohol-fed mice. Betaine attenuated this alcohol-induced PP2A suppression and HSL activation. In adipose tissue, a hypomethylation state contributes to its alcohol-induced dysfunction and an improvement in its function may contribute to the hepatoprotective effects of betaine in ALD.

Dysregulation of hepatic zinc transporters in a mouse model of alcoholic liver disease.

Zinc deficiency is a consistent phenomenon observed in patients with alcoholic liver disease, but the mechanisms have not been well defined. The objective of this study was to determine if alcohol alters hepatic zinc transporters in association with reduction of hepatic zinc levels and if oxidative stress mediates the alterations of zinc transporters. C57BL/6 mice were pair-fed with the Lieber-DeCarli control or ethanol diets for 2, 4, or 8 wk. Chronic alcohol exposure reduced hepatic zinc levels, but increased plasma and urine zinc levels, at all time points. Hepatic zinc finger proteins, peroxisome proliferator-activated receptor-α (PPAR-α) and hepatocyte nuclear factor 4α (HNF-4α), were downregulated in ethanol-fed mice. Four hepatic zinc transporter proteins showed significant alterations in ethanol-fed mice compared with the controls. ZIP5 and ZIP14 proteins were downregulated, while ZIP7 and ZnT7 proteins were upregulated, by ethanol exposure at all time points. Immunohistochemical staining demonstrated that chronic ethanol exposure upregulated cytochrome P-450 2E1 and caused 4-hydroxynonenal accumulation in the liver. For the in vitro study, murine FL-83B hepatocytes were treated with 5 μM 4-hydroxynonenal or 100 μM hydrogen peroxide for 72 h. The results from in vitro studies demonstrated that 4-hydroxynonenal treatment altered ZIP5 and ZIP7 protein abundance, and hydrogen peroxide treatment changed ZIP7, ZIP14, and ZnT7 protein abundance. These results suggest that chronic ethanol exposure alters hepatic zinc transporters via oxidative stress, which might account for ethanol-induced hepatic zinc deficiency.

Oxidative stress-mediated aldehyde adduction of GRP78 in a mouse model of alcoholic liver disease: functional independence of ATPase activity and chaperone function

Pathogenesis in alcoholic liver disease (ALD) is complicated and multifactorial but clearly involves oxidative stress and inflammation. Currently, conflicting reports exist regarding the role of endoplasmic reticulum (ER) stress in the etiology of ALD. The glucose-regulated protein 78 (GRP78) is the ER homolog of HSP70 and plays a critical role in the cellular response to ER stress by serving as a chaperone assisting protein folding and by regulating the signaling of the unfolded protein response (UPR). Comprising three functional domains, an ATPase, a peptide-binding, and a lid domain, GRP78 folds nascent polypeptides via the substrate-binding domain. Earlier work has indicated that the ATPase function of GRP78 is intrinsically linked and essential to its chaperone activity. Previous work in our laboratory has indicated that GRP78 and the UPR are not induced in a mouse model of ALD but that GRP78 is adducted by the lipid electrophiles 4-hydroxynonenal (4-HNE) and 4-oxononenal (4-ONE) in vivo. As impairment of GRP78 has the potential to contribute to pathogenesis in ALD, we investigated the functional consequences of aldehyde adduction on GRP78 function. Identification of 4-HNE and 4-ONE target residues in purified human GRP78 revealed a marked propensity for Lys and His adduction within the ATPase domain and a relative paucity of adduct formation within the peptide-binding domain. Consistent with these findings, we observed a concomitant dose-dependent decrease in ATP-binding and ATPase activity without any discernible impairment of chaperone function. Collectively, our data indicate that ATPase activity is not essential for GRP78-mediated chaperone activity and is consistent with the hypothesis that ER stress does not play a primary initiating role in the early stages of ALD.

Identification of 5′ AMP-activated Kinase as a Target of Reactive Aldehydes during Chronic Ingestion of High Concentrations of Ethanol

The production of reactive aldehydes including 4-hydroxy-2-nonenal (4-HNE) is a key component of the pathogenesis in a spectrum of chronic inflammatory hepatic diseases including alcoholic liver disease (ALD). One consequence of ALD is increased oxidative stress and altered β-oxidation in hepatocytes. A major regulator of β-oxidation is 5' AMP protein kinase (AMPK). In an in vitro cellular model, we identified AMPK as a direct target of 4-HNE adduction resulting in inhibition of both H2O2 and 5-aminoimidazole-4-carboxyamide ribonucleoside (AICAR)-induced downstream signaling. By employing biotin hydrazide capture, it was confirmed that 4-HNE treatment of cells resulted in carbonylation of AMPKα/β, which was not observed in untreated cells. Using a murine model of alcoholic liver disease, treatment with high concentrations of ethanol resulted in an increase in phosphorylated as well as carbonylated AMPKα. Despite increased AMPK phosphorylation, there was no significant change in phosphorylation of acetyl CoA carboxylase. Mass spectrometry identified Michael addition adducts of 4-HNE on Cys(130), Cys(174), Cys(227), and Cys(304) on recombinant AMPKα and Cys(225) on recombinant AMPKβ. Molecular modeling analysis of identified 4-HNE adducts on AMPKα suggest that inhibition of AMPK occurs by steric hindrance of the active site pocket and by inhibition of hydrogen peroxide induced oxidation. The observed inhibition of AMPK by 4-HNE provides a novel mechanism for altered β-oxidation in ALD, and these data demonstrate for the first time that AMPK is subject to regulation by reactive aldehydes in vivo.

386 Dietary Saturated and Unsaturated Fat Differentially Modulate Gut Microbiome, Intestinal Barrier and Liver Injury in a Mouse Model of Alcoholic Liver Disease

barrier dysfunction and hepatic endoplasmic reticulum (ER) stress and injury, which are recognized etiologic factors in ALD. We examined hepatic and intestinal effects of acrolein and alcohol using in vitro (rat hepatic H4IIEC, and human intestinal epithelial Caco2 cells) and in vivo (C57/Bl6 mice chronic+binge alcohol feeding) models. ACR adducts accumulated in response to alcohol or ACR in mouse livers and intestines, and in cultured cells. This was accompanied by hepatic steatosis, activation of JNK, ER stress (upregulation of ATF3, ATF4, and pro-apoptotic CHOP), mitochondrial disruption and apoptosis as seen by Cellomics. Notably, the cytotoxic effects of ACR and alcohol were attenuated by acrolein/ aldehyde scavengers. Alcohol-induced in vivo intestinal effects (down-regulation of tight junction proteins ZO-1, occludin, and claudin, and barrier dysfunction) were mimicked by ACR in Caco2 cells. Our study demonstrates that acrolein is an important mediator of the hepatic and intestinal effects of alcohol consumption, and suggests a therapeutic potential for acrolein scavengers in ALD.

Effects of Korean Red Ginseng (Panax ginseng), urushiol (Rhus vernicifera Stokes), and probiotics (Lactobacillus rhamnosus R0011 and Lactobacillus acidophilus R0052) on the gut–liver axis of alcoholic liver disease

BackgroundRoles of immune reaction and toll-like receptor-4 (TLR-4) have widely been established in the pathogenesis of alcoholic liver disease (ALD). MethodsWe evaluated the biologic efficacy of Korean Red Ginseng (KRG), urushiol, and probiotics (Lactobacillus rhamnosus R0011 and Lactobacillus acidophilus R0052) in mouse models of ALD. Sixty C57BL/6 mice were equally divided into six feeding groups for 10 weeks: normal diet, alcohol, control, alcohol + KRG, alcohol + urushiol, and alcohol + probiotics. Alcohol was administered via a Lieber–DeCarli liquid diet containing 10% alcohol. TLR-4 expression, proinflammatory cytokines, and histology, as well as the results of liver function tests were evaluated and compared. ResultsNo between-group differences were observed with regard to liver function. TLR-4 levels were significantly lower in the KRG, urushiol, and probiotics groups than in the alcohol group (0.37 ± 0.06 ng/mL, 0.39 ± 0.12 ng/mL, and 0.33 ± 0.07 ng/mL, respectively, vs. 0.88 ± 0.31 ng/mL; p < 0.05). Interleukin-1β levels in liver tissues were decreased among the probiotics and KRG groups. The tumor necrosis factor-α level of liver tissue was decreased in the KRG group. ConclusionThe pathological findings showed that alcohol-induced steatosis was significantly reduced by KRG and urushiol. As these agents improve immunologic capacity, they may be considered in potential anti-ALD treatments.

Zeaxanthin dipalmitate therapeutically improves hepatic functions in an alcoholic fatty liver disease model through modulating MAPK pathway.

In the current study, the therapeutic effects of zeaxanthin dipalmitate (ZD) on a rat alcoholic fatty liver disease (AFLD) model were evaluated. After-treatment with ZD from the 5th week to the 10th week in a 10-week ethanol intragastric administration in rats significantly alleviated the typical AFLD symptoms, including reduction in rat body weight, accumulation of hepatic fat droplets, occurrence of oxidative stress, inflammation, chemoattractive responses and hepatic apoptosis in the liver. The reduction of liver function abnormalities by ZD was partly through lower expression level of cytochrome P450 2E1 (CYP2E1), diminished activity of nuclear factor kappa B (NF-κB) through the restoration of its inhibitor kappa B alpha (IκBα), and the modulation of MAPK pathways including p38 MAPK, JNK and ERK. ZD treatment alone did not pose obvious adverse effect on the healthy rat. In the cellular AFLD model, we also confirmed the inhibition of p38 MAPK and ERK abolished the beneficial effects of ZD. These results provide a scientific rationale for the use of zeaxanthin and its derivatives as new complementary agents for the prevention and treatment of alcoholic liver diseases.

Animals Models of Gastrointestinal and Liver Diseases. Animal models of alcohol-induced liver disease: pathophysiology, translational relevance, and challenges

Over the last four decades, chronic ethanol feeding studies in rodents using either ad libitum feeding or intragastric infusion models have significantly enhanced our understanding of the pathogenesis of alcoholic liver disease (ALD). Recently, we developed a chronic plus binge alcohol feeding model in mice that is similar to the drinking patterns of many alcoholic hepatitis patients: a history of chronic drinking and recent excessive alcohol consumption. Chronic+binge ethanol feeding synergistically induced steatosis, liver injury, and neutrophil infiltration in mice, which may be useful for the study of early alcoholic liver injury and inflammation. Using this chronic+binge model, researchers have begun to identify novel mechanisms that participate in the pathogenesis of alcoholic liver injury, thereby revealing novel therapeutic targets. In this review article, we briefly discuss several mouse models of ALD with a focus on the chronic+binge ethanol feeding model.

Saturated dietary fat prevented unsaturated fat and alcohol‐mediated alterations in gut microbiota resulting in attenuation of intestinal barrier disruption and liver injury in an animal model of alcoholic liver disease (822.9)

Introduction: Gut microbiota play an important role in the pathogenesis of ALD. Dietary fat and alcohol both affect microbiota composition and abundance. The aim of the study was to evaluate the effects of different types of dietary fat on alcohol‐mediated changes in gut microbiota and consequent intestinal and liver injury. Materials and Methods: C57BL/6 mice were fed either saturated (medium chain triglycerides enriched [MCT]) or unsaturated (corn oil enriched) fat diet containing 5% ethanol for 8 weeks. Metagenomic analysis of the gut microbiome was performed by analyzing the fecal DNA by amplification of the V3‐V5 regions of the 16S rRNA gene and large‐scale parallel pyrosequencing on the 454 FLX Titanium platform. Intestinal barrier integrity; liver injury and steatosis were evaluated. Results: Dietary unsaturated fat and ethanol caused a decline in the abundance of both Bacteriodetes and Firmicutes phyla, with a proportional increase in the gram negative Proteobacteria and gram positive Actinobacteria phyla. The observed microbiota changes were associated with the alterations in the intestinal tight junctions; liver inflammation and injury. Notably, unsaturated fat and ethanol induced pathogenic alterations in the gut microbiome, intestinal barrier integrity, and the livers were prevented in animals receiving saturated fat diet and ethanol. Conclusion: ALD relevant pathogenic alterations in the gut microbiome induced by chronic ethanol are markedly influenced by dietary lipids. Dietary lipids can potentially provide therapeutic options in the management of ALD.Grant Funding Source: Supported by NIH, DOD and Veterans Administration

Protective effects of oyster extract against hepatic tissue injury in alcoholic liver diseases

Oyster extract is an effective bioactivity component. It has abundant nutritional value and antiviral, antitumor and immune defense functions. The role of oyster extract in treating liver injury has been paid more attention. We use Wistar rats to make alcoholic liver disease model through injecting alcohol into rats’ stomachs. These rats were randomly divided into five groups: model group, control group, low-dose, middle-dose and high-dose experimental group with a dose of 0.12 g kg−1, 0.40 g kg−1, and 1.20 g kg−1 alcoholic. After nine weeks, serum biomarkers (ALT, AST, TG and TCHO), malondialdehyde (MDA), glutathione (GSH), C3a, C5a, IL-17, TNF-α, anti-MAA-HAS IgG, CD3+, CD4+, CD8+, NK cell activation and zinc content were assessed. The results showed that the serum biomarkers(ALT, AST, TG and TCHO), MDA content, anti-MAA-HSA IgG, serum C3a, C5a IL-17 and TNF-α levels of oyster extract treatment groups were significantly decreased in comparison with model group. On the contrary, GSH showed adverse trend. Serum CD3+, CD4+ and NK cell activation were significantly increased in middle-dose group and high-dose group compared with model group, and there was decrease of CD8+ activity in high-dose group. Plasma Zn level was decreased in model group compared with that in control group. Meanwhile, Mean plasma Zn levels increased dramatically following the dose increase of a given oyster extract.

Hepatoprotective potential ofAloe verapolysaccharides against chronic alcohol-induced hepatotoxicity in mice

Aloe vera polysaccharides are reported to exhibit multiple biological effects, including anti-oxidation, anti-inflammation and immune enhancement. However, their influence on alcoholic liver disease (ALD) remains unclear. This study was designed to determine the protective effect of extracted A. vera polysaccharides (AVGP) against ALD in a chronic alcohol-feeding mouse model and investigate the possible underlying mechanisms. Supplementation of AVGP significantly attenuated the levels of serum aminotransferases, lipids and hepatic TG and ameliorated histopathological alterations in the model of ALD. Interestingly, AVGP markedly up-regulated hepatic expression of lipolytic genes (AMPK-α2 and PPAR-α) but had no effect on lipogenic gene expression. AVGP diminished alcohol-dependent oxidative stress partly through a decrease in MDA and increase in GSH and SOD. Alcohol-induced inflammation was also mitigated by AVGP treatment via significant reduction in LPS and TNF-α, down-regulation of TLR-4 and MyD88 and up-regulation of IκB-α. This study clearly showed that AVGP exerts a potent protective effect against chronic alcohol-induced liver injury. Its hepatoprotective effect appears to be associated with its antioxidant capacity and its ability to accelerate lipolysis and inhibit inflammatory response. The results indicate that AVGP could be considered as a potent food supplement in the prevention of ALD.

Modulation of Inflammation by Alcohol Exposure

Modulation of Inflammation by Alcohol Exposure

Mitochondrial dysfunction and tissue injury by alcohol, high fat, nonalcoholic substances and pathological conditions through post-translational protein modifications

Mitochondria are critically important in providing cellular energy ATP as well as their involvement in anti-oxidant defense, fat oxidation, intermediary metabolism and cell death processes. It is well-established that mitochondrial functions are suppressed when living cells or organisms are exposed to potentially toxic agents including alcohol, high fat diets, smoking and certain drugs or in many pathophysiological states through increased levels of oxidative/nitrative stress. Under elevated nitroxidative stress, cellular macromolecules proteins, DNA, and lipids can undergo different oxidative modifications, leading to disruption of their normal, sometimes critical, physiological functions. Recent reports also indicated that many mitochondrial proteins are modified via various post-translation modifications (PTMs) and primarily inactivated. Because of the recently-emerging information, in this review, we specifically focus on the mechanisms and roles of five major PTMs (namely oxidation, nitration, phosphorylation, acetylation, and adduct formation with lipid-peroxides, reactive metabolites, or advanced glycation end products) in experimental models of alcoholic and nonalcoholic fatty liver disease as well as acute hepatic injury caused by toxic compounds. We also highlight the role of the ethanol-inducible cytochrome P450-2E1 (CYP2E1) in some of these PTM changes. Finally, we discuss translational research opportunities with natural and/or synthetic anti-oxidants, which can prevent or delay the onset of mitochondrial dysfunction, fat accumulation and tissue injury.

Activation of farnesoid X receptor attenuates hepatic injury in a murine model of alcoholic liver disease

Alcoholic liver disease (ALD) is a common cause of advanced liver disease, and considered as a major risk factor of morbidity and mortality worldwide. Hepatic cholestasis is a pathophysiological feature observed in all stages of ALD. The farnesoid X receptor (FXR) is a member of the nuclear hormone receptor superfamily, and plays an essential role in the regulation of bile acid, lipid and glucose homeostasis. However, the role of FXR in the pathogenesis and progression of ALD remains largely unknown. Mice were fed Lieber-DeCarli ethanol diet or an isocaloric control diet. We used a specific agonist of FXR WAY-362450 to study the effect of pharmacological activation of FXR in alcoholic liver disease. In this study, we demonstrated that FXR activity was impaired by chronic ethanol ingestion in a murine model of ALD. Activation of FXR by specific agonist WAY-362450 protected mice from the development of ALD. We also found that WAY-362450 treatment rescued FXR activity, suppressed ethanol-induced Cyp2e1 up-regulation and attenuated oxidative stress in liver. Our results highlight a key role of FXR in the modulation of ALD development, and propose specific FXR agonists for the treatment of ALD patients.

Synergistic action of 4-hydroxynonenal and tumor necrosis factor involving the NF-kB/IkBa signaling pathway in alcohol-induced liver injury

To investigate the effects and mechanism of intracellular 4-hydroxynonenal (4-HNE) accumulation on tumor necrosis factor (TNF)-induced hepatotoxicity in alcoholic liver disease (ALD). An ALD model was established in male C57BL/6 mice (6-8 weeks old) by feeding an ethanol-containing diet for 5 weeks; mice given regular (non-ethanol) diet served as controls. ALD-related changes in 4-HNE and TNF levels were detected by western blotting. The underlying mechanisms of this molecular effect were examined by pre-treating HepG2 cells with 4-HNE followed by exposure to various concentrations of TNF. Effects on cell death were evaluated by MTT assay. Effects on TNF-mediated upstream factors' expression were detected by ELISA, western blotting, and real-time PCR. Effects on the TNF-induced inhibitor of NF-kB (IkBa) activity (phosphorylation status) and its formation of adducts were detected by western blotting and immunoprecipitation. ALD mice showed increased hepatic 4-HNE and TNF levels, and the increases were associated with extent of liver injury. Cell culture studies revealed that 4-HNE, at non-toxic concentrations, sensitized hepatocytes to TNF killing, which was associated with suppressed NF-kB trans activity. Furthermore, 4-HNE prevented phosphorylation of IkBa without affecting upstream IkB kinase activity. The ALD-enhanced 4-HNE content was found to associated with increased formation of 4-HNE-IkBa adduction for both the 4-HNE - treated hepatocytes in culture and in the livers of ALD mice. Alcohol-induced increase in 4-HNE accumulation represents a potent and clinically relevant mechanism of sensitizing hepatocytes to TNF-induced toxicity. These data support the notion that decreasing or eliminating accumulated intracellular 4-HNE can serve as a potential therapeutic option for ALD.

Build a better mouse model, and the world will beat a path to your door

Build a better mouse model, and the world will beat a path to your door

Increased carbonylation of the lipid phosphatase PTEN contributes to Akt2 activation in a murine model of early alcohol-induced steatosis

The production of reactive aldehydes such as 4-hydroxynonenal (4-HNE) is a key event in the pathogenesis of alcoholic liver disease (ALD), which ranges from simple steatosis to fibrosis. The lipid phosphatase PTEN plays a central role in the regulation of lipid metabolism in the liver. In this study, the effects of chronic ethanol feeding and carbonylation on the PTEN signaling pathway were examined in a 9-week mouse feeding model for ALD. Chronic ethanol consumption resulted in altered redox homeostasis as evidenced by decreased GSH, decreased Trx1, and increased GST activity. Both PTEN expression and PTEN phosphorylation were significantly increased in the livers of ethanol-fed mice. Carbonylation of PTEN increased significantly in the ethanol-fed mice compared to pair-fed control animals, corresponding to decreased PTEN 3-phosphatase activity. Concomitantly, increased expression of Akt2 along with increased Akt phosphorylation at residues Thr308, Thr450, and Ser473 was observed resulting in increased Akt2 activity in the ethanol-fed animals. Akt2 activation corresponded to a decrease in cytosolic SREBP and ChREBP. Subsequent LC/MS/MS analysis of 4-HNE-modified recombinant human PTEN identified Michael addition adducts of 4-HNE on Cys71, Cys136, Lys147, Lys223, Cys250, Lys254, Lys313, Lys327, and Lys344. Computational-based molecular modeling analysis of 4-HNE adducted to Cys71 near the active site and Lys327 in the C2 domain of PTEN suggested inhibition of enzyme catalysis via either stearic hindrance of the active-site pocket or prevention of C2 domain-dependent PTEN function. We hypothesize that 4-HNE-mediated PTEN inhibition contributes to the observed activation of Akt2, suggesting a possible novel mechanism of lipid accumulation in response to increased reactive aldehyde production during chronic ethanol administration in mice.

A diagnostic model for alcoholic liver disease based on a generalized regression neural network

To study the feasibility and rationale of using a generalized regression neural network model integrated with multiple disease indicators for diagnosing alcoholic liver disease (ALD). ALD indicators were identified by reviewing the clinical testing results of 40 ALD patients from the literature and 135 patients from the Second Xiangya Hospital of Central South University, who were also classified by physician experts upon clinical consultation. Seven indicators were selected as diagnosis indexes and applied to a general regression neural network diagnostic model. Thirty-four of the reported patients and 120 of the clinical patients were selected for use as training samples to establish the indicator recognition pattern for the model, and the remaining six and 15 patients from the two respective groups were selected for use as testing samples to determine the model's diagnostic ability. The model provided a correct diagnosis of ALD sub-classification for 94.1% (32/34) of the reported patients and 100% (120/120) of the clinical patients in the training set. The correct diagnosis rates achieved with the training sets were 100% for both the reported patient group (6/6) and the clinical patient group (15/15), indicating that the results of the diagnostic model were in good agreement with the ALD classifications generated by the clinical expert consultations. The general regression neural network model based on multiple indicators of ALD is capable of providing accurate and comprehensive diagnosis of ALD and may be feasible for clinical applications.

The Effect of Inflammatory Cytokines in Alcoholic Liver Disease

Alcohol is the most common cause of liver disease in the world. Chronic alcohol consumption leads to hepatocellular injury and liver inflammation. Inflammatory cytokines, such as TNF-α and IFN-γ, induce liver injury in the rat model of alcoholic liver disease (ALD). Hepatoprotective cytokines, such as IL-6, and anti-inflammatory cytokines, such as IL-10, are also associated with ALD. IL-6 improves ALD via activation of the signal transducer and activator of transcription 3 (STAT3) and the subsequent induction of a variety of hepatoprotective genes in hepatocytes. IL-10 inhibits alcoholic liver inflammation via activation of STAT3 in Kupffer cells and the subsequent inhibition of liver inflammation. Alcohol consumption promotes liver inflammation by increasing translocation of gut-derived endotoxins to the portal circulation and activating Kupffer cells through the LPS/Toll-like receptor (TLR) 4 pathways. Oxidative stress and microflora products are also associated with ALD. Interactions between pro- and anti-inflammatory cytokines and other cytokines and chemokines are likely to play important roles in the development of ALD. The present study aims to conduct a systemic review of ALD from the aspect of inflammation.

Increased Nitroxidative Stress Promotes Mitochondrial Dysfunction in Alcoholic and Nonalcoholic Fatty Liver Disease

Increased nitroxidative stress causes mitochondrial dysfunctions through oxidative modifications of mitochondrial DNA, lipids, and proteins. Persistent mitochondrial dysfunction sensitizes the target cells/organs to other pathological risk factors and thus ultimately contributes to the development of more severe disease states in alcoholic and nonalcoholic fatty liver disease. The incidences of nonalcoholic fatty liver disease continuously increase due to high prevalence of metabolic syndrome including hyperlipidemia, hypercholesterolemia, obesity, insulin resistance, and diabetes. Many mitochondrial proteins including the enzymes involved in fat oxidation and energy supply could be oxidatively modified (including S-nitrosylation/nitration) under increased nitroxidative stress and thus inactivated, leading to increased fat accumulation and ATP depletion. To demonstrate the underlying mechanism(s) of mitochondrial dysfunction, we employed a redox proteomics approach using biotin-N-maleimide (biotin-NM) as a sensitive biotin-switch probe to identify oxidized Cys residues of mitochondrial proteins in the experimental models of alcoholic and acute liver disease. The aims of this paper are to briefly describe the mechanisms, functional consequences, and detection methods of mitochondrial dysfunction. We also describe advantages and limitations of the Cys-targeted redox proteomics method with alternative approaches. Finally, we discuss various applications of this method in studying oxidatively modified mitochondrial proteins in extrahepatic tissues or different subcellular organelles and translational research.