Alcohol-mediated Liver Injury Research Articles

Protective role of 17β-estradiol in alcohol-associated liver fibrosis is mediated by suppression of integrin signaling.

Alcohol-associated liver disease is a complex disease regulated by genetic and environmental factors such as diet and sex. The combination of high-fat diet and alcohol consumption has synergistic effects on liver disease progression. Female sex hormones are known to protect females from liver disease induced by high-fat diet. In contrast, they promote alcohol-mediated liver injury. We aimed to define the role of female sex hormones on liver disease induced by a combination of high-fat diet and alcohol. Wild-type and protein arginine methyltransferase (Prmt)6 knockout female mice were subjected to gonadectomy (ovariectomy, OVX) or sham surgeries and then fed western diet and alcohol in the drinking water. We found that female sex hormones protected mice from western diet/alcohol-induced weight gain, liver steatosis, injury, and fibrosis. Our data suggest that these changes are, in part, mediated by estrogen-mediated induction of arginine methyltransferase PRMT6. Liver proteome changes induced by OVX strongly correlated with changes induced by Prmt6 knockout. Using Prmt6 knockout mice, we confirmed that OVX-mediated weight gain, steatosis, and injury are PRMT6 dependent, while OVX-induced liver fibrosis is PRMT6 independent. Proteomic and gene expression analyses revealed that estrogen signaling suppressed the expression of several components of the integrin pathway, thus reducing integrin-mediated proinflammatory (Tnf, Il6) and profibrotic (Tgfb1, Col1a1) gene expression independent of PRMT6 levels. Integrin signaling inhibition using Arg-Gly-Asp peptides reduced proinflammatory and profibrotic gene expression in mice, suggesting that integrin suppression by estrogen is protective against fibrosis development. Taken together, estrogen signaling protects mice from liver disease induced by a combination of alcohol and high-fat diet through upregulation of Prmt6 and suppression of integrin signaling.

Alcohol as a Modifiable Risk Factor for Alzheimer's Disease-Evidence from Experimental Studies.

Alzheimer's disease (AD) is a progressive neurodegenerative disease characterized by cognitive impairment and memory loss. Epidemiological evidence suggests that heavy alcohol consumption aggravates AD pathology, whereas low alcohol intake may be protective. However, these observations have been inconsistent, and because of methodological discrepancies, the findings remain controversial. Alcohol-feeding studies in AD mice support the notion that high alcohol intake promotes AD, while also hinting that low alcohol doses may be protective against AD. Chronic alcohol feeding to AD mice that delivers alcohol doses sufficient to cause liver injury largely promotes and accelerates AD pathology. The mechanisms by which alcohol can modulate cerebral AD pathology include Toll-like receptors, protein kinase-B (Akt)/mammalian target of rapamycin (mTOR) pathway, cyclic adenosine monophosphate (cAMP) response element-binding protein phosphorylation pathway, glycogen synthase kinase 3-β, cyclin-dependent kinase-5, insulin-like growth factor type-1 receptor, modulation of β-amyloid (Aβ) synthesis and clearance, microglial mediated, and brain endothelial alterations. Besides these brain-centric pathways, alcohol-mediated liver injury may significantly affect brain Aβ levels through alterations in the peripheral-to-central Aβ homeostasis. This article reviews published experimental studies (cell culture and AD rodent models) to summarize the scientific evidence and probable mechanisms (both cerebral and hepatic) by which alcohol promotes or protects against AD progression.

Shc Is Implicated in Calreticulin-Mediated Sterile Inflammation in Alcoholic Hepatitis.

Src homology and collagen (Shc) proteins are major adapters to extracellular signals, however, the regulatory role of Shc isoforms in sterile inflammatory responses in alcoholic hepatitis (AH) has not been fully investigated. We hypothesized that in an isoform-specific manner Shc modulates pre-apoptotic signals, calreticulin (CRT) membrane exposure, and recruitment of inflammatory cells. Liver biopsy samples from patients with AH vs healthy subjects were studied for Shc expression using DNA microarray data and immunohistochemistry. Shc knockdown (hypomorph) and age-matched wild-type mice were pair-fed according to the chronic-plus-binge alcohol diet. To analyze hepatocyte-specific effects, adeno-associated virus 8-thyroxine binding globulin-Cre (hepatocyte-specific Shc knockout)-mediated deletion was performed in flox/flox Shc mice. Lipid peroxidation, proinflammatory signals, redox radicals, reduced nicotinamide adenine dinucleotide/oxidized nicotinamide adenine dinucleotide ratio, as well as cleaved caspase 8, B-cell-receptor-associated protein 31 (BAP31), Bcl-2-associated X protein (Bax), and Bcl-2 homologous antagonist killer (Bak), were assessed invivo. CRT translocation was studied in ethanol-exposed p46ShcẟSH2-transfected hepatocytes by membrane biotinylation in conjunction with phosphorylated-eukaryotic initiation factor 2 alpha, BAP31, caspase 8, and Bax/Bak. The effects of idebenone, a novel Shc inhibitor, was studied in alcohol/pair-fed mice. Shc was significantly induced in patients with AH (P< .01). Alanine aminotransferase, reduced nicotinamide adenine dinucleotide/oxidized nicotinamide adenine dinucleotide ratios, production of redox radicals, and lipid peroxidation improved (P < .05), and interleukin 1β, monocyte chemoattractant protein 1, and C-X-C chemokine ligand 10 were reduced in Shc knockdown and hepatocyte-specific Shc knockout mice. Invivo, Shc-dependent induction, and, in hepatocytes, a p46Shc-dependent increase in pre-apoptotic proteins Bax/Bak, caspase 8, BAP31 cleavage, and membrane translocation of CRT/endoplasmic reticulum-resident protein 57 were seen. Idebenone protected against alcohol-mediated liver injury. Alcohol induces p46Shc-dependent activation of pre-apoptotic pathways and translocation of CRT to the membrane, where it acts as a damage-associated molecular pattern, instigating immunogenicity. Shc inhibition could be a novel treatment strategy in AH.

ALDH2 deficiency increases susceptibility to binge alcohol-induced gut leakiness, endotoxemia, and acute liver injury in mice through the gut-liver axis

Mitochondrial aldehyde dehydrogenase 2 (ALDH2) is the major enzyme responsible for metabolizing toxic acetaldehyde to acetate and acts as a protective or defensive protein against various disease states associated with alcohol use disorder (AUD), including alcohol-related liver disease (ARLD). We hypothesized that Aldh2-knockout (KO) mice are more susceptible to binge alcohol-mediated liver injury than wild-type (WT) mice through increased oxidative stress, gut leakiness and endotoxemia. Therefore, this study aimed to investigate the protective role of ALDH2 in binge alcohol-induced gut permeability, endotoxemia, and acute inflammatory liver injury by exposing Aldh2-KO or WT mice to a single oral dose of binge alcohol 3.5, 4.0, or 5.0 g/kg. Our findings showed for the first time that ALDH2 deficiency in Aldh2-KO mice increases their sensitivity to binge alcohol-induced oxidative and nitrative stress, enterocyte apoptosis, and nitration of gut tight junction (TJ) and adherent junction (AJ) proteins, leading to their degradation. These resulted in gut leakiness and endotoxemia in Aldh2-KO mice after exposure to a single dose of ethanol even at 3.5 g/kg, while no changes were observed in the corresponding WT mice. The elevated serum endotoxin (lipopolysaccharide, LPS) and bacterial translocation contributed to systemic inflammation, hepatocyte apoptosis, and subsequently acute liver injury through the gut-liver axis. Treatment with Daidzin, an ALDH2 inhibitor, exacerbated ethanol-induced cell permeability and reduced TJ/AJ proteins in T84 human colon cells. These changes were reversed by Alda-1, an ALDH2 activator. Furthermore, CRISPR/Cas9-mediated knockout of ALDH2 in T84 cells increased alcohol-mediated cell damage and paracellular permeability. All these findings demonstrate the critical role of ALDH2 in alcohol-induced epithelial barrier dysfunction and suggest that ALDH2 deficiency or gene mutation in humans is a risk factor for alcohol-mediated gut and liver injury, and that ALDH2 could be an important therapeutic target against alcohol-associated tissue or organ damage.

Lemon balm and dandelion leaf extract synergistically alleviate ethanol-induced hepatotoxicity by enhancing antioxidant and anti-inflammatory activity.

We investigated the effect of a 2:1 (w/w) mixture of lemon balm and dandelion extracts (LD) on ethanol (EtOH)-mediated liver injury and explored the underlying mechanisms. Administration of LD synergistically reduced relative liver weight and decreased the levels of serum biomarkers of hepatic injury. Histopathological and biochemical analyses indicated that LD synergistically attenuated hepatic accumulation of triacylglycerides (TGs) and restored the levels of mRNAs related to fatty acid metabolism. In addition, LD significantly reduced EtOH-induced hepatic oxidative stress by attenuating the reduction in levels of nuclear factor E2-related factor 2 (Nrf2) mRNA and enhancing antioxidant activity. Moreover, LD decreased the EtOH-mediated increase in levels of hepatic tumor necrosis factor-α (TNF-α) mRNA. In vitro, LD significantly scavenged free radicals, increased cell viability against tert-butylhydroperoxide (tBHP), and transactivated Nrf2 target genes in HepG2 cells. Furthermore, LD decreased levels of pro-inflammatory mediators in lipopolysaccharide-stimulated Raw264.7 cells. Therefore, LD shows promise for preventing EtOH-mediated liver injury. PRACTICAL APPLICATIONS: There were no approved therapeutic agents for preventing and/or treating alcoholic liver diseases. In this study, a 2:1 (w/w) mixture of lemon balm and dandelion leaf extract (DL) synergistically ameliorated EtOH-induced hepatic injury by inhibiting lipid accumulation, oxidative stress, and inflammation. Our findings will enable the development of a novel food supplement for the prevention or treatment of alcohol-mediated liver injury.

The effects of changes in glutathione levels through exogenous agents on intracellular cysteine content and protein adduct formation in chronic alcohol-treated VL17A cells

Alcohol-mediated liver injury is associated with changes in the level of the major cellular antioxidant glutathione (GSH). It is interesting to investigate if the changes in intracellular GSH level through exogenous agents affect the intracellular cysteine content and the protein adduct formation indicative of oxidative insult in chronic alcohol treated liver cells. In VL-17A cells treated with 2 mM N-acetyl cysteine (NAC) or 0.1 mM ursodeoxycholic acid (UDCA) plus 100 mM ethanol, an increase in cysteine concentration which was accompanied by decreases in hydroxynonenal (HNE) and glutathionylated protein adducts were observed. Pretreatment of 100 mM ethanol treated VL-17A cells with 0.4 mM buthionine sulfoximine (BSO) or 1 mM diethyl maleate (DEM) had opposite effects. Thus, altered GSH level through exogenous agents may either potentiate or ameliorate chronic alcohol-mediated protein adduct formation and change the cysteine level in chronic alcohol treated VL-17A cells. The gene expression of non-treated and ethanol-treated hepatocytes in 2 microarray datasets was also compared to locate differentially expressed genes involved in cysteine metabolism. The study demonstrates that increased protein adducts formation and changes in cysteine concentration occur under chronic alcohol condition in liver cells which may increase alcohol-mediated oxidative injury.

TLR2 and TLR9 contribute to alcohol-mediated liver injury through induction of CXCL1 and neutrophil infiltration.

Although previous studies reported the involvement of the TLR4-TRIF pathway in alcohol-induced liver injury, the role of TLR2 and TLR9 signaling in alcohol-mediated neutrophil infiltration and liver injury has not been elucidated. Since alcohol binge drinking is recognized to induce more severe form of alcohol liver disease, we used a chronic-binge ethanol-feeding model as a mouse model for early stage of alcoholic hepatitis. Whereas a chronic-binge ethanol feeding induced alcohol-mediated liver injury in wild-type mice, TLR2- and TLR9-deficient mice showed reduced liver injury. Induction of neutrophil-recruiting chemokines, including Cxcl1, Cxcl2, and Cxcl5, and hepatic neutrophil infiltration were increased in wild-type mice, but not in TLR2- and TLR9-deficient mice. In vivo depletion of Kupffer cells (KCs) by liposomal clodronate reduced liver injury and the expression of Il1b, but not Cxcl1, Cxcl2, and Cxcl5, suggesting that KCs are partly associated with liver injury, but not neutrophil recruitment, in a chronic-binge ethanol-feeding model. Notably, hepatocytes and hepatic stellate cells (HSCs) produce high amounts of CXCL1 in ethanol-treated mice. The treatment with TLR2 and TLR9 ligands synergistically upregulated CXCL1 expression in hepatocytes. Moreover, the inhibitors for CXCR2, a receptor for CXCL1, and MyD88 suppressed neutrophil infiltration and liver injury induced by chronic-binge ethanol treatment. Consistent with the above findings, hepatic CXCL1 expression was highly upregulated in patients with alcoholic hepatitis. In a chronic-binge ethanol-feeding model, the TLR2 and TLR9-dependent MyD88-dependent pathway mediates CXCL1 production in hepatocytes and HSCs; the CXCL1 then promotes neutrophil infiltration into the liver via CXCR2, resulting in the development of alcohol-mediated liver injury.

Emodin Ameliorates Ethanol-Induced Fatty Liver Injury in Mice

The liver plays a central role in ethanol (EtOH) metabolism, and oxidative stress is implicated in alcohol-mediated liver injury. The present study aimed to investigate the role of emodin in EtOH-induced fatty liver injury. Liver histology, biochemistry and gene-expression studies were performed. Mice fed with an EtOH-containing diet exhibited severe macrovesicular steatosis and higher serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels. However, emodin ameliorated liver steatosis and lowered ALT and AST. Emodin also decreased hepatic triglyceride in mice fed with EtOH. In addition, emodin attenuates Oil Red O staining in alcoholic fatty liver in mice. Hepatic cytochrome P450 2E1 protein levels were upregulated in EtOH-fed mice, but downregulated in emodin-treated mice. In addition, emodin decreased hepatic oxidative stress. Furthermore, emodin significantly reduced liver α-smooth muscle actin and collagen type I, whereas it increased the mRNA levels of PPAR-γ. Taken together, emodin plays protective roles in alcohol-mediated liver steatosis.

β-catenin is essential for ethanol metabolism and protection against alcohol-mediated liver steatosis in mice.

The liver plays a central role in ethanol metabolism, and oxidative stress is implicated in alcohol-mediated liver injury. β-Catenin regulates hepatic metabolic zonation and adaptive response to oxidative stress. We hypothesized that β-catenin regulates the hepatic response to ethanol ingestion. Female liver-specific β-catenin knockout (KO) mice and wild-type (WT) littermates were fed the Lieber-Decarli liquid diet (5% ethanol) in a pairwise fashion. Liver histology, biochemistry, and gene-expression studies were performed. Plasma alcohol and ammonia levels were measured using standard assays. Ethanol-fed (EtOH) KO mice exhibited systemic toxicity and early mortality. KO mice exhibited severe macrovesicular steatosis and 5 to 6-fold higher serum alanine aminotransferase and aspartate aminotransferase levels. KO mice had a modest increase in hepatic oxidative stress, lower expression of mitochondrial superoxide dismutase (SOD2), and lower citrate synthase activity, the first step in the tricarboxylic acid cycle. N-Acetylcysteine did not prevent ethanol-induced mortality in KO mice. In WT livers, β-catenin was found to coprecipitate with forkhead box O3, the upstream regulator of SOD2. Hepatic alcohol dehydrogenase and aldehyde dehydrogenase activities and expression were lower in KO mice. Hepatic cytochrome P450 2E1 protein levels were up-regulated in EtOH WT mice, but were nearly undetectable in KO mice. These changes in ethanol-metabolizing enzymes were associated with 30-fold higher blood alcohol levels in KO mice. β-Catenin is essential for hepatic ethanol metabolism and plays a protective role in alcohol-mediated liver steatosis. Our results strongly suggest that integration of these functions by β-catenin is critical for adaptation to ethanol ingestion in vivo.

Bio-informatics based analysis of genes implicated in alcohol mediated liver injury

Alcohol induced liver injury has been studied extensively. Using literature search and bioinformatics tools, the present study characterizes the genes involved in alcohol induced liver injury. The cellular and metabolic processes in which genes involved in alcohol induced liver injury are implicated are also discussed. The genes related to alcohol induced liver injury are also involved in affecting certain molecular functions and metabolism of drugs, besides being associated with diseases. In conclusion, the changes in regulation of genes implicated in alcohol induced liver injury apart from causing alcohol mediated hepatic dysfunction may affect other vital processes in the body.

Rat strain differences in susceptibility to alcohol-induced chronic liver injury and hepatic insulin resistance.

The finding of more severe steatohepatitis in alcohol fed Long Evans (LE) compared with Sprague Dawley (SD) and Fisher 344 (FS) rats prompted us to determine whether host factors related to alcohol metabolism, inflammation, and insulin/IGF signaling predict proneness to alcohol-mediated liver injury. Adult FS, SD, and LE rats were fed liquid diets containing 0% or 37% (calories) ethanol for 8 weeks. Among controls, LE rats had significantly higher ALT and reduced GAPDH relative to SD and FS rats. Among ethanol-fed rats, despite similar blood alcohol levels, LE rats had more pronounced steatohepatitis and fibrosis, higher levels of ALT, DNA damage, pro-inflammatory cytokines, ADH, ALDH, catalase, GFAP, desmin, and collagen expression, and reduced insulin receptor binding relative to FS rats. Ethanol-exposed SD rats had intermediate degrees of steatohepatitis, increased ALT, ADH and profibrogenesis gene expression, and suppressed insulin receptor binding and GAPDH expression, while pro-inflammatory cytokines were similarly increased as in LE rats. Ethanol feeding in FS rats only reduced IL-6, ALDH1–3, CYP2E1, and GAPDH expression in liver. In conclusion, susceptibility to chronic steatohepatitis may be driven by factors related to efficiency of ethanol metabolism and degree to which ethanol exposure causes hepatic insulin resistance and cytokine activation.

Interplay between oxidative stress and immunity in the progression of alcohol-mediated liver injury

Inflammation is recognized increasingly as having an important role in the pathogenesis of alcoholic liver disease (ALD). Nonetheless, the mechanisms by which alcohol maintains hepatic inflammation are still characterized incompletely. Several studies have demonstrated that ethanol-induced oxidative stress promotes immune responses in ALD by stimulating both humoral and cellular reactions against liver proteins adducted to hydroxyethyl free radicals and several lipid peroxidation products. Moreover, ALD patients have autoantibodies targeting cytochrome P4502E1 and oxidized phospholipids. In both chronic alcohol-fed rats and heavy drinkers, the elevation of IgG against lipid peroxidation-derived antigens is associated with tumor necrosis factor-alpha production and the severity of liver inflammation. On this basis, we propose that allo- and autoimmune reactions associated with oxidative stress might contribute to fueling hepatic inflammation in ALD.

Immunohistochemical characterization of hepatic malondialdehyde and 4-hydroxynonenal modified proteins during early stages of ethanol-induced liver injury.

Chronic ethanol consumption is associated with hepatic lipid peroxidation and the deposition or retention of aldehyde-adducted proteins postulated to be involved in alcohol-induced liver injury. The purpose of this study was to characterize hepatocellular formation of aldehyde-protein adducts during early stages of alcohol-induced liver injury. Female Sprague Dawley(R) rats were subjected to the intragastric administration of a low-carbohydrate/high-fat total enteral nutrition diet or a total enteral nutrition diet containing ethanol for a period of 36 days. Indexes of hepatic responses to ethanol were evaluated in terms of changes in plasma alanine aminotransferase activity, hepatic histopathologic analysis, and induction of cytochrome P-4502E1 (CYP2E1). Immunohistochemical methods were used to detect hepatic proteins modified with malondialdehyde (MDA) or 4-hydroxynonenal (4-HNE) for subsequent quantitative image analysis. After 36 days of treatment, rats receiving the alcohol-containing diet displayed hepatic histopathologies characterized by marked micro- and macrosteatosis associated with only minor inflammation and necrosis. Alcohol administration resulted in a 3-fold elevation of plasma alanine aminotransferase activity and 3-fold increases (p < 0.01) in hepatic CYP2E1 apoprotein and activity. Quantitative immunohistochemical analysis revealed significant (p < 0.01) 5-fold increases in MDA- and 4-HNE modified proteins in liver sections prepared from rats treated with alcohol. The MDA- or 4-HNE modified proteins were contained in hepatocytes displaying intact morphology and were colocalized primarily with microvesicular deposits of lipid. Aldehyde-modified proteins were not prevalent in parenchymal or nonparenchymal cells associated with foci of necrosis or inflammation. These results suggest that alcohol-induced lipid peroxidation is an early event during alcohol-mediated liver injury and may be a sensitizing event resulting in the production of bioactive aldehydes that have the potential to initiate or propagate ensuing proinflammatory or profibrogenic cellular events.

POTENTIAL NEW THERAPIES FOR ALCOHOLIC LIVER DISEASE

Alcoholic liver disease (ALD) is a common clinical problem. The various stages of alcoholic liver injury include alcoholic fatty liver, alcoholic hepatitis, and cirrhosis of the liver. 79,84 It has been suggested that only 8% to 20% of long-term alcohol abusers develop alcoholic cirrhosis. 16,45,62,127 The goals of therapy in ALD are shown below. Avoid alcohol Improve nutrition Treat hepatic injury Prevent progression to cirrhosis Avoid complications of severe liver disease Evaluate presence of coexisting hepato-injurious factors Attempt reversal of cirrhosis Promote hepatic regeneration and function Consider liver transplantation in end-stage liver disease Long-term outcome in these patients depends on three major factors— degree of continued alcohol abuse, severity of underlying liver damage and additional hepato-injurious factors (hepatitis C virus [HCV], acetaminophen). 12,43,126 The acute mortality of acute alcoholic hepatitis is 20% to 60%. 12 Progression to cirrhosis may occur despite abstinence but usually arises in subjects who continue to abuse alcohol. 105 Understanding the biomolecular basis of liver injury has advanced significantly in the past decade. The importance of acetaldehyde, free radicals and acetaldehyde–protein adduct antibody reactions has been studied extensively. 63,64,136 Conventional and potentially beneficial therapies for alcoholic liver disease are based on blocking or attempting to block one or more steps in the proposed pathogenic pathway for alcohol-mediated hepatic injury. 80 The major steps in alcohol-mediated liver injury are shown in Figure 1. 127 Conventional therapeutic measures for alcoholic hepatitis have included corticosteroids and nutritional rehabilitation. 12 Hepatoprotection by hormonal alterations (insulin-glucagon) has not been found to be very beneficial and colchicine may be of some benefit in fibrosis reduction. 80,86 Newer forms of interventions have included measures directed against the free radicals and cellular toxins such as iron overload and nitric oxide deficiency. Other measures have included those against endotoxemia and provision of the metabolite intermediates that are deficient in hepatocytes injured by alcohol. 38,63,64 These compounds have included pharmacologic agents used in patients with other forms of liver disease, provision of precursors for protective agents via dietary interventions, and many herbal products, the mechanisms of action of which are not yet clearly understood. 37,80,85,86 The present review focuses on less conventional agents that have been considered promising in initial clinical trials or have a rationale based on our current understanding of the pathogenesis of alcoholic liver injury. Hepatocytoprotective agents Ursodeoxycholic acid * *Controlled/uncontrolled trials in humans in addition to animal/experimental studies. Cyanidanol * Alpha-thioctic acid Silybum marianum* Pentoxifylline * Licorice derivatives Malotilate * Calcium channel blockers * Misoprostol † †Animal studies only available. rHGH=recombinant human growth hormone; CYP2E1=cytochrome P4502E1. Special nutrients S-Adenosyl methionine * Polyunsaturated lecithin * Saturated fat in diet † Linoleic acid † L-Cysteine † L-Glycine † Antioxidants Alpha-tocopherol * Lazeroid † Chrysanthemum extract †, kakkelide †, sirepar†, propolis † Iron chelation Macromolecular desferrioxamine † Anti-endotoxin (antibiotics, others) Ciprofloxacin, polymixin-neomycin † Nitric oxide synthase modulaters † Paromycin * Molecular interventions Proline analogues; rHGH * E3330 †; prolyl 4 hydroxylase inhibitors Others N-acetyl cysteine * Naftidrofuryl * Picroliv † CYP2E1 inhibitors †, Cimetidine † Metadoxine * The agents that have been considered promising in the therapy of ALD may be considered under various categories—agents that have been subjected to randomized trials, those evaluated in open trials, and agents under evaluation in experimental models. Some agents have been evaluated for ALD without definite experimental basis, but have shown promise in therapy for other liver diseases (Tables 1 and 2).

ALCOHOLIC LIVER DISEASE

Alcohol has been implicated in the genesis of liver disease for centuries. Significant progress has been made in our understanding of the pathogenesis of ALD. It is now apparent that both the consumption and the metabolism of alcohol promote the production of inflammatory mediators (cytokines) that result in hepatotoxicity and fibrogenesis. With time, this leads to progressively severe liver injury and, eventually, causes cirrhosis. Unfortunately, effective therapies for most individuals with ALD have not been found. High per capita consumption of alcohol, coupled with the dearth of effective treatments and the failure of most affected individuals to abstain from alcohol, explains why ALD is one of the most prevalent forms of disabling, chronic liver disease in the United States.