Alcoholic liver disease

The Hepatoprotective Effect of Leonurine Hydrochloride Against Alcoholic Liver Disease Based on Transcriptomic and Metabolomic Analysis

Excessive alcohol consumption can eventually progress to alcoholic liver disease (ALD). The underlying mechanism of ALD toxicity is primarily associated with oxidative damage. Many alkaloids have been reported to possess potential antioxidative efficacy, while the mechanism of their hepatoprotective activity against ALD is still not clear. In this study, eight alkaloids were selected from a monomer library of Traditional Chinese Medicine and evaluated for their antioxidant activity against ALD by the evaluation of Glutathione (GSH) and Malondialdehyde (MDA). The result suggested that Leonurine hydrochloride (LH) was a potent antioxidant that could reduce alcoholic liver damage. To further investigate the underlying mechanism of LH against ALD, the molecular pathway induced by LH was identified by RNA-seq analyses. Transcriptome data revealed the principal mechanism for the protective effect of LH against ALD might be attributed to the differentially expressed genes (DEGs) of PI3K-AKT, AMPK, and HIF-1 signaling pathways involved in the lipid metabolism. Given the hepatoprotective mechanism of LH is involved in lipid metabolism, the lipid metabolism induced by LH was further analyzed by UHPLC-MS/MS. Metabolome analysis indicated that LH significantly regulated glycerophospholipid metabolism including phosphatidylcholine, 1-acyl-sn-glycero-3-phosphocholine, phosphatidylethanolamine and 1-acyl-sn-glycero-3-phosphoethanolamine in the liver. Overall, this study revealed that the hepatoprotective mechanism of LH against alcoholic liver damage might be associated with the genes involved in glycerophospholipid metabolism.

Monascin and Ankaflavin of Monascus purpureus Prevent Alcoholic Liver Disease through Regulating AMPK-Mediated Lipid Metabolism and Enhancing Both Anti-Inflammatory and Anti-Oxidative Systems

Alcohol metabolism causes an excessive accumulation of liver lipids and inflammation, resulting in liver damage. The yellow pigments monascin (MS) and ankaflavin (AK) of Monascus purpureus-fermented rice were proven to regulate ethanol-induced damage in HepG2 cells, but the complete anti-inflammatory and anti-fatty liver mechanisms in the animal model are still unclear. This study explored the roles of MS and AK in improving alcoholic liver injury. MS and AK were simultaneously fed to evaluate their effects and mechanisms in C57BL/6J mice fed the Lieber–DeCarli liquid alcohol diet for 6 weeks. The results indicated that MS and AK significantly reduced the serum aspartate aminotransferase and alanine aminotransferase activity, as well as the total liver cholesterol and triglyceride levels. The histopathological results indicated that MS and AK prevented lipid accumulation in the liver. MS and AK effectively enhanced the activity of antioxidant enzymes and reduced the degree of lipid peroxidation; AK was particularly effective and exhibited a superior preventive effect against alcoholic liver injury and fatty liver. In addition to inhibiting the phosphorylation of the MAPK family, MS and AK directly reduced TNF-α, IL-6, and IL-1β levels, thereby reducing NF-κB and its downstream iNOS and COX-2 expressions, as well as increasing PPAR-γ, Nrf-2, and HO-1 expressions to prevent liver damage. MS and AK also directly reduced TNF-α, IL-6, and IL-1β expression, thereby reducing the production of NF-κB and its downstream iNOS and COX-2, and increasing PPAR-γ, Nrf-2, and HO-1 expressions, preventing alcohol damage to the liver.

Diverse Consequences in Liver Injury in Mice with Different Autophagy Functional Status Treated with Alcohol

Alcoholic fatty liver disease is often complicated by other pathologic insults, such as viral infection or high-fat diet. Autophagy plays a homeostatic role in the liver but can be compromised by alcohol, high-fat diet, or viral infection, which in turn affects the disease process caused by these etiologies. To understand the full impact of autophagy modulation on alcohol-induced liver injury, several genetic models of autophagy deficiency, which have different levels of functional alterations, were examined after acute binge or chronic-plus-binge treatment. Mice given alcohol with either mode and induced with deficiency in liver-specific Atg7 shortly after the induction of Atg7 deletion had elevated liver injury, indicating the protective role of autophagy. Constitutive hepatic Atg7-deficient mice, in which Atg7 was deleted in embryos, were more susceptible with chronic-plus-binge but not with acute alcohol treatment. Constitutive hepatic Atg5-deficient mice, in which Atg5 was deleted in embryos, were more susceptible with acute alcohol treatment, but liver injury was unexpectedly improved with the chronic-plus-binge regimen. A prolonged autophagy deficiency may complicate the hepatic response to alcohol treatment, likely in part due to endogenous liver injury. The complexity of the relationship between autophagy deficiency and alcohol-induced liver injury can thus be affected by the timing of autophagy dysfunction, the exact autophagy gene being affected, and the alcohol treatment regimen.

The Activation and Function of Autophagy in Alcoholic Liver Disease

Autophagy is an important lysosome-mediated intracellular degradation pathway required for tissue homeostasis. Dysregulation of liver autophagy is closely associated with different liver diseases including alcoholic liver disease. Studies now indicate that autophagy may be induced or suppressed depending on the amount and the duration of ethanol treatment. Autophagy induced by ethanol serves as a protective mechanism, probably by selective degradation of the damaged mitochondria (mitophagy) and excess lipid droplets (lipophagy) and in turn attenuates alcohol-induced steatosis and liver injury. However, the detailed molecular mechanism of selective targeting of mitochondria and lipid is still unclear. Autophagy may possess other functions that protect hepatocytes from ethanol. Understanding these molecular entities would be essential in order to therapeutically module autophagy for treatment of alcoholic liver disease.

Chronic Alcohol Consumption Inhibits Autophagy and Promotes Apoptosis in the Liver

Background: Chronic alcohol consumption is a major cause of liver injury. However, the molecular mechanisms by which alcohol impairs hepatocellular function and induces cell death remain unclear. Macroautophagy (hereafter called 'autophagy') is a degradation pathway involved in the survival or death of cells during conditions of cellular stress. This study examines the effect of chronic alcohol consumption on hepatocellular autophagy in an animal model. Methods: During a 12-week period male Wistar rats were fed a Lieber-DeCarli diet containing 5% alcohol (EtOH group; n=10), or an isocaloric diet (control group; n=10). Hepatic expression of key regulatory autophagy proteins (e.g. Beclin-1, ATG-3, ATG-5, p62/SQSTM1 and LC3) were detected by real-time polymerase chain reaction and Western blot analysis. Markers of cellular stress and apoptotic cell death (e.g. HO-1, caspase-3, PARP-1 and Bcl-2) were determined, and levels of reduced and oxidized glutathione were measured. Results: Chronic alcohol consumption caused cellular and oxidative stress in the liver. Transcriptional and translational expression of Beclin-1 and ATG-5 was significantly impaired. The protein expression of LC3-I and LC3-II was significantly increased, while the ratio of LC3I/II remained unchanged in the EtOH group compared with controls. Hepatocellular expression of p62/SQSTM1 and markers of apoptotic cell death (such as cleaved caspase-3 and cleaved PARP-1) were significantly increased in the EtOH group indicating a disrupted autophagic flux and increased rate of apoptosis in the liver. Conclusions: In this model, chronic alcohol consumption impaired hepatocellular autophagy and induced apoptotic cell death. It appears that changes in autophagy might contribute to alcohol-induced structural and functional hepatocellular injury.

Ethanol-triggered Lipophagy Requires SQSTM1 in AML12 Hepatic Cells

Ethanol-induced hepatic lipophagy plays an important cytoprotective role against liver injury, but its mechanism is not fully determined. In the present study, ethanol-induced lipophagy was studied in an immortalized mouse hepatocyte line, AML12. We found that ethanol treatment elevated lipid content in these cells, which could be regulated by autophagy. To determine the potential mechanism, we investigated the role of a key adaptor molecule SQSTM1/p62. SQSTM1 can bind to LC3 on autophagosomes and ubiquitinated molecules on cargos, thus facilitating the autophagic engulfment of the cargo. We found that both LC3 and SQSTM1 could colocalize with lipid droplets (LDs) following ethanol treatment. Colocalization of LC3 with LDs was significantly inhibited by SQSTM1 knockdown, which also reduced ethanol-induced lipid elevation. In addition, increased ubiquitin signals were found to colocalize with SQSTM1 on LDs in response to ethanol. Moreover, the SQSTM1 signal was colocalized with that of perilipin1, a major protein on LDs. Finally, perilipin1 knockdown significantly altered ethanol-induced lipophagy. Taken together, these data support a model in which autophagosomes were directed to the LDs via SQSTM1, which bound to ubiquitinated proteins, possibly including perilipin 1, on LDs. This study provides a potential mechanistic explanation to how ethanol induces lipophagy in hepatocytes.

Relevance of autophagy to fatty liver diseases and potential therapeutic applications

Autophagy is an evolutionarily conserved lysosome-mediated cellular degradation program. Accumulating evidence shows that autophagy is important to the maintenance of liver homeostasis. Autophagy involves recycling of cellular nutrients recycling as well as quality control of subcellular organelles. Autophagy deficiency in the liver causes various liver pathologies. Fatty liver disease (FLD) is characterized by the accumulation of lipids in hepatocytes and the dysfunction in energy metabolism. Autophagy is negatively affected by the pathogenesis of FLD and the activation of autophagy could ameliorate steatosis, which suggests a potential therapeutic approach to FLD. In this review, we will discuss autophagy and its relevance to liver diseases, especially FLD. In addition, we will discuss recent findings on potential therapeutic applications of autophagy modulators for FLD.

Autophagy in alcoholic liver disease, self-eating triggered by drinking

Macroautophagy (autophagy) is an evolutionarily conserved mechanism. It is important for normal cellular function and also plays critical roles in the etiology and pathogenesis of a number of human diseases. In alcohol-induced liver disease, autophagy is a protective mechanism against the liver injury caused by alcohol. Autophagy is activated in acute ethanol treatment but could be suppressed in chronic and/or high dose treatment of alcohol. The selective removal of lipid droplets and/or damaged mitochondria is likely the major mode of autophagy in reducing liver injury. Understanding the dynamics of the autophagy process and the approach to modulate autophagy could help finding new ways to battle against alcohol-induced liver injury.

Autophagy and mitochondrial alterations in human retinal pigment epithelial cells induced by ethanol: implications of 4-hydroxy-nonenal

Retinal pigment epithelium has a crucial role in the physiology and pathophysiology of the retina due to its location and metabolism. Oxidative damage has been demonstrated as a pathogenic mechanism in several retinal diseases, and reactive oxygen species are certainly important by-products of ethanol (EtOH) metabolism. Autophagy has been shown to exert a protective effect in different cellular and animal models. Thus, in our model, EtOH treatment increases autophagy flux, in a concentration-dependent manner. Mitochondrial morphology seems to be clearly altered under EtOH exposure, leading to an apparent increase in mitochondrial fission. An increase in 2',7'-dichlorofluorescein fluorescence and accumulation of lipid peroxidation products, such as 4-hydroxy-nonenal (4-HNE), among others were confirmed. The characterization of these structures confirmed their nature as aggresomes. Hence, autophagy seems to have a cytoprotective role in ARPE-19 cells under EtOH damage, by degrading fragmented mitochondria and 4-HNE aggresomes. Herein, we describe the central implication of autophagy in human retinal pigment epithelial cells upon oxidative stress induced by EtOH, with possible implications for other conditions and diseases.

Pharmacological promotion of autophagy alleviates steatosis and injury in alcoholic and non-alcoholic fatty liver conditions in mice

BACKGROUND & AIMS

Pharmacological approaches can potentially improve fatty liver condition in alcoholic and non-alcoholic fatty liver diseases. The salutary effects of reducing lipid synthesis or promoting lipid oxidation have been well reported, but the benefits of increasing lipid degradation have yet to be well explored. Macroautophagy is a cellular degradation process that can remove subcellular organelles including lipid droplets. We thus investigated whether pharmacological modulation of macroautophagy could be an effective approach to alleviate fatty liver condition and liver injury.

METHODS

C57BL/6 mice were given ethanol via intraperitoneal injection (acute) or by a 4-week oral feeding regime (chronic), or high fat diet for 12 weeks. An autophagy enhancer, carbamazepine or rapamycin, or an autophagy inhibitor, chloroquine, was given before sacrifice. Activation of autophagy, level of hepatic steatosis, and blood levels of triglycerides, liver enzyme, glucose and insulin were measured.

RESULTS

In both acute and chronic ethanol condition, macroautophagy was activated. Carbamazepine, as well as rapamycin, enhanced ethanol-induced macroautophagy in hepatocytes in vitro and in vivo. Hepatic steatosis and liver injury were exacerbated by chloroquine, but alleviated by carbamazepine. The protective effects of carbamazepine and rapamycin in reducing steatosis and in improving insulin sensitivity were also demonstrated in high fat diet-induced non-alcoholic fatty liver condition.

CONCLUSIONS

These findings indicate that pharmacological modulation of macroautophagy in the liver can be an effective strategy for reducing fatty liver condition and liver injury.

Pharmacological promotion of autophagy alleviates steatosis and injury in alcoholic and non-alcoholic fatty liver conditions in mice

BACKGROUND & AIMS

Pharmacological approaches can potentially improve fatty liver condition in alcoholic and non-alcoholic fatty liver diseases. The salutary effects of reducing lipid synthesis or promoting lipid oxidation have been well reported, but the benefits of increasing lipid degradation have yet to be well explored. Macroautophagy is a cellular degradation process that can remove subcellular organelles including lipid droplets. We thus investigated whether pharmacological modulation of macroautophagy could be an effective approach to alleviate fatty liver condition and liver injury.

METHODS

C57BL/6 mice were given ethanol via intraperitoneal injection (acute) or by a 4-week oral feeding regime (chronic), or high fat diet for 12 weeks. An autophagy enhancer, carbamazepine or rapamycin, or an autophagy inhibitor, chloroquine, was given before sacrifice. Activation of autophagy, level of hepatic steatosis, and blood levels of triglycerides, liver enzyme, glucose and insulin were measured.

RESULTS

In both acute and chronic ethanol condition, macroautophagy was activated. Carbamazepine, as well as rapamycin, enhanced ethanol-induced macroautophagy in hepatocytes in vitro and in vivo. Hepatic steatosis and liver injury were exacerbated by chloroquine, but alleviated by carbamazepine. The protective effects of carbamazepine and rapamycin in reducing steatosis and in improving insulin sensitivity were also demonstrated in high fat diet-induced non-alcoholic fatty liver condition.

CONCLUSIONS

These findings indicate that pharmacological modulation of macroautophagy in the liver can be an effective strategy for reducing fatty liver condition and liver injury.

Hepatoprotective potential of Lavandula coronopifolia extracts against ethanol induced oxidative stress-mediated cytotoxicity in HepG2 cells

The present investigations were carried out to study the protective potential of four extracts (namely petroleum ether extract (LCR), chloroform extract (LCM), ethyl acetate extract (LCE), and alcoholic extract (LCL)) of Lavandula coronopifolia on oxidative stress-mediated cell death induced by ethanol, a known hepatotoxin in human hapatocellular carcinoma (HepG2) cells. Cells were pretreated with LCR, LCM, LCE, and LCL extracts (10-50 μg/ml) of L. coronopifolia for 24 h and then ethanol was added and incubated further for 24 h. After the exposure, cell viability using (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and neutral red uptake assays and morphological changes in HepG2 cells were studied. Pretreatment with various extracts of L. coronpifolia was found to be significantly effective in countering the cytotoxic responses of ethanol. Antioxidant properties of these L. coronopifolia extracts against reactive oxygen species (ROS) generation, lipid peroxidation (LPO), and glutathione (GSH) levels induced by ethanol were investigated. Results show that pretreatment with these extracts for 24 h significantly inhibited ROS generation and LPO induced and increased the GSH levels reduced by ethanol. The data from the study suggests that LCR, LCM, LCE, and LCL extracts of L. coronopifolia showed hepatoprotective activity against ethanol-induced damage in HepG2 cells. However, a comparative study revealed that the LCE extract was found to be the most effective and LCL the least effective. The hepatoprotective effects observed in the study could be associated with the antioxidant properties of these extracts of L. coronopifolia.

Effects of the extracts and an active compound curcumenone isolated from Curcuma zedoaria rhizomes on alcohol-induced drunkenness in mice

The Curcuma zedoaria rhizome has been used traditionally to treat gastrointestinal diseases as an aromatic stomachic drug, and this is currently used to treat alcohol-induced loss of appetite and nausea in Japan. We examined the effects of various fractions and isolated compounds on alcohol-induced drunkenness and blood alcohol concentrations in mice. The 30% ethanol-extract (1000mg/kg) of C. zedoaria rhizome prevented drunkenness 60 and 120min after 40% alcohol administration. The n-hexane-soluble fraction (300mg/kg) and an isolated compound (3, 10 or 30mg/kg) prevented drunkenness at 30, 60 or 120min. The extract, n-hexane-soluble fraction and isolated compound reduced the elevation in blood alcohol concentrations 30 and 60min after 40% alcohol administration. The isolated compound (10 and 30mg/kg) enhanced liver ADH activity 30 and 60min after 40% alcohol administration. The compound was identified as curcumenone by a direct comparison of (1)H- and (13)C-NMR spectral data. In conclusion, the protective effect of the C. zedoaria extract on drunkenness might be due to an active substance, curcumenone, and decreases in the elevation of blood alcohol concentrations through increased liver alcohol dehydrogenase activity.

The emerging role of autophagy in alcoholic liver disease

Autophagy is a highly conserved intracellular catabolic pathway that degrades cellular long-lived proteins and organelles. Autophagy is normally activated in response to nutrient deprivation and other stresses as a cell survival mechanism. Accumulating evidence indicates that autophagy plays a critical role in liver pathophysiology, in addition to maintaining hepatic energy and nutrient balance. Alcohol consumption causes hepatic metabolic changes, oxidative stress, accumulation of lipid droplets and damaged mitochondria; all of these can be regulated by autophagy. This review summarizes the recent findings about the role and mechanisms of autophagy in alcoholic liver disease (ALD), and the possible intervention for treating ALD by modulating autophagy.

Autophagy reduces acute ethanol-induced hepatotoxicity and steatosis in mice

BACKGROUND & AIMS

Alcohol abuse is a major cause of liver injury. The pathologic features of alcoholic liver disease develop over prolonged periods, yet the cellular defense mechanisms against the detrimental effects of alcohol are not well understood. We investigated whether macroautophagy, an evolutionarily conserved cellular mechanism that is commonly activated in response to stress, could protect liver cells from ethanol toxicity.

METHODS

Mice were acutely given ethanol by gavage. The effects of ethanol on primary hepatocytes and hepatic cell lines were also studied in vitro.

RESULTS

Ethanol-induced macroautophagy in the livers of mice and cultured cells required ethanol metabolism, generation of reactive oxygen species, and inhibition of mammalian target of rapamycin signaling. Suppression of macroautophagy with pharmacologic agents or small interfering RNAs significantly increased hepatocyte apoptosis and liver injury; macroautophagy therefore protected cells from the toxic effects of ethanol. Macroautophagy induced by ethanol seemed to be selective for damaged mitochondria and accumulated lipid droplets, but not long-lived proteins, which could account for its protective effects. Increasing macroautophagy pharmacologically reduced hepatotoxicity and steatosis associated with acute ethanol exposure.

CONCLUSIONS

Macroautophagy protects against ethanol-induced toxicity in livers of mice. Reagents that modify macroautophagy might be developed as therapeutics for patients with alcoholic liver disease.

Intestinal permeability in patients with chronic liver diseases: Its relationship with the aetiology and the entity of liver damage

BACKGROUND

Alteration in intestinal permeability may be an important factor in the pathogenesis of both the progression of some chronic liver diseases and the onset of some complications in patients with liver cirrhosis.

AIMS

To investigate the relationships between intestinal permeability, portal hypertension, alcohol use, plasma levels of pro-inflammatory cytokines, and nitric oxide, expressed as s-nitrosothiols, and nitrite levels in patients with various types and degrees of chronic liver diseases.

METHODS

134 healthy volunteers and 83 patients with chronic liver damage entered the study. Intestinal permeability was assessed with the lactulose/mannitol test. Plasma levels of tumour necrosis factor-alpha, interleukin-6, and nitrite and total s-nitrosothiols were determined.

RESULTS

Intestinal permeability was altered in patients with advanced liver disease and impaired in 15-35% of patients without cirrhosis. Independent factors for intestinal permeability alteration were age, portal hypertension, alcohol use, and diabetes. Plasma levels of inflammatory cytokines and nitrosothiols were significantly higher in patients with altered intestinal permeability.

CONCLUSIONS

An intestinal permeability evaluation in patients with chronic liver diseases might clarify the significance of intestinal permeability in the pathophysiology of both the progression of liver damage, and the occurrence of complications that accompany liver cirrhosis.

Isolevuglandins covalently modify phosphatidylethanolamines in vivo: detection and quantitative analysis of hydroxylactam adducts

Levuglandins (LGs) and isolevuglandins (isoLGs, also called "isoketals" or "isoKs") are extraordinarily reactive products of cyclooxygenase- and free radical-induced oxidation of arachidonates. We now report the detection in vivo and quantitative analysis of LG/isoLG adducts that incorporate the amino group of phosphatidylethanolamines (PEs) into LG/isoLG-hydroxylactams. Notably, LC-MS/MS detection of these hydroxylactams is achieved with samples that are an order of magnitude smaller and sample processing is much simpler and less time consuming than required for measuring protein-derived LG/isoLG-lysyl lactams. A key feature of our protocol is treatment of biological phospholipid extracts with phospholipase A(2) to generate mainly 1-palmitoyl-2-lysoPE-hydroxylactams from heterogeneous mixtures of phospholipids with a variety of acyl groups on the 2 position. Over 160% higher mean levels of LG/isoLG-PE-hydroxylactam (P<0.001) were detected in liver from chronic ethanol-fed mice (32.4+/-6.3 ng/g, n=6) compared to controls (12.1+/-1.5 ng/g, n=4), and mean levels in plasma from patients with age-related macular degeneration (5.2+/-0.4 ng/ml, n=15) were elevated approximately 53% (P<0.0001) compared to those of healthy volunteers (3.4+/-0.1 ng/ml, n=15). Just as LG/isoLG-protein adducts provide a dosimeter of oxidative injury, this study suggests that LG/isoLG-PE-hydroxylactams are potential biomarkers for assessing risk for oxidative stress-stimulated diseases.

Formation of gamma-ketoaldehyde-protein adducts during ethanol-induced liver injury in mice

Ethanol metabolism promotes the formation of a variety of reactive aldehydes in the liver. These aldehydes can rapidly form covalent protein adducts. Accumulating evidence indicates that these protein adducts may contribute to ethanol-mediated liver injury. Overproduction of gamma-ketoaldehydes, levuglandins (LGs) and isolevuglandins, is implicated in the pathogenesis of several chronic inflammatory diseases. gamma-Ketoaldehydes can form protein adducts orders of magnitude more quickly than 4-hydroxynonenal (4-HNE) or malondialdehyde. We hypothesized that ethanol-induced oxidative stress in vivo results in overproduction of LGE(2)- and iso[4]LGE(2)-protein adducts in mouse liver. Female C57BL/6 mice were allowed free access to an ethanol-containing diet for up to 39 days or pair-fed control diets. Pathological markers of ethanol-induced hepatic injury including serum alanine aminotransferase, hepatic triglyceride, and CYP2E1 were elevated in response to ethanol feeding. Ethanol-induced formation of iso[4]LGE(2)-, LGE(2)-, and 4-HNE-protein adducts in mouse liver was dependent on both dose and duration of ethanol feeding. Deficiency of cyclooxygenase 1 or 2 did not prevent ethanol-induced iso[4]LGE(2) or LGE(2) adducts in the liver, but adduct formation was reduced in both TNFR1- and CYP2E1-deficient mice. In summary, ethanol feeding enhanced gamma-ketoaldehyde-protein adduct production via a TNFR1/CYP2E1-dependent, but cyclooxygenase-independent, mechanism in mouse liver.

Evidence that chronic alcohol exposure promotes intestinal oxidative stress, intestinal hyperpermeability and endotoxemia prior to development of alcoholic steatohepatitis in rats

BACKGROUND/AIMS

Not all alcoholics develop liver disease (ALD). Thus, excessive ethanol consumption is necessary, but not sufficient, to induce alcoholic steatohepatitis (ASH) and ALD. Since endotoxemia is present in patients with ALD, it has been proposed that gut-derived, circulating endotoxin is the necessary co-factor for ASH. But, it is not known whether endotoxemia is the consequence or the trigger for ALD. Accordingly, the aim of the current study was to determine whether endotoxemia occurs prior to development of ASH and whether gut leakiness is the primary cause of the endotoxemia in an animal model of ASH.

METHODS

Time courses for development of gut hyperpermeability, nitric oxide production, oxidative injury to the gut, endotoxemia, and liver injury were assessed in rats during 10 weeks of daily alcohol gavage.

RESULTS

Liver fat and serum transaminase increased after 2 weeks, but evidence of liver cell injury and inflammation (ASH) occurred after 8 weeks. Gut leakiness, intestinal oxidative injury, and endotoxemia occurred in weeks 2-4 and progressed thereafter.

CONCLUSIONS

That alcohol-induced gut leakiness and endotoxemia preceded steatohepatitis indicates they are not the consequence of ALD. Our data support the hypothesis that gut leakiness resulting in endotoxemia is a key co-factor (trigger) for ASH.

Effects of extracellular signal-regulated kinase on rat cultured hepatic stellate cells stimulated by acetaldehyde

OBJECTIVE

To investigate the effects of PD98059 on the cell cycle, cell proliferation, the secretion of type I collagen and expression of transforming growth factor-beta-1 mRNA in rat hepatic stellate cells stimulated by acetaldehyde.

METHODS

Rat hepatic stellate cells stimulated by acetaldehyde were incubated with different concentrations of PD98059. The cell cycle was analyzed by flow cytometry. Cell proliferation was assessed by methyl thiazolyl tetrazolium colorimetric assay. The mRNA expression of transforming growth factor-beta-1 was examined by reverse transcriptase polymerase chain reaction. Type I collagen of the culture medium was detected by enzyme-linked immunoadsorbent assay.

RESULTS

Twenty, 50 and 100 micromol/L PD98059 could significantly inhibit the proliferation and provoke a G0/G1-phase arrest of hepatic stellate cells stimulated by acetaldehyde in a dose-dependent manner. The secretion of type I collagen and transforming growth factor-beta-1 mRNA expression of acetaldehyde-induced hepatic stellate cells were markedly inhibited by 50 and 100 micromol/L PD98059, respectively.

CONCLUSION

Extracellular signal-regulated kinase signal transduction pathway could regulate cell proliferation, the secretion of type I collagen and transforming growth factor-beta-1 mRNA expression of rat hepatic stellate cells stimulated by acetaldehyde. This is most likely related to its regulative effect on the cell cycle.

Combining steroids with enteral nutrition: a better therapeutic strategy for severe alcoholic hepatitis? Results of a pilot study

BACKGROUND

Results of a previous randomized controlled trial comparing the outcome of patients with severe alcoholic hepatitis treated with total enteral nutrition (TEN) or corticosteroids suggest that these treatments act through different mechanisms and may be complementary. We report a pilot study of combined treatment with TEN and a shorter course of steroids in patients with severe alcoholic hepatitis.

METHODS

Thirteen patients with severe alcoholic hepatitis were treated with systemic steroids and TEN. Steroid therapy started with 40 mg oral prednisolone daily, and was progressively tapered as soon as both serum bilirubin and prothrombin time decreased below 50% of their baseline values. TEN (2000 kcal, or 8374 kJ, daily) was administered throughout the hospital stay. Patients were followed for at least 12 months or until death.

RESULTS

Tapering of prednisolone dose could be started after a mean (SD) of 15.4 (3.8) days, whereas TEN was maintained for 22 (3.8) days. TEN was tolerated in 10 of the 13 patients. The major adverse event attributable to therapy was hyperglycemia requiring insulin therapy, which occurred in 12 of 13 patients. Only two patients (15%) died during the treatment period. Another patient died within the first 2 months of follow-up. In no case was the death due to infectious complications, despite two-thirds of patients developing infections during the treatment period. Infections during follow-up occurred only in three patients.

CONCLUSION

This pilot study suggests that TEN associated with a short course of steroids could be a good therapeutic strategy for severe alcoholic hepatitis. This possibility deserves investigation in a randomized controlled trial.

In vivo monitoring of hepatic oxygenation changes in chronically ethanol-treated rats by functional magnetic resonance imaging

In this study, functional magnetic resonance imaging (fMRI) was used to evaluate in vivo hepatic oxygenation changes in chronically ethanol (CE)-treated and pair-fed (PF) control rats. Male Wistar rats were pair-fed an all-liquid diet containing 36% of total calories as either ethanol or dextrin-maltose for 8 weeks. The rats were initially examined under normoxic conditions, and then subjected to 100% oxygen (hyperoxia), 10% oxygen (hypoxia), 5% carbon dioxide (hypercapnia), or an acute dose of ethanol (1.4 g/kg bw intraperitoneally). A T(2)-weighted spin-echo sequence, which may be more selective for sinusoidal (capillary bed) changes, was performed before, during, and after the four challenges. During hyperoxia, both the CE and PF rats showed a statistically significant increase in signal intensity (22% +/- 5% and 48% +/- 6%, respectively, P < 0.05) relative to normoxia, while hypoxic challenge decreased the signal intensity (9% +/- 4%, p>0.05 and 15% +/- 3%, P < 0.05, respectively). The hypercapnic challenge, which causes vasodilation, resulted in a small increase in signal intensity in CE-fed rats (5% +/- 3%, P > 0.05) and a significant increase in the PF rats (15% +/- 4%, P < 0.05), again consistent with expected changes in deoxyhemoglobin. With all three physiological challenges, the degree of change was less in CE rats compared to PF controls. An acute dose of ethanol that causes vasodilation also increased signal intensity, with no significant difference between the two groups. The signal intensity changes seen with fMRI were highly correlated with pulse oximeter readings (r(2) = 0.95; P < 0.05). In conclusion, fMRI was shown to be a good noninvasive indicator of tissue deoxyhemoglobin changes in the liver. In addition, fMRI was able to detect subtle, early effects of CE administration (manifested as an impaired ability of the liver to respond adequately to oxygenation challenges), consistent with microvascular dysfunction.

Sensitive and real-time determination of H2O2 release from intact peroxisomes

Peroxisomes are essential and ubiquitous cell organelles having a key role in mammalian lipid and oxygen metabolism. The presence of flavine oxidases makes them an important intracellular source of H(2)O(2): an obligate product of peroxisomal redox reactions and a key reactive oxygen species. Peroxisomes proliferate in response to external signals triggered by peroxisome-proliferator-activated receptor signalling pathways. Peroxisome-derived oxidative stress as a consequence of this proliferation is increasingly recognized to participate in pathologies ranging from carcinogenesis in rodents to alcoholic and non-alcoholic steatosis hepatitis in humans. To date, no sensitive approach exists to record H(2)O(2) turnover of peroxisomes in real time. Here, we introduce a sensitive chemiluminescence method that allows the monitoring of H(2)O(2) generation and degradation in real time in suspensions of intact peroxisomes. Importantly, removal, as well as release of, H(2)O(2) can be assessed at nanomolar, non-toxic concentrations in the same sample. Owing to the kinetic properties of catalase and oxidases, H(2)O(2) forms fast steady-state concentrations in the presence of various peroxisomal substrates. Substrate screening suggests that urate, glycolate and activated fatty acids are the most important sources for H(2)O(2) in rodents. Kinetic studies imply further that peroxisomes contribute significantly to the beta-oxidation of medium-chain fatty acids, in addition to their essential role in the breakdown of long and very long ones. These observations establish a direct quantitative release of H(2)O(2) from intact peroxisomes. The experimental approach offers new possibilities for functionally studying H(2)O(2) metabolism, substrate transport and turnover in peroxisomes of eukaryotic cells.

Alcoholic liver disease

Research has substantiated the role of several mechanisms responsible for alcohol-induced hepatotoxicity. These mechanisms include: oxidative stress and lipid peroxidation; immunogenic processes initiated by formation of protein adducts of acetaldehyde, other aldehydes and 1-hydroxyethyl radicals; and activation of Kupffer cells by endotoxin and subsequent cascade of events that involved cytokines, chemokines, and adhesion molecules. Increasing evidence implicates enhanced intestinal permeability caused by alcohol ingestion as the culprit that leads to endotoxemia. While oxidative stress is important, the principal source of reactive oxygen species that causes alcohol-induced liver injury is hotly debated. Potential sources may include cytochrome P450IIE1, activated Kupffer cells, and mitochondrial electron transfer chain. Apoptosis is likely an important pathway that culminates in hepatocyte cell death. Abstinence, corticosteroids, and enteral nutrition remain the cornerstones in the treatment of alcoholic hepatitis. The efficacies of medications such as S-adenosylmethionine and pentoxifylline will need further confirmation by additional randomized trials before they can be recommended as standard therapies for alcoholic hepatitis.