The management of alcoholic liver disease

Ethanol-Induced Hepatic Ferroptosis Is Mediated by PERK-Dependent MAMs Formation: Preventive Role of Quercetin

SCOPE

Iron deposition is frequently observed in alcoholic liver disease (ALD), which indicates a potential role of ferroptosis in its development. This study aims to explore the effects of quercetin on ferroptosis in ALD and elucidates the underlying mechanism involving the formation of mitochondria-associated endoplasmic reticulum membranes (MAMs) mediated by protein kinase RNA-like endoplasmic reticulum kinase (PERK).

METHODS AND RESULTS

C57BL/6J mice are fed either a regular or an ethanol-containing liquid diet (with 28% energy form ethanol) with or without quercetin supplementation (100 mg kg-1 BW) for 12 weeks. Ethanol feeding or treatment induced ferroptosis in mice and AML12 cells, which is associated with increased MAMs formation and PERK expression within MAMs. Quercetin attenuates these changes and protects against ethanol-induced liver injury. The antiferroptotic effect of quercetin is abolished by ferroptosis inducers, but mimicked by ferroptosis inhibitors and PERK knockdown. The study demonstrates that PERK structure, rather than its kinase activity (transfected with the K618A site mutation that inhibits kinase activity-ΔK plasmid or protein C terminal knockout-ΔC plasmid of PERK), mediates the enhanced MAMs formation and ferroptosis during the ethanol exposure.

CONCLUSION

Quercetin ameliorates ethanol-induced liver injury by inhibiting ferroptosis via modulating PERK-dependent MAMs formation.

Improving Lipophagy by Restoring Rab7 Cycle: Protective Effects of Quercetin on Ethanol-Induced Liver Steatosis

Chronic alcohol consumption retards lipophagy, which contributes to the pathogenesis of liver steatosis. Lipophagy-related Rab7 has been presumed as a crucial regulator in the progression of alcohol liver disease despite elusive mechanisms. More importantly, whether or not hepatoprotective quercetin targets Rab7-associated lipophagy disorder is unknown. Herein, alcoholic fatty liver induced by chronic-plus-single-binge ethanol feeding to male C57BL/6J mice was manifested by hampering autophagosomes formation with lipid droplets and fusion with lysosomes compared with the normal control, which was normalized partially by quercetin. The GST-RILP pulldown assay of Rab7 indicated an improved GTP-Rab7 as the quercetin treatment for ethanol-feeding mice. HepG2 cells transfected with CYP2E1 showed similar lipophagy dysfunction when exposed to ethanol, which was blocked when cells were transfected with siRNA-Rab7 in advance. Ethanol-induced steatosis and autophagic flux disruption were aggravated by the Rab7-specific inhibitor CID1067700 while alleviated by transfecting with the Rab7Wt plasmid, which was visualized by immunofluorescence co-localization analysis and mCherry-GFP-LC3 transfection. Furthermore, TBC1D5, a Rab GTPase-activating protein for the subsequent normal circulation of Rab7, was downregulated after alcohol administration but regained by quercetin. Rab7 circulation retarded by ethanol and corrected by quercetin was further revealed by fluorescence recovery after photobleaching (FRAP). Altogether, quercetin attenuates hepatic steatosis by normalizing ethanol-imposed Rab7 turnover disorders and subsequent lipophagy disturbances, highlighting a novel mechanism and the promising prospect of quercetin-like phytochemicals against the crucial first hit from alcohol.

Repeated Administration of Kupffer Cells-Targeting Nanoantioxidant Ameliorates Liver Fibrosis in an Experimental Mouse Model

Kupffer cells are a major producer of reactive oxygen species and have been implicated in the development of liver fibrosis during chronic hepatitis in non-alcoholic steatohepatitis (NASH) and alcoholic steatohepatitis (ASH). We recently reported on the development of a polythiolated and mannosylated human serum albumin (SH-Man-HSA) that functions as a Kupffer cell-targeting nanoantioxidant. In this material, the albumin is mannosylated, which permits it to be taken up by mannose receptor C type 1 expressed on Kupffer cells, and is also polythiolated to have antioxidant activity. To clarify the anti-fibrotic property of this nanoantioxidant, we repeatedly administered SH-Man-HSA to a liver fibrosis mouse model that was induced by the repeated treatment of the concanavalin-A, which mimics the liver fibrosis observed in NASH and ASH. SH-Man-HSA dramatically improved the survival rate and suppressed liver fibrosis in the experimental model. In addition, SH-Man-HSA suppressed hepatic oxidative stress levels, thereby decreasing the numbers of apoptotic cells. In contrast, N-acetylcysteine, which contains the same thiol content as the SH-Man-HSA, failed to show a substantial therapeutic effect in these mice. The expression levels of inflammatory genes including epidermal growth factor module-containing mucin-like receptor (Emr-1/F4/80), Toll-like receptor-4 (TLR-4), high mobility group box-1 (HMGB-1), CC chemokine ligand-5 (CCL-5), tumor necrosis factor-α (TNF-α), CCL-2, interleukin-6 (IL-6), and IL-1β, as well as fibrotic (α-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-β), and Snail) and extracellular matrix genes (collagen, type Iα2 (Col1α2), matrix metalloproteinase-9 (MMP-9), and tissue inhibitor of metalloproteinase 1 (TIMP-1)), showed some decreasing trends by the SH-Man-HSA administration. These findings suggest that the repeated administration of the Kupffer cell-targeting nanoantioxidant, SH-Man-HSA, ameliorates liver fibrosis in mice by suppressing the level of oxidative stress and a portion of the inflammation, and has a potential therapeutic effect against NASH and ASH.

Characterization of natural melanin from Auricularia auricula and its hepatoprotective effect on acute alcohol liver injury in mice

This study characterized the natural melanin from Auricularia auricula and investigated its hepatoprotective effect on mice with acute alcoholic liver injury. The characterization of the melanin was analyzed based on elemental analysis, gel permeation chromatography (GPC), UV-visible spectroscopy (UV-visible), infrared spectrum (IR) and nuclear magnetic resonance spectra (NMR). To determine the liver protective effect of Auricularia auricula melanin, mice were administered with the melanin once daily for 3 weeks before ethanol induced liver injury. Biochemical parameters of liver function, histopathological sections, mRNA and protein expression of antioxidant enzyme were compared between mice with or without the melanin administered. Results showed that A. auricula melanin was a eumelanin and the average molecular weight was 48.99 kDa. The melanin can protect the mice from ethanol-induced liver injury by extending the duration of the righting reflex, and shortening the duration of the recovery. The liver index, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyl transpeptidase (γ-GT) and liver malondialdehyde (MDA) levels in mice treated with the melanin were significantly decreased. At the same time, the levels of liver alcohol dehydrogenase (ADH), and antioxidase such as catalase (CAT), and superoxide dismutase (SOD) were increased. Its protective effect may be related to the activation of nuclear factor E2-related factor 2 (Nrf2) and its downstream antioxidant enzymes such as glutamate cysteine ligase catalytic (GCLC), glutamate cysteine ligase modifier (GCLM), and NADP(H) quinine oxidoreductase 1 (NQO-1). These results suggested that A. auricula melanin may be an effective strategy to alleviate alcohol-induced liver damage.

Acute-on-chronic liver disease enhances phenylephrine-induced endothelial nitric oxide release in rat mesenteric resistance arteries through enhanced PKA, PI3K/AKT and cGMP signalling pathways

Acute-on-chronic liver disease is a clinical syndrome characterized by decompensated liver fibrosis, portal hypertension and splanchnic hyperdynamic circulation. We aimed to determine whether the alpha-1 agonist phenylephrine (Phe) facilitates endothelial nitric oxide (NO) release by mesenteric resistance arteries (MRA) in rats subjected to an experimental microsurgical obstructive liver cholestasis model (LC). Sham-operated (SO) and LC rats were maintained for eight postoperative weeks. Phe-induced vasoconstriction (in the presence/absence of the NO synthase –NOS- inhibitor L-NAME) and vasodilator response to NO donor DEA-NO were analysed. Phe-induced NO release was determined in the presence/absence of either H89 (protein kinase –PK- A inhibitor) or LY 294002 (PI3K inhibitor). PKA and PKG activities, alpha-1 adrenoceptor, endothelial NOS (eNOS), PI3K, AKT and soluble guanylate cyclase (sGC) subunit expressions, as well as eNOS and AKT phosphorylation, were determined. The results show that LC blunted Phe-induced vasoconstriction, and enhanced DEA-NO-induced vasodilation. L-NAME increased the Phe-induced contraction largely in LC animals. The Phe-induced NO release was greater in MRA from LC animals. Both H89 and LY 294002 reduced NO release in LC. Alpha-1 adrenoceptor, eNOS, PI3K and AKT expressions were unchanged, but sGC subunit expression, eNOS and AKT phosphorylation and the activities of PKA and PKG were higher in MRA from LC animals. In summary, these mechanisms may help maintaining splanchnic vasodilation and hypotension observed in decompensated LC.

The stellate cell system (vitamin A-storing cell system)

Past, present, and future research into hepatic stellate cells (HSCs, also called vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells, or Ito cells) are summarized and discussed in this review. Kupffer discovered black-stained cells in the liver using the gold chloride method and named them stellate cells (Sternzellen in German) in 1876. Wake rediscovered the cells in 1971 using the same gold chloride method and various modern histological techniques including electron microscopy. Between their discovery and rediscovery, HSCs disappeared from the research history. Their identification, the establishment of cell isolation and culture methods, and the development of cellular and molecular biological techniques promoted HSC research after their rediscovery. In mammals, HSCs exist in the space between liver parenchymal cells (PCs) or hepatocytes and liver sinusoidal endothelial cells (LSECs) of the hepatic lobule, and store 50-80% of all vitamin A in the body as retinyl ester in lipid droplets in the cytoplasm. SCs also exist in extrahepatic organs such as pancreas, lung, and kidney. Hepatic (HSCs) and extrahepatic stellate cells (EHSCs) form the stellate cell (SC) system or SC family; the main storage site of vitamin A in the body is HSCs in the liver. In pathological conditions such as liver fibrosis, HSCs lose vitamin A, and synthesize a large amount of extracellular matrix (ECM) components including collagen, proteoglycan, glycosaminoglycan, and adhesive glycoproteins. The morphology of these cells also changes from the star-shaped HSCs to that of fibroblasts or myofibroblasts.

Decompensated liver cirrhosis and neural regulation of mesenteric vascular tone in rats: role of sympathetic, nitrergic and sensory innervations

We evaluated the possible alterations produced by liver cholestasis (LC), a model of decompensated liver cirrhosis in sympathetic, sensory and nitrergic nerve function in rat superior mesenteric arteries (SMA). The vasoconstrictor response to electrical field stimulation (EFS) was greater in LC animals. Alpha-adrenoceptor antagonist phentolamine and P2 purinoceptor antagonist suramin decreased this response in LC animals more than in control animals. Both non-specific nitric oxide synthase (NOS) L-NAME and calcitonin gene related peptide (CGRP) (8-37) increased the vasoconstrictor response to EFS more strongly in LC than in control segments. Vasomotor responses to noradrenaline (NA) or CGRP were greater in LC segments, while NO analogue DEA-NO induced a similar vasodilation in both experimental groups. The release of NA was not modified, while those of ATP, nitrite and CGRP were increased in segments from LC. Alpha 1 adrenoceptor, Rho kinase (ROCK) 1 and 2 and total myosin phosphatase (MYPT) expressions were not modified, while alpha 2B adrenoceptor, nNOS expression and nNOS and MYPT phosphorylation were increased by LC. Together, these alterations might counteract the increased splanchnic vasodilation observed in the last phases of decompensated liver cirrhosis.

Hypoxia-inducible factors as molecular targets for liver diseases

Liver disease is a growing global health problem, as deaths from end-stage liver cirrhosis and cancer are rising across the world. At present, pharmacologic approaches to effectively treat or prevent liver disease are extremely limited. Hypoxia-inducible factor (HIF) is a transcription factor that regulates diverse signaling pathways enabling adaptive cellular responses to perturbations of the tissue microenvironment. HIF activation through hypoxia-dependent and hypoxia-independent signals have been reported in liver disease of diverse etiologies, from ischemia-reperfusion-induced acute liver injury to chronic liver diseases caused by viral infection, excessive alcohol consumption, or metabolic disorders. This review summarizes the evidence for HIF stabilization in liver disease, discusses the mechanistic involvement of HIFs in disease development, and explores the potential of pharmacological HIF modifiers in the treatment of liver disease.

Toxic damage increases angiogenesis and metastasis in fibrotic livers via PECAM-1

Excessive ethanol consumption is one of the main causes of liver fibrosis. However, direct effects of ethanol exposure on endothelial cells and their contribution to fibrogenesis and metastasis were not investigated. Therefore we analysed whether ethanol directly affects endothelial cells and if this plays a role during fibrogenesis and metastasis in the liver. Murine and human endothelial cells were exposed to ethanol for up to 72 hours. In vitro, effects on VEGF, HIF-1alpha, PECAM-1, and endothelial cell functions were analysed. In vivo, effects of continuous liver damage on blood vessel formation and metastasis were analysed by PECAM-1 immunohistochemistry. Ethanol increased HIF-1alpha and VEGF levels in murine and human endothelial cells. This resulted in enhanced intracellular signal transduction, and PECAM-1 expression as well as tube formation and wound healing. In vivo, toxic liver damage increased angiogenesis during fibrogenesis. Metastasis was also enhanced in fibrotic livers and located to PECAM-1 positive blood vessels compared to nonfibrotic mice. In conclusion, ethanol had strong effects on endothelial cells, which—at least in part—led to a profibrotic and prometastatic environment mediated by PECAM-1. Blockade of increased PECAM-1 expression could be a promising tool to inhibit fibrogenesis and metastasis in the liver.

Protective effects of dioscin against alcohol-induced liver injury

Our previous studies have shown that dioscin has protective effect against liver injury. However, the action of the compound against ethanol-induced liver injury is still unknown. In the present paper, ethanol-induced acute and chronic liver damage rat models were used, and the results showed that dioscin significantly alleviated liver steatosis, reduced the levels of alanine aminotransferase, aspartate aminotransferase, total triglyceride (TG), total cholesterol and malondialdehyde, and increased the levels of high-density lipoprotein, superoxide dismutase, glutathione and glutathione peroxidase. Transmission electron microscopy and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays showed that dioscin prevented mitochondrial ultrastructural alterations and apoptosis caused by ethanol. In addition, dioscin significantly inhibited ethanol-induced cytochrome P450 2E1 activation, down-regulated the levels of mitogen-activated protein kinases phosphorylation, inhibited the expressions of nuclear factor kappa B, glucose regulated protein 78, activating transcription factor 6 and alpha subunit of translation initiation factor 2 to attenuate oxidative damage, decreased the expressions of tumor necrosis factor alpha and interleukin-6, and down-regulated the expressions of apoptosis-related proteins including p53, caspase-3, caspase-9, poly (ADP-ribose)-polymerase and cytokeratin-18. Further investigation indicated that dioscin markedly increased the expressions of peroxisome proliferators-activated receptor α and its target genes including medium-chain acyl-CoA dehydrogenase, carnitine palmitoyl-CoA transferase I and acyl-CoA oxidase to advance fatty acid β-oxidation, up-regulated the expressions of acyl-CoA synthetase long-chain family member 1, acyl-CoA synthetase long-chain family member 5, alpha-aminoadipic semialdehyde dehydrogenase and acyl-CoA dehydrogenase to promote fatty acid metabolism, and down-regulated the expressions of glycerol-3-phosphate acyltransferase, diacylglycerol acyltransferase 1 and diacylglycerol acyltransferase 2 to accelerate TG synthesis. However, dioscin had no effects on the expressions of sterol regulatory element-binding protein-1c, fatty acid synthase, acetyl-CoA carboxylase 1 and stearoyl-CoA desaturase 1 associated with fatty acid synthesis. In conclusion, dioscin shows excellent protective effect against ethanol-induced liver injury through ameliorating ethanol-induced oxidative stress, mitochondrial function, inflammatory cytokine production, apoptosis and liver steatosis, which should be developed as a new drug for the treatment of ethanol-induced liver injury in the future.

Impact of PPAR-α induction on glucose homoeostasis in alcohol-fed mice

Alcohol consumption is a major cause of liver disease. It also associates with increased cardiovascular risk and Type 2 diabetes. ALD (alcoholic liver disease) and NAFLD (non-alcoholic fatty liver disease) share pathological features, pathogenic mechanisms and pattern of disease progression. In NAFLD, steatosis, lipotoxicity and liver inflammation participate to hepatic insulin resistance. The aim of the present study was to verify the effect of alcohol on hepatic insulin sensitivity and to evaluate the role of alcohol-induced steatosis and inflammation on glucose homoeostasis. C57BL/6J mice were fed for 20 days a modified Lieber-DeCarli diet in which the alcohol concentration was gradually increased up to 35% of daily caloric intake. OH (alcohol liquid diet)-fed mice had liver steatosis and inflammatory infiltration. In addition, these mice developed insulin resistance in the liver, but not in muscles, as demonstrated by euglycaemic-hyperinsulinaemic clamp and analysis of the insulin signalling cascade. Treatment with the PPAR-α (peroxisome-proliferator-activated receptor-α) agonist Wy14,643 protected against OH-induced steatosis and KC (Kupffer cell) activation and almost abolished OH-induced insulin resistance. As KC activation may modulate insulin sensitivity, we repeated the clamp studies in mice depleted in KC to decipher the role of macrophages. Depletion of KC using liposomes-encapsuled clodronate in OH-fed mice failed both to improve hepatic steatosis and to restore insulin sensitivity as assessed by clamp. Our study shows that chronic alcohol consumption induces steatosis, KC activation and hepatic insulin resistance in mice. PPAR-α agonist treatment that prevents steatosis and dampens hepatic inflammation also prevents alcohol-induced hepatic insulin resistance. However, KC depletion has little impact on OH-induced metabolic disturbances.

[Management of severe alcoholic hepatitis]

Severe alcoholic hepatitis is still associated with high mortality and presence of liver failure manifested by jaundice, coagulopathy and encephalopathy is a poor prognostic indicator. The management of these patients includes at first hand several supportive measures as treatment of alcohol withdrawal, administration of fluid and vitamins and admission to an intensive care unit in the unstable patient. Glucocorticoids have been since decades the most intensively studied therapy in alcoholic hepatitis and are effective in certain subgroups. Indication for such a therapy is usually defined on a Maddrey Discriminant Function > 32. The Lille score at day 7 is used to decide whether corticosteroid therapy should be stopped or continued for a 1 month course. Nutritional supplementation is also likely to be beneficial. The main progress in better understanding its pathophysiology has come from cytokine studies. Various proinflammatory cytokines such as tumor necrosis factor-alpha (TNFα) or interleukin-1 (IL-1) have been proposed to play a role in this disease. This advancement has recently led to pilot studies investigating anti-TNF drugs such as pentoxifylline, infliximab (anti-TNF antibody) or etanercept in the treatment of this disease. These studies revealed besides for pentoxifylline rather negative results. Despite this fact, targeting of certain cytokines such as IL-1 remains an attractive treatment concept for this devastating disorder in the future.

A novel canine model of portal vein stenosis plus thioacetamide administration-induced cirrhotic portal hypertension with hypersplenism

Current large animal models that could closely resemble the typical features of cirrhotic portal hypertension in human have not been well established. Thus, we aimed to develop and describe a reliable and reproducible canine cirrhosis model of portal hypertension. A total of 30 mongrel dogs were randomly divided into four groups: 1 (control; n = 5), 2 (portal vein stenosis [PVS]; n = 5], 3 (thioacetamide [TAA]; n = 5), and 4 (PVS plus TAA; n = 15). After 4-months modeling period, liver and spleen CT perfusion, abdominal CT scans, portal hemodynamics, gastroscopy, hepatic function, blood routine, the bone marrow, liver, and spleen histology were studied. The animals in group 2 (PVS) developed extrahepatic portosystemic collateral circulation, particularly esophageal varices, without hepatic cirrhosis and portal hypertension. Animals from group 3 (TAA) presented mild cirrhosis and portal hypertension without significant symptoms of esophageal varices and hypersplenism. In contrast, animals from group 4 (PVS + TAA) showed well-developed micronodular and macronodular cirrhosis, associated with significant portal hypertension and hypersplenism. The combination of PVS and TAA represents a novel, reliable, and reproducible canine cirrhosis model of portal hypertension, which is associated with the typical characteristics of portal hypertension, including hypersplenism.

Probiotics for patients with hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy is a disorder of brain function as a result of liver failure and/or portosystemic shunt. Both hepatic encephalopathy (clinically overt) and minimal hepatic encephalopathy (not clinically overt) significantly impair patient's quality of life and daily functioning and represent a significant burden on health care resources. Probiotics are live microorganisms, which when administered in adequate amounts may confer a health benefit on the host.

OBJECTIVES

To quantify the beneficial and harmful effects of any probiotic in any dosage, compared with placebo or no intervention, or with any other treatment for patients with any grade of acute or chronic hepatic encephalopathy as assessed from randomised trials.

SEARCH METHODS

We searched the The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, conference proceedings, reference lists of included trials and the WHO international clinical trials registry until April 2011 registry platform to identify new and ongoing trials.

SELECTION CRITERIA

We included randomised trials that compared probiotics in any dosage with placebo or no intervention, or with any other treatment in patients with hepatic encephalopathy.

DATA COLLECTION AND ANALYSIS

Three authors independently assessed the risk of bias of the included trials and extracted data on relevant outcomes, with differences resolved by consensus. We conducted random-effects model meta-analysis due to obvious heterogeneity of patients and interventions. A P value of 0.05 or less was defined as significant. Dichotomous outcomes are expressed as risk ratio (RR) and continuous outcomes as mean difference (MD) with 95% confidence intervals (CI).

MAIN RESULTS

We included seven trials of which 550 participants were randomised. Four of the seven trials compared a probiotic with placebo or no treatment in 245 participants, another trial compared a probiotic with lactulose in 40 participants , and the remaining two trials compared a probiotic with both placebo and lactulose in 265 participants. Each trial used different types of probiotics. Duration of administration of the experimental intervention varied from 10 days to 180 days. Two trials were industry funded, and five were unclear about origin of funding. All trials had high risk of bias. When probiotics were compared with no treatment, there was no significant difference in all-cause mortality (2 trials, 105 participants; 1/57 (2%) versus 1/48 (2%): RR 0.72; 95% CI 0.08 to 6.60), lack of recovery (4 trials, 206 participants; 54/107 (50%) versus 68/99 (69%): RR 0.72; 95% CI 0.49 to 1.05), adverse events (3 trials, 145 participants; 2/77 (3%) versus 6/68 (9%): RR 0.34; 95% CI 0.08 to 1.42), quality of life (1 trial, 20 participants contributed to the physical quality of life measurement, 20 participants contributed to the mental quality of life: MD Physical 0.00; 95% CI -5.47 to 5.47; MD Mental 4.00; 95% CI -1.82 to 9.82), or change of/or withdrawal from treatment (3 trials, 175 participants; 11/92 (12%) versus 7/83 (8%): RR 1.28; 95% CI 0.52 to 3.19). No trial reported sepsis or duration of hospital stay as an outcome. Plasma ammonia concentration was significantly lower for participants treated with probiotic at one month (3 trials, 226 participants: MD -2.99 μmol/L; 95% CI -5.70 to -0.29) but not at two months (3 trials, 181 participants: MD -1.82 μmol/L; 95% CI -14.04 to 10.41). Plasma ammonia decreased the most in the participants treated with probiotic at three months (1 trial, 73 participants: MD -6.79 μmol/L; 95% CI -10.39 to -3.19). When probiotics were compared with lactulose no trial reported all-cause mortality, quality of life, duration of hospital stay, or septicaemia. There were no significant differences in lack of recovery (3 trials, 173 participants; 47/87 (54%) versus 44/86 (51%): RR 1.05; 95% CI 0.75 to 1.47), adverse events (2 trials, 111 participants; 3/56 (5%) versus 6/55 (11%): RR 0.57; 95% CI 0.06 to 5.74), change of/or withdrawal from treatment at one month (3 trials, 190 participants; 8/95 (8%) versus 7/95 (7%): RR 1.10; 95% CI 0.40 to 3.03), plasma ammonia concentration (2 trials, 93 participants: MD -6.61 μmol/L; 95% CI -30.05 to 16.84), or change in plasma ammonia concentration (1 trial, 77 participants: MD 1.16 μmol/L; 95% CI -1.96 to 4.28).

AUTHORS' CONCLUSIONS

The trials we located suffered from a high risk of systematic errors ('bias') and high risk of random errors ('play of chance'). While probiotics appear to reduce plasma ammonia concentration when compared with placebo or no intervention, we are unable to conclude that probiotics are efficacious in altering clinically relevant outcomes. Demonstration of unequivocal efficacy is needed before probiotics can be endorsed as effective therapy for hepatic encephalopathy. Further randomised clinical trials are needed.

Angiogenesis in chronic liver disease and its complications

Nowadays, liver cancer, cirrhosis and other liver-related diseases are the fifth most common cause of mortality in the UK. Furthermore, chronic liver diseases (CLDs) are one of the major causes of death, which are still increasing year-on-year. Therefore, knowledge about the pathophysiology of CLDs and its complications is of uttermost importance. The goal of this review is to clarify the role of angiogenesis in the disease progression of various liver diseases. Looking closer at the pathophysiology of portal hypertension (PH), fibrosis, cirrhosis, non-alcoholic steatohepatitis (NASH) and hepatocellular carcinoma (HCC), we find that angiogenesis is a recurring factor in the disease progression. In PH, several factors involved in its pathogenesis, such as hypoxia, oxidative stress, inflammation and shear stress are potential mediators for the angiogenic response. The progression from fibrosis to cirrhosis, the end-point of CLDs, is distinguished by a prolonged inflammatory and fibrogenic process that leads to an abnormal angioarchitecture distinctive for cirrhosis. In several stages of NASH, a link might be made between the disease progression and hepatic microvasculature changes. HCC is one of the most vascular solid tumours in which angiogenesis plays an important role in its development, progression and metastasis. The close relationship between the progression of CLDs and angiogenesis emphasises the need for anti-angiogenic therapy as a tool for blocking or slowing down the disease progression. The fact that angiogenesis plays a pivotal role in CLDs gives rise to new opportunities for treating CLDs and its complications.

Cirrhosis decreases vasoconstrictor response to electrical field stimulation in rat mesenteric artery: role of calcitonin gene-related peptide

Our study determines alterations in the vasoconstrictor response elicited by electric field stimulation (EFS) in mesenteric arteries from cirrhotic rats treated with CCl(4), and how calcitonin gene-related peptide (CGRP) participates in this response. Vasoconstriction induced by EFS was analysed in the absence and presence of the CGRP receptor antagonist CGRP(8-37) in arterial segments from control and cirrhotic rats. The vasodilator response to exogenous CGRP was tested in both groups of rats, and the interference of the guanylate cyclase inhibitor ODQ or the K(ATP) channel blocker glibenclamide was analysed only in segments from cirrhotic rats. The vasodilator response to the K(ATP) channel opener pinacidil and to 8-bromo-cyclic GMP was tested. The K(ATP) currents were recorded using the patch-clamp technique. Expression of receptor activity-modifying protein 1 (RAMP1), calcitonin receptor-like receptor, Kir 6.1 and sulfonylurea receptor 2B (SUR2B) was also analysed. Release of CGRP and cGMP was measured. The EFS-elicited vasoconstriction was less in segments from cirrhotic rats. The presence of CGRP(8-37) increased the EFS-induced response only in segments from cirrhotic rats. The CGRP-induced vasodilatation was greater in segments from cirrhotic rats, and was inhibited by ODQ or glibenclamide. Both pinacidil and 8-bromo-cyclic GMP induced a stronger vasodilator response in segments from cirrhotic rats. Pinacidil induced greater K(ATP) currents in cirrhotic myocytes. Expression of RAMP1, calcitonin receptor-like receptor, Kir 6.1 and SUR2B was not modified by liver cirrhosis. Liver cirrhosis increased CGRP release, but did not modify cGMP formation. The decreased vasoconstrictor response to EFS in cirrhosis is mediated by increased vasodilator response to CGRP, as well as increased K(ATP) channel gating. This effect of CGRP may play a role in the splanchnic vasodilatation present in liver cirrhosis.

Pathological roles of bone marrow-derived stellate cells in a mouse model of alcohol-induced fatty liver

Chronic alcohol consumption activates hepatic stellate cells (HSCs) and causes fatty degeneration in the liver. However, the origin of HSCs and the mechanism of fatty changes of the liver have not been fully elucidated. Here, we examined the roles of bone marrow-derived cells (BMDCs) in a mouse model with chronic alcohol consumption. We performed bone marrow transplantation from transgenic mice expressing green fluorescence protein (GFP) to female wild-type and ROSA mice (B6.129S7-Gt 26Sor/J, transgenic mice expressing beta-galactosidase, beta-gal) and treated them with ethanol (EtOH) for 8 or 16 wk. GFP-expressing BMDCs increased in the liver with EtOH treatment in a time-dependent manner. In response to excess alcohol consumption, approximately 68% of the BMDCs became activated HSCs in that they expressed alpha-smooth muscle actin. Meanwhile, approximately 67% and approximately 66% of these BMDCs expressed Tnf-alpha and transforming growth factor (Tgf)-beta1, respectively, and the activities were further supported by the excessive mRNA expression of Tnf-alpha and Tgf-beta1 in RT-PCR, respectively. Cell fusion occurs between BMDCs and nonparenchymal cells but scarcely occurs between BMDCs and hepatocytes, demonstrated by double staining of beta-gal/GFP and further supported by the Y-chromosome staining. The EtOH withdrawal normalized most of the abnormalities produced by chronic alcohol consumption. These results indicate that excess alcohol consumption stimulates both the homing of HSCs from the bone marrow and their profibrogenic cytokine production in a mouse model of alcohol-induced fatty liver disease.

Comparison of three research models of portal hypertension in mice: macroscopic, histological and portal pressure evaluation

The characterization of mice models of portal hypertension (PHT) is lacking in the literature. Therefore, the aim of the present study was to make a histological approach during development of PHT in two models of cirrhosis with PHT compared with one model of isolated PHT. The model of isolated PHT was developed by partial portal vein ligation (PPVL). Two portal hypertensive cirrhotic mice models were developed either by common bile duct ligation (CBDL) or administration of carbon tetrachloride (CCl(4)) subcutaneously (twice weekly, 1 ml/kg). These models represent, respectively, a secondary biliary cirrhosis and alcoholic cirrhosis. Mice were killed at several time points to evaluate liver changes by histological and ultrastructural methods. A correlation was made with portal pressure measurements. Histology revealed the absence of fibrosis or cirrhosis in PPVL mice. They developed an isolated portal hypertension. After CBDL induction, the mice developed the characteristics of cirrhosis after 6 weeks, with simultaneous increase in portal pressures. Fifty percent of the mice had ascites at that time point. Sixteen weeks after administration of CCl(4), a micronodular cirrhotic aspect of the liver was seen associated with signs of portal hypertension. This is the first descriptive study of three widely used animal models in mice, allowing the study of pathophysiological changes in cirrhosis and portal hypertension. The PPVL in mice leads to a model of isolated portal hypertension. Secondary biliary cirrhosis developed after 6 weeks of common bile duct ligation in 50% of the mice that developed ascites. Subcutaneous injection of CCl(4) for 16 weeks induces cirrhosis and portal hypertension, without ascites. Moreover, the present study is the first description of a cirrhotic model in mice developed by subcutaneous injections of CCl(4). Well-described mice models will facilitate use of knock-out or transgenic mice and lead to a better understanding of the underlying molecular pathways in the field of portal hypertension and cirrhosis.

Treatment of severe forms of alcoholic hepatitis: where are we going?

Alcoholic hepatitis (AH) is observed in approximately 20% of heavy drinkers. The treatment of AH remains one of the main challenges to clinicians involved in the management of severe alcoholic liver disease. Corticosteroids improved the short-term survival of patients with severe AH. Nevertheless, the efficacy of corticosteroids is still considered controversial for some authors. Pentoxifylline may be considered an alternative to corticosteroids. Early identification of subjects with substantial risk of death according to the Lille model will improve management of patients suffering from severe AH and will aid in the design of future studies for alternative therapies. Alternative therapies are required to improve the prognosis of patients with a severe form of AH. Progress in understanding the pathogenesis of AH is opening up an exciting new era and is lending impetus to future evaluation of new drugs targeting the tumor necrosis factor pathways.

[MARS (Molecular Absorbent Recirculating System) as hepatic extracorporeal care in serious acute liver failure of alcoholic etiology]

Acute liver failure with criteria of seriousness and alcoholic etiology is a picture of worldwide distribution, with an elevated mortality, of approximately 50%, that requires admission to the ICU. Acute serious alcoholic hepatitis is defined by a Maddrey score value > 32 and/or spontaneous encephalopathy. Together with the classical treatment with corticosteroids and nutritional supplements, alcoholic abstinence and others such as anti-TNF therapy, we introduce MARS (Molecular Adsorbent recirculating System) as a extracorporeal liver assistance system with detoxification function, that is presented as a support measure that makes it possible to maintain the patient in good conditions until an organ becomes available or until the functional recovery of the native liver. In our case, MARS has shown some spectacular results and above all, results maintained over time, associated to the rest of the therapeutic measures characteristic of this disease.

Management strategies in alcoholic liver disease

Alcoholic liver disease (ALD) and its complications is still one of the most frequent causes of death in the Western world. Treatment modalities for both alcoholic steatohepatitis (ASH; the major inflammatory complication of ALD) and alcoholic liver cirrhosis are insufficient. Severe ASH is associated with a high mortality; although glucocorticoid treatment has been reported to improve survival, meta-analyses of clinical trials performed to date have failed to show a convincing benefit of such an approach. Most of the progress in understanding these diseases, especially ASH, has come from studies of cytokines. Various proinflammatory cytokines, such as tumor necrosis factor (TNF), have been proposed to have an important role in the pathophysiology of ALD and its complications. Pilot studies on the use of anti-TNF drugs, such as pentoxifylline or infliximab, in the treatment of ASH have now been performed with various levels of success. The treatment of patients with alcohol-related cirrhosis is mainly symptomatic and no therapies are currently available except orthotopic liver transplantation for end-stage liver disease. Independent of the stage of disease, abstinence from alcohol is the cornerstone of management. New treatment modalities for these diseases are eagerly awaited.

How to modulate inflammatory cytokines in liver diseases

Most acute and chronic liver diseases are characterized by inflammatory processes with enhanced expression of various pro- and anti-inflammatory cytokines in the liver. These cytokines are the driving force of many inflammatory liver disorders often resulting in fibrosis and cirrhosis. Severe alcoholic hepatitis is a prototypic tumor necrosis factor-alpha (TNF-alpha)-associated disease. This knowledge has recently led to pilot studies with promising results investigating specific anti-TNF drugs such as infliximab or etanercept in the treatment of this disease, although a recently performed controlled French study did show a potential detrimental effect of this approach. Anti-TNF treatment strategies might also improve chronic hepatitis C infection as shown by one controlled trial using etanercept administered subcutaneously for 24 weeks. Furthermore, several case reports suggest that TNF-alpha neutralization is not harmful to patients chronically infected with this virus. In contrast, neutralization of TNF-alpha worsens and might even be associated with fatalities in chronic hepatitis B infection. Anti-inflammatory cytokines such as interleukin-10 (IL-10) have also been tried in patients with chronic liver diseases. Whereas IL-10 administered to patients with chronic hepatitis C virus infection shows indeed anti-inflammatory effects in the liver, it seems to act as a proviral agent thereby limiting its clinical utility. Another cytokine with major anti-inflammatory potential is the adipokine adiponectin, as its administration is beneficial in many experimental models of liver injury. Interference with cytokine pathways and/or administration of anti-inflammatory cytokines will be of major interest in the future therapy of many liver diseases.

Vitamin A metabolic aspects and alcoholic liver disease

The liver is a strategic organ in the metabolism of macro and micronutrients; when its functioning is compromised, it may cause some change in the nutritional status of vitamin A. The purpose of this article is to review scientific evidence in literature on the liver metabolism of vitamin A, the role of ethanol and retinol interactions on hepatic morphology, besides the alterations in the metabolism of this vitamin in alcoholic liver disease. Data were collected from Medline database. The liver is the main organ responsible for the storage, metabolism and distribution of vitamin A to peripheral tissues. This organ uses retinol for its normal functioning such as cell proliferation and differentiation. This way, vitamin A deficiency seems to alter liver morphology. Patients with alcoholic liver disease have been found to have low hepatic levels of retinol in all stages of their disease. In alcoholic liver disease, vitamin A deficiency may result from decreased ingestion or absorption, reduction in retinoic acid synthesis or increased degradation. Long-term alcohol intake results in reduced levels of retinoic acid, which may promote the development of liver tumor. So, in chronic alcoholic subjects, vitamin A status needs to be closely monitored to avoid its deficiency and clinical effects, however its supplementation must be done with caution since the usual dose may be toxic for those who consume ethanol.

Differential liver sensitization to toll-like receptor pathways in mice with alcoholic fatty liver

Gut-derived, endotoxin-mediated hepatocellular damage has been postulated to play a crucial role in the pathogenesis of alcohol-induced liver injury in rodents. Endotoxins induce production of tumor necrosis factor alpha (TNF-alpha) by Kupffer cells via Toll-like receptor (TLR) 4 and contribute to liver injury. This study addressed the contribution of other TLRs and ligands to alcoholic fatty liver. C57Bl6/J mice were fed a modified Lieber-DeCarli diet. Serum aminotransferase measurements, histological analysis, and quantification of liver TNF-alpha and TLR1-9 messenger RNA (mRNA) were performed. The effect of TLR ligands on liver injury was assessed in vivo. Neomycin and metronidazole or diphenyleneiodonium sulfate (DPI) were administered to evaluate the role of gut bacteria and NADPH oxidase activity, respectively, in hepatic TLR expression. Enteral ethanol (EtOH) exposure induced steatosis and increased liver weight, aminotransferase levels, and expression of TLR1, 2, 4, 6, 7, 8, and 9 liver mRNA. Injection of lipoteichoic acid, peptidoglycan (PGN), lipopolysaccharide (LPS), loxoribine, and oligonudeotide containing CpG (ISS-ODN) increased TNF-alpha mRNA expression more in the livers of EtOH-fed mice than in control mice. PGN, LPS, flagellin, and ISS-ODN induced liver inflammatory infiltrate in EtOH-fed mice but not control mice. Addition of antibiotics reduced the severity of alcoholic fatty liver without affecting TLR expression, whereas daily DPI injections reduced the EtOH-mediated upregulation of TLR2, 4, 6, and 9 mRNA. In conclusion, EtOH-fed mice exhibited an oxidative stress dependent on upregulation of multiple TLRs in the liver and are sensitive to liver inflammation induced by multiple bacterial products recognized by TLRs.

A stable model of cirrhotic portal hypertension in the rat: thioacetamide revisited

BACKGROUND

Cirrhotic animal models are vital to investigate complications of chronic liver disease. We chronologically characterized the effect of thioacetamide, administrated orally and adapted weekly to weight changes, focusing on the optimal moment to obtain all typical features of portal hypertension and cirrhosis.

MATERIALS AND METHODS

Male Wistar rats, 200-250 g, were intoxicated for 6, 12 or 18 weeks (n = 8 per group), respectively, and compared with age-matched controls (n = 4 per group). An in-situ perfusion model was used to evaluate intrahepatic resistance and endothelial function. Splanchnic blood flow and portosystemic shunting were assessed by a perivascular flow probe.

RESULTS

Rats intoxicated for 6 or 12 weeks had no mortality and histologically showed hepatitis and advanced fibrosis, respectively. At 18 weeks, mortality was 16% (on a total of 56 animals) and only at that moment all animals showed homogenous macronodular cirrhosis with signs of high-grade hepatocellular dysplasia. Portal hypertension was present at 12 weeks (11 +/- 0.4 vs. 5.9 +/- 0.4 mmHg, P < 0.001), but was not associated with the hyperdynamic state until 18 weeks (12.1 +/- 0.8 vs. 5.6 +/- 0.5 mmHg, P < 0.001). At this latter time-point, we also observed increased intrahepatic resistance associated with endothelial dysfunction, hyperresponsiveness to vasoconstrictors, splanchnic hyperaemia and portosystemic shunting. These alterations were associated with increased systemic levels of nitrate/nitrite and thromboxane A(2).

CONCLUSION

Thioacetamide, adapted to weekly weight changes, leads to a homogenous, reproducible model of cirrhosis in the rat in 18 weeks, which is associated with all the typical characteristics of portal hypertension, including endothelial dysfunction.

Review article: non-biological liver support in liver failure

Liver failure, whether acute or acute-on-chronic, remains an important cause of morbidity and mortality. The lack of liver detoxification, metabolic and regulatory functions of the liver leads to life-threatening complications, such as renal failure, altered immune response, hepatic coma and systemic haemodynamic dysfunction, eventually culminating in multiorgan failure. Current medical therapy involves the management of the precipitating event and treatment of complications until the liver eventually recovers, leaving us with no other treatment options than transplantation if these attempts fail. However, the shortage in cadaveric organs and other transplant-related problems, have prompted the need for alternative methods to provide liver support. As liver failure is often potentially reversible, considerable effort has been invested in the development of liver support systems. Currently, most of the experience is available for non-biological support systems. They represent the focus of this review, which aims to define the goals of liver support, to describe the design of the different existing devices and to analyse the available data to determine their current status in the management of patients with liver failure.

Renal dysfunction in liver cirrhosis

Liver cirrhosis is an escalating health problem attributed to numerous causes, including an increase in alcohol consumption, morbid obesity and chronic viral hepatitis. The circulatory disturbances seen in advanced cirrhosis lead to the development of ascites, which often lead to progressive renal impairment or the development of hepatorenal syndrome. Furthermore, cirrhotic patients commonly experience clinical situations that predispose them to the development of pre-renal failure, such as dehydration, hypovolaemia, septic shock, or exposure to nephrotoxic drugs. This article provides an overview of the main causes of acute renal failure in liver cirrhosis and describes the current medical and nursing management.

Liver transplantation in alcoholic patients

Alcoholic liver disease is one of the most common causes of cirrhosis and indications for orthotopic liver transplantation in Europe and North America. The reluctance to transplant alcoholics stems in part from the view that alcoholics bear responsibility for their illness. There is also the perception that the alcoholic person is likely to relapse into alcohol use after transplantation and thereby damage the allograft. In this review, we considered the evaluation for and outcome of liver transplantation in alcoholics with special attention to the specific risks of alcohol relapse, to show that alcoholism should be considered like other co-morbid states rather than as a moral flaw.

4-Hydroxynonenal as a selective pro-fibrogenic stimulus for activated human hepatic stellate cells

BACKGROUND/AIMS

4-Hydroxynonenal (HNE) is a putative pro-fibrogenic product of oxidative stress able to elicit apoptosis and cytotoxicity in several cell types. This study has been performed to evaluate its 'in vivo' levels in injured liver and whether HNE may induce apoptosis and/or affect selected phenotypic responses in activated human hepatic stellate cells (HSC/MF).

METHODS/RESULTS

During the development of acute liver injury induced by CCl(4), liver tissue HNE levels were in the range 0.5-10 microM, as shown by high performance liquid chromatography analysis. Cultured human HSC/MF, developed cytotoxicity only if exposed to very high HNE concentrations (25-50 microM) without any sign of induction of classic, caspase-dependent apoptosis, as assessed by evaluating morphology and biochemical parameters of cell death. HNE, at non-cytotoxic doses, up-regulated procollagen type I and tissue inhibitor of metalloproteinases-1 gene expression and/or protein synthesis without significantly affecting chemotaxis (wound healing and haptotaxis assay), matrix metalloproteinases 1 and 2 mRNA expression and activity as well as basal DNA synthesis.

CONCLUSIONS

HNE, at concentrations compatible with those detected in vivo, does not elicit HSC/MF classic apoptosis but, rather, may act as a potent pro-fibrogenic stimulus for the expression of genes involved in excess extracellular matrix deposition and proposed as survival signals for HSC/MF.