Impact of alcohol on the ability of Kupffer cells to produce chemokines and its role in alcoholic liver disease

Oral administration of grape-derived nanovesicles for protection against LPS/D-GalN-induced acute liver failure

Although the exploration of the molecular mechanisms of Acute liver failure (ALF) is supported by a growing number of studies, the lack of effective therapeutic agents and measures indicates an urgent clinical need for the development of new drugs and treatment strategies. Herein, we focused on the treatment of ALF with grape-derived nanovesicles (GDNVs), and assessed its protective effects and molecular mechanisms against liver injury. In the mice model of ALF, prophylactic administration for three consecutive days and treatment with GDNVs after successful induction of ALF showed a significant reduction of ALT and AST activity in mouse serum, as well as a blockade of the release of inflammatory cytokines IL6, IL-1β and TNF-α. Treatment with GDNVs significantly prevented the massive apoptosis of hepatocytes caused by LPS/D-GalN and down-regulated the activation and expression of the mitochondrial apoptosis-related proteins p53, Caspase 9, Caspase 8, Caspase 3 and Bax. GDNVs downregulated the release of chemokines during the inflammatory eruption in mice and inhibited the infiltration of peripheral monocytes into the liver by inhibiting CCR2/CCR5. Moreover, the pro-inflammatory phenotype of macrophages in the liver was reversed by GDNVs. GDNVs further reduced the activation of NLRP3-related pathways, and treatment with GDNVs activated the expression of autophagy-related proteins Foxo3a, Sirt1 and LC3-II in the damaged mouse liver, inducing autophagy to occur. GDNVs could exert hepatoprotective and inflammatory suppressive functions by increasing nuclear translocation of Nrf2 and upregulating HO-1 expression against exogenous toxin-induced oxidative stress in the liver. In conclusion, these results demonstrate that GDNVs alleviate LPS/D-GalN-induced ALF and have the potential to be used as a novel hepatoprotective agent for clinical treatment.

O-alkyl and o-benzyl hesperetin derivative-1L attenuates inflammation and protects against alcoholic liver injury via inhibition of BRD2-NF-κB signaling pathway

Alcoholic liver injury (ALI) is a major risk factor for alcoholic liver disease, characterized by excessive inflammatory response and abnormal liver dysfunction. Previous studies have indicated that O-alkyl and o-benzyl hesperetin derivative-1 L (HD-1 L) has anti-inflammatory and hepato-protective effects in CCl₄-induced liver injury. However, its effect on ALI and underlying mechanism has not been elucidated. This study was designed to evaluate the protective effects of HD-1 L on alcoholic liver injury and reveal the underlying mechanisms. ALI model was established in male C57BL/6 J mice (aged 6-8 weeks) by Gao-Binge protocol. The mice were received different doses of HD-1 L (25 mg/kg, 50 mg/kg, 100 mg/kg) by daily intragastric administration, respectively. Liver function and inflammation were measured. Mechanism underlying the anti-inflammatory and hepato-protective effect of HD-1 L were studied in RAW264.7 cells. In alcoholic liver injury mice, HD-1 L effectively improved the liver pathology, and remarkably reduced the levels of alanine transaminase (ALT), aspartate transaminase (AST), triglyceride (TG) and total cholesterol (T-CHO) in serum. Moreover, HD-1 L markedly suppressed inflammation in vivo and inhibited the secretion of inflammatory factors in vitro. Our results showed that HD-1 L decreased the activity of Bromodomain-containing Protein 2 (BRD2) and inhibited expression of BRD2 in vivo and in vitro. Furthermore, HD-1 L further alleviated alcohol-induced inflammation after blocking BRD2 with inhibitor (JQ1) or BRD2 small interfering (si)-RNA in RAW264.7 cells. Besides, HD-1 L failed to effectively exert its anti-inflammatory effects after over expression of BRD2. In addition, HD-1 L significantly inhibited the phosphorylation and activation of NF-κB-P65 mediated by BRD2. In conclusion, HD-1 L alleviated liver injury and inflammation mainly by inhibiting BRD2-NF-κB signaling pathway, and HD-1 L may be a potential anti-inflammatory compound in treatment of alcoholic liver disease.

Super enhancer regulation of cytokine-induced chemokine production in alcoholic hepatitis

Alcoholic hepatitis (AH) is associated with liver neutrophil infiltration through activated cytokine pathways leading to elevated chemokine expression. Super-enhancers are expansive regulatory elements driving augmented gene expression. Here, we explore the mechanistic role of super-enhancers linking cytokine TNFα with chemokine amplification in AH. RNA-seq and histone modification ChIP-seq of human liver explants show upregulation of multiple CXCL chemokines in AH. Liver sinusoidal endothelial cells (LSEC) are identified as an important source of CXCL expression in human liver, regulated by TNFα/NF-κB signaling. A super-enhancer is identified for multiple CXCL genes by multiple approaches. dCas9-KRAB-mediated epigenome editing or pharmacologic inhibition of Bromodomain and Extraterminal (BET) proteins, transcriptional regulators vital to super-enhancer function, decreases chemokine expression in vitro and decreases neutrophil infiltration in murine models of AH. Our findings highlight the role of super-enhancer in propagating inflammatory signaling by inducing chemokine expression and the therapeutic potential of BET inhibition in AH treatment.

Chronic ethanol consumption compromises neutrophil function in acute pulmonary Aspergillus fumigatus infection

Chronic ethanol consumption is a leading cause of mortality worldwide, with higher risks to develop pulmonary infections, including Aspergillus infections. Mechanisms underlying increased susceptibility to infections are poorly understood. Chronic ethanol consumption induced increased mortality rates, higher Aspergillus fumigatus burden and reduced neutrophil recruitment into the airways. Intravital microscopy showed decrease in leukocyte adhesion and rolling after ethanol consumption. Moreover, downregulated neutrophil activation and increased levels of serum CXCL1 in ethanol-fed mice induced internalization of CXCR2 receptor in circulating neutrophils. Bone marrow-derived neutrophils from ethanol-fed mice showed lower fungal clearance and defective reactive oxygen species production. Taken together, results showed that ethanol affects activation, recruitment, phagocytosis and killing functions of neutrophils, causing susceptibility to pulmonary A. fumigatus infection. This study establishes a new paradigm in innate immune response in chronic ethanol consumers.

Alcoholism is a chronic disease that has many damaging effects on the body. Over long periods, excessive alcohol intake weakens the immune system, putting consumers at increased risk of getting lung infections such as pneumonia.

Some forms of pneumonia can be caused by the fungus Aspergillus fumigatus. This microbe does not tend to be a problem for healthy individuals, but it can be fatal for those with impaired immune systems. Here, Malacco et al. wanted to find out why excessive alcohol consumers are more prone to pneumonia.

To test this, the researchers used two groups of mice that were either fed plain water or water containing ethanol. After 12 weeks, both groups were infected with Aspergillus fumigatus. The results showed that alcohol-fed mice were more susceptible to the infection caused by strong inflammation of the lungs.

Normally, the immune system confronts a lung infection by activating a group of defense cells called neutrophils, which travel through the blood system to the infection site. Once in the right spot, neutrophils get to work by releasing toxins that kill the fungus. Malacco et al. discovered that after chronic alcohol consumption, neutrophils were less reactive to inflammatory signals and less likely to reach the lungs. They were also less effective in dealing with the infection. Neutrophil released fewer toxins and were thus less able to kill the microbial cells.

These findings demonstrate for the first time how alcohol can affect immune cells during infection and pave the way for new possibilities to prevent fatal lung infections in excessive alcohol consumers. A next step would be to identify how alcohol acts on other processes in the body and to find a way to modulate or even revert the changes it causes.

Pharmacological Inhibition of CCR2/5 Signaling Prevents and Reverses Alcohol-Induced Liver Damage, Steatosis, and Inflammation in Mice

Kupffer cell and macrophage (MØ) activation contributes to steatosis, inflammation, and fibrosis in alcoholic liver disease (ALD). We found increased frequency of MØ, T cells, and expression of C-C chemokine receptor type 2 (Ccr2) and C-C chemokine receptor type 5 (Ccr5) in the livers of patients with ALD, and increased circulating chemokines, C-C chemokine ligand types 2 (CCL2), and C-C chemokine ligand types 5 (CCL5) in patients with alcoholic hepatitis. We hypothesized that inhibition of CCL2 signaling with the dual CCR2/5 inhibitor, cenicriviroc (CVC), would attenuate ALD. In a mouse model of ALD, liver injury (alanine aminotransferase [ALT]) and steatosis were prevented by CVC whether administered as "prevention" throughout the alcohol feeding or as "treatment" started after the development of ALD. Alcohol-induced increases in early liver fibrosis markers (sirius red, hydroxyproline, and collagen-1) were normalized by both modes of CVC administration. We found that prevention and treatment with CVC reversed alcohol-related increases in liver mRNA and protein expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and CCL2. CVC administration regimens prevented the increase in infiltrating MØ (F4/80^lo CD11b^hi ) and reduced proinflammatory Ly6C^hi MØ in livers of alcohol-fed mice. CVC increased liver T-cell numbers and attenuated Il-2 expression without an effect on CD69⁺ or CD25⁺ T-cell expression. In vitro, CVC inhibited CCL2-induced increases in hepatocyte fatty acid synthase (Fasn) and adipose differentiation-related protein (Adrp), whereas it augmented acyl-coenzyme A oxidase 1 (Acox-1), proliferator-activated receptor gamma co-activator alpha (Pgc1α) and uncoupling protein 2 expression, suggesting mechanisms for attenuated hepatocyte steatosis. We found that CCL2 and CCL5 sensitized hepatocytes to lipopolysaccharide-induced liver injury (TNF-α, ALT, and lactate dehydrogenase release). Alcohol feeding induced apoptosis (poly ADP-ribose polymerase [PARP] and caspase-3 [CASP-3] cleavage) and pyroptosis (gasdermin D [GSDMD] cleavage) in livers, and CVC prevented both of these forms of cell death. Conclusion: Together, our data demonstrate preclinical evidence for CCR2/CCR5 inhibition with CVC as a potent intervention to ameliorate alcohol-induced steatohepatitis and liver damage.

Infection and Alcoholic Liver Disease

Acute and chronic alcohol use leads to an impaired immune response and dysregulated inflammatory state that contributes to a markedly increased risk of infection. Via shared mechanisms of immune-mediated injury, alcohol can alter the clinical course of viral infections such as hepatitis B, hepatitis C, and human immunodeficiency virus. These effects are most evident in patients with alcoholic hepatitis and cirrhosis. This article provides an overview of alcohol's effect on the immune system and contribution to the risks and outcomes of specific infectious diseases.

Increased Sensitivity to Binge Alcohol-Induced Gut Leakiness and Inflammatory Liver Disease in HIV Transgenic Rats

The mechanisms of alcohol-mediated advanced liver injury in HIV-infected individuals are poorly understood. Thus, this study was aimed to investigate the effect of binge alcohol on the inflammatory liver disease in HIV transgenic rats as a model for simulating human conditions. Female wild-type (WT) or HIV transgenic rats were treated with three consecutive doses of binge ethanol (EtOH) (3.5 g/kg/dose oral gavages at 12-h intervals) or dextrose (Control). Blood and liver tissues were collected at 1 or 6-h following the last dose of ethanol or dextrose for the measurements of serum endotoxin and liver pathology, respectively. Compared to the WT, the HIV rats showed increased sensitivity to alcohol-mediated gut leakiness, hepatic steatosis and inflammation, as evidenced with the significantly elevated levels of serum endotoxin, hepatic triglycerides, histological fat accumulation and F4/80 staining. Real-time PCR analysis revealed that hepatic levels of toll-like receptor-4 (TLR4), leptin and the downstream target monocyte chemoattractant protein-1 (MCP-1) were significantly up-regulated in the HIV-EtOH rats, compared to all other groups. Subsequent experiments with primary cultured cells showed that both hepatocytes and hepatic Kupffer cells were the sources of the elevated MCP-1 in HIV-EtOH rats. Further, TLR4 and MCP-1 were found to be upregulated by leptin. Collectively, these results show that HIV rats, similar to HIV-infected people being treated with the highly active anti-retroviral therapy (HAART), are more susceptible to binge alcohol-induced gut leakiness and inflammatory liver disease than the corresponding WT, possibly due to additive or synergistic interaction between binge alcohol exposure and HIV infection. Based on these results, HIV transgenic rats can be used as a surrogate model to study the molecular mechanisms of many disease states caused by heavy alcohol intake in HIV-infected people on HAART.

Alcoholic hepatitis: A comprehensive review of pathogenesis and treatment

Alcoholic hepatitis (AH) is an acute hepatic inflammation associated with significant morbidity and mortality. Current evidence suggests that the pathogenesis is the end result of the complex interplay between ethanol metabolism, inflammation and innate immunity. Several clinical scoring systems have been derived to predict the clinical outcomes of patients with AH; such as Child-Turcotte-Pugh score, the Maddrey discriminant function, the Lille Model, the model for end stage liver disease scores, and the Glasgow alcoholic hepatitis score. At present, Corticosteroids or pentoxifylline are the current pharmacologic treatment options; though the outcomes from the therapies are poor. Liver transplantation as the treatment of alcoholic hepatitis remains controversial, and in an era of organ shortage current guidelines do not recommend transplantation as the treatment option. Because of the limitations in the therapeutic options, it is no doubt that there is a critical need for the newer and more effective pharmacological agents to treat AH.

Cytochrome P4502E1 inhibitor, chlormethiazole, decreases lipopolysaccharide-induced inflammation in rat Kupffer cells with ethanol treatment

AIM

To investigate the role of Cytochrome P4502E1 in sensitizing Kupffer cells to lipopolysaccharide (LPS)-mediated inflammation after ethanol induction.

METHODS

Sprague-Dawley rats were fed a liquid ethanol diet, control diet or ethanol diet supplemented with CYP2E1 inhibitor, chlormethiazole (CMZ), for 4 weeks. Hepatic CYP2E1 protein, nuclear factor-kappa B (NF-κB) p65 protein and tumor necrosis factor (TNF)-α mRNA were measured. In vitro, isolated Kupffer cells from control rats were exposed to ethanol with different CMZ concentration; CYP2E1 expression and reactive oxygen species (ROS) generation were compared. The identified CMZ concentration was further utilized to evaluate the role of CYP2E1 on the sensitization of ethanol-induced Kupffer cell to LPS. The effect of LPS alone was tested in controlled Kupffer cells without ethanol. TNF-α, nuclear NF-κB p65 and cytoplasm IκB-α were monitored for all groups.

RESULTS

Ethanol feeding increased hepatic CYP2E1 level, nuclear accumulation of NF-κB p65 and TNF-α expression in rats. These changes were inhibited by CMZ supplementation. In cultured Kupffer cells, increased CYP2E1 content and ROS production by in vitro ethanol induction were dose-dependently inhibited by CMZ. Compared with LPS alone, the ethanol induction group produced significantly more TNF-α, nuclear NF-κB p65 and less cytoplasm IκB-α under LPS stimuli. CMZ abolished the effects of ethanol on LPS-stimulated NF-κB translocation and TNF-α generation in Kupffer cells.

CONCLUSION

In cultured Kupffer cell, using CMZ as inhibitor, ethanol-induced CYP2E1 overexpression was proved to contribute to the sensitization of Kupffer cells to LPS stimuli, with amplification of ROS production and activation of NF-κB, resulting in increased TNF-α production.

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.

An essential role for monocyte chemoattractant protein-1 in alcoholic liver injury: regulation of proinflammatory cytokines and hepatic steatosis in mice

The importance of chemokines in alcoholic liver injury has been implicated. The role of the chemokine, monocyte chemoattractant protein-1 (MCP-1), elevated in patients with alcoholic liver disease is not yet understood. Here, we evaluated the pathophysiological significance of MCP-1 and its receptor, chemokine (C-C motif) receptor 2 (CCR2), in alcoholic liver injury. The Leiber-DeCarli diet containing alcohol or isocaloric control diets were fed to wild-type (WT) and MCP-1-deficient knockout (KO) mice for 6 weeks. In vivo and in vitro assays were performed to study the role of MCP-1 in alcoholic liver injury. MCP-1 was increased in Kupffer cells (KCs) as well as hepatocytes of alcohol-fed mice. Alcohol feeding increased serum alanine aminotransferase in WT and CCR2KO, but not MCP-1KO, mice. Alcohol-induced liver steatosis and triglyceride were attenuated in alcohol-fed MCP-1KO, but high in CCR2KO mice, compared to WT, whereas serum endotoxin was high in alcohol-fed WT and MCP-1KO mice. Expression of liver proinflammatory cytokines tumor necrosis factor alpha, interleukin (IL)-1β, IL-6, KC/IL-8, intercellular adhesion molecule 1, and cluster of differentiation 68 was induced in alcohol-fed WT, but inhibited in MCP-1KO, mice independent of nuclear factor kappa light-chain enhancer of activated B cell activation in KCs. Oxidative stress, but not cytochrome P450 2E1, was prevented in chronic alcohol-fed MCP-1KO mice, compared to WT. Increased expression of peroxisome proliferator-activated receptor (PPAR)α and PPARγ was accompanied by nuclear translocation, DNA binding, and induction of fatty acid metabolism genes acyl coenzyme A oxidase and carnitine palmitoyltransferase 1A in livers of alcohol-fed MCP-1KO mice, compared to WT controls. In vitro assays uncovered an inhibitory effect of recombinant MCP-1 on PPARα messenger RNA and peroxisome proliferator response element binding in hepatocytes independent of CCR2.

CONCLUSION

Deficiency of MCP-1 protects mice against alcoholic liver injury, independent of CCR2, by inhibition of proinflammatory cytokines and induction of genes related to fatty acid oxidation, linking chemokines to hepatic lipid metabolism.

Zinc deprivation mediates alcohol-induced hepatocyte IL-8 analog expression in rodents via an epigenetic mechanism

Neutrophil infiltration caused by IL-8 production is a central mechanism in alcohol-induced hepatitis. This study was performed to examine if an epigenetic mechanism is involved in alcohol-induced IL-8 production. Mice were pair-fed an alcohol-containing liquid diet for 4 weeks. Alcohol exposure induced hepatitis as indicated by increased expression of keratinocyte-derived cytokine (mouse IL-8) and neutrophil infiltration. Alcohol exposure induced histone 3 hyperacetylation owing to inhibition of histone deacetylase (HDAC) in association with NF-κB activation. Cell culture studies showed that alcohol exposure induced IL-8 and cytokine-induced neutrophil chemoattractant-1 (CINC-1, rat IL-8) production in human VL-17A cells and rat H4IIEC3 cells, respectively, dependent on acetaldehyde production, oxidative stress, and zinc release. Zinc deprivation alone induced CINC-1 production and acted synergistically with lipopolysaccharide or tumor necrosis factor-α on CINC-1 production. Zinc deprivation induced histone 3 hyperacetylation at lysine 9 through suppression of HDAC activity. Zinc deprivation caused nuclear translocation of NF-κB, and reduced HDAC binding to NF-κB. Chromatin immunoprecipitation (ChIP) showed that zinc deprivation caused histone 3 hyperacetylation as well as increased NF-κB binding to the CINC-1 promoter. In conclusion, inactivation of HDAC caused by zinc deprivation is a novel mechanism underlying IL-8 up-regulation in alcoholic hepatitis.

Antigen-presenting cells under the influence of alcohol

The negative influence of alcohol (ethanol) and its metabolites on innate and adaptive immunity is well-recognized. Much attention has recently been focused on the impact of acute and chronic alcohol exposure on antigen-presenting cells (APC). In particular, insights have been gained into how the properties of human blood monocytes and rodent macrophages are influenced by alcohol in vitro and in vivo. Here, we review the impact of alcohol on various aspects of APC function and the underlying mechanisms, including its effects on intracellular signaling events. We also discuss new information regarding the influence of alcohol on various APC populations in the liver, a primary site of alcohol metabolism.

Cytokine and Chemokine Expression Associated with Steatohepatitis and Hepatocyte Proliferation in Rats Fed Ethanol via Total Enteral Nutrition

To determine the temporal relationship between alcohol-induced changes in cytokines and chemokines, development of liver pathology and stimulation of hepatocyte proliferation, male Sprague-Dawley rats were intragastrically fed low carbohydrate-containing ethanol (EtOH) diets via total enteral nutrition (TEN) for up to 49 d. Induction of EtOH metabolism and appearance of steatosis preceded development of oxidative stress, inflammation, and cell death. A transitory peak of tumor necrosis factor (TNFα) and interferon gamma (IFNγ) was observed at 14 d followed by reduced expression of TNFα, IFNγ and another Th1 cytokine IL-12 accompanied by reduced expression of the Th1 regulators T-bet and STAT4. After 35–49 d of EtOH, at a time when hepatocyte proliferation was stimulated, IL-12 returned to control values and a second peak of TNFα occurred. The Th2 cytokine IL-4 remained suppressed throughout the study and was accompanied by reductions in the Th2 regulator GATA3. There was no temporal effect of EtOH on expression of IL-6 or TGFβ. IL-5 and IL-13 mRNA were undetectable. Chemokine CXCL-2 expression increased progressively up to 35 d and preceded the appearance of inflammatory infiltrates. These data suggest that steatosis, increased ethanol metabolism, a transient induction of the innate immune response and suppression of Th2 responses were acute consequences of ethanol treatment and were followed by suppression of Th1 responses. However, the majority of necrosis, apoptosis and a late peak of TNFα only occurred after 6–7 weeks of ethanol, coincided with the appearance of inflammatory infiltrates and were associated with stimulation of hepatocyte proliferation.

Role of the proteasome in ethanol-induced liver pathology

The ubiquitin-proteasome system has come to be known as a vital constituent of mammalian cells. The proteasome is a large nonlysosomal enzyme that acts in concert with an 8.5 kDa polypeptide called ubiquitin and a series of conjugating enzymes, known as E1, E2 and E3, that covalently bind multiple ubiquitin moieties in a polyubiquitin chain to protein substrates in a process called ubiquitylation. The latter process targets protein substrates for unfolding and degradation by the 26S proteasome. This enzyme system specifically recognizes and degrades polyubiquitylated proteins, many of which are key proteins involved in cell cycle regulation, apoptosis, signal transduction, and antigen presentation. The 26S proteasome contains a cylinder-shaped 20S catalytic core that, itself, degrades proteins in an ATP- and ubiquitin-independent manner. The 20S form is actually the predominant enzyme form in mammalian cells. Proteolysis by the constitutive 20S proteasome is vital in removing oxidized, misfolded and otherwise modified proteins. Such degradation is critical as a means of cellular detoxification, as intracellular accumulation of damaged and misfolded proteins is potentially lethal. Studies have shown that inhibition of proteasome activity can lead to cell death. Ethanol and its metabolism cause partial inhibition of the proteasome. This leads to a number of pleiotropic effects that can affect a variety of cellular processes. This critical review describes important aspects of ethanol metabolism and its influence on the proteasome. The review will summarize recent findings on: (1) the interactions between the proteasome and the ethanol metabolizing enzyme, CYP2E1; (2) the dynamics of proteasome inhibition by ethanol in animal models and cultured cells; (3) ethanol-elicited suppression of proteasome activity and its effect on signal transduction; (4) The role of proteasome inhibition in cytokine production by liver cells; and (5) ethanol elicited suppression of peptide hydrolysis and the potential effects on antigen presentation. While the principal focus is on alcohol-induced liver injury, the authors foresee that the findings presented in this review will prompt further research on the role of this proteolytic system in other tissues injured by excessive alcohol consumption.

Pharmacological inhibition of the vitronectin receptor abrogates PDGF-BB-induced hepatic stellate cell migration and activation in vitro

BACKGROUND/AIMS

Activated hepatic stellate cells (HSC) play a central role in the development of liver fibrosis. Platelet-derived growth factor (PDGF)-BB and the integrin alphavbeta3 mediate mesenchymal cell migration and proliferation. However, their contribution and interaction during fibrogenic activation of HSC remains unclear. To this aim we investigated if PDFGF-BB and alphavbeta3 interact, and how far small molecular inhibitors of alphavbeta3 modulate PDGF-BB and serum-induced migration, proliferation and fibrogenic activation of HSC.

METHODS

Rat and human HSC were subjected to migration and proliferation assays in the presence or absence of a peptide or a nonpeptide alphavbeta3 inhibitor. Activation of mitogen-activated protein kinases (ERK1/2, p38), Akt, focal adhesion kinase (FAK), paxillin and beta3 integrin was evaluated by phospho-specific Western blotting. Fibrosis related transcripts were determined by quantitative real-time PCR.

RESULTS

PDGF-BB-stimulated HSC migration which was blocked dose-dependently by the alphavbeta3 antagonists, with complete inhibition at 10(-6)M. alphavbeta3 blockage did not affect cell viability or proliferation, while it decreased phosphorylation of FAK, paxillin, beta3 integrin and p38, but not of ERK1/2 or Akt. alphavbeta3 inhibition led to downregulation of certain profibrogenic transcripts, while it upregulated fibrolytic MMP-13 mRNA.

CONCLUSIONS

Inhibition of integrin alphavbeta3 leads to abrogation of migration of HSC stimulated with PDGF-BB and to an antifibrogenic gene expression pattern.

Serum concentrations of interleukin-8 in relation to different levels of alcohol consumption

Serum levels of interleukin-8 (IL-8) are increased in patients with alcoholic hepatitis and correlate with disease severity. The present study was aimed at investigating serum IL-8 levels in relation to different levels of alcohol consumption. Serum IL-8 was measured in (a) 459 individuals randomly selected from the general adult population, including 221 alcohol abstainers, 140 light drinkers (1-140 g/week), 53 moderate drinkers (141-280 g/week), and 45 heavy drinkers (>280 g/week), as well as (b) 137 alcoholics admitted to the hospital. The proportion of individuals with abnormally high (>10 pg/mL) IL-8 levels increased with alcohol use from 5.9% in abstainers to 10.7% in light, 13.2% in moderate, and 17.8% in heavy drinkers (P=0.004). This proportion was exceedingly high in alcoholics admitted to the hospital (70.1%, P<0.001 with respect to all other categories). Extremely high (>100 pg/mL) IL-8 levels were only observed among alcoholics, and were more frequent in females than in males (23.5% versus 9.7%, P=0.03) in spite of lower alcohol consumption among the former. These data indicate that the effect of alcohol on serum IL-8 levels begins with light-to-moderate drinking and is dose-dependent. Females may be more prone than males to develop extremely high IL-8 levels after heavy alcohol intake.

Distinct cellular responses differentiating alcohol- and hepatitis C virus-induced liver cirrhosis

BACKGROUND

Little is known at the molecular level concerning the differences and/or similarities between alcohol and hepatitis C virus induced liver disease. Global transcriptional profiling using oligonucleotide microarrays was therefore performed on liver biopsies from patients with cirrhosis caused by either chronic alcohol consumption or chronic hepatitis C virus (HCV).

RESULTS

Global gene expression patterns varied significantly depending upon etiology of liver disease, with a greater number of differentially regulated genes seen in HCV-infected patients. Many of the gene expression changes specifically observed in HCV-infected cirrhotic livers were expectedly associated with activation of the innate antiviral immune response. We also compared severity (CTP class) of cirrhosis for each etiology and identified gene expression patterns that differentiated ethanol-induced cirrhosis by class. CTP class A ethanol-cirrhotic livers showed unique expression patterns for genes implicated in the inflammatory response, including those related to macrophage activation and migration, as well as lipid metabolism and oxidative stress genes.

CONCLUSION

Stages of liver cirrhosis could be differentiated based on gene expression patterns in ethanol-induced, but not HCV-induced, disease. In addition to genes specifically regulating the innate antiviral immune response, mechanisms responsible for differentiating chronic liver damage due to HCV or ethanol may be closely related to regulation of lipid metabolism and to effects of macrophage activation on deposition of extracellular matrix components.

Proteasome inhibition attenuates hepatic injury in the bile duct-ligated mouse

Proteasome inhibition has recently been demonstrated to inhibit hepatic fibrogenesis in the bile duct-ligated (BDL) mouse by blocking stellate cell NF-kappaB activation. The effect of proteasome inhibition on liver injury, however, is unclear. Our aims were to assess the effect of the proteasome inhibitor bortezomib on liver injury in the BDL mouse. Liver injury was assessed in 7-day BDL mice treated with a single dose of bortezomib on day 4 after bile duct ligation. Despite NF-kappaB inhibition by bortezomib, liver injury and hepatocyte apoptosis were reduced in treated BDL mice. The antiapoptotic effect of bortezomib was likely mediated by an increase in hepatic cellular FLICE inhibitory protein (c-FLIP) levels, a potent antiapoptotic protein. Unexpectedly, numerous mitotic hepatocytes were observed in the bortezomib-treated BDL mice liver specimens. Consistent with this observation, PCNA immunoreactivity and cyclin A protein expression were also increased with bortezomib treatment. Bortezomib therapy was also associated with a decrease in numbers and activation of Kupffer cells/macrophages. In conclusion, these data suggest that the proteasome inhibitor bortezomib reduces hepatocyte injury in the BDL mouse by mechanisms associated with a reduction in hepatocyte apoptosis, a decrease in Kupffer cell/macrophage number and activation, and increased hepatocyte proliferation.

Molecular pathogenesis of alcohol-induced hepatic fibrosis

Alcohol abuse is a main cause of liver fibrosis and cirrhosis in the western world. Although the major mechanisms of fibrogenesis are independent of the origin of liver injury, alcoholic liver fibrosis features distinctive characteristics, including the pronounced inflammatory response of immune cells due to elevated gut-derived endotoxin plasma levels, increased formation of reactive oxygen species (ROS), ethanol-induced pericentral hepatic hypoxia or formation of cell-toxic and pro-fibrogenic ethanol metabolites (e.g., acetaldehyde or lipid oxidation products). These factors are together responsible for increased hepatocellular cell death and activation of hepatic stellate cells (HSCs), the key cell type of liver fibrogenesis. To date, removing the causative agent is the most effective intervention to prevent the manifestation of liver cirrhosis. A novel experimental approach in fibrosis therapy is the selective induction of cell death in HSCs. Substances such as gliotoxin, anandamide or antibody against tissue inhibitor of metalloproteinase (TIMP)-1 can selectively induce cell death in activated HSCs. These new results in basic science are encouraging for the search of new antifibrotic treatment.

Ethanol-induced liver injury: potential roles for egr-1

Chronic ethanol-induced liver injury follows a typical progression from its earliest stage of steatosis to more advanced injury, characterized by the development of inflammation, hepatocyte necrosis/apoptosis, fibrosis and finally cirrhosis. Kupffer cells, the resident macrophage in the liver, play a critical role in the progression of liver injury. Increased exposure of Kupffer cells to lipopolysaccharide (LPS) during chronic ethanol exposure leads to the production of a number of inflammatory mediators, including tumor necrosis factor alpha (TNF-alpha). Recent evidence indicates that in addition to increased exposure to LPS, Kupffer cells also develop an enhanced sensitivity to LPS after chronic ethanol feeding. We have recently identified early growth response-1 (Egr-1), an immediate-early gene transcription factor, as an important contributor to increased LPS-stimulated TNF-alpha secretion by Kupffer cells after chronic ethanol exposure. In other models of tissue injury, such as ischemia-reperfusion in the lung, Egr-1 acts as a coordinator of the complex response to stress. Here we review the literature regarding the role of EGR-1 in regulation of a number of genes implicated in each of the stages of chronic ethanol-induced liver injury. In addition to the critical role of Egr-1 in generating maximal LPS-stimulated TNF-alpha expression, Egr-1 also controls the expression of a number of inflammatory mediators, including intercellular adhesion molecule (ICAM)-1, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-2, as well as genes contributing to fibrosis, such as transforming growth factor (TFG)-beta1, platelet-derived growth factor PDGF-A chain and fibroblast growth factor (FGF). Understanding the contribution of Egr-1 to the expression of genes involved in the development of chronic ethanol-induced liver injury may lead to the development of improved therapies designed to prevent and/or reverse alcohol-induced liver injury.

The -159C/T polymorphism in the promoter region of the CD14 gene is associated with advanced liver disease and higher serum levels of acute-phase proteins in heavy drinkers

BACKGROUND

Innate inflammatory responses to endotoxin (lipopolysaccharide) contribute to the development of alcoholic liver disease (ALD). A single-nucleotide polymorphism (-159C/T) in the promoter region of the gene coding for CD14 (a lipopolysaccharide receptor) could be associated with the development of ALD. We sought too investigate the relationship between the CD14/-159C/T polymorphism and advanced ALD and acute-phase protein levels in heavy drinkers.

METHODS

A total of 138 heavy drinkers consecutively admitted to an Internal Medicine department were genotyped for the CD14/-159C/T polymorphism. Serum samples were analyzed for lipopolysaccharide-binding protein (LBP), soluble CD14 (sCD14), C-reactive protein (CRP), and immunoglobulin (Ig) A, IgG, and IgM. Patients with ascites or liver encephalopathy (n = 35) were classified as having advanced ALD.

RESULTS

After adjusting for potential confounding variables, the CD14/-159TT genotype was positively associated with advanced ALD (odds ratio, 2.99; 95% confidence interval, 1.09-8.24, p = 0.03) and serum LBP (p = 0.01) and sCD14 (p = 0.04) levels. The CD14/-159C/T polymorphism was not associated with serum levels of CRP, IgA, IgG, or IgM.

CONCLUSIONS

Our results support the notion that CD14/-159TT homozygous heavy drinkers have higher levels of the LPS-binding acute-phase proteins (LBP and sCD14) than do carriers of the CD14/-159C allele. Also, the CD14/-159TT genotype may be a risk factor for advanced ALD.

Severe alcoholic hepatitis with extremely high neutrophil count successfully treated by granulocytapheresis

We report a severe alcoholic hepatitis (SAH) patient with an extremely high WBC count, high serum bilirubin and low prothrombin time (PT) successfully treated with granulocytapheresis. After neutrophil-elastase inhibitor failed to reduce WBC count, methylprednisolone pulse therapy was performed. However, WBC count continued to be elevated to 97,190/microl (neutrophils 97.0%) despite improvement of total bilirubin and PT. After 5 sessions of granulocytapheresis and ulinastatin administration, increased serum IL-6, IL-8, neutrophil-elastase and WBC count gradually decreased. We could conclude that granulocytapheresis and ulinastatin can be very effective in reducing cytokines and neutrophil-elastase, and in improving the general status of SAH patients.

Gene by Environment Interaction: The -159C/T Polymorphism in the Promoter Region of the CD14 Gene Modifies the Effect of Alcohol Consumption on Serum IgE Levels

BACKGROUND

Serum IgE is increased in heavy drinkers. Endotoxin mediates most of the immunological alterations associated with heavy drinking. The -159C/T polymorphism in the promoter region of the gene encoding CD14 (an endotoxin receptor) is associated with serum IgE levels in different populations.

AIM

To investigate the possible interaction between alcohol intake and the -159C/T polymorphism in the promoter region of the CD14 gene for serum IgE levels.

METHODS

A total of 415 individuals (51.6% males, median age 50 years, range 18-92 years) were studied. A total of 140 individuals were alcohol abstainers, 112 were moderate drinkers (1-280 g/week), and 163 were heavy drinkers (>280 g/week). Main determinations included the CD14/-159C/T genotype, a panel of skin prick tests, total serum IgE, and specific serum IgE against common aeroallergens (Phadiatop test).

RESULTS

Heavy drinking was associated with increased total serum IgE values and with positive specific serum IgE to common aeroallergens, but the association was stronger in carriers of the CD14/-159C allele (either CC homozygotes or CT heterozygotes) than in CD14/-159TT homozygotes. Both additive and multiplicative interactions between heavy drinking and the CD14/-159C allele for total and specific serum IgE values was still present after adjusting for potential confounders. Neither alcohol consumption nor the CD14/-159 genotype was associated with skin prick test positivity.

CONCLUSIONS

The CD14/-159C/T polymorphism modifies the effect of alcohol consumption on serum IgE levels.

Perturbation of chemokine networks by gene deletion alters the reinforcing actions of ethanol

Microarray analysis of human alcoholic brain and cultured cells exposed to ethanol showed significant changes in expression of genes related to immune or inflammatory responses, including chemokines and chemokine receptors. To test the hypothesis that chemokines exhibit previously undiscovered pleiotropic effects important for the behavioral actions of ethanol, we studied mutant mice with deletion of the Ccr2, Ccr5, Ccl2 or Ccl3 genes. Deletion of Ccr2, Ccl2 (females) or Ccl3 in mice resulted in lower preference for alcohol and consumption of lower amounts of alcohol in a two-bottle choice test as compared with wild-type mice. Ethanol treatment (2.5 g/kg, i.p.) induced stronger conditioned taste aversion in Ccr2, Ccl2 or Ccl3 null mutant mice than in controls. Ccr2 and Ccr5 null mutant mice did not differ from wild-type mice in ethanol-induced loss of righting reflex (LORR), but mice lacking Ccl2 or Ccl3 showed longer LORR than wild-type mice. There were no differences between mutant strains and wild-type mice in severity of ethanol-induced withdrawal. Genetic mapping of chromosome 11 for the Ccl2 and Ccl3 genes (46.5 and 47.6 cM, respectively) revealed that an alcohol-induced LORR QTL region was contained within the introgressed region derived from 129/SvJ, which may cause some behavioral phenotypes observed in the null mice. On the contrary, known QTLs on Chr 9 are outside of 129/SvJ region in Ccr2 and Ccr5 (71.9 and 72.0 cM, respectively) null mutant mice. These data show that disruption of the chemokine network interferes with motivational effects of alcohol.

A review of Silybum marianum (milk thistle) as a treatment for alcoholic liver disease

Silybum marianum (milk thistle) and its derivatives have been used for centuries for the treatment of liver disease. This review focuses exclusively on published literature pertaining to the potential use of Silybum marianum or its derivatives for the treatment of alcoholic liver disease. Clinical studies have varied greatly in quality, with the majority limited by inadequate sample size, lack of uniformity in the population treated, lack of standardization of preparations studied, variability in dosing regimens, inconsistent outcome measures, and lack of information on concurrent use of alcohol during the treatment period. While Silybum marianum and its derivatives appear to be safe and the available evidence on the mechanisms of action appears promising, there are currently insufficient data from well-conducted clinical trials to recommend their use in patients with alcoholic liver disease.

Animal models and their results in gastrointestinal alcohol research

Alcohol-induced diseases of the gastrointestinal tract play an important role in clinical gastroenterology. However, the precise pathophysiological mechanisms are still largely unknown. Alcohol research depends essentially on animal models due to the fact that controlled experimental studies of ethanol-induced diseases in humans are unethical. Animal models have already been successfully applied to disclose and analyze molecular mechanisms in alcohol-induced diseases, partially by using knockout technology. Because of a lack of transferability of some animal models to the human condition, results have to be interpreted cautiously. For some alcohol-related diseases like chronic alcoholic pancreatitis, the ideal animal model does not yet exist. Here we provide an overview of the most commonly used animal models in gastrointestinal alcohol research. We will also briefly discuss the findings based on animal models as well as the current concepts of pathophysiological mechanisms involved in acute and chronic alcoholic damage of the esophagus, stomach, small and large intestine, pancreas and liver.

Ethanol blocks leukocyte recruitment and endothelial cell activation in vivo and in vitro

Immune system impairment and increased susceptibility to infection among alcohol abusers is a significant but not well-understood problem. We hypothesized that acute ethanol administration would inhibit leukocyte recruitment and endothelial cell activation during inflammation and infection. Using LPS and carrageenan air pouch models in mice, we found that physiological concentrations of ethanol (1-5 g/kg) significantly blocked leukocyte recruitment (50-90%). Because endothelial cell activation and immune cell-endothelial cell interactions are critical regulators of leukocyte recruitment, we analyzed the effect of acute ethanol exposure on endothelial cell activation in vivo using the localized Shwartzman reaction model. In this model, ethanol markedly suppressed leukocyte accumulation and endothelial cell adhesion molecule expression in a dose-dependent manner. Finally, we examined the direct effects of ethanol on endothelial cell activation and leukocyte-endothelial cell interactions in vitro. Ethanol, at concentrations within the range found in human blood after acute exposure and below the levels that induce cytotoxicity (0.1-0.5%), did not induce endothelial cell activation, but significantly inhibited TNF-mediated endothelial cell activation, as measured by adhesion molecule (E-selectin, ICAM-1, VCAM-1) expression and chemokine (IL-8, MCP-1, RANTES) production and leukocyte adhesion in vitro. Studies exploring the potential mechanism by which ethanol suppresses endothelial cell activation revealed that ethanol blocked NF-kappaB nuclear entry in an IkappaBalpha-dependent manner. These findings support the hypothesis that acute ethanol overexposure may increase the risk of infection and inhibit the host inflammatory response, in part, by blocking endothelial cell activation and subsequent immune cell-endothelial cell interactions required for efficient immune cell recruitment.

Limited role for CXC chemokines in the pathogenesis of alpha-naphthylisothiocyanate-induced liver injury

Alpha-naphthylisothiocyanate (ANIT) is a hepatotoxin that causes severe neutrophilic inflammation around portal tracts and bile ducts. The chemotactic signals that provoke this inflammatory response are unknown. In this study, we addressed the possibility that ANIT upregulates CXC chemokines in the liver and that these compounds mediate hepatic inflammation and tissue injury after ANIT treatment. Mice treated with a single dose of ANIT (50 mg/kg) exhibited rapid hepatic induction of the CXC chemokine macrophage inflammatory protein-2 (MIP-2). MIP-2 derived primarily from hepatocytes, with no apparent contribution by biliary cells. In ANIT-treated mice, the induction of MIP-2 coincided with an influx of neutrophils to portal zones; this hepatic neutrophil recruitment was suppressed by 50% in mice that lack the receptor for MIP-2 (CXCR2(-/-)). Interestingly, despite their markedly reduced degree of hepatic inflammation, CXCR2(-/-) mice displayed just as much hepatocellular injury and cholestasis after ANIT treatment as wild-type mice. Moreover, after long-term exposure, ANIT CXCR2(-/-) mice developed liver fibrosis that was indistinguishable from that in wild-type mice. In summary, our data show that CXC chemokines are responsible for some of the hepatic inflammation that occurs in response to ANIT but that these compounds are not essential to the pathogenesis of either acute or chronic ANIT hepatotoxicity.

Pathomorphological study on location and distribution of Kupffer cells in hepatocellular carcinoma

AIM: To clarify the location and distribution of Kupffer cells in hepatocellular carcinoma (HCC), and to investigate their role in hepatocarcinogenesis.

METHODS: Kupffer cells were immunohistochemically stained by streptavadin-peroxidase conjugated method (S-P). The numbers of Kupffer cells in cancerous, para-cancerous and adjacent normal liver tissues of 48 HCCs were comparatively examined.

RESULTS: The mean number of Kupffer cells in cancerous, para-cancerous and adjacent normal liver tissues was 12.7 ± 6.8, 18.1 ± 8.2 and 18.9 ± 7.9 respectively. The number of Kuppfer cells in cancerous tissues was significantly lower than that in para-cancerous tissues (t = 2.423, P < 0.05) and adjacent normal liver tissues (t = 2.521, P < 0.05). As tumor size increased, the number of Kupffer cells in cancerous tissues significantly decreased (F = 4.61, P < 0.05). Moreover, there was also a significant difference in the number of Kupffer cells among well-differentiated, moderately-differentiated and poorly-differentiated cases(F = 4.49, P < 0.05).

CONCLUSION: This study suggests that decrease of Kupffer cells in HCCs may play an important role in the carcinogenesis of HCC, the number of Kupffer cells in HCC is closely related to the size and differentiation grade of the tumor.

Animal models in gastrointestinal alcohol research-a short appraisal of the different models and their results

Alcohol-related diseases of the gastrointestinal tract play an important role in clinical gastroenterology. However, the mechanisms and pathophysiology underlying the effects of ethanol on the organs of the digestive tract are not yet completely understood. Animal models represent an essential tool for investigating alcohol-related diseases because they give researchers the opportunity to use methods that cannot be used in humans, such as knockout technology. However, there is still a need for new animal models resembling the human condition, since for some alcohol-related diseases such as chronic alcoholic pancreatitis, the ideal animal model does not yet exist. In this chapter, we provide an overview of the most commonly used animal models in gastrointestinal alcohol research. We will also briefly discuss the current concepts of the pathophysiological mechanisms involved in acute and chronic alcoholic damage of the oesophagus, stomach, small and large intestine, pancreas and liver.

Iron-induced oxidant stress in alcoholic liver fibrogenesis

Iron is an essential micronutrient. However, because human beings have no means to control iron excretion, excess iron, regardless of the route of entry, accumulates in parenchymal organs and threatens cell viability. Indeed, when iron-buffering capability is overwhelmed, oxidative stress-induced cell damage and fibrogenesis may arise, mainly in the liver, the main storage site for iron in the body. Results of recent studies have clearly shown that these pathologic events are induced by iron-generated reactive oxygen species and lipid peroxidation by-products. Hepatic fibrosis, characterized by excessive accumulation of extracellular matrix components in the liver, is a dynamic process, from chronic liver damage to end-stage liver cirrhosis. Iron-induced oxidant stress is involved in this process (1) as the primary cause of parenchymal cell necrosis or (2) as activator of cells that are effectors [e.g., hepatic stellate cells, (myo)fibroblasts] or key mediators (e.g., Kupffer cells) of hepatic fibrogenesis (or through both mechanisms). Beyond their effect as direct cytotoxic agents, iron and free radicals may trigger increased synthesis of collagen in myofibroblast-like cells as well as activate granulocytes and Kupffer cells, resulting in an increased formation of cytokines and eicosanoids and further reactive oxygen species. This may constitute a cascade of amplifying loops, which perpetuate the fibrogenic process. The fibrogenic potential of iron is even more dramatic when iron acts in concert with other hepatotoxins such as alcohol. In this instance, even if tissue iron levels are only slightly elevated, the toxic effect of alcohol or its metabolites may be amplified and propagated with rapid acceleration of the liver disease. At the molecular level, the presence of catalytically active "free iron" may (1) contribute directly to the hepatotoxicity of alcohol or (2) enhance the generation of cytokine and fibrogenic mediators from resident Kupffer cells (or be involved in both ways). A challenge for future research is to develop therapeutic tools able to block "redox-active" free iron in the cell.

Synthesis of endotoxin receptor CD14 protein in Kupffer cells and its role in alcohol-induced liver disease

AIM: To observe the synthesis of endotoxin receptor CD14 protein and its mRNA expression in Kupffer cells (KCs), and evaluate the role of CD14 in the pathogenesis of liver injury in rats with alcohol-induced liver disease (ALD).

METHODS: Twenty-eight Wistar rats were divided into two groups: ethanol-fed group and control group. Ethanol-fed group was fed ethanol (dose of 5-12g·kg·d^-1) and control group received dextrose instead of ethanol. Two groups were sacrificed at 4 wk and 8 wk, respectively. KCs were isolated and the synthesis of CD14 protein and its mRNA expression in KCs were determined by flow cytometric analysis (FCM) or the reverse transcription polymerase chain reaction (RT-PCR) analysis. The levels of plasma endotoxin and alanine transaminase (ALT) were measured by Limulus Amebocyte Lysate assay and standard enzymatic procedures respectively, and the levels of plasma tumor necosis factor (TNF)-α and interleukin (IL)-6 were both determined by ELISA. The liver pathology change was observed under light and electric microscopy.

RESULTS: In ethanol-fed group, the percentages of FITC-CD14 positive cells were 76.23% and 89.42% at 4 wk and 8 wk, respectively. Compared with control group (4.45% and 5.38%), the difference was significant (P < 0.05). The expressions of CD14 mRNA were 7.56 ± 1.02 and 8.74 ± 1.37 at 4 wk and 8 wk, respectively, which were significantly higher compared with the control group (1.77 ± 0.21 and 1.98 ± 0.23) (P < 0.05). Plasma endotoxin levels at 4 wk and 8 wk increased significantly in ethanol-fed group (129 ± 21 ng·L^-1 and 187 ± 35 ng·L^-1) than those in control rats (48 ± 9 ng·L^-1 and 53 ± 11 ng·L^-1)(P < 0.05). Mean values of plasma ALT levels increased dramatically in ethanol-fed rats (112 ± 15 IU/L and 147 ± 22 IU/L) than those in the control animals (31 ± 12 IU/L and 33 ± 9 IU/L) (P < 0.05). In ethanol-fed rats, the levels of TNF-α were 326 ± 42 ng·L^-1 and 402 ± 51 ng·l^-1 at 4 wk and 8 wk, respectively which were significantly higher than those in control group (86 ± 12 ng·L^-1 and 97 ± 13 ng·L^-1) (P < 0.05). The levels of IL-6 were 387 ± 46 ng·L^{- 1} and 413 ± 51 ng·L^-1, which were also higher than control group (78 ± 11 ng·L^-1 and 73 ± 10 ng·L^-1) (P < 0.05). In liver section from ethanol-fed rats, there were marked pathological changes including steatosis, cell infiltration and necrosis. No marked pathological changes were seen in control group.

CONCLUSION: Ethanol administration led to a significant synthesis of endotoxin receptor CD14 protein and its gene expression in KCs, which maybe result in the pathological changes of liver tissue and hepatic functional damages.

Human immunodeficiency virus type 1 gp120 and ethanol coexposure in rat organotypic brain slice cultures: Curtailment of gp120-induced neurotoxicity and neurotoxic mediators by moderate but not high ethanol concentrations

Human immunodeficiency virus type 1 (HIV-1) envelope protein gp120, implicated with other retroviral proteins in acquired immunodeficiency syndrome (AIDS)-related dementia, causes neuronal degeneration by inciting cascades of neurotoxic mediators from glia. It also may facilitate neuronal glutamate (N-methyl-D-aspartate, NMDA) receptor-mediated excitotoxicity by interacting at the glycine coagonist site. The authors reported that preconditioning rat organotypic hippocampal-cortical slice cultures subchronically with ethanol at concentrations occurring during moderate drinking (20 to 30 mM) prevented gp120's induction of neurotoxic mediators and intracellular calcium, as well as neuronal death. The authors now find that the acute copresence of ethanol in moderate as opposed to high concentrations similarly blocks the retroviral protein's neurotoxic effects in brain slice cultures, assessed with lactate dehydrogenase (LDH) release and propidium iodide (PI) labeling. As with ethanol preconditioning, neuroprotection against gp120 by moderate ethanol coexposure appears secondary to abrogation of the retroviral protein's early induction of arachidonic acid (AA), glutamate, and superoxide (but not nitric oxide) elevations/release. Additionally, experiments indicate that 30 mM ethanol is sufficient to inhibit the NMDA receptor, particularly in the presence of added glycine, thus hindering potential direct neuronal stimulation by gp120. However, in contrast to moderate ethanol, 100 mM ethanol, a concentration tolerated only in chronic alcoholics, potentiates gp120-dependent neurotoxicity (PI labeling) in the hippocampal CA1 region, augments LDH release, and fails to curtail gp120's actions on AA, glutamate, and superoxide-but does suppress nitric oxide induction. The results indicate dominant roles for AA, superoxide, and glutamate-mediated oxidative stress in gp120's neurotoxic mechanism, but perhaps a less important role for NMDA receptor stimulation, which would be constrained at both ethanol concentrations employed. We suggest that ethanol's concentration-dependent, two-edged sword behavior could alter the development of dementia in HIV-1-infected individuals during social consumption or abuse. Further studies are needed to elucidate the differing apparently glial effects of the two concentrations of ethanol.

Pathogenic interactions between alcohol and hepatitis C

Alcohol is the most commonly abused substance in the United States, and alcohol abuse leads to alcoholic liver disease, a long recognized major public health concern. The high prevalence of chronic hepatitis C virus (HCV) infection, along with the clinical observation that HCV infection is common in alcoholic patients presenting with liver disease, has directed attention to the interaction between alcohol and HCV infection. Clinical studies have identified alcohol use as an independent risk factor for progression of fibrosis in chronic HCV infection. Experimental evidence suggests additive inhibitory effects between HCV and alcohol on antiviral immune responses. In addition, specific pathways have been identified by which HCV core protein and alcohol interact to activate hepatocytes. Nonspecific inflammatory cell recruitment and proinflammatory cytokine activation have also been implicated in both alcohol- and HCV-induced liver diseases. Further investigation of these and other pathways by which alcohol and HCV interact should unravel the mechanisms that accelerate the progression of liver disease.

Role of ICAM-1 in chronic ethanol consumption-enhanced liver injury after gut ischemia-reperfusion in rats

Intercellular adhesion molecule-1 (ICAM-1) has been implicated in the hepatic microvascular dysfunction elicited by gut ischemia-reperfusion (I/R). Although the effects of chronic ethanol (EtOH) consumption on the liver are well known, it remains unclear whether this condition renders the hepatic microcirculation more vulnerable to the deleterious effects of gut and/or hepatic I/R. The objectives of this study were to determine whether chronic EtOH consumption alters the severity of gut I/R-induced hepatic microvascular dysfunction and hepatocellular injury and to determine whether ICAM-1 contributes to this response. Male Wistar rats, pair fed for 6 wk a liquid diet containing EtOH or an isocaloric control diet, were exposed to gut I/R. Intravital video microscopy was used to monitor leukocyte recruitment in the hepatic microcirculation, the number of nonperfused sinusoids (NPS), and plasma concentrations of endotoxin and tumor necrosis factor-alpha. Plasma alanine aminotransferase (ALT) levels were measured 6 h after the onset of reperfusion. In control rats, gut I/R elicited increases in the number of stationary leukocytes, NPS, and plasma endotoxin, tumor necrosis factor-alpha, and ALT. In EtOH-fed rats, the gut I/R-induced increases in NPS and leukostasis were blunted in the midzonal region, while exaggerated leukostasis was noted in the pericentral region and terminal hepatic venules. Chronic EtOH consumption also enhanced the gut I/R-induced increase in plasma endotoxin and ALT. The exaggerated responses to gut I/R normally seen in EtOH-fed rats were largely prevented by pretreatment with a blocking anti-ICAM-1 monoclonal antibody. In conclusion, these results suggest that chronic EtOH consumption enhances gut I/R-induced hepatic microvascular dysfunction and hepatocellular injury in the pericentral region and terminal hepatic venules via an enhanced hepatic expression of ICAM-1.

Neutrophilic infiltration in alcoholic hepatitis

Leukocyte infiltration in the liver is one of the most important features of alcoholic liver disease. However, in alcoholic hepatitis, the role of polymorphonuclear neutrophils (PMNs) in liver injury still remains to be fully elucidated. Furthermore, the migration of PMNs and their presence in the liver during alcoholic hepatitis have not been fully investigated. Up-regulation of chemokine secretion and adhesion molecule expression on effector cells (i.e., PMNs) and target cells (i.e., hepatocytes) are important factors in neutrophilic infiltration of the liver. The CXC chemokines--that is, interleukin (IL)-8 (in human beings), cytokine-induced neutrophil chemoattractant (CINC) (in rats), and KC (in mice)--are proneutrophilic agents. They are up-regulated during chronic--that is, several years of--alcohol use in human beings and in up to 30 weeks in experimental models of ethanol intoxication in mice and rats. Up-regulation of these chemokines in the circulation and tissues is also associated with enhanced neutrophilic infiltration in the liver. In the rat, the up-regulation of CXC chemokine production is time dependent. For example, after 16 weeks of feeding, up-regulation of CXC chemokine is observed, whereas after 32 weeks, CC chemokines are enhanced. Concomitantly, selective migration of PMNs and mononuclear cells is observed. In another model, in which both CXC and CC chemokines were enhanced after chronic ethanol use for 12 weeks in mice, neutrophilic and mononuclear/lymphocytic infiltrations were also seen. This model correlates closely with alcoholic hepatitis in human beings, characterized by increased IL-8, RANTES (regulated upon activation, normal T cell expressed and secreted), and macrophage inflammatory protein-1 (MIP-1) and profound increases in neutrophils and lymphocytes in the liver.

Liver sinusoidal endothelial cell injury by neutrophils in rats with acute obstructive cholangitis

AIM: The objective of this study is to elucidate the potential role of poly-morphonuclear neutrophils (PMN) in the development of such a sinusoidal endothelial cell (SEC) injury during early acute obstructive cholangitis (AOC) in rats.

METHODS: Twenty one Wistar rats were divided into three groups: the AOC group, the bile duct ligated group (BDL group), and the sham operation group (SO group). The common bile duct (CBD) of rats in AOC group was dually ligated and 0.2 mL of the E. coli O₁₁₁ B₄ (5 × 10⁹ cfu/mL) suspension was injected into the upper segment, in BDL group, only the CBD was ligated and in SO group, neither injection of E. coli suspension nor CBD ligation was done, but the same operative procedure. Such group consisted of seven rats, all animals were killed 6 h after the operation. Morphological changes of the liver were observed under light and electron microscope. Expression of intercellular adhesion molecule-1 (ICAM-1) mRNA in hepatic tissue was determined with reverse transcription polymerase chain reaction (RT-PCR). The serum levels of alanine aminotransferase (ALT) were determined with anutoanalyger and cytokine-induced neutrophil chemoattractant (CINC) was determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS: Neutrophils was accumulated in the hepatic sinusoids and sinusoidal endothelial cell injury existed in AOC group. In contrast, in rats of BDL group, all the features of SEC damage were greatly reduced. Expression of ICAM-1 mRNA in hepatic tissue in three groups were 7.54 ± 0.82, 2.87 ± 0.34, and 1.01 ± 0.12, respectively. There were significant differences among three groups (P < 0.05). The serum CINC levels in the three groups were 188 ± 21 ng•L⁻¹, 94 ± 11 ng•L⁻¹, and 57 ± 8 ng•L⁻¹, respectively. There were also significant differences among the three groups (P < 0.05). Activity of the serum ALT was 917 ± 167 nkat•L⁻¹, 901 ± 171 nkat•L⁻¹, and 908 ± 164 nkat•L⁻¹, respectively, (P > 0.05).

CONCLUSION: Hepatic SEC injury occurs earlier than hepatic parenchymal cells during AOC. Recruitments of circulating neutrophils in the hepatic sinusoidal space might mediate the SEC injury, and ICAM-1 in the liver may modulate the PMN of accumulation.

Expression of lipopolysaccharide binding protein and its receptor CD14 in experimental alcoholic liver disease

AIM: To evaluate the relationship between the expression of lipopolysaccharides (LPS) binding protein (LBP) and CD14 mRNA and the severity of liver injury in alcohol-fed rats.

METHODS: Twenty Wistar rats were divided into two groups: ethanol-fed group (group E) and control group (group C). Group E was fed with ethanol (5-12 g·kg¯¹·d¯¹) and group C received dextrose instead of ethanol. Rats of the two groups were sacrificed at 4 wk and 8 wk. Levels of endotoxin and alanine transaminase (ALT) in blood were measured, and liver pathology was observed under light and electronic microscopy. Expressions of LBP and CD14 mRNA in liver tissues were determined by RT-PCR analysis.

RESULTS: Plasma endotoxin levels were increased more significantly in group E (129 ± 21) ng·L¯¹ and (187 ± 35) ng·L¯¹ at 4 and 8 wk than in control rats (48 ± 9) ng·L¯¹ and (53 ± 11) ng·L¯¹, respectively (P < 0.05). Mean values of plasma ALT levels were (1867 ± 250) nkat·L¯¹ and (2450 ± 367) nkat·L¯¹ in Group E. The values were increased more dramatically in ethanol-fed rats than in Group C after 4 and 8 wk. In liver section from ethanol-fed rats, there were marked pathological changes (steatosis, cell infiltration and necrosis). In ethanol-fed rats, ethanol administration led to a significant increase in LBP and CD14 mRNA levels compared with the control group (P < 0.05).

CONCLUSION: Ethanol administration led to a significant increase in endotoxin levels in serum and LBP and CD14 mRNA expressions in liver tissues. The increase of LBP and CD14 mRNA expression might wake the liver more sensitive to endotoxin and liver injury.

Alcoholic liver disease: new insights into mechanisms and preventative strategies

Alcoholic liver disease has a known aetiology but a complex pathogenesis. It is an extremely common disease with a high mortality, but the reason why only a relatively small proportion of heavy drinkers progress to advanced disease remains elusive. Accumulating evidence points towards an elaborate interplay between metabolism, inflammation and immunity in the development of steatosis, hepatitis and fibrosis. These complex pathways leading to liver injury offer many potential susceptibility loci, as well as sites for potential therapeutic intervention.

Chronic ethanol intoxication enhances the production of cytokine-induced neutrophil chemoattractant and macrophage inflammatory protein-2 by hepatocytes after human immunodeficiency virus-1 glycoprotein 120 vaccination

Chemokines are implicated in the pathogenesis of alcoholic liver disease and human immunodeficiency virus-1 (HIV-1) infection. Thus, this work examined the regulation of chemokines --i.e., cytokine-induced neutrophil chemoattractant (CINC) and macrophage inflammatory protein-2 (MIP-2)--produced by hepatocytes after HIV-1 glycoprotein 120 (gp120) vaccination in Wistar rats fed with ethanol for 30 weeks. HIV-1 gp120 in complete Freund's adjuvant was given by intrainguinal route at a dose of 5 g/kg, followed by two booster shots in incomplete Freund's adjuvant at a weekly interval. Samples were taken 1 week after the last injection was given. Results show that anti-HIV-1 gp120 antibody titer was suppressed by 40% in the ethanol-fed rats, compared with findings in the parallel controls. However, serum CINC and MIP-2 levels were more elevated in the ethanol-fed rats than in the pair-fed group. The likely sources of these chemokines are the hepatocytes. After HIV-1 gp120 treatment, isolated hepatocytes obtained from the ethanol-fed group produced more CINC and MIP-2 than did those of pair-fed rats. Concomitantly, mRNA expression for these two chemokines and hepatic sequestration of neutrophils were upregulated. Ethanol feeding alone suppressed chemokine release, but it did not alter mRNA expression in isolated hepatocytes. Administration of Freund's adjuvant (without HIV-1 gp120) did not induce chemokine release in vivo and did not prime isolated hepatocytes for enhanced chemokine production in vitro. These results show that chronic ethanol intoxication affects the ability of the host to respond to HIV-1 gp120 vaccination.