Molecular pathogenesis of alcohol-induced hepatic fibrosis

Joint association of alcohol consumption and adiposity with alcohol- and obesity-related cancer in a population sample of 399,575 UK adults

Obesity and alcohol consumption are both important modifiable risk factors for cancer. We examined the joint association of adiposity and alcohol consumption with alcohol- and obesity-related cancer incidence. This prospective cohort study included cancer-free UK Biobank participants aged 40-69 years. Alcohol consumption was categorised based on current UK guidelines into four groups. We defined three markers of adiposity: body fat percentage (BF %), waist circumference and BMI and categorised each into three groups. We derived a joint alcohol consumption and adiposity marker variable with twelve mutually exclusive categories. Among 399 575 participants, 17 617 developed alcohol-related cancer and 20 214 developed obesity-related cancer over an average follow-up of 11·8 (SD 0·9) years. We found relatively weak evidence of independent associations of alcohol consumption with cancer outcomes. However, the joint association analyses showed that across all adiposity markers, above guideline drinkers who were in the top two adiposity groups had elevated cancer incidence risk (e.g. HR for alcohol-related cancer was 1·53 (95 % CI (1·24, 1·90)) for within guideline drinkers and 1·61 (95 % CI (1·30, 2·00)) for above guideline drinkers among participants who were in the top tertile BF %. Regardless of alcohol consumption status, the risk of obesity-related cancer increased with higher adiposity in a dose-response manner within alcohol consumption categories. Our study provides guidance for public health priorities aimed at lowering population cancer risk via two key modifiable risk factors.

Sequential delivery for hepatic fibrosis treatment based on carvedilol loaded star-like nanozyme

Hepatic fibrosis, characterized by excessive reactive oxygen species (ROS) generation, hepatic stellate cells (HSCs) activation, and enormous extracellular matrix (ECM) production, can further cause liver cirrhosis, liver failure and liver cancer. However, the combination of limited solubility, low targeting, uncontrolled release and the sophisticated physiological barriers are tremendous challenges for therapeutic effect. In this study, we engineered a sequential delivery strategy based on autophagy inhibitor carvedilol (CAR) loaded and hyaluronic acid (HA) modified star-like Au nanozyme (Au NS@CAR-HA) for targeted HSCs suppression. In hepatic fibrosis acidic environment, CAR-HA can be firstly detached from Au NS@CAR-HA. Then, CAR would be released from CAR-HA conjugation by chemical bond breakage which triggered by intracellular acid potential, thus could suppressing autolysosome generation by up-regulation of autosome and lysosome pH value to inhibit HSCs activation. Meanwhile, Au NS exhibited enhanced ROS scavenging efficiency of hydrogen peroxides and superoxide, which was helpful to restrain the activity of peroxisome proliferators-activated receptors β (PPARβ) and c-Jun N-terminal kinase (JNK), thereby reducing HSCs proliferation to enhance HSCs inactivation efficacy. In conclusion, Au NS@CAR-HA can attenuate hepatic fibrosis via regulating the proliferation and activation of hepatic stellate cells, which provides a new strategy for hepatic fibrosis treatment.

TGF-β1 can be regulated by NDRG2 via the NF-κB pathway in hypoxia-induced liver fibrosis

Background

The identification of the important elements that control hepatic stellate cell (HSC) activation will expand our understanding of the mechanism of liver fibrosis induced by hypoxia and affect the outcome of clinical treatment. A previous research demonstrated that N-Myc downstream-regulated gene 2 (NDRG2) is a potential regulator of fibrosis and a downstream target gene of hypoxia-inducible factor 1 (HIF-1). In this research, we studied the expression and function of NDRG2 in liver fibrosis induced by hypoxia.

Methods

LX-2 cells/NF-κB-silenced LX-2 cells were exposed to hypoxic conditions (1% O₂) to activate HSCs in vitro. The protein and mRNA expression levels of NDRG2, α-SMA and transforming growth factor beta 1 (TGF-β1) were evaluated by western blotting and real-time polymerase chain reaction (RT-PCR), respectively. Functional studies were performed using adenovirus-mediated gene upregulation.

Results

The NDRG2 mRNA and protein levels were reduced under hypoxic conditions in LX-2 cells and overexpression of NDRG2 resulted in a decrease in the expression of TGF-β1 and α-SMA. Interestingly, no relationship was observed between NDRG2 and TGF-β1 when the NF-κB pathway was blocked, which indicates that NDRG2 can regulate the expression of TGF-β1 in LX-2 cells via the NF-κB pathway under hypoxic conditions.

Conclusions

NDRG2 may regulate the expression of TGF-β1 via the NF-κB pathway and may be a novel therapeutic target for liver fibrosis induced by hypoxia.

Second hits exacerbate alcohol-related organ damage: an update

Chronic and excessive alcohol abuse cause direct and indirect detrimental effects on a wide range of body organs and systems and accounts for ~4% of deaths worldwide. Many factors influence the harmful effects of alcohol. This concise review presents newer insights into the role of select second hits in influencing the progression of alcohol-induced organ damage by synergistically acting to generate a more dramatic downstream biological defect. This review specifically addresses on how a lifestyle factor of high fat intake exacerbates alcoholic liver injury and its progression. This review also provides the mechanistic insights into how increasing matrix stiffness during liver injury promotes alcohol-induced fibrogenesis. It also discusses how hepatotropic viral (HCV, HBV) infections as well as HIV (which is traditionally not known to be hepatotropic), are potentiated by alcohol exposure to promote hepatotoxicity and fibrosis progression. Finally, this review highlights the impact of reactive aldehydes generated during alcohol and cigarette smoke coexposure impair innate antimicrobial defense and increased susceptibility to infections. This review was inspired by the symposium held at the 17th Congress of the European Society for Biomedical research on Alcoholism in Lille, France entitled 'Second hits in alcohol-related organ damage'.

Curcumin Can be Acts as Effective agent for Prevent or Treatment of Alcohol-induced Toxicity in Hepatocytes: An Illustrated Mechanistic Review

Previous studies have shown that alcohol abuse can cause serious liver damage and cirrhosis. The main pathway for these types of hepatocellular cell neurodegeneration is mitochondrial dysfunction, which causes lipid peroxidation and dysfunction of the glutathione ring and the defect of antioxidant enzymes in alcoholic hepatic cells. Alcohol can also initiate malicious inflammatory pathways and trigger the initiation and activation of intestinal and extrinsic apoptosis pathways in hepatocellular tissues that lead to cirrhosis. Previous studies have shown that curcumin may inhibit lipid peroxidation, glutathione dysfunction and restore antioxidant enzymes. Curcumin also modulates inflammation and the production of alcohol-induced biomarkers. Curcumin has been shown to play a critical role in the survival of alcoholic hepatocellular tissue. It has been shown that curcumin can induce and trigger mitochondrial biogenesis and, by this mechanism, prevent the occurrence of both intrinsic and extrinsic apoptosis pathways in liver cells that have been impaired by alcohol. According to this mechanism, curcumin may protect hepatocellular tissue from alcohol-induced cell degeneration and may therefore survive alcoholic hepatocellular tissue. . Based on these mechanisms, the protective functions of curcumin against alcohol-induced cell degeneration due to oxidative stress, inflammation, and apoptosis events in hepatocellular tissue have been recorded. Hence, in this research, we have attempted to evaluate and analyze the main contribution mechanism of curcumin cell defense properties against alcohol-induced hepatocellular damage, according to previous experimental and clinical studies, and in this way we report findings from major studies.

Ethanol upregulates the P2X7 purinergic receptor in human macrophages

Alcohol consumption is considered to be the third leading cause of death in the United States. In addition to its direct toxicity, ethanol has two contrasting effects on the immune system: the nucleotide oligomerization domain-like receptor pyrin domain-containing-3 (NLRP3) inflammasome is inhibited by acute ethanol exposure but activated by chronic ethanol exposure. Purinergic receptors (especially the P2X7 receptor) are able to activate the NLRP3 inflammasome and are involved in many ethanol-related diseases (such as gout, pulmonary fibrosis, alcoholic steatohepatitis, and certain cancers). We hypothesized that ethanol regulates purinergic receptors and thus modulates the NLRP3 inflammasome's activity. In experiments with monocyte-derived macrophages, we found that interleukin (IL)-1β secretion was inhibited after 7 h of exposure (but not 48 h of exposure) to ethanol. The disappearance of ethanol's inhibitory effect on IL-1β secretion after 48 h was not mediated by the upregulated production of IL-1β, IL-1α, IL-6 or the inflammasome components NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain, and caspase 1. P2X7R expression was upregulated by ethanol, whereas expression of the P2X4 and P2X1 receptors was not. Taken as a whole, our results suggest that ethanol induces NLRP3 inflammasome activation by upregulating the P2X7 receptor. This observation might have revealed a new mechanism for inflammation in ethanol-related diseases.

The Extract of Edible Alga Petalonia binghamiae Suppresses TGF-β1-or H2O2-Induced Liver Fibrogenesis in LX-2 and HepG2 Cells

Although the edible alga Petalonia binghamiae is extensively consumed as a health-promoting food by Northeast Asians, little is known about the biomedical efficacies of P. binghamiae. In this report, we investigated the novel efficacy of P. binghamiae extract ( Pb-E01) using LX-2 and HepG2 cells. Pb-E01 inhibited TGF-β1-induced cell proliferation and gene expression in LX-2 cells. In addition, Pb-E01 reduced H2O2–induced reactive oxygen species (ROS) and alanine aminotransferase (ALT) activity in HepG2 cells. According to these results, we suggest that Pb-E01 plays a functional role in suppressing liver fibrogenesis.

The therapeutic effect of nano-encapsulated and nano-emulsion forms of carvacrol on experimental liver fibrosis

OBJECTIVE

The present study aimed to compare the therapeutic efficiency of nano-encapsulated and nano-emulsion carvacrol administration on liver injury in thioacetamide (TAA) treated rats.

METHODS

To fulfill our target, we used sixty male albino rats classified into six groups as follow: control, nano-encapsulated carvacrol, nano-emulsion carvacrol, thioacetamide, treated nano-encapsulated carvacrol and treated nano-emulsion carvacrol groups. Blood samples were collected from all groups and the separated serum was used for analysis of the following biochemical parameters; aspartate aminotransferase (AST), alanine aminotransferase (ALT), S100 B protein, alpha fetoprotein (AFP) and caspase-3. The levels of malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), monocyte chemoattractant protein-1(MCP-1) and hydroxyproline content were all evaluated in liver tissue homogenate. Histopathological examinations for liver tissues were also performed.

RESULTS

Thioacetamide induced hepatic damage in rats as revealed by the significant increase in the levels of serum ALT, AST and produced oxidative stress as displayed by the significant elevation in the levels of hepatic MDA and NO concomitant with a significant decrease in GSH. In addition, thioacetamide significantly increased serum S100B protein, alpha fetoprotein and caspase-3 along with hepatic MCP-1 and hydroxyproline; these results were confirmed by the histopathological investigation. In contrast, nano-encapsulated and nano-emulsion carvacrol were able to ameliorate these negative changes in the thioacetamide injected rats. However, the effect of the nano-encapsulated form of carvacrol was more prominent than the nano-emulsion form.

CONCLUSION

Nano-encapsulated and nano-emulsion carvacrol can ameliorate thioacetamide induced liver injury. These results could be attributed to the potential anti-inflammatory, antioxidant, and anti-apoptotic activities of carvacrol in addition to the effectiveness of the encapsulation technique that can protect carvacrol structure and increase its efficiency and stability. Moreover, nano-encapsulation of carvacrol is more efficient than nano-emulsion.

Oxidative stress in cancer and fibrosis: Opportunity for therapeutic intervention with antioxidant compounds, enzymes, and nanoparticles

Oxidative stress, mainly contributed by reactive oxygen species (ROS), has been implicated in pathogenesis of several diseases. We review two primary examples; fibrosis and cancer. In fibrosis, ROS promote activation and proliferation of fibroblasts and myofibroblasts, activating TGF-β pathway in an autocrine manner. In cancer, ROS account for its genomic instability, resistance to apoptosis, proliferation, and angiogenesis. Importantly, ROS trigger cancer cell invasion through invadopodia formation as well as extravasation into a distant metastasis site. Use of antioxidant supplements, enzymes, and inhibitors for ROS-generating NADPH oxidases (NOX) is a logical therapeutic intervention for fibrosis and cancer. We review such attempts, progress, and challenges. Lastly, we review how nanoparticles with inherent antioxidant activity can also be a promising therapeutic option, considering their additional feature as a delivery platform for drugs, genes, and imaging agents.

Metabolic zonation of the liver: The oxygen gradient revisited

The liver has a multitude of functions which are necessary to maintain whole body homeostasis. This requires that various metabolic pathways can run in parallel in the most efficient manner and that futile cycles are kept to a minimum. To a large extent this is achieved due to a functional specialization of the liver parenchyma known as metabolic zonation which is often lost in liver diseases. Although this phenomenon is known for about 40 years, the underlying regulatory pathways are not yet fully elucidated. The physiologically occurring oxygen gradient was considered to be crucial for the appearance of zonation; however, a number of reports during the last decade indicating that β-catenin signaling, and the hedgehog (Hh) pathway contribute to metabolic zonation may have shifted this view. In the current review we connect these new observations with the concept that the oxygen gradient within the liver acinus is a regulator of zonation. This is underlined by a number of facts showing that the β-catenin and the Hh pathway can be modulated by the hypoxia signaling system and the hypoxia-inducible transcription factors (HIFs). Altogether, we provide a view by which the dynamic interplay between all these pathways can drive liver zonation and thus contribute to its physiological function.

Effect of ginseng extract on the TGF-β1 signaling pathway in CCl4-induced liver fibrosis in rats

Background

Liver diseases are major global health problems. Ginseng extract has antioxidant, immune-modulatory and anti-inflammatory activities. This study investigated the effect of ginseng extract on carbon tetrachloride (CCl4)-induced liver fibrosis in rats.

Methods

Male Wistar rats were divided into four groups: control group, ginseng group, CCl₄ group and CCl₄ + ginseng group. Liver injury was induced by the intraperitoneal (I.P) injection of 3 ml/kg CCl₄ (30% in olive oil) weekly for 8 weeks. The control group was I.P injected with olive oil. The expression of genes encoding transforming growth factor beta (TGF-β), type I TGF-β receptor (TβR-1), type II TGF-β receptor (TβR-II), mothers against decapentaplegic homolog 2 (Smad2), Smad3, Smad4, matrix metalloproteinase 2 (MMP2), MMP9, tissue inhibitor matrix metalloproteinase-1 (TIMP-1), Collagen 1a2 (Col1a2), Collagen 3a1 (Col3a1), interleukin-8 (IL-8) and interleukin -10 (IL-10) were measured by real-time PCR.

Results

Treatment with ginseng extract decreased hepatic fat deposition and lowered hepatic reticular fiber accumulation compared with the CCl₄ group. The CCl₄ group showed a significant increase in hepatotoxicity biomarkers and up-regulation of the expression of genes encoding TGF-β, TβR-I, TβR-II, MMP2, MMP9, Smad-2,-3, -4, and IL-8 compared with the control group. However, CCl₄ administration resulted in the significant down-regulation of IL-10 mRNA expression compared with the control group. Interestingly, ginseng extract supplementation completely reversed the biochemical markers of hepatotoxicity and the gene expression alterations induced by CCl₄.

Conclusion

ginseng extract had an anti‐fibrosis effect via the regulation of the TGF‐β1/Smad signaling pathway in the CCl₄‐induced liver fibrosis model. The major target was the inhibition of the expression of TGF‐β1, Smad2, and Smad3.

Venlafaxine-Induced Cytotoxicity Towards Isolated Rat Hepatocytes Involves Oxidative Stress and Mitochondrial/Lysosomal Dysfunction

Purpose: Depression is a public disorder worldwide. Despite the widespread use of venlafaxine in the treatment of depression, it has been associated with the incidence of toxicities. Hence, the goal of the current investigation was to evaluate the mechanisms of venlafaxine-induced cell death in the model of the freshly isolated rat hepatocytes. Methods: Collagenase-perfused rat hepatocytes were treated with venlafaxine and other agents. Cell damage, reactive oxygen species (ROS) formation, lipid peroxidation, mitochondrial membrane potential decline, lysosomal damage, glutathione (GSH) level were analyzed. Moreover, rat liver mitochondria were isolated through differential centrifugation to assess respiratory chain functionality. Results: Our results demonstrated that venlafaxine could induce ROS formation followed by lipid peroxidation, cellular GSH content depletion, elevated GSSG level, loss of lysosmal membrane integrity, MMP collapse and finally cell death in a concentration-dependent manner. N-acetyl cysteine, taurine and quercetine significantly decreased the aforementioned venlafaxine-induced cellular events. Also, radical scavenger (butylatedhydroxytoluene and α-tocopherol), CYP2E1 inhibitor (4-methylpyrazole), lysosomotropic agents (methylamine and chloroquine), ATP generators (L-gluthamine and fructose) and mitochondrial pore sealing agents (trifluoperazine and L-carnitine) considerably reduced cytotoxicity, ROS generation and lysosomal leakage following venlafaxine treatment. Mitochondrion dysfunction was concomitant with the blockade of the electron transfer complexes II and IV of the mitochondrial respiratory system. Conclusion: Therefore, our data indicate that venlafaxine induces oxidative stress towards hepatocytes and our findings provide evidence to propose that mitochondria and lysosomes are of the primary targets in venlafaxine-mediated cell damage.

Role of renin-angiotensin system in liver diseases: an outline on the potential therapeutic points of intervention

The current review aimed to outline the functions of the renin angiotensin system (RAS) in the context of the oxidative stress-associated liver disease. Areas covered: Angiotensin II (Ang II) as the major effector peptide of the RAS is a pro-oxidant and fibrogenic cytokine. Mechanistically, NADPH oxidase (NOX) is a multicomponent enzyme complex that is able to generate reactive oxygen species (ROS) as a downstream signaling pathway of Ang II which is expressed in liver. Ang II has a detrimental role in the pathogenesis of chronic liver disease through possessing pro-oxidant, fibrogenic, and pro-inflammatory impact in the liver. The alternative axis (ACE2/Ang(1-7)/mas) of the RAS serves as an anti-inflammatory, antioxidant and anti-fibrotic component of the RAS. Expert commentary: In summary, the use of alternative axis inhibitors accompanying with ACE2/ Ang(1-7)/mas axis activation is a promising new strategy serving as a novel therapeutic option to prevent and treat chronic liver diseases.

In vitro and in vivo evaluation of the mechanisms of citalopram-induced hepatotoxicity

Even though citalopram is commonly used in psychiatry, there are several reports on its toxic effects. So, the current study was designed to elucidate the mechanisms of cytotoxic effects of in vitro and in vivo citalopram treatment on liver and the following cytolethal events. For in vitro experiments, freshly isolated rat hepatocytes were exposed to citalopram along with/without various agents. To do in vivo studies liver function enzyme assays and histological examination were performed. In the in vitro experiments, citalopram (500 µM) exposure demonstrated cell death, a marked elevation in ROS formation, mitochondrial potential collapse, lysosomal membrane leakiness, glutathione (GSH) depletion and lipid peroxidation. In vivo biochemistry panel assays for liver enzymes function (AST, ALT and GGTP) and histological examination confirmed citalopram (20 mg/kg)-induced damage. citalopram-induced oxidative stress cytotoxicity markers were significantly prevented by antioxidants, ROS scavengers, MPT pore sealing agents, endocytosis inhibitors, ATP generators and CYP inhibitors. Either enzyme induction or GSH depletion were concomitant with augmented citalopram-induced damage both in vivo and in vitro which were considerably ameliorated with antioxidants and CYP inhibitors. In conclusion, it is suggested that citalopram hepatotoxicity might be a result of oxidative hazard leading to mitochondrial/lysosomal toxic connection and disorders in biochemical markers which were supported by histomorphological studies.

Thymosin Beta 4 Is a Potential Regulator of Hepatic Stellate Cells

Liver fibrosis, a major characteristic of chronic liver disease, is inappropriate tissue remodeling caused by prolonged parenchymal cell injury and inflammation. During liver injury, hepatic stellate cells (HSCs) undergo transdifferentiation from quiescent HSCs into activated HSCs, which promote the deposition of extracellular matrix proteins, leading to liver fibrosis. Thymosin beta 4 (Tβ4), a major actin-sequestering protein, is the most abundant member of the highly conserved β-thymosin family and controls cell morphogenesis and motility by regulating the dynamics of the actin cytoskeleton. Tβ4 is known to be involved in various cellular responses, including antiinflammation, wound healing, angiogenesis, and cancer progression. Emerging evidence suggests that Tβ4 is expressed in the liver; however, its biological roles are poorly understood. Herein, we introduce liver fibrogenesis and recent findings regarding the function of Tβ4 in various tissues and discuss the potential role of Tβ4 in liver fibrosis with a special focus on the effects of exogenous and endogenous Tβ4. Recent studies have revealed that activated HSCs express Tβ4 in vivo and in vitro. Treatment with the exogenous Tβ4 peptide inhibits the proliferation and migration of activated HSCs and reduces liver fibrosis, indicating it has an antifibrotic action. Meanwhile, the endogenously expressed Tβ4 in activated HSCs is shown to promote HSCs activation. Although the role of Tβ4 has not been elucidated, it is apparent that Tβ4 is associated with HSC activation. Therefore, understanding the potential roles and regulatory mechanisms of Tβ4 in liver fibrosis may provide a novel treatment for patients.

MMP-2 and MMP-9 activities and TIMP-1 and TIMP-2 expression in the prostatic tissue of two ethanol-preferring rat models

We investigated whether chronic ethanol intake is capable of altering the MMP-2 and MMP-9 activities and TIMP-2 and TIMP-1 expression in the dorsal and lateral prostatic lobes of low (UChA) and high (UChB) ethanol-preferring rats. MMP-2 and MMP-9 activities and TIMP-1 and TIMP-2 expression were significantly reduced in the lateral prostatic lobe of the ethanol drinking animals. Dorsal prostatic lobe was less affected showing no significant alterations in these proteins, except for a reduction in the TIMP-1 expression in UChA rats. These important findings demonstrate that chronic ethanol intake impairs the physiological balance of the prostate extracellular matrix turnover, through downregulation of MMPs, which may contribute to the development of prostatic diseases. Furthermore, since these proteins are also components of prostate secretion, the negative impact of chronic ethanol intake on fertility may also involve reduction of MMPs and TIMPs in the seminal fluid.

Expression of HIF-1α and NF-κB in non-alcoholic fat liver disease in rats

AIM: To investigate the role of hypoxia-inducible factor -1α (HIF-1α) and nuclear transcription factor κB (NF-κB) in the development of non-alcoholic fat liver disease (NAFLD) using a rat model.

METHODS: Fifty SD rats were randomly divided into five groups (a normal group, a 4 wk model group, an 8 wk group, a 12 wk and a 16 wk group). NAFLD was induced in rats by administration of a high fat diet. Serum biochemical parameters were tested, and fiver histological changes were observed. HIF-1α and NF-κB mRNA expression was detected by real-time PCR.

RESULTS: Compared with the normal group, significant elevations of serum alanine amiotransferase (ALT), triglyceride (TG), and cholesterol (CHOL) and reduction of high-density lipoprotein cholesterol (HDL-C) were observed in rats given a high fat diet for 12 wk or 16 wk (P < 0.05). In the model groups, liver steatosis, inflammation grade and degree of fibrosis were significantly aggravated. HIF-1α and NF- κB expression increased gradually with the severity of NAFLD (P < 0.05).

CONCLUSION: HIF-1α/NF-κB signaling may be related to the development of NAFLD.

Ginseng extract and ginsenoside Rb1 attenuate carbon tetrachloride-induced liver fibrosis in rats

Background

Ginsenosides, the major bioactive compounds in ginseng root, have been found to have antioxidant, immunomodulatory and anti-inflammatory activities. This study investigated the effects of ginsenosides on carbon tetrachloride (CCl₄)-induced hepatitis and liver fibrosis in rats.

Methods

Male Sprague–Dawley rats were randomly divided into four groups: control, CCl₄, CCl₄ + 0.5 g/kg Panax ginseng extract and CCl₄ + 0.05 g/kg ginsenoside Rb1 groups. The treated groups were orally given Panax ginseng extract or ginsenoside Rb1 two weeks before the induction of liver injury for successive 9 weeks. Liver injury was induced by intraperitoneally injected with 400 ml/l CCl₄ at a dose of 0.75 ml/kg body weight weekly for 7 weeks. The control group was intraperitoneally injected with olive oil.

Results

The pathological results showed that ginsenoside Rb1 decreased hepatic fat deposition (2.65 ± 0.82 vs 3.50 ± 0.75, p <0.05) and Panax ginseng extract lowered hepatic reticular fiber accumulation (1.05 ± 0.44 vs 1.60 ± 0.39, p <0.01) increased by CCl₄. Plasma alanine aminotransferase and aspartate aminotransferase activities were increased by CCl₄ (p <0.01)_, and aspartate aminotransferase activity was decreased by Panax ginseng extract at week 9 (p <0.05). Exposure to CCl₄ for 7 weeks, the levels of plasma and hepatic triglycerides (p <0.01), hepatic cholesterol (p <0.01), interleukin-1β (p <0.01), prostaglandin E₂ (p <0.05), soluble intercellular adhesion molecule-1 (p <0.05), hydroxyproline (p <0.05), matrix metalloproteinase-2 (p <0.05) and tissue inhibitor of metalloproteinase-1 (TIMP-1) (p <0.01) were elevated, however, hepatic interleukin-10 level was lowered (p <0.05). Both Panax ginseng extract and ginsenoside Rb1 decreased plasma and hepatic triglyceride, hepatic prostaglandin E₂, hydroxyproline and TIMP-1 levels, and Panax ginseng extract further inhibited interleukin-1β concentrations (p <0.05).

Conclusions

Panax ginseng extract and ginsenoside Rb1 attenuate plasma aminotransferase activities and liver inflammation to inhibit CCl₄-induced liver fibrosis through down-regulation of hepatic prostaglandin E₂ and TIMP-1.

Systems genetics of hepatocellular damage in vivo and in vitro: identification of a critical network on chromosome 11 in mouse

Quantitative trait locus (QTL) mapping is a powerful method to find modifier loci that influence disease risk and progression without prior knowledge of underlying genetic mechanisms. The aim of this study is to identify gene loci that contribute to individual differences in liver fibrosis following chronic liver damage. For this purpose, we carried out a mapping study across a panel of 21 BXD recombinant inbred strains using primary hepatocytes challenged with transforming growth factor (TGF)-β for 48 h. We identified a 6 Mb interval on chromosome 11 that is a major modifier of TGF-β-induced hepatocyte injury. Corresponding in vivo genetic analysis of fibrosis after chronic hepatotoxic injury by carbon tetrachloride (CCl4 ip for 6 wk) highlighted the same locus. Expression QTL (eQTL) analysis in liver tissues in the BXD family identified six polymorphisms in this region that are associated with strong cis eQTLs and that correlate well with gene expression in liver after both 6 wk CCl4 treatment and acute ethanol damage of the liver. Within this interval we rank two genes containing coding sequence variants as strong candidates that may modulate the severity of liver fibrosis: 1) the extracellular proteinase inhibitor gene Expi (also known as Wdnm1 or Wfdc18) and 2) musashi RNA-binding protein 2 (Msi2). The powerful combination of experimental, genetics, and bioinformatics methods, as well as combined in vitro and in vivo approaches can be used to define QTLs, genes, and even candidate sequence variants linked to hepatotoxicity and fibrosis.

Role of oxidative stress in the pathogenesis of alcohol-induced liver disease

Chronic alcohol consumption is a well-known risk factor for liver disease, which represents a major cause of morbidity and mortality worldwide. The pathological process of alcohol-induced liver disease is characterized by a broad spectrum of morphological changes ranging from steatosis with minimal injury to more advanced liver damage, including steato-hepatitis and fibrosis/cirrhosis. Experimental and clinical studies increasingly show that the oxidative damage induced by ethanol contribute in many ways to the pathogenesis of alcohol hepatotoxicity. This article describes the contribution of oxidative mechanisms to liver damage by alcohol.

Adenosine 2A receptor antagonist prevented and reversed liver fibrosis in a mouse model of ethanol-exacerbated liver fibrosis

The effect of moderate alcohol consumption on liver fibrosis is not well understood, but evidence suggests that adenosine may play a role in mediating the effects of moderate ethanol on tissue injury. Ethanol increases the concentration of adenosine in the liver. Adenosine 2A receptor (A2AR) activation is known to enhance hepatic stellate cell (HSC) activation and A2AR deficient mice are protected from fibrosis in mice. Making use of a novel mouse model of moderate ethanol consumption in which female C57BL/6J mice were allowed continued access to 2% (vol/vol) ethanol (11% calories) or pair-fed control diets for 2 days, 2 weeks or 5 weeks and superimposed with exposure to CCl4, we tested the hypothesis that moderate ethanol consumption increases fibrosis in response to carbon tetrachloride (CCl4) and that treatment of mice with an A2AR antagonist prevents and/or reverses this ethanol-induced increase in liver fibrosis. Neither the expression or activity of CYP2E1, required for bio-activation of CCl4, nor AST and ALT activity in the plasma were affected by ethanol, indicating that moderate ethanol did not increase the direct hepatotoxicity of CCl4. However, ethanol feeding enhanced HSC activation and exacerbated liver fibrosis upon exposure to CCl4. This was associated with an increased sinusoidal angiogenic response in the liver. Treatment with A2AR antagonist both prevented and reversed the ability of ethanol to exacerbate liver fibrosis.

CONCLUSION

Moderate ethanol consumption exacerbates hepatic fibrosis upon exposure to CCl4. A2AR antagonism may be a potential pharmaceutical intervention to decrease hepatic fibrosis in response to ethanol.

In vivo measurement of aldehyde dehydrogenase-2 activity in rat liver ethanol model using dynamic MRSI of hyperpolarized [1-(13) C]pyruvate

To date, measurements of the activity of aldehyde dehydrogenase-2 (ALDH2), a critical mitochondrial enzyme for the elimination of certain cytotoxic aldehydes in the body and a promising target for drug development, have been largely limited to in vitro methods. Recent advancements in MRS of hyperpolarized (13) C-labeled substrates have provided a method to detect and image in vivo metabolic pathways with signal-to-noise ratio gains greater than 10 000-fold over conventional MRS techniques. However aldehydes, because of their toxicity and short T1 relaxation times, are generally poor targets for such (13) C-labeled studies. In this work, we show that dynamic MRSI of hyperpolarized [1-(13) C]pyruvate and its conversion to [1-(13) C]lactate can provide an indirect in vivo measurement of ALDH2 activity via the concentration of NADH (nicotinamide adenine dinucleotide, reduced form), a co-factor common to both the reduction of pyruvate to lactate and the oxidation of acetaldehyde to acetate. Results from a rat liver ethanol model (n = 9) show that changes in (13) C-lactate labeling following the bolus injection of hyperpolarized pyruvate are highly correlated with changes in ALDH2 activity (R(2) = 0.76).

Azelnidipine is a calcium blocker that attenuates liver fibrosis and may increase antioxidant defence

BACKGROUND AND PURPOSE

Oxidative stress plays a critical role in liver fibrogenesis. Reactive oxygen species (ROS) stimulate hepatic stellate cells (HSCs), and ROS-mediated increases in calcium influx further increase ROS production. Azelnidipine is a calcium blocker that has been shown to have antioxidant effects in endothelial cells and cardiomyocytes. Therefore, we evaluated the anti-fibrotic and antioxidative effects of azelnidipine on liver fibrosis.

EXPERIMENTAL APPROACH

We used TGF-β1-activated LX-2 cells (a human HSC line) and mouse models of fibrosis induced by treatment with either carbon tetrachloride (CCl(4) ) or thioacetamide (TAA).

KEY RESULTS

Azelnidipine inhibited TGF-β1 and angiotensin II (Ang II)-activated α1(I) collagen mRNA expression in HSCs. Furthermore, TGF-β1- and Ang II-induced oxidative stress and TGF-β1-induced p38 and JNK phosphorylation were reduced in HSCs treated with azelnidipine. Azelnidipine significantly decreased inflammatory cell infiltration, pro-fibrotic gene expressions, HSC activation, lipid peroxidation, oxidative DNA damage and fibrosis in the livers of CCl(4) - or TAA-treated mice. Finally, azelnidipine prevented a decrease in the expression of some antioxidant enzymes and accelerated regression of liver fibrosis in CCl(4) -treated mice.

CONCLUSIONS AND IMPLICATIONS

Azelnidipine inhibited TGF-β1- and Ang II-induced HSC activation in vitro and attenuated CCl(4) - and TAA-induced liver fibrosis, and it accelerated regression of CCl(4) -induced liver fibrosis in mice. The anti-fibrotic mechanism of azelnidipine against CCl(4) -induced liver fibrosis in mice may have been due an increased level of antioxidant defence. As azelnidipine is widely used in clinical practice without serious adverse effects, it may provide an effective new strategy for anti-fibrotic therapy.

Carvedilol attenuates the progression of alcohol fatty liver disease in rats

BACKGROUND

Hepatosteatosis is an essential step in liver disease progression. However, the mechanisms that mediate the progression of hepatosteatosis and the optimal inhibitor of them remain largely unclear. The sympathetic nervous system (SNS) is responsible for the lipid metabolism and the accumulation of collagen that occurs in an injured liver. Medicines that inhibit this pathway may be a relevant treatment for the hepatosteatosis, and then reduce the liver injury that progresses through the stage of steatosis to fibrosis.

METHODS

Using an ethanol-liquid-diet-fed rat model of alcohol fatty liver disease (AFLD), we studied the effects of carvedilol, which can block the SNS completely via β1, β2, and α1 adrenergic receptors, on the sympathetic tone, hepatosteatosis, and fibrosis based on histological, immunohistochemical, Western blot, and reverse transcriptase polymerase chain reaction analyses.

RESULTS

Carvedilol inhibited the ethanol-induced whole-body and hepatic sympathetic activities based on the serum 3-methoxy-4-hydroxyphenylglycol level and hepatic tyrosine hydroxylase expression. Carvedilol attenuated the hepatosteatosis, as evidenced by reduced hepatic triglyceride level and the accumulation of fatty droplets within hepatocytes, down-regulated fatty acid synthase and sterol regulatory element binding protein-1, and up-regulated peroxisome proliferator-activated receptor-α. No fibrosis signs were shown in our rat model. Carvedilol inhibited ethanol-induced the thickening of zone 3 vessel walls, reduced the activation of hepatic stellate cells (HSCs), and decreased the induction of collagen, transforming growth factor β1, and tissue inhibitor of metalloproteinases-1. Tumor necrosis factor α (TNF-α) was expressed on the activated HSCs and inhibited by carvedilol based on the immunohistochemical double staining analysis.

CONCLUSIONS

Ethanol metabolism-induced lipogenesis may trigger the SNS-activated HSCs feedback loop, and then induct the activated HSCs and the activated HSCs-derived TNF-α, the mediator of lipogenesis, overproduction. Carvedilol may block this feedback loop via antisympathetic activity and demonstrate its preventive role on the development of hepatosteatosis in rat with AFLD.

Protective effect of sodium ferulate on acetaldehyde-treated precision-cut rat liver slices

Activated hepatic stellate cells (HSCs) play a key role in hepatic fibrogenesis, and inhibition of HSC activation may prevent liver fibrosis. Acetaldehyde, the most deleterious metabolite of alcohol, triggers HSC activation in alcoholic liver injury. In the present study, we investigated the protective effect of sodium ferulate (SF), a sodium salt of ferulic acid that is rich in fruits and vegetables, on acetaldehyde-stimulated HSC activation using precision-cut liver slices (PCLSs). Rat PCLSs were co-incubated with 350 μM acetaldehyde and different concentrations of SF. Hepatotoxicity was assessed by measuring enzyme leakage and malondialdehyde content in tissue. α-Smooth muscle actin, transforming growth factor-β(1), and hydroxyproline were determined to assess the activation of HSCs. In addition, matrix metalloproteinase (MMP)-1 and the tissue inhibitor of metalloproteinase (TIMP-1) were determined to evaluate collagen degradation. SF prominently prevented the enzyme leakage in acetaldehyde-treated slices and also inhibited HSC activation and collagen production stimulated by acetaldehyde. In addition, SF increased MMP-1 expression and decreased TIMP-1 expression. These results showed that SF protected PCLSs from acetaldehyde-stimulated HSC activation and liver injury, which may be associated with the attenuation of oxidative injury and acceleration of collagen degradation.

Potential antifibrotic effects of AT1 receptor antagonist, losartan, and/or praziquantel on acute and chronic experimental liver fibrosis induced by Schistosoma mansoni

1. This study investigates the potential antifibrotic effect of losartan, AT-1 receptor antagonist, and/or praziquantel (PZQ) on acute and chronic hepatic fibrosis induced by Schistosoma mansoni (S. mansoni). 2. Schistosoma mansoni-infected mice were in two batches (I & II), each in four groups: (i) Infected untreated; (ii) treated with losartan, starting from the 4th or 12th weeks post-infection (PI); (iii) treated with PZQ in the 7th week PI; and (iv) treated with losartan, as group (ii) plus PZQ as group (iii). Comparable groups of uninfected mice were run in parallel with infected groups. Mice of batches I and II were killed 10 and 18 weeks PI, respectively. Hepatic content of hydroxyproline (HYP), serum levels and tissue expression of matrix metalloproteinase-2 (MMP-2), and transforming growth factor-β1 (TGF-β1) were determined. Parasitological, biochemical and histological parameters, which reflect disease severity and morbidity, were examined. 3. Losartan alone caused a considerable decrease in worm burden, hepatic tissue egg load with an increase in percentage of dead eggs, modulation of granuloma size and regression of inflammatory reactions, which was less obvious in the chronic stage. The best results were obtained when losartan was co-administered with PZQ, especially in the acute stage. This was revealed by a remarkable reduction in serum levels and tissue expression of MMP-2, TGF-β1 and HYP content, accompanied by conservation of hepatic reduced glutathione (GSH) versus the PZQ-treated group. 4. In conclusion, losartan has a promising antifibrotic action and could be introduced as a therapeutic tool with PZQ especially in acute schistosomal hepatic fibrosis.

Chronic alcohol exposure alters gene expression in HepG2 cells

BACKGROUND

The liver is the primary site of alcohol metabolism and is highly vulnerable to injuries due to chronic alcohol abuse. Several molecular mechanisms, including oxidative stress and altered cellular metabolism, have been implicated in the development and progression of alcoholic liver disease. We sought to gain further insight into the molecular pathogenesis by studying the effects of ethanol exposure on the global gene expression in HepG2 cells.

METHODS

HepG2 cells were cultured in the presence or absence of 75 mM ethanol for 9 days, with fresh media daily. Global gene expression changes were studied using Affymetrix GeneChip(®) Human Exon 1.0 ST Arrays. Gene expression differences were validated for 13 genes by quantitative real-time RT-PCR. To identify biological pathways affected by ethanol treatment, differentially expressed genes were analyzed by Ingenuity Pathway Analysis software.

RESULTS

Long-term ethanol exposure altered the expression of 1,093 genes (false discovery rate ≤ 3%); many of these changes were modest. Long-term ethanol exposure affected several pathways, including acute phase response, amino acid metabolism, carbohydrate metabolism, and lipid metabolism.

CONCLUSIONS

Global measurements of gene expression show that a large number of genes are affected by chronic ethanol, although most show modest effect. These data provide insight into the molecular pathology resulting from extended alcohol exposure.

PCBP2 siRNA reverses the alcohol-induced pro-fibrogenic effects in hepatic stellate cells

PURPOSE

Type I collagen accumulates during liver fibrosis primarily because α-complex protein-2 (αCP(2)), encoded by the poly(rC) binding protein 2 (PCBP2) gene, binds to the 3' end of the collagen mRNA and increases its half-life. This study aimed to reverse the pro-fibrogenic effect of alcohol on hepatic stellate cells (HSCs) by silencing the PCBP2 gene with siRNA.

METHODS

The silencing effects of a series of predesigned PCBP2 siRNAs were evaluated in the rat hepatic stellate cell line, HSC-T6. The pro-fibrogenic effects of alcohol on the expression levels of PCBP2 and type-I collagen were examined by several methods. The effect of PCBP2 siRNA on the stability of type I collagen α1(I) mRNA was investigated by an in vitro mRNA decay assay.

RESULTS

We identified one potent PCBP2 siRNA that reversed the alcohol-induced expression of PCBP2 in HSCs. The decay rate of the collagen α1(I) mRNA increased significantly in HSCs treated with the PCBP2 siRNA.

CONCLUSION

This study provides the first evidence that alcohol up-regulates the expression of PCBP2, which subsequently increases the half-life of collagen α1(I) mRNA. Silencing of PCBP2 using siRNA may provide a promising strategy to reverse the alcohol-induced pro-fibrogenic effects in HSCs.

Role of the endocannabinoid system in alcoholic liver disease

Alcohol abuse is a major cause of liver fibrosis and cirrhosis in developed countries. Alcoholic liver disease (ALD) is distinctively characterized by a pronounced inflammatory response due to elevated gut-derived endotoxin plasma levels, an augmented generation of oxidative stress with pericentral hepatic hypoxia and the formation of noxious ethanol metabolites (e.g. acetaldehyde or lipid oxidation products). These factors, based on a complex network of cytokine actions, together result in increased hepatocellular damage and activation of hepatic stellate cells, the key cell type of liver fibrogenesis. Recent studies suggest that the endocannabinoid system is a signaling system that also plays an important role in the pathogenesis of ALD. A study comparing chronic alcohol administration in cannabinoid receptor (CB) 1 or CB2 knockout versus wild-type mice revealed that CB1 signaling aggravated hepatic steatosis and fibrogenesis whereas CB2 protected the liver from ALD. These data suggested a protective role of CB2 (in contrast to CB1) in ALD. Similar results were found in global or hepatocyte-specific CB1 knockout mice that were resistant to ethanol-induced steatosis. Moreover, ethanol feeding upregulated the endocannabinoid 2-arachidonoyl glycerol and its biosynthetic enzyme diacylglycerol lipase-β selectively in hepatic stellate cells and subsequently increased expression of CB1 receptors in hepatocytes of wild-type mice leading to CB1-dependent hepatic steatosis by activation of lipogenic pathways. This ethanol-induced upregulation of CB1 receptors was partly dependent on the ethanol metabolite acetaldehyde. Thus, the hepatic endocannabinoid system offers emerging options for therapeutic exploitation not only for liver disease in general, but also for ALD.

Effect of indole-3-carbinol on ethanol-induced liver injury and acetaldehyde-stimulated hepatic stellate cells activation using precision-cut rat liver slices

1. Indole-3-carbinol (I3C), a major indole compound found in high levels in cruciferous vegetables, shows a broad spectrum of biological activities. However, few studies have reported the effect of I3C on alcoholic liver injury. In the present study, we investigated the protective effect of I3C on acute ethanol-induced hepatotoxicity and acetaldehyde-stimulated hepatic stellate cells (HSC) activation using precision-cut liver slices (PCLS). 2. Rat PCLS were incubated with 50 mmol/L ethanol or 350 μmol/L acetaldehyde, and different concentrations (100-400 μmol/L) of I3C were added into the culture system of these two liver injury models, respectively. Hepatotoxicity was assessed by measuring enzyme leakage and malondialdehyde (MDA) content in tissue. Activities of alcoholic enzymes were also determined. α-Smooth muscle actin (α-SMA), transforming growth factor (TGF-β(1) ) and hydroxyproline (HYP) were used as indices to evaluate the activation of HSC. In addition, matrix metalloproteinase-1 (MMP-1) and the tissue inhibitor of metalloproteinase (TIMP-1) were observed to estimate collagen degradation. 3. I3C significantly reduced the enzyme leakage in ethanol-treated slices. In I3C groups, cytochrome P450 (CYP) 2E1 activities were inhibited by 40.9-51.8%, whereas alcohol dehydrogenase (ADH) activity was enhanced 1.6-fold compared with the ethanol-treated group. I3C also showed an inhibitory effect against HSC activation and collagen production stimulated by acetaldehyde. After being incubated with I3C (400 μmol/L), the expression of MMP-1 was markedly enhanced, whereas TIMP-1 was decreased. 4. These results showed that I3C protected PCLS against alcoholic liver injury, which might be associated with the regulation of ethanol metabolic enzymes, attenuation of oxidative injury and acceleration of collagen degradation.

Antioxidative status of patients with alcoholic liver disease in southeastern Taiwan

AIM: To investigate the antioxidative status of patients with alcoholic liver disease (ALD) in southeastern Taiwan.

METHODS: Our study comprised 27 patients with ALD recruited from Taitung Mackay Memorial Hospital, located in southeastern Taiwan. Patients with ALD included 12 non-aborigines (12 men) and 15 aborigines (11 men and 4 women). According to the severity of ALD, patients with ALD included 10 with hepatitis (9 men and 1 woman) and 17 with cirrhosis (14 men and 3 women). Twenty-two age- and gender-matched healthy adults served as the control group in this study. Venous blood (10 mL) of each subject was drawn into EDTA-containing tubes after 8 h overnight fasting.

RESULTS: Compared to the control group, patients with ALD showed significantly lower erythrocytic catalase (11.1 ± 0.7 U/mg Hb vs 8.0 ± 0.7 U/mg Hb, P < 0.05) and superoxide dismutase (9.5 ± 1.6 U/mg Hb vs 3.0 ± 0.2 U/mg Hb, P < 0.05) activities. Furthermore, the erythrocytic reduced glutathione/oxidized glutathione ratio was significantly lower in ALD patients than that in the control group (38.1 ± 5.4 vs 15.7 ± 1.9, P < 0.05). The results revealed that patients with ALD experienced more oxidative stress than those in the control group. The non-aboriginal, but not the aboriginal, ALD group had higher erythrocytic glutathione peroxidase (GPX) activity than that in the control group (46.1 ± 7.8 U/g Hb vs 27.9 ± 2.2 U/g Hb, P < 0.05). Hepatitis, but not cirrhosis, ALD patients had higher erythrocytic GPX activity than that in the control group (44.3 ± 8.6 U/g Hb vs 27.9 ± 2.2 U/g Hb, P < 0.05).

CONCLUSION: Our results indicate that both ethnicity and the severity of ALD may cause different erythrocytic antioxidative enzyme activities especially GPX activity.

Pathogenesis of alcoholic liver disease: interactions between parenchymal and non-parenchymal cells

The development of alcoholic liver disease (ALD) is a complex process involving both the parenchymal and non-parenchymal cells in the liver. The impact of ethanol on hepatocytes can be characterized as a condition of organelle stress with multifactorial changes in hepatocellular function accumulating during ethanol exposure. These changes include oxidative stress, mitochondrial dysfunction, decreased methylation capacity, endoplasmic reticulum stress, impaired vesicular trafficking and altered proteasome function. Injury to hepatocytes is attributed, in part, to ethanol metabolism by the hepatocytes. Changes in the structural integrity of hepatic sinusoidal endothelial cells, as well as enhanced inflammation in the liver during ethanol exposure are also important contributors to injury. Activation of hepatic stellate cells initiates the deposition of extracellular matrix proteins characteristic of fibrosis. Kupffer cells, the resident macrophages in the liver, are particularly critical to the onset of ethanol-induced liver injury. Chronic ethanol exposure sensitizes Kupffer cells to activation by lipopolysaccharides via toll-like receptor 4. This sensitization enhances the production of inflammatory mediators, such as tumor necrosis factor-α and reactive oxygen species that contribute to hepatocyte dysfunction, necrosis and apoptosis of hepatocytes and the generation of extracellular matrix proteins leading to fibrosis. In this review we provide an overview of the complex interactions between parenchymal and non-parenchymal cells in the liver during the progression of ethanol-induced liver injury.

Obesity and alcohol synergize to increase the risk of incident hepatocellular carcinoma in men

BACKGROUND & AIMS

Body mass index (BMI) and alcohol use are risk factors for hepatocellular carcinoma (HCC). We performed a prospective study to determine if these factors have synergistic effects on HCC risk.

METHODS

Over 14 years, we followed up 2260 Taiwanese men from the Risk Evaluation of Viral Load Elevation and Associated Liver Disease/Cancer-Hepatitis B Virus (REVEAL-HBV) Study Cohort who tested positive for the hepatitis B surface antigen (mean age, 46 ± 10 y; mean BMI, 24 ± 3 kg/m(2)); 20% reported alcohol use. Incident HCC cases were identified via linkage to the national cancer registry. Multivariate-adjusted hazard ratio (HR) and 95% confidence interval (CI) were estimated using Cox-proportional hazards models.

RESULTS

In univariate analysis, the interaction between BMI and alcohol predicted incident HCC (P = .029). Alcohol use and extreme obesity (BMI ≥30 kg/m(2)) had synergistic effects on the risk of incident HCC in analyses adjusted for age (HR, 3.41; 95% CI, 1.25-9.27; P < .025) and multivariables (HR, 3.40; 95% CI, 1.24-9.34; P < .025). The relative risk estimate for the interaction and the attributable proportion from the interaction and synergy index were 1.59, 0.52, and 4.40, respectively; these indicate a multiplicative interaction between alcohol use and extreme obesity. In an analysis stratified into 4 World Health Organization categories of BMI and alcohol use, the risk of incident HCC increased in overweight (HR, 2.4; 95% CI, 1.3-4.4), obese (HR, 2.0; 95% CI, 1.1-3.7), and extremely obese (HR, 2.9; 95% CI, 1.0-8.0) users of alcohol (P for trend = .046).

CONCLUSIONS

Obesity and alcohol have synergistic effects to increase the risk of incident HCC in hepatitis B surface antigen-positive men. Lifestyle interventions might reduce the incidence of HCC.

Pharmacological inhibition of integrin alphavbeta3 aggravates experimental liver fibrosis and suppresses hepatic angiogenesis

The vitronectin receptor integrin alphavbeta3 promotes angiogenesis by mediating migration and proliferation of endothelial cells, but also drives fibrogenic activation of hepatic stellate cells (HSCs) in vitro. Expecting antifibrotic synergism, we studied the effect of alphavbeta3 inhibition in two in vivo models of liver fibrogenesis. Liver fibrosis was induced in rats by way of bile duct ligation (BDL) for 6 weeks or thioacetamide (TAA) injections for 12 weeks. A specific alphavbeta3 (alphavbeta5) inhibitor (Cilengitide) was given intraperitoneally twice daily at 15 mg/kg during BDL or after TAA administration. Liver collagen was determined as hydroxyproline, and gene expression was quantified by way of quantitative polymerase chain reaction. Liver angiogenesis, macrophage infiltration, and hypoxia were assessed by way of CD31, CD68 and hypoxia-inducible factor-1alpha immunostaining. Cilengitide decreased overall vessel formation. This was significant in portal areas of BDL and septal areas of TAA fibrotic rats and was associated with a significant increase of liver collagen by 31% (BDL) and 27% (TAA), and up-regulation of profibrogenic genes and matrix metalloproteinase-13. Treatment increased gamma glutamyl transpeptidase in both models, while other serum markers remained unchanged. alphavbeta3 inhibition resulted in mild liver hypoxia, as evidenced by up-regulation of hypoxia-inducible genes. Liver infiltration by macrophages/Kupffer cells was not affected, although increases in tumor necrosis factor alpha, interleukin-18, and cyclooxygenase-2 messenger RNA indicated modest macrophage activation.

CONCLUSION

Specific inhibition of integrin alphavbeta3 (alphavbeta5) in vivo decreased angiogenesis but worsened biliary (BDL) and septal (TAA) fibrosis, despite its antifibrogenic effect on HSCs in vitro. Angiogenesis inhibitors should be used with caution in patients with hepatic fibrosis.

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.

Current experimental perspectives on the clinical progression of alcoholic liver disease

Chronic alcohol abuse is an important cause of morbidity and mortality throughout the world. Liver damage due to chronic alcohol intoxication initially leads to accumulation of lipids within the liver and with ongoing exposure this condition of steatosis may first progress to an inflammatory stage which leads the way for fibrogenesis and finally cirrhosis of the liver. While the earlier stages of the disease are considered reversible, cirrhotic destruction of the liver architecture beyond certain limits causes irreversible damage of the organ and often represents the basis for cancer development. This review will summarize current knowledge about the molecular mechanisms underlying the different stages of alcoholic liver disease (ALD). Recent observations have led to the identification of new molecular mechanisms and mediators of ALD. For example, plasminogen activator inhibitor 1 was shown to play a central role for steatosis, the anti-inflammatory adipokine, adiponectin profoundly regulates liver macrophage function and excessive hepatic deposition of iron is caused by chronic ethanol intoxication and increases the risk of hepatocellular carcinoma development.

S-adenosyl-L-methionine attenuates oxidative stress and hepatic stellate cell activation in an ethanol-LPS-induced fibrotic rat model

Previous studies report S-adenosyl-L-methionine (SAMe) can exert hepatoprotective effects. At present, the role of SAMe in affecting the activation and/or proliferation of hepatic stellate cells (HSCs) during alcohol-induced fibrotic disease progression is poorly understood. In the human disease state, chronic ethanol intake increases hepatic exposure to LPS and magnifies the hepatic insult leading to fibrosis and cirrhosis. In this study, we developed a "2-hit" ethanol-LPS fibrotic liver rat model with which to investigate the effects of SAMe as a hepatic antifibrotic treatment. Male rats were maintained on liquid diets containing either ethanol or isocalorically matched controls for 8 weeks. Animals received ethanol alone (E), ethanol concomitant with twice weekly LPS injections (EL), or ethanol, LPS, and daily SAMe injections. When using this model, SAMe-treated animals demonstrated significantly decreased fibrosis, oxidative stress, steatosis, and improved liver function versus the EL group. In addition, the EL group showed increased HSC activation, an effect that was abrogated by the addition of SAMe. Analysis of the transforming growth factor-beta (TGF-beta) signaling pathways demonstrated increased hepatic TGF-beta and Smad3 messenger RNA expression in the E and EL groups, which was inhibited in the presence of SAMe. Conversely, SAMe led to increased Smad7 (an inhibitor of TGF-beta signaling) messenger RNA expression. These data demonstrate chronic ethanol feeding combined with LPS induces liver fibrosis, and the addition of SAMe significantly reduces hepatic injury and fibrosis through inhibition of oxidative stress and HSC activation.

Oxidative stress in alcoholic liver disease: role of NADPH oxidase complex

Alcohol is a well-known risk factor for liver damage and is one of the major causes of liver disease worldwide. Chronic intake of alcohol, over a certain limit, inevitably leads to hepatic steatosis. If the injury persists, steatosis with concomitant tumor necrosis factor-alpha and other cytokines, progresses to steatohepatitis, fibrosis and finally cirrhosis. Among the multiple factors involved in the process of alcohol-induced liver injury, a crucial role is played by oxidative stress. Several mechanisms during ethanol metabolism result in reactive oxygen species (ROS) production. Although the main site of ethanol metabolism is hepatocytes, other mechanisms are involved in alcohol-induced liver injury. Specifically, in the ROS production activity, an important role is played by the NADPH oxidase complex. NADPH oxidase is expressed in hepatocytes, hepatic stellate cells and Kupffer cells in the liver. Studying NADPH oxidase gives new insights into alcohol-induced liver damage and provides new direction for future therapeutic strategies.

Immunological response in alcoholic liver disease

The development of alcoholic liver disease (ALD) can be attributed to many factors that cause damage to the liver and alter its functions. Data collected over the last 30 years strongly suggests that an immune component may be involved in the onset of this disease. This is best evidenced by the detection of circulating autoantibodies, infiltration of immune cells in the liver, and the detection of hepatic aldehyde modified proteins in patients with ALD. Experimentally, there are numerous immune responses that occur when proteins are modified with the metabolites of ethanol. These products are formed in response to the high oxidative state of the liver during ethanol metabolism, causing the release of many inflammatory processes and potential of necrosis or apoptosis of liver cells. Should cellular proteins become modified with these reactive alcohol metabolites and be recognized by the immune system, then immune responses may be initiated. Therefore, it was the purpose of this article to shed some insight into how the immune system is involved in the development and/or progression of ALD.

Effect of ethanol on inflammatory responses. Implications for pancreatitis

BACKGROUND/AIMS

Alcohol use alters inflammatory cell responses. While alcohol has direct effects on pancreatic acinar cells, activation of inflammatory cells is a major component of the pathology of alcoholic pancreatitis.

METHODS

The effects of acute or chronic alcohol exposure were evaluated in human monocytes on the production of TNFalpha or IL-10 production, pro-inflammatory gene and nuclear factor-kappaB (NF-kappaB) activation.

RESULTS

Moderate, acute alcohol consumption or equivalent doses of alcohol in vitro had anti-inflammatory effects on monocyte activation via inhibition of pro-inflammatory genes and NF-kappaB activation, inhibition of TNFalpha production and augmentation of the anti-inflammatory cytokine, IL-10. In contrast, acute alcohol treatment augmented NF-kappaB activation and TNFalpha production and inhibited IL-10 levels in the presence of complex stimulation with combined TLR2 and TLR4 ligands. Prolonged alcohol exposure also resulted in an increase in NF-kappaB and TNFalpha production in response to TLR4 stimulation with LPS.

CONCLUSION

These results suggest that alcohol can either attenuate or promote inflammatory responses that are critical in pancreatitis. Our results support the hypothesis that both acute alcohol intake in the presence of complex stimuli (such as necrotic cells) and chronic alcohol exposure result in hyper-responsiveness of monocytes to inflammatory signals and may contribute to increased inflammation in pancreatitis.

Role of hepatic stellate cells in fibrogenesis and the reversal of fibrosis

Liver fibrosis is caused by many chronic diseases. Liver injury results in activation of collagen-producing cells and excessive deposition of extracellular matrix proteins. This process is orchestrated by many cell types. Hepatocytes apoptosis and inflammatory cells trigger secretion of profibrogenic and proinflammatory cytokines, such as transforming growth factor-beta1, angiotensin II, leptin, which in turn activates hepatic stellate cells, the major source of collagen type I. This review is focused on recent progress in the study of the pathogenesis of liver fibrosis.

siRNA-mediated knockdown of connective tissue growth factor prevents N-nitrosodimethylamine-induced hepatic fibrosis in rats

Hepatic fibrosis is a dynamic process that involves the interplay of different cell types in the hepatic tissue. Connective tissue growth factor (CTGF) is a highly profibrogenic molecule and plays a crucial role in the pathogenesis of hepatic fibrosis. The aim of the present investigation was three-fold. First, we studied the expression of CTGF in the cultured hepatic stellate cells using immunohistochemical technique. Second, we induced hepatic fibrosis in rats through serial intraperitoneal injections of N-nitrosodimethylamine (NDMA; dimethylnitrosamine, DMN) and studied the upregulation of CTGF and TGF-beta1 during hepatic fibrogenesis. Third, we downregulated CTGF expression using CTGF siRNA and examined the role of CTGF siRNA to prevent the progression of NDMA-induced hepatic fibrosis. The results depicted strong staining of CTGF in the transformed hepatic stellate cells in culture. Serial administrations of NDMA resulted in activation of hepatic stellate cells, upregulation of CTGF and TGF-beta1 both at mRNA and protein levels and well-developed fibrosis in the liver. Immunostaining, Western blot analysis, semiquantitative and real-time RT-PCR studies showed downregulation of CTGF and TGF-beta1 after treatment with CTGF siRNA. The results of the present study demonstrated that CTGF gene silencing through siRNA reduces activation of hepatic stellate cells, prevents the upregulation of CTGF and TGF-beta1 gene expression and inhibits accumulation of connective tissue proteins in the liver. The data further suggest that knockdown of CTGF upregulation using siRNA has potential therapeutic application to prevent hepatic fibrogenesis.