Alcohol-induced Fatty Liver Research Articles

Activation of peroxisome proliferator-activated receptor-γ by rosiglitazone improves lipid homeostasis at the adipose tissue-liver axis in ethanol-fed mice.

The development of alcohol-induced fatty liver is associated with a reduction of white adipose tissue (WAT). Peroxisome proliferator-activated receptor (PPAR)-γ prominently distributes in the WAT and plays a crucial role in maintaining adiposity. The present study investigated the effects of PPAR-γ activation by rosiglitazone on lipid homeostasis at the adipose tissue-liver axis. Adult C57BL/6 male mice were pair fed liquid diet containing ethanol or isocaloric maltose dextrin for 8 wk with or without rosiglitazone supplementation to ethanol-fed mice for the last 3 wk. Ethanol exposure downregulated adipose PPAR-γ gene and reduced the WAT mass in association with induction of inflammation, which was attenuated by rosiglitazone. Ethanol exposure stimulated lipolysis but reduced fatty acid uptake capacity in association with dysregulation of lipid metabolism genes. Rosiglitazone normalized adipose gene expression and corrected ethanol-induced lipid dyshomeostasis. Ethanol exposure induced steatosis and upregulated inflammatory genes in the liver, which were attenuated by rosiglitazone. Hepatic peroxisomal fatty acid β-oxidation was suppressed by ethanol in associated with inhibition of acyl-coenzyme A oxidase 1. Rosiglitazone elevated plasma adiponectin level and normalized peroxisomal fatty acid β-oxidation rate. However, rosiglitazone did not affect ethanol-reduced very low-density lipoprotein secretion from the liver. These results demonstrated that activation of PPAR-γ by rosiglitazone reverses ethanol-induced adipose dysfunction and lipid dyshomeostasis at the WAT-liver axis, thereby abrogating alcoholic fatty liver.

Antilipogenic and Anti-Inflammatory Activities ofCodonopsis lanceolatain Mice Hepatic Tissues after Chronic Ethanol Feeding

This study evaluated the antilipogenic and anti-inflammatory effects of Codonopsis lanceolata (C. lanceolata) root extract in mice with alcohol-induced fatty liver and elucidated its underlying molecular mechanisms. Ethanol was introduced into the liquid diet by mixing it with distilled water at 5% (wt/v), providing 36% of the energy, for nine weeks. Among the three different fractions prepared from the C. lanceolata root, the C. lanceolata methanol extract (CME) exhibited the most remarkable attenuation of alcohol-induced fatty liver with respect to various parameters such as hepatic free fatty acid concentration, body weight loss, and hepatic accumulations of triglyceride and cholesterol. The hepatic gene and protein expression levels were analysed via RT-PCR and Western blotting, respectively. CME feeding significantly restored the ethanol-induced downregulation of the adiponectin receptor (adipoR) 1 and of adipoR2, along with their downstream molecules. Furthermore, the study data showed that CME feeding dramatically reversed ethanol-induced hepatic upregulation of toll-like receptor- (TLR-) mediated signaling cascade molecules. These results indicate that the beneficial effects of CME against alcoholic fatty livers of mice appear to be with adenosine- and adiponectin-mediated regulation of hepatic steatosis and TLR-mediated modulation of hepatic proinflammatory responses.

Cannabinoid CB2 receptors protect against alcoholic liver disease by regulating Kupffer cell polarization in mice

Activation of Kupffer cells plays a central role in the pathogenesis of alcoholic liver disease. Because cannabinoid CB2 receptors (CB2) display potent anti-inflammatory properties, we investigated their role in the pathogenesis of alcoholic liver disease, focusing on the impact of CB2 on Kupffer cell polarization and the consequences on liver steatosis. Wild-type (WT) mice fed an alcohol diet showed an induction of hepatic classical (M1) and alternative (M2) markers. Cotreatment of alcohol-fed mice with the CB2 agonist, JWH-133, decreased hepatic M1 gene expression without affecting the M2 profile. In keeping with this, genetic ablation of CB2 enhanced hepatic induction of M1 gene signature and blunted the induction of M2 markers. CB2 also modulated alcohol-induced fatty liver, as shown by the reduction of hepatocyte steatosis in JWH-133-treated mice and its enhancement in CB2-/- animals. Studies in isolated Kupffer cells and cultured macrophages further demonstrated that CB2 inhibits M1 polarization and favors the transition to an M2 phenotype. In addition, conditioned-medium experiments showed that preventing M1 polarization in CB2-activated macrophages protects from lipid accumulation in hepatocytes. Heme oxygenase-1 (HO-1) mediated the anti-inflammatory effects of CB2 receptors. Indeed, alcohol-fed mice treated with JWH-133 showed increased hepatic expression of macrophage HO-1, as compared to vehicle-treated counterparts. In keeping with this, JWH-133 induced HO-1 expression in cultured macrophages, and the HO-1 inhibitor, zinc protoporphyrin, blunted the inhibitory effect of JWH-133 on lipopolysaccharide-induced nuclear factor-kappa B activation and M1 polarization. Altogether, these findings demonstrate that CB2 receptors display beneficial effects on alcohol-induced inflammation by regulating M1/M2 balance in Kupffer cells, thereby reducing hepatocyte steatosis via paracrine interactions between Kupffer cells and hepatocytes. These data identify CB2 agonists as potential therapeutic agents for the management of alcoholic liver disease.

Effect of oral administration of water-soluble extract from citrus peel (Citrus unshiu) on suppressing alcohol-induced fatty liver in rats

Water-soluble citrus peel extract (WCE) from Citrus unshiu was studied for its anti-alcoholic fatty liver activities through chronic oral administration to Sprague Dawley (SD) rats. WCE, which was prepared by ultrasound-assisted extraction (UAE), was co-supplemented with ethanol (2.87ml/rat/day) at low and high dosages (278 and 576mg/rat/day, respectively) for 6weeks. Ethanol consumption significantly elevated both total cholesterol (TC) and triglyceride (TG) concentrations in the serum of SD rats; otherwise co-administration of WCE lowered both serum TG and TC levels. Ethanol consumption caused a hepatic lipid content of 227mg/g liver after 6weeks whereas co-administration of WCE, especially at high dosage, significantly reduced it to 187mg/g of liver. Analysis of hepatic fatty acids revealed that WCE suppressed conjugation of oleic acid into TG. These results support probable application of WCE as an anti-alcoholic fatty liver agent.

MyD88‐independent pathway plays an important role in alcohol‐induced osteonecrosis

ObjectivesOsteonecrosis of the femoral head (ONF) occurs under steroid therapy or chronic alcohol consumption. Most of patients with alcohol‐induced ONF contract alcoholic fatty liver disease, in the pathogenesis of which LPS, a ligand of TLR4, plays a crucial role. However, the pathogenesis of alcohol‐induced ONF remains unclear. In the present study, we found that feeding alcohol liquid diet for experimental alcoholic fatty liver disease causes ONF and clarified role of proinflammatory responses in the pathogenesis.MethodsMale Wistar rats were fed Lieber DeCarli liquid diet containing 5% ethanol or dextran for 1–6 weeks. Histopathological and biochemical analyses were performed.ResultsAlcohol liquid diet feeding remarkably promoted ONF. The animal had hepatic steatosis, liver dysfunction, and hyperlipidemia as well as many previous reports. Blood IFN gamma was increased in the rat fed with alcohol liquid diet, while adiponectin levels was decreased in the rat. IFN gamma and adiponectin can be related to TLR4 understream pathways via MyD88‐independent and dependent.ConclusionsWe found ONF in the rat fed alcohol liquid diet. The animal showed elevated IFN gamma and decreased adiponectin, suggesting that IFN gamma signaling pathway may play a crucial role in the pathogenesis of alcohol‐induced osteonecrosis of the femoral head.

The Effect of Lycium Barbarum Polysaccharide on Alcohol-Induced Oxidative Stress in Rats

The aim of this study was to investigate the effects of Lycium barbarum Polysaccharide (LBP) on alcohol-induced liver damage in rats. A total of 36 rats were divided into control, ethanol and ethanol + LBP groups. Rats in the ethanol group were fed 7 g ethanol/kg body weight by gastric infusion, three times a day, for 30 consecutive days, while rats in the control group received the same volume of physiological saline instead of ethanol, and rats in ethanol + LBP group were fed both ethanol (7 g/kg body weight) and LBP (300 mg/Kg body weight/day). Alcoholic liver injury was examined by serum ALT and AST activities, alcoholic fatty liver was assessed by lipid levels, and oxidative stress was evaluated by SOD, CAT, GSH-Px, GSH and MDA assays. In the ethanol group, a significant elevation of enzymes and lipid in serum, increased MDA level and depletion of SOD, CAT, GSH-Px and GSH in liver were observed. LBP administration significantly ameliorated liver injury, prevented the progression of alcohol-induced fatty liver, and improved the antioxidant functions when compared with the ethanol group. Histopathological examination of rat liver revealed that LBP administration protected liver cells from the damage induced by ethanol. The results suggest that LBP is a promising agent to protect the liver from hepatotoxicity and fatty liver induced by ethanol intake.

Hepatic Deletion of Smad7 in Mouse Leads to Spontaneous Liver Dysfunction and Aggravates Alcoholic Liver Injury

BackgroundTGF-β has been known to play an important role in various liver diseases including fibrosis and alcohol-induced fatty liver. Smad7 is an intracellular negative regulator of TGF-β signaling. It is currently unclear whether endogenous Smad7 has an effect on liver function and alcoholic liver damage.Methodology/Principal FindingsWe used Cre/loxP system by crossing Alb-Cre mice with Smad7loxP/loxP mice to generate liver-specific deletion of Smad7 with loss of the indispensable MH2 domain. Alcoholic liver injury was achieved by feeding mice with a liquid diet containing 5% ethanol for 6 weeks, followed by a single dose of ethanol gavage. Deletion of Smad7 in the liver was associated with increased Smad2/3 phosphorylation in the liver or upon TGF-β treatment in primary hepatocytes. The majority of mice with liver specific deletion of Smad7 (Smad7liver-KO) were viable and phenotypically normal, accompanied by only slight or no reduction of Smad7 expression in the liver. However, about 30% of Smad7liver-KO mice with high efficiency of Smad7 deletion had spontaneous liver dysfunction, demonstrated as low body weight, overall deterioration, and increased serum levels of AST and ALT. Degeneration and elevated apoptosis of liver cells were observed with these mice. TGF-β-induced epithelial to mesenchymal transition (EMT) was accelerated in Smad7-deleted primary hepatocytes. In addition, alcohol-induced liver injury and steatosis were profoundly aggravated in Smad7 deficient mice, associated with upregulation of critical genes involved in lipogenesis and inflammation. Furthermore, alcohol-induced ADH1 expression was significantly abrogated by Smad7 deletion in hepatocytes.Conclusion/SignificanceIn this study, we provided in vivo evidence revealing that endogenous Smad7 plays an important role in liver function and alcohol-induced liver injury.

Gentiana manshurica Kitagawa Reverses Acute Alcohol-Induced Liver Steatosis through Blocking Sterol Regulatory Element-Binding Protein-1 Maturation

This study was undertaken to investigate the protective effects of Gentiana manshurica Kitagawa (GM) on acute alcohol-induced fatty liver. Mice were treated with ethanol (5 g/kg of body weight) by gavage every 12 h for a total of three doses to induce acute fatty liver. Methanol extract of GM (50, 100, or 200 mg/kg) or silymarin (100 mg/kg) was gavaged simultaneously with ethanol for three doses. GM administration significantly reduced the increases in serum ALT and AST levels, the serum and hepatic triglyceride levels, at 4 h after the last ethanol administration. GM was also found to prevent ethanol-induced hepatic steatosis and necrosis, as indicated by liver histopathological studies. Additionally, GM suppressed the elevation of malondialdehyde (MDA) levels, restored the glutathione (GSH) levels, and enhanced the superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX) activities. The concurrent administration of GM efficaciously abrogated cytochrome P450 2E1 (CYP2E1) induction. Moreover, GM significantly reduced the nuclear translocation of sterol regulatory element-binding protein-1 (nSREBP-1) in ethanol-treated mice. These data indicated that GM possessed the ability to prevent ethanol-induced acute liver steatosis, possibly through blocking CYP2E1-mediated free radical scavenging effects and SREBP-1-regulated fatty acid synthesis. Especially, GM may be developed as a potential therapeutic candidate for ethanol-induced oxidative damage in liver.

Exploring the molecular mechanisms underlying the potentiation of exogenous growth hormone on alcohol-induced fatty liver diseases in mice

BackgroundGrowth hormone (GH) is an essential regulator of intrahepatic lipid metabolism by activating multiple complex hepatic signaling cascades. Here, we examined whether chronic exogenous GH administration (via gene therapy) could ameliorate liver steatosis in animal models of alcoholic fatty liver disease (AFLD) and explored the underlying molecular mechanisms.MethodsMale C57BL/6J mice were fed either an alcohol or a control liquid diet with or without GH therapy for 6 weeks. Biochemical parameters, liver histology, oxidative stress markers, and serum high molecular weight (HMW) adiponectin were measured. Quantitative real-time PCR and western blotting were also conducted to determine the underlying molecular mechanism.ResultsSerum HMW adiponectin levels were significantly higher in the GH1-treated control group than in the control group (3.98 ± 0.71 μg/mL vs. 3.07 ± 0.55 μg/mL; P < 0.001). GH1 therapy reversed HMW adiponectin levels to the normal levels in the alcohol-fed group. Alcohol feeding significantly reduced hepatic adipoR2 mRNA expression compared with that in the control group (0.71 ± 0.17 vs. 1.03 ± 0.19; P < 0.001), which was reversed by GH therapy. GH1 therapy also significantly increased the relative mRNA (1.98 ± 0.15 vs. 0.98 ± 0.15) and protein levels of SIRT1 (2.18 ± 0.37 vs. 0.99 ± 0.17) in the alcohol-fed group compared with those in the control group (both, P < 0.001). The alcohol diet decreased the phosphorylated and total protein levels of hepatic AMP-activated kinase-α (AMPKα) (phosphorylated protein: 0.40 ± 0.14 vs. 1.00 ± 0.12; total protein: 0.32 ± 0.12 vs. 1.00 ± 0.14; both, P < 0.001) and peroxisome proliferator activated receptor-α (PPARα) (phosphorylated protein: 0.30 ± 0.09 vs. 1.00 ± 0.09; total protein: 0.27 ± 0.10 vs. 1.00 ± 0.13; both, P < 0.001), which were restored by GH1 therapy. GH therapy also decreased the severity of fatty liver in alcohol-fed mice.ConclusionsGH therapy had positive effects on AFLD and may offer a promising approach to prevent or treat AFLD. These beneficial effects of GH on AFLD were achieved through the activation of the hepatic adiponectin-SIRT1-AMPK and PPARα-AMPK signaling systems.

Osthole improves alcohol‐induced fatty liver in mice by reduction of hepatic oxidative stress

The aim of our study was to examine the therapeutic effect of osthole, an active constituent isolated from the fruit of Cnidium monnieri (L.) Cusson, on alcohol-induced fatty liver in mice and investigate its potential mechanisms of treatment. A mouse alcoholic fatty liver model was established by feeding 52% alcohol for 4 weeks. These experimental mice were then treated with osthole 10, 20 and 40 mg/kg for 6 weeks. The levels of serum total cholesterol (TC), triglyceride (TG), low density lipoprotein-cholesterol (LDL-C) and hepatic tissue contents of TC, TG and malondialdehyde (MDA) in osthole-treated groups were significantly decreased, while the level of superoxide dismutase (SOD) was significantly increased compared with the model group. Moreover, the cytochrome P450 (CYP) 2E1 and diacylglycerol acyltransferase (DGAT) mRNA expressions in mouse liver were significantly decreased, and the carnitine palmitoyltransferase (CPT) 1A mRNA expression was increased by osthole treatment. Importantly, the histological evaluation of liver demonstrated that osthole dramatically decreased lipid accumulation. It was concluded that osthole was effective in treating mouse alcoholic fatty liver, and its main mechanisms might be related to reduction of hepatic oxidative stress, including the inhibition of reactive oxygen species (ROS) production, enhancement of antioxidative enzyme activity, and reduction of lipid accumulation and peroxidation.

1H and 31P NMR Lipidome of Ethanol‐Induced Fatty Liver

Hepatic steatosis (fatty liver), an early and reversible stage of alcoholic liver disease, is characterized by triglyceride deposition in hepatocytes, which can advance to steatohepatitis, fibrosis, cirrhosis, and ultimately to hepatocellular carcinoma. In the present work, we studied altered plasma and hepatic lipid metabolome (lipidome) to understand the mechanisms and lipid pattern of early-stage alcohol-induced-fatty liver. Male Fischer 344 rats were fed 5% alcohol in a Lieber-DeCarli diet. Control rats were pair-fed an equivalent amount of maltose-dextrin. After 1 month, animals were killed and plasma collected. Livers were excised for morphological, immunohistochemical, and biochemical studies. The lipids from plasma and livers were extracted with methyl-tert-butyl ether and analyzed by 750/800 MHz proton nuclear magnetic resonance (¹H NMR) and phosphorus (³¹P) NMR spectroscopy on a 600 MHz spectrometer. The NMR data were then subjected to multivariate statistical analysis. Hematoxylin and Eosin and Oil Red O stained liver sections showed significant fatty infiltration. Immunohistochemical analysis of liver sections from ethanol-fed rats showed no inflammation (absence of CD3 positive cells) or oxidative stress (absence of malondialdehyde reactivity or 4-hydroxynonenal positive staining). Cluster analysis and principal component analysis of ¹H NMR data of lipid extracts of both plasma and livers showed a significant difference in the lipid metabolome of ethanol-fed versus control rats. ³¹P NMR data of liver lipid extracts showed significant changes in phospholipids similar to ¹H NMR data. ¹H NMR data of plasma and liver reflected several changes, while comparison of ¹H NMR and ³¹P NMR data offered a correlation among the phospholipids. Our results show that alcohol consumption alters metabolism of cholesterol, triglycerides, and phospholipids that could contribute to the development of fatty liver. These studies also indicate that fatty liver precedes oxidative stress and inflammation. The similarities observed in plasma and liver lipid profiles offer a potential methodology for detecting early-stage alcohol-induced fatty liver disease by analyzing the plasma lipid profile.

Adenosine: Tipping the balance towards hepatic steatosis and fibrosis

Fatty liver is commonly associated with alcohol ingestion and abuse. While the molecular pathogenesis of these fatty changes is well understood, the histochemical and pharmacological mechanisms by which ethanol stimulates these molecular changes remain unknown. During ethanol metabolism, adenosine is generated by the enzyme ecto-5'-nucleotidase, and adenosine production and adenosine receptor activation are known to play critical roles in the development of hepatic fibrosis. We therefore investigated whether adenosine and its receptors play a role in the development of alcohol-induced fatty liver. WT mice fed ethanol on the Lieber-DeCarli diet developed hepatic steatosis, including increased hepatic triglyceride content, while mice lacking ecto-5-nucleotidase or adenosine A1 or A2B receptors were protected from developing fatty liver. Similar protection was also seen in WT mice treated with either an adenosine A1 or A2B receptor antagonist. Steatotic livers demonstrated increased expression of genes involved in fatty acid synthesis, which was prevented by blockade of adenosine A1 receptors, and decreased expression of genes involved in fatty acid metabolism, which was prevented by blockade of adenosine A2B receptors. In vitro studies supported roles for adenosine A1 receptors in promoting fatty acid synthesis and for A2B receptors in decreasing fatty acid metabolism. These results indicate that adenosine generated by ethanol metabolism plays an important role in ethanol-induced hepatic steatosis via both A1 and A2B receptors and suggest that targeting adenosine receptors may be effective in the prevention of alcohol-induced fatty liver.

Osthol regulates hepatic PPARα-mediated lipogenic gene expression in alcoholic fatty liver murine

Our previous studies found that osthol, an active constituent isolated from Cnidium monnieri (L.) Cusson (Apiaceae), could ameliorate the accumulation of lipids and decrease the lipid levels in serum and hepatic tissue in alcohol-induced fatty liver mice and rats. The objective of this study was to investigate its possible mechanism of the lipid-lowering effect. A mouse model with alcoholic fatty liver was induced by orally feeding 52% erguotou wine by gavage when they were simultaneously treated with osthol 10, 20, 40 mg/kg for 4 weeks. The BRL cells (rat hepatocyte line) were cultured and treated with osthol at 25, 50, 100, 200 microg/ml for 24h. The mRNA expressions of peroxisome proliferator-activated receptor (PPAR) alpha, diacylglycerol acyltransferase (DGAT), 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase and cholesterol 7 alpha-hydroxylase (CYP7A) in mouse hepatic tissue or cultured hepatocytes were determined by reverse transcription polymerase chain reaction (RT-PCR). After treatment with osthol, the PPAR alpha mRNA expression in mouse liver and cultured hepatocytes was increased in dose dependent manner, while its related target genes for mRNA expression, e.g., DGAT and HMG-CoA reductase, were decreased, the CYP7A was inversely increased. And osthol-regulated mRNA expressions of DGAT, HMG-CoA reductase and CYP7A in the cultured hepatocytes were abrogated after pretreatment with specific inhibitor of PPAR alpha, MK886. It was concluded that osthol might regulate the gene expressions of DGAT, HMG-CoA reductase and CYP7A via increasing the PPAR alpha mRNA expression.

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.

The beneficial effect of metadoxine (pyridoxine-pyrrolidone-carboxylate) in the treatment of fatty liver diseases

Hepatic steatosis involves an imbalance between the processes of the hepatocytes’ lipid uptake and lipid elimination, an overproduction results in the accumulation of excess triglycerides in the cells of the liver. Normally about 5% of the cells contain triglyceride; in steatosis this may exceed 50%. Under 50% the condition is called fatty infiltration, and over 50% it is called fatty liver. In mild forms this does not necessarily lead to disorders in cell functions, but in more severe forms it does; it often precedes the death of the cell. Fatty liver can be considered a pathologic condition which makes the liver more susceptible to other toxic influences. It is not a genuine disease; in most cases it is associated with a noxious state or other pathologic process. Alcohol-induced fatty liver is a current epidemie. The abnormal accumulation of fat in parenchymal organs, including the liver, is called fatty transformation or steatosis. Alone and limited to a certain degree of severity (the appearance of fibrosis), it represents a reversible damage; upon cessation of the underlying cause the liver clears its excess triglyceride content. The treatment is to be aimed at the underlying process; up to now there is no known specific medicine that could clearly reduce the fat accumulated in the hepatocytes. Although the etiologic factors of these diseases differ from each other, the pathological changes in the liver are very similar, thus certain drugs could be equally effective for treating them both. Metadoxine is one of those drugs, mainly due to its liver-protective effect against damage from free radicals. As an effective antioxidant, metadoxine regulates glutathione levels in the liver and throughout the body, thus positively influencing the maintenance of systemic redox homeostasis. The authors discuss in detail the effect of metadoxine in the treatment of fatty liver diseases (alcoholic and non-alcoholic), they also review the effect of metadoxine in both in vitro and in vivo experimental conditions.

알코올성 지방간과 비알코올성 지방간 성인에 있어 혈청 철 표지자, 심장 표지자, 생화학적 표지자의 차이

비록 음주가 간손상을 일으키는 지방간의 원인이 되긴 하나 다른 인자들 역시 지방간의 원인이 된다. 우리는 알코올성 지방간(알코올군) 및 비알코올성 지방간 남성(비알코올군)에 있어 철 표지자, 심장표지자, 그리고 생화학적 표지자의 변화와 차이를 연구하였다. 알코올군이 비알코올군 보다 신체지수, 수축기 및 확장기 혈압, 좌우 안압이 유의하게 더 높았다. 또한 혈색소 농도, 적혈구 용적률, 평균 적혈구 혈색소량, 평균 적혈구혈색소 농도, 단구 수 역시 알코올군이 비알코올군 보다 유의하게 더 높았다. 생화학적 지수인 alanine aminotransferase, <TEX>${\gamma}$</TEX>-glutamyltranspeptidase, 총콜레스테롤, 중성지방, 저밀도콜레스테롤, 혈당, 크레아티닌, 요산 등도 알코올군이 비알코올군 보다 유의하게 높았고, 철 지수인 철, 총철결합능, 페리틴 농도 역시 알코올군이 의미있게 더 높았다. 이러한 결과들은 장기적인 알코올 기인성 지방간이 비음주 지방간에 비해 혈청 철농도, 심혈관 표지자, 그리고 생화학적 표지자들을 더 상승시키며, 이는 심혈관 질환 및 대사성 증후군과 같은 성인병에 노출될 가능성이 보다 높을 수 있음을 시사하고 있다. Although alcohol drinking may cause fatty liver to induce hepatocytic injury, other factors lead to it. We designed this study to investigate the differences in serum iron, cardiac, and biochemical indices in men with fatty liver and the difference between alcohol drinkers (Alcohol group) and non-drinkers (Non-alcohol group). The alcohol group had higher body indices than the non-alcohol group. Systolic and diastolic blood pressure (SBP and DBP), and right and left intraocular pressure in the alcohol group were higher than those in the non-alcohol group. Hemoglobin, hematocrit, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and monocyte counts were higher in the alcohol group than in the non-alcohol group. Alanine aminotransferase, <TEX>${\gamma}$</TEX>-glutamyltranspeptidase, total cholesterol, triglyceride, low-density lipoprotein cholesterol, glucose, creatinine, uric acid, iron, total iron binding capacity, and ferritin levels in the alcohol group were greater than those in the non-alcohol group. The present data reveals that alcohol-induced fatty liver has more elevated level of iron indices than in non-alcohol fatty liver as well as biochemical and cardiac indices, indicating that alcohol- induced fatty liver may cause possibility of adult diseases including cardiovascular disease and metabolic syndrome.

Adenosine signaling contributes to ethanol-induced fatty liver in mice

Fatty liver is commonly associated with alcohol ingestion and abuse. While the molecular pathogenesis of these fatty changes is well understood, the biochemical and pharmacological mechanisms by which ethanol stimulates these molecular changes remain unknown. During ethanol metabolism, adenosine is generated by the enzyme ecto-5'-nucleotidase, and adenosine production and adenosine receptor activation are known to play critical roles in the development of hepatic fibrosis. We therefore investigated whether adenosine and its receptors play a role in the development of alcohol-induced fatty liver. WT mice fed ethanol on the Lieber-DeCarli diet developed hepatic steatosis, including increased hepatic triglyceride content, while mice lacking ecto-5'-nucleotidase or adenosine A1 or A2B receptors were protected from developing fatty liver. Similar protection was also seen in WT mice treated with either an adenosine A1 or A2B receptor antagonist. Steatotic livers demonstrated increased expression of genes involved in fatty acid synthesis, which was prevented by blockade of adenosine A1 receptors, and decreased expression of genes involved in fatty acid metabolism, which was prevented by blockade of adenosine A2B receptors. In vitro studies supported roles for adenosine A1 receptors in promoting fatty acid synthesis and for A2B receptors in decreasing fatty acid metabolism. These results indicate that adenosine generated by ethanol metabolism plays an important role in ethanol-induced hepatic steatosis via both A1 and A2B receptors and suggest that targeting adenosine receptors may be effective in the prevention of alcohol-induced fatty liver.

알코올 투여 흰쥐의 간 조직 산화스트레스에 미치는 글루타티온 고함유 효모 Saccharomyces cerevisiae FF-8 균체의 영향

글루타티온은 간 질환용 치료제 내지는 영양보충제로 시판되고 있다. 이전 실험에서 글루타티온 고함유 효모 Saccharomyces cerevisiae FF-8 균체(FF-8GY) 투여가 사염화탄소 및 알코올성 유발 간독성 개선효과를 나타내었다. 따라서, 알코올성 지방간의 산화 스트레스에 미치는 영향을 조사하기 위하여 시판되고 있는 글루타티온 고함유 효모 추출물(GYE)과 본 실험실에서 분리한 글루타티온 고함유 효모 FF-8GY을 비교실험 하였다. FF-8GY 또는 GYE 투여에 의한 간 조직 중의 산화스트레스 측정지표로서는 과산화지질(TBARS) 및 글루타티온 함량을 측정하였다. TBARS 농도는 간 조직 homogenize 분획에서 알코올 투여 대조군에 비해 FF-8GY 투여 실험군에서 5%수준에서 유의적으로 감소하였으며, GYE 투여에 의해서는 감소경향을 보였다. 간 조직 microsomal 및 mitochondria 분획에서도 같은 경향이 관찰되었다. 이때 간 조직 중의 글루타티온 농도는 정상군 보다 알코올 투여 대조군에서 5%수준에서 유의적으로 감소하였으며, 이러한 감소는 GYE 투여에 의해 더욱 감소되었으나 FF-8GY 투여에 의해서 정상군 수준까지 회복되는 것으로 나타났다. 한편 간조직의 손상정도를 나타내는 또 하나의 지표인 혈청 총단백질 및 알부민 농도는 알코올 처리 대조군에서 낮게 나타난 반면 FF-8GY 투여에 의해 정상군 수준 이상으로 증가하는 것으로 나타났다. 이상의 결과에서 글루타티온 고함유 효모 Saccharomyces cerevisiae FF-8 균체(FF-8GY)의 투여에 따른 알코올성 유발 산화스트레스의 경감 효과는 시판되고 있는 글루타티온 고함유 효모 추출물 보다 더욱 현저한 개선 효과가 있는 것으로 확인되었다. Glutathione is a well known chemotherapeutic agent for liver disease and is a popular nutritional supplement in the United States. Previous our studies reported the suppressive effects of glutathione-enriched Saccharomyces cerevisiae FF-8 strain (FF-8GY) on carbon tetrachloride- and alcohol-induced hepatotoxicity. The primary objective of this study was to investigate the comparative effects of FF-8GY and commercially available glutathione-enriched yeast extract (GYE) against the oxidative stress in alcohol-induced fatty liver of rats. The lipid peroxidative index (thiobarbituric acid-reactive substances, TBARS) and antioxidant status (reduced glutathione level) were used to monitor those protective roles of FF-8GY or GYE treatment. When the rat was treated alcohol, the TBARS levels in the whole liver and the subfractions of microsomal and mitochondria were significantly increased but these were significantly decreased by FF-8GY treatment and tended to be lowered by GYE treatment. The concentration of hepatic glutathione is known to be closely associated with antioxidant system and this was slightly deplete in the alcohol-induced rats, but this was recovered by treating with FF-8GY. However, the glutathione concentration was more significantly decreased in the GYE supplementation in alcohol feeding rats. Alcohol treatment also negatively affected the serum total protein and albumin, but these were significantly increased near normal levels in FF-8GY coadministered rats. These results suggest that glutathione-enriched Saccharomyces cerevisiae FF-8 strain may have positively mediate the alcohol-induced oxidative stress, and this effect was more pronounced in FF-8GY compared to GYE.

Prevention of alcoholic fatty liver and mitochondrial dysfunction in the rat by long-chain polyunsaturated fatty acids

We reported that reduced dietary intake of polyunsaturated fatty acids (PUFA) such as arachidonic (AA,20:4n6,omega-6) and docosahexaenoic (DHA,22:6n3,omega-3) acids led to alcohol-induced fatty liver and fibrosis. This study was aimed at studying the mechanisms by which a DHA/AA-supplemented diet prevents alcohol-induced fatty liver. Male Long-Evans rats were fed an ethanol or control liquid-diet with or without DHA/AA for 9 weeks. Plasma transaminase levels, liver histology, oxidative/nitrosative stress markers, and activities of oxidatively-modified mitochondrial proteins were evaluated. Chronic alcohol administration increased the degree of fatty liver but fatty liver decreased significantly in rats fed the alcohol-DHA/AA-supplemented diet. Alcohol exposure increased oxidative/nitrosative stress with elevated levels of ethanol-inducible CYP2E1, nitric oxide synthase, nitrite and mitochondrial hydrogen peroxide. However, these increments were normalized in rats fed the alcohol-DHA/AA-supplemented diet. The number of oxidatively-modified mitochondrial proteins was markedly increased following alcohol exposure but significantly reduced in rats fed the alcohol-DHA/AA-supplemented diet. The suppressed activities of mitochondrial aldehyde dehydrogenase, ATP synthase, and 3-ketoacyl-CoA thiolase in ethanol-exposed rats were also recovered in animals fed the ethanol-DHA/AA-supplemented diet. Addition of DHA/AA prevents alcohol-induced fatty liver and mitochondrial dysfunction in an animal model by protecting various mitochondrial enzymes most likely through reducing oxidative/nitrosative stress.

Effect of Transgenic Extrahepatic Expression of Betaine‐Homocysteine Methyltransferase on Alcohol or Homocysteine‐Induced Fatty Liver

Chronic alcohol feeding induces hyperhomocysteinemia (HHcy). Previously, we reported a protective role of betaine-homocysteine methyltransferase (BHMT) in homocysteine-induced injury in cultured hepatocytes. In this study, we investigated the direct role of BHMT in alcohol or homocysteine-induced liver injury. Betaine-homocysteine methyltransferase transgenic (Tg) mice were generated. Comparisons were made between the Tg and wild type (WT) mice in their response to intragastric alcohol infusion or to oral feeding of a high methionine low folate diet (HMLF). Expression of the Tg BHMT was increased in organs peripheral to the liver. The alcohol infusion for 4 weeks increased: plasma ALT by 5-fold in WT mice and 2.7-fold in Tg mice; plasma homocysteine by 7-fold in WT mice and 2-fold in Tg mice; liver triglycerides by 4-fold in WT mice and 2.5-fold in Tg mice. The alcohol-induced fatty liver was more severe in WT than in Tg mice based on H&E staining. The HMLF feeding for 4 weeks increased plasma ALT by 2-fold in WT mice and 1-fold in Tg mice; plasma homocysteine by 21-fold in WT mice and 3.3-fold in Tg mice; liver triglycerides by 2.5-fold in WT mice and 1.5-fold in Tg mice. HMLF induced accumulation of macro fat droplets in WT but not Tg mice. Betaine supplementation decreased partially the alcohol or HMLF-induced increase of ALT, homocysteine and liver lipids in WT mice. However, Tg mice were normal when fed both HMLF and betaine. In WT mice, both alcohol and HMLF induced moderate increase of sterol regulatory element binding protein 1 (SREBP1) protein which was partially reduced by betaine supplementation. In Tg mice, alcohol but not HMLF increased SREBP1. Carbohydrate responsive element-binding protein was increased by alcohol in either WT or Tg mice which was not affected by betaine supplementation. Ratio of S-adenosylmethionine (SAM) to S-adenosylhomocysteine (SAH) was reduced by 50% in WT and by 20% in Tg mice fed alcohol. Ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE) was reduced in WT but not Tg mice fed alcohol. Changes in PE methyltransferase activities were not detected in response to alcohol or HMLF feeding but were increased by betaine. The BHMT Tg mice are resistant to alcohol or HMLF-induced HHcy and liver steatosis indicating that peripheral metabolism of homocysteine protected the liver without a direct effect of BHMT in the liver. Multiple mechanisms are involved in protection by betaine including increased SAM/SAH and PC/PE ratios.