Alcohol-induced Hepatic Lipid Accumulation Research Articles

Lactiplantibacillus plantarum P101 Alleviated Alcohol-Induced Hepatic Lipid Accumulation in Mice via AMPK Signaling Pathway: Gut Microbiota and Metabolomics Analysis.

Mitigating steatosis is essential for delaying the progression of alcoholic liver disease. The effect and mechanism of Lactiplantibacillus plantarum P101 (LP.P101) on alleviating alcohol-induced hepatic lipid accumulation were investigated in our study. The mouse model was constructed by a short-term (10-day)-plus-binge ethanol feeding and gavaged with 108 CFU/mL of LP.P101 daily. Lipid droplet in the liver was significantly reduced by LP.101 intervention on AMPK activation. However, when AMPK was inhibited by dorsomorphin, the levels of related indicators (ALT, TG, etc.) and the expression levels of AMPK and relevant genes in the liver converged to that of the alcohol-fed group. Compared with the alcohol-fed group, LP.P101 reduced the relative abundance of Firmicutes and increased that of Bacteroidetes. Parabacteroides merdae was negatively correlated with lipid accumulation, and unclassified Negativibacillus was negatively associated with AMPK activation. Importantly, LP.P101 modified the compositions of the serum metabolites. The potential biomarker stercobilinogen was positively correlated with AMPK activation and negatively associated with lipid accumulation. This work confirmed that LP.P101 attenuated alcohol-induced hepatic lipid accumulation in mice through AMPK activation, and the alterations in gut microbiota and metabolites may play a significant role on AMPK activation.

Loss of Dec1 inhibits alcohol-induced hepatic lipid accumulation and circadian rhythm disorder.

Chronic alcohol exposure increases liver damage such as lipid accumulation and hepatitis, resulting in hepatic cirrhosis. Chronic alcohol intake is known to disturb circadian rhythms in humans and animals. DEC1, a basic helix-loop-helix transcription factor, plays an important role in the circadian rhythm, inflammation, immune responses, and tumor progression. We have previously shown that Dec1 deficiency inhibits stresses such as periodontal inflammation and perivascular fibrosis of the heart. However, the significance of Dec1 deficiency in chronic alcohol consumption remains unclear. In the present study, we investigated whether the biological stress caused by chronic alcohol intake is inhibited in Dec1 knockout mice. We treated control and Dec1 knockout mice for three months by providing free access to 10% alcohol. The Dec1 knockout mice consumed more alcohol than control mice, however, we observed severe hepatic lipid accumulation and circadian rhythm disturbance in control mice. In contrast, Dec1 knockout mice exhibited little effect on these outcomes. We also investigated the expression of peroxisome proliferator-activated receptors (PPARs) and AMP-activated protein kinase (AMPK), which are involved in the regulation of fatty acid metabolism. Immunohistochemical analysis revealed increases of phosphorylation AMPK and PPARa but decreases PPARg in Dec1 knockout mice compared to that in control mice. This indicates a molecular basis for the inhibition of hepatic lipid accumulation in alcohol-treated Dec1 knockout mice. These results suggest a novel function of Dec1 in alcohol-induced hepatic lipid accumulation and circadian rhythm disorders.

Lipidomics approach in alcoholic liver disease mice with sphingolipid metabolism disorder: Alleviation using sea cucumber phospholipids

The sea cucumber phospholipids (SC-PLs) are involved in regulating multiple chronic lipid metabolism disorders, but their mechanism remains unknown. Herein, ethanol diet-induced C57BL/6N mice were established as alcoholic liver disease (ALD) models. Dietary intake of SC-PLs, including plasmenyl phosphatidylethanolamine (PlsEtn) and plasmanyl phosphatidylcholine (PlsCho), alleviated alcohol-induced hepatic lipid accumulation and abnormal elevation of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The metabolic disorders of sphingolipid were relieved by SC-PLs in the livers of ALD mice. Notably, PlsEtn could improve anomalies more effectively than PlsCho. The mechanism results showed that SC-PLs inhibited the abnormal de novo synthesis of SLs and alleviated the dynamic transformation and accumulation of ceramide (Cer) and sphingomyelin. SC-PLs protected the liver by avoiding liver cells from Cer's pro-apoptotic. Additionally, seven sphingomyelin and four ceramide molecular species were identified as potential lipid biomarkers in the liver of ALD mice. Improving SLs homeostasis in ALD mice liver might be a critical pathway to explain the SC-PLs hepatoprotective effect.

Baicalin ameliorates alcohol-induced hepatic steatosis by suppressing SREBP1c elicited PNPLA3 competitive binding to ATGL

Baicalin is a flavonoid compound abundant in multiple edible and medicinal plants such as Scutellaria baicalensis Georgi. In this study, we provide evidence to support the fact that baicalin ameliorates alcohol-induced hepatic steatosis via regulating SREBP1c elicited PNPLA3 competitive binding to ATGL. Results showed that baicalin significantly attenuated the development of metabolic disorders and hepatic steatosis in alcohol-induced rats after four weeks of treatment. It was evident that baicalin treatment significantly normalized the serous contents of hepatic triglyceride (TG), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), and attenuated the increase of hepatic vacuolization and Oil Red O staining area caused by alcohol. Meanwhile, baicalin relieves alcohol-induced hepatic fibrosis by masson staining and RT-qPCR analysis. Mechanistically, alcohol aggravated the nuclear expression of SREBP1c, which contributed to the high expression of PNPLA3 and FASN, thereby enhancing the binding of PNPLA3 to ABHD5, and indirectly impairing the binding ability between ATGL and ABHD5, ultimately causing a decline in the hydrolysis capacity in liver lipid droplets. As expected, these alcohol-induced pathobolism were reversed by baicalin treatment both in vivo and in vitro. In conclusion, this study has demonstrated that baicalin can protect against alcohol-induced hepatic lipid accumulation by activating hepatic lipolysis via suppressing SREBP1c elicited PNPLA3 competitive binding to ATGL. Baicalin is a promising natural product for preventing alcohol-induced hepatic steatosis.

Transgenic overexpression of CTRP3 does not prevent alcohol induced hepatic steatosis in female mice.

Alcoholic liver disease (ALD) is one of the leading causes of morbidity and mortality from hepatic complications. C1q/TNF-related protein 3 (CTRP3) is an adiponectin paralog and, in male mice, increased levels of circulating CTRP3 prevents ALD. Therefore, the purpose of this study was to replicate the observed hepatoprotective effect of elevated circulating CTRP3 levels in female mice. Twelve-week-old female wildtype and CTRP3 overexpressing transgenic mice were fed the Lieber-DeCarli alcohol-containing liquid diet (5% vol/vol) for 6 weeks. Unlike the previous study with male mice, CTRP3 overexpression provided no attenuation to alcohol-induced hepatic lipid accumulation, cytokine production, or overall mortality. In conclusion, there appears to be a clear sex-specific effect of CTRP3 in response to alcohol consumption that needs to be explored further.

Protective Effects of Methoxsalen Supplementation on Chronic Alcohol-Induced Osteopenia and Steatosis in Rats.

Osteopenia or osteoporosis occurs frequently in alcoholics and patients with alcoholic fatty liver disease. Methoxsalen (MTS), 8-methoxypsoralen, improved osteoporosis in ovariectomized and diabetic mouse models; however, its effects on alcohol-induced osteopenia and steatosis have not been reported. This study examined the effects of MTS on alcohol-induced bone loss and steatosis. Rats in the alcohol groups were fed a Liber-DeCarli liquid diet containing 36% of its calories as alcohol. MTS was at 0.005% in their diet, while alendronate (positive control; 500 μg/kg BW/day) was administered orally for eight weeks. The pair-fed group received the same volume of isocaloric liquid diet containing dextrin-maltose instead of alcohol as the alcohol control group consumed the previous day. In the alcohol-fed rats, the MTS and alendronate increased the bone volume density, bone surface density and trabecular number, while the bone specific surface, trabecular separation and structure model index were decreased in the tibia. MTS down-regulated tibial tartrate-resistant acid phosphatase 5 (TRAP) expression compared to the alcohol control group. MTS or alendronate prevented chronic alcohol-induced hepatic lipid accumulation and the triglyceride level in the alcohol-fed rats by decreasing the lipogenic enzyme activities and increasing the fatty acid oxidation enzyme activities. MTS reduced significantly the serum levels of alcohol, TRAP and tumor necrosis factor-α compared to the alcohol control group. Overall, these results suggest that MTS is likely to be an alternative agent for alcoholic osteopenia and hepatosteatosis.

Neuronal modulation of hepatic lipid accumulation induced by bingelike drinking.

Excessive alcohol consumption, including binge drinking, is a common cause of fatty liver disease. Binge drinking rapidly induces hepatic steatosis, an early step in the pathogenesis of chronic liver injury. Despite its prevalence, the process by which excessive alcohol consumption promotes hepatic lipid accumulation remains unclear. Alcohol exerts potent effects on the brain, including hypothalamic neurons crucial for metabolic regulation. However, whether or not the brain plays a role in alcohol-induced hepatic steatosis is unknown. In the brain, alcohol increases extracellular levels of adenosine, a potent neuromodulator, and previous work implicates adenosine signaling as being important for the development of alcoholic fatty liver disease. Acute alcohol exposure also increases both the activity of agouti-related protein (AgRP)-expressing neurons and AgRP immunoreactivity. Here, we show that adenosine receptor A2B signaling in the brain modulates the extent of alcohol-induced fatty liver in mice and that both the AgRP neuropeptide and the sympathetic nervous system are indispensable for hepatic steatosis induced by bingelike alcohol consumption. Together, these results indicate that the brain plays an integral role in alcohol-induced hepatic lipid accumulation and that central adenosine signaling, hypothalamic AgRP, and the sympathetic nervous system are crucial mediators of this process.

Vitamin D Deficiency Attenuates Acute Alcohol-Induced Hepatic Lipid Accumulation in Mice.

Vitamin D deficiency has been frequently reported in chronic liver disease. However, its influence on hepatic lipid accumulation in alcoholic liver disease remains unclear. The present study investigated the effects of vitamin D deficiency on acute alcohol-induced hepatic lipid metabolism in mice. Mice were fed with vitamin D deficient diet, in which vitamin D was depleted for 12 weeks to establish an animal model of vitamin D deficiency. Some mice were administered a single gavage of alcohol (4 g/kg bodyweight) before they were euthanized. Results show that feeding mice with vitamin D deficient diet did not induce hepatic lipid accumulation. In contrast, vitamin D deficiency markedly reduced alcohol-induced triacylglycerol (TAG) content and prevented hepatic lipid accumulation. Moreover, vitamin D deficiency significantly attenuated alcohol-induced sterol-regulated element-binding protein (SREBP)-1c activation, which regulates genes for hepatic fatty acid (FA) and TAG synthesis, and the expression of its target genes fatty acid synthase (Fasn) and acetyl-coenzyme- A carboxylase (Acc). In addition, vitamin D deficiency alleviated alcohol-induced downregulation of hepatic nuclear peroxisome proliferator-activated receptor (PPAR)α, which governs FA transport and β-oxidation, and the expression of Carnitine palmitoyltransferase (Cpt)-1α, cytochrome P450, family 4, subfamily a, polypeptide (Cyp4a)10, and Cyp4a14, which are key enzymes for hepatic fatty acids β-oxidation and ω-oxidation. Taken together, these results suggest that vitamin D deficiency is not a direct risk factor for hepatic lipid accumulation. Vitamin D deficiency alleviates acute alcohol-induced hepatic lipid accumulation through inhibiting hepatic de novo fatty acid syntheses and promoting fatty acid β-oxidation and ω-oxidation.

Orally administration of Neolentinus lepideus extracts attenuated ethanol induced accumulation of hepatic lipid in mice.

In this study, we examined the effects of the water extract of Neolentinus lepideus (WENL), an edible mushroom, on ethanol-induced hepatic lipid accumulation. Ethanol-induced oil red O-positive spots on AML-12 hepatocytes were attenuated by WENL treatment. Furthermore, the oral administration of WENL in acute and chronic ethanol-fed mouse models resulted in the decrease in blood triglyceride and the accumulation of lipid droplets in the liver. Interestingly, the transcriptional expression related to lipid metabolisms, such as sterol regulatory element-binding protein 1, and cytochrome P450 2E1, was decreased by WENL treatment in both ethanol-induced AML-12 hepatocytes and our chronic ethanol-fed mouse models. In addition, WENL effectively attenuated the ethanol induced activation of MAP kinases and NF-κB in AML-12 hepatocytes. Taken together, our results suggested that WENL can be effective in alleviating alcohol-induced hepatic lipid accumulation and may be used as potential candidate for the prevention of alcoholic fatty liver disease.

Transgenic overexpression of CTRP3 prevents alcohol-induced hepatic triglyceride accumulation.

This study tested the ability of a novel adipose tissue derived cytokine, C1q TNF-related protein-3 (CTRP3), to prevent alcohol-induced hepatic lipid accumulation, or alcoholic fatty liver disease (ALD). Previous work has demonstrated that CTRP3 is effective at preventing high-fat diet-induced fatty liver; however, the potential of CTRP3 to inhibit ALD has not been explored. To test the potential protective effects of CTRP3, transgenic mice overexpressing CTRP3 (Tg) or wild-type littermates (WT) were subjected to one of two different models of ALD. In the first model, known as the NIAAA model, mice were fed control or alcohol-containing liquid diets (5% vol/vol) for 10 days followed by a single gavage of ethanol (5 g/kg). In the second model, the chronic model, mice were fed control or alcohol-containing diets for 6 wk with no gavage. This study found that CTRP3 reduced triglyceride accumulation in the chronic model of alcohol consumption by ~50%, whereas no reduction was observed in the NIAAA model. Further analysis of isolated primary hepatocytes from WT and Tg mice demonstrated that CTRP3 increased oxygen consumption in the presence of fatty acids, indicating that CTRP3 increases hepatic fatty acid utilization. In conclusion, this study indicates that CTRP3 attenuates hepatic triglyceride accumulation in response to long-term chronic, but not short-term, alcohol consumption.

Mitochondria-targeted ubiquinone (MitoQ) enhances acetaldehyde clearance by reversing alcohol-induced posttranslational modification of aldehyde dehydrogenase 2: A molecular mechanism of protection against alcoholic liver disease

Alcohol metabolism in the liver generates highly toxic acetaldehyde. Breakdown of acetaldehyde by aldehyde dehydrogenase 2 (ALDH2) in the mitochondria consumes NAD+ and generates reactive oxygen/nitrogen species, which represents a fundamental mechanism in the pathogenesis of alcoholic liver disease (ALD). A mitochondria-targeted lipophilic ubiquinone (MitoQ) has been shown to confer greater protection against oxidative damage in the mitochondria compared to untargeted antioxidants. The present study aimed to investigate if MitoQ could preserve mitochondrial ALDH2 activity and speed up acetaldehyde clearance, thereby protects against ALD. Male C57BL/6J mice were exposed to alcohol for 8 weeks with MitoQ supplementation (5mg/kg/d) for the last 4 weeks. MitoQ ameliorated alcohol-induced oxidative/nitrosative stress and glutathione deficiency. It also reversed alcohol-reduced hepatic ALDH activity and accelerated acetaldehyde clearance through modulating ALDH2 cysteine S-nitrosylation, tyrosine nitration and 4-hydroxynonenol adducts formation. MitoQ ameliorated nitric oxide (NO) donor-mediated ADLH2 S-nitrosylation and nitration in Hepa-1c1c7 cells under glutathion depletion condition. In addition, alcohol-increased circulating acetaldehyde levels were accompanied by reduced intestinal ALDH activity and impaired intestinal barrier. In accordance, MitoQ reversed alcohol-increased plasma endotoxin levels and hepatic toll-like receptor 4 (TLR4)-NF-κB signaling along with subsequent inhibition of inflammatory cell infiltration. MitoQ also reversed alcohol-induced hepatic lipid accumulation through enhancing fatty acid β-oxidation. Alcohol-induced ER stress and apoptotic cell death signaling were reversed by MitoQ. This study demonstrated that speeding up acetaldehyde clearance by preserving ALDH2 activity critically mediates the beneficial effect of MitoQ on alcohol-induced pathogenesis at the gut-liver axis.

Suppression of PPARγ-mediated monoacylglycerol O-acyltransferase 1 expression ameliorates alcoholic hepatic steatosis.

Alcohol consumption is one of the major causes of hepatic steatosis, fibrosis, cirrhosis, and superimposed hepatocellular carcinoma. Ethanol metabolism alters the NAD+/NADH ratio, thereby suppressing the activity of sirtuin family proteins, which may affect lipid metabolism in liver cells. However, it is not clear how long-term ingestion of ethanol eventually causes lipid accumulation in liver. Here, we demonstrate that chronic ethanol ingestion activates peroxisome proliferator-activated receptor γ (PPARγ) and its target gene, monoacylglycerol O-acyltransferase 1 (MGAT1). During ethanol metabolism, a low NAD+/NADH ratio repressed NAD-dependent deacetylase sirtuin 1 (SIRT1) activity, concomitantly resulting in increased acetylated PPARγ with high transcriptional activity. Accordingly, SIRT1 transgenic mice exhibited a low level of acetylated PPARγ and were protected from hepatic steatosis driven by alcohol or PPARγ2 overexpression, suggesting that ethanol metabolism causes lipid accumulation through activation of PPARγ through acetylation. Among the genes induced by PPARγ upon alcohol consumption, MGAT1 has been shown to be involved in triglyceride synthesis. Thus, we tested the effect of MGAT1 knockdown in mice following ethanol consumption, and found a significant reduction in alcohol-induced hepatic lipid accumulation. These results suggest that MGAT1 may afford a promising approach to the treatment of fatty liver disease.

알코올성 지방간을 유발시킨 마우스에서 유산균 발효 마늘추출물의 간 보호 효과

In this study, we investigated the hepatoprotective effects of garlic extracts fermented with Lactobacillus plantarum on alcohol-induced fatty liver damage in C57BL/6J mice. The weight of liver tissue of the lactic acid-fer- mented garlic extract (LAFGE) diet groups decreased in a dose-dependent manner compared to that of the normal diet group. The activities of typical serum enzymes such as ALT, AST, and ALP were low in the LAFGE 200 mg/kg administered group. The LAFGE 200 mg/kg administered group significantly decreased values of TBIL and DBIL, which are an important index of liver damage. LAFGE also ameliorated alcohol-induced hepatic lipid accumulation in histological analysis dose-dependently. In addition, total GSH and reduced GSH levels in LAFGE-treated groups were gradually recovered up to normal levels. The present study revealed that LAFGE improved unique tastes and odors of raw garlic through lactic acid fermentation technology and thus could be a commercially potential material for hepatoprotective functional foods against alcoholic fatty liver.

Scopoletin prevents alcohol-induced hepatic lipid accumulation by modulating the AMPK–SREBP pathway in diet-induced obese mice

ObjectiveThis study investigated the effects of scopoletin on alcohol-induced hepatic lipid accumulation in diet-induced obese mice and its mechanism. Material/MethodsAlcohol (25% v/v, 5g/kg body weight) was orally administered once a day for 6 weeks to mice fed with a high-fat diet (35%kcal) with or without scopoletin (0.05%, wt/wt). ResultsScopoletin reduced plasma acetaldehyde, fatty acid, total cholesterol, triglyceride and insulin levels, hepatic lipid and droplets and fasting blood glucose levels that were increased by alcohol. Scopoletin significantly activated hepatic AMPK and inhibited ACC and SREBP-1c and the activities of lipogenic enzymes, such as FAS, PAP and G6PD compared to the alcohol control group. Moreover, scopoletin significantly inhibited hepatic CYP2E1 activity and protein levels but elevated the activities of SOD, CAT, GSH-Px and GST and the levels of GSH compared to the alcohol control group. The hepatic lipid peroxide level was significantly lowered by scopoletin supplementation in alcohol-administered obese mice. ConclusionsTaken together, these results suggested that scopoletin can ameliorate alcohol-induced hepatic lipid accumulation by modulating AMPK–SREBP pathway-mediated lipogenesis in mice fed a high-fat diet.

Preservation of Hepatocyte Nuclear Factor‐4α Contributes to the Beneficial Effect of Dietary Medium Chain Triglyceride on Alcohol‐Induced Hepatic Lipid Dyshomeostasis in Rats

Alcohol consumption is a major cause of fatty liver, and dietary saturated fats have been shown to protect against alcoholic fatty liver. This study investigated the mechanisms of how dietary saturated fat may modulate alcohol-induced hepatic lipid dyshomeostasis. Male Sprague Dawley rats were pair-fed with 3 isocaloric liquid diets, control, alcohol, and medium chain triglyceride (MCT)/alcohol, respectively, for 8weeks. The control and alcohol diets were based on the Lieber-DeCarli liquid diet formula with 30% total calories derived from corn oil (rich in unsaturated long chain fatty acids). The corn oil was replaced by MCT, which consists of exclusive saturated fatty acids, in the MCT/alcohol diet. HepG2 cell culture was conducted to test the effects of unsaturated fatty acids on hepatocyte nuclear factor-4α (HNF4α) and the role of HNF4α in regulating hepatocyte lipid homeostasis. Alcohol feeding caused significant lipid accumulation, which was attenuated by dietary MCT. The major effect of alcohol on hepatic gene expression is the up-regulation of CYP4A1, CD36, and GPAT3, and down-regulation of apolipoprotein B (ApoB). Dietary MCT further up-regulated CYP4A1 gene, normalized ApoB gene, and up-regulated MTTP and SCD1 genes. The protein level of HNF4α, a master transcription factor of the liver, was reduced by alcohol feeding, which was normalized by dietary MCT. Fatty acid profiling demonstrated that alcohol feeding dramatically increased hepatic unsaturated long chain fatty acyl species, particularly linoleic acid and oleic acid, which was attenuated by dietary MCT. Dietary MCT attenuated alcohol-reduced serum triglyceride level and modulated the fatty acid composition of the serum triglycerides. Cell culture study demonstrated polyunsaturated linoleic acid rather than monounsaturated oleic acid inactivated HNF4α in HepG2 cells. Knockdown of HNF4α caused lipid accumulation in HepG2 cells due to dysregulation of very low density lipoprotein secretion. Results suggest that dietary MCT prevents alcohol-induced hepatic lipid accumulation, at least partially, through reducing hepatic polyunsaturated long chain fatty acids and preserving HNF4α.

Hepatocyte-specific hypoxia-inducible factor-1α is a determinant of lipid accumulation and liver injury in alcohol-induced steatosis in mice

Chronic alcohol causes hepatic steatosis and liver hypoxia. Hypoxia-regulated hypoxia-inducible factor 1-α, (HIF-1α) may regulate liporegulatory genes, but the relationship of HIF-1 to steatosis remains unknown. We investigated HIF-1α in alcohol-induced hepatic lipid accumulation. Alcohol administration resulted in steatosis, increased liver triglyceride levels, and increased serum alanine aminotransferase (ALT) levels, suggesting liver injury in wild-type (WT) mice. There was increased hepatic HIF-1α messenger RNA (mRNA), protein, and DNA-binding activity in alcohol-fed mice compared with controls. Mice engineered with hepatocyte-specific HIF-1 activation (HIF1dPA) had increased HIF-1α mRNA, protein, and DNA-binding activity, and alcohol feeding in HIF1dPA mice increased hepatomegaly and hepatic triglyceride compared with WT mice. In contrast, hepatocyte-specific deletion of HIF-1α [HIF-1α(Hep(-/-) )], protected mice from alcohol- and lipopolysaccharide (LPS)-induced liver damage, serum ALT elevation, hepatomegaly, and lipid accumulation. HIF-1α(Hep(-/-) ), WT, and HIF1dPA mice had equally suppressed levels of peroxisome proliferator-activated receptor α mRNA after chronic ethanol, whereas the HIF target, adipocyte differentiation-related protein, was up-regulated in WT mice but not HIF-1α(Hep(-/-) ) ethanol-fed/LPS-challenged mice. The chemokine monocyte chemoattractant protein-1 (MCP-1) was cooperatively induced by alcohol feeding and LPS in WT but not HIF-1α(Hep(-/-) ) mice. Using Huh7 hepatoma cells in vitro, we found that MCP-1 treatment induced lipid accumulation and increased HIF-1α protein expression as well as DNA-binding activity. Small interfering RNA inhibition of HIF-1α prevented MCP-1-induced lipid accumulation, suggesting a mechanistic role for HIF-1α in hepatocyte lipid accumulation. Alcohol feeding results in lipid accumulation in hepatocytes involving HIF-1α activation. The alcohol-induced chemokine MCP-1 triggers lipid accumulation in hepatocytes via HIF-1α activation, suggesting a mechanistic link between inflammation and hepatic steatosis in alcoholic liver disease.