Pathogenesis of Alcoholic Liver Disease: An Update

Oxidative stress in alcoholic liver disease, focusing on proteins, nucleic acids, and lipids: A review

Oxidative stress is one of the important factors in the development of alcoholic liver disease. The production of reactive oxygen species and other free radicals is an important feature of alcohol metabolism in the liver and an important substance in liver injury. When large amounts of ROS are produced, the homeostasis of the liver REDOX system will be disrupted and liver injury will be caused. Oxidative stress can damage proteins, nucleic acids and lipids, liver dysfunction. In addition, damaging factors produced by oxidative damage to liver tissue can induce the occurrence of inflammation, thereby aggravating the development of ALD. This article reviews the oxidative damage of alcohol on liver proteins, nucleic acids, and lipids, and provides new insights and summaries of the oxidative stress process. We also discussed the relationship between oxidative stress and inflammation in alcoholic liver disease from different perspectives. Finally, the research status of antioxidant therapy in alcoholic liver disease was summarized, hoping to provide better help for learning and developing the understanding of alcoholic liver disease.

Exploring the therapeutic potential of garlic in alcoholic liver disease: a network pharmacology and experimental validation study

OBJECTIVE

Employing network pharmacology and molecular docking, the study predicts the active compounds in garlic and elucidates their mechanism in inhibiting the development of alcoholic liver disease (ALD). ALD is a global chronic liver disease with potential for hepatocellular carcinoma progression.

METHODS

The main active ingredients and targets of garlic were identified through screening the TCMSP, TCM-ID, and ETCM databases. ALD disease targets were sourced from DisGeNET, GeneCards, and DiGSeE databases, and intervention targets for garlic were determined through intersections. Protein interaction networks were constructed using the STRING platform, and GO and KEGG pathway enrichment analyses were performed with R software. The garlic component-disease-target network was established using Cytoscape software. Validation of active ingredients against core targets was conducted through molecular docking simulations using AutoDock Vina software. Expression validation of core targets was carried out using human sequencing data of ALD obtained from the GEO database.

RESULTS

Integration of garlic drug targets with ALD disease targets identified 83 target genes. Validation through an alcohol-induced ALD mouse model supported certain network pharmacology findings, suggesting that garlic may impede disease progression by mitigating the inflammatory response and promoting ethanol metabolism.

CONCLUSION

This study provides insights into the potential therapeutic mechanisms of garlic in inhibiting ALD development. The identified active ingredients offer promising avenues for further investigation and development of treatments for ALD, emphasizing the importance of botanical remedies in liver disease management.

Differences in the Ability of Lactic Acid Bacteria To Prevent Acute Alcohol-Induced Liver Injury via the Gut Microbiota-Bile Acid-Liver Axis

Probiotics can regulate gut microbiota and protect against acute alcohol-induced liver injury through the gut-liver axis. However, efficacy is strain-dependent, and their mechanism remains unclear. This study investigated the effect of lactic acid bacteria (LAB), including Lacticaseibacillus paracasei E10 (E10), Lactiplantibacillus plantarum M (M), Lacticaseibacillus rhamnosus LGG (LGG), Lacticaseibacillus paracasei JN-1 (JN-1), and Lacticaseibacillus paracasei JN-8 (JN-8), on the prevention of acute alcoholic liver injury in mice. We found that LAB pretreatment reduced serum alanine transaminase (ALT) and aspartate transaminase (AST) and reduced hepatic total cholesterol (TC) and triglyceride (TG). JN-8 pretreatment exhibited superior efficacy in improving hepatic antioxidation. LGG and JN-8 pretreatment significantly attenuated hepatic and colonic inflammation by decreasing the expression of interleukin 6 (IL-6) and tumor necrosis factor α (TNF-α) and increasing the expression of interleukin 10 (IL-10). JN-1 and JN-8 pretreatments have better preventive effects than other LAB pretreatment on intestinal barrier dysfunction. In addition, the LAB pretreatment improved gut microbial dysbiosis and bile acid (BA) metabolic abnormality. All of the strains were confirmed to have bile salt deconjugation capacities in vitro, where M and JN-8 displayed higher activities. This study provides new insights into the prevention and mechanism of LAB strains in preventing acute alcoholic liver injury.

Butyrate alleviates alcoholic liver disease-associated inflammation through macrophage regulation and polarization via the HDAC1/miR-155 axis

BACKGROUND

We recently found that butyrate could ameliorate inflammation of alcoholic liver disease (ALD) in mice. However, the exact mechanism remains incompletely comprehended. Here, we examined the role of butyrate on ALD-associated inflammation through macrophage (Mψ) regulation and polarization using in vivo and in vitro experiments.

METHODS

For in vivo experiments, C57BL/6J mice were fed modified Lieber-DeCarli liquid diets supplemented with or without ethanol and sodium butyrate (NaB). After 6 weeks of treatment, mice were euthanized and associated indicators were analyzed. For in vitro experiments, lipopolysaccharide (LPS)-induced inflammatory murine RAW264.7 cells were treated with NaB or miR-155 inhibitor/mimic to verify the anti-inflammatory effect and underlying mechanism.

RESULTS

The administration of NaB alleviated pathological damage and associated inflammation, including LPS, tumor necrosis factor (TNF)-α, interleukin (IL)-6 and IL-1β levels in ALD mice. NaB intervention restored the imbalance of macrophage polarization by inhibiting inducible nitric oxide synthase (iNOS) and elevating arginase-1 (Arg-1). Moreover, NaB reduced histone deacetylase-1 (HDAC1), nuclear factor kappa-B (NF-κB), NOD-like receptor thermal protein domain associated protein 3 (NLRP3), and miR-155 expression in ALD mice, but also increased peroxisome proliferator-activated receptor-γ (PPAR-γ). Thus, MiR-155 was identified as a strong regulator of ALD. To further penetrate the role of miR-155, LPS-stimulated RAW264.7 cells co-cultured with NaB were treated with the specific inhibitor or mimic. Intriguingly, miR-155 was capable of negatively regulated inflammation with NaB intervention by targeting SOCS1, SHIP1, and IRAK-M genes.

CONCLUSION

Butyrate suppresses the inflammation in mice with ALD by regulating macrophage polarization via the HDAC1/miR-155 axis, which may potentially contribute to the novel therapeutic treatment for the disease.

Macrophage-expressed SRA ameliorates alcohol-induced liver injury by suppressing S-glutathionylation of Notch1 via recruiting thioredoxin

Scavenger receptor A (SRA) is preferentially expressed in macrophages and implicated as a multifunctional pattern recognition receptor for innate immunity. Hepatic macrophages play a primary role in the pathogenesis of alcoholic liver disease. Herein, we observed that SRA expression was significantly increased in the liver tissues of mice with alcohol-related liver injury. SRA-deficient (SRA-/-) mice developed more severe alcohol-induced liver disease than wild-type mice. Enhanced liver inflammation existed in alcohol-challenged SRA-/- mice and was associated with increased Notch activation in hepatic macrophages compared with wild-type control animals. Mechanistically, SRA directly bound with Notch1 and suppressed its S-glutathionylation, thereby inhibiting Notch pathway activation. Further, we determined that the SRA interacted with thioredoxin-1 (Trx-1), a redox-active protein. SRA inhibited Trx-1 dimerization and facilitated the interaction of Trx-1 with Notch1. Application of a Trx-1-specific inhibitory agent during macrophage stimulation abolished SRA-mediated regulation of the Notch pathway and its downstream targets. In summary, our study revealed that SRA plays a critical role in macrophage inflammatory response by targeting Notch1 for its glutathionylation. SRA-mediated negative regulation of Notch activation might serve as a novel therapeutic strategy for alcohol-induced liver injury.

The Protective Effect of Auricularia cornea var. Li. Polysaccharide on Alcoholic Liver Disease and Its Effect on Intestinal Microbiota

This study's objective was to examine the protective effect and mechanism of a novel polysaccharide (AYP) from Auricularia cornea var. Li. on alcoholic liver disease in mice. AYP was extracted from the fruiting bodies of Auricularia cornea var. Li. by enzymatic extraction and purified by DEAE-52 and Sephacryl S-400. Structural features were determined using high-performance liquid chromatography, ion exchange chromatography and Fourier-transform infrared analysis. Additionally, alcoholic liver disease (ALD) mice were established to explore the hepatoprotective activity of AYP (50, 100 and 200 mg/kg/d). Here, our results showed that AYP presented high purity with a molecular weight of 4.64 × 105 Da. AYP was composed of galacturonic acid, galactose, glucose, arabinose, mannose, xylose, rhamnose, ribos, glucuronic acid and fucose (molar ratio: 39.5:32.9:23.6:18.3:6.5:5.8:5.8:3.3:2:1.1). Notably, AYP remarkably reduced liver function impairment (alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglyceride (TG), total cholesterol (TC)), nitric oxide (NO) and malondialdehyde (MDA) of the liver and enhanced the activity of antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione (gGSH)) in mice with ALD. Meanwhile, the serum level of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and interleukin-1β (IL-1β) were reduced in ALD mice treated by AYP. Furthermore, the AYPH group was the most effective and was therefore chosen to further investigate its effect on the intestinal microbiota (bacteria and fungi) of ALD mice. Based on 16s rRNA and ITS-1 sequencing data, AYP influenced the homeostasis of intestinal microbiota to mitigate the damage of ALD mice, possibly by raising the abundance of favorable microbiota (Muribaculaceae, Lachnospiraceae and Kazachstania) and diminishing the abundance of detrimental microbiota (Lactobacillus, Mortierella and Candida). This discovery opens new possibilities for investigating physiological activity in A. cornea var. Li. and provides theoretical references for natural liver-protecting medication research.

Sirtuin 1 alleviates alcoholic liver disease by inhibiting HMGB1 acetylation and translocation

Background

Alcoholic liver disease (ALD) encompasses a spectrum of liver disorders resulting from prolonged alcohol consumption and is influenced by factors such as oxidative stress, inflammation, and apoptosis. High Mobility Group Box 1 (HMGB1) plays a pivotal role in ALD due to its involvement in inflammation and immune responses. Another key factor, Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, is known for its roles in cellular stress responses and metabolic regulation. Despite individual studies on HMGB1 and SIRT1 in ALD, their specific molecular interactions and combined effects on disease advancement remain incompletely understood.

Methods

Alcohol-induced liver injury (ALI) models were established using HepG2 cells and male C57BL/6 mice. HMGB1 and SIRT1 expressions were assessed at the mRNA and protein levels usingreverse transcription-quantitative polymerase chain reaction, western blot, and immunofluorescence staining. The physical interaction between HMGB1 and SIRT1 was investigated using co-immunoprecipitation and immunofluorescence co-expression analyses. Cellular viability was evaluated using the CCK-8 assay.

Results

In patients with clinical ALI, HMGB1 mRNA levels were elevated, while SIRT1 expression was reduced, indicating a negative correlation between the two. ALI models were successfully established in cells and mice, as evidenced by increased markers of cellular and liver damage. HMGB1 acetylation and translocation were observed in both ALI cells and mouse models. Treatment with the SIRT1 agonist, SRT1720, reversed the upregulation of HMGB1 acetylation, nuclear translocation, and release in the ethyl alcohol (EtOH) group. Furthermore, SIRT1 significantly attenuated ALI. Importantly, in vivo binding was confirmed between SIRT1 and HMGB1.

Conclusions

SIRT1 alleviates HMGB1 acetylation and translocation, thereby ameliorating ALI.

Ferroptosis contributes to ethanol-induced hepatic cell death via labile iron accumulation and GPx4 inactivation

Alcohol abuse is a significant cause of global morbidity and mortality, with alcoholic liver disease (ALD) being a common consequence. The pathogenesis of ALD involves various cellular processes, including oxidative stress, inflammation, and hepatic cell death. Recently, ferroptosis, an iron-dependent form of programmed cell death, has emerged as a potential mechanism in many diseases. However, the specific involvement and regulatory mechanisms of ferroptosis in ALD remain poorly understood. Here we aimed to investigate the presence and mechanism of alcohol-induced ferroptosis and the involvement of miRNAs in regulating ferroptosis sensitivity. Our findings revealed that long-term ethanol feeding induced ferroptosis in male mice, as evidenced by increased expression of ferroptosis-related genes, lipid peroxidation, and labile iron accumulation in the liver. Furthermore, we identified dysregulation of the methionine cycle and transsulfuration pathway, leading to severe glutathione (GSH) exhaustion and indirect deactivation of glutathione peroxidase 4 (GPx4), a critical enzyme in preventing ferroptosis. Additionally, we identified miR-214 as a ferroptosis regulator in ALD, enhancing hepatocyte ferroptosis by transcriptionally activating the expression of ferroptosis-driver genes. Our study provides novel insights into the involvement and regulatory mechanisms of ferroptosis in ALD, highlighting the potential therapeutic implications of targeting ferroptosis and miRNAs in ALD management.

Roles of Gut Microbiota in Alcoholic Liver Disease

Alcoholic liver disease (ALD)-one of the most common liver diseases - involves a wide range of disorders, including asymptomatic hepatic steatosis, alcoholic hepatitis (AH), liver fibrosis, and cirrhosis. Alcohol consumption induces a weakened gut barrier and changes in the composition of the gut microbiota. The presence of CYP2E1 and its elevated levels in the gastrointestinal tract after alcohol exposure lead to elevated levels of ROS and acetaldehyde, inducing inflammation and oxidative damage in the gut. At the same time, the influx of harmful molecules such as the bacterial endotoxin LPS and peptidogly from gut dysbiosis can induce intestinal inflammation and oxidative damage, further compromising the intestinal mucosal barrier. In this process, various oxidative stress-mediated post-translational modifications (PTMs) play an important role in the integrity of the barrier, eg, the presence of acetaldehyde will result in the sustained phosphorylation of several paracellular proteins (occludin and zona occludens-1), which can lead to intestinal leakage. Eventually, persistent oxidative stress, LPS infiltration and hepatocyte damage through the enterohepatic circulation will lead to hepatic stellate cell activation and hepatic fibrosis. In addition, probiotics, prebiotics, synbiotics, fecal microbial transplantation (FMT), bioengineered bacteria, gut-restricted FXR agonists and others are promising therapeutic approaches that can alter gut microbiota composition to improve ALD. In the future, there will be new challenges to study the interactions between the genetics of individuals with ALD and their gut microbiome, to provide personalized interventions targeting the gut-liver axis, and to develop better techniques to measure microbial communities and metabolites in the body.

Alcohol-associated bowel disease: new insights into pathogenesis

Excessive alcohol drinking can cause pathological changes including carcinogenesis in the digestive tract from mouth to large intestine, but the underlying mechanisms are not fully understood. In this review, we discuss the effects of alcohol on small and large intestinal functions, such as leaky gut, dysbiosis and alterations of intestinal epithelium and gut immune dysfunctions, commonly referred to as alcohol-associated bowel disease (ABD). To date, detailed mechanistic insights into ABD are lacking. Accumulating evidence suggests a pathogenic role of ethanol metabolism in dysfunctions of the intestinal tract. Ethanol metabolism generates acetaldehyde and acetate, which could potentially promote functional disruptions of microbial and host components of the intestinal barrier along the gastrointestinal tract. The potential involvement of acetaldehyde and acetate in the pathogenesis of the underlying ABD, including cancer, is discussed. We also highlight some gaps in knowledge existing in the field of ABD. Finally, we discuss future directions in exploring the role of acetaldehyde and acetate generated during chronic alcohol intake in various pathologies affecting different sites of the intestinal tract.

Serum keratin 18-M65 levels detect progressive forms of alcohol-associated liver disease in early noncirrhotic stages

BACKGROUND AND AIMS

The progression of alcohol-associated liver disease (ALD) in its early precirrhotic stages can be a silent process. Serum keratin 18 levels (K18-M65) predict severe events and mortality in advanced stages of ALD, but data on this biomarker in early stages are scarce. We evaluated the diagnostic accuracy of K18-M65 levels in identifying early forms of ALD.

METHODS

We prospectively evaluated two cohorts of actively drinking patients with alcohol use disorder (AUD) following a rehabilitation program (training (n = 162) and validation (n = 78)) and matched healthy controls (n = 21). Clinical, laboratory, and imaging data were used to distinguish AUD patients with simple steatosis (minimal ALD) and steatohepatitis/fibrosis (early ALD). We measured serum K18-M65 levels and assessed their ability to predict early ALD.

RESULTS

High levels of K18-M65 characterized AUD patients with early ALD, while levels in the minimal ALD group were similar to those in healthy controls. K18-M65 levels distinguished minimal liver disease from early ALD (AUROC = 0.8704; p < 0.0001) with an optimal cutoff at 265.9 U/L. K18-M65 levels strongly correlated with transaminases and predicted early ALD (OR 25.81; 95% CI 3.166-336.1; p < 0.0001), controlled attenuation parameter, and liver stiffness independently from transaminases and other potential confounders. K18-M65 levels did not discriminate between fibrosis and steatohepatitis but correlated with histological signs of hepatocellular injury and inflammation (all p < 0.05). The K18-M65 cutoff detected early ALD in the validation cohort with high accuracy (sensitivity 86.67%, specificity 96.67%) and a very high positive likelihood ratio (28.6; 95% CI 4.14-197.73).

CONCLUSIONS

Serum K18-M65 levels can be used as a biomarker to detect early ALD stages with excellent predictive value.

Hydrogen gas ameliorates acute alcoholic liver injury via anti-inflammatory and antioxidant effects and regulation of intestinal microbiota

Alcoholic liver disease (ALD) is a globally prevalent liver-related disorder characterized by severe oxidative stress and inflammatory liver damage, for which no effective treatment is currently available. Hydrogen gas (H₂) has been demonstrated to be an efficient antioxidant in various diseases in animals as well as humans. However, the protective effects of H₂ on ALD and its underlying mechanisms remain to be elucidated. The present study demonstrated that H₂ inhalation ameliorated liver injury, and attenuated liver oxidative stress, inflammation, and steatosis in an ALD mouse model. Moreover, H₂ inhalation improved gut microbiota, including increasing the abundance of Lachnospiraceae and Clostridia, and decreasing the abundance of Prevotellaceae and Muribaculaceae, and also improved intestinal barrier integrity. Mechanistically, H₂ inhalation blocked activation of the LPS/TLR4/NF-κB pathway in liver. Notably, it was further demonstrated that the reshaped gut microbiota may accelerate alcohol metabolism, regulate lipid homeostasis and maintain immune balance by bacterial functional potential prediction (PICRUSt). Fecal microbiota transplantation from mice that had undergone H₂ inhalation significantly alleviated acute alcoholic liver injury. In summary, the present study showed that H₂ inhalation alleviated liver injury by reducing oxidative stress and inflammation, while also improving intestinal flora and enhancing the intestinal barrier. H₂ inhalation may serve as an effective intervention for preventing and treating ALD in a clinical context.

Spectrum-effect relationship study to reveal the pharmacodynamic substances in Flos Puerariae-Semen Hoveniae medicine pair for the treatment of alcohol-induced liver damage

ETHNOPHARMACOLOGICAL RELEVANCE

Alcoholic liver disease (ALD) is the most serious and irreversible liver damage associated with alcohol consumption. Flos Puerariae and Semen Hoveniae are traditional Chinese medicines (TCM) for dispelling the effects of alcohol. Many studies have shown that the combination of two medicinal materials has the enhanced effect of treating ALD.

AIM OF THE STUDY

The aim of this study is to assess the pharmacological effects of Flos Puerariae-Semen Hoveniae medicine pair, to elucidate its action mechanism in the treatment of alcohol-induced BRL-3A cells, and to reveal the active ingredients in the medicine pair that exerted pharmacological effects by spectrum-effect relationship study.

MATERIALS AND METHODS

Firstly, MTT assays, ELISA, fluorescence probe analysis, and Western blot were employed to study the underlying mechanisms of the medicine pair in alcohol-induced BRL-3A cells by examining pharmacodynamic indexes and related protein expression. Secondly, HPLC method was established for chemical chromatograms of the medicine pair with different ratios and the sample extracted by different solvents. Then, principal component analysis, pearson bivariate correlation analysis and grey relational analysis were applied for development of the spectrum-effect correlation between pharmacodynamic indexes and HPLC chromatograms. Moreover, prototype components and their metabolites in vivo were identified by the HPLC-MS method.

RESULTS

Flos Puerariae-Semen Hoveniae medicine pair remarkably increased cell viability, decreased the activity of ALT, AST, TC and TG, reduced the generation of TNF-α, IL-1β, IL-6, MDA and ROS, increased the activity of SOD and GSH-Px, reduced protein expression of CYP2E1, compared with alcohol-induced BRL-3A cells. The medicine pair modulated the PI3K/AKT/mTOR signaling pathways by up-regulating the levels of phospho-PI3K, phospho-AKT and phospho-mTOR. Also, the results of the spectrum-effect relationship study showed that P1 (chlorogenic acid), P3 (daidzin), P4 (6″-O-xylosyl-glycitin), P5 (glycitin), P6 (unknown), P7 (unknown), P9 (unknown), P10 (6″-O-xylosyl-tectoridin), P12 (tectoridin) and P23 (unknown) can be considered as the main components of the medicine pair in the treatment of ALD. Furthermore, 6″-O-xylosyl-tectoridin, tectoridin, daidzin, 6″-O-xylosyl-glycitin and glycitin can be absorbed into the blood and showed clear metabolic and excretion behaviors in rats.

CONCLUSION

In this study, the hepatoprotective effects and the pharmacology mechanism of Flos Puerariae-Semen Hoveniae medicine pair in alcohol-induced BRL-3A cells were initially investigated and revealed. Through the spectrum-effect relationship study, the potential pharmacodynamic constituents such as daidzin, 6″-O-xylosyl-glycitin, 6″-O-xylosyl-tectoridin, glycitin, and tectoridin exert pharmacological effects on alcohol-induced oxidative stress and inflammation by modulating the PI3K/AKT/mTOR signaling pathways. This study provided experimental basis and data support for revealing the pharmacodynamic substance basis and pharmacology mechanism in the treatment of ALD. Moreover, it provides a robust mean of exploring the primary effective components responsible for the bioactivity of complicated TCM.

Walnut (Juglans regia L.) Oligopeptides Alleviate Alcohol-Induced Acute Liver Injury through the Inhibition of Inflammation and Oxidative Stress in Rats

The study was aimed at investigating the effects of walnut oligopeptides (WOPs) on alcohol-induced acute liver injury and its underlying mechanisms. Male Sprague Dawley (SD) rats were randomly assigned to six groups: normal control, alcohol control, whey protein (440 mg/kg.bw), and three WOPs (220 mg/kg.bw, 440 mg/kg.bw, 880 mg/kg.bw) groups. After 30 days of gavage, ethanol with a volume fraction of 50%, administered at a dose of 7 g/kg.bw., caused acute liver injury. A righting reflex experiment and a blood ethanol concentration evaluation were then performed. Serum biochemical parameters, inflammatory cytokines, liver alcohol metabolism enzymes, oxidative stress biomarkers, liver nuclear factor-κB (NF-κB p65), and cytochrome P4502E1 expression were determined. The results revealed that the intervention of 440 mg/kg and 880 mg/kg WOPs could alleviate the degree of intoxication, decrease blood ethanol concentration, alleviate alcohol-induced hepatic steatosis, enhance the activity of hepatic ethanol metabolizing enzymes and antioxidant capacity, reduce lipid oxidation products and pro-inflammatory factor contents, and inhibit the expression of NF-κBp65 in the livers of rats. The outcomes of the study suggest that WOPs have beneficial effects on liver damage caused by acute ethanol binge drinking, with the high-dose WOPs (880 mg/kg.bw) exerting the most pronounced hepatoprotective effect.

Protective Effect of Polyphenols, Protein, Peptides, and Polysaccharides on Alcoholic Liver Disease: A Review of Research Status and Molecular Mechanisms

Alcoholic liver disease (ALD) has emerged as an important public health problem in the world. The polyphenols, protein, peptides, and polysaccharides have attracted attention for prevention or treatment of ALD. Therefore, this paper reviews the pathogenesis of ALD, the relationship between polyphenols, peptides, polysaccharides, and ALD, and expounds the mechanism of gut microbiota on protecting ALD. It is mainly found that the hydroxyl group of polyphenols endows it with antioxidation to protect ALD. The ALD protection of bioactive peptides is related to amino acid composition. The ALD protection of polysaccharides is related to the primary structure. Meanwhile, polyphenols, protein, peptides, and polysaccharides prevent or treat ALD by antioxidation, anti-inflammatory, antiapoptosis, lipid metabolism, and gut microbiota regulation. This contribution provides updated information on polyphenols, protein, peptides, and polysaccharides in response to ALD, which will not only facilitate the development of novel bioactive components but also the future application of functional food raw materials will be promoted.

Deficiency of NLR family member NLRC5 alleviates alcohol induced hepatic injury and steatosis by enhancing autophagy of hepatocytes

Steatosis is regarded as an early response of the liver to excessive alcohol consumption, which ultimately results in alcoholic liver disease (ALD). Hepatocytes are the primary drivers of the pathological process known as hepatic damage and steatosis, which is characterized by significant fat accumulation and an abundance of fat vacuoles. NLRs, a family member of pattern recognition receptors, have recently been found to be crucial in liver disorders. In this study, we examined the possible impact of NLRC5, the largest NLR family member, on alcohol-induced fatty liver development using a gene knock-out mouse model. The mouse liver was severely damaged and developed steatosis as a result of chronic and excessive ethanol use, and this damage was prevented by the lack of NLRC5. Additionally, NLRC5 deletion reversed ethanol's ability to increase the serum concentrations of TG, T-CHO, ALT, and AST. Absence of NLRC5 reduced ethanol-stimulated aberrant expression of the vital regulators of lipid synthesis and metabolism, SREBP-1c, FAS and PPAR-α. Furthermore, loss- and gain-of-function research indicated that NLRC5 might affect the autophagy pathway in alcohol-induced hepatic steatosis progression. The functional role of NLRC5 in ALD is obviously impacted by the autophagy inducer rapamycin as well as the autophagy inhibitor 3-MA. Our research showed that NLRC5 was involved in ethanol-induced injury and steatosis of the liver, and may be considered a suitable therapeutic target for treating ALD.

Alcoholic liver disease and intestinal microbiota in an experimental model: Biochemical, inflammatory, and histologic parameters

OBJECTIVES

Alcoholic liver disease (ALD) is the leading cause of alcohol-related deaths worldwide. Experimental ALD models are expensive and difficult to reproduce. A low-cost, reproducible ALD model was developed, and liver damage compared with the gut microbiota. The aims of this study were to develop an experimental model of ALD, through a high-fat diet, the chronic use of ethanol, and intragastric alcohol binge; and to evaluate the composition of the gut microbiota and its correlation with markers of inflammatory and liver disease progression in this model.

METHODS

Adult male Wistar rats were randomized (N = 24) to one of three groups: control (standard diet and water + 0.05% saccharin), ALC4 and ALC8 (sunflower seed, 10% ethanol + 0.05% saccharin for 4 and 8 wk, respectively). On the last day, ALC4/8 received alcoholic binge (5 g/kg). Clinical, nutritional, biochemical, inflammatory, pathologic, and gut microbiota data were analyzed.

RESULTS

ALC4/8 animals consumed more alcohol and lipids (P < 0.01) and less total energy, liquids, solids, carbohydrates, and proteins (P < 0.01), and gained less weight (P < 0.01) than controls. ALC8 had lower Lee index scores than controls and ALC4 (P < 0.01). Aminotransferases increased and albumin diminished in ALC4/8 but not in the control group (P < 0.03 for all). Glucose and aspartate transaminase/alanine aminotransaminase ratios were higher in the ALC8 rats than in the controls (P < 0.03). Cholesterol was higher in ALC4 and lower in ALC8 compared with controls (P < 0.03). Albumin and high-density lipoprotein cholesterol levels were lower in ALC8 (P < 0.03). Hepatic concentration of triacylglycerols was higher in ALC8 than in ALC4 and controls (P < 0.05). ALC4/8 presented microvesicular grade 2 and 3 steatosis, respectively, and macrovesicular grade 1. No change in the gene expression of inflammatory markers between groups was seen. ALC4/8 had lower fecal bacterial α-diversity and relative abundance of Firmicutes (P < 0.005) and greater Bacterioidetes (P < 0.0007) and Protobacteria (P < 0.001) than controls. Gut microbiota correlated with serum and liver lipids, steatosis, albumin, and aminotransferases (P < 0.01 for all).

CONCLUSION

The model induced nutritional, biochemical, histologic, and gut microbiota changes, and appears to be useful in the study of therapeutic targets.

Four Different Structural Dietary Polyphenols, Especially Dihydromyricetin, Possess Superior Protective Effect on Ethanol-Induced ICE-6 and AML-12 Cytotoxicity: The Role of CYP2E1 and Keap1-Nrf2 Pathways

Polyphenols have received attention as dietary supplements for the relief of alcoholic liver disease (ALD) due to various bioactivities. Ethanol-induced rat small intestinal epithelial cell 6 (IEC-6) and alpha mouse liver 12 (AML-12) cell models were pretreated with four dietary polyphenols with different structures to explore their effects on cytotoxicity and potential protective mechanisms. The results showed that polyphenols had potential functions to inhibit ethanol-induced AML-12 and IEC-6 cell damage and oxidative stress, and restore ethanol-induced IEC-6 permeability and tight junction gene expression. Especially, dihydromyricetin (DMY) had the best protective effect on ethanol-induced cytotoxicity, followed by apigenin (API). Western blot results showed that DMY and API had the best ability to inhibit CYP2E1 and Keap1, and promote nuclear translocation of Nrf2, which might be the potential mechanism by which DMY and API attenuate ethanol-induced cytotoxicity. Moreover, the molecular docking results predicted that DMY and API could bind more tightly to the amino acid residues of CYP2E1 and Keap1, which might be one of the inhibitory modes of dietary polyphenols on CYP2E1 and Keap1. This study provided a rationale for the subsequent protective effect of dietary polyphenols on alcohol-induced liver injury in animal models and provided new clues on bioactive components for ALD-protection based on the gut-liver axis.

Red raspberry supplementation mitigates alcohol-induced liver injury associated with gut microbiota alteration and intestinal barrier dysfunction in mice

Alcoholic liver disease (ALD) is still a global health concern. Long-term alcohol intake alters the gut microbiota diversity and metabolic activity, and causes intestinal barrier dysfunction, leading to the development of ALD. This research explored the protective effects and underlying mechanisms of red raspberry (RR) on alcohol-related disorders in mice. Male C57BL/6J mice were fed a standard diet or a standard diet supplemented with 2%, 4%, and 8% weight/weight RR. Meanwhile, mice were administered 35% (v/v) ethanol (EtOH, 10 mL per kg body weight) intragastrically once daily for six weeks, except the control group mice. The results showed that RR supplementation decreased liver injury markers (alanine and aspartate transaminases) in the serum, reduced triglyceride level in the liver and downregulated hepatic cytochrome P450 2E1 mRNA expression in mice administered EtOH. In addition, EtOH-mediated oxidative stress in the liver was attenuated by RR supplementation through decreased hepatic malondialdehyde content and increased antioxidant (glutathione, glutathione peroxidase, and catalase) levels and activities in mice exposed to EtOH. Moreover, RR supplementation reversed EtOH-induced alteration in the cecal microbial composition at the phylum, order, genus, and species levels and improved the intestinal barrier function associated with the inhibition of the NF-κB/MLCK pathway, which was accompanied by upregulation of tight junctions (zonula occludens 1, occludin, claudin-1, and claudin-4) and E-cadherin mRNA and protein expressions. Accordingly, RR supplementation resulted in a decreased level of endotoxins in the serum and attenuation of the inflammatory response in the liver, illustrated by a significant decrease in tumor necrosis factor-alpha, interleukin (IL)-1β, and IL-6 levels. Overall, RR supplementation alleviated the adverse effects of chronic alcohol intake in C57BL/6J mice and could be a potential supplement for improving ALD.

Erk1/2 signaling mediates the HGF-induced protection against ethanol and acetaldehyde-induced toxicity in the pancreatic RINm5F cell line

Alcohol-induced pancreas damage remains as one of the main risk factors for pancreatitis development. This disorder is poorly understood, particularly the effect of acetaldehyde, the primary alcohol metabolite, in the endocrine pancreas. Hepatocyte growth factor (HGF) is a protective protein in many tissues, displaying antioxidant, antiapoptotic, and proliferative responses. In the present work, we were focused on characterizing the response induced by HGF and its protective mechanism in the RINm5F pancreatic cell line treated with ethanol and acetaldehyde. RINm5F cells were treated with ethanol or acetaldehyde for 12 h in the presence or not of HGF (50 ng/ml). Cells under HGF treatment decreased the content of reactive oxygen species and lipid peroxidation induced by both toxics, improving cell viability. This effect was correlated to an improvement in insulin expression impaired by ethanol and acetaldehyde. Using a specific inhibitor of Erk1/2 abrogated the effects elicited by the growth factor. In conclusion, the work provides mechanistic evidence of the HGF-induced-protective response to the alcohol-induced damage in the main cellular component of the endocrine pancreas.

P2X7 Receptor in Alcoholic Steatohepatitis and Alcoholic Liver Fibrosis

Alcoholic liver disease is one of the most common chronic liver diseases in the world. It is a liver disease caused by prolonged heavy drinking and its main clinical features are nausea, vomiting, enlargement of the liver, and jaundice. Recent studies suggest that Kupffer cell-mediated inflammatory response is a core driver in the development of alcoholic steatohepatitis and alcoholic liver fibrosis. As a danger signal, extracellular ATP activates the assembly of NLPR3 inflammasome by acting on purine P2X7 receptor, the activated NLRP3 inflammasome prompts ASC to cleave pro-cCaspase-1 into active caspase-1in KCs. Active caspase-1 promotes the conversion of pro-IL-1β to IL-1β, which further enhances the inflammatory response. Here, we briefly review the role of the P2X7R-NLRP3 inflammasome axis in the pathogenesis of alcoholic liver disease and the evolution of alcoholic steatohepatitis and alcoholic liver fibrosis. Regulation of the inflammasome axis of P2X7R-NLRP3 may be a new approach for the treatment of alcoholic liver disease.

The Ethanolic Extract of Lindera aggregata Modulates Gut Microbiota Dysbiosis and Alleviates Ethanol-Induced Acute Liver Inflammation and Oxidative Stress SIRT1/Nrf2/NF-κB Pathway

This study is an attempt to evaluate the therapeutic effect of the ethanolic extract of Lindera aggregata on the liver and intestinal microbiota in rats with alcohol-induced liver injury (ALI). Rats were treated with 70 mg probiotics, 1 g/kg, 2 g/kg, and 3 g/kg ethanolic extract of Lindera aggregata, respectively, for 10 days. We found that Lindera aggregata could significantly reduce the biochemical parameters in the serum of ALD rats. Lindera aggregata alleviates oxidative stress and inflammation by upregulating SIRT1 and Nrf2 and downregulating COX2 and NF-κB. The results of 16S rRNA gene sequencing showed that the medium dose of Lindera aggregata had the best effect on the growth of beneficial bacteria. Diversity analysis and LEfSe analysis showed that beneficial bacteria gradually occupied the dominant niche. The relative abundance of potential pathogens in the gut decreased significantly. We demonstrated that the ethanolic extract of Lindera aggregata can alleviate the oxidative stress and inflammation induced by alcohol through the SIRT1/Nrf2/NF-κB pathway and can modulate the disturbance of gut microbiota induced by alcohol intake.

Probiotic-fermented Pueraria lobata (Willd.) Ohwi alleviates alcoholic liver injury by enhancing antioxidant defense and modulating gut microbiota

BACKGROUND

Pueraria lobata (Willd.) Ohwi (PL) has been used in China to detoxify alcohol and protect the liver for millennia, though its mechanism of liver protection has not been elucidated. However, fermentation is considered to be one of the effective ways to enhance the efficacy of traditional Chinese medicine. The aim of this study was to investigate the hepatoprotective mechanism of probiotic-fermented PL (FPL). Sprague Dawley rats were administered with FPL followed by gavage of alcohol for seven consecutive days; following that, liver injury levels were evaluated in rats.

RESULTS

FPL ameliorated lipid accumulation and inflammation levels in rats. Meanwhile, the levels of ethanol dehydrogenase, acetaldehyde dehydrogenase, and cytochrome P4502E1 were elevated by FPL treatment. It was observed that the levels of catalase, superoxide dismutase, and glutathione peroxidase were elevated, and the expression of nuclear transcriptional factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase-1 genes and proteins were increased by FPL treatment, demonstrating that the Nrf2-mediated signal pathway was activated. Furthermore, FPL restored the composition of the gut microbiota with an increase in the abundances of Firmicutes and Lactobacillus and a decrease in the abundances of Bacteroidota and Akkermansia. Additionally, a strong correlation was found between the gut microbiota and the antioxidant parameters.

CONCLUSION

The results indicate that FPL possesses an excellent protective effect in alcoholic liver injury. Our findings are beneficial to the development of hepatoprotective nutraceuticals for alcoholics. © 2022 Society of Chemical Industry.

Dietary camellia seed oil attenuates liver injury in mice chronically exposed to alcohol

Dietary fat composition is closely associated with the pathological development of alcoholic liver disease (ALD). Fat enriched with saturated fatty acids protects whereas with polyunsaturated fatty acids aggravates alcohol-induced liver injury. However, limited study has addressed how monounsaturated fatty acids (MUFAs) determines the pathological process of ALD. Our study was conducted to evaluate the effect of MUFAs-enriched-camellia seed oil (CSO) on alcohol-induced liver injury. The ALD model was established by feeding C57BL/6 mice with Lieber-DeCarli diet, and with either CSO or polyunsaturated fatty acids (PUFAs)-enriched-corn oil (CO) as fat source. After 4-week-intervention, CSO-feed rescued alcohol-induced liver injury compared to CO-feed, evidenced by measurements of plasma ALT activity, H&E stain, and hepatic cleaved-Caspase-3 expression. Besides, CSO-feed alleviated alcohol-induced oxidative stress, associated with NRF2 and Hif-1α expressions improvement. The reduction of F4/80 immunostaining and the decreased expressions of hepatic TNF-α and IL-6 suggested CSO-feed improved alcohol-induced inflammation. The mechanistic analysis showed that the inhibition of ASK1 and MAPKs might contribute to CSO-protected liver injury. Notably, we observed CSO-feed relieved the gut microbiota disturbance with the decreased Firmicutes and Turicibater, and the increased Bacteroidota, Alloprevotella, and Bacteroides, and reduced circulatory endotoxin level and lipolysis of adipose tissue, which are the known pathogenic factors in alcohol-induced liver injury. Unexpectedly, CSO induced more hepatic steatosis than CO-feed. In conclusion, CSO attenuated chronic alcohol consumption-induced liver injury but enhanced hepatic steatosis. CSO could be a potential dietary choice for alcoholic individuals with liver injury.

Chemokines in Primary Liver Cancer

The liver is responsible for extremely important functions in the human body. In the liver’s structure, we distinguish between connective tissue (stroma) and parenchyma, the latter of which is formed from the basic structural and functional units of the liver—hepatocytes. There are many factors, that negatively affect the liver cells, contributing to their damage. This may lead to fibrosis, liver failure and, in consequence, primary liver cancer, which is the sixth most commonly diagnosed malignancy and the fourth leading cause of cancer death worldwide. Chemokines are a large family of secreted proteins. Their main role is to direct the recruitment and migration of cells to sites of inflammation or injury. Some authors suggest that these proteins might play a potential role in the development of many malignancies, including primary liver cancer. The aim of this study was to evaluate and summarize the knowledge regarding liver diseases, especially primary liver cancer (HCC) and the participation of chemokines in the development of this malignancy. Chemokines involved in the initiation of this type of tumor belong mainly to the CC and CXC chemokines. Their significant role in the course of hepatocellular carcinoma proves their usefulness in detecting and monitoring the course and treatment in patients with this disease.

Protective Mechanism of Polygonum perfoliatum L. Extract on Chronic Alcoholic Liver Injury Based on UHPLC-QExactive Plus Mass Spectrometry Lipidomics and MALDI-TOF/TOF Mass Spectrometry Imaging

Polygonum perfoliatum L. has a long history of medicinal and edible applications. Studies have shown that it can significantly protect liver injury, but the mechanism is unclear. The purpose of this study was to explore the protective mechanism of P. perfoliatum on chronic alcoholic liver injury from the perspective of lipid metabolism. After 8 weeks of alcohol exposure in male Wister mice, the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in serum were significantly increased, and the activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in liver were significantly decreased. Meanwhile, pathological changes of liver tissue in mice were observed by histopathology. Then, Ultra-High Performance Liquid Chromatography (UHPLC) QExactive Plus Mass Spectrometer lipidomics and matrix-assisted laser desorption/ionization time-of-flight/time -of-flight (MALDI-TOF/TOF) mass spectrometry imaging methods were established to analyze lipid metabolism in mice. Ten different lipids were identified by statistical analysis, including Fatty Acyls, Glycerophospholipids, Prenol lipids and Sphingomyelins. After intervention with P. perfoliatum extracts at different doses (25 to 100 mg/kg), levels of AST, ALT, ALP in serum, and activities of ADH and ALDH in liver were significantly corrected. The hepatic cord structure was clear, and the liver cells were closely arranged without other obvious abnormalities. Non-target lipidomics analysis showed that P. perfoliatum extract could regulate the metabolic disorders of the 10 different lipids caused by continuous alcohol exposure. Pathway analysis suggested that the mechanism of P. perfoliatum extract on chronic alcoholic liver injury may be related to the regulation of linoleic acid and α-linolenic acid.

Diallyl disulfide ameliorates ethanol-induced liver steatosis and inflammation by maintaining the fatty acid catabolism and regulating the gut-liver axis

Diallyl disulfide (DADS) has been suggested to possess hepatoprotection against alcoholic liver disease (ALD) by a couple of pilot studies, while the underlying mechanisms remain largely unknown. This study aimed to investigate the hepatoprotective effects of DADS against ethanol-induced liver steatosis and early inflammation by using the chronic-plus-binge mice model and cultured J774A.1 macrophages and AML12 hepatocytes. We found that DADS significantly attenuated ethanol-induced elevation of serum aminotransferase activities, accumulation of liver triglyceride, hepatocytes apoptosis, oxidative stress, infiltration of macrophages and neutrophils, and proinflammatory polarization of macrophages in mice livers. In addition, chronic-plus-binge drinking induced apparent intestinal mucosa damage and disturbance of gut microbiota, endotoxemia, and activation of hepatic NF-κB signaling and NLRP3 inflammasome, which was inhibited by DADS. In vitro studies using cocultured AML12/J774A.1 cells showed that DADS suppressed ethanol/LPS-induced cell injury and inflammatory activation of macrophages. Furthermore, DADS ameliorated ethanol-induced decline of peroxisome proliferator-activated receptor α (PPARα), carnitine palmitoyltransferase 1 (CPT1), and phosphorylated AMP-activated protein kinase (AMPK) protein levels in mice liver and AML12 cells. These results demonstrate that DADS could prevent ethanol-induced liver steatosis and early inflammation by regulating the gut-liver axis and maintaining fatty acid catabolism.

The amelioration of alcohol-induced liver and intestinal barrier injury by Lactobacillus rhamnosus Gorbach-Goldin (LGG) is dependent on Interleukin 22 (IL-22) expression

Alcoholic liver disease (ALD) is a common clinical liver injury disease. Lactobacillus rhamnosus Gorbach-Goldin (LGG) has been revealed to alleviate alcohol-induced intestinal barrier and liver injury. However, the underlying mechanism of LGG treatment for ALD remains unclear. To clarify this aspect, a chronic plus binge ALD model was constructed using C57BL/6 mice in line with a chronic alcohol binge feeding protocol. Interleukin 22 (IL-22) level was determined by quantitative real-time polymerase-chain reaction and enzyme-linked immunosorbent assays. Effects of LGG in model or IL-22 knockdown in LGG-treated model on the liver injury and steatosis status, as well as intestinal barrier function were assessed by hematoxylin eosin (HE) staining. Levels of alanine aminotransferase (ALT), triglyceride (TG), and aspartate aminotransferase (AST) in serum were measured by the corresponding kit. Western blot analysis was conducted to detect protein expressions of intestinal tight junction protein 1 (ZO-1) and Claudin-1. Concretely, LGG elevated IL-22 level in liver tissues and serum, while inhibiting ALT, TG, and AST levels in alcohol-exposed mice. Moreover, LGG alleviated liver injury, steatosis, and intestinal barrier injury caused by alcohol, and enhanced ZO-1 and Claudin-1 expressions. Furthermore, IL-22 knockdown increased ALT, TG, and AST levels in serum, and aggravated liver injury, steatosis, and intestinal barrier injury. ZO-1 and Claudin-1 levels were downregulated by IL-22 silencing. Importantly, downregulation of IL-22 reversed the effect of LGG on the liver and intestinal barrier injury. To conclude, LGG protects against chronic alcohol-induced intestinal and liver injury via regulating the intestinal IL-22 signaling pathway.

Extracts of Dracocephalum tanguticum Maxim Ameliorate Acute Alcoholic Liver Disease via Regulating Transcription Factors in Mice

Alcoholic liver disease (ALD) caused by excessive drinking is a health and economic concern worldwide. Given the high morbidity, mortality, and the progressive nature of ALD, finding effective interventions is essential. Previous studies have confirmed that edible food plants and their bioactive compounds exert a protective effect against ALD. Dracocephalum tanguticum Maxim (DTM) is one of the important traditional Tibetan medicines in China with the effect of clearing away liver heat, used for the treatment of hepatitis. In this study, the DTM chloroform extract (DtM-C), ethyl acetate extract (DtM-E), and n-butanol extract (DtM-B) were obtained by ethanol extraction combined with fractional extraction. Acute ALD was induced in mice given intragastric ethanol. Serum and liver biochemical markers were detected by ELISA. Liver histological observation, Oil Red O, and Masson's trichrome staining were performed. Liver injury cells were induced by ethanol. The cell vitality was detected by using MTT colorimetry. The expressions of Nrf2, NF-κB, STAT3, AP-1, CREB, HIF-1α, HO-1, NQO-1, GSTA1, IKB2, and Keap1 were detected by real-time polymerase chain reaction (PCR) to elucidate the mechanism of hepatoprotective effect, and the results were verified by using Western blot. The results of serum liver function indicators (ALT, AST, and ADH), serum hepatic lipid indicators (TC, TG, HDL-C, and LDL-C), and lipid peroxidation indicators (ADH, MDA, SOD, CAT, and GSH-Px) in liver tissue and liver histological observation showed that DtM-E could improve liver function, alleviate fatty degeneration, edema, cell necrosis, and liver fibrosis caused by alcohol. DtM-E also increased the vitality of EtOH-induced liver injury cells, upregulated the mRNA expression of Nrf2, HO-1, NQO-1, and GSTA1, while downregulated the expression of Keap-1, p65, and NF-κB. Western blot results were consistent with PCR. The results suggest that DtM-E has a protective effect against ALD in vitro and in vivo, and its mechanism of action may be related to the activation of Nrf2/Keap-1 and inhibition of the P65/NF-κB signaling pathways.

The Protective Effects of Ganoderic Acids from Ganoderma lucidum Fruiting Body on Alcoholic Liver Injury and Intestinal Microflora Disturbance in Mice with Excessive Alcohol Intake

This study aimed to investigate the protective effects of ganoderic acids (GA) from Ganoderma lucidum against liver injury and intestinal microbial disorder in mice with excessive alcohol intake. Results showed GA supplement significantly inhibited the abnormal elevation of the liver index, serum lipid parameters, aspartate aminotransferase and alanine aminotransferase in mice exposed to alcohol intake, and also significantly protected the excessive lipid accumulation and pathological changes. Alcohol-induced oxidative stress in the liver was significantly ameliorated by GA intervention through reducing the levels of maleic dialdehyde and lactate dehydrogenase and increasing the levels of glutathione, catalase, superoxide dismutase and alcohol dehydrogenase. Intestinal microbiota profiling demonstrated GA intervention modulated the composition of intestinal microflora by increasing the levels of Lactobacillus, Faecalibaculum, Romboutsia, Bifidobacterium and decreasing the Helicobacter level. Furthermore, liver metabolomic profiling suggested GA intervention had a remarkable regulatory effect on liver metabolism with excessive alcohol consumption. Moreover, GA intervention regulated mRNA levels of alcohol metabolism, fatty lipid metabolism, oxidative stress, bile acid biosynthesis and metabolism-related genes in the liver. Conclusively, these findings demonstrate GA intervention can significantly relieve alcoholic liver injury and it is hopeful to become a new functional food ingredient for the prevention of alcoholic liver injury.

Developing natural marine products for treating liver diseases

In recent years, marine-derived bioactive compounds have gained increasing attention because of their higher biodiversity vs land-derived compounds. A number of marine-derived compounds are proven to improve lipid metabolism, modulate the gut microbiota, and possess anti-inflammatory, antioxidant, antibacterial, antiviral, and antitumor activities. With the increasing understanding of the molecular landscape underlying the pathogenesis of chronic liver diseases, interest has spiked in developing new therapeutic drugs and medicine food homology from marine sources for the prevention and treatment of liver diseases.

Xenobiotic-Induced Aggravation of Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD), which is often linked to obesity, encompasses a large spectrum of hepatic lesions, including simple fatty liver, steatohepatitis, cirrhosis and hepatocellular carcinoma. Besides nutritional and genetic factors, different xenobiotics such as pharmaceuticals and environmental toxicants are suspected to aggravate MAFLD in obese individuals. More specifically, pre-existing fatty liver or steatohepatitis may worsen, or fatty liver may progress faster to steatohepatitis in treated patients, or exposed individuals. The mechanisms whereby xenobiotics can aggravate MAFLD are still poorly understood and are currently under deep investigations. Nevertheless, previous studies pointed to the role of different metabolic pathways and cellular events such as activation of de novo lipogenesis and mitochondrial dysfunction, mostly associated with reactive oxygen species overproduction. This review presents the available data gathered with some prototypic compounds with a focus on corticosteroids and rosiglitazone for pharmaceuticals as well as bisphenol A and perfluorooctanoic acid for endocrine disruptors. Although not typically considered as a xenobiotic, ethanol is also discussed because its abuse has dire consequences on obese liver.

Diallyl disulfide suppresses the lipopolysaccharide-driven inflammatory response of macrophages by activating the Nrf2 pathway

Lipopolysaccharide (LPS)-driven activation of Kupffer cells plays critical roles in the development of alcoholic liver disease (ALD). Accumulating evidence has revealed that nuclear factor erythroid 2-related factor 2 (Nrf2) can modulate the polarization of macrophages. The current study aimed to investigate the roles of diallyl disulfide (DADS) in LPS-driven inflammation in vitro and in vivo. We found that DADS significantly increased the nuclear translocation of Nrf2 and the transcription of Nrf2 targets, including HO1, NQO1, and γ-GCSc, and suppressed degradation of Nrf2 protein. Besides, DADS significantly inhibited LPS-induced activation of NF-κB and MAPK, secretion of NO and TNF-α, and production of reactive oxygen species (ROS) in LPS-exposed RAW264.7 cells. In vivo study demonstrated that DADS significantly ameliorated liver damage in mice challenged with LPS, as shown by the inhibition of increases in serum aminotransferase activities, neutrophil infiltration, and NF-κB and NLRP3 inflammasome activation. Finally, knockout of Nrf2 abrogated the suppression of DADS on macrophage polarization and on liver injury induced by LPS. These findings reveal that DADS suppresses LPS-driven inflammatory response in the liver by activating Nrf2, which suggests that the protective effects of DADS against ALD may be attributed to the modulation of Kupffer cell polarization in the liver.

The effects of Gentiana dahurica Fisch on alcoholic liver disease revealed by RNA sequencing

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Gentiana dahurica Fisch (called Qin-Jiao in China), a traditional Chinese medicine, is used in China to treat alcoholic liver disease (ALD), but there has been no scientific report on the treatment of ALD.

AIM OF THE STUDY

To investigate the therapeutic effects of Gentiana dahurica Fisch ethanol extract (GDEE) on ALD and to reveal its possible mechanism of action using RNA sequencing.

MATERIALS AND METHODS

The model of ALD was established by continuous gavage with alcohol in mice, and GDEE was used to treat ALD. Pathological observation (HE staining, oil red O staining) and biochemical indicators were performed to evaluate liver tissue lesions and efficacy of GDEE. RNA sequencing analysis of liver tissues was carried out to elucidate the pathogenesis of ALD and the mechanism of hepatoprotective effect by GDEE. The RNA sequencing results were verified by detecting mRNA and protein expressions of acetyl coenzyme A carboxylase α (Acacα), fatty acid synthase (Fasn) and carnitine palmitoyltransferase 1A (Cpt1a) by quantitative real-time polymerase chain reaction (PCR) and Western blot.

RESULTS

Measurements of biochemical parameters showed that GDEE could inhibit the increased transaminase activities in the serum and lipid levels in the liver caused by alcohol. It was observed that GDEE could alleviate fatty degeneration, edema and cell necrosis caused by alcohol in the liver tissue. RNA sequencing analysis of liver tissues found that 719 genes and 1137 genes were significantly changed by alcohol and GDEE, respectively. GDEE reversed most of the changes in triglycerides synthesis-related genes up-regulated by alcohol. GDEE up-regulated most of the genes involved in the fatty acid degradation in ALD mice, while alcohol had little effect on them. In addition, GDEE suppressed most of the genes involved in cholesterol synthesis that were up-regulated by alcohol. GDEE up-regulated genes related to bile acid synthesis in ALD mice, and down-regulated genes related to bile acid reabsorption, while alcohol had no significant effect on genes related to bile acid metabolism. In the validation experiments, the Acacα, Fasn and Cpt1a expressions quantified by real-time PCR and Western blot were consistent with the RNA sequencing results.

CONCLUSIONS

GDEE can alleviate liver damage and steatosis in ALD mice, and its mechanism of action may be related to the process of regulating triglycerides and cholesterol.

Magnesium Metabolism in Chronic Alcohol-Use Disorder: Meta-Analysis and Systematic Review

Chronic alcohol-use disorder has been imputed as a possible cause of dietary magnesium depletion. The purpose of this study was to assess the prevalence of hypomagnesemia in chronic alcohol-use disorder, and to provide information on intracellular magnesium and on its renal handling. We carried out a structured literature search up to November 2020, which returned 2719 potentially relevant records. After excluding non-significant records, 25 were retained for the final analysis. The meta-analysis disclosed that both total and ionized circulating magnesium are markedly reduced in chronic alcohol-use disorder. The funnel plot and the Egger’s test did not disclose significant publication bias. The I²-test demonstrated significant statistical heterogeneity between studies. We also found that the skeletal muscle magnesium content is reduced and the kidney’s normal response to hypomagnesemia is blunted. In conclusion, magnesium depletion is common in chronic alcohol-use disorder. Furthermore, the kidney plays a crucial role in the development of magnesium depletion.

Protective Mechanism of Edible Food Plants against Alcoholic Liver Disease with Special Mention to Polyphenolic Compounds

Alcoholic liver disease (ALD) is one type of liver disease, causing a global healthcare problem and mortality. The liver undergoes tissue damage by chronic alcohol consumption because it is the main site for metabolism of ethanol. Chronic alcohol exposure progresses from alcoholic fatty liver (AFL) to alcoholic steatohepatitis (ASH), which further lead to fibrosis, cirrhosis, and even hepatocellular cancer. Therapeutic interventions to combat ALD are very limited such as use of corticosteroids. However, these therapeutic drugs are not effective for long-term usage. Therefore, additional effective and safe therapies to cope with ALD are urgently needed. Previous studies confirmed that edible food plants and their bioactive compounds exert a protective effect against ALD. In this review article, we summarized the hepatoprotective potential of edible food plants and their bioactive compounds. The underlying mechanism for the prevention of ALD by edible food plants was as follows: anti-oxidation, anti-inflammation, lipid regulation, inhibition of apoptosis, gut microbiota composition modulation, and anti-fibrosis.

FOXO4 ameliorates alcohol-induced chronic liver injury via inhibiting NF-κB and modulating gut microbiota in C57BL/6J mice

BACKGROUND

Intestinal mucosa barrier function and gut-liver axis are impaired by ethanol in chronic alcoholic liver disease (ALD). However, the possible mechanism is not clear. This study aimed to investigate the effects of Forkhead Box O4 (FOXO4) on alcohol-induced chronic liver injury and its molecular mechanism(s).

METHODS

Male C57BL/6J mice were injected with or without FOXO4-WT, FOXO4-TB or NF-κB vectors, and fed with Lieber-DeCarli liquid diets containing 36% ethanol for eight weeks to induce chronic ALD. Thereafter, blood, liver, colon and fecal samples were collected. Biochemical parameters, endotoxin and inflammatory cytokines in the blood and antioxidant enzymes in the liver were tested by commercial kits. Histopathological changes in the liver were evaluated by HE staining. In addition, the mRNA and protein expression of FOXO4, NF-κB, ZO-1 and Occluding in the colon were measured by quantitative real-time PCR and Western blot, respectively. Furthermore, gut microbiota composition in the fecal samples was investigated with 16S rDNA sequencing.

RESULTS

FOXO4 significantly ameliorated liver histopathological damage. Moreover, FOXO4 reduced the serum endotoxin, biochemical parameters (ALT, AST, ALP and TG), antioxidant enzymes (ROS and MDA), inflammatory cytokines (IL-6, IL-1β, and TNF-α), but restored the levels of GSH, SOD and IL-10. Furthermore, FOXO4 significantly inhibited the expression of NF-κB, p-NF-κB p65, p-IKKα and p-IKKβ, and up-regulated the expression of ZO-1 and Occludin. Additionally, FOXO4 modulated the gut microbiota composition and certain bacteria including Odoribacter, Parasutterella and Psychrobacter.

CONCLUSION

These findings suggest that FOXO4 protects against alcohol-induced chronic liver injury via inhibiting NF-κB and modulating gut microbiota in C57BL/6J mice.

Lactobacillus plantarum KLDS1.0344 and Lactobacillus acidophilus KLDS1.0901 Mixture Prevents Chronic Alcoholic Liver Injury in Mice by Protecting the Intestinal Barrier and Regulating Gut Microbiota and Liver-Related Pathways

Health and wellbeing are significantly impaired by alcoholic liver disease (ALD), and although some lactic acid bacteria strains have been shown previously to relieve ALD symptoms, the mechanisms behind these effects are still unclear. Here, the Lieber-DeCarli liquid diet containing alcohol was fed to C57BL/6J mice for 6 weeks to build a chronic alcoholic liver lesion model to study the protective effects and possible mechanisms of Lactobacillus mixture (Lactobacillus plantarum KLDS1.0344 and Lactobacillus acidophilus KLDS1.0901). The results showed that Lactobacillus mixture improved intestinal epithelial permeability and reduced the serum lipopolysaccharide (LPS) levels. Furthermore, Lactobacillus mixture inhibited liver lipid accumulation, oxidative stress, and inflammation by regulating AMPK, Nrf-2, and TLR4/NF-κB pathways. Importantly, the Lactobacillus mixture modulated the gut microbiota, resulting in increased short-chain fatty acid (SCFA) producers and decreased Gram-negative bacteria. Taken together, these findings indicated that the Lactobacillus mixture could positively regulate the gut microbiota, causing increased levels of SCFAs, which inhibited alcohol-induced liver lipid accumulation and oxidative stress through the gut-liver axis. Moreover, following administration of the Lactobacillus mixture, the improvement of intestinal epithelial permeability and the reduction of Gram-negative bacteria led to the decrease of LPS entering the portal vein, thereby inhibiting alcohol-induced liver inflammation.

Contribution of glutaredoxin-1 to Fas s-glutathionylation and inflammation in ethanol-induced liver injury

AIMS

The reversible protein S-glutathionylation (PSSG) modification of Fas augments apoptosis, which can be reversed by the cytosolic deglutathionylation enzyme glutaredoxin-1 (Grx1), but its roles in alcoholic liver injury remain unknown. Therefore, the objective of this study was to investigate the impact of genetic ablation of Grx1 on Fas S-glutathionylation (Fas-SSG) in regulating ethanol-induced injury.

MATERIALS AND METHODS

We evaluated the Grx1 activity and oxidative damage, hepatic injury related indicators, Fas-SSG, we also assess the nuclear factor-κB (NF-κB) signaling, its downstream signal, and Akt signaling cascades, Furthermore, the number of Kupffer cells and related proinflammatory cytokines between WT and Grx1- groups after alcohol exposure.

KEY FINDINGS

Ethanol-fed mice had increased Grx1 activity and oxidative damage in the liver. Grx1-deficient mice had more serious liver damage when exposed to ethanol compared to that of wild-type mice, accompanied by increased alanine aminotransferase and aspartate aminotransferase levels, Fas-SSG, cleaved caspase-3 and hepatocyte apoptosis. Grx1 ablation resulted in the suppression of ethanol-induced NF-κB signaling, its downstream signal, and Akt signaling cascades, which are required for protection against Fas-mediated apoptosis. Accordingly, blocking NK-κB prevented Fas-induced apoptosis in WT mice but not Grx1-/- mice. Furthermore, the number of Kupffer cells and related proinflammatory cytokines, including Akt, were lower in Grx1-/- livers than those of the controls.

SIGNIFICANCE

Grx1 is essential for adaptation to alcohol exposure-induced oxidative injury by modulating Fas-SSG and Fas-induced apoptosis.

Alcohol associated liver disease 2020: A clinical practice guideline by the Italian Association for the Study of the Liver (AISF)

Alcohol use disorder which includes alcohol abuse and dependence represents one of the leading risk factors for premature mortality in Europe and it is responsible of over 200 conditions, including neuropsychiatric disorders, chronic diseases, cancers and accidents leading to permanent disability. Alcohol use disorder represents the most common cause of liver damage in the Western world, with a wide spectrum of diseases ranging from steatosis, steatohepatitis, fibrosis, cirrhosis and cancer. The present clinical practice guidelines by the Italian Association for the Study of the Liver (AISF) are focused on the current knowledge about epidemiology, pathophysiology, clinical features, diagnosis and treatment of alcohol associated liver disease, aiming to provide practical recommendations on the management of this complex pathological condition.

Mechanisms, biomarkers and targets for therapy in alcohol-associated liver injury: From Genetics to nutrition: Summary of the ISBRA 2018 symposium

The symposium "Mechanisms, Biomarkers and Targets for Therapy in Alcohol-associated Liver Injury: From Genetics to Nutrition" was held at the 19th Congress of International Society for Biomedical Research on Alcoholism on September 13th, 2018 in Kyoto, Japan. The goal of the symposium was to discuss the importance of genetics and nutrition in alcoholic liver disease (ALD) development from mechanistic and therapeutic perspectives. The following is a summary of this session addressing the gene polymorphisms in ALD, the role of zinc in gut-liver axis perturbations associated with ALD, highlighting the importance of dietary fat in ALD pathogenesis, the hepatic n6 and n3 PUFA oxylipin pattern associated with ethanol-induced liver injury, and finally deliberating on new biomarkers for alcoholic hepatitis and their implications for diagnosis and therapy. This summary of the symposium will benefit junior and senior faculty currently investigating alcohol-induced organ pathology as well as undergraduate, graduate, and post-graduate students and fellows.

The hepatoprotective activities of Kalimeris indica ethanol extract against liver injury in vivo

Kalimeris indica (L.) Sch. Bip. is a traditional Chinese medicine (TCM) and a portion of food used for cooking in China. It has been demonstrated that an ethanol extract of K. indica has an anti-inflammatory effect by inhibition of nitric oxide (NO) production on murine macrophage RAW264.7 cells after lipopolysaccharide (LPS) induction. In this study, the hepatoprotective effects of the total phenolics of K. indica (TPK), the total triterpenes of K. indica (TTK), and the total flavones of K. indica (TFK) from ethanol extracts of K. indica were evaluated in Bacille Calmette-Guerin (BCG)/LPS-induced liver injury in vivo. The treatments of TPK, TTK, and TFK improved liver injury in mice. Additionally, all treatments significantly not only reduced the hepatic malondialdehyde (MDA) content and hepatic total nitric oxide synthase (tNOS) but also induced the hepatic superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity. The treatments of TPK and TTK significantly reduced the hepatic inducible nitric oxide synthase (iNOS). The treatments of TPK, TTK, and TFK reduced the serum total bilirubin (T-Bil), and only TFK treatment reduced the serum alanine aminotransferase (ALT). Our results suggest that TPK, TTK, and TFK from ethanol extracts of K. indica might play an essential protective role against BCG/LPS-induced liver injury in vivo.

Serum lipopolysaccharides predict advanced liver disease in the general population

Background & Aims

Gut-derived endotoxemia has been implicated in the development of chronic liver disease, but its relevance at the population level remains unclear. We analyzed whether endotoxemia is associated with incident advanced liver disease in the general population.

Methods

Serum lipopolysaccharide (LPS) was measured in 6,727 (3,455 male and 3,272 female, mean age 53.4 ± 10.9 years, mean body mass index 27.2 ± 4.5) individuals participating in the Finnish population-based health examination survey FINRISK 1997. Data were linked with electronic health registers for incident advanced liver disease (hospitalization, cancer or death related to liver disease). During a mean follow-up of 16.3 ± 3.8 years (109,282 person-years), 86 liver events occurred. Univariate and multivariate Cox regression, and Kaplan-Meier analyses were performed.

Results

Serum LPS predicted incident advanced liver disease with a hazard ratio per 1 SD of 1.41 (95% CI 1.24–1.59; p ≪0.001) when adjusted for age, sex, gamma-glutamyltransferase, metabolic syndrome, alcohol use, patatin-like phospholipase domain-containing protein 3 (PNPLA3) I148M, waist-hip ratio and type 2 diabetes. This association remained robustly significant in additional multivariate analyses with various levels of adjustment. The association was accentuated among carriers of the PNPLA3 risk variant. The population attributable fraction of the highest LPS tertile for liver events was 29.7%. However, LPS was not associated with all-cause mortality.

Conclusion

Serum LPS is associated with hospitalization, cancer or death related to liver disease in the general population, with the highest tertile potentially accounting for 30% of the risk of liver disease.

Lay summary

Lipopolysaccharide, a gut-derived bacterial endotoxin, has been implicated in the development of chronic liver disease, but its relevance at the population level remains unclear. We found that serum lipopolysaccharide levels were associated with incident advanced liver disease in the general population, with the highest tertile accounting for up to 30% of the risk of hospitalization, cancer or death related to liver disease.

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Serum LPS was associated with incident advanced liver disease in the general population.

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LPS was associated with liver-related risk of hospitalization, cancer or death.

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The highest LPS tertile may account for up to 30% of the risk of incident liver disease.

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The risk of liver disease was accentuated among carriers of the PNPLA3 I143M.

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Serum LPS was not associated with all-cause mortality.

Binge Alcohol Is More Injurious to Liver in Female than in Male Rats: Histopathological, Pharmacologic, and Epigenetic Profiles

Binge alcohol consumption is a health problem, but differences between the sexes remain poorly defined. We have examined the in vivo effects of three acute, repeat binge alcohol administration on the liver in male and female rats. Sprague-Dawley rats were gavaged with alcohol (5 g/kg body weight) three times at 12-hour intervals. Blood and liver tissues were collected 4 hours after the last binge ethanol. Subsequently, several variables were analyzed. Compared with male rats, females had higher levels of blood alcohol, alanine aminotransferase, and triglycerides. Liver histology showed increased lipid vesicles that were larger in females. Protein levels of liver cytochrome P4502E1 were higher in the liver of females than in the liver of males after binge. Hepatic phospho-extracellular signal-regulated kinase 1/2 and phosph-p38 mitogen-activated protein kinase levels were lower in females compared with males after binge alcohol, but no differences were found in the phospho-C-jun N-terminal kinase levels. Peroxisome proliferator-activated receptor γ-coactivator 1α and cyclic AMP response element binding (CREB) protein levels increased more in female than in male livers; however, increases in phospho-CREB levels were lower in females. Remarkably, c-fos was reduced substantially in the livers of females, but no differences in c-myc protein were found. Binge ethanol caused elevation in acetylated (H3AcK9) and phosphoacetylated (H3AcK9PS10) histone H3 in both sexes but without any difference. Binge alcohol caused differential alterations in the levels of various species of phosphatidylethanol and a larger increase in the diacylglycerol kinase-α protein levels in the liver of female rats compared with male rats. These data demonstrate, for the first time, similarities and differences in the sex-specific responses to repeat binge alcohol leading to an increased susceptibility of female rats to have liver injury in vivo. SIGNIFICANCE STATEMENT: This study examines the molecular responses of male and female rat livers to acute binge alcohol in vivo and demonstrates significant differences in the susceptibility between sexes.