Alcoholic hepatitis: Translational approaches to develop targeted therapies

Cholestasis in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) is a leading cause of liver-related morbidity and mortality. ALD covers a spectrum of diseases, ranging from mild and reversible hepatic steatosis to the development of fibrosis, cirrhosis, and alcohol-associated hepatitis (AH). AH is marked by a rapid onset of jaundice and elevated serum levels of aspartate aminotransferase in individuals with heavy alcohol use. It can progress to acute-on-chronic liver failure, with a mortality rate of approximately 30% within the first month. Unfortunately, treatment options for AH are still limited. Cholestasis refers to an impairment in bile formation or flow, leading to clinical symptoms, such as fatigue, pruritus, and jaundice. Cholestasis and biliary dysfunction are commonly seen in patients with AH and can significantly worsen the prognosis. However, the mechanisms and roles of cholestasis in ALD are not yet fully understood. In this review, we will summarize recent findings and explore the potential roles and mechanisms of cholestasis in the progression of ALD.

New Insights into the Pathogenesis of Alcoholic Liver Disease Based on Global Research

BACKGROUND AND AIMS

Alcoholic liver disease (ALD) is the leading cause of death among alcohol-related diseases, yet its pathogenesis remains incompletely understood. This article employs data mining methods to conduct an indepth study of articles on ALD published in the past three decades, aiming to elucidate the pathogenesis of ALD.

METHODS

Firstly, articles related to the pathogenesis of ALD were retrieved from the Web of Science (WOS) database. CiteSpace 6.1.R2 and VOSviewer 1.6.18 were used to visually analyze the authors, institutions, journals, and keywords of the published articles. Secondly, by thoroughly reading the top 100 most cited articles and focusing on research hotspots such as cytochrome P450 2E1 (CYP2E1), gut microbiota, acetaldehyde dehydrogenase (ALDH), and alcohol dehydrogenase (ADH), the pathogenesis of ALD was preliminarily explored. Finally, the pathogenesis of ALD was further analyzed based on disease databases.

RESULTS

A total of 1521 articles were retrieved from the WOS database, and 384 of these were selected for in-depth reading. From GeneCards, 9084 genes related to ALD were identified. KEGG enrichment analysis was performed using DAVID, and the hsa04936: Alcoholic liver disease pathway was selected for visualization.

CONCLUSIONS

This study preliminarily elucidates the pathogenesis of ALD, which may be associated with the release of acetaldehyde, reactive oxygen species (ROS), and various pro-inflammatory factors during alcohol metabolism. It is also closely related to gut microbiota dysbiosis and increased intestinal permeability induced by multiple factors.

Silencing FAF2 mitigates alcohol-induced hepatic steatosis by modulating lipolysis and PCSK9 pathway

BACKGROUND

Chronic alcohol consumption leads to lipid accumulation, oxidative stress, cellular damage, and inflammation in the liver, collectively referred to as alcohol-associated liver disease (ALD). FAF2/UBXD8/ETEA (Fas-associated factor 2) is a ubiquitin ligase adaptor protein that plays a crucial role in the ubiquitin-mediated degradation of misfolded proteins in the endoplasmic reticulum. A recent genome-wide association study indicated an association between FAF2 and ALD; however, the exact contribution of FAF2 to ALD pathogenesis remains unclear.

METHODS

FAF2 was knocked down using AAV-delivered shRNA in C57/BL6 mice. Mice were subjected to a chronic-plus-single binge ethanol feeding (NIAAA) model. Nine hours after gavage, liver, blood, and other organs of interest were collected for gene expression and biochemical analyses.

RESULTS

We first observed a significant elevation in hepatic FAF2 protein expression in individuals with ALD and in mice subjected to an ethanol-binge model. Interestingly, knocking down FAF2 in the liver using adeno-associated virus serotype 8-delivered short hairpin RNA conferred a protective effect against alcohol-induced liver steatosis in ethanol-binged mice. Transcriptomic analysis revealed that differentially expressed genes were enriched in multiple lipid metabolism regulation pathways. Further analysis of transcription factors regulating these differentially expressed genes suggested potential regulation by SREBP1. Several SREBP1 target genes, including Fasn, Scd1, Lpin1, and Pcsk9 (proprotein convertase subtilisin/kexin type 9), were dysregulated in the livers of ethanol-fed FAF2 knockdown mice. Additionally, Pcsk9 could be regulated through the FOXO3-SIRT6 pathway in the livers of ethanol-fed FAF2 knockdown mice, leading to increased liver low-density lipoprotein receptor expression and reduced plasma LDL cholesterol levels. Furthermore, FAF2 knockdown in mouse liver enhanced adipose triglyceride lipase lipolytic activity by upregulating the adipose triglyceride lipase activator, comparative gene identification-58, and downregulating the adipose triglyceridelipase transport inhibitor, Elmod2, contributing to the alleviation of liver steatosis.

CONCLUSIONS

Our study uncovers a novel mechanism involving FAF2 in the pathogenesis of ALD.

Novel treatment of acute and acute-on-chronic liver failure: Interleukin-22

Acute liver failure (ALF) is a life-threatening medical condition, characterized by rapidly progressive hepatic dysfunction, coagulopathy and hepatic encephalopathy in patients without chronic liver disease, while acute-on-chronic liver failure (ACLF) occurs in patients with existing chronic liver disease. ALF and ACLF are often associated with multiple organ failure and a high short-term mortality. In this review, we briefly discuss the causes and pathogenesis of ALF and ACLF, the current options available for the treatment of both deadly maladies and interleukin-22 (IL-22), a novel promising drug that may have great therapeutic potential for ALF and ACLF treatment. IL-22 is a cytokine produced by immune cells but mainly targets epithelial cells including hepatocytes. IL-22 has been shown to protect against organ damage and reduce bacterial infection in many preclinical models and several clinical trials including alcohol-associated hepatitis. The potential application of IL-22 for the treatment of ALF and ACLF is also elaborated.

Alcohol-associated liver disease: Natural history, management and novel targeted therapies

Alcohol consumption is a leading cause of preventable morbidity and mortality worldwide and the primary cause of advanced liver disease. Alcohol use disorder is a chronic, frequently relapsing condition characterized by persistent alcohol consumption despite its negative consequences. Alcohol-associated liver disease (ALD) encompasses a series of stages, from fatty liver (steatosis) to inflammation (steatohepatitis), fibrosis, and, ultimately, liver cirrhosis and its complications. The development of ALD is complex, involving both genetic and environmental factors, yet the exact mechanisms at play remain unclear. Alcohol-associated hepatitis (AH), a severe form of ALD, presents with sudden jaundice and liver failure. Currently, there are no approved targeted therapies able to interfere in the pathogenesis of ALD to stop the progression of the disease, making alcohol abstinence the most effective way to improve prognosis across all stages of ALD. For patients with advanced ALD who do not respond to medical therapy, liver transplantation is the only option that can improve prognosis. Recently, AH has become an early indication for liver transplantation in non-responders to medical treatment, showing promising results in carefully selected patients. This review provides an update on the epidemiology, natural history, pathogenesis, and current treatments for ALD. A deeper insight into novel targeted therapies investigated for AH focusing on new pathophysiologically-based agents is also discussed, including anti-inflammatory and antioxidative stress drugs, gut-liver axis modulators, and hepatocyte regenerative molecules.

Research Priorities and Future Landscape of Clinical Trials in Alcohol-Associated Liver Disease

Liver is the most common organ affected by alcohol misuse. The spectrum of alcohol-associated liver disease (ALD) ranges from simple steatosis to cirrhosis and its complications. The unique clinical phenotype of alcohol-associated hepatitis has a risk for high short-term mortality. Several gaps exist with respect to epidemiology, noninvasive testing, prognostication, and treatment of ALD. Most studies focus on short-term survival as the ideal endpoint and ignore other aspects of alcohol-use disorder and ALD. In this review, the authors discuss the existing knowledge gaps, enumerate ongoing clinical trials, and highlight the research priorities and future landscape of clinical trials.

Cholestatic insult triggers alcohol-associated hepatitis in mice

BACKGROUND

Alcohol-associated hepatitis (AH) is a severe, potentially life-threatening form of alcohol-associated liver disease with limited therapeutic options. Existing evidence shows that biliary dysfunction and cholestasis are common in patients with AH and are associated with poorer prognosis. However, the role of cholestasis in the development of AH is largely unknown. We aimed to examine the hypothesis that cholestasis can be an important etiology factor for AH.

METHODS

To study the interaction of cholestasis and alcohol, chronically ethanol (EtOH)-fed mice were challenged with a subtoxic dose of α-naphthylisothiocyanate (ANIT), a well-studied intrahepatic cholestasis inducer. Liver injury was measured by biochemical and histological methods. RNAseq was performed to determine hepatic transcriptomic changes. The impact of inflammation was assessed using an anti-LY6G antibody to deplete the neutrophils and DNase I to degrade neutrophil extracellular traps.

RESULTS

ANIT synergistically enhanced liver injury following a 4-week EtOH feeding with typical features of AH, including increased serum levels of ALT, AST, and total bile acids, cholestasis, necrosis, neutrophil infiltration, and accumulation of neutrophil extracellular traps. RNAseq revealed multiple genes uniquely altered in the livers of EtOH/ANIT-treated mice. Analysis of differentially expressed genes suggested an enrichment of genes related to inflammatory response. Anti-LY6G antibody or DNase I treatment significantly inhibited liver damage in EtOH/ANIT-treated mice.

CONCLUSIONS

Our results support the hypothesis that cholestasis can be a critical contributor to the pathogenesis of AH. A combined treatment of EtOH and ANIT in mice presents biochemical, histological, and molecular features similar to those found in patients with AH, suggesting that this treatment scheme can be a useful model for studying Alcohol-associated Cholestasis and Hepatitis (AlChoHep).

Pathogenesis of Alcohol-Associated Liver Disease

The pathogenesis of alcohol-associated liver disease (ALD) is complex and multifactorial. Several intracellular, intrahepatic, and extrahepatic factors influence development of early fatty liver injury leading to inflammation and fibrosis. Alcohol metabolism, cellular stress, and gut-derived factors contribute to hepatocyte and immune cell injury leading to cytokine and chemokine production. The pathogenesis of alcohol-associated hepatitis (AH), an advanced form of acute-on-chronic liver failure due to excessive chronic intake in patients with underlying liver disease, is not well understood. While pathogenic mechanisms in early ALD are studied, the pathogenesis of AH requires further investigation to help design effective drugs for patients.

Involvement of BRD4 in Alcoholic Liver Injury: Autophagy Modulation via Regulation of the SIRT1/Beclin1 Axis

Alcoholic liver disease (ALD) caused by chronic alcohol abuse involves complex processes from steatosis to fibrosis, cirrhosis, and hepatocellular carcinoma, posing a global health issue. Bromodomain protein 4 (BRD4) typically serves as a "reader" modulating the functions of transcription factors involved in various biological processes and disease progression. However, the specific mechanisms underlying alcoholic liver injury remain unclear. In this study, we detected aberrant BRD4 expression in the alcohol-induced ALD mouse model of chronic and binge ethanol feeding developed by the National Institute on Alcohol Abuse and Alcoholism, consistent with the in vitro results in Aml-12 mouse hepatocytes. Blocking and inhibiting BRD4 restored the impaired autophagic flux and lysosomal functions in alcohol-treated Aml-12 cells, whereas BRD4 overexpression reduced the expression levels of autophagy marker and lysosomal genes. Furthermore, mouse BRD4 knockdown, mediated by a short hairpin RNA carried by the adeno-associated virus serotype 8, significantly attenuated the alcohol-induced hepatocyte damage, including lipid deposition and inflammatory cell infiltration. Mechanistically, BRD4 overexpression in alcoholic liver injury inhibited the expression of sirtuin (SIRT)1 in Aml-12 cells. Chromatin immunoprecipitation and dual-luciferase reporter assays revealed that BRD4 functions as a transcription factor and suppressor, actively binding to the SIRT1 promoter region and inhibiting its transcription. SIRT1 activated autophagy, which was suppressed in alcoholic liver injury via Beclin1 deacetylation. In conclusion, our study revealed that BRD4 negatively regulated the SIRT1/Beclin1 axis and that its deficiency alleviated alcohol-induced liver injury in mice, thus providing a new strategy for ALD treatment.

Molecular targets of PXR-dependent ethanol-induced hepatotoxicity in female mice

The pregnane X receptor (PXR, NR1I2), a xenobiotic-sensing nuclear receptor signaling potentiates ethanol (EtOH)-induced hepatotoxicity in male mice, however, how PXR signaling modulates EtOH-induced hepatotoxicity in female mice is unknown. Wild type (WT) and Pxr-null mice received 5 % EtOH-containing diets or paired-fed control diets for 8 weeks followed by assessment of liver injury, EtOH elimination rates, histology, and changes in gene and protein expression; microarray and bioinformatic analyses were also employed to identify PXR targets in chronic EtOH-induced hepatotoxicity. In WT females, EtOH ingestion significantly increased serum ethanol and alanine aminotransferase (ALT) levels, hepatic Pxr mRNA, constitutive androstane receptor activation, Cyp2b10 mRNA and protein, oxidative stress, endoplasmic stress (phospho-elF2α) and pro-apoptotic (Bax) protein expression. Unexpectedly, EtOH-fed female Pxr-null mice displayed increased EtOH elimination and elevated levels of hepatic acetaldehyde detoxifying aldehyde dehydrogenase 1a1 (Aldh1a1) mRNA and protein, EtOH-metabolizing alcohol dehydrogenase 1 (ADH1), and lipid suppressing microsomal triglyceride transport protein (MTP) protein, aldo-keto reductase 1b7 (Akr1b7) and Cyp2a5 mRNA, but suppressed CYP2B10 protein levels, with evidence of protection against chronic EtOH-induced oxidative stress and hepatotoxicity. While liver injury was not different between the two WT sexes, female sex may suppress EtOH-induced macrovesicular steatosis in the liver. Several genes and pathways important in retinol and steroid hormone biosynthesis, chemical carcinogenesis, and arachidonic acid metabolism were upregulated by EtOH in a PXR-dependent manner in both sexes. Together, these data establish that female Pxr-null mice are resistant to chronic EtOH-induced hepatotoxicity and unravel the PXR-dependent and -independent mechanisms that contribute to EtOH-induced hepatotoxicity.

Metallofullerenol alleviates alcoholic liver damage via ROS clearance under static magnetic and electric fields

Alcoholic liver disease (ALD) is a common chronic redox disease caused by increased alcohol consumption. Abstinence is a major challenge for people with alcohol dependence, and approved drugs have limited efficacy. Therefore, this study aimed to explore a new treatment strategy for ALD using ferroferric oxide endohedral fullerenol (Fe3O4@C60(OH)n) in combination with static magnetic and electric fields (sBE). The primary hepatocytes of 8-9-week-old female BALB/c mice were used to evaluate the efficacy of the proposed combination treatment. A mouse chronic binge ethanol feeding model was established to determine the alleviatory effect of Fe3O4@C60(OH)n on liver injury under sBE exposure. Furthermore, the ability of Fe3O4@C60(OH)n to eliminate •OH was evaluated. Alcohol-induced hepatocyte and mitochondrial damage were reversed in vitro. Additionally, the combination therapy reduced liver damage, alleviated oxidative stress by improving antioxidant levels, and effectively inhibited liver lipid accumulation in animal experiments. Here, we used a combination of magnetic derivatives of fullerenol and sBE to further improve the ROS clearance rate, thereby alleviating ALD. The developed combination treatment may effectively improve alcohol-induced liver damage and maintain redox balance without apparent toxicity, thereby enhancing therapy aimed at ALD and other redox diseases.

Reducing Oxidative Stress-Mediated Alcoholic Liver Injury by Multiplexed RNAi of Cyp2e1, Cyp4a10, and Cyp4a14

The prevalence of excessive drinking-related alcoholic liver disease (ALD) is rising, yet therapeutic options remain limited. High alcohol consumption and consequent oxidative metabolism by cytochrome P450 (CYP) can lead to extremely high levels of reactive oxygen species, which overwhelm cellular defenses and harm hepatocytes. Our previous investigations showed that inhibiting Cyp2e1 using RNA interference reduced the incidence of ALD. However, compensatory mechanisms other than CYP2E1 contribute to oxidative stress in the liver. Therefore, we coupled triple siRNA lipid nanoparticles (LNPs) targeting Cyp2e1 with two isoenzymes Cyp4a10 and Cyp4a14 to treat ALD mouse models fed with Lieber-Decarli ethanol liquid diet for 12 weeks at the early (1st week), middle (5th week), and late (9th week) stages. The administration of triple siRNA LNPs significantly ameliorated chronic alcoholic liver injury in mice, and early treatment achieved the most profound effects. These effects can be attributed to a reduction in oxidative stress and increased expression of antioxidant genes, including Gsh-Px, Gsh-Rd, and Sod1. Moreover, we observed the alleviation of inflammation, evidenced by the downregulation of Il-1β, Il-6, Tnf-α, and Tgf-β, and the prevention of excessive lipid synthesis, evidenced by the restoration of the expression of Srebp1c, Acc, and Fas. Finally, triple siRNA treatment maintained normal metabolism in lipid oxidation. In brief, our research examined the possible targets for clinical intervention in ALD by examining the therapeutic effects of triple siRNA LNPs targeting Cyp2e1, Cyp4a10, and Cyp4a14. The in vivo knockdown of the three genes in this study is suggested as a promising siRNA therapeutic approach for ALD.

GRP/GRPR enhances alcohol-associated liver injury through the IRF1-mediated Caspase-1 inflammasome and NOX2-dependent ROS pathway

BACKGROUND AND AIMS

The common characteristics of alcohol-associated liver injury (ALI) include abnormal liver function, infiltration of inflammatory cells, and generation of oxidative stress. The gastrin-releasing peptide receptor (GRPR) is activated by its neuropeptide ligand, gastrin-releasing peptide (GRP). GRP/GRPR appears to induce the production of cytokines in immune cells and promotes neutrophil migration. However, the effects of GRP/GRPR in ALI are unknown.

APPROACH AND RESULTS

We found high GRPR expression in the liver of patients with alcohol-associated steatohepatitis and increased pro-GRP levels in peripheral blood mononuclear cells of these patients compared with that of the control. Increased expression of GRP may be associated with histone H3 lysine 27 acetylation induced by alcohol, which promotes the expression of GRP and then GRPR binding. Grpr-/- and Grprflox/floxLysMCre mice alleviated ethanol-induced liver injury with relieved steatosis, lower serum alanine aminotransferase, aspartate aminotransferase, triglycerides, malondialdehyde, and superoxide dismutase levels, reduced neutrophil influx, and decreased expression and release of inflammatory cytokines and chemokines. Conversely, the overexpression of GRPR showed opposite effects. The pro-inflammatory and oxidative stress roles of GRPR might be dependent on IRF1-mediated Caspase-1 inflammasome and NOX2-dependent reactive oxygen species pathway, respectively. In addition, we verified the therapeutic and preventive effects of RH-1402, a novel GRPR antagonist, for ALI.

CONCLUSIONS

A knockout or antagonist of GRPR during excess alcohol intake could have anti-inflammatory and antioxidative roles, as well as provide a platform for histone modification-based therapy for ALI.

Identification of integrated proteomics and transcriptomics signature of alcohol-associated liver disease using machine learning

Distinguishing between alcohol-associated hepatitis (AH) and alcohol-associated cirrhosis (AC) remains a diagnostic challenge. In this study, we used machine learning with transcriptomics and proteomics data from liver tissue and peripheral mononuclear blood cells (PBMCs) to classify patients with alcohol-associated liver disease. The conditions in the study were AH, AC, and healthy controls. We processed 98 PBMC RNAseq samples, 55 PBMC proteomic samples, 48 liver RNAseq samples, and 53 liver proteomic samples. First, we built separate classification and feature selection pipelines for transcriptomics and proteomics data. The liver tissue models were validated in independent liver tissue datasets. Next, we built integrated gene and protein expression models that allowed us to identify combined gene-protein biomarker panels. For liver tissue, we attained 90% nested-cross validation accuracy in our dataset and 82% accuracy in the independent validation dataset using transcriptomic data. We attained 100% nested-cross validation accuracy in our dataset and 61% accuracy in the independent validation dataset using proteomic data. For PBMCs, we attained 83% and 89% accuracy with transcriptomic and proteomic data, respectively. The integration of the two data types resulted in improved classification accuracy for PBMCs, but not liver tissue. We also identified the following gene-protein matches within the gene-protein biomarker panels: CLEC4M-CLC4M, GSTA1-GSTA2 for liver tissue and SELENBP1-SBP1 for PBMCs. In this study, machine learning models had high classification accuracy for both transcriptomics and proteomics data, across liver tissue and PBMCs. The integration of transcriptomics and proteomics into a multi-omics model yielded improvement in classification accuracy for the PBMC data. The set of integrated gene-protein biomarkers for PBMCs show promise toward developing a liquid biopsy for alcohol-associated liver disease.

LPS-TLR4 pathway exaggerates alcoholic hepatitis via provoking NETs formation

BACKGROUND

Intrahepatic infiltration of neutrophils is a character of alcoholic hepatitis (AH) and neutrophil extracellular traps (NETs) are an important strategy for neutrophils to fix and kill invading microorganisms. The gut-liver axis has been thought to play a critical role in many liver diseases also including AH. However, whether NETs appear in AH and play role in AH is still unsure.

METHODS

Serum samples from AH patients were collected and LPS and MPO-DNA were detected. WT, NE KO, and TLR4 KO mice were used to build the AH model, and the intestinal bacteria were eliminated at the same time and LPS was given. Then the formation of NETs and AH-related markers were detected.

RESULTS

The serum MPO-DNA and LPS concentration was increased in AH patients and a correlation was revealed between these two indexes. More intrahepatic NETs formed in AH mice. NETs formation decreased with antibiotic intervention and restored with antibiotic intervention plus LPS supplement. While NETs formation failed to change with gut microbiome or combine LPS supplement in TLR4 KO mice. As we tested AH-related characters, liver injury, intrahepatic fat deposition, inflammation, and fibrosis alleviated with depletion of NE. These related marks were also attenuated with gut sterilization by antibiotics and recovered with a combined treatment with antibiotics plus LPS. But the AH-related markers did show a difference in TLR4 KO mice when they received the same treatment.

CONCLUSION

Intestinal-derived LPS promotes NETs formation in AH through the TLR4 pathway and further accelerates the AH process by NETs.

The health benefits of dietary short-chain fatty acids in metabolic diseases

Short-chain fatty acids (SCFAs) are a subset of fatty acids that play crucial roles in maintaining normal physiology and developing metabolic diseases, such as obesity, diabetes, cardiovascular disease, and liver disease. Even though dairy products and vegetable oils are the direct dietary sources of SCFAs, their quantities are highly restricted. SCFAs are produced indirectly through microbial fermentation of fibers. The biological roles of SCFAs in human health and metabolic diseases are mainly due to their receptors, GPR41 and GPR43, FFAR2 and FFAR3. Additionally, it has been demonstrated that SCFAs modulate DNMTs and HDAC activities, inhibit NF-κB-STAT signaling, and regulate G(i/o)βγ-PLC-PKC-PTEN signaling and PPARγ-UCP2-AMPK autophagic signaling, thus mitigating metabolic diseases. Recent studies have uncovered that SCFAs play crucial roles in epigenetic modifications of DNAs, RNAs, and post-translational modifications of proteins, which are critical regulators of metabolic health and diseases. At the same time, dietary recommendations for the purpose of SCFAs have been proposed. The objective of the review is to summarize the most recent research on the role of dietary SCFAs in metabolic diseases, especially the signal transduction of SCFAs in metabolic diseases and their functional efficacy in different backgrounds and models of metabolic diseases, at the same time, to provide dietary and nutritional recommendations for using SCFAs as food ingredients to prevent metabolic diseases.

FK-binding protein 5: Possible relevance to the pathogenesis of metabolic dysfunction and alcohol-associated liver disease

The FK506-binding protein (FKBP5) plays significant roles in mediating stress responses by interacting with glucocorticoids, participating in adipogenesis, and influencing various cellular pathways throughout the body. In this review, we described the potential role of FKBP5 in the pathogenesis of two common chronic liver diseases, metabolic dysfunction-associated steatotic liver disease (MASLD), and alcohol-associated liver disease (ALD). We provided an overview of the FK-binding protein family and elucidated their roles in cellular stress responses, metabolic diseases, and adipogenesis. We explored how FKBP5 may mechanistically influence the pathogenesis of MASLD and ALD and provided insights for further investigation into the role of FKBP5 in these two diseases.

Human Precision-Cut Liver Slices: A Potential Platform to Study Alcohol-Related Liver Disease

Alcohol-related liver disease (ALD) encompasses a range of pathological conditions that are complex to study at the clinical and preclinical levels. Despite the global burden of ALD, there is a lack of effective treatments, and mortality is high. One of the reasons for the unsuccessful development of novel therapies is that experimental studies are hindered by the challenge of recapitulating this multifactorial disorder in vitro, including the contributions of hepatotoxicity, impaired lipid metabolism, fibrosis and inflammatory cytokine storm, which are critical drivers in the pathogenesis of ALD in patients and primary targets for drug development. Here, we present the unique characteristics of the culture of human precision-cut liver slices (PCLS) to replicate key disease processes in ALD. PCLS were prepared from human liver specimens and treated with ethanol alone or in combination with fatty acids and lipopolysaccharide (FA + LPS) for up to 5 days to induce hepatotoxic, inflammatory and fibrotic events associated with ALD. Alcohol insult induced hepatocyte death which was more pronounced with the addition of FA + LPS. This mixture showed a significant increase in the cytokines conventionally associated with the prototypical inflammatory response observed in severe ALD, and interestingly, alcohol alone exhibited a different effect. Profibrogenic activation was also observed in the slices and investigated in the context of slice preparation. These results support the versatility of this organotypic model to study different pathways involved in alcohol-induced liver damage and ALD progression and highlight the applicability of the PCLS for drug discovery, confirming their relevance as a bridge between preclinical and clinical studies.

Long non-coding RNA HOX transcript antisense intergenic RNA depletion protects against alcoholic hepatitis through the microRNA-148a-3p/sphingosine 1-phosphate receptor 1 axis

The aggravating role of long noncoding RNA (lncRNA) HOTAIR has been indicated in liver injury caused by hepatic ischemia/reperfusion. However, under the condition of alcoholic hepatitis (AH), its effects remain unclear. The present study aimed to examine the effect of lncRNA HOTAIR on hepatic stellate cell viability and apoptosis during liver injury caused by AH. In the liver tissues of AH rats, HOTAIR and S1PR1 were overexpressed, and microRNA (miR)-148a-3p was poorly expressed. Loss-of-function assays revealed that silencing of HOTAIR alleviated liver injury in AH by inhibiting the activated phenotype of hepatic stellate cells, inflammation, and fibrosis. Using the bioinformatics databases, dual-luciferase, RIP, and FISH assays, we observed that HOTAIR was mainly localized in the cytoplasm of hepatic stellate cells, and HOTAIR could bind specifically to miR-148a-3p. In addition, miR-148a-3p could target S1PR1 expression. Rescue experiments showed that silencing of miR-148a-3p or overexpression of S1PR1 reversed the alleviating effects of HOTAIR silencing on liver injury. Taken together, our findings revealed that HOTAIR regulates hepatic stellate cell proliferation via the miR-148a-3p/S1PR1 axis in liver injury, which may serve as the basis for developing novel therapeutic strategies to treat AH.

Interleukin-11 drives human and mouse alcohol-related liver disease

OBJECTIVE

Alcoholic hepatitis (AH) reflects acute exacerbation of alcoholic liver disease (ALD) and is a growing healthcare burden worldwide. Interleukin-11 (IL-11) is a profibrotic, proinflammatory cytokine with increasingly recognised toxicities in parenchymal and epithelial cells. We explored IL-11 serum levels and their prognostic value in patients suffering from AH and cirrhosis of various aetiology and experimental ALD.

DESIGN

IL-11 serum concentration and tissue expression was determined in a cohort comprising 50 patients with AH, 110 patients with cirrhosis and 19 healthy volunteers. Findings were replicated in an independent patient cohort (n=186). Primary human hepatocytes exposed to ethanol were studied in vitro. Ethanol-fed wildtype mice were treated with a neutralising murine IL-11 receptor-antibody (anti-IL11RA) and examined for severity signs and markers of ALD.

RESULTS

IL-11 serum concentration and hepatic expression increased with severity of liver disease, mostly pronounced in AH. In a multivariate Cox-regression, a serum level above 6.4 pg/mL was a model of end-stage liver disease independent risk factor for transplant-free survival in patients with compensated and decompensated cirrhosis. In mice, severity of alcohol-induced liver inflammation correlated with enhanced hepatic IL-11 and IL11RA expression. In vitro and in vivo, anti-IL11RA reduced pathogenic signalling pathways (extracellular signal-regulated kinases, c-Jun N-terminal kinase, NADPH oxidase 4) and protected hepatocytes and murine livers from ethanol-induced inflammation and injury.

CONCLUSION

Pathogenic IL-11 signalling in hepatocytes plays a crucial role in the pathogenesis of ALD and could serve as an independent prognostic factor for transplant-free survival. Blocking IL-11 signalling might be a therapeutic option in human ALD, particularly AH.

Alcohol-Related Liver Disease: An Overview on Pathophysiology, Diagnosis and Therapeutic Perspectives

Alcohol-related liver disease (ALD) refers to a spectrum of liver manifestations ranging from fatty liver diseases, steatohepatitis, and fibrosis/cirrhosis with chronic inflammation primarily due to excessive alcohol use. Currently, ALD is considered as one of the most prevalent causes of liver disease-associated mortality worldwide. Although the pathogenesis of ALD has been intensively investigated, the present understanding of its biomarkers in the context of early clinical diagnosis is not complete, and novel therapeutic targets that can significantly alleviate advanced forms of ALD are limited. While alcohol abstinence remains the primary therapeutic intervention for managing ALD, there are currently no approved medications for treating ALD. Furthermore, given the similarities and the differences between ALD and non-alcoholic fatty liver disease in terms of disease progression and underlying molecular mechanisms, numerous studies have demonstrated that many therapeutic interventions targeting several signaling pathways, including oxidative stress, inflammatory response, hormonal regulation, and hepatocyte death play a significant role in ALD treatment. Therefore, in this review, we summarized several key molecular targets and their modes of action in ALD progression. We also described the updated therapeutic options for ALD management with a particular emphasis on potentially novel signaling pathways.

HAO1 negatively regulates liver macrophage activation via the NF-κB pathway in alcohol-associated liver disease

Inflammation is a key factor contributing to the progression of alcohol-associated liver disease (ALD). Accumulating data have shown that ethyl alcohol (EtOH) induced liver macrophages activation along with an inflammatory response that contributes to the development of ALD. The liver-specific peroxisomal enzyme hydroxyacid oxidase 1 (HAO1) has been found to be associated with chronic liver disease. But the role of HAO1 remains unknown in ALD. In our study, HAO1 was found to be decreased in ALD patients and EtOH-fed mice. Interestingly, HAO1 expression was reduced in primary hepatocytes, whereas HAO1 was elevated in peripheral blood monocytes from ALD patients and EtOH-fed mice liver macrophages as well as LPS-treated RAW264.7 cells. Moreover, HAO1 knockdown exacerbated the inflammatory response, while HAO1 overexpression inhibited inflammation in LPS-stimulated RAW264.7 cells. Additionally, overexpression or silencing of HAO1 in vitro significantly affected NF-κB signaling pathway. Collectively, the results revealed a key role of HAO1-mediated macrophage activation and may provide a potential target for treating ALD.

Prevalence, co-morbidities, and in-hospital mortality of patients hospitalized with alcohol-associated hepatitis in the United States from 2015 to 2019

BACKGROUND

The goals of our study are to determine the most recent trends in hospitalization, mortality, and healthcare utilization among hospitalized patients with alcohol-associated hepatitis (AH) in the United States.

METHODS

We examined the recent prevalence, co-morbidities, and mortality in hospitalized AH patients in the United States based on the available National Inpatient Sample (NIS) data (2015 to 2019) using appropriate International Classification of Diseases (ICD) codes. We reported our data as national estimates based on the discharge weighting variable (DISCWT). Logistic regression analyses were used to determine factors associated with mortality.

RESULTS

We observed an increase in the total number of hospitalized AH patients from 110,135 in 2015 to 136,620 in 2019, which represented 386 per 100,000 total hospitalizations or 42 per 100,000 US population, which in 2019 was 328 million. Patients were a mean of 48 years old and the majority were White and male. The average length of stay was around 6 days with an overall in-hospital mortality that decreased from 4.19% in 2015 to 3.86% in 2019 (p-value for trend = <0.0001). During the 5-year study period, a total of 24,795 hospitalized AH patients died and 592,885 survived the hospital stay. Those who died were older, had a longer length of stay, and higher hospital charges during the stay. Mortality was significantly greater in patients who presented with complications from portal hypertension, those with acute renal failure, underlying cirrhosis, and sepsis.

CONCLUSIONS

Our study documented the increasing prevalence of hospitalized AH patients and their significant associated healthcare costs and utilization. Our results underscore a continuing unmet and urgent need to identify effective therapies for hospitalized AH patients.

Distinct histopathological phenotypes of severe alcoholic hepatitis suggest different mechanisms driving liver injury and failure

Intrahepatic neutrophil infiltration has been implicated in severe alcoholic hepatitis (SAH) pathogenesis; however, the mechanism underlying neutrophil-induced injury in SAH remains obscure. This translational study aims to describe the patterns of intrahepatic neutrophil infiltration and its involvement in SAH pathogenesis. Immunohistochemistry analyses of explanted livers identified two SAH phenotypes despite a similar clinical presentation, one with high intrahepatic neutrophils (Neuhi), but low levels of CD8+ T cells, and vice versa. RNA-Seq analyses demonstrated that neutrophil cytosolic factor 1 (NCF1), a key factor in controlling neutrophilic ROS production, was upregulated and correlated with hepatic inflammation and disease progression. To study specifically the mechanisms related to Neuhi in AH patients and liver injury, we used the mouse model of chronic-plus-binge ethanol feeding and found that myeloid-specific deletion of the Ncf1 gene abolished ethanol-induced hepatic inflammation and steatosis. RNA-Seq analysis and the data from experimental models revealed that neutrophilic NCF1-dependent ROS promoted alcoholic hepatitis (AH) by inhibiting AMP-activated protein kinase (a key regulator of lipid metabolism) and microRNA-223 (a key antiinflammatory and antifibrotic microRNA). In conclusion, two distinct histopathological phenotypes based on liver immune phenotyping are observed in SAH patients, suggesting a separate mechanism driving liver injury and/or failure in these patients.

Transcriptomic Analysis Reveals the Messenger RNAs Responsible for the Progression of Alcoholic Cirrhosis

Alcohol-associated liver disease is the leading cause of chronic liver disease. We hypothesized that the expression of specific coding genes is critical for the progression of alcoholic cirrhosis (AC) from compensated to decompensated states. For the discovery phase, we performed RNA sequencing analysis of 16 peripheral blood RNA samples, 4 healthy controls (HCs) and 12 patients with AC. The DEGs from the discovery cohort were validated by quantitative polymerase chain reaction in a separate cohort of 17 HCs and 48 patients with AC (17 Child-Pugh A, 16 Child-Pugh B, and 15 Child-Pugh C). We observed that the numbers of differentially expressed messenger RNAs (mRNAs) were more pronounced with worsening disease severity. Pathway analysis for differentially expressed genes for patients with Child-Pugh A demonstrated genes involved innate immune responses; those in Child-Pugh B belonged to genes related to oxidation and alternative splicing; those in Child-Pugh C related to methylation, acetylation, and alternative splicing. We found significant differences in the expression of heme oxygenase 1 (HMOX1) and ribonucleoprotein, PTB binding 1 (RAVER1) in peripheral blood of those who died during the follow-up when compared to those who survived. Conclusion: Unique mRNAs that may implicate disease progression in patients with AC were identified by using a transcriptomic approach. Future studies to confirm our results are needed, and comprehensive mechanistic studies on the implications of these genes in AC pathogenesis and progression should be further explored.

Effect of rifaximin on infections, acute-on-chronic liver failure and mortality in alcoholic hepatitis: A pilot study (RIFA-AH)

BACKGROUND & AIMS

Alcoholic hepatitis (AH) is associated with a high incidence of infection and mortality. Rifaximin reduces bacterial overgrowth and translocation. We aimed to study whether the administration of rifaximin as an adjuvant treatment to corticosteroids decreases the number of bacterial infections at 90 days in patients with severe AH compared to a control cohort.

METHODS

This was a multicentre, open, comparative pilot study of the addition of rifaximin (1200 mg/day/90 days) to the standard treatment for severe AH. The results were compared with a carefully matched historical cohort of patients treated with standard therapy and matching by age and model of end-stage liver disease (MELD). We evaluated bacterial infections, liver-related complications, mortality and liver function tests after 90 days.

RESULTS

Twenty-one and 42 patients were included in the rifaximin and control groups respectively. No significant baseline differences were found between groups. The mean number of infections per patient was 0.29 and 0.62 in the rifaximin and control groups, respectively (p = .049), with a lower incidence of acute-on-chronic liver failure (ACLF) linked to infections within the treatment group. Liver-related complications were lower within the rifaximin group (0.43 vs. 1.26 complications/patient respectively) (p = .01). Mortality was lower in the treated versus the control groups (14.2% vs. 30.9, p = .15) without significant differences. No serious adverse events were associated with rifaximin treatment.

CONCLUSIONS

Rifaximin is safe in severe AH with a significant reduction in clinical complications. A lower number of infections and a trend towards a lower ACLF and mortality favours its use in these patients.

Management of Alcohol-Related Liver Disease and Its Complications

Alcohol-related liver disease (ALD) is a major healthcare/economic burden and one of the leading causes of liver transplantation. New epidemiological studies that detail the course of the disease are needed since, despite its high prevalence, it is still a stigmatised condition with underlying pathology. Alcoholic hepatitis, as the highest expression of ALD, has high morbidity. Current treatments have suboptimal results with the exception of liver transplantation. Epidemiological studies must also be developed to improve prevention and implement early diagnosis policies. It is essential to develop multidisciplinary health models that allow the liver transplantation candidate to be approached in a holistic way, both for indication and follow up. The implementation of alcohol consumption biomarkers (ethyl glucuronide, phosphatidylethanol) can assist in diagnosing and supporting recovery. There are several initiatives with new therapies that must be validated to establish their effectiveness and indication.

Proteomic analysis of alcohol-associated hepatitis reveals glycoprotein NMB (GPNMB) as a novel hepatic and serum biomarker

Alcohol consumption remains a leading cause of liver disease worldwide, resulting in a complex array of hepatic pathologies, including steatosis, steatohepatitis, and cirrhosis. Individuals who progress to a rarer form of alcohol-associated liver disease (ALD), alcohol-associated hepatitis (AH), require immediate life-saving intervention in the form of liver transplantation. Rapid onset of AH is poorly understood and the metabolic mechanisms contributing to the progression to liver failure remain undetermined. While multiple mechanisms have been identified that contribute to ALD, no cures exist and mortality from AH remains high. To identify novel pathways associated with AH, our group utilized proteomics to investigate AH-specific biomarkers in liver explant tissues. The goal of the present study was to determine changes in the proteome as well as epigenetic changes occurring in AH. Protein abundance and acetylomic analyses were performed utilizing nHPLC-MS/MS, revealing significant changes to proteins associated with metabolic and inflammatory fibrosis pathways. Here, we describe a novel hepatic and serum biomarker of AH, glycoprotein NMB (GPNMB). The anti-inflammatory protein GPNMB was significantly increased in AH explant liver and serum compared to healthy donors by 50-fold and 6.5-fold, respectively. Further, bioinformatics analyses identified an AH-dependent decrease in protein abundance across fatty acid degradation, biosynthesis of amino acids, and carbon metabolism. The greatest increases in protein abundance were observed in pathways for focal adhesion, lysosome, phagosome, and actin cytoskeleton. In contrast with the hyperacetylation observed in murine models of ALD, protein acetylation was decreased in AH compared to normal liver across fatty acid degradation, biosynthesis of amino acids, and carbon metabolism. Interestingly, immunoblot analysis found epigenetic marks were significantly increased in AH explants, including Histone H3K9 and H2BK5 acetylation. The increased acetylation of histones likely plays a role in the altered proteomic profile observed, including increases in GPNMB. Indeed, our results reveal that the AH proteome is dramatically impacted through unanticipated and unknown mechanisms. Understanding the origin and consequences of these changes will yield new mechanistic insight for ALD as well as identify novel hepatic and serum biomarkers, such as GPNMB.

Plasma angiopoietin 2 as a novel prognostic biomarker in alcohol-related cirrhosis and hepatitis

Background and aim

Severe alcoholic hepatitis (SAH), the most florid form of alcohol-related liver disease (ALD), has a mortality rate of 16% at 28 days. The angiopoietin-Tie 2 system regulates angiogenesis and inflammation, both of which are implicated in the pathogenesis of ALD. This study examined plasma and hepatic gene expression of angiopoietin 1 (ANG1) and angiopoietin 2 (ANG2) in patients with SAH and ALD and investigated their roles as prognostic biomarkers.

Methods

A case-control study was performed measuring plasma levels of ANG1 and ANG2 by enzyme-linked immunosorbent assay (ELISA) from 30 patients with SAH (Maddrey's discriminant function ≥32), 32 patients with ALD cirrhosis and 15 healthy controls (HC). RNA sequencing for ANG1, ANG2, TIE1 (codes for Tie1 receptor) and TEK (codes for Tie2 receptor) gene expression from a separate cohort study of 79 patients was also performed.

Results

Plasma levels of ANG1 were lower (P = 0.010) and ANG2 were higher (P < 0.0001) in patients with ALD/SAH compared to HC. The ANG2: ANG1 ratio was higher in those with ALD/SAH compared to HC (P < 0.0001). ANG2 levels were the highest in patients who developed sepsis (P = 0.030) and those dying within 90 days (P = 0.020). ANG2 levels correlated positively with model for end-stage liver disease (MELD) score (r = 0.30, P = 0.020), Child-Pugh score (r = 0.38, P = 0.003), international normalized ratio (r = 0.41, P = 0.001) and white blood cell count (r = 0.28, P = 0.040) and inversely correlated with albumin (r = -0.26, P = 0.040).ANG1 gene expression from liver biopsies was higher in SAH than that in HC (P < 0.0001), and greater in severe disease (P < 0.0001). ANG2 gene expression trended towards being lower in SAH than that in HC (P = 0.070) though was upregulated in severe disease (P = 0.0003).

Conclusions

Plasma ANG2 is raised in SAH and ALD and could be useful as a prognostic biomarker in this patient population.

Crosstalk between Oxidative Stress and Inflammatory Liver Injury in the Pathogenesis of Alcoholic Liver Disease

Alcoholic liver disease (ALD) is characterized by the injury, inflammation, and scarring in the liver owing to excessive alcohol consumption. Currently, ALD is a leading cause for liver transplantation. Therefore, extensive studies (in vitro, in experimental ALD models and in humans) are needed to elucidate pathological features and pathogenic mechanisms underlying ALD. Notably, oxidative changes in the liver have been recognized as a signature trait of ALD. Progression of ALD is linked to the generation of highly reactive free radicals by reactions involving ethanol and its metabolites. Furthermore, hepatic oxidative stress promotes tissue injury and, in turn, stimulates inflammatory responses in the liver, forming a pathological loop that promotes the progression of ALD. Accordingly, accumulating further knowledge on the relationship between oxidative stress and inflammation may help establish a viable therapeutic approach for treating ALD.

Activation of G protein-coupled receptors by ketone bodies: Clinical implication of the ketogenic diet in metabolic disorders

Ketogenesis takes place in hepatocyte mitochondria where acetyl-CoA derived from fatty acid catabolism is converted to ketone bodies (KB), namely β-hydroxybutyrate (β-OHB), acetoacetate and acetone. KB represent important alternative energy sources under metabolic stress conditions. Ketogenic diets (KDs) are low-carbohydrate, fat-rich eating strategies which have been widely proposed as valid nutritional interventions in several metabolic disorders due to its substantial efficacy in weight loss achievement. Carbohydrate restriction during KD forces the use of FFA, which are subsequently transformed into KB in hepatocytes to provide energy, leading to a significant increase in ketone levels known as "nutritional ketosis". The recent discovery of KB as ligands of G protein-coupled receptors (GPCR) - cellular transducers implicated in a wide range of body functions - has aroused a great interest in understanding whether some of the clinical effects associated to KD consumption might be mediated by the ketone/GPCR axis. Specifically, anti-inflammatory effects associated to KD regimen are presumably due to GPR109A-mediated inhibition of NLRP3 inflammasome by β-OHB, whilst lipid profile amelioration by KDs could be ascribed to the actions of acetoacetate via GPR43 and of β-OHB via GPR109A on lipolysis. Thus, this review will focus on the effects of KD-induced nutritional ketosis potentially mediated by specific GPCRs in metabolic and endocrinological disorders. To discriminate the effects of ketone bodies per se, independently of weight loss, only studies comparing ketogenic vs isocaloric non-ketogenic diets will be considered as well as short-term tolerability and safety of KDs.

Transcriptomic Analysis Reveals the MicroRNAs Responsible for Liver Regeneration Associated With Mortality in Alcohol-Associated Hepatitis

BACKGROUND AND AIMS

We conducted a comprehensive serum transcriptomic analysis to explore the roles of microRNAs (miRNAs) in alcohol-associated hepatitis (AH) pathogenesis and their prognostic significance.

APPROACH AND RESULTS

Serum miRNA profiling was performed in 15 controls, 20 heavy drinkers without liver disease, and 65 patients with AH and compared to publicly available hepatic miRNA profiling in AH patients. Among the top 26 miRNAs, expression of miR-30b-5p, miR-20a-5p, miR-146a-5p, and miR-26b-5p were significantly reduced in both serum and liver of AH patients. Pathway analysis of the potential targets of these miRNAs uncovered the genes related to DNA synthesis and cell-cycle progression pathways, including ribonucleotide reductase regulatory subunit M2 (RRM2), cyclin D1 (CCND1), cyclin D2 (CCND2), MYC proto-oncogene (MYC), and phorbol-12-myristate-13-acetate-induced protein 1 (PMAIP1). We found a significant increase in the protein expression of RRM2, CCND1, and CCND2, but not MYC and PMAIP1, in AH patients who underwent liver transplantation; miR-26b-5p and miR-30b-5p inhibited the 3'-UTR (untranslated region) luciferase activity of RRM2 and CCND2, and miR-20a-5p reduced the 3'-UTR luciferase activity of CCND1 and CCND2. During a median follow-up of 346 days, 21% of AH patients died; these patients had higher body mass index (BMI), Model for End-Stage Liver Disease (MELD), and serum miR-30b-5p, miR-20a-5p, miR-146a-5p, and miR-26b-5p than those who survived. Cox regression analysis showed that BMI, MELD score, miR-20a-5p, miR-146a-5p, and miR-26b-5p predicted mortality.

CONCLUSIONS

Patients with AH attempt to deal with hepatocyte injury by down-regulating specific miRNAs and up-regulating genes responsible for DNA synthesis and cell-cycle progression. Higher expression of these miRNAs, suggestive of a diminished capacity in liver regeneration, predicts short-term mortality in AH patients.

Loss of hepatocyte identity following aberrant YAP activation: A key mechanism in alcoholic hepatitis

BACKGROUND & AIMS

Alcoholic hepatitis (AH) is a life-threatening disease with limited therapeutic options, as the molecular mechanisms leading to death are not well understood. This study evaluates the Hippo/Yes-associated protein (YAP) pathway which has been shown to play a role in liver regeneration.

METHOD

The Hippo/YAP pathway was dissected in explants of patients transplanted for AH or alcohol-related cirrhosis and in control livers, using RNA-seq, real-time PCR, western blot, immunohistochemistry and transcriptome analysis after laser microdissection. We transfected primary human hepatocytes with constitutively active YAP (YAPS127A) and treated HepaRG cells and primary hepatocytes isolated from AH livers with a YAP inhibitor. We also used mouse models of ethanol exposure (Lieber de Carli) and liver regeneration (carbon tetrachloride) after hepatocyte transduction of YAPS127A.

RESULTS

In AH samples, RNA-seq analysis and immunohistochemistry of total liver and microdissected hepatocytes revealed marked downregulation of the Hippo pathway, demonstrated by lower levels of active MST1 kinase and abnormal activation of YAP in hepatocytes. Overactivation of YAP in hepatocytes in vitro and in vivo led to biliary differentiation and loss of key biological functions such as regeneration capacity. Conversely, a YAP inhibitor restored the mature hepatocyte phenotype in abnormal hepatocytes taken from patients with AH. In ethanol-fed mice, YAP activation using YAPS127A resulted in a loss of hepatocyte differentiation. Hepatocyte proliferation was hampered by YAPS127A after carbon tetrachloride intoxication.

CONCLUSION

Aberrant activation of YAP plays an important role in hepatocyte transdifferentiation in AH, through a loss of hepatocyte identity and impaired regeneration. Thus, targeting YAP is a promising strategy for the treatment of patients with AH.

LAY SUMMARY

Alcoholic hepatitis is characterized by inflammation and a life-threatening alteration of liver regeneration, although the mechanisms behind this have not been identified. Herein, we show that liver samples from patients with alcoholic hepatitis are characterized by profound deregulation of the Hippo/YAP pathway with uncontrolled activation of YAP in hepatocytes. We used human cell and mouse models to show that inhibition of YAP reverts this hepatocyte defect and could be a novel therapeutic strategy for alcoholic hepatitis.

The role of SHP/REV-ERBα/CYP4A axis in the pathogenesis of alcohol-associated liver disease

Alcohol-associated liver disease (ALD) represents a spectrum of histopathological changes, including alcoholic steatosis, steatohepatitis, and cirrhosis. One of the early responses to excessive alcohol consumption is lipid accumulation in the hepatocytes. Lipid ω-hydroxylation of medium- and long-chain fatty acid metabolized by the cytochrome P450 4A (CYP4A) family is an alternative pathway for fatty acid metabolism. The molecular mechanisms of CYP4A in ALD pathogenesis have not been elucidated. In this study, WT and Shp^−/− mice were fed with a modified ethanol-binge, National Institute on Alcohol Abuse and Alcoholism model (10 days of ethanol feeding plus single binge). Liver tissues were collected every 6 hours for 24 hours and analyzed using RNA-Seq. The effects of REV-ERBα agonist (SR9009, 100 mg/kg/d) or CYP4A antagonist (HET0016, 5 mg/kg/d) in ethanol-fed mice were also evaluated. We found that hepatic Cyp4a10 and Cyp4a14 expression were significantly upregulated in WT mice, but not in Shp^−/− mice, fed with ethanol. ChIP quantitative PCR and promoter assay revealed that REV-ERBα is the transcriptional repressor of Cyp4a10 and Cyp4a14. Rev-Erbα−/− hepatocytes had a marked induction of both Cyp4a genes and lipid accumulation. REV-ERBα agonist SR9009 or CYP4A antagonist HET0016 attenuated Cyp4a induction by ethanol and prevented alcohol-induced steatosis. Here, we have identified a role for the SHP/REV-ERBα/CYP4A axis in the pathogenesis of ALD. Our data also suggest REV-ERBα or CYP4A as the potential therapeutic targets for ALD.

Epidemiology of Alcohol-Associated Liver Disease

Alcohol-associated liver disease (ALD) is a consequence of excessive alcohol use. It comprises a spectrum of histopathologic changes ranging from simple steatosis, steatohepatitis, and cirrhosis to hepatocellular carcinoma. The public health impact of ALD is growing because of an increase in the prevalence and incidence of ALD in parallel with liver transplant and mortalities. There are multiple factors involved in the pathogenesis and progression of ALD. Reducing alcohol consumption is the cornerstone of ALD management. The efforts to reduce excessive alcohol use at the individual and population levels are urgently needed to prevent adverse outcomes from ALD.

Myeloid Endoplasmic Reticulum Resident Chaperone GP96 Facilitates Inflammation and Steatosis in Alcohol-Associated Liver Disease

Cellular stress-mediated chaperones are linked to liver macrophage activation and inflammation in alcohol-associated liver disease (ALD). In this study, we investigate the role of endoplasmic reticulum (ER) resident stress chaperone GP96/HSP90B1/GRP94, paralog of the HSP90 family, in ALD pathogenesis. We hypothesize that ER resident chaperone, heat shock protein GP96, plays a crucial role in alcohol-associated liver inflammation and contributes to liver injury. We show high expression of GP96/HSP90B1 and GRP78/HSPA5 in human alcohol-associated hepatitis livers as well as in mouse ALD livers with induction of GP96 prominent in alcohol-exposed macrophages. Myeloid-specific GP96 deficient (M-GP96KO) mice failed to induce alcohol-associated liver injury. Alcohol-fed M-GP96KO mice exhibit significant reduction in steatosis, serum endotoxin, and pro-inflammatory cytokines compared with wild-type mice. Anti-inflammatory cytokines interleukin-10 and transforming growth factor β, as well as activating transcription factor 3 and triggering receptor expressed on myeloid cells 2, markers of restorative macrophages, were higher in alcohol-fed M-GP96KO livers. M-GP96KO mice exhibit protection in a model of endotoxin-mediated liver injury in vivo, which is in agreement with reduced inflammatory responses during ex vivo lipopolysaccharide/endotoxin- stimulated bone marrow-derived macrophages from M-GP96KO mice. Furthermore, we show that liver macrophages from alcohol-fed M-GP96KO mice show compensatory induction of GRP78 messenger RNA, likely due to increased splicing of X-box binding protein-1. Finally, we show that inhibition of GP96 using a specific pharmacological agent, PU-WS13 or small interfering RNA, alleviates inflammatory responses in primary macrophages. Conclusion: Myeloid ER resident GP96 promotes alcohol-induced liver damage through activation of liver macrophage inflammatory responses, alteration in lipid homeostasis, and ER stress. These findings highlight a critical role for liver macrophage ER resident chaperone GP96/HSP90B1 in ALD, and its targeted inhibition represents a promising therapeutic approach in ALD.

Endothelial dysfunction markers predict short-term mortality in patients with severe alcoholic hepatitis

OBJECTIVES

Alcoholic hepatitis (AH) is a severe condition characterized by a marked inflammatory response and high short-term mortality. Endothelial dysfunction (ED) is an early event in vascular and inflammatory disorders. The aim of this study is to evaluate ED in AH patients.

METHODS

Prognostic value of ED biomarkers was evaluated in patients with severe AH (n = 67), compensated alcoholic cirrhosis (n = 15), heavy drinkers without liver disease (n = 15) and controls (n = 9), and in a validation cohort of 50 patients with AH. Gene expression of ED markers was analyzed in liver tissue.

RESULTS

Plasma levels of ED markers such as vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), E-selectin and von Willebrand factor (vWF) increased along alcohol-related liver disease (ALD) progression. Intergroup analysis showed a significant increase of these markers in AH patients. In addition, VCAM-1 showed a positive correlation with Maddrey, MELD and ABIC scores and inflammation parameters (i.e. C-reactive protein and LPS levels). Importantly, levels of VCAM-1 were higher in patients with increased mortality and were independently associated with short-term survival (90-day) when adjusted by ABIC score. These results were confirmed in an independent cohort of AH patients. In addition, severe AH patients showed altered hepatic expression of ED markers.

CONCLUSIONS

In this study we show that advanced ALD and particularly severe AH is associated with an increase of ED biomarkers, which correlate with patient outcomes. These results suggest that ED may be a pathogenic event in AH and highlight endothelial factors as potential biomarkers in AH.

Integrated Multiomics Reveals Glucose Use Reprogramming and Identifies a Novel Hexokinase in Alcoholic Hepatitis

BACKGROUND & AIMS

We recently showed that alcoholic hepatitis (AH) is characterized by dedifferentiation of hepatocytes and loss of mature functions. Glucose metabolism is tightly regulated in healthy hepatocytes. We hypothesize that AH may lead to metabolic reprogramming of the liver, including dysregulation of glucose metabolism.

METHODS

We performed integrated metabolomic and transcriptomic analyses of liver tissue from patients with AH or alcoholic cirrhosis or normal liver tissue from hepatic resection. Focused analyses of chromatin immunoprecipitation coupled to DNA sequencing was performed. Functional in vitro studies were performed in primary rat and human hepatocytes and HepG2 cells.

RESULTS

Patients with AH exhibited specific changes in the levels of intermediates of glycolysis/gluconeogenesis, the tricarboxylic acid cycle, and monosaccharide and disaccharide metabolism. Integrated analysis of the transcriptome and metabolome showed the used of alternate energetic pathways, metabolite sinks and bottlenecks, and dysregulated glucose storage in patients with AH. Among genes involved in glucose metabolism, hexokinase domain containing 1 (HKDC1) was identified as the most up-regulated kinase in patients with AH. Histone active promoter and enhancer markers were increased in the HKDC1 genomic region. High HKDC1 levels were associated with the development of acute kidney injury and decreased survival. Increased HKDC1 activity contributed to the accumulation of glucose-6-P and glycogen in primary rat hepatocytes.

CONCLUSIONS

Altered metabolite levels and messenger RNA expression of metabolic enzymes suggest the existence of extensive reprogramming of glucose metabolism in AH. Increased HKDC1 expression may contribute to dysregulated glucose metabolism and represents a novel biomarker and therapeutic target for AH.

Hepatic Histopathology Among Excessive Drinkers Without Advanced Liver Disease

AIMS

Alcohol-associated liver disease represents a spectrum of histopathological changes from steatosis to advanced fibrosis and cirrhosis. The major goals of this retrospective study were to characterize the histologic features in patients with excessive alcohol use who presented with an abnormal hepatic panel and/or abnormal radiographic imaging and did not meet the clinical diagnosis of alcoholic hepatitis or cirrhosis.

METHODS

We performed a retrospective study to describe hepatic histology of 62 and 83 excessive drinkers with normal and abnormal serum aspartate transaminase, respectively. The types of inflammatory cells in the liver were characterized by immunohistochemistry for CD4, CD8, CD20, CD68 and myeloperoxidase.

RESULTS

Among 62 patients with aspartate aminotransferase (AST) ≤ 50 U/L, 37% had histological evidence of steatosis. Of these, we found evidence of hepatocyte ballooning (21%), lobular inflammation (50%), portal inflammation (52%) and fibrosis (14%). For those with AST > 50 U/L, the presence of hepatic steatosis, lobular inflammation and portal inflammation was observed in 29, 60 and 69% of patients, respectively. Fibrosis was found in 33%, four with bridging fibrosis, and one with cirrhosis. We observed the aggregation of CD68+ macrophages, rather than normally distributed with minimal neutrophilic infiltration. Lobular and portal lymphocytic infiltrations are primarily CD8+ T cells.

CONCLUSION

Abnormal hepatic histopathology occurs in excessive drinkers with normal transaminase activity. Future studies to determine the diagnostic modalities to detect such abnormalities and to better understand its clinical implications and long-term outcome are needed.

Alcohol-associated liver disease: A review on its pathophysiology, diagnosis and drug therapy

One of the global burdens of health care is an alcohol-associated liver disease (ALD) and liver-related death which is caused due to acute or chronic consumption of alcohol. Chronic consumption of alcohol damage the normal defense mechanism of the liver and likely to disturb the gut barrier system, mucosal immune cells, which leads to decreased nutrient absorption. Therapy of ALD depends upon the spectrum of liver injury that causes fatty liver, hepatitis, and cirrhosis. The foundation of therapy starts with abstinence from alcohol. Corticosteroids are used for the treatment of ALD but due to poor acceptance, continuing mortality, and identification of tumor necrosis factor-alpha as an integral component in pathogenesis, recent studies focus on pentoxifylline and, antitumor necrosis factor antibody to neutralize cytokines in the therapy of severe alcoholic hepatitis. Antioxidants also play a significant role in the treatment but till today there is no universally accepted therapy available for any stage of ALD. The treatment aspects need to restore the gut functions and require nutrient-based treatments to regulate the functions of the gut system and prevent liver injury. The vital action of saturated fatty acids greatly controls the gut barrier. Overall, this review mainly focuses on the mechanism of alcohol-induced metabolic dysfunction, contribution to liver pathogenesis, the effect of pregnancy, and targeted therapy of ALD.

Advanced glycation end products (AGEs) and other adducts in aging-related diseases and alcohol-mediated tissue injury

Advanced glycation end products (AGEs) are potentially harmful and heterogeneous molecules derived from nonenzymatic glycation. The pathological implications of AGEs are ascribed to their ability to promote oxidative stress, inflammation, and apoptosis. Recent studies in basic and translational research have revealed the contributing roles of AGEs in the development and progression of various aging-related pathological conditions, such as diabetes, cardiovascular complications, gut microbiome-associated illnesses, liver or neurodegenerative diseases, and cancer. Excessive chronic and/or acute binge consumption of alcohol (ethanol), a widely consumed addictive substance, is known to cause more than 200 diseases, including alcohol use disorder (addiction), alcoholic liver disease, and brain damage. However, despite the considerable amount of research in this area, the underlying molecular mechanisms by which alcohol abuse causes cellular toxicity and organ damage remain to be further characterized. In this review, we first briefly describe the properties of AGEs: their formation, accumulation, and receptor interactions. We then focus on the causative functions of AGEs that impact various aging-related diseases. We also highlight the biological connection of AGE-alcohol-adduct formations to alcohol-mediated tissue injury. Finally, we describe the potential translational research opportunities for treatment of various AGE- and/or alcohol-related adduct-associated disorders according to the mechanistic insights presented.

Pyroptosis in liver disease

Pyroptosis is an inflammatory cell death process that is dependent on caspase. Pyroptosis is a specific form of programmed cell death with the morphological characteristics of formation of pores on the cell membrane, cell swelling, and rupture of the plasma membrane. Recent studies have demonstrated that pyroptosis plays an important role in the occurrence and development of liver diseases. Here, we focus on the mechanisms of pyroptosis, as well as on the relationship between pyroptosis and liver diseases.

Hepatic lipocalin 2 promotes liver fibrosis and portal hypertension

Advanced fibrosis and portal hypertension influence short-term mortality. Lipocalin 2 (LCN2) regulates infection response and increases in liver injury. We explored the role of intrahepatic LCN2 in human alcoholic hepatitis (AH) with advanced fibrosis and portal hypertension and in experimental mouse fibrosis. We found hepatic LCN2 expression and serum LCN2 level markedly increased and correlated with disease severity and portal hypertension in patients with AH. In control human livers, LCN2 expressed exclusively in mononuclear cells, while its expression was markedly induced in AH livers, not only in mononuclear cells but also notably in hepatocytes. Lcn2-/- mice were protected from liver fibrosis caused by either ethanol or CCl4 exposure. Microarray analysis revealed downregulation of matrisome, cell cycle and immune related gene sets in Lcn2-/- mice exposed to CCl4, along with decrease in Timp1 and Edn1 expression. Hepatic expression of COL1A1, TIMP1 and key EDN1 system components were elevated in AH patients and correlated with hepatic LCN2 expression. In vitro, recombinant LCN2 induced COL1A1 expression. Overexpression of LCN2 increased HIF1A that in turn mediated EDN1 upregulation. LCN2 contributes to liver fibrosis and portal hypertension in AH and could represent a new therapeutic target.

Harnessing the Proteostasis Network in Alcohol-associated Liver Disease

Purpose of review

Alcohol associated liver disease (ALD) accounts for significant mortality and morbidity in the United States. Prolonged alcohol exposure leads to increased reactive oxygen species and oxidative stress resulting in protein misfolding and/or aggregation. Cellular protein homeostasis network is an adaptive cellular response comprised of machineries that regulate biogenesis or degradation of proteins with chaperones as central coordinators to maintain proteome integrity during stress. Two extensively studied organelle-specific transcriptional proteostasis pathways are the heat shock response (HSR) in the cytosol and unfolded protein response (UPR) in endoplasmic reticulum (ER). Here we review the pathophysiological role of HSR and UPR and their potential as therapeutic targets in ALD.

Recent findings

The HSR and UPR are emerging as important pathways in ALD pathogenesis. We reported that acute and chronic alcohol activate the HSR to discretely induce downstream target chaperones, HSPA1A/HSP70 and HSP90, respectively. HSP90 serves as a pro-inflammatory mediator in ALD by stabilizing client kinases and adapters. On the other hand, HSF1 and HSPA1A prevents liver injury due to their anti-inflammatory properties. In vivo pharmacological targeting of HSP90 reduced pro-inflammatory cytokines and NLRP3 inflammasome mediated IL-1β and IL-18. The presence of HSP90 in circulating extracellular vesicles in ALD mouse models suggests its role in pathogenesis. Activation of UPR due to prolonged ER stress is associated with apoptosis, inflammation, and lipogenesis contributing to liver injury.

Summary

This review highlights the contribution of HSR and UPR, as well as druggable chaperones in pathogenesis of ALD. Binge/moderate or chronic alcohol exposure perturbs proteostasis mediators which fail to maintain proteome integrity and disease ensues. Understanding mechanisms that regulate proteostasis pathways, HSR and UPR, could identify novel disease modulators and guide development of therapeutic targets in ALD.

Interleukin-22 in alcoholic hepatitis and beyond

Alcoholic hepatitis (AH) is a clinical syndrome characterized by jaundice and progressive inflammatory liver injury in patients with a history of prolonged periods of excess alcohol consumption and recent heavy alcohol abuse. Severe AH is a life-threatening form of alcohol-associated liver disease with a high short-term mortality rate around 30-50% at one month from the initial presentation. A large number of pro-inflammatory mediators, metabolic pathways, transcriptional factors and epigenetic factors have been suggested to be associated with the development and progression of AH. Several factors may contribute to liver failure and mortality in patients with severe AH including hepatocyte death, inflammation, and impaired liver regeneration. Although the pathogeneses of AH have been extensively investigated and many therapeutic targets have been identified over the last five decades, no new drugs for AH have been successfully developed. In this review, we discuss interleukin-22 (IL-22) biology and its roles of anti-apoptosis, anti-fibrosis, anti-oxidation, anti-bacterial infection and regenerative stimulation in protecting against liver injury in many preclinical models including several recently developed models such as chronic-plus-binge ethanol feeding, acute-on-chronic liver failure, C-X-C motif chemokine ligand 1 plus high-fat diet-induced nonalcoholic steatohepatitis. Finally, clinical trials of IL-22 for the treatment of AH are also discussed, which showed some promising benefits for AH patients.

DNMT3b-mediated methylation of ZSWIM3 enhances inflammation in alcohol-induced liver injury via regulating TRAF2-mediated NF-κB pathway

The regulation of macrophages during inflammatory responses is a crucial process in alcoholic liver disease (ALD) and aberrant macrophage DNA methylation is associated with inflammation. Our preliminary screening results of macrophage methylation in the present study demonstrated the zinc finger SWI2/SNF2 and MuDR (SWIM)-domain containing 3 (ZSWIM3) were hypermethylated in the 5′ untranslated region (5′-UTR) region. ZSWIM3, a novel zinc finger-chelate domain of SWIM, is predicted to function in DNA-binding and protein-binding interactions. Its expression was found to be consistently decreased in macrophages isolated from livers of ethyl alcohol (EtOH)-fed mice and in EtOH+lipopolysaccharide (LPS)-induced RAW264.7 cells. Over-expression of ZSWIM3 was found to attenuate chronic+binge ethanol feeding-induced liver injury and inhibit inflammatory responses in vivo. Enforced expression of ZSWIM3 in vitro was also found to have anti-inflammatory effects. Aberrant expression of ZSWIM3 in alcohol-induced liver injury (ALI) was found to be associated with hypermethylation. Analysis of CpG prediction indicated the presence of two methylated sites in the ZSWIM3 promoter region and methylation inhibitor and DNA methyltransferases (DNMTs)-siRNA transfection were found to restore down-regulated ZSWIM3. Chromatin immunoprecipitation (ChIP) assay and molecular docking affirmed the role of DNMT 3b (DNMT3b) as a principal regulator of ZSWIM3 expression. Mechanistically, ZSWIM3 might affect inflammation by binding with tumor necrosis factor receptor-associated factor 2 (TRAF2), which further mediates the activation of the nuclear transcription factor κB (NF-κB) pathway. The present study, therefore, provides detailed insights into the possible structure and function of ZSWIM3 and thus, contributes new substantial research in the elucidation of the pathogenesis of ALI.

DNMT3b-mediated methylation of ZSWIM3 enhances inflammation in alcohol-induced liver injury via regulating TRAF2-mediated NF-κB pathway

The regulation of macrophages during inflammatory responses is a crucial process in alcoholic liver disease (ALD) and aberrant macrophage DNA methylation is associated with inflammation. Our preliminary screening results of macrophage methylation in the present study demonstrated the zinc finger SWI2/SNF2 and MuDR (SWIM)-domain containing 3 (ZSWIM3) were hypermethylated in the 5' untranslated region (5'-UTR) region. ZSWIM3, a novel zinc finger-chelate domain of SWIM, is predicted to function in DNA-binding and protein-binding interactions. Its expression was found to be consistently decreased in macrophages isolated from livers of ethyl alcohol (EtOH)-fed mice and in EtOH+lipopolysaccharide (LPS)-induced RAW264.7 cells. Over-expression of ZSWIM3 was found to attenuate chronic+binge ethanol feeding-induced liver injury and inhibit inflammatory responses in vivo. Enforced expression of ZSWIM3 in vitro was also found to have anti-inflammatory effects. Aberrant expression of ZSWIM3 in alcohol-induced liver injury (ALI) was found to be associated with hypermethylation. Analysis of CpG prediction indicated the presence of two methylated sites in the ZSWIM3 promoter region and methylation inhibitor and DNA methyltransferases (DNMTs)-siRNA transfection were found to restore down-regulated ZSWIM3. Chromatin immunoprecipitation (ChIP) assay and molecular docking affirmed the role of DNMT 3b (DNMT3b) as a principal regulator of ZSWIM3 expression. Mechanistically, ZSWIM3 might affect inflammation by binding with tumor necrosis factor receptor-associated factor 2 (TRAF2), which further mediates the activation of the nuclear transcription factor κB (NF-κB) pathway. The present study, therefore, provides detailed insights into the possible structure and function of ZSWIM3 and thus, contributes new substantial research in the elucidation of the pathogenesis of ALI.

DNMT3b-mediated methylation of ZSWIM3 enhances inflammation in alcohol-induced liver injury via regulating TRAF2-mediated NF-κB pathway

The regulation of macrophages during inflammatory responses is a crucial process in alcoholic liver disease (ALD) and aberrant macrophage DNA methylation is associated with inflammation. Our preliminary screening results of macrophage methylation in the present study demonstrated the zinc finger SWI2/SNF2 and MuDR (SWIM)-domain containing 3 (ZSWIM3) were hypermethylated in the 5′ untranslated region (5′-UTR) region. ZSWIM3, a novel zinc finger-chelate domain of SWIM, is predicted to function in DNA-binding and protein-binding interactions. Its expression was found to be consistently decreased in macrophages isolated from livers of ethyl alcohol (EtOH)-fed mice and in EtOH+lipopolysaccharide (LPS)-induced RAW264.7 cells. Over-expression of ZSWIM3 was found to attenuate chronic+binge ethanol feeding-induced liver injury and inhibit inflammatory responses in vivo. Enforced expression of ZSWIM3 in vitro was also found to have anti-inflammatory effects. Aberrant expression of ZSWIM3 in alcohol-induced liver injury (ALI) was found to be associated with hypermethylation. Analysis of CpG prediction indicated the presence of two methylated sites in the ZSWIM3 promoter region and methylation inhibitor and DNA methyltransferases (DNMTs)-siRNA transfection were found to restore down-regulated ZSWIM3. Chromatin immunoprecipitation (ChIP) assay and molecular docking affirmed the role of DNMT 3b (DNMT3b) as a principal regulator of ZSWIM3 expression. Mechanistically, ZSWIM3 might affect inflammation by binding with tumor necrosis factor receptor-associated factor 2 (TRAF2), which further mediates the activation of the nuclear transcription factor κB (NF-κB) pathway. The present study, therefore, provides detailed insights into the possible structure and function of ZSWIM3 and thus, contributes new substantial research in the elucidation of the pathogenesis of ALI.