Alcoholic steatohepatitis (ASH) and alcoholic hepatitis (AH): cascade of events, clinical aspects, and pharmacotherapy options

MASH as an emerging cause of hepatocellular carcinoma: current knowledge and future perspectives

Hepatocellular carcinoma is one of the deadliest and fastest-growing cancers. Among HCC etiologies, metabolic dysfunction-associated fatty liver disease (MAFLD) has served as a major HCC driver due to its great potential for increasing cirrhosis. The obesogenic environment fosters a positive energy balance and results in a continuous rise of obesity and metabolic syndrome. However, it is difficult to understand how metabolic complications lead to the poor prognosis of liver diseases and which molecular mechanisms are underpinning MAFLD-driven HCC development. Thus, suitable preclinical models that recapitulate human etiologies are essentially required. Numerous preclinical models have been created but not many mimicked anthropometric measures and the course of disease progression shown in the patients. Here we review the literature on adipose tissues, liver-related HCC etiologies and recently discovered genetic mutation signatures found in MAFLD-driven HCC patients. We also critically review current rodent models suggested for MAFLD-driven HCC study.

Cyclic nucleotide phosphodiesterases as drug targets

Cyclic nucleotides are synthesized by adenylyl and/or guanylyl cyclase, and downstream of this synthesis, the cyclic nucleotide phosphodiesterase families (PDEs) specifically hydrolyze cyclic nucleotides. PDEs control cyclic adenosine-3',5'monophosphate (cAMP) and cyclic guanosine-3',5'-monophosphate (cGMP) intracellular levels by mediating their quick return to the basal steady state levels. This often takes place in subcellular nanodomains. Thus, PDEs govern short-term protein phosphorylation, long-term protein expression, and even epigenetic mechanisms by modulating cyclic nucleotide levels. Consequently, their involvement in both health and disease is extensively investigated. PDE inhibition has emerged as a promising clinical intervention method, with ongoing developments aiming to enhance its efficacy and applicability. In this comprehensive review, we extensively look into the intricate landscape of PDEs biochemistry, exploring their diverse roles in various tissues. Furthermore, we outline the underlying mechanisms of PDEs in different pathophysiological conditions. Additionally, we review the application of PDE inhibition in related diseases, shedding light on current advancements and future prospects for clinical intervention. SIGNIFICANCE STATEMENT: Regulating PDEs is a critical checkpoint for numerous (patho)physiological conditions. However, despite the development of several PDE inhibitors aimed at controlling overactivated PDEs, their applicability in clinical settings poses challenges. In this context, our focus is on pharmacodynamics and the structure activity of PDEs, aiming to illustrate how selectivity and efficacy can be optimized. Additionally, this review points to current preclinical and clinical evidence that depicts various optimization efforts and indications.

Isolicoflavonol ameliorates acute liver injury via inhibiting NLRP3 inflammasome activation through boosting Nrf2 signaling in vitro and in vivo

BACKGROUND

NOD like receptor pyrin domain containing 3 (NLRP3) inflammasome is involved in innate immunity, and related to liver injury. However, no inflammasome inhibitors are clinically available until now. Our previous research suggests that isolicoflavonol (ILF), isolated from Macaranga indica, is a potent NLRP3 inflammasome inhibitor, but its mechanism is unclear.

METHODS

Fluorescent imaging and Western blot assay were used to ascertain the effects of ILF on pyroptosis and NLRP3 inflammasome activation in macrophages. Next, Nrf2 signal pathway, its downstream gene transcription and expression were further investigated. ML385, a Nrf2 inhibitor, was used to verify whether ILF targets Nrf2 signaling. A carbon tetrachloride induced liver injury model was introduced to evaluate the liver protection activity of ILF in mice.

RESULTS

This work revealed that ILF inhibited macrophage LDH release and IL-1β secretion in a dose-dependent manner. ILF had no significant cytotoxic effect on macrophage, it reduced pyroptosis and Gasdermin D N-terminal fragment formation. Moreover, ILF inhibited IL-1β maturation and Caspase-1 cleavage, but did not affect NLRP3, pro-Caspase-1, pro-IL-1β and ASC expression. ILF decreased ASC speck rate and reduced ASC oligomer formation. ILF decreased aggregated JC-1 formation restoring mitochondria membrane potential. In addition, ILF increased Nrf2 expression, extended Nrf2 lifespan and upregulated Nrf2 signaling pathway in macrophages whether the NLRP3 inflammasome was activated or not. Besides, ILF increased Nrf2 nuclear translocation, maintained a high proportion of Nrf2 in the nucleus, and upregulated ARE-related gene transcription and expression. Furthermore, Nrf2 signal inhibition attenuated compound ILF-mediated inhibition of pyroptosis, inflammasome activation and upregulation of Nrf2 signaling. ILF in a liver injury mouse model inhibited NLRP3 inflammasome activation and enhanced Nrf2 signaling.

CONCLUSION

Our study verified that ILF ameliorates liver injury via inhibiting NLRP3 inflammasome activation through boosting Nrf2 signaling, and highlighted that ILF is a potent anti-inflammatory drug for inflammasome-related liver diseases.

Understanding the Role of Alcohol in Metabolic Dysfunction and Male Infertility

Purpose: Over the past 40-50 years, demographic shifts and the obesity epidemic have coincided with significant changes in lifestyle habits, including a rise in excessive alcohol consumption. This increase in alcohol intake is a major public health concern due to its far-reaching effects on human health, particularly on metabolic processes and male reproductive function. This narrative review focuses on the role of alcohol consumption in altering metabolism and impairing testicular function, emphasizing the potential damage associated with both acute and chronic alcohol intake. Conclusion: Chronic alcohol consumption has been shown to disrupt liver function, impair lipid metabolism, and dysregulate blood glucose levels, contributing to the development of obesity, metabolic syndrome, and related systemic diseases. In terms of male reproductive health, alcohol can significantly affect testicular function by lowering testosterone levels, reducing sperm quality, and impairing overall fertility. The extent of these effects varies, depending on the frequency, duration, and intensity of alcohol use, with chronic and abusive consumption posing greater risks. The complexity of alcohol's impact is further compounded by individual variability and the interaction with other lifestyle factors such as diet, stress, and physical activity. Despite growing concern, research on alcohol's effects remains inconclusive, with significant discrepancies across studies regarding the definition and reporting of alcohol consumption. These inconsistencies highlight the need for more rigorous, methodologically sound research to better understand how alcohol consumption influences metabolic and reproductive health. Ultimately, a clearer understanding is essential for developing targeted public health interventions, particularly in light of rising alcohol use, demographic changes, and the ongoing obesity crisis.

Hepatoprotective Effect of Antrodia camphorata Mycelium Powder on Alcohol-Induced Liver Damage

BACKGROUND/OBJECTIVES

Antrodia camphorata, also known as "Niuchangchih" in Taiwan, is a unique medicinal mushroom native to Taiwan. It is used in traditional medicine to treat various health conditions. In this study, we investigated the efficacy of A. camphorata mycelia on alcohol-induced liver damage, both in vitro and in vivo, in a Good Laboratory Practice (GLP) facility.

METHODS

The experimental groups consisted of a normal control group (G1), a negative control group (G2), an A. camphorata mycelium powder 50 mg/kg/day administration group (G3), a 100 mg/kg/day administration group (G4), a 200 mg/kg/day administration group (G5), and a positive control silymarin 200 mg/kg/day administration group (G6), with 10 Sprague Dawley rats assigned to each treatment group.

RESULTS

We found that treatment with A. camphorata mycelium powder significantly reduced alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, cholesterol, adiponectin, triglyceride, and malondialdehyde concentrations. Histopathological analysis also revealed that the inflammation score significantly decreased in the A. camphorata-treated groups.

CONCLUSION

Based on these results, we conclude that repeated oral administration of A. camphorata mycelium powder is effective in improving alcoholic liver disease.

The role of gut microbiota, exosomes, and their interaction in the pathogenesis of ALD

BACKGROUND

The liver disorders caused by alcohol abuse are termed alcoholic-related liver disease (ALD), including alcoholic steatosis, alcoholic steatohepatitis, alcoholic hepatitis, and alcoholic cirrhosis, posing a significant threat to human health. Currently, ALD pathogenesis has not been completely clarified, which is likely to be related to the direct damage caused by alcohol and its metabolic products, oxidative stress, gut dysbiosis, and exosomes.

AIMS

The existing studies suggest that both the gut microbiota and exosomes contribute to the development of ALD. Moreover, there exists an interaction between the gut microbiota and exosomes. We discuss whether this interaction plays a role in the pathogenesis of ALD and whether it can be a potential therapeutic target for ALD treatment.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Chronic alcohol intake alters the diversity and composition of gut microbiota, which greatly contributes to ALD's progression. Some approaches targeting the gut microbiota, including probiotics, fecal microbiota transplantation, and phage therapy, have been confirmed to effectively ameliorate ALD in many animal experiments and/or several clinical trials. In ALD, the levels of exosomes and the expression profile of microRNA have also changed, which affects the pathogenesis of ALD. Moreover, there is an interplay between exosomes and the gut microbiota, which also putatively acts as a pathogenic factor of ALD.

Copper, Iron, Cadmium, and Arsenic, All Generated in the Universe: Elucidating Their Environmental Impact Risk on Human Health Including Clinical Liver Injury

Humans are continuously exposed to various heavy metals including copper, iron, cadmium, and arsenic, which were specifically selected for the current analysis because they are among the most frequently encountered environmental mankind and industrial pollutants potentially causing human health hazards and liver injury. So far, these issues were poorly assessed and remained a matter of debate, also due to inconsistent results. The aim of the actual report is to thoroughly analyze the positive as well as negative effects of these four heavy metals on human health. Copper and iron are correctly viewed as pollutant elements essential for maintaining human health because they are part of important enzymes and metabolic pathways. Healthy individuals are prepared through various genetically based mechanisms to maintain cellular copper and iron homeostasis, thereby circumventing or reducing hazardous liver and organ injury due to excessive amounts of these metals continuously entering the human body. In a few humans with gene aberration, however, liver and organ injury may develop because excessively accumulated copper can lead to Wilson disease and substantial iron deposition to hemochromatosis. At the molecular level, toxicities of some heavy metals are traced back to the Haber Weiss and Fenton reactions involving reactive oxygen species formed in the course of oxidative stress. On the other hand, cellular homeostasis for cadmium and arsenic cannot be provided, causing their life-long excessive deposition in the liver and other organs. Consequently, cadmium and arsenic represent health hazards leading to higher disability-adjusted life years and increased mortality rates due to cancer and non-cancer diseases. For unknown reasons, however, liver injury in humans exposed to cadmium and arsenic is rarely observed. In sum, copper and iron are good for the human health of most individuals except for those with Wilson disease or hemochromatosis at risk of liver injury through radical formation, while cadmium and arsenic lack any beneficial effects but rather are potentially hazardous to human health with a focus on increased disability potential and risk for cancer. Primary efforts should focus on reducing the industrial emission of hazardous heavy metals.

Network medicine-based analysis of the hepatoprotective effects of Amomum villosum Lour. on alcoholic liver disease in rats

Alcoholic liver disease (ALD) is characterized by high morbidity and mortality, and mainly results from prolonged and excessive alcohol use. Amomum villosum Lour. (A. villosum), a well-known traditional Chinese medicine (TCM), has hepatoprotective properties. However, its ability to combat alcohol-induced liver injury has not been fully explored. The objective of this study was to investigate the hepatoprotective effects of A. villosum in a rat model of alcohol-induced liver disease, thereby establishing a scientific foundation for the potential preventive use of A. villosum in ALD. We established a Chinese liquor (Baijiu)-induced liver injury model in rats. Hematoxylin and eosin (HE) staining, in combination with biochemical tests, was used to evaluate the protective effects of A. villosum on the liver. The integration of network medicine analysis with experimental validation was used to explore the hepatoprotective effects and potential mechanisms of A. villosum in rats. Our findings showed that A. villosum ameliorated alcohol-induced changes in body weight, liver index, hepatic steatosis, inflammation, blood lipid metabolism, and liver function in rats. Network proximity analysis was employed to identify 18 potentially active ingredients of A. villosum for ALD treatment. These potentially active ingredients in the blood were further identified using mass spectrometry (MS). Our results showed that A. villosum plays a hepatoprotective role by modulating the protein levels of estrogen receptor 1 (ESR1), anti-nuclear receptor subfamily 3 group C member 1 (NR3C1), interleukin 6 (IL-6), and tumor necrosis factor-α (TNF-α). In conclusion, the results of the current study suggested that A. villosum potentially exerts hepatoprotective effects on ALD in rats, possibly through regulating the protein levels of ESR1, NR3C1, IL-6, and TNF-α.

Wilson Disease: Copper-Mediated Cuproptosis, Iron-Related Ferroptosis, and Clinical Highlights, with Comprehensive and Critical Analysis Update

Wilson disease is a genetic disorder of the liver characterized by excess accumulation of copper, which is found ubiquitously on earth and normally enters the human body in small amounts via the food chain. Many interesting disease details were published on the mechanistic steps, such as the generation of reactive oxygen species (ROS) and cuproptosis causing a copper dependent cell death. In the liver of patients with Wilson disease, also, increased iron deposits were found that may lead to iron-related ferroptosis responsible for phospholipid peroxidation within membranes of subcellular organelles. All topics are covered in this review article, in addition to the diagnostic and therapeutic issues of Wilson disease. Excess Cu2+ primarily leads to the generation of reactive oxygen species (ROS), as evidenced by early experimental studies exemplified with the detection of hydroxyl radical formation using the electron spin resonance (ESR) spin-trapping method. The generation of ROS products follows the principles of the Haber-Weiss reaction and the subsequent Fenton reaction leading to copper-related cuproptosis, and is thereby closely connected with ROS. Copper accumulation in the liver is due to impaired biliary excretion of copper caused by the inheritable malfunctioning or missing ATP7B protein. As a result, disturbed cellular homeostasis of copper prevails within the liver. Released from the liver cells due to limited storage capacity, the toxic copper enters the circulation and arrives at other organs, causing local accumulation and cell injury. This explains why copper injures not only the liver, but also the brain, kidneys, eyes, heart, muscles, and bones, explaining the multifaceted clinical features of Wilson disease. Among these are depression, psychosis, dysarthria, ataxia, writing problems, dysphagia, renal tubular dysfunction, Kayser-Fleischer corneal rings, cardiomyopathy, cardiac arrhythmias, rhabdomyolysis, osteoporosis, osteomalacia, arthritis, and arthralgia. In addition, Coombs-negative hemolytic anemia is a key feature of Wilson disease with undetectable serum haptoglobin. The modified Leipzig Scoring System helps diagnose Wilson disease. Patients with Wilson disease are well-treated first-line with copper chelators like D-penicillamine that facilitate the removal of circulating copper bound to albumin and increase in urinary copper excretion. Early chelation therapy improves prognosis. Liver transplantation is an option viewed as ultima ratio in end-stage liver disease with untreatable complications or acute liver failure. Liver transplantation finally may thus be a life-saving approach and curative treatment of the disease by replacing the hepatic gene mutation. In conclusion, Wilson disease is a multifaceted genetic disease representing a molecular and clinical challenge.

Circulating cytokines and alcoholic liver disease: a two-sample bidirectional Mendelian randomization study

BACKGROUND

Increased inflammation in the liver during ethanol exposure is a major feature of alcoholic liver disease (ALD). An important contributing component to the development of ALD is the inflammatory response brought on by immunological response, however the connection between individual circulating cytokines and ALD is still unclear. To ascertain the causation, we conducted a two-sample bidirectional Mendelian randomization research.

METHODS

We extracted 41 cytokines and growth factors of 8293 Europeans and ALD cases of the same ethnicity (1416 cases and 217,376 controls) from the Genome-Wide Association Studies (GWAS) database for two-sample bidirectional MR analysis.

RESULTS

Our analyses suggest that higher interleukin-7 (IL-7) levels are associated with an increased risk of ALD (p = 0.028, OR = 1.191,95% CI = 1.019-1.392), while tumor necrosis factor related apoptosis inducing ligand (TRAIL) is a protective factor for ALD (p = 0.032, OR = 0.863, 95% CI = 0.754-0.988) which can reduce the risk of disease occurrence. In addition, genetically predicted ALD does not affect the expression of circulating cytokines regulators.

CONCLUSIONS

Our study supports that cytokines play a pivotal role in the pathogenesis of ALD. To determine the mechanisms and pathways of action of these biomarkers, further basic research is required to ensure their clinical suitability for preventing and treating ALD.

Bacillus coagulans regulates gut microbiota and ameliorates the alcoholic-associated liver disease in mice

Introduction

Alcoholic-associated liver diseases (ALD) are now widespread issues worldwide. Alcoholic-induced chronic dysbiosis of the gut microbiota is one of the factors in the pathophysiology of ALD.

Methods

In this work, we employed a chronic-binge ethanol feeding mice model, as described in a previous report.

Results

Our findings demonstrate that hepatic inflammatory injury damage and accumulation of fat can be effectively reduced in mice with ALD by altering the gut microbiota utilizing Bacillus coagulans. Treatment with B. coagulans significantly modulates the levels of TNF-α, IL-1β, and IL-22 cytokines while maintaining tight junction proteins and mucin protein expressions to support intestinal barrier function restoration. Treatment with B. coagulans also alters the composition of the gut microbiota and increases the production of short-chain fatty acids (SCFAs).

Discussion

This is mostly due to B. coagulans promotes the growth of bacteria that produce SCFAs, such as Ruminococcus species and Akkermansia, while inhibiting the growth of pathogenic bacteria like Escherichia Shigella. Moreover, treatment with B. coagulans causes levels of 2-Ketobutyric acid, ketoleucine, and indoleacetic acid increase while homovanillic acid and 3'-O-Methylguanosine metabolites decrease significantly. This study facilitates the development of therapeutic and preventive strategies for ALD using lactic acid bacteria.

Ambient particulate matter exposure plus chronic ethanol ingestion exacerbates hepatic fibrosis by triggering the mitochondrial ROS-ferroptosis signaling pathway in mice

BACKGROUND

Chronic ethanol ingestion causes persistent oxidative stresses in the liver, leading to hepatic injury and fibrosis, but the underlying mechanisms remain unclear. Recently, ambient particulate matter (PM) has been confirmed to aggravate high-fat diet-induced liver fibrosis by enhancing oxidative stress. Thus, we hypothesized that oxidative stress induced by ambient PM exposure increases the severity of liver fibrosis caused by ethanol ingestion.

METHODS AND RESULTS

C57BL/6 mice were subjected to ambient PM inhalation, ethanol ingestion or ambient PM-plus-ethanol ingestion for 12 weeks. Oxidative stress, mitochondrial reactive oxygen species (MtROS), liver fibrosis and ferroptosis indicators in the liver were evaluated. In vitro, oxidative stress, MtROS, ferroptosis indicators, profibrotic molecules and fibrosis markers in hepatic stellate (LX-2) cells were also determined. We found that ethanol ingestion markedly elevated hepatic oxidative stress and MtROS levels, triggered hepatic ferroptosis, and induced liver fibrosis, along with upregulation of the profibrotic molecule TGF-β1 and fibrosis marker collagen-I, in mice. Moreover, the combination of ambient PM and ethanol accelerated these adverse effects. Importantly, the combination of PM exposure and ethanol ingestion had a synergistic effect on these changes. In vitro, LX-2 cells activated with PM_2.5 alone or combined with ethanol showed upregulation of TGF-β1 and collagen-I. In addition, the levels of MtROS, the oxidative stress marker 4-hydroxynonenal (4-HNE) and ferroptosis-related proteins and the GSH/GSSG ratio were significantly increased in PM_2.5 plus ethanol-treated LX-2 cells. After pretreatment with a MtROS scavenger (Mito-TEMPO), we found that Mito-TEMPO treatment inhibited ferroptosis and oxidative stress in PM_2.5 plus ethanol-treated LX-2 cells. Furthermore, a specific ferroptosis inhibitor (Fer-1) decreased the levels of ferroptosis-related proteins and profibrotic molecules in activated LX-2 cells co-exposed to PM_2.5 and ethanol.

CONCLUSION

In this study, we revealed that ambient PM exposure induced profibrotic effects and that combined exposure to ambient PM and chronic ethanol ingestion exacerbated hepatic fibrosis, which may trigger ferroptosis by increasing MtROS, thereby activating hepatic stellate cells.

Alcohol, Inflammation, and Microbiota in Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a consequence of excessive alcohol use. According to many studies, alcohol represents a significant socioeconomic and health risk factor in today's population. According to data from the World Health Organization, there are about 75 million people who have alcohol disorders, and it is well known that its use leads to serious health problems. ALD is a multimodality spectrum that includes alcoholic fatty liver disease (AFL) and alcoholic steatohepatitis (ASH), consequently leading to liver fibrosis and cirrhosis. In addition, the rapid progression of alcoholic liver disease can lead to alcoholic hepatitis (AH). Alcohol metabolism produces toxic metabolites that lead to tissue and organ damage through an inflammatory cascade that includes numerous cytokines, chemokines, and reactive oxygen species (ROS). In the process of inflammation, mediators are cells of the immune system, but also resident cells of the liver, such as hepatocytes, hepatic stellate cells, and Kupffer cells. These cells are activated by exogenous and endogenous antigens, which are called pathogen and damage-associated molecular patterns (PAMPs, DAMPs). Both are recognized by Toll-like receptors (TLRs), which activation triggers the inflammatory pathways. It has been proven that intestinal dysbiosis and disturbed integrity of the intestinal barrier perform a role in the promotion of inflammatory liver damage. These phenomena are also found in chronic excessive use of alcohol. The intestinal microbiota has an important role in maintaining the homeostasis of the organism, and its role in the treatment of ALD has been widely investigated. Prebiotics, probiotics, postbiotics, and symbiotics represent therapeutic interventions that can have a significant effect on the prevention and treatment of ALD.

Effects of beer, wine, and baijiu consumption on non-alcoholic fatty liver disease: Potential implications of the flavor compounds in the alcoholic beverages

Non-alcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease and its global incidence is estimated to be 24%. Beer, wine, and Chinese baijiu have been consumed worldwide including by the NAFLD population. A better understanding of the effects of these alcoholic beverages on NAFLD would potentially improve management of patients with NAFLD and reduce the risks for progression to fibrosis, cirrhosis, and hepatocellular carcinoma. There is evidence suggesting some positive effects, such as the antioxidative effects of bioactive flavor compounds in beer, wine, and baijiu. These effects could potentially counteract the oxidative stress caused by the metabolism of ethanol contained in the beverages. In the current review, the aim is to evaluate and discuss the current human-based and laboratory-based study evidence of effects on hepatic lipid metabolism and NAFLD from ingested ethanol, the polyphenols in beer and wine, and the bioactive flavor compounds in baijiu, and their potential mechanism. It is concluded that for the potential beneficial effects of wine and beer on NAFLD, inconsistence and contrasting data exist suggesting the need for further studies. There is insufficient baijiu specific human-based study for the effects on NAFLD. Although laboratory-based studies on baijiu showed the antioxidative effects of the bioactive flavor compounds on the liver, it remains elusive whether the antioxidative effect from the relatively low abundance of the bioactivate compounds could outweigh the oxidative stress and toxic effects from the ethanol component of the beverages.

Pentoxifylline attenuates nonalcoholic fatty liver by inhibiting hepatic macrophage polarization to the M1 phenotype

BACKGROUND

Nonalcoholic fatty liver (NAFL), recognized as one of the most common causes of chronic liver diseases, is increasingly prevalent worldwide. Pentoxifylline, a derivative of theobromine extracted from Theobroma cacao and tea, has been studied for effects on blood viscosity, tissue oxygenation and inflammation. However, its effects on hepatic lipid accumulation and the potential mechanisms remain unclear.

PURPOSE

This study aimed to investigate the therapeutic effects of pentoxifylline on high-fat diet-induced NAFL and to explore the corresponding molecular mechanisms.

METHODS

NAFL mice were injected with or without 25, 50 or 100 mg/kg pentoxifylline for 2 weeks. Hepatic steatosis was observed by haematoxylin-eosin staining and Oil Red O staining, the levels of serum total cholesterol, triglyceride were detected by biochemical kits, and insulin resistance was evaluated by glucose and insulin tolerance tests. In addition, we measured the frequencies of macrophage and its polarization subsets in the liver using flow cytometry and immunofluorescence. The expressions of proteins associated with macrophage polarization signaling pathways were assessed by Western blotting and flow cytometry histograms. Molecular docking and cellular thermal shift assay were conducted to identify and verify the target protein of pentoxifylline in macrophage.

RESULTS

Pentoxifylline significantly alleviated hepatic lipid accumulation, reduced blood lipid levels and improved insulin resistance. Strikingly, the excessive M1 macrophages in NAFL development was abolished by pentoxifylline. And pentoxifylline was further evidenced it failed to reduce hepatocyte lipid accumulation in the absence of macrophages in vitro. Mechanistically, pentoxifylline competed with LPS for binding to toll-like receptor 4, dramatically inhibiting the TLR4/MyD88/NF-κB signaling pathway.

CONCLUSION

Pentoxifylline attenuated NAFL by inhibiting hepatic macrophage M1 polarization, indicating that pentoxifylline could be a therapeutic candidate for NAFL. This study first observed that M1 macrophages were increased in NAFL mice and then revealed the molecule targeted by pentoxifylline. In addition, we provided evidence that macrophage targeting may be an emerging strategy for NAFL treatment.

Aging of Liver in Its Different Diseases

The proportion of elderly people in the world population is constantly increasing. With age, the risk of numerous chronic diseases and their complications also rises. Research on the subject of cellular senescence date back to the middle of the last century, and today we know that senescent cells have different morphology, metabolism, phenotypes and many other characteristics. Their main feature is the development of senescence-associated secretory phenotype (SASP), whose pro-inflammatory components affect tissues and organs, and increases the possibility of age-related diseases. The liver is the main metabolic organ of our body, and the results of previous research indicate that its regenerative capacity is greater and that it ages more slowly compared to other organs. With age, liver cells change under the influence of various stressors and the risk of developing chronic liver diseases such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), alcoholic steatohepatitis (ASH) and hepatocellular carcinoma (HCC) increases. It has been proven that these diseases progress faster in the elderly population and in some cases lead to end-stage liver disease that requires transplantation. The treatment of elderly people with chronic liver diseases is a challenge and requires an individual approach as well as new research that will reveal other safe and effective therapeutic modalities.

Advancements in the Alcohol-Associated Liver Disease Model

Alcohol-associated liver disease (ALD) is an intricate disease that results in a broad spectrum of liver damage. The presentation of ALD can include simple steatosis, steatohepatitis, liver fibrosis, cirrhosis, and even hepatocellular carcinoma (HCC). Effective prevention and treatment strategies are urgently required for ALD patients. In previous decades, numerous rodent models were established to investigate the mechanisms of alcohol-associated liver disease and explore therapeutic targets. This review provides a summary of the latest developments in rodent models, including those that involve EtOH administration, which will help us to understand the characteristics and causes of ALD at different stages. In addition, we discuss the pathogenesis of ALD and summarize the existing in vitro models. We analyse the pros and cons of these models and their translational relevance and summarize the insights that have been gained regarding the mechanisms of alcoholic liver injury.

Modulation of IL-36-based inflammatory feedback loop through hepatocytes-derived IL-36R-P2X7R axis improves steatosis in alcoholic steatohepatitis

BACKGROUND AND PURPOSE

IL-36 is induced by proinflammatory cytokines and itself promotes inflammatory responses, shaping an IL-36-based inflammation loop. Although, hepatocytes, as "epithelial cell-like" hepatic parenchymal cells, produce IL-36 responses to drug-induced liver injury, little is known about the mechanistic role of the IL-36 signalling during the progression of alcoholic steatohepatitis (ASH). Regarding IL-36/IL-36R and P2X7R coregulates the inflammatory response, we elucidated the modulation of IL-36R-P2X7R-TLRs axis affected hepatocytes steatosis and IL-36-based inflammatory feedback loop that accompanies the onset of ASH.

EXPERIMENTAL APPROACH

C57BL/6J mice were subjected to chronic-plus-binge ethanol feeding or acute gavage with multiple doses of ethanol to establish ASH, followed by pharmacological inhibition or genetic silencing of IL-36R and P2X7R. AML12 cells or mouse primary hepatocytes were stimulated with alcohol, LPS plus ATP or Poly(I:C) plus ATP, followed by silencing of IL-36γ, IL-36R or P2X7R.

KEY RESULTS

P2X7R and IL-36R deficiency blocked the inflammatory loop, especially made by IL-36 cytokines, in hepatocytes of mice suffering from ASH. Pharmacological inhibition to P2X7R or IL-36R alleviated lipid accumulation and inflammatory response in ASH. IL-36R was indispensable for P2X7R modulated NLRP3 inflammasome activation in ASH and IL-36 led to a vicious cycle of P2X7R-driven inflammation in alcohol-exposed hepatocytes. TLR ligands promoted IL-36γ production in hepatocytes based on the synergism of P2X7R.

CONCLUSIONS AND IMPLICATIONS

Blockade of IL-36-based inflammatory feedback loop via IL-36R-P2X7R-TLRs-modulated NLRP3 inflammasome activation circumvented the steatosis and inflammation that accompanies the onset of ASH, suggesting that targeting IL-36 might serve as a novel therapeutic approach to combat ASH.

Inhibition of HMGB1/TLR4 Signaling Pathway by Digitoflavone: A Potential Therapeutic Role in Alcohol-Associated Liver Disease

Digitoflavone (DG) is a natural flavonoid abundant in many fruits, vegetables, and medicinal plants. We investigated whether DG inhibits lipid accumulation and inflammatory responses in alcoholic liver disease (ALD) in vivo and in vitro. The mouse ALD model was established by chronically feeding male C57BL/6 mice an ethanol-containing Lieber-DeCarli liquid diet. In vitro, mouse peritoneal macrophages (MPMs) and mouse bone marrow-derived macrophages (BMDMs) were stimulated with LPS/ATP, whereas HepG2 cells and mouse primary hepatocytes were treated with ethanol. DG reduced the serum levels of transaminase and serum and hepatic levels of triglycerides and malondialdehyde in ALD mice. DG downregulated SREBP1 and its target genes and upregulated PPARα and its target genes in the liver of mice with ALD. DG inhibited TLR4-mediated NLRP3 inflammasome activation, consequently reversing the inflammatory response, including the production of HMGB1, IL-1β, and IL-36γ, as well as the infiltration of macrophages and neutrophils. DG blocked NLRP3/ASC/caspase-1 inflammasome activation and HMGB1 release in LPS/ATP-stimulated MPMs. When Tlr4 was knocked in LPS/ATP-stimulated BMDMs, HMGB1 production and release were blocked, and NLRP3-mediated cleavage and release of IL-1β was suppressed in Hmgb1-silenced BMDMs. DG amplified these inhibitory effects in Tlr4 or Hmgb1 knockdown BMDMs. In ethanol-exposed hepatocytes, DG reduced lipogenesis and promoted lipid oxidation by inhibiting the HMGB1-TLR4 signaling pathway while suppressing the inflammatory response induced by ethanol exposure. Our data demonstrated that DG inhibited the occurrence of lipid accumulation and the inflammatory response via the HMGB1-TLR4 axis, underscoring a promising approach and utility of DG for the treatment of ALD.

Production of Bioactive Substances to Alleviates Hangover and Ethanol-Induced Liver Damage through Fermentation of Oenanthe javanica Using Lactiplantibacillus plantarum

The purpose of this study is to evaluate the effect of the bioconversion products of Oenanthe javanica extract fermented by Lactiplantibacillus plantarum (OEFL) on relieving hangovers and improving liver function. In addition, the bioactive substance of the OEFL, which alleviates hangover and ethanol-induced liver damage, was identified and its bioactive property was verified through in vivo experiments. In major substances analysis using high-performance liquid chromatography, OEFL produced 9.5-fold higher p-coumaric acid than the O. Javanica extract (OE). In addition, considering that quinic acid, which is not present in the OE, was produced in the OEFL it was confirmed that chlorogenic acid was decomposed into quinic acid by bioconversion. In the in vivo experiment using Sprague-Dawley rats, the OEFL and p-coumaric acid diets reduced blood ethanol, acetaldehyde, GPT, and ALP concentrations, increasing blood albumin concentrations compared to ethanol-administered groups, demonstrating that OEFL and p-coumaric acid, the main substance in the OEFL, improved ethanol-induced liver damage. Furthermore, the OEFL and its main bioactive substance, p-coumaric acid, alleviated liver fibrosis by downregulating TGF-β, SMAD-2, SMAD-4, α-SMA, and upregulating MMP-1. Therefore, OEFL is expected to be used as a functional food or pharmaceutical material as it has been confirmed to effectively relieve hangovers, prevent liver damage, and delay liver fibrosis in ethanol-induced liver damages.

Activation of UQCRC2-dependent mitophagy by tetramethylpyrazine inhibits MLKL-mediated hepatocyte necroptosis in alcoholic liver disease

Hepatocyte necroptosis is a core pathogenetic event during alcoholic liver disease. This study was aimed to explore the potential of tetramethylpyrazine (TMP), an active hepatoprotective ingredient extracted from Ligusticum Wallichii Franch, in limiting alcohol-triggered hepatocyte necroptosis and further specify the molecular mechanism. Results revealed that TMP reduced activation of receptor-interacting protein kinase 1 (RIPK1)/RIPK3 necrosome in ethanol-exposed hepatocytes and phosphorylation of mixed-lineage kinase domain-like protein (MLKL), which thereby diminished necroptosis and leakage of damage-associated molecular patterns. Suppression on mitochondrial translocation of p-MLKL by TMP contributed to recovery of mitochondrial function in ethanol-damaged hepatocytes. TMP also disrupted necroptotic signal loop by interrupting mitochondrial reactive oxygen species (ROS)-dependent positive feedback between p-MLKL and RIPK1/RIPK3 necrosome. Further, TMP promoted clearance of impaired mitochondria in ethanol-incubated hepatocytes via restoring PINK1/parkin-mediated mitophagy. Ubiquinol-cytochrome c reductase core protein 2 (UQCRC2) was downregulated in ethanol-exposed hepatocytes, which was restored after TMP treatment. In vitro UQCRC2 knockdown lowered the capacities of TMP in reducing mitochondrial ROS accumulation, relieving mitochondria damage, and enhancing PINK1/parkin-mediated mitophagy in ethanol-exposed hepatocytes. Analogously, systematic UQCRC2 knockdown interrupted the actions of TMP to trigger autophagic signal, repress necroptotic signal, and protect against alcoholic liver injury, inflammation, and ROS overproduction. In conclusion, this work concluded that TMP rescued UQCRC2 expression in ethanol-challenged hepatocytes, which contributed to necroptosis inhibition by facilitating PINK1/parkin-mediated mitophagy. These findings uncovered a potential molecular pharmacological mechanism underlying the hepatoprotective action of TMP and suggested TMP as a promising therapeutic candidate for alcoholic liver disease.

The Role of Epigenetic Changes in the Progression of Alcoholic Steatohepatitis

Alcoholic steatohepatitis (ASH) is a progression hepatitis with severe fatty liver and its mortality rate for 30-days in patients are over 30%. Additionally, ASH is well known for one-fifth all alcoholic related liver diseases in the world. Excessive chronic alcohol consumption is one of the most common causes of the progression of ASH and is associated with poor prognosis and liver failure. Alcohol abuse dysregulates the lipid homeostasis and causes oxidative stress and inflammation in the liver. Consequently, metabolic pathways stimulating hepatic accumulation of excessive lipid droplets are induced. Recently, many studies have indicated a link between ASH and epigenetic changes, showing differential expression of alcohol-induced epigenetic genes in the liver. However, the specific mechanisms underlying the pathogenesis of ASH remain elusive. Thus, we here summarize the current knowledge about the roles of epigenetics in lipogenesis, inflammation, and apoptosis in the context of ASH pathophysiology. Especially, we highlight the latest findings on the roles of Sirtuins, a conserved family of class-III histone deacetylases, in ASH. Additionally, we discuss the involvement of DNA methylation, histone modifications, and miRNAs in ASH as well as the ongoing efforts for the clinical translation of the findings in ASH-related epigenetic changes.

Genetic Variants of Alcohol Metabolizing Enzymes and Alcohol-Related Liver Cirrhosis Risk

Alcohol-related liver disease (ARLD) is a major public health issue caused by excessive alcohol consumption. ARLD encompasses a wide range of chronic liver lesions, alcohol-related liver cirrhosis being the most severe and harmful state. Variations in the genes encoding the enzymes, which play an active role in ethanol metabolism, might influence alcohol exposure and hence be considered as risk factors of developing cirrhosis. We conducted a case-control study in which 164 alcohol-related liver cirrhosis patients and 272 healthy controls were genotyped for the following functional single nucleotide variations (SNVs): ADH1B gene, rs1229984, rs1041969, rs6413413, and rs2066702; ADH1C gene, rs35385902, rs283413, rs34195308, rs1693482, and rs35719513; CYP2E1 gene, rs3813867. Furthermore, copy number variations (CNVs) for ADH1A, ADH1B, ADH1C, and CYP2E1 genes were analyzed. A significant protective association with the risk of developing alcohol-related liver cirrhosis was observed between the mutant alleles of SNVs ADH1B rs1229984 (P_c value = 0.037) and ADH1C rs283413 (P_c value = 0.037). We identified CNVs in all genes studied, ADH1A gene deletions being more common in alcohol-related liver cirrhosis patients than in control subjects, although the association lost statistical significance after multivariate analyses. Our findings support that susceptibility to alcohol-related liver cirrhosis is related to variations in alcohol metabolism genes.

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.

Butyrate ameliorates alcoholic fatty liver disease via reducing endotoxemia and inhibiting liver gasdermin D-mediated pyroptosis

Background

Alcoholic fatty liver disease (AFLD) is characterized by hepatic steatosis and carries an elevated risk of cirrhosis and hepatocellular carcinoma. However, the mechanism of AFLD has not been elucidated thoroughly, and there are still no efficient therapies in clinic. Notably, butyrate, one kind of short-chain fatty acids produced by gut microbiota, has been shown to improve methionine-choline-deficient diet-induced non-alcoholic steatohepatitis. And our previous study found that butyrate ameliorated endotoxemia in db/db mice. In this study, we aimed to explore the role of butyrate in the development of AFLD.

Methods

C57BL/6 mice were treated with saline (normal control), alcohol with or without butyrate by gavage for 6 months. AFLD was evaluated by the levels of serum alcohol, aspartate aminotransferase (AST), alanine transaminase (ALT), triglyceride (TG) and intrahepatic TG. And the histology and inflammation in liver and colon were analyzed using hematoxylin-eosin (H&E) staining, immunohistochemistry and western blot. In addition, gut microbiota composition was analyzed using the V3–V4 regions of the bacterial 16S ribosomal RNA gene by sequence. Furthermore, we performed in vitro experiment to verify the role of butyrate in hepatocyte by western blot and transmission electron microscopy.

Results

We found that butyrate ameliorated alcohol-induced hepatic steatosis and inflammation. Furthermore, chronic alcohol feeding induced dysbiosis and dysfunction of the gut microbiota, disrupted the intestinal barrier, and increased serum endotoxin levels. Meanwhile, butyrate improved the intestinal barrier disruption and endotoxemia induced by alcohol, but did not significantly alleviate the microbiome dysfunction. Mechanistically, butyrate ameliorated AFLD by inhibiting gasdermin D (GSDMD)-mediated pyroptosis.

Conclusions

In summary, we found butyrate ameliorated alcoholic fatty liver by down-regulating GSDMD-mediated pyroptosis. We speculate that butyrate improves AFLD mainly by maintaining intestinal barrier function and alleviating gut leakage. These findings suggest that butyrate may have the potential to serve as a novel treatment for AFLD.

Alcoholic-Hepatitis, Links to Brain and Microbiome: Mechanisms, Clinical and Experimental Research

The following review article presents clinical and experimental features of alcohol-induced liver disease (ALD). Basic aspects of alcohol metabolism leading to the development of liver hepatotoxicity are discussed. ALD includes fatty liver, acute alcoholic hepatitis with or without liver failure, alcoholic steatohepatitis (ASH) leading to fibrosis and cirrhosis, and hepatocellular cancer (HCC). ALD is fully attributable to alcohol consumption. However, only 10-20% of heavy drinkers (persons consuming more than 40 g of ethanol/day) develop clinical ALD. Moreover, there is a link between behaviour and environmental factors that determine the amount of alcohol misuse and their liver disease. The range of clinical presentation varies from reversible alcoholic hepatic steatosis to cirrhosis, hepatic failure, and hepatocellular carcinoma. We aimed to (1) describe the clinico-pathology of ALD, (2) examine the role of immune responses in the development of alcoholic hepatitis (ASH), (3) propose diagnostic markers of ASH, (4) analyze the experimental models of ALD, (5) study the role of alcohol in changing the microbiota, and (6) articulate how findings in the liver and/or intestine influence the brain (and/or vice versa) on ASH; (7) identify pathways in alcohol-induced organ damage and (8) to target new innovative experimental concepts modeling the experimental approaches. The present review includes evidence recognizing the key toxic role of alcohol in ALD severity. Cytochrome p450 CYP2E1 activation may change the severity of ASH. The microbiota is a key element in immune responses, being an inducer of proinflammatory T helper 17 cells and regulatory T cells in the intestine. Alcohol consumption changes the intestinal microbiota and influences liver steatosis and liver inflammation. Knowing how to exploit the microbiome to modulate the immune system might lead to a new form of personalized medicine in ALF and ASH.

Diagnostic Biomarkers in Liver Injury by Drugs, Herbs, and Alcohol: Tricky Dilemma after EMA Correctly and Officially Retracted Letter of Support

Liver injuries caused by the use of exogenous compounds such as drugs, herbs, and alcohol are commonly well diagnosed using laboratory tests, toxin analyses, or eventually reactive intermediates generated during metabolic degradation of the respective chemical in the liver and subject to covalent binding by target proteins. Conditions are somewhat different for idiosyncratic drug induced liver injury (DILI), for which metabolic intermediates as diagnostic aids are rarely available. Although the diagnosis of idiosyncratic DILI can well be established using the validated, liver specific, structured, and quantitative RUCAM (Roussel Uclaf Causality Assessment Method), there is an ongoing search for new diagnostic biomarkers that could assist in and also confirm RUCAM-based DILI diagnoses. With respect to idiosyncratic DILI and following previous regulatory letters of recommendations, selected biomarkers reached the clinical focus, including microRNA-122, microRNA-192, cytokeratin analogues, glutamate dehydrogenase, total HMGB-1 (High Mobility Group Box), and hyperacetylated HMGB-1 proteins. However, the new parameters total HMGB-1, and even more so the acetylated HMGB-1, came under critical scientific fire after misconduct at one of the collaborating partner centers, leading the EMA to recommend no longer the exploratory hyperacetylated HMGB1 isoform biomarkers in clinical studies. The overall promising nature of the recommended biomarkers was considered by EMA as highly dependent on the outstanding results of the now incriminated biomarker hyperacetylated HMGB-1. The EMA therefore correctly decided to officially retract its Letter of Support affecting all biomarkers listed above. New biomarkers are now under heavy scrutiny that will require re-evaluations prior to newly adapted recommendations. With Integrin beta 3 (ITGB3), however, a new diagnostic biomarker may emerge, possibly being drug specific but tested in only 16 patients; due to substantial remaining uncertainties, final recommendations would be premature. In conclusion, most of the currently recommended new biomarkers have lost regulatory support due to scientific misconduct, requiring now innovative approaches and re-evaluation before they can be assimilated into clinical practice.

Alcoholic Liver Disease: Current Mechanistic Aspects with Focus on Their Clinical Relevance

The spectrum of alcoholic liver disease (ALD) is broad and includes alcoholic fatty liver, alcoholic steatohepatitis, alcoholic hepatitis, alcoholic fibrosis, alcoholic cirrhosis, and alcoholic hepatocellular carcinoma, best explained as a five-hit sequelae of injurious steps. ALD is not primarily the result of malnutrition as assumed for many decades but due to the ingested alcohol and its metabolic consequences although malnutrition may marginally contribute to disease aggravation. Ethanol is metabolized in the liver to the heavily reactive acetaldehyde via the alcohol dehydrogenase (ADH) and the cytochrome P450 isoform 2E1 of the microsomal ethanol-oxidizing system (MEOS). The resulting disturbances modify not only the liver parenchymal cells but also non-parenchymal cells such as Kupffer cells (KCs), hepatic stellate cells (HSCs), and liver sinusoidal endothelial cells (LSECs). These are activated by acetaldehyde, reactive oxygen species (ROS), and endotoxins, which are produced from bacteria in the gut and reach the liver due to gut leakage. A variety of intrahepatic signaling pathways and innate or acquired immune reactions are under discussion contributing to the pathogenesis of ALD via the five injurious hits responsible for disease aggravation. As some of the mechanistic steps are based on studies with in vitro cell systems or animal models, respective proposals for humans may be considered as tentative. However, sufficient evidence is provided for clinical risk factors that include the amount of alcohol used daily for more than a decade, gender differences with higher susceptibility of women, genetic predisposition, and preexisting liver disease. In essence, efforts within the last years were devoted to shed more light in the pathogenesis of ALD, much has been achieved but issues remain to what extent results obtained from experimental studies can be transferred to humans.

Aldose Reductase Inhibitors of Plant Origin in the Prevention and Treatment of Alcoholic Liver Disease: A Minireview

Alcoholic liver disease (ALD) is caused by heavy alcohol consumption over a long period. Acetaldehyde-mediated toxicity, oxidative stress, and imbalance of lipid metabolism are generally considered involved in the initiation of ALD. There is an increasing requirement for alternative and natural medicine to treat ALD. Recently, aldose reductase (AR) has been reported to be involved in the development of ALD by affecting inflammatory cytokines, oxidative stress, and lipid metabolism. Here, we review the effect of plant-derived AR inhibitors on ALD in rodents. And we conclude that AR inhibitors of plant origin may enhance antioxidant capacity, inhibit lipid peroxidation and inflammatory cytokines expression, and activate AMP-activated protein kinase thereby subsequently suppressing alcohol-induced lipid synthesis in liver to achieve ALD protection. This review reveals that natural AR inhibitor may be potential therapeutic agent for ALD.

Pathogenesis, Early Diagnosis, and Therapeutic Management of Alcoholic Liver Disease

Alcoholic liver disease (ALD) refers to the damages to the liver and its functions due to alcohol overconsumption. It consists of fatty liver/steatosis, alcoholic hepatitis, steatohepatitis, chronic hepatitis with liver fibrosis or cirrhosis, and hepatocellular carcinoma. However, the mechanisms behind the pathogenesis of alcoholic liver disease are extremely complicated due to the involvement of immune cells, adipose tissues, and genetic diversity. Clinically, the diagnosis of ALD is not yet well developed. Therefore, the number of patients in advanced stages has increased due to the failure of proper early detection and treatment. At present, abstinence and nutritional therapy remain the conventional therapeutic interventions for ALD. Moreover, the therapies which target the TNF receptor superfamily, hormones, antioxidant signals, and MicroRNAs are used as treatments for ALD. In particular, mesenchymal stem cells (MSCs) are gaining attention as a potential therapeutic target of ALD. Therefore, in this review, we have summarized the current understandings of the pathogenesis and diagnosis of ALD. Moreover, we also discuss the various existing treatment strategies while focusing on promising therapeutic approaches for ALD.

Targeting Myeloid-Derived Cells: New Frontiers in the Treatment of Non-alcoholic and Alcoholic Liver Disease

Non-alcoholic fatty liver disease (NAFLD) and Alcoholic Liver Disease (ALD) are major causes of liver-related morbidity and mortality and constitute important causes of liver transplantation. The spectrum of the liver disease is wide and includes isolated steatosis, steatohepatitis, and cirrhosis. The treatment of NAFLD and ALD remains, however, an unmet need, and therefore it is a public health priority to develop effective treatments for these diseases. Alcoholic and non-alcoholic liver disease share common complex pathogenetic pathways that involve different organs and systems beyond the liver, including the gut, the adipose tissue, and the immune system, which cross-talk to generate damage. Myeloid-derived cells have been widely studied in the setting of NAFLD and ALD and are implicated at different levels in the onset and progression of this disease. Among these cells, monocytes and macrophages have been found to be involved in the induction of inflammation and in the progression to fibrosis, both in animal models and clinical studies and they have become interesting potential targets for the treatment of both NAFLD and ALD. The different mechanisms by which these cells can be targeted include modulation of Kupffer cell activation, monocyte recruitment in the liver and macrophage polarization and differentiation. Evidence from preclinical studies and clinical trials (some of them already in phase II and III) have shown encouraging results in ameliorating steatohepatitis, fibrosis, and the metabolic profile, individuating promising candidates for the pharmacological treatment of these diseases. The currently available results of myeloid-derived cells targeted treatments in NAFLD and ALD are covered in this review.

Microsomal Ethanol-Oxidizing System: Success Over 50 Years and an Encouraging Future

Fifty years ago, in 1968, the pioneering scientists Charles S. Lieber and Leonore M. DeCarli discovered the capacity for liver microsomes to oxidize ethanol (EtOH) and named it the microsomal ethanol-oxidizing system (MEOS), which revolutionized clinical and experimental alcohol research. The last 50 years of MEOS are now reviewed and highlighted. Since its discovery and as outlined in a plethora of studies, significant insight was gained regarding the fascinating nature of MEOS: (i) MEOS is distinct from alcohol dehydrogenase and catalase, representing a multienzyme complex with cytochrome P450 (CYP) and its preferred isoenzyme CYP 2E1, NADPH-cytochrome P450 reductase, and phospholipids; (ii) it plays a significant role in alcohol metabolism at high alcohol concentrations and after induction due to prolonged alcohol use; (iii) hydroxyl radicals and superoxide radicals promote microsomal EtOH oxidation, assisted by phospholipid peroxides; (iv) new aspects focus on microsomal oxidative stress through generation of reactive oxygen species (ROS), with intermediates such as hydroxyethyl radical, ethoxy radical, acetyl radical, singlet radical, hydroxyl radical, alkoxyl radical, and peroxyl radical; (v) triggered by CYP 2E1, ROS are involved in the initiation and perpetuation of alcoholic liver injury, consequently shifting the previous nutrition-based concept to a clear molecular-based disease; (vi) intestinal CYP 2E1 induction and ROS are involved in endotoxemia, leaky gut, and intestinal microbiome modifications, together with hepatic CYP 2E1 and liver injury; (vii) circulating blood CYP 2E1 exosomes may be of diagnostic value; (viii) circadian rhythms provide high MEOS activities associated with significant alcohol metabolism and potential toxicity risks as a largely neglected topic; and (ix) a variety of genetic animal models are useful and have been applied elucidating mechanistic aspects of MEOS. In essence, MEOS along with its CYP 2E1 component currently explains several mechanistic steps leading to alcoholic liver injury and has a promising future in alcohol research.

Aliphatic Halogenated Hydrocarbons: Report and Analysis of Liver Injury in 60 Patients

Background and Aims: Intoxications by aliphatic halogenated hydrocarbons (AHH), used as effective solvents, are rare and may cause life-threatening liver injury. Patients with acute intoxications by AHH received an innovative treatment. Methods: Analyzed were data of 60 patients intoxicated by AHH, such as dichloromethane (n = 3), chloroform (n = 2), carbon tetrachloride (n = 12), 1,2-dichloroethane (n = 18), 1,1,2-trichloroethane (n = 2), trichloroethylene (n = 2), tetrachloroethylene (n = 13) or mixed AHH chemicals (n = 8), who received a new treatment consisting of CO₂-induced hyperventilation to accelerate toxin removal via the lungs. Results: Added to the inspiration air at a flow rate of 2-3 Liter min^-1, CO₂ increased the respiratory volume up to 25-30 Liter min^-1, ensuring forced AHH exhalation. This CO₂-induced hyperventilation therapy was commonly well tolerated by the 60 patients and lasted for 106.0±10.5 hours. In most cases, initially increased liver test results of aminotransferases normalized quickly under the therapy, and liver histology obtained at completion of the therapy revealed, in the majority of patients, normal findings or fatty changes, and rarely severe single cell necrosis but no confluent liver cell necrosis. Despite therapy, clinical outcome was unfavorable for 4/60 patients (6.7%) of the study cohort, due to single or combined risk factors. These included late initiation of the CO₂-induced hyperventilation therapy, intentional intoxication, uptake of high amounts of AHH, concomitant ingestion of overdosed drugs, consumption of high amounts of alcohol, and history of alcohol abuse. Conclusions: For intoxications by AHH, effective therapy approaches including forced hyperventilation to increase toxin removal via the lungs are available and require prompt initiation.

Alcoholic Liver Disease: Alcohol Metabolism, Cascade of Molecular Mechanisms, Cellular Targets, and Clinical Aspects

Alcoholic liver disease is the result of cascade events, which clinically first lead to alcoholic fatty liver, and then mostly via alcoholic steatohepatitis or alcoholic hepatitis potentially to cirrhosis and hepatocellular carcinoma. Pathogenetic events are linked to the metabolism of ethanol and acetaldehyde as its first oxidation product generated via hepatic alcohol dehydrogenase (ADH) and the microsomal ethanol-oxidizing system (MEOS), which depends on cytochrome P450 2E1 (CYP 2E1), and is inducible by chronic alcohol use. MEOS induction accelerates the metabolism of ethanol to acetaldehyde that facilitates organ injury including the liver, and it produces via CYP 2E1 many reactive oxygen species (ROS) such as ethoxy radical, hydroxyethyl radical, acetyl radical, singlet radical, superoxide radical, hydrogen peroxide, hydroxyl radical, alkoxyl radical, and peroxyl radical. These attack hepatocytes, Kupffer cells, stellate cells, and liver sinusoidal endothelial cells, and their signaling mediators such as interleukins, interferons, and growth factors, help to initiate liver injury including fibrosis and cirrhosis in susceptible individuals with specific risk factors. Through CYP 2E1-dependent ROS, more evidence is emerging that alcohol generates lipid peroxides and modifies the intestinal microbiome, thereby stimulating actions of endotoxins produced by intestinal bacteria; lipid peroxides and endotoxins are potential causes that are involved in alcoholic liver injury. Alcohol modifies SIRT1 (Sirtuin-1; derived from Silent mating type Information Regulation) and SIRT2, and most importantly, the innate and adapted immune systems, which may explain the individual differences of injury susceptibility. Metabolic pathways are also influenced by circadian rhythms, specific conditions known from living organisms including plants. Open for discussion is a 5-hit working hypothesis, attempting to define key elements involved in injury progression. In essence, although abundant biochemical mechanisms are proposed for the initiation and perpetuation of liver injury, patients with an alcohol problem benefit from permanent alcohol abstinence alone.

Liver Injury by Carbon Tetrachloride Intoxication in 16 Patients Treated with Forced Ventilation to Accelerate Toxin Removal via the Lungs: A Clinical Report

Carbon tetrachloride (CCl₄) is an efficient but highly toxic solvent, used in households and commercially in the industry under regulatory surveillance to ensure safety at the working place and to protect the workers’ health. However, acute unintentional or intentional intoxications by CCl₄ may rarely occur and are potentially life-threatening. In this review article, therapy options are discussed that are based on a literature review of traditional poisoning cases and the clinical experience with 16 patients with acute poisoning by CCl₄. Among various therapy options, the CO₂-induced hyperventilation therapy will be considered in detail as the most promising approach. This special therapy was developed because only around 1% of the intoxicating CCl₄ is responsible for the liver injury after conversion to toxic radicals via microsomal cytochrome P450 2E1 whereas 99% of the solvent will leave the body unchanged by exhalation. Therefore, to enhance CCl₄ elimination through the lungs, CO₂ is added to the inspiration air at a flow rate of 2⁻3 L min−1 in order to achieve hyperventilation with a respiratory volume of 25⁻30 L min−1. Under this therapy, the clinical course was favorable in 15/16 patients, corresponding to 93.8%. In essence, patients with acute CCl₄ intoxication should be treated by forced ventilation.