Pathogenesis of non-alcoholic fatty liver disease in children and adolescence: From “two hit theory” to “multiple hit model”

IL-1 receptor-associated kinase family proteins: An overview of their role in liver disease

The interleukin-1 receptor-associated kinase (IRAK) family is a group of serine-threonine kinases that regulates various cellular processes via toll-like receptor (TLR)/interleukin-1 receptor (IL1R)-mediated signaling. The IRAK family comprises four members, including IRAK1, IRAK2, IRAK3, and IRAK4, which play an important role in the expression of various inflammatory genes, thereby contributing to the inflammatory response. IRAKs are key proteins in chronic and acute liver diseases, and recent evidence has implicated IRAK family proteins (IRAK1, IRAK3, and IRAK4) in the progression of liver-related disorders, including alcoholic liver disease, non-alcoholic steatohepatitis, hepatitis virus infection, acute liver failure, liver ischemia-reperfusion injury, and hepatocellular carcinoma. In this article, we provide a comprehensive review of the role of IRAK family proteins and their associated inflammatory signaling pathways in the pathogenesis of liver diseases. The purpose of this study is to explore whether IRAK family proteins can serve as the main target for the treatment of liver related diseases.

Oxidative Stress as a Target for Non-Pharmacological Intervention in MAFLD: Could There Be a Role for EVOO?

Oxidative stress plays a central role in most chronic liver diseases and, in particular, in metabolic dysfunction-associated fatty liver disease (MAFLD), the new definition of an old condition known as non-alcoholic fatty liver disease (NAFLD). The mechanisms leading to hepatocellular fat accumulation in genetically predisposed individuals who adopt a sedentary lifestyle and consume an obesogenic diet progress through mitochondrial and endoplasmic reticulum dysfunction, which amplifies reactive oxygen species (ROS) production, lipid peroxidation, malondialdehyde (MDA) formation, and influence the release of chronic inflammation and liver damage biomarkers, such as pro-inflammatory cytokines. This close pathogenetic link has been a key stimulus in the search for therapeutic approaches targeting oxidative stress to treat steatosis, and a number of clinical trials have been conducted to date on subjects with NAFLD using drugs as well as supplements or nutraceutical products. Vitamin E, Vitamin D, and Silybin are the most studied substances, but several non-pharmacological approaches have also been explored, especially lifestyle and diet modifications. Among the dietary approaches, the Mediterranean Diet (MD) seems to be the most reliable for affecting liver steatosis, probably with the added value of the presence of extra virgin olive oil (EVOO), a healthy food with a high content of monounsaturated fatty acids, especially oleic acid, and variable concentrations of phenols (oleocanthal) and phenolic alcohols, such as hydroxytyrosol (HT) and tyrosol (Tyr). In this review, we focus on non-pharmacological interventions in MAFLD treatment that target oxidative stress and, in particular, on the role of EVOO as one of the main antioxidant components of the MD.

Chronic unpredictable mild stress increases serum aldosterone without affecting corticosterone levels and induces hepatic steatosis and renal injury in young adult male rats

Stress is often associated with anxiety and depressive symptoms in adolescents. Stress is associated with components of metabolic syndrome and inflammation. The present study hypothesizes that aldosterone, more than corticosterone, promotes chronic stress-hepatic steatosis and fibrosis, as well as renal inflammation and fibrosis in young adult rats. Thirty-two young adult male Wistar rats of 51 days old were divided into four groups (n = 8 per group): Control (C), chronic unpredictable mild stress (CUMS), control plus vehicle (C plus veh), CUMS plus eplerenone, a selective aldosterone blocker (CUMS plus EP). On postnatal day 51, eplerenone was administered orally through a gastric tube two hours before the start of the stress test. The CUMS paradigm was administered once daily at different times, with no repetition of the stressor sequence for four weeks. Renal inflammation and fibrosis were measured, as well as liver glycogen, triacylglycerol, and fibrosis levels. The serum concentrations of corticosterone, aldosterone, sodium, and creatinine were measured in urine and serum. The CUMS group showed a high level of serum aldosterone without affecting the level of corticosterone, increased urinary sodium, tubular atrophy, glomerular sclerosis, the presence of inflammation, and fibrosis, without affecting creatinine, increased glycogen content, triacylglycerol, and moderate fibrosis in the liver, and treatment with eplerenone prevented the inflammation, fibrosis, glycogen, and triacylglycerol. Our results show that chronic stress-induced aldosterone promotes hepatic steatosis and renal injury more than corticosterone. The prevention by eplerenone supports our hypothesis.

Multiscale 3D genome organization underlies duck fatty liver with no adipose inflammation or serious injury

Non-alcoholic fatty liver disease (NAFLD) is the most common form of chronic liver disease. Little is known about how gene expression and chromatin structure are regulated in NAFLD due to lack of suitable model. Ducks naturally develop fatty liver similar to serious human non-alcoholic fatty liver (NAFL) without adipose inflammation and liver fibrosis, thus serves as a good model for investigating molecular mechanisms of adipose metabolism and anti-inflammation. Here, we constructed a NAFLD model without adipose inflammation and liver fibrosis in ducks. By performing dynamic pathological and transcriptomic analyses, we identified critical genes involving in regulation of the NF-κB and MHCII signaling, which usually lead to adipose inflammation and liver fibrosis. We further generated dynamic three-dimensional chromatin maps during liver fatty formation and recovery. This showed that ducks enlarged hepatocyte cell nuclei to reduce inter-chromosomal interaction, decompress chromatin structure, and alter strength of intra-TAD and loop interactions during fatty liver formation. These changes partially contributed to the tight control the NF-κB and the MHCII signaling. Our analysis uncovers duck chromatin reorganization might be advantageous to maintain liver regenerative capacity and reduce adipose inflammation. These findings shed light on new strategies for NAFLD control.

Phytonanotherapy for the Treatment of Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD), previously known as nonalcoholic fatty liver disease, is a steatotic liver disease associated with metabolic syndrome (MetS), especially obesity, hypertension, diabetes, hyperlipidemia, and hypertriglyceridemia. MASLD in 43-44% of patients can progress to metabolic dysfunction-associated steatohepatitis (MASH), and 7-30% of these cases will progress to liver scarring (cirrhosis). To date, the mechanism of MASLD and its progression is not completely understood and there were no therapeutic strategies specifically tailored for MASLD/MASH until March 2024. The conventional antiobesity and antidiabetic pharmacological approaches used to reduce the progression of MASLD demonstrated favorable peripheral outcomes but insignificant effects on liver histology. Alternatively, phyto-synthesized metal-based nanoparticles (MNPs) are now being explored in the treatment of various liver diseases due to their unique bioactivities and reduced bystander effects. Although phytonanotherapy has not been explored in the clinical treatment of MASLD/MASH, MNPs such as gold NPs (AuNPs) and silver NPs (AgNPs) have been reported to improve metabolic processes by reducing blood glucose levels, body fat, and inflammation. Therefore, these actions suggest that MNPs can potentially be used in the treatment of MASLD/MASH and related metabolic diseases. Further studies are warranted to investigate the feasibility and efficacy of phytonanomedicine before clinical application.

Long non-coding RNAs as modulators and therapeutic targets in non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world, with epidemiological studies indicating a 25% prevalence. NAFLD is considered to be a progressive disease that progresses from simple hepatic steatosis to non-alcoholic steatohepatitis (NASH), then to liver fibrosis, and finally to cirrhosis or hepatocellular carcinoma (HCC). Existing research has mostly elucidated the etiology of NAFLD, yet its particular molecular processes remain uncertain. Long non-coding RNAs (LncRNAs) have been linked in a wide range of biological processes in recent years, with the introduction of microarray and high-throughput sequencing technologies, and previous studies have established their tight relationship with several stages of NAFLD development. Existing studies have shown that lncRNAs can regulate the signaling pathways related to hepatic lipid metabolism, NASH, NASH-related fibrosis and HCC. This review aims to provide a basic overview of NAFLD and lncRNAs, summarize and describe the mechanisms of lncRNAs action involved in the development of NAFLD, and provide an outlook on the future of lncRNAs-based therapy for NAFLD.

Association between endocrine-disrupting chemical mixtures and non-alcoholic fatty liver disease with metabolic syndrome as a mediator among adults: A population-based study in Korea

Endocrine-disrupting chemicals (EDCs) may play a role in non-alcoholic fatty liver disease (NAFLD); however, studies on the combined effects of EDC mixtures on NAFLD development are limited. Here, we explored the association between exposure to EDC mixtures and NAFLD and investigated the potential mediating role of metabolic syndrome (MetS). We included participants from the Korean National Environmental Health Survey Cycle 4 (2018-2020) and quantified the urinary concentrations of various EDCs-eight phthalate metabolites, three phenols, one antibacterial compound, four parabens, four polycyclic aromatic hydrocarbons, and one pyrethroid pesticide metabolite-as well as serum concentrations of five perfluorinated compounds (PFCs). NAFLD was defined as a hepatic steatosis index (HSI) ≥36 or a fatty liver index (FLI) ≥60. Weighted quantile sum (WQS) regression was employed to evaluate the associations between EDC mixtures and the risk of MetS or NAFLD. Causal mediation analysis was conducted to explore the potential mediating effect of MetS on the association between mixtures of EDCs and NAFLD risk. All estimates were adjusted for age, sex, educational level, physical activity, smoking status, involuntary smoking, and drinking habits. A total of 2942 adults were included in the analysis. Moderate-to-high positive correlations were identified between phthalate metabolites and PFCs. Higher WQS scores were associated with an elevated risk of MetS and NAFLD. The sex-stratified WQS regression model showed that the interactions between the WQS index and sex were significant for MetS and NAFLD. According to the causal mediation analysis, both the direct and indirect effects of EDC mixtures on NAFLD, with MetS as a mediator, were significant in females. Collectively, these findings highlight the need for interventions that could address both EDC mixture exposure and metabolic status to effectively reduce the risks associated with NAFLD and its related complications.

Gut microbiota in MAFLD: therapeutic and diagnostic implications

Metabolic dysfunction-associated fatty liver disease (MAFLD), formerly known as nonalcoholic fatty liver disease, is becoming a significant contributor to chronic liver disease globally, surpassing other etiologies, such as viral hepatitis. Prevention and early treatment strategies to curb its growing prevalence are urgently required. Recent evidence suggests that targeting the gut microbiota may help treat and alleviate disease progression in patients with MAFLD. This review aims to explore the complex relationship between MAFLD and the gut microbiota in relation to disease pathogenesis. Additionally, it delves into the therapeutic strategies targeting the gut microbiota, such as diet, exercise, antibiotics, probiotics, synbiotics, glucagon-like peptide-1 receptor agonists, and fecal microbiota transplantation, and discusses novel biomarkers, such as microbiota-derived testing and liquid biopsy, for their diagnostic and staging potential. Overall, the review emphasizes the urgent need for preventive and therapeutic strategies to address the devastating consequences of MAFLD at both individual and societal levels and recognizes that further exploration of the gut microbiota may open avenues for managing MAFLD effectively in the future.

Association between serum perfluoroalkyl substances concentrations and non-alcoholic fatty liver disease among Korean adults: a cross-sectional study using the National Environmental Health Survey cycle 4

Background

Perfluoroalkyl substances (PFAS) are widely used in industry and daily life due to their useful properties. They have a long half-life, accumulate in the body, and there is evidence that they are associated with biomarkers of lipid metabolism and liver damage. This may suggest non-alcoholic fatty liver disease (NAFLD) caused by PFAS. However, since there has been no study analyzing the relationship between PFAS and NAFLD in the entire population in Korea. We sought to confirm the relationship between serum PFAS concentration and NAFLD prevalence in Korean adults using the Korean National Environmental Health Survey (KoNEHS) cycle 4.

Methods

The study was conducted on 2,529 subjects in 2018-2019 among KoNEHS participants. For the diagnosis of NAFLD, the hepatic steatosis index (HSI) was used, and the geometric mean and concentration distribution of serum PFAS were presented. Logistic regression was performed to confirm the increase in the risk of NAFLD due to changes in PFAS concentration, and the odds ratio and 95% confidence interval (CI) were calculated.

Results

In both adjusted and unadjusted models, an increased odds ratio was observed with increasing serum concentrations of total PFAS and perfluorooctane sulfonate (PFOS) in the non-obese group. In the adjusted model, the odds ratios for serum total PFAS and PFOS were 6.401 (95% CI: 1.883-21.758) and 7.018 (95% CI: 2.688-18.319).

Conclusions

In this study, a higher risk of NAFLD based on HSI was associated with serum total PFAS, PFOS in non-obese group. Further research based on radiological or histological evidence for NAFLD diagnosis and long-term prospective studies are necessary. Accordingly, it is necessary to find ways to reduce exposure to PFAS in industry and daily life.

Development and validation of a novel non-invasive test for diagnosing nonalcoholic fatty liver disease in Chinese children

BACKGROUND

With the exploding prevalence of obesity, many children are at risk of developing nonalcoholic fatty liver disease. Using anthropometric and laboratory parameters, our study aimed to develop a model to quantitatively evaluate liver fat content (LFC) in children with obesity.

METHODS

A well-characterized cohort of 181 children between 5 and 16 years of age were recruited to the study in the Endocrinology Department as the derivation cohort. The external validation cohort comprised 77 children. The assessment of liver fat content was performed using proton magnetic resonance spectroscopy. Anthropometry and laboratory metrics were measured in all subjects. B-ultrasound examination was carried out in the external validation cohort. The Kruskal-Wallis test, Spearman bivariate correlation analyses, univariable linear regressions and multivariable linear regression were used to build the optimal predictive model.

RESULTS

The model was based on indicators including alanine aminotransferase, homeostasis model assessment of insulin resistance, triglycerides, waist circumference and Tanner stage. The adjusted R2 of the model was 0.589, which presented high sensitivity and specificity both in internal [sensitivity of 0.824, specificity of 0.900, area under curve (AUC) of 0.900 with a 95% confidence interval: 0.783-1.000] and external validation (sensitivity of 0.918 and specificity of 0.821, AUC of 0.901 with a 95% confidence interval: 0.818-0.984).

CONCLUSIONS

Our model based on five clinical indicators was simple, non-invasive, and inexpensive; it had high sensitivity and specificity in predicting LFC in children. Thus, it may be useful for identifying children with obesity who are at risk for developing nonalcoholic fatty liver disease.

The Many Faces of Metabolic Dysfunction-Associated Fatty Liver Disease Treatment: From the Mediterranean Diet to Fecal Microbiota Transplantation

The gastrointestinal tract is inhabited by the gut microbiota. The main phyla are Firmicutes and Bacteroidetes. In non-alcoholic fatty liver disease, now renamed metabolic dysfunction-associated fatty liver disease (MAFLD), an alteration in Firmicutes and Bacteroidetes abundance promotes its pathogenesis and evolution into non-alcoholic steatohepatitis, liver cirrhosis, and hepatocellular carcinoma. For this reason, early treatment is necessary to counteract its progression. The aim of the present narrative review is to evaluate the different therapeutic approaches to MAFLD. The most important treatment for MAFLD is lifestyle changes. In this regard, the Mediterranean diet could be considered the gold standard in the prevention and treatment of MAFLD. In contrast, a Western diet should be discouraged. Probiotics and fecal microbiota transplantation seem to be valid, safe, and effective alternatives for MAFLD treatment. However, more studies with a longer follow-up and with a larger cohort of patients are needed to underline the more effective approaches to contrasting MAFLD.

Lactiplantibacillus plantarum ZDY2013 Inhibits the Development of Non-Alcoholic Fatty Liver Disease by Regulating the Intestinal Microbiota and Modulating the PI3K/Akt Pathway

Non-alcoholic fatty liver disease (NAFLD) is a common chronic hepatic condition whose impact on human health is increasingly significant. The imbalance of the gut microbiome, linked to insulin resistance, heightened intestinal permeability, and pro-inflammatory reactions, may be the linchpin in the development of NAFLD. In our research, the impact of Lactiplantibacillus plantarum ZDY2013 administration for 12 weeks on gut microbiota dysbiosis induced by a high-fat, high-fructose, high-cholesterol (FHHC) diet in male C57BL/6n mice was investigated. Research results presented that the intervention of L. plantarum ZDY2013 in mice fed with the FHHC diet could restore their liver function and regulate oxidative stress. Compared to mice in the model group, the intervention of L. plantarum ZDY2013 significantly regulated the gut microbiota, inhibited the LPS/NF-κB pathway, and led to a lower level of colonic inflammation in the mice administered with L. plantarum ZDY2013. It also improved insulin resistance to regulate the PI3K/Akt pathway and lipid metabolism, thereby resulting in reduced fat accumulation in the liver. The above results suggest that the intervention of L. plantarum ZDY2013 can hinder the progression of diet-induced NAFLD by reducing inflammation to regulate the PI3K/Akt pathway and regulating gut microbiota disturbance.

Lead exposure exacerbates liver injury in high-fat diet-fed mice by disrupting the gut microbiota and related metabolites

Lead (Pb) is a widespread toxic endocrine disruptor that could cause liver damage and gut microbiota dysbiosis. However, the causal relationship and underlying mechanisms between the gut microbiota and Pb-induced liver injury are unclear. In this study, we investigated the metabolic toxicity caused by Pb exposure in normal chow (Chow) and high-fat diet (HFD) mice and confirmed the causal relationship by fecal microbial transplantation (FMT) and antibiotic cocktail experiments. The results showed that Pb exposure exacerbated HFD-induced hepatic lipid deposition, fibrosis, and inflammation, but it had no significant effect on Chow mice. Pb increased serum lipopolysaccharide (LPS) levels and induced intestinal inflammation and barrier damage by activating TLR4/NFκB/MLCK in HFD mice. Furthermore, Pb exposure disrupted the gut microbiota, reduced short-chain fatty acid (SCFA) concentrations and the colonic SCFA receptors, G protein-coupled receptor (GPR) 41/43/109A, in HFD mice. Additionally, Pb significantly inhibited the hepatic GPR109A-mediated adenosine 5'-monophosphate-activated protein kinase (AMPK) pathway, resulting in hepatic lipid accumulation. FMT from Pb-exposed HFD mice exacerbated liver damage, disturbed lipid metabolic pathways, impaired intestinal barriers, and altered the gut microbiota and metabolites in recipient mice. However, mice exposed to HFD + Pb and HFD mice had similar levels of these biomarkers in microbiota depleted by antibiotics. In conclusion, our study provides new insights into gut microbiota dysbiosis as a potential novel mechanism for human health related to liver function impairment caused by Pb exposure.

Molecular Insights of Nonalcoholic Fatty Liver Disease Pathogenesis

Nonalcoholic fatty liver disease (NAFLD) is now the most prevalent chronic liver disease. Many hepatic abnormalities are associated with NAFLD such as nonalcoholic steatohepatitis, progressive fibrosis, cirrhosis, and liver failure. Moreover, the pathogenesis of NAFLD has numerous etiologies and can be explained due to the existence of several of stimulus that act simultaneously on genetically susceptible patients. These stimuli include obesity, diabetes, and insulin resistance. In addition, identifying the role of gut microbiota on NAFLD progression has been illustrated. In this review, we clarified the several factors that lead to the development of NAFLD and identify those who are most at risk of developing liver end-stage disease. Highlighting the noninvasive diagnostic NAFLD markers could be helpful in the disease prevention and treatment approaches.

Single-cell transcriptome landscape of zebrafish liver reveals hepatocytes and immune cell interactions in understanding nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is becoming the most common chronic liver disease in the world. Immunity is the major contributing factor in NAFLD; however, the interaction of immune cells and hepatocytes in disease progression has not been fully elucidated. As a popular species for studying NAFLD, zebrafish, whose liver is a complex immune system mediated by immune cells and non-immune cells in maintaining immune tolerance and homeostasis. Understanding the cellular composition and immune environment of zebrafish liver is of great significance for its application in NAFLD. Here, we established a liver atlas that consists of 10 cell types using single-cell RNA sequencing (scRNA-seq). By examining the heterogeneity of hepatocytes and analyzing the expression of NAFLD-associated genes in the specific cluster, we provide a potential target cell model to study NAFLD. Additionally, our analysis identified two subtypes of distinct resident macrophages with inflammatory and non-inflammatory functions and characterized the successive stepwise development of T cell subclusters in the liver. Importantly, we uncovered the possible regulation of macrophages and T cells on target cells of fatty liver by analyzing the cellular interaction between hepatocytes and immune cells. Our data provide valuable information for an in-depth study of immune cells targeting hepatocytes to regulate the immune balance in NAFLD.

Assessment of endocrine disruptor impacts on lipid metabolism in a fatty acid-supplemented HepaRG human hepatic cell line

The incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing worldwide. This disease encompasses several stages, from steatosis to steatohepatitis and, eventually, to fibrosis and cirrhosis. Exposure to environmental contaminants is one of the risk factors and an increasing amount of evidence points to a role for endocrine disrupting compounds (EDCs). This study assesses the impact of selected EDCs on the formation of lipid droplets, the marker for steatosis in a hepatic model. The mechanisms underlying this effect are then explored. Ten compounds were selected according to their obesogenic properties: bisphenol A, F and S, butyl-paraben, cadmium chloride, p,p'-DDE, DBP, DEHP, PFOA and PFOS. Using a 2D or 3D model, HepaRG cells were exposed to the compounds with or without fatty acid supplementation. Then, the formation of lipid droplets was quantified by an automated fluorescence-based method. The expression of genes and proteins involved in lipid metabolism and the impact on cellular respiration was analyzed. The formation of lipid droplets, which is revealed or enhanced by oleic acid supplementation, was most effectively induced by p,p'-DDE and DEHP. Experiments employing either 2D or 3D culture conditions gave similar results. Both compounds induced the expression of PLIN2. p,p'-DDE also appears to act by decreasing in fatty acid oxidation. Some EDCs were able to induce the formation of lipid droplets, in HepaRG cells, an effect which was increased after supplementation of the cells with oleic acid. A full understanding of the mechanisms of these effects will require further investigation. The novel automated detection method described here may also be useful in the future as a regulatory test for EDC risk assessment.

A bibliometric analysis of macrophages associated with non-alcoholic fatty liver disease research from 2005 to 2023

Non-alcoholic fatty liver disease (NAFLD) is a prevalent chronic liver condition associated with the risk of progressing to decompensated cirrhosis and hepatocellular carcinoma. While macrophages play a crucial role in the development of NAFLD, their heterogeneity and plasticity allow them to undertake diverse roles in immune response, tissue repair, and maintaining tissue homeostasis. Thus, the exact involvement of macrophages in the onset and progression of NAFLD remains to be further explored. This study aims to employ bibliometric analysis to elucidate the role of macrophages in the pathogenesis of NAFLD, analyze research focal points in this domain, and speculate on future research trends. The literature search, conducted using the Web of Science Core Collection, encompassed articles and reviews related to macrophages and NAFLD published between 2005 and 2023. A bibliometric analysis of 1264 extracted publications was performed using VOSviewer 1.6.17 and Citespace 6.1. R2, evaluating parameters such as spatial and temporal distribution, authors, thematic categories, topic distribution, references, and keywords. The findings revealed a steady global increase in publications in this field, with the United States contributing the most followed by China. The University of California System produced the highest volume of publications, while the Journal of Hepatology had the highest impact factors among the top 10 publishing journals. Tacke Frank emerged as both the most prolific author and the most cited. Co-occurrence and burst analysis of keywords and references highlighted the hotspots in this research area, emphasizing the mechanisms of NAFLD pathogenesis, metabolic regulation, immune modulation, and oxidative stress. Maintaining hepatic homeostasis by liver macrophages and macrophage polarization were identified as trending research directions in this field. Based on the bibliometric analysis, continued attention toward NAFLD therapeutic research involving hepatic macrophages is anticipated. As the mechanisms underlying NAFLD pathogenesis are further elucidated, the development of more treatment approaches related to macrophage immunology and metabolic regulation may expand therapeutic options. This study offers valuable insights into the current state and future trends in the field, providing beneficial guidance to researchers aiming to make significant contributions.

Metabolic-associated fatty liver disease: a selective review of pathogenesis, diagnostic approaches, and therapeutic strategies

Background

Metabolic associated fatty liver disease (MAFLD) is a novel terminology introduced in 2020 to provide a more accurate description of fatty liver disease associated with metabolic dysfunction. It replaces the outdated term nonalcoholic fatty liver disease (NAFLD) and aims to improve diagnostic criteria and tailored treatment strategies for the disease. NAFLD, the most prevalent liver disease in western industrialized nations, has been steadily increasing in prevalence and is associated with serious complications such as cirrhosis and hepatocellular carcinoma. It is also linked to insulin resistance syndrome and cardiovascular diseases. However, current studies on NAFLD have limitations in meeting necessary histological endpoints.

Objective

This literature review aims to consolidate recent knowledge and discoveries concerning MAFLD, integrating the diverse aspects of the disease. Specifically, it focuses on analyzing the diagnostic criteria for MAFLD, differentiating it from NAFLD and alcoholic fatty liver disease (AFLD), and exploring the epidemiology, clinical manifestations, pathogenesis, and management approaches associated with MAFLD. The review also explores the associations between MAFLD and other conditions. It discusses the heightened mortality risk associated with MAFLD and its link to chronic kidney disease (CKD), showing that MAFLD exhibits enhanced diagnostic accuracy for identifying patients with CKD compared to NAFLD. The association between MAFLD and incident/prevalent CKD is supported by cohort studies and meta-analyses.

Conclusion

This literature review highlights the importance of MAFLD as a distinct terminology for fatty liver disease associated with metabolic dysfunction. The review provides insights into the diagnostic criteria, associations with CKD, and management approaches for MAFLD. Further research is needed to develop more accurate diagnostic tools for advanced fibrosis in MAFLD and to explore the underlying mechanisms linking MAFLD with other conditions. This review serves as a valuable resource for researchers and healthcare professionals seeking a comprehensive understanding of MAFLD.

Extracellular vesicle therapy for obesity-induced NAFLD: a comprehensive review of current evidence

Non-alcoholic fatty liver disease (NAFLD) as a chronic disease especially in Western countries, is still a tough question in the clinical therapy. With the rising prevalence of various chronic diseases, liver transplantation is expected to be the most common therapy after the next 10 years. However, there is still no approved drug for NAFLD, and targeted therapy for NAFLD is urgent. Exosomes as a kind of extracellular vesicle are cell-derived nanovesicles, which play an essential role in intercellular communication. Due to complex cell-cell interactions in the liver, exosomes as therapeutic drugs or drug delivery vesicles may be involved in physiological or pathological processes in NAFLD. Compared with other nanomaterials, exosomes as a cell-free therapy, are not dependent on cell number limitation, which means can be administered safely in high doses. Apart from this, exosomes with the advantages of being low-toxic, high stability, and low-immunological are chosen for targeted therapy for many diseases. In this review, firstly we introduced the extracellular vesicles, including the biogenesis, composition, isolation and characterization, and fundamental function of extracellular vesicles. And then we discussed the modification of extracellular vesicles, cargo packing, and artificial exosomes. Finally, the extracellular vesicles for the therapies of NAFLD are summarized. Moreover, we highlight therapeutic approaches using exosomes in the clinical treatment of NAFLD, which provide valuable insights into targeting NAFLD in the clinical setting.

Dietary glycine supplementation enhances glutathione availability in tissues of pigs with intrauterine growth restriction

This study tested the hypothesis that dietary supplementation with glycine enhances the synthesis and concentrations of glutathione (GSH, a major antioxidant) in tissues of pigs with intrauterine growth restriction (IUGR). At weaning (21 d of age), IUGR pigs and litter mates with normal birth weights (NBW) were assigned randomly to one of two groups, representing supplementation with 1% glycine or 1.19% l-alanine (isonitrogenous control) to a corn- and soybean meal-based diet. Blood and other tissues were obtained from the pigs within 1 wk after the feeding trial ended at 188 d of age to determine GSH, oxidized GSH (GSSG), and activities of GSH-metabolic enzymes. Results indicated that concentrations of GSH + GSSG or GSH in plasma, liver, and jejunum (P < 0.001) and concentrations of GSH in longissimus lumborum and gastrocnemius muscles (P < 0.05) were lower in IUGR pigs than in NBW pigs. In contrast, IUGR increased GSSG/GSH ratios (an indicator of oxidative stress) in plasma (P < 0.001), jejunum (P < 0.001), both muscles (P < 0.05), and pancreas (P = 0.001), while decreasing activities of γ-glutamylcysteine synthetase and GSH synthetase in liver (P < 0.001) and jejunum (P < 0.01); and GSH reductase in jejunum (P < 0.01), longissimus lumborum muscle (P < 0.01), gastrocnemius muscle (P < 0.05), and pancreas (P < 0.01). In addition, IUGR pigs had greater (P < 0.001) concentrations of thiobarbituric acid reactive substances (TBARS; an indicator of lipid peroxidation) in plasma, jejunum, muscles, and pancreas than NBW pigs. Compared with isonitrogenous controls, dietary glycine supplementation increased concentrations of GSH plus GSSG and GSH in plasma (P < 0.01), liver (P < 0.001), jejunum (P < 0.001), longissimus lumborum muscle (P = 0.001), and gastrocnemius muscle (P < 0.05); activities of GSH-synthetic enzymes in liver (P < 0.01) and jejunum (P < 0.05), while reducing GSSG/GSH ratios in plasma (P < 0.001), jejunum (P < 0.001), longissimus lumborum muscle (P < 0.001), gastrocnemius muscle (P = 0.01), pancreas (P < 0.05), and kidneys (P < 0.01). Concentrations of GSH plus GSSG, GSH, and GSSG/GSH ratios in kidneys were not affected (P > 0.05) by IUGR. Furthermore, glycine supplementation reduced (P < 0.001) TBARS concentrations in plasma, jejunum, muscles, and pancreas. Collectively, IUGR reduced GSH availability and induced oxidative stress in pig tissues, and these abnormalities were prevented by dietary glycine supplementation in a tissue-specific manner.

Repeated detection of non-alcoholic fatty liver disease increases the incidence risk of type 2 diabetes in young adults

AIM

This study aimed to investigate the effects of repeated detection of non-alcoholic fatty liver disease (NAFLD) on the incidence risk of type 2 diabetes in young adults.

MATERIALS AND METHODS

In this nationwide population-based observational study using data from the Korean National Health Insurance Service, approximately 1 125 015 young adults aged 20-39 years who underwent health screening four times between 2009 and 2013 were included. NAFLD was defined as a fatty liver index (FLI) of ≥60. Repeated detection of NAFLD scores was defined as the number of times the participants met the criteria for NAFLD (0-4). To account for the degree of repeated detection of NAFLD, weighted repeated NAFLD scores were scaled as a sum by assigning points (0 points for FLI <30, 1 point for 30 ≤ FLI < 60, and 2 points for FLI ≥60) ranging from 0 to 8 points.

RESULTS

The multivariable-adjusted hazard ratios of type 2 diabetes associated with repeated detection of NAFLD scores of 1, 2, 3 and 4 were 2.74 (95% confidence interval 2.57-2.921), 3.45 (3.221-3.694), 4.588 (4.303-4.892) and 6.126 (5.77-6.504), respectively. The incidence risk of type 2 diabetes increased significantly with repeated detection of the NAFLD score. In the analysis of the weighted repeated NAFLD score, the hazard ratios for the incidence of type 2 diabetes showed a significant continuous positive linear association with increasing scores.

CONCLUSIONS

Repeated detection of NAFLD influenced the incidence risk of type 2 diabetes in young adults, and a higher degree of repeated detection of NAFLD was independently associated with the risk of type 2 diabetes in young adults.

Taiwan Association for the Study of the Liver-Taiwan Society of Cardiology Taiwan position statement for the management of metabolic dysfunction- associated fatty liver disease and cardiovascular diseases

Metabolic dysfunction-associated fatty liver disease (MAFLD) is an increasingly common liver disease worldwide. MAFLD is diagnosed based on the presence of steatosis on images, histological findings, or serum marker levels as well as the presence of at least one of the three metabolic features: overweight/obesity, type 2 diabetes mellitus, and metabolic risk factors. MAFLD is not only a liver disease but also a factor contributing to or related to cardiovascular diseases (CVD), which is the major etiology responsible for morbidity and mortality in patients with MAFLD. Hence, understanding the association between MAFLD and CVD, surveillance and risk stratification of MAFLD in patients with CVD, and assessment of the current status of MAFLD management are urgent requirements for both hepatologists and cardiologists. This Taiwan position statement reviews the literature and provides suggestions regarding the epidemiology, etiology, risk factors, risk stratification, nonpharmacological interventions, and potential drug treatments of MAFLD, focusing on its association with CVD.

Cell-type specific role of autophagy in the liver and its implications in non-alcoholic fatty liver disease

Autophagy, a cellular degradative process, has emerged as a key regulator of cellular energy production and stress mitigation. Dysregulated autophagy is a common phenomenon observed in several human diseases, and its restoration offers curative advantage. Non-alcoholic fatty liver disease (NAFLD), more recently renamed metabolic dysfunction-associated steatotic liver disease, is a major metabolic liver disease affecting almost 30% of the world population. Unfortunately, NAFLD has no pharmacological therapies available to date. Autophagy regulates several hepatic processes including lipid metabolism, inflammation, cellular integrity and cellular plasticity in both parenchymal (hepatocytes) and non-parenchymal cells (Kupffer cells, hepatic stellate cells and sinusoidal endothelial cells) with a profound impact on NAFLD progression. Understanding cell type-specific autophagy in the liver is essential in order to develop targeted treatments for liver diseases such as NAFLD. Modulating autophagy in specific cell types can have varying effects on liver function and pathology, making it a promising area of research for liver-related disorders. This review aims to summarize our present understanding of cell-type specific effects of autophagy and their implications in developing autophagy centric therapies for NAFLD.

Decreased FXR Agonism in the Bile Acid Pool Is Associated with Impaired FXR Signaling in a Pig Model of Pediatric NAFLD

The objective of this study was to investigate whether the impairment of farnesoid X receptor (FXR)-fibroblast growth factor 19 (FGF19) signaling in juvenile pigs with non-alcoholic fatty liver disease (NAFLD) is associated with changes in the composition of the enterohepatic bile acid pool. Eighteen 15-day-old Iberian pigs, pair-housed in pens, were allocated to receive either a control (CON) or high-fructose, high-fat (HFF) diet. Animals were euthanized in week 10, and liver, blood, and distal ileum (DI) samples were collected. HFF-fed pigs developed NAFLD and had decreased FGF19 expression in the DI and lower FGF19 levels in the blood. Compared with the CON, the HFF diet increased the total cholic acid (CA) and the CA to chenodeoxycholic acid (CDCA) ratio in the liver, DI, and blood. CA and CDCA levels in the DI were negatively and positively correlated with ileal FGF19 expression, respectively, and blood levels of FGF19 decreased with an increasing ileal CA to CDCA ratio. Compared with the CON, the HFF diet increased the gene expression of hepatic 12-alpha-hydrolase, which catalyzes the synthesis of CA in the liver. Since CA species are weaker FXR ligands than CDCA, our results suggest that impairment of FXR-FGF19 signaling in NAFLD pigs is associated with a decrease in FXR agonism in the bile acid pool.

Arbutin alleviates fatty liver by inhibiting ferroptosis via FTO/SLC7A11 pathway

Non-alcoholic fatty liver disease (NAFLD) is a potentially serious disease that affects 30 % of the global population and poses a significant risk to human health. However, to date, no safe, effective and appropriate treatment modalities are available. In recent years, ferroptosis has emerged as a significant mode of cell death and has been found to play a key regulatory role in the development of NAFLD. In this study, we found that arbutin (ARB), a natural antioxidant derived from Arctostaphylos uva-ursi (L.), inhibits the onset of ferroptosis and ameliorates high-fat diet-induced NAFLD in vivo and in vitro. Using reverse docking, we identified the demethylase fat mass and obesity-related protein (FTO) as a potential target of ARB. Subsequent mechanistic studies revealed that ARB plays a role in controlling methylation of the SLC7A11 gene through inhibition of FTO. In addition, we demonstrated that SLC7A11 could alleviate the development of NAFLD in vivo and in vitro. Our findings identify the FTO/SLC7A11 axis as a potential therapeutic target for the treatment of NAFLD. Specifically, we show that ARB alleviates NAFLD by acting on the FTO/SLC7A11 pathway to inhibit ferroptosis.

Isoliquiritigenin in combination with visceral adipose tissue and related markers as a predictive tool for nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent form of chronic liver disease in the world. New non-invasive diagnostic tools are needed to promptly treat this disease and avoid its complications. This study aimed to find key metabolites and related variables that could be used to predict and diagnose NAFLD. Ninety-eight subjects with NAFLD and 45 controls from the Fatty Liver in Obesity (FLiO) Study (NCT03183193) were analyzed. NAFLD was diagnosed and graded by ultrasound and classified into two groups: 0 (controls) and ≥ 1 (NAFLD). Hepatic status was additionally assessed through magnetic resonance imaging (MRI), elastography, and determination of transaminases. Anthropometry, body composition (DXA), biochemical parameters, and lifestyle factors were evaluated as well. Non-targeted metabolomics of serum was performed with high-performance liquid chromatography coupled to time-of-flight mass spectrometry (HPLC-TOF-MS). Isoliquiritigenin (ISO) had the strongest association with NAFLD out of the determinant metabolites. Individuals with higher concentrations of ISO had healthier metabolic and hepatic status and were less likely to have NAFLD (OR 0.13). Receiver operating characteristic (ROC) curves demonstrated the predictive power of ISO in panel combination with other NAFLD and IR-related variables, such as visceral adipose tissue (VAT) (AUROC 0.972), adiponectin (AUROC 0.917), plasmatic glucose (AUROC 0.817), and CK18-M30 (AUROC 0.810). Individuals with lower levels of ISO have from 71 to 82% more risk of presenting NAFLD compared to individuals with higher levels. Metabolites such as ISO, in combination with visceral adipose tissue, IR, and related markers, constitute a potential non-invasive tool to predict and diagnose NAFLD.

Metabolic dysfunction: The silenced connection with fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) represents a global public health burden. Despite the increase in its prevalence, the disease has not received sufficient attention compared to the associated diseases such as diabetes mellitus and obesity. In 2020 it was proposed to rename NAFLD to metabolic dysfunction-associated fatty liver disease (MAFLD) in order to recognize the metabolic risk factors and the complex pathophysiological mechanisms associated with its development. Furthermore, along with the implementation of the proposed diagnostic criteria, the aim is to address the whole clinical spectrum of the disease, regardless of BMI and the presence of other hepatic comorbidities. As would it be expected with such a paradigm shift, differing viewpoints have emerged regarding the benefits and disadvantages of renaming fatty liver disease. The following review aims to describe the way to the MAFLD from a historical, pathophysiological and clinical perspective in order to highlight why MAFLD is the approach to follow.

Lactobacillus coryniformis subsp. torquens T3 alleviates non-alcoholic fatty liver disease via reconstruction of the gut microbiota and redox system

BACKGROUND

A high-fat diet (HFD) that induces obesity has become the most common type of diet worldwide, leading to serious global health issues. Obesity is associated with an increased risk of non-alcoholic fatty liver disease (NAFLD). Probiotic supplements have been shown to help alleviate obesity. The present study aimed to investigate the mechanism by which Lactobacillus coryniformis supsp. torquens T3 (T3L) alleviated NAFLD induced by HFD via reconstruction of the gut microbiota and redox system.

RESULTS

The results showed that, compared with the HFD group, T3L inhibited obesity and relieved fat accumulation in the liver of mice with NAFLD. In addition, T3L inhibited liver inflammation and oxidative stress injury in NAFLD mice by regulating the lipopolysaccharide (LPS) inflammatory pathway in the liver. Furthermore, T3L changed the composition of the intestinal flora, reduced the abundance of harmful bacteria in the intestinal tract, enhanced the mechanical function of the intestinal barrier, and increased the short-chain fatty acid contents, thus inhibiting the secondary metabolite LPS, which directly causes liver damage through the portal vein.

CONCLUSION

In summary, T3L ameliorated NAFLD induced by obesity through the liver-gut axis pathway, thus reducing oxidative stress and liver injury. © 2023 Society of Chemical Industry.

Gene Variants Implicated in Steatotic Liver Disease: Opportunities for Diagnostics and Therapeutics

Non-alcoholic fatty liver disease (NAFLD) describes a steatotic (or fatty) liver occurring as a consequence of a combination of metabolic, environmental, and genetic factors, in the absence of significant alcohol consumption and other liver diseases. NAFLD is a spectrum of conditions. Steatosis in the absence of inflammation is relatively benign, but the disease can progress into more severe forms like non-alcoholic steatohepatitis (NASH), liver cirrhosis, and hepatocellular carcinoma. NAFLD onset and progression are complex, as it is affected by many risk factors. The interaction between genetic predisposition and other factors partially explains the large variability of NAFLD phenotype and natural history. Numerous genes and variants have been identified through large-scale genome-wide association studies (GWAS) that are associated with NAFLD and one or more subtypes of the disease. Among them, the largest effect size and most consistent association have been patatin-like phospholipase domain-containing protein 3 (PNPLA3), transmembrane 6 superfamily member 2 (TM6SF2), and membrane-bound O-acyltransferase domain containing 7 (MBOAT7) genes. Extensive in vitro and in vivo studies have been conducted on these variants to validate these associations. The focus of this review is to highlight the genetics underpinning the molecular mechanisms driving the onset and progression of NAFLD and how they could potentially be used to improve genetic-based diagnostic testing of the disease and develop personalized, targeted therapeutics.

Mechanism for FXR to regulate bile acid and glycolipid metabolism to improve NAFLD

Nonalcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease, with liver metabolic disorders as major pathological changes, manifested as abnormal lipid accumulation, liver cell oxidative stress, etc., but its etiology is still unclear. The farnesol X receptor (FXR) is a major bile acid receptor in the "gut-liver axis", via which FXR regulates metabolism and affects the pathophysiological status of various substances through different pathways, thus contributing to the occurrence and development of NAFLD. Therefore, FXR has become a potential therapeutic target for NAFLD. This article reviews the relationship between FXR regulation of bile acid, glucose, and lipid metabolism through the "gut-liver axis" and the occurrence and development of NAFLD, to provide new insights and clues for further research about FXR-based pharmaceutical treatments.

Current insights into the interplay between gut microbiota-derived metabolites and metabolic-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a prevalent and challenging disease associated with a significant health and economic burden. MAFLD has been subjected to and widely investigated in many studies; however, the underlying pathogenesis and its progression have yet to understand fully. Furthermore, precise biomarkers for diagnosing and specific drugs for treatment are yet to be discovered. Increasing evidence has proven gut microbiota as the neglected endocrine organ that regulates homeostasis and immune response. Targeting gut microbiota is an essential strategy for metabolic diseases, including MAFLD. Gut microbiota in the gut-liver axis is connected through tight bidirectional links through the biliary tract, portal vein, and systemic circulation, producing gut microbiota metabolites. This review focuses on the specific correlation between gut microbiota metabolites and MAFLD. Gut microbiota metabolites are biologically active in the host and, through subsequent changes and biological activities, provide implications for MAFLD. Based on the review studies, gut-liver axis related-metabolites including short-chain fatty acids, bile acids (BAs), lipopolysaccharide, choline and its metabolites, indole and its derivates, branched-chain amino acids, and methionine cycle derivates was associated with MAFLD and could be promising MAFLD diagnosis biomarkers, as well as the targets for MAFLD new drug discovery.

Urolithin C reveals anti-NAFLD potential via AMPK-ferroptosis axis and modulating gut microbiota

The pharmacology of urolithin C (UroC) on non-alcoholic fatty liver disease (NAFLD) is largely undetermined. We sought to investigate the potential for NAFLD improvement by administration of UroC and the underlying mechanisms. We verified the therapeutic effect of UroC on choline-deficient amino acid-defined high fat diet (CDAHFD) induced NAFLD mice via evaluating NAFLD activity score (NAS), AST, ALT, hepatic phosphorylated AMPK, and 4-hydroxynonenal. Oleic acid-induced AML12 cell was appraised by oil red staining and western blotting to explore the effect and mechanism of UroC in vitro. Transcriptional regulation of UroC was explored by liver RNA sequencing, gut microbiota composition was explored by 16SrRNA sequencing, and colorectal tight junctional proteins were detected by western blotting and immunohistochemistry. The detrimental effects of CDAHFD included the increased liver index, AST, ALT, hepatic 4-hydroxynonenal, impaired intestinal mucosal barrier, and most importantly, pathological damage in liver. Oral administration of UroC largely protected against these harmful alterations. Remarkably, both RNA sequencing and western blotting results indicated an activation in hepatic AMPK signaling pathway which was thought to inhibit ferroptosis response to UroC in vivo, while no change were found in AMPK-ferroptosis axis response to UroC in oleic acid-induced AML12 cells, hinted an indispensable linkage between UroC and hepatic AMPK, presumably the gut-liver axis. Furthermore, UroC could neither alleviate lipid deposition nor inhibit ferroptosis in vitro. The 16SrRNA showed UroC partially counteracted the dysbiosis induced by CDAHFD. Specifically, UroC reversed the elevated proportion of Firmicutes/Bacteroidota and enhanced the level of Parabacteroides goldsteinii and Lactobacillus vaginalis, which played a beneficial role in metabolic disorders. Oral administration of Urolithin C protected against the detrimental impact of CDAHFD via regulating AMPK-ferroptosis axis, maintaining intestinal mucosal barrier and counteracting gut dysbiosis.

The emerging significance of mitochondrial targeted strategies in NAFLD treatment

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease worldwide, ranging from liver steatosis to nonalcoholic steatohepatitis, which ultimately progresses to fibrosis, cirrhosis, and hepatocellular carcinoma. Individuals with NAFLD have a higher risk of developing cardiovascular and extrahepatic cancers. Despite the great progress being made in understanding the pathogenesis and the introduction of new pharmacological targets for NAFLD, no drug or intervention has been accepted for its management. Recent evidence suggests that NAFLD may be a mitochondrial disease, as mitochondrial dysfunction is involved in the pathological processes that lead to NAFLD. In this review, we describe the recent advances in our understanding of the mechanisms associated with mitochondrial dysfunction in NAFLD progression. Moreover, we discuss recent advances in the efficacy of mitochondria-targeted compounds (e.g., Mito-Q, MitoVit-E, MitoTEMPO, SS-31, mitochondrial uncouplers, and mitochondrial pyruvate carrier inhibitors) for treating NAFLD. Furthermore, we present some medications currently being tested in clinical trials for NAFLD treatment, such as exercise, mesenchymal stem cells, bile acids and their analogs, and antidiabetic drugs, with a focus on their efficacy in improving mitochondrial function. Based on this evidence, further investigations into the development of mitochondria-based agents may provide new and promising alternatives for NAFLD management.

Coagulation Dysfunctions in Non-Alcoholic Fatty Liver Disease-Oxidative Stress and Inflammation Relevance

Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver diseases. Its incidence is progressively rising and it is possibly becoming a worldwide epidemic. NAFLD encompasses a spectrum of diseases accounting for the chronic accumulation of fat within the hepatocytes due to various causes, excluding excessive alcohol consumption. In this study, we aimed to focus on finding evidence regarding the implications of oxidative stress and inflammatory processes that form the multifaceted pathophysiological tableau in relation to thrombotic events that co-occur in NAFLD and associated chronic liver diseases. Recent evidence on the pathophysiology of NAFLD suggests that a complex pattern of multidirectional components, such as prooxidative, proinflammatory, and prothrombotic components, better explains the multiple factors that promote the mechanisms underlying the fatty acid excess and subsequent processes. As there is extensive evidence on the multi-component nature of NAFLD pathophysiology, further studies could address the complex interactions that underlie the development and progression of the disease. Therefore, this study aimed to describe possible pathophysiological mechanisms connecting the molecular impairments with the various clinical manifestations, focusing especially on the interactions among oxidative stress, inflammation, and coagulation dysfunctions. Thus, we described the possible bidirectional modulation among coagulation homeostasis, oxidative stress, and inflammation that occurs in the various stages of NAFLD.

Ufmylation on UFBP1 alleviates non-alcoholic fatty liver disease by modulating hepatic endoplasmic reticulum stress

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease characterized by lipid accumulation and endoplasmic reticulum (ER) stress, while effective therapies targeting the specific characteristics of NAFLD are limited. Ufmylation is a newly found post-translational modification process that involves the attachment of the Ubiquitin-fold modifier 1 (UFM1) protein to its substrates via ufmylation modification system. Ufmylation regulates ER stress via modifying UFM1 binding protein 1 (UFBP1), suggesting a potential role for ufmylation in NAFLD pathogenesis. However, the precise role of ufmylation in NAFLD remains unclear. Herein, we aim to elucidate the impact of ufmylation on UFBP1 in NAFLD and explore the underlying mechanisms involved. We observed increased expression of UFM1-conjugated proteins and ufmylation modification system components in livers with steatosis derived from NAFLD patients and NAFLD models. Upregulation of ufmylation on hepatic proteins appeared to be an adaptive response to hepatic ER stress in NAFLD. In vitro, knocking down UFBP1 resulted in increased lipid accumulation and lipogenesis in hepatocytes treated with free fatty acids (FFA), which could be rescued by wild-type UFBP1 (WT UFBP1) but not by a mutant form of UFBP1 lacking the main ufmylation site lys267 (UFBP1 K267R). In vivo, ufmylation on UFBP1 ameliorated obesity, hepatic steatosis, hepatic lipogenesis, dyslipidemia, insulin resistance and liver damage in mice with NAFLD induced by a high fat diet (HFD). We also demonstrated that the downregulation of UFBP1 induced ER stress, whereas the reintroduction or overexpression of UFBP1 alleviated ER stress in a manner dependent on ufmylation in NAFLD. This mechanism could be responsible for the amelioration of aberrant hepatic lipogenesis and insulin resistance in NAFLD. Our data reveal a protective role of ufmylation on UFBP1 against NAFLD and offer a specific target for NAFLD treatment.

The Lasting Effects of COVID-19 on the Progression of Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD)

It is estimated that around 30% of the population living in Western countries has metabolic dysfunction-associated steatotic liver disease (MASLD), a spectrum of pathology (not attributed to alcohol/substance intake) initiated by steatosis and progression toward inflammation and irreversible fibrosis metabolic dysfunction-associated steatohepatitis (MASH). With inflammation being a key component of the transition to MASH, it raises the question of whether the ongoing COVID-19 pandemic, which has notoriously induced hyperinflammatory states, may influence the progression of MASLD. Specifically, it remains unclear if the potential chronic sequelae of COVID-19 in patients who recovered from it may increase the predisposition for MASH. Since MASH maintains a high risk for hepatocellular carcinoma, liver failure, and the need for a liver transplant, the potential additive effects of COVID-19 could prove critical to study. Thus, the objective of this study was to conduct a literature review to examine if COVID-19 could have chronic sequelae that affect the progression of MASLD pathogenesis. It was hypothesized that severe cases of COVID-19 could induce systemic inflammation, metabolic changes, and lasting gut microbiome alterations that lead to inflammatory and fibrotic changes in the liver, similar to those seen in MASH. A scoping review of the literature was conducted utilizing the PubMed database. Studies that examined hepatobiliary pathology, gut microbiome, systemic inflammation, metabolic changes, drug-induced liver injury (DILI), and hypoxia seen in COVID-19 were included. Human studies of adult cohorts, animal models, and in vitro experiments were included. Genetic components of MASLD were not examined. Exclusion criteria also encompassed any studies not referencing the hepatobiliary, gastrointestinal tract, portal system, or systemic circulation. Findings indicated a frequent trend of elevated liver enzymes, mild steatosis, Kupffer cell hyperplasia, and hepatobiliary congestion. It was found that direct cytopathic effects on hepatocytes were unlikely, but the direct viral insult of cholangiocytes was a potential complication. High serum levels of IL-1, TNF-a, and MCP-1, in COVID-19 were found as potential risk factors for MASH development. Hypoxia, altered lipid metabolism, and iatrogenic DILI were also proposed as potential precipitators of MASH development. Notably, lasting changes in gut microbiome were also frequently observed and correlated closely with those seen in MASH.

Protective effect of phytoestrogens on nonalcoholic fatty liver disease in postmenopausal women

Non-alcoholic fatty liver disease (NAFLD) is a progressive metabolic disease characterized by hepatic steatosis, inflammation, and fibrosis that seriously endangers global public health. Epidemiological studies have shown that the incidence of non-alcoholic fatty liver disease in postmenopausal women has significantly increased. Studies have shown that estrogen deficiency is the main reason for this situation, and supplementing estrogen has become a new direction for preventing the occurrence of postmenopausal fatty liver. However, although classical estrogen replacement therapy can reduce the incidence of postmenopausal NAFLD, it has the risk of increasing stroke and cardiovascular diseases, so it is not suitable for the treatment of postmenopausal NAFLD. More and more recent studies have provided evidence that phytoestrogens are a promising method for the treatment of postmenopausal NAFLD. However, the mechanism of phytoestrogens in preventing and treating postmenopausal NAFLD is still unclear. This paper summarizes the clinical and basic research evidence of phytoestrogens and reviews the potential therapeutic effects of phytoestrogens in postmenopausal NAFLD from six angles: enhancing lipid metabolism in liver and adipose tissue, enhancing glucose metabolism, reducing oxidative stress, reducing the inflammatory response, regulating intestinal flora, and blocking liver fibrosis (Graphical Abstract).

Polysaccharides: The Potential Prebiotics for Metabolic Associated Fatty Liver Disease (MAFLD)

Metabolic (dysfunction) associated fatty liver disease (MAFLD) is recognized as the most prevalent chronic liver disease globally. However, its pathogenesis remains incompletely understood. Recent advancements in the gut-liver axis offer novel insights into the development of MAFLD. Polysaccharides, primarily derived from fungal and algal sources, abundantly exist in the human diet and exert beneficial effects on glycometabolism, lipid metabolism, inflammation, immune modulation, oxidative stress, and the release of MAFLD. Numerous studies have demonstrated that these bioactivities of polysaccharides are associated with their prebiotic properties, including the ability to modulate the gut microbiome profile, maintain gut barrier integrity, regulate metabolites produced by gut microbiota such as lipopolysaccharide (LPS), short-chain fatty acids (SCFAs), and bile acids (BAs), and contribute to intestinal homeostasis. This narrative review aims to present a comprehensive summary of the current understanding of the protective effects of polysaccharides on MAFLD through their interactions with the gut microbiota and its metabolites. Specifically, we highlight the potential molecular mechanisms underlying the prebiotic effects of polysaccharides, which may give new avenues for the prevention and treatment of MAFLD.

Pharmacological Prevention of Ectopic Erythrophagocytosis by Cilostazol Mitigates Ferroptosis in NASH

Hepatic iron overload (HIO) is a hallmark of nonalcoholic fatty liver disease (NAFLD) with a poor prognosis. Recently, the role of hepatic erythrophagocytosis in NAFLD is emerging as a cause of HIO. We undertook various assays using human NAFLD patient pathology samples and an in vivo nonalcoholic steatohepatitis (NASH) mouse model named STAMTM. To make the in vitro conditions comparable to those of the in vivo NASH model, red blood cells (RBCs) and platelets were suspended and subjected to metabolic and inflammatory stresses. An insert-coculture system, in which activated THP-1 cells and RBCs are separated from HepG2 cells by a porous membrane, was also employed. Through various analyses in this study, the effect of cilostazol was examined. The NAFLD activity score, including steatosis, ballooning degeneration, inflammation, and fibrosis, was increased in STAMTM mice. Importantly, hemolysis occurred in the serum of STAMTM mice. Although cilostazol did not improve lipid or glucose profiles, it ameliorated hepatic steatosis and inflammation in STAMTM mice. Platelets (PLTs) played an important role in increasing erythrophagocytosis in the NASH liver. Upregulated erythrophagocytosis drives cells into ferroptosis, resulting in liver cell death. Cilostazol inhibited the augmentation of PLT and RBC accumulation. Cilostazol prevented the PLT-induced increase in ectopic erythrophagocytosis in in vivo and in vitro NASH models. Cilostazol attenuated ferroptosis of hepatocytes and phagocytosis of RBCs by THP-1 cells. Augmentation of hepatic erythrophagocytosis by activated platelets in NASH exacerbates HIO. Cilostazol prevents ectopic erythrophagocytosis, mitigating HIO-mediated ferroptosis in NASH models.

Genetic Predictors of Comorbid Course of COVID-19 and MAFLD: A Comprehensive Analysis

Metabolic-associated fatty liver disease (MAFLD) and its potential impact on the severity of COVID-19 have gained significant attention during the pandemic. This review aimed to explore the genetic determinants associated with MAFLD, previously recognized as non-alcoholic fatty liver disease (NAFLD), and their potential influence on COVID-19 outcomes. Various genetic polymorphisms, including PNPLA3 (rs738409), GCKR (rs780094), TM6SF2 (rs58542926), and LYPLAL1 (rs12137855), have been investigated in relation to MAFLD susceptibility and progression. Genome-wide association studies and meta-analyses have revealed associations between these genetic variants and MAFLD risk, as well as their effects on lipid metabolism, glucose regulation, and liver function. Furthermore, emerging evidence suggests a possible connection between these MAFLD-associated polymorphisms and the severity of COVID-19. Studies exploring the association between indicated genetic variants and COVID-19 outcomes have shown conflicting results. Some studies observed a potential protective effect of certain variants against severe COVID-19, while others reported no significant associations. This review highlights the importance of understanding the genetic determinants of MAFLD and its potential implications for COVID-19 outcomes. Further research is needed to elucidate the precise mechanisms linking these genetic variants to disease severity and to develop gene profiling tools for the early prediction of COVID-19 outcomes. If confirmed as determinants of disease severity, these genetic polymorphisms could aid in the identification of high-risk individuals and in improving the management of COVID-19.

New murine model of alcoholic hepatitis in obesity-induced metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) and alcoholic hepatitis (AH) are among the most prevalent liver diseases worldwide, and their coexistence is common in clinical practice. However, currently established models of MAFLD-AH coexistence do not fully replicate their pathological characteristics and require sophisticated experimental techniques. Therefore, we aimed to develop an easily replicable model that mimics obesity-induced MAFLD-AH in patients. Our goal was to establish a murine model that replicates MAFLD and AH coexistence, resulting in significant liver injury and inflammation. To this end, we administered a single ethanol gavage dose to ob/ob mice on a chow diet. The administration of a single dose of ethanol led to elevated serum transaminase levels, increased liver steatosis, and apoptosis in ob/ob mice. Furthermore, ethanol binge caused a significant increase in oxidative stress in ob/ob mice, as measured via 4-hydroxynonenal. Importantly, the single dose of ethanol also markedly exacerbated liver neutrophil infiltration and upregulated the hepatic mRNA expression of several chemokines and neutrophil-related proteins, including Cxcl1, Cxcl2, and Lcn2. Whole-liver transcriptomic analysis revealed that ethanol-induced changes in gene expression profile shared similar features with AH and MAFLD. In ob/ob mice, a single dose of ethanol binge caused significant liver injury and neutrophil infiltration. This easy-to-replicate murine model successfully mimics the pathological and clinical features of patients with coexisting MAFLD and AH and closely resembles the transcriptional regulation seen in human disease.

Wnt/beta-catenin signaling and its modulators in nonalcoholic fatty liver diseases

Nonalcoholic fatty liver disease (NAFLD) is a global health concern associated with significant morbidity and mortality. NAFLD is a spectrum of diseases originating from simple steatosis, progressing through nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis that may lead to hepatocellular carcinoma (HCC). The pathogenesis of NAFLD is mediated by the triglyceride accumulation followed by proinflammatory cytokines expression leading to inflammation, oxidative stress, and mitochondrial dysfunction denoted as "two-hit hypothesis", advancing with a "third hit" of insufficient hepatocyte proliferation, leading to the increase in hepatic progenitor cells contributing to fibrosis and HCC. Wnt/β-catenin signaling is responsible for normal liver development, regeneration, hepatic metabolic zonation, ammonia and drug detoxification, hepatobiliary development, etc., maintaining the overall liver homeostasis. The key regulators of canonical Wnt signaling such as LRP6, Wnt1, Wnt3a, β-catenin, GSK-3β, and APC are abnormally regulated in NAFLD. Many experimental studies have shown the aberrated Wnt/β-catenin signaling during the NAFLD progression and NASH to hepatic fibrosis and HCC. Therefore, in this review, we have emphasized the role of Wnt/β-catenin signaling and its modulators that can potentially aid in the inhibition of NAFLD.

The Pleiotropic Face of CREB Family Transcription Factors

cAMP responsive element-binding protein (CREB) is one of the most intensively studied phosphorylation-dependent transcription factors that provide evolutionarily conserved mechanisms of differential gene expression in vertebrates and invertebrates. Many cellular protein kinases that function downstream of distinct cell surface receptors are responsible for the activation of CREB. Upon functional dimerization of the activated CREB to cis-acting cAMP responsive elements within the promoters of target genes, it facilitates signal-dependent gene expression. From the discovery of CREB, which is ubiquitously expressed, it has been proven to be involved in a variety of cellular processes that include cell proliferation, adaptation, survival, differentiation, and physiology, through the control of target gene expression. In this review, we highlight the essential roles of CREB proteins in the nervous system, the immune system, cancer development, hepatic physiology, and cardiovascular function and further discuss a wide range of CREB-associated diseases and molecular mechanisms underlying the pathogenesis of these diseases.

High-cholesterol diet in combination with hydroxypropyl-beta-cyclodextrin induces NASH-like disorders in the liver of rats

Non-alcoholic fatty liver disease (NAFLD) is a general term for fatty liver disease not caused by viruses or alcohol. Fibrotic hepatitis, cirrhosis, and hepatocellular carcinoma can develop. The recent increase in NAFLD incidence worldwide has stimulated drug development efforts. However, there is still no approved treatment. This may be due in part to the fact that non-alcoholic steatohepatitis (NASH) pathogenesis is very complex, and its mechanisms are not well understood. Studies with animals are very important for understanding the pathogenesis. Due to the close association between the establishment of human NASH pathology and metabolic syndrome, several animal models have been reported, especially in the context of overnutrition. In this study, we investigated the induction of NASH-like pathology by enhancing cholesterol absorption through treatment with hydroxypropyl-beta-cyclodextrin (CDX). Female Sprague-Dawley rats were fed a normal diet with normal water (control group); a high-fat (60 kcal%), cholesterol (1.25 %), and cholic acid (0.5 %) diet with normal water (HFCC group); or HFCC diet with 2 % CDX water (HFCC+CDX group) for 16 weeks. Compared to the control group, the HFCC and HFCC+CDX groups showed increased blood levels of total cholesterol, aspartate aminotransferase, and alanine aminotransferase. At autopsy, parameters related to hepatic lipid synthesis, oxidative stress, inflammation, and fibrosis were elevated, suggesting the development of NAFLD/NASH. Elevated levels of endoplasmic reticulum stress-related genes were evident in the HFCC+CDX group. In the novel rat model, excessive cholesterol intake and accelerated absorption contributed to NAFLD/NASH pathogenesis.

Which obesity index is the most useful marker for predicting hepatic steatosis in children and adolescents with obesity? A cross-sectional study using quantitative magnetic resonance imaging

INTRODUCTION

We aimed to evaluate the relationships between hepatic steatosis and various indices of obesity, and to identify the most useful index for the prediction of hepatic steatosis in children and adolescents with obesity.

METHODS

A total of 226 children and adolescents with a mean body mass index (BMI) z-score of 2.65 and a mean age of 11.4 years were subjected to anthropometric and body composition measurements, laboratory testing, abdominal fat mass assessment, and hepatic fat accumulation by magnetic resonance imaging-derived proton density fat fraction (MRI-PDFF). The participants were divided into quartiles according to the severity of their hepatic steatosis, and the presence of hepatic steatosis was defined using an MRI-PDFF ≥ 5%.

RESULTS

The multivariate ordinal regression analysis showed that the severity of hepatic steatosis was positively associated with BMI, waist circumference, waist-to-hip ratio, waist-to-height ratio, fat mass, fat-free mass, visceral adiposity, and abdominal subcutaneous adiposity. Higher activities of liver enzymes and higher concentrations of triglyceride, C-reactive protein, fasting insulin, and leptin were associated with more severe hepatic steatosis, whereas high-density lipoprotein-cholesterol and adiponectin were negatively associated with hepatic steatosis. The indices of obesity with areas under the receiver operating characteristic curves (AUCs) > 0.8 for the prediction of hepatic steatosis were liver enzymes, visceral adipose tissue area, waist-to-hip ratio, and waist-to-height ratio.

CONCLUSION

The severity of hepatic steatosis significantly correlated with various indices of obesity and cardiometabolic markers in children and adolescents with obesity. The indices of abdominal obesity would be the most useful for the prediction of hepatic steatosis.

The challenging role of micro-RNAs in non-alcoholic fatty liver disease in children with obesity: is it time for a new era?

INTRODUCTION

As the pediatric obesity epidemic, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in childhood. Pediatric NAFLD pathophysiology is tangled and still unclear, but insulin resistance (IR), genetics, epigenetics, oxidative stress, and inflammation act as key players. Due to the increased cardiometabolic risk of these patients, several biomarkers have been proposed for early NAFLD identification, but their clinical utility is poor. Recently, hepatic dysregulation of microRNAs (miRNAs) has been linked to metabolic dysfunction, which in turn implied in NAFLD development. Evidence on the intriguing role of miRNAs in NAFLD pathogenesis has emerging especially in at-risk children such as those with obesity. However, pediatric evidence supporting their potential use as early noninvasive NAFLD tools is still limited but promising.

AREAS COVERED

We provided an overview on the emerging role of miRNAs in pediatric NAFLD by addressing some issues regarding their pathophysiological link with the metabolic milieu and their role as reliable NAFLD markers in children with obesity.

EXPERT OPINION

Strong evidence supports a potential role of miRNAs as early biomarkers of NAFLD in children with obesity. They might represent a valid diagnostic and targeted therapeutic tool due to its close pathogenic link with the metabolic milieu.

Atractylodin alleviates nonalcoholic fatty liver disease by regulating Nrf2-mediated ferroptosis

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. Oxidative stress is one of the main inducers of NAFLD. Atractylodin (ART), a major active ingredient of Atractylodes lancea, possesses potential antioxidant and anti-inflammatory activity in many types of disease. In the current study, the underlying mechanism by which ART alleviates the progression of NAFLD was explored. The function of ART in facilitating NAFLD was investigated in vitro and in vivo. Functionally, ART attenuated high-fat diet (HFD)-induced NAFLD in mice and palmitic acid (PA)-induced oxidative stress in HepG2 cells. Furthermore, our data verified that ART attenuated HFD-induced NAFLD by inhibiting ferroptosis of hepatocyte cells, as evidenced by decreased Fe2+ concentration, reactive oxygen species (ROS) level, malondialdehyde (MDA) content, and increased glutathione (GSH) content. The protective effect of ART on the cell viability of hepatocytes was blocked by a specific ferroptosis inhibitor (ferrostatin-1). Mechanistically, ART treatment promoted the translocation of nuclear factor erythroid 2-related Factor 2 (NFE2L2/NRF2) and thus increased glutathione peroxidase 4 (GPX4), ferritin heavy chain 1 (FTH1), and solute carrier family 7 member 11 (SLC7A11) expression. Taken together, ART alleviates NAFLD by regulating Nrf2-mediated ferroptosis.

Pachymic acid modulates sirtuin 6 activity to alleviate lipid metabolism disorders

Pachymic acid (Pac), a major bioactive constituent of Poria cocos, is an antioxidant that inhibits triglyceride (TG) accumulation. To the best of our knowledge, the present study investigated for the first time whether Pac activated sirtuin 6 (SIRT6) signaling to alleviate oleic acid (OA)-palmitic acid (PA)-induced lipid metabolism disorders in mouse primary hepatocytes (MPHs). In the present study, MPHs challenged with Pac were used to test the effects of Pac on intracellular lipid metabolism. Molecular docking studies were performed to explore the potential targets of Pac in defending against lipid deposition. MPHs isolated from liver-specific SIRT6-deficient mice were subjected to OA + PA incubation and treated with Pac to determine the function and detailed mechanism. It was revealed that Pac activated SIRT6 by increasing its expression and deacetylase activity. Pa prevented OA + PA-induced lipid deposition in MPHs in a dose-dependent manner. Pac (50 µM) administration significantly reduced TG accumulation and increased fatty acid oxidation rate in OA + PA-incubated MPHs. Meanwhile, as per the results of molecular docking and relative mRNA levels, Pac activated SIRT6 and increased SIRT6 deacetylation levels. Furthermore, SIRT6 deletions in MPHs abolished the protective effects of Pac against OA + PA-induced hepatocyte lipid metabolism disorders. The present study demonstrated that Pac alleviates OA + PA-induced hepatocyte lipid metabolism disorders by activating SIRT6 signaling. Overall, SIRT6 signaling increases oxidative stress burden and promotes hepatocyte lipolysis.

Statins on nonalcoholic fatty liver disease: A systematic review and meta-analysis of 14 RCTs

BACKGROUND

The prevalence of nonalcoholic fatty liver disease (NAFLD) is rising rapidly in the world. Our aim is to investigate the efficacy and safety of statins in the treatment of NAFLD.

METHODS

This study was conducted by searching The National Library of Medicine, Cochrane Library, China National Knowledge Infrastructure, Web of Science, and Wanfang Data Knowledge Service Platform databases. Literature data are expressed as mean difference (MD) and 95% confidence intervals (CIs) or relative risk and 95% CI. For I2 > 50% trials, random effect model is used for statistical analysis, otherwise fixed effect model is used.

RESULTS

Fourteen studies are selected for this meta-analysis, which includes totally 534 patients in the treatment group and 527 patients in the control group. As a result, 5 studies show that the total effective rate of the treatment group is 17% higher than that of the control group (Z = 2.11, relative risk = 1.17, 95% CI: [1.01-1.35]). Twelve studies show that alanine aminotransferase levels of the experimental group are lower than that of the control group (Z = 2.63, P = .009, MD = -5.53, 95% CI: [-9.64 to -1.41]). Eleven studies show that aspartate transaminase levels of the experimental group are lower than that of the control group (Z = 2.01, P = .04, MD = -3.43, 95% CI: [-6.77 to -0.08]). Six studies show that alkaline phosphatase levels of the experimental group are lower than that of the control group (Z = 0.79, P = .43, MD = -3.46, 95% CI: [-12.08 to 5.16]). Eight studies show that gamma-glutamyl transpeptidase levels of the experimental group are lower than that of the control group (Z = 2.04, P = .04, MD = -4.05, 95% CI: [-7.96 to -0.15]). Thirteen studies show that triglyceride levels of the experimental group are lower than that of the control group (Z = 4.15, P < .0001, MD = -0.94, 95% CI: [-1.39 to -0.50]). Eleven studies show that the total cholesterol levels of the experimental group are lower than that of the control group (Z = 5.42, P < .00001, MD = -1.51, 95% CI: [-2.05 to -0.96]). Seven studies show that low-density lipoprotein-cholesterol levels of the experimental group are lower than that of the control group (Z = 5.00, P < .00001, MD = -0.85, 95% CI: [-1.18 to -0.52]).

CONCLUSION

Statins can significantly reduce liver biochemical indicators in patients with NAFLD.

Opportunities and considerations for studying liver disease with microphysiological systems on a chip

Advances in microsystem engineering have enabled the development of highly controlled models of the liver that better recapitulate the unique in vivo biological conditions. In just a few short years, substantial progress has been made in creating complex mono- and multi-cellular models that mimic key metabolic, structural, and oxygen gradients crucial for liver function. Here we review: 1) the state-of-the-art in liver-centric microphysiological systems and 2) the array of liver diseases and pressing biological and therapeutic challenges which could be investigated with these systems. The engineering community has unique opportunities to innovate with new liver-on-a-chip devices and partner with biomedical researchers to usher in a new era of understanding of the molecular and cellular contributors to liver diseases and identify and test rational therapeutic modalities.