How does hepatic lipid accumulation lead to lipotoxicity in non-alcoholic fatty liver disease?

Inhibition of histone methyltransferase G9a aggravates phenotypic severity of hepatic lipotoxicity in non-alcoholic steatohepatitis (NASH)

Lipotoxicity is a key pathological feature in the development of non-alcoholic steatohepatitis (NASH), which is characterized by liver injury, inflammation, and fibrosis. Although lipotoxicity has been shown to induce transcriptomic alterations in liver cells, the specific role of epigenetic regulators in NASH remains elusive. In this study, we demonstrate that pharmacological inhibition of histone methyltransferase G9a significantly worsens NASH progression in mice, as evidenced by increased hepatic cell death, inflammation, and fibrosis. Additionally, at a cellular level both genetic and pharmacological inhibition of G9a in HepG2 cells increased their susceptibility to palmitic acid-induced apoptosis and sub-cellular stress. Furthermore, treatment with G9a inhibitor enhanced TGF-β induced activation of primary human hepatic stellate cells (hHSCs), implicating the role of G9a in NASH pathobiology.

Mechanisms and therapeutic implications of selective autophagy in nonalcoholic fatty liver disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease worldwide, whereas there is no approved drug therapy due to its complexity. Studies are emerging to discuss the role of selective autophagy in the pathogenesis of NAFLD, because the specificity among the features of selective autophagy makes it a crucial process in mitigating hepatocyte damage caused by aberrant accumulation of dysfunctional organelles, for which no other pathway can compensate.

AIM OF REVIEW

This review aims to summarize the types, functions, and dynamics of selective autophagy that are of particular importance in the initiation and progression of NAFLD. And on this basis, the review outlines the therapeutic strategies against NAFLD, in particular the medications and potential natural products that can modulate selective autophagy in the pathogenesis of this disease.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The critical roles of lipophagy and mitophagy in the pathogenesis of NAFLD are well established, while reticulophagy and pexophagy are still being identified in this disease due to the insufficient understanding of their molecular details. As gradual blockage of autophagic flux reveals the complexity of NAFLD, studies unraveling the underlying mechanisms have made it possible to successfully treat NAFLD with multiple pharmacological compounds that target associated pathways. Overall, it is convinced that the continued research into selective autophagy occurring in NAFLD will further enhance the understanding of the pathogenesis and uncover novel therapeutic targets.

Exploring Biomarkers in Nonalcoholic Fatty Liver Disease Among Individuals With Type 2 Diabetes Mellitus

Integrating biomarkers into a comprehensive strategy is crucial for precise patient management, especially considering the significant healthcare costs associated with diseases. Current studies emphasize the urgent need for a paradigm shift in conceptualizing nonalcoholic fatty liver disease (NAFLD), now renamed metabolic dysfunction-associated steatotic liver disease (MASLD). Biomarkers are emerging as indispensable tools for accurate diagnosis, risk stratification, and monitoring disease progression. This review classifies biomarkers into conventional and novel categories, such as lipids, insulin resistance, hepatic function, and cutting-edge imaging/omics, and evaluates their potential to transform the approach to MASLD among individuals with type 2 diabetes mellitus (T2D). It focuses on the critical role of biomarkers in early MASLD detection, enhancing predictive accuracy, and discerning responses to interventions (pharmacological or lifestyle modifications). Amid this discussion, the complexities of the relationship between T2D and MASLD are explored, considering factors like age, gender, genetics, ethnicity, and socioeconomic background. Biomarkers enhance the effectiveness of interventions and support global initiatives to reduce the burden of MASLD, thereby improving public health outcomes. This review recognizes the promising potential of biomarkers for diagnostic precision while candidly addressing the challenges in implementing these advancements in clinical practice. The transformative role of biomarkers emerges as a central theme, promising to reshape our understanding of disease trajectories, prognosis, and the customization of personalized therapeutic strategies for improved patient outcomes. From a future perspective, identifying early-stage biomarkers, understanding environmental impact through exposomes, and applying a multiomics approach may reveal additional insight into MASLD development.

Association between the lymphocyte-to-high-density lipoprotein ratio and metabolic dysfunction-associated steatotic liver disease among US adults: a cross-sectional study from NHANES 2017 to 2020

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a liver disease that is strongly associated with chronic low-grade inflammation. Stage 3 of MASLD is characterized by excessive formation of connective tissues, commonly referred to as liver fibrosis. Although numerous inflammatory markers have been identified and extensively studied, including the tumor necrosis factor-α and interleukin-6 have been studied [Byrne CD, Targher G. NAFLD: a multisystem disease. J Hepatol. 2015;62(1 Suppl):S47-64], the lymphocyte-to-high-density lipoprotein ratio (LHR) as a new biomarker that has not been sufficiently studied. This study aims to investigate the relationship between LHR levels and MASLD, determine its potential as a predictive marker for steatosis and fibrosis stages.

METHODS

This was a population-based study using data from 15,560 participants in the 2017-2020 National Health and Nutrition Examination Survey (NHANES) database. The study aimed to explore the relationship between LHR and MASLD. The disease progression was tracked by continuously measuring CAP and liver stiffness measurements. Participants who exhibited a median Controlled Attenuation Parameter (CAP) of 248 dB/m or higher were deemed to have hepatic steatosis. The LHR was calculated by dividing the lymphocyte count by the high-density lipoprotein cholesterol (HDL-C) level. Multivariate linear regression models were employed to explore the linear association between LHR and MASLD. Fitted smoothing curves and threshold effect analysis were employed to display nonlinear relationships. A two-part linear regression model was employed to estimate threshold effects. Subgroup analyses were conducted to determine the consistency of this association across various demographic groups.

RESULTS

A total of 6,950 adults aged 18 years and older were enrolled in the study, with an average age of 48.15 ± 17.10 years (49.14% male, 50.86% female). The adjusted multiple logistic regression analysis revealed a significant positive correlation between LHR and MASLD (OR: 1.64, 95% CI: 1.40-1.92). Using the complex two-piece linear regression model, we observed an inverted L-shaped association between LHR and CAP, suggesting a critical inflection point at -2.58. Subgroup analyses indicated a pronounced association of the LHR index with obese individuals (OR: 1.96, 95% CI: 1.66-2.32) and females (OR: 1.76, 95% CI: 1.25-2.46). There was no significant association between LHR and clinically significant fibrosis.

CONCLUSION

The LHR index is positively correlated with MASLD among US adults. Therefore, LHR may be a robust marker for early screening, diagnosis, and monitoring of treatment efficacy in clinical practice.

Ablation of Hepatic Asah1 Gene Disrupts Hepatic Lipid Homeostasis and Promotes Fibrotic Nonalcoholic Steatohepatitis in Mice

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of chronic liver conditions, ranging from simple steatosis to nonalcoholic steatohepatitis, which may progress to fibrosis/cirrhosis. Here, the GSE163211 data set was analyzed, and Asah1 (encoding acid ceramidase) was identified as a crucial lysosomal gene that positively correlated with NAFLD stages in obese patients. To evaluate the role of Asah1 in the progression of NAFLD, Asah1fl/fl/Albcre mice (hepatocyte-specific deletion of Asah1) and Asah1 floxed (Asah1fl/fl/wild-type) mice were fed with either a normal diet or a high-fat, high-cholesterol paigen diet (PD) for 20 weeks. The results showed that hepatocyte-specific Asah1 ablation markedly aggravated PD-induced hepatic steatosis, hepatitis, and apoptosis, and resulted in marked fibrotic changes. In addition, Asah1 gene ablation exacerbated PD-induced portal venous hemodynamic abnormality. In cultured hepatocytes, Asah1 gene knockdown resulted in increased ceramide and cholesterol levels but did not affect triglyceride level. Knocking down Asah1 gene also exhibited broad impacts on lipid homeostasis pathways, including lipogenesis, fatty acid uptake, fatty acid oxidation, and lipid transport. Furthermore, Asah1 knockdown resulted in increased endoplasmic reticulum stress and lipid droplet biogenesis. Last, Asah1 gene knockdown impaired chaperone-mediated autophagy. In conclusion, these results suggest that Asah1 functions as an important regulator of hepatic lipid homeostasis, and its deficiency exacerbates hepatocyte lipotoxicity and injury, and promotes the development of fibrotic nonalcoholic steatohepatitis.

AKR1B10 and digestive tumors development: a review

Aldo-keto reductase family 1 member B10 (AKR1B10) is a member of the AKR1B subfamily. It is mainly found in cytoplasm, and it is typically expressed in the stomach and intestines. Given that its expression is low or absent in other tissues, AKR1B10 is a potential diagnostic and therapeutic biomarker for various digestive system diseases. Here, we review recent research progress on AKR1B10 in digestive system tumors such as hepatocellular carcinoma, gastric carcinoma, colorectal carcinoma, pancreatic carcinoma, oral squamous cell carcinoma, laryngeal squamous cell carcinoma, cholangiocarcinoma, and nasopharyngeal carcinoma, over the last 5 years. We also discuss the current trends and future research directions for AKR1B10 in both oncological and non-oncological diseases to provide a scientific reference for further exploration of this gene.

TMEM135 deficiency improves hepatic steatosis by suppressing CD36 in a SIRT1-dependent manner

OBJECTIVES

Dysregulation of lipid homeostasis pathway causes many liver diseases, including hepatic steatosis. One of the primary factors contributing to lipid accumulation is fatty acid uptake by the liver. Transmembrane protein 135 (TMEM135), which exists in mitochondria and peroxisomes, participates in intracellular lipid metabolism. This study aims to investigate the role of TMEM135 on regulating cellular lipid import in the liver.

METHODS

We used in vivo, ex vivo, and in vitro models of steatosis. TMEM135 knockout (TMEM135KO) and wild type (WT) mice were fed a high-fat diet (HFD) to induce hepatic steatosis. Primary mouse hepatocytes and AML12 cells were treated with free fatty acid (FFA). Additionally, TMEM135-deficient stable cells and overexpressed cells were established using AML12 cells.

RESULTS

TMEM135 deficiency mitigated lipid accumulation in the liver of HFD-fed TMEM135KO mice. TMEM135-depleted primary hepatocytes and AML12 cells exhibited less lipid accumulation when treated with FFA compared to control cells, as shown as lipid droplets. Consistently, the effect of TMEM135 depletion on lipid accumulation was completely reversed under TMEM135 overexpression conditions. CD36 expression was markedly induced by HFD or FFA, which was reduced by TMEM135 depletion. Among the SIRT family proteins, only SIRT1 expression definitely increased in the liver of HFD-fed TMEM135KO mice along with a significant increase in NAD+/NADH ratio. However, inhibition of SIRT1 in TMEM135-depleted cells using siSIRT1 or the SIRT1 inhibitor EX-527 resulted in an increase of CD36 expression and consequent TG levels.

CONCLUSIONS

TMEM135 depletion attenuates CD36 expression in a SIRT1-dependent manner, thereby reducing cellular lipid uptake and hepatic steatosis.

Melatonin prevents glyphosate-induced hepatic lipid accumulation in roosters via activating Nrf2 pathway

BACKGROUND

Glyphosate (GLY) is a widely used herbicide with well-defined hepatotoxic effects, in which oxidative stress has been shown to be involved in the pathogenesis of hepatotoxicity. Melatonin (MET), an effective free radical scavenger, has been revealed to alleviate drug-induced liver damage by inhibiting oxidative stress.

METHODS

In this study, a rooster model with primary chicken embryo hepatocytes was applied to elucidate the therapeutic effects of MET against GLY-induced hepatic damage and the potential mechanism. Histopathological examinations, biochemical tests and immunoblotting analysis were used to monitor the protective effects of MET on GLY-induced hepatic lipid accumulation. Molecular docking analysis was used to reveal the key reason of MET-improved hepatic lipid deposition.

RESULTS

Data firstly showed that MET administration markedly improved GLY-induced hepatic injury, as evidenced by normalized liver enzymes and alleviated pathological changes of liver tissues. Moreover, MET supplementation alleviated GLY-induced hepatic lipid accumulation, which was correlated with improved serum and hepatic lipid profiles and normalized expression of lipolysis- and lipogenesis-related proteins. Notably, MET significantly inhibited vital enzymes involved in stimulating oxidative stress. Moreover, MET enhanced GLY-inhibited Nrf2 nuclear transcription and increased the expressions of its downstream target genes HO1 and NQO1. Further studies revealed that MET may interact with Nrf2 to enhance nuclear translocation of Nrf2.

CONCLUSION

Collectively, our results provide the first direct evidence that MET is a novel regulator of Nrf2, highlighting that Nrf2 may be a potential therapeutic target for GLY-induced lipotoxic liver injury.

Kidney fat by magnetic resonance spectroscopy in type 2 diabetes with chronic kidney disease

BACKGROUND AND HYPOTHESIS

The kidneys may be susceptible to ectopic fat and its lipotoxic effects, disposing them to chronic kidney disease (CKD) in type 2 diabetes (T2D). We investigated whether the kidney parenchyma fat content and kidney sinus fat volume would be higher in persons with T2D and CKD.

METHODS

Cross-sectional study including 29 controls, 27 persons with T2D and no CKD, and 48 persons with T2D and early CKD (urine albumin creatinine ratio (UACR) ≥ 30 mg/g). Kidney parenchyma fat content and kidney sinus fat volume were assessed using magnetic resonance spectroscopy and Dixon scans respectively.

RESULTS

In the control, T2D without CKD and T2D with CKD groups, respectively, median [1st - 3rd quartile] UACR was 5 [4 - 6], 6 [5 - 10] and 95 [43 - 278] mg/g. and mean ± standard deviation estimated glomerular filtration rate was 89 ± 11, 94 ± 11 and 77 ± 22 ml/min/1.73m2. Kidney parenchyma fat content was, respectively, 1.0 [0.5-2.4], 0.7 [0.2-1.2], 1.0 [0.3-2.0] % (p = 0.26). Kidney sinus fat volume was 2.8 [1.6-7.6], 8.0 [4.7-11.3], 10.3 [5.7-14.0] ml (p < 0.01). Around 90 % of T2D participants received a sodium-glucose cotransporter-2 inhibitor or glucagon-like peptide-1 receptor agonist.

CONCLUSIONS

In a setting of modern, multifactorial T2D management, kidney parenchyma fat content, evaluated with magnetic resonance spectroscopy, was similar among healthy controls and persons with T2D irrespective of CKD status. Still, kidney sinus fat volume was higher in the presence of T2D and higher still with CKD.

Carbon monoxide as a negative feedback mechanism on HIF-1α in the progression of metabolic-associated fatty liver disease

Metabolic-associated fatty liver disease (MAFLD) encompasses various chronic liver conditions, yet lacks approved drugs. Hypoxia-inducible factor-1α (HIF-1α) is pivotal in MAFLD development. Our prior research highlighted the efficacy of the nano-designed carbon monoxide (CO) donor, targeting HIF-1α in a mouse hepatic steatosis model. Given heme oxygenase-1 (HO-1, a major downstream molecule of HIF-1α) as the primary source of intrinsic CO, we hypothesized that upregulation of HO-1/CO, responsive to HIF-1α, forms a negative feedback loop regulating MAFLD progression. In this study, we explored the potential negative feedback mechanism of CO on HIF-1α and its downstream effects on MAFLD advancement. HIF-1α emerges early in hepatic steatosis induced by a high-fat (HF) diet, triggering increased HO-1 and inflammation. SMA/CORM2 effectively suppresses HIF-1α and steatosis progression when administered within the initial week of HF diet initiation but loses impact later. In adipose tissues, concurrent metabolic dysfunction and inflammation with HIF-1α activation suggest adipose tissue expansion initiates HF-induced steatosis, triggering hypoxia and liver inflammation. Notably, in an in vitro study using mouse hepatocytes treated with fatty acids, downregulating HO-1 intensified HIF-1α induction at moderate fatty acid concentrations. However, this effect diminished at high concentrations. These results suggest the HIF-1α-HO-1-CO axis as a feedback loop under physiological and mild pathological conditions. Excessive HIF-1α upregulation in pathological conditions overwhelms the CO feedback loop. Additional CO application effectively suppresses HIF-1α and disease progression, indicating potential application for MAFLD control.

Role and therapeutic perspectives of extracellular vesicles derived from liver and adipose tissue in metabolic dysfunction-associated steatotic liver disease

The global epidemic of metabolic diseases has led to the emergence of metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH), which pose a significant threat to human health. Despite recent advances in research on the pathogenesis and treatment of MASLD/MASH, there is still a lack of more effective and targeted therapies. Extracellular vesicles (EVs) discovered in a wide range of tissues and body fluids encapsulate different activated biomolecules and mediate intercellular communication. Recent studies have shown that EVs derived from the liver and adipose tissue (AT) play vital roles in MASLD/MASH pathogenesis and therapeutics, depending on their sources and intervention types. Besides, adipose-derived stem cell (ADSC)-derived EVs appear to be more effective in mitigating MASLD/MASH. This review presents an overview of the definition, extraction strategies, and characterisation of EVs, with a particular focus on the biogenesis and release of exosomes. It also reviews the effects and potential molecular mechanisms of liver- and AT-derived EVs on MASLD/MASH, and emphasises the contribution and clinical therapeutic potential of ADSC-derived EVs. Furthermore, the future perspective of EV therapy in a clinical setting is discussed.

Lipotoxicity of palmitic acid is associated with DGAT1 downregulation and abolished by PPARα activation in liver cells

Lipotoxicity refers to the harmful effects of excess fatty acids on metabolic health, and it can vary depending on the type of fatty acids involved. Saturated and unsaturated fatty acids exhibit distinct effects, though the precise mechanisms behind these differences remain unclear. Here, we investigated the lipotoxicity of palmitic acid (PA), a saturated fatty acid, compared with oleic acid (OA), a monounsaturated fatty acid, in the hepatic cell line HuH7. Our results demonstrated that PA, unlike OA, induces lipotoxicity, endoplasmic reticulum (ER) stress, and autophagy inhibition. Compared with OA, PA treatment leads to less lipid droplet (LD) accumulation and a significant reduction in the mRNA and protein level of diacylglycerol acyltransferase 1 (DGAT1), a key enzyme of triacylglycerol synthesis. Using modulators of ER stress and autophagy, we established that DGAT1 downregulation by PA is closely linked to these cellular pathways. Notably, the ER stress inhibitor 4-phenylbutyrate can suppress PA-induced DGAT1 downregulation. Furthermore, knockdown of DGAT1 by siRNA or with A922500, a specific DGAT1 inhibitor, resulted in cell death, even with OA. Both PA and OA increased the oxygen consumption rate; however, the increase associated with PA was only partially coupled to ATP synthesis. Importantly, treatment with GW7647 a specific PPARα agonist mitigated the lipotoxic effects of PA, restoring PA-induced ER stress, autophagy block, and DGAT1 suppression. In conclusion, our study highlights the crucial role of DGAT1 in PA-induced lipotoxicity, broadening the knowledge of the mechanisms underlying hepatic lipotoxicity and providing the basis for potential therapeutic interventions.

ASPP2 deficiency promotes the progression of metabolic dysfunction-associated steatohepatitis via ACSL4 upregulation

As a member of the p53-binding protein family, apoptosis-stimulating protein p53 2 (ASPP2) is closely related to autophagy and apoptosis. However, the mechanistic role of ASPP2 in the development of metabolic dysfunction-associated steatohepatitis (MASH) remains elusive. Therefore, we investigated the role and underlying mechanisms of ASPP2 in MASH progression in a mouse model of MASH and a cellular model of metabolic dysfunction-associated fatty liver disease. ASPP2 deficiency significantly promoted the inflammatory response, steatosis, and MASH progression in mice. Through transcriptomic analysis, increased ACSL4 expression was identified as a potential key factor. Further elucidation of the underlying mechanisms demonstrated that ASPP2 deficiency increased lipid accumulation and inhibited mitochondrial respiration capacity in HepG2 cells induced by oleic acid. However, silencing of ACSL4 reversed these effects. Thus, our study indicates that ASPP2 is an important regulator of MASH progression through ACSL4 upregulation, highlighting its potential as an alternative approach to MASH treatment.

Free Cholesterol-Induced Liver Injury in Non-Alcoholic Fatty Liver Disease: Mechanisms and a Therapeutic Intervention Using Dihydrotanshinone I

Build-up of free cholesterol (FC) substantially contributes to the development and severity of non-alcoholic fatty liver disease (NAFLD). Here, we investigate the specific mechanism by which FC induces liver injury in NAFLD and propose a novel therapeutic approach using dihydrotanshinone I (DhT). Rather than cholesterol ester (CE), we observed elevated levels of total cholesterol, FC, and alanine transaminase (ALT) in NAFLD patients and high-cholesterol diet-induced NAFLD mice compared to those in healthy controls. The FC level demonstrated a positive correlation with the ALT level in both patients and mice. Mechanistic studies revealed that FC elevated reactive oxygen species level, impaired the function of lysosomes, and disrupted lipophagy process, consequently inducing cell apoptosis. We then found that DhT protected mice on an HCD diet, independent of gut microbiota. DhT functioned as a potent ligand for peroxisome proliferator-activated receptor α (PPARα), stimulating its transcriptional function and enhancing catalase expression to lower reactive oxygen species (ROS) level. Notably, the protective effect of DhT was nullified in mice with hepatic PPARα knockdown. Thus, these findings are the first to report the detrimental role of FC in NAFLD, which could lead to the development of new treatment strategies for NAFLD by leveraging the therapeutic potential of DhT and PPARα pathway.

The Development of a Non-Invasive Screening Method Based on Serum microRNAs to Quantify the Percentage of Liver Steatosis

Metabolic dysfunction-associated steatotic liver disease (MASLD) is often asymptomatic and underdiagnosed; consequently, there is a demand for simple, non-invasive diagnostic tools. In this study, we developed a method to quantify liver steatosis based on miRNAs, present in liver and serum, that correlate with liver fat. The miRNAs were analyzed by miRNAseq in liver samples from two cohorts of patients with a precise quantification of liver steatosis. Common miRNAs showing correlation with liver steatosis were validated by RT-qPCR in paired liver and serum samples. Multivariate models were built using partial least squares (PLS) regression to predict the percentage of liver steatosis from serum miRNA levels. Leave-one-out cross validation and external validation were used for model selection and to estimate predictive performance. The miRNAseq results disclosed (a) 144 miRNAs correlating with triglycerides in a set of liver biobank samples (n = 20); and (b) 124 and 102 miRNAs correlating with steatosis by biopsy digital image and MRI analyses, respectively, in liver samples from morbidly obese patients (n = 24). However, only 35 miRNAs were common in both sets of samples. RT-qPCR allowed to validate the correlation of 10 miRNAs in paired liver and serum samples. The development of PLS models to quantitatively predict steatosis demonstrated that the combination of serum miR-145-3p, 122-5p, 143-3p, 500a-5p, and 182-5p provided the lowest root mean square error of cross validation (RMSECV = 1.1, p-value = 0.005). External validation of this model with a cohort of mixed MASLD patients (n = 25) showed a root mean squared error of prediction (RMSEP) of 5.3. In conclusion, it is possible to predict the percentage of hepatic steatosis with a low error rate by quantifying the serum level of five miRNAs using a cost-effective and easy-to-implement RT-qPCR method.

Inhibition of the miR-1914-5p increases the oxidative metabolism in cellular model of steatosis by modulating the Sirt1-PGC-1α pathway and systemic cellular activity

Metabolic associated fatty liver disease (MAFLD) is considered an indicator of metabolic syndrome, which affects millions of people around the world and no effective treatment is currently available. MAFLD involves a wide spectrum of liver damage, that initiates from steatosis (fatty live) and may progress to more complex pathophysiology. Then, details in lipid metabolism controlling should be explored aiming to control the fatty liver. In this context, the miR-1914-5p can be considered a potential biotechnology tool to control lipid metabolism in hepatic cells. This miRNA finds potential mRNA binding sequences in more than 100 molecules correlated with energy production and lipid metabolism pointed in bioinformatic platforms. The present study addressed the miR-1914-5p effects in hepatic HepG2/LX-2 co-cultured cells in a in vitro steatotic environment stablished by the addition of 400 μM of a mixture of oleic and palmitic acids. The analyses demonstrated that the inhibition of the miRNA reduced energetic metabolites such as total lipids, triglycerides, cholesterol and even glucose. In addition, the miR-inhibitor-transfected cells did not present any deleterious effect in cellular environment by controlling reactive oxygen species production (ROS), mitochondrial membrane potential (ΔΨm) and even the pro-inflammatory environment. Moreover, the functional effect of the investigated miR, suggested its close connection to the modulation of Sirt-1-PGC1-α pathway, a master switch metabolic route that controlls cellular energetic metabolism. Our assays also suggested a synergistic effect of this miR-1914-5p in cell metabolism, which should be considered as a strong candidate to control steatotic environment in future clinical trials.

Decreasing the burden of non-alcoholic fatty liver disease: From therapeutic targets to drug discovery opportunities

Non-alcoholic fatty liver disease (NAFLD) presents a pervasive global pandemic, affecting approximately 25 % of the world's population. This grave health issue not only demands urgent attention but also stands as a significant economic concern on a global scale. The genesis of NAFLD can be primarily attributed to unhealthy dietary habits and a sedentary lifestyle, albeit certain genetic factors have also been recorded to contribute to its occurrence. NAFLD is characterized by fat accumulation in more than 5 % of hepatocytes according to histological analysis, or >5.6 % of lipid volume fraction in total liver weight in patients. The pathophysiology of NAFLD/non-alcoholic steatohepatitis (NASH) is multifactorial and the mechanisms underlying the progression to advanced forms remain unclear, thereby representing a challenge to disease therapy. Despite the substantial efforts from the scientific community and the large number of pre-clinical and clinical trials performed so far, only one drug was approved by the Food and Drug Administration (FDA) to treat NAFLD/NASH specifically. This review provides an overview of available information concerning emerging molecular targets and drug candidates tested in clinical studies for the treatment of NAFLD/NASH. Improving our understanding of NAFLD pathophysiology and pharmacotherapy is crucial not only to explore new molecular targets, but also to potentiate drug discovery programs to develop new therapeutic strategies. This knowledge endeavours scientific efforts to reduce the time for achieving a specific and effective drug for NAFLD or NASH management and improve patients' quality of life.

Genome wide identification and characterization of Bax inhibitor-1 gene family in cucumber (Cucumis sativus) under biotic and abiotic stress

In plants, the BAX inhibitor-1 (BI-1) gene plays a crucial part in controlling cell death under stress conditions. This mechanism of Programmed Cell Death (PCD) is genetically regulated and is crucial for the elimination of unwanted or damaged cells in a controlled manner, which is essential for normal development and tissue maintenance. A study on cucumber identified and characterized five BI-1 genes: CsBI1, CsBI2, CsBI3, CsBI4, and CsBI5. These genes share conserved domains, indicating common evolutionary history and function. Physicochemical analysis revealed their molecular weights and isoelectric points, while subcellular localization showed their presence in different cellular compartments. The phylogenetic analysis highlighted evolutionary relationships with related crops. Chromosomal distribution and synteny analysis suggested segmental or tandem duplications within the gene family. Protein-protein interaction analysis revealed extensive interactions with other cucumber proteins. Cis-regulatory elements in the promoter regions provided insights into potential functions and transcriptional regulation. miRNAs showed diverse regulatory mechanisms, including mRNA cleavage and translational inhibition. The CsBI3, CsBI4 and CsBI5 genes exhibit elevated expression levels during cold stress, suggesting their vital involvement in cucumber plant defense mechanisms. The application of chitosan oligosaccharides externally confirms their distinct expression patterns. The qRT-PCR confirms the upregulation of CsBI genes in ToLCNDV-infected plants, indicating their potential to mitigate biotic and abiotic stresses. The comprehensive genome-wide exploration provides opportunities for the development of cold-tolerant and virus-resistant cucumber variants by traditional breeding or gene.

The NRF-2/HO-1 Signaling Pathway: A Promising Therapeutic Target for Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive liver disorder with a rising prevalence. It begins with lipid accumulation in hepatocytes and gradually progresses to Metabolic-associated steatohepatitis (MASH), fibrosis, cirrhosis, and potentially hepatocellular carcinoma (HCC). The pathophysiology of MASLD is complex and involves multiple factors, with oxidative stress playing a crucial role. Oxidative stress drives the progression of MASLD by causing cellular damage, inflammatory responses, and fibrosis, making it a key pathogenic mechanism. The Nuclear Factor Erythroid 2-Related Factor 2 / Heme Oxygenase-1 (Nrf2/HO-1) signaling axis provides robust multi-organ protection against a spectrum of endogenous and exogenous insults, particularly oxidative stress. It plays a pivotal role in mediating antioxidant, anti-inflammatory, and anti-apoptotic responses. Many studies indicate that activating the Nrf2/HO-1 signaling pathway can significantly mitigate the progression of MASLD. This article examines the role of the Nrf2/HO-1 signaling pathway in MASLD and highlights natural compounds that protect against MASLD by targeting Nrf2/HO-1 activation. The findings indicate that the Nrf2/HO-1 signaling pathway holds great promise as a therapeutic target for MASLD.

Copper homeostasis and cuproptosis-related genes: Therapeutic perspectives in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD), a metabolic-associated fatty liver disease, has become the most common chronic liver disease worldwide. Recently, the discovery of cuproptosis, a newly identified mode of cell death, further highlighted the importance of copper in maintaining metabolic homeostasis. An increasing number of studies have confirmed that liver copper metabolism is closely related to the pathogenesis of NAFLD. However, the relationship between NAFLD and copper metabolism, especially cuproptosis, remains unclear. In this review, we aim to summarize the current understanding of copper metabolism and its dysregulation, particularly the role of copper metabolism dysregulation in the pathogenesis of NAFLD. More importantly, this review emphasizes potential gene-targeted therapeutic strategies, challenges and the future of cuproptosis-related genes in the treatment of NAFLD. This review aims to provide innovative therapeutic strategies for NAFLD.

Jolkinolide B Ameliorates Liver Inflammation and Lipogenesis by Regulating JAK/STAT3 Pathway

Hepatic dysregulation of lipid metabolism exacerbates inflammation and enhances the progression of metabolic dysfunction-associated steatotic liver disease (MASLD). STAT3 has been linked to lipid metabolism and inflammation. Jolkinolide B (JB), derived from Euphorbia fischeriana, is known for its pharmacological anti-inflammatory and anti-tumor properties. Therefore, this study investigated whether JB affects MASLD prevention by regulating STAT3 signaling. JB attenuated steatosis and inflammatory responses in palmitic acid (PA)-treated hepatocytes. Additionally, JB treatment reduced the mRNA expression of de-novo lipogenic genes, such as acetyl-CoA carboxylase and stearoyl-CoA desaturase 1. Interestingly, JB-mediated reduction in inflammation and lipogenesis was dependent on STAT3 signaling. JB consistently modulated mitochondrial dysfunction and the mRNA expression of inflammatory cytokines by inhibiting PA-induced JAK/STAT3 activation. This study suggests that JB is a potential therapeutic agent to prevent major stages of MASLD through inhibition of JAK/STAT3 signaling in hepatocytes.

Zhimu-Huangbai herb-pair ameliorates hepatic steatosis in mice by regulating IRE1α/XBP1s pathway to inhibit SREBP-1c

BACKGROUND

Currently, there is a lack of validated pharmacological interventions for non-alcoholic fatty liver disease (NAFLD), which is characterized by the accumulation of hepatic triglyceride. Zhimu-Huangbai (ZH) herb-pair is a traditional Chinese medicine that regulates glucose and lipid metabolism disorders. However, the precise mechanisms underlying the preventive effects of hepatic triglyceride induced by high-fat diet (HFD) remain elusive.

PURPOSE

The study aimed to examine the impact of ZH herb-pair on NAFLD in mice and explore the underlying mechanisms, particularly its effects on endoplasmic reticulum (ER) stress and lipid metabolism.

METHODS

NAFLD was induced in mice using HFD, and the treated mice were orally administered ZH, metformin (Glucophage) or lovastatin. The lipid metabolism factors, ER stress markers, and the unfolded protein response (UPR) branch factors were measured using immunohistochemistry, western blotting or qRT-PCR. Co-Immunoprecipitation (CoIP) was performed to reveal the connection between SCAP and SREBP-1c. Tunicamycin (TM) and plasmid delivery were used to induce acute ER stress or crease XBP1 gain function models. The main compounds in ZH binding to IRE1α protein were studied by molecular docking and cellular thermal shift assay (CETSA).

RESULTS

Treatment with ZH significantly ameliorated hepatic steatosis and reduced lipid synthesis process mainly inhibiting the expression of mature active form of SREBP-1c through relieving ER stress. The expression of IRE1α and XBP1s was inhibited after treatment with ZH. In addition, ZH improved the fatty liver phenotype caused by XBP1 overexpression via decreasing srebp1c transcription. In vitro experimental results suggested that the main compounds in ZH decreased cellular TG contents. Mechanistically, ZH targeted IRE1α and inhibited XBP1s mRNA expression to relieve ER stress and inhibit SREBP-1c production.

CONCLUSIONS

ZH herb-pair can protect against NAFLD by reducing the expression of SREBP-1c, in part, via regulating IRE1α/XBP1s pathway.

Blockade of 11β-hydroxysteroid dehydrogenase type 1 ameliorates metabolic dysfunction-associated steatotic liver disease and fibrosis

11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1) is a key enzyme involved in the conversion of cortisone to active cortisol in the liver. Elevated cortisol levels can trigger oxidative stress, inflammation, and hepatocyte damage, highlighting the importance of 11β-HSD1 inhibition as a potential therapeutic approach. This study aimed to explore the effects of INU-101, an inhibitor of 11β-HSD1, on the development of metabolic dysfunction-associated steatotic liver disease (MASLD) and fibrosis. Our findings demonstrated that INU-101 effectively mitigated cortisol-induced lipid accumulation, reactive oxygen species generation, and hepatocyte apoptosis. Furthermore, 11β-HSD1 inhibition suppressed hepatic stellate cell activation by modulating β-catenin and phosphorylated SMAD2/3. INU-101 administration significantly reduced hepatic lipid accumulation and liver fibrosis in mice fed fast-food diet. This study suggests that INU-101 holds promise as a clinical candidate for treating MASLD and fibrosis, offering potential therapeutic benefits by targeting the intricate processes involving 11β-HSD1 and cortisol regulation in the liver.

Cooperative action of non-digestible oligosaccharides improves lipid metabolism of high-fat diet-induced mice

Non-digestible oligosaccharides are known to exert health-promoting effects. However, the specific mechanisms by which they regulate host physiology remain unclear. Understanding these mechanisms will facilitate the development of non-digestible oligosaccharide compositions that can achieve synergistic effects. This study selected three representative non-digestible oligosaccharides, namely xylo-oligosaccharides (XOS), galacto-oligosaccharides (GOS), and isomalto-oligosaccharides (IMO), to investigate their effects as dietary interventions on mice fed a high-fat diet. The results demonstrated that XOS and IMO synergistically mitigated weight gain and ectopic lipid deposition. Further analysis revealed that XOS significantly altered the composition of the gut microbiota, while IMO significantly enhanced insulin sensitivity via the PI3K/Akt pathway. Moreover, the combination of XOS and IMO synergistically promoted the oxidation and breakdown of fatty acids and increased the abundance of acetate and propionate-producing bacteria, such as Lactobacillus. These findings suggest a novel strategy for obesity management based on dietary intervention with XOS and IMO.

Unstressing the Reticulum: Nutritional Strategies for Modulating Endoplasmic Reticulum Stress in Obesity

The progression of obesity involves several molecular mechanisms that are closely associated with the pathophysiological response of the disease. Endoplasmic reticulum (ER) stress is one such factor. Lipotoxicity disrupts endoplasmic reticulum homeostasis in the context of obesity. Furthermore, it induces ER stress by activating several signaling pathways via inflammatory responses and oxidative stress. ER performs crucial functions in protein synthesis and lipid metabolism; thus, triggers such as lipotoxicity can promote the accumulation of misfolded proteins in the organelle. The accumulation of these proteins can lead to metabolic disorders and chronic inflammation, resulting in cell death. Thus, alternatives, such as flavonoids, amino acids, and polyphenols that are associated with antioxidant and anti-inflammatory responses have been proposed to attenuate this response by modulating ER stress via the administration of nutrients and bioactive compounds. Decreasing inflammation and oxidative stress can reduce the expression of several ER stress markers and improve clinical outcomes through the management of obesity, including the control of body weight, visceral fat, and lipid accumulation. This review explores the metabolic changes resulting from ER stress and discusses the role of nutritional interventions in modulating the ER stress pathway in obesity.

A systematic review of dietary and circulating carotenoids and liver disease

Background: due to the high incidence of liver disease and the severity of adverse outcomes, liver disease has become a serious public health problem, bringing a huge disease burden to individuals, families, and society. Most studies have shown significant differences in serum carotenoid content and dietary carotenoid intake between liver disease patients and non-liver disease patients, but some studies have reported contrary results. This paper aimed to systematically review and analyze all published epidemiological studies on carotenoids and liver disease to quantitatively assess the relationship between serum and dietary carotenoid concentrations and liver disease. Methods: by systematically searching PubMed, Web of Science, Scopus, Embase, and Cochrane databases according to pre-combined search terms from inception to July 23, 2024, 30 studies were found to meet the exclusion criteria. Finally, 3 RCT studies, 6 cohort studies, 11 case-control studies, 9 cross-sectional studies, and 1 RCT-combined cross-sectional study were included in the further analysis. Two reviewers independently scored the literature quality and extracted data, and the results were represented by the standard mean difference (SMD) with a 95% confidence interval. Cochran Q statistics and I2 statistics were used to evaluate statistical heterogeneity (defined as significant when P < 0.05 or I2 > 50%). When there was insignificant heterogeneity, a fixed effects model was selected; otherwise a random effects model was used. Publication bias was assessed by the Egger test. Results: pooled meta-analysis showed that serum α-carotene (SMD = -0.58, 95% CI (-0.83, -0.32), P < 0.001), β-carotene (SMD = -0.81, 95% CI (-1.13, -0.49), P < 0.001), and lycopene (SMD = -1.06, 95% CI (-1.74, -0.38), P < 0.001) were negatively correlated with the risk and severity of liver disease. However, no significant difference was observed between serum β-cryptoxanthin (SMD = 0.02, 95% CI (-0.41, 0.45), P = 0.92) and lutein/zeaxanthin (SMD = 0.62, 95% CI (-1.20, 2.45), P = 0.502). Dietary β-carotene intake (SMD = -0.22, 95% CI (-0.31, -0.13), P < 0.001) was negatively associated with the risk of liver disease. The Egger test showed no publication bias (P > 0.05). An intake of more than 6 mg of carotenoids on an energy-restricted diet can effectively alleviate the symptoms of NAFLD. Conclusion: lower serum concentrations of α-carotene, β-carotene, and lycopene were associated with a higher risk of liver disease. Meanwhile, dietary intake of β-carotene could reduce the incidence of liver disease. However, for malignant diseases such as liver cancer, it did not show the significant effects of carotenoid supplementation.

EZH2-Mediated H3K27 Trimethylation in the Liver of Mice Is an Early Epigenetic Event Induced by High-Fat Diet Exposure

BACKGROUND/OBJECTIVES

Methyltransferase EZH2-mediated H3K27me3 is involved in liver inflammation and fibrosis, but its role in hepatic metabolic derangements is not yet clearly defined. We investigated if a high-fat diet (HFD) induced early changes in EZH2 expression and H3K27 me3 in the liver of mice.

METHODS

Five-week-old mice were fed an HFD or a low-fat diet (Control) for 2 weeks (2 W) or 8 weeks (8 W). Body weight was recorded weekly. Glycemia and oral glucose tolerance were assessed at baseline and after 2 W-8 W. Finally, livers were collected for further analysis.

RESULTS

As expected, mice that received 8 W HFD showed an increase in body weight, glycemia, and liver steatosis and an impairment in glucose tolerance; no alterations were observed in 2 W HFD mice. Eight weeks of HFD caused hepatic EZH2 nuclear localization and increased H3 K27me3; surprisingly, the same alterations occurred in 2 W HFD mice livers, even before overweight onset. We demonstrated that selective EZH2 inhibition reduced H3K27me3 and counteracted lipid accumulation in HUH-7 cells upon palmitic acid treatment.

CONCLUSIONS

In conclusion, we point to EZH2/H3K27me3 as an early epigenetic event occurring in fatty-acid-challenged livers both in vivo and in vitro, thus establishing EZH2 as a potential pharmacological target for metabolic derangements.

Liver-specific actions of GH and IGF1 that protect against MASLD

Metabolic dysfunction-associated steatotic liver disease (MASLD; also known as nonalcoholic fatty liver disease) is a chronic condition associated with metabolic syndrome, a group of conditions that includes obesity, insulin resistance, hyperlipidaemia and cardiovascular disease. Primary growth hormone (GH) deficiency is associated with MASLD, and the decline in circulating levels of GH with weight gain might contribute to the development of MASLD. Raising endogenous GH secretion or administering GH replacement therapy in the context of MASLD enhances insulin-like growth factor 1 (IGF1) production and reduces steatosis and the severity of liver injury. GH and IGF1 indirectly control MASLD progression by regulating systemic metabolic function. Evidence supports the proposal that GH and IGF1 also have a direct role in regulating liver metabolism and health. This Review focuses on how GH acts on the hepatocyte in a sex-dependent manner to limit lipid accumulation, reduce stress, and promote survival and regeneration. In addition, we discuss how GH and IGF1 might regulate non-parenchymal cells of the liver to control inflammation and fibrosis, which have a major effect on hepatocyte survival and regeneration. Development of a better understanding of how GH and IGF1 coordinate the functions of specific, individual liver cell types might provide insight into the aetiology of MASLD initiation and progression and suggest novel approaches for the treatment of MASLD.

Transcriptome analysis reveals hepatic disordered lipid metabolism, lipotoxic injury, and abnormal development in IUGR sheep fetuses due to maternal undernutrition during late pregnancy

Although lipid metabolism in fetal livers under intrauterine growth restriction (IUGR) conditions has been widely studied, the implications of maternal undernutrition on fetal hepatic lipid metabolism, lipotoxic injury, and abnormal development remain largely unknown. Therefore, this study investigated the effects of maternal undernutrition on disordered hepatic lipid metabolism, lipotoxic injury, and abnormal development in IUGR sheep fetuses using transcriptome analysis. Seventeen singleton ewes were randomly divided into three groups on day 90 of pregnancy: a control group (CG; 0.63 MJ metabolic energy/body weight (ME/BW)0.75/day, n = 5), maternal undernutrition group 1 (MU1; 0.33 MJ ME/BW0.75/day, n = 6), and maternal undernutrition group 2 (MU2; 0.20 MJ ME/BW0.75/day, n = 6). The fetuses were euthanized and recovered on day 130 of pregnancy. The levels of free fatty acids (FFA) in maternal blood (P < 0.01), fetal blood (P < 0.01), and fetal livers (P < 0.05) were increased in the MU1 and MU2 groups, but fetal hepatic triglyceride (TG) levels in the MU2 group (P < 0.01) and β-hydroxybutyrate levels in the MU1 and MU2 groups (P < 0.01) were decreased compared to the CG. Severe inflammatory cell infiltration and increased non-alcoholic fatty liver disease activity scores were observed in MU1 and MU2 fetuses (P < 0.01). Progressive deposition of fetal hepatic reticular fibers and collagen fibers in the fetal livers of the MU1 and MU2 groups and significant hepatic fibrosis were observed in the MU2 fetuses (P < 0.05). Gene set enrichment analysis showed that genes involved in lipid accumulation and FFA beta oxidation were downregulated in both MU groups compared to those in the controls. The fetal liver mRNA expression of the β-oxidation regulator, acetyl-CoA acetyltransferase 1, and the TCA regulator, isocitrate dehydrogenase were reduced in MU1 (P < 0.05) and MU2 (P < 0.01) fetuses, and downregulated mRNA expression of long chain fatty acid CoA ligase 1 (P < 0.05) and glycerol-3-phosphate acyltransferase (P < 0.01) was observed in MU2 fetuses. Differentially expressed genes (DEGs) in MU1 versus CG (360 DEGs) and MU2 versus CG (746 DEGs) were identified using RNA sequencing. Bioinformatics analyses of the 231 intersecting DEGs between MU1 versus CG and MU2 versus CG indicated that neutrophil extracellular traps (NETs) were induced and played a central role in fetal hepatic injury in IUGR sheep. Increased maternal blood myeloperoxidase (MPO) levels (P < 0.01), NE (Elane)-positive areas in fetal liver sections (P < 0.05), and fetal liver MPO protein expression (P < 0.01) were found in the MU1 and MU2 groups; however, MPO levels were reduced in the fetal membrane (P < 0.01) and fetal blood (P < 0.05) in the MU1 group, and in the maternal-fetal placenta and fetal blood in the MU2 group (P < 0.01). Analysis of gene expression trends in the intersecting DEGs between MU1 versus CG (129 DEGs) and MU2 versus CG (515 DEGs) further revealed that 30 hub genes were essential regulators of the G2/M cell cycle, all of which were associated with hepatocellular carcinoma. G0/G1 phase cells of the fetal liver were reduced in the MU1 (P < 0.05) and MU2 (P < 0.01) groups, whereas G2/M phase cells were elevated in the MU1 and MU2 groups (P < 0.01). The representatives of upregulated hub genes and fetal liver protein expression of maternal embryonic leucine zipper kinase and protein regulator of cytokinesis 1 were progressively enhanced in the MU1 and MU2 groups (P < 0.01), and topoisomerase II alpha protein expression in the MU2 group (P < 0.05), as expected. These results indicate that FFA overload, severe lipotoxic injury, and NETs were induced, and disease-promoting regulators of the G2/M cell cycle were upregulated in the fetal liver of IUGR sheep. These findings provide new insights into the pathogenesis of impaired hepatic lipid metabolism and abnormal development and the molecular origin of post-natal liver disease in IUGR due to maternal undernutrition. This information can support the development of new therapeutic strategies.

Seabuckthorn polysaccharides mitigate hepatic steatosis by modulating the Nrf-2/HO-1 pathway and gut microbiota

Non-alcoholic fatty liver disease (NAFLD) is becoming a significant global public health threat. Seabuckthorn (Hippophae rhamnoides L.) has been used in traditional Chinese medicine (TCM). The hypolipidemic effects of Seabuckthorn polysaccharides (SP) against high-fat diets (HFD)-induced NAFLD were systematically explored and compared with that of Bifidobacterium lactis V9 (B. Lactis V9). Results showed that HFD-induced alanine transaminase (ALT) and aspartate aminotransferase (AST) levels decreased by 2.8-fold and 4.5-fold, respectively, after SP supplementation. Moreover, the alleviating effect on hepatic lipid accumulation is better than that of B. Lactis V9. The ACC and FASN mRNA levels were significantly reduced by 1.8 fold (P < 0.05) and 2.3 folds (P < 0.05), respectively, while the CPT1α and PPARα mRNA levels was significantly increased by 2.3 fold (P < 0.05) and 1.6 fold (P < 0.05), respectively, after SP administration. SP activated phosphorylated-AMPK and inhibited PPARγ protein expression, improved serum oxidative stress and inflammation (P < 0.05). SP supplementation leads to increased hepatic expression of nuclear factor erythroid 2-related factor 2 (Nrf-2), heme oxygenase-1 (HO-1) and Superoxide dismutase-2 (SOD-2). Furthermore, SP treatment improved HFD-induced intestinal dysbiosis. Lentisphaerae, Firmicutes, Tenericutes and Peptococcus sp., RC9_gut_group sp., and Parabacteroides sp. of the gut microbiota were significantly associated with hepatic steatosis and indicators related to oxidative stress and inflammation. Therefore, SP can mitigate hepatic lipid accumulation by regulating Nrf-2/HO-1 signaling pathways and gut microbiota. This study offers new evidence supporting the use of SP as a prebiotic treatment for NAFLD.

Esrra regulates Rplp1-mediated translation of lysosome proteins suppressed in metabolic dysfunction-associated steatohepatitis and reversed by alternate day fasting

OBJECTIVE

Currently, little is known about the mechanism(s) regulating global and specific protein translation during metabolic dysfunction-associated steatohepatitis (MASH; previously known as non-alcoholic steatohepatitis, NASH).

METHODS

Unbiased label-free quantitative proteome, puromycin-labelling and polysome profiling were used to understand protein translation activity in vitro and in vivo.

RESULTS

We observed a global decrease in protein translation during lipotoxicity in human primary hepatocytes, mouse hepatic AML12 cells, and livers from a dietary mouse model of MASH. Interestingly, proteomic analysis showed that Rplp1, which regulates ribosome and translation pathways, was one of the most downregulated proteins. Moreover, decreased Esrra expression and binding to the Rplp1 promoter, diminished Rplp1 gene expression during lipotoxicity. This, in turn, reduced global protein translation and Esrra/Rplp1-dependent translation of lysosome (Lamp2, Ctsd) and autophagy (sqstm1, Map1lc3b) proteins. Of note, Esrra did not increase its binding to these gene promoters or their gene transcription, confirming its regulation of their translation during lipotoxicity. Notably, hepatic Esrra-Rplp1-dependent translation of lysosomal and autophagy proteins also was impaired in MASH patients and liver-specific Esrra knockout mice. Remarkably, alternate day fasting induced Esrra-Rplp1-dependent expression of lysosomal proteins, restored autophagy, and reduced lipotoxicity, inflammation, and fibrosis in hepatic cell culture and in vivo models of MASH.

CONCLUSIONS

Esrra regulation of Rplp1-mediated translation of lysosome/autolysosome proteins was downregulated during MASH. Alternate day fasting activated this novel pathway and improved MASH, suggesting that Esrra and Rplp1 may serve as therapeutic targets for MASH. Our findings also provided the first example of a nuclear hormone receptor, Esrra, to not only regulate transcription but also protein translation, via induction of Rplp1.

Lipid nanoparticle encapsulated oleic acid induced lipotoxicity to hepatocytes via ROS overload and the DDIT3/BCL2/BAX/Caspases signaling in vitro and in vivo

BACKGROUND

To date, Non-alcoholic fatty liver disease (NAFLD) is one of the most common liver disease associated with clinical complications. Dietary fatty acids have been suggested to be involved in preventing or reversing the accumulation of hepatic fat. However, contradicting roles of monounsaturated fatty acids to the liver have been implicated in various human and murine models, mainly due to the insolubility nature of fatty acids.

METHODS

High pressure homogenization methods were used to fabricate oleic acid embedded lipid nanoparticles (OALNs). The in vitro and in vivo models were used to validate the physiological effect of this OALNs via various cellular and molecular approaches including cell viability essay, fluorescent staining, electron microscope, RNAseq, qPCR, Western blots, and IHC staining.

RESULTS

We successfully fabricated OALNs with enhanced stability and solubility. More importantly, lipid accumulation was successfully induced in hepatocytes via the application of OALNs in a dose-dependent manner. Overload of OALNs resulted in ROS accumulation and apoptosis of hepatocytes dose-dependently. With the help of transcriptome sequencing and traditional experimental approaches, we demonstrated that the lipotoxic effect induced by OALNs was exerted via the DDIT3/BCL2/BAX/Caspases signaling. Moreover, we also verified that OALNs induced steatosis and subsequent apoptosis in the liver of mice via the activation of DDIT3 in vivo.

CONCLUSIONS

In all, our results established a potential pathogenic model of NAFLD for further studies and indicated the possible involvement of DDIT3 signaling in abnormal steatosis process of the liver.

Lipidomics Investigation Reveals the Reversibility of Hepatic Injury by Silica Nanoparticles in Rats After a 6-Week Recovery Duration

Given the inevitable human exposure owing to its increasing production and utilization, the comprehensive safety evaluation of silica nanoparticles (SiNPs) has sparked concerns. Substantial evidence indicated liver damage by inhaled SiNPs. Notwithstanding, few reports focused on the persistence or reversibility of hepatic injuries, and the intricate molecular mechanisms involved remain limited. Here, rats are intratracheally instilled with SiNPs in two regimens (a 3-month exposure and a subsequent 6-week recovery after terminating SiNPs administration) to assess the hepatic effects. Nontargeted lipidomics revealed alterations in lipid metabolites as a contributor to the hepatic response and recovery effects of SiNPs. In line with the functional analysis of differential lipid metabolites, SiNPs activated oxidative stress, and induced lipid peroxidation and lipid deposition in the liver, as evidenced by the elevated hepatic levels of ROS, MDA, TC, and TG. Of note, these indicators showed great improvements after a 6-week recovery, even returning to the control levels. According to the correlation, ROC curve, and SEM analysis, 11 lipids identified as potential regulatory molecules for ameliorating liver injury by SiNPs. Collectively, the work first revealed the reversibility of SiNP-elicited hepatotoxicity from the perspective of lipidomics and offered valuable laboratory evidence and therapeutic strategy to facilitate nanosafety.

Adipose tissue macrophage infiltration and hepatocyte stress increase GDF-15 throughout development of obesity to MASH

Plasma growth differentiation factor-15 (GDF-15) levels increase with obesity and metabolic dysfunction-associated steatotic liver disease (MASLD) but the underlying mechanism remains poorly defined. Using male mouse models of obesity and MASLD, and biopsies from carefully-characterized patients regarding obesity, type 2 diabetes (T2D) and MASLD status, we identify adipose tissue (AT) as the key source of GDF-15 at onset of obesity and T2D, followed by liver during the progression towards metabolic dysfunction-associated steatohepatitis (MASH). Obesity and T2D increase GDF15 expression in AT through the accumulation of macrophages, which are the main immune cells expressing GDF15. Inactivation of Gdf15 in macrophages reduces plasma GDF-15 concentrations and exacerbates obesity in mice. During MASH development, Gdf15 expression additionally increases in hepatocytes through stress-induced TFEB and DDIT3 signaling. Together, these results demonstrate a dual contribution of AT and liver to GDF-15 production in metabolic diseases and identify potential therapeutic targets to raise endogenous GDF-15 levels.

Application of PPAR Ligands and Nanoparticle Technology in Metabolic Steatohepatitis Treatment

Metabolic dysfunction-associated steatotic liver disease/steatohepatitis (MASLD/MASH) is a major disease worldwide whose effective treatment is challenging. Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear receptor superfamily and function as ligand-activated transcription factors. To date, three distinct subtypes of PPARs have been characterized: PPARα, PPARβ/δ, and PPARγ. PPARα and PPARγ are crucial regulators of lipid metabolism that modulate the transcription of genes involved in fatty acid (FA), bile acid, and cholesterol metabolism. Many PPAR agonists, including natural (FAs, eicosanoids, and phospholipids) and synthetic (fibrate, thiazolidinedione, glitazar, and elafibranor) agonists, have been developed. Furthermore, recent advancements in nanoparticles (NPs) have led to the development of new strategies for MASLD/MASH therapy. This review discusses the applications of specific cell-targeted NPs and highlights the potential of PPARα- and PPARγ-targeted NP drug delivery systems for MASLD/MASH treatment.

Fanlian Huazhuo Formula alleviates high-fat diet-induced non-alcoholic fatty liver disease by modulating autophagy and lipid synthesis signaling pathway

BACKGROUND

Fanlian Huazhuo Formula (FLHZF) has the functions of invigorating spleen and resolving phlegm, clearing heat and purging turbidity. It has been identified to have therapeutic effects on type 2 diabetes mellitus (T2DM) in clinical application. Non-alcoholic fatty liver disease (NAFLD) is frequently diagnosed in patients with T2DM. However, the therapeutic potential of FLHZF on NAFLD and the underlying mechanisms need further investigation.

AIM

To elucidate the effects of FLHZF on NAFLD and explore the underlying hepatoprotective mechanisms in vivo and in vitro.

METHODS

HepG2 cells were treated with free fatty acid for 24 hours to induce lipid accumulation cell model. Subsequently, experiments were conducted with the different concentrations of freeze-dried powder of FLHZF for 24 hours. C57BL/6 mice were fed a high-fat diet for 8-week to establish a mouse model of NAFLD, and then treated with the different concentrations of FLHZF for 10 weeks.

RESULTS

FLHZF had therapeutic potential against lipid accumulation and abnormal changes in biochemical indicators in vivo and in vitro. Further experiments verified that FLHZF alleviated abnormal lipid metabolism might by reducing oxidative stress, regulating the AMPKα/SREBP-1C signaling pathway, activating autophagy, and inhibiting hepatocyte apoptosis.

CONCLUSION

FLHZF alleviates abnormal lipid metabolism in NAFLD models by regulating reactive oxygen species, autophagy, apoptosis, and lipid synthesis signaling pathways, indicating its potential for clinical application in NAFLD.

Heterocyclic Amines Disrupt Lipid Homeostasis in Cryopreserved Human Hepatocytes

Metabolic dysfunction associated-steatotic liver disease (MASLD)/metabolic dysfunction-associated steatohepatitis (MASH) is the liver manifestation of metabolic syndrome, which is characterized by insulin resistance, hyperglycemia, hypertension, dyslipidemia, and/or obesity. Environmental pollutant exposure has been recently identified as a risk factor for developing MASH. Heterocyclic amines (HCAs) are mutagens generated when cooking meat at high temperatures or until well-done. Recent epidemiological studies reported that dietary HCA exposure may be linked to insulin resistance and type II diabetes, and we recently reported that HCAs induce insulin resistance and glucose production in human hepatocytes. However, no previous studies have examined the effects of HCAs on hepatic lipid homeostasis. In the present study, we assessed the effects of two common HCAs, MeIQx (2-amino-3, 8-dimethylimidazo [4, 5-f] quinoxaline) and PhIP (2-amino-1-methyl-6-phenylimidazo[4, 5-b] pyridine), on lipid homeostasis in cryopreserved human hepatocytes. Exposure to a single concentration of 25 μM MeIQx or PhIP in human hepatocytes led to dysregulation of lipid homeostasis, typified by significant increases in lipid droplets and triglycerides. PhIP significantly increased expression of lipid droplet-associated genes, PNPLA3 and HSD17B13, and both HCAs significantly increased PLIN2. Exposure to MeIQx or PhIP also significantly increased expression of several key genes involved in lipid synthesis, transport and metabolism, including FASN, DGAT2, CPT1A, SCD, and CD36. Furthermore, both MeIQx and PhIP significantly increased intracellular cholesterol and decreased expression of PON1 which is involved in cholesterol efflux. Taken together, these results suggest that HCAs dysregulate lipid production, metabolism, and storage. The current study demonstrates, for the first time, that HCA exposure may lead to fat accumulation in hepatocytes, which may contribute to hepatic insulin resistance and MASH.

Polystyrene Nanoplastics Induce Lipid Metabolism Disorder by Activating the PERK-ATF4 Signaling Pathway in Mice

In recent years, the study of microplastics (MPs) and nanoplastics (NPs) and their effects on human health has gained significant attention. The impacts of NPs on lipid metabolism and the specific mechanisms involved remain poorly understood. To address this, we utilized high-throughput sequencing and molecular biology techniques to investigate how endoplasmic reticulum (ER) stress might affect hepatic lipid metabolism in the presence of polystyrene nanoplastics (PS-NPs). Our findings suggest that PS-NPs activate the PERK-ATF4 signaling pathway, which in turn upregulates the expression of genes related to lipid synthesis via the ATF4-PPARγ/SREBP-1 pathway. This activation leads to an abnormal accumulation of lipid droplets in the liver. 4-PBA, a known ER stress inhibitor, was found to mitigate the PS-NPs-induced lipid metabolism disorder. These results demonstrate the hepatotoxic effects of PS-NPs and clarify the mechanisms of abnormal lipid metabolism induced by PS-NPs.

Alanine aminotransferase as a risk marker for new-onset metabolic dysfunction-associated fatty liver disease

In this editorial, we comment on the article by Chen et al. Metabolic dysfunction-associated fatty liver disease (MAFLD) is a global public health burden whose incidence has risen concurrently with overweight and obesity. Given its detrimental health impact, early identification of at-risk individuals is crucial. MAFLD diagnosis is based on evidence of hepatic steatosis indicated by liver biopsy, imaging, or blood biomarkers, and one of the following conditions: Overweight/ obesity, type 2 diabetes mellitus, or metabolic dysregulation. However, in large-scale epidemiological studies, liver biopsies are not feasible. The application of techniques such as ultrasonography, computed tomography, magnetic resonance imaging, and magnetic resonance spectroscopy is restricted by their limited sensitivity, low effectiveness, high costs, and need for specialized software. Blood biomarkers offer several advantages, particularly in large-scale epidemiological studies or clinical scenarios where traditional imaging techniques are impractical. Analysis of cumulative effects of excess high-normal blood alanine aminotransferase (ALT) levels of blood ALT levels could facilitate identification of at-risk patients who might not be detected through conventional imaging methods. Accordingly, investigating the utility of blood biomarkers in MAFLD should enhance early detection and monitoring, enabling timely intervention and management and improving patient outcomes.

Morroniside delays the progression of non-alcoholic steatohepatitis by promoting AMPK-mediated lipophagy

BACKGROUND

Non-alcoholic steatohepatitis (NASH), the inflammatory subtype in the progression of non-alcoholic fatty liver disease, is becoming a serious burden threatening human health, but no approved medication is available to date. Mononoside is a natural active substance derived from Cornus officinalis and has been confirmed to have great potential in regulating lipid metabolism in our previous studies. However, its effect and mechanism to inhibit the progression of NASH remains unclear.

PURPOSE

Our work aimed to explore the action of mononoside in delaying the progression of NASH and its regulatory mechanisms from the perspective of regulating lipophagy.

METHODS AND RESULTS

Male C57BL/6 mice were fed with a high-fat and high-fructose diet for 16 weeks to establish a NASH mouse model. After 8 weeks of high-fat and high-fructose feeding, these mice were administrated with different doses of morroniside. H&E staining, ORO staining, Masson staining, RNA-seq, immunoblotting, and immunofluorescence were performed to determine the effects and molecular mechanisms of morroniside in delaying the progression of NASH. In this study, we found that morroniside is effective in attenuating hepatic lipid metabolism disorders and inflammatory response activation, thereby limiting the progression from simple fatty liver to NASH in high-fat and high-fructose diet-fed mice. Mechanistically, we identified AMPK signaling as the key molecular pathway for the positive efficacy of morroniside by transcriptome sequencing. Our results revealed that morroniside maintained hepatic lipid metabolism homeostasis and inhibited NLRP3 inflammasome activation by promoting AMPKα phosphorylation-mediated lipophagy and fatty acid oxidation. Consistent results were observed in palmitic acid-treated cell models. Of particular note, silencing AMPKα both in vivo and in vitro reversed morroniside-induced lipophagy flux enhancement and NLRP3 inflammasome inhibition, emphasizing the critical role of AMPKα activation in the effect of morroniside in inhibiting NASH progression.

CONCLUSION

In summary, the present study provides strong evidence for the first time that morroniside inhibits NASH progression by promoting AMPK-dependent lipophagy and inhibiting NLRP3 inflammasome activation, suggesting that morroniside is expected to be a potential molecular entity for the development of therapeutic drugs for NASH.

Acetylated pelargonidin-3-O-glucoside alleviates hepatocyte lipid deposition through activating the AMPK-mediated lysosome-autophagy pathway and redox state

Nonalcoholic fatty liver disease (NAFLD) is a worldwide public health issue, but a widely accepted therapy is still lacking until now. Anthocyanins are natural flavonoid compounds that possess various bioactivities, but their applications are limited due to their low bioavailability and stability. Acylated anthocyanins are reported to show higher stability, whereas their effects on NAFLD are still unclear. Herein, pelargonidin-3-O-(6''-acetyl)-glucoside (Ace Pg3G) was found to dose-dependently reduce intracellular lipid droplets and triglycerides, and improve cellular oxidative stress that accompanied lipid deposition. Besides, Ace Pg3G was proved to activate AMPK phosphorylation, thus stimulating AMPK-mediated lysosome-autophagy pathway to eliminate overloaded lipid. Further study unveiled that Ace Pg3G regulated genes related to lipid metabolism downstream of AMPK to inhibit lipid synthesis and accelerate lipid oxidation. Overall, this study provided the first evidence, to our best knowledge, that Ace Pg3G ameliorated free fatty acid-induced lipid deposition in hepatocytes through regulating AMPK-mediated autophagy pathways and redox state.

Association of Nonalcoholic Fatty Liver Disease with Arterial Stiffness and its Metabolomic Profiling in Japanese Community-Dwellers

AIMS

Nonalcoholic fatty liver disease (NAFLD) is known to be associated with atherosclerosis. This study focused on upstream changes in the process by which NAFLD leads to atherosclerosis. The study aimed to confirm the association between NAFLD and the cardio-ankle vascular index (CAVI), an indicator of subclinical atherosclerosis, and explore metabolites involved in both by assessing 94 plasma polar metabolites.

METHODS

A total of 928 Japanese community-dwellers (306 men and 622 women) were included in this study. The association between NAFLD and CAVI was examined using a multivariable regression model adjusted for confounders. Metabolites commonly associated with NAFLD and CAVI were investigated using linear mixed-effects models in which batch numbers of metabolite measurements were used as a random-effects variable, and false discovery rate-adjusted p-values were calculated. To determine the extent to which these metabolites mediated the association between NAFLD and CAVI, mediation analysis was conducted.

RESULTS

NAFLD was positively associated with CAVI (coefficients [95% Confidence intervals (CI)]=0.23 [0.09-0.37]; p=0.001). A total of 10 metabolites were involved in NAFLD and CAVI, namely, branched-chain amino acids (BCAAs; valine, leucine, and isoleucine), aromatic amino acids (AAAs; tyrosine and tryptophan), alanine, proline, glutamic acid, glycerophosphorylcholine, and 4-methyl-2-oxopentanoate. Mediation analysis showed that BCAAs mediated more than 20% of the total effect in the association between NAFLD and CAVI.

CONCLUSIONS

NAFLD was associated with a marker of atherosclerosis, and several metabolites related to insulin resistance, including BCAAs and AAAs, could be involved in the process by which NAFLD leads to atherosclerosis.

Development of hepatic steatosis in male and female mule ducks after respective force-feeding programs

Male and female mule ducks were subjected to a force-feeding diet to induce liver steatosis as it is generally done only with male ducks for the production of foie gras. The different biochemical measurements indicated that the course of hepatic steatosis development was present in both sexes and associated with a huge increase in liver weight mainly due to the synthesis and accumulation of lipids in hepatocytes. In livers of male and female ducks, this lipid accumulation was associated with oxidative stress and hypoxia. However, certain specific modifications (kinetics of lipid droplet development and hepatic inflammation) indicate that female ducks may tolerate force-feeding less well, at least at the hepatic level. This is in contradiction with what is generally reported concerning hepatic steatosis induced by dietary disturbances in mammals but could be explained by the very specific conditions imposed by force-feeding. Despite this, force-feeding female ducks seems entirely feasible, provided that the final quality of the product is as good as that of the male ducks, which will remain to be demonstrated in future studies.

Therapeutic implications for sphingolipid metabolism in metabolic dysfunction-associated steatohepatitis

The prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD), a leading cause of chronic liver disease, has increased worldwide along with the epidemics of obesity and related dysmetabolic conditions characterized by impaired glucose metabolism and insulin signaling, such as type 2 diabetes mellitus (T2D). MASLD can be defined as an excessive accumulation of lipid droplets in hepatocytes that occurs when the hepatic lipid metabolism is totally surpassed. This metabolic lipid inflexibility constitutes a central node in the pathogenesis of MASLD and is frequently linked to the overproduction of lipotoxic species, increased cellular stress, and mitochondrial dysfunction. A compelling body of evidence suggests that the accumulation of lipid species derived from sphingolipid metabolism, such as ceramides, contributes significantly to the structural and functional tissue damage observed in more severe grades of MASLD by triggering inflammatory and fibrogenic mechanisms. In this context, MASLD can further progress to metabolic dysfunction-associated steatohepatitis (MASH), which represents the advanced form of MASLD, and hepatic fibrosis. In this review, we discuss the role of sphingolipid species as drivers of MASH and the mechanisms involved in the disease. In addition, given the absence of approved therapies and the limited options for treating MASH, we discuss the feasibility of therapeutic strategies to protect against MASH and other severe manifestations by modulating sphingolipid metabolism.

MASLD-Related HCC: A Comprehensive Review of the Trends, Pathophysiology, Tumor Microenvironment, Surveillance, and Treatment Options

Hepatocellular carcinoma (HCC) represents a significant burden on global healthcare systems due to its considerable incidence and mortality rates. Recent trends indicate an increase in the worldwide incidence of metabolic dysfunction-associated steatotic liver disease (MASLD) and a shift in the etiology of HCC, with MASLD replacing the hepatitis B virus as the primary contributor to new cases of HCC. MASLD-related HCC exhibits distinct characteristics compared to viral HCC, including unique immune cell profiles resulting in an overall more immunosuppressive or exhausted tumor microenvironment. Furthermore, MASLD-related HCC is frequently identified in older age groups and among individuals with cardiometabolic comorbidities. Additionally, a greater percentage of MASLD-related HCC cases occur in noncirrhotic patients compared to those with viral etiologies, hindering early detection. However, the current clinical practice guidelines lack specific recommendations for the screening of HCC in MASLD patients. The evolving landscape of HCC management offers a spectrum of therapeutic options, ranging from surgical interventions and locoregional therapies to systemic treatments, for patients across various stages of the disease. Despite ongoing debates, the current evidence does not support differences in optimal treatment modalities based on etiology. In this study, we aimed to provide a comprehensive overview of the current literature on the trends, characteristics, clinical implications, and treatment modalities for MASLD-related HCC.

Soluble CD46 as a diagnostic marker of hepatic steatosis

BACKGROUND

The increasing prevalence of metabolic dysfunction-associated steatotic liver disease (MASLD) incurs substantial morbidity, mortality and healthcare costs. Detection and clinical intervention at early stages of disease improves prognosis; however, we are currently limited by a lack of reliable diagnostic tests for population screening and monitoring responses to therapy. To address this unmet need, we investigated human invariant Natural Killer T cell (iNKT) activation by fat-loaded hepatocytes, leading to the discovery that circulating soluble CD46 (sCD46) levels accurately predict hepatic steatosis.

METHODS

sCD46 in plasma was measured using a newly developed immuno-competition assay in two independent cohorts: Prospective living liver donors (n = 156; male = 66, female = 90) and patients with liver tumours (n = 91; male = 58, female = 33). sCD46 levels were statistically evaluated as a predictor of hepatic steatosis.

FINDINGS

Interleukin-4-secreting (IL-4+) iNKT cells were over-represented amongst intrahepatic lymphocytes isolated from resected human liver samples. IL-4+ iNKT cells preferentially developed in cocultures with a fat-loaded, hepatocyte-like cell line, HepaRG. This was attributed to induction of matrix metalloproteases (MMP) in fat-loaded HepaRG cells and primary human liver organoids, which led to indiscriminate cleavage of immune receptors. Loss of cell-surface CD46 resulted in unrepressed differentiation of IL-4+ iNKT cells. sCD46 levels were elevated in patients with hepatic steatosis. Discriminatory cut-off values for plasma sCD46 were found that accurately classified patients according to histological steatosis grade.

INTERPRETATION

sCD46 is a reliable clinical marker of hepatic steatosis, which can be conveniently and non-invasively measured in serum and plasma samples, raising the possibility of using sCD46 levels as a diagnostic method for detecting or grading hepatic steatosis.

FUNDING

F.B. was supported by the Else Kröner Foundation (Award 2016_kolleg.14). G.G. was supported by the Bristol Myers Squibb Foundation for Immuno-Oncology (Award FA-19-009). N.S. was supported by a Wellcome Trust Fellowship (211113/A/18/Z). J.A.H. received funding from the European Union's Horizon 2020 research and innovation programme (Award 860003). J.M.W. received funding from the Else Kröner Foundation (Award 2015_A10).

TRIM45 facilitates NASH-progressed HCC by promoting fatty acid synthesis via catalyzing FABP5 ubiquitylation

Non-alcoholic steatohepatitis (NASH) is rapidly surpassing viral hepatitis as the primary cause of hepatocellular carcinoma (HCC). However, understanding of NASH-progressed HCC remains poor, which might impede HCC diagnosis and therapy. In this study, we aim to identify shared transcriptional changes between NASH and HCC, of which we focused on E3 ligase TRIM45. We found TRIM45 exacerbates HCC cells proliferation and metastasis in vitro and in vivo. Further transcriptome analysis revealed TRIM45 predominantly affects fatty acid metabolism and oleic acid restored impaired proliferation and metastasis of TRIM45-deficient HCC cells. IP-tandem mass spectrum and FABP5 depriving experiment indicated that TRIM45 enhance fatty acid synthesis depending on FABP5 presence. Interestingly, we found TRIM45 directly added K33-type and K63-type poly-ubiquitin chains to FABP5 NLS domain, which ultimately promoted FABP5 nuclear translocation. Nuclear FABP5 interacted with PPARγ to facilitate downstream lipid synthesis gene expression. We observed TRIM45 accelerated NASH-to-HCC transition and exacerbated both NASH and NASH-HCC with the enhanced fatty acid production in vivo. Moreover, high concentration of fatty acid increased TRIM45 expression. The established mechanism was substantiated by gene expression correlation in TCGA-LIHC. Collectively, our research revealed a common lipid reprograming process in NASH and HCC and identified the cyclical amplification of the TRIM45-FABP5-PPARγ-fatty acid axis. This signaling pathway offers potential therapeutic targets for therapeutic intervention in NASH and NASH-progressed HCC.

Positive Effects of Physical Activity on Insulin Signaling

Physical activity is integral to metabolic health, particularly in addressing insulin resistance and related disorders such as type 2 diabetes mellitus (T2DM). Studies consistently demonstrate a strong association between physical activity levels and insulin sensitivity. Regular exercise interventions were shown to significantly improve glycemic control, highlighting exercise as a recommended therapeutic strategy for reducing insulin resistance. Physical inactivity is closely linked to islet cell insufficiency, exacerbating insulin resistance through various pathways including ER stress, mitochondrial dysfunction, oxidative stress, and inflammation. Conversely, physical training and exercise preserve and restore islet function, enhancing peripheral insulin sensitivity. Exercise interventions stimulate β-cell proliferation through increased circulating levels of growth factors, further emphasizing its role in maintaining pancreatic health and glucose metabolism. Furthermore, sedentary lifestyles contribute to elevated oxidative stress levels and ceramide production, impairing insulin signaling and glucose metabolism. Regular exercise induces anti-inflammatory responses, enhances antioxidant defenses, and promotes mitochondrial function, thereby improving insulin sensitivity and metabolic efficiency. Encouraging individuals to adopt active lifestyles and engage in regular exercise is crucial for preventing and managing insulin resistance and related metabolic disorders, ultimately promoting overall health and well-being.

Microcystin-RR promote lipid accumulation through CD36 mediated signal pathway and fatty acid uptake in HepG2 cells

Microcystins (MC)-RR is a significant analogue of MC-LR, which has been identified as a hepatotoxin capable of influencing lipid metabolism and promoting the progression of liver-related metabolic diseases. However, the toxicity and biological function of MC-RR are still not well understood. In this study, the toxic effects and its role in lipid metabolism of MC-RR were investigated in hepatoblastoma cells (HepG2cells). The results demonstrated that MC-RR dose-dependently reduced cell viability and induced apoptosis. Additionally, even at low concentrations, MC-RR promoted lipid accumulation through up-regulating levels of triglyceride, total cholesterol, phosphatidylcholines and phosphatidylethaolamine in HepG2 cells, with no impact on cell viability. Proteomics and transcriptomics analysis further revealed significant alterations in the protein and gene expression profiles in HepG2 cells treated with MC-RR. Bioinformatic analysis, along with subsequent validation, indicated the upregulation of CD36 and activation of the AMPK and PI3K/AKT/mTOR in response to MC-RR exposure. Finally, knockdown of CD36 markedly ameliorated MC-RR-induced lipid accumulation in HepG2 cells. These findings collectively suggest that MC-RR promotes lipid accumulation in HepG2 cells through CD36-mediated signal pathway and fatty acid uptake. Our findings provide new insights into the hepatotoxic mechanism of MC-RR.

Starvation-resistant cavefish reveal conserved mechanisms of starvation-induced hepatic lipotoxicity

Starvation causes the accumulation of lipid droplets in the liver, a somewhat counterintuitive phenomenon that is nevertheless conserved from flies to humans. Much like fatty liver resulting from overfeeding, hepatic lipid accumulation (steatosis) during undernourishment can lead to lipotoxicity and atrophy of the liver. Here, we found that although surface populations of Astyanax mexicanus undergo this evolutionarily conserved response to starvation, the starvation-resistant cavefish larvae of the same species do not display an accumulation of lipid droplets upon starvation. Moreover, cavefish are resistant to liver atrophy during starvation, providing a unique system to explore strategies for liver protection. Using comparative transcriptomics between zebrafish, surface fish, and cavefish, we identified the fatty acid transporter slc27a2a/fatp2 to be correlated with the development of fatty liver. Pharmacological inhibition of slc27a2a in zebrafish rescues steatosis and atrophy of the liver upon starvation. Furthermore, down-regulation of FATP2 in Drosophila larvae inhibits the development of starvation-induced steatosis, suggesting the evolutionarily conserved importance of the gene in regulating fatty liver upon nutrition deprivation. Overall, our study identifies a conserved, druggable target to protect the liver from atrophy during starvation.