Nonalcoholic Fatty liver disease: pathogenesis and therapeutics from a mitochondria-centric perspective

Inhibition of Drp1-Filamin Protein Complex Prevents Hepatic Lipid Droplet Accumulation by Increasing Mitochondria-Lipid Droplet Contact

Lipid droplet (LD) accumulation in hepatocytes is one of the major symptoms associated with fatty liver disease. Mitochondria play a key role in catabolizing fatty acids for energy production through β-oxidation. The interplay between mitochondria and LD assumes a crucial role in lipid metabolism, while it is obscure how mitochondrial morphology affects systemic lipid metabolism in the liver. We previously reported that cilnidipine, an already existing anti-hypertensive drug, can prevent pathological mitochondrial fission by inhibiting protein-protein interaction between dynamin-related protein 1 (Drp1) and filamin, an actin-binding protein. Here, we found that cilnidipine and its new dihydropyridine (DHP) derivative, 1,4-DHP, which lacks Ca2+ channel-blocking action of cilnidipine, prevent the palmitic acid-induced Drp1-filamin interaction, LD accumulation and cytotoxicity of human hepatic HepG2 cells. Cilnidipine and 1,4-DHP also suppressed the LD accumulation accompanied by reducing mitochondrial contact with LD in obese model and high-fat diet-fed mouse livers. These results propose that targeting the Drp1-filamin interaction become a new strategy for the prevention or treatment of fatty liver disease.

Hepatic selective insulin resistance at the intersection of insulin signaling and metabolic dysfunction-associated steatotic liver disease

Insulin resistance (IR) is a major pathogenic factor in the progression of MASLD. In the liver, insulin suppresses gluconeogenesis and enhances de novo lipogenesis (DNL). During IR, there is a defect in insulin-mediated suppression of gluconeogenesis, but an unrestrained increase in hepatic lipogenesis persists. The mechanism of increased hepatic steatosis in IR is unclear and remains controversial. The key discrepancy is whether insulin retains its ability to directly regulate hepatic lipogenesis. Blocking insulin/IRS/AKT signaling reduces liver lipid deposition in IR, suggesting insulin can still regulate lipid metabolism; hepatic glucose metabolism that bypasses insulin's action may contribute to lipogenesis; and due to peripheral IR, other tissues are likely to impact liver lipid deposition. We here review the current understanding of insulin's action in governing different aspects of hepatic lipid metabolism under normal and IR states, with the purpose of highlighting the essential issues that remain unsettled.

Carboxymethyl Chitosan-Coated Cyanidin-3-O-Glucoside-Beared Nanonutriosomes Suppress Palmitic Acid-Induced Hepatocytes Injury

Cyanidin-3-O-glucoside (C3G) is classified as an anthocyanin (ACN) and is recognized for its remarkable antioxidant properties. Yet, the inadequate physicochemical stability of C3G restricts its potential for various biological applications. Thus, in this study, carboxymethyl chitosan (CMC)-coated nanonutriosomes (NS) were synthesized as a novel carrier for encapsulating C3G (CMC-C3G-NS) to improve C3G stability. CMC-C3G-NS exhibited a diameter of less than 200 nm along with an encouraging encapsulation efficiency exceeding 90%. Notably, the formulated CMC-C3G-NS possessed better stability under various pH, ionic, and oxygen conditions, improved controlled release properties, and higher hepatocellular uptake than uncoated particles (C3G-NS), indicating a longer retention time of C3G in a physiological environment. Of utmost significance, CMC-C3G-NS demonstrated superior alleviating effects against palmitic acid (PA)-induced oxidative hepatic damage compared to C3G-NS. Our study provided promising nanocarriers with the potential to deliver hydrophilic ACNs and controlled release properties for PA-induced hepatotoxicity alleviation.

Mitochondria-Derived Vesicles, Sterile Inflammation, and Pyroptosis in Liver Cancer: Partners in Crime or Innocent Bystanders?

Alterations in cellular signaling, chronic inflammation, and tissue remodeling contribute to hepatocellular carcinoma (HCC) development. The release of damage-associated molecular patterns (DAMPs) upon tissue injury and the ensuing sterile inflammation have also been attributed a role in HCC pathogenesis. Cargoes of extracellular vesicles (EVs) and/or EVs themselves have been listed among circulating DAMPs but only partially investigated in HCC. Mitochondria-derived vesicles (MDVs), a subpopulation of EVs, are another missing link in the comprehension of the molecular mechanisms underlying the onset and progression of HCC biology. EVs have been involved in HCC growth, dissemination, angiogenesis, and immunosurveillance escape. The contribution of MDVs to these processes is presently unclear. Pyroptosis triggers systemic inflammation through caspase-dependent apoptotic cell death and is implicated in tumor immunity. The analysis of this process, together with MDV characterization, may help capture the relationship among HCC development, mitochondrial quality control, and inflammation. The combination of immune checkpoint inhibitors (i.e., atezolizumab and bevacizumab) has been approved as a synergistic first-line systemic treatment for unresectable or advanced HCC. The lack of biomarkers that may allow prediction of treatment response and, therefore, patient selection, is a major unmet need. Herein, we overview the molecular mechanisms linking mitochondrial dysfunction, inflammation, and pyroptosis, and discuss how immunotherapy targets, at least partly, these routes.

A classical herbal formula alleviates high-fat diet induced nonalcoholic steatohepatitis (NASH) via targeting mitophagy to rehabilitate dysfunctional mitochondria, validated by UPLC-HRMS identification combined with in vivo experiment

BACKGROUND

Nonalcoholic steatohepatitis (NASH) has caused a significant burden on public health care systems, the economy and society. However, there has still been no officially approved pharmacotherapy for NASH. It has been suggested that oxidative stress and mitochondrial dysfunction play vital roles in NASH pathological progression. Shugan Xiaozhi (SG) formula, as a kind of classical herbal formula, was shown to attenuate NASH.

PURPOSE

This study aimed to explore the potential mechanisms of SG formula treating NASH.

STUDY DESIGN AND METHODS

Ultra-high-performance liquid chromatography-high resolution mass spectrometry combined with bioinformatics analysis was applied to explore the therapeutic targets and main components of SG formula. Moreover, in vivo NASH model was utilized to confirmed the therapeutic effects of SG formula. Molecular docking analysis and further validation experiments were conducted to verify the results of bioinformatics analysis.

RESULTS

The in vivo experiments confirmed SG formula significantly attenuated hepatic pathological progression and relieved oxidative stress in high-fat diet (HFD) induced - NASH model. Ultra-high-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) combined with bioinformatics analysis expounded the components of SG formula and revealed the mitochondrial regulation mechanism of SG formula treating NASH. Further in vivo experiments validated that SG formula could alleviate oxidative stress by rehabilitating the structure and function of mitochondria, which was strongly related to regulating mitophagy.

CONCLUSION

In summary, this study demonstrated that SG formula, which could attenuate NASH by regulating mitochondria and might be a potential pharmacotherapy for NASH.

Effect of herbal extracts and Saroglitazar on high-fat diet-induced obesity, insulin resistance, dyslipidemia, and hepatic lipidome in C57BL/6J mice

We evaluated the effects of select herbal extracts (Tinospora cordifolia [TC], Tinospora cordifolia with Piper longum [TC + PL], Withania somnifera [WS], Glycyrrhiza glabra [GG], AYUSH-64 [AY-64], and Saroglitazar [S]) on various parameters in a diet-induced obesity mouse model. After 12 weeks of oral administration of the herbal extracts in high-fat diet (HFD)-fed C57BL/6J mice, we analyzed plasma biochemical parameters, insulin resistance (IR), liver histology, and the expression of inflammatory and fibrosis markers, along with hepatic lipidome. We also used a 3D hepatic spheroid model to assess their impact on profibrotic gene expression. Among the extracts, TC + PL showed a significant reduction in IR, liver weight, TNF-α, IL4, IL10 expression, and hepatic lipid levels (saturated triglycerides, ceramides, lysophosphocholines, acylcarnitines, diglycerides, and phosphatidylinositol levels). Saroglitazar reversed changes in body weight, IR, plasma triglycerides, glucose, insulin, and various hepatic lipid species (fatty acids, phospholipids, glycerophospholipids, sphingolipids, and triglycerides). With the exception of GG, Saroglitazar, and other extracts protected against palmitic acid-induced fibrosis marker gene expression in the 3D spheroids. TC + PL and Saroglitazar also effectively prevented HFD-induced insulin resistance, inflammation, and specific harmful lipid species in the liver.

Cellular stress in the pathogenesis of nonalcoholic steatohepatitis and liver fibrosis

The burden of chronic liver disease is rising substantially worldwide. Fibrosis, characterized by excessive deposition of extracellular matrix proteins, is the common pathway leading to cirrhosis, and limited treatment options are available. There is increasing evidence suggesting the role of cellular stress responses contributing to fibrogenesis. This Review provides an overview of studies that analyse the role of cellular stress in different cell types involved in fibrogenesis, including hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells and macrophages.

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.

Non-alcoholic fatty liver disease: Immunological mechanisms and current treatments

Non-alcoholic fatty liver disease (NAFLD) causes significant global disease burden and is a leading cause of mortality. NAFLD induces a myriad of aberrant changes in hepatocytes at both the cellular and molecular level. Although the disease spectrum of NAFLD is widely recognised, the precise triggers for disease progression are still to be fully elucidated. Furthermore, the propagation to cirrhosis is poorly understood. Whilst some progress in terms of treatment options have been explored, an incomplete understanding of the hepatic cellular and molecular alterations limits their clinical utility. We have therefore reviewed some of the key pathways responsible for the pathogenesis of NAFLD such as innate and adaptative immunity, lipotoxicity and fibrogenesis, and highlighted current trials and treatment options for NAFLD patients.

The Role of Fucoxanthin in Non-Alcoholic Fatty Liver Disease

Chronic liver disease (CLD) has emerged as a leading cause of human deaths. It caused 1.32 million deaths in 2017, which affected men more than women by a two-to-one ratio. There are various causes of CLD, including obesity, excessive alcohol consumption, and viral infection. Among them, non-alcoholic fatty liver disease (NAFLD), one of obesity-induced liver diseases, is the major cause, representing the cause of more than 50% of cases. Fucoxanthin, a carotenoid mainly found in brown seaweed, exhibits various biological activities against NAFLD. Its role in NAFLD appears in several mechanisms, such as inducing thermogenesis in mitochondrial homeostasis, altering lipid metabolism, and promoting anti-inflammatory and anti-oxidant activities. The corresponding altered signaling pathways are the β3-adorenarine receptor (β3Ad), proliferator-activated receptor gamma coactivator (PGC-1), adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptor (PPAR), sterol regulatory element binding protein (SREBP), nuclear factor kappa B (NF-κB), mitogen-activated protein kinase (MAPK), protein kinase B (AKT), SMAD2/3, and P13K/Akt pathways. Fucoxanthin also exhibits anti-fibrogenic activity that prevents non-alcoholic steatohepatitis (NASH) development.

Hepatic Alarmins and Mitochondrial Dysfunction under Residual Hyperlipidemic Stress Lead to Irreversible NAFLD

BACKGROUND AND AIMS

Nonalcoholic fatty liver disease (NAFLD) includes a range of progressive disorders generated by excess lipid accumulation in the liver leading to hepatic steatosis and eventually fibrosis. We aimed to identify by high performance mass spectrometry-based proteomics the main signaling pathways and liver proteome changes induced by hypercholesterolemia in a rabbit atherosclerotic model that induced high accumulation of lipids in the liver.

METHODS

The effect of combined lipid-lowering drugs (statins and anti-PCSK9 monoclonal antibody) were used after the interruption of the hypercholesterolemic diet to identify also the potential mediators, such as alarmins, responsible for the irreversible NAFLD build up under the hyperlipidemic sustained stress.

RESULTS

Proteomic analysis revealed a number of proteins whose abundance was altered. They were components of metabolic pathways including fatty-acid degradation, glycolysis/gluconeogenesis, and nonalcoholic fatty liver disease. Mitochondrial dysfunction indicated alteration at the mitochondrial respiratory chain level and down-regulation of NADH: ubiquinone oxidoreductase. The expression of a majority of cytochromes (P4502E1, b5, and c) were up-regulated by lipid-lowering treatment. Long-term hyperlipidemic stress, even with a low-fat diet and lipid-lowering treatment, was accompanied by alarmin release (annexins, galectins, HSPs, HMGB1, S100 proteins, calreticulin, and fibronectin) that generated local inflammation and induced liver steatosis and aggressive fibrosis (by high abundance of galectin 3, fibronectin, and calreticulin).

CONCLUSIONS

The novel findings of this study were related to the residual effects of hyperlipidemic stress with consistent, combined lipid-lowering treatment with statin and inhibitor of PCSK9.

Vegetable Oil-Peroxidation Product 'Hydroxynonenal' Causes Hepatocyte Injury and Steatosis via Hsp70.1 and BHMT Disorders in the Monkey Liver

Hsp70.1 has a dual function as a chaperone protein and lysosomal stabilizer. In 2009, we reported that calpain-mediated cleavage of carbonylated Hsp70.1 causes neuronal death by inducing lysosomal rupture in the hippocampal CA1 neurons of monkeys after transient brain ischemia. Recently, we also reported that consecutive injections of the vegetable oil-peroxidation product 'hydroxynonenal' induce hepatocyte death via a similar cascade in monkeys. As Hsp70.1 is also related to fatty acid β-oxidation in the liver, its deficiency causes fat accumulation. The genetic deletion of betaine-homocysteine S-methyltransferase (BHMT) was reported to perturb choline metabolism, inducing a decrease in phosphatidylcholine and resulting in hepatic steatosis. Here, focusing on Hsp70.1 and BHMT disorders, we studied the mechanisms of hepatocyte degeneration and steatosis. Monkey liver tissues with and without hydroxynonenal injections were compared using proteomics, immunoblotting, immunohistochemical, and electron microscopy-based analyses. Western blotting showed that neither Hsp70.1 nor BHMT were upregulated, but an increased cleavage was observed in both. Proteomics showed a marked downregulation of Hsp70.1, albeit a two-fold increase in the carbonylated BHMT. Hsp70.1 carbonylation was negligible, in contrast to the ischemic hippocampus, which was associated with ~10-fold increments. Although histologically, the control liver showed very little lipid deposition, numerous tiny lipid droplets were seen within and around the degenerating/dying hepatocytes in monkeys after the hydroxynonenal injections. Electron microscopy showed permeabilization/rupture of lysosomal membranes, dissolution of the mitochondria and rough ER membranes, and proliferation of abnormal peroxisomes. It is probable that the disruption of the rough ER caused impaired synthesis of the Hsp70.1 and BHMT proteins, while impairment of the mitochondria and peroxisomes contributed to the sustained generation of reactive oxygen species. In addition, hydroxynonenal-induced disorders facilitated degeneration and steatosis in the hepatocytes.

Investigating associations between blood metabolites, later life brain imaging measures, and genetic risk for Alzheimer's disease

BACKGROUND

Identifying blood-based signatures of brain health and preclinical pathology may offer insights into early disease mechanisms and highlight avenues for intervention. Here, we systematically profiled associations between blood metabolites and whole-brain volume, hippocampal volume, and amyloid-β status among participants of Insight 46-the neuroscience sub-study of the National Survey of Health and Development (NSHD). We additionally explored whether key metabolites were associated with polygenic risk for Alzheimer's disease (AD).

METHODS

Following quality control, levels of 1019 metabolites-detected with liquid chromatography-mass spectrometry-were available for 1740 participants at age 60-64. Metabolite data were subsequently clustered into modules of co-expressed metabolites using weighted coexpression network analysis. Accompanying MRI and amyloid-PET imaging data were present for 437 participants (age 69-71). Regression analyses tested relationships between metabolite measures-modules and hub metabolites-and imaging outcomes. Hub metabolites were defined as metabolites that were highly connected within significant (p_FDR < 0.05) modules or were identified as a hub in a previous analysis on cognitive function in the same cohort. Regression models included adjustments for age, sex, APOE genotype, lipid medication use, childhood cognitive ability, and social factors. Finally, associations were tested between AD polygenic risk scores (PRS), including and excluding the APOE region, and metabolites and modules that significantly associated (p_FDR < 0.05) with an imaging outcome (N = 1638).

RESULTS

In the fully adjusted model, three lipid modules were associated with a brain volume measure (p_FDR < 0.05): one enriched in sphingolipids (hippocampal volume: ß = 0.14, 95% CI = [0.055,0.23]), one in several fatty acid pathways (whole-brain volume: ß =  - 0.072, 95%CI = [- 0.12, - 0.026]), and another in diacylglycerols and phosphatidylethanolamines (whole-brain volume: ß =  - 0.066, 95% CI = [- 0.11, - 0.020]). Twenty-two hub metabolites were associated (p_FDR < 0.05) with an imaging outcome (whole-brain volume: 22; hippocampal volume: 4). Some nominal associations were reported for amyloid-β, and with an AD PRS in our genetic analysis, but none survived multiple testing correction.

CONCLUSIONS

Our findings highlight key metabolites, with functions in membrane integrity and cell signalling, that associated with structural brain measures in later life. Future research should focus on replicating this work and interrogating causality.

Phytochemical gallic acid alleviates nonalcoholic fatty liver disease via AMPK-ACC-PPARa axis through dual regulation of lipid metabolism and mitochondrial function

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) usually includes NAFL called simple hepatosteatosis and nonalcoholic steatohepatitis (NASH) called more steatohepatitis. The latter is a leading pathogenic promotor of hepatocellular carcinoma (HCC). Phytochemical gallic acid (GA) has been proved to exert positive efficacy in HCC in our work, but it remains unclear whether its hepatoprotective effect attributes to the controlled transition from simple steatosis to steatohepatitis.

PURPOSE

This work aims to provide mechanistic evidence that the therapeutic application of GA in NAFLD is indispensable for GA-meliorated NASH progression.

METHODS

The high-fat diet (HFD)-fed mice and palmitic acid (PA) and oleic acid (OA)-treated hepatocytes were used collectively in this study. Bioinformatic analysis, clinical subjects, RNA-Seq, molecular docking, and confirmatory experiments were performed comprehensively to uncover the pathological link between the AMPK-ACC-PPARα axis and the treatment of NAFLD.

RESULTS

By analyzing the clinical subjects and GEO database, we find a close link between the activation of AMPK-ACC-PPARα axis and the progression of NAFLD in human fatty liver. Subsequent assays show that GA exhibits pharmacological activation of AMPK, reprogramming lipid metabolism, and reversing mitochondrial function in cellular and murine fatty liver models. AMPK activation conferred substantial protection against murine NASH and fibrosis in the context of HFD-induced NAFLD. In contrast, silencing AMPK badly aggravates lipid deposition in hepatocytes, boosting NASH and NAFLD-associated HCC progression. The in silico docking, in vitro surface plasmon resonance and in vivo cellular thermal shift assay collectively reveal that GA directly interacts with AMPKα, which inactivates the ACC-PPARα axis signaling. Notably, GA repairs the liver damage, lipotoxicity, and mitochondrial respiratory capacity caused by excessive mtROS, while showing minimal effects in other major organs in mice.

CONCLUSION

Our work identifies GA as an important suppressor of NAFLD-HCC progression, and underscores the AMPK-ACC-PPARα signal axis as a potential therapeutic target for NAFLD treatment.

Potential Therapeutic Implication of Herbal Medicine in Mitochondria-Mediated Oxidative Stress-Related Liver Diseases

Mitochondria are double-membrane organelles that play a role in ATP synthesis, calcium homeostasis, oxidation-reduction status, apoptosis, and inflammation. Several human disorders have been linked to mitochondrial dysfunction. It has been found that traditional therapeutic herbs are effective on alcoholic liver disease (ALD) and nonalcoholic fatty liver disease (NAFLD) which are leading causes of liver cirrhosis and hepatocellular carcinoma. The generation of reactive oxygen species (ROS) in response to oxidative stress is caused by mitochondrial dysfunction and is considered critical for treatment. The role of oxidative stress, lipid toxicity, and inflammation in NAFLD are well known. NAFLD is a chronic liver disease that commonly progresses to cirrhosis and chronic liver disease, and people with obesity, insulin resistance, diabetes, hyperlipidemia, and hypertension are at a higher risk of developing NAFLD. NAFLD is associated with a number of pathological factors, including insulin resistance, lipid metabolic dysfunction, oxidative stress, inflammation, apoptosis, and fibrosis. As a result, the improvement in steatosis and inflammation is enough to entice researchers to look into liver disease treatment. However, antioxidant treatment has not been very effective for liver disease. Additionally, it has been suggested that the beneficial effects of herbal medicines on immunity and inflammation are governed by various mechanisms for lipid metabolism and inflammation control. This review provided a summary of research on herbal medicines for the therapeutic implementation of mitochondria-mediated ROS production in liver disease as well as clinical applications through herbal medicine. In addition, the pathophysiology of common liver disorders such as ALD and NAFLD would be investigated in the role that mitochondria play in the process to open new therapeutic avenues in the management of patients with liver disease.

Walnut Prevents Cognitive Impairment by Regulating the Synaptic and Mitochondrial Dysfunction via JNK Signaling and Apoptosis Pathway in High-Fat Diet-Induced C57BL/6 Mice

This study was conducted to evaluate the protective effect of Juglans regia (walnut, Gimcheon 1ho cultivar, GC) on high-fat diet (HFD)-induced cognitive dysfunction in C57BL/6 mice. The main physiological compounds of GC were identified as pedunculagin/casuariin isomer, strictinin, tellimagrandin I, ellagic acid-O-pentoside, and ellagic acid were identified using UPLC Q-TOF/MS analysis. To evaluate the neuro-protective effect of GC, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 2′,7′-dichlorodihydrofluorecein diacetate (DCF-DA) analysis were conducted in H₂O₂ and high glucose-induced neuronal PC12 cells and hippocampal HT22 cells. GC presented significant cell viability and inhibition of reactive oxygen species (ROS) production. GC ameliorated behavioral and memory dysfunction through Y-maze, passive avoidance, and Morris water maze tests. In addition, GC reduced white adipose tissue (WAT), liver fat mass, and serum dyslipidemia. To assess the inhibitory effect of antioxidant system deficit, lipid peroxidation, ferric reducing antioxidant power (FRAP), and advanced glycation end products (AGEs) were conducted. Administration of GC protected the antioxidant damage against HFD-induced diabetic oxidative stress. To estimate the ameliorating effect of GC, acetylcholine (ACh) level, acetylcholinesterase (AChE) activity, and expression of AChE and choline acetyltransferase (ChAT) were conducted, and the supplements of GC suppressed the cholinergic system impairment. Furthermore, GC restored mitochondrial dysfunction by regulating the mitochondrial ROS production and mitochondrial membrane potential (MMP) levels in cerebral tissues. Finally, GC ameliorated cerebral damage by synergically regulating the protein expression of the JNK signaling and apoptosis pathway. These findings suggest that GC could provide a potential functional food source to improve diabetic cognitive deficits and neuronal impairments.

Mitochondrial Dysfunction Plays Central Role in Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a global pandemic that affects one-quarter of the world’s population. NAFLD includes a spectrum of progressive liver disease from steatosis to nonalcoholic steatohepatitis (NASH), fibrosis, and cirrhosis and can be complicated by hepatocellular carcinoma. It is strongly associated with metabolic syndromes, obesity, and type 2 diabetes, and it has been shown that metabolic dysregulation is central to its pathogenesis. Recently, it has been suggested that metabolic- (dysfunction) associated fatty liver disease (MAFLD) is a more appropriate term to describe the disease than NAFLD, which puts increased emphasis on the important role of metabolic dysfunction in its pathogenesis. There is strong evidence that mitochondrial dysfunction plays a significant role in the development and progression of NAFLD. Impaired mitochondrial fatty acid oxidation and, more recently, a reduction in mitochondrial quality, have been suggested to play a major role in NAFLD development and progression. In this review, we provide an overview of our current understanding of NAFLD and highlight how mitochondrial dysfunction contributes to its pathogenesis in both animal models and human subjects. Further we discuss evidence that the modification of mitochondrial function modulates NAFLD and that targeting mitochondria is a promising new avenue for drug development to treat NAFLD/NASH.

Acetyl-CoA metabolism drives epigenome change and contributes to carcinogenesis risk in fatty liver disease

BACKGROUND

The incidence of non-alcoholic fatty liver disease (NAFLD)-associated hepatocellular carcinoma (HCC) is increasing worldwide, but the steps in precancerous hepatocytes which lead to HCC driver mutations are not well understood. Here we provide evidence that metabolically driven histone hyperacetylation in steatotic hepatocytes can increase DNA damage to initiate carcinogenesis.

METHODS

Global epigenetic state was assessed in liver samples from high-fat diet or high-fructose diet rodent models, as well as in cultured immortalized human hepatocytes (IHH cells). The mechanisms linking steatosis, histone acetylation and DNA damage were investigated by computational metabolic modelling as well as through manipulation of IHH cells with metabolic and epigenetic inhibitors. Chromatin immunoprecipitation and next-generation sequencing (ChIP-seq) and transcriptome (RNA-seq) analyses were performed on IHH cells. Mutation locations and patterns were compared between the IHH cell model and genome sequence data from preneoplastic fatty liver samples from patients with alcohol-related liver disease and NAFLD.

RESULTS

Genome-wide histone acetylation was increased in steatotic livers of rodents fed high-fructose or high-fat diet. In vitro, steatosis relaxed chromatin and increased DNA damage marker γH2AX, which was reversed by inhibiting acetyl-CoA production. Steatosis-associated acetylation and γH2AX were enriched at gene clusters in telomere-proximal regions which contained HCC tumour suppressors in hepatocytes and human fatty livers. Regions of metabolically driven epigenetic change also had increased levels of DNA mutation in non-cancerous tissue from NAFLD and alcohol-related liver disease patients. Finally, genome-scale network modelling indicated that redox balance could be a key contributor to this mechanism.

CONCLUSIONS

Abnormal histone hyperacetylation facilitates DNA damage in steatotic hepatocytes and is a potential initiating event in hepatocellular carcinogenesis.

SGLT-2 inhibitors and GLP-1 receptor agonists in metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a chronic condition that affects nearly one billion people globally, characterized by triacylglycerol accumulation in the liver as a consequence of metabolic abnormalities (obesity and impaired glucose regulation). Low-grade inflammation, oxidative stress, mitochondrial dysfunction, and dysbiosis in gut microbiota are involved in the etiology of MAFLD, and both cardiovascular events and hepatic complications are the long-term consequences. In the absence of approved therapies for this condition, sodium-glucose cotransporter 2 inhibitors (SGLT-2 Is) and glucagon-like peptide 1 receptor agonists (GLP-1 RAs) have the specific advantage of lowering body weight and providing cardiovascular benefits. Here, we discuss potential roles for SGLT-2 Is and GLP-1 RAs in the prevention and treatment of intrahepatic triacylglycerol accumulation and associated inflammation and/or fibrosis.

Empagliflozin-Enhanced Antioxidant Defense Attenuates Lipotoxicity and Protects Hepatocytes by Promoting FoxO3a- and Nrf2-Mediated Nuclear Translocation via the CAMKK2/AMPK Pathway

Lipotoxicity is an important factor in the development and progression of nonalcoholic steatohepatitis. Excessive accumulation of saturated fatty acids can increase the substrates of the mitochondrial electron transport chain in hepatocytes and cause the generation of reactive oxygen species, resulting in oxidative stress, mitochondrial dysfunction, loss of mitochondrial membrane potential, impaired triphosphate (ATP) production, and fracture and fragmentation of mitochondria, which ultimately leads to hepatocellular inflammatory injuries, apoptosis, and necrosis. In this study, we systematically investigated the effects and molecular mechanisms of empagliflozin on lipotoxicity in palmitic acid-treated LO2 cell lines. We found that empagliflozin protected hepatocytes and inhibited palmitic acid-induced lipotoxicity by reducing oxidative stress, improving mitochondrial functions, and attenuating apoptosis and inflammation responses. The mechanistic study indicated that empagliflozin significantly activated adenosine 5'-monophosphate (AMP)-activated protein kinase alpha (AMPKα) through Calcium/Calmodulin dependent protein kinase kinase beta (CAMKK2) instead of liver kinase B1 (LKB1) or TGF-beta activated kinase (TAK1). The activation of empagliflozin on AMPKα not only promoted FoxO3a phosphorylation and thus forkhead box O 3a (FoxO3a) nuclear translocation, but also promoted Nrf2 nuclear translocation. Furthermore, empagliflozin significantly upregulated the expressions of antioxidant enzymes superoxide dismutase (SOD) and HO-1. In addition, empagliflozin did not attenuate lipid accumulation at all. These results indicated that empagliflozin mitigated lipotoxicity in saturated fatty acid-induced hepatocytes, likely by promoting antioxidant defense instead of attenuating lipid accumulation through enhanced FoxO3a and Nrf2 nuclear translocation dependent on the CAMKK2/AMPKα pathway. The CAMKK2/AMPKα pathway might serve as a promising target in treatment of lipotoxicity in nonalcoholic steatohepatitis.

Exercise during weight-loss improves hepatic mitophagy

Non-alcoholic fatty liver disease (NAFLD) has recently become a public health concern concurrent with the obesity crisis. Previous work has shown aberrant mitochondrial content/quality and autophagy in models of NAFLD, whereas exercise is known to improve these derangements. The purpose of this study was to examine the effect of different weight-loss modalities on hepatic mitochondrial content, autophagy and mitophagy in NAFLD. Forty-eight male C57BL/6J mice were divided into 1 of 4 groups: low fat diet (LFD, 10% fat, 18 weeks), high fat diet (HFD, 60% fat diet, 18 weeks), weight-loss by diet (D, 60% fat diet for 10 weeks then 10% fat diet for 8 weeks) or weight-loss by diet and physical activity (D/PA, 60% fat diet for 10 weeks, then 10% fat diet plus a running wheel for 8 weeks). Immunoblot data were analyzed by one-way analysis of variance (ANOVA) with significance denoted at p ​< ​0.05. COX-IV protein contents were approximately 50% less in HFD compared to LFD. D/PA had 50% more BNIP3 compared to HFD. PINK1 content was 40% higher in D and D/PA compared to LFD. P-PARKIN/PARKIN levels were 40% lower in HFD, D, and D/PA compared to LFD. Whereas p-Ub^Ser65 was 3-fold higher in HFD. LC3II/I ratio was 50% greater in HFD and D/PA, yet p62 protein content was 2.5 fold higher in HFD. High-fat diet causes disruptions in markers of mitochondrial quality control. Physical activity combined with diet were able to ameliorate these derangements and seemingly improve hepatic mitochondrial quality above control values.

Non-alcoholic Fatty Liver Disease and Steatohepatitis: Risk Factors and Pathophysiology

Non-alcoholic fatty liver disease (NAFLD) and its progressive subtype non-alcoholic steatohepatitis (NASH) are the most prevalent liver diseases, often leading to hepatocellular carcinoma (HCC). This review aims to describe the present knowledge of the risk factors responsible for the development of NAFLD and NASH. I performed a literature review identifying studies focusing on the complex pathogenic pathway and risk factors of NAFLD and steatohepatitis. The relationship between NAFLD and metabolic syndrome is well established and widely recognized. Obesity, dyslipidemia, type 2 diabetes, hypertension, and insulin resistance are the most common risk factors associated with NAFLD. Among the components of metabolic syndrome, current evidence strongly suggests obesity and type 2 diabetes as risk factors of NASH and HCC. However, other elements, namely gender divergences, ethnicity, genetic factors, participation of innate immune system, oxidative stress, apoptotic pathways, and adipocytokines, take a leading role in the onset and promotion of NAFLD. Pathophysiological mechanisms that are responsible for NAFLD development and subsequent progression to NASH are insulin resistance and hyperinsulinemia, oxidative stress, hepatic stellate cell (HSC) activation, cytokine/adipokine signaling pathways, and genetic and environmental factors. Major pathophysiological findings of NAFLD are dysfunction of adipose tissue through the enhanced flow of free fatty acids (FFAs) and release of adipokines, and altered gut microbiome that generate proinflammatory signals and cause NASH progression. Understanding the pathophysiology and risk factors of NAFLD and NASH; this review could provide insight into the development of therapeutic strategies and useful diagnostic tools.

Mitochondrial Dysfunction and Acute Fatty Liver of Pregnancy

The liver is one of the richest organs in mitochondria, serving as a hub for key metabolic pathways such as β-oxidation, the tricarboxylic acid (TCA) cycle, ketogenesis, respiratory activity, and adenosine triphosphate (ATP) synthesis, all of which provide metabolic energy for the entire body. Mitochondrial dysfunction has been linked to subcellular organelle dysfunction in liver diseases, particularly fatty liver disease. Acute fatty liver of pregnancy (AFLP) is a life-threatening liver disorder unique to pregnancy, which can result in serious maternal and fetal complications, including death. Pregnant mothers with this disease require early detection, prompt delivery, and supportive maternal care. AFLP was considered a mysterious illness and though its pathogenesis has not been fully elucidated, molecular research over the past two decades has linked AFLP to mitochondrial dysfunction and defects in fetal fatty-acid oxidation (FAO). Due to deficient placental and fetal FAO, harmful 3-hydroxy fatty acid metabolites accumulate in the maternal circulation, causing oxidative stress and microvesicular fatty infiltration of the liver, resulting in AFLP. In this review, we provide an overview of AFLP and mitochondrial FAO followed by discussion of how altered mitochondrial function plays an important role in the pathogenesis of AFLP.

Targeting mitochondria in dermatological therapy: Beyond oxidative damage and skin aging

INTRODUCTION

The analysis of the role of the mitochondria in oxidative damage and skin aging is a significant aspect of dermatological research. Mitochondria generate most reactive oxygen species (ROS); however, excessive ROS are cytotoxic and DNA-damaging and promote (photo-)aging. ROS also possesses key physiological and regulatory functions and mitochondrial dysfunction is prominent in several skin diseases including skin cancers. Although many standard dermatotherapeutics modulate mitochondrial function, dermatological therapy rarely targets the mitochondria. Accordingly, there is a rationale for "mitochondrial dermatology"-based approaches to be applied to therapeutic research.

AREAS COVERED

This paper examines the functions of mitochondria in cutaneous physiology beyond energy (ATP) and ROS production. Keratinocyte differentiation and epidermal barrier maintenance, appendage morphogenesis and homeostasis, photoaging and skin cancer are considered. Based on related PubMed search results, the paper evaluates thyroid hormones, glucocorticoids, Vitamin D3 derivatives, retinoids, cannabinoid receptor agonists, PPARγ agonists, thyrotropin, and thyrotropin-releasing hormone as instructive lead compounds. Moreover, the mitochondrial protein MPZL3 as a promising new drug target for future "mitochondrial dermatology" is highlighted.

EXPERT OPINION

Future dermatological therapeutic research should have a mitochondrial medicine emphasis. Focusing on selected lead agents, protein targets, in silico drug design, and model diseases will fertilize a mito-centric approach.

Mitochondrial depletion of glutaredoxin 2 induces metabolic dysfunction-associated fatty liver disease in mice

Glutaredoxin 2 (Grx2) is a glutathione-dependent oxidoreductase that facilitates glutathionylation/de-glutathionylation of target proteins. The main variants of Grx2 are the mitochondrial Grx2a and the cytosolic Grx2c. The aim of this study was to investigate the specific role of mitochondrial Grx2 in vivo using a mitochondrial Grx2 depleted (mGD) mouse model. mGD mice displayed an altered mitochondrial morphology and functioning. Furthermore, the lack of Grx2 in the mitochondrial compartment is responsible for increased blood lipid levels under a normal diet, a metabolic dysfunction-associated fatty liver disease (MAFLD) phenotype and a decreased glycogen storage capacity. In addition, depleting Grx2a leads to an alteration in abundance and in glutathionylation pattern of different mitochondrial enzymes, highlighting the selective role of Grx2 in the regulation of metabolic pathways. Overall, our findings identify the involvement of mitochondrial Grx2a in the regulation of cell metabolism and highlight a previously unknown association between Grx2 and MAFLD.

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Mitochondrial Grx2 depleted (mGD) mice display mitochondrial impairment.

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mGD mice show alterations in lipid metabolism and glycogen storage in the liver.

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Upon Grx2 deficiency the glutathionylation pattern of metabolic enzymes changes

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Mitochondrial Grx2 depletion is associated with MAFLD development

Hepatic Steatosis in the Mouse Model of Wilson Disease Coincides with a Muted Inflammatory Response

Wilson disease (WND) is caused by inactivation of the copper transporter ATP7B and copper accumulation in tissues. WND presentations vary from liver steatosis to inflammation, fibrosis, and liver failure. Diets influence the liver phenotype in WND, but findings are inconsistent. To better understand the impact of excess calories on liver phenotype in WND, the study compared C57BL/6J Atp7b-/- and C57BL/6J mice fed for 12 weeks with Western diet or normal chow. Serum and liver metabolites, body fat content, liver histology, hepatic proteome, and copper content were analyzed. Wild-type and Atp7b-/- livers showed striking similarities in their responses to Western diet, most notably down-regulation of cholesterol biosynthesis, altered nuclear receptor signaling, and changes in cytoskeleton. Western diet increased body fat content and induced liver steatosis in males and females regardless of genotype; however, the effects were less pronounced in Atp7b-/- mice compared with those in the wild type mice. Although hepatic copper remained elevated in Atp7b-/- mice, liver inflammation was reduced. The diet diminished signaling by Rho GTPases, integrin, IL8, and reversed changes in cell cycle machinery and cytoskeleton. Overall, high calories decreased inflammatory response in favor of steatosis without improving markers of cell viability. Similar changes of cellular pathways during steatosis development in wild-type and Atp7b-/- mice explain histologic overlap between WND and non-alcoholic fatty liver disease despite opposite copper changes in these disorders.

Roles of Therapeutic Bioactive Compounds in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is due to poor prognosis and lack of availability of effective treatment. Novel therapeutic strategies will be the fine tuning of intracellular ROS signaling to effectively deprive cells of ROS-induced tumor-promoting events. This review discusses the generation of ROS, the major signaling their modulation in therapeutics. We explore some of the major pathways involved in HCC, which include the VEGF, MAPK/ERK, mTOR, FGF, and Ser/Thr kinase pathways. In this review, we study cornerstone on natural bioactive compounds with their effect on hepatocarcinomas. Furthermore, we focus on oxidative stress and FDA-approved signaling pathway inhibitors, along with chemotherapy and radiotherapy enhancers which with early evidence of success. While more in vivo testing is required to confirm the findings presented here, our findings will aid future nonclinical, preclinical, and clinical studies with these compounds, as well as inspire medicinal chemistry scientists to conduct appropriate research on this promising natural compound and their derivatives.

Favorable effect of sodium-glucose cotransporter 2 inhibitor, dapagliflozin, on non-alcoholic fatty liver disease compared with pioglitazone

AIMS/INTRODUCTION

Sodium-glucose cotransporter 2 inhibitors, as well as thiazolidines, suppress nonalcoholic fatty liver disease (NAFLD); however, few comparative studies have been reported. Dapagliflozin has shown non-inferiority compared with pioglitazone for glycemic control, and superiority regarding weight reduction in patients with type 2 diabetes. We carried out a secondary analysis for the favorable effects of sodium-glucose cotransporter inhibitors for NAFLD.

MATERIALS AND METHODS

In this multicenter, open-label, prospective, randomized, parallel-group comparison trial, patients taking pioglitazone for ≥12 weeks were randomly switched to dapagliflozin or continued pioglitazone for a further 24 weeks. The fatty liver index (FLI), consisting of body mass index, triglycerides, waist circumference and γ-glutamyl transpeptidase, was used for the evaluation of NAFLD.

RESULTS

A total of 53 participants with NAFLD (27 dapagliflozin; 26 pioglitazone) were included in this analysis. FLI decreased significantly in the dapagliflozin group (48.7 ± 23.4 to 42.1 ± 23.9) compared with the pioglitazone group (49.0 ± 26.1 to 51.1 ± 25.8; P < 0.01). Multiple linear regression analysis showed that the changes in FLI had a significantly positive correlation with changes in glycated hemoglobin (P = 0.03) and insulin level (P < 0.01) in the dapagliflozin group.

CONCLUSION

Dapagliflozin might be more beneficial than pioglitazone in patients with NAFLD. Improvements in FLI would be closely related to glycemic control.

The effects of melatonin therapy on the treatment of patients with Non-alcoholic steatohepatitis: A systematic review and Meta-analysis on clinical trial studies

Melatonin has shown promising effects in controlling the progress of non-alcoholic fatty liver disease (NAFLD), introducing it as a possible candidate for NAFLD treatment. In this context, the current study is aimed to evaluate melatonin's effect on the plasma levels of Gamma-glutamyl transpeptidase, cholesterol, triglyceride, and liver aminotransferases in NAFLD patients. NAFLD and melatonin, as well as their related terms, were searched in electronic databases, until May 1st, 2020. The initial search identified 1152 studies. Considering inclusion and exclusion criteria, the final seven articles were included in the study. The methodology of the articles was assessed by the Newcastle-Ottawa Scale. Alanine transaminase levels were significantly lowered with melatonin treatment but not earlier than the 4th week (P = 0.010 and 0.519, respectively). Aspartate aminotransferase levels didn't show significant alteration before 4 weeks, although exhibiting substantial decline in total (P = 0.697 and 0.008, respectively). Alkaline phosphatase changes under 4 weeks of follow-up were not significant (P = 0.3), however, it decreased significantly in total (P = 0.006). A significant decline was detected in triglyceride levels after melatonin treatment (P = 0.015). There was a significant reduction in cholesterol levels (P = 0.005). Gamma-glutamyl transpeptidase levels were also significantly different after the administration of melatonin (P < 0.001). Melatonin could reduce the progress of NAFLD. It might also decrement hepatic function parameters. Thus, it could be used for managing NAFLD and possibly as part of the treatment plan for patients with NAFLD.

The role of pioglitazone in antioxidant, anti-inflammatory, and insulin sensitivity in a high fat-carbohydrate diet-induced rat model of insulin resistance

We explored the cascade effects of a high fat-carbohydrate diet (HFCD) and pioglitazone (an anti-diabetic therapy used to treat type 2 diabetes mellitus (T2DM)) on lipid profiles, oxidative stress/antioxidant, insulin, and inflammatory biomarkers in a rat model of insulin resistance. Sixty albino rats (80-90 g) were randomly divided into three dietary groups; 1) standard diet; 2) HFCD diet for 12 weeks to induce an in vivo model of insulin resistance; and 3) HFCD diet plus pioglitazone. Blood and tissue samples were taken to assess hepatic function, lipid profiles, oxidative biomarkers, malondialdehyde (MDA) levels, antioxidant defense biomarkers, including reduced glutathione (GSH), superoxide dismutase (SOD), and the inflammatory markers interleukin-6 (IL-6) and tumor necrotic factor (TNF-α). HFCD-fed rats had significantly (P≤0.05) increased serum triacylglycerol (TG), total cholesterol (TC), low-density lipoprotein (LDL), alanine transaminase (ALT), and bilirubin levels, but decreased high-density lipoprotein (HDL) levels compared with the normal group. Moreover, serum leptin, resistin, TNF-α, and IL-6 levels were increased significantly in HFCD animals compared with controls. Similarly, HFCD-induced insulin resistance caused antioxidant and cytokine disturbances, which are important therapy targets for pioglitazone. Importantly, administration of this drug ameliorated these changes, normalized leptin and resistin and inflammatory markers by reducing TNF-α levels. Metabolic cascades of elevated lipid profiles, oxidative stress, insulin, and inflammatory biomarkers are implicated in insulin resistance progression. HFCD induced metabolic cascades comprising hypertriglyceridemia, hyperglycemia, insulin resistance, obesity-associated hormones, and inflammatory biomarkers may be alleviated using pioglitazone.

Serum iron and risk of nonalcoholic fatty liver disease and advanced hepatic fibrosis in US adults

Epidemiological evidence on the relationship between serum iron and liver diseases is limited. This study aims to investigate whether serum iron is associated with nonalcoholic fatty liver disease (NAFLD) and advanced hepatic fibrosis (AHF). Cross-sectional data for adults aged ≥ 18 years who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 were analyzed. Odds ratio (ORs) and 95% confidence intervals (CIs) of NAFLD and AHF associated with serum iron were estimated using multivariable logistic regression models. A total of 18,031 males and 18,989 females were included in the analysis. After multivariable adjustment for potential confounders, serum iron was significantly and inversely associated with NAFLD in both genders (P-trend < 0.001) and AHF in females (P-trend = 0.018). Compared to the bottom quartile, those in higher quartiles of serum iron had no significant ORs for AHF in males, but the trend across the quartiles was significant (P-trend = 0.046). In conclusion, higher serum iron level was associated with lower risk of NAFLD in males and females, and with lower risk of AHF in females but not in males. No significant racial/ethnical differences in these associations were observed.

Role of Steroid Hormones in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease and may progress to cirrhosis or even hepatocellular carcinoma. A number of steroid hormones are important regulators of lipid homeostasis through fine tuning the expression of genes related to lipid synthesis, export, and metabolism. Dysregulation of such pathways has been implicated in the pathogenesis of NAFLD. The aim of this review is to clarify the potential impact of steroid hormones on NAFLD. We also highlight potential interventions through modulating steroid hormone levels or the activities of their cognate receptors as therapeutic strategies for preventing NAFLD.

Modulation of vascular contraction via soluble guanylate cyclase signaling in a novel ex vivo method using rat precision-cut liver slices

Fibrotic processes in the liver of non-alcoholic steatohepatitis (NASH) patients cause microcirculatory dysfunction in the organ which increases blood vessel resistance and causes portal hypertension. Assessing blood vessel function in the liver is challenging, necessitating the development of novel methods in normal and fibrotic tissue that allow for drug screening and translation toward pre-clinical settings. Cultures of precision cut liver slices (PCLS) from normal and fibrotic rat livers were used for blood vessel function analysis. Live recording of vessel diameter was used to assess the response to endothelin-1, serotonin and soluble guanylate cyclase (sGC) activation. A cascade of contraction and relaxation events in response to serotonin, endothelin-1, Ketanserin and sGC activity could be established using vessel diameter analysis of rat PCLS. Both the sGC activator BI 703704 and the sGC stimulator Riociguat prevented serotonin-induced contraction in PCLS from naive rats. By contrast, PCLS cultures from the rat CCl4 NASH model were only responsive to the sGC activator, thus establishing that the sGC enzyme is rendered non-responsive to nitric oxide under oxidative stress found in fibrotic livers. The role of the sGC pathway for vessel relaxation of fibrotic liver tissue was identified in our model. The obtained data shows that the inhibitory capacities on vessel contraction of sGC compounds can be translated to published preclinical data. Altogether, this novel ex vivo PCLS method allows for the differentiation of drug candidates and the translation of therapeutic approaches towards the clinical use.

Malvidin-3-O-Glucoside from Blueberry Ameliorates Nonalcoholic Fatty Liver Disease by Regulating Transcription Factor EB-Mediated Lysosomal Function and Activating the Nrf2/ARE Signaling Pathway

Nonalcoholic fatty liver disease (NAFLD) has become a universal health issue, whereas there is still a lack of widely accepted therapy until now. Clinical research studies have shown that blueberry could effectively regulate the lipid metabolism, thereby improving obesity-related metabolic syndromes; however, the specific active substances and mechanisms remain unclear. Herein, the effects of the major 10 kinds of anthocyanins from blueberry against NAFLD were investigated using an free fatty acid (FFA)-induced cell model. Among these anthocyanins, malvidin-3-O-glucoside (M3G) and malvidin-3-O-galactoside (M3Ga) could remarkably ameliorate FFA-induced lipid accumulation. Besides, M3G and M3Ga also inhibited oxidative stress via suppressing reactive oxygen species and superoxide anion overproduction, increasing glutathione levels, and enhancing activities of antioxidant enzymes. Further studies unveiled that the representative anthocyanin M3G-upregulated transcription factor EB (TFEB)-mediated lysosomal function possibly interacted with TFEB and activated the Nrf2/ARE (antioxidant responsive element) signaling pathway. Overall, this study enriched the knowledge about the health-promoting effects of blueberry anthocyanins against NAFLD and provided ideas for the development of functional foods of blueberry anthocyanins.

Maternal high-fat high-sucrose diet and gestational exercise modulate hepatic fat accumulation and liver mitochondrial respiratory capacity in mothers and male offspring

BACKGROUND

Maternal high-caloric nutrition and related gestational diabetes mellitus (GDM) are associated with a high-risk for developing metabolic complications later in life and in their offspring. In contrast, exercise is recognized as a non-pharmacological strategy against metabolic dysfunctions associated to lifestyle disorders. Therefore, we investigated whether gestational exercise delays the development of metabolic alterations in GDM mothers later in life, but also protects 6-week-old male offspring from adverse effects of maternal diet.

METHODS

Female Sprague-Dawley rats were fed with either control (C) or high-fat high-sucrose (HFHS) diet to induce GDM and submitted to gestational exercise during the 3 weeks of pregnancy. Male offspring were sedentary and fed with C-diet.

RESULTS

Sedentary HFHS-fed dams exhibited increased gestational body weight gain (p < 0.01) and glucose intolerance (p < 0.01), characteristic of GDM. Their offspring had normal glucose metabolism, but increased early-age body weight, which was reverted by gestational exercise. Gestational exercise also reduced offspring hepatic triglycerides accumulation (p < 0.05) and improved liver mitochondrial respiration capacity (p < 0.05), contributing to the recovery of liver bioenergetics compromised by maternal HFHS diet. Interestingly, liver mitochondrial respiration remained increased by gestational exercise in HFHS-fed dams despite prolonged HFHS consumption and exercise cessation.

CONCLUSIONS

Gestational exercise can result in liver mitochondrial adaptations in GDM animals, which can be preserved even after the exercise program cessation. Exposure to maternal GDM programs liver metabolic setting of male offspring, whereas gestational exercise appears as an important preventive tool against maternal diet-induced metabolic alterations.

Effects of Pyrroloquinoline Quinone on Lipid Metabolism and Anti-Oxidative Capacity in a High-Fat-Diet Metabolic Dysfunction-Associated Fatty Liver Disease Chick Model

Metabolic dysfunction-associated fatty liver disease (MAFLD) and its interaction with many metabolic pathways raises global public health concerns. This study aimed to determine the therapeutic effects of Pyrroloquinoline quinone (PQQ, provided by PQQ.Na₂) on MAFLD in a chick model and primary chicken hepatocytes with a focus on lipid metabolism, anti-oxidative capacity, and mitochondrial biogenesis. The MAFLD chick model was established on laying hens by feeding them a high-energy low-protein (HELP) diet. Primary hepatocytes isolated from the liver of laying hens were induced for steatosis by free fatty acids (FFA) and for oxidative stress by hydrogen peroxide (H₂O₂). In the MAFLD chick model, the dietary supplementation of PQQ conspicuously ameliorated the negative effects of the HELP diet on liver biological functions, suppressed the progression of MAFLD mainly through enhanced lipid metabolism and protection of liver from oxidative injury. In the steatosis and oxidative stress cell models, PQQ functions in the improvement of the lipid metabolism and hepatocytes tolerance to fatty degradation and oxidative damage by enhancing mitochondrial biogenesis and then increasing the anti-oxidative activity and anti-apoptosis capacity. At both the cellular and individual levels, PQQ was demonstrated to exert protective effects of hepatocyte and liver from fat accumulation through the improvement of mitochondrial biogenesis and maintenance of redox homeostasis. The key findings of the present study provide an in-depth knowledge on the ameliorative effects of PQQ on the progression of fatty liver and its mechanism of action, thus providing a theoretical basis for the application of PQQ, as an effective nutrient, into the prevention of MAFLD.

Mesenchymal stem cells ameliorate lipid metabolism through reducing mitochondrial damage of hepatocytes in the treatment of post-hepatectomy liver failure

Hepatectomy is an effective therapeutic strategy for many benign and malignant liver diseases, while the complexity of liver anatomy and the difficulty of operation lead to complications after hepatectomy. Among them, post-hepatectomy liver failure (PHLF) is the main factor threatening the life of patients. At present, liver transplantation is an effective approach for PHLF. However, the application of liver transplantation has been largely limited due to the shortage of donors and the high cost of such operation. Therefore, it is urgently necessary to develop a new treatment for PHLF. Mesenchymal stem cells (MSCs) have become a new treatment regimen for liver diseases because of their easy access and low immunogenicity. Our study found that there were some subtle connections between MSCs and liver lipid metabolism in the PHLF model. We used MSC transplantation to treat PHLF induced by 90% hepatectomy. MSC transplantation could restore the mitochondrial function, promote the β-oxidation of fatty acid (FA), and reduce the lipid accumulation of hepatocytes. In addition, interleukin 10 (IL-10), a cytokine with immunoregulatory function, had an important role in lipid metabolism. We also found that MSCs transplantation activated the mammalian target of rapamycin (mTOR) pathway. Therefore, we explored the relationship between mitochondrial damage and lipid metabolism abnormality or PHLF. MSCs improved mitochondrial function and corrected abnormal lipid metabolism by affecting the mTOR pathway in the treatment of PHLF. Collectively, MSC transplantation could be used as a potential treatment for PHLF.

Phloroglucinol Strengthens the Antioxidant Barrier and Reduces Oxidative/Nitrosative Stress in Nonalcoholic Fatty Liver Disease (NAFLD)

Nonalcoholic fatty liver disease (NAFLD) is one of the most commonly occurring diseases within western dietary patterns. Usually untreated, it may lead to type 2 diabetes mellitus (T2DM), steatohepatitis (NASH), and hepatocellular carcinoma (HCC). Besides its severe aftermath, up to now, there is no known therapeutic approach to this disease in everyday clinical practice. Most NAFLD patients are encouraged to do physical activities or diet change and remain without pharmacological treatment. In this study, we present phloroglucinol (PHG) as a novel and promising compound in NAFLD treatment. PHG significantly increased the level of enzymatic and nonenzymatic antioxidants both in palmitate and hydrogen peroxide-induced oxidative stress models. Strengthened antioxidative defense reduced the oxidative/nitrosative damage to cell proteins, lipids, and carbohydrates. Furthermore, PHG treatment reduced hepatic steatosis; lowered inflammatory markers, such as NF-κB or HIF-1α; and inhibited cell apoptosis. Moreover, PHG had a more comprehensive effect than other commonly used antioxidants: N-acetylcysteine (NAC) and α-lipoic acid (ALA), suggesting its clinical usability. Therefore, our paper supports the benefits of natural compounds as a therapeutical approach to NAFLD.

Plant sterol ester of α-linolenic acid ameliorates high-fat diet-induced nonalcoholic fatty liver disease in mice: association with regulating mitochondrial dysfunction and oxidative stress via activating AMPK signaling

Plant sterol ester of α-linolenic acid prevents nonalcoholic fatty liver disease by improving mitochondrial function, modifying lipid metabolism, and inhibiting oxidative stress via AMPK signaling.

Physiological evidence of mitochondrial permeability transition pore opening caused by lipid deposition leading to hepatic steatosis in db/db mice

Mitochondrial permeability transition pore (mPTP) is an important regulator in cell apoptosis and necrosis. However, its role in hepatic steatosis, especially its electrophysiological properties transformation remains elusive. Herein, using diabetes mice, we investigated the role of mPTP in hepatic steatosis triggered by diabetes and the mechanisms involved. We found that hepatic steatosis altered mitochondrial morphology, generating mega mitochondria, mitochondria swelling, calcein fluorescence quenching and mitochondrial membrane potential depolarization. At the same time, we confirmed an augmented mPTP opening with patch clamping in liver mitoplasts in db/db mice and a similar transformation with arachidonic acid (AA) simulating liquid deposition. We also found mPTP opening was significantly attenuated in wt mice after removing mitochondrial matrix, while that in db/db mice remained active. In addition, we observed that AA could directly activate mPTP in inside-out mode, independent of matrix calcium. In conclusion, we for the first time provided a physiological evidence of mPTP opening in lipid deposition, which could be directly induced by AA without Ca²⁺ and can be inhibited by cyclosporine A. As a result, it led to mitochondria morphology and function transformation. This might provide insights into potential therapeutic target for future treatment of mitochondrial liver disease.

Effect of SGLT2 Inhibitors on Type 2 Diabetes Mellitus With Non-Alcoholic Fatty Liver Disease: A Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

Clinical trials showed that sodium-glucose cotransporter 2 (SGLT2) inhibitors can improve non-alcoholic fatty liver disease (NAFLD). In this work, a meta-analysis of randomized controlled trials was conducted to evaluate the effect of SGLT2 inhibitors on type 2 diabetes mellitus (T2DM) with NAFLD.

METHODS

PubMed, Embase, Web of Science, and Cochrane Libraries were used for the systematic literature review to determine eligible studies. A randomized effect model was adapted to perform a meta-analysis on these eligible studies to estimate the combined effect sizes. Differences were expressed as the weighted average difference (WMD) of the continuous results and the 95% confidence interval (CI).

RESULTS

Ten randomized controlled trials with 573 participants were included. SGLT2 inhibitors significantly reduced the levels of alanine transaminase (WMD -5.36 [95% CI: -8.86, -1.85], p = 0.003) and Aspartate Transaminase (WMD -2.56 [95% CI: -3.83, -1.29], p <0.0001). In terms of body composition, liver proton density fat fraction (WMD -2.20 [95% CI: -3.67, -0.74], p = 0.003), visceral fat mass area (WMD -20.71 [95% CI: -28.19, -13.23], p <0.00001), subcutaneous fat areas (WMD -14.68 [95% CI: -26.96, -2.40], p = 0.02) were also significantly reduced.

CONCLUSION

SGLT2 inhibitors can remarkably reduce hepatic enzymes, hepatic fat and improve body composition. Thus, they may become a new treatment option for NAFLD.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, identifier CRD42020215570.

β-patchoulene improves lipid metabolism to alleviate non-alcoholic fatty liver disease via activating AMPK signaling pathway

Non-alcoholic fatty liver disease (NAFLD) has been a leading cause of chronic metabolic disease, seriously posing healthy burdens to the public, whereas interventions available for it are limited to date. Patchouli oil had been reported to attenuate hepatic steatosis in our previous study. β-patchoulene (β-PAE) is a representative component separated from patchouli oil with multiple activities, but its effect against NAFLD is still unknown. To investigate the effect and potential mechanism of β-PAE on NAFLD, we used high fat diet (HFD) in vivo and free fatty acid (FFA) in vitro to induce hepatic steatosis in rats and L02 cells, respectively. Histological examination was evaluated via Hematoxylin-eosin and oil red O staining. The parameters for hepatic steatosis were estimated via biochemical kits, western blotting and quantitative real-time PCR. Compound C, the inhibitor of AMPK, was applied further to examine the precise mechanism of β-PAE on NAFLD. Our results indicated that β-PAE significantly attenuated HFD-induced weight gain, hepatic injury, lipid deposition in serum and hepatic tissue as well as FFA induced-lipid accumulation. Besides, β-PAE markedly improved the expression of AMP-activated protein kinase (AMPK) and its downstream factors which correlate with hepatic lipid synthesis and oxidation in vivo and in vitro. Nevertheless, Compound C abrogated the benefits derived from β-PAE in L02 cells. In conclusion, these results suggest that β-PAE exerts AMPK agonist-like effect to regulate hepatic lipid synthesis and oxidation, eventually prevent NAFLD progression.

Carbon tetrachloride (CCl4) accelerated development of non-alcoholic fatty liver disease (NAFLD)/steatohepatitis (NASH) in MS-NASH mice fed western diet supplemented with fructose (WDF)

Background

Multiple murine models of nonalcoholic fatty liver disease/steatohepatitis (NAFLD/NASH) have been established by using obesogenic diets and/or chemical induction. MS-NASH mouse (formally FATZO) is a spontaneously developed dysmetabolic strain that can progress from hepatosteatosis to moderate fibrosis when fed a western diet supplemented with 5% fructose (WDF). This study aimed to use carbon tetrachloride (CCl₄) to accelerate and aggravate progression of NAFLD/NASH in MS-NASH mouse.

Methods

Male MS-NASH mice at 8 weeks of age were fed WDF for the entire study. Starting at 16 weeks of age, CCl₄ was intraperitoneally administered twice weekly at a dose of 0.2 mL/kg for 3 weeks or 0.08 mL/kg for 8 weeks. Obeticholic acid (OCA, 30 mg/kg, QD) was administered in both MS-NASH and C57Bl/6 mice fed WDF and treated with CCl₄ (0.08 mL/kg).

Results

WDF enhanced obesity and hepatosteatosis, as well as induced moderate fibrosis in MS-NASH mice similar to previous reports. Administration of CCl₄ accelerated liver fibrosis with increased bridging and liver hydroxyproline contents, but had no significant impact on liver steatosis and lipid contents. High dose CCl₄ caused high mortality and dramatic elevation of ALT and ASL, while low dose CCl₄ resulted in a moderate elevation of ALT and AST with low mortality. Compared to C57BI/6 mice with WDF and CCl₄ (0.08 mL/kg), MS-NASH mice had more prominent hepatosteatosis and fibrosis. OCA treatment significantly lowered liver triglycerides, steatosis and fibrosis in both MS-NASH and C57Bl/6 mice fed WDF with CCl₄ treatment.

Conclusions

CCl₄ reduced induction time and exacerbated liver fibrosis in MS-NASH mice on WDF, proving a superior NASH model with more prominent liver pathology, which has been used favorably in pharmaceutical industry for testing novel NASH therapeutics.

Protective effect of Argan oil on mitochondrial function and oxidative stress against acrylamide-induced liver and kidney injury in rats

CONTEXT

Acrylamide (ACR) is now a risk for general public health. Argan oil (AO) is harvested from the fruits of Argania spinosa and its rich source of antioxidant and phenolic compounds.

OBJECTIVE

The aim of present study was to investigate the protective effect of AO against ACR-induced liver and kidney injury in rats.

MATERIALS AND METHODS

Rats were exposed to ACR (50 mg/kg/day three times per week), AO (6 ml/kg/day per day) and ACR together with AO for 30 days. Oxidative status and mitochondrial functions were evaluated in liver and kidney.

RESULTS

Although ALT, AST, urea and creatine levels in serum, myeloperoxidase and total nitrite (NOx) levels in the tissues, lipid peroxidation and protein carbonyls levels were increased in the ACR-treated rats, cytosolic glucose-6-phosphate dehydrogenase and glutathione-S-transferase activities, mitochondrial antioxidant enzyme activities, glutathione levels, oxidative phosphorylation enzymes, TCA cycle enzymes, mitochondrial metabolic function and ATP level were decreased. The administration of ACR together with AO normalised almost all these parameters.

CONCLUSION

Over recent years, compounds that specifically target mitochondria have emerged as promising therapeutic options for patients with hepatic and renal diseases. We think that AO oil is one of these compounds due to its unique content.

Silencing hepatic MCJ attenuates non-alcoholic fatty liver disease (NAFLD) by increasing mitochondrial fatty acid oxidation

Nonalcoholic fatty liver disease (NAFLD) is considered the next major health epidemic with an estimated 25% worldwide prevalence. No drugs have yet been approved and NAFLD remains a major unmet need. Here, we identify MCJ (Methylation-Controlled J protein) as a target for non-alcoholic steatohepatitis (NASH), an advanced phase of NAFLD. MCJ is an endogenous negative regulator of the respiratory chain Complex I that acts to restrain mitochondrial respiration. We show that therapeutic targeting of MCJ in the liver with nanoparticle- and GalNAc-formulated siRNA efficiently reduces liver lipid accumulation and fibrosis in multiple NASH mouse models. Decreasing MCJ expression enhances the capacity of hepatocytes to mediate β-oxidation of fatty acids and minimizes lipid accumulation, which results in reduced hepatocyte damage and fibrosis. Moreover, MCJ levels in the liver of NAFLD patients are elevated relative to healthy subjects. Thus, inhibition of MCJ emerges as an alternative approach to treat NAFLD.

Non-alcoholic fatty liver (NAFLD) disease causes degeneration of the liver, affects about 25% of people globally, and has no approved treatment. Here, the authors show that the therapeutic siRNA-driven silencing of MCJ in the liver is an effective and safe treatment for NAFLD in multiple mouse models.

ApoE deficiency promotes non-alcoholic fatty liver disease in mice via impeding AMPK/mTOR mediated autophagy

AIM

This work was to investigate the relationship between ApoE and autophagy regulated by AMPK/mTOR pathway in the pathological process of NAFLD.

MAIN METHODS

Both WT and ApoE^-/- mice were divided into two groups and allocated into either a normal chow (ND) or a high-fat diet (HFD) for 8 weeks. After that, we detected the indicators of lipid accumulation, hepatic injury, mitochondrial function hallmark, autophagy, apoptosis, inflammation, and oxidative stress by commercially available kits, immunohistochemistry, immunofluorescent staining, and western blot.

KEY FINDING

We found the lipid levels of serum and liver, and hepatic injury were significantly increased in the ApoE^-/--HFD group compared to other groups. ApoE^-/- mice exhibited increased deposition of fat in liver tissue. The PGC1α, NRF1, ATP, p-AMPK, AMPK, Beclin1, and LC3 levels were downregulated and ROS, p-mTOR, and mTOR were increased in the ApoE^-/--HFD group compared to WT-HFD group. When treated with AMPK and autophagy activators, AICAR and rapamycin, these pathologies and protein levels can be rescued. The expression levels of apoptosis-related proteins, inflammation, and oxidative stress were increased in the ApoE^-/--HFD group compared to the WT-HFD group.

SIGNIFICANCE

Our results indicated that ApoE deficiency can regulate AMPK/mTOR pathway, which leads to NAFLD most likely by modulating hepatic mitochondrial function.