Bergenin inhibits hepatic fat deposition by activating the AMPK signaling pathway, thereby attenuating alcoholic liver disease

Alcoholic liver disease (ALD) is a prevalent liver condition that arises from prolonged and excessive alcohol intake. Bergenin (BER) is an effective phytotherapeutic agent that exhibits pharmacological properties, including anti-inflammatory and anti-oxidative effects. To establish an in vivo model of ALD, C57BL/6 mice were continuously fed a high-fat diet (HFD) and administered alcohol gavage for 8 weeks, while concurrently administering BER and evaluated for therapeutic effects. After modeling, the therapeutic effects of BER were evaluated by observing histopathological changes and the detection of relevant biochemical indicators in mice. In addition, RNA sequencing of liver tissues was performed to analyze differentially expressed genes and to investigate the associated signaling pathways in order to elucidate the protective mechanisms of BER. These differentially expressed genes were mainly enriched in lipid metabolism pathways and the cytochrome P450 metabolism of exogenous substances. Subsequently, HepG2 was co-treated with sodium oleate (NaOA) and ethanol to establish an in vitro model, and the specific mechanism by which BER ameliorates ALD was further analyzed in depth. AMPK inhibitor, Compound C (CC), was demonstrated to significantly inhibit the regulation of lipid metabolism by BER in vitro. Finally, the differentially expressed genes selected were validated through qRT-PCR and Western blot analysis. Collectively, our findings revealed that BER effectively alleviated liver injury caused by alcohol and HFD in mice, significantly suppressing lipid deposition in ALD, enhancing alcohol metabolism, and mitigating oxidative stress.

Lipids associated with autophagy: mechanisms and therapeutic targets

Autophagy is a molecular process essential for maintaining cellular homeostasis, with its impairment or dysregulation linked to the progression of various diseases in mammals. Specific lipids, including phosphoinositides, sphingolipids, and oxysterols, play pivotal roles in inducing and regulating autophagy, highlighting their significance in this intricate process. This review focuses on the critical involvement of these lipids in autophagy and lipophagy, providing a comprehensive overview of the current understanding of their functions. Moreover, we delve into how abnormalities in autophagy, influenced by these lipids, contribute to the pathogenesis of various diseases. These include age-related conditions such as cardiovascular diseases, neurodegenerative disorders, type 2 diabetes, and certain cancers, as well as inflammatory and liver diseases, skeletal muscle pathologies and age-related macular degeneration (AMD). This review aims to highlight function of lipids and their potential as therapeutic targets in treating diverse human pathologies by elucidating the specific roles of phosphoinositides, sphingolipids, and oxysterols in autophagy.

Qiwei Jinggan Ling regulates oxidative stress and lipid metabolism in alcoholic liver disease by activating AMPK

BACKGROUND

Alcoholic liver disease (ALD) is a severe public health concern worldwide and there is still a lack of effective treatments. Qiwei Jinggan Ling (QJL) has protective effects against various liver injuries, but its pharmacological action on ALD has received little attention.

PURPOSE

To investigate the effect and mechanism of QJL on ALD in vivo and in vitro.

METHODS

In vivo, an ALD mouse model was established by alcohol combined with a high-fat diet (HFD) and treated with QJL. Biochemical indicators, HE staining, and Oil Red O staining were employed to assess hepatic oxidative stress, steatosis, and alcohol metabolism. RNA sequencing analysis was performed, and the results were verified by qRT-PCR and Western blot to elucidate the hepatoprotective mechanism of QJL. In vitro, HepG2 cells were co-stimulated with NaOA (sodium oleate) and EtOH (ethanol), followed by intervention with Compound C (CC, AMPK inhibitor) and QJL-containing serum. Oil Red O, BODIPY (boron-dipyrromethene), and ROS (reactive oxygen species) staining were applied to validate the efficacy and mechanism of QJL-containing serum. The expression of AMP-activated protein kinase (AMPK) pathway-related factors was analyzed through qRT-PCR and Western blot for additional corroboration. Moreover, the key pharmacodynamic components of QJL were identified by UPLC-MS/MS and molecular docking.

RESULTS

In vivo, QJL ameliorated liver structural disorders, steatosis, oxidative stress, and impaired alcohol metabolism, as indicated by biochemical indicators and histopathological assays. RNA sequencing analysis revealed that QJL reversed the expression of genes related to alcohol metabolism, fatty acid metabolism, and cholesterol metabolism. The results of qRT-PCR and Western blot were in line with those of RNA sequencing. Furthermore, it was discovered that QJL significantly upregulated the expression of p-AMPK and downregulated the expression of sterol regulatory element binding transcription factor 1 (SREBP-1c). In vitro, biochemical indicators and staining assays demonstrated that QJL-containing serum inhibited lipid accumulation and oxidative stress. The qRT-PCR and Western blot analysis revealed that QJL-containing serum markedly enhanced the expression of p-AMPK and carnitine palmitoyltransferase 1a (Cpt1a), while suppressing the expression of SREBP-1c, fatty acid synthase (Fasn), and acetyl-coenzyme A carboxylase 1 (ACC-1). However, CC inhibited the above pharmacological activities of QJL-containing serum. Additionally, (2S)-Liquiritigenin, Glycyrrhetinate, Isovitexin, Taxifolin, and Yohimbine were proved to be the key active components of QJL.

CONCLUSION

QJL had the potential to be a therapeutic drug for ALD by activating the AMPK pathway, thereby regulating lipid metabolism and inhibiting oxidative stress.

Progress in the mechanism of autophagy and traditional Chinese medicine herb involved in alcohol-related liver disease

Alcohol-related liver disease (ALD) is chronic liver damage caused by long-term heavy drinking with, extremely complicated pathogenesis. The current studies speculated that excessive alcohol and its metabolites are the major causes of liver cell toxicity. Autophagy is evolutionarily conserved in eukaryotes and aggravates alcoholic liver damage, through various mechanisms, such as cellular oxidative stress, inflammation, mitochondrial damage and lipid metabolism disorders. Therefore, autophagy plays an critical role in the occurrence and development of ALD. Some studies have shown that traditional Chinese medicine extracts improve the histological characteristics of ALD, as reflected in the improvement of oxidative stress and lipid droplet clearance, which might be achieved by inducing autophagy. This article reviews the mechanisms of quercetin, baicalin, glycycoumarin, salvianolic acid A, resveratrol, ginsenoside rg1, and dihydromyricetin inducing autophagy and their participation in the inhibition of ALD. The regulation of autophagy in ALD by these traditional Chinese medicine extracts provides novel ideas for the treatment of the disease; however, its molecular mechanism needs to be elucidated further.

Advanced effect of curcumin and resveratrol on mitigating hepatic steatosis in metabolic associated fatty liver disease via the PI3K/AKT/mTOR and HIF-1/VEGF cascade

Metabolic associated fatty liver disease (MAFLD) is the most common chronic liver disease that has no viable treatment. Curcumin (Cur) and resveratrol (Res) are two natural products that have been studied for their potential to ameliorate MAFLD. However, while these compounds have been investigated individually, their combined use and the potential for a synergistic or augmented effect remain unexplored. This study aims to investigate the effect of curcumin (Cur) and resveratrol (Res) as a potential combination therapy on MAFLD. Cur, Res and Cur+Res were tested in palmitic acid (PA)-induced-HepG2 cells. MAFLD model was established using Goto-Kakizaki rats. The animals were treated with vehicle control (model group), Cur (150 mg/kg), Res (150 mg/kg), Cur+Res (150 mg/kg, 8:2, w/w), or metformin (Met, positive control, 400 mg/kg/day) via oral gavage for 4 weeks. Wistar rats were used as the control group. Network pharmacology was conducted to elucidate the molecular actions of Cur and Res, followed by q-PCR and immunoblotting in vivo. Cur+Res exhibited synergistic effects in reducing triglyceride, total cholesterol and lipid accumulation in PA-induced HepG2 cells. The combination also markedly attenuated hepatic steatosis in the MAFLD rats. Network pharmacology illustrated that the interaction of Cur and Res was associated with the modulation of multiple molecular targets associated with the PI3K/AKT/mTOR and HIF-1 signaling pathways. Experimental results confirmed that Cur+Res nomalised the gene targets and protein expressions in the PI3K/AKT/mTOR and HIF-1 signaling pathways, including PI3K, mTOR, STAT-3, HIF-1α, and VEGF. The present study demonstrated an advanced effect of Cur and Res in combination to attenuate MAFLD, and the mechanism is at least partly associated with the modulation of the PI3K/AKT/mTOR and HIF-1 signaling pathways.

Autophagy, Oxidative Stress, and Alcoholic Liver Disease: A Systematic Review and Potential Clinical Applications

Ethanol consumption triggers oxidative stress by generating reactive oxygen species (ROS) through its metabolites. This process leads to steatosis and liver inflammation, which are critical for the development of alcoholic liver disease (ALD). Autophagy is a regulated dynamic process that sequesters damaged and excess cytoplasmic organelles for lysosomal degradation and may counteract the harmful effects of ROS-induced oxidative stress. These effects include hepatotoxicity, mitochondrial damage, steatosis, endoplasmic reticulum stress, inflammation, and iron overload. In liver diseases, particularly ALD, macroautophagy has been implicated as a protective mechanism in hepatocytes, although it does not appear to play the same role in stellate cells. Beyond the liver, autophagy may also mitigate the harmful effects of alcohol on other organs, thereby providing an additional layer of protection against ALD. This protective potential is further supported by studies showing that drugs that interact with autophagy, such as rapamycin, can prevent ALD development in animal models. This systematic review presents a comprehensive analysis of the literature, focusing on the role of autophagy in oxidative stress regulation, its involvement in organ-organ crosstalk relevant to ALD, and the potential of autophagy-targeting therapeutic strategies.

A review of edible plant-derived natural compounds for the therapy of liver fibrosis

Liver fibrosis has a high incidence worldwide and is the common pathological basis of many chronic liver diseases. Liver fibrosis is caused by the excessive deposition of extracellular matrix and concomitant collagen accumulation in livers and can lead to the development of liver cirrhosis and even liver cancer. A large number of studies have provided evidence that liver fibrosis can be blocked or even reversed by appropriate medical interventions. However, the antifibrosis drugs with ideal clinical efficacy are still insufficient. The edible plant-derived natural compounds have been reported to exert effective antifibrotic effects with few side-effects, representing a kind of promising source for the treatment of liver fibrosis. In this article, we reviewed the current progress of the natural compounds derived from dietary plants in the treatment of liver fibrosis, including phenolic compounds (capsaicin, chlorogenic acid, curcumin, ellagic acid, epigallocatechin-3-gallate, resveratrol, sinapic acid, syringic acid, vanillic acid and vitamin E), flavonoid compounds (genistein, hesperidin, hesperetin, naringenin, naringin and quercetin), sulfur-containing compounds (S-allylcysteine, ergothioneine, lipoic acid and sulforaphane) and other compounds (betaine, caffeine, cucurbitacin B, lycopene, α-mangostin, γ-mangostin, ursolic acid, vitamin C and yangonin). The pharmacological effects and related mechanisms of these compounds in in-vivo and in-vitro models of liver fibrosis are focused.

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

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

Extracellular Vesicles and Fatty Liver

Fatty liver is a complex pathological process caused by multiple etiologies. In recent years, the incidence of fatty liver has been increasing year by year, and it has developed into a common chronic disease that seriously affects people's health around the world. It is an important risk factor for liver cirrhosis, liver cancer, and a variety of extrahepatic chronic diseases. Therefore, the early diagnosis and early therapy of fatty liver are important. Except for invasive liver biopsy, there is still a lack of reliable diagnosis and staging methods. Extracellular vesicles are small double-layer lipid membrane vesicles derived from most types of cells. They play an important role in intercellular communication and participate in the occurrence and development of many diseases. Since extracellular vesicles can carry a variety of biologically active substances after they are released by cells, they have received widespread attention. The occurrence and development of fatty liver are also closely related to extracellular vesicles. In addition, extracellular vesicles are expected to provide a new direction for the diagnosis of fatty liver. This article reviews the relationship between extracellular vesicles and fatty liver, laying a theoretical foundation for the development of new strategies for the diagnosis and therapy of fatty liver.

Synergistic Beneficial Effects of Resveratrol and Diet on High-Fat Diet-Induced Obesity

Introduction: Despite decades of research, obesity and its related medical complications remain a major health concern globally. Therefore, novel therapeutic strategies are needed to combat obesity and its numerous debilitating complications. Resveratrol (RES) has a potential therapeutic effect in obesity and diabetes by improving oxidative metabolism and insulin signaling. Background and Objectives: The aim of this study was to investigate the effect of RES treatment on weight loss and glucose and fatty acid metabolism. Methods: Obesity was induced in 24 mice by exposure to a high-fat diet (HFD) for 8 weeks. Mice were randomly assigned to one group of either: group 1: control, non-treated low-fat diet (LFD) for 12 weeks (n = 8), group 2: non-treated high-fat diet (HFD) for 12 weeks (n = 8), group 3: RES-treated HFD (HFD + RES) (n = 8), or group 4: RES-treated and switched to LFD (HFD-LFD + RES) (n = 8). HFD + RES mice were first fed an HFD for 8 weeks followed by 4 weeks of RES. The HFD-LFD + RES group was first fed an HFD for 8 weeks and then treated with RES and switched to an LFD for 4 weeks. Results: After 12 weeks, group 2 mice had significantly higher body weights compared to group 1 (23.71 ± 1.95 vs. 47.83 ± 2.27; p < 0.05). Group 4 had a significant decrease in body weight and improvement in glucose tolerance compared to mice in group 2 (71.3 ± 1.17 vs. 46.1 ± 1.82 and 40.9 ± 1.75, respectively; p < 0.05). Skeletal muscles expression of SIRT1, SIRT3, and PGC1α were induced in group 3 and 4 mice compared to group 2 (p < 0.01), with no changes in AMP-activated protein kinase expression levels. Furthermore, combination of RES and diet ameliorated skeletal muscle intermediate lipid accumulation and significantly improved insulin sensitivity and secretion. Conclusions: The results of this study suggest a synergistic beneficial effect of LFD and RES to lower body weight and enhance glucose and fatty acid metabolism.

Overview of Polyamines as Nutrients for Human Healthy Long Life and Effect of Increased Polyamine Intake on DNA Methylation

Polyamines, spermidine and spermine, are synthesized in every living cell and are therefore contained in foods, especially in those that are thought to contribute to health and longevity. They have many physiological activities similar to those of antioxidant and anti-inflammatory substances such as polyphenols. These include antioxidant and anti-inflammatory properties, cell and gene protection, and autophagy activation. We have first reported that increased polyamine intake (spermidine much more so than spermine) over a long period increased blood spermine levels and inhibited aging-associated pathologies and pro-inflammatory status in humans and mice and extended life span of mice. However, it is unlikely that the life-extending effect of polyamines is exerted by the same bioactivity as polyphenols because most studies using polyphenols and antioxidants have failed to demonstrate their life-extending effects. Recent investigations revealed that aging-associated pathologies and lifespan are closely associated with DNA methylation, a regulatory mechanism of gene expression. There is a close relationship between polyamine metabolism and DNA methylation. We have shown that the changes in polyamine metabolism affect the concentrations of substances and enzyme activities involved in DNA methylation. I consider that the increased capability of regulation of DNA methylation by spermine is a key of healthy long life of humans.

Caveolin-1 attenuates acetaminophen aggravated lipid accumulation in alcoholic fatty liver by activating mitophagy via the Pink-1/Parkin pathway

Alcoholic fatty liver (AFL) is a disease characterized by the abnormal structure and dysfunction of hepatocytes caused by long-term, excessive drinking. Acetaminophen (APAP) is a commonly used painkiller, but it can aggravate lipid deposition in the liver and cause liver injury when used in fatty liver disease. Here, we investigated the effect of caveolin-1 (CAV-1), an intracellular stent protein, on the pathogenesis of APAP aggravated lipid deposition in AFL mice. This study shows that lipid accumulation was more severe in APAP groups than in alcohol-treated mice. The CAV-1 stent-like domain (CSD, 82-101 amino acids of caveolin-1), used to upregulate CAV-1 expression, could reduce lipid accumulation and activate autophagy in AFL mice treated with APAP. The levels of CAV-1 and autophagy-related proteins (LC3-II/I and Beclin-1) had decreased, whereas SREBP-1c had increased in A/O (alcohol and oleic acid) and APAP-co-treated L02 cells. CAV-1 small interfering RNA and CAV1-overexpressing plasmid were separately transfected into A/O and APAP co-treated L02 cells. When CAV-1 was downregulated, the levels of Pink-1, Parkin, and autophagy-related proteins (LC3-II/I and Beclin-1) were decreased, whereas SREBP-1c was increased. The opposite trend was observed when CAV-1 was overexpressed. The results show that CAV-1 reduced lipid accumulation in L02 cells and activated Pink-1/Parkin-related mitophagy. This study highlights the positive role of CAV-1 in APAP-increased lipid accumulation under the AFL status and provides a new understanding of the function of CAV-1 in the liver through mitophagy associated with the Pink-1/Parkin pathway.

Monoterpene-flavonoid conjugates from Sarcandra glabra and their autophagy modulating activities

Fourteen new monoterpene-flavonoid conjugates including four monoterpene-conjugated chalcones (glabratins A-D, 1-4), seven monoterpene-conjugated dihydrochalcones (glabratins E-K, 5-11), and three monoterpene-conjugated flavanones (glabratins L-N, 12-14), together with four known analogues (15-18) were isolated from the aerial parts of Sarcandra glabra. The structures and the absolute configurations of these compounds were elucidated by the spectroscopic data, single-crystal X-ray diffraction, and electronic circular dichroism (ECD) calculations. Compounds 1, 4-6, 9-14, and 18 showed obvious cell autophagy-inducing activities at 25 μM in HEK293 cells. Furthermore, the bioassay results also showed that 18 induced cell autophagy in a dose dependent manner. Our findings revealed a rare class of monoterpene-flavonoid conjugates in nature and firstly reported their autophagy-inducing activities.

Modulation of Autophagy: A Novel "Rejuvenation" Strategy for the Aging Liver

Aging is a natural life process which leads to a gradual decline of essential physiological processes. For the liver, it leads to alterations in histomorphology (steatosis and fibrosis) and function (protein synthesis and energy generation) and affects central hepatocellular processes (autophagy, mitochondrial respiration, and hepatocyte proliferation). These alterations do not only impair the metabolic capacity of the liver but also represent important factors in the pathogenesis of malignant liver disease. Autophagy is a recycling process for eukaryotic cells to degrade dysfunctional intracellular components and to reuse the basic substances. It plays a crucial role in maintaining cell homeostasis and in resisting environmental stress. Emerging evidence shows that modulating autophagy seems to be effective in improving the age-related alterations of the liver. However, autophagy is a double-edged sword for the aged liver. Upregulating autophagy alleviates hepatic steatosis and ROS-induced cellular stress and promotes hepatocyte proliferation but may aggravate hepatic fibrosis. Therefore, a well-balanced autophagy modulation strategy might be suitable to alleviate age-related liver dysfunction. Conclusion. Modulation of autophagy is a promising strategy for "rejuvenation" of the aged liver. Detailed knowledge regarding the most devastating processes in the individual patient is needed to effectively counteract aging of the liver without causing obvious harm.

Autophagy in liver diseases

Autophagy is the liver cell energy recycling system regulating a variety of homeostatic mechanisms. Damaged organelles, lipids and proteins are degraded in the lysosomes and their elements are re-used by the cell. Investigations on autophagy have led to the award of two Nobel Prizes and a health of important reports. In this review we describe the fundamental functions of autophagy in the liver including new data on the regulation of autophagy. Moreover we emphasize the fact that autophagy acts like a two edge sword in many occasions with the most prominent paradigm being its involvement in the initiation and progress of hepatocellular carcinoma. We also focused to the implication of autophagy and its specialized forms of lipophagy and mitophagy in the pathogenesis of various liver diseases. We analyzed autophagy not only in well studied diseases, like alcoholic and nonalcoholic fatty liver and liver fibrosis but also in viral hepatitis, biliary diseases, autoimmune hepatitis and rare diseases including inherited metabolic diseases and also acetaminophene hepatotoxicity. We also stressed the different consequences that activation or impairment of autophagy may have in hepatocytes as opposed to Kupffer cells, sinusoidal endothelial cells or hepatic stellate cells. Finally, we analyzed the limited clinical data compared to the extensive experimental evidence and the possible future therapeutic interventions based on autophagy manipulation.

Resveratrol contributes to the inhibition of liver fibrosis by inducing autophagy via the microRNA‑20a‑mediated activation of the PTEN/PI3K/AKT signaling pathway

Liver fibrosis (LF) is a healing response to wounds resulting in liver injury that can cause liver failure or even cancer without functional prevention. Resveratrol (RSV) has been suggested to exert biological effects against various human diseases. MicroRNA-20a (miRNA/miR-20a) has been shown to promote disease progression. The present study aimed to assess the mechanisms through which RSV induces autophagy and activates the miR-20a-mediated phosphatase and tensin homolog (PTEN)/PI3K/AKT signaling pathway in LF. First, a rat model of carbon tetrachlo-ride (CCL₄)-induced LF and a cell model of platelet-derived growth factor (PDGF)-BB-stimulated HSC-T6 cells were established for use in subsequent experiments. Subsequently, RSV at a range of concentrations was injected into the model rats with LF. Indicators related to liver injury, oxidative stress and fibrosis were determined in the rats with LF. The RSV-treated HSC-T6 cells were subjected to transfection with miR-20a mimic and PTEN overexpression plasmid to assess the levels of liver injury and LF. A dual-luciferase reporter gene assay was performed to verify the binding sites between PTEN and miR-20a. RSV was found to alleviate LF in rats, and autophagy was enhanced in the rats with LF following RSV treatment. Furthermore, the activation of the PTEN/PI3K/AKT axis attenuated LF, which was reversed by transfection with miR-20a mimic. RSV reversed the inhibitory effects of miR-20a on PTEN expression, reducing miR-20a expression and promoting PTEN, PI3K and p-AKT protein expression, thus attenuating LF. On the whole, the present study demonstrates that RSV induces autophagy and activates the miR-20a-mediated PTEN/PI3K/AKT signaling pathway to attenuate LF. These findings may lead to the development of potential therapeutic strategies for LF.

An Overview of the Mechanism of Penthorum chinense Pursh on Alcoholic Fatty Liver

Alcohol liver disease (ALD) caused by excessive alcohol consumption is a progressive disease, and alcohol fatty liver disease is the primary stage. Currently, there is no approved drug for its treatment. Abstinence is the best way to heal, but patients' compliance is poor. Unlike other chronic diseases, alcohol fatty liver disease is not caused by nutritional deficiencies; it is caused by the molecular action of ingested alcohol and its metabolites. More and more studies have shown the potential of Penthorum chinense Pursh (PCP) in the clinical use of alcohol fatty liver treatment. The purpose of this paper is to reveal from the essence of PCP treatment of alcohol liver mechanism mainly by the ethanol dehydrogenase (ADH) and microsomal ethanol oxidation system-dependent cytochrome P4502E1 (CYP2E1) to exert antilipogenesis, antioxidant, anti-inflammatory, antiapoptotic, and autophagy effects, with special emphasis on its mechanisms related to SIRT1/AMPK, KEAP-1/Nrf2, and TLR4/NF-κB. Overall, data from the literature shows that PCP appears to be a promising hepatoprotective traditional Chinese medicine (TCM).

Melatonin inhibits Benzo(a)pyrene-Induced apoptosis through activation of the Mir-34a/Sirt1/autophagy pathway in mouse liver

Benzo(a)pyrene (BaP), an important environmental pollutant, is produced as the result of incomplete combustion of organic materials in many industries and food cooking process. It has been purposed that BaP induces hepatotoxicity through oxidative stress and apoptosis. Several studies have shown that melatonin can protect against chemical-induced apoptosis through autophagy pathway. In this study, we assessed the modulating effect of melatonin, a well-known antioxidant, on BaP-induced hepatotoxicity through induction of autophagy. Thirty male mice were treated daily for 28 consecutive days. BaP (75 mg/kg; oral gavage) and melatonin (10 and 20 mg/kg, i.p.) were administered to mice. The liver histopathology and the levels of apoptosis and autophagy proteins as well as the expression of miR-34a were determined. The BaP exposure induced severe liver histological injury and markedly enhanced AST, ALT and MDA level. Also, apoptosis proteins and hepatic miR-34a expression increased. However, the level of Sirt1 and autophagy markers such as LC3 II/I ratio and Beclin-1 reduced. The co-administration of melatonin reversed all changes caused by BaP. In summary, melatonin appears to be effective in BaP-induced hepatotoxicity maybe through the miR-34a/Sirt1/autophagy molecular pathway.

Health Benefits and Molecular Mechanisms of Resveratrol: A Narrative Review

Resveratrol is a bioactive compound in many foods. Since its anticancer activity was reported in 1997, its health benefits have been intensively investigated. Resveratrol has antioxidant, anti-inflammatory, immunomodulatory, glucose and lipid regulatory, neuroprotective, and cardiovascular protective effects, therefore, can protect against diverse chronic diseases, such as cardiovascular diseases (CVDs), cancer, liver diseases, obesity, diabetes, Alzheimer's disease, and Parkinson's disease. This review summarizes the main findings of resveratrol-related health benefits in recent epidemiological surveys, experimental studies, and clinical trials, highlighting its related molecular mechanisms. Resveratrol, therefore, has been regarded as a potent candidate for the development of nutraceuticals and pharmaceuticals to prevent and treat certain chronic diseases.

Caveolin-1 alleviates lipid accumulation in NAFLD associated with promoting autophagy by inhibiting the Akt/mTOR pathway

Non-alcoholic fatty liver disease (NAFLD) is the most burgeoning chronic liver disease worldwide whose pathogenesis is complex and controversial. Here, we investigated the impact of caveolin-1 (CAV1), a scaffolding protein of caveolae for lipid homeostasis and endocytosis, on the pathogenesis of NAFLD. CAV1 and caveolae play crucial roles in the regulation of autophagy and hepatic energy metabolism. However, it remains unclear whether CAV1 could affect hepatic lipid metabolism by regulating autophagy. In this study, results showed that the expressions of CAV1 and autophagy-related proteins (Beclin1 and LC3-II/Ⅰ) were decreased, while the level of p62 was increased in HFD (high-fat diet) fed mice liver and in A/O (alcohol and oleic acid mixture) treated L02 cells, compared to the corresponding controls. In vivo study, upregulation of CAV1 with CAV1 scaffolding domain peptides (CSD, amino acids 82-101 of caveolin-1) could alleviate lipid accumulation and promote autophagy in NAFLD mice. In vitro study, CAV1 overexpression plasmid and its small interfering RNA were cultured with A/O treated L02 cells respectively. The results also demonstrated that CAV1 reduced lipid accumulation and promoted autophagy in L02 cells. Treatment with chloroquine, an inhibitor of autophagic degradation, abrogated CAV1 plasmid-mediated alleviation of lipid accumulation. Mechanistically, the inhibition of Akt/mTOR pathway was involved in the protective role of CAV1 in autophagy induction and lipid metabolism in NAFLD. Together, these results provided novel perception into the function of CAV1 in liver through autophagy and emphasized its positive role in NAFLD.

Emerging Roles of Lipophagy in Health and Disease

The term lipophagy is used to describe the autophagic degradation of lipid droplets, the main lipid storage organelles of eukaryotic cells. Ever since its discovery in 2009, lipophagy has emerged as a significant component of lipid metabolism with important implications for organismal health. This review aims to provide a brief summary of our current knowledge on the mechanisms that are responsible for regulating lipophagy and the impact the process has under physiological and pathological conditions.

Natural compounds in the chemoprevention of alcoholic liver disease

Alcoholic liver disease (ALD), caused by excessive consumption of alcohol, is a major cause of chronic liver disease worldwide. Much effort has been expended to explore the pathogenesis of ALD. Hepatic cell injury, oxidative stress, inflammation, regeneration, and bacterial translocation are all involved in the pathogenesis of ALD. Immediate abstinence is the most important therapeutic treatment for affected individuals. However, the medical treatment for ALD had not advanced in a long period. Intriguingly, an increasing body of research indicates the potential of natural compounds in the targeted therapy of ALD. A plethora of dietary natural products such as flavonoids, resveratrol, saponins, and β-carotene are found to exert protective effects on ALD. This occurs through various mechanisms composed of antioxidative, anti-inflammatory, iron chelation, pro-apoptosis, and/or antiproliferation of hepatic stellate cells and hepatocellular carcinoma cells. In this review, we will summarize current knowledge about the pathogenesis and treatments of ALD and focus on the potential of natural compounds in ALD therapies and underlying mechanisms.

Acetaminophen aggravates fat accumulation in NAFLD by inhibiting autophagy via the AMPK/mTOR pathway

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease which affects millions of people worldwide. Acetaminophen (APAP) overdose is the leading cause of acute liver failure. In this study, APAP (50, 100, 200 mg/kg) were employed on mice fed with a high-fat diet, and APAP (2, 4, 8 mM) were cultured with L02 cells in the presence of alcohol and oleic acid. APAP treatment significantly aggravated hepatic lipid accumulation, increased the serum levels of triglyceride (TG), alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and increased hepatic lipid accumulation in H&E and Oil red O staining results. Transmission electron microscopy (TEM) found fewer number of autophagosomes in APAP (100 mg/kg) treated group. Immunohistochemistry analysis showed the intensity of hepatic mTOR was increased and AMPK was decreased in 200 mg/kg APAP treated group. Western blot analysis showed APAP treatment decreased the levels of LC3-Ⅱ, Beclin1 and AMPK, while increased the levels of mTOR and SREBP-1c, respectively. In vitro study showed APAP treatment obviously increased TG activities in cell supernatant, and Oil red O staining had the same results. Western blot analysis demonstrated APAP treatment decreased the levels of LC3-Ⅱ, Beclin1 and AMPK, increased the levels of mTOR and SREBP-1c, but rapamycin treatment significantly reversed these effects of APAP. In conclusion, therapeutic dosages of APAP aggravates fat accumulation in NAFLD, the potential mechanism might be involved in inhibiting autophagy associated with the AMPK/mTOR pathway, and patients with NAFLD should use a lower dose of APAP.

Autophagy in Human Health and Disease: Novel Therapeutic Opportunities

SIGNIFICANCE

In eukaryotes, autophagy represents a highly evolutionary conserved process, through which macromolecules and cytoplasmic material are degraded into lysosomes and recycled for biosynthetic or energetic purposes. Dysfunction of the autophagic process has been associated with the onset and development of many human chronic pathologies, such as cardiovascular, metabolic, and neurodegenerative diseases as well as cancer. Recent Advances: Currently, comprehensive research is being carried out to discover new therapeutic agents that are able to modulate the autophagic process in vivo. Recent evidence has shown that a large number of natural bioactive compounds are involved in the regulation of autophagy by modulating several transcriptional factors and signaling pathways.

CRITICAL ISSUES

Critical issues that deserve particular attention are the inadequate understanding of the complex role of autophagy in disease pathogenesis, the limited availability of therapeutic drugs, and the lack of clinical trials. In this context, the effects that natural bioactive compounds exert on autophagic modulation should be clearly highlighted, since they depend on the type and stage of the pathological conditions of diseases.

FUTURE DIRECTIONS

Research efforts should now focus on understanding the survival-supporting and death-promoting roles of autophagy, how natural compounds interact exactly with the autophagic targets so as to induce or inhibit autophagy and on the evaluation of their pharmacological effects in a more in-depth and mechanistic way. In addition, clinical studies on autophagy-inducing natural products are strongly encouraged, also to highlight some fundamental aspects, such as the dose, the duration, and the possible synergistic action of these compounds with conventional therapy.

Effect of ethanol on lipid metabolism

Hepatic lipid metabolism is a series of complex processes that control influx and efflux of not only hepatic lipid pools, but also organismal pools. Lipid homeostasis is usually tightly controlled by expression, substrate supply, oxidation and secretion that keep hepatic lipid pools relatively constant. However, perturbations of any of these processes can lead to lipid accumulation in the liver. Although it is thought that these responses are hepatic arms of the 'thrifty genome', they are maladaptive in the context of chronic fatty liver diseases. Ethanol is likely unique among toxins, in that it perturbs almost all aspects of hepatic lipid metabolism. This complex response is due in part to the large metabolic demand placed on the organ by alcohol metabolism, but also appears to involve more nuanced changes in expression and substrate supply. The net effect is that steatosis is a rapid response to alcohol abuse. Although transient steatosis is largely an inert pathology, the chronicity of alcohol-related liver disease seems to require steatosis. Better and more specific understanding of the mechanisms by which alcohol causes steatosis may therefore translate into targeted therapies to treat alcohol-related liver disease and/or prevent its progression.

Pharmacological Effects and Mechanisms of Chinese Medicines Modulating NLRP3 Inflammasomes in Ischemic Cardio/Cerebral Vascular Disease

Cardio/cerebral-vascular diseases seriously threaten human health and are the leading cause of death. As such, there is great interest in identifying a potential mechanism that controls the development process of cardio/cerebral vascular diseases. Present studies demonstrate that inflammasomes play an important role in the process of ischemic cardio/cerebral vascular diseases (ICCVDs). Among the pathological process of ICCVDs, inflammasomes activated the sterile inflammatory response that accelerated the development of diseases and aggravated the acute lesion of tissue. As the most thoroughly studied inflammasome, the NLRP3 inflammasome has been proven to be a potential therapeutic target for ICCVDs. In this review, we summarized the mechanisms of Chinese herbal medicine which can affect ICCVDs via the regulation of the NLRP3 inflammasome. Our study discovers that active compounds of Chinese medicines have a negative effect on NLRP3 in different ICCVDs models. Astragaloside IV may influence the receptor of the cell membrane to inhibit NLRP3 activation. Resveratrol, colchicinesis, salvianolic acid B, chrysophanol and sulforaphane may directly damage the formation of NLRP3 by inhibiting ASC or Caspase-1. Most of the active natural compounds can negatively regulate the downstream products of NLRP3 inflammasome such as IL-18 and IL1 β . In addition, Chinese medicines such as sinomenine, ruscogenin, resveratrol, arctigenin and cepharanthineas may downregulate NLRP3 inflammasome by inducing autophagy activation. Due to the advantages of multi-target effects, Chinese herbal medicine can be treated as a splendid therapy for ICCVDs by inhibiting NLRP3 inflammasome.

Polyamine Metabolism and Gene Methylation in Conjunction with One-Carbon Metabolism

Recent investigations have revealed that changes in DNA methylation status play an important role in aging-associated pathologies and lifespan. The methylation of DNA is regulated by DNA methyltransferases (DNMT1, DNMT3a, and DNMT3b) in the presence of S-adenosylmethionine (SAM), which serves as a methyl group donor. Increased availability of SAM enhances DNMT activity, while its metabolites, S-adenosyl-l-homocysteine (SAH) and decarboxylated S-adenosylmethionine (dcSAM), act to inhibit DNMT activity. SAH, which is converted from SAM by adding a methyl group to cytosine residues in DNA, is an intermediate precursor of homocysteine. dcSAM, converted from SAM by the enzymatic activity of adenosylmethionine decarboxylase, provides an aminopropyl group to synthesize the polyamines spermine and spermidine. Increased homocysteine levels are a significant risk factor for the development of a wide range of conditions, including cardiovascular diseases. However, successful homocysteine-lowering treatment by vitamins (B6, B12, and folate) failed to improve these conditions. Long-term increased polyamine intake elevated blood spermine levels and inhibited aging-associated pathologies in mice and humans. Spermine reversed changes (increased dcSAM, decreased DNMT activity, aberrant DNA methylation, and proinflammatory status) induced by the inhibition of ornithine decarboxylase. The relation between polyamine metabolism, one-carbon metabolism, DNA methylation, and the biological mechanism of spermine-induced lifespan extension is discussed.

Potential of resveratrol in mitigating metabolic disturbances induced by ethanol

Alcohol abuse is associated with numerous health problems, including metabolic disturbances and liver damage. Therefore, different compounds are continuously being tested to evaluate their potential effectiveness in reducing these harmful changes. Animal studies clearly show that resveratrol is capable of ameliorating some consequences of ethanol ingestion. Resveratrol is a naturally occurring diphenolic compound having pleiotropic, health-promoting properties. Its beneficial action have been also demonstrated in animal models with ethanol-induced metabolic disturbances and liver injury. In ethanol treated animals, resveratrol effectively reduced liver lipid accumulation. Moreover, this compound diminished necrosis of hepatocytes, and also reduced liver fibrosis. The hepatoprotective action of resveratrol is largely associated with its ant-oxidant and anti-inflammatory properties, and also covers changes in activities of some enzymes. It is known that this compound upregulates the adiponectin-SIRT1-AMPK signaling pathway in the liver. Resveratrol was also found to positively affect blood lipids in animals exposed to ethanol. Moreover, administration of resveratrol to animals with ethanol-induced hypoinsulinemia and insulin resistance was shown to alleviate these disturbances. These outcomes clearly indicate that resveratrol holds great potential to reduce some consequences of ethanol ingestion. However, human studies are required to fully assess its therapeutic value.

Rosmarinic acid attenuates hepatic steatosis by modulating ER stress and autophagy in oleic acid-induced HepG2 cells

Non-alcoholic fatty acid disease (NAFLD) has become an emerging entity of liver disorders worldwide. Oxidative stress and deranged autophagy-induced endoplasmic reticulum (ER) stress has recently been recognized as one of the prime factors involved in the pathological mechanism underlying NAFLD and progressive non-alcoholic steato-hepatitis (NASH). Epidemiological and experimental data reveal the potency of dietary polyphenols in averting NAFLD. In this line, to analyse and address the underlying pathogenic mechanisms, in the present study, oleic acid-induced HepG2 cells were treated with rosmarinic acid (RA), a dietary polyphenol with well-established cytoprotective properties. Treatment with rosmarinic acid (20 μg) was found to potently counter the elevated levels of total cholesterol (TC) and triglycerides (TG). Additionally, exposure of oleic acid-induced HepG2 cells to rosmarinic acid showed reduced levels of ROS and increased activity of enzymic and non-enzymic antioxidants. The steatotic HepG2 cells presented a pronounced increase in the expression of key ER stress markers such as p-PERK, p-IRE-1, ATF-6, p-eIF-α and CHOP, which was considerably reduced upon treatment with rosmarinic acid. Moreover, exposure to rosmarinic acid altered the deranged autophagic mechanism in oleic acid-induced HepG2 cells, which was observed via the protein expression of Beclin 1, LC31, ATG5 and ATG7. This study demonstrates that rosmarinic acid abrogates NAFLD via diminishing ER stress by nullifying oxidative stress and restoring deranged autophagy and can be used as a potent adjunct in the treatment of NAFLD, thus illustrating the valuable application of polyphenols in combating NAFLD.

Non-alcoholic fatty acid disease (NAFLD) has become an emerging entity of liver disorders worldwide.

Lipophagy and liver disease: New perspectives to better understanding and therapy

Intracellular lipid droplets (LDs) are remarkably dynamic and complex organelles that enact regulated storage and release of lipids to fulfil their fundamental roles in energy metabolism, membrane synthesis and provision of lipid-derived signaling molecules. The recent finding that LDs can be selectively degraded by the lysosomal pathway of autophagy through a process termed lipophagy has opened up a new understanding of how lipid metabolism regulates cellular physiology and pathophysiology. Many new functions for autophagic lipid metabolism have now been defined in various diseases including liver disease. Lipophagy was originally described in hepatocytes, where it is critical for maintaining cellular energy homeostasis in obesity and metabolic syndrome. In vitro and in vivo studies have demonstrated the selective uptake of LDs by autophagosomes, and inhibition of autophagy has been shown to reduce the β-oxidation of free fatty acids due to the increased accumulation of lipids and LDs. The identification of lipophagy as a new process dedicated to cellular lipid removal has mapped autophagy as an emerging player in cellular lipid metabolism. Pharmacological or genetic modulation of lipophagy might point to possible therapeutic strategies for combating a broad range of liver diseases. This review summarizes recent work focusing on lipophagy and liver disease as well as highlighting challenges and future directions of research. On the other hand, it also offers a glimpse into different strategies that have been used in experimental models to counteract excessive pathological lipophagy in the prevention and treatment of liver disease.

Altering ethanol pharmacokinetics to treat alcohol use disorder: Can you teach an old dog new tricks?

Disulfiram was the first pharmacotherapy approved to treat alcohol use disorder in the 1950s. Disulfiram alters ethanol pharmacokinetics and causes uncomfortable reactions (e.g. headache, tachycardia, nausea, flushing and hypotension) when alcohol is consumed. Subsequently, a better understanding of the neurobiological pathways involved in alcohol use disorder led to the development of other medications (e.g. naltrexone and acamprosate). These neurobiological-based medications act on alcohol use disorder-related phenotypes including craving, stress, and/or withdrawal. The original approach to treat alcohol use disorder, by altering ethanol pharmacokinetics has been much less investigated. Recent research on ethanol pharmacokinetics has shed light on the mechanisms of action underlying alcohol use disorder and how some medications that alter ethanol pharmacokinetics may be helpful in treating alcohol use disorder. This review summarizes and discusses the complex pharmacokinetics of ethanol, and proposes that altering ethanol pharmacokinetics via novel pharmacological approaches may be a viable approach to treat alcohol use disorder.

Breaking fat: The regulation and mechanisms of lipophagy

Lipophagy is defined as the autophagic degradation of intracellular lipid droplets (LDs). While the field of lipophagy research is relatively young, an expansion of research in this area over the past several years has greatly advanced our understanding of lipophagy. Since its original characterization in fasted liver, the contribution of lipophagy is now recognized in various organisms, cell types, metabolic states and disease models. Moreover, recent studies provide exciting new insights into the underlying mechanisms of lipophagy induction as well as the consequences of lipophagy on cell metabolism and signaling. This review summarizes recent work focusing on LDs and lipophagy as well as highlighting challenges and future directions of research as our understanding of lipophagy continues to grow and evolve. This article is part of a Special Issue entitled: Recent Advances in Lipid Droplet Biology edited by Rosalind Coleman and Matthijs Hesselink.

Chinese Herbal Medicine for the Optimal Management of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a complex heterogeneous disorder characterized by androgen excess and ovulatory dysfunction; it is now known to be closely linked to metabolic syndrome. Recent research suggests that insulin resistance plays an important role in the pathogenesis of PCOS which may lead to the excessive production of androgens by ovarian theca cells. Currently there is no single drug that can treat both the reproductive and metabolic complications of the disorder. Existing pharmaceutical agents such as hormonal therapies have been associated with side effects and are not appropriate for PCOS women with infertility. Additionally, insulin sensitizing agents useful for treating the metabolic abnormalities in PCOS have limited efficacy for treating reproductive aspects of the disorder. Chinese herbal medicines have a long history of treating gynaecological problems and infertility and therefore may be a novel approach to the treatment of PCOS. Current research demonstrates that the compounds isolated from herbs have shown beneficial effects for PCOS and when combined in an herbal formula can target both reproductive and metabolic defects simultaneously. Therefore, further investigation into Chinese herbal medicine in the treatment of PCOS is warranted.

Autophagy-inducing natural compounds: a treasure resource for developing therapeutics against tissue fibrosis

Tissue fibrosis is a common pathologic change of many chronic diseases, which is characterized by extracellular matrix accumulation in tissues and dysfunction of the injured organs. Despite there recently gain mechanistic insight into the pathogenesis of tissue fibrosis, therapeutics for tissue fibrosis and thus many chronic diseases remain a significant clinical unmet need. Recent progressions indicate that autophagy, a conserved lysosomal degradation process in eukaryotic cells, not only plays an important regulatory role in maintaining cellular and tissue homeostasis, but also contributes to the development and progression of tissue fibrosis in a diversity of organs. Interestingly, a number of natural compounds derived from plant or Chinese Herb Medicines (CHM), have been identified as modulators of autophagy, and may function as potential therapeutic agents for the treatment of different fibrotic diseases. In this review, we focus on several plant natural compounds that have well-known anti-fibrotic effects through regulating autophagic signal pathways or autophagy activity. These findings should provide important therapeutic clues and strategy for the development of new anti-fibrosis drugs.

SIRT1‑mediated regulation of oxidative stress induced by Pseudomonas aeruginosa lipopolysaccharides in human alveolar epithelial cells

Sirtuin1 (SIRT1) is an NAD+‑dependent deacetylase that exhibits multiple biological functions, including cell differentiation inhibition, transcription regulation, cell cycle regulation and anti‑apoptosis. Lipopolysaccharides (LPS) are crucial virulence factors produced by Pseudomonas aeruginosa and serve an important role in adjusting the interactions between the host and the pathogen. However, the effect of SIRT1 in the regulation of LPS‑induced A459 human alveolar epithelial cells (AECs) oxidative stress remains unclear. The cellular reactive oxygen species (ROS) production was examined in A549 cells that were supplemented with LPS. Relative cell signaling pathway proteins were further investigated by western blot analysis. It was identified that LPS downregulated SIRT1 expression, however, upregulated ROS generation, which was associated with the increase of nuclear factor (NF)‑κB and acetyl‑NF‑κB. Activation of SIRT1 by resveratrol significantly reversed the effects of LPS on A549 cells. By contrast, inhibition of SIRT1 by nicotinamide had the opposite effects that enhance cell ROS production. Thus, the results indicated that SIRT1 serves an important role in the regulation of oxidative stress induced by LPS in human AECs.