Alisol A 24-acetate ameliorates nonalcoholic steatohepatitis by inhibiting oxidative stress and stimulating autophagy through the AMPK/mTOR pathway

Current Advances in the Regulatory Effects of Bioactive Compounds from Dietary Resources on Nonalcoholic Fatty Liver Disease: Role of Autophagy

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic liver disease characterized by lipid metabolic disorder primarily due to sedentary lifestyles and excessive food consumption. However, there are currently no approved and effective drugs available to treat NAFLD. In recent years, research has shown that dietary bioactive compounds, such as polysaccharides, polyphenols, flavones, and alkaloids, have the potential to improve NAFLD by regulating autophagy. However, there is no up-to-date review of research progress in this field. This review aims to systematically summarize and discuss the regulatory effects and molecular mechanisms of dietary bioactive compounds on NAFLD through the modulation of autophagy. The existing research has demonstrated that some dietary bioactive compounds can effectively improve various aspects of NAFLD progression, such as lipid metabolism, insulin resistance (IR), endoplasmic reticulum (ER) stress, oxidative stress, mitochondrial homeostasis, and inflammation. Molecular mechanism studies have revealed that they exert their beneficial effects on NAFLD through autophagy-mediated signaling pathways, predominantly involving transcription factor EB (TFEB), mammalian target of rapamycin (mTOR), adenosine monophosphate-activated protein kinase (AMPK), peroxisome proliferator-activated receptors (PPARs), SIRT, and PTEN-induced kinase 1 (PINK1)/parkin. Furthermore, the challenges and prospects of current research in this field are highlighted. Overall, this review provides valuable insights into the potential treatment of NAFLD using dietary bioactive compounds that can modulate autophagy.

Radical oxygen species: an important breakthrough point for botanical drugs to regulate oxidative stress and treat the disorder of glycolipid metabolism

Background: The incidence of glycolipid metabolic diseases is extremely high worldwide, which greatly hinders people's life expectancy and patients' quality of life. Oxidative stress (OS) aggravates the development of diseases in glycolipid metabolism. Radical oxygen species (ROS) is a key factor in the signal transduction of OS, which can regulate cell apoptosis and contribute to inflammation. Currently, chemotherapies are the main method to treat disorders of glycolipid metabolism, but this can lead to drug resistance and damage to normal organs. Botanical drugs are an important source of new drugs. They are widely found in nature with availability, high practicality, and low cost. There is increasing evidence that herbal medicine has definite therapeutic effects on glycolipid metabolic diseases. Objective: This study aims to provide a valuable method for the treatment of glycolipid metabolic diseases with botanical drugs from the perspective of ROS regulation by botanical drugs and to further promote the development of effective drugs for the clinical treatment of glycolipid metabolic diseases. Methods: Using herb*, plant medicine, Chinese herbal medicine, phytochemicals, natural medicine, phytomedicine, plant extract, botanical drug, ROS, oxygen free radicals, oxygen radical, oxidizing agent, glucose and lipid metabolism, saccharometabolism, glycometabolism, lipid metabolism, blood glucose, lipoprotein, triglyceride, fatty liver, atherosclerosis, obesity, diabetes, dysglycemia, NAFLD, and DM as keywords or subject terms, relevant literature was retrieved from Web of Science and PubMed databases from 2013 to 2022 and was summarized. Results: Botanical drugs can regulate ROS by regulating mitochondrial function, endoplasmic reticulum, phosphatidylinositol 3 kinase (PI3K)/protein kinase B (AKT), erythroid 2-related factor 2 (Nrf-2), nuclear factor κB (NF-κB), and other signaling pathways to improve OS and treat glucolipid metabolic diseases. Conclusion: The regulation of ROS by botanical drugs is multi-mechanism and multifaceted. Both cell studies and animal experiments have demonstrated the effectiveness of botanical drugs in the treatment of glycolipid metabolic diseases by regulating ROS. However, studies on safety need to be further improved, and more studies are needed to support the clinical application of botanical drugs.

Adlay (Coix lacryma-jobi L.) Polyphenol Improves Hepatic Glucose and Lipid Homeostasis through Regulating Intestinal Flora via AMPK Pathway

SCOPE

Non-alcoholic fatty liver disease (NAFLD) is a type of metabolic syndrome characterized of abnormal lipid deposition in the liver. Adlay polyphenol (AP), an effective component extracted from Coix lacryma-jobi L., has been reported that it can be used as a dietary supplement to prevent NAFLD. In this study, the mechanism and action of AP on lipid metabolism and regulation of intestinal flora are investigated.

METHODS AND RESULTS

AP significantly decreases the lipid accumulation in free fatty acid-treated HepG2 cells. Western blot results indicate that AP improves lipid metabolism via activating the p-AMPK/p-ACC pathway. In vivo experiments show AP treatment significantly decreases the body weight, liver weight, hepatic triglyceride, and total cholesterol contents, as well as the serum glucose levels in high fat diet-fed mice, which may affect lipid accumulation by activating AMPK pathway and changing intestinal bacterial communities and intestinal microbiome metabolism.

CONCLUSION

AP can be used as a food supplement for improving lipid metabolic dysfunction and reducing the incidence of metabolic diseases.

Alisol B Alleviates Hepatocyte Lipid Accumulation and Lipotoxicity via Regulating RARα-PPARγ-CD36 Cascade and Attenuates Non-Alcoholic Steatohepatitis in Mice

Non-alcoholic steatohepatitis (NASH) is a common chronic liver disease worldwide, with no effective therapies available. Discovering lead compounds from herb medicine might be a valuable strategy for the treatment of NASH. Here, we discovered Alisol B, a natural compound isolated from Alisma orientalis (Sam.), that attenuated hepatic steatosis, inflammation, and fibrosis in high-fat diet plus carbon tetrachloride (DIO+CCl₄)-induced and choline-deficient and amino acid-defined (CDA)-diet-induced NASH mice. RNA-seq showed Alisol B significantly suppressed CD36 expression and regulated retinol metabolism in NASH mice. In mouse primary hepatocytes, Alisol B decreased palmitate-induced lipid accumulation and lipotoxicity, which were dependent on CD36 suppression. Further study revealed that Alisol B enhanced the gene expression of RARα with no direct RARα agonistic activity. The upregulation of RARα by Alisol B reduced HNF4α and PPARγ expression and further decreased CD36 expression. This effect was fully abrogated after RARα knockdown, suggesting Alisol B suppressed CD36 via regulating RARα-HNF4α-PPARγ cascade. Moreover, the hepatic gene expression of RARα was obviously decreased in murine NASH models, whereas Alisol B significantly increased RARα expression and decreased CD36 expression, along with the downregulation of HNF4α and PPARγ. Therefore, this study showed the unrecognized therapeutic effects of Alisol B against NASH with a novel mechanism by regulating RARα-PPARγ-CD36 cascade and highlighted Alisol B as a promising lead compound for the treatment of NASH.

Autophagy and beyond: Unraveling the complexity of UNC-51-like kinase 1 (ULK1) from biological functions to therapeutic implications

UNC-51-like kinase 1 (ULK1), as a serine/threonine kinase, is an autophagic initiator in mammals and a homologous protein of autophagy related protein (Atg) 1 in yeast and of UNC-51 in Caenorhabditis elegans. ULK1 is well-known for autophagy activation, which is evolutionarily conserved in protein transport and indispensable to maintain cell homeostasis. As the direct target of energy and nutrition-sensing kinase, ULK1 may contribute to the distribution and utilization of cellular resources in response to metabolism and is closely associated with multiple pathophysiological processes. Moreover, ULK1 has been widely reported to play a crucial role in human diseases, including cancer, neurodegenerative diseases, cardiovascular disease, and infections, and subsequently targeted small-molecule inhibitors or activators are also demonstrated. Interestingly, the non-autophagy function of ULK1 has been emerging, indicating that non-autophagy-relevant ULK1 signaling network is also linked with diseases under some specific contexts. Therefore, in this review, we summarized the structure and functions of ULK1 as an autophagic initiator, with a focus on some new approaches, and further elucidated the key roles of ULK1 in autophagy and non-autophagy. Additionally, we also discussed the relationships between ULK1 and human diseases, as well as illustrated a rapid progress for better understanding of the discovery of more candidate small-molecule drugs targeting ULK1, which will provide a clue on novel ULK1-targeted therapeutics in the future.

Neuroprotective effects of alisol A 24-acetate on cerebral ischaemia-reperfusion injury are mediated by regulating the PI3K/AKT pathway

BACKGROUND

Neuroinflammation and apoptosis are involved in the pathogenesis of ischaemic stroke. Alisol A 24-acetate (24A) exerts a strong inhibitory effect on inflammation and cell apoptosis. The neuroprotective effect of 24A on global cerebral ischaemia/reperfusion (GCI/R) injury remains unclear.

METHODS

GCI/R mice were used to investigate the neuroprotective effect of 24A. Modified neurological deficit scores, Morris water maze and object recognition tests were used to evaluate behaviours. Metabolism in brain regions was detected using magnetic resonance spectroscopy (MRS), and changes in microglia, astrocytes and neurons were detected. Inflammation and apoptosis were measured.

RESULTS

The results showed that 24A suppressed neurological deficits scores and improved GCI/R induced cognitive dysfunction. It was also observed that 24A could alleviate neuroinflammation, which manifested as 24A inhibited microglia and astrocytes proliferation, downregulated the expression of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and inducible nitric oxide synthase (iNOS) in the GCI/R mice brain. The apoptosis of neurons reduced, and dendritic spines of hippocampal neurons increased in the presence of 24A. In addition, 24A could up-regulate the expression of phosphorylated phosphoinositide 3-kinases (p-PI3K) and phosphorylated protein kinase B (p-AKT) in GCI/R mice brain, and all the morphological, neurological, and biochemical changes of 24A treatment were abolished by the application of PI3K/AKT pathway inhibitor LY294002.

CONCLUSIONS

Taken together, our study indicated that 24A alleviated GCI/R injury by inhibiting neuroinflammation and apoptosis through the regulation of the PI3K/AKT pathway.

Alisol A 24-acetate protects oxygen-glucose deprivation-induced brain microvascular endothelial cells against apoptosis through miR-92a-3p inhibition by targeting the B-cell lymphoma-2 gene

CONTEXT

Alisol A 24-acetate has been used to treat vascular diseases. However, the underlying mechanisms still remain unclear.

OBJECTIVE

The present study evaluated the antiapoptotic effect of alisol A 24-acetate on brain microvascular endothelial cells (BMECs) and explored the underlying mechanisms.

MATERIALS AND METHODS

BMECs were injured through oxygen -glucose deprivation (OGD) after alisol A 24-acetate treatment. Cell viability and half-maximal inhibitory concentration (IC₅₀) were measured using CCK-8, whereas inflammatory factors and oxidative stress indicators were measured using enzyme linked immunosorbent assay. Cell invasion and wound healing assays were detected. Cell apoptosis was assessed using flow cytometry. B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X (Bax) expression were analyzed using Western blotting. Dual-luciferase assay was applied to detect target genes of miR-92a-3p.

RESULT

Alisol A 24-acetate had an IC₅₀ of 98.53 mg/L and inhibited cell viability at concentrations over 50mg/L. OGD induced apoptosis and promoted miR-92a-3p overexpression in BMECs. However, alisol A 24-acetate treatment suppressed inflammation, improved migration and invasion abilities, increased Bcl-2 expression, inhibited Bax expression, and repressed apoptosis and miR92a-3p overexpression in OGD-induced BMECs. MiR-92a-3p overexpression promoted cell apoptosis and suppressed Bcl-2 expression, whereas its inhibitor reversed the tendency. Alisol A 24-acetate treatment relieved the effects of miR-92a-3p overexpression. Dual-luciferase assay confirmed that miR-92a-3p negatively regulated the Bcl-2 expression.

CONCLUSIONS

These findings suggest that alisol A 24-acetate exerts antiapoptotic effects on OGD-induced BMECs through miR-92a-3p inhibition by targeting the Bcl-2 gene, indicating its potential for BMECs protection and as a novel therapeutic agent for the treatment of cerebrovascular disease.

Nuciferine protects against high-fat diet-induced hepatic steatosis and insulin resistance via activating TFEB-mediated autophagy–lysosomal pathway

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis and insulin resistance and there are currently no approved drugs for its treatment. Hyperactivation of mTOR complex 1 (mTORC1) and subsequent impairment of the transcription factor EB (TFEB)-mediated autophagy–lysosomal pathway (ALP) are implicated in the development of NAFLD. Accordingly, agents that augment hepatic TFEB transcriptional activity may have therapeutic potential against NAFLD. The objective of this study was to investigate the effects of nuciferine, a major active component from lotus leaf, on NAFLD and its underlying mechanism of action. Here we show that nuciferine activated ALP and alleviated steatosis, insulin resistance in the livers of NAFLD mice and palmitic acid-challenged hepatocytes in a TFEB-dependent manner. Mechanistic investigation revealed that nuciferine interacts with the Ragulator subunit hepatitis B X-interacting protein and impairs the interaction of the Ragulator complex with Rag GTPases, thereby suppressing lysosomal localization and activity of mTORC1, which activates TFEB-mediated ALP and further ameliorates hepatic steatosis and insulin resistance. Our present results indicate that nuciferine may be a potential agent for treating NAFLD and that regulation of the mTORC1–TFEB–ALP axis could represent a novel pharmacological strategy to combat NAFLD.

The Potential Application of Chinese Medicine in Liver Diseases: A New Opportunity

Liver diseases have been a common challenge for people all over the world, which threatens the quality of life and safety of hundreds of millions of patients. China is a major country with liver diseases. Metabolic associated fatty liver disease, hepatitis B virus and alcoholic liver disease are the three most common liver diseases in our country, and the number of patients with liver cancer is increasing. Therefore, finding effective drugs to treat liver disease has become an urgent task. Chinese medicine (CM) has the advantages of low cost, high safety, and various biological activities, which is an important factor for the prevention and treatment of liver diseases. This review systematically summarizes the potential of CM in the treatment of liver diseases, showing that CM can alleviate liver diseases by regulating lipid metabolism, bile acid metabolism, immune function, and gut microbiota, as well as exerting anti-liver injury, anti-oxidation, and anti-hepatitis virus effects. Among them, Keap1/Nrf2, TGF-β/SMADS, p38 MAPK, NF-κB/IκBα, NF-κB-NLRP3, PI3K/Akt, TLR4-MyD88-NF-κB and IL-6/STAT3 signaling pathways are mainly involved. In conclusion, CM is very likely to be a potential candidate for liver disease treatment based on modern phytochemistry, pharmacology, and genomeproteomics, which needs more clinical trials to further clarify its importance in the treatment of liver diseases.

Capillin protects against non-alcoholic steatohepatitis through suppressing NLRP3 inflammasome activation and oxidative stress

BACKGROUND

Non-alcoholic steatohepatitis (NASH) is an extreme form of non-alcoholic fatty liver disease. The present study concentrated on the role of Capillin, a polyacetylene compound isolated from Artemisia capillaris Thunb., in NASH development.

MATERIALS AND METHODS

Palmitic acid (PA) was treated with FL83B hepatocytes, and high-fat diet was given to mouse to construct the NASH model in vivo. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method, flow cytometry, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were carried out to measure the viability and apoptosis of FL83B hepatocytes. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was performed to measure the mRNA expressions of infiltration markers (Cd11c, Ccr2, and Ly6c), fibrosis genes (Tgfβ1, Col1a1, and Timp1), and alpha-smooth muscle actin (α-SMA). Western blot, immunofluorescence, and Enzyme-linked immunosorbent assay (ELISA) were implemented to examine the proteins of Caspase-3, Bcl2, Nrf2, HO-1, NLRP3, ASC, and Caspase-1, the ROS level, and oxidative stress markers (MDA, GSH-ST, SOD, and GSH-Px), and the lipid peroxidation level, respectively. Moreover, HE staining was manipulated to observe the histopathological changes in liver tissue.

RESULTS

Capillin hampered PA-mediated hepatocytes apoptosis and enhanced cell viability. Furthermore, Capillin suppressed PA-mediated oxidative stress in hepatocytes, promoted Nrf2/HO-1 expression, and repressed NLRP3-ASC-Caspase1 inflammasome. The in vivo studies indicated that Capillin vigorously improves liver fat accumulation, oxidative stress, and liver injury in NASH mice. Mechanistically, Capillin repressed NLRP3-ASC-Caspase1 inflammasome and up-regulated the Nrf2-HO-1 pathway in the liver.

CONCLUSION

Capillin ameliorates hepatocyte injury by dampening oxidative stress and repressing NLRP3 inflammasome in NASH mice.

Integrating Network Pharmacology and RT-qPCR Analysis to Investigate the Mechanisms Underlying ZeXie Decoction-Mediated Treatment of Non-alcoholic Fatty Liver Disease

ZeXie Decoction (ZXD) is a traditional Chinese medicine composed of Alisma orientalis (Sam.) Juzep. and Atractylodes macrocephala Koidz. ZXD has been widely used to treat non-alcoholic fatty liver disease (NAFLD). The mechanistic basis for the pharmacological activity of ZXD, however, remains poorly understood. In this study, we used a network pharmacology approach and investigated the association between ZXD and NAFLD. We identified the active ingredients of ZXD and screened the potential targets of these ingredients, after which a database of relevant NAFLD-related targets were constructed and several enrichment analyses were performed. Furthermore, the ethanol and aqueous extracts of ZXD were prepared and experimental pharmacology validation was conducted using RT-qPCR of the non-alcoholic fatty liver disease (NAFLD) model in Sprague-Dawley (SD) rats. As a result, a herb-compound-target-pathway network model was developed, and HMGCR, SREBP-2, MAPK1, and NF-κBp65 targets were validated. The gene expression results of these four targets were consistent with those of the network pharmacology prediction. Using an integration strategy, we revealed that ZXD could treat NAFLD by targeting HMGCR, SREBP-2, MAPK1, and NF-κBp65.

Traditional Chinese medicine in the treatment of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a common chronic liver disease in clinical practice. It has been considered that NASH is one of the main causes of chronic liver disease, cirrhosis and carcinoma. The mechanism of the NASH progression is complex, including lipid metabolism dysfunction, insulin resistance, oxidative stress, inflammation, apoptosis, fibrosis and gut microbiota dysbiosis. Except for lifestyle modification and bariatric surgery, there has been no pharmacological therapy that is being officially approved in NASH treatment. Traditional Chinese medicine (TCM), as a conventional and effective therapeutic strategy, has been proved to be beneficial in treating NASH in numbers of studies. In the light of this, TCM may provide a potential therapy for treating NASH. In this review, we summarized the associated mechanisms of action TCM treating NASH in preclinical studies and systematically analysis the effectiveness of TCM treating NASH in current clinical trials.

Traditional Chinese Medicine in nonalcoholic fatty liver disease: molecular insights and therapeutic perspectives

Nonalcoholic fatty liver disease (NAFLD) has become the world's largest chronic liver disease, while there is still no specific drug to treat NAFLD. Traditional Chinese Medicine (TCM) have been widely used in hepatic diseases for centuries in Asia, and TCM's holistic concept and differentiation treatment of NAFLD show their advantages in the treatment of this complex metabolic disease. However, the multi-compounds and multi-targets are big obstacle for the study of TCM. Here, we summarize the pharmacological actions of active ingredients from frequently used single herbs in TCM compounds. The combined mechanism of herbs in TCM compounds are further discussed to explore their comprehensive effects on NAFLD. This article aims to summarize multiple functions and find the common ground for TCM treatment on NAFLD, thus providing enrichment to the scientific connotation of TCM theories and promotes the exploration of TCM therapies on NAFLD.

Anti-Autophagy Mechanism of Zhi Gan Prescription Based on Network Pharmacology in Nonalcoholic Steatohepatitis Rats

Background and Aims: Zhi Gan prescription (ZGP) has been clinically proven to exert a favorable therapeutic effect on nonalcoholic steatohepatitis (NASH). This study purpose to reveal the underlying molecular mechanisms of ZGP action in NASH. Methods: Systematic network pharmacology was used to identify bioactive components, potential targets, and the underlying mechanism of ZGP action in NASH. High fat (HF)-induced NASH model rats were used to assess the effect of ZGP against NASH, and to verify the possible molecular mechanisms as predicted by network pharmacology. Results: A total of 138 active components and 366 potential targets were acquired in ZGP. In addition, 823 targets of NASH were also screened. In vivo experiments showed that ZGP significantly improved the symptoms in HF-induced NASH rats. qRT-PCR and western blot analyses showed that ZGP could regulate the hub genes, PTEN, IL-6 and TNF in NASH model rats. In addition, ZGP suppressed mitochondrial autophagy through mitochondrial fusion and fission via the PINK/Parkin pathway. Conclusion: ZGP exerts its effects on NASH through mitochondrial autophagy. These findings provide novel insights into the mechanisms of ZGP in NASH.

Alisol A 24-acetate protects against brain microvascular endothelial cells injury through inhibiting miR-92a-3p/tight junctions axis

Blood brain barrier (BBB) dysfunction developed with aging is related to brain microvascular endothelial cells (BMECs) injury and losses of tight junctions (TJs). In the present study, we found that Alisol A 24-acetate (AA), a natural compound frequently used as treatment against vascular diseases was essential for BMECs injury and TJs degradation. Our experimental results showed that AA enhanced cell viability and increased zonula occludens-1 (ZO-1), claudin-5, and occludin expression in the oxygen-glucose deprivation (OGD)-induced BMECs. The exploration of the underlying mechanism revealed that AA restrained miR-92a-3p, a noncoding RNA involved in endothelial cells senescence and TJs impairment. To test the role of the miR-92a-3p in BMECs, the cells were transfected with miR-92a-3p mimics and inhibitor. The results showed that miR-92a-3p mimics inhibited cell viability and elevated lactate dehydrogenase (LDH) levels as well as suppressed ZO-1, claudin-5 and occludin expression, while the miR-92a-3p inhibitor reversed the above results. These findings were similar to the therapeutic effects of AA in the OGD-induced BMECs. Bioinformatics analysis and dual-luciferase assay confirmed ZO-1 and occludin were the target genes of miR-92a-3p mediated AA protective roles. In summary, the data demonstrated that AA protected against BMECs damage and TJs loss through the inhibition of miR-92a-3p expression. This provided evidence for AA application in aging-associated BBB protection.

A link between chemical structure and biological activity in triterpenoids

BACKGROUND

Plants with triterpenoid compounds in nature have various biological activities and are reported in many scientific works of literature. Triterpenoids are compounds that draw the attention of scientists because of their wide source, wide variety, high medicinal value, and anti-tumor properties. However, a lack of approach to understand their chemical structures has limited the fundamental comprehension of these compounds in cancer cell therapy.

OBJECTIVE

To seek anti-cancer activity of the structures of triterpenoid compounds and their derivatives, we summarized a number of plants and their derivatives that are a source of potential novel therapeutic anti-cancer agents.

METHODS

This work focuses on relevant 1036 patents and references that detail the structure of organic compounds and derivatives for the treatment of tumors.

RESULT

Compared to tetracyclic triterpenoid, pentacyclic triterpenoid has contributed more to improve the autophagic signaling pathways of cancer cells.

CONCLUSION

The heterogenous skeleton structure of triterpenoids impaired the programmed cell death signaling pathway in various cancers.

Alisol A 24-acetate stimulates lipolysis in 3 T3-L1 adipocytes

BACKGROUND

Alisol A 24-acetate (AA-24-a), one of the main active triterpenes isolated from the well-known medicinal plant Alisma orientale (Sam.) Juz., exhibits multiple biological activities including hypolipidemic activity. However, its effect on lipid metabolism in adipocytes remains unclear. The present study aimed to clarify the effect of AA-24-a on adipocyte lipolysis and to determine its potential mechanism of action using 3 T3-L1 cells.

METHODS

We assayed the release of glycerol into culture medium of 3 T3-L1 cells under treatment with AA-24-a. Protein and mRNA expression and phosphorylation levels of the main lipases and kinases involved in lipolysis regulation were determined by quantitative polymerase chain reaction and western blotting. Specific inhibitors of protein kinase A (PKA; H89) and extracellular signal-regulated kinase (ERK; PD98059), which are key enzymes in relevant signaling pathways, were used to examine their roles in AA-24-a-stimulated lipolysis.

RESULTS

AA-24-a significantly stimulated neutral lipolysis in fully differentiated adipocytes. To determine the underlying mechanism, we assessed the changes in mRNA and protein levels of key lipolysis-related genes in the presence or absence of H89 and PD98059. Both inhibitors reduced AA-24-a-induced lipolysis. Moreover, pretreatment with H89 attenuated AA-24-a-induced phosphorylation of hormone-sensitive lipase at Ser660, while pretreatment with PD98059 attenuated AA-24-a-induced downregulation of peroxisome proliferator-activated receptor-γ and perilipin A.

CONCLUSIONS

Our results indicate that AA-24-a promoted neutral lipolysis in 3 T3-L1 adipocytes by activating PKA-mediated phosphorylation of hormone-sensitive lipase and ERK- mediated downregulation of expression of perilipin A.

Autophagy in Hepatic Steatosis: A Structured Review

Steatosis is the accumulation of neutral lipids in the cytoplasm. In the liver, it is associated with overeating and a sedentary lifestyle, but may also be a result of xenobiotic toxicity and genetics. Non-alcoholic fatty liver disease (NAFLD) defines an array of liver conditions varying from simple steatosis to inflammation and fibrosis. Over the last years, autophagic processes have been shown to be directly associated with the development and progression of these conditions. However, the precise role of autophagy in steatosis development is still unclear. Specifically, autophagy is necessary for the regulation of basic metabolism in hepatocytes, such as glycogenolysis and gluconeogenesis, response to insulin and glucagon signaling, and cellular responses to free amino acid contents. Also, genetic knockout models for autophagy-related proteins suggest a critical relationship between autophagy and hepatic lipid metabolism, but some results are still ambiguous. While autophagy may seem necessary to support lipid oxidation in some contexts, other evidence suggests that autophagic activity can lead to lipid accumulation instead. This structured literature review aims to critically discuss, compare, and organize results over the last 10 years regarding rodent steatosis models that measured several autophagy markers, with genetic and pharmacological interventions that may help elucidate the molecular mechanisms involved.

Alleviation of non-alcoholic fatty liver disease by Huazhi Fugan Granules is associated with suppression of TLR4/NF-κB signaling pathway

INTRODUCTION

In parallel with the improvement of living standard, Non-alcoholic fatty liver disease (NAFLD) becomes the most common liver disease around the world. Huazhi Fugan Granules (HZFGG) is a formula which is used to treating of fatty liver, Based on the data we studied, HZFGG may have potential as a therapeutic formula for the alleviation of NAFLD.

OBJECTIVES

The aim of our study was to identifying the improvement of HZFGG on NAFLD and exploring the potential mechanisms.

METHODS

MCD diet fed C57BL/6 mice once a day for 4 weeks to induce NAFLD model, HZFGG (10, 15, 20g/kg) orally administered simultaneously. The serum levels of TC, TG, ALT, AST were detected. H&E and Oil Red O staining were used to observed the liver sections. TNF-α, IL-1β and Gpx were also detected. The expression levels of TLR4, MyD88, p-NF-κB, NF-κB, p-IκBa were measured by western blotting assay. The apoptosis of the liver tissues were detected by TUNEL assay.

RESULTS

HZFGG decreased the serum levels of TC, TG, ALT, AST in MCD-diet mice. HZFGG alleviated inflammation by decreasing the levels of TNF-α and IL-1β and ameliorated oxidative stress through increased the level of Gpx. HZFGG Attenuates MCD-induced liver steatosis and injury in mice. Hepatocyte apoptosis was decreased after HZFGG treatment. Furthermore, HZFGG also suppressed the expression levels of TLR4 and MyD88, subsequently, inhibited the phosphorylation of NF-κB and IκBa.

CONCLUSION

HZFGG can improved MCD induced hepatic injury through inhibited TLR4/NF-κB signaling pathway in NAFLD model.

Alisol A-24-acetate promotes glucose uptake via activation of AMPK in C2C12 myotubes

BACKGROUND

Alisol A-24-acetate (AA-24-a) is one of the main active triterpenes isolated from the well-known medicinal plant Alisma orientale (Sam.) Juz., which possesses multiple biological activities, including a hypoglycemic effect. Whether AA-24-a is a hypoglycemic-active compound of A. orientale (Sam.) Juz. is unclear. The present study aimed to clarify the effect and potential mechanism of action of AA-24-a on glucose uptake in C2C12 myotubes.

METHOD

Effects of AA-24-a on glucose uptake and GLUT4 translocation to the plasma membrane were evaluated. Glucose uptake was determined using a 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG) uptake assay. Cell membrane proteins were isolated and glucose transporter 4 (GLUT4) protein was detected by western blotting to examine the translocation of GLUT4 to the plasma membrane. To determine the underlying mechanism, the phosphorylation levels of proteins involved in the insulin and 5'-adenosine monophosphate-activated protein kinase (AMPK) pathways were examined using western blotting. Furthermore, specific inhibitors of key enzymes in AMPK signaling pathway were used to examine the role of these kinases in the AA-24-a-induced glucose uptake and GLUT4 translocation.

RESULTS

We found that AA-24-a significantly promoted glucose uptake and GLUT4 translocation in C2C12 myotubes. AA-24-a increased the phosphorylation of AMPK, but had no effect on the insulin-dependent pathway involving insulin receptor substrate 1 (IRS1) and protein kinase B (PKB/AKT). In addition, the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and the AKT substrate of 160 kDa (AS160), two proteins that act downstream of AMPK, was upregulated. Compound C, an AMPK inhibitor, blocked AA-24-a-induced AMPK pathway activation and reversed AA-24-a-induced glucose uptake and GLUT4 translocation to the plasma membrane, indicating that AA-24-a promotes glucose metabolism via the AMPK pathway in vitro. STO-609, a calcium/calmodulin-dependent protein kinase kinase β (CaMKKβ) inhibitor, also attenuated AA-24-a-induced glucose uptake and GLUT4 translocation. Moreover, STO-609 weakened AA-24-a-induced phosphorylation of AMPK, p38 MAPK and AS160.

CONCLUSIONS

These results indicate that AA-24-a isolated from A. orientale (Sam.) Juz. significantly enhances glucose uptake via the CaMKKβ-AMPK-p38 MAPK/AS160 pathway.

Chinese Medicinal Herbs Targeting the Gut-Liver Axis and Adipose Tissue-Liver Axis for Non-Alcoholic Fatty Liver Disease Treatments: The Ancient Wisdom and Modern Science

Non-alcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. The pathogenesis of NAFLD is complex. Frontline western medicines only ameliorate the symptoms of NAFLD. On the contrary, the uniqueness of Chinese medicine in its interpretation of NAFLD and the holistic therapeutic approach lead to a promising therapeutic efficacy. Recent studies reveal that the gut-liver axis and adipose tissue-liver axis play important roles in the development of NAFLD. Interestingly, with advanced technology, many herbal formulae are found to target the gut-liver axis and adipose tissue-liver axis and resolve the inflammation in NAFLD. This is the first review summarizes the current findings on the Chinese herbal formulae that target the two axes in NAFLD treatment. This review not only demonstrates how the ancient wisdom of Chinese medicine is being interpreted by modern pharmacological studies, but also provides valuable information for the further development of the herbal-based treatment for NAFLD.

Hepatoprotective Effect of Jianpi Huoxue Formula on Nonalcoholic Fatty Liver Disease Induced by Methionine-Choline-Deficient Diet in Rat

In parallel with the prevalence metabolic syndrome, nonalcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in most countries. It features a constellation of simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and even hepatocellular carcinoma. There are no approved drugs for effective management of NAFLD and NASH. Jianpi Huoxue formula (JPHX) mainly consists of Atractylodes macrocephal (Baizhu), Salvia miltiorrhiza (Danshen), Rasux Paeonia Alba (Baishao), Rhizoma Alismatis (Zexie), and Fructus Schisandrae Chinensis (Wuweizi), which may have beneficial effects on NAFLD. The aim of the study was to identify the effect of JPHX on NAFLD. A NAFLD model was induced by methionine-choline-deficient food (MCD) in Wistar rats and orally administered with simultaneous JPHX, once a day for 8 weeks. Hepatocellular injury, lipid profile, inflammation, fibrosis, and apoptosis were evaluated. The results showed that JPHX significantly decreased the abnormal serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels compared with the MCD model (P<0.05). Furthermore, JPHX protected MCD diet-fed rats from accumulation of hepatic triglycerides (TG) and total cholesterol (TC). Histological examination demonstrated that JPHX noticeably normalized the NAFLD activity score (NAS). Moreover, JPHX ameliorated liver inflammation by decreasing TNF-α levels and reduced collagen and matrix metalloproteinases in MCD diet-fed rats. In addition, JPHX prevented rats from MCD-induced cellular apoptosis, as suggested by TUNEL staining, and suppressed the activation of caspase 3 and 7 proteins. JPHX also inhibited the phosphorylation of JNK. In conclusion, JPHX exhibited a hepatoprotective effect against NAFLD in an MCD experimental model.

Pharmacological Activities of Alisma orientale against Nonalcoholic Fatty Liver Disease and Metabolic Syndrome: Literature Review

Nonalcoholic fatty liver disease (NAFLD) is a rapidly emerging hepatic manifestation of metabolic syndrome. However, its unrevealed mechanism and complicated comorbidities have led to no specific medication, except for weight loss and lifestyle modification. Alisma orientale (Sam.) Juzep (A. orientale, Alismataceae) has been increasingly reported on therapeutic effects of A. orientale against NAFLD and metabolic syndrome such as insulin resistance, hyperlipidemia, and obesity. Therefore, this study aimed to review the preclinical efficacy of A. orientale and its chemical constituents including Alisol A 24-acetate, Alisol B 23-acetate, Alisol F, and Alismol against NAFLD and metabolic syndrome. A. orientale prevented hepatic triglyceride accumulation through suppressing de novo lipogenesis and increasing lipid export. In addition, it controlled oxidative stress markers, lipoapoptosis, liver injury panels, and inflammatory and fibrotic mediators, eventually influencing steatohepatitis and liver fibrosis. Moreover, it exhibited pharmacological activities against hyperlipidemia, obesity, and hyperglycemia as well as appetite. These biological actions of A. orientale might contribute to adiponectin activation or a role as a farnesoid X receptor agonist. In particular, Alisol A 24-acetate and Alisol B 23-acetate could be expected as main compounds. Taken together, A. orientale might be an effective candidate agent for the treatment of NAFLD and its comorbidities, although further assessment of its standardization, safety test, and clinical trials is consistently required.

Alisol A attenuates high-fat-diet-induced obesity and metabolic disorders via the AMPK/ACC/SREBP-1c pathway

Obesity and its associated metabolic disorders such as diabetes, hepatic steatosis and chronic heart diseases are affecting billions of individuals. However there is no satisfactory drug to treat such diseases. In this study, we found that alisol A, a major active triterpene isolated from the Chinese traditional medicine Rhizoma Alismatis, could significantly attenuate high‐fat‐diet‐induced obesity. Our biochemical detection demonstrated that alisol A remarkably decreased lipid levels, alleviated glucose metabolism disorders and insulin resistance in high‐fat‐diet‐induced obese mice. We also found that alisol A reduced hepatic steatosis and improved liver function in the obese mice model.In addition, protein expression investigation revealed that alisol A had an active effect on AMPK/ACC/SREBP‐1c pathway. As suggested by the molecular docking study, such bioactivity of alisol A may result from its selective binding to the catalytic region of AMPK.Therefore, we believe that Alisol A could serve as a promising agent for treatment of obesity and its related metabolic diseases.

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.