Gypenosides improves nonalcoholic fatty liver disease induced by high-fat diet induced through regulating LPS/TLR4 signaling pathway

Effects of Saponins on Lipid Metabolism: The Gut-Liver Axis Plays a Key Role

Unhealthy lifestyles (high-fat diet, smoking, alcohol consumption, too little exercise, etc.) in the current society are prone to cause lipid metabolism disorders affecting the health of the organism and inducing the occurrence of diseases. Saponins, as biologically active substances present in plants, have lipid-lowering, inflammation-reducing, and anti-atherosclerotic effects. Saponins are thought to be involved in the regulation of lipid metabolism in the body; it suppresses the appetite and, thus, reduces energy intake by modulating pro-opiomelanocortin/Cocaine amphetamine regulated transcript (POMC/CART) neurons and neuropeptide Y/agouti-related peptide (NPY/AGRP) neurons in the hypothalamus, the appetite control center. Saponins directly activate the AMP-activated protein kinase (AMPK) signaling pathway and related transcriptional regulators such as peroxisome-proliferator-activated-receptors (PPAR), CCAAT/enhancer-binding proteins (C/EBP), and sterol-regulatory element binding proteins (SREBP) increase fatty acid oxidation and inhibit lipid synthesis. It also modulates gut-liver interactions to improve lipid metabolism by regulating gut microbes and their metabolites and derivatives-short-chain fatty acids (SCFAs), bile acids (BAs), trimethylamine (TMA), lipopolysaccharide (LPS), et al. This paper reviews the positive effects of different saponins on lipid metabolism disorders, suggesting that the gut-liver axis plays a crucial role in improving lipid metabolism processes and may be used as a therapeutic target to provide new strategies for treating lipid metabolism disorders.

Gypenoside XVII inhibits ox-LDL-induced macrophage inflammatory responses and promotes cholesterol efflux through activating the miR-182-5p/HDAC9 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The deposition of lipids in macrophages and the subsequent formation of foam cells significantly increase the risk of developing atherosclerosis (As). Targeting ATP-binding cassette transporter A1/G1 (ABCA1/ABCG1)-mediated reverse cholesterol transport is crucial for regulating foam cell formation. Therefore, the search for natural chemical components with the ability to regulate ABCA1/G1 is a potential drug target to combat the development of atherosclerosis. Gypenoside XVII (GP-17), a gypenoside monomer extracted from gynostemma pentaphyllum, presents an efficient anti-atherosclerosis function. However, the suppressed formation mechanism of foam cells by GP-17 remains elusive.

AIM OF STUDY

To explore the protective activities of GP-17 in ox-LDL-induced THP-1 macrophage-derived foam cells through modulating the promotion of cholesterol efflux and alleviation of inflammation.

MATERIALS AND METHODS

MTT was used to detect cell viability. Bodipy493/503 and oil red O staining were performed to measure cell lipid deposition. Enzymatic assay was used to measure intracellular cholesterol measurement. Cholesterol efflux/uptake were determined by cholesterol efflux assay and Dil-ox-LDL uptake assay. Inflammatory cytokines were measured by ELISA. Bioinformatics prediction and dual luciferase reporter assay were performed to validate miR-182-5p targeting HDAC9. Relative protein levels were evaluated by immunoblotting and relative gene levels were determined by quantitative real-time PCR.

RESULTS

Our results showed that GP-17 upregulated the expression of ABCA1, ABCG1 and miR-182-5p, but reduced HDAC9 expression levels in lipid-loaded macrophages, which promoted cholesterol efflux and inhibited lipid deposition. Additionally, GP-17 promoted the M2 phenotype of the macrophage and suppressed the inflammatory response in THP-1 macrophage-derived foam cells. Overexpression of HDAC9 or suppression of miR-182-5p eliminated the effects of ABCA1/G1 expression, lipid deposition and pro-inflammatory response.

CONCLUSION

These findings suggest that GP-17 exerts a beneficial effect on macrophage lipid deposition and inflammation responses through activating the miR-182-5p/HDAC9 signaling pathway.

Immunology of gut microbiome and liver in non-alcoholic fatty liver disease (NAFLD): mechanisms, bacteria, and novel therapeutic targets

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world. Most important contributors to its development are diet and obesity. Gut microbiome's importance for immune system and inflammatory pathways more widely accepted as an important component in NAFLD and other liver diseases' pathogenesis. In this article we review potential mechanisms of microbiome alteration of local and systemic immune responses leading to NAFLD's development, and how can modulate them for the treatment. Our review mentions different immune system pathways and microorganisms regulating metabolism, liver inflammation and fibrosis. We specifically point out TLR-4 as a potential key immune pathway activated by bacterial lipopolysaccharides producing pro-inflammatory cytokines in NAFLD. Also, we discuss three endotoxin-producing strains (Enterobacter cloacae B29, Escherichia coli PY102, Klebsiella pneumoniae A7) that can promote NAFLD development via TLR4-dependent immune response activation in animal models and how they potentially contribute to disease progression in humans. Additionally, we discuss their other immune and non-immune mechanisms contributing to NAFLD pathogenesis. In the end we point out gut microbiome researches' future perspective in NAFLD as a potential new target for both diagnostic and treatment.

Traditional Chinese Medicine in Osteoporosis Intervention and the Related Regulatory Mechanism of Gut Microbiome

The gut microbiome (GM) has become a crucial factor that can affect the progression of osteoporosis. A number of studies have demonstrated the impact of Traditional Chinese Medicine (TCM) on GM and bone metabolism. In this review, we summarize the potential mechanisms of the relationship between osteoporosis and GM disorder and introduce several natural Chinese medicines that exert anti-osteoporosis effects by modulating the GM. It is underlined that, through the provision of the microbial associated molecular pattern (MAMP), the GM causes inflammatory reactions and alterations in the Treg-Th17 balance and ultimately leads to changes in bone mass. Serotonin and many hormones, especially estrogen, may play a crucial role in the interaction of the GM with bone metabolism. Additionally, the GM may affect the absorption of specific nutrients in the intestine, particularly minerals like calcium, magnesium, and phosphorus. Several natural Chinese herbs, such as Sambucus Williamsii, Achyranthes bidentata Blume, Pleurotus ostreatus and Ganoderma lucidum mushrooms, Pueraria Lobata, and Agaricus blazei Murill have exhibited anti-osteoporosis effects through regulating the distribution and metabolism of the GM. These herbs may increase the abundance of Firmicutes, decrease the abundance of Bacteroides, promote the GM to produce more SCFAs, modulate the immune response caused by harmful bacteria, and increase the proportion of Treg-Th17 to indirectly affect bone metabolism. Moreover, gut-derived 5-HT is an important target for TCM to prevent osteoporosis via the gut-bone axis. Puerarin could prevent osteoporosis by improving intestinal mucosal integrity and decrease systemic inflammation caused by estrogen deficiency.

Gypenosides suppress hepatocellular carcinoma cells by blocking cholesterol biosynthesis through inhibition of MVA pathway enzyme HMGCS1

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors with high morbidity and mortality. Targeting abnormal cholesterol metabolism is a potential therapeutic direction. Therefore, more natural drugs targeting cholesterol in HCC need to be developed. Gypenosides (Gyp), the major constituent of Gynostemma pentaphyllum, has been demonstrated to have pharmacological properties on anti-cancer, anti-obesity, and hepatoprotective. We investigated whether Gyp, isolated and purified by our lab, could inhibit HCC progression by inhibiting cholesterol synthesis. The present research showed that Gyp inhibited proliferation and migration, and induced apoptosis in Huh-7 and Hep3B cells. Metabolomics, transcriptomics, and target prediction all suggested that lipid metabolism and cholesterol biosynthesis were the mechanisms of Gyp. Gyp could limit the production of cholesterol and target HMGCS1, the cholesterol synthesis-related protein. Downregulation of HMGCS1 could suppress the progression and abnormal cholesterol metabolism of HCC. In terms of mechanism, Gyp suppressed mevalonate (MVA) pathway mediated cholesterol synthesis by inhibiting HMGCS1 transcription factor SREBP2. And the high expression of HMGCS1 in HCC human specimens was correlated with poor clinical prognosis. The data suggested that Gyp could be a promising cholesterol-lowering drug for the prevention and treatment of HCC. And targeting SREBP2-HMGCS1 axis in MVA pathway might be an effective HCC therapeutic strategy.

Gypenosides Synergistically Reduce the Extracellular Matrix of Hepatic Stellate Cells and Ameliorate Hepatic Fibrosis in Mice

Liver fibrosis resulting from chronic liver damage is becoming one of the major threats to health worldwide. Active saponin constituents isolated from Gynostemma pentaphyllum were found to possess a protective effect in liver diseases. Here, we obtained a naturally abundant gypenoside, XLVI, and evaluated its liver protection activity in both animal and cellular models. The results showed that it ameliorated acute and chronic liver injuries and lightened the process of fibrogenesis in vivo. XLVI can inhibit TGF-β-induced activation of hepatic stellate cells and ECM deposition in vitro. The underlying mechanism study verified that it upregulated the protein expression of protein phosphatase 2C alpha and strengthened the vitality of the phosphatase together with a PP2Cα agonist gypenoside NPLC0393. These results shed new light on the molecular mechanisms and the potential therapeutic function of the traditional herb Gynostemma pentaphyllum in the treatment of liver fibrosis.

Gypenosides suppress fibrosis of the renal NRK-49F cells by targeting miR-378a-5p through the PI3K/AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

The incidence of renal fibrosis caused by chronic kidney disease is increasing year by year. Preventing the activation and conversion of kidney-intrinsic fibroblasts to a myofibroblast phenotype is an important target for blocking the development of renal interstitial fibrosis. Our team established a stable renal interstitial fibrosis cell model in the early stage, and the screening results showed that GPs has good anti-fibrosis potential. At this stage, only a few literatures have reported its anti-fibrosis effect, and the mechanism of action is still unclear.

AIM OF THE STUDY

The massive synthesis and secretion of extracellular-matrix (ECM) components by activated fibroblasts in the kidneys causes irreversible renal interstitial fibrosis. Gypenosides (GPs) have been shown to decelerate this process, in which micro RNAs (miRNAs) play an important regulatory role. This study aimed to evaluate the mechanism underlying the suppressive effect of GPs on renal fibrosis.

MATERIALS AND METHODS

This study used TGF-β1-stimulated NRK-49F renal cells as an in-vitro model of renal interstitial fibrosis. First, the concentration range of GPs that significantly affects the cytoactive was determined. Then, the anti-fibrotic effects of various concentrations of GPs in the in-vitro model were assessed via immunofluorescence, western blotting, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Non-coding-RNA sequencing combined with bioinformatics was used to predict the mechanistic basis of the anti-fibrotic effect of GPs, and qRT-PCR was used to verify the sequencing results and bioinformatic predictions. The identified relationships of the anti-fibrotic effect of GPs with miR-378a-5p and the PI3K/AKT signaling were evaluated using a miR-NC mimic and the PI3K inhibitor LY294002 as controls, respectively.

RESULTS

TGF-β1 stimulation up-regulated α-SMA, COL1, and COL3 in NRK-49F cells, and this effect was suppressed by GPs. Additionally, TGF-β1 stimulation significantly changed the expression levels of 151 miRNAs, and GPs significantly suppressed the effect of TGF-β1 on the levels of 18 of these miRNAs. Among them, miR-3588 and miR-378a-5p were down-regulated, and miR-135b-5p and miR-3068-5p were up-regulated upon TGF-β1 induction. Of these miRNAs, miR-378a-5p was predicted to target the mRNAs of numerous proteins mainly enriched in the PI3K/AKT signaling pathway. The miRNA transfection experiments with the miR-NC mimic and PI3K inhibitor as controls showed that miR-378a-5p overexpression could suppress the TGF-β1-induced up-regulation of α-SMA, COL1, PI3K, and AKT, including the phosphorylated form (p-AKT).

CONCLUSION

GPs inhibit the PI3K/AKT signaling by up-regulating miR-378a-5p in TGF-β1-stimulated NRK-49F cells and thereby reduce their massive secretion of ECM components. Given that this in-vitro model of renal interstitial fibrosis closely mimics the in-vivo pathogenesis, our results most likely apply to the in-vivo conditions.

Gypenosides ameliorate ductular reaction and liver fibrosis via inhibition of hedgehog signaling

Backgroud and aims: Ductular reaction (DR) is a common pathological change and thought to have a key role in the pathogenesis and progression of liver fibrosis. Our previous study reported Gypenosides (GPs) ameliorated liver fibrosis, however, the anti-fibrotic mechanisms of GPs are still unclear. Methods: Liver fibrosis was induced in rats by carbon tetrachloride combining with 2-acerylaminofluorene (CCl4/2-AAF), and Mdr2 knockout (Mdr2 -/-) mice to evaluate the anti-fibrotic role of GPs. In vitro, WB-F344 cells, a hepatic progenitor cells (HPCs) line, with or without Gli1 overexpressing lentiviral vectors, were induced by sodium butyrate (SB) to validate the mechanism of GPs and NPLC0393, the main ingredient of GPs. Results: Both in CCl4/2-AAF-treated rats and Mdr2 -/- mice, GPs obviously reduced the deposition of collagen and hydroxyproline content, inhibited the activation of hepatic stellate cells and inflammatory cell infiltration. Notably, GPs reduced the expressions of Epcam, CK19, CK7, Dhh, Smo, Ptch2, Gli1 and Gli2. Furthermore, CK19+ cells co-expressed Gli1, while the number of CK19+/Gli1+ cells was decreased by GPs. In vitro, GPs and NPLC0393 inhibited the differentiation of WB-F344 cells toward a biliary phenotype. Mechanistically, GPs and NPLC0393 protected against DR by inhibiting hedgehog signaling, which was supported by the results that DR, triggered directly by Gli1 overexpressing lentiviral vector was blocked by administration with GPs or NPLC0393. Conclusion: GPs attenuated DR and liver fibrosis by inhibiting hedgehog signaling, which provided more evidences and a novel mechanism of anti-fibrotic effect of GPs.

Research Progress on the Therapeutic Effect of Polysaccharides on Non-Alcoholic Fatty Liver Disease through the Regulation of the Gut–Liver Axis

Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease affecting global public health at present, which can induce cirrhosis and liver cancer in serious cases. However, NAFLD is a multifactorial disease, and there is still a lack of research on its mechanism and therapeutic strategy. With the development of the gut–liver axis theory, the association between the gut–liver axis and the pathogenesis of NAFLD has been gradually disclosed. Polysaccharides, as a kind of natural product, have the advantages of low toxicity, multi-target and multi-pathway action. It has been reported that polysaccharides can affect the gut–liver axis at multiple interrelated levels, such as maintaining the ecological balance of gut microbiota (GM), regulating the metabolites of GM and improving the intestinal barrier function, which thereby plays a protective role in NAFLD. These studies have great scientific significance in understanding NAFLD based on the gut–liver axis and developing safe and effective medical treatments. Herein, we reviewed the recent progress of polysaccharides in improving nonalcoholic fatty liver disease (NAFLD) through the gut–liver axis.

Anti-Inflammatory Effects and Mechanisms of Dandelion in RAW264.7 Macrophages and Zebrafish Larvae

Dandelions (Taraxacum spp.) play an important role in the treatment of inflammatory diseases. In this study, we investigated the anti-inflammatory effects of Dandelion Extract (DE) in LPS-induced RAW264.7 macrophages and copper sulfate (CuSO4)-induced zebrafish larvae. DE was not toxic to RAW264.7 cells at 75 μg/ml as measured by cell viability, and DE inhibited LPS-induced cell morphological changes as measured by inverted microscopy. In survival experiments, DE at 25 μg/ml had no toxicity to zebrafish larvae. By using an enzymatic standard assay, DE reduced the production of nitric oxide (NO) in LPS-induced RAW264.7 cells. Fluorescence microscopy results show that DE reduced LPS-induced ROS production and apoptosis in RAW264.7 cells. DE also inhibited CuSO4-induced ROS production and neutrophil aggregation in zebrafish larvae. The results of flow cytometry show that DE alleviated the LPS-induced cell cycle arrest. In LPS-induced RAW264.7 cells, RT-PCR revealed that DE decreased the expression of M1 phenotypic genes iNOS, IL-6, and IL-1β while increasing the expression of M2 phenotypic genes IL-10 and CD206. Furthermore, in CuSO4-induced zebrafish larvae, DE reduced the expression of iNOS, TNF-α, IL-6, and IL-10. The findings suggest that DE reduces the LPS-induced inflammatory response in RAW264.7 cells by regulating polarization and apoptosis. DE also reduces the CuSO4-induced inflammatory response in zebrafish larvae.

Gypenosides ameliorate high-fat diet-induced non-alcoholic steatohepatitis via farnesoid X receptor activation

Background

Gypenosides (Gyps), the major botanical component of Gynostemma pentaphyllum, was found to up-regulate the farnesoid X receptor (FXR) in a mouse model of non-alcoholic steatohepatitis (NASH). However, the exact role of FXR and underlying mechanisms in Gyps-mediated effects on NASH remain to be elucidated.

Purpose

This study investigated whether Gyps attenuates NASH through directly activating FXR in high-fat diet (HFD)-induced NASH, and delineated the molecular pathways involved.

Study design

A mouse model of HFD-induced NSAH was used to examine effects of Gyps on NASH with obeticholic acid (OCA) as a positive control, and the role of FXR in its mechanism of action was investigated in wild-type (WT) and FXR knockout (KO) mice.

Methods

WT or FXR KO mice were randomly assigned into four groups: normal diet (ND) group as negative control, HFD group, HFD + Gyps group, or HFD + OCA group.

Results

Treatment with Gyps and OCA significantly improved liver histopathological abnormalities in HFD-induced NASH, reduced the non-alcoholic fatty liver disease (NAFLD) activity score (NAS), and lowered hepatic triglyceride (TG) content compared with the HFD group. In agreement with these liver tissue changes, biochemical tests of blood samples revealed that alanine aminotransferase (ALT), aspartate aminotransferase (AST), TG, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), fasting blood glucose (FBG), and fasting insulin (FINS) levels were significantly lower in the HFD + Gyps vs. HFD group. Furthermore, Gyps and OCA treatment significantly up-regulated hepatic FXR, small heterodimer partner (SHP), carnitine palmitoyltransferase 1A (CPT1A), and lipoprotein lipase (LPL) expression, and significantly down-regulated sterol-regulatory element binding protein 1 (SREBP1), fatty acid synthetase (FASN), and stearoyl-CoA desaturase 1 (SCD1) protein levels compared with the HFD group in WT mice but not in FXR KO mice. Notably, Gyps- and OCA-mediated pharmacological effects were significantly abrogated by depletion of the FXR gene in FXR KO mice.

Conclusion

Gyps ameliorated HFD-induced NASH through the direct activation of FXR and FXR-dependent signaling pathways.

Fucoxanthin Attenuates Free Fatty Acid-Induced Nonalcoholic Fatty Liver Disease by Regulating Lipid Metabolism/Oxidative Stress/Inflammation via the AMPK/Nrf2/TLR4 Signaling Pathway

Fucoxanthin, a xanthophyll carotenoid abundant in brown algae, is reported to have several biological functions, such as antioxidant, anti-inflammatory, and anti-tumor activities, in mice. We investigated the effects and mechanisms of fucoxanthin in the mixture oleate/palmitate = 2/1(FFA)-induced nonalcoholic fatty liver disease (NAFLD) cell model in this study. The results showed that the content of superoxide dismutase in the FFA group was 9.8 ± 1.0 U/mgprot, while that in the fucoxanthin high-dose (H-Fx) group (2 μg/mL) increased to 22.9 ± 0.6 U/mgprot. The content of interleukin-1β in the FFA group was 89.3 ± 3.6 ng/mL, while that in the H-Fx group was reduced to 53.8 ± 2.8 ng/mL. The above results indicate that fucoxanthin could alleviate the FFA-induced oxidative stress and inflammatory levels in the liver cells. Oil red-O staining revealed visible protrusions and a significant decrease in the number of lipid droplets in the cytoplasm of cells in the fucoxanthin group. These findings on the mechanisms of action suggest that fucoxanthin can repair FFA-induced NAFLD via the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway and nuclear factor erythroid-2-related factor 2-mediated (Nrf2) signaling pathway, as well as by downregulating the expression of the Toll-like receptor 4-mediated (TLR4) signaling pathway. Fucoxanthin exhibited alleviating effects in the FFA-induced NAFLD model and could be explored as a potential anti-NAFLD substance.

Prebiotic properties of jiaogulan in the context of gut microbiome

Jiaogulan (Gynostemma pentaphyllum) is a traditional Chinese medicinal herb that has been widely used in food and supplemental products. In the last 20 years, extensive research has been conducted to investigate the medicinal prospects of jiaogulan, and in this regard, more than 200 compounds have been isolated with various medicinal properties such as anticancer, anti-obesity, anti-inflammation, and antioxidation. In respect of potential benefits, jiaogulan market is likely growing, and various food items comprised of jiaogulan (beverage, sport drinks, cola, beer, tea, bread, and noodles) have been commercialized in the United States of America, China, and other Asian countries. More recently, there has been growing interest in the prebiotic potential of jiaogulan, especially at the interface of the gut microbiota. This review focuses on the prebiotic and therapeutic aspects of saponins and polysaccharides of jiaogulan tea by summarizing the literature on cancer, obesity, antioxidant activity, and immune-modulatory properties.