Total flavonoids of Broussonetia papyrifera alleviate non-alcohol fatty liver disease via regulating Nrf2/AMPK/mTOR signaling pathways.

BACKGROUNDS: Non-alcoholic fatty liver disease (NAFLD) is one of the most prevalent chronic liver diseases. The leaves of Broussonetia papyrifera contain a large number of flavonoids, which have a variety of biological functions. METHODS: In vitro experiments, free fatty acids were used to stimulate HepG2 cells. NAFLD model was established in vivo in mice fed with high fat diet (HFD) or intraperitoneally injected with Tyloxapol (Ty). At the same time, Total flavonoids of Broussonetia papyrifera (TFBP) was used to interfere with HepG2 cells or mice. RESULTS: The results showed that TFBP significantly decreased the lipid accumulation induced by oil acid (OA) with palmitic acid (PA) in HepG2 cells. TFBP decreased the total cholesterol (TC), the triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and increased high-density lipoprotein cholesterol (HDLC) in serum. TFBP could also effectively inhibit the generation of reactive oxygen species (ROS) and restrained the level of myeloperoxidase (MPO), and enhance the activity of superoxide dismutase (SOD) to alleviate the injury from oxidative stress in the liver. Additionally, TFBP activated nuclear factor erythroid-2-related factor 2 (Nrf2) pathway to increasing the phosphorylation of AMP-activated protein kinase (AMPK). Meanwhile, protein levels of mTORC signaling pathway were evidently restrained with the treatment of TFBP. CONCLUSION: Our experiments proved that TFBP has the therapeutic effect in NAFLD, and the activation of Nrf2 and AMPK signaling pathways should make sense.

Aescin can alleviate NAFLD through Keap1-Nrf2 by activating antioxidant and autophagy.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a common metabolic liver disease worldwide. It has been proven that aescin (Aes), a bioactive compound derived from the ripe dried fruit of Aesculus chinensis Bunge, has a number of physiologically active properties like anti-inflammatory and anti-edema, however it has not been investigated as a potential solution for NAFLD. PURPOSE: This study's major goal was to determine whether Aes can treat NAFLD and the mechanism underlying its therapeutic benefits. METHODS: We constructed HepG2 cell models in vitro that were affected by oleic and palmitic acids, as well as in vivo models for acute lipid metabolism disorder caused by tyloxapol and chronic NAFLD caused by high-fat diet. RESULTS: We discovered that Aes could promote autophagy, activate the Nrf2 pathway, and ameliorate lipid accumulation and oxidative stress both in vitro and in vivo. Nevertheless, in Autophagy-related proteins 5 (Atg5) and Nrf2 knockout mice, Aes lost its curative impact on NAFLD. Computer simulations show that Aes might interact with Keap1, which might allow Aes to increase Nrf2 transfer into the nucleus and perform its function. Importantly, Aes's stimulation of autophagy in the liver was hampered in Nrf2 knockout mice. This suggested that the impact of Aes in inducing autophagy may be connected to the Nrf2 pathway. CONCLUSION: We first discovered Aes's regulating effects on liver autophagy and oxidative stress in NAFLD. And we found Aes may combine the Keap1 and regulate autophagy in the liver by affecting Nrf2 activation to exert its protective effect.

Pterostilbene alleviated NAFLD via AMPK/mTOR signaling pathways and autophagy by promoting Nrf2.

BACKGROUND: NAFLD is a liver disease that is caused by liver damage or extreme lipid deposition but not alcohol. Nrf2 could mediate resistance to oxidative stress injury. Autophagy can degrade metabolic waste and accumulated toxic endogenous substances. Pterostilbene (PTE) is an active compound extracted from blueberry, and grape, that exhibits many biological effects, such as antiinflammation and antitumor. PURPOSE: This study provides a mechanism of PTE affecting on oxidative stress and autophagy in NAFLD mice. Tyloxapol, oil acid (OA) and palmitic acid (PA) were used to induce lipid accumulation in mice and HepG2 cells. METHODS: Western blotting, CRISPR/Cas 9 and other molecular biological approaches were applied to explore the mechanisms of PTE effected on NAFLD. RESULTS: PTE pretreatment effectively reduced the lipid accumulation in OA and PA induced HepG2 cells and tyloxapol induced mice, and significantly promoted the expression of nNrf2, PPAR-α and HO-1, and AMPK activity, but inhibited the expression of mTORC 1 and SREBP-1c. PTE activated phosphatidylinositide 3-kinase (PI3K) and proteins in the autophagy-related gene (ATG) family, and promoted the transformation of LC3Ⅰ to LC3Ⅱ which indicated the activation of autophagy, however, these effects were abolished after Nrf2 knockout. CONCLUSION: PTE effectively alleviated oxidative stress damage induced by excessive lipid accumulation in hepatocytes, thus promoting the metabolism and decomposition of fatty acids to improve NAFLD.

Phellinus linteus polysaccharides mediates acetaminophen-induced hepatotoxicity via activating AMPK/Nrf2 signaling pathways.

Overdose of acetaminophen (APAP) is currently one of the main causes of hepatoxicity and acute liver injury, which is often linked to oxidative stress. Phellinus linteus polysaccharides (Phps) have shown many hepatoprotective effects, however, the mechanism of Phps on APAP-induced acute liver injury has not been further elucidated. The aim of this study is to investigate the underlying mechanism of Phps to acute liver injury. The expression of AMPK/Nrf2 and autophagy were detected using western blot. The results indicated that Phps treatment effectively alleviated APAP-induced acute liver injury by reducing alanine transaminase (ALT) and aspartate aminotransferase (AST) levels in serum. Phps significantly attenuated myeloperoxidase (MPO) activity and glutathione (GSH) depletion. Meanwhile, Phps remarkably alleviated histopathological changes. Further research found that Phps promoted AMPK pathway and up-regulated nuclear factor erythroid-2-related factor (Nrf2) transported into nucleus, and elevated heme oxygenase 1(HO-1), glutamate-cysteine ligase catalytic (GCLC), glutamate cysteine ligase modifier (GCLM) and quinone oxidoreductase (NQO1). Additionally, Phps apparently facilitated the expression of autophagy proteins (ATG3, ATG5, ATG7, and ATG12). However, the protection of pathologic changes was nearly absent in Nrf2-/- mice. Phps have potential in preventing oxidative stress in APAP-induced acute liver injury.

Lipopolysaccharide and tyloxapol accelerate the development of atherosclerosis in mice.

The occurrence of atherosclerosis is closely related to inflammation and lipid metabolism disorder. It has been found that lipopolysaccharide (LPS) could induce inflammation, and tyloxapol (Ty) could induce hyperlipidemia. However, the effects of LPS and Ty on the development and mechanism of atherosclerosis have not been investigated thoroughly. To answer this question, we used assay kits to detect total cholesterol (TC), triglyceride (TG), and low-density lipoprotein (LDL) content to evaluate dyslipidemia. We used hematoxylin and eosin staining to evaluate the pathological structure of the aorta and liver, and then used Oil Red O staining to access lipid accumulation in the aortic wall. Subsequently, we used the alanine transaminase (ALT) kit to examine the liver injury. Finally, we used the Western blot experiment to measure proteins that regulate lipid metabolism. We found that the LPS + Ty group could increase the levels of TC, TG, and LDL in the serum and promote lipid accumulation in the aortic wall in mice. Moreover, our study showed that the LPS + Ty group induced pathological changes in hepatocytes and increased ALT content in mice. Significantly, we found that the LPS + Ty group could activate acetyl-CoA carboxylase, sterol regulatory element-binding protein-1c, and inhibit peroxisome proliferator-activated receptors α in mice. Therefore, we suppose that LPS and Ty aggravated the development of atherosclerosis by promoting hyperlipidemia and the disorder of lipid metabolism in mice. These findings are significant for the study of the pathogenesis of atherosclerosis and the selection of animal models.

Erythritol Improves Nonalcoholic Fatty Liver Disease by Activating Nrf2 Antioxidant Capacity.

Nonalcoholic fatty liver disease (NAFLD) is a kind of serious fat disorder that has become a critical problem to human society. Therefore, finding drugs that are safe and effective has become more and more important. Erythritol (Ery) is a polyol sweetener with a variety of biological functions. However, whether Ery has a relieving effect on NAFLD has not been reported yet. Therefore, we induced HepG2 cells with oleic acid and palmitic acid as our in vitro model. Moreover, we choose wild-type mice with tyloxapol and high-fat diet and nuclear factor E2-related factor 2 (Nrf2) knockout mice with high-fat diet as our in vivo model. We found that Ery could reverse the lipid accumulation, oxidative stress, and endoplasmic reticulum stress caused by the NAFLD model. The mechanism studies showed that Ery promoted the translocation of Nrf2 from cytoplasm to nucleus, and the molecular simulation docking results of Ery and Nrf2 showed that there was a hydrogen bond between them. Moreover, Ery could promote the production of HO-1 and NQO1 antioxidant proteins and inhibit the expression of endoplasmic reticulum stress proteins GPR78, p-PERK, and CHOP. On the contrast, when Nrf2 was knocked out in mice, Ery lost its protective effect on NAFLD. In conclusion, we found that the potential mechanism of Ery's protective effect is that it plays an antioxidant role by activating the Nrf2 signaling pathway, thereby inhibiting endoplasmic reticulum stress and lipid accumulation in NAFLD.

Geniposide alleviates non-alcohol fatty liver disease via regulating Nrf2/AMPK/mTOR signalling pathways.

Non-alcohol fatty liver disease (NAFLD) is a common disease which causes serious liver damage. Geniposide (GEN), a kind of iridoid glycoside extracted from Gardenia jasminoides fruit, has many biological effects, such as resistance to cell damage and anti-neurodegenerative disorder. Lipid accumulation was obvious in tyloxapol-induced liver and oil acid (OA) with palmitic acid (PA)-induced HepG2 cells compared with the control groups while GEN improved the increasing conditions. GEN significantly lessened the total cholesterol (TC), the triglyceride (TG), low-density lipoprotein (LDL), very low-density lipoprotein (VLDL), myeloperoxidase (MPO), reactive oxygen species (ROS) and increased high-density lipoprotein (HDL), superoxide dismutase (SOD) to response the oxidative stress via activating nuclear factor erythroid-2-related factor 2 (Nrf2), haeme oxygenase (HO)-1 and peroxisome proliferator-activated receptor (PPAR)α which may influence the phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathway in mice and cells. Additionally, GEN evidently decreased the contents of sterol regulatory element-binding proteins (SREBP)-1c, phosphorylation (P)-mechanistic target of rapamycin complex (mTORC), P-S6K, P-S6 and high mobility group protein (HMGB) 1 via inhibiting the expression of phosphoinositide 3-kinase (PI3K), and these were totally abrogated in Nrf2-/- mice. Our study firstly proved the protective effect of GEN on lipid accumulation via enhancing the ability of antioxidative stress and anti-inflammation which were mostly depend on up-regulating the protein expression of Nrf2/HO-1 and AMPK signalling pathways, thereby suppressed the phosphorylation of mTORC and its related protein.

Chicoric acid ameliorate inflammation and oxidative stress in Lipopolysaccharide and d-galactosamine induced acute liver injury.

Chicoric acid is polyphenol of natural plant and has a variety of bioactivity. Caused by various kinds of stimulating factors, acute liver injury has high fatality rate. The effect of chicoric acid in acute liver injury induced by Lipopolysaccharide (LPS) and d-galactosamine (d-GalN) was investigated in this study. The results showed that CA decreased the aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum and reduced the mortality induced by LPS/d-GalN. CA can restrain mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) to alleviate inflammation. Meanwhile, the results indicated CA can active nuclear factor-erythroid 2-related factor 2 (Nrf2) pathway with increasing the level of AMP-activated protein kinase (AMPK). And with the treatment of CA, protein levels of autophagy genes were obvious improved. The results of experiments indicate that CA has protective effect in liver injury, and the activation of AMPK and autophagy may make sense.

Inhibition of histone deacetylase reduces lipopolysaccharide-induced-inflammation in primary mammary epithelial cells by regulating ROS-NF-кB signaling pathways.

Histone deacetylase 6 (HDAC6) is the sole member of the HDAC family, that is predominantly located in the cytoplasm and has substrate specificity for nonhistone proteins, such as α-Tubulin. Although an increasing number of studies have shown that HDAC6 is involved in inflammatory diseases, but little is known about the participation of HDAC6 in the transcriptional regulation of inflammatory cytokines. Here, we examined the effects of Tubastatin (Tub), a highly selective HDAC6 inhibitor, on lipopolysaccharide (LPS)-stimulated primary bovine mammary epithelial cells (bMECs). The specific inhibition of HDAC6 using Tub significantly decreased the release of pro-inflammatory cytokines, such as TNF-α and IL-1ß, which was associated with increased α-Tubulin acetylation. HDAC6 overexpression significantly induced reactive oxygen species (ROS) generation via upregulation of NADPH oxidase activity. Administration of Tub dose-dependently inhibited ROS production and NADPH oxidase activity. In addition, inhibition of HDAC6 led to suppression of the NF-κB signaling pathway. Thus, we report herein that HDAC6 is involved in ROS-NF-κB signaling pathway related to pro-inflammatory cytokine expression and that selective HDAC6 inhibition by Tub is a potent approach for preventing LPS-mediated inflammation.

Costunolide protects lipopolysaccharide/d-galactosamine-induced acute liver injury in mice by inhibiting NF-κB signaling pathway.

BACKGROUND: Costunolide, a well-known sesquiterpene lactone, has been reported to have anti-inflammatory and anti-oxidative effects. METHODS: In this study, we aim to investigate the protective effects and mechanism of costunolide on lipopolysaccharide/d-galactosamine (LPS/D-Gal)-induced acute liver injury. Acute liver injury animal model was induced by intraperitoneal injection with D-Gal and LPS. Costunolide (10, 20, and 30 mg/kg) was injected intraperitoneally 1 h before or after LPS/D-Gal treatment. RESULTS: The results showed that costunolide significantly attenuated liver pathologic changes, as well as alanine aminotransferase and aspartate aminotransferase levels in serum. Meanwhile, costunolide inhibited the expressions of interleukin (IL-1ß) and tumor necrosis factor (TNF-α) in liver tissues in a dose-dependent manner. Furthermore, costunolide dose dependently inhibited LPS/D-Gal-induced NF-κB activation. CONCLUSIONS: In conclusion, this study suggested that costunolide could attenuate LPS/D-Gal-induced liver injury and might be a potential therapeutic reagent for liver injury.