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SRT1720 Alleviates ANIT-Induced Cholestasis in a Mouse Model.

ABSTRACT: Intrahepatic cholestasis is a kind of clinical syndrome along with hepatotoxicity which caused by intrahepatic and systemic accumulations of bile acid. There are several crucial generating factors of the pathogenesis of cholestasis, such as inflammation, dysregulation of bile acid transporters and oxidative stress. SIRT1 is regarded as a class III histone deacetylase (HDAC). According to a set of researches, SIRT1 is one of the most important factors which can regulate the hepatic bile acid metabolism. SRT1720 is a kind of activator of SIRT1 which is 1000 times more potent than resveratrol, and this paper is aimed to study its protective influence on hepatotoxicity and cholestasis induced by alpha-naphthylisothiocyanate (ANIT) in mice. The findings revealed that SRT1720 treatment increased FXR and Nrf2 gene expressions to shield against hepatotoxicity and cholestasis induced by ANIT. The mRNA levels of hepatic bile acid transporters were also altered by SRT1720. Furthermore, SRT1720 enhanced the antioxidative system by increasing Nrf2, SOD, GCLc, GCLm, Nqo1, and HO-1 gene expressions. In conclusion, a protective influence could be provided by SRT1720 to cure ANIT-induced hepatotoxicity and cholestasis, which was partly through FXR and Nrf2 activations. These results indicated that SIRT1 could be regarded as a therapeutic target to cure the cholestasis.

SUBMITTER: Yu L

PROVIDER: S-EPMC5425580 | biostudies-literature | 2017

REPOSITORIES: biostudies-literature

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SRT1720 Alleviates ANIT-Induced Cholestasis in a Mouse Model.

Yu Linxi L Liu Xiaoxin X Yuan Zihang Z Li Xiaojiaoyang X Yang Hang H Yuan Ziqiao Z Sun Lixin L Zhang Luyong L Jiang Zhengzhou Z

Frontiers in pharmacology 20170511

Intrahepatic cholestasis is a kind of clinical syndrome along with hepatotoxicity which caused by intrahepatic and systemic accumulations of bile acid. There are several crucial generating factors of the pathogenesis of cholestasis, such as inflammation, dysregulation of bile acid transporters and oxidative stress. SIRT1 is regarded as a class III histone deacetylase (HDAC). According to a set of researches, SIRT1 is one of the most important factors which can regulate the hepatic bile acid meta ...[more]

PMID: 28553227

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Project description:Alpha-naphthylisothiocyanate (ANIT) causes intrahepatic cholestasis by injuring biliary epithelial cells. Adaptive regulation of hepatobiliary transporter expression has been proposed to reduce liver injury during cholestasis. Recently, the oxidative stress transcription factor Nrf2 (nf-e2-related factor 2) was shown to regulate expression of hepatobiliary transporters. The purpose of this study was to determine whether ANIT-induced hepatotoxicity and regulation of hepatobiliary transporters are altered in the absence of Nrf2. For this purpose, wild-type and Nrf2-null mice were administered ANIT (75 mg/kg po). Surprisingly, ANIT-induced hepatotoxicity was similar in both genotypes at 48 h. Accumulation of bile acids in serum and liver was lower in Nrf2-null mice compared with wild-types treated with ANIT. Transporter mRNA profiles differed between wild-type and Nrf2-null mice after ANIT. Bsep (bile salt export pump), Mdr2 (multidrug resistance gene), and Mrp3 (multidrug resistance-associated protein) efflux transporters were increased by ANIT in wild-type, but not in Nrf2-null mice. In contrast, mRNA expression of two hepatic uptake transporters, Ntcp (sodium-taurocholate cotransporting polypeptide) and Oatp1b2 (organic anion transporting peptide), were decreased in both genotypes after ANIT, with larger declines in Nrf2-null mice. mRNA expression of the transcriptional repressor of Ntcp, small heterodimeric partner (SHP), was increased in Nrf2-null mice after ANIT. Furthermore, hepatocyte nuclear factor 1alpha (HNF1alpha), which regulates Oatp1b2, was downregulated in ANIT-treated Nrf2-null mice. Preferential upregulation of SHP and downregulation of HNF1alpha and uptake transporters likely explains why Nrf2-null mice exhibited similar injury to wild-types after ANIT. A subsequent study revealed that treatment of mice with the Nrf2 activator oltipraz protects against ANIT-induced histological injury. Despite compensatory changes in Nrf2-null mice to limit ANIT toxicity, pharmacological activation of Nrf2 may represent a therapeutic option for intrahepatic cholestasis.

Project description:BackgroundPaeonia lactiflora Pall. (PLP), a traditional Chinese herbal medicine, has been used for hepatic disease treatment over thousands of years. In our previous study, PLP was shown to demonstrate therapeutic effect on hepatitis with severe cholestasis. The aim of this study was to evaluate the antioxidative effect of PLP on alpha-naphthylisothiocyanate (ANIT)-induced cholestasis by activating NF-E2-related factor 2 (Nrf2) via phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway.Materials and methodsLiquid chromatography-mass spectrometry (LC-MS) was performed to identify the main compounds present in PLP. The mechanism of action of PLP and its therapeutic effect on cholestasis, induced by ANIT, were further investigated. Serum indices such as total bilirubin (TBIL), direct bilirubin (DBIL), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), γ-glutamyl transpeptidase (γ-GT), and total bile acid (TBA) were measured, and histopathology of liver was also performed to determine the efficacy of treatment with PLP. Moreover, in order to illustrate the underlying signaling pathway, liver glutathione (GSH) content and mRNA or protein levels of glutamate-cysteine ligase catalytic subunit (GCLc), glutamate-cysteine ligase modulatory subunit (GCLm), Akt, heme oxygenase-1 (HO-1), NAD(P)H/quinone oxidoreductase 1 (Nqo1), and Nrf2 were further analyzed. In addition, validation of PLP putative target network was also performed in silico.ResultsFour major compounds including paeoniflorin, albiflorin, oxypaeoniflorin, and benzoylpaeoniflorin were identified by LC-MS analysis in water extract of PLP. Moreover, PLP could remarkably downregulate serum levels of TBIL, DBIL, AST, ALT, ALP, γ-GT, and TBA, and alleviate the histological damage of liver tissue caused by ANIT. It enhanced antioxidative system by activating PI3K/Akt/Nrf2 pathway through increasing Akt, Nrf2, HO-1, Nqo1, GCLc, and GCLm expression. The putative targets network validation also confirmed the important role of PLP in activating Akt expression.ConclusionThe potential mechanism of PLP in alleviating ANIT-induced cholestasis could to be related to the induction of GSH synthesis by activating Nrf2 through PI3K/Akt-dependent pathway. This indicates that PLP might be a potential therapeutic agent for cholestasis.

Project description:Sirtuin1 (Sirt1; mammalian homolog of Saccharomyces cerevisiae enzyme Sir2) is a transcriptional and transactivational regulator of murine farnesoid X receptor (Fxr), which is the primary bile acid (BA) sensor, and critical regulator of BA metabolism in physiological and pathophysiological conditions. Previous studies have suggested compromised Sirt1 expression in rodent models of cholestatic liver injury. We hypothesized that Sirt1 could be potentially targeted to alleviate cholestatic liver injury. In cultured primary human hepatocytes, SIRT1 messenger RNA was down-regulated after GCA treatment, potentially through induction of microRNA (miR)-34a, whereas tauroursodeoxycholic acid induced SIRT1 expression without affecting miR-34a expression. Sirt1 expression was also significantly down-regulated in three mouse models of liver injury (bile duct ligation, 1% cholic acid [CA] fed, and the Mdr2-/- mouse). Mice fed CA diet also demonstrated hepatic FXR hyperacetylation and induction of the Janus kinase/p53 pathway. Mice fed a CA diet and concurrently administered the Sirt1 activator, SRT1720 (50 mg/kg/day, orally), demonstrated 40% and 45% decrease in plasma alanine aminotransferase and BA levels, respectively. SRT1720 increased hepatic BA hydrophilicity by increasing tri- and tetrahydroxylated and decreasing the dihydroxylated BA fraction. SRT1720 administration also inhibited hepatic BA synthesis, potentially through ileal fibroblast growth factor 15- and Fxr-mediated inhibition of cytochrome p450 (Cyp) 7a1 and Cyp27a1, along with increased hepatic BA hydroxylation in association with Cyp2b10 induction. SRT1720 administration significantly induced renal multidrug resistance-associated protein 2 and 4, peroxisome proliferator-activated receptor gamma coactivator 1-?, and constitutive androstance receptor expression along with ?2-fold increase in urinary BA concentrations.SRT1720 administration alleviates cholestatic liver injury in mice by increasing hydrophilicity of hepatic BA composition and decreasing plasma BA concentration through increased BA excretion into urine. Thus, use of small-molecule activators of Sirt1 presents a novel therapeutic target for cholestatic liver injury. (Hepatology 2016;64:2151-2164).

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SRT1720 Alleviates ANIT-Induced Cholestasis in a Mouse Model.

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SRT1720 Alleviates ANIT-Induced Cholestasis in a Mouse Model.

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