Project description:BACKGROUND: Unexpected cholestasis substantially contributes to drug failure in clinical trials. Current models used for safety assessment in drug development do not accurately predict cholestasis in humans. Therefore, it is of relevance to develop new screening models that allow identifying drugs with cholestatic properties. METHODS: We employed mouse precision cut liver slices (PCLS), which were incubated 24 h with two model cholestatic compounds: cyclosporin A (CsA) and chlorpromazine (CPZ). Subsequently, transcriptome analysis using DNA microarrays and q-PCR were performed to identify relevant biological processes and biomarkers. Additionally, histology was carried out and levels of triglycerides (TG) and bile acids (BA) were measured. To verify the ex vivo mouse data, these were compared with publically available human data relevant for cholestasis. RESULTS: Whole genome gene expression analysis showed that CsA up-regulated pathways related to NF-?B, ER stress and inflammation. Both CsA and CPZ down-regulated processes related to extracellular matrix (ECM) remodelling, BA homeostasis, Fxr signalling, and energy metabolism. The differential expression of a number of characteristic genes (e.g. Abcg5, Abcg8, Klf15, and Baat) could be confirmed by q-PCR. Histology revealed that CsA but not CPZ induced "ballooning" of hepatocytes. No effects on TG and BA levels were observed after incubation of PCLS with CsA and CPZ. A substantial number of processes altered in CsA- and CPZ-treated mouse PCLS ex vivo was also found to be affected in liver biopsies of cholestatic patients. CONCLUSION: The present study demonstrated that mouse PCLS can be used as a tool to identify mechanisms of action of cholestatic model compounds. The induction of general stress responses and down-regulated Fxr signalling could play a role in the development of drug induced cholestasis. Importantly, comparative data analysis showed that the ex vivo mouse findings are also relevant for human pathology. Moreover, this work provides a set of genes that are potentially useful to assess drugs for cholestatic properties.

Project description:Although drug induced steatosis represents a mild type of hepatotoxicity, it can progress into more severe non-alcoholic steatohepatitis. Current models used for safety assessment in drug development and chemical risk assessment do not accurately predict steatosis in humans. Therefore, new models need to be developed to screen compounds for steatogenic properties. We have studied the usefulness of mouse precision-cut liver slices (PCLS) as an alternative to animal testing to gain more insight into the mechanisms involved in the steatogenesis. To this end, PCLS were incubated 24h with the model steatogenic compounds, amiodarone (AMI), valproic acid (VA), and tetracycline (TET). Transcriptome analysis using DNA microarrays was used to identify genes and processes affected by these compounds. AMI and VA upregulated lipid metabolism, whereas processes associated with extracellular matrix remodelling and inflammation were downregulated. TET downregulated mitochondrial functions, lipid metabolism, and fibrosis. From the transcriptomics data it was hypothesized that all 3 compounds affect peroxisome proliferator activated-receptor (PPAR) signalling. Application of PPAR reporter assays classified AMI and VA as PPARγ and triple PPARα/ (β/δ)/γ agonist, respectively, whereas TET had no effect on any of the PPARs. Some of the differentially expressed genes were considered as potential candidate biomarkers to identify PPAR agonists (i.e. AMI and VA) or compounds impairing mitochondrial functions (i.e. TET). Finally, comparison of our findings with publicly available transcriptomics data showed that a number of processes altered in the mouse PCLS was also affected in mouse livers and human primary hepatocytes exposed to known PPAR agonists. Thus mouse PCLS are a valuable model to identify mechanisms of action of compounds altering lipid metabolism. Two sets of candidate biomarkers could be used to screen compounds interfering with lipid metabolism by different mechanisms. Cholestatic compounds exposures Mouse precision cut liver slices (PCLS) were prepared from livers obtained from 5 different C57BL/6 male mice (24 weeks old). PCLS were cultured for 24 hours at 80% of oxygen; 5% CO2 and the remaining gas volume was filled up to 95% with N2. PCLS were exposed to model steatogenic, cholestatic, and necrotic compounds selected based on published reports. As steatogenic model compounds amiodarone (AMI), valproic acid (VA), and tetracycline (TET) were selected. As model cholestatic compounds cyclosporin A (CsA), chlorpromazine (CPZ), and ethinyl estradiol (EE) were applied. As necrotic compounds acetaminophen (APAP), isoniazid (ISND), and paraquat (PQ) were applied. To select a non-toxic dose eventually to be used for exposure experiments and subsequent gene expression profiling experiments, the following concentrations ranges were tested: AMI 0-100 μM, VA 0-500 μM, TET 0-100 μM , CsA 0-100 μM, CPZ 0-80 μM, EE 0-100 μM, PQ 0-10 μM, APAP 0-3000 μM and ISND 0-1000 μM. CsA, CPZ, AMI, PQ, EE were dissolved in DMSO, VA and TET were dissolved in ethanol (EtOH), and ISND was dissolved in PBS. The compounds were added to the culture medium at a final concentration of 0.1% vol/vol in an appropriate solvent (DMSO, EtOH, or PBS). Slices incubated with the solvents at 0.1% vol/vol served as controls. The viability of the slices was assessed by measuring the ATP content normalized on protein. Dose selection for the three steatogenic, cholestatic, and necrotic exposures were performed in 5 independent experiments with slices obtained from 5 mice. Concentrations that did not cause a decrease of the ATP level normalized on protein, compared to controls, were selected. For transcriptome analysis, PCLS were cultured at the same conditions as described above. The selected concentrations for steatogenic, cholestatic, and necrotic drugs were tested again in liver slices obtained from 5 different mice to re-confirm that the selected concentrations for the exposure experiments were not toxic. The concentrations used in the exposure experiments were for the steatogenic compounds: 50 μM for AMI, 200 μM for VA, and 40 μM for TET. For the cholestatic exposures 40 μM CsA, 20 μM CPZ, and 10 μM EE. For the necrotic compounds: 1000 μM APAP, 1000 μM ISND, and 5 μM PQ. Thereafter, RNA was extracted from three slices per each condition and after processing, the samples were hybridized on the HT Mouse Genome 430 PM array plate(s) using the Affymetrix GeneTitan system (CA, USA).

Project description:Although drug induced steatosis represents a mild type of hepatotoxicity, it can progress into more severe non-alcoholic steatohepatitis. Current models used for safety assessment in drug development and chemical risk assessment do not accurately predict steatosis in humans. Therefore, new models need to be developed to screen compounds for steatogenic properties. We have studied the usefulness of mouse precision-cut liver slices (PCLS) as an alternative to animal testing to gain more insight into the mechanisms involved in the steatogenesis. To this end, PCLS were incubated 24h with the model steatogenic compounds, amiodarone (AMI), valproic acid (VA), and tetracycline (TET). Transcriptome analysis using DNA microarrays was used to identify genes and processes affected by these compounds. AMI and VA upregulated lipid metabolism, whereas processes associated with extracellular matrix remodelling and inflammation were downregulated. TET downregulated mitochondrial functions, lipid metabolism, and fibrosis. From the transcriptomics data it was hypothesized that all 3 compounds affect peroxisome proliferator activated-receptor (PPAR) signalling. Application of PPAR reporter assays classified AMI and VA as PPARγ and triple PPARα/ (β/δ)/γ agonist, respectively, whereas TET had no effect on any of the PPARs. Some of the differentially expressed genes were considered as potential candidate biomarkers to identify PPAR agonists (i.e. AMI and VA) or compounds impairing mitochondrial functions (i.e. TET). Finally, comparison of our findings with publicly available transcriptomics data showed that a number of processes altered in the mouse PCLS was also affected in mouse livers and human primary hepatocytes exposed to known PPAR agonists. Thus mouse PCLS are a valuable model to identify mechanisms of action of compounds altering lipid metabolism. Two sets of candidate biomarkers could be used to screen compounds interfering with lipid metabolism by different mechanisms. Cholestatic compounds exposures

Project description:Background and aimsPrimary sclerosing cholangitis (PSC) is a chronic liver disease characterized by progressive biliary inflammation and bile duct injury. Berberine (BBR) is a bioactive isoquinoline alkaloid found in various herbs and has multiple beneficial effects on metabolic and inflammatory diseases, including liver diseases. This study aimed to examine the therapeutic effect of BBR on cholestatic liver injury in a PSC mouse model (Mdr2-/- mice) and elucidate the underlying mechanisms.MethodsMdr2-/-mice (12-14 weeks old, both sexes) received either BBR (50 mg/kg) or control solution daily for eight weeks via oral gavage. Histological and serum biochemical analyses were used to assess fibrotic liver injury severity. Total RNAseq and pathway analyses were used to identify the potential signaling pathways modulated by BBR in the liver. The expression levels of key genes involved in regulating hepatic fibrosis, bile duct proliferation, inflammation, and bile acid metabolism were validated by qRT-PCR or Western blot analysis. The bile acid composition and levels in the serum, liver, small intestine, and feces and tissue distribution of BBR were measured by LC-MS/MS. Intestinal inflammation and injury were assessed by gene expression profiling and histological analysis. The impact on the gut microbiome was assessed using 16S rRNA gene sequencing.ResultsBBR treatment significantly ameliorated cholestatic liver injury, evidenced by decreased serum levels of AST, ALT, and ALP, and reduced bile duct proliferation and hepatic fibrosis, as shown by H&E, Picro-Sirius Red, and CK19 IHC staining. RNAseq and qRT-PCR analyses indicated a substantial inhibition of fibrotic and inflammatory gene expression. BBR also mitigated ER stress by downregulating Chop, Atf4 and Xbp-1 expression. In addition, BBR modulated bile acid metabolism by altering key gene expressions in the liver and small intestine, resulting in restored bile acid homeostasis characterized by reduced total bile acids in serum, liver, and small intestine and increased fecal excretion. Furthermore, BBR significantly improved intestinal barrier function and reduced bacterial translocation by modulating the gut microbiota.ConclusionBBR effectively attenuates cholestatic liver injury, suggesting its potential as a therapeutic agent for PSC and other cholestatic liver diseases.

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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Cyclosporin A as a model cholestatic compound - transcriptomic study in mouse liver slices

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