Gene expression profiles of murine fatty liver induced by the administration of methotrexate

Methotrexate (MTX) is used to treat a variety of chronic inflammatory and neoplastic diseases. However, it can induce hepatotoxicity such as microvesicular steatosis and necrosis. To explore the mechanisms of MTX-induced hepatic steatosis, we used microarray analysis to profile the gene expression patterns of mouse liver after MTX treatment. MTX was administered orally as a single dose of 10mg/kg (low dose) or 100 mg/kg (high dose) to ICR mice, and the livers were obtained 6 h, 24 h, and 72 h after treatment. Serum alanine aminotransferase, aspartate aminotransferase and triacylglycerol levels were not significantly altered in the experimental animals. Signs of steatosis were observed at 24 h after administration of high dose of MTX. From microarray data analysis, 908 genes were selected as MTX-responsive genes (P<0.05, two-way ANOVA; cutoff > or =1.5-fold). Database for Annotation, Visualization and Integrated Discovery (DAVID) analysis revealed that the predominant biological processes associated with these genes are response to unfolded proteins, phosphate metabolism, and cellular lipid metabolism. Functional categorization of these genes identified 28 genes involved in lipid metabolism that was interconnected with the biological pathways of biosynthesis, catabolism, and transport of lipids and fatty acids. Taken together, these data provide a better understanding of the molecular mechanisms of MTX-induced steatogenic hepatotoxicity, and useful information for predicting hepatotoxicity through pattern recognition.     

Subchronic effects of valproic acid on gene expression profiles for lipid metabolism in mouse liver

Valproic acid (VPA) is used clinically to treat epilepsy, however it induces hepatotoxicity such as microvesicular steatosis. Acute hepatotoxicity of VPA has been well documented by biochemical studies and microarray analysis, but little is known about the chronic effects of VPA in the liver. In the present investigation, we profiled gene expression patterns in the mouse liver after subchronic treatment with VPA. VPA was administered orally at a dose of 100 mg/kg/day or 500 mg/kg/day to ICR mice, and the livers were obtained after 1, 2, or 4 weeks. The activities of serum liver enzymes did not change, whereas triglyceride concentration increased significantly. Microarray analysis revealed that 1325 genes of a set of 32,996 individual genes were VPA responsive when examined by two-way ANOVA (P<0.05) and fold change (>1.5). Consistent with our previous results obtained using an acute VPA exposure model (Lee et al., Toxicol Appl Pharmacol. 220:45-59, 2007), the most significantly over-represented biological terms for these genes included lipid, fatty acid, and steroid metabolism. Biological pathway analysis suggests that the genes responsible for increased biosynthesis of cholesterol and triglyceride, and for decreased fatty acid beta-oxidation contribute to the abnormalities in lipid metabolism induced by subchronic VPA treatment. A comparison of the VPA-responsive genes in the acute and subchronic models extracted 15 commonly altered genes, such as Cyp4a14 and Adpn, which may have predictive power to distinguish the mode of action of hepatotoxicants. Our data provide a better understanding of the molecular mechanisms of VPA-induced hepatotoxicity and useful information to predict steatogenic hepatotoxicity.     

Hepatic gene expression profiling and lipid homeostasis in mice exposed to steatogenic drug, tetracycline.

Tetracycline is one of a group of drugs known to induce microvesicular steatosis. In the present study, we investigated the effects of tetracycline on gene expression in mouse liver, using Applied Biosystems Mouse Genome Survey Microarrays. A single oral dose of 0.1 or 1 g/kg tetracycline was administered to male ICR mice, and liver samples were obtained after 6, 24, or 72 h. Histopathological evaluation showed microvesicular steatosis in the high-dose group at 24 h. In total, 96 genes were identified as tetracycline responsive. Their level of expression differed significantly from controls (two-way analysis of variance; p < 0.05), after adjustment by the Benjamini-Hochberg multiple testing correction, and displayed a twofold or greater induction or repression. The largest groups of gene products affected by tetracycline exposure were those involved in signal transduction, nucleic acid metabolism, developmental processes, and protein metabolism. The expression of genes known to be involved in lipid metabolism was examined, using two-sample Student's t-test for each treatment group versus a corresponding control group. The overall net effects on expression of lipid metabolism genes indicated an increase in cholesterol and triglyceride biosynthesis and a decrease in beta-oxidation of fatty acids. Our data support a proposed mechanism for tetracycline-induced steatogenic hepatotoxicity that involves these processes. Moreover, we demonstrated global changes in hepatic gene expression following tetracycline exposure; many of these genes have the potential to be used as biomarkers of exposure to steatogenic hepatotoxic agents.     

Combined effects of a high-fat diet and chronic valproic acid treatment on hepatic steatosis and hepatotoxicity in rats

Aim： To investigate the potential interactive effects of a high-fat diet （HFD） and valproic acid （VPA） on hepatic steatosis and hepatotoxicity in rats. Methods： Male SD rats were orally administered VPA （100 or 500 mg.kgl.d1） combined with HFD or a standard diet for 8 weeks. Blood and liver samples were analyzed to determine lipid levels and hepatic function biomarkers using commercial kit assays. Low- molecular-weight compounds in serum, urine and bile samples were analyzed using a metabonomic approach based on GC/TOF-MS. Results： HFD alone induced extensive hepatocyte steatosis and edema in rats, while VPA alone did not cause significant liver lesions. VPA significantly aggravated HFD-induced accumulation of liver lipids, and caused additional spotty or piecemeal necrosis, accompanied by moderate infiltration of inflammatory cells in the liver. Metabonomic analysis of serum, urine and bile samples revealed that HFD significantly increased the levells of amino acids, free fatty acids （FFAs） and 3-hydroxy-butanoic acid, whereas VPA markedly decreased the levels of amino acids, FFAs and the intermediate products of the tricarboxylic acid cycle （TCA） compared with the control group. HFD aggravated VPA-induced inhibition on lipid and amino acid metabolism. Conclusion： HFD magnifies VPA-induced impairment of mitochondria113-oxidation of FFAs and TCA, thereby increases hepatic steatosis and hepatotoxicity. The results suggest the patients receiving VPA treatment should be advised to avoid eating HFD.     

Analysis of hepatic gene expression during fatty liver change due to chronic ethanol administration in mice

Chronic consumption of ethanol can cause cumulative liver damage that can ultimately lead to cirrhosis. To explore the mechanisms of alcoholic steatosis, we investigated the global intrahepatic gene expression profiles of livers from mice administered alcohol. Ethanol was administered by feeding the standard Lieber-DeCarli diet, of which 36% (high dose) and 3.6% (low dose) of the total calories were supplied from ethanol for 1, 2, or 4 weeks. Histopathological evaluation of the liver samples revealed fatty changes and punctate necrosis in the high-dose group and ballooning degeneration in the low-dose group. In total, 292 genes were identified as ethanol responsive, and several of these differed significantly in expression compared to those of control mice (two-way ANOVA; p < 0.05). Specifically, the expression levels of genes involved in hepatic lipid transport and metabolism were examined. An overall net increase in gene expression was observed for genes involved in (i) glucose transport and glycolysis, (ii) fatty acid influx and de novo synthesis, (iii) fatty acid esterification to triglycerides, and (iv) cholesterol transport, de novo cholesterol synthesis, and bile acid synthesis. Collectively, these data provide useful information concerning the global gene expression changes that occur due to alcohol intake and provide important insights into the comprehensive mechanisms of chronic alcoholic steatosis.     

Valproate-Induced Liver Injury: Modulation by the Omega-3 Fatty Acid DHA Proposes a Novel Anticonvulsant Regimen

Background

The polyunsaturated, ω-3 fatty acid, docosahexaenoic acid (DHA), claims diverse cytoprotective potentials, although via largely undefined triggers. Thus, we currently first tested the ability of DHA to ameliorate valproate (VPA)-evoked hepatotoxicity, to modulate its anticonvulsant effects, then sought the cellular and molecular basis of such actions. Lastly, we also verified whether DHA may kinetically alter plasma levels/clearance rate of VPA.

Methods and Results

VPA (500 mg/kg orally for 14 days in rats) evoked prominent hepatotoxicity that appeared as a marked rise (2- to 4-fold) in serum hepatic enzymes (γ-glutamyl transferase [γ-GT], alanine aminotransferase [ALT], and alkaline phosphatase [ALP]), increased hepatic lipid peroxide (LPO) and tumor necrosis factor-alpha (TNFα) levels, as well as myeloperoxidase (MPO) activity (3- to 5-fold), lowering of serum albumin (40 %), and depletion of liver reduced-glutathione (GSH, 35 %). Likewise, histopathologic examination revealed hepatocellular degeneration, replacement by inflammatory cells, focal pericentral necrosis, and micro/macrovesicular steatosis. Concurrent treatment with DHA (250 mg/kg) markedly blunted the elevated levels of liver enzymes, lipid peroxides, TNFα, and MPO activity, while raising serum albumin and hepatic GSH levels. DHA also alleviated most of the cytologic insults linked to VPA. Besides, in a pentylenetetrazole (PTZ) mouse convulsion model, DHA (250 mg/kg) markedly increased the latency in convulsion evoked by VPA, beyond their individual responses. Lastly, pharmacokinetic studies revealed that joint DHA administration did not alter serum VPA concentrations.

Conclusions

DHA substantially ameliorated liver injury induced by VPA, while also markedly boosted its pharmacologic effects. DHA manipulated definite cellular machinery to curb liver oxidative stress and inflammation, without affecting VPA plasma levels. Collectively, these protective and synergy profiles for DHA propose a superior VPA-drug combination regimen.     

Valproic acid perturbs hematopoietic homeostasis by inhibition of erythroid differentiation and activation of the myelo-monocytic pathway

As a histone deacetylase inhibitor, valproic acid (VPA) is a candidate for anticancer therapy. Besides, VPA exhibits various mechanisms of action and its effects on the molecular basis of hematopoiesis remain unclear. To study the effects of VPA on the hematopoietic system, we performed microarray analysis using K562 cells treated with 1 mM VPA over a 72 h time course. The association between gene ontology (GO) terms and the lists of differentially expressed genes was tested using the Bioconductor package GOstats. Enrichment analysis for cellular differentiation pathways was performed based on manually curated gene lists. Results from microarray analysis were confirmed by studying cell differentiation features at the molecular and cellular levels using other hematopoietic cell lines as well as hematopoietic stem/progenitor CD34⁺ cells. Microarray analysis revealed 3440 modulated genes in the presence of VPA. Genes involved in the granulo-monocytic differentiation pathway were up-regulated while genes of the erythroid pathway were down-regulated. This was confirmed by analyzing erythrocytic and myeloid membrane markers and lineage-related gene expression in HEL, MEG01, HL60 as well as CD34⁺ cells. Moreover, GATA-1 and its co-factors (FOG1, SP1) were down-regulated, while myelopoiesis activator PU.1 was up-regulated, in agreement with an inhibition of erythropoiesis. Our functional profiling and cell phenotyping approach demonstrates that VPA is able to alter hematopoietic homeostasis by modifying the cell population balance in the myeloid compartment. This may lead to a potential failure of erythropoiesis in patients with cancer or chronic inflammatory diseases having a well-described propensity to anemia.     

Temporal and dose-dependent hepatic gene expression patterns in mice provide new insights into TCDD-Mediated hepatotoxicity.

In an effort to further characterize the mechanisms of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-mediated toxicity, comprehensive temporal and dose-response microarray analyses were performed on hepatic tissue from immature ovariectomized C57BL/6 mice treated with TCDD. For temporal analysis, mice were gavaged with 30 microg/kg of TCDD or vehicle and sacrificed after 2, 4, 8, 12, 18, 24, 72, or 168 h. Dose-response mice were gavaged with 0, 0.001, 0.01, 0.1, 1, 10, 100, or 300 microg/kg of TCDD and sacrificed after 24 h. Hepatic gene expression profiles were monitored using custom cDNA microarrays containing 13,362 cDNA clones. Gene expression analysis identified 443 and 315 features which exhibited a significant change at one or more doses or time points, respectively, as determined using an empirical Bayes approach. Functional gene annotation extracted from public databases associated gene expression changes with physiological processes such as oxidative stress and metabolism, differentiation, apoptosis, gluconeogenesis, and fatty acid uptake and metabolism. Complementary histopathology (H&E and Oil Red O stains), clinical chemistry (i.e., alanine aminotransferase [ALT], triglyceride [TG], free fatty acids [FFA], cholesterol) and high-resolution gas chromatography/mass spectrometry assessment of hepatic TCDD levels were also performed in order to phenotypically anchor changes in gene expression to physiological end points. Collectively, the data support a proposed mechanism for TCDD-mediated hepatotoxicity, including fatty liver, which involves mobilization of peripheral fat and inappropriate increases in hepatic uptake of fatty acids.     

红霉素和阿奇霉素诱导斑马鱼肝毒性及作用机制研究

目的 利用模式生物斑马鱼模型探索红霉素和阿奇霉素导致肝毒性及作用机制,并比较红霉素和阿奇霉素诱导肝毒性的差异。方法 选用肝脏转基因斑马鱼Tg(fapb10: dsRed)作为实验动物,将发育正常的3dpf斑马鱼幼鱼暴露于不同浓度的红霉素和阿奇霉素溶液中72h后,统计各组斑马鱼死亡率,计算红霉素和阿奇霉素对斑马鱼的LD50;荧光显微镜下活体观察斑马鱼幼鱼给药后肝脏形态的变化;采用整体油红O染色观察肝脏脂肪含量变化;利用qRT-PCR检测肝脏病理标志基因和凋亡相关基因在转录水平的变化。结果 红霉素和阿奇霉素对斑马鱼的LD50分别为3.82mmol/L和3.10mmol/L;活体观察显示红霉素和阿奇霉素均能导致幼鱼肝脏形态和荧光强度变化;整体油红O染色显示红霉素和阿奇霉素均能导致肝细胞脂肪堆积,并呈剂量依赖性;qRT-PCR结果显示红霉素和阿奇霉素均能影响脂肪肝、肝纤维化和细胞凋亡相关基因的表达。结论 红霉素和阿奇霉素均能诱导斑马鱼肝毒性,作用机制可能与两者诱导肝细胞变性或凋亡有关,但两者影响的相关基因通路可能有所不同。     

The relationship between glucuronide conjugate levels and hepatotoxicity after oral administration of valproic acid

The aim of this study was to investigate the relationship between hepatotoxicity, levels of glucuronide conjugates of valproic acid (VPA), and the toxic metabolites of VPA (4-ene VPA and 2,4-diene VPA). We also examined whether hepatotoxicity could be predicted by the urinary excretion levels of VPA and its toxic metabolites. VPA was administrated orally in rats in amounts ranging from 20 mg/kg to 500 mg/kg. Free and total (free plus glucuronide conjugated) VPA, 4-ene VPA, and 2,4-diene VPA were quantified in urine and liver using gas chromatography-mass spectrometry. Serum levels of aspartate aminotransferase, alanine aminotransferase, and α-glutathione S-transferase (α-GST) were also determined to measure the level of hepatotoxicity. The serum α-GST level increased slightly at the 20 mg/kg dose, and substantially increased at the 100 and 500 mg/kg dose; aspartate aminotransferase and alanine aminotransferase levels did not change with the administration of increasing doses of VPA. The liver concentration of free 4-ene VPA and the urinary excretion of total 4-ene VPA were the only measures that correlated with the increase in the serum α-GST level (p < 0.094 and p < 0.023 respectively). From these results, we conclude that hepatotoxicity of VPA correlates with liver concentration of 4-ene VPA and can be predicted by the urinary excretion of total 4-ene VPA.     

Effect of Rosiglitazone on Liver Structure and Function in Genetically Diabetic Akita Mice

Genetically diabetic Akita mice, kept on a high‐fat and high‐cholesterol diet, and treated with the peroxisome proliferator‐activated receptor‐γ agonist rosiglitazone (10 mg/kg per day during 4 months), displayed rosiglitazone‐induced side effects, similar to those observed in patients, including weight and fat gain and early signs of hypertrophic cardiomyopathy. As several cases of hepatotoxicity were reported in patients receiving rosiglitazone treatment, this study evaluated whether rosiglitazone also induced hepatotoxicity in these diabetic animals. Liver structure and function was analysed in wild‐type and rosiglitazone‐treated and untreated Akita mice, kept for 4 months on the high‐fat and high‐cholesterol diet. Decreased circulating levels of the liver enzymes aspartate and alanine aminotransferase and increased levels of alkaline phosphatases were observed upon rosiglitazone treatment, whereas liver weight was markedly increased. Rosiglitazone administration was associated with liver steatosis, as demonstrated by triglyceride accumulation. However, gene expression of steatosis markers in liver tissue was not markedly affected by rosiglitazone treatment, while expression of fatty acid transport protein was reduced by rosiglitazone treatment, suggesting an impairment of the fatty acid β‐oxidation pathway. mRNA expression of pro‐ and anti‐oxidant enzymes and liver 3‐nitrotyrosine content was not affected. Furthermore, gene and protein expression of macrophage markers and of cell adhesion molecules did not indicate progression to steatohepatitis, whereas an unaltered collagen deposition did not suggest steatofibrosis. In conclusion, rosiglitazone treatment of diabetic Akita mice induced liver steatosis without, however, progression to more advanced stages of liver disease.     

Acute hepatotoxicity: a predictive model based on focused illumina microarrays.

Drug-induced hepatotoxicity is a major issue for drug development, and toxicogenomics has the potential to predict toxicity during early toxicity screening. A bead-based Illumina oligonucleotide microarray containing 550 liver specific genes has been developed. We have established a predictive screening system for acute hepatotoxicity by analyzing differential gene expression profiles of well-known hepatotoxic and nonhepatotoxic compounds. Low and high doses of tetracycline, carbon tetrachloride (CCL4), 1-naphthylisothiocyanate (ANIT), erythromycin estolate, acetaminophen (AAP), or chloroform as hepatotoxicants, clofibrate, theophylline, naloxone, estradiol, quinidine, or dexamethasone as nonhepatotoxic compounds, were administered as a single dose to male Sprague-Dawley rats. After 6, 24, and 72 h, livers were taken for histopathological evaluation and for analysis of gene expression alterations. All hepatotoxic compounds tested generated individual gene expression profiles. Based on leave-one-out cross-validation analysis, gene expression profiling allowed the accurate discrimination of all model compounds, 24 h after high dose treatment. Even during the regeneration phase, 72 h after treatment, CCL4, ANIT, and AAP were predicted to be hepatotoxic, and only these three compounds showed histopathological changes at this time. Furthermore, we identified 64 potential marker genes responsible for class prediction, which reflected typical hepatotoxicity responses. These genes and pathways, commonly deregulated by hepatotoxicants, may be indicative of the early characterization of hepatotoxicity and possibly predictive of later hepatotoxicity onset. Two unknown test compounds were used for prevalidating the screening test system, with both being correctly predicted. We conclude that focused gene microarrays are sufficient to classify compounds with respect to toxicity prediction.     

β-氧化代谢基因多态性与癫痫患儿丙戊酸肝毒性的相关性

目的:分析ACSM2A、CPT1A基因多态性与癫痫患儿丙戊酸(VPA)血药浓度及肝毒性之间的相关性.方法:采用聚合酶链式反应(PCR)和直接测序法检测110例服用丙戊酸单药治疗癫痫患儿外周血ACSM2A rs1133607、CPT1A rs597316基因多态性,并采用液相色谱-质谱联用技术(LC-MS)测定血清VPA...