Publications by authors named "Yongke Lu"

48 Publications

PPARα agonist WY-14,643 enhances ethanol metabolism in mice: Role of catalase.

Free Radic Biol Med 2021 Apr 20;169:283-293. Epub 2021 Apr 20.

Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, 1700 3rd Avenue, Huntington, WV, 25755, USA; Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV, 25755, USA. Electronic address:

Peroxisome proliferator-activated receptor α (PPARα), a fatty acid oxidation regulator, inhibits alcohol-induced fatty liver (AFL). PPARα agonist WY-14,643 ameliorates AFL. Nicotine enhances AFL. In this study, we investigated whether PPARα activation also blocks nicotine-enhanced AFL. Mice were fed liquid diets containing ethanol in the presence or absence of nicotine, WY-14,643 was added to the above diets at 10 mg/L. The results showed that WY-14,643 blunted AFL and nicotine-enhanced AFL, which was paralleled with striking induction of PPARα target genes. However, serum ALT was dramatically increased by the ethanol/WY-14,643 feeding and was further increased by nicotine/ethanol/WY-14,643 feeding, which was confirmed by necro-inflammation and elevated oxidative stress. Interestingly, serum alcohol levels were dramatically decreased by WY-14,643. Ethanol is mainly metabolized by alcohol dehydrogenase (ADH), cytochrome P450 2E1 (CYP2E1) and catalase. ADH and CYP2E1 were not increased by WY-14,643, but catalase was induced. What is more, injection of catalase inhibitor increased serum ethanol. Decreased serum alcohol, attenuated fatty liver, and enhanced liver injury were not induced by WY-14,643 in mice lacking PPARα. In conclusion, PPARα activation by WY-14,643 attenuates alcohol/nicotine-induced fatty liver but deteriorates ethanol/nicotine-induced liver injury; WY-14,643 enhances ethanol metabolism via induction of catalase.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.freeradbiomed.2021.04.018DOI Listing
April 2021

High-fat diet induces fibrosis in mice lacking CYP2A5 and PPARα: a new model for steatohepatitis-associated fibrosis.

Am J Physiol Gastrointest Liver Physiol 2020 11 2;319(5):G626-G635. Epub 2020 Sep 2.

Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia.

Obesity is linked to nonalcoholic steatohepatitis. Peroxisome proliferator-activated receptor-α (PPARα) regulates lipid metabolism. Cytochrome -450 2A5 (CYP2A5) is a potential antioxidant and CYP2A5 induction by ethanol is CYP2E1 dependent. High-fat diet (HFD)-induced obesity and steatosis are more severe in CYP2A5 knockout () mice than in wild-type mice although PPARα is elevated in mice. To examine why the upregulated PPARα failed to prevent the enhanced steatosis in mice, we abrogate the upregulated PPARα in mice by cross-breeding mice with PPARα knockout ) mice to create / mice. The / mice, mice, and mice were fed HFD to induce steatosis. After HFD feeding, more severe steatosis was developed in / mice than in mice and mice. The / mice and mice exhibited comparable and impaired lipid metabolism. Elevated serum alanine transaminase and liver interleukin-1β, liver inflammatory cell infiltration, and foci of hepatocellular ballooning were observed in / mice but not in mice and mice. In / mice, although redox-sensitive transcription factor nuclear factor erythroid 2-related factor 2 and its target antioxidant genes were upregulated as a compensation, thioredoxin was suppressed, and phosphorylation of JNK and formation of nitrotyrosine adduct were increased. Liver glutathione was decreased, and lipid peroxidation was increased. Interestingly, inflammation and fibrosis were all observed within the clusters of lipid droplets, and these lipid droplet clusters were all located inside the area with CYP2E1-positive staining. These results suggest that HFD-induced fibrosis in / mice is associated with steatosis, and CYP2A5 interacts with PPARα to participate in regulating steatohepatitis-associated fibrosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajpgi.00213.2020DOI Listing
November 2020

Pyrosequencing analysis of IRS1 methylation levels in schizophrenia with tardive dyskinesia.

Mol Med Rep 2020 Apr 12;21(4):1702-1708. Epub 2020 Feb 12.

Beijing Huilongguan Hospital, Peking University Huilongguan Clinical Medical School, Beijing 100096, P.R. China.

Tardive dyskinesia (TD) is a serious side effect of certain antipsychotic medications that are used to treat schizophrenia (SCZ) and other mental illnesses. The methylation status of the insulin receptor substrate 1 (IRS1) gene is reportedly associated with SCZ; however, no study, to the best of the authors' knowledge, has focused on the quantitative DNA methylation levels of the IRS1 gene using pyrosequencing in SCZ with or without TD. The present study aimed to quantify DNA methylation levels of 4 CpG sites in the IRS1 gene using a Chinese sample including SCZ patients with TD and without TD (NTD) and healthy controls (HCs). The general linear model (GLM) was used to detect DNA methylation levels among the 3 proposed groups (TD vs. NTD vs. HC). Mean DNA methylation levels of 4 CpG sites demonstrated normal distribution. Pearson's correlation analysis did not reveal any significant correlations between the DNA methylation levels of the 4 CpG sites and the severity of SCZ. GLM revealed significant differences between the 3 groups for CpG site 1 and the average of the 4 CpG sites (P=0.0001 and P=0.0126, respectively). Furthermore, the TD, NTD and TD + NTD groups demonstrated lower methylation levels in CpG site 1 (P=0.0003, P<0.0001 and P<0.0001, respectively) and the average of 4 CpG sites (P=0.0176, P=0.0063 and P=0.003, respectively) compared with the HC group. The results revealed that both NTD and TD patients had significantly decreased DNA methylation levels compared with healthy controls, which indicated a significant association between the DNA methylation levels of the IRS1 gene with SCZ and TD.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3892/mmr.2020.10984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7057828PMC
April 2020

Transplanted adult human hepatic stem/progenitor cells prevent histogenesis of advanced hepatic fibrosis in mice induced by carbon tetrachloride.

Am J Transl Res 2019 15;11(4):2350-2358. Epub 2019 Apr 15.

Institute of Liver Diseases, Affiliated Hospital of Jining Medical University Jining 272000, China.

Transplantation of adult human hepatic stem/progenitor cells (hHSPCs) has been considered as an alternative therapy, replacing donor liver transplantation to treat liver cirrhosis. This study assessed the antifibrotic effects of hHSPCs in mice with fibrosis induced by carbon tetrachloride (CCl) and examined the actions of hHSPCs on the fibrogenic activity of human hepatic stellate cells (HSCs) in a coculture system. Isolated hHSPCs expressed stem/progenitor cell phenotypic markers. Mice were given CCl (twice weekly for 7 weeks) and hHSPC transplantation weekly. CCl induced advanced fibrosis (bridging fibrosis and cirrhosis) in mice, which was prevented by hHSPC transplantation. The liver of hHSPC-transplanted mice showed only occasional short septa and focal parenchymal fibrosis, and a 50% reduction in hepatic collagen, assessed by Sirius red stain histomorphometry. Moreover, the proteins for α-smooth muscle actin (α-SMA) and collagen I were decreased. While α-SMA, collagen α1(I), and tissue inhibitor of metalloproproteinase-1 mRNAs were decreased, matrix metalloproteinase (MMP)-1 mRNA was increased, consistent with decreased fibrogenesis. MMP-2 and transforming growth factor-β were not affected. Alanine aminotransferase and aspartate aminotransferase were lower, suggesting improvement of liver function/damage. In coculture, hHSPCs elicited changes of α-SMA and fibrogenic molecules in HSCs similar to those observed , providing evidence for a functional link between hHSPCs and HSCs. A decreased HSC proliferation was noted. Thus, transplantation of hHSPCs prevents histogenesis of advanced liver fibrosis caused by CCl. hHSPCs mediate downregulation of HSC activation coincident with modulation of fibrogenic molecule expression, leading to suppression of fibrogenesis both and .
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6511762PMC
April 2019

Suppressed hepatocyte proliferation via a ROS-HNE-P21 pathway is associated with nicotine- and cotinine-enhanced alcoholic fatty liver in mice.

Biochem Biophys Res Commun 2019 04 12;512(1):119-124. Epub 2019 Mar 12.

Department of Health Sciences, College of Public Health, East Tennessee State University, Johnson City, TN, 37614, USA. Electronic address:

CYP2A5 is a major enzyme responsible for nicotine and cotinine metabolism in mice. Nicotine and cotinine enhance alcoholic fatty liver in wild type (WT) mice but not in CYP2A5 knockout (KO) mice, and reactive oxygen species (ROS) generated during the CYP2A5-mediated metabolism contributes to the enhancing effect. In combination with ethanol, nicotine and cotinine increased lipid peroxidation end product 4-hydroxynonenal (HNE) in WT mice but not in KO mice. In ethanol-fed KO mice, only 5 and 10 genes were regulated by nicotine and cotinine, respectively. However, in ethanol-fed WT mice, 59 and 104 genes were regulated by nicotine and cotinine, respectively, and 7 genes were up-regulated by both nicotine and cotinine. Plin 2 and Cdkn1a are among the 7 genes. Plin2 encodes adipose differentiation-related protein (ADRP), a lipid droplet-associated protein, which was confirmed to be increased by nicotine and cotinine in WT mice but not in KO mice. Cdkn1a encodes P21 and elevated P21 in nuclei was also confirmed. HNE can increase P21 and P21 inhibit cell proliferation. Consistently, hepatocyte proliferation markers proliferating cell nuclear antigen (PCNA) and Ki67 were decreased in WT mice but not in KO mice by nicotine/ethanol and cotinine/ethanol, respectively. These results suggest that inhibition of liver proliferation via a ROS-HNE-P21 pathway is involved in nicotine- and cotinine-enhanced alcoholic fatty liver.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bbrc.2019.03.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6433518PMC
April 2019

Nicotine enhances alcoholic fatty liver in mice: Role of CYP2A5.

Arch Biochem Biophys 2018 11 15;657:65-73. Epub 2018 Sep 15.

Department of Health Sciences, College of Public Health, East Tennessee State University, Johnson City, TN, 37614, USA; Center of Excellence for Inflammation, Infectious Disease and Immunity, East Tennessee State University, Johnson City, TN, USA. Electronic address:

Tobacco and alcohol are often co-abused. Nicotine can enhance alcoholic fatty liver, and CYP2A6 (CYP2A5 in mice), a major metabolism enzyme for nicotine, can be induced by alcohol. CYP2A5 knockout (cyp2a5) mice and their littermates (cyp2a5) were used to test whether CYP2A5 has an effect on nicotine-enhanced alcoholic fatty liver. The results showed that alcoholic fatty liver was enhanced by nicotine in cyp2a5 mice but not in the cyp2a5 mice. Combination of ethanol and nicotine increased serum triglyceride in cyp2a5 mice but not in the cyp2a5 mice. Cotinine, a major metabolite of nicotine, also enhanced alcoholic fatty liver, which was also observed in cyp2a5 mice but not in the cyp2a5 mice. Nitrotyrosine and malondialdehyde (MDA), markers of oxidative/nitrosative stress, were induced by alcohol and were further increased by nicotine and cotinine in cyp2a5 mice but not in the cyp2a5 mice. Reactive oxygen species (ROS) production during microsomal metabolism of nicotine and cotinine was increased in microsomes from cyp2a5 mice but not in microsomes from cyp2a5 mice. These results suggest that nicotine enhances alcoholic fatty liver in a CYP2A5-dependent manner, which is related to ROS produced during the process of CYP2A5-dependent nicotine metabolism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.abb.2018.09.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6177319PMC
November 2018

Cytochrome P450s and Alcoholic Liver Disease.

Curr Pharm Des 2018 ;24(14):1502-1517

Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, Newyork, United States.

Alcohol consumption causes liver diseases, designated as Alcoholic Liver Disease (ALD). Because alcohol is detoxified by alcohol dehydrogenase (ADH), a major ethanol metabolism system, the development of ALD was initially believed to be due to malnutrition caused by alcohol metabolism in liver. The discovery of the microsomal ethanol oxidizing system (MEOS) changed this dogma. Cytochrome P450 enzymes (CYP) constitute the major components of MEOS. Cytochrome P450 2E1 (CYP2E1) in MEOS is one of the major ROS generators in liver and is considered to be contributive to ALD. Our labs have been studying the relationship between CYP2E1 and ALD for many years. Recently, we found that human CYP2A6 and its mouse analog CYP2A5 are also induced by alcohol. In mice, the alcohol induction of CYP2A5 is CYP2E1-dependent. Unlike CYP2E1, CYP2A5 protects against the development of ALD. The relationship of CYP2E1, CYP2A5, and ALD is a major focus of this review.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1381612824666180410091511DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6053342PMC
October 2019

Polymorphisms Within RYR3 Gene Are Associated With Risk and Age at Onset of Hypertension, Diabetes, and Alzheimer's Disease.

Am J Hypertens 2018 06;31(7):818-826

Department of Health and Biomedical Sciences, College of Health Affairs, University of Texas Rio Grande Valley, Brownsville, Texas, USA.

Background: Hypertension affects 33% of Americans while type 2 diabetes and Alzheimer's disease (AD) affect 10% of Americans, respectively. Ryanodine receptor 3 gene (RYR3) codes for the RYR which functions to release stored endoplasmic reticulum calcium ions (Ca2+) to increase intracellular Ca2+ concentration. Increasing studies demonstrate that altered levels of intracellular Ca2+ affect cardiac contraction, insulin secretion, and neurodegeneration. In this study, we investigated associations of the RYR3 genetic variants with hypertension, AD, and diabetes.

Methods: Family data sets were used to explore association of RYR3 polymorphisms with risk and age at onset (AAO) of hypertension, diabetes, and AD.

Results: Family-based association tests using generalized estimating equations (FBAT-GEE) showed several unique or shared disease-1 associated variants in the RYR3 gene. Three single nuclear polymorphisms (SNPs; rs2033610, rs2596164, and rs2278317) are significantly associated with risk for hypertension, diabetes, and AD. Two SNPs (rs4780174 and rs7498093) are significantly associated with AAO of the 3 diseases.

Conclusions: RYR3 variants are associated with hypertension, diabetes, and AD. Replication of these results of this gene in these 3 complex traits may help to better understand the genetic basis of calcium-signaling gene, RYR3 in association with risk and AAO of these diseases.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/ajh/hpy046DOI Listing
June 2018

CYP2A6 is associated with obesity: studies in human samples and a high fat diet mouse model.

Int J Obes (Lond) 2019 03 20;43(3):475-486. Epub 2018 Feb 20.

Department of Health Sciences, College of Public Health, East Tennessee State University, Johnson City, TN, USA.

Background/objectives: CYP2A6 (CYP2A5 in mice) is mainly expressed in the liver. Hepatic CYP2A6 expression is increased in patients with non-alcoholic fatty liver disease (NAFLD). In mice, hepatic CYP2A5 is induced by high fat diet (HFD) feeding. Hepatic CYP2A5 is also increased in monosodium glutamate-induced obese mice. NAFLD is associated with obesity. In this study, we examined whether obesity is related to CYP2A6.

Subjects/methods: Obesity genetic association study: The SAGE is a comprehensive genome-wide association study (GWAS) with case subjects having a lifetime history of alcohol dependence and control subjects never addicted to alcohol. We used 1030 control individuals with self-reported height and weight. A total of 12 single nucleotide polymorphisms (SNP) within the CYP2A6 gene were available. Obesity was determined as a BMI ≥30: 30-34.9 (Class I obesity) and ≥35 (Class II and III obesity). Animal experiment study: CYP2A5 knockout (cyp2a5) mice and wild type (cyp2a5) mice were fed HFD for 14 weeks. Body weight was measured weekly. After an overnight fast, the mice were sacrificed. Liver and blood were collected for biochemical assays.

Results: Single marker analysis showed that three SNPs (rs8192729, rs7256108, and rs7255443) were associated with class I obesity (p < 0.05). The most significant SNP for obesity was rs8192729 (odds ratio (OR) = 1.94, 95% confidence intervals = 1.21-3.10, p = 0.00582). After HFD feeding, body weight was increased in cyp2a5 mice to a greater extent than in cyp2a5 mice, and fatty liver was more pronounced in cyp2a5 mice than in cyp2a5 mice. PPARα deficiency in cyp2a5 mice developed more severe fatty liver, but body weight was not increased significantly.

Conclusion: CYP2A6 is associated with human obesity; CYP2A5 protects against obesity and NAFLD in mice. PPARα contributes to the CYP2A5 protective effects on fatty liver but it opposes to the protective effects on obesity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41366-018-0037-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6102101PMC
March 2019

The adipokine C1q TNF related protein 3 (CTRP3) is elevated in the breast milk of obese mothers.

PeerJ 2018 5;6:e4472. Epub 2018 Mar 5.

Department of Health Sciences, College of Public Health, East Tennessee State University, Johnson City, TN, USA.

Background: C1q TNF related protein 3 (CTRP3) is a relatively novel hormonal factor primarily derived from adipose tissue and has anti-diabetic properties. To determine if CTRP3 could play a role in early childhood development, the purpose of this study was to establish the presence of CTRP3 in breast milk (BM) and to determine whether CTRP3 levels were correlated with pregravid obesity status of the mother.

Methods: Breast milk was collected from breast-feeding mothers who had a pregravid body mass index (BMI) classification of normal weight (BMI 18-25 kg/m, = 23) or obese (BMI > 30 kg/m, = 14). Immunoprecipitation followed by immunoblot analysis confirmed the presence of CTRP3 in BM. The concentration of CTRP3 in BM samples was determined by ELISA. Additional bioactive components were also measured by commercially available assays: ghrelin, insulin, leptin, adiponectin, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and glucose. Bioactive components in normal weight and obese mothers were compared using unpaired -test (parametric) and Mann-Whitney -test (non-parametric), as appropriate.

Results: The primary findings of this study are that the adipokine CTRP3 is present in BM and CTRP3 levels are increased with pregravid obesity. Additionally, this study independently confirmed previous work that BM from obese mothers has a higher concentration of insulin and leptin. Further, no differences were observed in BM between obese and normal weight mothers in ghrelin, adiponectin, IL-6, TNF-α, or glucose levels.

Conclusion: This study identified a novel factor in BM, CTRP3, and showed that BM CTRP3 levels higher in obese mothers. Because of the purported insulin sensitizing effect of CTRP3, it is possible that the elevated levels of CTRP3 in the BM of obese mothers may offset negative effects of elevated leptin and insulin levels in the BM of obese mothers. Future studies will need to be conducted to determine the relevance of CTRP3 in BM and to examine the presence of other adipose tissue-derived hormonal factors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.7717/peerj.4472DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5842766PMC
March 2018

Author Correction: Midbrain circuit regulation of individual alcohol drinking behaviors in mice.

Nat Commun 2018 02 8;9(1):653. Epub 2018 Feb 8.

Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.

The original version of this Article contained an error in the spelling of the author Scott Edwards, which was incorrectly given as Scott Edward. This has now been corrected in both the PDF and HTML versions of the Article.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-018-02921-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5805722PMC
February 2018

Osteopontin deletion drives hematopoietic stem cell mobilization to the liver and increases hepatic iron contributing to alcoholic liver disease.

Hepatol Commun 2018 01 12;2(1):84-98. Epub 2017 Nov 12.

Department of Pathology University of Illinois at Chicago Chicago IL.

The aim of this study was to investigate the role of osteopontin (OPN) in hematopoietic stem cell (HPSC) mobilization to the liver and its contribution to alcoholic liver disease (ALD). We analyzed young (14-16 weeks) and old (>1.5 years) wild-type (WT) littermates and global knockout ( ) mice for HPSC mobilization to the liver. In addition, WT and mice were chronically fed the Lieber-DeCarli diet for 7 weeks. Bone marrow (BM), blood, spleen, and liver were analyzed by flow cytometry for HPSC progenitors and polymorphonuclear neutrophils (PMNs). Chemokines, growth factors, and cytokines were measured in serum and liver. Prussian blue staining for iron deposits and naphthol AS-D chloroacetate esterase staining for PMNs were performed on liver sections. Hematopoietic progenitors were lower in liver and BM of young compared to old mice. Granulocyte colony-stimulating factor and macrophage colony-stimulating factor were increased in mice, suggesting potential migration of HPSCs from the BM to the liver. Furthermore, ethanol-fed mice showed significant hepatic PMN infiltration and hemosiderin compared to WT mice. As a result, ethanol feeding caused greater liver injury in compared to WT mice. deletion promotes HPSC mobilization, PMN infiltration, and iron deposits in the liver and thereby enhances the severity of ALD. The age-associated contribution of OPN to HPSC mobilization to the liver, the prevalence of PMNs, and accumulation of hepatic iron, which potentiates oxidant stress, reveal novel signaling mechanisms that could be targeted for therapeutic benefit in patients with ALD. ( 2018;2:84-98).
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/hep4.1116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5776866PMC
January 2018

Midbrain circuit regulation of individual alcohol drinking behaviors in mice.

Nat Commun 2017 12 20;8(1):2220. Epub 2017 Dec 20.

Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA.

Alcohol-use disorder (AUD) is the most prevalent substance-use disorder worldwide. There is substantial individual variability in alcohol drinking behaviors in the population, the neural circuit mechanisms of which remain elusive. Utilizing in vivo electrophysiological techniques, we find that low alcohol drinking (LAD) mice have dramatically higher ventral tegmental area (VTA) dopamine neuron firing and burst activity. Unexpectedly, VTA dopamine neuron activity in high alcohol drinking (HAD) mice does not differ from alcohol naive mice. Optogenetically enhancing VTA dopamine neuron burst activity in HAD mice decreases alcohol drinking behaviors. Circuit-specific recordings reveal that spontaneous activity of nucleus accumbens-projecting VTA (VTA-NAc) neurons is selectively higher in LAD mice. Specifically activating this projection is sufficient to reduce alcohol consumption in HAD mice. Furthermore, we uncover ionic and cellular mechanisms that suggest unique neuroadaptations between the alcohol drinking groups. Together, these data identify a neural circuit responsible for individual alcohol drinking behaviors.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1038/s41467-017-02365-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5738419PMC
December 2017

Alcoholic fatty liver is enhanced in CYP2A5 knockout mice: The role of the PPARα-FGF21 axis.

Toxicology 2017 03 25;379:12-21. Epub 2017 Jan 25.

Department of Health Sciences, College of Public Health, East Tennessee State University, Johnson City, TN, United States; Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, New York, United States. Electronic address:

Background & Aims: Cytochrome P450 2A5 (CYP2A5) is induced by ethanol, and the ethanol induction of CYP2A5 is regulated by nuclear factor-erythroid 2-related factor 2 (NRF2). Cyp2a5 knockout (Cyp2a5) mice develop more severe alcoholic fatty liver than Cyp2a5 mice. Fibroblast growth factor 21 (FGF21), a PPARα-regulated liver hormone, is involved in hepatic lipid metabolism. Alcoholic and non-alcoholic fatty liver are enhanced in Pparα knockout (Pparα) mice. This study investigates the relationship between the PPARα-FGF21 axis and the enhanced alcoholic fatty liver in Cyp2a5 mice.

Methods: Mice were fed the Lieber-Decarli ethanol diet to induce alcoholic fatty liver.

Results: More severe alcoholic fatty liver disease was developed in Cyp2a5 mice than in Cyp2a5 mice. Basal FGF21 levels were higher in Cyp2a5 mice than in Cyp2a5 mice, but ethanol did not further increase the elevated FGF21 levels in Cyp2a5 mice while FGF21 was induced by ethanol in Cyp2a5 mice. Basal levels of serum FGF21 were lower in Pparα mice than in Pparα mice; ethanol induced FGF21 in Pparα mice but not in Pparα mice, whereas ethanol induced hypertriglyceridemia in Pparα mice but not in Pparα mice. Administration of recombinant FGF21 normalized serum FGF21 and triglyceride in Pparα mice. Alcoholic fatty liver was enhanced in liver-specific Fgf21 knockout mice. Pparα and Cyp2a5 double knockout (Pparα/Cyp2a5) mice developed more severe alcoholic fatty liver than Pparα/Cyp2a5 mice.

Conclusions: These results suggest that CYP2A5 protects against the development of alcoholic fatty liver disease, and the PPARα-FGF21 axis contributes to the protective effects of CYP2A5 on alcoholic fatty liver disease.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.tox.2017.01.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5319905PMC
March 2017

Alcohol Upregulation of CYP2A5: Role of Reactive Oxygen Species.

React Oxyg Species (Apex) 2016 Mar;1(2):117-130

Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

Hepatic cytochrome P450 (CYP) 2E1 and CYP2A5 activate many important drugs and hepatotoxins. CYP2E1 is induced by alcohol, but whether CYP2A5 is upregulated by alcohol is not known. This article reviews recent studies on the induction of CYP2A5 by alcohol and the mechanism and role of reactive oxygen species (ROS) in this upregulation. Chronic feeding of ethanol to wild type mice increased CYP2A5 catalytic activity and protein and mRNA levels. This induction was blunted in CYP2E1 knockout mice and by a CYP2E1 inhibitor, but was restored in CYP2E1 knockin mice, suggesting a role for CYP2E1 in the induction of CYP2A5 by alcohol. Since CYP2E1 actively generates ROS, the possible role of ROS in the induction of CYP2A5 by alcohol was determined. ROS production was elevated by ethanol treatment. The antioxidants -acetyl cysteine and vitamin C lowered the alcohol-induced elevation of ROS and blunted the alcohol-mediated induction of CYP2A5. These results suggest that ROS play a novel role in the crosstalk between CYP2E1 and CYP2A5. Alcohol treatment activated nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2), a transcription factor which up-regulates expression of CYP2A5. The antioxidants blocked the activation of Nrf2. The alcohol-induced elevation of CYP2A5, but not CYP2E1, was lower in Nrf2 knockout mice. We propose that increased generation of ROS from the alcohol-induced CYP2E1 activates Nrf2, which subsequently up-regulates the expression of CYP2A5. Thus, a novel consequence of the alcohol-mediated induction of CYP2E1 and increase in ROS is the activation of redox-sensitive transcription factors, such as Nrf2, and expression of CYP2A5. Further perspectives on this alcohol-CYP2E1-ROS-Nrf2-CYP2A5 pathway are presented.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5944604PMC
March 2016

Signalling via the osteopontin and high mobility group box-1 axis drives the fibrogenic response to liver injury.

Gut 2017 06 27;66(6):1123-1137. Epub 2016 Jan 27.

Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA.

Objective: Liver fibrosis is associated with significant collagen-I deposition largely produced by activated hepatic stellate cells (HSCs); yet, the link between hepatocyte damage and the HSC profibrogenic response remains unclear. Here we show significant induction of osteopontin (OPN) and high-mobility group box-1 (HMGB1) in liver fibrosis. Since OPN was identified as upstream of HMGB1, we hypothesised that OPN could participate in the pathogenesis of liver fibrosis by increasing HMGB1 to upregulate collagen-I expression.

Design And Results: Patients with long-term hepatitis C virus (HCV) progressing in disease stage displayed enhanced hepatic OPN and HMGB1 immunostaining, which correlated with fibrosis stage, whereas it remained similar in non-progressors. Hepatocyte cytoplasmic OPN and HMGB1 expression was significant while loss of nuclear HMGB1 occurred in patients with HCV-induced fibrosis compared with healthy explants. Well-established liver fibrosis along with marked induction of HMGB1 occurred in CCl-injected transgenic yet it was less in wild type and almost absent in mice. ablation in hepatocytes () protected mice from CCl-induced liver fibrosis. Coculture with hepatocytes that secrete OPN plus HMGB1 and challenge with recombinant OPN (rOPN) or HMGB1 (rHMGB1) enhanced collagen-I expression in HSCs, which was blunted by neutralising antibodies (Abs) and by or ablation. rOPN induced acetylation of HMGB1 in HSCs due to increased NADPH oxidase activity and the associated decrease in histone deacetylases 1/2 leading to upregulation of collagen-I. Last, rHMGB1 signalled via receptor for advanced glycation end-products and activated the PI3K-pAkt1/2/3 pathway to upregulate collagen-I.

Conclusions: During liver fibrosis, the increase in OPN induces HMGB1, which acts as a downstream alarmin driving collagen-I synthesis in HSCs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/gutjnl-2015-310752DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532463PMC
June 2017

Autophagy Protects against CYP2E1/Chronic Ethanol-Induced Hepatotoxicity.

Biomolecules 2015 Oct 16;5(4):2659-74. Epub 2015 Oct 16.

Department of Pharmacology and Systems Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.

Autophagy is an intracellular pathway by which lysosomes degrade and recycle long-lived proteins and cellular organelles. The effects of ethanol on autophagy are complex but recent studies have shown that autophagy serves a protective function against ethanol-induced liver injury. Autophagy was found to also be protective against CYP2E1-dependent toxicity in vitro in HepG2 cells which express CYP2E1 and in vivo in an acute alcohol/CYPE1-dependent liver injury model. The goal of the current report was to extend the previous in vitro and acute in vivo experiments to a chronic ethanol model to evaluate whether autophagy is also protective against CYP2E1-dependent liver injury in a chronic ethanol-fed mouse model. Wild type (WT), CYP2E1 knockout (KO) or CYP2E1 humanized transgenic knockin (KI), mice were fed an ethanol liquid diet or control dextrose diet for four weeks. In the last week, some mice received either saline or 3-methyladenine (3-MA), an inhibitor of autophagy, or rapamycin, which stimulates autophagy. Inhibition of autophagy by 3-MA potentiated the ethanol-induced increases in serum transaminase and triglyceride levels in the WT and KI mice but not KO mice, while rapamycin prevented the ethanol liver injury. Treatment with 3-MA enhanced the ethanol-induced fat accumulation in WT mice and caused necrosis in the KI mice; little or no effect was found in the ethanol-fed KO mice or any of the dextrose-fed mice. 3-MA treatment further lowered the ethanol-decrease in hepatic GSH levels and further increased formation of TBARS in WT and KI mice, whereas rapamycin blunted these effects of ethanol. Neither 3-MA nor rapamycin treatment affected CYP2E1 catalytic activity or content or the induction CYP2E1 by ethanol. The 3-MA treatment decreased levels of Beclin-1 and Atg 7 but increased levels of p62 in the ethanol-fed WT and KI mice whereas rapamycin had the opposite effects, validating inhibition and stimulation of autophagy, respectively. These results suggest that autophagy is protective against CYP2E1-dependent liver injury in a chronic ethanol-fed mouse model. We speculate that autophagy-dependent processes such as mitophagy and lipophagy help to minimize ethanol-induced CYP2E1-dependent oxidative stress and therefore the subsequent liver injury and steatosis. Attempts to stimulate autophagy may be helpful in lowering ethanol and CYP2E1-dependent liver toxicity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.3390/biom5042659DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4693252PMC
October 2015

The role of CYP2A5 in liver injury and fibrosis: chemical-specific difference.

Naunyn Schmiedebergs Arch Pharmacol 2016 Jan 12;389(1):33-43. Epub 2015 Sep 12.

Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY, 10029, USA.

Liver injuries induced by carbon tetrachloride (CCL4) or thioacetamide (TAA) are dependent on cytochrome P450 2E1 (CYP2E1). CYP2A5 can be induced by TAA but not by CCL4. In this study, liver injury including fibrosis induced by CCL4 or TAA were investigated in wild-type (WT) mice and CYP2A5 knockout (cyp2a5 (-/-) ) mice as well as in CYP2E1 knockout (cyp2e1 (-/-) ) mice as a comparison. Acute and subchronic liver injuries including fibrosis were induced by CCL4 and TAA in WT mice but not in cyp2e1 (-/-) mice, confirming the indispensable role of CYP2E1 in CCL4 and TAA hepatotoxicity. WT mice and cyp2a5 (-/-) mice developed comparable acute liver injury induced by a single injection of CCL4 as well as subchronic liver injury including fibrosis induced by 1 month of repeated administration of CCL4, suggesting that CYP2A5 does not affect CCL4-induced liver injury and fibrosis. However, while 200 mg/kg TAA-induced acute liver injury was comparable in WT mice and cyp2a5 (-/-) mice, 75 and 100 mg/kg TAA-induced liver injury were more severe in cyp2a5 (-/-) mice than those found in WT mice. After multiple injections with 200 mg/kg TAA for 1 month, while subchronic liver injury as indicated by serum aminotransferases was comparable in WT mice and cyp2a5 (-/-) mice, liver fibrosis was more severe in cyp2a5 (-/-) mice than that found in WT mice. These results suggest that while both CCL4- and TAA-induced liver injuries and fibrosis are CYP2E1 dependent, under some conditions, CYP2A5 may protect against TAA-induced liver injury and fibrosis, but it does not affect CCL4 hepatotoxicity.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00210-015-1172-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4703559PMC
January 2016

Alcoholic Liver Disease: from CYP2E1 to CYP2A5.

Curr Mol Pharmacol 2017 ;10(3):172-178

Department of Structural and Chemical Biology, Box 1677, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029. United States.

This article reviews recent studies on CYP2E1-mediated alcoholic liver injury, the induction of CYP2A5 by alcohol and the mechanism for this upregulation, especially the permissive role of CYP2E1 in the induction of CYP2A5 by alcohol and the CYP2E1-ROS-Nrf2 pathway, and protective effects of CYP2A5 against ethanol-induced oxidative liver injury. Ethanol can induce CYP2E1, an active generator of reactive oxygen species (ROS), and CYP2E1 is a contributing factor for alcoholinduced oxidative liver injury. CYP2A5, another isoform of cytochrome P450, can also be induced by ethanol. Chronic feeding of ethanol to wild type mice increased CYP2A5 catalytic activity, protein and mRNA levels as compared to pair-fed controls. This induction was blunted in CYP2E1 knockout (cyp2e1-/-) mice but was restored when human CYP2E1 was reintroduced and expressed in cyp2e1-/- mice. Ethanol-induced CYP2E1 co-localized with CYP2A5 and preceded the elevation of CYP2A5. The antioxidants N-acetyl cysteine and vitamin C lowered the alcohol elevation of ROS and blunted the alcohol induction of CYP2A5, but not CYP2E1, suggesting ROS play a novel role in the crosstalk between CYP2E1 and CYP2A5. The antioxidants blocked the activation of Nrf2, a transcription factor known to upregulate expression of CYP2A5. When alcohol-induced liver injury was enhanced in Nrf2 knockout (Nrf2-/-) mice, alcohol elevation of CYP2A5 but not CYP2E1 was also lower in Nrf2-/- mice. CYP2A5 knockout (cyp2a5-/-) mice exhibited an enhanced alcoholic liver injury compared with WT mice as indicated by serum ALT, steatosis and necroinflammation. Alcohol-induced hyperglycemia were observed in cyp2a5-/- mice but not in WT mice.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.2174/1874467208666150817111846DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5856453PMC
February 2019

Absence of cytochrome P450 2A5 enhances alcohol-induced liver injury in mice.

Dig Liver Dis 2015 Jun 6;47(6):470-7. Epub 2015 Mar 6.

Department of Structural and Chemical Biology, Icahn School of Medicine at Mount Sinai, New York, NY, United States. Electronic address:

Background: Ethanol can induce cytochrome P450 2E1, an active generator of reactive oxygen species, and this cytochrome is considered a risk factor for oxidative liver injury. Recently, we found that in addition to P450 2E1 also cytochrome P450 2A5, another isoform of cytochrome P450, can be induced by ethanol, and that ethanol induction of cytochrome P450 2A5 is P450 2E1-dependent.

Aims: To investigate the role of cytochrome P450 2A5 in alcohol-induced liver injury.

Methods: Cytochrome P450 2A5-knockout mice and wild type mice were fed the Lieber-Decarli ethanol liquid diet to induce liver injury. Controls were fed the Lieber-Decarli control diet.

Results: After 4 weeks of feeding with Lieber-Decarli diet, ethanol-induced liver injury was enhanced in the knockout mice compared with wild type mice, as indicated by serum transaminases, hepatic fat accumulation (steatosis), and necroinflammation observed in liver sections with Haematoxylin & Eosin staining. Ethanol-induced oxidative stress was also higher in the knockout mice than the wild types. Ethanol feeding induced cytochrome P450 2A5 in wild type mice but not in the knockout mice, while induction of cytochrome P450 2E1 was comparable in the knockout and wild type mice.

Conclusion: These results suggest that cytochrome P450 2A5 protects against ethanol-induced oxidative liver injury.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.dld.2015.02.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4442740PMC
June 2015

Synergistic toxic interactions between CYP2E1, LPS/TNFα, and JNK/p38 MAP kinase and their implications in alcohol-induced liver injury.

Adv Exp Med Biol 2015 ;815:145-72

Department of Pharmacology and Systems Therapeutics, Mount Sinai School of Medicine, Box 1603, One Gustave L. Levy Place, New York, NY, 10029, USA,

The mechanisms by which alcohol causes cell injury are not clear. Many pathways have been suggested to play a role in how alcohol induces oxidative stress. Considerable attention has been given to alcohol-elevated production of lipopolysaccharide (LPS) and TNFα and to alcohol induction of CYP2E1. These two pathways are not exclusive of each other; however, associations and interactions between them, especially in vivo, have not been extensively evaluated. We have shown that increased oxidative stress from induction of CYP2E1 in vivo sensitizes hepatocytes to LPS and TNFα toxicity and that oxidative stress, activation of p38 and JNK MAP kinases, and mitochondrial dysfunction are downstream mediators of this CYP2E1-LPS/TNFα potentiated hepatotoxicity. This Review will summarize studies showing potentiated interactions between these two risk factors in promoting liver injury and the mechanisms involved including activation of the mitogen-activated kinase kinase kinase ASK-1 as a result of CYP2E1-derived reactive oxygen intermediates promoting dissociation of the inhibitory thioredoxin from ASK-1. This activation of ASK-1 is followed by activation of the mitogen-activated kinase kinases MKK3/MKK6 and MKK4/MMK7 and subsequently p38 and JNK MAP kinases. Synergistic toxicity occurs between CYP2E1 and the JNK1 but not the JNK2 isoform as JNK1 knockout mice are completely protected against CYP2E1 plus TNFα toxicity, elevated oxidative stress, and mitochondrial dysfunction. We hypothesize that similar interactions occur as a result of ethanol induction of CYP2E1 and TNFα.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/978-3-319-09614-8_9DOI Listing
March 2015

High mobility group box-1 (HMGB1) participates in the pathogenesis of alcoholic liver disease (ALD).

J Biol Chem 2014 Aug 13;289(33):22672-22691. Epub 2014 Jun 13.

Division of Liver Diseases, Department of Medicine and Icahn School of Medicine at Mount Sinai, New York, New York 10029. Electronic address:

Growing clinical and experimental evidence suggests that sterile inflammation contributes to alcoholic liver disease (ALD). High mobility group box-1 (HMGB1) is highly induced during liver injury; however, a link between this alarmin and ALD has not been established. Thus, the aim of this work was to determine whether HMGB1 contributes to the pathogenesis of ALD. Liver biopsies from patients with ALD showed a robust increase in HMGB1 expression and translocation, which correlated with disease stage, compared with healthy explants. Similar findings were observed in chronic ethanol-fed wild-type (WT) mice. Using primary cell culture, we validated the ability of hepatocytes from ethanol-fed mice to secrete a large amount of HMGB1. Secretion was time- and dose-dependent and responsive to prooxidants and antioxidants. Selective ablation of Hmgb1 in hepatocytes protected mice from alcohol-induced liver injury due to increased carnitine palmitoyltransferase-1, phosphorylated 5'AMP-activated protein kinase-α, and phosphorylated peroxisome proliferator-activated receptor-α expression along with elevated LDL plus VLDL export. Native and post-translationally modified HMGB1 were detected in humans and mice with ALD. In liver and serum from control mice and in serum from healthy volunteers, the lysine residues within the peptides containing nuclear localization signals (NLSs) 1 and 2 were non-acetylated, and all cysteine residues were reduced. However, in livers from ethanol-fed mice, in addition to all thiol/non-acetylated isoforms of HMGB1, we observed acetylated NLS1 and NLS2, a unique phosphorylation site in serine 35, and an increase in oxidation of HMGB1 to the disulfide isoform. In serum from ethanol-fed mice and from patients with ALD, there was disulfide-bonded hyperacetylated HMGB1, disulfide-bonded non-acetylated HMGB1, and HMGB1 phosphorylated in serine 35. Hepatocytes appeared to be a major source of these HMGB1 isoforms. Thus, hepatocyte HMGB1 participates in the pathogenesis of ALD and undergoes post-translational modifications (PTMs) that could condition its toxic effects.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1074/jbc.M114.552141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4132775PMC
August 2014

Osteopontin induces ductular reaction contributing to liver fibrosis.

Gut 2014 Nov 4;63(11):1805-18. Epub 2014 Feb 4.

Division of Liver Diseases, Department of Medicine, Ichan School of Medicine at Mount Sinai, New York, New York, USA.

Objective: In human chronic liver disease, there is association between ductular reaction (DR) and fibrosis; yet, the mechanism triggering its onset and its role in scar formation remains unknown. Since we previously showed that osteopontin (OPN) is highly induced during drug-induced liver fibrosis, we hypothesised that OPN could drive oval cells (OC) expansion and DR and signal to hepatic stellate cells (HSC) to promote scarring.

Results: In vivo studies demonstrated increased OPN expression in biliary epithelial cells (BEC) and in OC in thioacetamide (TAA)-treated mice. OPN ablation protected mice from TAA and bile duct ligation-induced liver injury, DR and scarring. This was associated with greater hepatocyte proliferation, lower OC expansion and DR along with less fibrosis, suggesting that OPN could activate the OC compartment to differentiate into BEC, which could then signal to HSC to enhance scarring. Since TAA-treated wild-type mice and cirrhotic patients showed TGF-β(+) BEC, which were lacking in TAA-treated Opn(-/-) mice and in healthy human explants, this suggested that OPN could regulate TGF-β, a profibrogenic factor. In vitro experiments confirmed that recombinant OPN (rOPN) decreases hepatocyte proliferation and increases OC and BEC proliferation. To evaluate how BEC regulate collagen-I production in HSC, co-cultures were established. Co-cultured BEC upregulated OPN and TGF-β expression and enhanced collagen-I synthesis by HSC. Lastly, recombinant TGF-β (rTGFβ) and rOPN promoted BEC proliferation and neutralisation of OPN and TGF-β reduced collagen-I expression in co-cultured HSC.

Conclusions: OPN emerges as a key matricellular protein driving DR and contributing to scarring and liver fibrosis via TGF-β.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/gutjnl-2013-306373DOI Listing
November 2014

Ethanol plus the Jo2 Fas agonistic antibody-induced liver injury is attenuated in mice with partial ablation of argininosuccinate synthase.

Alcohol Clin Exp Res 2014 Mar 13;38(3):649-56. Epub 2013 Nov 13.

Division of Liver Diseases , Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.

Background: Argininosuccinate synthase (ASS) is an enzyme shared by the urea cycle and the l-citrulline/nitric oxide (NO·) cycle. ASS is the rate-limiting enzyme in the urea cycle and along with nitric oxide synthase 2 (NOS2), it endows cells with the l-citrulline/NO· salvage pathway to continuously supply l-arginine from l-citrulline for sustained NO· generation. Thus, ASS conditions NO· synthesis by NOS2. Because of the relevance of NOS2 activation for liver injury, we examined the contribution of ASS to NO· generation and how it impacts liver injury.

Methods: Wild-type (WT) mice and Ass(+/-) mice (Ass(-/-) mice are lethal) were intraperitoneally injected with ethanol (EtOH) at a dose of 2.5 g/kg of body weight twice a day for 3 days. Two hours after the last dose of EtOH, mice were administered the agonistic Jo2 anti-mouse Fas monoclonal antibody (Ab) at a dose of 0.2 μg/g of body weight. Mice were sacrificed 8 hours after the Jo2 Ab injection. Markers of nitrosative and oxidative stress as well as liver damage were analyzed.

Results: EtOH plus Jo2 injection induced liver injury as shown by serum alanine aminotransferase and aspartate aminotransferase activity, liver pathology, TUNEL, and cleaved caspase-3 were lower in Ass(+/-) mice compared with WT mice, suggesting that ASS contributes to EtOH plus Jo2-mediated liver injury. CYP2E1 induction, glutathione depletion, and elevated thiobarbituric acid reactive substances were comparable in both groups of mice, suggesting that CYP2E1-mediated oxidative stress is not linked to ASS-induced liver injury. In contrast, NOS2 induction, 3-nitrotyrosine adducts formation and elevated nitrites, nitrates, and S-nitrosothiols were higher in livers from WT mice than from Ass(+/-) mice.

Conclusion: Decreased nitrosative stress causes lower EtOH plus Jo2-induced liver injury in Ass(+/-) mice.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/acer.12309DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3959268PMC
March 2014

Osteopontin binding to lipopolysaccharide lowers tumor necrosis factor-α and prevents early alcohol-induced liver injury in mice.

Hepatology 2014 Apr 1;59(4):1600-16. Epub 2014 Mar 1.

Division of Liver Diseases, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Unlabelled: Although osteopontin (OPN) is induced in alcoholic patients, its role in the pathophysiology of alcoholic liver disease (ALD) remains unclear. Increased translocation of lipopolysaccharide (LPS) from the gut is key for the onset of ALD because it promotes macrophage infiltration and activation, tumor necrosis factor-α (TNFα) production, and liver injury. Since OPN is protective for the intestinal mucosa, we postulated that enhancing OPN expression in the liver and consequently in the blood and/or in the gut could protect from early alcohol-induced liver injury. Wild-type (WT), OPN knockout (Opn(-/-)), and transgenic mice overexpressing OPN in hepatocytes (Opn(HEP) Tg) were fed either the control or the ethanol Lieber-DeCarli diet. Ethanol increased hepatic, plasma, biliary, and fecal OPN more in Opn(HEP) Tg than in WT mice. Steatosis was less in ethanol-treated Opn(HEP) Tg mice as shown by decreased liver-to-body weight ratio, hepatic triglycerides, the steatosis score, oil red-O staining, and lipid peroxidation. There was also less inflammation and liver injury as demonstrated by lower alanine aminotransferase (ALT) activity, hepatocyte ballooning degeneration, LPS levels, the inflammation score, and the number of macrophages and TNFα(+) cells. To establish if OPN could limit LPS availability and its noxious effects in the liver, binding studies were performed. OPN showed binding affinity for LPS which prevented macrophage activation, reactive oxygen, and nitrogen species generation and TNFα production. Treatment with milk OPN (m-OPN) blocked LPS translocation in vivo and protected from early alcohol-induced liver injury.

Conclusion: Natural induction plus forced overexpression of OPN in the liver or treatment with m-OPN protect from early alcohol-induced liver injury by blocking the gut-derived LPS and TNFα effects in the liver.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/hep.26931DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3966944PMC
April 2014

Nicotine enhances ethanol-induced fat accumulation and collagen deposition but not inflammation in mouse liver.

Alcohol 2013 Aug 31;47(5):353-7. Epub 2013 May 31.

Division of Liver Diseases, Department of Medicine, Mount Sinai School of Medicine, One Gustave L. Levy Place, New York, NY 10029, USA.

Introduction: Alcohol and tobacco are frequently co-abused. Tobacco smoke increases alcoholic steatosis in apoE(-/-) mice. Tobacco smoke contains more than 4000 chemicals, but it is unknown which compounds in tobacco smoke play a major role in increasing alcoholic steatosis.

Methods: C57BL/J6 mice were intraperitoneally injected with nicotine at 1 mg/kg every day or saline at the same volume as a control and the mice were fed dextrose-control or ethanol Lieber-DeCarli liquid diets. Three weeks later the mice were sacrificed after overnight fasting.

Results: Neither nicotine injection nor ethanol feeding alone increased serum levels of triglyceride, but the combination of nicotine and ethanol increased serum levels of triglyceride. Both nicotine injection alone and ethanol feeding alone increased hepatic collagen type I deposition, and nicotine injection and ethanol feeding combined further increased hepatic collagen type I deposition. The combination of nicotine and ethanol also activated hepatic stellate cells, a principal liver fibrogenic cell. Hepatic fat accumulation was induced by ethanol feeding, which was further enhanced by nicotine injection. Ethanol feeding caused an increase in serum ALT, but nicotine did not further increase serum ALT levels. Lipid droplets and inflammatory foci were observed in liver sections from ethanol-fed mice; nicotine treatment increased the number and size of lipid droplets, but not the number and size of inflammatory foci. Nicotine did not further increase ethanol-induced hepatic neutrophil infiltration.

Conclusions: These results suggest that nicotine enhances ethanol-induced steatosis and collagen deposition, but nicotine has no effect on ethanol-induced inflammation.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.alcohol.2013.04.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3723131PMC
August 2013

Milk osteopontin, a nutritional approach to prevent alcohol-induced liver injury.

Am J Physiol Gastrointest Liver Physiol 2013 May 21;304(10):G929-39. Epub 2013 Mar 21.

Div. of Liver Diseases, Dept. of Medicine, Mount Sinai School of Medicine, Box 11-23, 1425 Madison Ave., Rm. 11-70, New York, NY 10029, USA.

Alcohol consumption is a leading cause of liver disease worldwide; thus, there is an urgent need to develop novel therapeutic interventions. Key events for the onset and progression of alcoholic liver disease result in part from the gut-to-liver interaction. Osteopontin is a cytokine present at high concentration in human milk, umbilical cord, and infants' plasma with beneficial potential. We hypothesized that dietary administration of milk osteopontin could prevent alcohol-induced liver injury perhaps by maintaining gut integrity and averting hepatic inflammation and steatosis. Wild-type mice were fed either the control or the ethanol Lieber-DeCarli diets alone or in combination with milk osteopontin for 3 wk, and parameters of gut and liver damage were measured. Milk osteopontin protected the stomach and the gut by increasing gland height, crypt cell plus enterocyte proliferation, and mucin content in addition to lowering macrophages, plasmacytes, lymphocytes, and neutrophils in the mucosa and submucosa in alcohol-fed mice. Milk osteopontin targeted the gut-liver axis, preserving the expression of tight-junction proteins in alcohol-fed mice thus maintaining intestinal integrity and permeability. There was protection from liver injury since transaminases, the activity scores, triglyceride levels, neutrophil infiltration, 3-nitrotyrosine residues, lipid peroxidation end products, translocation of gram-negative bacteria, lipopolysaccharide levels, and tumor necrosis factor-α were lower in cotreated than in ethanol-fed mice. Furthermore, milk osteopontin diminished ethanol-mediated liver injury in OPN knockout mice. Milk osteopontin could be a simple effective nutritional therapeutic strategy to prevent alcohol hepatotoxicity due, among others, to gut protective, anti-inflammatory, and anti-steatotic actions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1152/ajpgi.00014.2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3652071PMC
May 2013

Reversal by RARα agonist Am580 of c-Myc-induced imbalance in RARα/RARγ expression during MMTV-Myc tumorigenesis.

Breast Cancer Res 2012 Aug 24;14(4):R121. Epub 2012 Aug 24.

Introduction: Retinoic acid signaling plays key roles in embryonic development and in maintaining the differentiated status of adult tissues. Recently, the nuclear retinoic acid receptor (RAR) isotypes α, β and γ were found to play specific functions in the expansion and differentiation of the stem compartments of various tissues. For instance, RARγ appears to be involved in stem cell compartment expansion, while RARα and RARβ are implicated in the subsequent cell differentiation. We found that over-expressing c-Myc in normal mouse mammary epithelium and in a c-Myc-driven transgenic model of mammary cancer, disrupts the balance between RARγ and RARα/β in favor of RARγ.

Methods: The effects of c-Myc on RAR isotype expression were evaluated in normal mouse mammary epithelium, mammary tumor cells obtained from the MMTV-Myc transgenic mouse model as well as human normal immortalized breast epithelial and breast cancer cell lines. The in vivo effect of the RARα-selective agonist 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carboxamido]benzoic acid (Am580) was examined in the MMTV-Myc mouse model of mammary tumorigenesis.

Results: Modulation of the RARα/β to RARγ expression in mammary glands of normal mice, oncomice, and human mammary cell lines through the alteration of RAR-target gene expression affected cell proliferation, survival and tumor growth. Treatment of MMTV-Myc mice with the RARα-selective agonist Am580 led to significant inhibition of mammary tumor growth (~90%, P<0.001), lung metastasis (P<0.01) and extended tumor latency in 63% of mice. Immunocytochemical analysis showed that in these mice, RARα responsive genes such as Cyp26A1, E-cadherin, cellular retinol-binding protein 1 (CRBP1) and p27, were up-regulated. In contrast, the mammary gland tumors of mice that responded poorly to Am580 treatment (37%) expressed significantly higher levels of RARγ. In vitro experiments indicated that the rise in RARγ was functionally linked to promotion of tumor growth and inhibition of differentiation. Thus, activation of the RARα pathway is linked to tumor growth inhibition, differentiation and cell death.

Conclusions: The functional consequence of the interplay between c-Myc oncogene expression and the RARγ to RARα/β balance suggests that prevalence of RARγ over-RARα/β expression levels in breast cancer accompanied by c-Myc amplification or over-expression in breast cancer should be predictive of response to treatment with RARα-isotype-specific agonists and warrant monitoring during clinical trials.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1186/bcr3247DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3680916PMC
August 2012

Ethanol induction of CYP2A5: role of CYP2E1-ROS-Nrf2 pathway.

Toxicol Sci 2012 Aug 2;128(2):427-38. Epub 2012 May 2.

Department of Medicine, Division of Liver Diseases, Mount Sinai School of Medicine New York, New York 10029, USA.

Chronic ethanol consumption was previously shown to induce CYP2A5 in mice, and this induction of CYP2A5 by ethanol was CYP2E1 dependent. In this study, the mechanisms of CYP2E1-dependent ethanol induction of CYP2A5 were investigated. CYP2E1 was induced by chronic ethanol consumption to the same degree in wild-type (WT) mice and CYP2A5 knockout (Cyp2a5 (-/-)) mice, suggesting that unlike the CYP2E1-dependent ethanol induction of CYP2A5, ethanol induction of CYP2E1 is not CYP2A5 dependent. Microsomal ethanol oxidation was about 25% lower in Cyp2a5 (-/-) mice compared with that in WT mice, suggesting that CYP2A5 can oxidize ethanol although to a lesser extent than CYP2E1 does. CYP2A5 was induced by short-term ethanol consumption in human CYP2E1 transgenic knockin (Cyp2e1 (-/-) KI) mice but not in CYP2E1 knockout (Cyp2e1 (-/-)) mice. The redox-sensitive transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) was also induced by acute ethanol in Cyp2e1 (-/-) KI mice but not in Cyp2e1 (-/-) mice. Ethanol induction of CYP2A5 in Nrf2 knockout (Nrf2 (-/-)) mice was lower compared with that in WT mice, whereas CYP2E1 induction by ethanol was comparable in WT and Nrf2 (-/-) mice. Antioxidants (N-acetyl-cysteine and vitamin C), which blocked oxidative stress induced by chronic ethanol in WT mice and acute ethanol in Cyp2e1 (-/-) KI mice, also blunted the induction of CYP2A5 and Nrf2 by ethanol but not the induction of CYP2E1 by ethanol. These results suggest that oxidative stress induced by ethanol via induction of CYP2E1 upregulates Nrf2 activity, which in turn regulates ethanol induction of CYP2A5. Results obtained from primary hepatocytes, mice gavaged with binge ethanol or fed chronic ethanol, show that Nrf2-regulated ethanol induction of CYP2A5 protects against ethanol-induced steatosis.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/toxsci/kfs164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3493190PMC
August 2012

Argininosuccinate synthase conditions the response to acute and chronic ethanol-induced liver injury in mice.

Hepatology 2012 05;55(5):1596-1609

Division of Liver Diseases, Department of Medicine, Mount Sinai School of Medicine, Box 1123, 1425 Madison Avenue, Room 11-76, New York, NY 10029, USA.

Unlabelled: Argininosuccinate synthase (ASS) is the rate-limiting enzyme in both the urea and the L-citrulline/nitric oxide (NO·) cycles regulating protein catabolism, ammonia levels, and NO· generation. Because a proteomics analysis identified ASS and nitric oxide synthase-2 (NOS2) as coinduced in rat hepatocytes by chronic ethanol consumption, which also occurred in alcoholic liver disease (ALD) and in cirrhosis patients, we hypothesized that ASS could play a role in ethanol binge and chronic ethanol-induced liver damage. To investigate the contribution of ASS to the pathophysiology of ALD, wildtype (WT) and Ass(+/-) mice (Ass(-/-) are lethal due to hyperammonemia) were exposed to an ethanol binge or to chronic ethanol drinking. Compared with WT, Ass(+/-) mice given an ethanol binge exhibited decreased steatosis, lower NOS2 induction, and less 3-nitrotyrosine (3-NT) protein residues, indicating that reducing nitrosative stress by way of the L-citrulline/NO· pathway plays a significant role in preventing liver damage. However, chronic ethanol-treated Ass(+/-) mice displayed enhanced liver injury compared with WT mice. This was due to hyperammonemia, lower phosphorylated AMP-activated protein kinase alpha (pAMPKα) to total AMPKα ratio, decreased sirtuin-1 (Sirt-1) and peroxisomal proliferator-activated receptor coactivator-1α (Pgc1α) messenger RNAs (mRNAs), lower fatty acid β-oxidation due to down-regulation of carnitine palmitoyl transferase-II (CPT-II), decreased antioxidant defense, and elevated lipid peroxidation end-products in spite of comparable nitrosative stress but likely reduced NOS3.

Conclusion: Partial Ass ablation protects only in acute ethanol-induced liver injury by decreasing nitrosative stress but not in a more chronic scenario where oxidative stress and impaired fatty acid β-oxidation are key events.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/hep.25543DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4632528PMC
May 2012