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Wickramasinghe PB, Qian S, Langley LE, Liu C, Jia L. Hepatocyte Toll-Like Receptor 4 Mediates Alcohol-Induced Insulin Resistance in Mice. Biomolecules 2023; 13:454. [PMID: 36979389 PMCID: PMC10046504 DOI: 10.3390/biom13030454] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/20/2023] [Accepted: 02/25/2023] [Indexed: 03/06/2023] Open
Abstract
Accumulating evidence has demonstrated the association between alcohol overconsumption and the development of insulin resistance. However, the underlying mechanisms are not completely understood. To investigate the requirement and sufficiency of hepatocyte toll-like receptor 4 (TLR4) in alcohol-induced insulin resistance, we used two mouse models (Tlr4fl/fl and Tlr4LoxTB) that allow ablation of TLR4 only in hepatocytes (Tlr4LKO) and restoration of endogenous TLR4 expression in hepatocytes on a TLR4-null background (Tlr4LoxTB × Alb-Cre), respectively. A Lieber-DeCarli feeding model was used to induce glucose intolerance and insulin resistance in mice. Glucose tolerance test, insulin tolerance test, and insulin signaling experiments were performed to examine systemic and tissue-specific insulin sensitivity. We found that alcohol-fed hepatocyte TLR4 deficient mice (Tlr4LKO) had lower blood glucose levels in response to intraperitoneal injection of insulin. Moreover, increased phosphorylation of glycogen synthase kinase-3β (GSK3β) was observed in the liver of Tlr4LKO mice after chronic alcohol intake. In contrast, when hepatic TLR4 was reactivated in mice (Tlr4LoxTB × Alb-Cre), alcohol feeding caused glucose intolerance in these mice compared with littermate controls (Tlr4LoxTB). In addition, AKT phosphorylation was dramatically reduced in the liver and epididymal white adipose tissue (eWAT) of alcohol-fed Tlr4LoxTB × Alb-Cre mice, which was similar to that of mice with whole-body TLR4 reactivation (Tlr4LoxTB × Zp3-Cre). Collectively, these findings suggest that hepatocyte TLR4 is both required and sufficient in the development of insulin resistance induced by alcohol overconsumption.
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Affiliation(s)
- Piumi B. Wickramasinghe
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Shuwen Qian
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lyndsey E. Langley
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080, USA
| | - Chen Liu
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lin Jia
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX 75080, USA
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Tong M, Ziplow JL, Mark P, de la Monte SM. Dietary Soy Prevents Alcohol-Mediated Neurocognitive Dysfunction and Associated Impairments in Brain Insulin Pathway Signaling in an Adolescent Rat Model. Biomolecules 2022; 12:676. [PMID: 35625605 PMCID: PMC9139005 DOI: 10.3390/biom12050676] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 05/04/2022] [Accepted: 05/05/2022] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Alcohol-related brain degeneration is linked to cognitive-motor deficits and impaired signaling through insulin/insulin-like growth factor type 1 (IGF-1)-Akt pathways that regulate cell survival, plasticity, metabolism, and homeostasis. In addition, ethanol inhibits Aspartyl-asparaginyl-β-hydroxylase (ASPH), a downstream target of insulin/IGF-1-Akt signaling and an activator of Notch networks. Previous studies have suggested that early treatment with insulin sensitizers or dietary soy could reduce or prevent the long-term adverse effects of chronic ethanol feeding. OBJECTIVE The goal of this study was to assess the effects of substituting soy isolate for casein to prevent or reduce ethanol's adverse effects on brain structure and function. METHODS Young adolescent male and female Long Evans were used in a 4-way model as follows: Control + Casein; Ethanol + Casein; Control + Soy; Ethanol + Soy; Control = 0% ethanol; Ethanol = 26% ethanol (caloric). Rats were fed isocaloric diets from 4 to 11 weeks of age. During the final experimental week, the Morris Water maze test was used to assess spatial learning (4 consecutive days), after which the brains were harvested to measure the temporal lobe expression of the total phospho-Akt pathway and downstream target proteins using multiplex bead-based enzyme-linked immunosorbent assays (ELISAs) and duplex ELISAs. RESULTS Ethanol inhibited spatial learning and reduced brain weight, insulin signaling through Akt, and the expression of ASPH when standard casein was provided as the protein source. The substitution of soy isolate for casein largely abrogated the adverse effects of chronic ethanol feeding. In contrast, Notch signaling protein expression was minimally altered by ethanol or soy isolate. CONCLUSIONS These novel findings suggest that the insulin sensitizer properties of soy isolate may prevent some of the adverse effects that chronic ethanol exposure has on neurobehavioral function and insulin-regulated metabolic pathways in adolescent brains.
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Affiliation(s)
- Ming Tong
- Liver Research Center, Division of Gastroenterology, Department of Medicine, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI 02808, USA; (M.T.); (J.L.Z.); (P.M.)
| | - Jason L. Ziplow
- Liver Research Center, Division of Gastroenterology, Department of Medicine, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI 02808, USA; (M.T.); (J.L.Z.); (P.M.)
| | - Princess Mark
- Liver Research Center, Division of Gastroenterology, Department of Medicine, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, RI 02808, USA; (M.T.); (J.L.Z.); (P.M.)
| | - Suzanne M. de la Monte
- Liver Research Center, Division of Gastroenterology, Departments of Medicine, Neurology and Pathology and Laboratory Medicine, Rhode Island Hospital, Providence, RI 02808, USA
- Women and Infants Hospital of Rhode Island, Alpert Medical School of Brown University, Providence VA Medical Center, Providence, RI 02808, USA
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Betaine Supplementation Causes an Increase in Fatty Acid Oxidation and Carbohydrate Metabolism in Livers of Mice Fed a High-Fat Diet: A Proteomic Analysis. Foods 2022; 11:foods11060881. [PMID: 35327303 PMCID: PMC8949908 DOI: 10.3390/foods11060881] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/04/2022] [Accepted: 03/15/2022] [Indexed: 11/16/2022] Open
Abstract
Betaine, a common methyl donor whose methylation is involved in the biosynthesis of carnitine and phospholipids in animals, serves as food and animal feed additive. The present study used liquid chromatography-mass spectrometry (LC-MS) to analyze the liver protein profile of mice on a high fat (HF) diet to investigate the mechanism by which betaine affects hepatic metabolism. Although betaine supplementation had no significant effect on body weight, a total of 103 differentially expressed proteins were identified between HF diet + 1% betaine group (HFB) and HF diet group by LC-MS (fold change > 2, p < 0.05). The addition of 1% betaine had a significant enhancement of the expression of enzymes related to fatty acid oxidation metabolism, such as hydroxyacyl-Coenzyme A dehydrogenase (HADHA), enoyl Coenzyme A hydratase 1 (ECHS1) (p < 0.05) etc., and the expression of apolipoprotein A-II (APOA2) protein was significantly reduced (p < 0.01). Meanwhile, the protein expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and succinate-CoA ligase (SUCLG1) were highly significant (p < 0.01). Pathway enrichment using the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that the functions of differential proteins involved fatty acid catabolism, carbohydrate metabolism, tricarboxylic acid cycle (TCA) and peroxisome proliferator-activated receptor alpha (PPARα) signaling pathway. Protein−protein interaction (PPI) analysis discovered that acetyl-Coenzyme A acetyltransferase 1 (ACAT1), HADHA and ECHS1 were central hubs of hepatic proteomic changes in the HFB group of mice. Betaine alleviates hepatic lipid accumulation by enhancing fatty acid oxidation and accelerating the TCA cycle and glycolytic process in the liver of mice on an HF diet.
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Koga T, Peters JM. Targeting Peroxisome Proliferator-Activated Receptor-β/δ (PPARβ/δ) for the Treatment or Prevention of Alcoholic Liver Disease. Biol Pharm Bull 2021; 44:1598-1606. [PMID: 34719638 DOI: 10.1248/bpb.b21-00486] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Excessive, chronic alcohol consumption can lead to alcoholic liver disease. The etiology of alcoholic liver disease is multifactorial and is influenced by alterations in gene expression and changes in fatty acid metabolism, oxidative stress, and insulin resistance. These events can lead to steatosis, fibrosis, and eventually to cirrhosis and liver cancer. Many of these functions are regulated by peroxisome proliferator-activated receptors (PPARs). Thus, it is not surprising that PPARs can modulate the mechanisms that cause alcoholic liver disease. While the roles of PPARα and PPARγ are clearer, the role of PPARβ/δ in alcoholic liver disease requires further clarification. This review summarizes the current understanding based on recent studies that indicate that PPARβ/δ can likely be targeted for the treatment and/or the prevention of alcoholic liver disease.
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Affiliation(s)
- Takayuki Koga
- Laboratory of Hygienic Chemistry, Department of Health Science and Hygiene, Daiichi University of Pharmacy
| | - Jeffrey M Peters
- Department of Veterinary and Biomedical Sciences and the Center of Molecular Toxicology and Carcinogenesis, The Pennsylvania State University
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Nikolova-Karakashian M. Alcoholic and non-alcoholic fatty liver disease: Focus on ceramide. Adv Biol Regul 2018; 70:40-50. [PMID: 30455063 DOI: 10.1016/j.jbior.2018.11.004] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/13/2018] [Accepted: 11/13/2018] [Indexed: 12/24/2022]
Abstract
Sphingolipids are class of metabolically distinct lipids that play structural and signaling functions in all organisms. Sphingolipid metabolism is deregulated during various diseases such as cancer, neurological and immune disorders, and metabolic syndrome. With the advancement of sphingo-lipidomics and sphingo-genomics, an understanding of the specific roles of ceramide, the quintessential bioactive sphingolipid, in fatty liver disease has taken shape. Two major pathways for ceramide generation, the de novo pathway and the sphingomyelinase pathway are activated in the course of both, the non-alcoholic and the alcoholic, forms of fatty liver disease. The mechanisms of activation of these two pathways are distinct and reflect the different disease etiology in each case; at the same time, common processes impacted by the resulting ceramide overproduction involve lipotoxocity, ER/mitochondrial stress, inflammation, and de-regulation of hepatic lipid metabolism. Studies in human patients and animal models have delineated specific enzymes and ceramide species that are involved at the different stages of the disease, and represent novel pharmaceutical targets for successful management of fatty liver disease.
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Affiliation(s)
- Mariana Nikolova-Karakashian
- Department of Physiology, University of Kentucky College of Medicine, 800 Rose Str., MS 508, Lexington, KY, 40536, United States.
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The role of sphingolipids in psychoactive drug use and addiction. J Neural Transm (Vienna) 2018; 125:651-672. [DOI: 10.1007/s00702-018-1840-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 01/03/2018] [Indexed: 12/14/2022]
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Abstract
Adipose tissue represents a large volume of biologically active tissue that exerts substantial systemic effects in health and disease. Alcohol consumption can profoundly disturb the normal functions of adipose tissue by inducing adipocyte death and altering secretion of adipokines, pro-inflammatory mediators and free fatty acids from adipose tissue, which have important direct and indirect effects on the pathogenesis of alcoholic liver disease (ALD). Cessation of alcohol intake quickly reverses inflammatory changes in adipose tissue, and pharmacological treatment that normalizes adipose tissue function improves experimental ALD. Obesity exacerbates liver injury induced by chronic or binge alcohol consumption, and obesity and alcohol can synergize to increase risk of ALD and progression. Physicians who care for individuals with ALD should be aware of the effects of adipose tissue dysfunction on liver function, and consider strategies to manage obesity and insulin resistance. This Review examines the effect of alcohol on adiposity and adipose tissue and the relationship between alcohol, adipose tissue and the liver.
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Tong M, Gonzalez-Navarrete H, Kirchberg T, Gotama B, Yalcin EB, Kay J, de la Monte SM. Ethanol-Induced White Matter Atrophy Is Associated with Impaired Expression of Aspartyl-Asparaginyl- β-Hydroxylase (ASPH) and Notch Signaling in an Experimental Rat Model. JOURNAL OF DRUG AND ALCOHOL RESEARCH 2017; 6:236033. [PMID: 29204305 PMCID: PMC5711436 DOI: 10.4303/jdar/236033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Alcohol-induced white matter (WM) degeneration is linked to cognitive-motor deficits and impairs insulin/insulin-like growth factor (IGF) and Notch networks regulating oligodendrocyte function. Ethanol downregulates Aspartyl-Asparaginyl-β-Hydroxylase (ASPH) which drives Notch. These experiments determined if alcohol-related WM degeneration was linked to inhibition of ASPH and Notch. Adult Long Evans rats were fed for 3, 6 or 8 weeks with liquid diets containing 26% ethanol (caloric) and in the last two weeks prior to each endpoint they were binged with 2 g/kg ethanol, 3×/week. Controls were studied in parallel. Histological sections of the frontal lobe and cerebellar vermis were used for image analysis. Frontal WM proteins were used for Western blotting and duplex ELISAs. The ethanol exposures caused progressive reductions in frontal and cerebellar WM. Ethanol-mediated frontal WM atrophy was associated with reduced expression of ASPH, Jagged 1, HES-1, and HIF-1α. These findings link ethanol-induced WM atrophy to inhibition of ASPH expression and signaling through Notch networks, including HIF-1α.
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Affiliation(s)
- Ming Tong
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
- Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | | | | | - Billy Gotama
- Molecular Pharmacology and Biotechnology Graduate Program, Brown University, Providence, RI 02912, USA
- Brown University, Providence, RI 02912, USA
| | - Emine B. Yalcin
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
- Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Jared Kay
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Suzanne M. de la Monte
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
- Departments of Neurology, Neurosurgery, and Pathology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
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Tong M, Gao JS, Borgas D, de la Monte SM. Phosphorylation Modulates Aspartyl-(Asparaginyl)-β Hydroxylase Protein Expression, Catalytic Activity and Migration in Human Immature Neuronal Cerebellar Cells. ACTA ACUST UNITED AC 2017; 6. [PMID: 29607347 DOI: 10.4172/2324-9293.1000133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Background Abundant aspartyl-asparaginyl-β-hydroxylase (ASPH) expression supports robust neuronal migration during development, and reduced ASPH expression and function, as occur in fetal alcohol spectrum disorder, impair cerebellar neuron migration. ASPH mediates its effects on cell migration via hydroxylation-dependent activation of Notch signaling networks. Insulin and Insulin-like growth factor (IGF-1) stimulate ASPH mRNA transcription and enhance ASPH protein expression by inhibiting Glycogen Synthase Kinase-3β (GSK-3β). This study examines the role of direct GSK-3β phosphorylation as a modulator of ASPH protein expression and function in human cerebellar-derived PNET2 cells. Methods Predicted phosphorylation sites encoded by human ASPH were ablated by S/T→A site-directed mutagenesis of an N-Myc-tagged wildtype (WT) cDNA regulated by a CMV promoter. Phenotypic and functional features were assessed in transiently transfected PNET2 cells. Results Cells transfected with WT ASPH had increased ASPH protein expression, directional motility, Notch-1 and Jagged-1 expression, and catalytic activity relative to control. Although most single- and multi-point ASPH mutants also had increased ASPH protein expression, their effects on Notch and Jagged expression, directional motility and adhesion, and catalytic activity varied such that only a few of the cDNA constructs conferred functional advantages over WT. Immunofluorescence studies showed that ASPH phosphorylation site deletions can alter the subcellular distribution of ASPH and therefore its potential interactions with Notch/Jagged at the cell surface. Conclusions Inhibition of ASPH phosphorylation enhances ASPH protein expression, but attendant alterations in intra-cellular trafficking may govern the functional consequences in relation to neuronal migration, adhesion and Notch activated signaling.
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Affiliation(s)
- Ming Tong
- Liver Research Center, Divisions of Gastroenterology and Neuropathology, and Departments of Medicine, Pathology (Neuropathology), Neurology, and Neurosurgery, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI and the Molecular Pharmacology and Physiology Graduate Program, Brown University, Providence, RI, USA
| | - Jin-Song Gao
- Liver Research Center, Divisions of Gastroenterology and Neuropathology, and Departments of Medicine, Pathology (Neuropathology), Neurology, and Neurosurgery, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI and the Molecular Pharmacology and Physiology Graduate Program, Brown University, Providence, RI, USA
| | - Diana Borgas
- Liver Research Center, Divisions of Gastroenterology and Neuropathology, and Departments of Medicine, Pathology (Neuropathology), Neurology, and Neurosurgery, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI and the Molecular Pharmacology and Physiology Graduate Program, Brown University, Providence, RI, USA
| | - Suzanne M de la Monte
- Liver Research Center, Divisions of Gastroenterology and Neuropathology, and Departments of Medicine, Pathology (Neuropathology), Neurology, and Neurosurgery, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI and the Molecular Pharmacology and Physiology Graduate Program, Brown University, Providence, RI, USA
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Sugimoto K, Takei Y. Pathogenesis of alcoholic liver disease. Hepatol Res 2017; 47:70-79. [PMID: 27138729 DOI: 10.1111/hepr.12736] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 04/26/2016] [Accepted: 04/29/2016] [Indexed: 02/06/2023]
Abstract
Alcoholic liver disease (ALD) has become one of the most critical health problems in many countries, including Japan. Liver injury in ALD ranges from steatosis and steatohepatitis to fibrosis, cirrhosis, and hepatocellular carcinoma. Many factors are thought to contribute to the development and progression of ALD, particularly insulin resistance, generation of reactive oxygen species during alcohol metabolism, adipokines from visceral adipose tissue, and endotoxin derived from the gut. Although the pathogenesis of ALD has been widely investigated, the precise mechanisms are yet to be elucidated and many questions remain. This article reviews the possible mechanisms for the development of ALD identified to date.
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Affiliation(s)
- Kazushi Sugimoto
- Department of Gastroenterology and Hepatology, Mie University School of Medicine, Tsu, Mie, Japan
| | - Yoshiyuki Takei
- Department of Gastroenterology and Hepatology, Mie University School of Medicine, Tsu, Mie, Japan
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Deochand C, Tong M, Agarwal AR, Cadenas E, de la Monte SM. Tobacco Smoke Exposure Impairs Brain Insulin/IGF Signaling: Potential Co-Factor Role in Neurodegeneration. J Alzheimers Dis 2016; 50:373-86. [PMID: 26682684 DOI: 10.3233/jad-150664] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Human studies suggest tobacco smoking is a risk factor for cognitive impairment and neurodegeneration, including Alzheimer's disease (AD). However, experimental data linking tobacco smoke exposures to underlying mediators of neurodegeneration, including impairments in brain insulin and insulin-like growth factor (IGF) signaling in AD are lacking. OBJECTIVE This study tests the hypothesis that cigarette smoke (CS) exposures can impair brain insulin/IGF signaling and alter expression of AD-associated proteins. METHODS Adult male A/J mice were exposed to air for 8 weeks (A8), CS for 4 or 8 weeks (CS4, CS8), or CS8 followed by 2 weeks recovery (CS8+R). Gene expression was measured by qRT-PCR analysis and proteins were measured by multiplex bead-based or direct binding duplex ELISAs. RESULTS CS exposure effects on insulin/IGF and insulin receptor substrate (IRS) proteins and phosphorylated proteins were striking compared with the mRNA. The main consequences of CS4 or CS8 exposures were to significantly reduce insulin R, IGF-1R, IRS-1, and tyrosine phosphorylated insulin R and IGF-1R proteins. Paradoxically, these effects were even greater in the CS8+R group. In addition, relative levels of S312-IRS-1, which inhibits downstream signaling, were increased in the CS4, CS8, and CS8+R groups. Correspondingly, CS and CS8+R exposures inhibited expression of proteins and phosphoproteins required for signaling through Akt, PRAS40, and/or p70S6K, increased AβPP-Aβ, and reduced ASPH protein, which is a target of insulin/IGF-1 signaling. CONCLUSION Secondhand CS exposures caused molecular and biochemical abnormalities in brain that overlap with the findings in AD, and many of these effects were sustained or worsened despite short-term CS withdrawal.
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Affiliation(s)
- Chetram Deochand
- Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Divisions of Gastroenterology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Ming Tong
- Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Divisions of Gastroenterology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Amit R Agarwal
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, USA
| | - Enrique Cadenas
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, USA
| | - Suzanne M de la Monte
- Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Divisions of Gastroenterology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Divisions of Neuropathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Pathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Neurology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.,Department of Neurosurgery, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
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Liver-Specific Deletion of Phosphatase and Tensin Homolog Deleted on Chromosome 10 Significantly Ameliorates Chronic EtOH-Induced Increases in Hepatocellular Damage. PLoS One 2016; 11:e0154152. [PMID: 27124661 PMCID: PMC4849752 DOI: 10.1371/journal.pone.0154152] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 04/08/2016] [Indexed: 12/20/2022] Open
Abstract
Alcoholic liver disease is a significant contributor to global liver failure. In murine models, chronic ethanol consumption dysregulates PTEN/Akt signaling. Hepatospecific deletion of phosphatase and tensin homolog deleted on chromosome 10 (PTENLKO) mice possess constitutive activation of Akt(s) and increased de novo lipogenesis resulting in increased hepatocellular steatosis. This makes PTENLKO a viable model to examine the effects of ethanol in an environment of preexisting steatosis. The aim of this study was to determine the impact of chronic ethanol consumption and the absence of PTEN (PTENLKO) compared to Alb-Cre control mice (PTENf/f) on hepatocellular damage as evidenced by changes in lipid accumulation, protein carbonylation and alanine amino transferase (ALT). In the control PTENf/f animals, ethanol significantly increased ALT, liver triglycerides and steatosis. In contrast, chronic ethanol consumption in PTENLKO mice decreased hepatocellular damage when compared to PTENLKO pair-fed controls. Consumption of ethanol elevated protein carbonylation in PTENf/f animals but had no effect in PTENLKO animals. In PTENLKO mice, overall hepatic mRNA expression of genes that contribute to GSH homeostasis as well as reduced glutathione (GSH) and oxidized glutathione (GSSG) concentrations were significantly elevated compared to respective PTENf/f counterparts. These data indicate that during conditions of constitutive Akt activation and steatosis, increased GSH homeostasis assists in mitigation of ethanol-dependent induction of oxidative stress and hepatocellular damage. Furthermore, data herein suggest a divergence in EtOH-induced hepatocellular damage and increases in steatosis due to polyunsaturated fatty acids downstream of PTEN.
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de la Monte SM, Tong M, Agarwal AR, Cadenas E. Tobacco Smoke-Induced Hepatic Injury with Steatosis, Inflammation, and Impairments in Insulin and Insulin-Like Growth Factor Signaling. ACTA ACUST UNITED AC 2016; 6. [PMID: 27525191 PMCID: PMC4979551 DOI: 10.4172/2161-0681.1000269] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Background Alcoholic liver disease (ALD) is associated with impairments in hepatic insulin and insulin-like growth factor (IGF) signaling through cell growth, survival, and metabolic pathways. Since not all heavy drinkers develop ALD, co-factors may be important. Epidemiologic data indicate that most heavy drinkers smoke tobacco and experimental data revealed that low-level nitrosamine exposures, including those from tobacco, can cause steatohepatitis with hepatic insulin/IGF resistance and exacerbate ALD. We hypothesize that cigarette smoke (CS) exposures also cause liver injury with impaired hepatic insulin/IGF signaling, and thereby contribute to ALD. Methods Adult male A/J mice were exposed to air for 8 weeks (A8), CS for 4 (CS4) or 8 (CS8) weeks, or CS for 8 weeks with 2 weeks recovery (CS8+R). Results CS exposures caused progressive liver injury with disruption of the normal hepatic chord architecture, lobular inflammation, apoptosis or necrosis, micro-steatosis, sinusoidal dilatation, and nuclear pleomorphism. Histopathological liver injury scores increased significantly from A8 to CS4 and then further to CS8 (P<0.0001). The mean histological grade was also higher in CS8+R relative to A8 (P<0.0001) but lower than in CS4, reflecting partial resolution of injury by CS withdrawal. CS exposures impaired insulin and IGF-1 signaling through IRS-1, Akt, GSK-3β, and PRAS40. Livers from CS8+R mice had normalized or elevated levels of insulin receptor, pYpY-Insulin-R, 312S-IRS-1, 473S-Akt, S9-GSK-3β, and pT246-PRAS40 relative to A8, CS4, or CS8, reflecting partial recovery. Conclusion CS-mediated liver injury and steatohepatitis with impairments in insulin/IGF signalling are reminiscent of the findings in ALD. Therefore, CS exposures (either first or second-hand) may serve as a co-factor in ALD. The persistence of several abnormalities following CS exposure cessation suggests that some aspects of CS-mediated hepatic metabolic dysfunction are not readily reversible.
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Affiliation(s)
- Suzanne M de la Monte
- Liver Research Center, Department of Medicine, Rhode Island Hospital and the Alpert Medical School of Brown University, USA; Division of Neuropathology and Departments of Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and the Alpert Medical School of Brown University, USA
| | - M Tong
- Liver Research Center, Department of Medicine, Rhode Island Hospital and the Alpert Medical School of Brown University, USA
| | - A R Agarwal
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, USA
| | - E Cadenas
- Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Southern California, Los Angeles, CA, USA
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Andreani T, Tong M, Gundogan F, Silbermann E, de la Monte SM. Differential Effects of 3rd Trimester-Equivalent Binge Ethanol and Tobacco-Specific Nitrosamine Ketone Exposures on Brain Insulin Signaling in Adolescence. JOURNAL OF DIABETES AND RELATED DISORDERS 2016; 1:105. [PMID: 29242853 PMCID: PMC5726776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND Fetal alcohol spectrum disorder (FASD) is associated with impairments in insulin and insulin-like growth factor (IGF) signaling through Akt pathways and altered expression of neuro-glial proteins needed for structural and functional integrity of the brain. However, alcohol abuse correlates with smoking, and tobacco smoke contains 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), which like other nitrosamines, impairs insulin and IGF signaling. HYPOTHESIS NNK exposure can serve as a co-factor in mediating long-term neuro-developmental abnormalities associated with FASD. DESIGN Long Evans rat pups were IP administered ethanol (2 g/kg) on postnatal days (P) 2, 4, 6 and/or NNK (2 mg/kg) on P3, P5, and P7, simulating third trimester human exposures. Temporal lobes from P30 rats (young adolescent) were used to measure signaling through the insulin/IGF-1/Akt pathways by multiplex ELISAs, and expression of neuroglial proteins by duplex ELISAs. RESULTS Ethanol, NNK, and ethanol + NNK exposures significantly inhibited insulin receptor tyrosine phosphorylation, and IRS-1 and myelin-associated glycoprotein expression. However, the major long-term adverse effects on Akt pathway downstream signaling and its targeted proteins including choline acetyltransferase, Tau, pTau, ubiquitin, and aspartate-β-hydroxylase were due to NNK rather than ethanol. CONCLUSION Alcohol and tobacco exposures can both contribute to long-term brain abnormalities currently regarded fetal ethanol effects. However, the findings suggest that many of the adverse effects on brain function are attributable to smoking, including impairments in signaling through survival and metabolic pathways, and altered expression of genes that regulate myelin synthesis, maturation and integrity and synaptic plasticity. Therefore, public health measures should address both substances of abuse to prevent "FASD".
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Affiliation(s)
- Tomas Andreani
- Department of Medicine, Division of Gastroenterology, and the Liver
Research Center Rhode Island Hospital, Providence, RI, USA
| | - Ming Tong
- Department of Medicine, Division of Gastroenterology, and the Liver
Research Center Rhode Island Hospital, Providence, RI, USA
- Warren Alpert Medical School of Brown University, Providence, RI,
USA
| | - Fusun Gundogan
- Department of Pathology, Women and Infants Hospital of Rhode Island,
Providence, RI, USA
- Warren Alpert Medical School of Brown University, Providence, RI,
USA
| | | | - Suzanne M. de la Monte
- Department of Medicine, Division of Gastroenterology, and the Liver
Research Center Rhode Island Hospital, Providence, RI, USA
- Departments of Pathology and Neurology, and the Division of
Neuropathology, Rhode Island Hospital, Providence, RI, USA
- Warren Alpert Medical School of Brown University, Providence, RI,
USA
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15
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High Intrinsic Aerobic Capacity Protects against Ethanol-Induced Hepatic Injury and Metabolic Dysfunction: Study Using High Capacity Runner Rat Model. Biomolecules 2015; 5:3295-308. [PMID: 26610588 PMCID: PMC4693279 DOI: 10.3390/biom5043295] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2015] [Accepted: 11/10/2015] [Indexed: 01/12/2023] Open
Abstract
Rats artificially selected over several generations for high intrinsic endurance/aerobic capacity resulting in high capacity runners (HCR) has been developed to study the links between high aerobic fitness and protection from metabolic diseases (Wisloff et al., Science, 2005). We have previously shown that the HCR strain have elevated hepatic mitochondrial content and oxidative capacity. In this study, we tested if the elevated hepatic mitochondrial content in the HCR rat would provide "metabolic protection" from chronic ethanol-induced hepatic steatosis and injury. The Leiber-Decarli liquid diet with ethanol (7% v/v; HCR-E) and without (HCR-C) was given to HCR rats (n = 8 per group) from 14 to 20 weeks of age that were weight matched and pair-fed to assure isocaloric intake. Hepatic triglyceride (TG) content and macro- and microvesicular steatosis were significantly greater in HCR-E compared with HCR-C (p < 0.05). In addition, hepatic superoxide dismutase activity and glutathione levels were significantly (p < 0.05) reduced in the HCR-E rats. This hepatic phenotype also was associated with reduced total hepatic fatty acid oxidation (p = 0.03) and β-hydroxyacyl-CoA dehydrogenase activity (p = 0.01), and reductions in microsomal triglyceride transfer protein and apoB-100 protein content (p = 0.01) in HCR-E animals. However, despite these documented hepatic alterations, ethanol ingestion failed to induce significant hepatic liver injury, including no changes in hepatic inflammation, or serum alanine amino transferase (ALTs), free fatty acids (FFAs), triglycerides (TGs), insulin, or glucose. High intrinsic aerobic fitness did not reduce ethanol-induced hepatic steatosis, but protected against ethanol-induced hepatic injury and systemic metabolic dysfunction in a high aerobic capacity rat model.
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16
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Godfrey J, Jeanguenin L, Castro N, Olney JJ, Dudley J, Pipkin J, Walls SM, Wang W, Herr DR, Harris GL, Brasser SM. Chronic Voluntary Ethanol Consumption Induces Favorable Ceramide Profiles in Selectively Bred Alcohol-Preferring (P) Rats. PLoS One 2015; 10:e0139012. [PMID: 26405804 PMCID: PMC4583526 DOI: 10.1371/journal.pone.0139012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 09/07/2015] [Indexed: 12/20/2022] Open
Abstract
Heavy alcohol consumption has detrimental neurologic effects, inducing widespread neuronal loss in both fetuses and adults. One proposed mechanism of ethanol-induced cell loss with sufficient exposure is an elevation in concentrations of bioactive lipids that mediate apoptosis, including the membrane sphingolipid metabolites ceramide and sphingosine. While these naturally-occurring lipids serve as important modulators of normal neuronal development, elevated levels resulting from various extracellular insults have been implicated in pathological apoptosis of neurons and oligodendrocytes in several neuroinflammatory and neurodegenerative disorders. Prior work has shown that acute administration of ethanol to developing mice increases levels of ceramide in multiple brain regions, hypothesized to be a mediator of fetal alcohol-induced neuronal loss. Elevated ceramide levels have also been implicated in ethanol-mediated neurodegeneration in adult animals and humans. Here, we determined the effect of chronic voluntary ethanol consumption on lipid profiles in brain and peripheral tissues from adult alcohol-preferring (P) rats to further examine alterations in lipid composition as a potential contributor to ethanol-induced cellular damage. P rats were exposed for 13 weeks to a 20% ethanol intermittent-access drinking paradigm (45 ethanol sessions total) or were given access only to water (control). Following the final session, tissues were collected for subsequent chromatographic analysis of lipid content and enzymatic gene expression. Contrary to expectations, ethanol-exposed rats displayed substantial reductions in concentrations of ceramides in forebrain and heart relative to non-exposed controls, and modest but significant decreases in liver cholesterol. qRT-PCR analysis showed a reduction in the expression of sphingolipid delta(4)-desaturase (Degs2), an enzyme involved in de novo ceramide synthesis. These findings indicate that ethanol intake levels achieved by alcohol-preferring P rats as a result of chronic voluntary exposure may have favorable vs. detrimental effects on lipid profiles in this genetic line, consistent with data supporting beneficial cardioprotective and neuroprotective effects of moderate ethanol consumption.
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Affiliation(s)
- Jessica Godfrey
- Department of Psychology, San Diego State University, San Diego, California, United States of America
| | - Lisa Jeanguenin
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Norma Castro
- Department of Psychology, San Diego State University, San Diego, California, United States of America
| | - Jeffrey J. Olney
- Department of Psychology, San Diego State University, San Diego, California, United States of America
| | - Jason Dudley
- Department of Psychology, San Diego State University, San Diego, California, United States of America
| | - Joseph Pipkin
- Department of Psychology, San Diego State University, San Diego, California, United States of America
| | - Stanley M. Walls
- Department of Biology, San Diego State University, San Diego, California, United States of America
| | - Wei Wang
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Deron R. Herr
- Department of Biology, San Diego State University, San Diego, California, United States of America
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Greg L. Harris
- Department of Biology, San Diego State University, San Diego, California, United States of America
- * E-mail: (SMB); (GLH)
| | - Susan M. Brasser
- Department of Psychology, San Diego State University, San Diego, California, United States of America
- * E-mail: (SMB); (GLH)
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17
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Tong M, Yu R, Deochand C, de la Monte SM. Differential Contributions of Alcohol and the Nicotine-Derived Nitrosamine Ketone (NNK) to Insulin and Insulin-Like Growth Factor Resistance in the Adolescent Rat Brain. Alcohol Alcohol 2015; 50:670-9. [PMID: 26373814 DOI: 10.1093/alcalc/agv101] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 08/17/2015] [Indexed: 12/11/2022] Open
Abstract
AIMS Since epidemiologic studies suggest that tobacco smoke toxins, e.g. the nicotine-derived nitrosamine ketone (NNK) tobacco-specific nitrosamine, can be a co-factor in alcohol-related brain disease (ARBD), we examined the independent and additive effects of alcohol and NNK exposures on spatial learning/memory, and brain insulin/IGF signaling, neuronal function and oxidative stress. METHODS Adolescent Long Evans rats were fed liquid diets containing 0 or 26% caloric ethanol for 8 weeks. During weeks 3-8, rats were treated with i.p. NNK (2 mg/kg, 3×/week) or saline. In weeks 7-8, ethanol groups were binge-administered ethanol (2 g/kg; 3×/week). In week 8, at 12 weeks of age, rats were subjected to Morris Water Maze tests. Temporal lobes were used to assess molecular indices of insulin/IGF resistance, oxidative stress and neuronal function. RESULTS Ethanol and NNK impaired spatial learning, and NNK ± ethanol impaired memory. Linear trend analysis demonstrated worsening performance from control to ethanol, to NNK, and then ethanol + NNK. Ethanol ± NNK, caused brain atrophy, inhibited insulin signaling through the insulin receptor and Akt, activated GSK-3β, increased protein carbonyl and 3-nitrotyrosine, and reduced acetylcholinesterase. NNK increased NTyr. Ethanol + NNK had synergistic stimulatory effects on 8-iso-PGF-2α, inhibitory effects on p-p70S6K, tau and p-tau and trend effects on insulin-like growth factor type 1 (IGF-1) receptor expression and phosphorylation. CONCLUSIONS Ethanol, NNK and combined ethanol + NNK exposures that begin in adolescence impair spatial learning and memory in young adults. The ethanol and/or NNK exposures differentially impair insulin/IGF signaling through neuronal growth, survival and plasticity pathways, increase cellular injury and oxidative stress and reduce expression of critical proteins needed for neuronal function.
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Affiliation(s)
- Ming Tong
- Department of Medicine, Division of Gastroenterology, and the Liver Research Center, Rhode Island Hospital, Providence, RI, USA Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Rosa Yu
- Departments of Pathology and Neurology, and the Division of Neuropathology, Rhode Island Hospital, Providence, RI, USA
| | - Chetram Deochand
- Biotechnology Graduate Program, Brown University, Providence, RI, USA
| | - Suzanne M de la Monte
- Department of Medicine, Division of Gastroenterology, and the Liver Research Center, Rhode Island Hospital, Providence, RI, USA Warren Alpert Medical School of Brown University, Providence, RI, USA Departments of Pathology and Neurology, and the Division of Neuropathology, Rhode Island Hospital, Providence, RI, USA
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18
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Carr RM, Correnti J. Insulin resistance in clinical and experimental alcoholic liver disease. Ann N Y Acad Sci 2015; 1353:1-20. [PMID: 25998863 DOI: 10.1111/nyas.12787] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Alcoholic liver disease (ALD) is the number one cause of liver failure worldwide; its management costs billions of healthcare dollars annually. Since the advent of the obesity epidemic, insulin resistance (IR) and diabetes have become common clinical findings in patients with ALD; and the development of IR predicts the progression from simple steatosis to cirrhosis in ALD patients. Both clinical and experimental data implicate the impairment of several mediators of insulin signaling in ALD, and experimental data suggest that insulin-sensitizing therapies improve liver histology. This review explores the contribution of impaired insulin signaling in ALD and summarizes the current understanding of the synergistic relationship between alcohol and nutrient excess in promoting hepatic inflammation and disease.
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Affiliation(s)
- Rotonya M Carr
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jason Correnti
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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19
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Xu CQ, de la Monte SM, Tong M, Huang CK, Kim M. Chronic Ethanol-Induced Impairment of Wnt/β-Catenin Signaling is Attenuated by PPAR-δ Agonist. Alcohol Clin Exp Res 2015; 39:969-79. [PMID: 25903395 DOI: 10.1111/acer.12727] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 03/09/2015] [Indexed: 01/28/2023]
Abstract
BACKGROUND The Wnt/β-catenin pathway regulates liver growth, repair, and regeneration. Chronic ethanol (EtOH) exposure blunts normal liver regenerative responses, in part by inhibiting insulin/IGF signaling, and correspondingly, previous studies showed that EtOH-impaired liver regeneration could be restored by insulin sensitizer (proliferator-activated receptor [PPAR]-δ agonist) treatment. As Wnt/β-catenin functions overlap and cross talk with insulin/IGF pathways, we investigated the effects of EtOH exposure and PPAR-δ agonist treatment on Wnt pathway gene expression in relation to liver regeneration. METHODS Adult male Long Evans rats were fed with isocaloric liquid diets containing 0 or 37% EtOH for 8 weeks and also treated with vehicle or a PPAR-δ agonist during the last 3 weeks of the feeding regimen. The rats were then subjected to 70% partial hepatectomy (PH) and livers harvested at various post-PH time points were used to quantitate expression of 19 Wnt pathway genes using Quantigene 2.0 Multiplex Assay. RESULTS EtOH broadly inhibited expression of Wnt/β-catenin signaling-related genes, including down-regulation of Wnt1, Fzd3, Lef1, and Bcl9 throughout the post-PH time course (0 to 72 hours), and suppression of Wnt7a, Ccnd1, Fgf4, Wif1, Sfrp2, and Sfrp5 at 18- and 24-hour post-PH time points. PPAR-δ agonist treatments rescued the EtOH-induced suppression of Wnt1, Wnt7a, Fzd3, Lef1, Bcl9, Ccnd1, and Sfrp2 gene expression in liver, corresponding with the improvements in DNA synthesis and restoration of hepatic architecture. CONCLUSIONS Chronic high-dose EtOH exposures inhibit Wnt signaling, which likely contributes to the impairments in liver regeneration. Therapeutic effects of PPAR-δ agonists extend beyond restoration of insulin/IGF signaling mechanisms and are mediated in part by enhancement of Wnt pathway signaling. Future studies will determine the degree to which targeted restoration of Wnt signaling is sufficient to improve liver regeneration and remodeling in the context of chronic EtOH exposure.
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Affiliation(s)
- Chelsea Q Xu
- Liver Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Suzanne M de la Monte
- Departments of Medicine and Pathology, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Ming Tong
- Liver Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Chiung-Kuei Huang
- Liver Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island
| | - Miran Kim
- Liver Research Center, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, Rhode Island
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20
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Kim JY, Lee DY, Lee YJ, Park KJ, Kim KH, Kim JW, Kim WH. Chronic alcohol consumption potentiates the development of diabetes through pancreatic β-cell dysfunction. World J Biol Chem 2015; 6:1-15. [PMID: 25717351 PMCID: PMC4317634 DOI: 10.4331/wjbc.v6.i1.1] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 10/29/2014] [Accepted: 12/10/2014] [Indexed: 02/05/2023] Open
Abstract
Chronic ethanol consumption is well established as a major risk factor for type-2 diabetes (T2D), which is evidenced by impaired glucose metabolism and insulin resistance. However, the relationships between alcohol consumption and the development of T2D remain controversial. In particular, the direct effects of ethanol consumption on proliferation of pancreatic β-cell and the exact mechanisms associated with ethanol-mediated β-cell dysfunction and apoptosis remain elusive. Although alcoholism and alcohol consumption are prevalent and represent crucial public health problems worldwide, many people believe that low-to-moderate ethanol consumption may protect against T2D and cardiovascular diseases. However, the J- or U-shaped curves obtained from cross-sectional and large prospective studies have not fully explained the relationship between alcohol consumption and T2D. This review provides evidence for the harmful effects of chronic ethanol consumption on the progressive development of T2D, particularly with respect to pancreatic β-cell mass and function in association with insulin synthesis and secretion. This review also discusses a conceptual framework for how ethanol-produced peroxynitrite contributes to pancreatic β-cell dysfunction and metabolic syndrome.
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21
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Zabala V, Tong M, Yu R, Ramirez T, Yalcin EB, Balbo S, Silbermann E, Deochand C, Nunez K, Hecht S, de la Monte SM. Potential contributions of the tobacco nicotine-derived nitrosamine ketone (NNK) in the pathogenesis of steatohepatitis in a chronic plus binge rat model of alcoholic liver disease. Alcohol Alcohol 2015; 50:118-31. [PMID: 25618784 DOI: 10.1093/alcalc/agu083] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIMS Alcoholic liver disease (ALD) is linked to binge drinking and cigarette smoking. Heavy chronic ± binge alcohol, or low-level exposures to dietary nitrosamines cause steatohepatitis with insulin resistance and oxidative stress in animal models. This study examines hepatotoxic effects of sub-mutagenic exposures to tobacco-specific nitrosamine (NNK) in relation to ALD. METHODS Long Evans rats were fed liquid diets containing 0 or 26% (caloric) ethanol (EtOH) for 8 weeks. In Weeks 3 through 8, rats were treated with NNK (2 mg/kg) or saline by i.p. injection, 3×/week, and in Weeks 7 and 8, EtOH-fed rats were binge-administered 2 g/kg EtOH 3×/week; controls were given saline. RESULTS EtOH ± NNK caused steatohepatitis with necrosis, disruption of the hepatic cord architecture, ballooning degeneration, early fibrosis, mitochondrial cytopathy and ER disruption. Severity of lesions was highest in the EtOH+NNK group. EtOH and NNK inhibited insulin/IGF signaling through Akt and activated pro-inflammatory cytokines, while EtOH promoted lipid peroxidation, and NNK increased apoptosis. O(6)-methyl-Guanine adducts were only detected in NNK-exposed livers. CONCLUSION Both alcohol and NNK exposures contribute to ALD pathogenesis, including insulin/IGF resistance and inflammation. The differential effects of EtOH and NNK on adduct formation are critical to ALD progression among alcoholics who smoke.
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Affiliation(s)
- Valerie Zabala
- Department of Medicine, Division of Gastroenterology, and The Liver Research Center, Rhode Island Hospital, Providence, RI, USA Department of Molecular Pharmacology and Physiology, Brown University, Providence, RI, USA
| | - Ming Tong
- Department of Medicine, Division of Gastroenterology, and The Liver Research Center, Rhode Island Hospital, Providence, RI, USA Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Rosa Yu
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Teresa Ramirez
- Department of Molecular Pharmacology and Physiology, Brown University, Providence, RI, USA
| | - Emine B Yalcin
- Department of Medicine, Division of Gastroenterology, and The Liver Research Center, Rhode Island Hospital, Providence, RI, USA Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Silvia Balbo
- Masonic Cancer Center, University of Minnesota, Cancer and Cardiovascular Research Building, 2231 6th Street SE, Minneapolis, MN 55455, USA
| | | | - Chetram Deochand
- Biotechnology Graduate Program, Brown University, Providence, RI, USA
| | - Kavin Nunez
- Department of Neuroscience, Brown University, Providence, RI, USA
| | - Stephen Hecht
- Masonic Cancer Center, University of Minnesota, Cancer and Cardiovascular Research Building, 2231 6th Street SE, Minneapolis, MN 55455, USA
| | - Suzanne M de la Monte
- Department of Medicine, Division of Gastroenterology, and The Liver Research Center, Rhode Island Hospital, Providence, RI, USA Warren Alpert Medical School of Brown University, Providence, RI, USA Departments of Pathology and Neurology, and the Division of Neuropathology, Rhode Island Hospital, Providence, RI, USA
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22
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Mellion ML, Silbermann E, Gilchrist JM, Machan JT, Leggio L, de la Monte S. Small-fiber degeneration in alcohol-related peripheral neuropathy. Alcohol Clin Exp Res 2014; 38:1965-72. [PMID: 24961481 DOI: 10.1111/acer.12470] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 04/10/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND Alcohol-related peripheral neuropathy (ALN) is generally characterized as an axonal large-fiber polyneuropathy caused by thiamine deficiency. We hypothesized, based on clinical observations, that ALN is associated with a small-fiber polyneuropathy that can be diagnosed with skin biopsy in heavy alcohol drinking subjects with normal thiamine status. METHODS Eighteen individuals (9 heavy alcohol drinking subjects and 9 healthy control subjects) were assessed for the potential utility of skin biopsies in detecting ALN-associated small nerve fiber degeneration. Heavy drinking was defined as greater than 4 drinks/d and 5 drinks/d in women and men, respectively, as determined by the Timeline Follow-Back and lifetime drinking history. All subjects underwent neurological examination, nerve conduction studies, and skin biopsies to quantify end nerve fiber densities (ENFD). Other causes of neuropathy were excluded and thiamine status was assessed. RESULTS Average ENFD were significantly decreased at the calf in the alcohol group as compared with control group (p < 0.0001). Histological sections demonstrated striking attrition and architectural simplification of intraepidermal nerve fibers in the heavy alcohol drinking subjects. There were no significant intergroup differences with respect to clinical assessments of neuropathy or thiamine status. CONCLUSIONS ALN is associated with a small-fiber neuropathy that can be detected with skin biopsy in heavy alcohol drinking individuals with normal thiamine status. Skin biopsy is a useful, minimally invasive biomarker that could extend studies to understand the effect of alcohol on the peripheral nerves and to evaluate potential therapeutic agents in larger clinical trials.
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Affiliation(s)
- Michelle L Mellion
- Department of Neurology, Rhode Island Hospital, Alpert Medical School of Brown University, Providence, Rhode Island
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23
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Carr RM, Peralta G, Yin X, Ahima RS. Absence of perilipin 2 prevents hepatic steatosis, glucose intolerance and ceramide accumulation in alcohol-fed mice. PLoS One 2014; 9:e97118. [PMID: 24831094 PMCID: PMC4022498 DOI: 10.1371/journal.pone.0097118] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 04/14/2014] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Perilipin 2 (Plin2) is a lipid droplet protein that has roles in both lipid and glucose homeostasis. An increase in Plin2 in liver is associated with the development of steatosis, glucose intolerance, and ceramide accumulation in alcoholic liver disease. We investigated the role of Plin2 on energy balance and glucose and lipid homeostasis in wildtype and Plin2 knockout (Plin2KO) mice chronically fed a Lieber-DeCarli liquid ethanol or control diet for six weeks. METHODS We performed in vivo measurements of energy intake and expenditure; body composition; and glucose tolerance. After sacrifice, liver was dissected for histology and lipid analysis. RESULTS We found that neither genotype nor diet had a significant effect on final weight, body composition, or energy intake between WT and Plin2KO mice fed alcohol or control diets. Additionally, alcohol feeding did not affect oxygen consumption or carbon dioxide production in Plin2KO mice. We performed glucose tolerance testing and observed that alcohol feeding failed to impair glucose tolerance in Plin2KO mice. Most notably, absence of Plin2 prevented hepatic steatosis and ceramide accumulation in alcohol-fed mice. These changes were related to downregulation of genes involved in lipogenesis and triglyceride synthesis. CONCLUSIONS Plin2KO mice chronically fed alcohol are protected from hepatic steatosis, glucose intolerance, and hepatic ceramide accumulation, suggesting a critical pathogenic role of Plin2 in experimental alcoholic liver disease.
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Affiliation(s)
- Rotonya M. Carr
- University of Pennsylvania, Perelman School of Medicine, Department of Medicine, Gastroenterology Division, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| | - Giselle Peralta
- University of Pennsylvania, Perelman School of Medicine, Institute for Diabetes, Obesity and Metabolism, Philadelphia, Pennsylvania, United States of America
| | - Xiaoyan Yin
- University of Pennsylvania, Perelman School of Medicine, Institute for Diabetes, Obesity and Metabolism, Philadelphia, Pennsylvania, United States of America
| | - Rexford S. Ahima
- University of Pennsylvania, Perelman School of Medicine, Institute for Diabetes, Obesity and Metabolism, Philadelphia, Pennsylvania, United States of America
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Zhu Z, Jiang Z, Zhou J, Zhou D, Wang W, Zhao C, Zhen Z, Nanji AA. Involvement of insulin resistance in the protective effect of metformin against alcoholic liver injury. Alcohol Clin Exp Res 2014; 38:1510-9. [PMID: 24797033 DOI: 10.1111/acer.12418] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 02/11/2014] [Accepted: 03/12/2014] [Indexed: 12/21/2022]
Abstract
BACKGROUND Alcoholic liver disease (ALD) continues to be a major cause of morbidity worldwide. The exact mechanisms for ALD pathogenesis are not fully understood. There is currently no known available drug for ALD. Previous studies have suggested that ethanol (EtOH)-induced hepatic insulin resistance, through the inhibition of adenosine monophosphate-activated protein kinase (AMPK) and the expression of adiponectin as well as downstream enzymes, contribute to the development of ALD. This study was to determine the effects of EtOH on AMPK activity as well as the protective effect of metformin. METHODS Forty male Wistar rats weighing 200 ± 20 g were randomized into 4 groups (n = 10) as follows: A = control group-rats received rodent chow; B = control + metformin group-rats received metformin (200 mg/kg/d intragastrically [IG]) at 21:00; C = EtOH group-rats were gavaged with alcohol of gradually increasing concentrations (30 to 60%, 5 to 9 g/kg/d) twice a day (9:00 and 16:00); D = EtOH + metformin group-rats received the same amount of EtOH as the rats in group C, and in addition received metformin (200 mg/kg/d IG) at 21:00. After 16 weeks, blood and liver samples were collected for further study. RESULTS Chronic EtOH consumption led to liver injury both histologically and biochemically accompanied by insulin resistance, reduced AMPK activity, and dysregulation of downstream enzymes. Decreased levels of circulating adiponectin and decreased expression of proliferator-activated receptor gamma coactivator-1α (PGC-1α) and peroxisome proliferator-activated receptors-α (PPAR-α) in the hepatic tissue were observed. Treatment with metformin attenuated the severity of liver injury, restored AMPK activity and normalized the expression of acetyl-CoA carboxylase and fatty acid synthase. In addition, metformin also increased the circulating adiponectin and liver adiponectin receptor 2 expression. Furthermore, PGC-1α and PPAR-α activities were also restored. CONCLUSIONS EtOH exposure induces hepatic insulin resistance. Metformin improved insulin resistance and reversed liver injury through the activation of AMPK and normalized adiponectin signaling making metformin a promising drug for the treatment of ALD.
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Affiliation(s)
- ZhanTao Zhu
- Department of Infectious disease , Third Hospital, Hebei Medical University, Shijiazhuang, China
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Hakucho A, Liu J, Liu X, Fujimiya T. Carvedilol improves ethanol-induced liver injury via modifying the interaction between oxidative stress and sympathetic hyperactivity in rats. Hepatol Res 2014; 44:560-70. [PMID: 23607506 DOI: 10.1111/hepr.12143] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 04/02/2013] [Accepted: 04/17/2013] [Indexed: 12/20/2022]
Abstract
AIM Oxidative stress is a major pathway mediating ethanol hepatotoxicity and liver injury. We previously found that carvedilol, which can block the sympathetic nervous system via β1-, β2- and α1-adrenoreceptors, modifies ethanol-induced production of lipogenesis- and fibrogenesis-related mediators from hepatic stellate cells (HSC). In the present study, we assessed the effects of carvedilol on ethanol-induced liver injury, hepatic insulin resistance, and the interaction between oxidative stress and sympathetic hyperactivity in rats with alcoholic fatty liver disease (AFLD). METHODS Male Wistar rats were pair-fed for 49 days and divided into four groups: control and ethanol liquid-diet-fed rats with and without 7-day carvedilol treatment. Rats' sympathetic activity, hepatic oxidative stress, hepatic insulin resistance and liver injury were evaluated based on biochemical analysis, enzyme-linked immunosorbent assay, fluorescence immunohistochemistry, western blot and reverse transcriptase polymerase chain reaction. RESULTS Forty-nine days of ethanol consumption induced the increases in circulating noradrenaline metabolite (3-methoxy-4-hydroxyphenylglycol), hepatic noradrenaline and 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, the downregulation of hepatic insulin receptor substrate-1 gene expression, and the accumulation of fatty droplets within hepatocytes with the increased hepatic triglyceride and blood alanine aminotransferase levels. All of these changes were modified by carvedilol treatment. 8-OHdG was detected in activated HSC and suppressed by carvedilol treatment based on fluorescence immunohistochemical double-staining analysis. CONCLUSION Carvedilol may modify the interaction between the oxidative stress and the sympathetic hyperactivity, and then contribute to attenuating the development of AFLD in rats. Additionally, oxidative stress may be responsible for the activation of HSC during the early stage of alcoholic liver disease.
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Affiliation(s)
- Ayako Hakucho
- Department of Legal Medicine, Yamaguchi University Graduate School of Medicine, Ube, Japan
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Abstract
Long-term, excessive consumption of alcoholic beverages produces a peripheral neuropathy with symptoms of decreased superficial sensation, hyperalgesia, and weakness. Alcoholic neuropathy is characterized by axonal degeneration with reduced density of both small and large fibers and axonal sprouting. Electrophysiologic studies reveal a marked reduction in the amplitude of sensory potentials and moderate slowing of nerve conduction, mainly in the lower extremities. Dietary deficiency of vitamins, which are often associated with chronic alcoholism, can contribute to the pathogenesis. Recent studies using animal models have identified several mechanisms by which ethanol impacts peripheral nerve function. Ethanol can exert direct neurotoxic effects on peripheral nerves via its metabolite acetaldehyde and by enhancing oxidative stress. Ethanol activation of protein kinase Cε signaling in primary afferent nociceptors plays an important role in lowering nociceptive threshold. Further, ethanol causes cytoskeletal dysfunction and inhibits both anterograde and retrograde axonal transport. Alcoholic neuropathy is potentially reversible and treatments include abstinence from alcoholic beverages and consumption of a nutritionally balanced diet supplemented with B vitamins. However, response to these treatment strategies can be variable, which underscores the need for novel therapeutic strategies. In this review, we provide an overview of the clinical findings and insights on molecular mechanisms from animal models.
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Affiliation(s)
- Rajani P Maiya
- College of Pharmacy, University of Texas, Austin, TX, USA
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Tong M, Longato L, Ramirez T, Zabala V, Wands JR, de la Monte SM. Therapeutic reversal of chronic alcohol-related steatohepatitis with the ceramide inhibitor myriocin. Int J Exp Pathol 2013; 95:49-63. [PMID: 24456332 DOI: 10.1111/iep.12052] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2013] [Accepted: 08/18/2013] [Indexed: 12/13/2022] Open
Abstract
Alcohol-related liver disease (ALD) is associated with steatohepatitis and insulin resistance. Insulin resistance impairs growth and disrupts lipid metabolism in hepatocytes. Dysregulated lipid metabolism promotes ceramide accumulation and oxidative stress, leading to lipotoxic states that activate endoplasmic reticulum (ER) stress pathways and worsen inflammation and insulin resistance. In a rat model of chronic alcohol feeding, we characterized the effects of a ceramide inhibitor, myriocin, on the histopathological and ultrastructural features of steatohepatitis, and the biochemical and molecular indices of hepatic steatosis, insulin resistance and ER stress. Myriocin reduced the severity of alcohol-related steatohepatitis including the abundance and sizes of lipid droplets and mitochondria, inflammation and architectural disruption of the ER. In addition, myriocin-mediated reductions in hepatic lipid and ceramide levels were associated with constitutive enhancement of insulin signalling through the insulin receptor and IRS-2, reduced hepatic oxidative stress and modulation of ER stress signalling mechanisms. In conclusion, ceramide accumulation in liver mediates tissue injury, insulin resistance and lipotoxicity in ALD. Reducing hepatic ceramide levels can help restore the structural and functional integrity of the liver in chronic ALD due to amelioration of insulin resistance and ER stress. However, additional measures are needed to protect the liver from alcohol-induced necroinflammatory responses vis-à-vis continued alcohol abuse.
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Affiliation(s)
- Ming Tong
- Liver Research Center, Division of Gastroenterology, Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
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Lizarazo D, Zabala V, Tong M, Longato L, de la Monte SM. Ceramide inhibitor myriocin restores insulin/insulin growth factor signaling for liver remodeling in experimental alcohol-related steatohepatitis. J Gastroenterol Hepatol 2013; 28:1660-8. [PMID: 23802886 PMCID: PMC4551508 DOI: 10.1111/jgh.12291] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/19/2013] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Alcohol-related liver disease (ALD) is mediated in part by insulin resistance. Attendant dysregulation of lipid metabolism increases accumulation of hepatic ceramides that worsen insulin resistance and compromise the structural and functional integrity of the liver. Insulin and insulin growth factor (IGF) stimulate aspartyl-asparaginyl-β-hydroxylase (AAH), which promotes cell motility needed for structural maintenance and remodeling of the liver. AAH mediates its effects by activating Notch, and in ALD, insulin/IGF signaling, AAH, and Notch are inhibited. METHOD To test the hypothesis that in ALD, hepatic ceramide load contributes to impairments in insulin, AAH, and Notch signaling, control and chronic ethanol-fed adult Long-Evans rats were treated with myriocin, an inhibitor of serine palmitoyl transferase. Livers were used to assess steatohepatitis, insulin/IGF pathway activation, and expression of AAH-Notch signaling molecules. RESULTS Chronic ethanol-fed rats had steatohepatitis with increased ceramide levels; impairments in signaling through the insulin receptor, insulin receptor substrate, and Akt; and decreased expression of AAH, Notch, Jagged, Hairy-Enhancer of Split-1, hypoxia-inducible factor 1α, and proliferating cell nuclear antigen. Myriocin abrogated many of these adverse effects of ethanol, particularly hepatic ceramide accumulation, steatohepatitis, and impairments of insulin signaling through Akt, AAH, and Notch. CONCLUSIONS In ALD, the histopathology and impairments in insulin/IGF responsiveness can be substantially resolved by ceramide inhibitor treatments, even in the context of continued chronic ethanol exposure.
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Affiliation(s)
- Diana Lizarazo
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Valerie Zabala
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Ming Tong
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Lisa Longato
- Liver Research Center, Division of Gastroenterology and Department of Medicine, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Suzanne M. de la Monte
- Liver Research Center, Divisions of Gastroenterology and Neuropathology and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA
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Abstract
PURPOSE OF REVIEW To explore the causal relationship between metabolic syndrome, type 2 diabetes and hyperuricemia. RECENT FINDINGS The prevalence of hyperuricemia in male adults with metabolic syndrome was increased and a large difference in prevalence of metabolic syndrome also existed in those with hyperuricemia compared with normouricemia. Even in those with normouricemia, higher serum uric acid levels were associated with metabolic syndrome. Serum uric acid was an independent risk factor for incident diabetes, and evidence showed that the patients with both gout and type 2 diabetes exhibited a mutual inter-dependent effect on higher incidences. Furthermore, obese patients often demonstrated insulin resistance and adipose tissue macrophage with low-grade inflammation, which is suggested to be the major contributor. Although alcohol intake is considered a risk for developing hyperuricemia, moderate alcohol intake showed a lower risk for developing type 2 diabetes and insulin resistance. Hyperinsulinemia reduces renal excretion of uric acid on the proximal tubular of the kidney leading to hyperuricemia, which has deleterious effects on endothelial function and on nitric oxide bioavailability, thus causing hyperinsulinemia. SUMMARY We found evidence to suggest that insulin resistance plays a potentially key role in the causal relationship between metabolic syndrome, type 2 diabetes and hyperuricemia. Furthermore, it is likely that hyperuricemia and insulin resistance share a bidirectional causal effect.
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Gallego-Durán R, Ampuero J, Funuyet J, Romero-Gómez M. [Alcoholic and non-alcoholic steatohepatitis: who is affected and what can we do for them?]. GASTROENTEROLOGIA Y HEPATOLOGIA 2013; 36:587-96. [PMID: 24011648 DOI: 10.1016/j.gastrohep.2013.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 06/18/2013] [Indexed: 12/21/2022]
Abstract
The most common causes of steatohepatitis are alcohol intake and metabolic disorders. Several methods based on biochemical determinations (carbohydrate deficient transferrin) and questionnaires (AUDIT, CAGE, MALE) are useful for detecting surreptitious alcohol intake. Although new non-invasive methods are under development, based both on lipidomics (Owl-Liver(®)) and on biochemical determinations and anthropometric parameters (NAFLD Fibrosis score) or imaging methods (DeMILI NASH-MRi(®)), none has been proposed as definitive and the gold standard continues to be liver biopsy. The pathogenesis of alcoholic and non-alcoholic steatohepatitis shares some elements such as insulin resistance, cytochrome CYP2E1-mediated oxidative stress, adiponutrin and its PNPLA3 gene, and the microbiota. The first-line treatment consists of lifestyle changes, including giving up alcohol, diet and exercise.
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Affiliation(s)
- Rocío Gallego-Durán
- Unidad Médico-Quirúrgica de Enfermedades Digestivas y CIBERehd, Hospital Universitario de Valme, Universidad de Sevilla, Sevilla, España
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Mellion ML, Nguyen V, Tong M, Gilchrist J, De La Monte S. Experimental model of alcohol-related peripheral neuropathy. Muscle Nerve 2013; 48:204-11. [PMID: 23761140 PMCID: PMC4551398 DOI: 10.1002/mus.23744] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/28/2012] [Indexed: 11/11/2022]
Abstract
INTRODUCTION The aim of this work was to determine the effect of chronic alcohol exposure on peripheral nerves in a nutritionally balanced rat model of alcoholism. METHODS Three different strains of adult male rats were pair-fed for 8 weeks with isocaloric liquid diets containing 0% or 37% ethanol. Nerve conduction studies (NCS) were performed. Peripheral nerve and muscle were examined histologically with morphometrics. RESULTS Ethanol exposure significantly slowed velocity in tibial and fibular nerves, but not in the plantar nerve in all 3 strains. Studies of the sciatic nerve revealed decreased fiber diameters and increased regenerative sprouts in peripheral nerves. There was muscle denervation of ethanol-exposed rats in all 3 strains. CONCLUSIONS Chronic ethanol exposure caused a polyneuropathy characterized by axonal degeneration despite adequate nutrition. These results suggest that ethanol exposure has direct neurotoxic effects on peripheral nerves. This model may be useful in understanding the underlying mechanism(s) of alcohol-related peripheral neuropathy.
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Affiliation(s)
- Michelle L Mellion
- Department of Neurology, Warren Alpert School of Medicine, Rhode Island Hospital, Brown University, Suite 555, 2 Dudley Street, Providence, Rhode Island 02905, USA.
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Carr RM, Dhir R, Yin X, Agarwal B, Ahima RS. Temporal effects of ethanol consumption on energy homeostasis, hepatic steatosis, and insulin sensitivity in mice. Alcohol Clin Exp Res 2013; 37:1091-9. [PMID: 23398239 DOI: 10.1111/acer.12075] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 11/20/2012] [Indexed: 12/17/2022]
Abstract
BACKGROUND Alcoholic liver disease (ALD) progresses from steatosis to inflammation, fibrosis, and cirrhosis. Although ALD has been associated with insulin resistance, it is unclear whether insulin resistance coincides with the development of steatosis. METHODS We studied the temporal relationship of steatosis and glucose homeostasis in mice fed a Lieber-DeCarli liquid control or ethanol (EtOH) diet for 2, 4, or 8 weeks. We studied the effects of alcohol consumption on energy balance, body composition, and hepatic lipids. Glucose tolerance test was performed, and insulin sensitivity was evaluated with hyperinsulinemic-euglycemic clamp. RESULTS EtOH-fed mice developed hepatic steatosis over time as compared with control-fed mice despite similar energy intake and expenditure, and gain in body weight and fat. EtOH-fed mice developed glucose intolerance as early as 2 weeks, while insulin resistance developed at 4 weeks. A hyperinsulinemic clamp study at 8 weeks revealed both hepatic and peripheral insulin resistance in EtOH-fed mice. Insulin resistance was associated with hepatic steatosis, increased ceramide levels, and Perilipin 2 expression. CONCLUSIONS Chronic EtOH consumption leads to the development of hepatic steatosis, impaired glucose tolerance, and insulin resistance. These changes are independent of energy intake or expenditure, weight, whole body fat content, and inflammation. A better understanding of the processes linking EtOH-induced steatosis and abnormal glucose homeostasis may lead to novel therapies targeting the progression of ALD.
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Affiliation(s)
- Rotonya M Carr
- Department of Medicine, Gastroenterology Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Ramirez T, Tong M, Chen WC, Nguyen QG, Wands JR, de la Monte SM. Chronic alcohol-induced hepatic insulin resistance and endoplasmic reticulum stress ameliorated by peroxisome-proliferator activated receptor-δ agonist treatment. J Gastroenterol Hepatol 2013; 28:179-87. [PMID: 22988930 PMCID: PMC4406771 DOI: 10.1111/j.1440-1746.2012.07256.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/10/2012] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Chronic alcoholic liver disease is associated with hepatic insulin resistance, dysregulated lipid metabolism with increased toxic lipid (ceramide) accumulation, lipid peroxidation, and oxidative and endoplasmic reticulum (ER) stress. Peroxisome-proliferator activated receptor (PPAR) agonists are insulin sensitizers that can restore hepatic insulin responsiveness in both alcohol and non-alcohol-related steatohepatitis. Herein, we demonstrate that treatment with a PPAR-δ agonist enhances insulin signaling and reduces the severities of ER stress and ceramide accumulation in an experimental model of ethanol-induced steatohepatitis. METHODS Adult male Long Evans rats were pair fed with isocaloric liquid diets containing 0% or 37% ethanol (caloric) for 8 weeks. After 3 weeks on the diets, rats were treated with vehicle or PPAR-δ agonist twice weekly by i.p. injection. RESULTS Ethanol-fed rats developed steatohepatitis with inhibition of signaling through the insulin and insulin-like growth factor-1 receptors, and Akt activated pathways. Despite continued ethanol exposure, PPAR-δ agonist co-treatments increased Akt activation, reduced multiple molecular indices of ER stress and steatohepatitis. CONCLUSIONS These results suggest that PPAR-δ agonist rescue of chronic alcoholic liver disease is mediated by enhancement of insulin signaling through Akt/metabolic pathways that reduce lipotoxicity and ER stress.
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Affiliation(s)
- Teresa Ramirez
- Liver Research Center and Department of Medicine, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island 02903, USA
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Ramirez T, Longato L, Dostalek M, Tong M, Wands JR, de la Monte SM. Insulin resistance, ceramide accumulation and endoplasmic reticulum stress in experimental chronic alcohol-induced steatohepatitis. Alcohol Alcohol 2012; 48:39-52. [PMID: 22997409 DOI: 10.1093/alcalc/ags106] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
AIMS Chronic alcohol abuse causes steatohepatitis with insulin resistance, which impairs hepatocellular growth, survival and metabolism. However, growing evidence supports the concept that progressive alcohol-related liver injury may be mediated by concurrent mal-signaling through other networks that promote insulin resistance, e.g. pro-inflammatory, pro-ceramide and endoplasmic reticulum (ER) stress cascades. METHODS Using the Long Evans rat model of chronic ethanol feeding, we characterized the histopathologic and ultrastructural features of steatohepatitis in relation to biochemical and molecular indices of tissue injury, inflammation, insulin resistance, dysregulated lipid metabolism and ER stress. RESULTS Chronic steatohepatitis with early chicken-wire fibrosis was associated with enlargement of mitochondria and disruption of ER structure by electron microscopy, elevated indices of lipid storage, lipid peroxidation and DNA damage, increased activation of pro-inflammatory cytokines, impaired signaling through the insulin receptor (InR), InR substrate-1, Akt, ribosomal protein S6 kinase and proline-rich Akt substrate 40 kDa, glycogen synthase kinase 3β activation and constitutive up-regulation of ceramide and ER stress-related genes. Liquid chromatography coupled with tandem mass spectrometry demonstrated altered ceramide profiles with higher levels of C14 and C18, and reduced C16 species in ethanol-exposed livers. CONCLUSION The histopathologic and ultrastructural abnormalities in chronic alcohol-related steatohepatitis are associated with persistent hepatic insulin resistance and pro-inflammatory cytokine activation, dysregulated lipid metabolism with altered ceramide profiles and both ER and oxidative stress. Corresponding increases in lipid peroxidation, DNA damage and protein carbonylation may have contributed to the chronicity and progression of disease. The findings herein suggest that multi-pronged therapeutic strategies may be needed for effective treatment of chronic alcoholic liver disease in humans.
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Affiliation(s)
- Teresa Ramirez
- Liver Research Center, Divisions of Gastroenterology and Neuropathology, Departments of Medicine, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Claverick Street, Providence, RI 02903, USA
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De La Monte SM. Metabolic derangements mediate cognitive impairment and Alzheimer's disease: role of peripheral insulin-resistance diseases. Panminerva Med 2012; 54:171-8. [PMID: 22801434 PMCID: PMC4537701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Herein, we review evidence that systemic insulin-resistance diseases linked to obesity, type 2 diabetes, and non-alcoholic steatohepatitis promote neurodegeneration. Insulin-resistance dysregulates lipid metabolism, which promotes ceramide accumulation with attendant inflammation and endoplasmic reticulum (ER) stress. Mechanistically, we propose that toxic ceramides generated in extra-CNS tissues, e.g. liver, get released into peripheral blood, and subsequently transit across the blood-brain barrier into the brain where they induce brain insulin-resistance, inflammation, and cell death (extrinsic pathway). These abnormalities establish or help propagate a cascade of neurodegeneration associated with increased ER stress and ceramide generation, which exacerbate brain insulin-resistance, cell death, myelin degeneration, and neuro-inflammation. The data suggest that a mal-signaling network mediated by toxic ceramides, ER stress, and insulin-resistance should be targeted to disrupt positive feedback loops that drive the AD neurodegeneration cascade.
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Affiliation(s)
- S M De La Monte
- Department of Neuropathology, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Providence, RI, USA.
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Impaired insulin/IGF signaling in experimental alcohol-related myopathy. Nutrients 2012; 4:1058-75. [PMID: 23016132 PMCID: PMC3448087 DOI: 10.3390/nu4081058] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 08/07/2012] [Accepted: 08/13/2012] [Indexed: 12/13/2022] Open
Abstract
Alcohol-related myopathy (Alc-M) is highly prevalent among heavy drinkers, although its pathogenesis is not well understood. We hypothesize that Alc-M is mediated by combined effects of insulin/IGF resistance and oxidative stress, similar to the effects of ethanol on liver and brain. We tested this hypothesis using an established model in which adult rats were pair-fed for 8 weeks with isocaloric diets containing 0% (N = 8) or 35.5% (N = 13) ethanol by caloric content. Gastrocnemius muscles were examined by histology, morphometrics, qRT-PCR analysis, and ELISAs. Chronic ethanol feeding reduced myofiber size and mRNA expression of IGF-1 polypeptide, insulin, IGF-1, and IGF-2 receptors, IRS-1, and IRS-2. Multiplex ELISAs demonstrated ethanol-associated inhibition of insulin, IRS-1, Akt, and p70S6K signaling, and increased activation of GSK-3β. In addition, ethanol-exposed muscles had increased 4-hydroxy-2-nonenal immunoreactivity, reflecting lipid peroxidation, and reduced levels of mitochondrial Complex IV, Complex V, and acetylcholinesterase. These results demonstrate that experimental Alc-M is associated with inhibition of insulin/IGF/IRS and downstream signaling that mediates metabolism and cell survival, similar to findings in alcoholic liver and brain degeneration. Moreover, the increased oxidative stress, which could be mediated by mitochondrial dysfunction, may have led to inhibition of acetylcholinesterase, which itself is sufficient to cause myofiber atrophy and degeneration.
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Nguyen VA, Le T, Tong M, Mellion M, Gilchrist J, de la Monte SM. Experimental alcohol-related peripheral neuropathy: role of insulin/IGF resistance. Nutrients 2012; 4:1042-57. [PMID: 23016131 PMCID: PMC3448086 DOI: 10.3390/nu4081042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 07/30/2012] [Accepted: 08/02/2012] [Indexed: 01/01/2023] Open
Abstract
The mechanisms of alcohol-related peripheral neuropathy (ALPN) are poorly understood. We hypothesize that, like alcohol-related liver and brain degeneration, ALPN may be mediated by combined effects of insulin/IGF resistance and oxidative stress. Adult male Long Evans rats were chronically pair-fed with diets containing 0% or 37% ethanol (caloric), and subjected to nerve conduction studies. Chronic ethanol feeding slowed nerve conduction in the tibial (p = 0.0021) motor nerve, and not plantar sensory nerve, but it did not affect amplitude. Histological studies of the sciatic nerve revealed reduced nerve fiber diameters with increased regenerative sprouts, and denervation myopathy in ethanol-fed rats. qRT-PCR analysis demonstrated reduced mRNA levels of insulin, IGF-1, and IGF-2 polypeptides, IGF-1 receptor, and IRS2, and ELISAs revealed reduced immunoreactivity for insulin and IGF-1 receptors, IRS-1, IRS-4, myelin-associated glycoprotein, and tau in sciatic nerves of ethanol-fed rats (all p < 0.05 or better). The findings suggest that ALPN is characterized by (1) slowed conduction velocity with demyelination, and a small component of axonal degeneration; (2) impaired trophic factor signaling due to insulin and IGF resistance; and (3) degeneration of myelin and axonal cytoskeletal proteins. Therefore, ALPN is likely mediated by molecular and signal transduction abnormalities similar to those identified in alcoholic liver and brain degeneration.
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Affiliation(s)
- Van Anh Nguyen
- Department of Medicine, Rhode Island Hospital, Alpert Medical School of Brown University, 55 Claverick Street, Providence RI 02903, USA; (V.A.N.); (T.L.); (M.T.)
| | - Tran Le
- Department of Medicine, Rhode Island Hospital, Alpert Medical School of Brown University, 55 Claverick Street, Providence RI 02903, USA; (V.A.N.); (T.L.); (M.T.)
| | - Ming Tong
- Department of Medicine, Rhode Island Hospital, Alpert Medical School of Brown University, 55 Claverick Street, Providence RI 02903, USA; (V.A.N.); (T.L.); (M.T.)
| | - Michelle Mellion
- Department of Neurology, Rhode Island Hospital, Alpert Medical School of Brown University, 593 Eddy Street, Providence RI 02903, USA; (M.M.); (J.G.)
| | - James Gilchrist
- Department of Neurology, Rhode Island Hospital, Alpert Medical School of Brown University, 593 Eddy Street, Providence RI 02903, USA; (M.M.); (J.G.)
| | - Suzanne M. de la Monte
- Departments of Neuropathology/Pathology, Neurology, Neurosurgery, and Medicine, Rhode Island Hospital, Alpert Medical School of Brown University, 55 Claverick Street, Providence RI 02903, USA
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Insulin resistance, ceramide accumulation, and endoplasmic reticulum stress in human chronic alcohol-related liver disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:479348. [PMID: 22577490 PMCID: PMC3347750 DOI: 10.1155/2012/479348] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Revised: 12/28/2011] [Accepted: 01/10/2012] [Indexed: 12/14/2022]
Abstract
Background. Chronic alcohol-related liver disease (ALD) is mediated by insulin resistance, mitochondrial dysfunction, inflammation, oxidative stress, and DNA damage. Recent studies suggest that dysregulated lipid metabolism with accumulation of ceramides, together with ER stress potentiate hepatic insulin resistance and may cause steatohepatitis to progress. Objective. We examined the degree to which hepatic insulin resistance in advanced human ALD is correlated with ER stress, dysregulated lipid metabolism, and ceramide accumulation. Methods. We assessed the integrity of insulin signaling through the Akt pathway and measured proceramide and ER stress gene expression, ER stress signaling proteins, and ceramide profiles in liver tissue. Results. Chronic ALD was associated with increased expression of insulin, IGF-1, and IGF-2 receptors, impaired signaling through IGF-1R and IRS1, increased expression of multiple proceramide and ER stress genes and proteins, and higher levels of the C14, C16, C18, and C20 ceramide species relative to control. Conclusions. In human chronic ALD, persistent hepatic insulin resistance is associated with dysregulated lipid metabolism, ceramide accumulation, and striking upregulation of multiple ER stress signaling molecules. Given the role of ceramides as mediators of ER stress and insulin resistance, treatment with ceramide enzyme inhibitors may help reverse or halt progression of chronic ALD.
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Abstract
Chronic alcohol exposure inhibits insulin and insulin-like growth factor signaling in the liver and brain by impairing the signaling cascade at multiple levels. These alterations produced by alcohol cause severe hepatic and central nervous system insulin resistance as the cells fail to adequately transmit signals downstream through Erk/mitogen-activated protein kinase (MAPK), which is needed for DNA synthesis and liver regeneration, and phosphatidylinositol 3-kinase (PI3K), which promotes growth, survival, cell motility, glucose utilization, plasticity, and energy metabolism. The robust inhibition of insulin signaling in liver and brain is augmented by additional factors involving the activation of phosphatases such as phosphatase and tensin homologue (PTEN), which further impairs insulin signaling through PI3K/Akt. Thus, intact insulin signaling is important for neuronal survival. Chronic alcohol consumption produces steatohepatitis, which also promotes hepatic insulin resistance, oxidative stress and injury, with the attendant increased generation of "toxic lipids" such as ceramides that increase insulin resistance. The PI3K/Akt signaling cascade is altered by direct interaction with ceramides as well as through PTEN upregulation as a downstream target gene of enhanced p53 transcriptional activity. Cytotoxic ceramides transferred from the liver to the blood can enter the brain due to their lipid-soluble nature, and thereby exert neurodegenerative effects via a liver-brain axis. We postulate that the neurotoxic and neurodegenerative effects of liver-derived ceramides activate pro-inflammatory cytokines and increase lipid adducts and insulin resistance in the brain to impair cognitive and motor function. These observations are discussed in the context of insulin sensitizers as potential cytoprotective agents against liver and brain injury induced by alcohol.
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MESH Headings
- Alcohol-Induced Disorders, Nervous System/etiology
- Alcohol-Induced Disorders, Nervous System/metabolism
- Alcohol-Induced Disorders, Nervous System/pathology
- Alcohol-Induced Disorders, Nervous System/physiopathology
- Alcoholism/complications
- Alcoholism/drug therapy
- Alcoholism/metabolism
- Alcoholism/pathology
- Alcoholism/physiopathology
- Animals
- Brain/metabolism
- Brain/pathology
- Brain/physiopathology
- DNA Damage
- Fatty Liver, Alcoholic/etiology
- Fatty Liver, Alcoholic/metabolism
- Humans
- Insulin/metabolism
- Insulin Resistance
- Liver/drug effects
- Liver/metabolism
- Liver/pathology
- Liver/physiopathology
- Liver Diseases, Alcoholic/drug therapy
- Liver Diseases, Alcoholic/etiology
- Liver Diseases, Alcoholic/metabolism
- Liver Diseases, Alcoholic/pathology
- Liver Diseases, Alcoholic/physiopathology
- Liver Regeneration
- PPAR gamma/agonists
- PPAR gamma/metabolism
- PTEN Phosphohydrolase/metabolism
- Receptor, IGF Type 1/metabolism
- Signal Transduction
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Affiliation(s)
- Suzanne de la Monte
- Department of Pathology, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
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Liangpunsakul S, Rahmini Y, Ross RA, Zhao Z, Xu Y, Crabb DW. Imipramine blocks ethanol-induced ASMase activation, ceramide generation, and PP2A activation, and ameliorates hepatic steatosis in ethanol-fed mice. Am J Physiol Gastrointest Liver Physiol 2012; 302:G515-23. [PMID: 22194417 PMCID: PMC3311438 DOI: 10.1152/ajpgi.00455.2011] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/18/2011] [Indexed: 01/31/2023]
Abstract
Our previous data showed the inhibitory effect of ethanol on AMP-activated protein kinase phosphorylation, which appears to be mediated, in part, through increased levels of hepatic ceramide and activation of protein phosphatase 2A (Liangpunsakul S, Sozio MS, Shin E, Zhao Z, Xu Y, Ross RA, Zeng Y, Crabb DW. Am J Physiol Gastrointest Liver Physiol 298: G1004-G1012, 2010). The effect of ethanol on AMP-activated protein kinase phosphorylation was reversed by imipramine, suggesting that the generation of ceramide via acid sphingomyelinase (ASMase) is stimulated by ethanol. In this study, we determined the effects of imipramine on the development of hepatic steatosis, the generation of ceramide, and downstream effects of ceramide on inflammatory, insulin, and apoptotic signaling pathways, in ethanol-fed mice. The effect of ethanol and imipramine (10 μg/g body wt ip) on ceramide levels, as well as inflammatory, insulin, and apoptotic signaling pathways, was studied in C57BL/6J mice fed the Lieber-DeCarli diet. Ethanol-fed mice developed the expected steatosis, and cotreatment with imipramine for the last 2 wk of ethanol feeding resulted in improvement in hepatic steatosis. Ethanol feeding for 4 wk induced impaired glucose tolerance compared with controls, and this was modestly improved with imipramine treatment. There was a significant decrease in total ceramide concentrations in response to imipramine in ethanol-fed mice treated with and without imipramine (287 ± 11 vs. 348 ± 12 pmol/mg tissue). The magnitude and specificity of inhibition on each ceramide species differed. A significant decrease was observed for C16 (28 ± 3 vs. 33 ± 2 pmol/mg tissue) and C24 (164 ± 9 vs. 201 ± 4 pmol/mg tissue) ceramide. Ethanol feeding increased the levels of the phosphorylated forms of ERK slightly and increased phospho-p38 and phospho-JNK substantially. The levels of phospho-p38 and phospho-JNK were reduced by treatment with imipramine. The activation of ASMase and generation of ceramide in response to ethanol feeding may underlie several effects of ethanol. ASMase inhibitors may be considered as a therapeutic target for alcohol-induced hepatic steatosis and activation of stress kinases.
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Affiliation(s)
- Suthat Liangpunsakul
- Division of Gastroenterology and Hepatology, Department of Medicine, Indiana University School of Medicine, Indianapolis, USA.
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Ramirez T, Tong M, Ayala CA, Monfils PR, McMillan PN, Zabala V, Wands JR, de la Monte SM. Structural Correlates of PPAR Agonist Rescue of Experimental Chronic Alcohol-Induced Steatohepatitis. ACTA ACUST UNITED AC 2012; 2. [PMID: 26339530 PMCID: PMC4554760 DOI: 10.4172/2161-0681.1000114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Chronic alcoholic liver disease is associated with hepatic insulin resistance, inflammation, oxidative and ER stress, mitochondrial dysfunction, and DNA damage. Peroxisome-proliferator activated receptor (PPAR) agonists are insulin sensitizers that have anti-inflammatory/anti-oxidant effects. We previously showed that PPAR agonists can restore hepatic insulin responsiveness in chronic ethanol-fed rats with steatohepatitis. Herein, we furthered our investigations by characterizing the histological and ultrastructural changes mediated by PPAR agonist rescue of alcohol-induced steatohepatitis. Adult male Long Evans rats were pair fed with isocaloric liquid diets containing 0% or 37% ethanol (caloric) for 8 weeks. After 3 weeks on the diets, rats were treated with vehicle, or a PPAR-α, PPAR-δ, or PPAR-γ agonist twice weekly by i.p. injection. Ethanol-fed rats developed steatohepatitis with disordered hepatic chord architecture, mega-mitochondria, disruption of the RER, increased apoptosis, and increased 4-hydroxynonenal (HNE) and 3-nitrotyrosine (NTyr) immunoreactivity. PPAR-δ and PPAR-γ agonists reduced the severity of steatohepatitis, and restored the hepatic chord-like architectural, mitochondrial morphology, and RER organization, and the PPAR-δ agonist significantly reduced hepatic HNE. On the other hand, prominent RER tubule dilation, which could reflect ER stress, persisted in ethanol-exposed, PPAR-γ treated but not PPAR-δ treated livers. The PPAR-α agonist exacerbated both steatohepatitis and formation of mega-mitochondria, and it failed to restore RER architecture or lower biochemical indices of oxidative stress. In conclusion, improved hepatic insulin responsiveness and decreased inflammation resulting from PPAR-δ or PPAR-γ agonist treatments of alcohol-induced steatohepatitis are likely mediated by enhanced signaling through metabolic pathways with attendant reductions in ER stress, oxidative stress, and mitochondrial dysfunction.
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Affiliation(s)
- Teresa Ramirez
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Ming Tong
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Carol A Ayala
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Paul R Monfils
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Paul N McMillan
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Valerie Zabala
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Jack R Wands
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
| | - Suzanne M de la Monte
- Liver Research Center and Departments of Medicine, Pathology, Neurology, and Neurosurgery, Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA
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de la Monte SM. Triangulated mal-signaling in Alzheimer's disease: roles of neurotoxic ceramides, ER stress, and insulin resistance reviewed. J Alzheimers Dis 2012; 30 Suppl 2:S231-49. [PMID: 22337830 PMCID: PMC4550324 DOI: 10.3233/jad-2012-111727] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ceramides are lipid signaling molecules that cause cytotoxicity and cell death mediated by insulin resistance, inflammation, and endoplasmic reticulum (ER) stress. However, insulin resistance dysregulates lipid metabolism, which promotes ceramide accumulation with attendant inflammation and ER stress. Herein, we discuss two major pathways, extrinsic and intrinsic, that converge and often overlap in propagating AD-type neurodegeneration via a triangulated mal-signaling network. First, we review evidence that systemic insulin resistance diseases linked to obesity, type 2 diabetes, and non-alcoholic steatohepatitis promote neurodegeneration. Mechanistically, we propose that toxic ceramides generated in extra-CNS tissues (e.g., liver) get released into peripheral blood, and subsequently transit across the blood-brain barrier into the brain where they induce brain insulin resistance, inflammation, and cell death (extrinsic pathway). Then we discuss the role of the intrinsic pathway of neurodegeneration which is mediated by endogenous or primary brain insulin/IGF resistance, and impairs neuronal and oligodendrocyte survival, energy metabolism, membrane integrity, cytoskeletal function, and AβPP-Aβ secretion. The end result is increased ER stress and ceramide generation, which exacerbate brain insulin resistance, cell death, myelin degeneration, and neuroinflammation. Altogether, the data suggest that the triangulated mal-signaling network mediated by toxic ceramides, ER stress, and insulin resistance should be targeted to disrupt positive feedback loops that drive the AD neurodegeneration cascade.
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Affiliation(s)
- Suzanne M de la Monte
- Department of Pathology (Neuropathology), Rhode Island Hospital and The Warren Alpert Medical School of Brown University, Providence, RI, USA. SuzanneDeLaMonte
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Abstract
BACKGROUND/AIMS We have compared dendritic cell (DC) function derived from the alcoholic liver disease (ALD) sensitive Long-Evans (LE) and resistant Fischer rat strains to determine if the influence of ethanol on DCs was dependent on ALD. METHODS The LE and Fischer rats were fed an ethanol-containing or isocaloric control liquid diet for 8 weeks and comparisons were made to LE rats injected with thioacetamide as a liver disease control. DCs were isolated from the spleen after expansion with human Fms-like tyrosine kinase receptor 3 ligand plasmid. Maturation markers CD86, CD80, CD40 and MHC-II were analysed by flow cytometry with or without lipopolysaccharide and poly I:C stimulation. Production of tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), interleukin (IL)-12p40 and IL-10 cytokines and the antigen presentation ability of DCs was determined. RESULTS Only LE rats developed ALD characterized by liver injury, elevated alanine aminotransferase levels and steatosis; CD86 and CD40 expression was decreased in LE but not Fischer rats. Reduced TNF-α, IFN-γ, IL-12, proinflammatory and enhanced IL-10 cytokine production was found in DCs isolated from ethanol-fed LE but not Fischer rats. Allostimulatory activity was reduced in LE compared with the Fischer strain. In contrast, DCs isolated from thioacetamide-induced liver damage displayed a reduction only in IL-12p40; TNF-α, IL-10 and IFN-α production as well as antigen presenting ability remained intact compared with controls. CONCLUSIONS ALD sensitive LE rats exhibited characteristics of a suppressed DC phenotype that was not observed following thioacetamide-induced liver disease, which suggests an important role for ALD in altering the host cellular and humoral immune responses.
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Affiliation(s)
- Dechun Feng
- The Department of Medicine, Liver Research Center, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, RI 02905, USA
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Setshedi M, Longato L, Petersen DR, Ronis M, Chen WC, Wands JR, de la Monte SM. Limited therapeutic effect of N-acetylcysteine on hepatic insulin resistance in an experimental model of alcohol-induced steatohepatitis. Alcohol Clin Exp Res 2011; 35:2139-51. [PMID: 21790669 DOI: 10.1111/j.1530-0277.2011.01569.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Alcohol-related steatohepatitis is associated with increased oxidative stress, DNA damage, lipotoxicity, and insulin resistance in liver. As inflammation and oxidative stress can promote insulin resistance, effective treatment with antioxidants, for example, N-acetylcysteine (NAC), may restore ethanol-impaired insulin signaling in the liver. METHODS Adult male Sprague-Dawley rats were fed for 130 days with liquid diets containing 0 or 37% ethanol by caloric content, and simultaneously treated with vehicle or NAC. Chow-fed controls were studied in parallel. Liver tissues were used for histopathology, cytokine activation, and insulin/IGF-1 signaling assays. RESULTS We observed significant positive trends of increasing severity of steatohepatitis (p = 0.016) with accumulation of neutral lipid (p = 0.0002) and triglycerides (p = 0.0004) from chow to control, to the ethanol diet, irrespective of NAC treatment. In ethanol-fed rats, NAC reduced inflammation, converted the steatosis from a predominantly microvesicular to a mainly macrovesicular histological pattern, reduced pro-inflammatory cytokine gene expression, ceramide load, and acid sphingomyelinase activity, and increased expression of IGF-1 receptor and IGF-2 in liver. However, NAC did not abrogate ethanol-mediated impairments in signaling through insulin/IGF-1 receptors, IRS-1, Akt, GSK-3β, or p70S6K, nor did it significantly reduce pro-ceramide or GM3 ganglioside gene expression in liver. CONCLUSIONS Antioxidant treatments reduce the severity of chronic alcohol-related steatohepatitis, possibly because of the decreased expression of inflammatory mediators and ceramide accumulation, but they do not restore insulin/IGF-1 signaling in liver, most likely due to persistent elevation of GM3 synthase expression. Effective treatment of alcohol-related steatohepatitis most likely requires dual targeting of oxidative stress and insulin/IGF resistance.
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Affiliation(s)
- Mashiko Setshedi
- Department of Medicine, Brown University, Providence, Rhode Island, USA
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Shearn CT, Fritz KS, Reigan P, Petersen DR. Modification of Akt2 by 4-Hydroxynonenal Inhibits Insulin-Dependent Akt Signaling in HepG2 Cells. Biochemistry 2011; 50:3984-96. [DOI: 10.1021/bi200029w] [Citation(s) in RCA: 238] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- C. T. Shearn
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
| | - K. S. Fritz
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
| | - P. Reigan
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
| | - Dennis R. Petersen
- Department of Pharmaceutical Sciences, University of Colorado—Denver, Aurora, Colorado 80045, United States
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de la Monte SM, Pang M, Chaudhry R, Duan K, Longato L, Carter J, Ouh J, Wands JR. Peroxisome proliferator-activated receptor agonist treatment of alcohol-induced hepatic insulin resistance. Hepatol Res 2011; 41:386-98. [PMID: 21426453 PMCID: PMC3399907 DOI: 10.1111/j.1872-034x.2011.00775.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
AIM Chronic ethanol exposure impairs insulin signaling in the liver. Peroxisome-proliferator activated receptor (PPAR) agonists function as insulin sensitizers and are used to treat type 2 diabetes mellitus. We examined the therapeutic effectiveness of PPAR agonists in reducing alcoholic hepatitis and hepatic insulin resistance in a model of chronic ethanol feeding. METHODS Adult male Long Evans rats were pair fed with isocaloric liquid diets containing 0% (control) or 37% ethanol (caloric content; 9.2% v/v) for 8 weeks. After 3 weeks on the diets, the rats were treated with vehicle, or a PPAR-α, PPAR-δ or PPAR-γ agonist twice weekly by i.p. injection. Livers were harvested for histopathological, gene expression (reverse transcription polymerase chain reaction), protein (western and ELISA) and receptor binding studies. RESULTS Ethanol-fed rats developed steatohepatitis with disordered hepatic chord architecture, increased hepatocellular apoptosis, reduced binding to the insulin, insulin-like growth factor (IGF)-1 and IGF-2 receptors, and decreased expression of glyceraldehyde-3-phosphate dehydrogenase and aspartyl-(asparaginyl)-β-hydroxylase (mediating remodeling), which are regulated by insulin/IGF signaling. PPAR-α, PPAR-δ or PPAR-γ agonist treatments reduced the severity of ethanol-mediated liver injury, including hepatic architectural disarray and steatosis. In addition, PPAR-δ and PPAR-γ agonists reduced insulin/IGF resistance and increased insulin/IGF-responsive gene expression. CONCLUSION PPAR agonists may help reduce the severity of chronic ethanol-induced liver injury and insulin/IGF resistance, even in the context of continued high-level ethanol consumption.
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Affiliation(s)
- Suzanne M de la Monte
- Liver Research Center and Departments of Medicine and Pathology, Warren Alpert Medical School of Brown University, Providence, Rhode Island, USA
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Mellion M, Gilchrist JM, de la Monte S. Alcohol-related peripheral neuropathy: nutritional, toxic, or both? Muscle Nerve 2011; 43:309-16. [PMID: 21321947 PMCID: PMC4551507 DOI: 10.1002/mus.21946] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Alcohol-related peripheral neuropathy (ALN) is a potentially debilitating complication of alcoholism that results in sensory, motor, and autonomic dysfunction. Unfortunately, ALN is rarely discussed as a specific disease entity in textbooks because it is widely assumed to primarily reflect consequences of nutritional deficiency. This hypothesis is largely based on observations first made over eight decades ago when it was demonstrated that thiamine deficiency (beriberi) neuropathy was clinically similar to ALN. In recent studies, failure of thiamine treatment to reverse ALN, together with new information demonstrating clinical and electrophysiological distinctions between ALN and nutritional deficiency neuropathies, suggests that alcohol itself may significantly predispose and enhance development of neuropathy in the appropriate clinical setting. We reviewed the evidence on both sides and conclude that ALN should be regarded as a toxic rather than nutritional neuropathy.
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Affiliation(s)
- Michelle Mellion
- Department of Neurology, Rhode Island Hospital, Warren Alpert Medical School of Brown University, Medical Office Center, 2 Dudley Street, Suite 555, Providence, Rhode Island 02905, USA.
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Akiyama T, Mizuta T, Kawazoe S, Eguchi Y, Kawaguchi Y, Takahashi H, Ozaki I, Fujimoto K. Body mass index is associated with age-at-onset of HCV-infected hepatocellular carcinoma patients. World J Gastroenterol 2011; 17:914-21. [PMID: 21412500 PMCID: PMC3051141 DOI: 10.3748/wjg.v17.i7.914] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Revised: 09/29/2010] [Accepted: 10/06/2010] [Indexed: 02/06/2023] Open
Abstract
AIM To identify factors associated with the age at onset of hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC). METHODS Five hundred and fifty-six consecutive patients positive for HCV antibody and treatment-naïve HCC diagnosed between 1995 and 2004 were analyzed. Patients were classified into three groups according to age at HCC onset: < 60 years (n = 79), 60-79 years (n = 439), or ≥ 80 years (n = 38). Differences among groups in terms of sex, body mass index (BMI), lifestyle characteristics, and liver function were assessed. Factors associated with HCC onset in patients < 60 or ≥ 80 years were analyzed by logistic regression analysis. RESULTS Significant differences emerged for sex, BMI, degree of smoking and alcohol consumption, mean bilirubin, alanine aminotransferase (ALT), and γ-glutamyl transpeptidase (GGT) levels, prothrombin activity, and platelet counts. The mean BMI values of male patients > 60 years old were lower and mean BMI values of female patients < 60 years old were higher than those of the general Japanese population. BMI > 25 kg/m² [hazard ratio (HR), 1.8, P = 0.045], excessive alcohol consumption (HR, 2.5, P = 0.024), male sex (HR, 3.6, P = 0.002), and GGT levels > 50 IU/L (HR, 2.4, P = 0.014) were independently associated with HCC onset in patients < 60 years. Low ALT level was the only factor associated with HCC onset in patients aged ≥ 80 years. CONCLUSION Increased BMI is associated with increased risk for early HCC development in HCV-infected patients. Achieving recommended BMI and reducing alcohol intake could help prevent hepatic carcinogenesis.
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Derdak Z, Lang CH, Villegas KA, Tong M, Mark NM, de la Monte SM, Wands JR. Activation of p53 enhances apoptosis and insulin resistance in a rat model of alcoholic liver disease. J Hepatol 2011; 54:164-72. [PMID: 20961644 PMCID: PMC2994971 DOI: 10.1016/j.jhep.2010.08.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 07/16/2010] [Accepted: 08/23/2010] [Indexed: 01/26/2023]
Abstract
BACKGROUND & AIMS Chronic ethanol consumption in the Long-Evans (LE) rat has been associated with hepatic p53 activation, and inhibition of the insulin/PI3K/AKT signal transduction cascade due to increased expression of PTEN. We hypothesize that p53 activation and altered insulin signaling may influence the susceptibility of rats to ethanol-induced liver damage. Furthermore, p53 not only activates programmed cell death pathways and suppresses hepatocellular survival signals, but also promotes gluconeogenesis to increase systemic insulin resistance due to a novel metabolic function. METHODS Fischer (F), Sprague-Dawley (SD) and LE rats were fed ethanol-containing or control liquid diet for 8 weeks. Histopathological and biochemical changes were assessed. RESULTS Here, we demonstrate that chronic ethanol feeding in rats promotes p53 activation, hepatic steatosis, oxidative stress, PUMA, and PTEN expression, which contribute to hepatocellular death and diminished insulin signaling in the liver. Such changes are pronounced in the LE, less prominent in SD, and virtually absent in the F rat strain. More importantly, there is activation of Tp53-induced glycolysis and apoptosis regulator (TIGAR) in the ethanol-fed LE rat. This event generates low hepatic fructose-2,6-bisphosphate (Fru-2,6-P₂) levels, reduced lactate/pyruvate ratio and may contribute to increased basal glucose turnover and high residual hepatic glucose production during euglycemic hyperinsulinemic clamp. CONCLUSIONS p53 activation correlates with the susceptibility to ethanol-induced liver damage in different rat strains. p53 not only orchestrates apoptosis and suppresses cell survival, but by activating TIGAR and decreasing hepatic Fru-2,6-P₂) levels it promotes insulin resistance and therefore, contributes to the metabolic abnormalities associated with hepatic steatosis.
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Affiliation(s)
- Zoltan Derdak
- Division of Gastroenterology and Liver Research Center, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI 02903, USA.
| | - Charles H. Lang
- Pennsylvania State University College of Medicine, Department of Cellular and Molecular Physiology, Hershey, PA 17033
| | - Kristine A. Villegas
- Division of Gastroenterology & Liver Research Center, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, 02903, USA
| | - Ming Tong
- Division of Gastroenterology & Liver Research Center, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, 02903, USA
| | - Nicholas M. Mark
- Division of Gastroenterology & Liver Research Center, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, 02903, USA
| | - Suzanne M. de la Monte
- Department of Pathology, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, 02903, USA
| | - Jack R. Wands
- Division of Gastroenterology & Liver Research Center, Warren Alpert Medical School of Brown University and Rhode Island Hospital, Providence, RI, 02903, USA
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DeNucci SM, Tong M, Longato L, Lawton M, Setshedi M, Carlson RI, Wands JR, de la Monte SM. Rat strain differences in susceptibility to alcohol-induced chronic liver injury and hepatic insulin resistance. Gastroenterol Res Pract 2010; 2010:312790. [PMID: 20814553 PMCID: PMC2931394 DOI: 10.1155/2010/312790] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 05/16/2010] [Accepted: 07/05/2010] [Indexed: 02/06/2023] Open
Abstract
The finding of more severe steatohepatitis in alcohol fed Long Evans (LE) compared with Sprague Dawley (SD) and Fisher 344 (FS) rats prompted us to determine whether host factors related to alcohol metabolism, inflammation, and insulin/IGF signaling predict proneness to alcohol-mediated liver injury. Adult FS, SD, and LE rats were fed liquid diets containing 0% or 37% (calories) ethanol for 8 weeks. Among controls, LE rats had significantly higher ALT and reduced GAPDH relative to SD and FS rats. Among ethanol-fed rats, despite similar blood alcohol levels, LE rats had more pronounced steatohepatitis and fibrosis, higher levels of ALT, DNA damage, pro-inflammatory cytokines, ADH, ALDH, catalase, GFAP, desmin, and collagen expression, and reduced insulin receptor binding relative to FS rats. Ethanol-exposed SD rats had intermediate degrees of steatohepatitis, increased ALT, ADH and profibrogenesis gene expression, and suppressed insulin receptor binding and GAPDH expression, while pro-inflammatory cytokines were similarly increased as in LE rats. Ethanol feeding in FS rats only reduced IL-6, ALDH1-3, CYP2E1, and GAPDH expression in liver. In conclusion, susceptibility to chronic steatohepatitis may be driven by factors related to efficiency of ethanol metabolism and degree to which ethanol exposure causes hepatic insulin resistance and cytokine activation.
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Affiliation(s)
- Sarah M. DeNucci
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
| | - Ming Tong
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
| | - Lisa Longato
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
| | - Margot Lawton
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
| | - Mashiko Setshedi
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
| | - Rolf I. Carlson
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
| | - Jack R. Wands
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
| | - Suzanne M. de la Monte
- Departments of Medicine and Pathology, Liver Research Center, Rhode Island Hospital and the Warren Alpert Medical School of Brown University, Pierre Galletti Research Building, 55 Claverick Street, Room 421, Providence, RI 02903, USA
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