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Role of alcohol metabolism in non-alcoholic steatohepatitis.

ABSTRACT: BACKGROUND: Non-alcoholic steatohepatitis (NASH) is a serious form of non-alcoholic fatty liver disease (NAFLD), associated with obesity and insulin resistance. Previous studies suggested that intestinal bacteria produced more alcohol in obese mice than lean animals. METHODOLOGY/PRINCIPAL FINDINGS: To investigate whether alcohol is involved in the pathogenesis of NASH, the expression of inflammation, fibrosis and alcohol metabolism related genes in the liver tissues of NASH patients and normal controls (NCs) were examined by microarray (NASH, n = 7; NC, n = 4) and quantitative real-time PCR (NASH, n = 6; NC, n = 6). Genes related to liver inflammation and fibrosis were found to be elevated in NASH livers compared to normal livers. The most striking finding is the increased gene transcription of alcohol dehydrogenase (ADH) genes, genes for catalase and cytochrome P450 2E1, and aldehyde dehydrogenase genes. Immunoblot analysis confirmed the increased expression of ADH1 and ADH4 in NASH livers (NASH, n = 9; NC, n = 4). CONCLUSIONS/SIGNIFICANCE: The augmented activity of all the available genes of the pathways for alcohol catabolism suggest that 1) alcohol concentration was elevated in the circulation of NASH patients; 2) there was a high priority for the NASH livers to scavenge alcohol from the circulation. Our data is the first human evidence that suggests alcohol may contribute to the development of NAFLD.

SUBMITTER: Baker SS

PROVIDER: S-EPMC2833196 | biostudies-literature | 2010

REPOSITORIES: biostudies-literature

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Role of alcohol metabolism in non-alcoholic steatohepatitis.

Baker Susan S SS Baker Robert D RD Liu Wensheng W Nowak Norma J NJ Zhu Lixin L

PloS one 20100308 3

<h4>Background</h4>Non-alcoholic steatohepatitis (NASH) is a serious form of non-alcoholic fatty liver disease (NAFLD), associated with obesity and insulin resistance. Previous studies suggested that intestinal bacteria produced more alcohol in obese mice than lean animals.<h4>Methodology/principal findings</h4>To investigate whether alcohol is involved in the pathogenesis of NASH, the expression of inflammation, fibrosis and alcohol metabolism related genes in the liver tissues of NASH patients ...[more]

PMID: 20221393

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Project description:This paper is based upon the "Charles Lieber Satellite Symposia" organized by Manuela G. Neuman at the Research Society on Alcoholism (RSA) Annual Meetings, 2013 and 2014. The present review includes pre-clinical, translational and clinical research that characterize alcoholic liver disease (ALD) and non-alcoholic steatohepatitis (NASH). In addition, a literature search in the discussed area was performed. Strong clinical and experimental evidence lead to recognition of the key toxic role of alcohol in the pathogenesis of ALD. The liver biopsy can confirm the etiology of NASH or alcoholic steatohepatitis (ASH) and assess structural alterations of cells, their organelles, as well as inflammatory activity. Three histological stages of ALD are simple steatosis, ASH, and chronic hepatitis with hepatic fibrosis or cirrhosis. These latter stages may also be associated with a number of cellular and histological changes, including the presence of Mallory's hyaline, megamitochondria, or perivenular and perisinusoidal fibrosis. Genetic polymorphisms of ethanol metabolizing enzymes such as cytochrome p450 (CYP) 2E1 activation may change the severity of ASH and NASH. Alcohol mediated hepatocarcinogenesis, immune response to alcohol in ASH, as well as the role of other risk factors such as its co-morbidities with chronic viral hepatitis in the presence or absence of human immunodeficiency virus are discussed. Dysregulation of hepatic methylation, as result of ethanol exposure, in hepatocytes transfected with hepatitis C virus (HCV), illustrates an impaired interferon signaling. The hepatotoxic effects of ethanol undermine the contribution of malnutrition to the liver injury. Dietary interventions such as micro and macronutrients, as well as changes to the microbiota are suggested. The clinical aspects of NASH, as part of metabolic syndrome in the aging population, are offered. The integrative symposia investigate different aspects of alcohol-induced liver damage and possible repair. We aim to (1) determine the immuno-pathology of alcohol-induced liver damage, (2) examine the role of genetics in the development of ASH, (3) propose diagnostic markers of ASH and NASH, (4) examine age differences, (5) develop common research tools to study alcohol-induced effects in clinical and pre-clinical studies, and (6) focus on factors that aggravate severity of organ-damage. The intention of these symposia is to advance the international profile of the biological research on alcoholism. We also wish to further our mission of leading the forum to progress the science and practice of translational research in alcoholism.

Project description:The mechanisms underlying the progression of non-alcoholic steatohepatitis (NASH) are not completely elucidated. In this study we have integrated gene expression profiling of liver biopsies of NASH patients with translational studies in a mouse model of steatohepatitis and with pharmacological interventions in isolated hepatocytes to identify a novel mechanism implicated in the pathogenesis of NASH. By using high-density oligonucleotide microarray analysis we identified a significant enrichment of known genes involved in the multi-step catalysis of long chain polyunsaturated fatty acids, including delta-5 and 6 desaturases. A combined inhibitor of delta-5 and delta-6 desaturases significantly reduced intracellular lipid accumulation and inflammatory gene expression in isolated hepatocytes. Gas chromatography analysis revealed impaired delta-5 desaturase activity toward the omega-3 pathway in livers from mice with high-fat diet (HFD)-induced NASH. Consistently, restoration of omega-3 index in transgenic fat-1 mice expressing an omega-3 desaturase, which allows the endogenous conversion of omega-6 into omega-3 fatty acids, produced a significant reduction in hepatic insulin resistance, hepatic steatosis, macrophage infiltration and necroinflammatory liver injury, accompanied by attenuated expression of genes involved in inflammation, fatty acid uptake and lipogenesis. These results were comparable to those obtained in a group of mice receiving a HFD supplemented with EPA/DHA. Of interest, hepatocytes from fat-1 mice or supplemented with EPA exhibited synergistic anti-steatotic and anti-inflammatory actions with the delta-5/ delta-6 inhibitor. Conclusion: These findings indicate that both endogenous and exogenous restoration of the hepatic balance between omega-6 and omega-3 fatty acids and/or modulation of desaturase activities exert preventive actions in NASH. The complete database comprised the expression measurements of 18185 genes for liver sample groups: 8 non-alcoholic steatohepatitis (NASH ) and 7 control samples. This dataset is part of the TransQST collection.

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Role of alcohol metabolism in non-alcoholic steatohepatitis.

Publications

Role of alcohol metabolism in non-alcoholic steatohepatitis.

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