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Increasing Dietary Medium-Chain Fatty Acid Ratio Mitigates High-fat Diet-Induced Non-Alcoholic Steatohepatitis by Regulating Autophagy.

ABSTRACT: Previous studies have demonstrated that saturated fatty acids (SFAs) are more lipotoxic than unsaturated fatty acids (UFAs) in inhibiting hepatic autophagy and promoting non-alcoholic steatohepatitis (NASH). However, there have been few studies have investigated the effects of carbon chain length on SFA-induced autophagy impairment and lipotoxicity. To investigate whether SFAs with shorter carbon chain lengths have differential effects on hepatic autophagy and NASH development, we partially replaced lard with coconut oil to elevate the ratio of medium-chain fatty acids (MCFAs) to long-chain fatty acids (LCFAs) in a mouse high-fat diet (HFD) and fed mice for 16 weeks. In addition, we treated HepG2 cells with different combinations of fatty acids to study the mechanisms of MCFAs-mediated hepatic protections. Our results showed that increasing dietary MCFA/LCFA ratio mitigated HFD-induced Type 2 diabetes and NASH in mice. Importantly, we demonstrated that increased MCFA ratio exerted its protective effects by restoring Rubicon-suppressed autophagy. Our study suggests that the relative amount of LCFAs and MCFAs in the diet, in addition to the amount of SFAs, can significantly contribute to autophagy impairment and hepatic lipotoxicity. Collectively, we propose that increasing dietary MCFAs could be an alternative therapeutic and prevention strategy for Type 2 diabetes and NASH.

SUBMITTER: Wang ME

PROVIDER: S-EPMC5656678 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Increasing Dietary Medium-Chain Fatty Acid Ratio Mitigates High-fat Diet-Induced Non-Alcoholic Steatohepatitis by Regulating Autophagy.

Wang Mu-En ME Singh Brijesh K BK Hsu Meng-Chieh MC Huang Chien C Yen Paul M PM Wu Leang-Shin LS Jong De-Shien DS Chiu Chih-Hsien CH

Scientific reports 20171025 1

Previous studies have demonstrated that saturated fatty acids (SFAs) are more lipotoxic than unsaturated fatty acids (UFAs) in inhibiting hepatic autophagy and promoting non-alcoholic steatohepatitis (NASH). However, there have been few studies have investigated the effects of carbon chain length on SFA-induced autophagy impairment and lipotoxicity. To investigate whether SFAs with shorter carbon chain lengths have differential effects on hepatic autophagy and NASH development, we partially repl ...[more]

PMID: 29070903

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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:Non-alcoholic steatohepatitis (NASH) is a progressive form of non-alcoholic fatty liver disease (NAFLD) that causes cirrhosis and hepatocellular carcinoma. Iron is an essential trace element in the body; however, excess iron can cause tissue damage and dysfunction. Iron overload is often observed in patients with NASH, and the amount of iron accumulated in the liver positively correlates with the histological severity of NASH. Ferroptosis, a novel form of iron-dependent cell death, is caused by the accumulation of lipid peroxidation and oxidative stress and is related to NASH. In addition, ferroptosis is closely related to autophagy, an intracellular self-degradation process. Although autophagy has many beneficial effects, it may also be harmful to the organism, for example, inducing ferroptosis. It is unclear whether iron overload aggravates NASH via autophagy. The aim of this research is to determine the mechanism by which iron overload induces ferroptosis via autophagy and aggravates NASH. Stroke-prone spontaneously hypertensive rats (SHRSP5/Dmcr) were divided into two groups and fed a high-fat and high-cholesterol (HFC) diet for eight weeks. Iron dextran was administered to the Fe group in addition to the HFC diet. Blood analysis, histological staining, calcineurin activity assay, quantitative reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence staining, and electron microscopy were performed. The results showed that iron overload promoted autophagy via nuclear translocation of transcription factor EB (TFEB) and induced ferritinophagy, which is the autophagic degradation of ferritin. In addition, the HFC diet induced lipophagy, the autophagic degradation of lipid droplets. The Fe group also exhibited promoted ferroptosis and aggravated hepatic inflammation and fibrosis. In conclusion, iron overload accelerates ferritinophagy and lipophagy, aggravating NASH pathology via ferroptosis. These findings indicate the therapeutic potential of inhibiting autophagy and ferroptosis for treating NASH.

Project description:BackgroundNon-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. Autophagy plays a vital role in NAFLD development and progression. We aimed to establish a novel autophagy-related gene (ARG) signature as a therapeutic target in NAFLD patients based on high-throughput sequencing data.MethodsARGs obtained from the HAMdb and high-sequencing data obtained from the Gene Expression Omnibus (GEO) database were analyzed to identify differentially expressed ARGs (DEARGs) between normal and NASH tissues. Then, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed to explore potential biological and pathological functions of DEARGs. The protein-protein interaction (PPI) network of the DEARGs was established through the STRING website, and visualized by Cytoscape. In addition, hub genes were validated by an independent dataset GSE89632. Finally, we performed Gene Set Variation Analysis (GSVA) pathway-related analysis to identify the pivotal signaling pathways and genes for the progression of non-alcoholic fatty liver (NAFL) to non-alcoholic steatohepatitis (NASH).ResultsA total of 76 DEARGs were identified in the GSE126848 dataset, of which 45 genes were upregulated and 31 genes were downregulated. GO analysis showed that the biological functions of DEARGs focused primarily on autophagy, cellular response to external stimulus, fibroblast proliferation, late endosome, and ubiquitin protein ligase binding. KEGG pathway analysis showed that these DEARGs were mainly involved in the apoptosis, PI3K-Akt signaling pathway, and estrogen signaling pathway. Among DEGs, 9 most closely related genes were identified from the PPI network. Furthermore, NOS3, IGF1, VAMP8, FOS, and HMOX1 were verified in the GSE89632 dataset. At last, the MAPK signal pathway was identified as important pathway, and JUN was identified as a key gene involved in the progression from NAFL to NASH.ConclusionThis study may provide credible molecular biomarkers in terms of screening and diagnosis for NAFLD. Meanwhile, it also serves as a basis for exploring the molecular mechanisms underlying the progression of NAFL to NASH.

Project description:Background & aimsKetogenic medium-chain fatty acids (MCFAs) with profound health benefits are commonly found in dairy products, palm kernel oil and coconut oil. We hypothesize that magnesium (Mg) supplementation leads to enhanced gut microbial production of MCFAs and, in turn, increased circulating MCFAs levels.MethodsWe tested this hypothesis in the Personalized Prevention of Colorectal Cancer Trial (PPCCT) (NCT01105169), a double-blind 2 × 2 factorial randomized controlled trial enrolling 240 participants. Six 24-h dietary recalls were performed for all participants at the baseline and during the intervention period. Based on the baseline 24-h dietary recalls, the Mg treatment used a personalized dose of Mg supplementation that would reduce the calcium (Ca): Mg intake ratio to around 2.3. We measured plasma MCFAs, sugars, ketone bodies and tricarboxylic acid cycle (TCA cycle) metabolites using the Metabolon's global Precision Metabolomics™ LC-MS platform. Whole-genome shotgun metagenomics (WGS) sequencing was performed to assess microbiota in stool samples, rectal swabs, and rectal biopsies.ResultsPersonalized Mg treatment (mean dose 205.58 mg/day with a range from 77.25 to 389.55 mg/day) significantly increased the plasma levels of C7:0, C8:0, and combined C7:0 and C8:0 by 18.45%, 25.28%, and 24.20%, respectively, compared to 14.15%, 10.12%, and 12.62% decreases in the placebo arm. The effects remain significant after adjusting for age, sex, race and baseline level (P = 0.0126, P = 0.0162, and P = 0.0031, respectively) and FDR correction at 0.05 (q = 0.0324 for both C7:0 and C8:0). Mg treatment significantly reduced the plasma level of sucrose compared to the placebo arm (P = 0.0036 for multivariable-adjusted and P = 0.0216 for additional FDR correction model) whereas alterations in daily intakes of sucrose, fructose, glucose, maltose and C8:0 from baseline to the end of trial did not differ between two arms. Mediation analysis showed that combined C7:0 and C8:0 partially mediated the effects of Mg treatment on total and individual ketone bodies (P for indirect effect = 0.0045, 0.0043, and 0.03, respectively). The changes in plasma levels of C7:0 and C8:0 were significantly and positively correlated with the alterations in stool microbiome α diversity (r = 0.51, p = 0.0023 and r = 0.34, p = 0.0497, respectively) as well as in stool abundance for the signatures of MCFAs-related microbiota with acyl-ACP thioesterase gene producing C7:0 (r = 0.46, p = 0.0067) and C8:0 (r = 0.49, p = 0.003), respectively, following Mg treatment.ConclusionsOptimizing Ca:Mg intake ratios to around 2.3 through 12-week personalized Mg supplementation leads to increased circulating levels of MCFAs (i.e. C7:0 and C8:0), which is attributed to enhanced production from gut microbial fermentation and, maybe, sucrose consumption.

Dataset Information

Increasing Dietary Medium-Chain Fatty Acid Ratio Mitigates High-fat Diet-Induced Non-Alcoholic Steatohepatitis by Regulating Autophagy.

Publications

Increasing Dietary Medium-Chain Fatty Acid Ratio Mitigates High-fat Diet-Induced Non-Alcoholic Steatohepatitis by Regulating Autophagy.

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