Does nonalcoholic fatty liver disease cause cardiovascular disease? Current knowledge and gaps
TL;DR: There is presently no evidence that NAFLD diagnosis can be used as a tool to improve cardiovascular risk stratification and modify treatment, and genetic variants predisposing toNAFLD were not consistently associated with an increased risk of cardiovascular events.
About: This article is published in Atherosclerosis.The article was published on 2019-03-01. It has received 65 citations till now. The article focuses on the topics: Nonalcoholic fatty liver disease & Steatohepatitis.
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TL;DR: Recent evidence linking excessive fructose consumption to health risk markers and development of components of the Metabolic Syndrome is reviewed.
Abstract: Consumption of fructose, the sweetest of all naturally occurring carbohydrates, has increased dramatically in the last 40 years and is today commonly used commercially in soft drinks, juice, and baked goods. These products comprise a large proportion of the modern diet, in particular in children, adolescents, and young adults. A large body of evidence associate consumption of fructose and other sugar-sweetened beverages with insulin resistance, intrahepatic lipid accumulation, and hypertriglyceridemia. In the long term, these risk factors may contribute to the development of type 2 diabetes and cardiovascular diseases. Fructose is absorbed in the small intestine and metabolized in the liver where it stimulates fructolysis, glycolysis, lipogenesis, and glucose production. This may result in hypertriglyceridemia and fatty liver. Therefore, understanding the mechanisms underlying intestinal and hepatic fructose metabolism is important. Here we review recent evidence linking excessive fructose consumption to health risk markers and development of components of the Metabolic Syndrome.
142 citations
Cites background from "Does nonalcoholic fatty liver disea..."
...has raised the questions how the liver can handle extra influx of lipids and the consequences on lipoprotein metabolism and ultimately vascular health [9,10,13,41]....
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TL;DR: In this article, a review article discusses recent research addressing hepatic lipid synthesis, VLDL production, and lipoprotein internalization as well as the lipid exchange between adipose tissue and the liver in the context of metabolic-associated fatty liver disease.
Abstract: Background Non-alcoholic fatty liver disease, or as recently proposed ‘metabolic-associated fatty liver disease’ (MAFLD), is characterized by pathological accumulation of triglycerides and other lipids in hepatocytes. This common disease can progress from simple steatosis to steatohepatitis, and eventually end-stage liver diseases. MAFLD is closely related to disturbances in systemic energy metabolism, including insulin resistance and atherogenic dyslipidemia. Scope of review The liver is the central organ in lipid metabolism by secreting very low density lipoproteins (VLDL) and, on the other hand, by internalizing fatty acids and lipoproteins. This review article discusses recent research addressing hepatic lipid synthesis, VLDL production, and lipoprotein internalization as well as the lipid exchange between adipose tissue and the liver in the context of MAFLD. Major conclusions Liver steatosis in MAFLD is triggered by excessive hepatic triglyceride synthesis utilizing fatty acids derived from white adipose tissue (WAT), de novo lipogenesis (DNL) and endocytosed remnants of triglyceride-rich lipoproteins. In consequence of high hepatic lipid content, VLDL secretion is enhanced, which is the primary cause of complex dyslipidemia typical for subjects with MAFLD. Interventions reducing VLDL secretory capacity attenuate dyslipidemia while they exacerbate MAFLD, indicating that the balance of lipid storage versus secretion in hepatocytes is a critical parameter determining disease outcome. Proof of concept studies have shown that promoting lipid storage and energy combustion in adipose tissues reduces hepatic lipid load and thus ameliorates MAFLD. Moreover, hepatocellular triglyceride synthesis from DNL and WAT-derived fatty acids can be targeted to treat MAFLD. However, more research is needed to understand how individual transporters, enzymes, and their isoforms affect steatosis and dyslipidemia in vivo, and whether these two aspects of MAFLD can be selectively treated. Processing of cholesterol-enriched lipoproteins appears less important for steatosis. It may, however, modulate inflammation and consequently MAFLD progression.
111 citations
University of São Paulo1, Monterrey Institute of Technology and Higher Education2, Brigham and Women's Hospital3, Sultan Qaboos University4, University of Paris5, University of New South Wales6, Charles University in Prague7, University of Milan8, Laval University9, university of lille10, University of Colorado Denver11, Columbia University12, Université catholique de Louvain13, Jichi Medical University14, University of Oxford15, University of Tokyo16, University of Ulm17, Technische Universität München18, Institut national de la recherche agronomique19, Hotel Dieu Hospital20, Seoul National University Bundang Hospital21, University of Ottawa22, Complutense University of Madrid23, University of Copenhagen24, Copenhagen University Hospital25, University of Glasgow26, Boston Medical Center27, Imperial College London28, University Hospital Centre Zagreb29, Jaslok Hospital30, University of Tsukuba31, Mahidol University32, National Taiwan University33, University of Helsinki34, Sheba Medical Center35, Tel Aviv University36, Hacettepe University37, The Chinese University of Hong Kong38, Gentofte Hospital39, University of Lausanne40, Nanyang Technological University41, University of Western Australia42, Osaka University43, Chiba University44, University of Padua45
TL;DR: In this paper, the authors developed a selective peroxisome proliferator-activated receptor alpha modulator (SPPARMα) for the treatment of atherogenic dyslipidemia.
Abstract: In the era of precision medicine, treatments that target specific modifiable characteristics of high-risk patients have the potential to lower further the residual risk of atherosclerotic cardiovascular events. Correction of atherogenic dyslipidemia, however, remains a major unmet clinical need. Elevated plasma triglycerides, with or without low levels of high-density lipoprotein cholesterol (HDL-C), offer a key modifiable component of this common dyslipidemia, especially in insulin resistant conditions such as type 2 diabetes mellitus. The development of selective peroxisome proliferator-activated receptor alpha modulators (SPPARMα) offers an approach to address this treatment gap. This Joint Consensus Panel appraised evidence for the first SPPARMα agonist and concluded that this agent represents a novel therapeutic class, distinct from fibrates, based on pharmacological activity, and, importantly, a safe hepatic and renal profile. The ongoing PROMINENT cardiovascular outcomes trial is testing in 10,000 patients with type 2 diabetes mellitus, elevated triglycerides, and low levels of HDL-C whether treatment with this SPPARMα agonist safely reduces residual cardiovascular risk.
90 citations
TL;DR: From studies that used common variants in PNPLA3, TM6SF2 and GCKR as instruments to investigate the relationship between NAFLD and coronary artery disease (CAD), it appears that plasma lipids are an important mediator between NA FLD and CVD risk.
Abstract: Non-alcoholic fatty liver disease (NAFLD) is highly prevalent among individuals with type 2 diabetes. Although epidemiological studies have shown that NAFLD is associated with cardiovascular disease (CVD), it remains unknown whether NAFLD is an active contributor or an innocent bystander. Plasma lipids, low-grade inflammation, impaired fibrinolysis and hepatokines are potential mediators of the relationship between NAFLD and CVD. The Mendelian randomisation approach can help to make causal inferences. Studies that used common variants in PNPLA3, TM6SF2 and GCKR as instruments to investigate the relationship between NAFLD and coronary artery disease (CAD) have reported contrasting results. Variants in PNPLA3 and TM6SF2 were found to protect against CAD, whereas variants in GCKR were positively associated with CAD. Since all three genes have been associated with non-alcoholic steatohepatitis, the second stage of NAFLD, the question of whether low-grade inflammation is an important mediator of the relationship between NAFLD and CAD arises. In contrast, the differential effects of these genes on plasma lipids (i.e. lipid-lowering for PNPLA3 and TM6SF2, and lipid-raising for GCKR) strongly suggest that plasma lipids account for their differential effects on CAD risk. This concept has recently been confirmed in an extended set of 12 NAFLD susceptibility genes. From these studies it appears that plasma lipids are an important mediator between NAFLD and CVD risk. These findings have important clinical implications, particularly for the design of anti-NAFLD drugs that also affect lipid metabolism.
88 citations
01 Jan 2017
TL;DR: The Grading of Recommendations, Assessment Development, and Evaluation (GRADE) system as discussed by the authors provides a data-supported approach to the diagnostic, therapeutic, and preventive aspects of NAFLD care.
Abstract: This guidance provides a data-supported approach to the diagnostic, therapeutic, and preventive aspects of NAFLD care. A "Guidance" document is different from a "Guideline." Guidelines are developed by a multidisciplinary panel of experts and rate the quality (level) of the evidence and the strength of each recommendation using the Grading of Recommendations, Assessment Development, and Evaluation (GRADE) system. A guidance document is developed by a panel of experts in the topic, and guidance statements, not recommendations, are put forward to help clinicians understand and implement the most recent evidence. This article is protected by copyright. All rights reserved.
86 citations
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TL;DR: This guidance provides a data-supported approach to the diagnostic, therapeutic, and preventive aspects of NAFLD care.
4,431 citations
TL;DR: In this article, the authors quantified the biological sources of hepatic and plasma lipoprotein TAG in NAFLD patients, using stable isotopes for four days to label and track serum nonesterified fatty acids (NEFAs), dietary fatty acids, and those derived from the de novo lipogenesis (DNL) pathway, present in liver tissue and lipid TAG.
Abstract: Nonalcoholic fatty liver disease (NAFLD) is characterized by the accumulation of excess liver triacylglycerol (TAG), inflammation, and liver damage The goal of the present study was to directly quantify the biological sources of hepatic and plasma lipoprotein TAG in NAFLD Patients (5 male and 4 female; 44 ± 10 years of age) scheduled for a medically indicated liver biopsy were infused with and orally fed stable isotopes for 4 days to label and track serum nonesterified fatty acids (NEFAs), dietary fatty acids, and those derived from the de novo lipogenesis (DNL) pathway, present in liver tissue and lipoprotein TAG Hepatic and lipoprotein TAG fatty acids were analyzed by gas chromatography/mass spectrometry NAFLD patients were obese, with fasting hypertriglyceridemia and hyperinsulinemia Of the TAG accounted for in liver, 590% ± 99% of TAG arose from NEFAs; 261% ± 67%, from DNL; and 149% ± 70%, from the diet The pattern of labeling in VLDL was similar to that in liver, and throughout the 4 days of labeling, the liver demonstrated reciprocal use of adipose and dietary fatty acids DNL was elevated in the fasting state and demonstrated no diurnal variation These quantitative metabolic data document that both elevated peripheral fatty acids and DNL contribute to the accumulation of hepatic and lipoprotein fat in NAFLD
2,870 citations
TL;DR: Variation in PNPLA3 contributes to ancestry-related and inter-individual differences in hepatic fat content and susceptibility to NAFLD.
Abstract: Nonalcoholic fatty liver disease (NAFLD) is a burgeoning health problem of unknown etiology that varies in prevalence among ancestry groups. To identify genetic variants contributing to differences in hepatic fat content, we carried out a genome-wide association scan of nonsynonymous sequence variations (n = 9,229) in a population comprising Hispanic, African American and European American individuals. An allele in PNPLA3 (rs738409[G], encoding I148M) was strongly associated with increased hepatic fat levels (P = 5.9 x 10(-10)) and with hepatic inflammation (P = 3.7 x 10(-4)). The allele was most common in Hispanics, the group most susceptible to NAFLD; hepatic fat content was more than twofold higher in PNPLA3 rs738409[G] homozygotes than in noncarriers. Resequencing revealed another allele of PNPLA3 (rs6006460[T], encoding S453I) that was associated with lower hepatic fat content in African Americans, the group at lowest risk of NAFLD. Thus, variation in PNPLA3 contributes to ancestry-related and inter-individual differences in hepatic fat content and susceptibility to NAFLD.
2,651 citations
Virginia Commonwealth University1, Indiana University – Purdue University Indianapolis2, Virginia Mason Medical Center3, Case Western Reserve University4, Duke University5, University of California, San Francisco6, Saint Louis University7, University of California, San Diego8, Johns Hopkins University9, Washington University in St. Louis10, National Institutes of Health11
TL;DR: Vitamin E was superior to placebo for the treatment of nonalcoholic steatohepatitis in adults without diabetes, and significant benefits of pioglitazone were observed for some of the secondary outcomes.
Abstract: Background Nonalcoholic steatohepatitis is a common liver disease that can progress to cirrho sis. Currently, there is no established treatment for this disease. Methods We randomly assigned 247 adults with nonalcoholic steatohepatitis and without dia betes to receive pioglitazone at a dose of 30 mg daily (80 subjects), vitamin E at a dose of 800 IU daily (84 subjects), or placebo (83 subjects), for 96 weeks. The pri mary outcome was an improvement in histologic features of nonalcoholic steato hepatitis, as assessed with the use of a composite of standardized scores for steato sis, lobular inflammation, hepatocellular ballooning, and fibrosis. Given the two planned primary comparisons, P values of less than 0.025 were considered to indi cate statistical significance. Results Vitamin E therapy, as compared with placebo, was associated with a significantly higher rate of improvement in nonalcoholic steatohepatitis (43% vs. 19%, P = 0. 001), but the difference in the rate of improvement with pioglitazone as compared with placebo was not significant (34% and 19%, respectively; P = 0. 04). Serum alanine and aspartate aminotransferase levels were reduced with vitamin E and with pio glitazone, as compared with placebo (P<0.001 for both comparisons), and both agents were associated with reductions in hepatic steatosis (P = 0. 005 for vitamin E and P<0.001 for pioglitazone) and lobular inflammation (P = 0. 02 for vitamin E and P = 0. 004 for pioglitazone) but not with improvement in fibrosis scores (P = 0. 24 for vitamin E and P = 0. 12 for pioglitazone). Subjects who received pioglitazone gained more weight than did those who received vitamin E or placebo; the rates of other side effects were similar among the three groups. Conclusions Vitamin E was superior to placebo for the treatment of nonalcoholic steatohepatitis in adults without diabetes. There was no benefit of pioglitazone over placebo for the primary outcome; however, significant benefits of pioglitazone were observed for some of the secondary outcomes. (ClinicalTrials.gov number, NCT000 63622.)
2,632 citations
TL;DR: It is shown that AdipoR1 and AdIPoR2 serve as receptors for globular and full-length adiponectin and mediate increased AMP-activated protein kinase, peroxisome proliferator-activated receptor-alpha ligand activities, and glucose uptake and fatty-acid oxidation by adiponECTin.
Abstract: Metabolic syndrome is thought to result from obesity and obesity-linked insulin resistance. Obesity in adulthood is characterized by adipocyte hypertrophy. Adipose tissue participates in the regulation of energy homeostasis as an important endocrine organ that secretes a number of biologically active “adipokines.” Heterozygous peroxisome proliferator-activated receptor- knockout mice were protected from high-fat diet induced obesity, adipocyte hypertrophy, and insulin resistance. Systematic gene profiling analysis of these mice revealed that adiponectin/Acrp30 was overexpressed. Functional analyses including generation of adiponectin transgenic or knockout mice have revealed that adiponectin serves as an insulinsensitizing adipokine. In fact, obesity-linked down-regulation of adiponectin was a mechanism whereby obesity could cause insulin resistance and diabetes. Recently, we have cloned adiponectin receptors in the skeletal muscle (AdipoR1) and liver (AdipoR2), which appear to comprise a novel cell-surface receptor family. We showed that AdipoR1 and AdipoR2 serve as receptors for globular and full-length adiponectin and mediate increased AMP-activated protein kinase, peroxisome proliferator-activated receptorligand activities, and glucose uptake and fatty-acid oxidation by adiponectin. Obesity decreased expression levels of AdipoR1/R2, thereby reducing adiponectin sensitivity, which finally leads to insulin resistance, the so-called “vicious cycle.” Most recently, we showed that osmotin, which is a ligand for the yeast homolog of AdipoR (PHO36), activated AMPK via AdipoR in C2C12 myocytes. This may facilitate efficient development of adiponectin receptor agonists. Adiponectin receptor agonists and adiponectin sensitizers should serve as versatile treatment strategies for obesitylinkeddiseasessuchasdiabetesandmetabolicsyndrome.(Endocrine Reviews 26: 439–451, 2005)
2,525 citations