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Nagarajan SR, Cross E, Sanna F, Hodson L. Dysregulation of hepatic metabolism with obesity: factors influencing glucose and lipid metabolism. Proc Nutr Soc 2022; 81:1-11. [PMID: 34726148 DOI: 10.1017/s0029665121003761] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The liver is a key metabolic organ that undertakes a multitude of physiological processes over the course of a day, including intrahepatic lipid and glucose metabolism which plays a key role in the regulation of systemic lipid and glucose concentrations. It serves as an intermediary organ between exogenous (dietary) and endogenous energy supply to extrahepatic organs. Thus, perturbations in hepatic metabolism can impact widely on metabolic disease risk. For example, the accumulation of intra-hepatocellular TAG (IHTG), for which adiposity is almost invariably a causative factor may result in dysregulation of metabolic pathways. Accumulation of IHTG is likely due to an imbalance between fatty acid delivery, synthesis and removal (via oxidation or export as TAG) from the liver; insulin plays a key role in all of these processes.
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Affiliation(s)
- S R Nagarajan
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - E Cross
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - F Sanna
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - L Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford, UK
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2
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Della Torre S. Beyond the X Factor: Relevance of Sex Hormones in NAFLD Pathophysiology. Cells 2021; 10:2502. [PMID: 34572151 PMCID: PMC8470830 DOI: 10.3390/cells10092502] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/12/2021] [Accepted: 09/14/2021] [Indexed: 12/12/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a major health issue worldwide, being frequently associated with obesity, unbalanced dietary regimens, and reduced physical activity. Despite their greater adiposity and reduced physical activity, women show a lower risk of developing NAFLD in comparison to men, likely a consequence of a sex-specific regulation of liver metabolism. In the liver, sex differences in the uptake, synthesis, oxidation, deposition, and mobilization of lipids, as well as in the regulation of inflammation, are associated with differences in NAFLD prevalence and progression between men and women. Given the major role of sex hormones in driving hepatic sexual dimorphism, this review will focus on the role of sex hormones and their signaling in the regulation of hepatic metabolism and in the molecular mechanisms triggering NAFLD development and progression.
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Affiliation(s)
- Sara Della Torre
- Department of Pharmaceutical Sciences, University of Milan, Via Balzaretti 9, 20133 Milan, Italy
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3
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Goldberg IJ, Cabodevilla AG, Samovski D, Cifarelli V, Basu D, Abumrad NA. Lipolytic enzymes and free fatty acids at the endothelial interface. Atherosclerosis 2021; 329:1-8. [PMID: 34130222 DOI: 10.1016/j.atherosclerosis.2021.05.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/12/2021] [Accepted: 05/21/2021] [Indexed: 01/17/2023]
Abstract
Lipids released from circulating lipoproteins by intravascular action of lipoprotein lipase (LpL) reach parenchymal cells in tissues with a non-fenestrated endothelium by transfer through or around endothelial cells. The actions of LpL are controlled at multiple sites, its synthesis and release by myocytes and adipocytes, its transit and association with the endothelial cell luminal surface, and finally its activation and inhibition by a number of proteins and by its product non-esterified fatty acids. Multiple pathways mediate endothelial transit of lipids into muscle and adipose tissues. These include movement of fatty acids via the endothelial cell fatty acid transporter CD36 and movement of whole or partially LpL-hydrolyzed lipoproteins via other apical endothelial cell receptors such as SR-B1and Alk1. Lipids also likely change the barrier function of the endothelium and operation of the paracellular pathway around endothelial cells. This review summarizes in vitro and in vivo support for the key role of endothelial cells in delivery of lipids and highlights incompletely understood processes that are the focus of active investigation.
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Affiliation(s)
- Ira J Goldberg
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine, New York, NY, USA.
| | - Ainara G Cabodevilla
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine, New York, NY, USA
| | - Dmitri Samovski
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, Saint Louis, MO, USA
| | - Vincenza Cifarelli
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, Saint Louis, MO, USA
| | - Debapriya Basu
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine, New York, NY, USA
| | - Nada A Abumrad
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, Saint Louis, MO, USA.
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4
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Abstract
PURPOSE OF REVIEW Prevalence of metabolic-associated fatty liver disease (MAFLD) is increasing, and as pharmacological treatment does not exist, lifestyle interventions (i.e. diet and exercise) represent the cornerstone management and treatment strategy. Although the available data clearly demonstrate that changes in lifestyle influence intrahepatic triglyceride (IHTG) content, the mechanisms through which this is achieved are seldom investigated. Here, we review recent evidence demonstrating the influence of lifestyle interventions on hepatic fatty acid metabolism and IHTG content. RECENT FINDINGS Diet and exercise influence IHTG content through various, and often interrelated factors. These include alterations in whole-body and tissue-specific insulin sensitivity, which may influence the flux of fatty acid and lipogenic substrates to the liver, and changes in intrahepatic fatty acid synthesis and partitioning. Notably, there are only a few studies that have investigated intrahepatic fatty acid metabolism in vivo in humans before and after an intervention. SUMMARY Lifestyle interventions represent an effective means of influencing hepatic fatty acid metabolism. IHTG content is decreased without weight-loss either through exercise or by changing the macronutrient composition of the diet, although what the optimal macronutrient composition is to achieve this has yet to be defined.
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Affiliation(s)
- Sion A Parry
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford
| | - Mark C Turner
- Research Centre for Sport, Exercise and Life Sciences, Coventry University, Coventry
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford
- Oxford NIHR Biomedical Research Centre, Churchill Hospital, Oxford, UK
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5
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Ness KM, Strayer SM, Nahmod NG, Schade MM, Chang AM, Shearer GC, Buxton OM. Four nights of sleep restriction suppress the postprandial lipemic response and decrease satiety. J Lipid Res 2019; 60:1935-1945. [PMID: 31484696 DOI: 10.1194/jlr.p094375] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 08/20/2019] [Indexed: 12/16/2022] Open
Abstract
Chronic sleep restriction, or inadequate sleep, is associated with increased risk of cardiometabolic disease. Laboratory studies demonstrate that sleep restriction causes impaired whole-body insulin sensitivity and glucose disposal. Evidence suggests that inadequate sleep also impairs adipose tissue insulin sensitivity and the NEFA rebound during intravenous glucose tolerance tests, yet no studies have examined the effects of sleep restriction on high-fat meal lipemia. We assessed the effect of 5 h time in bed (TIB) per night for four consecutive nights on postprandial lipemia following a standardized high-fat dinner (HFD). Furthermore, we assessed whether one night of recovery sleep (10 h TIB) was sufficient to restore postprandial metabolism to baseline. We found that postprandial triglyceride (TG) area under the curve was suppressed by sleep restriction (P = 0.01), but returned to baseline values following one night of recovery. Sleep restriction decreased NEFAs throughout the HFD (P = 0.02) and NEFAs remained suppressed in the recovery condition (P = 0.04). Sleep restriction also decreased participant-reported fullness or satiety (P = 0.03), and decreased postprandial interleukin-6 (P < 0.01). Our findings indicate that four nights of 5 h TIB per night impair postprandial lipemia and that one night of recovery sleep may be adequate for recovery of TG metabolism, but not for markers of adipocyte function.
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Affiliation(s)
- Kelly M Ness
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802.,Departments of Biobehavioral Health Pennsylvania State University, University Park, PA 16802.,Nutritional Sciences, Pennsylvania State University, University Park, PA 16802
| | - Stephen M Strayer
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802.,Departments of Biobehavioral Health Pennsylvania State University, University Park, PA 16802
| | - Nicole G Nahmod
- Departments of Biobehavioral Health Pennsylvania State University, University Park, PA 16802
| | - Margeaux M Schade
- Departments of Biobehavioral Health Pennsylvania State University, University Park, PA 16802
| | - Anne-Marie Chang
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802.,Departments of Biobehavioral Health Pennsylvania State University, University Park, PA 16802.,College of Nursing, Pennsylvania State University, University Park, PA 16802
| | - Gregory C Shearer
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802.,Nutritional Sciences, Pennsylvania State University, University Park, PA 16802
| | - Orfeu M Buxton
- Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802 .,Departments of Biobehavioral Health Pennsylvania State University, University Park, PA 16802.,Division of Sleep Medicine, Harvard Medical School, Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, and Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA 20115
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6
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[ 18F]BODIPY-triglyceride-containing chylomicron-like particles as an imaging agent for brown adipose tissue in vivo. Sci Rep 2019; 9:2706. [PMID: 30804455 PMCID: PMC6389948 DOI: 10.1038/s41598-019-39561-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 01/16/2019] [Indexed: 12/23/2022] Open
Abstract
Brown adipose tissue (BAT) is present in human adults and the current gold standard to visualize and quantify BAT is [18F]FDG PET-CT. However, this method fails to detect BAT under insulin-resistant conditions associated with ageing and weight gain, such as type 2 diabetes. The aim of this study was to develop a novel triglyceride-based tracer for BAT. For this purpose we designed a dual-modal fluorescent/PET fatty acid tracer based on commercially available BODIPY-FL-C16, which can be esterified to its correspondent triglyceride, radiolabeled and incorporated into pre-synthesized chylomicron-like particles. BODIPY-FL-C16 was coupled to 1,2-diolein with a subsequent radiolabeling step resulting in [18F]BODIPY-C16-triglyceride that was incorporated into chylomicron-like particles. Various quality control steps using fluorescent and radioactive methods were conducted before BAT visualization was tested in mice. Triglyceride synthesis, radiolabeling and subsequent incorporation into chylomicron-like particles was carried out in decent yields. This radiotracer appeared able to visualize BAT in vivo, and the uptake of the radiotracer was stimulated by cold exposure. The here reported method can be used to incorporate radiolabeled triglycerides into pre-synthesized chylomicron-like particles. Our approach is feasible to visualize and quantify the uptake of triglyceride-derived fatty acids by BAT.
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7
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Piché ME, Parry SA, Karpe F, Hodson L. Chylomicron-Derived Fatty Acid Spillover in Adipose Tissue: A Signature of Metabolic Health? J Clin Endocrinol Metab 2018; 103:25-34. [PMID: 29099975 PMCID: PMC5761493 DOI: 10.1210/jc.2017-01517] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/27/2017] [Indexed: 12/29/2022]
Abstract
Context and Objectives Spillover of fatty acids (FAs) into the plasma nonesterified fatty acid (NEFA) pool, because of an inability of adipose tissue (AT) to accommodate sufficient fat uptake, has been suggested to contribute to obesity-related insulin resistance. Using specific labeling techniques, we compared the proportion of spillover-derived NEFA across a range of adiposity. Participants and Methods Seventy-one healthy men and women were fed a mixed meal (40 g fat) containing [U13C]palmitate to assess the contribution of chylomicron-derived spillover FAs. To investigate subcutaneous abdominal-specific spillover, arteriovenous difference and stable-isotope methodologies were used in substudy (six men, six women). Results Chylomicron-derived FA spillover was higher in individuals with a BMI <25 kg/m2 (n = 18) compared with those with a BMI ≥25 kg/m2 (n = 53) (22.2 ± 1.6% vs 18.6 ± 0.7%, P = 0.02). Women had higher chylomicron-derived FA spillover than age- and BMI-matched men (21.9 ± 1.1% vs 15.0 ± 1.6%, P = 0.001). Assessing spillover across subcutaneous abdominal AT showed higher proportions in women than in men (28.5 ± 6.1% vs 9.9 ± 1.3%, P = 0.01). Conclusion There is a considerable degree of spillover FA into the systemic NEFA pool in the postprandial state; this process is greater and more dynamic in lean individuals and women. Contrary to general perception, spillover of chylomicron-derived FA into systemic circulation is a physiologically normal feature most easily observed in people with a higher capacity for clearance of plasma triglycerides, but does not appear to be a pathway providing excess NEFA in obesity.
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Affiliation(s)
- Marie-Eve Piché
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, United Kingdom
- Quebec Heart and Lung Institute, Laval University, Quebec G1V 4G5, Canada
| | - Siôn A. Parry
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, United Kingdom
| | - Fredrik Karpe
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, United Kingdom
- National Institute for Health Research Oxford Biomedical Research Centre, Oxford University Hospital Trusts, Oxford OX3 9DU, United Kingdom
| | - Leanne Hodson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford OX3 7LE, United Kingdom
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8
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Koopal C, Marais AD, Visseren FLJ. Familial dysbetalipoproteinemia: an underdiagnosed lipid disorder. Curr Opin Endocrinol Diabetes Obes 2017; 24:133-139. [PMID: 28098593 DOI: 10.1097/med.0000000000000316] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE OF REVIEW To review pathophysiological, epidemiological and clinical aspects of familial dysbetalipoproteinemia; a model disease for remnant metabolism and remnant-associated cardiovascular risk. RECENT FINDINGS Familial dysbetalipoproteinemia is characterized by remnant accumulation caused by impaired remnant clearance, and premature cardiovascular disease. Most familial dysbetalipoproteinemia patients are homozygous for apolipoprotein ε2, which is associated with decreased binding of apolipoprotein E to the LDL receptor. Although familial dysbetalipoproteinemia is an autosomal recessive disease in most cases, 10% is caused by autosomal dominant mutations. Of people with an ε2ε2 genotype 15% develops familial dysbetalipoproteinemia, which is associated with secondary risk factors, such as obesity and insulin resistance, that inhibit remnant clearance by degradation of the heparan sulfate proteoglycan receptor. The prevalence of familial dysbetalipoproteinemia ranges from 0.12 to 0.40% depending on the definition used. Clinical characteristics of familial dysbetalipoproteinemia are xanthomas and mixed hyperlipidemia (high total cholesterol and triglycerides); the primary lipid treatment goal in familial dysbetalipoproteinemia is non-HDL-cholesterol; and treatment consists of dietary therapy and treatment with statin and fibrate combination. SUMMARY Familial dysbetalipoproteinemia is a relatively common, though often not diagnosed, lipid disorder characterized by mixed hyperlipidemia, remnant accumulation and premature cardiovascular disease, which should be treated with dietary therapy and statin and fibrate combination.
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Affiliation(s)
- Charlotte Koopal
- aVascular Medicine, University Medical Center Utrecht, Utrecht, The Netherlands bDivision of Chemical Pathology, University of Cape Town Health Science Faculty and National Health Laboratory Service, Cape Town, South Africa
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9
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Love-Gregory L, Kraja AT, Allum F, Aslibekyan S, Hedman ÅK, Duan Y, Borecki IB, Arnett DK, McCarthy MI, Deloukas P, Ordovas JM, Hopkins PN, Grundberg E, Abumrad NA. Higher chylomicron remnants and LDL particle numbers associate with CD36 SNPs and DNA methylation sites that reduce CD36. J Lipid Res 2016; 57:2176-2184. [PMID: 27729386 DOI: 10.1194/jlr.p065250] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 09/28/2016] [Indexed: 12/18/2022] Open
Abstract
Cluster of differentiation 36 (CD36) variants influence fasting lipids and risk of metabolic syndrome, but their impact on postprandial lipids, an independent risk factor for cardiovascular disease, is unclear. We determined the effects of SNPs within a ∼410 kb region encompassing CD36 and its proximal and distal promoters on chylomicron (CM) remnants and LDL particles at fasting and at 3.5 and 6 h following a high-fat meal (Genetics of Lipid Lowering Drugs and Diet Network study, n = 1,117). Five promoter variants associated with CMs, four with delayed TG clearance and five with LDL particle number. To assess mechanisms underlying the associations, we queried expression quantitative trait loci, DNA methylation, and ChIP-seq datasets for adipose and heart tissues that function in postprandial lipid clearance. Several SNPs that associated with higher serum lipids correlated with lower adipose and heart CD36 mRNA and aligned to active motifs for PPARγ, a major CD36 regulator. The SNPs also associated with DNA methylation sites that related to reduced CD36 mRNA and higher serum lipids, but mixed-model analyses indicated that the SNPs and methylation independently influence CD36 mRNA. The findings support contributions of CD36 SNPs that reduce adipose and heart CD36 RNA expression to inter-individual variability of postprandial lipid metabolism and document changes in CD36 DNA methylation that influence both CD36 expression and lipids.
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Affiliation(s)
- Latisha Love-Gregory
- Department of Medicine, Center for Human Nutrition Washington University School of Medicine, St. Louis, MO 63110
| | - Aldi T Kraja
- Department of Genetics, Division of Statistical Genomics, Washington University School of Medicine, St. Louis, MO 63110
| | - Fiona Allum
- Department of Human Genetics, McGill University and Genome Quebec Innovation Centre, Montreal, Québec, Canada H3A 0G1
| | - Stella Aslibekyan
- Department of Epidemiology, University of Alabama, Birmingham, AL 35294
| | - Åsa K Hedman
- Departments of Medical Sciences and Molecular Epidemiology, and Science for Life Laboratory, Uppsala University, Uppsala 75185, Sweden
| | - Yanan Duan
- Department of Genetics, Division of Statistical Genomics, Washington University School of Medicine, St. Louis, MO 63110
| | - Ingrid B Borecki
- Department of Genetics, Division of Statistical Genomics, Washington University School of Medicine, St. Louis, MO 63110
| | - Donna K Arnett
- Department of Epidemiology, University of Alabama, Birmingham, AL 35294
| | - Mark I McCarthy
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK, and Oxford Centre for Diabetes, Endocrinology, and Metabolism and Oxford National Institute for Health Research Biomedical Research Centre, Churchill Hospital, Oxford OX3 7JU, UK
| | - Panos Deloukas
- William Harvey Research Institute, Queen Mary University of London, EC1M 6BQ London, UK
| | - Jose M Ordovas
- JM-USDA-Human Nutrition Research Center on Aging, Tufts University, Boston, MA 02111
| | - Paul N Hopkins
- Cardiovascular Genetics Research, University of Utah, Salt Lake City, UT 84132
| | - Elin Grundberg
- Department of Human Genetics, McGill University and Genome Quebec Innovation Centre, Montreal, Québec, Canada H3A 0G1
| | - Nada A Abumrad
- Department of Medicine, Center for Human Nutrition Washington University School of Medicine, St. Louis, MO 63110
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10
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Hersoug LG, Møller P, Loft S. Gut microbiota-derived lipopolysaccharide uptake and trafficking to adipose tissue: implications for inflammation and obesity. Obes Rev 2016; 17:297-312. [PMID: 26712364 DOI: 10.1111/obr.12370] [Citation(s) in RCA: 174] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 12/12/2022]
Abstract
The composition of the gut microbiota and excessive ingestion of high-fat diets (HFD) are considered to be important factors for development of obesity. In this review we describe a coherent mechanism of action for the development of obesity, which involves the composition of gut microbiota, HFD, low-grade inflammation, expression of fat translocase and scavenger receptor CD36, and the scavenger receptor class B type 1 (SR-BI). SR-BI binds to both lipids and lipopolysaccharide (LPS) from Gram-negative bacteria, which may promote incorporation of LPS in chylomicrons (CMs). These CMs are transported via lymph to the circulation, where LPS is transferred to other lipoproteins by translocases, preferentially to HDL. LPS increases the SR-BI binding, transcytosis of lipoproteins over the endothelial barrier,and endocytosis in adipocytes. Especially large size adipocytes with high metabolic activity absorb LPS-rich lipoproteins. In addition, macrophages in adipose tissue internalize LPS-lipoproteins. This may contribute to the polarization from M2 to M1 phenotype, which is a consequence of increased LPS delivery into the tissue during hypertrophy. In conclusion, evidence suggests that LPS is involved in the development of obesity as a direct targeting molecule for lipid delivery and storage in adipose tissue.
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Affiliation(s)
- L-G Hersoug
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - P Møller
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - S Loft
- Section of Environmental Health, Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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11
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Scarsi C, Levesque A, Lisi L, Navarra P. The free fractions of circulating docosahexaenoic acid and eicosapentenoic acid as optimal end-point of measure in bioavailability studies on n-3 fatty acids. Prostaglandins Leukot Essent Fatty Acids 2015; 96:11-6. [PMID: 25559240 DOI: 10.1016/j.plefa.2014.12.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Revised: 12/06/2014] [Accepted: 12/14/2014] [Indexed: 11/21/2022]
Abstract
The high complexity of n-3 fatty acids absorption process, along with the huge amount of endogenous fraction, makes bioavailability studies with these agents very challenging and deserving special consideration. In this paper we report the results of a bioequivalence study between a new formulation of EPA+DHA ethyl esters developed by IBSA Institut Biochimique and reference medicinal product present on the Italian market. Bioequivalence was demonstrated according to the criteria established by the EMA Guideline on the Investigation of Bioequivalence. We found that the free fractions represent a better and more sensitive end-point for bioequivalence investigations on n-3 fatty acids, since: (i) the overall and intra-subject variability of PK parameters was markedly lower compared to the same variability calculated on the total DHA and EPA fractions; (ii) the absorption process was completed within 4h, and the whole PK profile could be drawn within 12-15 h from drug administration.
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Affiliation(s)
- Claudia Scarsi
- IBSA Institut Biochimique SA, Via del Piano, 6915 Pambio-Noranco, Switzerland
| | - Ann Levesque
- inVentiv Health Clinical, 2500 Einstein, Québec, QC, Canada G1P 0A2
| | - Lucia Lisi
- Institute of Pharmacology, Catholic University Medical School, L.go F. Vito 1, 00168 Rome, Italy
| | - Pierluigi Navarra
- Institute of Pharmacology, Catholic University Medical School, L.go F. Vito 1, 00168 Rome, Italy.
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12
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Slivkoff-Clark KM, James AP, Mamo JC. The chronic effects of fish oil with exercise on postprandial lipaemia and chylomicron homeostasis in insulin resistant viscerally obese men. Nutr Metab (Lond) 2012; 9:9. [PMID: 22314022 PMCID: PMC3296659 DOI: 10.1186/1743-7075-9-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Accepted: 02/07/2012] [Indexed: 12/15/2022] Open
Abstract
Background Visceral obesity and insulin resistance are associated with a postprandial accumulation of atherogenic chylomicron remnants that is difficult to modulate with lipid-lowering therapies. Dietary fish oil and exercise are cardioprotective interventions that can significantly modify the metabolism of TAG-rich lipoproteins. In this study, we investigated whether chronic exercise and fish oil act in combination to affect chylomicron metabolism in obese men with moderate insulin resistance. Methods The single blind study tested the effect of fish oil, exercise and the combined treatments on fasting and postprandial chylomicron metabolism. Twenty nine men with metabolic syndrome were randomly assigned to take fish oil or placebo for four weeks, before undertaking an additional 12 week walking program. At baseline and at the end of each treatment, subjects were tested for concentrations of fasting apo B48, plasma lipids and insulin. Postprandial apo B48 and TAG kinetics were also determined following ingestion of a fat enriched meal. Results Combining fish oil and exercise resulted in a significant reduction in the fasting apo B48 concentration, concomitant with attenuation of fasting TAG concentrations and the postprandial TAGIAUC response (p < 0.05). Fish oil by itself reduced the postprandial TAG response (p < 0.05) but not postprandial apo B48 kinetics. Individual treatments of fish oil and exercise did not correspond with improvements in fasting plasma TAG and apo B48. Conclusion Fish oil was shown to independently improve plasma TAG homeostasis but did not resolve hyper-chylomicronaemia. Instead, combining fish oil with chronic exercise reduced the plasma concentration of pro-atherogenic chylomicron remnants; in addition it reduced the fasting and postprandial TAG response in viscerally obese insulin resistant subjects.
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Affiliation(s)
- Karin M Slivkoff-Clark
- School of Public Health, Curtin Health Innovation Research Institute and the Australian Technology Network, Centre for Metabolic Fitness, Curtin University, Bentley Campus, Kent St, Perth 6102, Australia.
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13
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Consumption of low doses of fat prevents the postprandial rise in chylomicron particle concentration and remnant accumulation in healthy normolipidaemic males. J Nutr Sci 2012; 1:e4. [PMID: 25191552 PMCID: PMC4153322 DOI: 10.1017/jns.2012.4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 05/22/2012] [Accepted: 05/22/2012] [Indexed: 11/16/2022] Open
Abstract
Chylomicron particles are continually synthesised and secreted from the intestine even in
the absence of ingested fat. It is possible that following consumption of low doses of fat
the basal level of chylomicron secretion and subsequent metabolism are sufficient to
metabolise this fat without an increase in postprandial chylomicron concentrations. To
test this hypothesis, healthy male subjects were randomised to receive, on three separate
occasions, meals containing a range of doses of fat (average 8·1–19 g) and effects on
postprandial lipaemia and chylomicron concentration were determined. Furthermore, to
delineate the effect on lipid-rich v. lipid-poor (remnant) forms lipid
levels were also determined in a density <1·006 g/ml fraction. Following
consumption of the very low dose of fat the postprandial concentration of chylomicrons was
unaltered, whereas following the medium dose postprandial chylomicron concentrations were
significantly increased. Interestingly, this increase was only detected in the lipid-rich
chylomicron fraction, with postprandial levels of chylomicron remnants remaining
unchanged. In conclusion, it appears that consumption of what would be considered low to
medium doses of fat are not associated with transient postprandial increases in
chylomicron remnants in healthy male subjects.
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14
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Klop B, Castro Cabezas M. Chylomicrons: A Key Biomarker and Risk Factor for Cardiovascular Disease and for the Understanding of Obesity. CURRENT CARDIOVASCULAR RISK REPORTS 2011. [DOI: 10.1007/s12170-011-0215-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Tatarczyk T, Ciardi C, Niederwanger A, Kranebitter M, Patsch JR, Pedrini MT. Postprandial triglyceride-rich lipoproteins induce hepatic insulin resistance in HepG2 cells independently of their receptor-mediated cellular uptake. Mol Cell Endocrinol 2011; 343:71-8. [PMID: 21704120 PMCID: PMC3167371 DOI: 10.1016/j.mce.2011.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 06/08/2011] [Accepted: 06/09/2011] [Indexed: 01/22/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is associated with hepatic insulin resistance with the molecular basis of this association being not well understood. Here we studied the effect of hepatic triglyceride accumulation induced by postprandial triglyceride-rich lipoproteins (TGRL) on hepatic insulin sensitivity in HepG2 cells. Incubation of HepG2 cells with purified TGRL particles induced hepatocellular triglyceride accumulation paralleled by diminished insulin-stimulated glycogen content and glycogen synthase activity. Accordingly, insulin-induced inhibition of glycogen synthase phosphorylation as well as insulin-induced GSK-3 and AKT phosphorylation were reduced by TGRL. The effects of TGRL were dependent on the presence of apolipoproteins and more pronounced for denser TGRL. Moreover, TGRL effects required the presence of heparan sulfate-proteoglycans on the cell membrane and lipase activity but were independent of the cellular uptake of TGRL particles by receptors of the LDL receptor family. We suggest postprandial lipemia to be an important factor in the pathogenesis of NAFLD.
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Key Words
- bmi, body mass index
- dapi, 4′,6-diamidino-2-phenylindole
- dmem, dulbeccos minimal essential media
- fcs, fetal calf serum
- gs, glycogen synthase
- gsk-3, glycogen synthase kinase 3
- hl, hepatic lipase
- homa-ir, homeostasis model assessment of insulin resistance
- hspg, heparan sulfate proteoglycans
- lpl, lipoprotein lipase
- lrp, ldl-receptor-related protein
- nafld, non-alcoholic fatty liver disease
- pbs, phosphate buffered saline
- rap, receptor-associated protein
- ros, reactive oxygen species
- sf, svedberg flotation rate
- tgrl, triglyceride-rich lipoproteins
- thl, tetrahydrolipstatin
- glucose metabolism
- hepatic insulin resistance
- insulin signaling
- liver steatosis
- postprandial lipemia
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van Hees AMJ, Jans A, Hul GB, Roche HM, Saris WHM, Blaak EE. Skeletal muscle fatty acid handling in insulin resistant men. Obesity (Silver Spring) 2011; 19:1350-9. [PMID: 21331063 DOI: 10.1038/oby.2011.10] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Disturbances in skeletal muscle lipid metabolism may precede or contribute to the development of whole body insulin resistance. In this study, we examined fasting and postprandial skeletal muscle fatty acid (FA) handling in insulin resistant (IR) men. Thirty men with the metabolic syndrome (MetS) (National Cholesterol Education Program-Adult Treatment Panel III) were included in this sub-study to the LIPGENE study, and divided in two groups (IR and control) based on the median of insulin sensitivity (S(I) = 2.06 (mU/l(-1))·min(-1)·10(-4)). Fasting and postprandial skeletal muscle FA handling were examined by combining the forearm balance technique with stable isotopes of palmitate. [(2)H(2)]-palmitate was infused intravenously to label endogenous triacylglycerol (TAG) and free FAs (FFAs) in the circulation and [U-(13)C]-palmitate was incorporated in a high-fat mixed meal (2.6 MJ, 61 E% fat) to label chylomicron-TAG. Muscle biopsies were taken to determine muscle TAG, diacylglycerol (DAG), FFA, and phospholipid (PL) content, their fractional synthetic rates (FSRs) and degree of saturation, as well as messenger RNA (mRNA) expression of genes involved in lipid metabolism. In the first 2 h after meal consumption, forearm muscle [(2)H(2)]-labeled TAG extraction was higher in IR vs. control (P = 0.05). Fasting percentage saturation of muscle DAG was higher in IR vs. control (P = 0.016). No differences were observed for intramuscular TAG, DAG, FFA, and PL content, FSR, and muscle mRNA expression. In conclusion, increased muscle (hepatically derived) TAG extraction during postprandial conditions and increased saturation of intramuscular DAG are associated with insulin resistance, suggesting that disturbances in skeletal muscle FA handling could play a role in the development of whole body insulin resistance and type 2 diabetes.
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Affiliation(s)
- Anneke M J van Hees
- Department of Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre, Maastricht, The Netherlands
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Wang X, Magkos F, Mittendorfer B. Sex differences in lipid and lipoprotein metabolism: it's not just about sex hormones. J Clin Endocrinol Metab 2011; 96:885-93. [PMID: 21474685 PMCID: PMC3070248 DOI: 10.1210/jc.2010-2061] [Citation(s) in RCA: 267] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
It is commonly thought that sex hormones are important regulators of plasma lipid kinetics and are responsible for sexual dimorphism in the plasma lipid profile. Here we discuss the findings from studies evaluating lipid and lipoprotein kinetics in men and women in the context of what we know about the effects of exogenous sex hormone administration, and we conclude that it is more complicated than that. It has become clear that normal physiological alterations in the hormonal milieu (i.e. due to menopause or throughout the menstrual cycle) do not significantly affect plasma lipid homeostasis. Furthermore, parenterally administered estrogens have either no effect or only very small beneficial effects, whereas orally administered estrogens raise plasma triglyceride concentrations--a phenomenon that is not consistent with the observed sex differences and likely results from the hepatic "first-pass effect." The effects of progestogens and androgens mimic only in part the differences in plasma lipids between men and women. Thus, the underlying physiological modulators of plasma lipid metabolism responsible for the differences between men and women remain to be elucidated.
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Affiliation(s)
- Xuewen Wang
- Center for Human Nutrition, Washington University School of Medicine, St Louis, Missouri 63110, USA
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18
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Magkos F, Mittendorfer B. Gender differences in lipid metabolism and the effect of obesity. Obstet Gynecol Clin North Am 2009; 36:245-65, vii. [PMID: 19501312 DOI: 10.1016/j.ogc.2009.03.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
There are many differences between men and women, and between lean and obese subjects, in fatty acid and very low-density lipoprotein triglyceride and apolipoprotein B-100 metabolism. Currently, observations in this area are predominantly descriptive. The mechanisms responsible for sexual dimorphism in lipid metabolism are largely unknown.
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Affiliation(s)
- Faidon Magkos
- Center for Human Nutrition, Division of Geriatrics & Nutritional Science, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA
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19
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Magkos F, Mittendorfer B. Stable isotope-labeled tracers for the investigation of fatty acid and triglyceride metabolism in humans in vivo. ACTA ACUST UNITED AC 2009; 4:215-230. [PMID: 20161007 DOI: 10.2217/clp.09.9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Understanding lipid metabolism and its regulation requires information on the rates at which lipids are produced within the body, absorbed (dietary lipids) into the body, transported within the body, and utilized by various tissues. This article focuses on the use of stable isotope-labeled tracers for the quantitative evaluation of major pathways of fatty acid and triglyceride metabolism in humans in vivo. Adipose tissue lipolysis and free fatty acid appearance in plasma, fatty acid tissue uptake and oxidation, and hepatic very low-density lipoprotein triglyceride secretion are among the metabolic pathways that can be studied by using stable isotope labeled tracers, and will be discussed in detail. The methodology has been in use for many years and is constantly being refined. A variety of tracers and analytical approaches are available and can be used; knowing the advantages, assumptions, and limitations of each is essential for the planning of studies and the interpretation of data, which can provide unique insights into human lipid metabolism.
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Affiliation(s)
- Faidon Magkos
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
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20
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Redgrave TG. Chylomicrons in disease-future challenges. ATHEROSCLEROSIS SUPP 2008; 9:3-6. [DOI: 10.1016/j.atherosclerosissup.2008.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 04/21/2008] [Accepted: 05/13/2008] [Indexed: 10/21/2022]
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Botham KM, Wheeler-Jones CPD. Introduction to the Biochemical Society Focused Meeting on Diet and Cardiovascular Health: chylomicron remnants and their emerging roles in vascular dysfunction in atherosclerosis. Biochem Soc Trans 2007; 35:437-9. [PMID: 17511621 DOI: 10.1042/bst0350437] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although it has been known for many years that dietary lipids influence the development of atherosclerosis, in the past this has been attributed to their effects on blood cholesterol levels. Recent work, however, has shown that CMRs (chylomicron remnants), the lipoproteins which carry dietary lipids in the blood, potentially have a direct role in initiating atherogenesis by influencing vascular function. The Diet and Cardiovascular Health: Chylomicron Remnants and Their Emerging Roles in Vascular Dysfunction in Atherosclerosis Meeting focused attention on studies which have shown that CMRs influence vascular function via interactions with cells of the artery wall, including endothelial cells and macrophages, and also highlighted the part played by CMRs in the development of premature atherosclerosis in conditions such as the metabolic syndrome, which are an increasing cause of heart disease in developed countries.
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Affiliation(s)
- K M Botham
- Department of Veterinary Basic Sciences, The Royal Veterinary College, Royal College Street, London NW1 0TU, UK.
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