51
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de Boer JF, Schonewille M, Boesjes M, Wolters H, Bloks VW, Bos T, van Dijk TH, Jurdzinski A, Boverhof R, Wolters JC, Kuivenhoven JA, van Deursen JM, Oude Elferink RPJ, Moschetta A, Kremoser C, Verkade HJ, Kuipers F, Groen AK. Intestinal Farnesoid X Receptor Controls Transintestinal Cholesterol Excretion in Mice. Gastroenterology 2017; 152:1126-1138.e6. [PMID: 28065787 DOI: 10.1053/j.gastro.2016.12.037] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 12/03/2016] [Accepted: 12/23/2016] [Indexed: 01/17/2023]
Abstract
BACKGROUND & AIMS The role of the intestine in the maintenance of cholesterol homeostasis increasingly is recognized. Fecal excretion of cholesterol is the last step in the atheroprotective reverse cholesterol transport pathway, to which biliary and transintestinal cholesterol excretion (TICE) contribute. The mechanisms controlling the flux of cholesterol through the TICE pathway, however, are poorly understood. We aimed to identify mechanisms that regulate and stimulate TICE. METHODS We performed studies with C57Bl/6J mice, as well as with mice with intestine-specific knockout of the farnesoid X receptor (FXR), mice that express an FXR transgene specifically in the intestine, and ABCG8-knockout mice. Mice were fed a control diet or a diet supplemented with the FXR agonist PX20606, with or without the cholesterol absorption inhibitor ezetimibe. Some mice with intestine-specific knockout of FXR were given daily injections of fibroblast growth factor (FGF)19. To determine fractional cholesterol absorption, mice were given intravenous injections of cholesterol D5 and oral cholesterol D7. Mice were given 13C-acetate in drinking water for measurement of cholesterol synthesis. Bile cannulations were performed and biliary cholesterol secretion rates were assessed. In a separate set of experiments, bile ducts of male Wistar rats were exteriorized, allowing replacement of endogenous bile by a model bile. RESULTS In mice, we found TICE to be regulated by intestinal FXR via induction of its target gene Fgf15 (FGF19 in rats and human beings). Stimulation of this pathway caused mice to excrete up to 60% of their total cholesterol content each day. PX20606 and FGF19 each increased the ratio of muricholate:cholate in bile, inducing a more hydrophilic bile salt pool. The altered bile salt pool stimulated robust secretion of cholesterol into the intestinal lumen via the sterol-exporting heterodimer adenosine triphosphate binding cassette subfamily G member 5/8 (ABCG5/G8). Of note, the increase in TICE induced by PX20606 was independent of changes in cholesterol absorption. CONCLUSIONS Hydrophilicity of the bile salt pool, controlled by FXR and FGF15/19, is an important determinant of cholesterol removal via TICE. Strategies that alter bile salt pool composition might be developed for the prevention of cardiovascular disease. Transcript profiling: http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?token=irsrayeohfcntqx&acc=GSE74101.
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Affiliation(s)
- Jan Freark de Boer
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
| | - Marleen Schonewille
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Marije Boesjes
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Henk Wolters
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Vincent W Bloks
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Trijnie Bos
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Theo H van Dijk
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Angelika Jurdzinski
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Renze Boverhof
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Justina C Wolters
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jan A Kuivenhoven
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jan M van Deursen
- Department of Pediatric and Adolescent Medicine, Department of Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Ronald P J Oude Elferink
- Tytgat Institute for Liver and Intestinal Research, Department of Hepatology and Gastroenterology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Antonio Moschetta
- Department of Interdisciplinary Medicine, University of Bari, IRCCS Istituto Tumori "Giovanni Paolo II," Bari, Italy
| | | | - Henkjan J Verkade
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Folkert Kuipers
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Albert K Groen
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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52
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Disrupting Hepatocyte Cyp51 from Cholesterol Synthesis Leads to Progressive Liver Injury in the Developing Mouse and Decreases RORC Signalling. Sci Rep 2017; 7:40775. [PMID: 28098217 PMCID: PMC5241696 DOI: 10.1038/srep40775] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 12/12/2016] [Indexed: 11/16/2022] Open
Abstract
Development of mice with hepatocyte knockout of lanosterol 14α-demethylase (HCyp51−/−) from cholesterol synthesis is characterized by the progressive onset of liver injury with ductular reaction and fibrosis. These changes begin during puberty and are generally more aggravated in the knockout females. However, a subgroup of (pre)pubertal knockout mice (runts) exhibits a pronounced male prevalent liver dysfunction characterized by downregulated amino acid metabolism and elevated Casp12. RORC transcriptional activity is diminished in livers of all runt mice, in correlation with the depletion of potential RORC ligands subsequent to CYP51 disruption. Further evidence for this comes from the global analysis that identified a crucial overlap between hepatic Cyp51−/− and Rorc−/− expression profiles. Additionally, the reduction in RORA and RORC transcriptional activity was greater in adult HCyp51−/− females than males, which correlates well with their downregulated amino and fatty acid metabolism. Overall, we identify a global and sex-dependent transcriptional de-regulation due to the block in cholesterol synthesis during development of the Cyp51 knockout mice and provide in vivo evidence that sterol intermediates downstream of lanosterol may regulate the hepatic RORC activity.
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53
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54
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Jakulj L, van Dijk TH, de Boer JF, Kootte RS, Schonewille M, Paalvast Y, Boer T, Bloks VW, Boverhof R, Nieuwdorp M, Beuers UHW, Stroes ESG, Groen AK. Transintestinal Cholesterol Transport Is Active in Mice and Humans and Controls Ezetimibe-Induced Fecal Neutral Sterol Excretion. Cell Metab 2016; 24:783-794. [PMID: 27818259 DOI: 10.1016/j.cmet.2016.10.001] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 05/09/2016] [Accepted: 09/30/2016] [Indexed: 01/10/2023]
Abstract
Except for conversion to bile salts, there is no major cholesterol degradation pathway in mammals. Efficient excretion from the body is therefore a crucial element in cholesterol homeostasis. Yet, the existence and importance of cholesterol degradation pathways in humans is a matter of debate. We quantified cholesterol fluxes in 15 male volunteers using a cholesterol balance approach. Ten participants repeated the protocol after 4 weeks of treatment with ezetimibe, an inhibitor of intestinal and biliary cholesterol absorption. Under basal conditions, about 65% of daily fecal neutral sterol excretion was bile derived, with the remainder being contributed by direct transintestinal cholesterol excretion (TICE). Surprisingly, ezetimibe induced a 4-fold increase in cholesterol elimination via TICE. Mouse studies revealed that most of ezetimibe-induced TICE flux is mediated by the cholesterol transporter Abcg5/Abcg8. In conclusion, TICE is active in humans and may serve as a novel target to stimulate cholesterol elimination in patients at risk for cardiovascular disease.
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Affiliation(s)
- Lily Jakulj
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Theo H van Dijk
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands
| | - Jan Freark de Boer
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands
| | - Ruud S Kootte
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Marleen Schonewille
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands
| | - Yared Paalvast
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands
| | - Theo Boer
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands
| | - Vincent W Bloks
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands
| | - Renze Boverhof
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands
| | - Max Nieuwdorp
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Ulrich H W Beuers
- Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Erik S G Stroes
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, the Netherlands
| | - Albert K Groen
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, the Netherlands; Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands; Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen 9713ZG, the Netherlands; Amsterdam Diabetes Research Center, Academic Medical Center, Amsterdam 1105AZ, the Netherlands; Groningen Center of Systems Biology, University Medical Center Groningen, Groningen 9713ZG, the Netherlands.
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55
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Ronda OAHO, van Dijk TH, Verkade HJ, Groen AK. Measurement of Intestinal and Peripheral Cholesterol Fluxes by a Dual-Tracer Balance Method. ACTA ACUST UNITED AC 2016; 6:408-434. [PMID: 27906461 DOI: 10.1002/cpmo.16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Long-term elevated plasma cholesterol levels put individuals at risk for developing atherosclerosis. Plasma cholesterol levels are determined by the balance between cholesterol input and output fluxes. Here we describe in detail the methodology to determine the different cholesterol fluxes in mice. The percentage of absorbed cholesterol is calculated from a stable isotope-based double-label method. Cholesterol synthesis is calculated from MIDA after 13 C-acetate enrichment. Cholesterol is removed from the body via the feces. The fecal excretion route is either biliary or non-biliary. The non-biliary route is dominated by trans-intestinal cholesterol efflux, or TICE. Biliary excretion of cholesterol is measured by collecting bile. Non-biliary excretion is calculated by computational modeling. In this article, we describe methods and procedures to measure and calculate dietary intake of cholesterol, fractional cholesterol absorption, fecal neutral sterol output, biliary cholesterol excretion, TICE, cholesterol synthesis, peripheral fluxes, and whole-body cholesterol balance. © 2016 by John Wiley & Sons, Inc.
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Affiliation(s)
- Onne A H O Ronda
- Center for Liver, Digestive and Metabolic Diseases, Departments of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Theo H van Dijk
- Department of Laboratory Medicine, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - H J Verkade
- Center for Liver, Digestive and Metabolic Diseases, Departments of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Albert K Groen
- Department of Laboratory Medicine, Center for Liver Digestive and Metabolic Diseases, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Amsterdam Diabetes Center, Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands
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56
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Kanhai K, Goulooze SC, Stevens J, Hay JL, Dent G, Verma A, Hankemeier T, de Boer T, Meijering H, Chavez JC, Cohen AF, Groeneveld GJ. Quantifying Beta-Galactosylceramide Kinetics in Cerebrospinal Fluid of Healthy Subjects Using Deuterium Labeling. Clin Transl Sci 2016; 9:321-327. [PMID: 27743499 PMCID: PMC5351000 DOI: 10.1111/cts.12424] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 09/08/2016] [Indexed: 12/12/2022] Open
Abstract
Therapeutics promoting myelin synthesis may enhance recovery in demyelinating diseases, such as multiple sclerosis. However, no suitable method exists to quantify myelination. The turnover of galactosylceramide (myelin component) is indicative of myelination in mice, but its turnover has not been determined in humans. Here, six healthy subjects consumed 120 mL 70% D2O daily for 70 days to label galactosylceramide. We then used mass spectrometry and compartmental modeling to quantify the turnover rate of galactosylceramide in cerebrospinal fluid. Maximum deuterium enrichment of body water ranged from 1.5–3.9%, whereas that of galactosylceramide was much lower: 0.05–0.14%. This suggests a slow turnover rate, which was confirmed by the model‐estimated galactosylceramide turnover rate of 0.00168 day−1, which corresponds to a half‐life of 413 days. Additional studies in patients with multiple sclerosis are needed to investigate whether galactosylceramide turnover could be used as an outcome measure in clinical trials with remyelination therapies.
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Affiliation(s)
- Kms Kanhai
- Centre for Human Drug Research, Leiden, The Netherlands
| | - S C Goulooze
- Centre for Human Drug Research, Leiden, The Netherlands
| | - J Stevens
- Centre for Human Drug Research, Leiden, The Netherlands
| | - J L Hay
- Centre for Human Drug Research, Leiden, The Netherlands
| | - G Dent
- Experimental Medicine, Biogen Cambridge, Massachusetts, USA
| | - A Verma
- Experimental Medicine, Biogen Cambridge, Massachusetts, USA
| | - T Hankemeier
- Netherlands Metabolomics Centre, Leiden, The Netherlands
| | - T de Boer
- Analytical Biochemical Laboratory BV, Assen, The Netherlands
| | - H Meijering
- Analytical Biochemical Laboratory BV, Assen, The Netherlands
| | - J C Chavez
- Experimental Medicine, Biogen Cambridge, Massachusetts, USA
| | - A F Cohen
- Centre for Human Drug Research, Leiden, The Netherlands
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57
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Ruiz-Rodado V, Nicoli ER, Probert F, Smith DA, Morris L, Wassif CA, Platt FM, Grootveld M. 1H NMR-Linked Metabolomics Analysis of Liver from a Mouse Model of NP-C1 Disease. J Proteome Res 2016; 15:3511-3527. [PMID: 27503774 DOI: 10.1021/acs.jproteome.6b00238] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Clinical manifestations of Niemann-Pick type C1 (NP-C1) disease include neonatal hepatosplenomegaly and in some patients progressive liver dysfunction and failure. This study involved a 1H NMR-linked metabolomics analysis of liver samples collected from a NP-C1 disease mutant mouse model in order to explore time-dependent imbalances in metabolic pathways associated with NP-C1 liver dysfunction, including fibrosis. NP-C1 mutant (Npc1-/-; NP-C1), control (Npc1+/+; WT), and NP-C1 heterozygous mice (Npc1+/-; HET) were generated from heterozygote matings. Aqueous extracts of these liver samples collected at time points of 3, 6, 9, and 11 weeks were subjected to high-resolution NMR analysis, and multivariate (MV) metabolomics analyses of data sets acquired were performed. A MV random forests (RFs) model effectively discriminated between NP-C1 and a combined WT/HET hepatic NMR profiles with very high predictive accuracy and reliability. Key distinguishing features included significant upregulations in the hepatic concentrations of phenylalanine, tyrosine, glutamate, lysine/ornithine, valine, threonine, and hypotaurine/methionine, and diminished levels of nicotinate/niacinamide, inosine, phosphoenolpyruvate, and 3-hydroxyphenylacetate. Quantitative pathway topological analysis confirmed that imbalances in tyrosine biosynthesis, and hepatic phenylalanine, tyrosine, glutamate/glutamine, and nicotinate/niacinamide metabolism were involved in the pathogenesis of NP-C1 disease-associated liver dysfunction/damage. 1H NMR-linked metabolomics analysis provides valuable biomarker information regarding hepatic dysfunction or damage in NP-C1 disease.
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Affiliation(s)
- Victor Ruiz-Rodado
- Leicester School of Pharmacy, De Montfort University , The Gateway, Leicester LE1 9BH, United Kingdom
| | - Elena-Raluca Nicoli
- Department of Pharmacology, University of Oxford , Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Fay Probert
- Leicester School of Pharmacy, De Montfort University , The Gateway, Leicester LE1 9BH, United Kingdom
| | - David A Smith
- Department of Pharmacology, University of Oxford , Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Lauren Morris
- Department of Pharmacology, University of Oxford , Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Christopher A Wassif
- Department of Pharmacology, University of Oxford , Mansfield Road, Oxford OX1 3QT, United Kingdom.,Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH , Bethesda, Maryland 20892, United States
| | - Frances M Platt
- Department of Pharmacology, University of Oxford , Mansfield Road, Oxford OX1 3QT, United Kingdom
| | - Martin Grootveld
- Leicester School of Pharmacy, De Montfort University , The Gateway, Leicester LE1 9BH, United Kingdom
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58
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Liu H, Pathak P, Boehme S, Chiang JL. Cholesterol 7α-hydroxylase protects the liver from inflammation and fibrosis by maintaining cholesterol homeostasis. J Lipid Res 2016; 57:1831-1844. [PMID: 27534992 DOI: 10.1194/jlr.m069807] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Indexed: 12/30/2022] Open
Abstract
Cholesterol 7α-hydroxylase (CYP7A1) plays a critical role in control of bile acid and cholesterol homeostasis. Bile acids activate farnesoid X receptor (FXR) and Takeda G protein-coupled receptor 5 (TGR5) to regulate lipid, glucose, and energy metabolism. However, the role of bile acids in hepatic inflammation and fibrosis remains unclear. In this study, we showed that adenovirus-mediated overexpression of Cyp7a1 ameliorated lipopolysaccharide (LPS)-induced inflammatory cell infiltration and pro-inflammatory cytokine production in WT and TGR5-deficient (Tgr5-/-) mice, but not in FXR-deficient (Fxr-/-) mice, suggesting that bile acid signaling through FXR protects against hepatic inflammation. Nuclear factor κ light-chain enhancer of activated B cells (NF-κB)-luciferase reporter assay showed that FXR agonists significantly inhibited TNF-α-induced NF-κB activity. Furthermore, chromatin immunoprecipitation and mammalian two-hybrid assays showed that ligand-activated FXR interacted with NF-κB and blocked recruitment of steroid receptor coactivator-1 to cytokine promoter and resulted in inhibition of NF-κB activity. Methionine/choline-deficient (MCD) diet increased hepatic inflammation, free cholesterol, oxidative stress, apoptosis, and fibrosis in CYP7A1-deficient (Cyp7a1-/-) mice compared with WT mice. Remarkably, adenovirus-mediated overexpression of Cyp7a1 effectively reduced hepatic free cholesterol and oxidative stress and reversed hepatic inflammation and fibrosis in MCD diet-fed Cyp7a1-/- mice. Current studies suggest that increased Cyp7a1 expression and bile acid synthesis ameliorate hepatic inflammation through activation of FXR, whereas reduced bile acid synthesis aggravates MCD diet-induced hepatic inflammation and fibrosis. Maintaining bile acid and cholesterol homeostasis is important for protecting against liver injury and nonalcoholic fatty liver disease.
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Affiliation(s)
- Hailiang Liu
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272
| | - Preeti Pathak
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272
| | - Shannon Boehme
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272
| | - JohnY L Chiang
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272.
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59
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Saadane A, Mast N, Dao T, Ahmad B, Pikuleva IA. Retinal Hypercholesterolemia Triggers Cholesterol Accumulation and Esterification in Photoreceptor Cells. J Biol Chem 2016; 291:20427-39. [PMID: 27514747 DOI: 10.1074/jbc.m116.744656] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Indexed: 01/01/2023] Open
Abstract
The process of vision is impossible without the photoreceptor cells, which have a unique structure and specific maintenance of cholesterol. Herein we report on the previously unrecognized cholesterol-related pathway in the retina discovered during follow-up characterizations of Cyp27a1(-/-)Cyp46a1(-/-) mice. These animals have retinal hypercholesterolemia and convert excess retinal cholesterol into cholesterol esters, normally present in the retina in very small amounts. We established that in the Cyp27a1(-/-)Cyp46a1(-/-) retina, cholesterol esters are generated by and accumulate in the photoreceptor outer segments (OS), which is the retinal layer with the lowest cholesterol content. Mouse OS were also found to express the cholesterol-esterifying enzyme acyl-coenzyme A:cholesterol acyltransferase (ACAT1), but not lecithin-cholesterol acyltransferase (LCAT), and to differ from humans in retinal expression of ACAT1. Nevertheless, cholesterol esters were discovered to be abundant in human OS. We suggest a mechanism for cholesterol ester accumulation in the OS and that activity impairment of ACAT1 in humans may underlie the development of subretinal drusenoid deposits, a hallmark of age-related macular degeneration, which is a common blinding disease. We generated Cyp27a1(-/-)Cyp46a1(-/-)Acat1(-/-) mice, characterized their retina by different imaging modalities, and confirmed that unesterified cholesterol does accumulate in their OS and that there is photoreceptor apoptosis and OS degeneration in this line. Our results provide insights into the retinal response to local hypercholesterolemia and the retinal significance of cholesterol esterification, which could be cell-specific and both beneficial and detrimental for retinal structure and function.
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Affiliation(s)
- Aicha Saadane
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
| | - Natalia Mast
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
| | - Tung Dao
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
| | - Baseer Ahmad
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and the University Hospitals, Cleveland, Ohio 44106
| | - Irina A Pikuleva
- From the Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio and
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60
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Kirchgessner TG, Sleph P, Ostrowski J, Lupisella J, Ryan CS, Liu X, Fernando G, Grimm D, Shipkova P, Zhang R, Garcia R, Zhu J, He A, Malone H, Martin R, Behnia K, Wang Z, Barrett YC, Garmise RJ, Yuan L, Zhang J, Gandhi MD, Wastall P, Li T, Du S, Salvador L, Mohan R, Cantor GH, Kick E, Lee J, Frost RJA. Beneficial and Adverse Effects of an LXR Agonist on Human Lipid and Lipoprotein Metabolism and Circulating Neutrophils. Cell Metab 2016; 24:223-33. [PMID: 27508871 DOI: 10.1016/j.cmet.2016.07.016] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/21/2016] [Accepted: 07/21/2016] [Indexed: 01/20/2023]
Abstract
The development of LXR agonists for the treatment of coronary artery disease has been challenged by undesirable properties in animal models. Here we show the effects of an LXR agonist on lipid and lipoprotein metabolism and neutrophils in human subjects. BMS-852927, a novel LXRβ-selective compound, had favorable profiles in animal models with a wide therapeutic index in cynomolgus monkeys and mice. In healthy subjects and hypercholesterolemic patients, reverse cholesterol transport pathways were induced similarly to that in animal models. However, increased plasma and hepatic TG, plasma LDL-C, apoB, apoE, and CETP and decreased circulating neutrophils were also evident. Furthermore, similar increases in LDL-C were observed in normocholesterolemic subjects and statin-treated patients. The primate model markedly underestimated human lipogenic responses and did not predict human neutrophil effects. These studies demonstrate both beneficial and adverse LXR agonist clinical responses and emphasize the importance of further translational research in this area.
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Affiliation(s)
| | - Paul Sleph
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Jacek Ostrowski
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - John Lupisella
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Carol S Ryan
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Xiaoqin Liu
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Gayani Fernando
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Denise Grimm
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Petia Shipkova
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Rongan Zhang
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Ricardo Garcia
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Jun Zhu
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Aiqing He
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Harold Malone
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | | | - Kamelia Behnia
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Zhaoqing Wang
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Yu Chen Barrett
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Robert J Garmise
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Long Yuan
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Jane Zhang
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Mohit D Gandhi
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Philip Wastall
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Tong Li
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Shuyan Du
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Lisa Salvador
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Raju Mohan
- Exelixis, Inc., South San Francisco, CA 94080, USA
| | - Glenn H Cantor
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Ellen Kick
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - John Lee
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
| | - Robert J A Frost
- Research and Development, Bristol-Myers Squibb, Princeton, NJ 08543, USA
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61
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Imamura T, Poulsen O, Haddad GG. Intermittent hypoxia induces murine macrophage foam cell formation by IKK-β-dependent NF-κB pathway activation. J Appl Physiol (1985) 2016; 121:670-7. [PMID: 27471237 DOI: 10.1152/japplphysiol.00307.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/27/2016] [Indexed: 12/23/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a common sleep disorder characterized by intermittent hypoxia (IH). Clinical studies have previously shown that OSA is an independent risk factor for atherosclerosis. Atherogenicity in OSA patients has been assumed to be associated with the NF-κB pathways. Although foam cells are considered to be a hallmark of atherosclerosis, how IH as in OSA affects their development has not been fully understood. Therefore, we hypothesized that IH induces macrophage foam cell formation through NF-κB pathway activation. To test this hypothesis, peritoneal macrophages collected from myeloid-restricted IKK-β-deleted mice were incubated with native LDL and exposed to either IH or normoxia. After exposure, NF-κB pathway activity and intracellular cholesterol were measured. In control macrophages, IH significantly increased NF-κB pathway activity by 93% compared with normoxia (P < 0.05). However, such response to IH was diminished by IKK-β deletion (increased by +31% compared with normoxia; P = 0.64), suggesting that IKK-β is critical for IH-induced NF-κB pathway activation. Likewise, in control macrophages, total cholesterol was increased in IH compared with normoxia (65.7 ± 3.8 μg/mg cellular protein and 53.2 ± 1.2, respectively; P < 0.05). However, this IH-induced foam cell formation was disappeared when IKK-β was deleted (52.2 ± 1.2 μg/mg cellular protein for IH and 46.3 ± 1.7 for normoxia; P = 0.55). This IH-mediated effect still existed in macrophages without LDL receptor. Taken together, our findings show that IH activates the IKK-β-dependent NF-κB pathway and that this, in turn, induces foam cell formation in murine macrophages.
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Affiliation(s)
- Toshihiro Imamura
- Department of Pediatrics, Division of Respiratory Medicine, University of California, San Diego, California;
| | - Orit Poulsen
- Department of Neurosciences, University of California, San Diego, California; and
| | - Gabriel G Haddad
- Department of Pediatrics, Division of Respiratory Medicine, University of California, San Diego, California; Department of Neurosciences, University of California, San Diego, California; and Rady Children's Hospital, San Diego, California
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62
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Smith KR, Hussain T, Karimian Azari E, Steiner JL, Ayala JE, Pratley RE, Kyriazis GA. Disruption of the sugar-sensing receptor T1R2 attenuates metabolic derangements associated with diet-induced obesity. Am J Physiol Endocrinol Metab 2016; 310:E688-E698. [PMID: 26884387 PMCID: PMC4835941 DOI: 10.1152/ajpendo.00484.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 02/12/2016] [Indexed: 11/22/2022]
Abstract
Sweet taste receptors (STRs) on the tongue mediate gustatory sweet sensing, but their expression in the gut, pancreas, and adipose tissue suggests a physiological contribution to whole body nutrient sensing and metabolism. However, little is known about the function and contribution of these sugar sensors during metabolic stress induced by overnutrition and subsequent obesity. Here, we investigated the effects of high-fat/low-carbohydrate (HF/LC) diet on glucose homeostasis and energy balance in mice with global disruption of the sweet taste receptor protein T1R2. We assessed body composition, energy balance, glucose homeostasis, and tissue-specific nutrient metabolism in T1R2 knockout (T1R2-KO) mice fed a HF/LC diet for 12 wk. HF/LC diet-fed T1R2-KO mice gained a similar amount of body mass as did WT mice, but had reduced fat mass and increased lean mass relative to WT mice. T1R2-KO mice were also hyperphagic and hyperactive. Ablation of the T1R2 sugar sensor protected mice from HF/LC diet-induced hyperinsulinemia and altered substrate utilization, including increased rates of glucose oxidation and decreased liver triglyceride (TG) accumulation, despite normal intestinal fat absorption. Finally, STRs (T1r2/T1r3) were upregulated in the adipose tissue of WT mice in response to HF/LC diet, and their expression positively correlated with fat mass and glucose intolerance. The chemosensory receptor T1R2, plays an important role in glucose homeostasis during diet-induced obesity through the regulation of yet to be identified molecular mechanisms that alter energy disposal and utilization in peripheral tissues.
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Affiliation(s)
- Kathleen R Smith
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida; and
| | - Tania Hussain
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida; and
| | - Elnaz Karimian Azari
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida; and
| | - Jennifer L Steiner
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida; and
| | - Julio E Ayala
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida; and
| | - Richard E Pratley
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida; and
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida
| | - George A Kyriazis
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida; and
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida
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63
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Huang Z, Liang L, Li L, Xu M, Li X, Sun H, He S, Lin L, Zhang Y, Song Y, Yang M, Luo Y, Loh HH, Law PY, Zheng D, Zheng H. Opioid doses required for pain management in lung cancer patients with different cholesterol levels: negative correlation between opioid doses and cholesterol levels. Lipids Health Dis 2016; 15:47. [PMID: 26952011 PMCID: PMC4782347 DOI: 10.1186/s12944-016-0212-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/24/2016] [Indexed: 02/01/2023] Open
Abstract
Background Pain management has been considered as significant contributor to broad quality-of-life improvement for cancer patients. Modulating serum cholesterol levels affects analgesia abilities of opioids, important pain killer for cancer patients, in mice system. Thus the correlation between opioids usages and cholesterol levels were investigated in human patients with lung cancer. Methods Medical records of 282 patients were selected with following criteria, 1) signed inform consent, 2) full medical records on total serum cholesterol levels and opioid administration, 3) opioid-naïve, 4) not received/receiving cancer-related or cholesterol lowering treatment, 5) pain level at level 5–8. The patients were divided into different groups basing on their gender and cholesterol levels. Since different opioids, morphine, oxycodone, and fentanyl, were all administrated at fixed low dose initially and increased gradually only if pain was not controlled, the percentages of patients in each group who did not respond to the initial doses of opioids and required higher doses for pain management were determined and compared. Results Patients with relative low cholesterol levels have larger percentage (11 out of 28 in female and 31 out of 71 in male) to not respond to the initial dose of opioids than those with high cholesterol levels (0 out of 258 in female and 8 out of 74 in male). Similar differences were obtained when patients with different opioids were analyzed separately. After converting the doses of different opioids to equivalent doses of oxycodone, significant correlation between opioid usages and cholesterol levels was also observed. Conclusions Therefore, more attention should be taken to those cancer patients with low cholesterol levels because they may require higher doses of opioids as pain killer. Electronic supplementary material The online version of this article (doi:10.1186/s12944-016-0212-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhenhua Huang
- Department of Oncology, Nanfang Hospital, Southern Medical University, #1838 Guangzhou Ave. N, Guangzhou, 510515, China.
| | - Lining Liang
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China.
| | - Lingyu Li
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China. .,Anhui University, Hefei, 230601, China.
| | - Miao Xu
- Sun Yat-sen University Cancer Center; State Key Laboratory of Oncology in South China; Collaborative Innovation Center for Cancer Medicine, #651 Dongfeng East Ave, Guangzhou, 510060, China.
| | - Xiang Li
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China.
| | - Hao Sun
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China.
| | - Songwei He
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China.
| | - Lilong Lin
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China.
| | - Yixin Zhang
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China.
| | - Yancheng Song
- The third hospital, Southern Medical University, #183 Zhongshan Ave. E, Guangzhou, 510665, China.
| | - Man Yang
- Department of Neurology, Nanfang Hospital, Southern Medical University, #1838 Guangzhou Ave. N, Guangzhou, 510515, China.
| | - Yuling Luo
- Department of Oncology, Nanfang Hospital, Southern Medical University, #1838 Guangzhou Ave. N, Guangzhou, 510515, China.
| | - Horace H Loh
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, 6-120 Jackson Hall, 321 Church St. SE, Minneapolis, MN, 55455, USA.
| | - Ping-Yee Law
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, 6-120 Jackson Hall, 321 Church St. SE, Minneapolis, MN, 55455, USA.
| | - Dayong Zheng
- Department of Oncology, Nanfang Hospital, Southern Medical University, #1838 Guangzhou Ave. N, Guangzhou, 510515, China.
| | - Hui Zheng
- CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, A-131, #190 Kaiyuan Ave, Guangzhou, 510530, China.
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64
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Alphonse PAS, Jones PJH. Revisiting Human Cholesterol Synthesis and Absorption: The Reciprocity Paradigm and its Key Regulators. Lipids 2015. [PMID: 26620375 DOI: 10.1007/s11745‐015‐4096‐7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Hypercholesterolemia is a major risk factor for cardiovascular disease. Cholesterol homeostasis in the body is governed by the interplay between absorption, synthesis, and excretion or conversion of cholesterol into bile acids. A reciprocal relationship between cholesterol synthesis and absorption is known to regulate circulating cholesterol in response to dietary or therapeutic interventions. However, the degree to which these factors affect synthesis and absorption and the extent to which one vector shifts in response to the other are not thoroughly understood. Also, huge inter-individual variability exists in the manner in which the two systems act in response to any cholesterol-lowering treatment. Various factors are known to account for this variability and in light of recent experimental advances new players such as gene-gene interactions, gene-environmental effects, and gut microbiome hold immense potential in offering an explanation to the complex traits of inter-individual variability in human cholesterol metabolism. In this context, the objective of the present review is to provide an overview on cholesterol metabolism and discuss the role of potential factors such as genetics, epigenetics, epistasis, and gut microbiome, as well as other regulators in modulating cholesterol metabolism, especially emphasizing the reciprocal relationship between cholesterol synthesis and absorption. Furthermore, an evaluation of the implications of this push-pull mechanism on cholesterol-lowering strategies is presented.
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Affiliation(s)
- Peter A S Alphonse
- Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada.
- Richardson Centre for Functional Foods and Nutraceuticals (RCFFN), University of Manitoba, 196, Innovation Drive, SmartPark, Winnipeg, MB, R3T 2N2, Canada.
| | - Peter J H Jones
- Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada
- Richardson Centre for Functional Foods and Nutraceuticals (RCFFN), University of Manitoba, 196, Innovation Drive, SmartPark, Winnipeg, MB, R3T 2N2, Canada
- Food Science, University of Manitoba, Winnipeg, MB, Canada
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65
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Lin JB, Mast N, Bederman IR, Li Y, Brunengraber H, Björkhem I, Pikuleva IA. Cholesterol in mouse retina originates primarily from in situ de novo biosynthesis. J Lipid Res 2015; 57:258-64. [PMID: 26630912 DOI: 10.1194/jlr.m064469] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Indexed: 12/18/2022] Open
Abstract
The retina, a thin tissue in the back of the eye, has two apparent sources of cholesterol: in situ biosynthesis and cholesterol available from the systemic circulation. The quantitative contributions of these two cholesterol sources to the retinal cholesterol pool are unknown and have been determined in the present work. A new methodology was used. Mice were given separately deuterium-labeled drinking water and chow containing 0.3% deuterium-labeled cholesterol. In the retina, the rate of total cholesterol input was 21 μg of cholesterol/g retina • day, of which 15 μg of cholesterol/g retina • day was provided by local biosynthesis and 6 μg of cholesterol/g retina • day was uptaken from the systemic circulation. Thus, local cholesterol biosynthesis accounts for the majority (72%) of retinal cholesterol input. We also quantified cholesterol input to mouse brain, the organ sharing important similarities with the retina. The rate of total cerebral cholesterol input was 121 μg of cholesterol/g brain • day with local biosynthesis providing 97% of total cholesterol input. Our work addresses a long-standing question in eye research and adds new knowledge to the potential use of statins (drugs that inhibit cholesterol biosynthesis) as therapeutics for age-related macular degeneration, a common blinding disease.
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Affiliation(s)
- Joseph B Lin
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
| | - Natalia Mast
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
| | - Ilya R Bederman
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106
| | - Yong Li
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
| | - Henri Brunengraber
- Department of Nutrition, Case Western Reserve University, Cleveland, OH 44106
| | - Ingemar Björkhem
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska University Hospital, Karolinska Institute, Huddinge, Stockholm 141 86 Sweden
| | - Irina A Pikuleva
- Department of Ophthalmology and Visual Sciences,Case Western Reserve University, Cleveland, OH 44106
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66
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Alphonse PAS, Jones PJH. Revisiting Human Cholesterol Synthesis and Absorption: The Reciprocity Paradigm and its Key Regulators. Lipids 2015; 51:519-36. [PMID: 26620375 DOI: 10.1007/s11745-015-4096-7] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 11/09/2015] [Indexed: 12/22/2022]
Abstract
Hypercholesterolemia is a major risk factor for cardiovascular disease. Cholesterol homeostasis in the body is governed by the interplay between absorption, synthesis, and excretion or conversion of cholesterol into bile acids. A reciprocal relationship between cholesterol synthesis and absorption is known to regulate circulating cholesterol in response to dietary or therapeutic interventions. However, the degree to which these factors affect synthesis and absorption and the extent to which one vector shifts in response to the other are not thoroughly understood. Also, huge inter-individual variability exists in the manner in which the two systems act in response to any cholesterol-lowering treatment. Various factors are known to account for this variability and in light of recent experimental advances new players such as gene-gene interactions, gene-environmental effects, and gut microbiome hold immense potential in offering an explanation to the complex traits of inter-individual variability in human cholesterol metabolism. In this context, the objective of the present review is to provide an overview on cholesterol metabolism and discuss the role of potential factors such as genetics, epigenetics, epistasis, and gut microbiome, as well as other regulators in modulating cholesterol metabolism, especially emphasizing the reciprocal relationship between cholesterol synthesis and absorption. Furthermore, an evaluation of the implications of this push-pull mechanism on cholesterol-lowering strategies is presented.
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Affiliation(s)
- Peter A S Alphonse
- Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada. .,Richardson Centre for Functional Foods and Nutraceuticals (RCFFN), University of Manitoba, 196, Innovation Drive, SmartPark, Winnipeg, MB, R3T 2N2, Canada.
| | - Peter J H Jones
- Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada.,Richardson Centre for Functional Foods and Nutraceuticals (RCFFN), University of Manitoba, 196, Innovation Drive, SmartPark, Winnipeg, MB, R3T 2N2, Canada.,Food Science, University of Manitoba, Winnipeg, MB, Canada
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67
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Evaluating computational models of cholesterol metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1360-76. [DOI: 10.1016/j.bbalip.2015.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 05/08/2015] [Accepted: 05/26/2015] [Indexed: 02/02/2023]
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68
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Zhu F, Gatti DL, Yang KH. Nodal versus Total Axonal Strain and the Role of Cholesterol in Traumatic Brain Injury. J Neurotrauma 2015; 33:859-70. [PMID: 26393780 DOI: 10.1089/neu.2015.4007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) is a health threat that affects every year millions of people involved in motor vehicle and sporting accidents, and thousands of soldiers in battlefields. Diffuse axonal injury (DAI) is one of the most frequent types of TBI leading to death. In DAI, the initial traumatic event is followed by a cascade of biochemical changes that take time to develop in full, so that symptoms may not become apparent until days or weeks after the original injury. Hence, DAI is a dynamic process, and the opportunity exists to prevent its progression provided the initial trauma can be predicted at the molecular level. Here, we present preliminary evidence from micro-finite element (FE) simulations that the mechanical response of central nervous system myelinated fibers is dependent on the axonal diameter, the ratio between axon diameter and fiber diameter (g-ratio), the microtubules density, and the cholesterol concentration in the axolemma and myelin. A key outcome of the simulations is that there is a significant difference between the overall level of strain in a given axonal segment and the level of local strain in the Ranvier nodes contained in that segment, with the nodal strain being much larger than the total strain. We suggest that the acquisition of this geometric and biochemical information by means of already available high resolution magnetic resonance imaging techniques, and its incorporation in current FE models of the brain will enhance the models capacity to predict the site and magnitude of primary axonal damage upon TBI.
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Affiliation(s)
- Feng Zhu
- 1 Department of Biomedical Engineering, Wayne State University , Detroit, Michigan
| | - Domenico L Gatti
- 2 Department of Biochemistry and Molecular Biology, Wayne State University , Detroit, Michigan.,3 CardioVascular Research Institute, Wayne State University , Detroit, Michigan
| | - King H Yang
- 1 Department of Biomedical Engineering, Wayne State University , Detroit, Michigan
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69
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Mitsche MA, McDonald JG, Hobbs HH, Cohen JC. Flux analysis of cholesterol biosynthesis in vivo reveals multiple tissue and cell-type specific pathways. eLife 2015; 4:e07999. [PMID: 26114596 PMCID: PMC4501332 DOI: 10.7554/elife.07999] [Citation(s) in RCA: 128] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 06/25/2015] [Indexed: 01/22/2023] Open
Abstract
Two parallel pathways produce cholesterol: the Bloch and Kandutsch-Russell pathways. Here we used stable isotope labeling and isotopomer analysis to trace sterol flux through the two pathways in mice. Surprisingly, no tissue used the canonical K–R pathway. Rather, a hybrid pathway was identified that we call the modified K–R (MK–R) pathway. Proportional flux through the Bloch pathway varied from 8% in preputial gland to 97% in testes, and the tissue-specificity observed in vivo was retained in cultured cells. The distribution of sterol isotopomers in plasma mirrored that of liver. Sterol depletion in cultured cells increased flux through the Bloch pathway, whereas overexpression of 24-dehydrocholesterol reductase (DHCR24) enhanced usage of the MK–R pathway. Thus, relative use of the Bloch and MK–R pathways is highly variable, tissue-specific, flux dependent, and epigenetically fixed. Maintenance of two interdigitated pathways permits production of diverse bioactive sterols that can be regulated independently of cholesterol. DOI:http://dx.doi.org/10.7554/eLife.07999.001 Cholesterol is important for animals, both as an essential component of the membrane that surrounds cells and as a building block to make hormones and other biologically important molecules. However, cells limit how much cholesterol they make because an excess of this fatty molecule can cause serious health problems, including heart disease and stroke. Cholesterol is made via a complex process that involves more than 30 different steps, which can be organized into two biochemical pathways (named the Bloch pathway and the Kandutsch–Russell pathway). The enzymes that carry out the steps in these pathways have been characterized in detail. Less is known about which of the two pathways is actually used in different cells and tissues, or how much cholesterol each pathway produces. This is partly because it is difficult to distinguish between the closely related intermediate molecules that are formed in each pathway. Mitsche et al. have now used mass spectrometry and isotope labeling techniques to analyze the relative contributions of the two cholesterol-making pathways in both cells grown in the laboratory and in mice. The experiments show that many cells use the Bloch pathway. However, no cells were found to use the Kandutsch–Russell pathway as it was originally described. Rather, some of the cells used a hybrid pathway where the production of cholesterol was started using the Bloch pathway and then after a certain number of steps, the process switched to using part of the Kandutsch–Russell pathway. Mitsche et al. referred to this mixed system as the ‘modified Kandutsch–Russell pathway’. Mitsche et al. next examined the flow of molecules through these two pathways in different tissues and observed that the Bloch pathway is exclusively used in the testes and adrenal glands, which produce high levels of cholesterol. In contrast, the skin and brain use the modified Kandutsch–Russell pathway. In some tissues, a fraction of the building blocks that can be used to make cholesterol were instead diverted to make other products. This suggests that animals have maintained the two pathways over the course of evolution to enable them to generate a variety of products, which can be used to carry out different biological processes. One challenge following this work will be to use the newly developed methods to analyze other complex biochemical pathways. DOI:http://dx.doi.org/10.7554/eLife.07999.002
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Affiliation(s)
- Matthew A Mitsche
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jeffrey G McDonald
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Helen H Hobbs
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, United States
| | - Jonathan C Cohen
- Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, United States
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70
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Temel RE, Brown JM. A new model of reverse cholesterol transport: enTICEing strategies to stimulate intestinal cholesterol excretion. Trends Pharmacol Sci 2015; 36:440-51. [PMID: 25930707 DOI: 10.1016/j.tips.2015.04.002] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 03/31/2015] [Accepted: 04/06/2015] [Indexed: 01/02/2023]
Abstract
Cardiovascular disease (CVD) remains the largest cause of mortality in most developed countries. Although recent failed clinical trials and Mendelian randomization studies have called into question the high-density lipoprotein (HDL) hypothesis, it remains well accepted that stimulating the process of reverse cholesterol transport (RCT) can prevent or even regress atherosclerosis. The prevailing model for RCT is that cholesterol from the artery wall must be delivered to the liver where it is secreted into bile before leaving the body through fecal excretion. However, many studies have demonstrated that RCT can proceed through a non-biliary pathway known as transintestinal cholesterol excretion (TICE). The goal of this review is to discuss the current state of knowledge of the TICE pathway, with emphasis on points of therapeutic intervention.
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Affiliation(s)
- Ryan E Temel
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536-0509, USA.
| | - J Mark Brown
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA.
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71
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Hypercholesterolemia and ApoE deficiency result in severe infection with Lyme disease and relapsing-fever Borrelia. Proc Natl Acad Sci U S A 2015; 112:5491-6. [PMID: 25870274 DOI: 10.1073/pnas.1502561112] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Lyme disease (Borrelia burgdorferi) and relapsing-fever (Borrelia hispanica) agents have distinct infection courses, but both require cholesterol for growth. They acquire cholesterol from the environment and process it to form cholesterol glycolipids that are incorporated onto their membranes. To determine whether higher levels of serum cholesterol could enhance the organ burdens of B. burgdorferi and the spirochetemia of B. hispanica in laboratory mice, apolipoprotein E (apoE)-deficient and low-density lipoprotein receptor (LDLR)-deficient mice that produce large amounts of serum cholesterol were infected with both spirochetes. Both apoE- and LDLR-deficient mice infected with B. burgdorferi had an increased number of spirochetes in the joints and inflamed ankles compared with the infected wild-type (WT) mice, suggesting that mutations in cholesterol transport that result in high serum cholesterol levels can affect the pathogenicity of B. burgdorferi. In contrast, elevated serum cholesterol did not lead to an increase in the spirochetemia of B. hispanica. In the LDLR-deficient mice, the course of infection was indistinguishable from the WT mice. However, infection of apoE-deficient mice with B. hispanica resulted in a longer spirochetemia and increased mortality. Together, these results argue for the apoE deficiency, and not hypercholesterolemia, as the cause for the increased severity with B. hispanica. Serum hyperlipidemias are common human diseases that could be a risk factor for increased severity in Lyme disease.
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72
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Pelton K, Coticchia CM, Curatolo AS, Schaffner CP, Zurakowski D, Solomon KR, Moses MA. Hypercholesterolemia induces angiogenesis and accelerates growth of breast tumors in vivo. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 184:2099-110. [PMID: 24952430 DOI: 10.1016/j.ajpath.2014.03.006] [Citation(s) in RCA: 78] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 03/20/2014] [Accepted: 03/26/2014] [Indexed: 12/19/2022]
Abstract
Obesity and metabolic syndrome are linked to an increased prevalence of breast cancer among postmenopausal women. A common feature of obesity, metabolic syndrome, and a Western diet rich in saturated fat is a high level of circulating cholesterol. Epidemiological reports investigating the relationship between high circulating cholesterol levels, cholesterol-lowering drugs, and breast cancer are conflicting. Here, we modeled this complex condition in a well-controlled, preclinical animal model using innovative isocaloric diets. Female severe combined immunodeficient mice were fed a low-fat/no-cholesterol diet and then randomized to four isocaloric diet groups: low-fat/no-cholesterol diet, with or without ezetimibe (cholesterol-lowering drug), and high-fat/high-cholesterol diet, with or without ezetimibe. Mice were implanted orthotopically with MDA-MB-231 cells. Breast tumors from animals fed the high-fat/high-cholesterol diet exhibited the fastest progression. Significant differences in serum cholesterol level between groups were achieved and maintained throughout the study; however, no differences were observed in intratumoral cholesterol levels. To determine the mechanism of cholesterol-induced tumor progression, we analyzed tumor proliferation, apoptosis, and angiogenesis and found a significantly greater percentage of proliferating cells from mice fed the high-fat/high-cholesterol diet. Tumors from hypercholesterolemic animals displayed significantly less apoptosis compared with the other groups. Tumors from high-fat/high-cholesterol mice had significantly higher microvessel density compared with tumors from the other groups. These results demonstrate that hypercholesterolemia induces angiogenesis and accelerates breast tumor growth in vivo.
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Affiliation(s)
- Kristine Pelton
- Department of Urology, Boston Children's Hospital, Boston, Massachusetts
| | - Christine M Coticchia
- The Program in Vascular Biology, Boston Children's Hospital, Boston, Massachusetts; Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts
| | - Adam S Curatolo
- The Program in Vascular Biology, Boston Children's Hospital, Boston, Massachusetts
| | - Carl P Schaffner
- Department of Microbiology and Biochemistry, Waksman Institute, Rutgers, the State University of New Jersey, New Brunswick, New Jersey
| | - David Zurakowski
- Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts; Department of Anesthesiology, Boston Children's Hospital, Boston, Massachusetts
| | - Keith R Solomon
- Department of Urology, Boston Children's Hospital, Boston, Massachusetts; Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts; Department of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts.
| | - Marsha A Moses
- The Program in Vascular Biology, Boston Children's Hospital, Boston, Massachusetts; Department of Surgery, Harvard Medical School, Boston Children's Hospital, Boston, Massachusetts
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Warrier M, Shih DM, Burrows AC, Ferguson D, Gromovsky AD, Brown AL, Marshall S, McDaniel A, Schugar RC, Wang Z, Sacks J, Rong X, Vallim TDA, Chou J, Ivanova PT, Myers DS, Brown HA, Lee RG, Crooke RM, Graham MJ, Liu X, Parini P, Tontonoz P, Lusis AJ, Hazen SL, Temel RE, Brown JM. The TMAO-Generating Enzyme Flavin Monooxygenase 3 Is a Central Regulator of Cholesterol Balance. Cell Rep 2015; 10:326-338. [PMID: 25600868 DOI: 10.1016/j.celrep.2014.12.036] [Citation(s) in RCA: 279] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2014] [Revised: 11/24/2014] [Accepted: 12/16/2014] [Indexed: 12/15/2022] Open
Abstract
Circulating levels of the gut microbe-derived metabolite trimethylamine-N-oxide (TMAO) have recently been linked to cardiovascular disease (CVD) risk. Here, we performed transcriptional profiling in mouse models of altered reverse cholesterol transport (RCT) and serendipitously identified the TMAO-generating enzyme flavin monooxygenase 3 (FMO3) as a powerful modifier of cholesterol metabolism and RCT. Knockdown of FMO3 in cholesterol-fed mice alters biliary lipid secretion, blunts intestinal cholesterol absorption, and limits the production of hepatic oxysterols and cholesteryl esters. Furthermore, FMO3 knockdown stimulates basal and liver X receptor (LXR)-stimulated macrophage RCT, thereby improving cholesterol balance. Conversely, FMO3 knockdown exacerbates hepatic endoplasmic reticulum (ER) stress and inflammation in part by decreasing hepatic oxysterol levels and subsequent LXR activation. FMO3 is thus identified as a central integrator of hepatic cholesterol and triacylglycerol metabolism, inflammation, and ER stress. These studies suggest that the gut microbiota-driven TMA/FMO3/TMAO pathway is a key regulator of lipid metabolism and inflammation.
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Affiliation(s)
- Manya Warrier
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Diana M Shih
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Amy C Burrows
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Daniel Ferguson
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Anthony D Gromovsky
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Amanda L Brown
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Stephanie Marshall
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Allison McDaniel
- Departments of Pathology and Biostatistics, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Rebecca C Schugar
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Zeneng Wang
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Jessica Sacks
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Xin Rong
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | | | - Jeff Chou
- Departments of Pathology and Biostatistics, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Pavlina T Ivanova
- Departments of Pharmacology and Biochemistry, The Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, USA
| | - David S Myers
- Departments of Pharmacology and Biochemistry, The Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, USA
| | - H Alex Brown
- Departments of Pharmacology and Biochemistry, The Vanderbilt Institute of Chemical Biology, Nashville, TN 37232, USA
| | - Richard G Lee
- Cardiovascular Group, Antisense Drug Discovery, Isis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - Rosanne M Crooke
- Cardiovascular Group, Antisense Drug Discovery, Isis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - Mark J Graham
- Cardiovascular Group, Antisense Drug Discovery, Isis Pharmaceuticals, Inc., Carlsbad, CA 92010, USA
| | - Xiuli Liu
- Department of Anatomical Pathology, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Paolo Parini
- Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet at Huddinge University Hospital, 141 86 Stockholm, Sweden
| | - Peter Tontonoz
- Howard Hughes Medical Institute; Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Aldon J Lusis
- Department of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Stanley L Hazen
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA
| | - Ryan E Temel
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536-0509, USA
| | - J Mark Brown
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH 44195, USA.
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74
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Dawson PA. Impact of Inhibiting Ileal Apical versus Basolateral Bile Acid Transport on Cholesterol Metabolism and Atherosclerosis in Mice. Dig Dis 2015; 33:382-7. [PMID: 26045273 PMCID: PMC4465549 DOI: 10.1159/000371691] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
BACKGROUND Bile acid sequestrants have been used for many years to treat hypercholesterolemia by increasing hepatic conversion of cholesterol to bile acids, thereby inducing hepatic LDL receptor expression and clearance of apoB-containing particles. In order to further understand the underlying molecular mechanisms linking gut-liver signaling and cholesterol homeostasis, mouse models defective in ileal apical membrane bile acid transport (Asbt-null) and ileal basolateral membrane bile acid transport (Ostα-null) were studied under basal and hypercholesterolemic conditions. KEY MESSAGES Hepatic conversion of cholesterol to bile acids is the major pathway for cholesterol catabolism and a major mechanism for cholesterol elimination. Blocking ileal apical membrane bile acid transport (Asbt-null mice) increases fecal bile acid excretion, hepatic Cyp7a1 expression, and the relative proportion of taurocholate in the bile acid pool, but decreases ileal FGF15 expression, bile acid pool size, and hepatic cholesterol content. In contrast, blocking ileal basolateral membrane bile acid transport (Ostα-null mice) increases ileal FGF15 expression, reduces hepatic Cyp7a1 expression, and increases the proportion of tauro-β-muricholic acid in the bile acid pool. In the hypercholesterolemic apoE-null background, plasma cholesterol levels and measurements of atherosclerosis were reduced in Asbt/apoE-null mice, but not in Ostα/apoE-null mice. CONCLUSIONS Blocking the intestinal absorption of bile acids at the apical versus basolateral membrane differentially affects bile acid and cholesterol metabolism, including the development of hypercholesterolemia-associated atherosclerosis. The molecular mechanism likely involves an altered regulation of ileal FGF15 expression.
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Affiliation(s)
- Paul A. Dawson
- Department of Pediatrics, Division of Gastroenterology, Hepatology and Nutrition, Emory University School of Medicine, Atlanta, GA 30322
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75
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Heinonen SE, Genové G, Bengtsson E, Hübschle T, Åkesson L, Hiss K, Benardeau A, Ylä-Herttuala S, Jönsson-Rylander AC, Gomez MF. Animal models of diabetic macrovascular complications: key players in the development of new therapeutic approaches. J Diabetes Res 2015; 2015:404085. [PMID: 25785279 PMCID: PMC4345079 DOI: 10.1155/2015/404085] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 01/26/2015] [Indexed: 12/19/2022] Open
Abstract
Diabetes mellitus is a lifelong, incapacitating metabolic disease associated with chronic macrovascular complications (coronary heart disease, stroke, and peripheral vascular disease) and microvascular disorders leading to damage of the kidneys (nephropathy) and eyes (retinopathy). Based on the current trends, the rising prevalence of diabetes worldwide will lead to increased cardiovascular morbidity and mortality. Therefore, novel means to prevent and treat these complications are needed. Under the auspices of the IMI (Innovative Medicines Initiative), the SUMMIT (SUrrogate markers for Micro- and Macrovascular hard end points for Innovative diabetes Tools) consortium is working on the development of novel animal models that better replicate vascular complications of diabetes and on the characterization of the available models. In the past years, with the high level of genomic information available and more advanced molecular tools, a very large number of models has been created. Selecting the right model for a specific study is not a trivial task and will have an impact on the study results and their interpretation. This review gathers information on the available experimental animal models of diabetic macrovascular complications and evaluates their pros and cons for research purposes as well as for drug development.
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Affiliation(s)
- Suvi E. Heinonen
- Bioscience, Cardiovascular and Metabolic Diseases, Innovative Medicines and Early Development, AstraZeneca R&D, 43183 Mölndal, Sweden
- *Suvi E. Heinonen:
| | - Guillem Genové
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 17177 Stockholm, Sweden
| | - Eva Bengtsson
- Department of Clinical Sciences, Lund University Diabetes Centre (LUDC), Lund University, 20502 Malmö, Sweden
| | - Thomas Hübschle
- R&D Diabetes Division, Translational Medicine, Sanofi-Aventis, 65926 Frankfurt am Main, Germany
| | - Lina Åkesson
- Department of Clinical Sciences, Lund University Diabetes Centre (LUDC), Lund University, 20502 Malmö, Sweden
| | - Katrin Hiss
- R&D Diabetes Division, Translational Medicine, Sanofi-Aventis, 65926 Frankfurt am Main, Germany
| | - Agnes Benardeau
- Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, 70210 Kuopio, Finland
| | - Seppo Ylä-Herttuala
- Pharmaceutical Division, pRED, CV and Metabolic Disease, Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Ann-Cathrine Jönsson-Rylander
- Bioscience, Cardiovascular and Metabolic Diseases, Innovative Medicines and Early Development, AstraZeneca R&D, 43183 Mölndal, Sweden
| | - Maria F. Gomez
- Department of Clinical Sciences, Lund University Diabetes Centre (LUDC), Lund University, 20502 Malmö, Sweden
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76
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Hidden disease susceptibility and sexual dimorphism in the heterozygous knockout of Cyp51 from cholesterol synthesis. PLoS One 2014; 9:e112787. [PMID: 25393872 PMCID: PMC4231084 DOI: 10.1371/journal.pone.0112787] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 10/15/2014] [Indexed: 01/16/2023] Open
Abstract
We examined the genotype-phenotype interactions of Cyp51+/- mice carrying one functional allele of lanosterol 14α-demethylase from cholesterol biosynthesis. No distinct developmental or morphological abnormalities were observed by routine visual inspection of Cyp51+/- and Cyp51+/+ mice and fertility was similar. We further collected a large data-set from female and male Cyp51+/- mice and controls fed for 16 weeks with three diets and applied linear regression modeling. We used 3 predictor variables (genotype, sex, diet), and 39 response variables corresponding to the organ characteristics (7), plasma parameters (7), and hepatic gene expression (25). We observed significant differences between Cyp51+/- and wild-type mice in organ characteristics and blood lipid profile. Hepatomegaly was observed in Cyp51+/- males, together with elevated total and low-density lipoprotein cholesterol. Cyp51+/- females fed high-fat, high-cholesterol diet were leaner and had elevated plasma corticosterone compared to controls. We observed elevated hepatocyte apoptosis, mitosis and lipid infiltration in heterozygous knockouts of both sexes. The Cyp51+/- females had a modified lipid storage homeostasis protecting them from weight-gain when fed high-fat high-cholesterol diet. Malfunction of one Cyp51 allele therefore initiates disease pathways towards cholesterol-linked liver pathologies and sex-dependent response to dietary challenge.
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77
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Wang J, Mitsche MA, Lütjohann D, Cohen JC, Xie XS, Hobbs HH. Relative roles of ABCG5/ABCG8 in liver and intestine. J Lipid Res 2014; 56:319-30. [PMID: 25378657 PMCID: PMC4306686 DOI: 10.1194/jlr.m054544] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABCG5 (G5) and ABCG8 (G8) form a sterol transporter that acts in liver and intestine to prevent accumulation of dietary sterols. Mutations in either G5 or G8 cause sitosterolemia, a recessive disorder characterized by sterol accumulation and premature coronary atherosclerosis. Hepatic G5G8 mediates cholesterol excretion into bile, but the function and relative importance of intestinal G5G8 has not been defined. To determine the role of intestinal G5G8, we developed liver-specific (L-G5G8(-/-)), intestine-specific (I-G5G8(-/-)), and total (G5G8(-/-)) KO mice. Tissue levels of sitosterol, the most abundant plant sterol, were >90-fold higher in G5G8(-/-) mice than in WT animals. Expression of G5G8 only in intestine or only in liver decreased tissue sterol levels by 90% when compared with G5G8(-/-) animals. Biliary sterol secretion was reduced in L-G5G8(-/-) and G5G8(-/-) mice, but not in I-G5G8(-/-) mice. Conversely, absorption of plant sterols was increased in I-G5G8(-/-) and G5G8(-/-) mice, but not in L-G5G8(-/-) mice. Reverse cholesterol transport, as assessed from the fraction of intravenously administered (3)H-cholesterol that appeared in feces, was reduced in G5G8(-/-), I-G5G8(-/-), and L-G5G8(-/-) mice. Thus, G5G8 expression in both the liver and intestine protects animals from sterol accumulation, and intestinal G5G8 contributes to extrahepatic cholesterol efflux in mice.
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Affiliation(s)
- Jin Wang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Matthew A Mitsche
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Dieter Lütjohann
- Department of Clinical Pharmacology, University of Bonn, D-53105 Bonn, Germany
| | - Jonathan C Cohen
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Xiao-Song Xie
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Helen H Hobbs
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390 Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390 Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
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78
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Meaney S. Epigenetic regulation of cholesterol homeostasis. Front Genet 2014; 5:311. [PMID: 25309573 PMCID: PMC4174035 DOI: 10.3389/fgene.2014.00311] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 08/20/2014] [Indexed: 01/15/2023] Open
Abstract
Although best known as a risk factor for cardiovascular disease, cholesterol is a vital component of all mammalian cells. In addition to key structural roles, cholesterol is a vital biochemical precursor for numerous biologically important compounds including oxysterols and bile acids, as well as acting as an activator of critical morphogenic systems (e.g., the Hedgehog system). A variety of sophisticated regulatory mechanisms interact to coordinate the overall level of cholesterol in cells, tissues and the entire organism. Accumulating evidence indicates that in additional to the more “traditional” regulatory schemes, cholesterol homeostasis is also under the control of epigenetic mechanisms such as histone acetylation and DNA methylation. The available evidence supporting a role for these mechanisms in the control of cholesterol synthesis, elimination, transport and storage are the focus of this review.
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Affiliation(s)
- Steve Meaney
- School of Biological Sciences, College of Sciences and Health, Dublin Institute of Technology Dublin, Ireland ; Environmental Sustainability and Health Institute, Dublin Institute of Technology Dublin, Ireland
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79
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Cai JS, Chen JH. The mechanism of enterohepatic circulation in the formation of gallstone disease. J Membr Biol 2014; 247:1067-82. [PMID: 25107305 PMCID: PMC4207937 DOI: 10.1007/s00232-014-9715-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Accepted: 07/25/2014] [Indexed: 12/25/2022]
Abstract
Bile acids entering into enterohepatic circulating are primary acids synthesized from cholesterol in hepatocyte. They are secreted actively across canalicular membrane and carried in bile to gallbladder, where they are concentrated during digestion. About 95 % BAs are actively taken up from the lumen of terminal ileum efficiently, leaving only approximately 5 % (or approximately 0.5 g/d) in colon, and a fraction of bile acids are passively reabsorbed after a series of modifications in the human large intestine including deconjugation and oxidation of hydroxy groups. Bile salts hydrolysis and hydroxy group dehydrogenation reactions are performed by a broad spectrum of intestinal anaerobic bacteria. Next, hepatocyte reabsorbs bile acids from sinusoidal blood, which are carried to liver through portal vein via a series of transporters. Bile acids (BAs) transporters are critical for maintenance of the enterohepatic BAs circulation, where BAs exert their multiple physiological functions including stimulation of bile flow, intestinal absorption of lipophilic nutrients, solubilization, and excretion of cholesterol. Tight regulation of BA transporters via nuclear receptors (NRs) is necessary to maintain proper BA homeostasis. In conclusion, disturbances of enterohepatic circulation may account for pathogenesis of gallstones diseases, including BAs transporters and their regulatory NRs and the metabolism of intestinal bacterias, etc.
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Affiliation(s)
- Jian-Shan Cai
- Department of General Surgery, Huashan Hospital, Fudan University, 12 Wulumuqi Road, Shanghai, 200040, People's Republic of China,
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80
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Degirolamo C, Sabbà C, Moschetta A. Intestinal nuclear receptors in HDL cholesterol metabolism. J Lipid Res 2014; 56:1262-70. [PMID: 25070952 DOI: 10.1194/jlr.r052704] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Indexed: 12/18/2022] Open
Abstract
The intestine plays a pivotal role in cholesterol homeostasis by functioning as an absorptive and secretory organ in the reverse cholesterol transport pathway. Enterocytes control cholesterol absorption, apoAI synthesis, HDL biogenesis, and nonbiliary cholesterol fecal disposal. Thus, intestine-based therapeutic interventions may hold promise in the management of diseases driven by cholesterol overload. Lipid-sensing nuclear receptors (NRs) are highly expressed in the intestinal epithelium and regulate transcriptionally the handling of cholesterol by the enterocytes. Here, we discuss the NR regulation of cholesterol fluxes across the enterocytes with special emphasis on NR exploitation as a bona fide novel HDL-raising strategy.
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Affiliation(s)
- Chiara Degirolamo
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Tumori "Giovanni Paolo II", 70124 Bari, Italy
| | - Carlo Sabbà
- Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", 70124 Bari, Italy
| | - Antonio Moschetta
- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Istituto Tumori "Giovanni Paolo II", 70124 Bari, Italy Clinica Medica "Cesare Frugoni", Department of Interdisciplinary Medicine, University of Bari "Aldo Moro", 70124 Bari, Italy
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81
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Palomino-Morales R, Alejandre MJ, Perales S, Torres C, Linares A. Effect of PUFAs on extracellular matrix production and remodeling in vascular smooth muscle cell cultures in an atherosclerotic model. EUR J LIPID SCI TECH 2014. [DOI: 10.1002/ejlt.201400141] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Rogelio Palomino-Morales
- Faculty of Sciences, Department of Biochemistry and Molecular Biology I; Campus Universitario de Fuentenueva, University of Granada; Granada Spain
| | - M. Jose Alejandre
- Faculty of Sciences, Department of Biochemistry and Molecular Biology I; Campus Universitario de Fuentenueva, University of Granada; Granada Spain
| | - Sonia Perales
- Faculty of Sciences, Department of Biochemistry and Molecular Biology I; Campus Universitario de Fuentenueva, University of Granada; Granada Spain
| | - Carolina Torres
- Faculty of Sciences, Department of Biochemistry and Molecular Biology I; Campus Universitario de Fuentenueva, University of Granada; Granada Spain
| | - Ana Linares
- Faculty of Sciences, Department of Biochemistry and Molecular Biology I; Campus Universitario de Fuentenueva, University of Granada; Granada Spain
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82
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Hofmann AF, Hagey LR. Key discoveries in bile acid chemistry and biology and their clinical applications: history of the last eight decades. J Lipid Res 2014; 55:1553-95. [PMID: 24838141 DOI: 10.1194/jlr.r049437] [Citation(s) in RCA: 230] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Indexed: 12/12/2022] Open
Abstract
During the last 80 years there have been extraordinary advances in our knowledge of the chemistry and biology of bile acids. We present here a brief history of the major achievements as we perceive them. Bernal, a physicist, determined the X-ray structure of cholesterol crystals, and his data together with the vast chemical studies of Wieland and Windaus enabled the correct structure of the steroid nucleus to be deduced. Today, C24 and C27 bile acids together with C27 bile alcohols constitute most of the bile acid "family". Patterns of bile acid hydroxylation and conjugation are summarized. Bile acid measurement encompasses the techniques of GC, HPLC, and MS, as well as enzymatic, bioluminescent, and competitive binding methods. The enterohepatic circulation of bile acids results from vectorial transport of bile acids by the ileal enterocyte and hepatocyte; the key transporters have been cloned. Bile acids are amphipathic, self-associate in solution, and form mixed micelles with polar lipids, phosphatidylcholine in bile, and fatty acids in intestinal content during triglyceride digestion. The rise and decline of dissolution of cholesterol gallstones by the ingestion of 3,7-dihydroxy bile acids is chronicled. Scientists from throughout the world have contributed to these achievements.
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Affiliation(s)
- Alan F Hofmann
- Department of Medicine, University of California, San Diego, San Diego, CA
| | - Lee R Hagey
- Department of Medicine, University of California, San Diego, San Diego, CA
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83
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Cholesterol in the retina: the best is yet to come. Prog Retin Eye Res 2014; 41:64-89. [PMID: 24704580 DOI: 10.1016/j.preteyeres.2014.03.002] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 01/09/2023]
Abstract
Historically understudied, cholesterol in the retina is receiving more attention now because of genetic studies showing that several cholesterol-related genes are risk factors for age-related macular degeneration (AMD) and because of eye pathology studies showing high cholesterol content of drusen, aging Bruch's membrane, and newly found subretinal lesions. The challenge before us is determining how the cholesterol-AMD link is realized. Meeting this challenge will require an excellent understanding these genes' roles in retinal physiology and how chorioretinal cholesterol is maintained. In the first half of this review, we will succinctly summarize physico-chemical properties of cholesterol, its distribution in the human body, general principles of maintenance and metabolism, and differences in cholesterol handling in human and mouse that impact on experimental approaches. This information will provide a backdrop to the second part of the review focusing on unique aspects of chorioretinal cholesterol homeostasis, aging in Bruch's membrane, cholesterol in AMD lesions, a model for lesion biogenesis, a model for macular vulnerability based on vascular biology, and alignment of AMD-related genes and pathobiology using cholesterol and an atherosclerosis-like progression as unifying features. We conclude with recommendations for the most important research steps we can take towards delineating the cholesterol-AMD link.
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84
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Meiliana A, Wijaya A. MicroRNAs in Lipid Metabolism and Atherosclerosis. INDONESIAN BIOMEDICAL JOURNAL 2014. [DOI: 10.18585/inabj.v6i1.39] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND: MicroRNAs (miRNA) are mediators of post-transcriptional gene expression that likely regulate most biological pathways and networks. The study of miRNAs is a rapidly emerging field; recent findings have revealed a significant role for miRNAs in atherosclerosis and lipoprotein metabolism.CONTENT: Results from recent studies demonstrated a role for miRNAs in endothelial integrity, macrophage inflammatory response to oxidized low-density lipoprotein, vascular smooth muscle cell proliferation and cholesterol synthesis. These mechanisms are all vital to the initiation and proliferation of atherosclerosis and cardiovascular disease. The importance of miRNAs has recently been recognized in cardiovascular sciences and miRNAs will likely become an integral part of our fundamental comprehension of atherosclerosis and lipoprotein metabolism. The extensive impact of miRNA mediated gene regulation and the relative ease of in vivo applicable modifications highlight the enormous potential of miRNA-based therapeutics in cardiovascular diseases.SUMMARY: miRNA studies in the field of lipid metabolism and atherosclerosis are in their infancy, and thus there is tremendous opportunity for discovery in this understudied area. The ability to target miRNAs in vivo through delivery of miRNA-mimics to enhance miRNA function, or antimiRNAs which inhibit miRNAs, has opened new avenues for the development of therapeutics for dyslipidemias and atherosclerosis, offers a unique approach to treating disease by modulating entire biological pathways. These exciting findings support the development of miRNA antagonists as potential therapeutics for the treatment of dyslipidaemia, atherosclerosis and related metabolic diseases.KEYWORDS: atherosclerosis, lipoprotein, HDL, miRNA
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85
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Zhou L, Yang H, Okoro EU, Guo Z. Up-regulation of cholesterol absorption is a mechanism for cholecystokinin-induced hypercholesterolemia. J Biol Chem 2014; 289:12989-99. [PMID: 24692543 DOI: 10.1074/jbc.m113.534388] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Excessive absorption of intestinal cholesterol is a risk factor for atherosclerosis. This report examines the effect of cholecystokinin (CCK) on plasma cholesterol level and intestinal cholesterol absorption using the in vivo models of C57BL/6 wild-type and low density lipoprotein receptor knock-out (LDLR(-/-)) mice. These data were supported by in vitro studies involving mouse primary intestinal epithelial cells and human Caco-2 cells; both express CCK receptor 1 and 2 (CCK1R and CCK2R). We found that intravenous injection of [Thr(28),Nle(31)]CCK increased plasma cholesterol levels and intestinal cholesterol absorption in both wild-type and LDLR(-/-) mice. Treatment of mouse primary intestinal epithelial cells with [Thr(28),Nle(31)]CCK increased cholesterol absorption, whereas selective inhibition of CCK1R and CCK2R with antagonists attenuated CCK-induced cholesterol absorption. In Caco-2 cells, CCK enhanced CCK1R/CCK2R heterodimerization. Knockdown of both CCK1R and CCK2 or either one of them diminished CCK-induced cholesterol absorption to the same extent. CCK also increased cell surface-associated NPC1L1 (Niemann-Pick C1-like 1) transporters but did not alter their total protein expression. Inhibition or knockdown of NPC1L1 attenuated CCK-induced cholesterol absorption. CCK enhanced phosphatidylinositide 3-kinase (PI3K) and Akt phosphorylation and augmented the interaction between NPC1L1 and Rab11a (Rab-GTPase-11a), whereas knockdown of CCK receptors or inhibition of G protein βγ dimer (Gβγ) diminished CCK-induced PI3K and Akt phosphorylation. Inhibition of PI3K and Akt or knockdown of PI3K diminished CCK-induced NPC1L1-Rab11a interaction and cholesterol absorption. Knockdown of Rab11a suppressed CCK-induced NPC1L1 translocation and cholesterol absorption. These data imply that CCK enhances cholesterol absorption by activation of a pathway involving CCK1R/CCK2R, Gβγ, PI3K, Akt, Rab11a, and NPC1L.
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Affiliation(s)
- LiChun Zhou
- From the Department of Physiology, Meharry Medical College, Nashville, Tennessee 37208
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Pramfalk C, Melhuish TA, Wotton D, Jiang ZY, Eriksson M, Parini P. TG-interacting factor 1 acts as a transcriptional repressor of sterol O-acyltransferase 2. J Lipid Res 2014; 55:709-17. [PMID: 24478032 PMCID: PMC3966704 DOI: 10.1194/jlr.m045922] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2013] [Revised: 01/26/2014] [Indexed: 11/20/2022] Open
Abstract
Acat2 [gene name: sterol O-acyltransferase 2 (SOAT2)] esterifies cholesterol in enterocytes and hepatocytes. This study aims to identify repressor elements in the human SOAT2 promoter and evaluate their in vivo relevance. We identified TG-interacting factor 1 (Tgif1) to function as an important repressor of SOAT2. Tgif1 could also block the induction of the SOAT2 promoter activity by hepatocyte nuclear factor 1α and 4α. Women have ∼ 30% higher hepatic TGIF1 mRNA compared with men. Depletion of Tgif1 in mice increased the hepatic Soat2 expression and resulted in higher hepatic lipid accumulation and plasma cholesterol levels. Tgif1 is a new player in human cholesterol metabolism.
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Affiliation(s)
- Camilla Pramfalk
- Division of Clinical Chemistry, Department of Laboratory Medicine, and Centre for Nutrition and Toxicology, NOVUM, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
- Molecular Nutrition Unit, Department of Biosciences and Nutrition, Centre for Nutrition and Toxicology, NOVUM, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Tiffany A. Melhuish
- Department of Biochemistry and Molecular Genetics and Center for Cell Signaling, University of Virginia, Charlottesville, VA
| | - David Wotton
- Department of Biochemistry and Molecular Genetics and Center for Cell Signaling, University of Virginia, Charlottesville, VA
| | - Zhao-Yan Jiang
- Department of Surgery, Shanghai Institute of Digestive Surgery, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China; and
| | - Mats Eriksson
- Molecular Nutrition Unit, Department of Biosciences and Nutrition, Centre for Nutrition and Toxicology, NOVUM, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
- Metabolism Unit, Department of Endocrinology, Metabolism and Diabetes, and Department of Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Paolo Parini
- Division of Clinical Chemistry, Department of Laboratory Medicine, and Centre for Nutrition and Toxicology, NOVUM, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
- Molecular Nutrition Unit, Department of Biosciences and Nutrition, Centre for Nutrition and Toxicology, NOVUM, Karolinska Institutet at Karolinska University Hospital Huddinge, Stockholm, Sweden
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87
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Cross-talk between liver and intestine in control of cholesterol and energy homeostasis. Mol Aspects Med 2014; 37:77-88. [PMID: 24560594 DOI: 10.1016/j.mam.2014.02.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 12/04/2013] [Accepted: 02/10/2014] [Indexed: 12/19/2022]
Abstract
A major hurdle for organisms to dispose of cholesterol is the inability to degrade the sterol nucleus which constitutes the central part of the molecule. Synthesis of the sterol nucleus requires a complex, energy costly, metabolic pathway but also generates a diverse array of intermediates serving crucial roles in cellular energy metabolism and signal transduction. This may be the reason why this complex pathway has survived evolutionary pressure. The only way to get rid of substantial amounts of cholesterol is conversion into bile acid or direct excretion of the sterol in the feces. The lack of versatility in disposal mechanisms causes a lack of flexibility to regulate cholesterol homeostasis which may underlie the considerable human pathology linked to cholesterol removal from the body. Export of cholesterol from the body requires an intricate communication between intestine and the liver. The last decade this inter-organ cross talk has been focus of intense research leading to considerable new insight. This novel information on particular the cross-talk between liver and intestine and role of bile acids as signal transducing molecules forms the focus of this review.
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88
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von Eckardstein A. Implications of torcetrapib failure for the future of HDL therapy: is HDL-cholesterol the right target? Expert Rev Cardiovasc Ther 2014; 8:345-58. [DOI: 10.1586/erc.10.6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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89
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Abstract
High-density lipoprotein (HDL) is a complex mixture of lipoproteins that is associated with many minor proteins and lipids that influence the function of HDL. Although HDL is a promising marker and potential therapeutic target based on its epidemiological data and the effects of healthy HDL in vitro in endothelial cells and macrophages, as well as based on infusion studies of reconstituted HDL in patients with hypercholesterolemia, it remains still uncertain whether or not HDL cholesterol–raising drugs will improve outcomes. Recent studies suggest that HDL becomes modified in patients with coronary artery disease or acute coronary syndrome because of oxidative processes that result in alterations in its proteome composition (proteome remodelling) leading to HDL dysfunction.
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Affiliation(s)
- Thomas F. Lüscher
- From Department of Cardiology, University Heart Center (T.F.L., U.L.), and Department of Clinical Chemistry (A.v.E.), University Hospital Zurich, Zurich, Switzerland; Division of Cardiovascular Research, Institute of Physiology, University of Zurich, Zurich, Switzerland (T.F.L., U.L.); and Department of Medicine, University of California, Los Angeles, CA (A.M.F.)
| | - Ulf Landmesser
- From Department of Cardiology, University Heart Center (T.F.L., U.L.), and Department of Clinical Chemistry (A.v.E.), University Hospital Zurich, Zurich, Switzerland; Division of Cardiovascular Research, Institute of Physiology, University of Zurich, Zurich, Switzerland (T.F.L., U.L.); and Department of Medicine, University of California, Los Angeles, CA (A.M.F.)
| | - Arnold von Eckardstein
- From Department of Cardiology, University Heart Center (T.F.L., U.L.), and Department of Clinical Chemistry (A.v.E.), University Hospital Zurich, Zurich, Switzerland; Division of Cardiovascular Research, Institute of Physiology, University of Zurich, Zurich, Switzerland (T.F.L., U.L.); and Department of Medicine, University of California, Los Angeles, CA (A.M.F.)
| | - Alan M. Fogelman
- From Department of Cardiology, University Heart Center (T.F.L., U.L.), and Department of Clinical Chemistry (A.v.E.), University Hospital Zurich, Zurich, Switzerland; Division of Cardiovascular Research, Institute of Physiology, University of Zurich, Zurich, Switzerland (T.F.L., U.L.); and Department of Medicine, University of California, Los Angeles, CA (A.M.F.)
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90
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Sanchez-Soria P, Broka D, Quach S, Hardwick RN, Cherrington NJ, Camenisch TD. Fetal exposure to arsenic results in hyperglycemia, hypercholesterolemia, and nonalcoholic fatty liver disease in adult mice. ACTA ACUST UNITED AC 2014. [DOI: 10.7243/2056-3779-1-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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91
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Reshetnyak VI. Physiological and molecular biochemical mechanisms of bile formation. World J Gastroenterol 2013; 19:7341-7360. [PMID: 24259965 PMCID: PMC3831216 DOI: 10.3748/wjg.v19.i42.7341] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 07/17/2013] [Accepted: 09/29/2013] [Indexed: 02/06/2023] Open
Abstract
This review considers the physiological and molecular biochemical mechanisms of bile formation. The composition of bile and structure of a bile canaliculus, biosynthesis and conjugation of bile acids, bile phospholipids, formation of bile micellar structures, and enterohepatic circulation of bile acids are described. In general, the review focuses on the molecular physiology of the transporting systems of the hepatocyte sinusoidal and apical membranes. Knowledge of physiological and biochemical basis of bile formation has implications for understanding the mechanisms of development of pathological processes, associated with diseases of the liver and biliary tract.
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92
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Lorbek G, Perše M, Horvat S, Björkhem I, Rozman D. Sex differences in the hepatic cholesterol sensing mechanisms in mice. Molecules 2013; 18:11067-85. [PMID: 24025456 PMCID: PMC6270450 DOI: 10.3390/molecules180911067] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Revised: 09/02/2013] [Accepted: 09/05/2013] [Indexed: 02/07/2023] Open
Abstract
Cholesterol is linked to many multifactorial disorders, including different forms of liver disease where development and severity depend on the sex. We performed a detailed analysis of cholesterol and bile acid synthesis pathways at the level of genes and metabolites combined with the expression studies of hepatic cholesterol uptake and transport in female and male mice fed with a high-fat diet with or without cholesterol. Lack of dietary cholesterol led to a stronger response of the sterol sensing mechanism in females, resulting in higher expression of cholesterogenic genes compared to males. With cholesterol in the diet, the genes were down-regulated in both sexes; however, males maintained a more efficient hepatic metabolic flux through the pathway. Females had higher content of hepatic cholesterol but this was likely not due to diminished excretion but rather due to increased synthesis and absorption. Dietary cholesterol and sex were not important for gallbladder bile acids composition. Neither sex up-regulated Cyp7a1 upon cholesterol loading and there was no compensatory up-regulation of Abcg5 or Abcg8 transporters. On the other hand, females had higher expression of the Ldlr and Cd36 genes. These findings explain sexual dimorphism of cholesterol metabolism in response to dietary cholesterol in a high-fat diet in mice, which contributes to understanding the sex-basis of cholesterol-associated liver diseases.
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Affiliation(s)
- Gregor Lorbek
- Center for Functional Genomics and Bio-Chips, Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; E-Mail:
| | - Martina Perše
- Medical Experimental Centre, Institute of Pathology, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; E-Mail:
| | - Simon Horvat
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, SI-1000 Ljubljana, Slovenia; E-Mail: or
- National Institute of Chemistry, SI-1000 Ljubljana, Slovenia
| | - Ingemar Björkhem
- Department of Laboratory Medicine, Division of Clinical Chemistry, Karolinska Institute, Karolinska University Hospital, SE-141 86 Huddinge, Sweden; E-Mail:
| | - Damjana Rozman
- Center for Functional Genomics and Bio-Chips, Institute of Biochemistry, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia; E-Mail:
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93
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Ekholm E, Nilsson R, Groop L, Pramfalk C. Alterations in bile acid synthesis in carriers of hepatocyte nuclear factor 1α mutations. J Intern Med 2013; 274:263-72. [PMID: 23607861 DOI: 10.1111/joim.12082] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVES Heterozygous mutations in hepatocyte nuclear factor 1α (HNF1α) cause maturity onset diabetes of the young 3 (MODY3), an autosomal dominant form of diabetes. Deficiency of HNF1α in mice results in diabetes, hypercholesterolaemia and increased bile acid (BA) and cholesterol synthesis. Little is known about alterations in lipid metabolism in patients with MODY3. The aim of this study was to investigate whether patients with MODY3 have altered cholesterol and BA synthesis and intestinal cholesterol absorption. A secondary aim was to investigate the effects of HNF1α mutations on the transcriptional regulation of BA metabolism. METHODS Plasma biomarkers of BA and cholesterol synthesis and intestinal cholesterol absorption were measured in patients with MODY3 (n = 19) and in matched healthy control subjects (n = 15). Cotransfection experiments were performed with several promoters involved in BA metabolism along with expression vectors carrying the mutations found in these patients. RESULTS Plasma analysis showed higher levels of BA synthesis in patients with MODY3. No differences were observed in cholesterol synthesis or intestinal cholesterol absorption. Cotransfection experiments showed that one of the mutations (P379A) increased the induction of the cholesterol 7α-hydroxylase promoter compared with HNF1α, without further differences in other studied promoters. By contrast, the other four mutations (L107I, T260M, P291fsinsC and R131Q) reduced the induction of the farnesoid X receptor (FXR) promoter, which was followed by reduced repression of the small heterodimer partner promoter. In addition, these mutations also reduced the induction of the apical sodium-dependent bile salt transporter promoter. CONCLUSIONS BA synthesis is increased in patients with MODY3 compared with control subjects. Mutations in HNF1α affect promoters involved in BA metabolism.
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Affiliation(s)
- E Ekholm
- Department of Clinical Sciences, Diabetes and Endocrinology, Malmö University Hospital, Sweden
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94
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Lee SD, Thornton SJ, Sachs-Barrable K, Kim JH, Wasan KM. Evaluation of the contribution of the ATP binding cassette transporter, P-glycoprotein, to in vivo cholesterol homeostasis. Mol Pharm 2013; 10:3203-12. [PMID: 23750858 DOI: 10.1021/mp4002415] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
P-glycoprotein (Pgp, encoded by ABCB1, commonly known as MDR1), an ATP-dependent transporter with a broad range of hydrophobic drug substrates, has been associated with the in vitro intracellular transport of cholesterol; however, these findings have not been confirmed in vivo. In this manuscript we tested the contributions of Pgp to in vivo cholesterol homeostasis by comparing the cholesterol phenotype of wild type mice with mice lacking both murine isoforms of Pgp (Abcb1a(-/-)/1b(-/-)) by measuring cholesterol absorption, circulating cholesterol, and lipoprotein cholesterol profiles. The mice were fed diets containing normal or high levels of dietary fat (25% vs 45% kcal from fat) and cholesterol (0.02% vs 0.20% w/w) for 8 weeks to challenge their capacity to maintain homeostasis. There were no significant differences in cholesterol absorption, circulating cholesterol levels, and lipoprotein profiles between Pgp knockout and wild type mice fed matching diets. Compensatory shifts were observed in the activation of two key transcription factors involved in maintaining cholesterol balance, the Liver X Receptor and SREBP-2, which may have maintained the wild type phenotype in the knockout mice. Deletion of Pgp affected the molar composition of gallbladder bile, when the mice were fed diets containing high levels of dietary fat, cholesterol, or both. The mole fraction of bile salts was reduced in the gallbladder bile of Pgp knockout mice, while the mole fraction of cholesterol was increased. In this paper, we provide evidence that Pgp knockout mice maintain cholesterol homeostasis, even when challenged with high cholesterol diets. We suggest that the specific shifts in cholesterol regulatory networks identified in the jejunum and liver of the knockout mice may have compensated for the lack of Pgp. Our finding that Pgp knockout mice were unable to maintain gallbladder bile composition when challenged with high dietary fat and/or cholesterol compliments recent reports that Pgp may be a secondary bile salt export pump.
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Affiliation(s)
- Stephen D Lee
- Faculty of Pharmaceutical Sciences, University of British Columbia , 2405 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3
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95
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Ignatova ID, Angdisen J, Moran E, Schulman IG. Differential regulation of gene expression by LXRs in response to macrophage cholesterol loading. Mol Endocrinol 2013; 27:1036-47. [PMID: 23686114 DOI: 10.1210/me.2013-1051] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The ability of cells to precisely control gene expression in response to intracellular and extracellular signals plays an important role in both normal physiology and in pathological settings. For instance, the accumulation of excess cholesterol by macrophages initiates a genetic response mediated by the liver X receptors (LXRs)-α (NR1H3) and LXRβ (NR1H2), which facilitates the transport of cholesterol out of cells to high-density lipoprotein particles. Studies using synthetic LXR agonists have also demonstrated that macrophage LXR activation simultaneously induces a second network of genes that promotes fatty acid and triglyceride synthesis that may support the detoxification of excess free cholesterol by storage in the ester form. We now show that treatment of human THP-1 macrophages with endogenous or synthetic LXR ligands stimulates both transcriptional and posttranscriptional pathways that result in the selective recruitment of the LXRα subtype to LXR-regulated promoters. Interestingly, when human or mouse macrophages are loaded with cholesterol under conditions that mimic the development of atherogenic macrophage foam cells, a selective LXR response is generated that induces genes mediating cholesterol transport but does not coordinately regulate genes involved in fatty acid synthesis. The gene-selective response to cholesterol loading occurs, even in the presence of LXRα binding to the promoter of the gene encoding the sterol regulatory element-binding protein-1c, the master transcriptional regulator of fatty acid synthesis. The ability of promoter bound LXRα to recruit RNA polymerase to the sterol regulatory element-binding protein-1c promoter, however, appears to be ligand selective.
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Affiliation(s)
- Irena D Ignatova
- Department of Pharmacology, University of Virginia, 1300 Jefferson Park Avenue, PO Box 800735, Charlottesville, Virginia 22908, USA.
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96
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Bura KS, Lord C, Marshall S, McDaniel A, Thomas G, Warrier M, Zhang J, Davis MA, Sawyer JK, Shah R, Wilson MD, Dikkers A, Tietge UJF, Collet X, Rudel LL, Temel RE, Brown JM. Intestinal SR-BI does not impact cholesterol absorption or transintestinal cholesterol efflux in mice. J Lipid Res 2013; 54:1567-1577. [PMID: 23564696 DOI: 10.1194/jlr.m034454] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Reverse cholesterol transport (RCT) can proceed through the classic hepatobiliary route or through the nonbiliary transintestinal cholesterol efflux (TICE) pathway. Scavenger receptor class B type I (SR-BI) plays a critical role in the classic hepatobiliary route of RCT. However, the role of SR-BI in TICE has not been studied. To examine the role of intestinal SR-BI in TICE, sterol balance was measured in control mice and mice transgenically overexpressing SR-BI in the proximal small intestine (SR-BI(hApoCIII-ApoAIV-Tg)). SR-BI(hApoCIII-ApoAIV-Tg) mice had significantly lower plasma cholesterol levels compared with wild-type controls, yet SR-BI(hApoCIII-ApoAIV-Tg) mice had normal fractional cholesterol absorption and fecal neutral sterol excretion. Both in the absence or presence of ezetimibe, intestinal SR-BI overexpression had no impact on the amount of cholesterol excreted in the feces. To specifically study effects of intestinal SR-BI on TICE we crossed SR-BI(hApoCIII-ApoAIV-Tg) mice into a mouse model that preferentially utilized the TICE pathway for RCT (Niemann-Pick C1-like 1 liver transgenic), and likewise found no alterations in cholesterol absorption or fecal sterol excretion. Finally, mice lacking SR-BI in all tissues also exhibited normal cholesterol absorption and fecal cholesterol disposal. Collectively, these results suggest that SR-BI is not rate limiting for intestinal cholesterol absorption or for fecal neutral sterol loss through the TICE pathway.
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Affiliation(s)
- Kanwardeep S Bura
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Caleb Lord
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Stephanie Marshall
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Allison McDaniel
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Gwyn Thomas
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Manya Warrier
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Jun Zhang
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Matthew A Davis
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Janet K Sawyer
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Ramesh Shah
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Martha D Wilson
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Arne Dikkers
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Uwe J F Tietge
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Xavier Collet
- INSERM U1048, Institute of Metabolic and Cardiovascular Diseases of Rangueil Hospital, BP 84225, Toulouse, France
| | - Lawrence L Rudel
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC
| | - Ryan E Temel
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC.
| | - J Mark Brown
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC.
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Martel C, Li W, Fulp B, Platt AM, Gautier EL, Westerterp M, Bittman R, Tall AR, Chen SH, Thomas MJ, Kreisel D, Swartz MA, Sorci-Thomas MG, Randolph GJ. Lymphatic vasculature mediates macrophage reverse cholesterol transport in mice. J Clin Invest 2013; 123:1571-9. [PMID: 23524964 DOI: 10.1172/jci63685] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 01/03/2013] [Indexed: 11/17/2022] Open
Abstract
Reverse cholesterol transport (RCT) refers to the mobilization of cholesterol on HDL particles (HDL-C) from extravascular tissues to plasma, ultimately for fecal excretion. Little is known about how HDL-C leaves peripheral tissues to reach plasma. We first used 2 models of disrupted lymphatic drainage from skin--1 surgical and the other genetic--to quantitatively track RCT following injection of [3H]-cholesterol-loaded macrophages upstream of blocked or absent lymphatic vessels. Macrophage RCT was markedly impaired in both models, even at sites with a leaky vasculature. Inhibited RCT was downstream of cholesterol efflux from macrophages, since macrophage efflux of a fluorescent cholesterol analog (BODIPY-cholesterol) was not altered by impaired lymphatic drainage. We next addressed whether RCT was mediated by lymphatic vessels from the aortic wall by loading the aortae of donor atherosclerotic Apoe-deficient mice with [2H]6-labeled cholesterol and surgically transplanting these aortae into recipient Apoe-deficient mice that were treated with anti-VEGFR3 antibody to block lymphatic regrowth or with control antibody to allow such regrowth. [2H]-Cholesterol was retained in aortae of anti-VEGFR3-treated mice. Thus, the lymphatic vessel route is critical for RCT from multiple tissues, including the aortic wall. These results suggest that supporting lymphatic transport function may facilitate cholesterol clearance in therapies aimed at reversing atherosclerosis.
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Affiliation(s)
- Catherine Martel
- Department of Gene and Cell Medicine, Mount Sinai School of Medicine, New York, New York, USA
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99
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Cholesterol: its regulation and role in central nervous system disorders. CHOLESTEROL 2012; 2012:292598. [PMID: 23119149 PMCID: PMC3483652 DOI: 10.1155/2012/292598] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 09/03/2012] [Accepted: 09/10/2012] [Indexed: 02/08/2023]
Abstract
Cholesterol is a major constituent of the human brain, and the brain is the most cholesterol-rich organ. Numerous lipoprotein receptors and apolipoproteins are expressed in the brain. Cholesterol is tightly regulated between the major brain cells and is essential for normal brain development. The metabolism of brain cholesterol differs markedly from that of other tissues. Brain cholesterol is primarily derived by de novo synthesis and the blood brain barrier prevents the uptake of lipoprotein cholesterol from the circulation. Defects in cholesterol metabolism lead to structural and functional central nervous system diseases such as Smith-Lemli-Opitz syndrome, Niemann-Pick type C disease, and Alzheimer's disease. These diseases affect different metabolic pathways (cholesterol biosynthesis, lipid transport and lipoprotein assembly, apolipoproteins, lipoprotein receptors, and signaling molecules). We review the metabolic pathways of cholesterol in the CNS and its cell-specific and microdomain-specific interaction with other pathways such as the amyloid precursor protein and discuss potential treatment strategies as well as the effects of the widespread use of LDL cholesterol-lowering drugs on brain functions.
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100
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Abstract
OBJECTIVES Polyethylene glycol (PEG) is a frequently used laxative agent. It is unknown, however, whether PEG affects the absorptive capacity of the intestine. Reduced lipid (dietary fat and cholesterol) absorption induced by long-term PEG treatment could negatively affect growth in children. We tested whether PEG accelerates gastrointestinal transit and alters lipid absorption and plasma lipid levels. METHODS Wistar rats were administered drinking water with or without PEG (7%) for 2 weeks. We studied whole gut transit time by recording the first appearance of red feces after intragastric carmine red administration. We measured plasma concentrations of cholesterol and triglycerides, dietary fat absorption by 48-hour fat balance and by plasma appearance of intragastrically administered stable-isotope labeled fats, and cholesterol absorption with a dual stable isotope technique. RESULTS PEG decreased whole gut transit time by 20% (P=0.028) without causing diarrhea. PEG treatment did neither affects overall dietary fat balance nor fat uptake kinetics, cholesterol absorption, or plasma lipid concentrations. CONCLUSIONS PEG does not affect lipid absorption nor steady-state plasma lipid levels in rats, although it accelerates the gastrointestinal transit.
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