1
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Garrido-Sanchez L, Leiva-Badosa E, Llop-Talaveron J, Pintó-Sala X, Lozano-Andreu T, Corbella-Inglés E, Alia-Ramos P, Arias-Barquet L, Ramon-Torrel JM, Badía-Tahull MB. Blood Phytosterol Concentration and Genetic Variant Associations in a Sample Population. Nutrients 2024; 16:1067. [PMID: 38613098 PMCID: PMC11013666 DOI: 10.3390/nu16071067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/26/2024] [Accepted: 04/01/2024] [Indexed: 04/14/2024] Open
Abstract
The main objective of this study was to determine plasma levels of PS and to study SNVs rs41360247, rs4245791, rs4148217, and rs11887534 of ABCG8 and the r657152 SNV at the ABO blood group locus in a sample of a population treated at our hospital, and to determine whether these SNVs are related to plasma PS concentrations. The secondary objective was to establish the variables associated with plasma PS concentrations in adults. Participants completed a dietary habit questionnaire and a blood sample was collected to obtain the following variables: campesterol, sitosterol, sitostanol, lanosterol, stigmasterol, biochemical parameters, and the SNVs. In addition, biometric and demographic variables were also recorded. In the generalized linear model, cholesterol and age were positively associated with total PS levels, while BMI was negatively related. For rs4245791, homozygous T allele individuals showed a significantly lower campesterol concentration compared with C homozygotes, and the GG alleles of rs657152 had the lowest levels of campesterol compared with the other alleles of the SNV. Conclusions: The screening of certain SNVs could help prevent the increase in plasma PS and maybe PNALD in some patients. However, further studies on the determinants of plasma phytosterol concentrations are needed.
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Affiliation(s)
- Leticia Garrido-Sanchez
- Pharmacy Department, Hospital Universitari Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Elisabet Leiva-Badosa
- Pharmacy Department, Hospital Universitari Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Josep Llop-Talaveron
- Pharmacy Department, Hospital Universitari Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Xavier Pintó-Sala
- Cardiovascular Risk Unit, Internal Medicine, Hospital Universitari de Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain; (X.P.-S.)
| | - Toni Lozano-Andreu
- Pharmacy Department, Institut Català d’Oncologia, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Emili Corbella-Inglés
- Cardiovascular Risk Unit, Internal Medicine, Hospital Universitari de Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain; (X.P.-S.)
| | - Pedro Alia-Ramos
- Clinical Laboratory Department, Hospital Universitari Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Lluis Arias-Barquet
- Ophthalmology Department, Hospital Universitari Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Josep Maria Ramon-Torrel
- Preventive Medicine Department, Hospital Universitari Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
| | - Maria B. Badía-Tahull
- Pharmacy Department, Hospital Universitari Bellvitge, IDIBELL, Universitat Barcelona, 08907 L’Hospitalet de Llobregat, Spain
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2
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Windler E, Beil FU, Berthold HK, Gouni-Berthold I, Kassner U, Klose G, Lorkowski S, März W, Parhofer KG, Plat J, Silbernagel G, Steinhagen-Thiessen E, Weingärtner O, Zyriax BC, Lütjohann D. Phytosterols and Cardiovascular Risk Evaluated against the Background of Phytosterolemia Cases-A German Expert Panel Statement. Nutrients 2023; 15:nu15040828. [PMID: 36839186 PMCID: PMC9963617 DOI: 10.3390/nu15040828] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 02/08/2023] Open
Abstract
Phytosterols (PSs) have been proposed as dietary means to lower plasma LDL-C. However, concerns are raised that PSs may exert atherogenic effects, which would offset this benefit. Phytosterolemia was thought to mimic increased plasma PSs observed after the consumption of PS-enriched foods. This expert statement examines the possibility of specific atherogenicity of PSs based on sterol metabolism, experimental, animal, and human data. Observational studies show no evidence that plasma PS concentrations would be associated with an increased risk of atherosclerosis or cardiovascular (CV) events. Since variants of the ABCG5/8 transporter affect the absorption of cholesterol and non-cholesterol sterols, Mendelian randomization studies examining the effects of ABCG5/8 polymorphisms cannot support or refute the potential atherogenic effects of PSs due to pleiotropy. In homozygous patients with phytosterolemia, total PS concentrations are ~4000% higher than under physiological conditions. The prevalence of atherosclerosis in these individuals is variable and may mainly relate to concomitant elevated LDL-C. Consuming PS-enriched foods increases PS concentrations by ~35%. Hence, PSs, on a molar basis, would need to have 20-40 times higher atherogenicity than cholesterol to offset their cholesterol reduction benefit. Based on their LDL-C lowering and absence of adverse safety signals, PSs offer a dietary approach to cholesterol management. However, their clinical benefits have not been established in long-term CV endpoint studies.
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Affiliation(s)
- Eberhard Windler
- Preventive Medicine, University Heart Center, University Hospital Hamburg-Eppendorf, Hamburg-Eppendorf, Martinistr. 52-Bldg. N26, 20246 Hamburg, Germany
| | - Frank-Ulrich Beil
- Ambulanzzentrum, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Heiner K. Berthold
- Department of Internal Medicine and Geriatrics, Bethel Clinic, 33611 Bielefeld, Germany
| | - Ioanna Gouni-Berthold
- Center for Endocrinology, Diabetes and Preventive Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Ursula Kassner
- Lipid Clinic at the Interdisciplinary Metabolism Center, Charite-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Gerald Klose
- Praxen Dres. T. Beckenbauer & S. Maierhof, Am Markt 11, 28195 Bremen und Dres. I. van de Loo & K. Spieker, Gerold Janssen Straße 2 A, 28359 Bremen, Germany
| | - Stefan Lorkowski
- Institute of Nutritional Science and Competence Cluster for Nutrition and Cardiovascular Health (nutriCARD), Halle-Jena-Leipzig, Friedrich Schiller University Jena, Dornburger Str. 25, 07743 Jena, Germany
| | - Winfried März
- SYNLAB Akademie für Ärztliche Fortbildung, SYNLAB Holding Deutschland GmbH, P5,7, 68161 Mannheim, Germany
- Medical Clinic V, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, 8010 Graz, Austria
- Correspondence:
| | - Klaus G. Parhofer
- Medizinische Klinik IV, Klinikum der Universität München, Grosshadern, Marchioninistr. 15, 81377 München, Germany
| | - Jogchum Plat
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, 6211 LK Maastricht, The Netherlands
| | - Günter Silbernagel
- Division of Vascular Medicine, Department of Internal Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Elisabeth Steinhagen-Thiessen
- Arbeitsbereich Lipidstoffwechsel der Medizinischen Klinik für Endokrinologie und Stoffwechselmedizin, Charité—Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Oliver Weingärtner
- Klinik für Innere Medizin I, Universitätskliniken Jena, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
| | - Birgit-Christiane Zyriax
- Midwifery Science—Health Care Research and Prevention, Research Group, Preventive Medicine and Nutrition, Institute for Health Services Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, 53127 Bonn, Germany
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3
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Shen MF, Hu YN, Chen WX, Liao LS, Wu M, Wu QY, Zhang JH, Zhang YP, Luo JW, Lin XF. Clinical and Genetic Analysis of a Family With Sitosterolemia Caused by a Novel ATP-Binding Cassette Subfamily G Member 5 Compound Heterozygous Mutation. Front Cardiovasc Med 2022; 9:887618. [PMID: 35557526 PMCID: PMC9086554 DOI: 10.3389/fcvm.2022.887618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 04/05/2022] [Indexed: 11/13/2022] Open
Abstract
Sitosterolemia (OMIM ##210250), also known as phytosterolemia, is a rare autosomal recessive disorder caused by mutations in the ATP-binding cassette subfamily G member 5 (ABCG5) or member 8 (ABCG8) genes. This leads to abnormal functions of the transporter sterolin-1 protein encoded by ABCG5 and sterolin-2 protein encoded by ABCG8, respectively, which can hinder the formation of stable ABCG5/G8 heterodimers, decreasing its ability to transport sterols. As a result, phytosterols in tissue or plasma are significantly increased, leading to early onset atherosclerosis-related diseases and xanthelasma of tendons and skin. In this study, whole exome sequencing was performed on a Chinese Han proband with sitosterolemia to capture the target gene and screen for suspected pathogenic mutations. Sanger sequencing of the family members was performed to verify the relationship between family genetics and phenotypes. The structural and functional changes in the transporter sterolin-1 protein after the responsible mutation were predicted using bioinformatics analysis. A novel compound heterozygous mutation in the ABCG5 gene (NM_022436) was identified in a proband with sitosterolemia, one of which was inherited from the father: c.296T >G (p.M99R), and one from the mother: c.−76 C >T. SIFT, Polyphen2, and Mutation Taster software predicted that p.M99R may be the responsible variant and a novel variant. RNAFold software predicts that c.−76 C >T may affect the transcriptional information or the binding of RNA binding proteins by regulating the structure of RNA, and ultimately affect gene transcription or RNA stability and translation. Swiss model software predicts that the amino acid sequence around p.M99R is highly conserved, and p.M99R leads to instability of the tertiary structure of the ABCG5/ABCG8 heterodimer. GPS 5.0 predicted that M99R affects the phosphorylation of nearby amino acid sequences, and DUET and VarSite software predicted that M99R affects the stability of sterolin-1 and cause disease. The p.M99R and c.−76 C >T mutations led to the formation of unstable heterodimers, which disturbed sterol absorption and excretion in vivo. The compound heterozygous variants c.296 T >G (p.m99r) and C.−76 C >T on exon 3 of ABCG5 in this family may be the molecular genetic basis of sitosterolemia.
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Affiliation(s)
- Ming-fang Shen
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
- Pediatrics Department, Fujian Provincial Hospital, Fuzhou, China
| | - Ya-nan Hu
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Wei-xiang Chen
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
- Pediatrics Department, Fujian Provincial Hospital, Fuzhou, China
| | - Li-sheng Liao
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
- Department of Hematology, Fujian Provincial Hospital, Fuzhou, China
| | - Min Wu
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Qiu-yan Wu
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Jian-hui Zhang
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Yan-ping Zhang
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
| | - Jie-wei Luo
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
- Department of Traditional Chinese Medicine, Fujian Provincial Hospital, Fuzhou, China
- *Correspondence: Jie-wei Luo,
| | - Xin-fu Lin
- Fujian Provincial Hospital, Shengli Clinical Medical College of Fujian Medical University, Fuzhou, China
- Pediatrics Department, Fujian Provincial Hospital, Fuzhou, China
- Xin-fu Lin,
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4
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Zhou Z, Su X, Cai Y, Ting TH, Zhang W, Lin Y, Xu A, Mao X, Zeng C, Liu L, Li X. Features of chinese patients with sitosterolemia. Lipids Health Dis 2022; 21:11. [PMID: 35042526 PMCID: PMC8764812 DOI: 10.1186/s12944-021-01619-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Accepted: 12/24/2021] [Indexed: 11/10/2022] Open
Abstract
Background Sitosterolemia is a lipid disorder characterized by the accumulation of phytosterols in plasma and organs, caused by mutations in the ABCG5 and/or ABCG8 genes. The disease is frequently misdiagnosed and mistreated as familial hypercholesterolemia (FH). To gain a better understanding of the disease, the current status of diagnosis and treatment of Chinese patients with sitosterolemia was reviewed and summarized. Method Literature search was performed. The clinical features and molecular characteristics of Chinese patients with sitosterolemia were analysed. Four children with sitosterolemia and the treatment experience were described. Results Fifty-five patients with sitosterolemia have been reported in China. These patients were aged from 3 months to 67 years at diagnosis, and the median was 8 years of age. Several complications, such as xanthomas in 47 patients (85%), thrombocytopenia in 17 patients (31%), anemia in 14 patients (25%), and cardiovascular damage in 12 patients (22%), were observed. Thirty-nine patients (71%) exhibited mutations in the ABCG5 gene, 15 patients (27%) showed mutations in ABCG8, and variations in both genes occurred in one patient (2%). A patient with two clinically rare diseases, namely, sitosterolemia and glycogen storage disease type VI (GSD VI)), is reported here for the first time. The four reported patients were treated with low cholesterol and phytosterol-limited diet alone or combined with cholestyramine. Even though decreases were observed for total plasma cholesterol (TC) and low-density-lipoprotein cholesterol (LDL-C), and these levels were as low as normal in some patients, the levels of plant sterols remained above the normal range. However, TC, LDL-C and plant sterol levels remained at high levels in patients treated with a control diet control only. Conclusions The analysis reveals that different from Caucasians carrying mainly variations in ABCG8, most Chinese patients have mutations in the ABCG5 gene, and Arg446Ter, Gln251Ter, anArg389His might be hot-spot mutations in Chinese patients. The current survey provides clinical data to enable the development of a standardized protocol for the diagnosis and treatment of sitosterolemia in China.
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Affiliation(s)
- Zhizi Zhou
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Xueying Su
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Yanna Cai
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Tzer Hwu Ting
- Department of Pediatrics, Faculty of Medicine & Health Sciences, University Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - Wen Zhang
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Yunting Lin
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Aijing Xu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Xiaojian Mao
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Chunhua Zeng
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China
| | - Li Liu
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China.
| | - Xiuzhen Li
- Department of Genetics and Endocrinology, Guangzhou Women and Children's Medical Center, 9 Jinsui Road, 510623, Guangzhou, Guangdong, China.
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5
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Khunweeraphong N, Kuchler K. Multidrug Resistance in Mammals and Fungi-From MDR to PDR: A Rocky Road from Atomic Structures to Transport Mechanisms. Int J Mol Sci 2021; 22:4806. [PMID: 33946618 PMCID: PMC8124828 DOI: 10.3390/ijms22094806] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/19/2022] Open
Abstract
Multidrug resistance (MDR) can be a serious complication for the treatment of cancer as well as for microbial and parasitic infections. Dysregulated overexpression of several members of the ATP-binding cassette transporter families have been intimately linked to MDR phenomena. Three paradigm ABC transporter members, ABCB1 (P-gp), ABCC1 (MRP1) and ABCG2 (BCRP) appear to act as brothers in arms in promoting or causing MDR in a variety of therapeutic cancer settings. However, their molecular mechanisms of action, the basis for their broad and overlapping substrate selectivity, remains ill-posed. The rapidly increasing numbers of high-resolution atomic structures from X-ray crystallography or cryo-EM of mammalian ABC multidrug transporters initiated a new era towards a better understanding of structure-function relationships, and for the dynamics and mechanisms driving their transport cycles. In addition, the atomic structures offered new evolutionary perspectives in cases where transport systems have been structurally conserved from bacteria to humans, including the pleiotropic drug resistance (PDR) family in fungal pathogens for which high resolution structures are as yet unavailable. In this review, we will focus the discussion on comparative mechanisms of mammalian ABCG and fungal PDR transporters, owing to their close evolutionary relationships. In fact, the atomic structures of ABCG2 offer excellent models for a better understanding of fungal PDR transporters. Based on comparative structural models of ABCG transporters and fungal PDRs, we propose closely related or even conserved catalytic cycles, thus offering new therapeutic perspectives for preventing MDR in infectious disease settings.
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Affiliation(s)
| | - Karl Kuchler
- Center for Medical Biochemistry, Max Perutz Labs Vienna, Campus Vienna Biocenter, Medical University of Vienna, Dr. Bohr-Gasse 9/2, A-1030 Vienna, Austria;
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6
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Williams K, Segard A, Graf GA. Sitosterolemia: Twenty Years of Discovery of the Function of ABCG5ABCG8. Int J Mol Sci 2021; 22:2641. [PMID: 33807969 PMCID: PMC7961684 DOI: 10.3390/ijms22052641] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/19/2021] [Accepted: 02/26/2021] [Indexed: 02/06/2023] Open
Abstract
Sitosterolemia is a lipid disorder characterized by the accumulation of dietary xenosterols in plasma and tissues caused by mutations in either ABCG5 or ABCG8. ABCG5 ABCG8 encodes a pair of ABC half transporters that form a heterodimer (G5G8), which then traffics to the surface of hepatocytes and enterocytes and promotes the secretion of cholesterol and xenosterols into the bile and the intestinal lumen. We review the literature from the initial description of the disease, the discovery of its genetic basis, current therapy, and what has been learned from animal, cellular, and molecular investigations of the transporter in the twenty years since its discovery. The genomic era has revealed that there are far more carriers of loss of function mutations and likely pathogenic variants of ABCG5 ABCG8 than previously thought. The impact of these variants on G5G8 structure and activity are largely unknown. We propose a classification system for ABCG5 ABCG8 mutants based on previously published systems for diseases caused by defects in ABC transporters. This system establishes a framework for the comprehensive analysis of disease-associated variants and their impact on G5G8 structure-function.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 5/genetics
- ATP Binding Cassette Transporter, Subfamily G, Member 5/history
- ATP Binding Cassette Transporter, Subfamily G, Member 5/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 8/genetics
- ATP Binding Cassette Transporter, Subfamily G, Member 8/history
- ATP Binding Cassette Transporter, Subfamily G, Member 8/metabolism
- Animals
- Cholesterol/metabolism
- Enterocytes/metabolism
- Enterocytes/pathology
- Hepatocytes/metabolism
- Hepatocytes/pathology
- History, 21st Century
- Humans
- Hypercholesterolemia/genetics
- Hypercholesterolemia/history
- Hypercholesterolemia/metabolism
- Hypercholesterolemia/pathology
- Intestinal Diseases/genetics
- Intestinal Diseases/history
- Intestinal Diseases/metabolism
- Intestinal Diseases/pathology
- Lipid Metabolism, Inborn Errors/genetics
- Lipid Metabolism, Inborn Errors/history
- Lipid Metabolism, Inborn Errors/metabolism
- Lipid Metabolism, Inborn Errors/pathology
- Lipoproteins/genetics
- Lipoproteins/history
- Lipoproteins/metabolism
- Mutation
- Phytosterols/adverse effects
- Phytosterols/genetics
- Phytosterols/history
- Phytosterols/metabolism
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Affiliation(s)
- Kori Williams
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA; (K.W.); (A.S.)
| | - Allison Segard
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA; (K.W.); (A.S.)
| | - Gregory A. Graf
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA; (K.W.); (A.S.)
- Saha Cardiovascular Research Center, Lexington, KY 40536, USA
- Barnstable Brown Diabetes and Obesity Center, Lexington, KY 40536, USA
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7
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Tanaka H, Watanabe Y, Hirano S, Tada H, Nomura A, Kawashiri MA, Takenaga M. Sitosterolemia Exhibiting Severe Hypercholesterolemia with Tendon Xanthomas Due to Compound Heterozygous ABCG5 Gene Mutations Treated with Ezetimibe and Alirocumab. Intern Med 2020; 59:3033-3037. [PMID: 32713907 PMCID: PMC7759703 DOI: 10.2169/internalmedicine.3811-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We herein report a rare case presenting with severe hypercholesterolemia, massive Achilles tendon xanthomas, and multi-vessel coronary artery disease. Initially, the patient was misdiagnosed with familial hypercholesterolemia. However, a genetic analysis using our custom sequencing panel covering genes associated with Mendelian lipid disorders revealed him to have a genetic basis of sitosterolemia with compound heterozygous mutations in the adenosine triphosphate binding cassette subfamily G5 (ABCG5) gene. A comprehensive genetic analysis can be particularly useful for diagnosing cases with severe phenotypes, leading to appropriate and medical therapies. Our patient was refractory to statins, whereas ezetimibe and PCSK9 inhibitor with a low-plant-sterol diet successfully reduced his serum levels of low-density lipoprotein cholesterol.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 5/genetics
- Achilles Tendon/physiopathology
- Antibodies, Monoclonal, Humanized/therapeutic use
- Anticholesteremic Agents/therapeutic use
- Cholesterol, LDL/blood
- Cholesterol, LDL/drug effects
- Ezetimibe/therapeutic use
- Humans
- Hypercholesterolemia/complications
- Hypercholesterolemia/diagnosis
- Hypercholesterolemia/drug therapy
- Hypercholesterolemia/etiology
- Hypercholesterolemia/genetics
- Intestinal Diseases/complications
- Intestinal Diseases/diagnosis
- Intestinal Diseases/drug therapy
- Intestinal Diseases/genetics
- Lipid Metabolism, Inborn Errors/complications
- Lipid Metabolism, Inborn Errors/diagnosis
- Lipid Metabolism, Inborn Errors/drug therapy
- Lipid Metabolism, Inborn Errors/genetics
- Male
- Middle Aged
- Mutation
- Phytosterols/adverse effects
- Phytosterols/genetics
- Treatment Outcome
- Xanthomatosis/drug therapy
- Xanthomatosis/etiology
- Xanthomatosis/physiopathology
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Affiliation(s)
- Hiroki Tanaka
- Department of Cardiovascular Medicine, Fujimoto Central Hospital, Japan
| | - Yuki Watanabe
- Department of Cardiovascular Medicine, Fujimoto Central Hospital, Japan
| | - Shuji Hirano
- Department of Cardiovascular Medicine, Fujimoto Central Hospital, Japan
| | - Hayato Tada
- Department of Cardiology, Kanazawa University Graduate School of Medicine, Japan
| | - Akihiro Nomura
- Department of Cardiology, Kanazawa University Graduate School of Medicine, Japan
| | - Masa-Aki Kawashiri
- Department of Cardiology, Kanazawa University Graduate School of Medicine, Japan
| | - Makoto Takenaga
- Department of Cardiovascular Medicine, Fujimoto Central Hospital, Japan
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8
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Khunweeraphong N, Kuchler K. The first intracellular loop is essential for the catalytic cycle of the human ABCG2 multidrug resistance transporter. FEBS Lett 2020; 594:4059-4075. [PMID: 33169382 PMCID: PMC7756363 DOI: 10.1002/1873-3468.13994] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/03/2020] [Indexed: 12/16/2022]
Abstract
The human multidrug transporter ABCG2 is required for physiological detoxification and mediates anticancer drug resistance. Here, we identify pivotal residues in the first intracellular loop (ICL1), constituting an intrinsic part of the transmission interface. The architecture includes a triple helical bundle formed by the hot spot helix of the nucleotide‐binding domain, the elbow helix, and ICL1. We show here that the highly conserved ICL1 residues G462, Y463, and Y464 are essential for the proper cross talk of the closed nucleotide‐binding domain dimer with the transmembrane domains. Hence, ICL1 acts as a molecular spring, triggering the conformational switch of ABCG2 before substrate extrusion. These data suggest that the ABCG2 transmission interface may offer therapeutic options for the treatment of drug‐resistant malignancies.
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Affiliation(s)
- Narakorn Khunweeraphong
- Max Perutz Labs Vienna, Center for Medical Biochemistry, Campus Vienna Biocenter, Medical University of Vienna, Austria.,St. Anna Children's Cancer Research Institute-CCRI, Vienna, Austria
| | - Karl Kuchler
- Max Perutz Labs Vienna, Center for Medical Biochemistry, Campus Vienna Biocenter, Medical University of Vienna, Austria
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9
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Kroll T, Prescher M, Smits SHJ, Schmitt L. Structure and Function of Hepatobiliary ATP Binding Cassette Transporters. Chem Rev 2020; 121:5240-5288. [PMID: 33201677 DOI: 10.1021/acs.chemrev.0c00659] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The liver is beyond any doubt the most important metabolic organ of the human body. This function requires an intensive crosstalk within liver cellular structures, but also with other organs. Membrane transport proteins are therefore of upmost importance as they represent the sensors and mediators that shuttle signals from outside to the inside of liver cells and/or vice versa. In this review, we summarize the known literature of liver transport proteins with a clear emphasis on functional and structural information on ATP binding cassette (ABC) transporters, which are expressed in the human liver. These primary active membrane transporters form one of the largest families of membrane proteins. In the liver, they play an essential role in for example bile formation or xenobiotic export. Our review provides a state of the art and comprehensive summary of the current knowledge of hepatobiliary ABC transporters. Clearly, our knowledge has improved with a breath-taking speed over the last few years and will expand further. Thus, this review will provide the status quo and will lay the foundation for new and exciting avenues in liver membrane transporter research.
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Affiliation(s)
- Tim Kroll
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Martin Prescher
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Sander H J Smits
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.,Center for Structural Studies, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
| | - Lutz Schmitt
- Institute of Biochemistry, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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10
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Khunweeraphong N, Mitchell-White J, Szöllősi D, Hussein T, Kuchler K, Kerr ID, Stockner T, Lee JY. Picky ABCG5/G8 and promiscuous ABCG2 - a tale of fatty diets and drug toxicity. FEBS Lett 2020; 594:4035-4058. [PMID: 32978801 PMCID: PMC7756502 DOI: 10.1002/1873-3468.13938] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 09/03/2020] [Indexed: 12/20/2022]
Abstract
Structural data on ABCG5/G8 and ABCG2 reveal a unique molecular architecture for subfamily G ATP‐binding cassette (ABCG) transporters and disclose putative substrate‐binding sites. ABCG5/G8 and ABCG2 appear to use several unique structural motifs to execute transport, including the triple helical bundles, the membrane‐embedded polar relay, the re‐entry helices, and a hydrophobic valve. Interestingly, ABCG2 shows extreme substrate promiscuity, whereas ABCG5/G8 transports only sterol molecules. ABCG2 structures suggest a large internal cavity, serving as a binding region for substrates and inhibitors, while mutational and pharmacological analyses support the notion of multiple binding sites. By contrast, ABCG5/G8 shows a collapsed cavity of insufficient size to hold substrates. Indeed, mutational analyses indicate a sterol‐binding site at the hydrophobic interface between the transporter and the lipid bilayer. In this review, we highlight key differences and similarities between ABCG2 and ABCG5/G8 structures. We further discuss the relevance of distinct and shared structural features in the context of their physiological functions. Finally, we elaborate on how ABCG2 and ABCG5/G8 could pave the way for studies on other ABCG transporters.
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Affiliation(s)
- Narakorn Khunweeraphong
- Max Perutz Labs Vienna, Campus Vienna Biocenter, Center for Medical Biochemistry, Medical University of Vienna, Vienna, Austria.,CCRI-St. Anna Children's Cancer Research Institute, Vienna, Austria
| | - James Mitchell-White
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
| | - Dániel Szöllősi
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Toka Hussein
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Karl Kuchler
- Max Perutz Labs Vienna, Campus Vienna Biocenter, Center for Medical Biochemistry, Medical University of Vienna, Vienna, Austria
| | - Ian D Kerr
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
| | - Thomas Stockner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Jyh-Yeuan Lee
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
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11
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ABCG5/G8: a structural view to pathophysiology of the hepatobiliary cholesterol secretion. Biochem Soc Trans 2020; 47:1259-1268. [PMID: 31654053 PMCID: PMC6824678 DOI: 10.1042/bst20190130] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/26/2019] [Accepted: 09/30/2019] [Indexed: 12/17/2022]
Abstract
The ABCG5/G8 heterodimer is the primary neutral sterol transporter in hepatobiliary and transintestinal cholesterol excretion. Inactivating mutations on either the ABCG5 or ABCG8 subunit cause Sitosterolemia, a rare genetic disorder. In 2016, a crystal structure of human ABCG5/G8 in an apo state showed the first structural information on ATP-binding cassette (ABC) sterol transporters and revealed several structural features that were observed for the first time. Over the past decade, several missense variants of ABCG5/G8 have been associated with non-Sitosterolemia lipid phenotypes. In this review, we summarize recent pathophysiological and structural findings of ABCG5/G8, interpret the structure-function relationship in disease-causing variants and describe the available evidence that allows us to build a mechanistic view of ABCG5/G8-mediated sterol transport.
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12
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Wang HH, Liu M, Portincasa P, Wang DQH. Recent Advances in the Critical Role of the Sterol Efflux Transporters ABCG5/G8 in Health and Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1276:105-136. [PMID: 32705597 PMCID: PMC8118135 DOI: 10.1007/978-981-15-6082-8_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Cardiovascular disease is characterized by lipid accumulation, inflammatory response, cell death, and fibrosis in the arterial wall and is the leading cause of morbidity and mortality worldwide. Cholesterol gallstone disease is caused by complex genetic and environmental factors and is one of the most prevalent and costly digestive diseases in the USA and Europe. Although sitosterolemia is a rare inherited lipid storage disease, its genetic studies led to identification of the sterol efflux transporters ABCG5/G8 that are located on chromosome 2p21 in humans and chromosome 17 in mice. Human and animal studies have clearly demonstrated that ABCG5/G8 play a critical role in regulating hepatic secretion and intestinal absorption of cholesterol and plant sterols. Sitosterolemia is caused by a mutation in either the ABCG5 or the ABCG8 gene alone, but not in both simultaneously. Polymorphisms in the ABCG5/G8 genes are associated with abnormal plasma cholesterol metabolism and may play a key role in the genetic determination of plasma cholesterol concentrations. Moreover, ABCG5/G8 is a new gallstone gene, LITH9. Gallstone-associated variants in ABCG5/G8 are involved in the pathogenesis of cholesterol gallstones in European, Asian, and South American populations. In this chapter, we summarize the latest advances in the critical role of the sterol efflux transporters ABCG5/G8 in regulating hepatic secretion of biliary cholesterol, intestinal absorption of cholesterol and plant sterols, the classical reverse cholesterol transport, and the newly established transintestinal cholesterol excretion, as well as in the pathogenesis and pathophysiology of ABCG5/G8-related metabolic diseases such as sitosterolemia, cardiovascular disease, and cholesterol gallstone disease.
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Affiliation(s)
- Helen H Wang
- Department of Medicine and Genetics, Division of Gastroenterology and Liver Diseases, Marion Bessin Liver Research Center, Einstein-Mount Sinai Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Min Liu
- Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Piero Portincasa
- Department of Biomedical Sciences and Human Oncology, Clinica Medica "A. Murri", University of Bari Medical School, Bari, Italy
| | - David Q-H Wang
- Department of Medicine and Genetics, Division of Gastroenterology and Liver Diseases, Marion Bessin Liver Research Center, Einstein-Mount Sinai Diabetes Research Center, Albert Einstein College of Medicine, Bronx, NY, USA.
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13
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Bastida JM, Girós ML, Benito R, Janusz K, Hernández-Rivas JM, González-Porras JR. Sitosterolemia: Diagnosis, Metabolic and Hematological Abnormalities, Cardiovascular Disease and Management. Curr Med Chem 2019; 26:6766-6775. [DOI: 10.2174/0929867325666180705145900] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 03/27/2018] [Accepted: 03/27/2018] [Indexed: 12/30/2022]
Abstract
Sitosterolemia is a recessive inherited metabolic disorder of unknown prevalence,
characterized by increased levels of plasma plant sterols. It is caused by 28 and 31 variants in
ABCG5 and ABCG8 genes, respectively, and is characterized by a predisposition to hyperabsorption
and accumulation of toxic levels of plant sterols in plasma. Its clinical picture is extremely
heterogeneous. The main clinical features are tendinous and cutaneous xanthomas, arthritis
or arthralgia, premature cardiovascular disease and atherosclerosis. These characteristics
are shared with familial hypercholesterolemia (FH), making it possible for sitosterolemia to be
misdiagnosed as homozygous FH, especially in pediatric patients. In such cases, a specific
chromatography-based laboratory method is essential to differentiate sitosterol and cholesterol.
Hematological abnormalities (hemolytic anemia and macrothrombocytopenia) may be present in
25-35% of patients, in whom it is usually associated with the main clinical features, as occurs in
the 70% of the cases. In this context, the peripheral blood smear is essential and reveals giant
platelets and stomatocytes. Only 21 causative variants in ABCG5/ABCG8 are associated with
macrothrombocytopenia. Most physicians still do not recognize these hematological abnormalities
or relate them to sitosterolemia. Patients may suffer long-term misdiagnosis of immune
thrombocytopenia and be at high risk of receiving harmful therapies or of not benefitting from a
low-cholesterol diet and/or from the gold standard treatment with ezetimibe. This drug reduces
the levels of plasma plant sterols, provokes regression of xanthomas, and can alleviate hematological
abnormalities. Finally, to identify genetic defects, recent advances in high-throughput
sequencing, especially in the use of targeted sequencing of pre-specified genes, have begun to be
incorporated in the first-line approach in the field of genetic disorders.
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Affiliation(s)
- Jose María Bastida
- Department of Hematology, Hospital Universitario de Salamanca-IBSAL-USAL, Salamanca, Spain
| | - María Luisa Girós
- Seccio d'Errors Congenits del Metabolisme-IBC, Servei de Bioquimica i Genetica Molecular Hospital Clínic, IDIBAPS, CIBERER, Barcelona, Spain
| | - Rocío Benito
- IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Salamanca, Spain
| | - Kamila Janusz
- IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Salamanca, Spain
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14
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Genes Potentially Associated with Familial Hypercholesterolemia. Biomolecules 2019; 9:biom9120807. [PMID: 31795497 PMCID: PMC6995538 DOI: 10.3390/biom9120807] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/24/2019] [Accepted: 11/26/2019] [Indexed: 12/21/2022] Open
Abstract
This review addresses the contribution of some genes to the phenotype of familial hypercholesterolemia. At present, it is known that the pathogenesis of this disease involves not only a pathological variant of low-density lipoprotein receptor and its ligands (apolipoprotein B, proprotein convertase subtilisin/kexin type 9 or low-density lipoprotein receptor adaptor protein 1), but also lipids, including sphingolipids, fatty acids, and sterols. The genetic cause of familial hypercholesterolemia is unknown in 20%–40% of the cases. The genes STAP1 (signal transducing adaptor family member 1), CYP7A1 (cytochrome P450 family 7 subfamily A member 1), LIPA (lipase A, lysosomal acid type), ABCG5 (ATP binding cassette subfamily G member 5), ABCG8 (ATP binding cassette subfamily G member 8), and PNPLA5 (patatin like phospholipase domain containing 5), which can cause aberrations of lipid metabolism, are being evaluated as new targets for the diagnosis and personalized management of familial hypercholesterolemia.
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15
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Veit L, Allegri Machado G, Bürer C, Speer O, Häberle J. Sitosterolemia-10 years observation in two sisters. JIMD Rep 2019; 48:4-10. [PMID: 31392106 PMCID: PMC6607017 DOI: 10.1002/jmd2.12038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 04/18/2019] [Accepted: 04/24/2019] [Indexed: 12/26/2022] Open
Abstract
Familial hypercholesterolemia due to heterozygous low-density lipoprotein-receptor mutations is a common inborn errors of metabolism. Secondary hypercholesterolemia due to a defect in phytosterol metabolism is far less common and may escape diagnosis during the work-up of patients with dyslipidemias. Here we report on two sisters with the rare, autosomal recessive condition, sitosterolemia. This disease is caused by mutations in a defective adenosine triphosphate-binding cassette sterol excretion transporter, leading to highly elevated plant sterol concentrations in tissues and to a wide range of symptoms. After a delayed diagnosis, treatment with a diet low in plant lipids plus ezetimibe to block the absorption of sterols corrected most of the clinical and biochemical signs of the disease. We followed the two patients for over 10 years and report their initial presentation and long-term response to treatment.
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Affiliation(s)
- Lara Veit
- Division of Metabolism and Children's Research CenterUniversity Children's Hospital ZurichZurichSwitzerland
| | - Gabriella Allegri Machado
- Division of Metabolism and Children's Research CenterUniversity Children's Hospital ZurichZurichSwitzerland
| | - Céline Bürer
- Division of Metabolism and Children's Research CenterUniversity Children's Hospital ZurichZurichSwitzerland
| | - Oliver Speer
- Division of Haematology and Children's Research CenterUniversity Children's Hospital ZurichZurichSwitzerland
- Institut für LabormedizinSpital Thurgau AGFrauenfeldSwitzerland
| | - Johannes Häberle
- Division of Metabolism and Children's Research CenterUniversity Children's Hospital ZurichZurichSwitzerland
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16
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17
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Clinical features, molecular characteristics, and treatments of a Chinese girl with sitosterolemia: A case report and literature review. J Clin Lipidol 2019; 13:246-250. [DOI: 10.1016/j.jacl.2019.01.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 01/14/2019] [Accepted: 01/16/2019] [Indexed: 11/22/2022]
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18
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Plat J, Baumgartner S, Vanmierlo T, Lütjohann D, Calkins KL, Burrin DG, Guthrie G, Thijs C, Te Velde AA, Vreugdenhil ACE, Sverdlov R, Garssen J, Wouters K, Trautwein EA, Wolfs TG, van Gorp C, Mulder MT, Riksen NP, Groen AK, Mensink RP. Plant-based sterols and stanols in health & disease: "Consequences of human development in a plant-based environment?". Prog Lipid Res 2019; 74:87-102. [PMID: 30822462 DOI: 10.1016/j.plipres.2019.02.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Revised: 02/13/2019] [Accepted: 02/25/2019] [Indexed: 01/27/2023]
Abstract
Dietary plant sterols and stanols as present in our diet and in functional foods are well-known for their inhibitory effects on intestinal cholesterol absorption, which translates into lower low-density lipoprotein cholesterol concentrations. However, emerging evidence suggests that plant sterols and stanols have numerous additional health effects, which are largely unnoticed in the current scientific literature. Therefore, in this review we pose the intriguing question "What would have occurred if plant sterols and stanols had been discovered and embraced by disciplines such as immunology, hepatology, pulmonology or gastroenterology before being positioned as cholesterol-lowering molecules?" What would then have been the main benefits and fields of application of plant sterols and stanols today? We here discuss potential effects ranging from its presence and function intrauterine and in breast milk towards a potential role in the development of non-alcoholic steatohepatitis (NASH), cardiovascular disease (CVD), inflammatory bowel diseases (IBD) and allergic asthma. Interestingly, effects clearly depend on the route of entrance as observed in intestinal-failure associated liver disease (IFALD) during parenteral nutrition regimens. It is only until recently that effects beyond lowering of cholesterol concentrations are being explored systematically. Thus, there is a clear need to understand the full health effects of plant sterols and stanols.
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Affiliation(s)
- J Plat
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands.
| | - S Baumgartner
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands
| | - T Vanmierlo
- Department of Immunology and Biochemistry, Biomedical Research Institute (Biomed) Hasselt University, Hasselt, Belgium; Division of Translational Neuroscience, Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Maastricht University, the Netherlands
| | - D Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University of Bonn, Bonn, Germany
| | - K L Calkins
- David Geffen School of Medicine, University of California Los Angeles, Mattel Children's Hospital at UCLA, Los Angeles, CA; Department of Pediatrics, Division of Neonatology and Developmental Biology, Neonatal Research Center, USA
| | - D G Burrin
- Department of Pediatrics, USDA Children's Nutrition Research Center, Baylor College of Medicine, Houston, USA
| | - G Guthrie
- Department of Pediatrics, USDA Children's Nutrition Research Center, Baylor College of Medicine, Houston, USA
| | - C Thijs
- Department of Epidemiology, Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, the Netherlands
| | - A A Te Velde
- Tytgat Institute for Liver and Intestinal Research, Amsterdam Medical Center, the Netherlands
| | - A C E Vreugdenhil
- Department of Pediatrics, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands
| | - R Sverdlov
- Department of Molecular Genetics, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands
| | - J Garssen
- Utrecht University, Division Pharmacology, Utrecht Institute for Pharmaceutical Sciences, the Netherlands
| | - K Wouters
- Department of Internal Medicine, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, Maastricht, the Netherlands
| | | | - T G Wolfs
- Department of Pediatrics, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands
| | - C van Gorp
- Department of Pediatrics, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands
| | - M T Mulder
- Department of Internal Medicine, Rotterdam University, Rotterdam, the Netherlands
| | - N P Riksen
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, the Netherlands
| | - A K Groen
- Amsterdam Diabetes Center and Department of Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - R P Mensink
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, Maastricht, the Netherlands
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19
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Wadsack D, Sattler H, Kleber ME, Eirich K, Scharnagl H, Fauler G, März W, Grammer TB. Recurrent tendosynovitis as a rare manifestation of a lipid disorder. J Clin Lipidol 2018; 13:54-61. [PMID: 30459115 DOI: 10.1016/j.jacl.2018.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 10/28/2022]
Abstract
A 33-year-old female had suffered from spontaneously recurrent bursitis and tendosynovitis/enthesitis of the patellar and Achilles tendons for about 10 years. The episodes of immobilization increased. Ultrasound imaging of the swollen and painful tendons showed chronic inflammation with neoangiogenesis within the tendons and hypoechoic lesions. Clinical and laboratory tests did not provide evidence for a rheumatic disease. Low density lipoprotein cholesterol was elevated. Biopsies of skin lesions did not confirm the suspicion of cutaneous xanthomas. Genetic testing for familial hypercholesterolemia was negative. Campesterol and sitosterol were elevated 7- to 12-fold and 20- to 38-fold over the upper limit of normal on two occasions. There was no relevant mutation in ABCG5. In ABCG8, we identified a missense mutation c.1267G>A in exon 9 changing glutamic acid 423 into lysine within the transmembrane domain, and an insertion of adenine (c.1487insA) leading to a frameshift and a premature stop codon (Ile497Aspfs*105). The patient had no clinical evidence of premature atherosclerosis. Therapeutic approaches with nonsteroidal antirheumatic drugs, prednisone, statins, and ezetimibe accompanied by a diet poor in plant sterols led to a relief of symptoms. This case report shows that tendon xanthoma along with tendosynovitis, especially on extensor areas, is suspicious for hypercholesterolemia as the underlying cause. The absence of atherosclerotic plaques in the abdominal aorta and in the carotid arteries on ultrasound may suggest that phytosterolemia is not necessarily accompanied by premature vascular disease.
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Affiliation(s)
- Daniel Wadsack
- Department of Medicine A, Klinikum Ludwigshafen, Ludwigshafen, Germany
| | - Horst Sattler
- Department of Medicine A, Klinikum Ludwigshafen, Ludwigshafen, Germany
| | - Marcus E Kleber
- Department of Internal Medicine V (Nephrology, Rheumatology, Hypertensiology, Endocrinolgy, Diabetology), Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany
| | | | - Hubert Scharnagl
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Günter Fauler
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Winfried März
- Department of Internal Medicine V (Nephrology, Rheumatology, Hypertensiology, Endocrinolgy, Diabetology), Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany; Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria; Synlab Academy, Synlab Holding Deutschland GmbH, Mannheim, Germany
| | - Tanja B Grammer
- Department of Internal Medicine V (Nephrology, Rheumatology, Hypertensiology, Endocrinolgy, Diabetology), Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany; Mannheim Institute of Public Health, Social and Preventive Medicine, Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany.
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20
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Patel SB, Graf GA, Temel RE. ABCG5 and ABCG8: more than a defense against xenosterols. J Lipid Res 2018; 59:1103-1113. [PMID: 29728459 DOI: 10.1194/jlr.r084244] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/17/2018] [Indexed: 12/14/2022] Open
Abstract
The elucidation of the molecular basis of the rare disease, sitosterolemia, has revolutionized our mechanistic understanding of how dietary sterols are excreted and how cholesterol is eliminated from the body. Two proteins, ABCG5 and ABCG8, encoded by the sitosterolemia locus, work as obligate dimers to pump sterols out of hepatocytes and enterocytes. ABCG5/ABCG8 are key in regulating whole-body sterol trafficking, by eliminating sterols via the biliary tree as well as the intestinal tract. Importantly, these transporters keep xenosterols from accumulating in the body. The sitosterolemia locus has been genetically associated with lipid levels and downstream atherosclerotic disease, as well as formation of gallstones and the risk of gallbladder cancer. While polymorphic variants raise or lower the risks of these phenotypes, loss of function of this locus leads to more dramatic phenotypes, such as premature atherosclerosis, platelet dysfunction, and thrombocytopenia, and, perhaps, increased endocrine disruption and liver dysfunction. Whether small amounts of xenosterol exposure over a lifetime cause pathology in normal humans with polymorphic variants at the sitosterolemia locus remains largely unexplored. The purpose of this review will be to summarize the current state of knowledge, but also highlight key conceptual and mechanistic issues that remain to be explored.
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Affiliation(s)
- Shailendra B Patel
- Division of Endocrinology, Diabetes, and Metabolism, University of Cincinnati, Cincinnati, OH 45219
| | - Gregory A Graf
- Department of Pharmaceutical Sciences and Saha Cardiovascular Research Center and University of Kentucky, Lexington, KY 40536
| | - Ryan E Temel
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536
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21
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Bazerbachi F, Conboy EE, Mounajjed T, Watt KD, Babovic-Vuksanovic D, Patel SB, Kamath PS. Cryptogenic Cirrhosis and Sitosterolemia: A Treatable Disease If Identified but Fatal If Missed. Ann Hepatol 2017; 16:970-978. [PMID: 29055934 DOI: 10.5604/01.3001.0010.5290] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Sitosterolemia is an autosomal recessive metabolic disease caused by mutations in ABCG5 or ABCG8 genes which encode for the (ATP)-binding cassette (ABC) transporters that are responsible for the trafficking of xenosterols. Liver involvement is not a recognized manifestation of this disease, and cirrhosis has been reported only once in the medical literature. We describe a fatal case of a 21-year old South Asian male who presented with decompensated cirrhosis, and biochemical abnormalities consistent with sitosterolemia. Genetic testing showed a homozygous pathogenic mutation in ABCG5, confirming the diagnosis. Sitosterolemia is a rare, but likely under-recognized condition, and a high degree of suspicion is imperative to make the diagnosis. We propose that sitosterolemia should be included in the differential diagnosis for patients with cryptogenic cirrhosis, especially as there are effective oral therapies to treat this condition. Newly diagnosed sitosterolemia patients should undergo a thorough hepatology evaluation and follow-up to evaluate for the presence, development, and progression of any hepatic involvement.
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Affiliation(s)
- Fateh Bazerbachi
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | - Erin E Conboy
- Department of Clinical Genomics, Mayo Clinic, Rochester, MN
| | | | - Kymberly D Watt
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
| | | | - Shailendra B Patel
- Division of Endocrinology, Diabetes, and Metabolism, University of Cincinnati, OH
| | - Patrick S Kamath
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN
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22
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Köhler J, Teupser D, Elsässer A, Weingärtner O. Plant sterol enriched functional food and atherosclerosis. Br J Pharmacol 2017; 174:1281-1289. [PMID: 28253422 PMCID: PMC5429322 DOI: 10.1111/bph.13764] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 02/09/2017] [Accepted: 02/15/2017] [Indexed: 12/25/2022] Open
Abstract
Hypercholesterolaemia is a major cardiovascular risk factor. A healthy diet and a healthy lifestyle reduces cardiovascular risk. 'Functional foods' supplemented with phytosterols are recommended for the management of hypercholesterolaemia and have become a widely used non-prescription approach to lower plasma cholesterol levels. Two billion euros are spent world-wide each year on various functional foods, which have regulator-approved health claims for the management of elevated cholesterol levels. While international societies, such as the European Atherosclerosis Society or the National Heart Foundation in Australia, still advise phytosterols as an additional dietary option in the management of hypercholesterolaemia, recently released guidelines such as those from the National Institute of Health and Clinical Excellence in the United Kingdom are more critical of food supplementation with phytosterols and draw attention to significant safety issues. This review challenges whether an intervention with phytosterol supplements is beneficial. We summarize the current evidence from genetic diseases, genetic association studies, clinical trial data and data from animal studies. LINKED ARTICLES This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.
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Affiliation(s)
- Jürgen Köhler
- Clinic for Thorax‐, Vascular and Endovascular Surgery, Pius‐Hospital OldenburgCarl von Ossietzky UniversitätOldenburgGermany
| | - Daniel Teupser
- Institute of Laboratory MedicineLudwig‐Maximilians‐University MunichMunichGermany
| | - Albrecht Elsässer
- Department of Cardiology, Klinikum Oldenburg, European Medical School Oldenburg‐GroningenCarl von Ossietzky UniversityOldenburgGermany
| | - Oliver Weingärtner
- Department of Cardiology, Klinikum Oldenburg, European Medical School Oldenburg‐GroningenCarl von Ossietzky UniversityOldenburgGermany
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Nghiem-Rao TH, Patel SB. Investigating Sitosterolemia to Understand Lipid Physiology. ACTA ACUST UNITED AC 2017; 8:649-658. [PMID: 29928317 DOI: 10.2217/clp.13.60] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The cholesterol molecule is at the center of the pathophysiology of many vascular diseases. Whole-body cholesterol pools are maintained by a balance of endogenous synthesis, dietary absorption and elimination from our bodies. While the cellular aspects of cholesterol metabolism received significant impetus from the seminal work of Goldstein and Brown investigating LDL receptor trafficking, how dietary cholesterol was absorbed and eliminated was relatively neglected. The identification of the molecular defect a rare human disorder, Sitosterolemia, led to elucidation of a key mechanism of how we regulate the excretory pathway in the liver and in the intestine. Two proteins, ABCG5 and ABCG8, constitute a heterodimeric transporter that facilitates the extrusion of sterols from the cell into the biliary lumen, with a preference for xenosterols. This mechanism explained how dietary xenosterols are prevented from accumulating in our bodies. In addition, this disease has also highlighted the potential harm of xenosterols; macrothrombocytopenia, liver disease and endocrine disruption are seen when xenosterols accumulate. Mouse models of this disease suggest that there are more dramatic alterations of physiology, suggesting that these highly conserved mechanisms have evolved to prevent these xenosterols from accumulating in our bodies.
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Affiliation(s)
| | - Shailendra B Patel
- Medical College of Wisconsin, and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI
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Wang HH, Li X, Patel SB, Wang DQH. Evidence that the adenosine triphosphate-binding cassette G5/G8-independent pathway plays a determinant role in cholesterol gallstone formation in mice. Hepatology 2016; 64:853-64. [PMID: 27014967 PMCID: PMC6037420 DOI: 10.1002/hep.28570] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 03/19/2016] [Indexed: 12/18/2022]
Abstract
UNLABELLED The adenosine triphosphate-binding cassette (ABC) sterol transporter, Abcg5/g8, is Lith9 in mice, and two gallstone-associated variants in ABCG5/G8 have been identified in humans. Although ABCG5/G8 plays a critical role in determining hepatic sterol secretion, cholesterol is still secreted to bile in sitosterolemic patients with a defect in either ABCG5 or ABCG8 and in either Abcg5/g8 double- or single-knockout mice. We hypothesize that in the defect of ABCG5/G8, an ABCG5/G8-independent pathway is essential for regulating hepatic secretion of biliary sterols, which is independent of the lithogenic mechanism of the ABCG5/G8 pathway. To elucidate the effect of the ABCG5/G8-independent pathway on cholelithogenesis, we investigated the biliary and gallstone characteristics in male wild-type (WT), ABCG5(-/-)/G8(-/-), and ABCG8 (-/-) mice fed a lithogenic diet or varying amounts of cholesterol, treated with a liver X receptor (LXR) agonist, or injected intravenously with [(3) H]sitostanol- and [(14) C]cholesterol-labeled high-density lipoprotein (HDL). We found that ABCG5(-/-)/G8(-/-) and ABCG8 (-/-) mice displayed the same biliary and gallstone phenotypes. Although both groups of knockout mice showed a significant reduction in hepatic cholesterol output compared to WT mice, they still formed gallstones. The LXR agonist significantly increased biliary cholesterol secretion and gallstones in WT, but not ABCG5(-/-)/G8(-/-) or ABCG8 (-/-), mice. The 6-hour recovery of [(14) C]cholesterol in hepatic bile was significantly lower in both groups of knockout mice than in WT mice and [(3) H]sitostanol was detected in WT, but not ABCG5(-/-)/G8(-/-) or ABCG8 (-/-), mice. CONCLUSIONS The ABCG5/G8-independent pathway plays an important role in regulating biliary cholesterol secretion, the transport of HDL-derived cholesterol from plasma to bile, and gallstone formation, which works independently of the ABCG5/G8 pathway. Further studies are needed to observe whether this pathway is also operational in humans. (Hepatology 2016;64:853-864).
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Affiliation(s)
- Helen H. Wang
- Department of Medicine, Liver Center and Gastroenterology Division, Beth Israel Deaconess Medical Center, Harvard Medical School and Harvard Digestive Diseases Center, Boston, MA,Department of Internal Medicine, Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, MO
| | - Xiaodan Li
- Department of Internal Medicine, Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, MO
| | - Shailendra B. Patel
- Division of Endocrinology, Metabolism and Clinical Nutrition, Medical College of Wisconsin, Milwaukee, WI
| | - David Q.-H. Wang
- Department of Medicine, Liver Center and Gastroenterology Division, Beth Israel Deaconess Medical Center, Harvard Medical School and Harvard Digestive Diseases Center, Boston, MA,Department of Internal Medicine, Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, MO,Correspondence to David Q.-H. Wang, M.D., Ph.D., at his present address: Department of Internal Medicine, Division of Gastroenterology and Hepatology, Saint Louis University School of Medicine, St. Louis, MO 63104, USA. Phone: (314) 977-8737, Fax: (314) 977-9909,
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25
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Ali S, Shetty S, Ghosh K. Bengal macrothrombocytopenia is not totally an innocuous condition. Blood Cells Mol Dis 2016; 60:3-6. [PMID: 27519935 DOI: 10.1016/j.bcmd.2016.05.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 05/26/2016] [Accepted: 05/26/2016] [Indexed: 11/25/2022]
Abstract
Inherited macrothrombocytopenia is a subgroup of thrombocytopenias, and is characterised by the presence of giant platelets and decreased platelet count with variable bleeding manifestations. Bengal macrothrombocytopenia is a newly described entity, previously called asymptomatic constitutional macrothrombocytopenia (ACMT), presented with variable bleeding tendencies; with mild to severe thrombocytopenia and macro-platelets in their peripheral blood smear and it is not totally an innocuous condition as described previously.
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Affiliation(s)
- Shahnaz Ali
- National Institute of Immunohaematology (ICMR), 13th Floor, KEM Hospital, Parel, Mumbai 400 012, India.
| | - Shrimati Shetty
- National Institute of Immunohaematology (ICMR), 13th Floor, KEM Hospital, Parel, Mumbai 400 012, India
| | - Kanjaksha Ghosh
- National Institute of Immunohaematology (ICMR), 13th Floor, KEM Hospital, Parel, Mumbai 400 012, India
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26
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Differential expression of genes involved in Bengal macrothrombocytopenia (BMTCP). Blood Cells Mol Dis 2015; 55:410-4. [DOI: 10.1016/j.bcmd.2015.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/18/2015] [Accepted: 09/18/2015] [Indexed: 11/21/2022]
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Baccini V, Alessi MC. [Diagnosis of inherited thrombocytopenia]. Rev Med Interne 2015; 37:117-26. [PMID: 26617290 DOI: 10.1016/j.revmed.2015.10.346] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 10/19/2015] [Indexed: 12/19/2022]
Abstract
Inherited thrombocytopenias are rare, heterogenous and probably under-diagnosed because often classified as autoimmune thrombocytopenia. About 20 genes were described responsible for these thrombocytopenias. Precise diagnosis is necessary because the prognosis is different and some of them can evolve into hemopathies. First of all, it is important to gather a body of evidence to orientate towards an inherited cause: presence of the thrombocytopenia since childhood and of other family cases is a strong argument. Secondly, it is difficult to target the genetic investigations that settle the precise diagnosis. Genetic variants responsible for inherited thrombocytopenias affect different stage during megakaryocytopoiesis and cause thrombocytopenias with distinct characteristics. Presence of extra-hematological features, platelets' size measurement and evaluation of bone marrow megakaryocyte morphology when it is possible allow a primary orientation. We propose a diagnostic approach considering extra-hematological features, mode of inheritance, morphology, molecular and functional platelets' studies and bone marrow megakaryocyte morphology in order to better target genetic study. Nevertheless, despite this approach, some inherited thrombocytopenias remain still unexplained and could benefit from new methods of new generation sequencing in the future.
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Affiliation(s)
- V Baccini
- Laboratoire d'hématologie, hôpital Nord, CHU de Marseille, chemin des Bourrelly, 13015 Marseille, France; Centre de référence des pathologies plaquettaires (CRPP), CHU Timone, 264, rue Saint-Pierre, 13385 Marseille cedex 5, France.
| | - M C Alessi
- Laboratoire d'hématologie, hôpital Nord, CHU de Marseille, chemin des Bourrelly, 13015 Marseille, France; Centre de référence des pathologies plaquettaires (CRPP), CHU Timone, 264, rue Saint-Pierre, 13385 Marseille cedex 5, France
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Kinetics of phytosterol metabolism in neonates receiving parenteral nutrition. Pediatr Res 2015; 78:181-9. [PMID: 25897540 PMCID: PMC4546827 DOI: 10.1038/pr.2015.78] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 01/21/2015] [Indexed: 01/14/2023]
Abstract
BACKGROUND Phytosterols in soybean oil (SO) lipids likely contribute to parenteral nutrition-associated liver disease (PNALD) in infants. No characterization of phytosterol metabolism has been done in infants receiving SO lipids. METHODS In a prospective cohort study, 45 neonates (36 SO lipid vs. 9 control) underwent serial blood sample measurements of sitosterol, campesterol, and stigmasterol. Mathematical modeling was used to determine pharmacokinetic parameters of phytosterol metabolism and phytosterol exposure. RESULTS Compared to controls, SO lipid-exposed infants had significantly higher levels of sitosterol and campesterol (P < 0.01). During SO lipid infusion, sitosterol and campesterol reached half of steady-state plasma levels within 1.5 and 0.8 d, respectively. Steady-state level was highest for sitosterol (1.68 mg/dl), followed by campesterol (0.98 mg/dl), and lowest for stigmasterol (0.01 mg/dl). Infants born < 28 wk gestational age had higher sitosterol steady-state levels (P = 0.03) and higher area under the curve for sitosterol (P = 0.03) during the first 5 d of SO lipid (AUC5) than infants born ≥ 28 wk gestational age. CONCLUSION Phytosterols in SO lipid accumulate rapidly in neonates. Very preterm infants receiving SO lipid have higher sitosterol exposure, and may have poorly developed mechanisms of eliminating phytosterols that may contribute to their vulnerability to PNALD.
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Favier R, Raslova H. Progress in understanding the diagnosis and molecular genetics of macrothrombocytopenias. Br J Haematol 2015; 170:626-39. [DOI: 10.1111/bjh.13478] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Remi Favier
- Institut National de la Santé et de la Recherche Médicale; U1170; Equipe Labellisée Ligue Contre le Cancer; Villejuif France
- Assistance Publique-Hôpitaux de Paris; Armand Trousseau Children Hospital; French Reference Center for Platelet Disorders; Haematological Laboratory; Paris France
| | - Hana Raslova
- Institut National de la Santé et de la Recherche Médicale; U1170; Equipe Labellisée Ligue Contre le Cancer; Villejuif France
- Faculté de Médecine; University Paris Saclay and University Paris-Sud 11; Le Kremlin-Bicêtre France
- Gustave Roussy; Villejuif France
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Abstract
Phytosterolemia (sitosterolemia) is a rare autosomal recessive sterol storage disease caused by mutations in either of the adenosine triphosphate (ATP) binding cassette transporter genes; (ABC) G5 or ABCG8, leading to impaired elimination of plant sterols and stanols, with their increased accumulation in the blood and tissues. Thus the disease is characterized by substantially elevated serum plant sterols and stanols, with moderate to high plasma cholesterol levels, and increased risk of premature atherosclerosis. Hematologic abnormalities including macrothrombocytopenia, stomatocytosis and hemolysis are frequently observed in sitosterolemia patients. Currently, ezetimibe, a sterol absorption inhibitor, is used as the routine treatment for sitosterolemia, with reported improvement in plant sterol levels and hemolytic parameters. This review summarizes the research related to the health impact of plant sterols and stanols on sitosterolemia.
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Affiliation(s)
- Bridget O. Ajagbe
- University of Manitoba, Department of Human Nutritional Sciences, Winnipeg, MB, Canada, R3T 2N2, and University of Manitoba, Richardson Centre for Functional Foods and Nutraceuticals, Winnipeg, MB, Canada, R3T 6C5
| | - Rgia A. Othman
- University of Manitoba, Department of Human Nutritional Sciences, Winnipeg, MB, Canada, R3T 2N2, and University of Manitoba, Richardson Centre for Functional Foods and Nutraceuticals, Winnipeg, MB, Canada, R3T 6C5
| | - Semone B. Myrie
- University of Manitoba, Department of Human Nutritional Sciences, Winnipeg, MB, Canada, R3T 2N2, and University of Manitoba, Richardson Centre for Functional Foods and Nutraceuticals, Winnipeg, MB, Canada, R3T 6C5
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31
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Nie S, Chen G, Cao X, Zhang Y. Cerebrotendinous xanthomatosis: a comprehensive review of pathogenesis, clinical manifestations, diagnosis, and management. Orphanet J Rare Dis 2014; 9:179. [PMID: 25424010 PMCID: PMC4264335 DOI: 10.1186/s13023-014-0179-4] [Citation(s) in RCA: 190] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 11/04/2014] [Indexed: 12/20/2022] Open
Abstract
Cerebrotendinous xanthomatosis (CTX) OMIM#213700 is a rare autosomal-recessive lipid storage disease caused by mutations in the CYP27A1 gene; this gene codes for the mitochondrial enzyme sterol 27-hydroxylase, which is involved in bile acid synthesis. The CYP27A1 gene is located on chromosome 2q33-qter and contains nine exons. A CYP27A1 mutation leads to decreased synthesis of bile acid, excess production of cholestanol, and consequent accumulation of cholestanol in tissues. Currently there is no consensus on the prevalence of CTX, one estimate being <5/100,000 worldwide. The prevalence of CTX due to the CYP27A1 mutation R362C alone is approximately 1/50,000 in Caucasians. Patients with CTX have an average age of 35 years at the time of diagnosis and a diagnostic delay of 16 years. Clinical signs and symptoms include adult-onset progressive neurological dysfunction (i.e., ataxia, dystonia, dementia, epilepsy, psychiatric disorders,peripheral neuropathy, and myopathy) and premature non-neurologic manifestations (i.e., tendon xanthomas, childhood-onset cataracts, infantile-onset diarrhea, premature atherosclerosis, osteoporosis, and respiratory insufficiency). Juvenile cataracts, progressive neurologic dysfunction, and mild pulmonary insufficiency are unique symptoms that distinguish CTX from other lipid storage disorders including familial dysbetalipoproteinemia, homozygous familial hypercholesterolemia, and sitosterolemia, all of which might also present with xanthomas and cardiovascular diseases. Brain magnetic resonance imaging (MRI) shows bilateral lesions in the dentate nucleus of the cerebellum and mild white matter lesions. The classical symptoms and signs, namely elevated levels of cholestanol and bile alcohols in serum and urine, brain MRI, and the mutation in the CYP27A1 gene confirm the diagnosis of CTX. Early diagnosis and long-term treatment with chenodeoxycholic acid (750 mg/d) improve neurological symptoms and contribute to a better prognosis.
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Affiliation(s)
- Shuke Nie
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, China.
| | - Guiqin Chen
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, China.
| | - Xuebing Cao
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, China.
| | - Yunjian Zhang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, 430022, China.
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Uehara Y, Saku K. High-density lipoprotein and atherosclerosis: Roles of lipid transporters. World J Cardiol 2014; 6:1049-1059. [PMID: 25349649 PMCID: PMC4209431 DOI: 10.4330/wjc.v6.i10.1049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 02/10/2014] [Accepted: 08/31/2014] [Indexed: 02/06/2023] Open
Abstract
Various previous studies have found a negative correlation between the risk of cardiovascular events and serum high-density lipoprotein (HDL) cholesterol levels. The reverse cholesterol transport, a pathway of cholesterol from peripheral tissue to liver which has several potent antiatherogenic properties. For instance, the particles of HDL mediate to transport cholesterol from cells in arterial tissues, particularly from atherosclerotic plaques, to the liver. Both ATP-binding cassette transporters (ABC) A1 and ABCG1 are membrane cholesterol transporters and have been implicated in mediating cholesterol effluxes from cells in the presence of HDL and apolipoprotein A-I, a major protein constituent of HDL. Previous studies demonstrated that ABCA1 and ABCG1 or the interaction between ABCA1 and ABCG1 exerted antiatherosclerotic effects. As a therapeutic approach for increasing HDL cholesterol levels, much focus has been placed on increasing HDL cholesterol levels as well as enhancing HDL biochemical functions. HDL therapies that use injections of reconstituted HDL, apoA-I mimetics, or full-length apoA-I have shown dramatic effectiveness. In particular, a novel apoA-I mimetic peptide, Fukuoka University ApoA-I Mimetic Peptide, effectively removes cholesterol via specific ABCA1 and other transporters, such as ABCG1, and has an antiatherosclerotic effect by enhancing the biological functions of HDL without changing circulating HDL cholesterol levels. Thus, HDL-targeting therapy has significant atheroprotective potential, as it uses lipid transporter-targeting agents, and may prove to be a therapeutic tool for atherosclerotic cardiovascular diseases.
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33
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[Sitosterolemia in a 2 year-old child with xanthomas and hematological anomalies]. An Pediatr (Barc) 2014; 82:209-10. [PMID: 25074708 DOI: 10.1016/j.anpedi.2014.06.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 06/16/2014] [Accepted: 06/18/2014] [Indexed: 10/25/2022] Open
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Ruiz XD, Levesque MC, Modi SR, Mock GD, Liang KP. 20-year-old amish woman with abdominal pain, retroperitoneal mass, and hyperlipidemia. Arthritis Care Res (Hoboken) 2014; 67:447-51. [PMID: 25073796 DOI: 10.1002/acr.22425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 07/22/2014] [Indexed: 11/08/2022]
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Abstract
PURPOSE OF REVIEW To provide an update on recent advances made in our mechanistic and pathophysiological understanding of the rare human disease Sitosterolemia, the role of ABCG5/ABCG8 in sterol trafficking and how newer data implicate a more wider role in the body. RECENT FINDINGS Sitosterolemia is caused by a genetic defect of sterolins (ABCG5/ABCG8) mapped to the STSL locus. Polymorphic variations in STSL have been linked to lipid levels and gallstone disease in whites. Newer studies now link this locus to a more diverse ethnic group for gallstone disease, susceptibility to biliary cancer, and show variants that alter sterolin function. Intriguingly, carriers of a mutant allele seem to show protection against carotid wall disease. Although the 'promoter' region of the STSL is minimal, regulatory regions responsive to liver X receptor have remained elusive, but no longer; two intronic regions in ABCG8 have now been identified. Xenosterol accumulation leads to loss of abdominal fat, infertility, and premature death. Xenosterol accumulation in mouse platelet membranes leads to platelet hyperactivation, increased microparticle formation, and reduced αIIbβ3 surface expression. In humans, phytosterols may promote liver injury in parenteral nutrition-associated liver disease. SUMMARY Progress in understanding sterolin function is beginning to show that xenosterols can be toxic and are involved on pathogenesis, and the role of ABCG5/ABCG8 may extend into other metabolic processes by altering intracellular sterol metabolism.
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Affiliation(s)
- Shailendra B Patel
- aClement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA bDivision of Endocrinology, Metabolism and Clinical Nutrition, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Tachibana S, Hirano M, Hirata T, Matsuo M, Ikeda I, Ueda K, Sato R. Cholesterol and Plant Sterol Efflux from Cultured Intestinal Epithelial Cells Is Mediated by ATP-Binding Cassette Transporters. Biosci Biotechnol Biochem 2014; 71:1886-95. [PMID: 17690481 DOI: 10.1271/bbb.70109] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In this study we analyzed functions of ATP-binding cassette (ABC) transporters involved in sterol transport from Caco-2 cells. Treatment with a synthetic liver x receptor ligand elevated both mRNA and protein levels of ABCG5, G8, and ABCA1. The ligand stimulated cholesterol efflux, suggesting that ABC transporters are involved in it. To identify the acceptors of cholesterol, potential molecules such as apolipoprotein A-I, glycocholic acid, phosphatidylcholine, and bile acid micelles were added to the medium. Apo A-I, a known acceptor of cholesterol transported by ABCA1, elevated cholesterol efflux on the basal side, whereas the others raised cholesterol efflux on the apical side. Moreover, bile acid micelles preferentially augmented plant sterol efflux rather than cholesterol. Finally, in HEK293 cells stably expressing ABCG5/G8, bile acid micelle-mediated sterol efflux was significantly accelerated. These results indicate that ABCG5/G8, unlike ABCA1, together with bile acids should participate in sterol efflux on the apical surface of Caco-2 cells.
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Affiliation(s)
- Shizuko Tachibana
- Department of Applied Biological Chemistry, Graduate School of Agriculture and Life Sciences, University of Tokyo, Tokyo, Japan
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Escolà-Gil JC, Quesada H, Julve J, Martín-Campos JM, Cedó L, Blanco-Vaca F. Sitosterolemia: Diagnosis, Investigation, and Management. Curr Atheroscler Rep 2014; 16:424. [DOI: 10.1007/s11883-014-0424-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Bakay M, Pandey R, Hakonarson H. Genes involved in type 1 diabetes: an update. Genes (Basel) 2013; 4:499-521. [PMID: 24705215 PMCID: PMC3924830 DOI: 10.3390/genes4030499] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 08/26/2013] [Accepted: 09/05/2013] [Indexed: 01/06/2023] Open
Abstract
Type 1 Diabetes (T1D) is a chronic multifactorial disease with a strong genetic component, which, through interactions with specific environmental factors, triggers disease onset. T1D typically manifests in early to mid childhood through the autoimmune destruction of pancreatic β cells resulting in a lack of insulin production. Historically, prior to genome-wide association studies (GWAS), six loci in the genome were fully established to be associated with T1D. With the advent of high-throughput single nucleotide polymorphism (SNP) genotyping array technologies, enabling investigators to perform high-density GWAS, many additional T1D susceptibility genes have been discovered. Indeed, recent meta-analyses of multiple datasets from independent investigators have brought the tally of well-validated T1D disease genes to almost 60. In this mini-review, we address recent advances in the genetics of T1D and provide an update on the latest susceptibility loci added to the list of genes involved in the pathogenesis of T1D.
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Affiliation(s)
- Marina Bakay
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
| | - Rahul Pandey
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
| | - Hakon Hakonarson
- Center for Applied Genomics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
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Platelet hyperreactivity explains the bleeding abnormality and macrothrombocytopenia in a murine model of sitosterolemia. Blood 2013; 122:2732-42. [PMID: 23926302 DOI: 10.1182/blood-2013-06-510461] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Sitosterolemia is a rare, autosomal recessive disease caused by mutations in the adenosine triphosphate-binding cassette transporter genes ABCG5 or ABCG8 that result in accumulation of xenosterols in the body. Clinical manifestations include tendon xanthomas, premature coronary artery disease, hemolytic anemia, macrothrombocytopenia, and bleeding. Although the effect of sterol accumulation on the predisposition for atherosclerosis is evident, how xenosterol accumulation leads to defects in platelet physiology is unknown. Sitosterolemia induced in Abcg5- and Abcg8-deficient mice fed a high plant sterol diet resulted in accumulation of free sterols in platelet plasma membranes, leading to hyperactivatable platelets characterized by constitutive binding of fibrinogen to its αIIbβ3 integrin receptor, internalization of the αIIbβ3 complex, generation of platelet-derived microparticles, and changes in the quantity and subcellular localization of filamin. The latter was associated with macrothrombocytopenia, shedding of GPIbα, impaired platelet adhesion to von Willebrand factor, and inability to form stable thrombi. Plasma levels of soluble GPIbα were strongly correlated with plasma sitosterol levels in samples from human sitosterolemic patients, implicating a similar mechanism of sterol-induced platelet passivation in the human disease. Intercalation of plant sterols into the plasma membrane therefore results in dysregulation of multiple platelet activation pathways, leading to macrothrombocytopenia and bleeding.
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Horenstein RB, Mitchell BD, Post WS, Lütjohann D, von Bergmann K, Ryan KA, Terrin M, Shuldiner AR, Steinle NI. The ABCG8 G574R variant, serum plant sterol levels, and cardiovascular disease risk in the Old Order Amish. Arterioscler Thromb Vasc Biol 2012; 33:413-9. [PMID: 23241408 DOI: 10.1161/atvbaha.112.245480] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To determine whether long-term exposure to moderate elevations in plasma plant sterol levels increases risk for atherosclerosis. METHODS AND RESULTS In Old Order Amish participants aged 18 to 85 years, with (n=110) and without (n=181) 1 copy of the ABCG8 G574R variant, we compared mean plasma levels of plant sterols and cholesterol precursors and carotid intima-media wall thickness. Carriers of a single 574R allele had increased plant sterol levels (eg, 35%-37% higher plasma levels of sitosterol, campesterol, and stigmasterol) and increased plant sterol/cholesterol ratios (P<0.001 for all). 574R carriers had significantly decreased levels of lathosterol and lanosterol, precursors in a pathway for endogenous cholesterol synthesis, suggesting that plant sterols may alter regulation of genes involved in cholesterol synthesis. The G574R variant was not associated with high-density lipoprotein cholesterol or low-density lipoprotein cholesterol levels. Compared with noncarriers, 574R carriers had decreased carotid intima-media wall thickness (0.62 versus 0.66 mm; age- and sex-adjusted P=0.03). Adjustment for body weight, blood pressure, and standard lipid measures (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides) did not alter this association. CONCLUSIONS Although the G574R variant is associated with moderately elevated plant sterol levels, carriers of the 574R allele had modestly lower levels of carotid wall thickness compared with noncarriers.
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Affiliation(s)
- Richard B Horenstein
- Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
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Solca C, Tint GS, Patel SB. Dietary xenosterols lead to infertility and loss of abdominal adipose tissue in sterolin-deficient mice. J Lipid Res 2012. [PMID: 23180829 DOI: 10.1194/jlr.m031476] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The investigation of the human disease sitosterolemia (MIM 210250) has shed light not only on the pathways by which dietary sterols may traffic but also on how the mammalian body rids itself of cholesterol and defends against xenosterols. Two genes, ABCG5 and ABCG8, located at the sitosterolemia locus, each encodes a membrane-bound ABC half-transporter and constitutes a functional unit whose activity has now been shown to account for biliary and intestinal sterol excretion. Knockout mice deficient in Abcg5 or Abcg8 recapitulate many of the phenotypic features of sitosterolemia. During the course of our studies to characterize these knockout mice, we noted that these mice, raised on normal rodent chow, exhibited infertility as well as loss of abdominal fat. We show that, although sitosterolemia does not lead to any structural defects or to any overt endocrine defects, fertility could be restored if xenosterols are specifically blocked from entry and that the loss of fat is also reversed by a variety of maneuvers that limit xenosterol accumulation. These studies show that xenosterols may have a significant biological impact on normal mammalian physiology and that the Abcg5 or Abcg8 knockout mouse model may prove useful in investigating the role of xenosterols on mammalian physiology.
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Affiliation(s)
- Curzio Solca
- Clement J. Zablocki Veterans Medical Health Center, Milwaukee, WI, USA
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Abstract
Mammalian physiological processes, and likely any organism with a biliary tree, can distinguish between dietary cholesterol and non-cholesterols, retaining very little of the non-cholesterol in their bodies. Historically, the distinction between plant sterols and cholesterol has been known about for a century or more. That plants sterols were not 'absorbed' has been investigated for almost half a century. Indeed, the oral of plant sterols in gram quantities was shown to interfere with cholesterol absorption and is one of the oldest pharmacological therapies for hypercholesterolemia. Although the basis for the latter was shown to be caused by exclusion of cholesterol from intestinal micelles by plant sterols, it was not until the identification of the a rare genetic disease, sitosterolemia, first described in 1974, that led to the hypothesis that specific molecular mechanism(s) governed both the entry and excretion of sterols by the body. This talk will cover the physiology of dietary sterol metabolism, genetics and pathophysiology of sitosterolemia. Additionally, the role of plant sterols in normal and abnormal metabolism in humans as well as selected animal models will be discussed.
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Affiliation(s)
- Shailendra B Patel
- Division of Endocrinology, Metabolism and Clinical Nutrition, Medical College of Wisconsin, Milwaukee, WI
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Inhibition of cholesterol absorption: targeting the intestine. Pharm Res 2012; 29:3235-50. [PMID: 22923351 DOI: 10.1007/s11095-012-0858-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 08/06/2012] [Indexed: 01/06/2023]
Abstract
Atherosclerosis, the gradual formation of a lipid-rich plaque in the arterial wall is the primary cause of Coronary Artery Disease (CAD), the leading cause of mortality worldwide. Hypercholesterolemia, elevated circulating cholesterol, was identified as a key risk factor for CAD in epidemiological studies. Since the approval of Mevacor in 1987, the primary therapeutic intervention for hypercholesterolemia has been statins, drugs that inhibit the biosynthesis of cholesterol. With improved understanding of the risks associated with elevated cholesterol levels, health agencies are recommending reductions in cholesterol that are not achievable in every patient with statins alone, underlying the need for improved combination therapies. The whole body cholesterol pool is derived from two sources, biosynthesis and diet. Although statins are effective at reducing the biosynthesis of cholesterol, they do not inhibit the absorption of cholesterol, making this an attractive target for adjunct therapies. This report summarizes the efforts to target the gastrointestinal absorption of cholesterol, with emphasis on specifically targeting the gastrointestinal tract to avoid the off-target effects sometimes associated with systemic exposure.
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Miscellaneous non-inflammatory musculoskeletal conditions. Rare thesaurismosis and xanthomatosis. Best Pract Res Clin Rheumatol 2012; 25:683-701. [PMID: 22142747 DOI: 10.1016/j.berh.2011.10.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 10/13/2011] [Indexed: 11/21/2022]
Abstract
The focus will be on xanthomatosis, a tissue danger signal which needs to be recognized by the clinician, and its relationship with monogenetic lipoprotein disorders (cholesterol, triglycerides), bile acid and sterol metabolism, particularly on metabolic pathways and genetics as well as on musculoskeletal and cardiovascular involvement, and their implications for clinical management. The critical question is to assess coronary heart disease risk, requiring correct identification of the pattern of lipoprotein disorders and of the causes (primary or secondary). Familial hypercholesterolemia must be suspected in adults and children with raised total cholesterol, especially when there is a personal or a family history of premature coronary heart disease, usually requiring potent statins to achieve adequate LDL-cholesterol lowering, even if we do not know safety of long-term therapy and whether treatments of dyslipidemia early in life prevent cardiovascular diseases in adulthood. Cerebrotendinous xanthomatosis is a treatable disease and must be suspected if there is a history of infantile chronic diarrhea and/or juvenile cataracts, even in the absence of tendon xanthomas. Current evidence for the prevention and screening, diagnosis, and treatment of dyslipidemia are available for the clinicians.
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Abstract
Bile salts, cholesterol and phosphatidylcholine are secreted across the canalicular membrane of hepatocytes into bile by ATP-binding cassette (ABC) transporters. Secretion of bile salts by ABCB11 is essential for bile flow and for absorption of lipids and fat-soluble vitamins. ABCG5 and ABCG8 eliminate excess cholesterol and sterols from the body by secreting them into bile. There are two mechanisms to protect the canalicular membrane from solubilization by bile salts; ABCB4 secretes phosphatidylcholine into bile to form mixed micelles with bile salts, and ATP8B1 maintains the canalicular membrane in a liquid-ordered state. Three different forms of progressive familial intrahepatic cholestasis (PFIC) disorders, PFIC1, PFIC2 and PFIC3, are caused by mutations in ATP8B1, ABCB11 and ABCB4, respectively. Sitosterolemia is caused by mutations in ABCG5 and ABCG8. This article reviews the physiological roles of these canalicular transporters, and the pathophysiological processes and clinical features associated with their mutations.
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Affiliation(s)
- Jeannie Chan
- Southwest National Primate Research Center & Department of Genetics, Texas Biomedical Research Institute, PO Box 760549, San Antonio, TX, USA
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Nicolaou M, Andress EJ, Zolnerciks JK, Dixon PH, Williamson C, Linton KJ. Canalicular ABC transporters and liver disease. J Pathol 2011; 226:300-15. [DOI: 10.1002/path.3019] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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Wang G, Wang Z, Liang J, Cao L, Bai X, Ruan C. A phytosterolemia patient presenting exclusively with macrothrombocytopenia and stomatocytic hemolysis. Acta Haematol 2011; 126:95-8. [PMID: 21576934 DOI: 10.1159/000327248] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 02/24/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND Phytosterolemia is a rare autosomal recessive lipid storage disease. It is caused by mutations of ABCG5 and ABCG8 genes and characterized by the increased plasma levels of plant sterols. The common clinical manifestations include tendon and tuberous xanthomas and premature coronary heart disease; it has occasionally been associated with hematologic abnormalities. AIMS We report a phytosterolemia patient presenting exclusively with macrothrombocytopenia and stomatocytic hemolysis and discuss its clinical significance. CASE REPORT The patient, aged 31 years, was born of a consanguineous marriage. He had epistaxis from childhood and underwent splenectomy because of thrombocytopenia, anemia and splenomegaly at the age of 9 years. His blood film showed prominent stomatocytes and macroplatelets. High performance liquid chromatography showed a grossly elevated level of phytosterols in the blood. The patient was confirmed to be a homozygote of missense mutation R419H in ABCG5. CONCLUSION We describe a phytosterolemia patient whose clinical manifestations were macrothrombocytopenia, stomatocytic hemolysis and splenomegaly, without the common features of this disorder. Our results suggest that blood cells could be a target for the toxic effect of plasma plant sterols, which should be measured in patients with unexplained stomatocytosis and/or macrothrombocytopenia in order to determine if they have phytosterolemia.
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Affiliation(s)
- Gaifeng Wang
- Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Key Laboratory of Thrombosis and Hemostasis of Ministry of Health, Suzhou, China
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Izar MC, Machado VA, Fonseca FA. Genetic screening for homozygous and heterozygous familial hypercholesterolemia. Appl Clin Genet 2010; 3:147-57. [PMID: 23776359 PMCID: PMC3681171 DOI: 10.2147/tacg.s13490] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Familial hypercholesterolemia (FH) is a common inherited disorder that results in premature atherosclerosis. Diagnosis of FH is suspected on the basis of clinical criteria, but confirmation requires genetic testing. In the era of statins, early diagnosis and initiation of treatment can modify disease progression and outcomes. Therefore, cascade screening with a combination of lipid concentration measurements and DNA testing should be used to identify relatives of index cases with a clinical diagnosis of FH. Autosomal dominant FH is related to mutations in the low-density lipoprotein receptor (LDLR), apolipoprotein B-100 (APOB), or proprotein convertase subtilisin/kexin type 9 (PCSK9) genes. Genetic screening of the LDLR gene is challenging to achieve at a feasible cost, especially in people who do not have a founder effect. Nucleotide sequencing of all exons and flanking splicing regions in combination with multiplex ligation probe amplification to detect large insertions or deletions is considered the gold-standard approach to screen for LDLR mutations. Alternatively, the cDNA can be sequenced; however, this procedure is not suitable for use in large populations, because of the need of RNA extraction. Multiplex analysis can be appropriate for population with founder effects or a low number of different mutations. Finally, there are many techniques for a mutation scanning approach, which have some benefits over sequencing, and also with the potential for detecting known and novel mutations. Familial defective Apo B is amenable to genetic diagnosis by screening for a few mutations. Recently, gain-of-function mutations in PCSK9 gene have been demonstrated to cause FH phenotype. Strategies for population screening, cost-effectiveness of genetic screening, ethical aspects, and insurance policies are discussed and need implementation worldwide.
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Affiliation(s)
- Maria C Izar
- Cardiology Division, Department of Medicine, Federal University of São Paulo, UNIFESP, São Paulo, SP, Brazil
| | - Valéria A Machado
- Cardiology Division, Department of Medicine, Federal University of São Paulo, UNIFESP, São Paulo, SP, Brazil
| | - Francisco A Fonseca
- Cardiology Division, Department of Medicine, Federal University of São Paulo, UNIFESP, São Paulo, SP, Brazil
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Phytosterols and phytosterolemia: gene-diet interactions. GENES AND NUTRITION 2010; 6:17-26. [PMID: 21437027 DOI: 10.1007/s12263-010-0182-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 08/14/2010] [Indexed: 01/08/2023]
Abstract
Phytosterol intake is recommended as an adjunctive therapy for hypercholesterolemia, and plant sterols/stanols can reduce cholesterol absorption at the intestinal lumen through the Niemann-Pick C1 Like 1 (NPC1L1) transporter pathway by competitive solubilization in mixed micelles. Phytosterol absorption is of less magnitude than cholesterol and is preferably secreted in the intestinal lumen by ABCG5/G8 transporters. Therefore, plasma levels of plant sterols/stanols are negligible compared with cholesterol, under an ordinary diet. The mechanisms of cholesterol and plant sterols absorption and the whole-body pool of sterols are discussed in this chapter. There is controversy about treatment with statins inducing further increase in plasma non-cholesterol sterols raising concerns about the safety of supplementation of plant sterols to such drugs. In addition, increase in plant sterols has also been reported upon consumption of plant sterol-enriched foods, regardless of other treatments. Rare mutations on ABCG5/G8 transporters affecting cholesterol/non-cholesterol extrusion, causing sitosterolemia with xanthomas and premature atheroslerotic disease are now known, and cholesterol/plant sterols absorption inhibitor, ezetimibe, emerges as the drug that reduces phytosterolemia and promotes xanthoma regression. On the other hand, common polymorphisms affecting the NPC1L1 transporter can interfere with the action of ezetimibe. Gene-diet interactions participate in this intricate network modulating the expression of genetic variants on specific phenotypes and can also affect the individual response to the hypolipidemic treatment. These very interesting aspects promoted a great deal of research in the field.
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Niu DM, Chong KW, Hsu JH, Wu TJT, Yu HC, Huang CH, Lo MY, Kwok CF, Kratz LE, Ho LT. Clinical observations, molecular genetic analysis, and treatment of sitosterolemia in infants and children. J Inherit Metab Dis 2010; 33:437-43. [PMID: 20521169 DOI: 10.1007/s10545-010-9126-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Revised: 04/01/2010] [Accepted: 05/07/2010] [Indexed: 01/12/2023]
Abstract
The clinical observation and treatment of young children with sitosterolemia has rarely been reported. We report clinical, biochemical, and molecular genetic observations and treatment outcomes for five Chinese children from four separate families presenting with sitosterolemia in whom we identified two new (Y329X, G269R) and three known (R446X, N437K, R389H) mutations in the ABCG5 gene. The R389H mutation was found in 50% of alleles. Three of these five patients received cholestyramine therapy with a very good response. However, all patients discontinued this therapy because of poor compliance. Finally, all patients were on ezetimibe therapy and had satisfactory total serum cholesterol levels, though their plant sterol levels were still higher than normal. Another noteworthy finding is that a female infant had a serum cholesterol level of 654 mg/dl at 7 months of age, despite being breast fed (with very tiny amounts of plant sterols) since birth and undergoing 4 months of ezetimibe administration. Although she failed to respond to ezetimibe during this period, she did show improvement when the therapy was started again at 2 years of age. It is possible that another 23-month-old female patient also responded more slowly to ezetimibe treatment than older patients.
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Affiliation(s)
- Dau-Ming Niu
- Institute of Clinical Medicine, School of Medicine, National Yang-Ming University, No. 155, Sec. 2, Linong Street, Taipei, 112, Taiwan, Republic of China.
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