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Bertolini A, Bloks VW, Wilmink M, Bos E, van de Peppel IP, Eilers R, Prins S, Thomas R, de Bruin A, Verkade H, Jonker JW. Treatment of intestinal and liver features in cystic fibrosis mice by the osmotic laxative polyethylene glycol. J Cyst Fibros 2024; 23:461-473. [PMID: 37775443 DOI: 10.1016/j.jcf.2023.09.015] [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: 05/22/2023] [Revised: 09/07/2023] [Accepted: 09/24/2023] [Indexed: 10/01/2023]
Abstract
BACKGROUND Cystic Fibrosis (CF) is a genetic disease affecting multiple organs, primarily the lungs and digestive system. Improved pulmonary management significantly improved life expectancy of CF patients. As a result, extrapulmonary manifestations, including gastrointestinal and liver-related symptoms, have become more relevant. We previously reported that the osmotic laxative polyethylene glycol (PEG), which hydrates the CF gut, decreased fecal bile acid loss in a CF knockout mouse model. In the current study we investigated the effect of PEG on intestinal fat and cholesterol absorption and on CF-related liver features in a CF mouse model with the most common CF-causing mutation. METHODS CftrΔF508/ΔF508 (n=13) and wild-type (WT) (n=12) mice were treated with PEG for 2 weeks. The intestinal and hepatic effects of PEG were assessed by analysis of intestinal bile acid, cholesterol, and fat fluxes, transcriptome analysis as well as histology. RESULTS PEG improved intestinal malabsorption of bile acids, fat, and cholesterol in CftrΔF508/ΔF508 mice. Transcriptome analysis showed that PEG partially restored the intestinal signaling of nuclear receptors RXR, FXR, and CAR/PXR, which are involved in bile acid and xenobiotic metabolism. PEG also reduced liver inflammation in CF mice as assessed by transcriptome and histological analyses. CONCLUSIONS PEG, a non-absorbable osmotic laxative, improved intestinal nutrient absorption, intestinal bile acid and xenobiotic signaling, as well as CF-related liver features. These findings highlight the potential for osmotic laxation to improve gastrointestinal complications of CF in humans.
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Affiliation(s)
- Anna Bertolini
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Vincent W Bloks
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Marijn Wilmink
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Eline Bos
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Ivo P van de Peppel
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Roos Eilers
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Sake Prins
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Rachel Thomas
- Dutch Molecular Pathology Centre, Department of Pathobiology, Utrecht University, Utrecht, the Netherlands
| | - Alain de Bruin
- Dutch Molecular Pathology Centre, Department of Pathobiology, Utrecht University, Utrecht, the Netherlands
| | - Henkjan Verkade
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands
| | - Johan W Jonker
- Department of Pediatrics, Section of Molecular Metabolism and Nutrition, University Medical Center Groningen, Groningen, the Netherlands.
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2
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Heida A, van Dijk T, Smit M, Koehorst M, Koster M, Kloosterhuis N, Havinga R, Bloks VW, Wolters JC, de Bruin A, Kuivenhoven JA, de Boer JF, Kuipers F, van de Sluis B. Changes in bile acid composition are correlated with reduced intestinal cholesterol uptake in intestine-specific WASH-deficient mice. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159445. [PMID: 38086439 DOI: 10.1016/j.bbalip.2023.159445] [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: 10/20/2023] [Revised: 12/04/2023] [Accepted: 12/06/2023] [Indexed: 12/17/2023]
Abstract
The Wiskott-Aldrich syndrome protein and SCAR homolog (WASH) complex is a pentameric protein complex localized at endosomes, where it facilitates the transport of numerous receptors from endosomes toward the plasma membrane. Recent studies have shown that the WASH complex plays an essential role in cholesterol and glucose homeostasis in humans and mice. To investigate the physiological importance of intestinal WASH, we ablated the WASH component WASHC1 specifically in murine enterocytes. Male and female intestine-specific WASHC1-deficient mice (Washc1IKO) were challenged with either a standard chow diet or a high-cholesterol (1.25 %) diet (HCD). Washc1IKO mice fed a standard diet did not present any apparent phenotype, but when fed an HCD, their hepatic cholesterol levels were ~ 50 % lower compared to those observed in control mice. The intestinal cholesterol absorption was almost 2-fold decreased in Washc1IKO mice, which translated into increased fecal neutral sterol loss. The intestinal expression of cholesterogenic genes, such as Hmgcs1, Hmgcr, and Ldlr, was significantly higher in Washc1IKO mice than in control mice and correlated with increased whole-body de novo cholesterol synthesis, likely to compensate for impaired intestinal cholesterol absorption. Unexpectedly, the ratio of biliary 12α-/non-12α-hydroxylated bile acids (BAs) was decreased in Washc1IKO mice and reversing this reduced ratio by feeding the mice with the HCD supplemented with 0.5 % (w/w) sodium cholate normalized the improvement of hepatic cholesterol levels in Washc1IKO mice. Our data indicate that the intestinal WASH complex plays an important role in intestinal cholesterol absorption, likely by modulating biliary BA composition.
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Affiliation(s)
- Andries Heida
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Theo van Dijk
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Marieke Smit
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Martijn Koehorst
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Mirjam Koster
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Niels Kloosterhuis
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Rick Havinga
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Vincent W Bloks
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Justina C Wolters
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Alain de Bruin
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, the Netherlands
| | - Jan Albert Kuivenhoven
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Jan Freark de Boer
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Folkert Kuipers
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands; European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - Bart van de Sluis
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
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3
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Truong JK, Li J, Li Q, Pachura K, Rao A, Gumber S, Fuchs CD, Feranchak AP, Karpen SJ, Trauner M, Dawson PA. Active enterohepatic cycling is not required for the choleretic actions of 24-norUrsodeoxycholic acid in mice. JCI Insight 2023; 8:e149360. [PMID: 36787187 PMCID: PMC10070106 DOI: 10.1172/jci.insight.149360] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 02/07/2023] [Indexed: 02/15/2023] Open
Abstract
The pronounced choleretic properties of 24-norUrsodeoxycholic acid (norUDCA) to induce bicarbonate-rich bile secretion have been attributed to its ability to undergo cholehepatic shunting. The goal of this study was to identify the mechanisms underlying the choleretic actions of norUDCA and the role of the bile acid transporters. Here, we show that the apical sodium-dependent bile acid transporter (ASBT), organic solute transporter-α (OSTα), and organic anion transporting polypeptide 1a/1b (OATP1a/1b) transporters are dispensable for the norUDCA stimulation of bile flow and biliary bicarbonate secretion. Chloride channels in biliary epithelial cells provide the driving force for biliary secretion. In mouse large cholangiocytes, norUDCA potently stimulated chloride currents that were blocked by siRNA silencing and pharmacological inhibition of calcium-activated chloride channel transmembrane member 16A (TMEM16A) but unaffected by ASBT inhibition. In agreement, blocking intestinal bile acid reabsorption by coadministration of an ASBT inhibitor or bile acid sequestrant did not impact norUDCA stimulation of bile flow in WT mice. The results indicate that these major bile acid transporters are not directly involved in the absorption, cholehepatic shunting, or choleretic actions of norUDCA. Additionally, the findings support further investigation of the therapeutic synergy between norUDCA and ASBT inhibitors or bile acid sequestrants for cholestatic liver disease.
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Affiliation(s)
- Jennifer K. Truong
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Emory University School of Medicine, Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Jianing Li
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Emory University School of Medicine, Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Qin Li
- Department of Pediatrics, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Kimberly Pachura
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Emory University School of Medicine, Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Anuradha Rao
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Emory University School of Medicine, Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Sanjeev Gumber
- Division of Pathology and Laboratory Medicine, Yerkes National Research Center, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Claudia Daniela Fuchs
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Andrew P. Feranchak
- Department of Pediatrics, University of Pittsburgh Medical Center Children’s Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Saul J. Karpen
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Emory University School of Medicine, Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Michael Trauner
- Hans Popper Laboratory of Molecular Hepatology, Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Vienna, Austria
| | - Paul A. Dawson
- Department of Pediatrics, Division of Pediatric Gastroenterology, Hepatology and Nutrition, Emory University School of Medicine, Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
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Moon J, Lee SY, Na HS, Lee AR, Cho KH, Choi JW, Park SH, Cho ML. Ezetimibe ameliorates clinical symptoms in a mouse model of ankylosing spondylitis associated with suppression of Th17 differentiation. Front Immunol 2022; 13:922531. [PMID: 36059546 PMCID: PMC9428320 DOI: 10.3389/fimmu.2022.922531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 07/22/2022] [Indexed: 12/01/2022] Open
Abstract
Ankylosing spondylitis (AS) is a chronic inflammatory disease that causes spinal inflammation and fusion. Although the cause of AS is unknown, genetic factors (e.g., HLA-B27) and environmental factors (e.g., sex, age, and infection) increase the risk of AS. Current treatments for AS are to improve symptoms and suppress disease progression. There is no way to completely cure it. High blood cholesterol and lipid levels aggravate the symptoms of autoimmune diseases. We applied hyperlipidemia drugs ezetimibe and rosuvastatin to AS mice and to PBMCs from AS patients. Ezetimibe and rosuvastatin was administered for 11 weeks to AS model mice on the SKG background. Then, the tissues and cells of mice were performed using flow cytometry, computed tomography, immunohistochemistry, and immunofluorescence. Also, the normal mouse splenocytes were cultured in Th17 differentiation conditions for in vitro analysis such as flow cytometry, ELISA and RNA sequencing. The 10 AS patients’ PBMCs were treated with ezetimibe and rosuvastatin. The patients’ PBMC were analyzed by flow cytometry and ELISA for investigation of immune cell type modification. Ezetimibe caused substantial inhibition for AS. The present study showed that ezetimibe inhibits Th17 cell function, thereby slowing the progression of AS. It is well known that statins are more effective in reducing blood lipid concentrations than ezetimibe, however, our results that ezetimibe had a better anti-inflammatory effect than rosuvastatin in AS. This data suggests that ezetimibe has an independent anti-inflammatory effect independent of blood lipid reduction. To investigate whether ezetimibe has its anti-inflammatory effect through which signaling pathway, various in vitro experiments and RNA sequencing have proceeded. Here, this study suggests that ezetimibe can be an effective treatment for AS patients by inhibiting Th17 differentiation-related genes such as IL-23R and IL-1R. Thus, this study suggests that ezetimibe has therapeutic potential for AS through inhibition of Th17 differentiation and the production of pro-inflammatory cytokines.
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Affiliation(s)
- Jeonghyeon Moon
- Departments of Neurology and Immunobiology, Yale School of Medicine, New Haven, CT, United States
| | - Seon-Yeong Lee
- Rheumatism Research Center, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Lab of Translational ImmunoMedicine, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Hyun Sik Na
- Rheumatism Research Center, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Lab of Translational ImmunoMedicine, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Department of Biomedicine & Health Sciences, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - A Ram Lee
- Rheumatism Research Center, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Lab of Translational ImmunoMedicine, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Department of Biomedicine & Health Sciences, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Keun-Hyung Cho
- Rheumatism Research Center, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Lab of Translational ImmunoMedicine, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Department of Biomedicine & Health Sciences, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Jeong Won Choi
- Rheumatism Research Center, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Lab of Translational ImmunoMedicine, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Sung-Hwan Park
- Division of Rheumatology, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Mi-La Cho
- Rheumatism Research Center, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Lab of Translational ImmunoMedicine, Catholic Research Institute of Medical Science, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Department of Biomedicine & Health Sciences, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- Department of Medical Life Sciences, College of Medicine, The Catholic University of Korea, Seoul, South Korea
- *Correspondence: Mi-La Cho,
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5
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Stellaard F. From Dietary Cholesterol to Blood Cholesterol, Physiological Lipid Fluxes, and Cholesterol Homeostasis. Nutrients 2022; 14:nu14081643. [PMID: 35458205 PMCID: PMC9025004 DOI: 10.3390/nu14081643] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/04/2022] [Accepted: 04/12/2022] [Indexed: 02/06/2023] Open
Abstract
Dietary cholesterol (C) is a major contributor to the endogenous C pool, and it affects the serum concentration of total C, particularly the low-density lipoprotein cholesterol (LDL-C). A high serum concentration of LDL-C is associated with an increased risk for atherosclerosis and cardiovascular diseases. This concentration is dependent on hepatic C metabolism creating a balance between C input (absorption and synthesis) and C elimination (conversion to bile acids and fecal excretion). The daily C absorption rate is determined by dietary C intake, biliary C secretion, direct trans-intestinal C excretion (TICE), and the fractional C absorption rate. Hepatic C metabolism coordinates C fluxes entering the liver via chylomicron remnants (CMR), LDL, high-density lipoproteins (HDL), hepatic C synthesis, and those leaving the liver via very low-density lipoproteins (VLDL), biliary secretion, and bile acid synthesis. The knowns and the unknowns of this C homeostasis are discussed.
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Affiliation(s)
- Frans Stellaard
- Department of Nutrition and Movement Sciences, NUTRIM (School of Nutrition and Translational Research in Metabolism), Maastricht University Medical Center, P.O. Box 5800 Maastricht, The Netherlands;
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Venusberg-Campus 1, 53127 Bonn, Germany
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6
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Bertolini A, van de Peppel I, Havinga R, Jonker J, Verkade H. The Apical Sodium-Dependent Bile Acid Transporter in Cholangiocytes Is Not Required for the Generation of Bile Flow in Mice. GASTRO HEP ADVANCES 2022; 1:375-377. [PMID: 39131683 PMCID: PMC11308047 DOI: 10.1016/j.gastha.2022.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 02/02/2022] [Indexed: 08/13/2024]
Affiliation(s)
| | - I.P. van de Peppel
- Correspondence: Address correspondence to: Ivo P. van de Peppel, MD, PhD, Pediatrics, Universitair Medisch Centrum Groningen, Hanzeplein 1, Groningen 9713GZ, The Netherlands.
| | - R. Havinga
- Section Molecular Metabolism and Nutrition, Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - J.W. Jonker
- Section Molecular Metabolism and Nutrition, Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - H.J. Verkade
- Section Molecular Metabolism and Nutrition, Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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7
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Mice with a deficiency in Peroxisomal Membrane Protein 4 (PXMP4) display mild changes in hepatic lipid metabolism. Sci Rep 2022; 12:2512. [PMID: 35169201 PMCID: PMC8847483 DOI: 10.1038/s41598-022-06479-y] [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: 10/28/2020] [Accepted: 01/31/2022] [Indexed: 11/08/2022] Open
Abstract
Peroxisomes play an important role in the metabolism of a variety of biomolecules, including lipids and bile acids. Peroxisomal Membrane Protein 4 (PXMP4) is a ubiquitously expressed peroxisomal membrane protein that is transcriptionally regulated by peroxisome proliferator-activated receptor α (PPARα), but its function is still unknown. To investigate the physiological function of PXMP4, we generated a Pxmp4 knockout (Pxmp4-/-) mouse model using CRISPR/Cas9-mediated gene editing. Peroxisome function was studied under standard chow-fed conditions and after stimulation of peroxisomal activity using the PPARα ligand fenofibrate or by using phytol, a metabolite of chlorophyll that undergoes peroxisomal oxidation. Pxmp4-/- mice were viable, fertile, and displayed no changes in peroxisome numbers or morphology under standard conditions. Also, no differences were observed in the plasma levels of products from major peroxisomal pathways, including very long-chain fatty acids (VLCFAs), bile acids (BAs), and BA intermediates di- and trihydroxycholestanoic acid. Although elevated levels of the phytol metabolites phytanic and pristanic acid in Pxmp4-/- mice pointed towards an impairment in peroxisomal α-oxidation capacity, treatment of Pxmp4-/- mice with a phytol-enriched diet did not further increase phytanic/pristanic acid levels. Finally, lipidomic analysis revealed that loss of Pxmp4 decreased hepatic levels of the alkyldiacylglycerol class of neutral ether lipids, particularly those containing polyunsaturated fatty acids. Together, our data show that while PXMP4 is not critical for overall peroxisome function under the conditions tested, it may have a role in the metabolism of (ether)lipids.
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8
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Vidimce J, Pillay J, Ronda O, Boon A, Pennell E, Ashton KJ, Dijk TH, Wagner K, Verkade HJ, Bulmer AC. Sexual Dimorphism: increased sterol excretion leads to hypocholesterolaemia in female hyperbilirubinaemic Gunn rats. J Physiol 2022; 600:1889-1911. [PMID: 35156712 PMCID: PMC9310728 DOI: 10.1113/jp282395] [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: 09/20/2021] [Accepted: 02/02/2022] [Indexed: 11/08/2022] Open
Abstract
Abstract Circulating bilirubin is associated with reduced serum cholesterol concentrations in humans and in hyperbilirubinaemic Gunn rats. However, mechanisms contributing to hypocholesterolaemia remain unknown. Therefore, this study aimed to investigate cholesterol synthesis, transport and excretion in mutant Gunn rats. Adult Gunn and control rats were assessed for daily faecal sterol excretion using metabolic cages, and water was supplemented with [1‐13C]‐acetate to determine cholesterol synthesis. Bile was collected to measure biliary lipid secretion. Serum and liver were collected for biochemical analysis and for gene/protein expression using RT‐qPCR and western blot, respectively. Additionally, serum was collected and analysed from juvenile rats. A significant interaction of sex, age and phenotype on circulating lipids was found with adult female Gunn rats reporting significantly lower cholesterol and phospholipids. Female Gunn rats also demonstrated elevated cholesterol synthesis, greater biliary lipid secretion and increased total faecal cholesterol and bile acid excretion. Furthermore, they possessed increased hepatic low‐density lipoprotein (LDL) receptor and SREBP2 expression. In contrast, there were no changes to sterol metabolism in adult male Gunn rats. This is the first study to demonstrate elevated faecal sterol excretion in female hyperbilirubinaemic Gunn rats. Increased sterol excretion creates a negative intestinal sterol balance that is compensated for by increased cholesterol synthesis and LDL receptor expression. Therefore, reduced circulating cholesterol is potentially caused by increased hepatic uptake via the LDL receptor. Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome). Key points Female adult hyperbilirubinaemic (Gunn) rats demonstrated lower circulating cholesterol, corroborating human studies that report a negative association between bilirubin and cholesterol concentrations. Furthermore, female Gunn rats had elevated sterol excretion creating a negative intestinal sterol balance that was compensated for by elevated cholesterol synthesis and increased hepatic low‐density lipoprotein (LDL) receptor expression. Therefore, elevated LDL receptor expression potentially leads to reduced circulating cholesterol levels in female Gunn rats providing an explanation for the hypocholesterolaemia observed in humans with elevated bilirubin levels. This study also reports a novel interaction of sex with the hyperbilirubinaemic phenotype on sterol metabolism because changes were only reported in females and not in male Gunn rats. Future studies are required to further evaluate the sexual dimorphism of this response and whether similar findings occur in females with benign unconjugated hyperbilirubinaemia (Gilbert's syndrome).
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Affiliation(s)
- Josif Vidimce
- School of Pharmacy and Medical Sciences Griffith University Gold Coast Queensland Australia
| | - Johara Pillay
- School of Pharmacy and Medical Sciences Griffith University Gold Coast Queensland Australia
| | - Onne Ronda
- Pediatric Gastroenterology/Hepatology Dept. Pediatrics University of Groningen, University Medical Center Groningen Groningen The Netherlands
| | - Ai‐Ching Boon
- School of Pharmacy and Medical Sciences Griffith University Gold Coast Queensland Australia
| | - Evan Pennell
- School of Pharmacy and Medical Sciences Griffith University Gold Coast Queensland Australia
| | - Kevin J. Ashton
- Faculty of Health Science and Medicine Bond University Gold Coast Australia
| | - Theo H. Dijk
- University of Groningen, University Medical Center Groningen Department of Laboratory Medicine Groningen The Netherlands
| | - Karl‐Heinz Wagner
- Department of Nutritional Sciences and Research Platform Active Ageing University of Vienna Vienna Austria
| | - Henkjan J. Verkade
- Pediatric Gastroenterology/Hepatology Dept. Pediatrics University of Groningen, University Medical Center Groningen Groningen The Netherlands
| | - Andrew C. Bulmer
- School of Pharmacy and Medical Sciences Griffith University Gold Coast Queensland Australia
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Abstract
PURPOSE OF REVIEW The transintestinal cholesterol efflux (TICE) pathway is the second described route for plasma cholesterol fecal elimination. This article summarizes recent TICE research progresses, involving TICE inducers, molecular determinants of this pathway, and its role in lipoprotein metabolism. RECENT FINDINGS TICE is an active pathway in mice, rats, and humans. Kinetic measurements showed that under basal conditions, the relative contribution of TICE in fecal elimination of plasma cholesterol is quantitatively less important than the hepatobiliary pathway. However, the amplitude of TICE can be induced by numerous nutritional factors and pharmacological drugs. More importantly, by contrast with the stimulation of biliary cholesterol excretion that is associated with an increased risk of gallstone formation, TICE appears as a safer therapeutical target. Finally, several independent studies have demonstrated that TICE is actively contributing to the anti-atherogenic reverse cholesterol pathway reinforcing the interest to better understand its mode of action. The discovery of TICE and the understanding of its mode of action open new therapeutical perspectives for patients at high risk of cardiovascular diseases.
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10
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Kunst RF, Verkade HJ, Oude Elferink RP, van de Graaf SF. Targeting the Four Pillars of Enterohepatic Bile Salt Cycling; Lessons From Genetics and Pharmacology. Hepatology 2021; 73:2577-2585. [PMID: 33222321 PMCID: PMC8252069 DOI: 10.1002/hep.31651] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 10/29/2020] [Accepted: 11/12/2020] [Indexed: 12/14/2022]
Abstract
Bile salts play a pivotal role in lipid homeostasis, are sensed by specialized receptors, and have been implicated in various disorders affecting the gut or liver. They may play a role either as culprit or as potential panacea. Four very efficient transporters mediate most of the hepatic and intestinal bile salt uptake and efflux, and are each essential for the efficient enterohepatic circulation of bile salts. Starting from the intestinal lumen, conjugated bile salts cross the otherwise impermeable lipid bilayer of (primarily terminal ileal) enterocytes through the apical sodium-dependent bile acid transporter (gene SLC10A2) and leave the enterocyte through the basolateral heteromeric organic solute transporter, which consists of an alpha and beta subunit (encoded by SLC51A and SLC51B). The Na+ -taurocholate cotransporting polypeptide (gene SLC10A1) efficiently clears the portal circulation of bile salts, and the apical bile salt export pump (gene ABCB11) pumps the bile salts out of the hepatocyte into primary bile, against a very steep concentration gradient. Recently, individuals lacking either functional Na+ -taurocholate cotransporting polypeptide or organic solute transporter have been described, completing the quartet of bile acid transport deficiencies, as apical sodium-dependent bile acid transporter and bile salt export pump deficiencies were already known for years. Novel pathophysiological insights have been obtained from knockout mice lacking functional expression of these genes and from pharmacological transporter inhibition in mice or humans. Conclusion: We provide a concise overview of the four main bile salt transport pathways and of their status as possible targets of interventions in cholestatic or metabolic disorders.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 11/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 11/metabolism
- Animals
- Bile Acids and Salts/metabolism
- Biological Transport, Active/drug effects
- Biological Transport, Active/physiology
- Drug Development
- Enterohepatic Circulation/drug effects
- Enterohepatic Circulation/physiology
- Humans
- Membrane Transport Proteins/genetics
- Membrane Transport Proteins/metabolism
- Organic Anion Transporters, Sodium-Dependent/antagonists & inhibitors
- Organic Anion Transporters, Sodium-Dependent/genetics
- Organic Anion Transporters, Sodium-Dependent/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Symporters/antagonists & inhibitors
- Symporters/genetics
- Symporters/metabolism
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Affiliation(s)
- Roni F. Kunst
- Tytgat Institute for Liver and Intestinal ResearchAmsterdam UMC, University of AmsterdamAmsterdamthe Netherlands
- Amsterdam Gastroenterology Endocrinology MetabolismAmsterdamthe Netherlands
| | - Henkjan J. Verkade
- Pediatric Gastroenterology/HepatologyDepartment of PediatricsUniversity of GroningenUniversity Medical Center GroningenGroningenthe Netherlands
| | - Ronald P.J. Oude Elferink
- Tytgat Institute for Liver and Intestinal ResearchAmsterdam UMC, University of AmsterdamAmsterdamthe Netherlands
- Amsterdam Gastroenterology Endocrinology MetabolismAmsterdamthe Netherlands
- Department of Gastroenterology and HepatologyAmsterdam UMCUniversity of AmsterdamAmsterdamthe Netherlands
| | - Stan F.J. van de Graaf
- Tytgat Institute for Liver and Intestinal ResearchAmsterdam UMC, University of AmsterdamAmsterdamthe Netherlands
- Amsterdam Gastroenterology Endocrinology MetabolismAmsterdamthe Netherlands
- Department of Gastroenterology and HepatologyAmsterdam UMCUniversity of AmsterdamAmsterdamthe Netherlands
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11
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Zinöcker MK, Svendsen K, Dankel SN. The homeoviscous adaptation to dietary lipids (HADL) model explains controversies over saturated fat, cholesterol, and cardiovascular disease risk. Am J Clin Nutr 2021; 113:277-289. [PMID: 33471045 DOI: 10.1093/ajcn/nqaa322] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 10/09/2020] [Indexed: 12/16/2022] Open
Abstract
SFAs play the leading role in 1 of the greatest controversies in nutrition science. Relative to PUFAs, SFAs generally increase circulating concentrations of LDL cholesterol, a risk factor for atherosclerotic cardiovascular disease (ASCVD). However, the purpose of regulatory mechanisms that control the diet-induced lipoprotein cholesterol dynamics is rarely discussed in the context of human adaptive biology. We argue that better mechanistic explanations can help resolve lingering controversies, with the potential to redefine aspects of research, clinical practice, dietary advice, public health management, and food policy. In this paper we propose a novel model, the homeoviscous adaptation to dietary lipids (HADL) model, which explains changes in lipoprotein cholesterol as adaptive homeostatic adjustments that serve to maintain cell membrane fluidity and hence optimal cell function. Due to the highly variable intake of fatty acids in humans and other omnivore species, we propose that circulating lipoproteins serve as a buffer to enable the rapid redistribution of cholesterol molecules between specific cells and tissues that is necessary with changes in dietary fatty acid supply. Hence, circulating levels of LDL cholesterol may change for nonpathological reasons. Accordingly, an SFA-induced raise in LDL cholesterol in healthy individuals could represent a normal rather than a pathologic response. These regulatory mechanisms may become disrupted secondarily to pathogenic processes in association with insulin resistance and the presence of other ASCVD risk factors, as supported by evidence showing diverging lipoprotein responses in healthy individuals as opposed to those with metabolic disorders such as insulin resistance and obesity. Corresponding with the model, we suggest alternative contributing factors to the association between elevated LDL cholesterol concentrations and ASCVD, involving dietary factors beyond SFAs, such as an increased endotoxin load from diet-gut microbiome interactions and subsequent chronic low-grade inflammation that interferes with fine-tuned signaling pathways.
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Affiliation(s)
| | - Karianne Svendsen
- Department of Nutrition, University of Oslo, Oslo, Norway.,The Lipid Clinic, Department of Endocrinology, Morbid Obesity and Preventive Medicine, Oslo University Hospital, Oslo, Norway
| | - Simon Nitter Dankel
- Mohn Nutrition Research Laboratory, Department of Clinical Science, University of Bergen, Bergen, Norway
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12
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Induction of fecal cholesterol excretion is not effective for the treatment of hyperbilirubinemia in Gunn rats. Pediatr Res 2021; 89:510-517. [PMID: 32357361 DOI: 10.1038/s41390-020-0926-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 02/28/2020] [Accepted: 04/01/2020] [Indexed: 11/08/2022]
Abstract
BACKGROUND Unconjugated hyperbilirubinemia, a feature of neonatal jaundice or Crigler-Najjar syndrome, can lead to neurotoxicity and even death. We previously demonstrated that unconjugated bilirubin (UCB) can be eliminated via transintestinal excretion in Gunn rats, a model of unconjugated hyperbilirubinemia, and that this is stimulated by enhancing fecal fatty acid excretion. Since transintestinal excretion also occurs for cholesterol (TICE), we hypothesized that increasing fecal cholesterol excretion and/or TICE could also enhance fecal UCB disposal and subsequently lower plasma UCB concentrations. METHODS To determine whether increasing fecal cholesterol excretion could ameliorate unconjugated hyperbilirubinemia, we treated hyperbilirubinemic Gunn rats with ezetimibe (EZE), an intestinal cholesterol absorption inhibitor, and/or a liver X receptor (LXR) and farnesoid X receptor (FXR) agonist (T0901317 (T09) and obeticholic acid (OCA), respectively), known to stimulate TICE. RESULTS We found that EZE treatment alone or in combination with T09 or OCA increased fecal cholesterol disposal but did not lower plasma UCB levels. CONCLUSIONS These findings do not support a link between the regulation of transintestinal excretion of cholesterol and bilirubin. Furthermore, induction of fecal cholesterol excretion is not a potential therapy for unconjugated hyperbilirubinemia. IMPACT Increasing fecal cholesterol excretion is not effective to treat unconjugated hyperbilirubinemia. This is the first time a potential relation between transintestinal excretion of cholesterol and unconjugated bilirubin is investigated. Transintestinal excretion of cholesterol and unconjugated bilirubin do not seem to be quantitatively linked. Unlike intestinal fatty acids, cholesterol cannot "capture" unconjugated bilirubin to increase its excretion. These results add to our understanding of ways to improve and factors regulating unconjugated bilirubin disposal in hyperbilirubinemic conditions.
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13
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van de Peppel IP, Verkade HJ, Jonker JW. Metabolic consequences of ileal interruption of the enterohepatic circulation of bile acids. Am J Physiol Gastrointest Liver Physiol 2020; 319:G619-G625. [PMID: 32938201 DOI: 10.1152/ajpgi.00308.2020] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The enterohepatic circulation of bile acids comprises a tightly regulated process of hepatic bile acid secretion, intestinal reabsorption and transport back to the liver. Disruption of this process has significant consequences for gastrointestinal, liver and whole body homeostasis and therefore offers opportunities for therapeutic intervention. In this review we discuss the effects of (pharmacological) interruption of the enterohepatic circulation at different levels. Recently, several studies have been published on ileal interruption of the enterohepatic circulation of bile acids, targeting the apical-sodium dependent bile acid transporter (ASBT, SLC10A2), as therapy for various diseases. However, ambiguous results have been reported and in-depth mechanistic insights are lacking. Here we discuss these novel studies and review the current knowledge on the consequences of ASBT inhibition and its potential effects on physiology and metabolism.
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Affiliation(s)
- Ivo P van de Peppel
- Section of Molecular Metabolism and Nutrition, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Henkjan J Verkade
- Section of Molecular Metabolism and Nutrition, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Johan W Jonker
- Section of Molecular Metabolism and Nutrition, Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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14
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van de Peppel IP, Rao A, Dommerholt MB, Bongiovanni L, Thomas R, de Bruin A, Karpen SJ, Dawson PA, Verkade HJ, Jonker JW. The Beneficial Effects of Apical Sodium-Dependent Bile Acid Transporter Inactivation Depend on Dietary Fat Composition. Mol Nutr Food Res 2020; 64:e2000750. [PMID: 33079450 PMCID: PMC7757219 DOI: 10.1002/mnfr.202000750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/25/2020] [Indexed: 02/06/2023]
Abstract
SCOPE The apical sodium-dependent bile acid transporter (ASBT, SLC10A2) is important in the enterohepatic cycling of bile acids and thereby in the intestinal absorption of lipids. ASBT inhibition has been shown to improve aspects of the metabolic syndrome, but the underlying mechanisms have remained unclear. Here, the effect of ASBT inhibition on the uptake of specific fatty acids and its consequences for diet-induced obesity and non-alcoholic fatty liver disease (NAFLD) are investigated. METHODS Intestinal fat absorption is determined in mice receiving an ASBT inhibitor and in Asbt-/- mice. Metabolic disease development is determined in Asbt-/- mice receiving a low-fat control diet (LFD) or high-fat diet (HFD) rich in saturated fatty acids (SFAs) or PUFAs. RESULTS Both ASBT inhibition and Asbt gene inactivation reduce total fat absorption, particularly of SFAs. Asbt gene inactivation lowers bodyweight gain, improves insulin sensitivity, and decreases the NAFLD activity score upon feeding a HFD rich in SFAs, but not in PUFAs. CONCLUSIONS The beneficial metabolic effects of ASBT inactivation on diet-induced obesity depend on decreased intestinal absorption of SFAs, and thus on the dietary fatty acid composition. These findings highlight the importance of dietary fatty acid composition in the therapeutic effects of ASBT inhibition.
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Affiliation(s)
- Ivo P. van de Peppel
- Section of Molecular Metabolism and NutritionDepartment of PediatricsUniversity of GroningenUniversity Medical Center GroningenHanzeplein 1Groningen9713 GZThe Netherlands
| | - Anuradha Rao
- Department of PediatricsEmory University School of Medicine1760 Haygood Drive NortheastAtlantaGA 30322USA
| | - Marleen B. Dommerholt
- Section of Molecular Metabolism and NutritionDepartment of PediatricsUniversity of GroningenUniversity Medical Center GroningenHanzeplein 1Groningen9713 GZThe Netherlands
| | - Laura Bongiovanni
- Dutch Molecular Pathology CentreDepartment of PathobiologyFaculty of Veterinary MedicineUtrecht UniversityYalelaan 1Utrecht3584 CLThe Netherlands
| | - Rachel Thomas
- Dutch Molecular Pathology CentreDepartment of PathobiologyFaculty of Veterinary MedicineUtrecht UniversityYalelaan 1Utrecht3584 CLThe Netherlands
| | - Alain de Bruin
- Dutch Molecular Pathology CentreDepartment of PathobiologyFaculty of Veterinary MedicineUtrecht UniversityYalelaan 1Utrecht3584 CLThe Netherlands
| | - Saul J. Karpen
- Department of PediatricsEmory University School of Medicine1760 Haygood Drive NortheastAtlantaGA 30322USA
| | - Paul A. Dawson
- Department of PediatricsEmory University School of Medicine1760 Haygood Drive NortheastAtlantaGA 30322USA
| | - Henkjan J. Verkade
- Section of Molecular Metabolism and NutritionDepartment of PediatricsUniversity of GroningenUniversity Medical Center GroningenHanzeplein 1Groningen9713 GZThe Netherlands
| | - Johan W. Jonker
- Section of Molecular Metabolism and NutritionDepartment of PediatricsUniversity of GroningenUniversity Medical Center GroningenHanzeplein 1Groningen9713 GZThe Netherlands
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15
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Yang N, Dong YQ, Jia GX, Fan SM, Li SZ, Yang SS, Li YB. ASBT(SLC10A2): A promising target for treatment of diseases and drug discovery. Biomed Pharmacother 2020; 132:110835. [PMID: 33035828 DOI: 10.1016/j.biopha.2020.110835] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/17/2020] [Accepted: 09/28/2020] [Indexed: 12/14/2022] Open
Abstract
Bile acids has gradually become a new focus in various diseases, and ASBT as a transporter responsible for the reabsorption of ileal bile acids, is a key hinge associated to the bile acids-cholesterol balance and bile acids of enterohepatic circulation. The cumulative studies have also shown that ASBT is a promising target for treatment of liver, gallbladder, intestinal and metabolic diseases. This article briefly reviewed the process of bile acids enterohepatic circulation, as well as the regulations of ASBT expression, covering transcription factors, nuclear receptors and gut microbiota. In addition, the relationship between ASBT and various diseases were discussed in this paper. According to the structural classification of ASBT inhibitors, the research status of ASBT inhibitors and potential ASBT inhibitors of traditional Chinese medicine (such resveratrol, jatrorrhizine in Coptis chinensis) were summarized. This review provides a basis for the development of ASBT inhibitors and the treatment strategy of related diseases.
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Affiliation(s)
- Na Yang
- Tianjin University of Traditional Chinese Medicine, No.10, Poyang Lake Road, Tuanbo New City, Jinghai District, Tianjin 301617, China
| | - Ya-Qian Dong
- Tianjin University of Traditional Chinese Medicine, No.10, Poyang Lake Road, Tuanbo New City, Jinghai District, Tianjin 301617, China
| | - Guo-Xiang Jia
- Tianjin University of Traditional Chinese Medicine, No.10, Poyang Lake Road, Tuanbo New City, Jinghai District, Tianjin 301617, China
| | - Si-Miao Fan
- Tianjin University of Traditional Chinese Medicine, No.10, Poyang Lake Road, Tuanbo New City, Jinghai District, Tianjin 301617, China
| | - Shan-Ze Li
- Tianjin University of Traditional Chinese Medicine, No.10, Poyang Lake Road, Tuanbo New City, Jinghai District, Tianjin 301617, China
| | - Shen-Shen Yang
- Tianjin University of Traditional Chinese Medicine, No.10, Poyang Lake Road, Tuanbo New City, Jinghai District, Tianjin 301617, China.
| | - Yu-Bo Li
- Tianjin University of Traditional Chinese Medicine, No.10, Poyang Lake Road, Tuanbo New City, Jinghai District, Tianjin 301617, China.
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16
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Tanaka Y, Ikeda T, Ogawa H, Kamisako T. Ezetimibe Markedly Reduces Hepatic Triglycerides and Cholesterol in Rats Fed on Fish Oil by Increasing the Expression of Cholesterol Efflux Transporters. J Pharmacol Exp Ther 2020; 374:175-183. [DOI: 10.1124/jpet.120.265660] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 04/30/2020] [Indexed: 12/13/2022] Open
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17
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Rao A, van de Peppel IP, Gumber S, Karpen SJ, Dawson PA. Attenuation of the Hepatoprotective Effects of Ileal Apical Sodium Dependent Bile Acid Transporter (ASBT) Inhibition in Choline-Deficient L-Amino Acid-Defined (CDAA) Diet-Fed Mice. Front Med (Lausanne) 2020; 7:60. [PMID: 32158763 PMCID: PMC7052288 DOI: 10.3389/fmed.2020.00060] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 02/10/2020] [Indexed: 12/15/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a major growing worldwide health problem. We previously reported that interruption of the enterohepatic circulation of bile acids using a non-absorbable apical sodium-dependent bile acid transporter inhibitor (ASBTi; SC-435) reduced the development of NAFLD in high fat diet fed mice. However, the ability of ASBTi treatment to impact the progression of NAFLD to non-alcoholic steatohepatitis (NASH) and fibrosis in a diet-induced mouse model remains untested. In the current study, we assessed whether ASBTi treatment is hepatoprotective in the choline-deficient, L-amino acid-defined (CDAA) diet model of NASH-induced fibrosis. Methods: Male C57Bl/6 mice were fed with: (A) choline-sufficient L-amino acid-defined diet (CSAA) (31 kcal% fat), (B) CSAA diet plus ASBTi (SC-435; 60 ppm), (C) CDAA diet, or (D) CDAA diet plus ASBTi. Body weight and food intake were monitored. After 22 weeks on diet, liver histology, cholesterol and triglyceride levels, and gene expression were measured. Fecal bile acid and fat excretion were measured, and intestinal fat absorption was determined using the sucrose polybehenate method. Results: ASBTi treatment reduced bodyweight gain in mice fed either the CSAA or CDAA diet, and prevented the increase in liver to body weight ratio observed in CDAA-fed mice. ASBTi significantly reduced hepatic total cholesterol levels in both CSAA and CDAA-fed mice. ASBTi-associated significant reductions in hepatic triglyceride levels and histological scoring for NAFLD activity were observed in CSAA but not CDAA-fed mice. These changes correlated with measurements of intestinal fat absorption, which was significantly reduced in ASBTi-treated mice fed the CSAA (85 vs. 94%, P < 0.001) but not CDAA diet (93 vs. 93%). As scored by Ishak staging of Sirius red stained liver sections, no hepatic fibrosis was evident in the CSAA diet mice. The CDAA diet-fed mice developed hepatic fibrosis, which was increased by the ASBTi. Conclusions: ASBT inhibition reduced intestinal fat absorption, bodyweight gain and hepatic steatosis in CSAA diet-fed mice. The effects of the ASBTi on steatosis and fat absorption were attenuated in the context of dietary choline-deficiency. Inhibition of intestinal absorption of fatty acids may be involved in the therapeutic effects of ASBTi treatment.
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Affiliation(s)
- Anuradha Rao
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States
| | - Ivo P van de Peppel
- Section of Molecular Metabolism and Nutrition, Department of Pediatrics, University Medical Center Groningen, University of Groningen, Groningen, Netherlands
| | - Sanjeev Gumber
- Division of Pathology, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States
| | - Saul J Karpen
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States
| | - Paul A Dawson
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States
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