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Kinoo SM, Chuturgoon AA, Singh B, Nagiah S. Hepatic expression of cholesterol regulating genes favour increased circulating low-density lipoprotein in HIV infected patients with gallstone disease: a preliminary study. BMC Infect Dis 2021; 21:294. [PMID: 33757439 PMCID: PMC7986270 DOI: 10.1186/s12879-021-05977-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 03/04/2021] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND HIV endemic populations are displaying higher incidence of metabolic disorders. HIV and the standard treatment are both associated with altered lipid and cholesterol metabolism, however gallstone disease (a cholesterol related disorder) in Sub-Saharan African populations is rarely investigated. METHODS This study sought to evaluate hepatic expression of key genes in cholesterol metabolism (LDLr, HMGCR, ABCA1) and transcriptional regulators of these genes (microRNA-148a, SREBP2) in HIV positive patients on antiretroviral therapy presenting with gallstones. Liver biopsies from HIV positive patients (cases: n = 5) and HIV negative patients (controls: n = 5) were analysed for miR-148a and mRNA expression using quantitative PCR. RESULTS Circulating total cholesterol was elevated in the HIV positive group with significantly elevated LDL-c levels(3.16 ± 0.64 mmol/L) relative to uninfected controls (2.10 ± 0.74 mmol/L; p = 0.04). A scavenging receptor for LDL-c, LDLr was significantly decreased (0.18-fold) in this group, possibly contributing to higher LDL-c levels. Transcriptional regulator of LDLr, SREBP2 was also significantly lower (0.13-fold) in HIV positive patients. Regulatory microRNA, miR-148a-3p, was reduced in HIV positive patients (0.39-fold) with a concomitant increase in target ABCA1 (1.5-fold), which regulates cholesterol efflux. CONCLUSIONS Collectively these results show that HIV patients on antiretroviral therapy display altered hepatic regulation of cholesterol metabolizing genes, reducing cholesterol scavenging, and increasing cholesterol efflux.
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Affiliation(s)
- Suman Mewa Kinoo
- Department of Medical Biochemistry, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu Natal, Durban, Glenwood 4041 South Africa
- Discipline of General Surgery, School of Clinical Medicine, College of Health Science, University of KwaZulu Natal, Umbilo, Durban, 4001 South Africa
| | - Anil A. Chuturgoon
- Department of Medical Biochemistry, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu Natal, Durban, Glenwood 4041 South Africa
| | - Bugwan Singh
- Discipline of General Surgery, School of Clinical Medicine, College of Health Science, University of KwaZulu Natal, Umbilo, Durban, 4001 South Africa
| | - Savania Nagiah
- Department of Medical Biochemistry, School of Laboratory Medicine and Medical Science, College of Health Science, University of KwaZulu Natal, Durban, Glenwood 4041 South Africa
- Present address: Department of Human Biology, Medical Programme, Faculty of Health Sciences, Nelson Mandela University Missionvale Campus, Room 113, 2nd floor, Road, Salt Pan, Bethelsdorp, Port Elizabeth, 6059 South Africa
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2
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Yoo KS, Lim WT, Choi HS. Biology of Cholangiocytes: From Bench to Bedside. Gut Liver 2017; 10:687-98. [PMID: 27563020 PMCID: PMC5003190 DOI: 10.5009/gnl16033] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 02/14/2016] [Accepted: 03/09/2016] [Indexed: 12/11/2022] Open
Abstract
Cholangiocytes, the lining epithelial cells in bile ducts, are an important subset of liver cells. They are activated by endogenous and exogenous stimuli and are involved in the modification of bile volume and composition. They are also involved in damaging and repairing the liver. Cholangiocytes have many functions including bile production. They are also involved in transport processes that regulate the volume and composition of bile. Cholangiocytes undergo proliferation and cell death under a variety of conditions. Cholangiocytes have functional and morphological heterogenecity. The immunobiology of cholangiocytes is important, particularly for understanding biliary disease. Secretion of different proinflammatory mediators, cytokines, and chemokines suggests the major role that cholangiocytes play in inflammatory reactions. Furthermore, paracrine secretion of growth factors and peptides mediates extensive cross-talk with other liver cells, including hepatocytes, stellate cells, stem cells, subepithelial myofibroblasts, endothelial cells, and inflammatory cells. Cholangiopathy refers to a category of chronic liver diseases whose primary disease target is the cholangiocyte. Cholangiopathy usually results in end-stage liver disease requiring liver transplant. We summarize the biology of cholangiocytes and redefine the concept of cholangiopathy. We also discuss the recent progress that has been made in understanding the pathogenesis of cholangiopathy and how such progress has influenced therapy.
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Affiliation(s)
- Kyo-Sang Yoo
- Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea
| | - Woo Taek Lim
- Korea University School of Medicine, Seoul, Korea
| | - Ho Soon Choi
- Department of Internal Medicine, Hanyang University College of Medicine, Seoul, Korea
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3
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Castella B, Kopecka J, Sciancalepore P, Mandili G, Foglietta M, Mitro N, Caruso D, Novelli F, Riganti C, Massaia M. The ATP-binding cassette transporter A1 regulates phosphoantigen release and Vγ9Vδ2 T cell activation by dendritic cells. Nat Commun 2017; 8:15663. [PMID: 28580927 PMCID: PMC5465356 DOI: 10.1038/ncomms15663] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 04/19/2017] [Indexed: 12/21/2022] Open
Abstract
Vγ9Vδ2 T cells are activated by phosphoantigens, such as isopentenyl pyrophosphate (IPP), which is generated in the mevalonate pathway of antigen-presenting cells. IPP is released in the extracellular microenvironment via unknown mechanisms. Here we show that the ATP-binding cassette transporter A1 (ABCA1) mediates extracellular IPP release from dendritic cells (DC) in cooperation with apolipoprotein A-I (apoA-I) and butyrophilin-3A1. IPP concentrations in the supernatants are sufficient to induce Vγ9Vδ2 T cell proliferation after DC mevalonate pathway inhibition with zoledronic acid (ZA). ZA treatment increases ABCA1 and apoA-I expression via IPP-dependent LXRα nuclear translocation and PI3K/Akt/mTOR pathway inhibition. These results close the mechanistic gap in our understanding of extracellular IPP release from DC and provide a framework to fine-tune Vγ9Vδ2 T cell activation via mevalonate and PI3K/Akt/mTOR pathway modulation. γδT cells are activated by phosphoantigens, and ABCA1 is involved in cholesterol transport. Here the authors link these ideas to show that ABCA1, apoA-I and BTN3A1 regulate extracellular phosphoantigen release by dendritic cells, and implicate ABCA1 in mevalonate-mediated activation of Vγ9Vδ2 T cells.
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Affiliation(s)
- Barbara Castella
- Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Università degli Studi di Torino, Via Nizza 52, Torino 10126, Italy.,Centro di Ricerca in Medicina Sperimentale (CeRMS), AOU Città della Salute e della Scienza di Torino, Via Santena 5, Torino 10126, Italy
| | - Joanna Kopecka
- Dipartimento di Oncologia, Università degli Studi di Torino, Via Santena 5/bis, Torino 10126, Italy
| | - Patrizia Sciancalepore
- Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Università degli Studi di Torino, Via Nizza 52, Torino 10126, Italy.,Centro di Ricerca in Medicina Sperimentale (CeRMS), AOU Città della Salute e della Scienza di Torino, Via Santena 5, Torino 10126, Italy
| | - Giorgia Mandili
- Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Università degli Studi di Torino, Via Nizza 52, Torino 10126, Italy.,Centro Interdipartimentale di Ricerca per le Biotecnologie Molecolari (CIRBM), Via Nizza 52, Torino 10126, Italy
| | - Myriam Foglietta
- Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Università degli Studi di Torino, Via Nizza 52, Torino 10126, Italy.,Centro di Ricerca in Medicina Sperimentale (CeRMS), AOU Città della Salute e della Scienza di Torino, Via Santena 5, Torino 10126, Italy
| | - Nico Mitro
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, Milano 20133, Italy
| | - Donatella Caruso
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Via Balzaretti 9, Milano 20133, Italy
| | - Francesco Novelli
- Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Università degli Studi di Torino, Via Nizza 52, Torino 10126, Italy.,Centro Interdipartimentale di Ricerca per le Biotecnologie Molecolari (CIRBM), Via Nizza 52, Torino 10126, Italy
| | - Chiara Riganti
- Centro di Ricerca in Medicina Sperimentale (CeRMS), AOU Città della Salute e della Scienza di Torino, Via Santena 5, Torino 10126, Italy.,Dipartimento di Oncologia, Università degli Studi di Torino, Via Santena 5/bis, Torino 10126, Italy
| | - Massimo Massaia
- Dipartimento di Biotecnologie Molecolari e Scienze della Salute, Università degli Studi di Torino, Via Nizza 52, Torino 10126, Italy.,Centro di Ricerca in Medicina Sperimentale (CeRMS), AOU Città della Salute e della Scienza di Torino, Via Santena 5, Torino 10126, Italy.,Centro Interdipartimentale di Ricerca per le Biotecnologie Molecolari (CIRBM), Via Nizza 52, Torino 10126, Italy.,SC. Ematologia, AO S. Croce e Carle, Via Michele Coppino 26, Cuneo 12100, Italy
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4
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Housset C, Chrétien Y, Debray D, Chignard N. Functions of the Gallbladder. Compr Physiol 2016; 6:1549-77. [PMID: 27347902 DOI: 10.1002/cphy.c150050] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The gallbladder stores and concentrates bile between meals. Gallbladder motor function is regulated by bile acids via the membrane bile acid receptor, TGR5, and by neurohormonal signals linked to digestion, for example, cholecystokinin and FGF15/19 intestinal hormones, which trigger gallbladder emptying and refilling, respectively. The cycle of gallbladder filling and emptying controls the flow of bile into the intestine and thereby the enterohepatic circulation of bile acids. The gallbladder also largely contributes to the regulation of bile composition by unique absorptive and secretory capacities. The gallbladder epithelium secretes bicarbonate and mucins, which both provide cytoprotection against bile acids. The reversal of fluid transport from absorption to secretion occurs together with bicarbonate secretion after feeding, predominantly in response to an adenosine 3',5'-cyclic monophosphate (cAMP)-dependent pathway triggered by neurohormonal factors, such as vasoactive intestinal peptide. Mucin secretion in the gallbladder is stimulated predominantly by calcium-dependent pathways that are activated by ATP present in bile, and bile acids. The gallbladder epithelium has the capacity to absorb cholesterol and provides a cholecystohepatic shunt pathway for bile acids. Changes in gallbladder motor function not only can contribute to gallstone disease, but also subserve protective functions in multiple pathological settings through the sequestration of bile acids and changes in the bile acid composition. Cholecystectomy increases the enterohepatic recirculation rates of bile acids leading to metabolic effects and an increased risk of nonalcoholic fatty liver disease, cirrhosis, and small-intestine carcinoid, independently of cholelithiasis. Among subjects with gallstones, cholecystectomy remains a priority in those at risk of gallbladder cancer, while others could benefit from gallbladder-preserving strategies. © 2016 American Physiological Society. Compr Physiol 6:1549-1577, 2016.
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Affiliation(s)
- Chantal Housset
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Centre de Référence Maladies Rares (CMR) des Maladies Inflammatoires des Voies Biliaires (MIVB), Service d'Hépatologie, Paris, France
| | - Yues Chrétien
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Saint-Antoine, Centre de Référence Maladies Rares (CMR) des Maladies Inflammatoires des Voies Biliaires (MIVB), Service d'Hépatologie, Paris, France
| | - Dominique Debray
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France.,Assistance Publique-Hôpitaux de Paris, Hôpital Necker Enfants Malades, Medical-Surgical Center, Hepatology and Transplantation, Paris, France
| | - Nicolas Chignard
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, UMR_S 938, Centre de Recherche Saint-Antoine, Institute of Cardiometabolism and Nutrition (ICAN), Paris, France
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5
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Chen Y, Kong J, Wu S. Cholesterol gallstone disease: focusing on the role of gallbladder. J Transl Med 2015; 95:124-31. [PMID: 25502177 DOI: 10.1038/labinvest.2014.140] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Revised: 10/11/2014] [Accepted: 10/15/2014] [Indexed: 02/06/2023] Open
Abstract
Gallstone disease (GSD) is one of the most common biliary tract diseases worldwide in which both genetic and environmental factors have roles in its pathogenesis. Biliary cholesterol supersaturation from metabolic defects in the liver is traditionally seen as the main pathogenic factor. Recently, there have been renewed investigative interests in the downstream events that occur in gallbladder lithogenesis. This article focuses on the role of the gallbladder in the pathogenesis of cholesterol GSD (CGD). Various conditions affecting the crystallization process are discussed, such as gallbladder motility, concentrating function, lipid transport, and an imbalance between pro-nucleating and nucleation inhibiting proteins.
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Affiliation(s)
- Yongsheng Chen
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Jing Kong
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
| | - Shuodong Wu
- Department of General Surgery, Shengjing Hospital of China Medical University, Shenyang, China
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6
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Dikkers A, Tietge UJF. The neglected cousin of the hepatocyte: how gallbladder epithelial cells might contribute to cholesterol gallstone formation. Dig Dis Sci 2013; 58:296-8. [PMID: 23371007 DOI: 10.1007/s10620-012-2541-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 12/19/2012] [Indexed: 12/09/2022]
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7
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Yoon JH, Choi HS, Jun DW, Yoo KS, Lee J, Yang SY, Kuver R. ATP-binding cassette sterol transporters are differentially expressed in normal and diseased human gallbladder. Dig Dis Sci 2013. [PMID: 23179156 DOI: 10.1007/s10620-012-2481-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND AND AIMS Gallbladder epithelial cells (GBEC) are exposed to high cholesterol concentrations in bile, and export cholesterol via an ATP-binding cassette (ABC) transporter-mediated pathway in vitro. These findings suggest that aberrant expression and/or function of ABC sterol transporters may be associated with cholesterol-related gallbladder diseases (CAGD). In this study, we investigated the relative levels of the sterol transporters ABCA1, ABCG5, and ABCG8 in human gallbladders in CAGD, and the relationship between ABCA1 and inflammation. METHODS Expression of ABCA1, ABCG5, and ABCG8 was evaluated in 31 gallbladders with CAGD and 6 normal gallbladders by western blotting and immunohistochemistry. RT-PCR was used to measure ABCA1 mRNA expression. To investigate the relationship between ABCA1 and inflammation, wWestern blots were performed on cultured dog GBEC treated with lipopolysaccharide (LPS) using an anti-ABCA1 antibody. RESULTS Immunohistochemistry showed ABCA1 to be localized predominantly to the basolateral membrane, while ABCG8 formed a diffuse intracellular pattern at the apical pole of human GBEC. ABCA1 and ABCG8 expression was more prominent in GBEC that were surrounded by cholesterol-laden macrophages. ABCA1 and ABCG8 expression was increased in gallbladders with CAGD. Western blots showed increased ABCA1, ABCG5, and ABCG8 expression in CAGD. ABCA1 mRNA levels were increased in all gallbladders with CAGD. LPS treatment of cultured dog GBEC enhanced ABCA1 expression. CONCLUSIONS The sterol transporters ABCA1, ABCG5, and ABCG8 may play a role in the pathogenesis of human CAGD. Inflammation appears to be a key factor that increases ABCA1 expression and activity in the human gallbladder.
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Affiliation(s)
- Jai Hoon Yoon
- Department of Internal Medicine, Hallym University College of Medicine, Chucheon, Korea
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8
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Stukas S, May S, Wilkinson A, Chan J, Donkin J, Wellington CL. The LXR agonist GW3965 increases apoA-I protein levels in the central nervous system independent of ABCA1. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:536-46. [PMID: 21889608 DOI: 10.1016/j.bbalip.2011.08.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Revised: 07/29/2011] [Accepted: 08/05/2011] [Indexed: 01/09/2023]
Abstract
Lipoprotein metabolism in the central nervous system (CNS) is based on high-density lipoprotein-like particles that use apoE as their predominant apolipoprotein rather than apoA-I. Although apoA-I is not expressed in astrocytes and microglia, which produce CNS apoE, apoA-I is reported to be expressed in porcine brain capillary endothelial cells and also crosses the blood-brain barrier (BBB). These mechanisms allow apoA-I to reach concentrations in cerebrospinal fluid (CSF) that are approximately 0.5% of its plasma levels. Recently, apoA-I has been shown to enhance cognitive function and reduce cerebrovascular amyloid deposition in Alzheimer's Disease (AD) mice, raising questions about the regulation and function of apoA-I in the CNS. Peripheral apoA-I metabolism is highly influenced by ABCA1, but less is known about how ABCA1 regulates CNS apoA-I. We report that ABCA1 deficiency leads to greater retention of apoA-I in the CNS than in the periphery. Additionally, treatment of symptomatic AD mice with GW3965, an LXR agonist that stimulates ABCA1 expression, increases apoA-I more dramatically in the CNS compared to the periphery. Furthermore, GW3965-mediated up-regulation of CNS apoA-I is independent of ABCA1. Our results suggest that apoA-I may be regulated by distinct mechanisms on either side of the BBB and that apoA-I may serve to integrate peripheral and CNS lipid metabolism. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Sophie Stukas
- Department of Pathology and Laboratory Medicine, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada V5Z 4H4
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9
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Dong SH, Lee J, Koh DH, Choi MH, Jang HJ, Kae SH. Pravastatin activates PPARalpha/PPARgamma expression in the liver and gallbladder epithelium of hamsters. Hepatobiliary Pancreat Dis Int 2011; 10:185-90. [PMID: 21459726 DOI: 10.1016/s1499-3872(11)60029-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Our earlier study with cultured gallbladder epithelial cells demonstrated that statins (HMG-CoA reductase inhibitors) activate the expression of PPARalpha and PPARgamma, consequently blocking the production of pro-inflmmatory cytokines. The present study used hamsters to investigate the effects of pavastatin on PPARalpha/PPARgamma expression in the liver and gallbladder epithelium, and to determine whether pravastatin suppresses cholesterol crystal formation in the gallbladder. METHODS A total of 40 Golden Syrian male hamsters (4 weeks old) were randomly assigned to four groups (basal diet control; basal diet+pavastatin; high cholesterol diet; high cholesterol diet+pravastatin). All hamsters were 11 weeks old at the end of the experiment. The liver, gallbladder and bile were harvested. Immunohistochemical staining and Western blotting for PPARalpha and PPARgamma were performed in the liver and gallbladder. A drop of fresh bile was examined for cholesterol crystals under a microscope. RESULTS In the gallbladder and liver of the hamsters, pravastatin activated the PPARalpha and PPARgamma expression of gallbladder epithelial cells and hepatocytes, and particularly the response of PPARgamma was much stronger than that of PPARalpha. Pravastatin suppressed the formation of cholesterol gallstones or crystals in the gallbladder. CONCLUSION Pravastatin is an effective medication to activate PPARs (especially PPARgamma) in the liver and the gallbladder epithelium of hamsters, and contributes to the prevention of gallstone formation.
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Affiliation(s)
- Seok Ho Dong
- Division of Gastroenterology, Department of Internal Medicine, Kyung Hee University College of Medicine, Seoul, Republic of Korea
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10
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Lee BJ, Kim JS, Kim BK, Jung SJ, Joo MK, Hong SG, Kim JS, Kim JH, Yeon JE, Park JJ, Byun KS, Bak YT, Yoo HS, Oh S. Effects of sphingolipid synthesis inhibition on cholesterol gallstone formation in C57BL/6J mice. J Gastroenterol Hepatol 2010; 25:1105-10. [PMID: 20594226 DOI: 10.1111/j.1440-1746.2010.06246.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
BACKGROUND Sphingolipids play a very important role in cell membrane formation, signal transduction and plasma lipoprotein metabolism. The first rate-limiting step in the sphingolipid biosynthetic pathway is catalyzed by serine palmitoyltransferase (SPT), and myriocin is a potent and specific inhibitor of SPT. We investigated the impact of SPT inhibition on cholesterol gallstone formation in C57BL/6J mice. METHODS Three groups of eight-week-old C57BL/6J mice were utilized. Each group consisted of 20 mice; group A, B, and C were fed normal chow, lithogenic diet with phosphate buffered saline, and lithogenic diet with myriocin (0.3 mg/kg), respectively, for 6 weeks. The ceramide levels in both serum and bile were assessed by high performance liquid chromatography analysis. Protein expression of ERK, JNK and p38 in the extracted gallbladder were determined by Western-blot analysis. RESULTS Myriocin treatment caused a significant decrease in the rate of cholesterol gallstone formation. The lithogenic diet mice (group B) showed the highest ceramide activities in both the serum and bile among all the tested groups and there was significant suppression of the ceramide levels in both the serum and bile of the myriocin-treated mice (group C, p < 0.05). Phosphorylation of p38 in the gallbladder was increased in the lithogenic-diet mice and the expression of phosphorylated p38 was significantly suppressed in the myriocin treated mice. CONCLUSIONS SPT inhibition by myriocin suppressed gallstone formation and the levels of ceramide in both the serum and bile. p38 in the cellular signaling pathways might be associated with cholesterol gallstone formation.
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Affiliation(s)
- Beom Jae Lee
- Department of Internal Medicine, Korea University College of Medicine, Seoul, Korea
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11
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Lee J, Hong EM, Koh DH, Choi MH, Jang HJ, Kae SH, Choi HS. HMG-CoA reductase inhibitors (statins) activate expression of PPARalpha/PPARgamma and ABCA1 in cultured gallbladder epithelial cells. Dig Dis Sci 2010; 55:292-9. [PMID: 19225884 DOI: 10.1007/s10620-009-0734-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 01/16/2009] [Indexed: 02/08/2023]
Abstract
In gallbladder epithelial cells (GBEC), PPARalpha and PPARgamma ligands modulate inflammation by suppression of TNFalpha production and prevent excessive accumulation of cholesterol by ABCA1 activation. Recently, HMG-CoA reductase inhibitors (statins) were shown to activate PPARalpha and PPARgamma in various cells but no studies of their effects in GBEC have been conducted. The objective of this study was, therefore, to determine the effects of statins on PPAR and ABCA1 expression and the anti-inflammatory effect of statins in GBEC. Canine GBEC were cultured on Petri dishes. Expression of the proteins PPARalpha, PPARgamma, and ABCA1 was measured by western blotting analysis after treatment with simvastatin, pravastatin, NO-pravastatin, PPARalpha ligand, or PPARgamma ligand in the culture media. Expression of ABCA1 and LXRalpha mRNAs was estimated by RT-PCR. Expression of TNFalpha mRNA was measured by RT-PCR after 24 h pre-treatment with the statins, preceding 1 h of lipopolysaccharide (LPS) loading. Simvastatin, pravastatin, and NO-pravastatin increased expression of the proteins PPARalpha, PPARgamma, and ABCA1, and expression of the mRNA of ABCA1 and LXRalpha in GBEC. Pre-treatment with simvastatin, pravastatin, and NO-pravastatin suppressed the production of TNFalpha mRNA induced by LPS. In conclusion, statins probably contribute to the preservation of GBEC function by activation of PPARalpha and PPARgamma, which have anti-inflammatory effects by suppression of pro-inflammatory cytokines, and ABCA1 activation mediated by LXRalpha, which prevents the accumulation of cholesterol in GBEC.
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Affiliation(s)
- Jin Lee
- Division of Gastroenterology, Department of Internal Medicine, College of Medicine, Hangang Sacred Heart Hospital, Hallym University, Youngdungpo-Gu, Seoul, Korea.
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12
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Hu YW, Zheng L, Wang Q. Regulation of cholesterol homeostasis by liver X receptors. Clin Chim Acta 2010; 411:617-25. [PMID: 20060389 DOI: 10.1016/j.cca.2009.12.027] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2009] [Revised: 12/21/2009] [Accepted: 12/21/2009] [Indexed: 12/13/2022]
Abstract
Cellular cholesterol levels reflect a balance between uptake, efflux, and endogenous synthesis. The sterol-responsive transcription factors liver X receptors (LXRalpha and LXRbeta) help maintain cholesterol homeostasis, not only through promotion of cholesterol efflux from peripheral tissues but also through suppression of de novo synthesis and exogenous cholesterol uptake. In this review, we summarize the important role of LXRs in regulating expression of key members that keep cholesterol levels in balance.
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Affiliation(s)
- Yan-Wei Hu
- Laboratory Medicine Center, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China
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13
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Lee J, Hong EM, Byun HW, Choi MH, Jang HJ, Eun CS, Kae SH, Choi HS. The effect of PPARalpha and PPARgamma ligands on inflammation and ABCA1 expression in cultured gallbladder epithelial cells. Dig Dis Sci 2008; 53:1707-15. [PMID: 17932758 DOI: 10.1007/s10620-007-0029-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 09/19/2007] [Indexed: 12/09/2022]
Abstract
The preservation of gallbladder function by control of inflammation and elimination of cholesterol accumulation in gallbladder epithelial cells (GBEC) could contribute to the prevention of gallstone formation and cholecystitis. Peroxisome proliferator-activated receptors (PPARs) modulate inflammation and lipid metabolism in various cells and GBEC efflux of excessive amounts of absorbed cholesterol through the ATP-binding cassette transporter A1 (ABCA1)-mediated pathway. The aim of this study was to determine whether ligands of PPARalpha and PPARgamma modulate inflammation and have an effect on ABCA1 expression in GBEC. Canine GBEC were cultured on dishes coated with collagen matrix. We performed Western blot analysis for the expression of specific protein and/or RT-PCR for the expression of specific mRNA. PPARalpha and PPARgamma expression was observed and increased in GBEC treated with WY-14643 (PPARalpha ligand), troglitazone (PPARgamma ligand), and lipopolysaccharide (LPS) compared to the no-treatment control and PPARalpha( antagonist (GW-9662) treatment group. WY-14643, troglitazone, and LPS also induced an increase in the expression of ABCA1 protein and mRNA in cultured GBEC. LPS-induced TNFalpha mRNA expression was suppressed by pretreatment with WY-14643 and troglitazone preceding LPS treatment in GBEC. PPAR ligands, especially PPARgamma, may preserve gallbladder function by suppression of inflammatory reaction and prevention of cholesterol accumulation in GBEC, contributing to the prevention of gallstone formation and progression to cholecystitis.
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Affiliation(s)
- Jin Lee
- Division of Gastroenterology, Department of Internal Medicine, Hallym University Hangang Sacred Heart Hospital, 94-200, Youngdungpo-Dong, Youngdungpo-Gu, Seoul 150-030, South Korea.
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14
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Sato M, Kawata Y, Erami K, Ikeda I, Imaizumi K. LXR Agonist Increases the Lymph HDL Transport in Rats by Promoting Reciprocally Intestinal ABCA1 and apo A-I mRNA Levels. Lipids 2007; 43:125-31. [DOI: 10.1007/s11745-007-3131-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 10/23/2007] [Indexed: 10/22/2022]
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15
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Lyons MA, Wittenburg H. Cholesterol gallstone susceptibility loci: a mouse map, candidate gene evaluation, and guide to human LITH genes. Gastroenterology 2006; 131:1943-70. [PMID: 17087948 DOI: 10.1053/j.gastro.2006.10.024] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2006] [Accepted: 08/15/2006] [Indexed: 12/11/2022]
Affiliation(s)
- Malcolm A Lyons
- Centre for Medical Research, University of Western Australia, Western Australian Institute for Medical Research, Perth, Australia.
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16
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17
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Panzenboeck U, Kratzer I, Sovic A, Wintersperger A, Bernhart E, Hammer A, Malle E, Sattler W. Regulatory effects of synthetic liver X receptor- and peroxisome-proliferator activated receptor agonists on sterol transport pathways in polarized cerebrovascular endothelial cells. Int J Biochem Cell Biol 2006; 38:1314-29. [PMID: 16530456 DOI: 10.1016/j.biocel.2006.01.013] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2005] [Revised: 12/20/2005] [Accepted: 01/17/2006] [Indexed: 01/03/2023]
Abstract
The blood-brain barrier contributes to maintain brain cholesterol metabolism and protects this uniquely balanced system from exchange with plasma lipoprotein cholesterol. Brain capillary endothelial cells, representing a physiological barrier to the central nervous system, express apolipoprotein A-I (apoA-I, the major high-density lipoprotein (HDL)-associated apolipoprotein), ATP-binding cassette transporter A1 (ABCA1), and scavenger receptor, class B, type I (SR-BI), proteins that promote cellular cholesterol mobilization. Liver X receptors (LXRs) and peroxisome-proliferator activated receptors (PPARs) are regulators of cholesterol transport, and activation of LXRs and PPARs has potential therapeutic implications for lipid-related neurodegenerative diseases. To clarify the functional impact of LXR/PPAR activation, sterol transport along the: (i) ABCA1/apoA-I and (ii) SR-BI/HDL pathway was investigated in primary, polarized brain capillary endothelial cells, an in vitro model of the blood-brain barrier. Activation of LXR (24(S)OH-cholesterol, TO901317), PPARalpha (bezafibrate, fenofibrate), and PPARgamma (troglitazone, pioglitazone) modulated expression of apoA-I, ABCA1, and SR-BI on mRNA and/or protein levels without compromising transendothelial electrical resistance or tight junction protein expression. LXR-agonists and troglitazone enhanced basolateral-to-apical cholesterol mobilization in the absence of exogenous sterol acceptors. Along with the induction of cell surface-located ABCA1, several agonists enhanced cholesterol mobilization in the presence of exogenous apoA-I, while efflux of 24(S)OH-cholesterol (the major brain cholesterol metabolite) in the presence of exogenous HDL remained unaffected. Summarizing, in cerebrovascular endothelial cells apoA-I, ABCA1, and SR-BI represent drug targets for LXR and PPAR-agonists to interfere with cholesterol homeostasis at the periphery of the central nervous system.
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MESH Headings
- ATP Binding Cassette Transporter 1
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Animals
- Apolipoprotein A-I/genetics
- Apolipoprotein A-I/metabolism
- Biological Transport/drug effects
- Biological Transport/physiology
- Cell Polarity/physiology
- Cells, Cultured
- Clofibric Acid/chemical synthesis
- Clofibric Acid/pharmacology
- DNA-Binding Proteins/agonists
- DNA-Binding Proteins/metabolism
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Immunoblotting
- Lipoproteins, HDL/metabolism
- Lipoproteins, HDL3
- Liver X Receptors
- Microscopy, Fluorescence
- Models, Biological
- Orphan Nuclear Receptors
- Peroxisome Proliferator-Activated Receptors/agonists
- Peroxisome Proliferator-Activated Receptors/metabolism
- Pioglitazone
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Cytoplasmic and Nuclear/agonists
- Receptors, Cytoplasmic and Nuclear/metabolism
- Scavenger Receptors, Class B/genetics
- Scavenger Receptors, Class B/metabolism
- Signal Transduction/drug effects
- Sterols/chemistry
- Sterols/metabolism
- Swine
- Thiazolidinediones/chemical synthesis
- Thiazolidinediones/pharmacology
- Transcription, Genetic/drug effects
- Transcription, Genetic/genetics
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Affiliation(s)
- Ute Panzenboeck
- Medical University Graz, Center of Molecular Medicine, Institute of Molecular Biology and Biochemistry, Harrachgasse 21, A-8010 Graz, Austria.
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18
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Oram JF, Heinecke JW. ATP-binding cassette transporter A1: a cell cholesterol exporter that protects against cardiovascular disease. Physiol Rev 2005; 85:1343-72. [PMID: 16183915 DOI: 10.1152/physrev.00005.2005] [Citation(s) in RCA: 378] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Blood high-density lipoprotein (HDL) levels are inversely related to risk for cardiovascular disease, implying that factors associated with HDL metabolism are atheroprotective. One of these factors is ATP-binding cassette transporter A1 (ABCA1), a cell membrane protein that mediates the transport of cholesterol, phospholipids, and other metabolites from cells to lipid-depleted HDL apolipoproteins. ABCA1 transcription is highly induced by sterols, a major substrate for cellular export, and its expression and activity are regulated posttranscriptionally by diverse processes. Liver ABCA1 initiates formation of HDL particles, and macrophage ABCA1 protects arteries from developing atherosclerotic lesions. ABCA1 mutations can cause a severe HDL deficiency syndrome characterized by cholesterol deposition in tissue macrophages and prevalent atherosclerosis. Genetic manipulations of ABCA1 expression in mice also affect plasma HDL levels and atherogenesis. Metabolites elevated in individuals with the metabolic syndrome and diabetes destabilize ABCA1 protein and decrease cholesterol export from macrophages. Moreover, oxidative modifications of HDL found in patients with cardiovascular disease reduce the ability of apolipoproteins to remove cellular cholesterol by the ABCA1 pathway. These observations raise the possibility that an impaired ABCA1 pathway contributes to the enhanced atherogenesis associated with common inflammatory and metabolic disorders. The ABCA1 pathway has therefore become an important new therapeutic target for treating cardiovascular disease.
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Affiliation(s)
- John F Oram
- Department of Medicine, University of Washington, Seattle, WA 98195-6426, USA.
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19
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Gentili C, Tutolo G, Pianezzi A, Cancedda R, Descalzi Cancedda F. Cholesterol secretion and homeostasis in chondrocytes: a liver X receptor and retinoid X receptor heterodimer mediates apolipoprotein A1 expression. Matrix Biol 2005; 24:35-44. [PMID: 15749000 DOI: 10.1016/j.matbio.2004.12.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2004] [Revised: 12/14/2004] [Accepted: 12/14/2004] [Indexed: 11/17/2022]
Abstract
Cholesterol is required for chondrocyte differentiation and bone formation. Apolipoprotein A1 (apoA-1) plays a major role in lipoprotein clearance and cholesterol redistribution. We report here that apoA-1 is expressed during chondrocyte differentiation in vitro and in vivo. In differentiating chondrocytes, the expression of the liver X receptor (LXR) is modulated and its expression correlates to the expression of apoA-1. The expression of other LXR target genes related to cholesterol homeostasis such as ABCA1 cholesterol transporter and sterol regulatory element-binding protein 1 (SREBP1) is similarly regulated. Small molecule ligands activating either LXR or retinoid X receptor (RXR) lead to a dramatic increase in apoA-1 mRNA and protein expression in cultured chondrocytes. These ligands strongly induce ABCA1 cholesterol transporter expression and effectively mediate cholesterol efflux from hypertrophic chondrocytes. In addition, we report that, in the same cells, the ligands down modulate Serum Amyloid A expression induced by bacterial lipopolysaccharide. Our studies provide evidence that LXR/RXR mediate a fine regulation of cholesterol homeostasis in differentiating chondrocytes.
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Affiliation(s)
- C Gentili
- Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy
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20
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Erranz B, Miquel JF, Argraves WS, Barth JL, Pimentel F, Marzolo MP. Megalin and cubilin expression in gallbladder epithelium and regulation by bile acids. J Lipid Res 2004; 45:2185-98. [PMID: 15375181 DOI: 10.1194/jlr.m400235-jlr200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Cholesterol crystal formation in the gallbladder is a key step in gallstone pathogenesis. Gallbladder epithelial cells might prevent luminal gallstone formation through a poorly understood cholesterol absorption process. Genetic studies in mice have highlighted potential gallstone susceptibility alleles, Lith genes, which include the gene for megalin. Megalin, in conjunction with the large peripheral membrane protein cubilin, mediates the endocytosis of numerous ligands, including HDL/apolipoprotein A-I (apoA-I). Although the bile contains apoA-I and several cholesterol-binding megalin ligands, the expression of megalin and cubilin in the gallbladder has not been investigated. Here, we show that both proteins are expressed by human and mouse gallbladder epithelia. In vitro studies using a megalin-expressing cell line showed that lithocholic acid strongly inhibits and cholic and chenodeoxycholic acids increase megalin expression. The effects of bile acids (BAs) were also demonstrated in vivo, analyzing gallbladder levels of megalin and cubilin from mice fed with different BAs. The BA effects could be mediated by the farnesoid X receptor, expressed in the gallbladder. Megalin protein was also strongly increased after feeding a lithogenic diet. These results indicate a physiological role for megalin and cubilin in the gallbladder and provide support for a role for megalin in gallstone pathogenesis.
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Affiliation(s)
- Benjamín Erranz
- Center for Cell Regulation and Pathology "Joaquin V. Luco", Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, and Instituto Milenio de Biología Fundamental y Aplicada, Santiago, Chile
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