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Dyslipidemia in Transplant Patients: Which Therapy? J Clin Med 2022; 11:jcm11144080. [PMID: 35887846 PMCID: PMC9318180 DOI: 10.3390/jcm11144080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/11/2022] [Accepted: 07/11/2022] [Indexed: 12/17/2022] Open
Abstract
Cardiovascular disease is the most important cause of death worldwide in recent years; an increasing trend is also shown in organ transplant patients subjected to immunosuppressive therapies, in which cardiovascular diseases represent one of the most frequent causes of long-term mortality. This is also linked to immunosuppressant-induced dyslipidemia, which occurs in 27 to 71% of organ transplant recipients. The aim of this review is to clarify the pathophysiological mechanisms underlying dyslipidemia in patients treated with immunosuppressants to identify immunosuppressive therapies which do not cause dyslipidemia or therapeutic pathways effective in reducing hypercholesterolemia, hypertriglyceridemia, or both, without further adverse events.
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Cuomo G, Cioffi G, Di Lorenzo A, Iannone FP, Cudemo G, Iannicelli AM, Pacileo M, D’Andrea A, Vigorito C, Iannuzzo G, Giallauria F. Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors Use for Atherogenic Dyslipidemia in Solid Organ Transplant Patients. J Clin Med 2022; 11:jcm11113247. [PMID: 35683632 PMCID: PMC9180971 DOI: 10.3390/jcm11113247] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/03/2022] [Accepted: 06/04/2022] [Indexed: 01/27/2023] Open
Abstract
Dyslipidemia is a widespread risk factor in solid organ transplant patients, due to many reasons, such as the use of immunosuppressive drugs, with a consequent increase in cardiovascular diseases in this population. PCSK9 is an enzyme mainly known for its role in altering LDL levels, consequently increasing cardiovascular risk. Monoclonal antibody PCSK9 inhibitors demonstrated remarkable efficacy in the general population in reducing LDL cholesterol levels and preventing cardiovascular disease. In transplant patients, these drugs are still poorly used, despite having comparable efficacy to the general population and giving fewer drug interactions with immunosuppressants. Furthermore, there is enough evidence that PCSK9 also plays a role in other pathways, such as inflammation, which is particularly dangerous for graft survival. In this review, the current evidence on the function of PCSK9 and the use of its inhibitors will be discussed, particularly in transplant patients, in which they may provide additional benefits.
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Affiliation(s)
- Gianluigi Cuomo
- Department of Translational Medical Sciences, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (G.C.); (G.C.); (A.D.L.); (G.C.); (A.M.I.); (C.V.)
| | - Giuseppe Cioffi
- Department of Translational Medical Sciences, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (G.C.); (G.C.); (A.D.L.); (G.C.); (A.M.I.); (C.V.)
| | - Anna Di Lorenzo
- Department of Translational Medical Sciences, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (G.C.); (G.C.); (A.D.L.); (G.C.); (A.M.I.); (C.V.)
| | - Francesca Paola Iannone
- Department of Clinical Medicine and Surgery, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (F.P.I.); (G.I.)
| | - Giuseppe Cudemo
- Department of Translational Medical Sciences, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (G.C.); (G.C.); (A.D.L.); (G.C.); (A.M.I.); (C.V.)
| | - Anna Maria Iannicelli
- Department of Translational Medical Sciences, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (G.C.); (G.C.); (A.D.L.); (G.C.); (A.M.I.); (C.V.)
| | - Mario Pacileo
- Unit of Cardiology and Intensive Care, Umberto I Hospital, 84014 Nocera Inferiore, Italy; (M.P.); (A.D.)
| | - Antonello D’Andrea
- Unit of Cardiology and Intensive Care, Umberto I Hospital, 84014 Nocera Inferiore, Italy; (M.P.); (A.D.)
| | - Carlo Vigorito
- Department of Translational Medical Sciences, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (G.C.); (G.C.); (A.D.L.); (G.C.); (A.M.I.); (C.V.)
| | - Gabriella Iannuzzo
- Department of Clinical Medicine and Surgery, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (F.P.I.); (G.I.)
| | - Francesco Giallauria
- Department of Translational Medical Sciences, “Federico II” University of Naples, Via S. Pansini 5, 80131 Naples, Italy; (G.C.); (G.C.); (A.D.L.); (G.C.); (A.M.I.); (C.V.)
- Correspondence:
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Aziz F, Jorgenson M, Garg N, Parajuli S, Mohamed M, Raza F, Mandelbrot D, Djamali A, Dhingra R. New Approaches to Cardiovascular Disease and Its Management in Kidney Transplant Recipients. Transplantation 2022; 106:1143-1158. [PMID: 34856598 DOI: 10.1097/tp.0000000000003990] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cardiovascular events, including ischemic heart disease, heart failure, and arrhythmia, are common complications after kidney transplantation and continue to be leading causes of graft loss. Kidney transplant recipients have both traditional and transplant-specific risk factors for cardiovascular disease. In the general population, modification of cardiovascular risk factors is the best strategy to reduce cardiovascular events; however, studies evaluating the impact of risk modification strategies on cardiovascular outcomes among kidney transplant recipients are limited. Furthermore, there is only minimal guidance on appropriate cardiovascular screening and monitoring in this unique patient population. This review focuses on the limited scientific evidence that addresses cardiovascular events in kidney transplant recipients. Additionally, we focus on clinical management of specific cardiovascular entities that are more prevalent among kidney transplant recipients (ie, pulmonary hypertension, valvular diseases, diastolic dysfunction) and the use of newer evolving drug classes for treatment of heart failure within this cohort of patients. We note that there are no consensus documents describing optimal diagnostic, monitoring, or management strategies to reduce cardiovascular events after kidney transplantation; however, we outline quality initiatives and research recommendations for the assessment and management of cardiovascular-specific risk factors that could improve outcomes.
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Affiliation(s)
- Fahad Aziz
- Division of Nephrology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Margaret Jorgenson
- Department of Pharmacology, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Neetika Garg
- Division of Nephrology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Sandesh Parajuli
- Division of Nephrology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Maha Mohamed
- Division of Nephrology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Farhan Raza
- Cardiovascular Division, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Didier Mandelbrot
- Division of Nephrology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Arjang Djamali
- Division of Nephrology, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
- Division of Transplantation, Department of Surgery, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
| | - Ravi Dhingra
- Cardiovascular Division, Department of Medicine, University of Wisconsin-Madison School of Medicine and Public Health, University of Wisconsin Hospital and Clinics, Madison, WI
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Choudhary NS, Saraf N, Saigal S, Soin AS. Long-term Management of the Adult Liver Transplantation Recipients. J Clin Exp Hepatol 2021; 11:239-253. [PMID: 33746450 PMCID: PMC7953009 DOI: 10.1016/j.jceh.2020.06.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 06/14/2020] [Indexed: 12/12/2022] Open
Abstract
The survival of liver transplantation (LT) recipients has been improved remarkably in short-term. The major causes of mortality in long-term include nonimmunological causes such as cardiovascular, de novo malignancy, chronic kidney disease, and recurrence of primary disease. Rejection-related mortality is rare in the long-term after LT. We discuss nonrejection causes of long-term morbidity/mortality, risk factors, and management strategies in LT recipients. In addition, we discuss osteoporosis, contraception, and pregnancy in LT recipients.
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Key Words
- AIH, autoimmune hepatitis
- BMI, body mass index
- CKD, chronic kidney disease
- CNI, calcineurin inhibitors
- CVD, cardiovascular disease
- DDLT, deceased donor liver transplantation
- DM, diabetes mellitus
- DNM, de novo malignancy
- HCV, hepatitis C virus
- HR, hazard ratio
- IUCD, Intrauterine contraceptive devices
- LDLT, living donor liver transplantation
- LT, liver transplantation
- MDRD, Modification of Diet in Renal Disease
- MMF, mycophenolate
- MS, metabolic syndrome
- NAFLD, nonalcoholic fatty liver disease
- NASH, nonalcoholic steatohepatitis
- OR, odds ratio
- PBC, primary biliary cholangitis
- PSC, primary sclerosing cholangitis
- PTDM, posttransplantation diabetes mellitus
- PTMS, posttransplantation metabolic syndrome
- SVR, sustained virological response
- cardiovascular disease
- de novo malignancy
- eGFR, estimated glomerular filtration rate
- mTORi, Mammalian target of rapamycin inhibitors
- osteoporosis
- pregnancy
- recurrence
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Affiliation(s)
- Narendra S. Choudhary
- Institute of Liver Transplantation and Regenerative Medicine, Medanta The Medicity, Gurgaon, Delhi (NCR), India
| | - Neeraj Saraf
- Institute of Liver Transplantation and Regenerative Medicine, Medanta The Medicity, Gurgaon, Delhi (NCR), India
| | - Sanjiv Saigal
- Institute of Liver Transplantation and Regenerative Medicine, Medanta The Medicity, Gurgaon, Delhi (NCR), India
| | - Arvinder S. Soin
- Institute of Liver Transplantation and Regenerative Medicine, Medanta The Medicity, Gurgaon, Delhi (NCR), India
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Kohara H, Bajaj P, Yamanaka K, Miyawaki A, Harada K, Miyamoto K, Matsui T, Okai Y, Wagoner M, Shinozawa T. High-Throughput Screening to Evaluate Inhibition of Bile Acid Transporters Using Human Hepatocytes Isolated From Chimeric Mice. Toxicol Sci 2020; 173:347-361. [PMID: 31722436 DOI: 10.1093/toxsci/kfz229] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Cholestasis resulting from hepatic bile acid efflux transporter inhibition may contribute to drug-induced liver injury (DILI). This condition is a common safety-related reason for drug attrition and withdrawal. To screen for safety risks associated with efflux transport inhibition, we developed a high-throughput cellular assay for different drug discovery phases. Hepatocytes isolated from chimeric mice with humanized livers presented gene expression resembling that of the human liver and demonstrated apical membrane polarity when sandwiched between Matrigel and collagen. The fluorescent bile acid-derivative cholyl-l-lysyl-fluorescein (CLF) was used to quantify drug-induced efflux transport inhibition in hepatocytes. Cyclosporine inhibited CLF accumulation in the apical bile canalicular lumen in a concentration-dependent manner. The assay had equivalent predictive power to a primary human hepatocyte-based assay and greater predictive power than an assay performed with rat hepatocytes. Predictive power was tested using 45 pharmaceutical compounds, and 91.3% of the compounds with cholestatic potential (21/23) had margins (IC50/Cmax) < 20. In contrast, 90.9% (20/22) of compounds without cholestatic potential had IC50/Cmax>20. Assay sensitivity and specificity were 91.3% and 90.9%, respectively. We suggest that this improved assay performance could result from higher expression of efflux transporters, metabolic pathways, and/or species differences. Given the long-term supply of cells from the same donor, the humanized mouse-derived hepatocyte-based CLF efflux assay could be a valuable tool for predicting cholestatic DILI.
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Affiliation(s)
- Hiroshi Kohara
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
| | - Piyush Bajaj
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Cambridge, Massachusetts 02139, USA
| | - Kazunori Yamanaka
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
| | - Akimitsu Miyawaki
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
| | - Kosuke Harada
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
| | - Kazumasa Miyamoto
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
| | - Toshikatsu Matsui
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
| | - Yoshiko Okai
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
| | - Matthew Wagoner
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Cambridge, Massachusetts 02139, USA
| | - Tadahiro Shinozawa
- Drug Safety Research and Evaluation, Takeda Pharmaceutical Company Limited, Kanagawa 251-8555, Kanagawa, Japan
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Abstract
An increased risk of cardiovascular disease, independent of conventional risk factors, is present even at minor levels of renal impairment and is highest in patients with end-stage renal disease (ESRD) requiring dialysis. Renal dysfunction changes the level, composition and quality of blood lipids in favour of a more atherogenic profile. Patients with advanced chronic kidney disease (CKD) or ESRD have a characteristic lipid pattern of hypertriglyceridaemia and low HDL cholesterol levels but normal LDL cholesterol levels. In the general population, a clear relationship exists between LDL cholesterol and major atherosclerotic events. However, in patients with ESRD, LDL cholesterol shows a negative association with these outcomes at below average LDL cholesterol levels and a flat or weakly positive association with mortality at higher LDL cholesterol levels. Overall, the available data suggest that lowering of LDL cholesterol is beneficial for prevention of major atherosclerotic events in patients with CKD and in kidney transplant recipients but is not beneficial in patients requiring dialysis. The 2013 Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for Lipid Management in CKD provides simple recommendations for the management of dyslipidaemia in patients with CKD and ESRD. However, emerging data and novel lipid-lowering therapies warrant some reappraisal of these recommendations.
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Chakkera HA, Sharif A, Kaplan B. Negative Cardiovascular Consequences of Small Molecule Immunosuppressants. Clin Pharmacol Ther 2017; 102:269-276. [PMID: 28512771 DOI: 10.1002/cpt.738] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 05/05/2017] [Accepted: 05/10/2017] [Indexed: 01/04/2023]
Abstract
Immunosuppressants are critical after transplantation and prescribed as immune-modulators for autoimmune disorders and glomerulonephritides. Immunosuppressants include large (e.g., thymoglobulin, alemtuzumab, and rituximab) and small molecules (e.g., corticosteroids, calcineurin inhibitors, antimetabolites, and mammalian target of rapamycin (mTOR) inhibitors). The majority of the small molecules worsen traditional cardiovascular risks. This review describes cardiovascular risks of small molecule immunosuppressants: corticosteroids, calcineurin inhibitors (tacrolimus and cyclosporine), and mTOR inhibitors (rapamycin), by categorizing these risks into two categories: ischemic heart disease and nonischemic cardiac effects.
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Affiliation(s)
- H A Chakkera
- Division of Transplantation, Mayo Clinic, Phoenix, Arizona, USA
| | - A Sharif
- Division of Nephrology and Transplantation, Queen Elizabeth Hospital, Birmingham, United Kingdom
| | - B Kaplan
- Division of Transplantation, Mayo Clinic, Phoenix, Arizona, USA
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Agarwal A, Prasad GVR. Post-transplant dyslipidemia: Mechanisms, diagnosis and management. World J Transplant 2016; 6:125-134. [PMID: 27011910 PMCID: PMC4801788 DOI: 10.5500/wjt.v6.i1.125] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 11/26/2015] [Accepted: 02/17/2016] [Indexed: 02/05/2023] Open
Abstract
Post-transplant dyslipidemia is highly prevalent and presents unique management challenges to the clinician. The two major outcomes to consider with post-transplant therapies for dyslipidemia are preserving or improving allograft function, and reducing cardiovascular risk. Although there are other cardiovascular risk factors such as graft dysfunction, hypertension, and diabetes, attention to dyslipidemia is warranted because interventions for dyslipidemia have an impact on reducing cardiac events in clinical trials specific to the transplant population. Dyslipidemia is not synonymous with hyperlipidemia. Numerous mechanisms exist for the occurrence of post-transplant dyslipidemia, including those mediated by immunosuppressive drug therapy. Statin therapy has received the most attention in all solid organ transplant recipient populations, although the effect of proper dietary advice and adjuvant pharmacological and non-pharmacological agents should not be dismissed. At all stages of treatment appropriate monitoring strategies for side effects should be implemented so that the benefits from these therapies can be achieved. Clinicians have a choice when there is a conflict between various transplant society and lipid society guidelines for therapy and targets.
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Sharanek A, Burban A, Humbert L, Bachour-El Azzi P, Felix-Gomes N, Rainteau D, Guillouzo A. Cellular Accumulation and Toxic Effects of Bile Acids in Cyclosporine A-Treated HepaRG Hepatocytes. Toxicol Sci 2015. [DOI: 10.1093/toxsci/kfv155] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Staufer K, Halilbasic E, Trauner M, Kazemi-Shirazi L. Cystic fibrosis related liver disease--another black box in hepatology. Int J Mol Sci 2014; 15:13529-49. [PMID: 25093717 PMCID: PMC4159809 DOI: 10.3390/ijms150813529] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/10/2014] [Accepted: 07/16/2014] [Indexed: 02/07/2023] Open
Abstract
Due to improved medical care, life expectancy in patients with cystic fibrosis (CF) has veritably improved over the last decades. Importantly, cystic fibrosis related liver disease (CFLD) has become one of the leading causes of morbidity and mortality in CF patients. However, CFLD might be largely underdiagnosed and diagnostic criteria need to be refined. The underlying pathomechanisms are largely unknown, and treatment strategies with proven efficacy are lacking. This review focuses on current invasive and non-invasive diagnostic standards, the current knowledge on the pathophysiology of CFLD, treatment strategies, and possible future developments.
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Affiliation(s)
- Katharina Staufer
- Division of Transplantation, Department of Surgery, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
| | - Emina Halilbasic
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
| | - Michael Trauner
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
| | - Lili Kazemi-Shirazi
- Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria.
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Sharanek A, Azzi PBE, Al-Attrache H, Savary CC, Humbert L, Rainteau D, Guguen-Guillouzo C, Guillouzo A. Different dose-dependent mechanisms are involved in early cyclosporine a-induced cholestatic effects in hepaRG cells. Toxicol Sci 2014; 141:244-53. [PMID: 24973091 DOI: 10.1093/toxsci/kfu122] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Mechanisms involved in drug-induced cholestasis in humans remain poorly understood. Although cyclosporine A (CsA) and tacrolimus (FK506) share similar immunosuppressive properties, only CsA is known to cause dose-dependent cholestasis. Here, we have investigated the mechanisms implicated in early cholestatic effects of CsA using the differentiated human HepaRG cell line. Inhibition of efflux and uptake of taurocholate was evidenced as early as 15 min and 1 h respectively after addition of 10μM CsA; it peaked at around 2 h and was reversible. These early effects were associated with generation of oxidative stress and deregulation of cPKC pathway. At higher CsA concentrations (≥50μM) alterations of efflux and uptake activities were enhanced and became irreversible, pericanalicular F-actin microfilaments were disorganized and bile canaliculi were constricted. These changes were associated with induction of endoplasmic reticulum stress that preceded generation of oxidative stress. Concentration-dependent changes were observed on total bile acid disposition, which were characterized by an increase and a decrease in culture medium and cells, respectively, after a 24-h treatment with CsA. Accordingly, genes encoding hepatobiliary transporters and bile acid synthesis enzymes were differently deregulated depending on CsA concentration. By contrast, FK506 induced limited effects only at 25-50μM and did not alter bile canaliculi. Our data demonstrate involvement of different concentration-dependent mechanisms in CsA-induced cholestasis and point out a critical role of endoplasmic reticulum stress in the occurrence of the major cholestatic features.
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Affiliation(s)
- Ahmad Sharanek
- Inserm UMR991, Foie, Métabolisme et Cancer, Rennes, France Université de Rennes 1, Rennes, France
| | - Pamela Bachour-El Azzi
- Inserm UMR991, Foie, Métabolisme et Cancer, Rennes, France Université de Rennes 1, Rennes, France
| | - Houssein Al-Attrache
- Inserm UMR991, Foie, Métabolisme et Cancer, Rennes, France Université de Rennes 1, Rennes, France
| | - Camille C Savary
- Inserm UMR991, Foie, Métabolisme et Cancer, Rennes, France Université de Rennes 1, Rennes, France
| | - Lydie Humbert
- ERL Inserm U1157/UMR7203, Faculté de Medecine Pierre et Marie Curie, Site Saint Antoine, Paris, France
| | - Dominique Rainteau
- ERL Inserm U1157/UMR7203, Faculté de Medecine Pierre et Marie Curie, Site Saint Antoine, Paris, France
| | | | - André Guillouzo
- Inserm UMR991, Foie, Métabolisme et Cancer, Rennes, France Université de Rennes 1, Rennes, France
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Robien K, Oppeneer SJ, Kelly JA, Hamilton-Reeves JM. Drug-vitamin D interactions: a systematic review of the literature. Nutr Clin Pract 2013; 28:194-208. [PMID: 23307906 DOI: 10.1177/0884533612467824] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Extensive media coverage of the potential health benefits of vitamin D supplementation has translated into substantial increases in supplement sales over recent years. Yet, the potential for drug-vitamin D interactions is rarely considered. This systematic review of the literature was conducted to evaluate the extent to which drugs affect vitamin D status or supplementation alters drug effectiveness or toxicity in humans. Electronic databases were used to identify eligible peer-reviewed studies published through September 1, 2010. Study characteristics and findings were abstracted, and quality was assessed for each study. A total of 109 unique reports met the inclusion criteria. The majority of eligible studies were classified as class C (nonrandomized trials, case-control studies, or time series) or D (cross-sectional, trend, case report/series, or before-and-after studies). Only 2 class C and 3 class D studies were of positive quality. Insufficient evidence was available to determine whether lipase inhibitors, antimicrobial agents, antiepileptic drugs, highly active antiretroviral agents, or H2 receptor antagonists alter serum 25(OH)D concentrations. Atorvastatin appears to increase 25(OH)D concentrations, whereas concurrent vitamin D supplementation decreases concentrations of atorvastatin. Use of thiazide diuretics in combination with calcium and vitamin D supplements may cause hypercalcemia in the elderly or those with compromised renal function or hyperparathyroidism. Larger studies with stronger study designs are needed to clarify potential drug-vitamin D interactions, especially for drugs metabolized by cytochrome P450 3A4 (CYP3A4). Healthcare providers should be aware of the potential for drug-vitamin D interactions.
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Affiliation(s)
- Kim Robien
- Department of Epidemiology and Biostatistics, George Washington University School of Public Health and Health Services, Washington, DC 20037, USA.
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Einollahi B, Teimoori M, Rostami Z. Change of Cyclosporine Absorption over the Time after Kidney Transplantation. Nephrourol Mon 2012; 4:470-4. [PMID: 23573469 PMCID: PMC3614282 DOI: 10.5812/numonthly.2437] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 10/06/2011] [Accepted: 10/17/2011] [Indexed: 11/21/2022] Open
Abstract
Background Although the immunosuppressant cyclosporine (CsA) is widely used after kidney transplantation over the long term, there is still no firm consensus on the best way to monitor of CsA blood levels. Objectives Cyclosporine (CsA) assay is critical for the management of renal transplant recipients due to inter– and intra–patient variation in CsA absorption and metabolism. Patients and Methods: In a retrospective cross sectional study, blood levels of CsA (through and 2 hours post dose) measured at least 5 times during 3 years post transplantation, in 7702 kidney transplant recipients from different transplant center of Tehran, IR Iran between 2008 and 2012. Cyclosporine absorption (CA) calculated C2/C0 ratio. Results CA had a significant correlation with allograft function (P = 0.000, r =.0.285), this correlation was stronger than its relationship with C0 and C2 blood levels (P = 0.000 and P = 0.000 as well as r = 0.033 and r = 0.090, respectively). In univariate analysis during different times after transplantation, C0 and C2 blood levels significantly decreased over three years follow up (P = 0.000), (P = 0.000); While, CA reversely increases over the time (P = 0.000). In linear regression model overall CA levels had correlation with lower age of recipient (P = 0.02), hypokalemia (P = 0.001), higher level of creatinine (P = 0.02) and triglyceride (P = 0.001). Conclusions The present study shows that CsA absorption changes trough the post-transplant time and appears to increases over time in long–term period after kidney transplantation.
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Affiliation(s)
- Behzad Einollahi
- Nephrology and Urology Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR Iran
| | - Mojtaba Teimoori
- Nephrology and Urology Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR Iran
| | - Zohreh Rostami
- Nephrology and Urology Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR Iran
- Corresponding author: Zohreh Rostami, Nephrology and Urology Research Center, Baqiyatallah University of Medical Sciences, Tehran, IR Iran. Tel.: +98-81262073, Fax: +98-81262073, E-mail:
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Kockx M, Jessup W, Kritharides L. Cyclosporin A and atherosclerosis--cellular pathways in atherogenesis. Pharmacol Ther 2010; 128:106-18. [PMID: 20598751 DOI: 10.1016/j.pharmthera.2010.06.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 06/02/2010] [Indexed: 12/31/2022]
Abstract
Cyclosporin A (CsA) is an immunosuppressant drug widely used in organ transplant recipients and people with autoimmune disorders. Long term treatment with CsA is associated with many side effects including hyperlipidemia and an increased risk of atherosclerosis. While its immunosuppressive effects are closely linked to its effects on T cell activation via the inhibition of the nuclear factor of activated T cells (NFAT) pathway, the precise mechanisms underlying its cardiovascular effects appear to involve multiple pathways additional to those relevant for immunosuppression. These include inhibition of calcineurin activity and intracellular cyclophilin peptidylprolyl isomerase and chaperone activities, inhibition of pro-inflammatory extracellular cyclophilin A, and NFAT-independent transcriptional effects. CsA demonstrates complex effects on lipoprotein metabolism and bile acid production, and affects endothelial cells, smooth muscle cells and macrophages, all of which are critical to the atherosclerotic process. Interpretation of the available data is hampered as many experimental models are used to study the effects of CsA in vivo and in vitro, leading to diverse and often contradictory findings. In this review we will describe the cellular mechanisms related to CsA-induced hyperlipidemia and atherosclerosis, with a focus on identifying pro-atherogenic pathways that are distinct from those relevant to its immunosuppressant effects. The potential of CsA analogues to avoid such sequelae will be discussed.
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Affiliation(s)
- Maaike Kockx
- Macrophage Biology Group, Centre for Vascular Research, University of New South Wales, Sydney, Australia
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Kockx M, Guo DL, Traini M, Gaus K, Kay J, Wimmer-Kleikamp S, Rentero C, Burnett JR, Le Goff W, Van Eck M, Stow JL, Jessup W, Kritharides L. Cyclosporin A decreases apolipoprotein E secretion from human macrophages via a protein phosphatase 2B-dependent and ATP-binding cassette transporter A1 (ABCA1)-independent pathway. J Biol Chem 2009; 284:24144-54. [PMID: 19589783 DOI: 10.1074/jbc.m109.032615] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cyclosporin A (CsA) is an immunosuppressant that inhibits protein phosphatase 2B (PP2B/calcineurin) and is associated with hyperlipidemia, decreased cholesterol efflux via ATP-binding cassette transporter A1 (ABCA1), and increased risk of atherosclerosis. Apolipoprotein E (apoE) is an important regulator of lipid metabolism and atherosclerosis, the secretion of which from human macrophages is regulated by the serine/threonine protein kinase A (PKA) and intracellular calcium (Ca(2+)) (Kockx, M., Guo, D. L., Huby, T., Lesnik, P., Kay, J., Sabaretnam, T., Jary, E., Hill, M., Gaus, K., Chapman, J., Stow, J. L., Jessup, W., and Kritharides, L. (2007) Circ. Res. 101, 607-616). As PP2B is Ca(2+)-dependent and has been linked to PKA-dependent processes, we investigated whether CsA modulated apoE secretion. CsA dose- and time-dependently inhibited secretion of apoE from primary human macrophages and from Chinese hamster ovary cells stably transfected with human apoE and increased cellular apoE levels without affecting apoE mRNA. [(35)S]Met kinetic modeling studies showed that CsA inhibited both secretion and degradation of apoE, increasing the half-life of cellular apoE 2-fold. CsA also inhibited secretion from primary human Tangier disease macrophages and from mouse macrophages deficient in ABCA1, indicating that the effect is independent of the known inhibition of ABCA1 by CsA. The role of PP2B in mediating apoE secretion was confirmed using additional peptide and chemical inhibitors of PP2B. Importantly, kinetic modeling, live-cell imaging, and confocal microscopy all indicated that CsA inhibited apoE secretion by mechanisms quite distinct from those of PKA inhibition, most likely inducing accumulation of apoE in the endoplasmic reticulum compartment. Taken together, these results establish a novel mechanism for the pro-atherosclerotic effects of CsA, and establish for the first time a role for PP2B in regulating the intracellular transport and secretion of apoE.
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Affiliation(s)
- Maaike Kockx
- Centre for Vascular Research, School of Medical Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
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Kőhalmy K, Rozman D, Pascussi JM, Sárváry E, Monostory K. Crosstalk between cholesterol homeostasis and drug metabolism. Orv Hetil 2008; 149:1283-9. [DOI: 10.1556/oh.2008.28329] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Napjainkban a cardiovascularis megbetegedések vezető halálozási oknak számítanak világszerte. A szív- és érrendszeri megbetegedések kialakulásában jelentős szerepet játszik a magas szérumkoleszterin-szint, illetve az atherosclerosis. A vér koleszterinszintjének csökkentésével kedvezően befolyásolható a káros folyamatok kialakulása, és a már kialakult betegségekben is javulás érhető el. Az általánosan alkalmazott sztatinalapú gyógyszeres terápia ade novokoleszterin-bioszintézist gátolja a májban. Más hatóanyagok (például ezetimib) a koleszterin táplálékból történő felszívódását gátolják. A leghatékonyabb megoldást ezek kombinált alkalmazása jelentheti. A gyógyszeres terápia során azonban figyelembe kell venni, hogy számos vegyület (gyógyszer) képes specifikusan megváltoztatni – a koleszterinhomeosztázis fenntartásában szerepet játszó enzimek mellett – a gyógyszer-metabolizáló enzimek indukciójával a citokróm P450 enzimek mennyiségét is (például sztatinok), ami a terápia módosítását teszi szükségessé. A koleszterin-anyagcsere és a gyógyszer-metabolizmus szabályozásában ugyanis több kapcsolódási pont is található. A kapcsolat az úgynevezett nukleáris receptorokon keresztül valósul meg, ezért a koleszterinhomeosztázis és a gyógyszer-metabolizmus közti összefüggés megértése és ismereteink bővítése elengedhetetlen egy megfelelő terápiás stratégia kidolgozásához, illetve új gyógyszerek fejlesztéséhez.
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Affiliation(s)
- Krisztina Kőhalmy
- 1 Magyar Tudományos Akadémia, Kémiai Kutatóközpont Farmakobiokémiai Osztály Budapest Pusztaszeri út 59–67. 1025
| | | | - Jean-Marc Pascussi
- 3 Université Montpellier Institut National de la Santé et de la Recherche Médicale Montpellier Franciaország
| | - Enikő Sárváry
- 4 Semmelweis Egyetem, Általános Orvostudományi Kar Transzplantációs és Sebészeti Klinika Budapest
| | - Katalin Monostory
- 1 Magyar Tudományos Akadémia, Kémiai Kutatóközpont Farmakobiokémiai Osztály Budapest Pusztaszeri út 59–67. 1025
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Josephine A, Nithya K, Amudha G, Veena CK, Preetha SP, Varalakshmi P. Role of sulphated polysaccharides from Sargassum Wightii in Cyclosporine A-induced oxidative liver injury in rats. BMC Pharmacol 2008; 8:4. [PMID: 18289374 PMCID: PMC2291455 DOI: 10.1186/1471-2210-8-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Accepted: 02/20/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Seaweeds or marine algae have long been made up a key part of the Asian diet, and as an antioxidant, sulphated polysaccharides have piqued the interest of many researchers as one of the ocean's greatest treasures. The present investigation suggests the therapeutic potential of sulphated polysaccharides from marine brown algae "Sargassum wightii" in Cyclosporine A (CsA)- induced liver injury. CsA is a potent immunosuppressive agent used in the field of organ transplantations and various autoimmune disorders. However, hepatotoxicity due to CsA remains to be one of the major clinical challenges. METHODS The effect of sulphated polysaccharides on CsA-induced hepatotoxicity was studied in adult male albino rats of Wistar strain, and the animals were randomized into four groups with six rats in each. Group I served as vehicle control. Group II rats were given CsA at a dosage of 25 mg/kg body weight, orally for 21 days. Group III rats were given sulphated polysaccharides at a dosage of 5 mg/kg body weight, subcutaneously for 21 days. Group IV rats were given sulphated polysaccharides simultaneously along with CsA, as mentioned in Group II for 21 days. RESULTS CsA provoked hepatotoxicity was evident from the decreased activities of hepatic marker enzymes. A significant rise in the level of oxidants, along with a striking decline in both the enzymic and non-enzymic antioxidants, marks the severity of oxidative stress in CsA-induced rats. This in turn led to enhanced levels of lipid peroxidation, 8-hydroxy-2-deoxy guanosine and protein carbonyls, along with a decrease in ATPase activities and alterations in lipid profile. Histopathological changes also strongly support the above aberrations. However, concomitant treatment with sulphated polysaccharides restored the above deformities to near control and prevented the morphological alterations significantly. CONCLUSION Thus, the present study highlights that sulphated polysaccharides can act therapeutically against CsA-induced hepatotoxicity.
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Affiliation(s)
- Anthony Josephine
- Department of Medical Biochemistry, Dr. ALM. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai – 600 113, India
| | - Kalaiselvam Nithya
- Department of Medical Biochemistry, Dr. ALM. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai – 600 113, India
| | - Ganapathy Amudha
- Department of Medical Biochemistry, Dr. ALM. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai – 600 113, India
| | - Coothan Kandaswamy Veena
- Department of Medical Biochemistry, Dr. ALM. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai – 600 113, India
| | - Sreenivasan P Preetha
- Department of Medical Biochemistry, Dr. ALM. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai – 600 113, India
| | - Palaninathan Varalakshmi
- Department of Medical Biochemistry, Dr. ALM. Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai – 600 113, India
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Gueguen Y, Ferrari L, Souidi M, Batt AM, Lutton C, Siest G, Visvikis S. Compared Effect of Immunosuppressive Drugs Cyclosporine A and Rapamycin on Cholesterol Homeostasis Key Enzymes CYP27A1 and HMG-CoA Reductase. Basic Clin Pharmacol Toxicol 2007; 100:392-7. [PMID: 17516993 DOI: 10.1111/j.1742-7843.2007.00066.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hyperlipidaemia, i.e. increase in total cholesterol and triglycerides, is a common side-effect of the immunosuppressive drugs rapamycin (RAPA) and cyclosporine A (CsA), and is probably related to inhibition of the 27-hydroxylation of cholesterol (acid pathway of bile acid biosynthesis). This might be one of the causes for the increase in plasma cholesterol, as 27-hydroxycholesterol is a potent suppressor of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR), a key enzyme of cholesterol synthesis. As the sterol 27-hydroxylase (CYP27A1) inhibition by CsA is well known, we evaluated the effect of another immunosuppressive drug, RAPA, on this enzyme in HepG2 mitochondria, which confirmed the dose-dependent inhibition of mitochondrial CYP27A1 by cyclosporine (10-20 microM), while the inhibition by RAPA required a higher dose (50-100 microM). Corresponding K(i) was 10 microM for CsA (non-competitive inhibition) and 110 microM for RAPA (competitive inhibition). Cotreatment with both immunosuppressive drugs showed an additive inhibitory effect on CYP27A1 activity. Later, we analysed the effect of these immunosuppressants on HMGR expression in HepG2 cells, and a dose-dependent up-regulation of HMGR gene expression was observed. The results suggest that RAPA and CsA are both inhibitors of CYP27A1 activity with slightly different mechanisms and that they may accordingly increase HMGR expression.
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Affiliation(s)
- Yann Gueguen
- Faculty of Pharmacy 1, Nancy Universities, Institut National de la Santé et de la Recherche Médicale, INSERM U525, 30 Rue Lionnois, Nancy, France.
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Josephine A, Veena CK, Amudha G, Preetha SP, Varalakshmi P. Protective role of sulphated polysaccharides in abating the hyperlipidemic nephropathy provoked by cyclosporine A. Arch Toxicol 2007; 81:371-9. [PMID: 17019561 DOI: 10.1007/s00204-006-0151-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Accepted: 08/28/2006] [Indexed: 10/24/2022]
Abstract
Cyclosporine A (CsA)-induced nephrotoxicity hampers the immense therapeutic potential of such a powerful immunosuppressant. The present study was conducted with an aim to explicate the contribution of sulphated polysaccharides (SPS) in abating the lipid abnormalities induced by CsA in the rat kidney. Hyperlipidemia associated with nephrotic syndrome may play a role in the worsening of renal function. Male albino Wistar rats sorted into four groups were used for the study. CsA was given at a dose of 25 mg/kg body weight, orally for 21 days. Significant alterations in the lipid profile as well an increase in the activity of cholesterol ester synthase, coupled with a decrease in cholesterol ester hydrolase and lipoprotein lipase enzyme activities were noted in the plasma and kidneys of CsA-administered rats. A marked increase in the lipoprotein fractions, low-density lipoprotein (LDL) and very low density lipoprotein (VLDL), along with a decrease in the HDL level were found in CsA-administered rats. The degree of nephrotoxicity allied with lipid discrepancies was evident from augmented urinary excretion of urea, uric acid and creatinine. Further, an enhanced susceptibility of the apo B-containing lipoproteins (LDL + VLDL) to oxidation in vitro, induced by copper ions was also found in the plasma of CsA given groups. While SPS co-treated groups (5 mg/kg body weight, subcutaneously) revealed a normalized lipid profile and lipid metabolizing enzymes, the supplementation of SPS also brought back the elevated urinary constituents close to that of the controls and substantially minimized the oxidative changes. With these observations, it may be concluded herein that SPS may be an ideal choice as a renoprotective and hypolipidemic agent against CsA-induced hyperlipidemic nephropathy.
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Affiliation(s)
- Anthony Josephine
- Department of Medical Biochemistry, Dr ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, India
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20
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Baiocchi L, Angelico M, De Luca L, Ombres D, Anselmo A, Telesca C, Orlando G, D'Andria D, Tisone G. Cyclosporine A versus tacrolimus monotherapy. Comparison on bile lipids in the first 3 months after liver transplant in humans. Transpl Int 2006; 19:389-95. [PMID: 16623874 DOI: 10.1111/j.1432-2277.2006.00296.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Biliary lipids output is reduced after liver transplantation and tends to normalize thereafter. Cyclosporine A (CyA) is reported to interfere with the normal bile-restoring process after liver grafting, but data are inconclusive, in particular regarding the comparison with the other widely used calcineurin inhibitor tacrolimus (TCR). Furthermore, previous researches were conducted in patients taking multiple immunosuppressive therapies and with a short follow up. In this study we readdressed this issue by comparing biliary lipids in the first 3 months after liver transplant, in 20 patients randomized to receive immunosuppression with CyA or TCR monotherapy. Bile samples, harvested through a T-tube at days 1, 3, 7, 15, 30, 60 and 90 were assessed for cholesterol, phospholipids, and total and individual concentrations of bile acids (BA). Liver and kidney function tests were evaluated as well. We found no differences between CyA and TCR in biochemical findings or in total biliary BAs, cholesterol, and phospholipids. However, CyA-treated patients showed lower levels of glycochenodeoxycholic acid at day 15, compared to those treated with TCR (P < 0.04). This difference normalized thereafter, without any biochemical or clinical effect at 3-month follow up.
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21
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Hall EA, Ren S, Hylemon PB, Rodriguez-Agudo D, Redford K, Marques D, Kang D, Gil G, Pandak WM. Detection of the steroidogenic acute regulatory protein, StAR, in human liver cells. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1733:111-9. [PMID: 15863358 DOI: 10.1016/j.bbalip.2005.01.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Revised: 12/16/2004] [Accepted: 01/20/2005] [Indexed: 11/30/2022]
Abstract
Overexpressing StAR (a mitochondrial cholesterol transporter) increases (>5-fold) the rate of 27-hydroxylation of cholesterol and the rates of bile acid synthesis in primary rat hepatocytes; suggesting that the transport of cholesterol into mitochondria is rate-limiting for bile acid biosynthesis via the CYP27A1 initiated 'acidic' pathway. Our objective was to determine the level of StAR expression in human liver and whether changes in StAR would correlate with changes in CYP27A1 activity/bile acid synthesis rates in human liver tissues. StAR mRNA and protein were detected in primary human hepatocytes and HepG2 cells by RT-PCR/Northern analysis and by Western analysis, respectively. In immunocompetition assays, liver StAR was competed away with the addition of purified human adrenal StAR. Overexpressing CYP27A1 in both cell types led to >2-fold increases in liver StAR concentration. StAR protein levels also increased approximately 2-fold with the addition of 27-hydroxycholesterol to HepG2 cell culture medium. Overexpressing StAR increased the rates of 27-hydroxylation of cholesterol/bile acid synthesis in both cell lines and increased intracellular levels of 27-hydroxycholesterol. In conclusion, human liver cells contain regulable StAR protein whose level of expression appears capable of regulating cellular cholesterol homeostasis, representing a potential therapeutic target in the management of hyperlipidemia.
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Affiliation(s)
- E A Hall
- Department of Medicine, Veterans Affairs Medical Center and Virginia Commonwealth University, Richmond, USA
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22
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Hansson M, Wikvall K, Babiker A. Regulation of sterol 27-hydroxylase in human monocyte-derived macrophages: up-regulation by transforming growth factor β1. Biochim Biophys Acta Mol Cell Biol Lipids 2005; 1687:44-51. [PMID: 15708352 DOI: 10.1016/j.bbalip.2004.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Revised: 10/04/2004] [Accepted: 11/03/2004] [Indexed: 01/22/2023]
Abstract
Regulatory mechanisms for human CYP27A1 enzyme have not yet been fully investigated. Our approach was to add different hormones and cytokines to cultured human monocyte-derived macrophages, and assess the effects on the CYP27A1 by measuring the production of 27-hydroxylated cholesterol in the media. Of the different hormones and cytokines tested, only transforming growth factor beta1 (TGF-beta1) had a clear effect on CYP27A1. Further experiments showed a significant increase in 27-hydroxylated cholesterol products (27-hydroxycholesterol and 3beta-hydroxy-5-cholestenoic acid). A concomitant increase in CYP27A1 mRNA levels was also seen and this positive effect was confirmed using a human CYP27A1 luciferase reporter gene expressed in HepG2 cells. Experiments with progressive deletion/luciferase reporter gene constructs indicated that a TGF-beta1 responsive sequence might be localized in a region about 400 bp upstream of the CYP27A1 translation start. The possibility is discussed that induction of CYP27A1 by TGF-beta1 may be responsible for some of the anti-atherogenic properties of this cytokine.
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Affiliation(s)
- Magnus Hansson
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska University Hospital at Huddinge, SE-141 86 Stockholm, Sweden
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Abstract
This article summarises the mechanisms responsible for the hyperlipidaemia observed after immunosuppressive treatment. Much progress has been achieved in the treatment of organ transplantation over the last 10 years, in particular because of the use of new immunosuppressive drugs with less nephrotoxicity. However, hypercholesterolaemia and hypertriglyceridaemia persist among many patients, who are thus more likely to develop cardiovascular diseases. We first reviewed the effects of immunosuppressive drugs on biliary acid biosynthesis, which is the main pathway of cholesterol degradation. The inhibition of this biosynthesis pathway, and especially of some key cytochrome P450s (CYP) such as CYP27A1, could contribute to the increased cholesterolaemia. Immunosuppressive drugs may also modify the activity of lipoprotein receptors or the expression of different apolipoproteins involved in cholesterol and triglyceride transport by lipoproteins. Finally, the fact that hypertriglyceridaemia is more frequently observed after certain immunosuppressive treatments may be partly caused by changes in the synthesis and elimination of triglycerides involving lipoprotein lipase or some apolipoproteins which serve as its cofactors (apoCII or apoCIII).
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Affiliation(s)
- Yann Gueguen
- INSERM U525, Université Henri Poincaré--Nancy 1, Nancy, France
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24
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Hulzebos CV, Bijleveld CMA, Stellaard F, Kuipers F, Fidler V, Slooff MJH, Peeters PMJG, Sauer PJJ, Verkade HJ. Cyclosporine A-induced reduction of bile salt synthesis associated with increased plasma lipids in children after liver transplantation. Liver Transpl 2004; 10:872-80. [PMID: 15237371 DOI: 10.1002/lt.20168] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Hyperlipidemia is a common side effect of cyclosporine A (CsA) after solid organ transplantation. CsA also markedly reduces the synthesis rate of bile salts in rats and can inhibit biliary bile salt secretion. It is not known, however, whether CsA inhibits the synthesis of bile salts in humans, and whether the hyperlipidemic effects of CsA are related to bile salt metabolism. Our objective was to assess the effects of CsA on the synthesis rate of bile salts and on plasma triglycerides and cholesterol levels in pediatric liver transplant patients. Before and after discontinuation of CsA treatment after liver transplantation, synthesis rate and pool size of the primary bile salts cholate and chenodeoxycholate were determined using a stable isotope dilution technique and related to plasma lipids. In 6 children (age: 3-16 years) CsA treatment was discontinued at 2 years (median 2.3 years) after liver transplantation. Discontinuation of CsA increased synthesis rate of chenodeoxycholate (+38%, P <.001) and cholate (+21%, P <.05) and the pool size of chenodeoxycholate (+54%, P <.001). Discontinuation of CsA decreased plasma levels of cholesterol (-18%, P <.05) and triglycerides (-23%, P <.05). Bile salt synthesis rate appeared to be inversely correlated with plasma cholesterol (Spearman rank correlation coefficient [r(s)] = -0.82, P <.01) and plasma triglyceride levels (r(s) = -0.62, P <.05). In conclusion, CsA inhibits bile salt synthesis and increases plasma concentration of cholesterol and triglycerides in pediatric liver transplant patients. Suppression of bile salt synthesis by long-term CsA treatment may contribute to hyperlipidemia and thus to increased risk for cardiovascular disease.
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Affiliation(s)
- Christian V Hulzebos
- Groningen University Institute for Drug Exploration, Center for Liver, Digestive and Metabolic Diseases, Pediatric Gastroenterology, Department of Pediatrics; University Hospital, Groningen, The Netherlands.
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Maeda K, Kimura A, Yamato Y, Matsuishi T. Perinatal bile acid metabolism: analysis of urinary unsaturated ketonic bile acids in preterm and full-term infants. Acta Paediatr 2003; 92:216-20. [PMID: 12710649 DOI: 10.1111/j.1651-2227.2003.tb00529.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To compare urinary concentrations of unsaturated ketonic bile acids in preterm and full-term infants. METHODS Urinary unsaturated ketonic bile acids were determined using gas chromatography-mass spectrometry. RESULTS Urinary concentrations of total bile acids in early preterm infants (of less than 29wk gestational age) exceeded concentrations in late preterm (between 30 and 37 wk) and full-term infants (between 38 and 41 wk; p < 0.01). The percentage of ketonic bile acids (7alpha, 12alpha-dihydroxy-3-oxo-4-cholenoic acid and 7alpha-hydroxy-3-oxo-4-cholenoic acid) among total urinary bile acids in full-term infants (20.2 +/- 14.1%) was higher than that in early preterm infants (8.94 +/- 8.1%; p < 0.05). The percentage of unsaturated bile acids (3beta-hydroxy-delta5-bile acids) among total bile acids in urine did not differ greatly between groups. CONCLUSION The percentage of 3-oxo-delta4 bile acids among total bile acids in urine gradually increased from early to late preterm infants, while healthy full-term infants excreted large amounts of 3-oxo-delta4 bile acids in urine at delivery.
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Affiliation(s)
- K Maeda
- Department of Pediatrics and Child Health, Kurume University School of Medicine, Kurume, Japan
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26
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Chanussot F, Benkoël L. Prevention by dietary (n-6) polyunsaturated phosphatidylcholines of intrahepatic cholestasis induced by cyclosporine A in animals. Life Sci 2003; 73:381-92. [PMID: 12759133 DOI: 10.1016/s0024-3205(03)00292-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Previous findings showed that dietary (n-6) polyunsaturated phosphatidylcholines (vegetable lecithin) could efficiently prevent intrahepatic cholestasis induced by cyclosporine A in rats. Mechanistic studies showed that expressions in rat liver of Na(+), K(+)-ATPase, Ca(2+), Mg(2+)-ATPase and F-actin were both decreased by drug administration and both enhanced by (n-6) lecithin enriched diet. There is a possible direct effect of phosphatidylcholines, vectors of polyunsaturated fatty acids provided by the metabolism of the dietary lecithin, on the aforesaid hepatic parameters. Such modulations by drug and diet result in reversed modifications of membrane composition and fluidity. Final outcome is decreased and enhanced bile lipid secretion by cyclosporine and vegetable lecithin enriched diet respectively. Moreover, we advance the hypothesis of a bypass process including a separate and functional actin-independent way for the non micellar and phospholipid-dependent secretion of bile lipids. The relationships between the ATPases, the microfilament components such as F-actin and the different transporters still remain to be clarified. Furthermore, one can speculate on beneficial effects in humans of diets enriched in vegetable lecithins that might prevent cholestasis induced by cyclosporine A.
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Affiliation(s)
- Françoise Chanussot
- INSERM U. 476, Faculté de Médecine, 27 bd Jean Moulin, 13385 Marseille cedex 05, France.
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Kosters A, Jirsa M, Groen AK. Genetic background of cholesterol gallstone disease. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1637:1-19. [PMID: 12527402 DOI: 10.1016/s0925-4439(02)00173-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cholesterol gallstone formation is a multifactorial process involving a multitude of metabolic pathways. The primary pathogenic factor is hypersecretion of free cholesterol into bile. For people living in the Western Hemisphere, this is almost a normal condition, certainly in the elderly, which explains the very high incidence of gallstone disease. It is probably because the multifactorial background genes responsible for the high incidence have not yet been identified, despite the fact that genetic factors clearly play a role. Analysis of the many pathways involved in biliary cholesterol secretion reveals many potential candidates and considering the progress in unraveling the regulatory mechanisms of the responsible genes, identification of the primary gallstone genes will be successful in the near future.
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Affiliation(s)
- Astrid Kosters
- Department of Experimental Hepatology, AMC Liver Center S1-172, Academic Medical Center, Meibergdreef 69-71, 1105 BK, Amsterdam, The Netherlands.
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Hulzebos CV, Wolters H, Plösch T, Kramer W, Stengelin S, Stellaard F, Sauer PJJ, Verkade HJ, Kuipers F. Cyclosporin a and enterohepatic circulation of bile salts in rats: decreased cholate synthesis but increased intestinal reabsorption. J Pharmacol Exp Ther 2003; 304:356-63. [PMID: 12490612 DOI: 10.1124/jpet.102.041640] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cyclosporin A (CsA) has been shown to inhibit synthesis and hepatobiliary transport of bile salts. However, effects of CsA on the enterohepatic circulation of bile salts in vivo are largely unknown. We characterized the effects of CsA on the enterohepatic circulation of cholate, with respect to synthesis rate, pool size, cycling time, intestinal absorption, and the expression of relevant transporters in liver and intestine in rats. CsA (1 mg. 100 g(-1). day(-1) s.c.) or its solvent was administered daily to male rats for 10 days. Cholate synthesis rate and pool size were determined by a 2H4-cholate dilution technique. Bile and feces were collected for determination of cholate and total bile salts, respectively. Cycling time and intestinal absorption of cholate were calculated. The mRNA levels and corresponding transporter protein levels in liver and intestine were assessed by real-time polymerase chain reaction and Western analysis, respectively. CsA treatment decreased cholate synthesis rate by 71%, but did not affect pool size or cycling time. CsA reduced the amount of cholate lost per enterohepatic cycle by approximately 70%. Protein levels of the apical sodium-dependent bile salt transporter (Asbt) were 2-fold increased in distal ileum of CsA-treated rats, due to post-transcriptional events. In conclusion, chronic CsA treatment markedly reduces cholate synthesis rate in rats, but does not affect cholate pool size or cycling time. Our results strongly suggest that CsA enhances efficacy of intestinal cholate reabsorption through increased Asbt protein expression in the distal ileum, which contributes to maintenance of cholate pool size in CsA-treated rats.
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Affiliation(s)
- Christian V Hulzebos
- Groningen University Institute for Drug Exploration, Center for Liver, Digestive, and Metabolic Diseases, Laboratory of Pediatrics, University Hospital Groningen, Groningen, The Netherlands.
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29
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Pandak WM, Ren S, Marques D, Hall E, Redford K, Mallonee D, Bohdan P, Heuman D, Gil G, Hylemon P. Transport of cholesterol into mitochondria is rate-limiting for bile acid synthesis via the alternative pathway in primary rat hepatocytes. J Biol Chem 2002; 277:48158-64. [PMID: 12368294 DOI: 10.1074/jbc.m205244200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Bile acid synthesis occurs mainly via two pathways: the "classic" pathway, initiated by microsomal cholesterol 7alpha-hydroxylase (CYP7A1), and an "alternative" (acidic) pathway, initiated by sterol 27-hydroxylase (CYP27). CYP27 is located in the inner mitochondrial membrane, where cholesterol content is very low. We hypothesized that cholesterol transport into mitochondria may be rate-limiting for bile acid synthesis via the "alternative" pathway. Overexpression of the gene encoding steroidogenic acute regulatory (StAR) protein, a known mitochondrial cholesterol transport protein, led to a 5-fold increase in bile acid synthesis. An increase in StAR protein coincided with an increase in bile acid synthesis. CYP27 overexpression increased bile acid synthesis by <2-fold. The rates of bile acid synthesis following a combination of StAR plus CYP27 overexpression were similar to those obtained with StAR alone. TLC analysis of (14)C-labeled bile acids synthesized in cells overexpressing StAR showed a 5-fold increase in muricholic acid; in chloroform-extractable products, a dramatic increase was seen in bile acid biosynthesis intermediates (27- and 7,27-hydroxycholesterol). High-performance liquid chromatography analysis showed that 27-hydroxycholesterol accumulated in the mitochondria of StAR-overexpressing cells only. These findings suggest that cholesterol delivery to the inner mitochondrial membrane is the predominant rate-determining step for bile acid synthesis via the alternative pathway.
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Affiliation(s)
- William M Pandak
- Department of Medicine, Veterans Affairs Medical Center, and Virginia Commonwealth University, Richmond 23298-0711, USA.
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30
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Abstract
Bile acids derived from cholesterol and oxysterols derived from cholesterol and bile acid synthesis pathways are signaling molecules that regulate cholesterol homeostasis in mammals. Many nuclear receptors play pivotal roles in the regulation of bile acid and cholesterol metabolism. Bile acids activate the farnesoid X receptor (FXR) to inhibit transcription of the gene for cholesterol 7alpha-hydroxylase, and stimulate excretion and transport of bile acids. Therefore, FXR is a bile acid sensor that protects liver from accumulation of toxic bile acids and xenobiotics. Oxysterols activate the liver orphan receptors (LXR) to induce cholesterol 7alpha-hydroxylase and ATP-binding cassette family of transporters and thus promote reverse cholesterol transport from the peripheral tissues to the liver for degradation to bile acids. LXR also induces the sterol response element binding protein-1c that regulates lipogenesis. Therefore, FXR and LXR play critical roles in coordinate control of bile acid, cholesterol, and triglyceride metabolism to maintain lipid homeostasis. Nuclear receptors and bile acid/oxysterol-regulated genes are potential targets for developing drug therapies for lowering serum cholesterol and triglycerides and treating cardiovascular and liver diseases.
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Affiliation(s)
- John Y L Chiang
- Department of Biochemistry and Molecular Pathology, Northeastern Ohio Universities College of Medicine, Rootstown, Ohio 44272, USA.
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31
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Post SM, Duez H, Gervois PP, Staels B, Kuipers F, Princen HM. Fibrates suppress bile acid synthesis via peroxisome proliferator-activated receptor-alpha-mediated downregulation of cholesterol 7alpha-hydroxylase and sterol 27-hydroxylase expression. Arterioscler Thromb Vasc Biol 2001; 21:1840-5. [PMID: 11701475 DOI: 10.1161/hq1101.098228] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Fibrates are hypolipidemic drugs that affect the expression of genes involved in lipid metabolism by activating peroxisome proliferator-activated receptors (PPARs). Fibrate treatment causes adverse changes in biliary lipid composition and decreases bile acid excretion, leading to an increased incidence of cholesterol gallstones. In this study, we investigated the effect of fibrates on bile acid synthesis. Ciprofibrate and the PPARalpha agonist Wy14,643 decreased bile acid synthesis in cultured rat hepatocytes and suppressed cholesterol 7alpha-hydroxylase and sterol 27-hydroxylase activities, paralleled by a similar reduction of the respective mRNAs. Treatment of rats with 0.05% (wt/wt) ciprofibrate decreased cholesterol 7alpha-hydroxylase enzyme activity and mRNA. The functional involvement of PPARalpha in the suppression of both enzymes was proven with the use of PPARalpha-null mice. In wild-type mice, ciprofibrate reduced cholesterol 7alpha-hydroxylase and sterol 27-hydroxylase enzyme activities and mRNA. The decrease in mRNA of both enzymes is regulated transcriptionally and posttranscriptionally, respectively, resulting in a decline in the output of fecal bile acids (-45%) and a 3-fold increase in fecal cholesterol secretion. These effects were completely abolished in PPARalpha-null mice. A decreased bile acid production by PPARalpha-mediated downregulation of cholesterol 7alpha-hydroxylase and sterol 27-hydroxylase may contribute to the increased risk of gallstone formation after fibrate treatment.
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Affiliation(s)
- S M Post
- Gaubius Laboratory, TNO-PG, Leiden, the Netherlands
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32
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Pandak WM, Schwarz C, Hylemon PB, Mallonee D, Valerie K, Heuman DM, Fisher RA, Redford K, Vlahcevic ZR. Effects of CYP7A1 overexpression on cholesterol and bile acid homeostasis. Am J Physiol Gastrointest Liver Physiol 2001; 281:G878-89. [PMID: 11557507 DOI: 10.1152/ajpgi.2001.281.4.g878] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The initial and rate-limiting step in the classic pathway of bile acid biosynthesis is 7alpha-hydroxylation of cholesterol, a reaction catalyzed by cholesterol 7alpha-hydroxylase (CYP7A1). The effect of CYP7A1 overexpression on cholesterol homeostasis in human liver cells has not been examined. The specific aim of this study was to determine the effects of overexpression of CYP7A1 on key regulatory steps involved in hepatocellular cholesterol homeostasis, using primary human hepatocytes (PHH) and HepG2 cells. Overexpression of CYP7A1 in HepG2 cells and PHH was accomplished by using a recombinant adenovirus encoding a CYP7A1 cDNA (AdCMV-CYP7A1). CYP7A1 overexpression resulted in a marked activation of the classic pathway of bile acid biosynthesis in both PHH and HepG2 cells. In response, there was decreased HMG-CoA-reductase (HMGR) activity, decreased acyl CoA:cholesterol acyltransferase (ACAT) activity, increased cholesteryl ester hydrolase (CEH) activity, and increased low-density lipoprotein receptor (LDLR) mRNA expression. Changes observed in HMGR, ACAT, and CEH mRNA levels paralleled changes in enzyme specific activities. More specifically, LDLR expression, ACAT activity, and CEH activity appeared responsive to an increase in cholesterol degradation after increased CYP7A1 expression. Conversely, accumulation of the oxysterol 7alpha-hydroxycholesterol in the microsomes after CYP7A1 overexpression was correlated with a decrease in HMGR activity.
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Affiliation(s)
- W M Pandak
- Department of Medicine, Veterans Affairs Medical Center and Virginia Commonwealth University, Richmond, Virginia 23249, USA
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33
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Hall E, Hylemon P, Vlahcevic Z, Mallonee D, Valerie K, Avadhani N, Pandak W. Overexpression of CYP27 in hepatic and extrahepatic cells: role in the regulation of cholesterol homeostasis. Am J Physiol Gastrointest Liver Physiol 2001; 281:G293-301. [PMID: 11408283 DOI: 10.1152/ajpgi.2001.281.1.g293] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
In the liver, sterol 27-hydroxylase (CYP27) participates in the classic and alternative pathways of bile acid biosynthesis from cholesterol (Chol). In extrahepatic tissues, CYP27 converts intracellular Chol to 27-hydroxycholesterol (27OH-Chol), which may regulate the activity of 3-hydroxy-3-methylglutaryl CoA reductase (HMG-CoA-R). This study attempts to better define the role of CYP27 in the maintenance of Chol homeostasis in hepatic and extrahepatic cells by overexpressing CYP27 in Hep G2 cells and Chinese hamster ovary (CHO) cells through infection with a replication-defective recombinant adenovirus encoding for CMV-CYP27. After infection, CYP27 mRNA and protein levels increased dramatically. CYP27 specific activity also increased two- to fourfold in infected cells (P < or = 0.02), with a marked increase in conversion of [(14)C]Chol to [(14)C]27OH-Chol (approximately 150%; P < or = 0.01). Accumulation of 27OH-Chol in CHO cells was associated with a 50% decrease in HMG-CoA-R specific activity (P < or = 0.02). In infected Hep G2 cells, the significant increase in bile acid synthesis (46%; P < or = 0.006), which prevented the accumulation of intracellular 27OH-Chol, resulted in increased HMG-CoA-R activity (183%; P < or = 0.02). Overexpression of CYP27 in Hep G2 cells also increased acyl CoA-cholesterol acyltransferase (71%, P < or = 0.02) and decreased cholesteryl ester hydrolase (55%, P < or = 0.02). In conclusion, CYP27 generates different physiological responses depending on cell type and presence or absence of bile acid biosynthetic pathways.
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Affiliation(s)
- E Hall
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University and McGuire Veterans Affairs Medical Center, Richmond, Virginia 23249, USA
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34
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Lyons MA, Brown AJ. Metabolism of an oxysterol, 7-ketocholesterol, by sterol 27-hydroxylase in HepG2 cells. Lipids 2001; 36:701-11. [PMID: 11521968 DOI: 10.1007/s11745-001-0775-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
7-Ketocholesterol (7K) is a quantitatively important oxysterol in both atherosclerotic lesions and macrophage foam cells. We reported recently that radiolabeled 7K delivered to rodents in a modified lipoprotein or chylomicron remnant-like emulsion, both cleared predominantly by the liver, was rapidly excreted into the intestine as water-soluble products, presumably bile acids. Herein, we aimed to elucidate the early or initial reactions in 7K metabolism. The hypothesis was tested that sterol 27-hydroxylase, a mitochondrial cytochrome P450 and the first enzyme of the acidic bile acid pathway, is responsible for the initial metabolism of 7K by HepG2 cells, a human hepatoblastoma cell-line. The 27-hydroxylated product of 7K (27OH-7K) was shown to be the initial, lipid-soluble product of 7K metabolism. It was produced in mitochondrial incubations and whole cells and was readily released into the media from cells. Intact cells generated metabolites of 7K that had undergone conversion from lipid-soluble precursors to water-soluble products rapidly and extensively. Their production was ablated with cyclosporin A, a sterol 27-hydroxylase inhibitor. Furthermore, we demonstrated the effectiveness of two novel selective inhibitors of this enzyme, GW273297X and GI268267X. These inhibitors also ablated the production of water-soluble products by cells; and the inhibitor of choice, GW273297X, decreased the production of 27OH-7K in mitochondrial preparations. This is the first study to demonstrate that sterol 27-hydroxylase plays an important role in the metabolism of oxysterols such as 7K in liver cells.
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Affiliation(s)
- M A Lyons
- Cell Biology Group, Heart Research Institute, Sydney, New South Wales, Australia
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35
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Pandak WM, Bohdan P, Franklund C, Mallonee DH, Eggertsen G, Björkhem I, Gil G, Vlahcevic ZR, Hylemon PB. Expression of sterol 12alpha-hydroxylase alters bile acid pool composition in primary rat hepatocytes and in vivo. Gastroenterology 2001; 120:1801-9. [PMID: 11375960 DOI: 10.1053/gast.2001.24833] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
BACKGROUND & AIMS The rate of 12alpha-hydroxylation of bile acid intermediates is believed to determine the ratio of cholic acid (CA) to chenodeoxycholic acid (CDCA) biosynthesis and the overall hydrophobicity of the bile acid pool. The aim of this study was to determine the effects of the level of expression of sterol 12alpha-hydroxylase (CYP8b1) and cholesterol 7alpha-hydroxylase (CYP7a1) on rates of CA biosynthesis and bile acid pool composition. METHODS Expression of CYP8b1 and CYP7a1 was accomplished through infection of primary rat hepatocytes (PRH) or intact male SD rats with replication-defective recombinant adenoviruses encoding either CYP8b1 or CYP7a1. RESULTS Increased expression of CYP7a1 over basal levels in PRH dramatically increased bile acid biosynthesis (586% +/- 82%, P < 0.001) but did not alter the ratio of CA to CDCA. Conversely, increased expression of CYP8b1 in vitro had no significant effect on the rates of total bile acid synthesis but significantly increased (4.1-fold) the rates of CA biosynthesis, resulting in an increase in the CA-CDCA ratio from 1:6.6 to 2.8:1. In whole rats, increased CYP8b1 expression over basal levels markedly increased the CA in the bile acid pool from 36% +/- 3.4% to 50% +/- 2.9% in 5 days. CDCA and its muricholic acid derivatives decreased from 64% +/- 3.4% to 50% +/- 2.9%. CONCLUSIONS Increased expression of CYP8b1 led to a marked increase in CA biosynthesis both in PRH and in whole animals. CYP8b1 is capable of 12alpha-hydroxylating bile acid intermediates from both the classic and acidic pathways.
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Affiliation(s)
- W M Pandak
- Division of Gastroenterology, McGuire Veterans Administration Medical Center, Medical College of Virginia Campus of Virginia Commonwealth University, Richmond, Virginia 23249, USA.
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36
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Segev H, Honigman A, Rosen H, Leitersdorf E. Transcriptional regulation of the human sterol 27-hydroxylase gene (CYP27) and promoter mapping. Atherosclerosis 2001; 156:339-47. [PMID: 11395030 DOI: 10.1016/s0021-9150(00)00654-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Recent evidence suggests that sterol 27-hydroxylase may play a role in cholesterol homeostasis and affect atherogenesis. The major objective of the study was to map and characterize the sterol 27-hydroxylase (CYP27) promoter region. Here we show that CYP27 gene has a TATA-less promoter and transcription initiates at a cluster of sites. The basic promoter is located between -166 and -187 bp from the translation initiation site. Possible positive transcription regulation sites are located at position -187 to -320 and -857 to -1087 bp. A negative transcription regulator site is located in position -320 to -413 bp. An enhancer sequence is located upstream to position -1087. CYP27 is upregulated by dexamethasone and downregulated by cyclosporin A and cholic acid. The dexamethasone responsive element is located between 1087 and 678 bp upstream to the putative ATG. Cyclosporin A affects bile acid metabolism by repressing CYP27 at the transcriptional level. The cyclosporin A- responsive element is mapped to between 1087 and 4000 bp upstream of the ATG. Cholic acid represses sterol 27-hydroxylase mRNA level by affecting the stability of its mRNA. The results obtained here imply that CYP27 has a potentially important role in cholesterol homeostasis in human cells, and is regulated by several substances that were previously shown to affect bile acid metabolism.
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Affiliation(s)
- H Segev
- Department of Medicine, The Center for Research, Prevention, and Treatment of Atherosclerosis, Hadassah University Hospital, 91120, Jerusalem, Israel
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Del Puppo M, Kienle MG, Crosignani A, Petroni M, Amati B, Zuin M, Podda M. Cholesterol metabolism in primary biliary cirrhosis during simvastatin and UDCA administration. J Lipid Res 2001. [DOI: 10.1016/s0022-2275(20)31668-0] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Einarsson C, Ellis E, Abrahamsson A, Ericzon BG, Bjorkhem I, Axelson M. Bile acid formation in primary human hepatocytes. World J Gastroenterol 2000; 6:522-525. [PMID: 11819640 PMCID: PMC4723550 DOI: 10.3748/wjg.v6.i4.522] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate a culture system for bile acid formation in primary human hepatocytes in comparison with HepG2 cells.
METHODS: Hepatocytes were isolated from normal human liver tissue and were cultured in serum-free William’s E medium. The medium was collected and re newed every 24 h. Bile acids and their precursors in media were finally analysed by gas chromatography-mass spectrometry.
RESULTS: Cholic acid (CA) and chenodeoxycholic acid (CDCA) conjugated with glycine or taurine accounted for 70% and 25% of total steroids. A third of CDC A was also conjugated with sulphuric acid. Dexamethasone and thyroid hormone alone or in combination did not significantly effect bile acid formation. The addit ion of cyclosporin A (10 μmol/L) inhibited the synthesis of CA and CDCA by about 13% and 30%, respectively.
CONCLUSION: Isolated human hepatocytes in primary culture behave as in the intact liver by converting cholesterol to conjugated CA and CDCA. This is in contrast to cultured HepG2 cells, which release large amounts of bile acid precursors and unconjugated bile acids into the medium.
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Benkoel L, Chanussot F, Dodero F, De la Maisonneuve C, Bongrand P, Benoliel AM, Lambert R, Brisse J, Chamlian A. Effect of dietary lipid (soybean lecithin and triacylglycerol) on hepatic F-actin microfilaments in cyclosporine A-treated rats: image analysis by confocal laser scanning microscopy. Dig Dis Sci 2000; 45:1096-102. [PMID: 10877222 DOI: 10.1023/a:1005533531756] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
We studied and quantified the effect of cyclosporine A on hepatic F-actin on bile canalicular and basolateral membranes in rats fed either soybean lecithin, triacylglycerol-enriched diet, or low-fat diet by means of confocal laser scanning microscopy imaging. The phalloidin-FITC staining of F-actin was quite normal in the lecithin-cyclosporine A group but decreased significantly in the other cyclosporine A-treated groups (by 40% and 25% of control in triacylglycerol-cyclosporine A and cyclosporine A groups, respectively). The alteration of F-actin by cyclosporine A, related to cholestasis evidenced by a decrease in bile salt secretion, was prevented by dietary soybean lecithin and amplified by dietary soybean triacylglycerol.
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Affiliation(s)
- L Benkoel
- Laboratoire de Pathologie Cellulaire et Métabolique du Foie, INSERM U260, Faculté de Médecine, Marseille, France
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Axelson M, Ellis E, Mörk B, Garmark K, Abrahamsson A, Björkhem I, Ericzon BG, Einarsson C. Bile acid synthesis in cultured human hepatocytes: support for an alternative biosynthetic pathway to cholic acid. Hepatology 2000; 31:1305-12. [PMID: 10827156 DOI: 10.1053/jhep.2000.7877] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The biosynthesis of bile acids by primary cultures of normal human hepatocytes has been investigated. A general and sensitive method for the isolation and analysis of sterols and bile acids was used, based on anion exchange chromatography and gas chromatography-mass spectrometry (GC/MS). Following incubation for 5 days, 8 oxysterols and 8 C(27)- or C(24)-bile acids were identified in media and cells. Cholic and chenodeoxycholic acids conjugated with glycine or taurine were by far the major steroids found, accounting for 70% and 24% of the total, respectively, being consistent with bile acid synthesis in human liver. Small amounts of sulfated 3beta-hydroxy-5-cholenoic acid and 3beta,7alpha-dihydroxy-5beta-cholanoic acid were also detected. Nine steroids were potential bile acid precursors (2% of total), the major precursors being 7alpha, 12alpha-dihydroxy-3-oxo-4-cholenoic acid and its 5beta-reduced form. These 2 and 5 other intermediates formed a complete metabolic sequence from cholesterol to cholic acid (CA). This starts with 7alpha-hydroxylation of cholesterol, followed by oxidation to 7alpha-hydroxy-4-cholesten-3-one and 12alpha-hydroxylation. Notably, 27-hydroxylation of the product 7alpha, 12alpha-dihydroxy-4-cholesten-3-one and further oxidation and cleavage of the side chain precede A-ring reduction. A-Ring reduction may also occur before side-chain cleavage, but after 27-hydroxylation, yielding 3alpha,7alpha, 12alpha-trihydroxy-5beta-cholestanoic acid as an intermediate. The amounts of the intermediates increased in parallel to those of CA during 4 days of incubation. Suppressing 27-hydroxylation with cyclosporin A (CsA) resulted in a 10-fold accumulation of 7alpha, 12alpha-dihydroxy-4-cholesten-3-one and a decrease of the production of CA and its acidic precursors. These results suggest that the observed intermediates reflect an alternative biosynthetic pathway to CA, which may be quantitatively significant in the cells.
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Affiliation(s)
- M Axelson
- Department of Clinical Chemistry, Karolinska Hospital, Huddinge University Hospital, Karolinska Institute, Stockholm, Sweden.
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41
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Vlahcevic ZR, Eggertsen G, Björkhem I, Hylemon PB, Redford K, Pandak WM. Regulation of sterol 12alpha-hydroxylase and cholic acid biosynthesis in the rat. Gastroenterology 2000; 118:599-607. [PMID: 10702212 DOI: 10.1016/s0016-5085(00)70267-8] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Sterol 12alpha-hydroxylase (CYP8b1) is required for the biosynthesis of cholic acid (CA) and hence helps determine the ratio of CA to chenodeoxycholic acid (CDCA) in bile. This study examined the in vivo regulation of CYP8b1 in the rat by bile acids, cholesterol, and thyroxine. METHODS The specific activities (SAs), messenger RNA (mRNA) levels, and transcriptional activities of CYP8b1 were determined in intact rats and rats with biliary diversion. RESULTS CA, CDCA, and deoxycholic acid (DCA), fed as a supplement to the diet, down-regulated CYP8b1 SAs by 99% +/- 0%, 72% +/- 10%, and 98% +/- 1%, respectively. Under these same conditions, mRNA levels decreased by 93% +/- 7%, 60% +/- 11%, and 93% +/- 4%, respectively. Intraduodenal infusion of taurocholate (36 micromol/h. 100 g rat(-1)) decreased SAs and mRNA levels by 63% +/- 8% and 74% +/- 8%, respectively. Ursodeoxycholic acid (UDC) and hyocholic acid (HC) feeding increased CYP8b1 SAs by 119% +/- 21% and 65% +/- 18%, respectively. CA feeding decreased CYP8b1 transcriptional activity by 72%. Complete biliary diversion increased CYP8b1 SAs and mRNA levels by 150% +/- 30% and 287% +/- 51%, respectively. Cholesterol feeding decreased CYP8b1 mRNA by 39% +/- 8%. In intact rats, a single injection of thyroid hormone eliminated CYP8b1 activity. CONCLUSIONS CYP8b1 is transcriptionally down-regulated by hydrophobic but not hydrophilic bile acids. Cholesterol feeding and a single thyroid hormone injection repressed CYP8b1 in the face of induction of cholesterol 7alpha-hydroxylase (CYP7a1 by the new nomenclature) SAs. These results suggest that cholesterol, thyroid hormone, and hydrophobic bile acids are important regulators of CYP8b1 and consequently of the bile acid pool composition.
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Affiliation(s)
- Z R Vlahcevic
- Division of Gastroenterology, McGuire Veterans Administration Medical Center, Virginia Commonwealth University, Richmond, Virginia 23249, USA
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Abstract
Oxygenated derivatives of cholesterol (oxysterols) present a remarkably diverse profile of biological activities, including effects on sphingolipid metabolism, platelet aggregation, apoptosis, and protein prenylation. The most notable oxysterol activities center around the regulation of cholesterol homeostasis, which appears to be controlled in part by a complex series of interactions of oxysterol ligands with various receptors, such as the oxysterol binding protein, the cellular nucleic acid binding protein, the sterol regulatory element binding protein, the LXR nuclear orphan receptors, and the low-density lipoprotein receptor. Identification of the endogenous oxysterol ligands and elucidation of their enzymatic origins are topics of active investigation. Except for 24, 25-epoxysterols, most oxysterols arise from cholesterol by autoxidation or by specific microsomal or mitochondrial oxidations, usually involving cytochrome P-450 species. Oxysterols are variously metabolized to esters, bile acids, steroid hormones, cholesterol, or other sterols through pathways that may differ according to the type of cell and mode of experimentation (in vitro, in vivo, cell culture). Reliable measurements of oxysterol levels and activities are hampered by low physiological concentrations (approximately 0.01-0.1 microM plasma) relative to cholesterol (approximately 5,000 microM) and by the susceptibility of cholesterol to autoxidation, which produces artifactual oxysterols that may also have potent activities. Reports describing the occurrence and levels of oxysterols in plasma, low-density lipoproteins, various tissues, and food products include many unrealistic data resulting from inattention to autoxidation and to limitations of the analytical methodology. Because of the widespread lack of appreciation for the technical difficulties involved in oxysterol research, a rigorous evaluation of the chromatographic and spectroscopic methods used in the isolation, characterization, and quantitation of oxysterols has been included. This review comprises a detailed and critical assessment of current knowledge regarding the formation, occurrence, metabolism, regulatory properties, and other activities of oxysterols in mammalian systems.
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Affiliation(s)
- G J Schroepfer
- Departments of Biochemistry, Rice University, Houston, Texas, USA.
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Wu J, Zhu YH, Patel SB. Cyclosporin-induced dyslipoproteinemia is associated with selective activation of SREBP-2. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:E1087-94. [PMID: 10600799 DOI: 10.1152/ajpendo.1999.277.6.e1087] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The use of cyclosporin A has contributed greatly to the success of organ transplantation. However, cyclosporin-associated side effects of hypertension, nephrotoxicity, and dyslipoproteinemia have tempered these benefits. Cyclosporin-induced dyslipoproteinemia may be an important risk factor for the accelerated atherosclerosis observed posttransplantation. Using a mouse model, we treated Swiss-Webster mice for 6 days with a daily dose of 20 microg/g body wt of cyclosporin and observed significant elevations of plasma cholesterol, triglyceride, and apolipoprotein B (apoB) levels relative to vehicle-alone treated control animals. Measurement of the rate of secretion of very low-density lipoprotein (VLDL) by the liver in vivo showed that cyclosporin treatment led to a significant increase in the rate of hepatic VLDL triglyceride secretion. Total apoB secretion was unaffected. Northern analysis showed that cyclosporin A treatment increased the abundance of hepatic mRNA levels for a number of key genes involved in cholesterol biosynthesis relative to vehicle-alone treated animals. Two key transcriptional factors, sterol regulatory element-binding protein (SREBP)-1 and SREBP-2, also showed differential expression; SREBP-2 expression was increased at the mRNA level, and there was an increase in the active nuclear form, whereas the mRNA and the nuclear form of SREBP-1 were reduced. These results show that the molecular mechanisms by which cyclosporin causes dyslipoproteinemia may, in part, be mediated by selective activation of SREBP-2, leading to enhanced expression of lipid metabolism genes and hepatic secretion of VLDL triglyceride.
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Affiliation(s)
- J Wu
- Division of Endocrinology, Diabetes, and Medical Genetics, Medical University of South Carolina, Charleston, South Carolina 29425-2222, USA
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Nguyen LB, Xu G, Shefer S, Tint GS, Batta A, Salen G. Comparative regulation of hepatic sterol 27-hydroxylase and cholesterol 7alpha-hydroxylase activities in the rat, guinea pig, and rabbit: effects of cholesterol and bile acids. Metabolism 1999; 48:1542-8. [PMID: 10599986 DOI: 10.1016/s0026-0495(99)90243-3] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The regulation of the classic and alternative bile acid synthetic pathways by key hepatic enzyme activities (microsomal cholesterol 7alpha-hydroxylase and mitochondrial sterol 27-hydroxylase, respectively) was examined in bile acid depletion and replacement and cholesterol-feeding experiments with rats, guinea pigs, and rabbits. The bile acid pool was depleted by creating a bile fistula (BF) and collecting bile for 2 to 5 days, and it was replaced by intraduodenal infusion of the major biliary bile acids (taurocholic acid [TCA], glycochenodeoxycholic acid [GCDCA], and glycocholic acid [GCA] in the rat, guinea pig, and rabbit, respectively) at rates equivalent to the measured hepatic flux of the bile acids. To study the effects of cholesterol, the animals were fed for 7 days on a basal diet with and without 2% cholesterol. Cholesterol 7alpha-hydroxylase and sterol 27-hydroxylase activities, measured by isotope incorporation assays, were related to bile acid output and composition and hepatic cholesterol concentrations. Intraduodenal infusion of bile acids increased the output of the tested bile acids, but did not significantly change hepatic cholesterol concentrations and had no effect on sterol 27-hydroxylase activity. Neither bile acid depletion nor replacement affected sterol 27-hydroxylase activity when three different substrates (cholesterol, 5beta-cholestane-3alpha,7alpha-diol, and 5beta-cholestane-3alpha,7alpha,12alpha-triol) were tested. In contrast, feeding 2% cholesterol increased hepatic cholesterol concentrations in rats, guinea pigs, and rabbits threefold, twofold, and eightfold, respectively, and increased hepatic mitochondrial sterol 27-hydroxylase activity (conversion of cholesterol to 27-hydroxycholesterol) in all three animal models. The stimulation and feedback inhibition of cholesterol 7alpha-hydroxylase activity by bile acid depletion and replacement were observed in all three animal models, whereas the effect of cholesterol feeding was species-dependent (cholesterol 7alpha-hydroxylase activity increased in the rat, did not change in the guinea pig, and was inhibited in the rabbit). Thus, in contrast to sterol 27-hydroxylase, which was upregulated by cholesterol but not affected by bile acid depletion and replacement in all three animal models, cholesterol 7alpha-hydroxylase activity was controlled consistently and inversely by the hepatic flux of bile acids, but was species-dependent in its response to a 1-week feeding with 2% cholesterol.
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Affiliation(s)
- L B Nguyen
- Department of Medicine/Division of Gastroenterology and the Liver Center, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark 07103, USA
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Hillebrant C, Nyberg B, Angelin B, Axelson M, Björkhem I, Rudling M, Einarsson C. Deoxycholic acid treatment in patients with cholesterol gallstones: failure to detect a suppression of cholesterol 7alpha-hydroxylase activity. J Intern Med 1999; 246:399-407. [PMID: 10583711 DOI: 10.1046/j.1365-2796.1999.00572.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
UNLABELLED Hillebrant C-G, Nyberg B, Angelin B, Axelson M, Björkhem I, Rudling M, Einarsson C (Huddinge University Hospital and Karolinska Hospital, Karolinska Institute, Stockholm, Sweden). Deoxycholic acid treatment in patients with cholesterol gallstones: failure to detect a suppression of cholesterol 7alpha-hydroxylase activity. J Intern Med 1999; 246: 399-407. OBJECTIVES Based on animal studies, hydrophobic bile acids have been postulated to be particularly strong inhibitors of bile acid synthesis. The present study was undertaken to characterize in humans the effects of one of the most hydrophobic of the common bile acids, deoxycholic acid (DCA), on the transcriptional regulation and activity of the cholesterol 7alpha-hydroxylase, on hepatic cholesterol metabolism and on biliary lipid metabolism and plasma lipids. DESIGN, SUBJECTS AND SETTINGS: Thirteen patients with cholesterol gallstone disease were treated with DCA (750 mg day-1) for 3 weeks prior to cholecystectomy. Blood samples were collected before and during treatment. At operation, a liver biopsy and gallbladder bile were obtained. Twenty-eight untreated gallstone patients undergoing cholecystectomy served as controls. The study was carried out at a university hospital. RESULTS Deoxycholic acid comprised 72 +/- 6% (mean +/- SEM) of total biliary bile acids in DCA-treated patients (n = 8), and 21 +/- 2% in the controls (n = 16; P < 0.001). Cholesterol saturation of gallbladder bile averaged 102% in both treated (n = 7) and untreated (n = 16) patients. Cholesterol 7alpha-hydroxylase and HMG CoA reductase activities and mRNA levels were not different between DCA-treated and untreated gallstone patients. The LDL receptor mRNA levels were similar in both groups of patients. Plasma levels of total cholesterol were lowered by 10% upon DCA treatment (P < 0.05). CONCLUSIONS Treatment with DCA did not significantly affect mRNA levels and activity of hepatic cholesterol 7alpha-hydroxylase or HMG CoA reductase in patients with cholesterol gallstones. There was no effect on the saturation of gallbladder bile, Thus, the present study could not verify that the hydrophobicity of the bile acid pool is a major factor regulating human hepatic cholesterol 7alpha-hydroxylase activity.
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Affiliation(s)
- C Hillebrant
- Department of Gastroenterology, Huddinge University Hospital, Sweden
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Benkoël L, Chanussot F, Dodero F, de la Maisonneuve C, Lambert R, Brisse J, Chamlian A. Effect of dietary lipids on hepatic Na+,K(+)-ATPase in cyclosporine A-treated rats: immunocytochemical analysis of alpha1 subunit by confocal laser scanning microscopy imaging. Dig Dis Sci 1999; 44:1643-9. [PMID: 10492147 DOI: 10.1023/a:1026683531461] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
We studied the effect of dietary soybean lecithin or triacylglycerol on hepatic Na+,K(+)-ATPase in cyclosporine A-treated rats by means of quantitative immunocytochemistry. Cyclosporine A-treated rats were fed lecithin or a triacylglycerol-enriched diet or a low-fat diet. As a control, one group was only fed the low-fat diet; the three other groups were treated with cyclosporine A solvent and received the low fat, lecithin, or triacylglycerol diet. Bile canalicular staining significantly decreased in all cyclosporine A-treated groups with the higher values in lecithin-fed rats. In basolateral membranes, no decrease was observed in the lecithin-cyclosporine group, in contrast to the other groups. The triacylglycerol-cyclosporine group had lower values in both membrane domains. The alteration of Na+,K(+)-ATPase by cyclosporine A was related to cholestasis evidenced by a decrease in bile salt secretion. These modifications were prevented by dietary soybean lecithin and amplified by dietary soybean triacylglycerol.
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Affiliation(s)
- L Benkoël
- Laboratoire de Pathologie Cellulaire et Métabolique du Foie (JE 2058), Faculté de Médecine, Marseille, France
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Post SM, Zoeteweij JP, Bos MH, de Wit EC, Havinga R, Kuipers F, Princen HM. Acyl-coenzyme A:cholesterol acyltransferase inhibitor, avasimibe, stimulates bile acid synthesis and cholesterol 7alpha-hydroxylase in cultured rat hepatocytes and in vivo in the rat. Hepatology 1999; 30:491-500. [PMID: 10421659 DOI: 10.1002/hep.510300230] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Acyl-coenzyme A:cholesterol acyltransferase (ACAT) inhibitors are currently in clinical development as potential lipid-lowering and antiatherosclerotic agents. We investigated the effect of avasimibe (Cl- 1011), a novel ACAT inhibitor, on bile acid synthesis and cholesterol 7alpha-hydroxylase in cultured rat hepatocytes and rats fed different diets. Avasimibe dose-dependently decreased ACAT activity in rat hepatocytes in the presence and absence of beta-migrating very low-density lipoproteins (betaVLDL) (by 93% and 75% at 10 micromol/L) and reduced intracellular storage of cholesteryl esters. Avasimibe (3 micromol/L) increased bile acid synthesis (2.9-fold) after preincubation with betaVLDL and cholesterol 7alpha-hydroxylase activity (1.7- and 2.6-fold, with or without betaVLDL), the latter paralleled by a similar induction of its messenger RNA (mRNA). Hepatocytes treated with avasimibe showed a shift from storage and secretion of cholesteryl esters to conversion of cholesterol into bile acids. In rats fed diets containing different amounts of cholesterol and cholate, avasimibe reduced plasma cholesterol (by 52% to 71%) and triglyceride levels (by 28% to 62%). Avasimibe did not further increase cholesterol 7alpha-hydroxylase activity and mRNA in cholesterol-fed rats, but prevented down-regulation by cholate. Avasimibe did not affect sterol 27-hydroxylase and oxysterol 7alpha-hydroxylase, 2 enzymes in the alternative pathway in bile acid synthesis. No increase in the ratio of biliary excreted cholesterol to bile acids was found, indicating that ACAT inhibition does not result in a more lithogenic bile. Avasimibe increases bile acid synthesis in cultured hepatocytes by enhancing the supply of free cholesterol both as substrate and inducer of cholesterol 7alpha-hydroxylase. These effects may partially explain the potent cholesterol-lowering effects of avasimibe in the rat.
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Affiliation(s)
- S M Post
- Gaubius Laboratory, TNO-PG, Leiden, The Netherlands
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Post SM, Twisk J, van der Fits L, de Wit EC, Hoekman MF, Mager WH, Princen HM. Lipoprotein cholesterol uptake mediates up-regulation of bile-acid synthesis by increasing cholesterol 7alpha-hydroxylase but not sterol 27-hydroxylase gene expression in cultured rat hepatocytes. Biochem J 1999; 341 ( Pt 2):339-46. [PMID: 10393091 PMCID: PMC1220365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Lipoproteins may supply substrate for the formation of bile acids, and the amount of hepatic cholesterol can regulate bile-acid synthesis and increase cholesterol 7alpha-hydroxylase expression. However, the effect of lipoprotein cholesterol on sterol 27-hydroxylase expression and the role of different lipoproteins in regulating both enzymes are not well established. We studied the effect of different rabbit lipoproteins on cholesterol 7alpha-hydroxylase and sterol 27-hydroxylase in cultured rat hepatocytes. beta-Migrating very-low-density lipoprotein (betaVLDL) and intermediate-density lipoprotein (IDL) caused a significant increase in the intracellular cholesteryl ester content of cells (2. 3- and 2-fold, respectively) at a concentration of 200 microgram of cholesterol/ml, whereas high-density lipoprotein (HDL, 50% v/v), containing no apolipoprotein E (apo E), showed no effect after a 24-h incubation. betaVLDL and IDL increased bile-acid synthesis (1. 9- and 1.6-fold, respectively) by up-regulation of cholesterol 7alpha-hydroxylase activity (1.7- and 1.5-fold, respectively). Dose- and time-dependent changes in cholesterol 7alpha-hydroxylase mRNA levels and gene expression underlie the increase in enzyme activity. Incubation of cells with HDL showed no effect. Sterol 27-hydroxylase gene expression was not affected by any of the lipoproteins added. Transient-expression experiments in hepatocytes, transfected with a promoter-reporter construct containing the proximal 348 nucleotides of the rat cholesterol 7alpha-hydroxylase promoter, showed an enhanced gene transcription (2-fold) with betaVLDL, indicating that a sequence important for a cholesterol-induced transcriptional response is located in this part of the cholesterol 7alpha-hydroxylase gene. The extent of stimulation of cholesterol 7alpha-hydroxylase is associated with the apo E content of the lipoprotein particle, which is important in the uptake of lipoprotein cholesterol. We conclude that physiological concentrations of cholesterol in apo E-containing lipoproteins increase bile-acid synthesis by stimulating cholesterol 7alpha-hydroxylase gene transcription, whereas HDL has no effect and sterol 27-hydroxylase is not affected.
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Affiliation(s)
- S M Post
- Gaubius Laboratory, TNO-PG, Zernikedreef 9, 2333 CK, Leiden, The Netherlands
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Scheibner J, Fuchs M, Hörmann E, Stange EF. Complex feedback regulation of bile acid synthesis in the hamster: the role of newly synthesized cholesterol. Hepatology 1999; 30:230-7. [PMID: 10385661 DOI: 10.1002/hep.510300135] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Abstract
Hepatic bile acid synthesis is regulated by recirculating bile acids, possibly by modulating the availability of newly synthesized and preformed cholesterol. Because data in the hamster on this mechanism are lacking, we fitted these animals with an extracorporeal bile duct and administered tritiated water intraperitoneally to label newly formed cholesterol. After interruption of the enterohepatic circulation, physiological and double-physiological doses of conjugated cholate (25 or 50 micromol/100 g. h) or of unconjugated deoxycholate (6 or 12 micromol) were infused intraduodenally for 54 hours and compared with controls. De novo and preformed cholesterol directly secreted into bile or used for cholate and chenodeoxycholate synthesis were quantitated by high-pressure liquid chromatography (HPLC)-liquid scintillation. Directly after depletion of the bile acid pool (6-9 hours) at nearly physiological conditions, chenodeoxycholate synthesis was significantly reduced by cholate and deoxycholate by up to 45% to 51%, whereas cholate formation decreased by approximately 22% during deoxycholate. This short-term effect was mainly mediated by reduced synthesis from preformed cholesterol. After long-term bile depletion (30-54 hours), bile acid synthesis returned to control levels during 25 micromol of cholate and of both deoxycholate doses. In contrast, only 50 micromol of cholate prevented derepression of bile acid synthesis. This long-term effect was mainly attributed to a diminished formation from de novo cholesterol exceeding the reduced synthesis from preformed cholesterol. In summary, short- and long-term regulation of bile acid synthesis in hamsters differs with respect to availabilities of preformed and de novo cholesterol.
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Affiliation(s)
- J Scheibner
- Department of Internal Medicine I, Division of Gastroenterology, Medical University of Luebeck, Luebeck, Germany
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