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Current world literature. Curr Opin Psychiatry 2012; 25:251-9. [PMID: 22456191 DOI: 10.1097/yco.0b013e328352dd8d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Lee YS, Siméon FG, Briard E, Pike VW. Solution structures of the prototypical 18 kDa translocator protein ligand, PK 11195, elucidated with 1H/13C NMR spectroscopy and quantum chemistry. ACS Chem Neurosci 2012; 3:325-35. [PMID: 22860199 DOI: 10.1021/cn3000108] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 02/08/2012] [Accepted: 02/14/2012] [Indexed: 11/29/2022] Open
Abstract
Eighteen kilodalton translocator protein (TSPO) is an important target for drug discovery and for clinical molecular imaging of brain and peripheral inflammatory processes. PK 11195 [1a; 1-(2-chlorophenyl)-N-methyl-(1-methylpropyl)-3-isoquinoline carboxamide] is the major prototypical high-affinity ligand for TSPO. Elucidation of the solution structure of 1a is of interest for understanding small-molecule ligand interactions with the lipophilic binding site of TSPO. Dynamic (1)H/(13)C NMR spectroscopy of 1a revealed four quite stable but interconverting rotamers, due to amide bond and 2-chlorophenyl group rotation. These rotamers have been neglected in previous descriptions of the structure of 1a and of the binding of 1a to TSPO. Here, we used quantum chemistry at the level of B3LYP/6-311+G(2d,p) to calculate (13)C and (1)H chemical shifts for the rotamers of 1a and for the very weak TSPO ligand, N-desmethyl-PK 11195 (1b). These data, plus experimental NMR data, were then used to characterize the structures of rotamers of 1a and 1b in organic solution. Energy barriers for both the amide bond and 2'-chlorophenyl group rotation of 1a were determined from dynamic (1)H NMR to be similar (ca.17 to 18 kcal/mol), and they compared well with those calculated at the level of B3LYP/6-31G*. Furthermore, the computed barrier for Z to E rotation is considerably lower in 1a(18.7 kcal/mol) than in 1b (25.4 kcal/mol). NMR (NOE) unequivocally demonstrated that the E rotamer of 1a is the more stable in solution by about 0.4 kcal/mol. These detailed structural findings will aid future TSPO ligand design and support the notion that TSPO prefers to bind ligands as amide E-rotamers.
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Affiliation(s)
- Yong-Sok Lee
- Center for Molecular Modeling,
Division of Computational Bioscience, Center for Information Technology, National Institutes of Health, Building 12a, Room 2049,
Bethesda, Maryland 20892, United States
| | - Fabrice G. Siméon
- PET Radiopharmaceutical Sciences
Section, Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3
C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Emmanuelle Briard
- PET Radiopharmaceutical Sciences
Section, Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3
C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Victor W. Pike
- PET Radiopharmaceutical Sciences
Section, Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Building 10, Room B3
C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
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Keliher EJ, Yoo J, Nahrendorf M, Lewis JS, Marinelli B, Newton A, Pittet MJ, Weissleder R. 89Zr-labeled dextran nanoparticles allow in vivo macrophage imaging. Bioconjug Chem 2011; 22:2383-9. [PMID: 22035047 DOI: 10.1021/bc200405d] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Tissue macrophages play a critical role both in normal physiology and in disease states. However, because of a lack of specific imaging agents, we continue to have a poor understanding of their absolute numbers, flux rates, and functional states in different tissues. Here, we describe a new macrophage specific positron emission tomography imaging agent, labeled with zirconium-89 ((89)Zr), that was based on a cross-linked, short chain dextran nanoparticle (13 nm). Following systemic administration, the particle demonstrated a vascular half-life of 3.9 h and was found to be located primarily in tissue resident macrophages rather than other white blood cells. Subsequent imaging of the probe using a xenograft mouse model of cancer allowed for quantitation of tumor-associated macrophage numbers, which are of major interest in emerging molecular targeting strategies. It is likely that the material described, which allows the visualization of macrophage biology in vivo, will likewise be useful for a multitude of human applications.
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Affiliation(s)
- Edmund J Keliher
- Center for Systems Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, United States
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Current paradigm of the 18-kDa translocator protein (TSPO) as a molecular target for PET imaging in neuroinflammation and neurodegenerative diseases. Insights Imaging 2011; 3:111-9. [PMID: 22696004 PMCID: PMC3292648 DOI: 10.1007/s13244-011-0128-x] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/18/2011] [Accepted: 09/09/2011] [Indexed: 11/08/2022] Open
Abstract
Neuroinflammation is a process characterised by drastic changes in microglial morphology and by marked upregulation of the 18-kDa translocator protein (TSPO) on the mitochondria. The continual increase in incidence of neuroinflammation and neurodegenerative diseases poses a major health issue in many countries, requiring more innovative diagnostic and monitoring tools. TSPO expression may constitute a biomarker for brain inflammation that could be monitored by using TSPO tracers as neuroimaging agents. From medical imaging perspectives, this review focuses on the current concepts related to the TSPO, and discusses briefly on the status of its PET imaging related to neuroinflammation and neurodegenerative diseases in humans.
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Denora N, Laquintana V, Trapani A, Suzuki H, Sawada M, Trapani G. New fluorescent probes targeting the mitochondrial-located translocator protein 18 kDa (TSPO) as activated microglia imaging agents. Pharm Res 2011; 28:2820-32. [PMID: 21818711 DOI: 10.1007/s11095-011-0552-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 07/28/2011] [Indexed: 11/28/2022]
Abstract
PURPOSE To evaluate the utility of new Translocator protein 18 kDa (TSPO)-targeted fluorescent probes for in vivo molecular imaging of activated microglia. METHODS Compounds 2-4 were synthesized; their stability and affinity for TSPO were determined. Compounds 2-4 were incubated both with Ra2 cells in the presence of LPS, a potent activator of microglia, and with tissue sections of normal and chemically injured brains. Compounds 2-4 were injected into carotid artery or directly in striatum of mice. Cells and tissue sections from these in vitro and in vivo studies were observed by fluorescence microscopy after histochemical treatments. RESULTS Compounds 2-4 are stable in both buffer and physiological medium and showed high affinity for TSPO and were found to stain live Ra2 microglial cells effectively. Double staining with Mito Tracker Red suggested that binding sites of compounds 2 and 3 may exist on mitochondria. In vivo studies showed that compounds 2-4 may penetrate in part into brain; moreover, cells in mouse striatum were stained with compounds 2-4 and microglial marker CD11b. CONCLUSION Compounds 2-4 can fluorescently label activated microglia in vitro and in vivo.
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Affiliation(s)
- Nunzio Denora
- Dipartimento Farmaco-Chimico, Facoltà di Farmacia, Università degli Studi di Bari, Via Orabona 4, 70125 Bari, Italy
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Donohue SR, Dannals RF, Halldin C, Pike VW. N-(4-cyanotetrahydro-2H-pyran-4-yl) and N-(1-cyanocyclohexyl) derivatives of 1,5-diarylpyrazole-3-carboxamides showing high affinity for 18 kDa translocator protein and/or cannabinoid receptors. J Med Chem 2011; 54:2961-70. [PMID: 21428406 PMCID: PMC3085958 DOI: 10.1021/jm2000536] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In order to develop improved radioligands for imaging brain CB(1) receptors with positron emission tomography (PET) based on rimonabant (5-(4-chlorophenyl)-1-(2,4-dichlorophenyl)-4-methyl-N-(piperidin-1-yl)-1H-pyrazole-3-carboxamide, 1), we synthesized compounds 9a-s in which the N-piperidinyl ring was replaced with a 4-(4-cyanotetrahydro-2H-pyranyl) or 1-cyanocyclohexyl ring. Such changes were expected to be almost isosteric with 1, confer greater metabolic resistance, and in the case of the 4-(4-cyanotetrahydro-2H-pyranyl) compounds, substantially reduce lipophilicity. One derivative, 1-(2-bromophenyl)-N-(1-cyanocyclohexyl)-5-(4-methoxyphenyl)-4-methylpyrazole-3-carboxamide (9n), showed high affinity (K(i) = 15.7 nM) and selectivity for binding to CB(1) receptors. The corresponding 4-(4-cyanotetrahydro-2H-pyranyl) derivative (9m) also showed quite high affinity for CB(1) receptors (K(i) = 62 nM) but was found to have even higher affinity (K(i) = 29 nM) for the structurally unrelated 18 kDa translocator protein (TSPO). Some other minor structural changes among 9a-s were also found to switch binding selectivity from CB(1) receptors to TSPO or vice versa. These unexpected findings and their implications for the development of selective ligands or PET radioligands for CB(1) receptors or TSPO are discussed in relation to current pharmacophore models of CB(1) receptor and TSPO binding sites.
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Affiliation(s)
- Sean R. Donohue
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-1003, United States
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, S-17176, Stockholm, Sweden
- Division of Nuclear Medicine, The Johns Hopkins PET Center, Baltimore, Maryland 21287, United States
| | - Robert F. Dannals
- Division of Nuclear Medicine, The Johns Hopkins PET Center, Baltimore, Maryland 21287, United States
| | - Christer Halldin
- Karolinska Institutet, Department of Clinical Neuroscience, Psychiatry Section, Karolinska Hospital, S-17176, Stockholm, Sweden
| | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-1003, United States
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Zheng J, Boisgard R, Siquier-Pernet K, Decaudin D, Dollé F, Tavitian B. Differential Expression of the 18 kDa Translocator Protein (TSPO) by Neoplastic and Inflammatory Cells in Mouse Tumors of Breast Cancer. Mol Pharm 2011; 8:823-32. [DOI: 10.1021/mp100433c] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Jinzi Zheng
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
| | - Raphaël Boisgard
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
| | - Karine Siquier-Pernet
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
| | - Didier Decaudin
- Laboratory of Preclinical Investigation, Institut Curie, 26 rue d'Ulm, F-75248 Paris, France
| | - Frédéric Dollé
- Institut d'Imagerie BioMédicale, Service Hospitalier Frédéric Joliot, Commissariat a l'Énergie Atomique, 4 Place du Général Leclerc, F-91400, France
| | - Bertrand Tavitian
- Laboratoire d'Imagerie Moléculaire Expérimentale, Université Paris Sud, INSERM Unit 1023, 4 Place du Général Leclerc, F-91400 Orsay, France
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Suomalainen A. Biomarkers for mitochondrial respiratory chain disorders. J Inherit Metab Dis 2011; 34:277-82. [PMID: 20941643 DOI: 10.1007/s10545-010-9222-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 09/09/2010] [Accepted: 09/27/2010] [Indexed: 10/19/2022]
Abstract
Mitochondrial respiratory chain deficiencies are a group of more than 100 disorders of adults and children, with highly variable phenotypes. Their diagnosis is a great challenge, in spite of the fact that knowledge on their molecular genetic background has increased considerably during the last 20 years. Muscle biopsy is the key diagnostic procedure, including histological and biochemical analysis of mitochondria. Less invasive, specific and sensitive diagnostic tools based on serum biomarkers are still lacking. Recent technological developments, especially in mass spectrometry, enable novel tools for identification of local and global molecular consequences of mitochondrial respiratory chain dysfunction in patient samples. Furthermore, emerging disease models, especially genetically modified mice, offer unique materials to tackle pathophysiology with modern transcriptomic, proteomic, and metabolomic approaches. Identified molecular signals or metabolic fingerprints have the potential to be highly useful biomarkers for future diagnosis of mitochondrial respiratory chain disorders.
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Affiliation(s)
- Anu Suomalainen
- Research Program of Molecular Neurology, Biomedicum-Helsinki, r.C523B, University of Helsinki, Helsinki, Finland.
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Pike VW, Taliani S, Lohith TG, Owen DRJ, Pugliesi I, Da Pozzo E, Hong J, Zoghbi SS, Gunn RN, Parker CA, Rabiner EA, Fujita M, Innis RB, Martini C, Da Settimo F. Evaluation of novel N1-methyl-2-phenylindol-3-ylglyoxylamides as a new chemotype of 18 kDa translocator protein-selective ligand suitable for the development of positron emission tomography radioligands. J Med Chem 2010; 54:366-73. [PMID: 21133364 DOI: 10.1021/jm101230g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel series of N(1)-methyl-(2-phenylindol-3-yl)glyoxylamides, 19-31, designed in accordance with our previously reported pharmacophore/topological model, showed high affinity for the 18 kDa translocator protein (TSPO) and paved the way for developing a new radiolabeled probe. Thus ligand 31, N,N-di-n-propyl-(N(1)-methyl-2-(4'-nitrophenyl)indol-3-yl)glyoxylamide, featuring the best combination of affinity and lipophilicity, was labeled with carbon-11 for evaluation with positron emission tomography (PET) in monkey. After intravenous injection, [(11)C]31 entered brain to give a high proportion of TSPO-specific binding. These findings augur well for the future application of [(11)C]31 in humans. Consequently, the binding of 31 to human TSPO was tested on samples of brain membranes from deceased subjects who through ethically approved in vitro study had previously been established to be high-affinity binders (HABs), mixed-affinity binders (MABs), or low-affinity binders (LABs) for the known TSPO ligand, PBR28 (2). 31 showed high affinity for HABs, MABs, and LABs. In conclusion, [(11)C]31 represents a promising new chemotype for developing novel TSPO radioligands as biomarkers of neuroinflammation.
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Affiliation(s)
- Victor W Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892, United States.
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