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Chauveau F, Winkeler A, Chalon S, Boutin H, Becker G. PET imaging of neuroinflammation: any credible alternatives to TSPO yet? Mol Psychiatry 2024:10.1038/s41380-024-02656-9. [PMID: 38997465 DOI: 10.1038/s41380-024-02656-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 06/26/2024] [Accepted: 07/01/2024] [Indexed: 07/14/2024]
Abstract
Over the last decades, the role of neuroinflammation in neuropsychiatric conditions has attracted an exponentially growing interest. A key driver for this trend was the ability to image brain inflammation in vivo using PET radioligands targeting the Translocator Protein 18 kDa (TSPO), which is known to be expressed in activated microglia and astrocytes upon inflammatory events as well as constitutively in endothelial cells. TSPO is a mitochondrial protein that is expressed mostly by microglial cells upon activation but is also expressed by astrocytes in some conditions and constitutively by endothelial cells. Therefore, our current understanding of neuroinflammation dynamics is hampered by the lack of alternative targets available for PET imaging. We performed a systematic search and review on radiotracers developed for neuroinflammation PET imaging apart from TSPO. The following targets of interest were identified through literature screening (including previous narrative reviews): P2Y12R, P2X7R, CSF1R, COX (microglial targets), MAO-B, I2BS (astrocytic targets), CB2R & S1PRs (not specific of a single cell type). We determined the level of development and provided a scoping review for each target. Strikingly, astrocytic biomarker MAO-B has progressed in clinical investigations the furthest, while few radiotracers (notably targeting S1P1Rs, CSF1R) are being implemented in clinical investigations. Other targets such as CB2R and P2X7R have proven disappointing in clinical studies (e.g. poor signal, lack of changes in disease conditions, etc.). While astrocytic targets are promising, development of new biomarkers and tracers specific for microglial activation has proven challenging.
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Affiliation(s)
- Fabien Chauveau
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
| | - Alexandra Winkeler
- Université Paris-Saclay, Inserm, CNRS, CEA, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401, Orsay, France
| | - Sylvie Chalon
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France
| | - Hervé Boutin
- UMR 1253 iBrain, Université de Tours - INSERM, Bâtiment Planiol, UFR de Médecine, 10 Boulevard Tonnellé, 37032, Tours, Cedex 01, France.
| | - Guillaume Becker
- Université Claude Bernard Lyon 1, Centre de Recherche en Neurosciences de Lyon, Inserm U1028, CNRS UMR5292, BIORAN, Groupement Hospitalier Est - CERMEP, 59 boulevard Pinel, 69677, Bron, Cedex, France
- Agence Nationale de Sécurité Sanitaire de l'Alimentation, de l'Environnement et du Travail, 14 rue Pierre et Marie Curie, 94701, Maisons-Alfort, Cedex, France
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2
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Lee N, Choi JY, Ryu YH. The development status of PET radiotracers for evaluating neuroinflammation. Nucl Med Mol Imaging 2024; 58:160-176. [PMID: 38932754 PMCID: PMC11196502 DOI: 10.1007/s13139-023-00831-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/16/2023] [Accepted: 12/05/2023] [Indexed: 06/28/2024] Open
Abstract
Neuroinflammation is associated with the pathophysiologies of neurodegenerative and psychiatric disorders. Evaluating neuroinflammation using positron emission tomography (PET) plays an important role in the early diagnosis and determination of proper treatment of brain diseases. To quantify neuroinflammatory responses in vivo, many PET tracers have been developed using translocator proteins, imidazole-2 binding site, cyclooxygenase, monoamine oxidase-B, adenosine, cannabinoid, purinergic P2X7, and CSF-1 receptors as biomarkers. In this review, we introduce the latest developments in PET tracers that can image neuroinflammation, focusing on clinical trials, and further consider their current implications.
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Affiliation(s)
- Namhun Lee
- Division of Applied RI, Korea Institute of Radiological & Medical Sciences, 75 Nowon-ro, Nowon-gu, Seoul, 01812 Korea
| | - Jae Yong Choi
- Division of Applied RI, Korea Institute of Radiological & Medical Sciences, 75 Nowon-ro, Nowon-gu, Seoul, 01812 Korea
- Radiological and Medico-Oncological Sciences, University of Science and Technology (UST), Seoul, Korea
| | - Young Hoon Ryu
- Department of Nuclear Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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3
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Cai Y, Zhang Y, Leng S, Ma Y, Jiang Q, Wen Q, Ju S, Hu J. The relationship between inflammation, impaired glymphatic system, and neurodegenerative disorders: A vicious cycle. Neurobiol Dis 2024; 192:106426. [PMID: 38331353 DOI: 10.1016/j.nbd.2024.106426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Revised: 01/16/2024] [Accepted: 01/28/2024] [Indexed: 02/10/2024] Open
Abstract
The term "glymphatic" emerged roughly a decade ago, marking a pivotal point in neuroscience research. The glymphatic system, a glial-dependent perivascular network distributed throughout the brain, has since become a focal point of investigation. There is increasing evidence suggesting that impairment of the glymphatic system appears to be a common feature of neurodegenerative disorders, and this impairment exacerbates as disease progression. Nevertheless, the common factors contributing to glymphatic system dysfunction across most neurodegenerative disorders remain unclear. Inflammation, however, is suspected to play a pivotal role. Dysfunction of the glymphatic system can lead to a significant accumulation of protein and waste products, which can trigger inflammation. The interaction between the glymphatic system and inflammation appears to be cyclical and potentially synergistic. Yet, current research is limited, and there is a lack of comprehensive models explaining this association. In this perspective review, we propose a novel model suggesting that inflammation, impaired glymphatic function, and neurodegenerative disorders interconnected in a vicious cycle. By presenting experimental evidence from the existing literature, we aim to demonstrate that: (1) inflammation aggravates glymphatic system dysfunction, (2) the impaired glymphatic system exacerbated neurodegenerative disorders progression, (3) neurodegenerative disorders progression promotes inflammation. Finally, the implication of proposed model is discussed.
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Affiliation(s)
- Yu Cai
- Nurturing Center of Jiangsu Province for State Laboratory of AI Imaging & Interventional Radiology, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing 210009, China
| | - Yangqiqi Zhang
- School of Medicine, Southeast University, Nanjing 210009, China
| | - Shuo Leng
- Center of Interventional Radiology and Vascular Surgery, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, 87 Dingjiaqiao Road, Nanjing 210009, China
| | - Yuanyuan Ma
- Nurturing Center of Jiangsu Province for State Laboratory of AI Imaging & Interventional Radiology, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing 210009, China
| | - Quan Jiang
- Department of Neurology, Henry Ford Health System, 2799 W Grand Blvd, Detroit, MI 48202, USA
| | - Qiuting Wen
- Department of Radiology and Imaging Sciences, Indiana University School of Medicine, 355 W.16th Street, Indianapolis, IN 46202-5188, USA
| | - Shenghong Ju
- Nurturing Center of Jiangsu Province for State Laboratory of AI Imaging & Interventional Radiology, Department of Radiology, Zhongda Hospital, Medical School of Southeast University, Nanjing 210009, China.
| | - Jiani Hu
- Department of Radiology, School of Medicine, Wayne State University, Detroit, MI 48201, USA.
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4
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Etebar F, Harkin DG, White AR, Dando SJ. Non-invasive in vivo imaging of brain and retinal microglia in neurodegenerative diseases. Front Cell Neurosci 2024; 18:1355557. [PMID: 38348116 PMCID: PMC10859418 DOI: 10.3389/fncel.2024.1355557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 01/10/2024] [Indexed: 02/15/2024] Open
Abstract
Microglia play crucial roles in immune responses and contribute to fundamental biological processes within the central nervous system (CNS). In neurodegenerative diseases, microglia undergo functional changes and can have both protective and pathogenic roles. Microglia in the retina, as an extension of the CNS, have also been shown to be affected in many neurological diseases. While our understanding of how microglia contribute to pathological conditions is incomplete, non-invasive in vivo imaging of brain and retinal microglia in living subjects could provide valuable insights into their role in the neurodegenerative diseases and open new avenues for diagnostic biomarkers. This mini-review provides an overview of the current brain and retinal imaging tools for studying microglia in vivo. We focus on microglia targets, the advantages and limitations of in vivo microglia imaging approaches, and applications for evaluating the pathogenesis of neurological conditions, such as Alzheimer's disease and multiple sclerosis.
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Affiliation(s)
- Fazeleh Etebar
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
- Mental Health and Neuroscience Program, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Damien G. Harkin
- Centre for Vision and Eye Research, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
| | - Anthony R. White
- Mental Health and Neuroscience Program, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Samantha J. Dando
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
- Centre for Vision and Eye Research, School of Biomedical Sciences, Faculty of Health, Queensland University of Technology (QUT), Brisbane, QLD, Australia
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5
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Teodoro R, Gündel D, Deuther-Conrad W, Kazimir A, Toussaint M, Wenzel B, Bormans G, Hey-Hawkins E, Kopka K, Brust P, Moldovan RP. Synthesis, Structure-Activity Relationships, Radiofluorination, and Biological Evaluation of [ 18F]RM365, a Novel Radioligand for Imaging the Human Cannabinoid Receptor Type 2 (CB2R) in the Brain with PET. J Med Chem 2023; 66:13991-14010. [PMID: 37816245 PMCID: PMC10614203 DOI: 10.1021/acs.jmedchem.3c01035] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Indexed: 10/12/2023]
Abstract
The development of cannabinoid receptor type 2 (CB2R) PET radioligands has been intensively explored due to the pronounced CB2R upregulation under various pathological conditions. Herein, we report on the synthesis of a series of CB2R affine fluorinated indole-2-carboxamide ligands. Compound RM365 was selected for PET radiotracer development due to its high CB2R affinity (Ki = 2.1 nM) and selectivity over CB1R (factor > 300). Preliminary in vitro evaluation of [18F]RM365 indicated species differences in the binding to CB2R (KD of 2.32 nM for the hCB2R vs KD > 10,000 nM for the rCB2R). Metabolism studies in mice revealed a high in vivo stability of [18F]RM365. PET imaging in a rat model of local hCB2R(D80N) overexpression in the brain demonstrates the ability of [18F]RM365 to reach and selectively label the hCB2R(D80N) with a high signal-to-background ratio. Thus, [18F]RM365 is a very promising PET radioligand for the imaging of upregulated hCB2R expression under pathological conditions.
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Affiliation(s)
- Rodrigo Teodoro
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Daniel Gündel
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Winnie Deuther-Conrad
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Aleksandr Kazimir
- Faculty
of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Magali Toussaint
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Barbara Wenzel
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
| | - Guy Bormans
- Radiopharmaceutical
Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, BE-3000 Leuven, Belgium
| | - Evamarie Hey-Hawkins
- Faculty
of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Klaus Kopka
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
- Faculty
of Chemistry and Food Chemistry, School of Science, TU Dresden, 01069 Dresden, Germany
| | - Peter Brust
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
- The
Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig-Holstein, 23562 Lübeck, Germany
| | - Rareş-Petru Moldovan
- Institute
of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals,
Research Site Leipzig, Helmholtz-Zentrum
Dresden-Rossendorf (HZDR), 04318 Leipzig, Germany
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6
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Haider A, Wang L, Gobbi L, Li Y, Chaudhary A, Zhou X, Chen J, Zhao C, Rong J, Xiao Z, Hou L, Elghazawy NH, Sippl W, Davenport AT, Daunais JB, Ahmed H, Crowe R, Honer M, Rominger A, Grether U, Liang SH, Ametamey SM. Evaluation of [ 18F]RoSMA-18-d 6 as a CB2 PET Radioligand in Nonhuman Primates. ACS Chem Neurosci 2023; 14:3752-3760. [PMID: 37788055 DOI: 10.1021/acschemneuro.3c00222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/04/2023] Open
Abstract
The cannabinoid type 2 receptor (CB2) has been implicated in a variety of central and peripheral inflammatory diseases, prompting significant interest in the development of CB2-targeted diagnostic and therapeutic agents. A validated positron emission tomography (PET) radioligand for imaging CB2 in the living human brain as well as in peripheral tissues is currently lacking. As part of our research program, we have recently identified the trisubstituted pyridine, [18F]RoSMA-18-d6, which proved to be highly suitable for in vitro and in vivo mapping of CB2 in rodents. The aim of this study was to assess the performance characteristics of [18F]RoSMA-18-d6 in nonhuman primates (NHPs) to pave the way for clinical translation. [18F]RoSMA-18-d6 was synthesized from the respective tosylate precursor according to previously reported procedures. In vitro autoradiograms with NHP spleen tissue sections revealed a high binding of [18F]RoSMA-18-d6 to the CB2-rich NHP spleen, which was significantly blocked by coincubation with the commercially available CB2 ligand, GW405833 (10 μM). In contrast, no specific binding was observed by in vitro autoradiography with NHP brain sections, which was in agreement with the notion of a CB2-deficient healthy mammalian brain. In vitro findings were corroborated by PET imaging experiments in NHPs, where [18F]RoSMA-18-d6 uptake in the spleen was dose-dependently attenuated with 1 and 5 mg/kg GW405833, while no specific brain signal was observed. Remarkably, we observed tracer uptake and retention in the NHP spinal cord, which was reduced by GW405833 blockade, pointing toward a potential utility of [18F]RoSMA-18-d6 in probing CB2-expressing cells in the bone marrow. If these observations are substantiated in NHP models of enhanced leukocyte proliferation in the bone marrow, [18F]RoSMA-18-d6 may serve as a valuable marker for hematopoietic activity in various pathologies. In conclusion, [18F]RoSMA-18-d6 proved to be a suitable PET radioligand for imaging CB2 in NHPs, supporting its translation to humans.
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Affiliation(s)
- Ahmed Haider
- Department of Radiology, Division of Nuclear Medicine and Molecular Imaging Massachusetts General Hospital and Harvard Medical School, 55 Fruit Street, Boston, Massachusetts 02114, United States
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Lu Wang
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou 510630, China
| | - Luca Gobbi
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Yinlong Li
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Ahmad Chaudhary
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Xin Zhou
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Jiahui Chen
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Chunyu Zhao
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Jian Rong
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Zhiwei Xiao
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Lu Hou
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou 510630, China
| | - Nehal H Elghazawy
- Institute of Pharmacy, Department of Medicinal Chemistry, Martin-Luther-University Halle-Wittenberg, W.-Langenbeck-Str. 4, 06120 Halle, Germany
| | - Wolfgang Sippl
- Institute of Pharmacy, Department of Medicinal Chemistry, Martin-Luther-University Halle-Wittenberg, W.-Langenbeck-Str. 4, 06120 Halle, Germany
| | - April T Davenport
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157, United States
| | - James B Daunais
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston Salem, North Carolina 27157, United States
| | - Hazem Ahmed
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Institute of Pharmaceutical Sciences ETH, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
| | - Ron Crowe
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Michael Honer
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Axel Rominger
- Department of Nuclear Medicine, Bern University Hospital, 3010 Bern, Switzerland
| | - Uwe Grether
- Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche, 4070 Basel, Switzerland
| | - Steven H Liang
- Department of Radiology and Imaging Sciences, Emory University, 1364 Clifton Road, Atlanta, Georgia 30322, United States
| | - Simon M Ametamey
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Institute of Pharmaceutical Sciences ETH, Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
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7
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Cools R, Kerkhofs K, Leitao RCF, Bormans G. Preclinical Evaluation of Novel PET Probes for Dementia. Semin Nucl Med 2023; 53:599-629. [PMID: 37149435 DOI: 10.1053/j.semnuclmed.2023.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Accepted: 03/24/2023] [Indexed: 05/08/2023]
Abstract
The development of novel PET imaging agents that selectively bind specific dementia-related targets can contribute significantly to accurate, differential and early diagnosis of dementia causing diseases and support the development of therapeutic agents. Consequently, in recent years there has been a growing body of literature describing the development and evaluation of potential new promising PET tracers for dementia. This review article provides a comprehensive overview of novel dementia PET probes under development, classified by their target, and pinpoints their preclinical evaluation pathway, typically involving in silico, in vitro and ex/in vivo evaluation. Specific target-associated challenges and pitfalls, requiring extensive and well-designed preclinical experimental evaluation assays to enable successful clinical translation and avoid shortcomings observed for previously developed 'well-established' dementia PET tracers are highlighted in this review.
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Affiliation(s)
- Romy Cools
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Kobe Kerkhofs
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium; NURA, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium
| | - Renan C F Leitao
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
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8
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Singh P, Singh D, Srivastava P, Mishra G, Tiwari AK. Evaluation of advanced, pathophysiologic new targets for imaging of CNS. Drug Dev Res 2023; 84:484-513. [PMID: 36779375 DOI: 10.1002/ddr.22040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Revised: 12/12/2022] [Accepted: 12/31/2022] [Indexed: 02/14/2023]
Abstract
The inadequate information about the in vivo pathological, physiological, and neurological impairments, as well as the absence of in vivo tools for assessing brain penetrance and the efficiency of newly designed drugs, has hampered the development of new techniques for the treatment for variety of new central nervous system (CNS) diseases. The searching sites such as Science Direct and PubMed were used to find out the numerous distinct tracers across 16 CNS targets including tau, synaptic vesicle glycoprotein, the adenosine 2A receptor, the phosphodiesterase enzyme PDE10A, and the purinoceptor, among others. Among the most encouraging are [18 F]FIMX for mGluR imaging, [11 C]Martinostat for Histone deacetylase, [18 F]MNI-444 for adenosine 2A imaging, [11 C]ER176 for translocator protein, and [18 F]MK-6240 for tau imaging. We also reviewed the findings for each tracer's features and potential for application in CNS pathophysiology and therapeutic evaluation investigations, including target specificity, binding efficacy, and pharmacokinetic factors. This review aims to present a current evaluation of modern positron emission tomography tracers for CNS targets, with a focus on recent advances for targets that have newly emerged for imaging in humans.
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Affiliation(s)
- Priya Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Deepika Singh
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
| | - Pooja Srivastava
- Division of Cyclotron and Radiopharmaceuticals Sciences, Institute of Nuclear Medicine and Allied Sciences, Delhi, India
| | - Gauri Mishra
- Department of Zoology, Swami Shraddhananad College, University of Delhi, Alipur, Delhi, India
| | - Anjani K Tiwari
- Department of Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, Uttar Pradesh, India
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9
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Gündel D, Deuther-Conrad W, Ueberham L, Kaur S, Otikova E, Teodoro R, Toussaint M, Lai TH, Clauß O, Scheunemann M, Bormans G, Bachmann M, Kopka K, Brust P, Moldovan RP. Structure-Based Design, Optimization, and Development of [ 18F]LU13: A Novel Radioligand for Cannabinoid Receptor Type 2 Imaging in the Brain with PET. J Med Chem 2022; 65:9034-9049. [PMID: 35771668 DOI: 10.1021/acs.jmedchem.2c00256] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The cannabinoid receptor type 2 (CB2R) is an attractive target for the diagnosis and therapy of neurodegenerative diseases and cancer. In this study, we aimed at the development of a novel 18F-labeled radioligand starting from the structure of the known naphthyrid-2-one CB2R ligands. Compound 28 (LU13) was identified with the highest binding affinity and selectivity versus CB1R (CB2RKi = 0.6 nM; CB1RKi/CB2RKi > 1000) and was selected for radiolabeling with fluorine-18 and biological characterization. The new radioligand [18F]LU13 showed high CB2R affinity in vitro as well as high metabolic stability in vivo. PET imaging with [18F]LU13 in a rat model of vector-based/-related hCB2R overexpression in the striatum revealed a high signal-to-background ratio. Thus, [18F]LU13 is a novel and highly promising PET radioligand for the imaging of upregulated CB2R expression under pathological conditions in the brain.
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Affiliation(s)
- Daniel Gündel
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Winnie Deuther-Conrad
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Lea Ueberham
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Sarandeep Kaur
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Elina Otikova
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Rodrigo Teodoro
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Magali Toussaint
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Thu Hang Lai
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany.,Department of Research and Development, ROTOP Pharmaka GmbH, 01069 Dresden, Germany
| | - Oliver Clauß
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Matthias Scheunemann
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Guy Bormans
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, BE-3000 Leuven, Belgium
| | - Michael Bachmann
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
| | - Klaus Kopka
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany.,Faculty of Chemistry and Food Chemistry, School of Science, TU Dresden, 01069 Dresden, Germany
| | - Peter Brust
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany.,The Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig-Holstein, 23562 Lübeck, Germany
| | - Rareş-Petru Moldovan
- Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Research Site Leipzig, 04318 Leipzig, Germany
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10
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Chen Z, Haider A, Chen J, Xiao Z, Gobbi L, Honer M, Grether U, Arnold SE, Josephson L, Liang SH. The Repertoire of Small-Molecule PET Probes for Neuroinflammation Imaging: Challenges and Opportunities beyond TSPO. J Med Chem 2021; 64:17656-17689. [PMID: 34905377 PMCID: PMC9094091 DOI: 10.1021/acs.jmedchem.1c01571] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Neuroinflammation is an adaptive response of the central nervous system to diverse potentially injurious stimuli, which is closely associated with neurodegeneration and typically characterized by activation of microglia and astrocytes. As a noninvasive and translational molecular imaging tool, positron emission tomography (PET) could provide a better understanding of neuroinflammation and its role in neurodegenerative diseases. Ligands to translator protein (TSPO), a putative marker of neuroinflammation, have been the most commonly studied in this context, but they suffer from serious limitations. Herein we present a repertoire of different structural chemotypes and novel PET ligand design for classical and emerging neuroinflammatory targets beyond TSPO. We believe that this Perspective will support multidisciplinary collaborations in academic and industrial institutions working on neuroinflammation and facilitate the progress of neuroinflammation PET probe development for clinical use.
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Affiliation(s)
- Zhen Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Ahmed Haider
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Jiahui Chen
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Zhiwei Xiao
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Luca Gobbi
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Michael Honer
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Uwe Grether
- Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Steven E. Arnold
- Department of Neurology and the Massachusetts Alzheimer’s Disease Research Center, Massachusetts General Hospital, Harvard Medical School, 114 16th Street, Charlestown, Massachusetts 02129, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
| | - Steven H. Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, MA, 02114, United States
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11
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Van Camp N, Lavisse S, Roost P, Gubinelli F, Hillmer A, Boutin H. TSPO imaging in animal models of brain diseases. Eur J Nucl Med Mol Imaging 2021; 49:77-109. [PMID: 34245328 PMCID: PMC8712305 DOI: 10.1007/s00259-021-05379-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 04/25/2021] [Indexed: 12/19/2022]
Abstract
Over the last 30 years, the 18-kDa TSPO protein has been considered as the PET imaging biomarker of reference to measure increased neuroinflammation. Generally assumed to image activated microglia, TSPO has also been detected in endothelial cells and activated astrocytes. Here, we provide an exhaustive overview of the recent literature on the TSPO-PET imaging (i) in the search and development of new TSPO tracers and (ii) in the understanding of acute and chronic neuroinflammation in animal models of neurological disorders. Generally, studies testing new TSPO radiotracers against the prototypic [11C]-R-PK11195 or more recent competitors use models of acute focal neuroinflammation (e.g. stroke or lipopolysaccharide injection). These studies have led to the development of over 60 new tracers during the last 15 years. These studies highlighted that interpretation of TSPO-PET is easier in acute models of focal lesions, whereas in chronic models with lower or diffuse microglial activation, such as models of Alzheimer's disease or Parkinson's disease, TSPO quantification for detection of neuroinflammation is more challenging, mirroring what is observed in clinic. Moreover, technical limitations of preclinical scanners provide a drawback when studying modest neuroinflammation in small brains (e.g. in mice). Overall, this review underlines the value of TSPO imaging to study the time course or response to treatment of neuroinflammation in acute or chronic models of diseases. As such, TSPO remains the gold standard biomarker reference for neuroinflammation, waiting for new radioligands for other, more specific targets for neuroinflammatory processes and/or immune cells to emerge.
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Affiliation(s)
- Nadja Van Camp
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Sonia Lavisse
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Pauline Roost
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Francesco Gubinelli
- Université Paris-Saclay, CEA, CNRS, MIRCen, Laboratoire des Maladies Neurodégénératives, 92265, Fontenay-aux-Roses, France
| | - Ansel Hillmer
- Department of Psychiatry, Yale School of Medicine, New Haven, CT, USA
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale School of Engineering & Applied Science, New Haven, CT, USA
| | - Hervé Boutin
- Division of Neuroscience and Experimental Psychology, School of Biological Sciences, Faculty of Brain and Mental Health, University of Manchester, M13 9PL, Manchester, UK.
- Wolfson Molecular Imaging Centre, University of Manchester, 27 Palatine Road, M20 3LJ, Manchester, UK.
- Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Northern Care Alliance & University of Manchester, Manchester, UK.
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12
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Teodoro R, Gündel D, Deuther-Conrad W, Ueberham L, Toussaint M, Bormans G, Brust P, Moldovan RP. Development of [ 18F]LU14 for PET Imaging of Cannabinoid Receptor Type 2 in the Brain. Int J Mol Sci 2021; 22:ijms22158051. [PMID: 34360817 PMCID: PMC8347709 DOI: 10.3390/ijms22158051] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 12/16/2022] Open
Abstract
Cannabinoid receptors type 2 (CB2R) represent an attractive therapeutic target for neurodegenerative diseases and cancer. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor receptor density and/or occupancy during a CB2R-tailored therapy, we herein describe the radiosynthesis of cis-[18F]1-(4-fluorobutyl-N-((1s,4s)-4-methylcyclohexyl)-2-oxo-1,2-dihydro-1,8-naphthyridine-3-carboxamide ([18F]LU14) starting from the corresponding mesylate precursor. The first biological evaluation revealed that [18F]LU14 is a highly affine CB2R radioligand with >80% intact tracer in the brain at 30 min p.i. Its further evaluation by PET in a well-established rat model of CB2R overexpression demonstrated its ability to selectively image the CB2R in the brain and its potential as a tracer to further investigate disease-related changes in CB2R expression.
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Affiliation(s)
- Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Daniel Gündel
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Lea Ueberham
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Magali Toussaint
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
| | - Guy Bormans
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, BE-3000 Leuven, Belgium;
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
- The Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig-Holstein, 23562 Lübeck, Germany
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, 04318 Leipzig, Germany; (R.T.); (D.G.); (W.D.-C.); (L.U.); (M.T.); (P.B.)
- Correspondence: ; Tel.: +49-3412-3417-94634
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13
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Aly MW, Ludwig FA, Deuther-Conrad W, Brust P, Abadi AH, Moldovan RP, Osman NA. Development of fluorinated and methoxylated benzothiazole derivatives as highly potent and selective cannabinoid CB 2 receptor ligands. Bioorg Chem 2021; 114:105191. [PMID: 34375194 DOI: 10.1016/j.bioorg.2021.105191] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 07/15/2021] [Accepted: 07/16/2021] [Indexed: 11/25/2022]
Abstract
The upregulation of the CB2 receptors in neuroinflammation and cancer and their potential visualization with PET (positron emission tomography) could provide a valuable diagnostic and therapy-monitoring tool in such disorders. However, the availability of reliable CB2-selective imaging probes is still lacking in clinical practice. We have recently identified a benzothiazole-2-ylidine amide hit (6a) as a highly potent CB2 ligand. With the aim of enhancing its CB2 over CB1 selectivity and introducing structural sites suitable for radiolabeling, we herein describe the development of fluorinated and methoxylated benzothiazole derivatives endowed with extremely high CB2 binding affinity and an exclusive selectivity to the CB2 receptor. Compounds 14, 15, 18, 19, 21, 24 and 25 displayed subnanomolar CB2Ki values (ranging from 0.16 nM to 0.68 nM) and interestingly, all of the synthesized compounds completely lacked affinity at the CB1 receptor (Ki > 10,000 nM for all compounds), indicating their remarkably high CB2 over CB1 selectivity factors. The fluorinated analogs, 15 and 21, were evaluated for their in vitro metabolic stability in mouse and human liver microsomes (MLM and HLM). Both 15 and 21 displayed an exceptionally high stability (98% and 91% intact compounds, respectively) after 60 min incubation with MLM. Contrastingly, a 5- and 2.8-fold lower stability was demonstrated for compounds 15 and 21, respectively, upon incubation with HLM for 60 min. Taken together, our data present extremely potent and selective CB2 ligands as credible leads that can be further exploited for 18F- or 11C-radiolabeling and utilization as PET tracers.
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Affiliation(s)
- Mayar W Aly
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Egypt
| | - Friedrich-Alexander Ludwig
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, Leipzig 04318, Germany
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, Leipzig 04318, Germany
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, Leipzig 04318, Germany
| | - Ashraf H Abadi
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Egypt
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiopharmaceutical Cancer Research, Department of Neuroradiopharmaceuticals, Research Site Leipzig, Leipzig 04318, Germany.
| | - Noha A Osman
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy and Biotechnology, German University in Cairo, Egypt.
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14
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15
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Hou L, Rong J, Haider A, Ogasawara D, Varlow C, Schafroth MA, Mu L, Gan J, Xu H, Fowler CJ, Zhang MR, Vasdev N, Ametamey S, Cravatt BF, Wang L, Liang SH. Positron Emission Tomography Imaging of the Endocannabinoid System: Opportunities and Challenges in Radiotracer Development. J Med Chem 2020; 64:123-149. [PMID: 33379862 DOI: 10.1021/acs.jmedchem.0c01459] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The endocannabinoid system (ECS) is involved in a wide range of biological functions and comprises cannabinoid receptors and enzymes responsible for endocannabinoid synthesis and degradation. Over the past 2 decades, significant advances toward developing drugs and positron emission tomography (PET) tracers targeting different components of the ECS have been made. Herein, we summarized the recent development of PET tracers for imaging cannabinoid receptors 1 (CB1R) and 2 (CB2R) as well as the key enzymes monoacylglycerol lipase (MAGL) and fatty acid amide hydrolase (FAAH), particularly focusing on PET neuroimaging applications. State-of-the-art PET tracers for the ECS will be reviewed including their chemical design, pharmacological properties, radiolabeling, as well as preclinical and human PET imaging. In addition, this review addresses the current challenges for ECS PET biomarker development and highlights the important role of PET ligands to study disease pathophysiology as well as to facilitate drug discovery.
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Affiliation(s)
- Lu Hou
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Jian Rong
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Ahmed Haider
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Daisuke Ogasawara
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, SR107, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Cassis Varlow
- Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Department of Psychiatry/Institute of Medical Science, University of Toronto, 250 College Street, Toronto, M5T 1R8 ON, Canada
| | - Michael A Schafroth
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, SR107, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Linjing Mu
- Center for Radiopharmaceutical Sciences of ETH, PSI, and USZ, and Institute of Pharmaceutical Sciences, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Jiefeng Gan
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Hao Xu
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China
| | - Christopher J Fowler
- Department of Pharmacology and Clinical Neuroscience, Umeå University, SE-901 87 Umeå, Sweden
| | - Ming-Rong Zhang
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States.,Azrieli Centre for Neuro-Radiochemistry, Brain Health Imaging Centre, Centre for Addiction and Mental Health, and Department of Psychiatry/Institute of Medical Science, University of Toronto, 250 College Street, Toronto, M5T 1R8 ON, Canada
| | - Simon Ametamey
- Center for Radiopharmaceutical Sciences of ETH, PSI, and USZ, and Institute of Pharmaceutical Sciences, ETH Zurich, Vladimir-Prelog-Weg 4, CH-8093 Zurich, Switzerland
| | - Benjamin F Cravatt
- The Skaggs Institute for Chemical Biology and Department of Chemical Physiology, The Scripps Research Institute, SR107, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
| | - Lu Wang
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, 613 West Huangpu Road, Tianhe District, Guangzhou 510630, China.,Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, and Department of Radiology, Harvard Medical School, Boston, Massachusetts 02114, United States
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16
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Cipollina G, Davari Serej A, Di Nolfi G, Gazzano A, Marsala A, Spatafora MG, Peviani M. Heterogeneity of Neuroinflammatory Responses in Amyotrophic Lateral Sclerosis: A Challenge or an Opportunity? Int J Mol Sci 2020; 21:E7923. [PMID: 33113845 PMCID: PMC7662281 DOI: 10.3390/ijms21217923] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/21/2020] [Accepted: 10/22/2020] [Indexed: 02/06/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a complex pathology: (i) the neurodegeneration is chronic and progressive; it starts focally in specific central nervous system (CNS) areas and spreads to different districts; (ii) multiple cell types further than motor neurons (i.e., glial/immune system cells) are actively involved in the disease; (iii) both neurosupportive and neurotoxic neuroinflammatory responses were identified. Microglia cells (a key player of neuroinflammation in the CNS) attracted great interest as potential target cell population that could be modulated to counteract disease progression, at least in preclinical ALS models. However, the heterogeneous/multifaceted microglia cell responses occurring in different CNS districts during the disease represent a hurdle for clinical translation of single-drug therapies. To address this issue, over the past ten years, several studies attempted to dissect the complexity of microglia responses in ALS. In this review, we shall summarize these results highlighting how the heterogeneous signature displayed by ALS microglia reflects not only the extent of neuronal demise in different regions of the CNS, but also variable engagement in the attempts to cope with the neuronal damage. We shall discuss novel avenues opened by the advent of single-cell and spatial transcriptomics technologies, underlining the potential for discovery of novel therapeutic targets, as well as more specific diagnostic/prognostic not-invasive markers of neuroinflammation.
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Affiliation(s)
| | | | | | | | | | | | - Marco Peviani
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, via Ferrata 9, 27100 Pavia, Italy; (G.C.); (A.D.S.); (G.D.N.); (A.G.); (A.M.); (M.G.S.)
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17
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Harms AS, Kordower JH, Sette A, Lindestam Arlehamn CS, Sulzer D, Mach RH. Inflammation in Experimental Models of α-Synucleinopathies. Mov Disord 2020; 36:37-49. [PMID: 33009855 DOI: 10.1002/mds.28264] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 05/29/2020] [Accepted: 06/17/2020] [Indexed: 12/11/2022] Open
Abstract
Neuroinflammation has long been associated with central nervous system pathology in α-synucleinopathy disorders including Parkinson's disease and multiple system atrophy. In the past decade, research-focused efforts in preclinical and experimental models have rallied around this idea, and considerable effort has been made to delineate critical neuroinflammatory processes. In this article, we discuss challenges in preclinical research, notably the use of animal models to recapitulate and dissect disease phenotypes as well as the need for more sensitive, reliable radiotracers to detect on-target efficacy of immunomodulatory treatments in both human Parkinson's disease as well as preclinical models. © 2020 International Parkinson and Movement Disorder Society.
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Affiliation(s)
- Ashley S Harms
- Department of Neurology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jeffrey H Kordower
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA
| | - Alessandro Sette
- Division of Vaccine Discovery, La Jolla Institute for Immunology, La Jolla, California, USA.,Department of Medicine, University of California, San Diego, La Jolla, California, USA
| | | | - David Sulzer
- Department of Neurology, Columbia University Medical Center, New York, New York, USA.,Department of Psychiatry, Columbia University Medical Center, New York, New York, USA.,Department of Pharmacology, Columbia University Medical Center, New York, New York, USA
| | - Robert H Mach
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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18
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Positron Emission Tomography in the Inflamed Cerebellum: Addressing Novel Targets among G Protein-Coupled Receptors and Immune Receptors. Pharmaceutics 2020; 12:pharmaceutics12100925. [PMID: 32998351 PMCID: PMC7601272 DOI: 10.3390/pharmaceutics12100925] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 09/17/2020] [Accepted: 09/25/2020] [Indexed: 01/12/2023] Open
Abstract
Inflammatory processes preceding clinical manifestation of brain diseases are moving increasingly into the focus of positron emission tomographic (PET) investigations. A key role in inflammation and as a target of PET imaging efforts is attributed to microglia. Cerebellar microglia, with a predominant ameboid and activated subtype, is of special interest also regarding improved and changing knowledge on functional involvement of the cerebellum in mental activities in addition to its regulatory role in motor function. The present contribution considers small molecule ligands as potential PET tools for the visualization of several receptors recognized to be overexpressed in microglia and which can potentially serve as indicators of inflammatory processes in the cerebellum. The sphingosine 1 phosphate receptor 1 (S1P1), neuropeptide Y receptor 2 (NPY2) and purinoceptor Y12 (P2Y12) cannabinoid receptors and the chemokine receptor CX3CR1 as G-protein-coupled receptors and the ionotropic purinoceptor P2X7 provide structures with rather classical binding behavior, while the immune receptor for advanced glycation end products (RAGE) and the triggering receptor expressed on myeloid cells 2 (TREM2) might depend for instance on further accessory proteins. Improvement in differentiation between microglial functional subtypes in comparison to the presently used 18 kDa translocator protein ligands as well as of the knowledge on the role of polymorphisms are special challenges in such developments.
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19
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Basagni F, Rosini M, Decker M. Functionalized Cannabinoid Subtype 2 Receptor Ligands: Fluorescent, PET, Photochromic and Covalent Molecular Probes. ChemMedChem 2020; 15:1374-1389. [PMID: 32578963 PMCID: PMC7497013 DOI: 10.1002/cmdc.202000298] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Indexed: 01/01/2023]
Abstract
Cannabinoid subtype 2 receptors (CB2 Rs) are G protein-coupled receptors (GPCRs) belonging to the endocannabinoid system, a complex network of signalling pathways leading to the regulation of key physiological processes. Interestingly, CB2 Rs are strongly up-regulated in pathological conditions correlated with the onset of inflammatory events like cancer and neurodegenerative diseases. Therefore, CB2 Rs represent an important biological target for therapeutic as well as diagnostic purposes. No CB2 R-selective drugs are yet on the market, thus underlining a that deeper comprehension of CB2 Rs' complex activation pathways and their role in the regulation of diseases is needed. Herein, we report an overview of pharmacological and imaging tools such as fluorescent, positron emission tomography (PET), photochromic and covalent selective CB2 R ligands. These molecular probes can be used in vitro as well as in vivo to investigate and explore the unravelled role(s) of CB2 Rs, and they can help to design suitable CB2 R-targeted drugs.
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Affiliation(s)
- Filippo Basagni
- Pharmaceutical and Medicinal Chemistry Institute of Pharmacy and Food ChemistryJulius Maximilian University of WürzburgAm Hubland97074WürzburgGermany
- Department of Pharmacy and BiotechnologyUniversity of BolognaVia Belmeloro 640126BolognaItaly
| | - Michela Rosini
- Department of Pharmacy and BiotechnologyUniversity of BolognaVia Belmeloro 640126BolognaItaly
| | - Michael Decker
- Pharmaceutical and Medicinal Chemistry Institute of Pharmacy and Food ChemistryJulius Maximilian University of WürzburgAm Hubland97074WürzburgGermany
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20
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Cannabinoids in the Pathophysiology of Skin Inflammation. Molecules 2020; 25:molecules25030652. [PMID: 32033005 PMCID: PMC7037408 DOI: 10.3390/molecules25030652] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/26/2020] [Accepted: 02/02/2020] [Indexed: 12/22/2022] Open
Abstract
Cannabinoids are increasingly-used substances in the treatment of chronic pain, some neuropsychiatric disorders and more recently, skin disorders with an inflammatory component. However, various studies cite conflicting results concerning the cellular mechanisms involved, while others suggest that cannabinoids may even exert pro-inflammatory behaviors. This paper aims to detail and clarify the complex workings of cannabinoids in the molecular setting of the main dermatological inflammatory diseases, and their interactions with other substances with emerging applications in the treatment of these conditions. Also, the potential role of cannabinoids as antitumoral drugs is explored in relation to the inflammatory component of skin cancer. In vivo and in vitro studies that employed either phyto-, endo-, or synthetic cannabinoids were considered in this paper. Cannabinoids are regarded with growing interest as eligible drugs in the treatment of skin inflammatory conditions, with potential anticancer effects, and the readiness in monitoring of effects and the facility of topical application may contribute to the growing support of the use of these substances. Despite the promising early results, further controlled human studies are required to establish the definitive role of these products in the pathophysiology of skin inflammation and their usefulness in the clinical setting.
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Yamagishi S, Iga Y, Nakamura M, Takizawa C, Fukumoto D, Kakiuchi T, Nishiyama S, Ohba H, Tsukada H, Sato K, Ouchi Y. Upregulation of cannabinoid receptor type 2, but not TSPO, in senescence-accelerated neuroinflammation in mice: a positron emission tomography study. J Neuroinflammation 2019; 16:208. [PMID: 31707986 PMCID: PMC6842455 DOI: 10.1186/s12974-019-1604-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 09/26/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microglial cells are activated in response to changes in brain homeostasis during aging, dementia, and stroke. Type 2 endocannabinoid receptors (CB2) and translocator protein 18 kD (TSPO) are considered to reflect distinct aspects of microglia-related neuroinflammatory responses in the brain. CB2 activation is considered to relate to the neuroprotective responses that may occur predominantly in the early stage of brain disorders such as Alzheimer's disease, while an increase in TSPO expression tends to occur later during neuroinflammation, in a proinflammatory fashion. However, this information was deduced from studies with different animal samples under different experimental settings. In this study, we aimed to examine the early microglial status in the inflammation occurring in the brains of senescence-accelerated mouse prone 10 (SAMP10) mice, using positron emission tomography (PET) with CB2 and TSPO tracers, together with immunohistochemistry. METHODS Five- and 15-week-old SAMP10 mice that undergo neurodegeneration after 7 months of age were used. The binding levels of the TSPO tracer (R)-[11C]PK11195 and CB2 tracer [11C]NE40 were measured using PET in combination with immunohistochemistry for CB2 and TSPO. To our knowledge, this is the first study to report PET data for CB2 and TSPO at the early stage of cognitive impairment in an animal model. RESULTS The standard uptake value ratios (SUVRs) of [11C]NE40 binding were significantly higher than those of (R)-[11C]PK11195 binding in the cerebral cortical region at 15 weeks of age. At 5 weeks of age, the [11C]NE40 SUVR tended to be higher than the (R)-[11C]PK11195 SUVR. The (R)-[11C]PK11195 SUVR did not significantly differ between 5- and 15-week-old mice. Consistently, immunostaining analysis confirmed the upregulation of CB2, but not TSPO. CONCLUSIONS The use of the CB2 tracer [11C]NE40 and/or an immunohistochemical approach allows evaluation of the role of microglia in acute neuroinflammatory processes in the early stage of neurodegeneration. The present results provide in vivo evidence of different responses of two types of microglia to senescence-accelerated neuroinflammation, implying the perturbation of microglial balance by aging. Specific treatment for CB2-positive microglia might help ameliorate senescence-related neuroinflammation and the following neurodegeneration.
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Affiliation(s)
- Satoru Yamagishi
- Department of Organ and Tissue Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Yurika Iga
- Department of Organ and Tissue Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Masato Nakamura
- Department of Organ and Tissue Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Chika Takizawa
- Department of Organ and Tissue Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Dai Fukumoto
- Central Research Laboratory, Hamamatsu Photonics KK, Hamamatsu, Japan
| | - Takeharu Kakiuchi
- Central Research Laboratory, Hamamatsu Photonics KK, Hamamatsu, Japan
| | - Shingo Nishiyama
- Central Research Laboratory, Hamamatsu Photonics KK, Hamamatsu, Japan
| | - Hiroyuki Ohba
- Central Research Laboratory, Hamamatsu Photonics KK, Hamamatsu, Japan
| | - Hideo Tsukada
- Central Research Laboratory, Hamamatsu Photonics KK, Hamamatsu, Japan
| | - Kohji Sato
- Department of Organ and Tissue Anatomy, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Yasuomi Ouchi
- Department of Biofunctional Imaging, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan.
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22
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Kallinen A, Boyd R, Lane S, Bhalla R, Mardon K, Stimson DHR, Werry EL, Fulton R, Connor M, Kassiou M. Synthesis and in vitro evaluation of fluorine-18 benzimidazole sulfones as CB2 PET-radioligands. Org Biomol Chem 2019; 17:5086-5098. [PMID: 31070218 DOI: 10.1039/c9ob00656g] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Cannabinoid type 2 receptor (CB2) is up-regulated on activated microglial cells and can potentially be used as a biomarker for PET-imaging of neuroinflammation. In this study the synthesis and pharmacological evaluation of novel fluorinated pyridyl and ethyl sulfone analogues of 2-(tert-butyl)-5-((2-fluoropyridin-4-yl)sulfonyl)-1-(2-methylpentyl)-1H-benzo[d]imidazole (rac-1a) are described. In general, the ligands showed low nanomolar potency (CB2 EC50 < 10 nM) and excellent selectivity over the CB1 subtype (>10 000×). Selected ligands 1d, 1e, 1g and 3l showing high CB2 binding affinity (Ki < 10 nM) were radiolabelled with fluorine-18 from chloropyridyl and alkyl tosylate precursors with good to high isolated radioactive yields (25-44%, non-decay corrected, at the end of synthesis). CB2-specific binding of the radioligand candidates [18F]-1d and [18F]-3l was assessed on rat spleen cryosections using in vitro autoradiography. The results warrant further in vivo evaluation of the tracer candidates as prospective CB2 PET-imaging agents.
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Affiliation(s)
- Annukka Kallinen
- School of Chemistry, The University of Sydney, NSW 2006, Australia.
| | - Rochelle Boyd
- Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW 2109, Australia
| | - Samuel Lane
- Faculty of Health Sciences, The University of Sydney, NSW 2050, Australia
| | - Rajiv Bhalla
- The Centre for Advanced Imaging, The University of Queensland, QLD 4072, Australia
| | - Karine Mardon
- The Centre for Advanced Imaging, The University of Queensland, QLD 4072, Australia
| | - Damion H R Stimson
- The Centre for Advanced Imaging, The University of Queensland, QLD 4072, Australia
| | - Eryn L Werry
- School of Chemistry, The University of Sydney, NSW 2006, Australia.
| | - Roger Fulton
- Faculty of Health Sciences, The University of Sydney, NSW 2050, Australia
| | - Mark Connor
- Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, NSW 2109, Australia
| | - Michael Kassiou
- School of Chemistry, The University of Sydney, NSW 2006, Australia.
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23
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Bauckneht M, Capitanio S, Raffa S, Roccatagliata L, Pardini M, Lapucci C, Marini C, Sambuceti G, Inglese M, Gallo P, Cecchin D, Nobili F, Morbelli S. Molecular imaging of multiple sclerosis: from the clinical demand to novel radiotracers. EJNMMI Radiopharm Chem 2019; 4:6. [PMID: 31659498 PMCID: PMC6453990 DOI: 10.1186/s41181-019-0058-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 03/21/2019] [Indexed: 12/13/2022] Open
Abstract
Background Brain PET imaging with different tracers is mainly clinically used in the field of neurodegenerative diseases and brain tumors. In recent years, the potential usefulness of PET has also gained attention in the field of MS. In fact, MS is a complex disease and several processes can be selected as a target for PET imaging. The use of PET with several different tracers has been mainly evaluated in the research setting to investigate disease pathophysiology (i.e. phenotypes, monitoring of progression) or to explore its use a surrogate end-point in clinical trials. Results We have reviewed PET imaging studies in MS in humans and animal models. Tracers have been grouped according to their pathophysiological targets (ie. tracers for myelin kinetic, neuroinflammation, and neurodegeneration). The emerging clinical indication for brain PET imaging in the differential diagnosis of suspected tumefactive demyelinated plaques as well as the clinical potential provided by PET images in view of the recent introduction of PET/MR technology are also addressed. Conclusion While several preclinical and fewer clinical studies have shown results, full-scale clinical development programs are needed to translate molecular imaging technologies into a clinical reality that could ideally fit into current precision medicine perspectives.
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Affiliation(s)
- Matteo Bauckneht
- Nuclear Medicine Unit, IRCCS Ospedale Policlinico San Martino, Largo R. Benzi 10, 16132, Genoa, Italy.
| | - Selene Capitanio
- Nuclear Medicine Unit, IRCCS Ospedale Policlinico San Martino, Largo R. Benzi 10, 16132, Genoa, Italy
| | - Stefano Raffa
- Department of Health Sciences (DISSAL), University of Genova, Genoa, Italy
| | - Luca Roccatagliata
- Department of Health Sciences (DISSAL), University of Genova, Genoa, Italy.,Neuroradiology, IRCCS Ospedale Policlinico San Martino, Genoa, Italy
| | - Matteo Pardini
- Clinical Neurology, Department of Neuroscience (DINOGMI), University of Genoa, Genoa, Italy.,Clinica Neurologica, IRCCS Ospedale Policlinico, San Martino, Genoa, Italy
| | - Caterina Lapucci
- Clinical Neurology, Department of Neuroscience (DINOGMI), University of Genoa, Genoa, Italy
| | - Cecilia Marini
- Nuclear Medicine Unit, IRCCS Ospedale Policlinico San Martino, Largo R. Benzi 10, 16132, Genoa, Italy.,CNR Institute of Molecular Bioimaging and Physiology, Milan, Italy
| | - Gianmario Sambuceti
- Nuclear Medicine Unit, IRCCS Ospedale Policlinico San Martino, Largo R. Benzi 10, 16132, Genoa, Italy.,Department of Health Sciences (DISSAL), University of Genova, Genoa, Italy
| | - Matilde Inglese
- Clinical Neurology, Department of Neuroscience (DINOGMI), University of Genoa, Genoa, Italy.,Clinica Neurologica, IRCCS Ospedale Policlinico, San Martino, Genoa, Italy
| | - Paolo Gallo
- Multiple Sclerosis Centre of the Veneto Region, Department of Neurosciences DNS, University of Padua, Padua, Italy
| | - Diego Cecchin
- Nuclear Medicine Unit, Department of Medicine-DIMED, Padova University Hospital, Padua, Italy.,Padua Neuroscience Center, University of Padua, Padua, Italy
| | - Flavio Nobili
- Clinical Neurology, Department of Neuroscience (DINOGMI), University of Genoa, Genoa, Italy.,Clinica Neurologica, IRCCS Ospedale Policlinico, San Martino, Genoa, Italy
| | - Silvia Morbelli
- Nuclear Medicine Unit, IRCCS Ospedale Policlinico San Martino, Largo R. Benzi 10, 16132, Genoa, Italy.,Department of Health Sciences (DISSAL), University of Genova, Genoa, Italy
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24
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Ni R, Mu L, Ametamey S. Positron emission tomography of type 2 cannabinoid receptors for detecting inflammation in the central nervous system. Acta Pharmacol Sin 2019; 40:351-357. [PMID: 29921889 PMCID: PMC6460366 DOI: 10.1038/s41401-018-0035-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2017] [Accepted: 05/01/2018] [Indexed: 02/06/2023] Open
Abstract
Cannabinoid receptor CB2 (CB2R) is upregulated on activated microglia and astrocytes in the brain under inflammatory conditions and plays important roles in many neurological diseases, such as Alzheimer's disease, amyotrophic lateral sclerosis, and ischemic stroke. The advent of positron emission tomography (PET) using CB2R radiotracers has enabled the visualization of CB2R distribution in vivo in animal models of central nervous system inflammation, however translation to humans has been less successful. Several novel CB2R radiotracers have been developed and evaluated to quantify microglial activation. In this review, we summarize the recent preclinical and clinical imaging results of CB2R PET tracers and discuss the prospects of CB2R imaging using PET.
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Affiliation(s)
- Ruiqing Ni
- Department of Chemistry and Applied Biosciences, Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, 8093, Switzerland.
| | - Linjing Mu
- Department of Chemistry and Applied Biosciences, Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, 8093, Switzerland
- Department of Nuclear Medicine, University Hospital Zurich, Zurich, 8091, Switzerland
| | - Simon Ametamey
- Department of Chemistry and Applied Biosciences, Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, 8093, Switzerland
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25
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Attili B, Celen S, Ahamed M, Koole M, Haute CVD, Vanduffel W, Bormans G. Preclinical evaluation of [ 18 F]MA3: a CB 2 receptor agonist radiotracer for PET. Br J Pharmacol 2019; 176:1481-1491. [PMID: 30588600 DOI: 10.1111/bph.14564] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 10/31/2018] [Accepted: 11/16/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Non-invasive in vivo imaging of cannabinoid CB2 receptors using PET is pursued to study neuroinflammation. The purpose of this study is to evaluate the in vivo binding specificity of [18 F]MA3, a CB2 receptor agonist, in a rat model with local overexpression of human (h) CB2 receptors. METHODS [18 F]MA3 was produced with good radiochemical yield and radiochemical purity. The radiotracer was evaluated in rats with local overexpression of hCB2 receptors and in a healthy non-human primate using PET. KEY RESULTS Ex vivo autoradiography demonstrated CB2 -specific binding of [18 F]MA3 in rat hCB2 receptor vector injected striatum. In a PET study, increased tracer binding in the hCB2 receptor vector-injected striatum compared to the contralateral control vector-injected striatum was observed. Binding in hCB2 receptor vector-injected striatum was blocked with a structurally non-related CB2 receptor inverse agonist, and a displacement study confirmed the reversibility of tracer binding. This study identified the utility of mutated inactive vector model for evaluation of CB2 receptor agonist PET tracers. [18 F]MA3 PET scans in the non-human primate showed good uptake and fast washout from brain, but no CB2 receptor-specific binding was observed. CONCLUSION AND IMPLICATIONS Evaluation of [18 F]MA3 in a rat model with local overexpression of hCB2 receptors showed CB2 receptor-specific and reversible tracer binding. [18 F]MA3 showed good brain uptake and subsequent washout in a healthy non-human primate, but no specific binding was observed. Further clinical evaluation of [18 F]MA3 in patients with neuroinflammation is warranted. LINKED ARTICLES This article is part of a themed section on 8th European Workshop on Cannabinoid Research. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.10/issuetoc.
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Affiliation(s)
- Bala Attili
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Sofie Celen
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Muneer Ahamed
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Michel Koole
- Department of Nuclear Medicine and Molecular Imaging, UZ Gasthuisberg, Leuven, Belgium
| | - Chris Van Den Haute
- Laboratory for Neurobiology and Gene Therapy, Department of Neurosciences, KU Leuven, Leuven, Belgium.,Leuven Viral Vector Core, Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Wim Vanduffel
- Laboratory for Neuro- and Psychophysiology, Department of Neurosciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Radiopharmaceutical Research, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
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26
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Development of brain PET imaging agents: Strategies for imaging neuroinflammation in Alzheimer's disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 165:371-399. [DOI: 10.1016/bs.pmbts.2019.04.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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27
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Abstract
Neuroinflammation, which involves microglial activation, is thought to play a key role in the development and progression of neurodegenerative diseases and other brain pathologies. Positron emission tomography is an ideal imaging technique for studying biochemical processes in vivo, and particularly for studying the living brain. Neuroinflammation has been traditionally studied using radiotracers targeting the translocator protein 18 kDa, but this comes with certain limitations. The current review describes alternative biological targets that have gained interest for the imaging of microglial activation over recent years, such as the cannabinoid receptor type 2, cyclooxygenase-2, the P2X₇ receptor and reactive oxygen species, and some promising radiotracers for these targets. Although many advances have been made in the field of neuroinflammation imaging, current radiotracers all target the pro-inflammatory (M1) phenotype of activated microglia, since the number of known biological targets specific for the anti-inflammatory (M2) phenotype that are also suited as a target for radiotracer development is still limited. Next to proceeding the currently available tracers for M1 microglia into the clinic, the development of a suitable radiotracer for M2 microglia would mean a great advance in the field, as this would allow for imaging of the dynamics of microglial activation in different diseases.
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Affiliation(s)
- Bieneke Janssen
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Danielle J Vugts
- Department of Radiology & Nuclear Medicine, VU University Medical Center, 1081 HV Amsterdam, The Netherlands.
| | - Albert D Windhorst
- Department of Radiology & Nuclear Medicine, VU University Medical Center, 1081 HV Amsterdam, The Netherlands.
| | - Robert H Mach
- Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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28
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Narayanaswami V, Dahl K, Bernard-Gauthier V, Josephson L, Cumming P, Vasdev N. Emerging PET Radiotracers and Targets for Imaging of Neuroinflammation in Neurodegenerative Diseases: Outlook Beyond TSPO. Mol Imaging 2018; 17:1536012118792317. [PMID: 30203712 PMCID: PMC6134492 DOI: 10.1177/1536012118792317] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 05/31/2018] [Accepted: 07/09/2018] [Indexed: 11/16/2022] Open
Abstract
The dynamic and multicellular processes of neuroinflammation are mediated by the nonneuronal cells of the central nervous system, which include astrocytes and the brain's resident macrophages, microglia. Although initiation of an inflammatory response may be beneficial in response to injury of the nervous system, chronic or maladaptive neuroinflammation can have harmful outcomes in many neurological diseases. An acute neuroinflammatory response is protective when activated neuroglia facilitate tissue repair by releasing anti-inflammatory cytokines and neurotrophic factors. On the other hand, chronic neuroglial activation is a major pathological mechanism in neurodegenerative diseases, likely contributing to neuronal dysfunction, injury, and disease progression. Therefore, the development of specific and sensitive probes for positron emission tomography (PET) studies of neuroinflammation is attracting immense scientific and clinical interest. An early phase of this research emphasized PET studies of the prototypical imaging biomarker of glial activation, translocator protein-18 kDa (TSPO), which presents difficulties for quantitation and lacks absolute cellular specificity. Many alternate molecular targets present themselves for PET imaging of neuroinflammation in vivo, including enzymes, intracellular signaling molecules as well as ionotropic, G-protein coupled, and immunoglobulin receptors. We now review the lead structures in radiotracer development for PET studies of neuroinflammation targets for neurodegenerative diseases extending beyond TSPO, including glycogen synthase kinase 3, monoamine oxidase-B, reactive oxygen species, imidazoline-2 binding sites, cyclooxygenase, the phospholipase A2/arachidonic acid pathway, sphingosine-1-phosphate receptor-1, cannabinoid-2 receptor, the chemokine receptor CX3CR1, purinergic receptors: P2X7 and P2Y12, the receptor for advanced glycation end products, Mer tyrosine kinase, and triggering receptor expressed on myeloid cells-1. We provide a brief overview of the cellular expression and function of these targets, noting their selectivity for astrocytes and/or microglia, and highlight the classes of PET radiotracers that have been investigated in early-stage preclinical or clinical research studies of neuroinflammation.
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Affiliation(s)
- Vidya Narayanaswami
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Kenneth Dahl
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Vadim Bernard-Gauthier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Paul Cumming
- School of Psychology and Counselling and IHBI, Queensland University of Technology, Brisbane, Queensland, Australia
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Department of Radiology, Harvard Medical School, Boston, MA, USA
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29
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Spinelli F, Mu L, Ametamey SM. Radioligands for positron emission tomography imaging of cannabinoid type 2 receptor. J Labelled Comp Radiopharm 2017; 61:299-308. [PMID: 29110331 DOI: 10.1002/jlcr.3579] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Revised: 10/10/2017] [Accepted: 10/24/2017] [Indexed: 01/11/2023]
Abstract
The cannabinoid type 2 (CB2) receptor is an immunomodulatory receptor mainly expressed in peripheral cells and organs of the immune system. The expression level of CB2 in the central nervous system under physiological conditions is negligible, however under neuroinflammatory conditions an upregulation of CB2 protein or mRNA mainly colocalized with activated microglial cells has been reported. Consequently, CB2 agonists have been confirmed to play a role in neuroprotective and anti-inflammatory processes. A suitable positron emission tomography radioligand for imaging CB2 would provide an invaluable research tool to explore the role of CB2 receptor expression in inflammatory disorders. In this review, we provide a summary of so far published CB2 radioligands as well as their in vitro and in vivo binding characteristics.
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Affiliation(s)
- Francesco Spinelli
- Department of Pharmacy-Pharmaceutical Sciences, University of Bari "A. Moro", Bari, Italy.,Department of Chemistry and Applied Biosciences, Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Linjing Mu
- Department of Nuclear Medicine, Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, University Hospital Zurich, Zurich, Switzerland
| | - Simon M Ametamey
- Department of Chemistry and Applied Biosciences, Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
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30
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Caillé F, Cacheux F, Peyronneau MA, Jego B, Jaumain E, Pottier G, Ullmer C, Grether U, Winkeler A, Dollé F, Damont A, Kuhnast B. From Structure-Activity Relationships on Thiazole Derivatives to the In Vivo Evaluation of a New Radiotracer for Cannabinoid Subtype 2 PET Imaging. Mol Pharm 2017; 14:4064-4078. [PMID: 28968497 DOI: 10.1021/acs.molpharmaceut.7b00746] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Upregulation of the cannabinoid type 2 receptors (CB2R) unveils inflammation processes of pathological disorders, such as cancer, pain, or neurodegenerative diseases. Among others, CB2R agonist A-836339 has been labeled with carbon-11 for PET imaging of the CB2R and displayed promising results in a mouse model of Alzheimer's disease. The aim of the present work was to develop fluorinated analogs of A-836339 for labeling with fluorine-18 to design a new PET tracer for CB2R imaging. Seven fluorinated analogs of A-836339 were synthesized in two to three steps and their binding affinities and selectivities for both the human and the mouse CB2R were measured as well as their early ADME profiles. Among them, compound 2f (KihCB2R = 0.1 nM, KihCB1R/KihCB2R = 300) displayed high affinity and selectivity for CB2R but also promising lipophilicity, kinetic solubility, and membrane permeation properties and was further selected for in vitro metabolism studies. Incubation of 2f with human or rat liver microsomes followed by LC/MS analysis revealed the presence of six different metabolites mainly resulting from oxidation reactions. A tosylated precursor of 2f was synthesized in two steps and radiolabeled with fluorine-18 to afford [18F]2f in 15 ± 5% radiochemical yield and a molar activity of 110 ± 30 GBq/μmol. Autoradiographies of rat spleen and biodistribution studies in healthy rats including pretreatments with either CB2R or CB1R-specific compounds suggested that [18F]2f is a specific tracer for the CB2R in vivo. We have therefore demonstrated here that [18F]2f is a promising novel tracer for imaging CB2R in vivo using PET. Further investigation in animal models of inflammation will follow.
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Affiliation(s)
- Fabien Caillé
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Fanny Cacheux
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Marie-Anne Peyronneau
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Benoît Jego
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Emilie Jaumain
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Géraldine Pottier
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Christoph Ullmer
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd. , 4070 Basel, Switzerland
| | - Uwe Grether
- Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd. , 4070 Basel, Switzerland
| | - Alexandra Winkeler
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Frédéric Dollé
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Annelaure Damont
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
| | - Bertrand Kuhnast
- UMR 1023 IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay , 91405 Orsay, France
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Tronel C, Largeau B, Santiago Ribeiro MJ, Guilloteau D, Dupont AC, Arlicot N. Molecular Targets for PET Imaging of Activated Microglia: The Current Situation and Future Expectations. Int J Mol Sci 2017; 18:ijms18040802. [PMID: 28398245 PMCID: PMC5412386 DOI: 10.3390/ijms18040802] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 03/15/2017] [Accepted: 03/28/2017] [Indexed: 12/13/2022] Open
Abstract
Microglia, as cellular mediators of neuroinflammation, are implicated in the pathogenesis of a wide range of neurodegenerative diseases. Positron emission tomography (PET) imaging of microglia has matured over the last 20 years, through the development of radiopharmaceuticals targeting several molecular biomarkers of microglial activation and, among these, mainly the translocator protein-18 kDa (TSPO). Nevertheless, current limitations of TSPO as a PET microglial biomarker exist, such as low brain density, even in a neurodegenerative setting, expression by other cells than the microglia (astrocytes, peripheral macrophages in the case of blood brain barrier breakdown), genetic polymorphism, inducing a variation for most of TSPO PET radiopharmaceuticals’ binding affinity, or similar expression in activated microglia regardless of its polarization (pro- or anti-inflammatory state), and these limitations narrow its potential interest. We overview alternative molecular targets, for which dedicated radiopharmaceuticals have been proposed, including receptors (purinergic receptors P2X7, cannabinoid receptors, α7 and α4β2 nicotinic acetylcholine receptors, adenosine 2A receptor, folate receptor β) and enzymes (cyclooxygenase, nitric oxide synthase, matrix metalloproteinase, β-glucuronidase, and enzymes of the kynurenine pathway), with a particular focus on their respective contribution for the understanding of microglial involvement in neurodegenerative diseases. We discuss opportunities for these potential molecular targets for PET imaging regarding their selectivity for microglia expression and polarization, in relation to the mechanisms by which microglia actively participate in both toxic and neuroprotective actions in brain diseases, and then take into account current clinicians’ expectations.
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Affiliation(s)
- Claire Tronel
- INSERM U930, Université François Rabelais de Tours, 10 boulevard Tonnelé, 37032 Tours, France.
| | | | - Maria Joao Santiago Ribeiro
- INSERM U930, Université François Rabelais de Tours, 10 boulevard Tonnelé, 37032 Tours, France.
- CHRU de Tours, 37044 Tours, France.
| | - Denis Guilloteau
- INSERM U930, Université François Rabelais de Tours, 10 boulevard Tonnelé, 37032 Tours, France.
- CHRU de Tours, 37044 Tours, France.
| | - Anne-Claire Dupont
- INSERM U930, Université François Rabelais de Tours, 10 boulevard Tonnelé, 37032 Tours, France.
- CHRU de Tours, 37044 Tours, France.
| | - Nicolas Arlicot
- INSERM U930, Université François Rabelais de Tours, 10 boulevard Tonnelé, 37032 Tours, France.
- CHRU de Tours, 37044 Tours, France.
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Hosoya T, Fukumoto D, Kakiuchi T, Nishiyama S, Yamamoto S, Ohba H, Tsukada H, Ueki T, Sato K, Ouchi Y. In vivo TSPO and cannabinoid receptor type 2 availability early in post-stroke neuroinflammation in rats: a positron emission tomography study. J Neuroinflammation 2017; 14:69. [PMID: 28356120 PMCID: PMC5372312 DOI: 10.1186/s12974-017-0851-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 03/23/2017] [Indexed: 01/08/2023] Open
Abstract
Background Upregulated levels of 18-kDa translocator proteins (TSPO) and type 2 endocannabinoid receptors (CB2) are considered to reflect different aspects of microglia-related neuroinflammatory responses in the brain. Relative to the increase in the TSPO expression that occurs slightly later during neuroinflammation in a proinflammatory fashion, CB2 activation is considered to relate to the neuroprotective responses that occurs predominantly at an early stage of brain disorders. These findings, however, were deduced from studies with different animal samples under different experimental settings. Here, we aimed to examined the differences in TSPO binding and CB2 availability at an early stage of stroke in the same animal using positron emission tomography (PET). Methods We used a total of eight Sprague-Dawley rats that underwent photothrombotic stroke surgery. The binding levels of a TSPO tracer [11C](R)PK11195 and a CB2 tracer [11C]NE40 were measured at 24 h after the surgery in the same animal using PET in combination with immunohistochemistry for CB2 and several other markers. A morphological inspection was also performed with X-ray computed tomography for small animals. Results The levels of [11C]NE40 binding potential (BPND) were significantly higher in the cerebral cortical region on the lesion side than those on the non-lesion side, whereas no difference was found in the levels of [11C](R)PK11195 BPND between hemispheres. The tracer influx index (R1) data were all reduced on the lesion side irrespective of tracers. This increase in [11C]NE40 BPND was concomitant with an elevation in CB2 expression mainly within the microglia in the peri-infarct area, as shown by immunohistochemical examinations with Iba-1, CD11b/c+, and NG2+ staining. Conclusions The present results provide in vivo evidence of different responses of microglia occurring in the acute state of stroke. The use of the CB2 tracer [11C]NE40 allows us to evaluate the roles played by the neuroprotective aspect of microglia in acute neuroinflammatory processes. Electronic supplementary material The online version of this article (doi:10.1186/s12974-017-0851-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Teruyo Hosoya
- Department of Neuroanatomy and Neuroscience, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Dai Fukumoto
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita-ku, Hamamatsu, 434-8601, Japan
| | - Takeharu Kakiuchi
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita-ku, Hamamatsu, 434-8601, Japan
| | - Shingo Nishiyama
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita-ku, Hamamatsu, 434-8601, Japan
| | - Shigeyuki Yamamoto
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita-ku, Hamamatsu, 434-8601, Japan
| | - Hiroyuki Ohba
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita-ku, Hamamatsu, 434-8601, Japan
| | - Hideo Tsukada
- Central Research Laboratory, Hamamatsu Photonics KK, 5000 Hirakuchi, Hamakita-ku, Hamamatsu, 434-8601, Japan
| | - Takatoshi Ueki
- Department of Neuroanatomy and Neuroscience, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Kohji Sato
- Department of Neuroanatomy and Neuroscience, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan
| | - Yasuomi Ouchi
- Department of Biofunctional Imaging, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi-ku, Hamamatsu, 431-3192, Japan.
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Positron emission tomography in amyotrophic lateral sclerosis: Towards targeting of molecular pathological hallmarks. Eur J Nucl Med Mol Imaging 2016; 44:533-547. [DOI: 10.1007/s00259-016-3587-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 11/23/2016] [Indexed: 12/18/2022]
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Ahamed M, van Veghel D, Ullmer C, Van Laere K, Verbruggen A, Bormans GM. Synthesis, Biodistribution and In vitro Evaluation of Brain Permeable High Affinity Type 2 Cannabinoid Receptor Agonists [ 11C]MA2 and [ 18F]MA3. Front Neurosci 2016; 10:431. [PMID: 27713686 PMCID: PMC5031696 DOI: 10.3389/fnins.2016.00431] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 09/06/2016] [Indexed: 12/22/2022] Open
Abstract
The type 2 cannabinoid receptor (CB2) is a member of the endocannabinoid system and is known for its important role in (neuro)inflammation. A PET-imaging agent that allows in vivo visualization of CB2 expression may thus allow quantification of neuroinflammation. In this paper, we report the synthesis, radiosynthesis, biodistribution and in vitro evaluation of a carbon-11 ([11C]MA2) and a fluorine-18 ([18F]MA3) labeled analog of a highly potent N-arylamide oxadiazole CB2 agonist (EC50 = 0.015 nM). MA2 and MA3 behaved as potent CB2 agonist (EC50: 3 nM and 0.1 nM, respectively) and their in vitro binding affinity for hCB2 was found to be 87 nM and 0.8 nM, respectively. Also MA3 (substituted with a fluoro ethyl group) was found to have higher binding affinity and EC50 values when compared to the originally reported trifluoromethyl analog 12. [11C]MA2 and [18F]MA3 were successfully synthesized with good radiochemical yield, high radiochemical purity and high specific activity. In mice, both tracers were efficiently cleared from blood and all major organs by the hepatobiliary pathway and importantly these compounds showed high brain uptake. In conclusion, [11C]MA2 and [18F]MA3 are shown to be high potent CB2 agonists with good brain uptake, these favorable characteristics makes them potential PET probes for in vivo imaging of brain CB2 receptors. However, in view of its higher affinity and selectivity, further detailed evaluation of MA3 as a PET tracer for CB2 is warranted.
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Affiliation(s)
- Muneer Ahamed
- Laboratory for Radiopharmacy, KU Leuven Leuven, Belgium
| | | | - Christoph Ullmer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd Basel, Switzerland
| | - Koen Van Laere
- Division of Nuclear Medicine, University Hospital and KU Leuven Leuven, Belgium
| | | | - Guy M Bormans
- Laboratory for Radiopharmacy, KU Leuven Leuven, Belgium
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Poutiainen P, Jaronen M, Quintana FJ, Brownell AL. Precision Medicine in Multiple Sclerosis: Future of PET Imaging of Inflammation and Reactive Astrocytes. Front Mol Neurosci 2016; 9:85. [PMID: 27695400 PMCID: PMC5023680 DOI: 10.3389/fnmol.2016.00085] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Accepted: 08/30/2016] [Indexed: 12/29/2022] Open
Abstract
Non-invasive molecular imaging techniques can enhance diagnosis to achieve successful treatment, as well as reveal underlying pathogenic mechanisms in disorders such as multiple sclerosis (MS). The cooperation of advanced multimodal imaging techniques and increased knowledge of the MS disease mechanism allows both monitoring of neuronal network and therapeutic outcome as well as the tools to discover novel therapeutic targets. Diverse imaging modalities provide reliable diagnostic and prognostic platforms to better achieve precision medicine. Traditionally, magnetic resonance imaging (MRI) has been considered the golden standard in MS research and diagnosis. However, positron emission tomography (PET) imaging can provide functional information of molecular biology in detail even prior to anatomic changes, allowing close follow up of disease progression and treatment response. The recent findings support three major neuroinflammation components in MS: astrogliosis, cytokine elevation, and significant changes in specific proteins, which offer a great variety of specific targets for imaging purposes. Regardless of the fact that imaging of astrocyte function is still a young field and in need for development of suitable imaging ligands, recent studies have shown that inflammation and astrocyte activation are related to progression of MS. MS is a complex disease, which requires understanding of disease mechanisms for successful treatment. PET is a precise non-invasive imaging method for biochemical functions and has potential to enhance early and accurate diagnosis for precision therapy of MS. In this review we focus on modulation of different receptor systems and inflammatory aspect of MS, especially on activation of glial cells, and summarize the recent findings of PET imaging in MS and present the most potent targets for new biomarkers with the main focus on experimental MS research.
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Affiliation(s)
- Pekka Poutiainen
- Athinoula A Martinos Biomedical Imaging Center, Department of Radiology, Massachusetts General Hospital, Harvard Medical SchoolCharlestown, MA, USA
| | - Merja Jaronen
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical SchoolBoston, MA, USA
| | - Francisco J. Quintana
- Ann Romney Center for Neurologic Diseases, Brigham and Women's Hospital, Harvard Medical SchoolBoston, MA, USA
| | - Anna-Liisa Brownell
- Athinoula A Martinos Biomedical Imaging Center, Department of Radiology, Massachusetts General Hospital, Harvard Medical SchoolCharlestown, MA, USA
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Moldovan RP, Teodoro R, Gao Y, Deuther-Conrad W, Kranz M, Wang Y, Kuwabara H, Nakano M, Valentine H, Fischer S, Pomper MG, Wong DF, Dannals RF, Brust P, Horti AG. Development of a High-Affinity PET Radioligand for Imaging Cannabinoid Subtype 2 Receptor. J Med Chem 2016; 59:7840-55. [PMID: 27500461 DOI: 10.1021/acs.jmedchem.6b00554] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Cannabinoid receptors type 2 (CB2) represent a target with increasing importance for neuroimaging due to its upregulation under various pathological conditions. Encouraged by preliminary results obtained with [(11)C](Z)-N-(3-(2-methoxyethyl)-4,5-dimethylthiazol-2(3H)-ylidene)-2,2,3,3-tetramethyl-cyclopropanecarboxamide ([(11)C]A-836339, [(11)C]1) in a mouse model of acute neuroinflammation (induced by lipopolysaccharide, LPS), we designed a library of fluorinated analogues aiming for an [(18)F]-labeled radiotracer with improved CB2 binding affinity and selectivity. Compound (Z)-N-(3-(4-fluorobutyl)-4,5-dimethylthiazol-2(3H)-ylidene)-2,2,3,3-tetramethyl-cyclopropanecarboxamide (29) was selected as the ligand with the highest CB2 affinity (Ki = 0.39 nM) and selectivity over those of CB1 (factor of 1000). [(18)F]29 was prepared starting from the bromo precursor (53). Specific binding was shown in vitro, whereas fast metabolism was observed in vivo in CD-1 mice. Animal PET revealed a brain uptake comparable to that of [(11)C]1. In the LPS-treated mice, a 20-30% higher uptake in brain was found in comparison to that in nontreated mice (n = 3, P < 0.05).
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Affiliation(s)
- Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research , Leipzig, Germany
| | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research , Leipzig, Germany
| | - Yongjun Gao
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research , Leipzig, Germany
| | - Mathias Kranz
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research , Leipzig, Germany
| | - Yuchuan Wang
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Hiroto Kuwabara
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Masayoshi Nakano
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Heather Valentine
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Steffen Fischer
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research , Leipzig, Germany
| | - Martin G Pomper
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Dean F Wong
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Robert F Dannals
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Radiopharmaceutical Cancer Research , Leipzig, Germany
| | - Andrew G Horti
- Johns Hopkins School of Medicine , Department of Radiology, Baltimore, 21287 United States
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Ahmad R, Postnov A, Bormans G, Versijpt J, Vandenbulcke M, Van Laere K. Decreased in vivo availability of the cannabinoid type 2 receptor in Alzheimer’s disease. Eur J Nucl Med Mol Imaging 2016; 43:2219-2227. [DOI: 10.1007/s00259-016-3457-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 07/01/2016] [Indexed: 10/21/2022]
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Slavik R, Müller Herde A, Haider A, Krämer SD, Weber M, Schibli R, Ametamey SM, Mu L. Discovery of a fluorinated 4-oxo-quinoline derivative as a potential positron emission tomography radiotracer for imaging cannabinoid receptor type 2. J Neurochem 2016; 138:874-86. [PMID: 27385045 DOI: 10.1111/jnc.13716] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 06/08/2016] [Accepted: 06/09/2016] [Indexed: 11/28/2022]
Abstract
The cannabinoid receptor type 2 (CB2) is part of the endocannabinoid system and has gained growing attention in recent years because of its important role in neuroinflammatory/neurodegenerative diseases. Recently, we reported on a carbon-11 labeled 4-oxo-quinoline derivative, designated RS-016, as a promising radiotracer for imaging CB2 using PET. In this study, three novel fluorinated analogs of RS-016 were designed, synthesized, and pharmacologically evaluated. The results of our efforts led to the identification of N-(1-adamantyl)-1-(2-(2-fluoroethoxy)ethyl)-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxamide (RS-126) as the most potent candidate for evaluation as a CB2 PET ligand. [(18) F]RS-126 was obtained in ≥ 99% radiochemical purity with an average specific radioactivity of 98 GBq/μmol at the end of the radiosynthesis. [(18) F]RS-126 showed a logD7.4 value of 1.99 and is stable in vitro in rat and human plasma over 120 min, whereas 55% intact parent compound was found in vivo in rat blood plasma at 10 min post injection. In vitro autoradiographic studies with CB2-positive rat spleen tissue revealed high and blockable binding which was confirmed in in vivo displacement experiments with rats by dynamic PET imaging. Ex vivo biodistribution studies confirmed accumulation of [(18) F]RS-126 in rat spleen with a specificity of 79% under blocking conditions. The moderate elevated CB2 levels in LPS-treated mice brain did not permit the detection of CB2 by [(18) F]RS-126 using PET imaging. In summary, [(18) F]RS-126 demonstrated high specificity toward CB2 receptor in vitro and in vivo and is a promising radioligand for imaging CB2 receptor expression. Cannabinoid receptor type 2 (CB2) is an interesting target for PET imaging. Specific binding of [(18) F]RS-126 in CB2-positive spleen tissue (white arrow head) was confirmed in in vivo displacement experiments with rats. Time activity curve of [(18) F]RS-126 in the spleen after the addition of GW405833 (CB2 specific ligand, green) demonstrates faster radiotracer elimination (blue) compared to the tracer only (red).
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Affiliation(s)
- Roger Slavik
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | | | - Ahmed Haider
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Stefanie D Krämer
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland
| | - Markus Weber
- Neuromuscular Diseases Unit/ALS Clinic, Kantonsspital St. Gallen, St. Gallen, Switzerland
| | - Roger Schibli
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland.,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland
| | - Simon M Ametamey
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland.
| | - Linjing Mu
- Institute of Pharmaceutical Sciences, ETH Zurich, Zurich, Switzerland. .,Department of Nuclear Medicine, University Hospital Zurich, Zurich, Switzerland.
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Abstract
Microglial activation is a key aspect of the neuroinflammatory process in neurodegenerative disorders including idiopathic and atypical parkinsonian disorders. With positron emission tomography (PET) it has become possible to image this phenomenon in vivo and over the last years patterns of microglia activation corresponding with the known distribution of neuropathological changes in these disorders have been demonstrated using this technique. In addition the effects of interventions aimed at suppressing microglia activation as part of interventional trials have successfully been demonstrated. Current research aims at evaluating PET tracers for microglial activation with more favorable properties than the prototypical [11C]-(R)-PK11195, as well as developing tracers targeting additional parameters of the neuroinflammatory process like astroglial function.
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Affiliation(s)
- Alexander Gerhard
- Wolfson Molecular Imaging Centre, Institute of Brain, Behaviour and Mental Health, The University of Manchester, 27 Palatine Road, Withington, Manchester, M20 3LJ UK
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Savonenko AV, Melnikova T, Wang Y, Ravert H, Gao Y, Koppel J, Lee D, Pletnikova O, Cho E, Sayyida N, Hiatt A, Troncoso J, Davies P, Dannals RF, Pomper MG, Horti AG. Cannabinoid CB2 Receptors in a Mouse Model of Aβ Amyloidosis: Immunohistochemical Analysis and Suitability as a PET Biomarker of Neuroinflammation. PLoS One 2015; 10:e0129618. [PMID: 26086915 PMCID: PMC4472959 DOI: 10.1371/journal.pone.0129618] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 05/11/2015] [Indexed: 11/18/2022] Open
Abstract
In Alzheimer's disease (AD), one of the early responses to Aβ amyloidosis is recruitment of microglia to areas of new plaque. Microglial receptors such as cannabinoid receptor 2 (CB2) might be a suitable target for development of PET radiotracers that could serve as imaging biomarkers of Aβ-induced neuroinflammation. Mouse models of amyloidosis (J20APPswe/ind and APPswe/PS1ΔE9) were used to investigate the cellular distribution of CB2 receptors. Specificity of CB2 antibody (H60) was confirmed using J20APPswe/ind mice lacking CB2 receptors. APPswe/PS1ΔE9 mice were used in small animal PET with a CB2-targeting radiotracer, [11C]A836339. These studies revealed increased binding of [11C]A836339 in amyloid-bearing mice. Specificity of the PET signal was confirmed in a blockade study with a specific CB2 antagonist, AM630. Confocal microscopy revealed that CB2-receptor immunoreactivity was associated with astroglial (GFAP) and, predominantly, microglial (CD68) markers. CB2 receptors were observed, in particular, in microglial processes forming engulfment synapses with Aβ plaques. In contrast to glial cells, neuron (NeuN)-derived CB2 signal was equal between amyloid-bearing and control mice. The pattern of neuronal CB2 staining in amyloid-bearing mice was similar to that in human cases of AD. The data collected in this study indicate that Aβ amyloidosis without concomitant tau pathology is sufficient to activate CB2 receptors that are suitable as an imaging biomarker of neuroinflammation. The main source of enhanced CB2 PET binding in amyloid-bearing mice is increased CB2 immunoreactivity in activated microglia. The presence of CB2 immunoreactivity in neurons does not likely contribute to the enhanced CB2 PET signal in amyloid-bearing mice due to a lack of significant neuronal loss in this model. However, significant loss of neurons as seen at late stages of AD might decrease the CB2 PET signal due to loss of neuronally-derived CB2. Thus this study in mouse models of AD indicates that a CB2-specific radiotracer can be used as a biomarker of neuroinflammation in the early preclinical stages of AD, when no significant neuronal loss has yet developed.
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Affiliation(s)
- Alena V. Savonenko
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- Departments of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- * E-mail: (AGH); (AS)
| | - Tatiana Melnikova
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Yuchuan Wang
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Hayden Ravert
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Yongjun Gao
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Jeremy Koppel
- Litwin-Zucker Research Center, Feinstein Institute for Medical Research, North-Shore Long Island Jewish Health System, Manhasset, NY, United States of America
| | - Deidre Lee
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Olga Pletnikova
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Eugenia Cho
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Nuzhat Sayyida
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Andrew Hiatt
- MAPP Biopharmaceutical Inc, San-Diego, CA, United States of America
| | - Juan Troncoso
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- Departments of Neurology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Peter Davies
- Litwin-Zucker Research Center, Feinstein Institute for Medical Research, North-Shore Long Island Jewish Health System, Manhasset, NY, United States of America
| | - Robert F. Dannals
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Andrew G. Horti
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- * E-mail: (AGH); (AS)
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Imaging neuroinflammation in Alzheimer's disease and other dementias: Recent advances and future directions. Alzheimers Dement 2014; 11:1110-20. [DOI: 10.1016/j.jalz.2014.08.105] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 04/21/2014] [Accepted: 08/12/2014] [Indexed: 12/13/2022]
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Yrjölä S, Sarparanta M, Airaksinen AJ, Hytti M, Kauppinen A, Pasonen-Seppänen S, Adinolfi B, Nieri P, Manera C, Keinänen O, Poso A, Nevalainen TJ, Parkkari T. Synthesis, in vitro and in vivo evaluation of 1,3,5-triazines as cannabinoid CB2 receptor agonists. Eur J Pharm Sci 2014; 67:85-96. [PMID: 25447744 DOI: 10.1016/j.ejps.2014.11.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/01/2014] [Accepted: 11/06/2014] [Indexed: 11/28/2022]
Abstract
The cannabinoid receptors type 2 (CBR2) are attractive therapeutic targets of the endocannabinoid signaling system (ECS) as they are not displaying the undesired psychotropic and cardiovascular side-effects seen with cannabinoid receptor type 1 (CB1R) agonists. In continuation of our previous work on 2,4,6-trisubstituted 1,3,5-triazines as potent CB2 agonists, we synthesized an additional series of more polar analogues (1-10), which were found to possess high CB2R agonist activity with enhanced water solubility. The most potent compound in the series was N-(adamantan-1-yl)-4-ethoxy-6-(4-(2-fluoroethyl)piperazin-1-yl)-1,3,5-triazin-2-amine (9) with EC50 value of 0.60nM. To further evaluate the biological effects of the compounds, the selected compounds were tested in vitro against four different cell lines. A human retinal pigment epithelial cell line (ARPE-19) was used to evaluate the cytotoxicity of the compounds whereas an androgen-sensitive human prostate adenocarcinoma cell line (LNCaP), a Jurkat leukemia cell line and a C8161 melanoma cell line were used to assess the antiproliferative activity of the compounds. The most interesting results were obtained for N-(adamantan-1-yl)-4-ethoxy-6-(4-methylpiperazin-1-yl)-1,3,5-triazin-2-amine (6), which induced cell viability decrease in prostate and leukemia cell lines, and diminished proliferation of C8161 melanoma cells. The results could be reversed in leukemia cells with the selective CB2R antagonist AM630, whereas in prostate cells the AM630 induced a significant cell viability decrease with a mechanism probably unlinked to CB2 cannabinoid receptor. The antiproliferative effect of 6 on the melanoma cells seemed not to be mediated via the CB1R or CB2R. No cytotoxicity was detected against ARPE-19 cell line at concentrations of 1 and 10μM for compound 6. However, at 30μM concentration the compound 6 decreased the cell viability. Finally, in order to estimate in vivo behavior of these compounds, (18)F labeled PET ligand, N-cyclopentyl-4-ethoxy-6-(4-(2-fluoro-18-ethyl)piperazin-1-yl)-1,3,5-triazin-2-amine ([(18)F]5), was synthesized and its biodistribution was determined in healthy male Sprague-Dawley rats. As a result, the tracer showed a rapid (<15min) elimination in urine accompanied by a slower excretion via the hepatobiliary route. In conclusion, we further demonstrated that 1,3,5-triazine scaffold serves as a suitable template for the design of highly potent CB2R agonists with reasonable water solubility properties. The compounds may be useful when studying the role of the endocannabinoid system in different diseases. The triazine scaffold is also a promising candidate for the development of new CB2R PET ligands.
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Affiliation(s)
- Sari Yrjölä
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland.
| | - Mirkka Sarparanta
- Laboratory of Radiochemistry, Department of Chemistry, PO Box 55, FI-00014 University of Helsinki, Finland
| | - Anu J Airaksinen
- Laboratory of Radiochemistry, Department of Chemistry, PO Box 55, FI-00014 University of Helsinki, Finland
| | - Maria Hytti
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O.B. 1627, FI-70211 Kuopio, Finland
| | - Anu Kauppinen
- Department of Ophthalmology, Institute of Clinical Medicine, University of Eastern Finland, P.O.B. 1627, FI-70211 Kuopio, Finland; Department of Ophthalmology, Kuopio University Hospital, P.O.B 100, FI-70029 KYS, Finland
| | - Sanna Pasonen-Seppänen
- School of Medicine, Institute of Biomedicine, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
| | - Barbara Adinolfi
- Institute of Applied Physics "Nello Carrara", National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino, FI, Italy; Department of Pharmacy, University of Pisa, Via Bonanno 6, 56100 Pisa, PI, Italy
| | - Paola Nieri
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56100 Pisa, PI, Italy
| | - Clementina Manera
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56100 Pisa, PI, Italy
| | - Outi Keinänen
- Laboratory of Radiochemistry, Department of Chemistry, PO Box 55, FI-00014 University of Helsinki, Finland
| | - Antti Poso
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland; Division of Translational Gastrointestinal Oncology, Dept. of Internal Medicine I, University Hospital Tuebingen, Otfried-Mueller-Strasse 10, 72076 Tuebingen, Germany
| | - Tapio J Nevalainen
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
| | - Teija Parkkari
- School of Pharmacy, Faculty of Health Sciences, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
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Amhaoul H, Staelens S, Dedeurwaerdere S. Imaging brain inflammation in epilepsy. Neuroscience 2014; 279:238-52. [DOI: 10.1016/j.neuroscience.2014.08.044] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 08/27/2014] [Accepted: 08/27/2014] [Indexed: 01/15/2023]
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Mu L, Slavik R, Müller A, Popaj K, Cermak S, Weber M, Schibli R, Krämer SD, Ametamey SM. Synthesis and Preliminary Evaluation of a 2-Oxoquinoline Carboxylic Acid Derivative for PET Imaging the Cannabinoid Type 2 Receptor. Pharmaceuticals (Basel) 2014; 7:339-52. [PMID: 24662272 PMCID: PMC3978495 DOI: 10.3390/ph7030339] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 02/21/2014] [Accepted: 02/27/2014] [Indexed: 11/27/2022] Open
Abstract
Cannabinoid receptor subtype 2 (CB2) has been shown to be up-regulated in activated microglia and therefore plays an important role in neuroinflammatory and neurodegenerative diseases such as multiple sclerosis, amyotrophic lateral sclerosis and Alzheimer’s disease. The CB2 receptor is therefore considered as a very promising target for therapeutic approaches as well as for imaging. A promising 2-oxoquinoline derivative designated KP23 was synthesized and radiolabeled and its potential as a ligand for PET imaging the CB2 receptor was evaluated. [11C]KP23 was obtained in 10%–25% radiochemical yield (decay corrected) and 99% radiochemical purity. It showed high stability in phosphate buffer, rat and mouse plasma. In vitro autoradiography of rat and mouse spleen slices, as spleen expresses a high physiological expression of CB2 receptors, demonstrated that [11C]KP23 exhibits specific binding towards CB2. High spleen uptake of [11C]KP23 was observed in dynamic in vivo PET studies with Wistar rats. In conclusion, [11C]KP23 showed promising in vitro and in vivo characteristics. Further evaluation with diseased animal model which has higher CB2 expression levels in the brain is warranted.
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Affiliation(s)
- Linjing Mu
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Department of Nuclear Medicine, University Hospital Zürich, CH-8091 Zürich, Switzerland.
| | - Roger Slavik
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Adrienne Müller
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Kasim Popaj
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Department of Nuclear Medicine, University Hospital Zürich, CH-8091 Zürich, Switzerland
| | - Stjepko Cermak
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Markus Weber
- Neuromuscular Diseases Unit/ALS Clinic, Kantonsspital St. Gallen, CH-9007 St. Gallen, Switzerland
| | - Roger Schibli
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Department of Nuclear Medicine, University Hospital Zürich, CH-8091 Zürich, Switzerland
| | - Stefanie D Krämer
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
| | - Simon M Ametamey
- Center for Radiopharmaceutical Sciences of ETH-PSI-USZ, Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, CH-8093 Zürich, Switzerland
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Ahmad R, Koole M, Evens N, Serdons K, Verbruggen A, Bormans G, Van Laere K. Whole-body biodistribution and radiation dosimetry of the cannabinoid type 2 receptor ligand [11C]-NE40 in healthy subjects. Mol Imaging Biol 2014; 15:384-90. [PMID: 23508466 DOI: 10.1007/s11307-013-0626-y] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE The type 2 cannabinoid receptor (CB2R) is part of the human endocannabinoid system and is involved in central and peripheral inflammatory processes. In vivo imaging of the CB2R would allow study of several (neuro)inflammatory disorders. In this study we have investigated the safety and tolerability of [11C]-NE40, a CB2R positron emission tomography (PET) ligand, in healthy human male subjects and determined its biodistribution and radiation dosimetry. PROCEDURE Six healthy male subjects (age 20-65 years) underwent a dynamic series of nine whole-body PET/CT scans for up to 140 min, after injection of an average bolus of 286 MBq of [11C]-NE40. Organ absorbed and total effective doses were calculated through OLINDA. RESULTS [11C]-NE40 showed high initial uptake in the spleen and a predominant hepatobiliary excretion. In the brain, rapid uptake and swift washout were seen. Organ absorbed doses were largest for the small intestine and liver, with 15.6 and 11.5 μGy/MBq, respectively. The mean effective dose was 3.64±0.81 μSv/MBq. There were no changes with aging observed. No adverse events were encountered. CONCLUSIONS This first-in-man study of [11C]-NE40 showed an expected biodistribution compatible with lymphoid tissue uptake and appropriate fast brain kinetics in the healthy human brain, underscoring the potential of this tracer for further application in central and peripheral inflammation imaging. The effective dose is within the typical expected range for 11C ligands.
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Affiliation(s)
- Rawaha Ahmad
- Division of Nuclear Medicine, University Hospital Leuven, Herestraat 49, 3000, Leuven, Belgium.
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Hortala L, Arnaud J, Roux P, Oustric D, Boulu L, Oury-Donat F, Avenet P, Rooney T, Alagille D, Barret O, Tamagnan G, Barth F. Synthesis and preliminary evaluation of a new fluorine-18 labelled triazine derivative for PET imaging of cannabinoid CB2 receptor. Bioorg Med Chem Lett 2014; 24:283-7. [DOI: 10.1016/j.bmcl.2013.11.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 11/08/2013] [Accepted: 11/10/2013] [Indexed: 01/26/2023]
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Gerhard A. Imaging of Neuroinflammation in Parkinsonian Syndromes with Positron Emission Tomography. Curr Neurol Neurosci Rep 2013; 13:405. [DOI: 10.1007/s11910-013-0405-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Wu C, Li F, Niu G, Chen X. PET imaging of inflammation biomarkers. Theranostics 2013; 3:448-66. [PMID: 23843893 PMCID: PMC3706689 DOI: 10.7150/thno.6592] [Citation(s) in RCA: 131] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Accepted: 05/24/2013] [Indexed: 01/04/2023] Open
Abstract
Inflammation plays a significant role in many disease processes. Development in molecular imaging in recent years provides new insight into the diagnosis and treatment evaluation of various inflammatory diseases and diseases involving inflammatory process. Positron emission tomography using (18)F-FDG has been successfully applied in clinical oncology and neurology and in the inflammation realm. In addition to glucose metabolism, a variety of targets for inflammation imaging are being discovered and utilized, some of which are considered superior to FDG for imaging inflammation. This review summarizes the potential inflammation imaging targets and corresponding PET tracers, and the applications of PET in major inflammatory diseases and tumor associated inflammation. Also, the current attempt in differentiating inflammation from tumor using PET is also discussed.
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