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Gündel D, Toussaint M, Lai TH, Deuther-Conrad W, Cumming P, Schröder S, Teodoro R, Moldovan RP, Pan-Montojo F, Sattler B, Kopka K, Sabri O, Brust P. Quantitation of the A2A Adenosine Receptor Density in the Striatum of Mice and Pigs with [18F]FLUDA by Positron Emission Tomography. Pharmaceuticals (Basel) 2022; 15:ph15050516. [PMID: 35631343 PMCID: PMC9146919 DOI: 10.3390/ph15050516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 12/10/2022] Open
Abstract
The cerebral expression of the A2A adenosine receptor (A2AAR) is altered in neurodegenerative diseases such as Parkinson’s (PD) and Huntington’s (HD) diseases, making these receptors an attractive diagnostic and therapeutic target. We aimed to further investigate the pharmacokinetic properties in the brain of our recently developed A2AAR–specific antagonist radiotracer [18F]FLUDA. For this purpose, we retrospectively analysed dynamic PET studies of healthy mice and rotenone–treated mice, and conducted dynamic PET studies with healthy pigs. We performed analysis of mouse brain time–activity curves to calculate the mean residence time (MRT) by non–compartmental analysis, and the binding potential (BPND) of [18F]FLUDA using the simplified reference tissue model (SRTM). For the pig studies, we performed a Logan graphical analysis to calculate the radiotracer distribution volume (VT) at baseline and under blocking conditions with tozadenant. The MRT of [18F]FLUDA in the striatum of mice was decreased by 30% after treatment with the A2AAR antagonist istradefylline. Mouse results showed the highest BPND (3.9 to 5.9) in the striatum. SRTM analysis showed a 20% lower A2AAR availability in the rotenone–treated mice compared to the control–aged group. Tozadenant treatment significantly decreased the VT (14.6 vs. 8.5 mL · g−1) and BPND values (1.3 vs. 0.3) in pig striatum. This study confirms the target specificity and a high BPND of [18F]FLUDA in the striatum. We conclude that [18F]FLUDA is a suitable tool for the non–invasive quantitation of altered A2AAR expression in neurodegenerative diseases such as PD and HD, by PET.
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Affiliation(s)
- Daniel Gündel
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Correspondence: ; Tel.: +49-341-234179-4615
| | - Magali Toussaint
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
| | - Thu Hang Lai
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Department of Research and Development, ROTOP Pharmaka Ltd., 01328 Dresden, Germany;
| | - Winnie Deuther-Conrad
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
| | - Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, 3010 Bern, Switzerland;
- School of Psychology and Counselling, Queensland University of Technology, Brisbane 4000, Australia
| | - Susann Schröder
- Department of Research and Development, ROTOP Pharmaka Ltd., 01328 Dresden, Germany;
| | - Rodrigo Teodoro
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Department of Research and Development, Life Molecular Imaging GmbH, 13353 Berlin, Germany
| | - Rareş-Petru Moldovan
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
| | - Francisco Pan-Montojo
- Department of Psychiatry, University Hospital Munich, Ludwig–Maximilians–Universität (LMU) Munich, 80336 Munich, Germany;
- Department of Neurology, University Hospital Munich, Ludwig–Maximilians–Universität (LMU) Munich, 81377 Munich, Germany
| | - Bernhard Sattler
- Department for Nuclear Medicine, University Hospital Leipzig, 04103 Leipzig, Germany; (B.S.); (O.S.)
| | - Klaus Kopka
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Faculty of Chemistry and Food Chemistry, School of Science, TU Dresden, 01069 Dresden, Germany
| | - Osama Sabri
- Department for Nuclear Medicine, University Hospital Leipzig, 04103 Leipzig, Germany; (B.S.); (O.S.)
| | - Peter Brust
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- The Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig–Holstein, 23562 Lübeck, Germany
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Toyohara J, Sakata M, Wagatsuma K, Tago T, Ishibashi K, Ishii K, Elsinga P, Ishiwata K. Test-retest reproducibility of cerebral adenosine A 2A receptor quantification using [ 11C]preladenant. Ann Nucl Med 2022; 36:15-23. [PMID: 34564828 DOI: 10.1007/s12149-021-01678-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 09/13/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVE To evaluate the reproducibility of cerebral adenosine A2A receptor (A2AR) quantification using [11C]preladenant ([11C]PLN) and PET in a test-retest study. METHODS Eight healthy male volunteers were enrolled. Dynamic 90 min PET scans were performed twice at the same time of the day to avoid the effect of diurnal variation. Subjects refrained from caffeine from 12 h prior to scanning, and serum caffeine was measured before radioligand injection. Arterial blood was sampled repeatedly during scanning and the fraction of the parent compound in plasma was determined. Total distribution volume (VT) was estimated using 1- and 2-tissue compartment models (1-TCM and 2-TCM, respectively) and Logan graphical analysis (Logan plot) (t* = 30 min). Plasma-free fraction (fP) of [11C]PLN was measured and used for correction of VT values. Distribution volume ratio (DVR) was calculated from VT of target and reference regions and obtained by noninvasive Logan graphical reference tissue model (LGAR) (t* = 30 min). Absolute test-retest variability (aTRV), and intra-class correlation coefficient (ICC) of VT and DVR were calculated as indexes of repeatability. Correlation between DVR and serum concentration of caffeine (a nonselective A2AR blocker) was analyzed by Pearson's correlation analysis. RESULTS Regional time-activity curves were well described by 2-TCM models. Estimation of VT by 2-TCM produced some erroneous values; therefore, the more robust Logan plot was selected as the appropriate model. Global mean aTRV was 20% for VT and 14% for VT/fP (ICC, 0.72 for VT and 0.87 for VT/fP). Global mean aTRV of DVR was 13% for Logan plot and 10% for LGAR (ICC, 0.70 for Logan plot and 0.81 for LGAR). DVR estimates using LGAR and Logan plot were in good agreement (r2 = 0.96). Coefficients of variation for VT, VT/fP, DVR (Logan plot), and DVR (LGAR) were 47%, 47%, 27%, and 18%, respectively. Despite low serum caffeine levels, significant concentration-dependent effects on [11C]PLN binding to target regions were observed (p < 0.01). CONCLUSIONS In this study, moderate test-retest reproducibility and large inter-subject differences were observed with [11C]PLN PET, possibly attributable to competition by baseline amount of caffeine. Analysis of plasma caffeine concentration is recommended during [11C]PLN PET studies. TRIAL REGISTRATION UMIN000030040.
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Affiliation(s)
- Jun Toyohara
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan.
| | - Muneyuki Sakata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Kei Wagatsuma
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
- School of Allied Health Science, Kitasato University, 1-15-1 Kitasato, Sagamihara, Kanagawa, 252-0373, Japan
| | - Tetsuro Tago
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Kenji Ishibashi
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Kenji Ishii
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
| | - Philip Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Kiichi Ishiwata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi-ku, Tokyo, 173-0015, Japan
- Institute of Cyclotron and Drug Discovery Research, Southern Tohoku Research Institute for Neuroscience, 7-115 Yatsuyamada, Koriyama, Fukushima, 963-8563, Japan
- Department of Biofunctional Imaging, Fukushima Medical University, 1 Hikariga-oka, Fukushima, 960-1295, Japan
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Takamura Y, Kakuta H. In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography. J Med Chem 2021; 64:5226-5251. [PMID: 33905258 DOI: 10.1021/acs.jmedchem.0c01714] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Positron emission tomography (PET) is useful for noninvasive in vivo visualization of disease-related receptors, for evaluation of receptor occupancy to determine an appropriate drug dosage, and for proof-of-concept of drug candidates in translational research. For these purposes, the specificity of the PET tracer for the target receptor is critical. Here, we review work in this area, focusing on the chemical structures of reported PET tracers, their Ki/Kd values, and the physical properties relevant to target receptor selectivity. Among these physical properties, such as cLogP, cLogD, molecular weight, topological polar surface area, number of hydrogen bond donors, and pKa, we focus especially on LogD and LogP as important physical properties that can be easily compared across a range of studies. We discuss the success of PET tracers in evaluating receptor occupancy and consider likely future developments in the field.
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Affiliation(s)
- Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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Abstract
Positron emission tomography (PET) is a non-invasive imaging technology employed to describe metabolic, physiological, and biochemical processes in vivo. These include receptor availability, metabolic changes, neurotransmitter release, and alterations of gene expression in the brain. Since the introduction of dedicated small-animal PET systems along with the development of many novel PET imaging probes, the number of PET studies using rats and mice in basic biomedical research tremendously increased over the last decade. This article reviews challenges and advances of quantitative rodent brain imaging to make the readers aware of its physical limitations, as well as to inspire them for its potential applications in preclinical research. In the first section, we briefly discuss the limitations of small-animal PET systems in terms of spatial resolution and sensitivity and point to possible improvements in detector development. In addition, different acquisition and post-processing methods used in rodent PET studies are summarized. We further discuss factors influencing the test-retest variability in small-animal PET studies, e.g., different receptor quantification methodologies which have been mainly translated from human to rodent receptor studies to determine the binding potential and changes of receptor availability and radioligand affinity. We further review different kinetic modeling approaches to obtain quantitative binding data in rodents and PET studies focusing on the quantification of endogenous neurotransmitter release using pharmacological interventions. While several studies have focused on the dopamine system due to the availability of several PET tracers which are sensitive to dopamine release, other neurotransmitter systems have become more and more into focus and are described in this review, as well. We further provide an overview of latest genome engineering technologies, including the CRISPR/Cas9 and DREADD systems that may advance our understanding of brain disorders and function and how imaging has been successfully applied to animal models of human brain disorders. Finally, we review the strengths and opportunities of simultaneous PET/magnetic resonance imaging systems to study drug-receptor interactions and challenges for the translation of PET results from bench to bedside.
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Prasad K, de Vries EFJ, Elsinga PH, Dierckx RAJO, van Waarde A. Allosteric Interactions between Adenosine A 2A and Dopamine D 2 Receptors in Heteromeric Complexes: Biochemical and Pharmacological Characteristics, and Opportunities for PET Imaging. Int J Mol Sci 2021; 22:ijms22041719. [PMID: 33572077 PMCID: PMC7915359 DOI: 10.3390/ijms22041719] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Adenosine and dopamine interact antagonistically in living mammals. These interactions are mediated via adenosine A2A and dopamine D2 receptors (R). Stimulation of A2AR inhibits and blockade of A2AR enhances D2R-mediated locomotor activation and goal-directed behavior in rodents. In striatal membrane preparations, adenosine decreases both the affinity and the signal transduction of D2R via its interaction with A2AR. Reciprocal A2AR/D2R interactions occur mainly in striatopallidal GABAergic medium spiny neurons (MSNs) of the indirect pathway that are involved in motor control, and in striatal astrocytes. In the nucleus accumbens, they also take place in MSNs involved in reward-related behavior. A2AR and D2R co-aggregate, co-internalize, and co-desensitize. They are at very close distance in biomembranes and form heteromers. Antagonistic interactions between adenosine and dopamine are (at least partially) caused by allosteric receptor–receptor interactions within A2AR/D2R heteromeric complexes. Such interactions may be exploited in novel strategies for the treatment of Parkinson’s disease, schizophrenia, substance abuse, and perhaps also attention deficit-hyperactivity disorder. Little is known about shifting A2AR/D2R heteromer/homodimer equilibria in the brain. Positron emission tomography with suitable ligands may provide in vivo information about receptor crosstalk in the living organism. Some experimental approaches, and strategies for the design of novel imaging agents (e.g., heterobivalent ligands) are proposed in this review.
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Affiliation(s)
- Kavya Prasad
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Correspondence: (K.P.); (A.v.W.); Tel.: +31-50-3613215
| | - Erik F. J. de Vries
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
| | - Philip H. Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
| | - Rudi A. J. O. Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Department of Diagnostic Sciences, Ghent University Faculty of Medicine and Health Sciences, C.Heymanslaan 10, 9000 Gent, Belgium
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands; (E.F.J.d.V.); (P.H.E.); (R.A.J.O.D.)
- Correspondence: (K.P.); (A.v.W.); Tel.: +31-50-3613215
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Hámor PU, Gobin CM, Schwendt M. The role of glutamate mGlu5 and adenosine A2a receptor interactions in regulating working memory performance and persistent cocaine seeking in rats. Prog Neuropsychopharmacol Biol Psychiatry 2020; 103:109979. [PMID: 32470496 DOI: 10.1016/j.pnpbp.2020.109979] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 01/17/2023]
Abstract
Cocaine use disorder (CUD) is associated with neurobehavioral deficits that are resistant to current treatments. While craving and high rates of relapse are prominent features of CUD, persistent cognitive impairments are common and linked to poorer treatment outcomes. Here we sought to develop an animal model to study post-cocaine changes in drug seeking and working memory, and to evaluate 'therapeutic' effects of combined glutamate mGlu5 and adenosine A2a receptor blockade. As mGlu5 antagonists reduce drug seeking, and A2a blockade ameliorates working memory impairment, we hypothesized that mGlu5 + A2a antagonist cocktail would reduce both cocaine relapse and post-cocaine working memory deficits. Adult male Sprague-Dawley rats were first trained and tested in an operant delayed match-to-sample (DMS) task to establish the working memory baseline, followed by 6 days of limited and 12 days of extended access cocaine self-administration. Chronic cocaine reduced working memory performance (abstinence day 30-40) and produced robust time-dependent cocaine seeking at 45-, but not 120-days of abstinence. Systemic administration of A2a antagonist KW-6002 (0.125 and 1 mg/kg) failed to rescue post-cocaine working memory deficit. It also failed to reverse working memory impairment produced by mGlu5 NAM MTEP (1 mg/kg). Finally, KW-6002 prevented the ability of MTEP to reduce cocaine seeking and increased locomotor behavior. Thus, despite mGlu5 and A2a being exclusively co-localized in the striatum and showing behavioral synergism towards reducing cocaine effects in some studies, our findings advocate against the use of mGlu5 + A2a antagonist cocktail as it may further compromise cognitive deficits and augment drug craving in CUD.
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Affiliation(s)
- Peter U Hámor
- Department of Psychology, University of Florida, FL, USA; Center for Addiction Education and Research, University of Florida, FL, USA
| | - Christina M Gobin
- Center for Addiction Education and Research, University of Florida, FL, USA; Department of Pharmacodynamics, University of Florida, FL, USA
| | - Marek Schwendt
- Department of Psychology, University of Florida, FL, USA; Center for Addiction Education and Research, University of Florida, FL, USA.
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Sun MJ, Liu F, Zhao YF, Wu XA. In Vivo Positron Emission Tomography Imaging of Adenosine A 2A Receptors. Front Pharmacol 2020; 11:599857. [PMID: 33324226 PMCID: PMC7726429 DOI: 10.3389/fphar.2020.599857] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/04/2020] [Indexed: 02/05/2023] Open
Abstract
As an invasive nuclear medical imaging technology, positron emission tomography (PET) possess the possibility to imaging the distribution as well as the density of selective receptors via specific PET tracers. Inspired by PET, the development of radio-chemistry has greatly promoted the progress of innovative imaging PET tracers for adenosine receptors, in particular adenosine A2A receptors (A2ARs). PET imaging of A2A receptors play import roles in the research of adenosine related disorders. Several radio-tracers for A2A receptors imaging have been evaluated in human studies. This paper reviews the recent research progress of PET tracers for A2A receptors imaging, and their applications in the diagnosis and treatment of related disease, such as cardiovascular diseases, autoimmune diseases, neurodegenerative and psychiatric disease. The future development of A2A PET tracers were also discussed.
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Affiliation(s)
- Meng-Juan Sun
- Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China
| | - Fang Liu
- Department of Laboratory Pathology, Xijing Hospital, Fourth Military Medical University, Xian, China
| | - Ya-Fei Zhao
- Chengdu University of Traditional Chinese Medicine, Chengdu, China
- Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China
| | - Xiao-Ai Wu
- Department of Nuclear Medicine, Laboratory of Clinical Nuclear Medicine, West China Hospital, Sichuan University, Chengdu, China
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Tracers for non-invasive radionuclide imaging of immune checkpoint expression in cancer. EJNMMI Radiopharm Chem 2019; 4:29. [PMID: 31696402 PMCID: PMC6834817 DOI: 10.1186/s41181-019-0078-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/21/2019] [Indexed: 12/11/2022] Open
Abstract
Abstract Immunotherapy with checkpoint inhibitors demonstrates impressive improvements in the treatment of several types of cancer. Unfortunately, not all patients respond to therapy while severe immune-related adverse effects are prevalent. Currently, patient stratification is based on immunotherapy marker expression through immunohistochemical analysis on biopsied material. However, expression can be heterogeneous within and between tumor lesions, amplifying the sampling limitations of biopsies. Analysis of immunotherapy target expression by non-invasive quantitative molecular imaging with PET or SPECT may overcome this issue. In this review, an overview of tracers that have been developed for preclinical and clinical imaging of key immunotherapy targets, such as programmed cell death-1, programmed cell death ligand-1, IDO1 and cytotoxic T lymphocyte-associated antigen-4 is presented. We discuss important aspects to consider when developing such tracers and outline the future perspectives of molecular imaging of immunotherapy markers. Graphical abstract Current techniques in immune checkpoint imaging and its potential for future applications ![]()
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Occupancy of adenosine A 2A receptors by istradefylline in patients with Parkinson's disease using 11C-preladenant PET. Neuropharmacology 2018; 143:106-112. [PMID: 30253174 DOI: 10.1016/j.neuropharm.2018.09.036] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/19/2018] [Accepted: 09/21/2018] [Indexed: 12/20/2022]
Abstract
Istradefylline, an adenosine A2A receptor (A2AR) antagonist, is effective as an adjunct to levodopa and can alleviate "off" time and motor symptoms in patients with Parkinson's disease (PD). The present study aimed to calculate occupancy rates of A2ARs by administrating istradefylline 20 mg or 40 mg, which is the currently approved dose for PD in Japan. Additionally, A2AR availability was compared between patients with PD and healthy controls. Ten patients with PD under levodopa therapy and six age-matched healthy controls were included. The patients underwent a total of two 11C-preladenant positron emission tomography scans before and after the administration of istradefylline 20 mg or 40 mg (both n = 5). Binding potential (BPND) was calculated to estimate A2AR availability in the ventral striatum, caudate, and putamen. Maximal A2AR occupancy and ED50 were estimated by modeling the dose-occupancy curves. All patients were around the middle stage of PD, and their characteristics were clinically heterogeneous. Maximal A2AR occupancy and ED50 were 93.5% and 28.6 mg in the ventral striatum, 69.5% and 10.8 mg in the caudate, and 66.8% and 14.8 mg in the putamen, respectively. There were no significant differences in BPND values in the ventral striatum (P = 0.42), caudate (P = 0.72), and putamen (P = 0.43) between the PD and control groups. In conclusion, the present study shows that istradefylline binds to A2ARs dose-dependently. A sufficient occupancy of A2ARs could be obtained by administrating the approved dose of istradefylline.
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Högel H, Rissanen E, Vuorimaa A, Airas L. Positron emission tomography imaging in evaluation of MS pathology in vivo. Mult Scler 2018; 24:1399-1412. [DOI: 10.1177/1352458518791680] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Positron emission tomography (PET) gives an opportunity to quantitate the expression of specific molecular targets in vivo and longitudinally in brain and thus enhances our possibilities to understand and follow up multiple sclerosis (MS)-related pathology. For successful PET imaging, one needs a relevant target molecule within the brain, to which a blood–brain barrier–penetrating specific radioligand will bind. 18-kDa translocator protein (TSPO)-binding radioligands have been used to detect activated microglial cells at different stages of MS, and remyelination has been measured using amyloid PET. Several PET ligands for the detection of other inflammatory targets, besides TSPO, have been developed but not yet been used for imaging MS patients. Finally, synaptic density evaluation has been successfully tested in human subjects and gives opportunities for the evaluation of the development of cortical and deep gray matter pathology in MS. This review will discuss PET imaging modalities relevant for MS today.
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Affiliation(s)
- Heidi Högel
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland/Division of Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
| | - Eero Rissanen
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland/Division of Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
| | - Anna Vuorimaa
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland/Division of Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
| | - Laura Airas
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland/Division of Clinical Neurosciences, Turku University Hospital and University of Turku, Turku, Finland
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Blum D, Chern Y, Domenici MR, Buée L, Lin CY, Rea W, Ferré S, Popoli P. The Role of Adenosine Tone and Adenosine Receptors in Huntington's Disease. J Caffeine Adenosine Res 2018; 8:43-58. [PMID: 30023989 PMCID: PMC6049521 DOI: 10.1089/caff.2018.0006] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by a mutation in the IT15 gene that encodes for the huntingtin protein. Mutated hungtingtin, although widely expressed in the brain, predominantly affects striato-pallidal neurons, particularly enriched with adenosine A2A receptors (A2AR), suggesting a possible involvement of adenosine and A2AR is the pathogenesis of HD. In fact, polymorphic variation in the ADORA2A gene influences the age at onset in HD, and A2AR dynamics is altered by mutated huntingtin. Basal levels of adenosine and adenosine receptors are involved in many processes critical for neuronal function and homeostasis, including modulation of synaptic activity and excitotoxicity, the control of neurotrophin levels and functions, and the regulation of protein degradation mechanisms. In the present review, we critically analyze the current literature involving the effect of altered adenosine tone and adenosine receptors in HD and discuss why therapeutics that modulate the adenosine system may represent a novel approach for the treatment of HD.
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Affiliation(s)
- David Blum
- University of Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc, LabEx DISTALZ, Lille, France
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Maria Rosaria Domenici
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
| | - Luc Buée
- University of Lille, Inserm, CHU Lille, UMR-S 1172 - JPArc, LabEx DISTALZ, Lille, France
| | - Chien-Yu Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - William Rea
- Integrative Neurobiology Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland
| | - Sergi Ferré
- Integrative Neurobiology Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, Maryland
| | - Patrizia Popoli
- National Center for Drug Research and Evaluation, Istituto Superiore di Sanità, Rome, Italy
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In Vivo PET Imaging of Adenosine 2A Receptors in Neuroinflammatory and Neurodegenerative Disease. CONTRAST MEDIA & MOLECULAR IMAGING 2017; 2017:6975841. [PMID: 29348737 PMCID: PMC5733838 DOI: 10.1155/2017/6975841] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/18/2017] [Indexed: 01/01/2023]
Abstract
Adenosine receptors are G-protein coupled P1 purinergic receptors that are broadly expressed in the peripheral immune system, vasculature, and the central nervous system (CNS). Within the immune system, adenosine 2A (A2A) receptor-mediated signaling exerts a suppressive effect on ongoing inflammation. In healthy CNS, A2A receptors are expressed mainly within the neurons of the basal ganglia. Alterations in A2A receptor function and expression have been noted in movement disorders, and in Parkinson's disease pharmacological A2A receptor antagonism leads to diminished motor symptoms. Although A2A receptors are expressed only at a low level in the healthy CNS outside striatum, pathological challenge or inflammation has been shown to lead to upregulation of A2A receptors in extrastriatal CNS tissue, and this has been successfully quantitated using in vivo positron emission tomography (PET) imaging and A2A receptor-binding radioligands. Several radioligands for PET imaging of A2A receptors have been developed in recent years, and A2A receptor-targeting PET imaging may thus provide a potential additional tool to evaluate various aspects of neuroinflammation in vivo. This review article provides a brief overview of A2A receptors in healthy brain and in a selection of most important neurological diseases and describes the recent advances in A2A receptor-targeting PET imaging studies.
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Altered adenosine 2A and dopamine D2 receptor availability in the 6-hydroxydopamine-treated rats with and without levodopa-induced dyskinesia. Neuroimage 2017; 157:209-218. [PMID: 28583881 DOI: 10.1016/j.neuroimage.2017.05.066] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 05/30/2017] [Accepted: 05/31/2017] [Indexed: 11/22/2022] Open
Abstract
Several lines of evidence imply alterations in adenosine signaling in Parkinson's disease (PD). Here, we investigated cerebral changes in adenosine 2A receptor (A2AR) availability in 6-hydroxydopamine (6-OHDA)-lesioned rats with and without levodopa-induced dyskinesia (LID) using positron-emission tomography (PET) with [11C]preladenant. In parallel dopamine type 2 receptor (D2R) imaging with [11C]raclopride PET and behavioral tests for motor and cognitive function were performed. METHODS Parametric A2AR and D2R binding potential (BPND) images were reconstructed using reference tissue models with midbrain and cerebellum as reference tissue, respectively. All images were anatomically standardized to Paxinos space and analyzed using volume-of-interest (VOI) and voxel-based approaches. The behavioral alternations were assessed with the open field test, Y-maze, novel object recognition test, cylinder test, and abnormal involuntary movement (AIM) score. In total, 28 female Wistar rats were included. RESULTS On the behavioral level, 6-OHDA-lesioned rats showed asymmetry in forepaw use and deficits in spatial memory and explorative behavior as compared to the sham-operated animals. 15-Days of levodopa (L-DOPA) treatment induced dyskinesia but did not alleviate motor deficits in PD rats. Intranigral 6-OHDA injection significantly increased D2R binding in the lesioned striatum (BPND: 2.69 ± 0.40 6-OHDA vs. 2.31 ± 0.18 sham, + 16.6%; p = 0.03), whereas L-DOPA treatment did not affect the D2R binding in the ipsilateral striatum of the PD rats. In addition, intranigral 6-OHDA injection tended to decrease the A2AR availability in the lesioned striatum. The decrease became significant when data were normalized to the non-affected side (BPND: 4.32 ± 0.41 6-OHDA vs. 4.58 ± 0.89 sham; NS, ratio: 0.94 ± 0.03 6-OHDA vs. 1.00 ± 0.02 sham; - 6.1%; p = 0.01). L-DOPA treatment significantly increased A2AR binding in the affected striatum (BPND: 6.02 ± 0.91 L-DOPA vs. 4.90 ± 0.76 saline; + 23.4%; p = 0.02). In PD rats with LID, positive correlations were found between D2R and A2AR BPND values in the ipsilateral striatum (r = 0.88, ppeak = 8.56.10-4 uncorr), and between AIM score and the D2R BPND in the contralateral striatum (r = 0.98; ppeak = 9.55.10-5 uncorr). CONCLUSION A2AR availability changed in drug-naïve and in L-DOPA-treated PD rats. The observed correlations of striatal D2R availability with A2AR availability and with AIM score may provide new knowledge on striatal physiology and new possibilities to further unravel the functions of these targets in the pathophysiology of PD.
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Sakata M, Ishibashi K, Imai M, Wagatsuma K, Ishii K, Zhou X, de Vries EF, Elsinga PH, Ishiwata K, Toyohara J. Initial Evaluation of an Adenosine A2A Receptor Ligand, 11C-Preladenant, in Healthy Human Subjects. J Nucl Med 2017; 58:1464-1470. [DOI: 10.2967/jnumed.116.188474] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Accepted: 02/13/2017] [Indexed: 12/15/2022] Open
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15
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Zhou X, Boellaard R, Ishiwata K, Sakata M, Dierckx RAJO, de Jong JR, Nishiyama S, Ohba H, Tsukada H, de Vries EFJ, Elsinga PH. In Vivo Evaluation of 11C-Preladenant for PET Imaging of Adenosine A 2A Receptors in the Conscious Monkey. J Nucl Med 2017; 58:762-767. [PMID: 28062599 DOI: 10.2967/jnumed.116.182410] [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] [Received: 08/10/2016] [Accepted: 11/10/2016] [Indexed: 12/22/2022] Open
Abstract
11C-preladenant was developed as a novel PET ligand for the adenosine A2A receptors (A2ARs). The present study aimed to evaluate the suitability of 11C-preladenant PET for the quantification of striatal A2ARs and the assessment of A2AR occupancy in the conscious monkey brain. Methods:11C-preladenant was intravenously injected into conscious monkeys (n = 4, 18 PET scans), and a 91-min dynamic scan was started. Arterial blood samples in combination with metabolite analysis were obtained during the scan to provide the input function for kinetic modeling. The distribution volume (VT) was obtained by kinetic modeling with a 2-tissue-compartment model. The simplified reference tissue model (SRTM) with selected reference regions (cerebellum, cingulate, parietal cortex, and occipital cortex) was tested to estimate the binding potential (BPND) in A2AR-rich regions. BPND obtained from the SRTM was compared with distribution volume ratio (DVR)-1. The effects of blood volume, blood delay, and scan duration on BPND and DVR-1 were investigated. VT and BPND were also obtained after preblocking with unlabeled preladenant (1 mg/kg), A2AR-selective KW-6002 (0.5-1 mg/kg), and nonselective adenosine receptor antagonist caffeine (2.5-10 mg/kg). A2AR occupancy was studied with caffeine blockade. Results: Regional uptake of 11C-preladenant was consistent with the distribution of A2ARs in the monkey brain, with the highest uptake in the putamen, followed by the caudate, and the lowest uptake in the cerebellum. Tracer kinetics were well described by the 2-tissue-compartment model with a lower constraint on k4 to stabilize fits. The highest VT was observed in A2AR-rich regions (∼5.8-7.4) and lowest value in the cerebellum (∼1.3). BPND values estimated from the SRTM with different scan durations were comparable and were in agreement with DVR-1 (∼4.3-5.3 in A2AR-rich regions). Preladenant preinjection decreased the tracer uptake in A2AR-rich regions to the level of the reference regions. Caffeine pretreatment reduced the tracer uptake in the striatum in a dose-dependent manner. Conclusion:11C-preladenant PET is suitable for noninvasive quantification of A2ARs and assessment of A2AR occupancy in A2AR-rich regions in the monkey brain. SRTM using the cerebellum as the reference tissue is the applicable model for A2AR quantification.
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Affiliation(s)
- Xiaoyun Zhou
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Ronald Boellaard
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Kiichi Ishiwata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.,Institute of Cyclotron and Drug Discovery Research, Southern TOHOKU Research Institute for Neuroscience, Koriyama, Japan.,Department of Biofunctional Imaging, Fukushima Medical University, Fukushima, Japan; and
| | - Muneyuki Sakata
- Research Team for Neuroimaging, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan
| | - Rudi A J O Dierckx
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Johan R de Jong
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Shingo Nishiyama
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu, Japan
| | - Hiroyuki Ohba
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu, Japan
| | - Hideo Tsukada
- Central Research Laboratory, Hamamatsu Photonics K.K., Hamamatsu, Japan
| | - Erik F J de Vries
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Philip H Elsinga
- University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Khanapur S, van Waarde A, Dierckx RAJO, Elsinga PH, Koole MJB. Preclinical Evaluation and Quantification of 18F-Fluoroethyl and 18F-Fluoropropyl Analogs of SCH442416 as Radioligands for PET Imaging of the Adenosine A 2A Receptor in Rat Brain. J Nucl Med 2016; 58:466-472. [PMID: 27789720 DOI: 10.2967/jnumed.116.178103] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 10/02/2016] [Indexed: 11/16/2022] Open
Abstract
The cerebral adenosine A2A receptor is an attractive therapeutic target for neuropsychiatric disorders. 18F-fluoroethyl and 18F-fluoropropyl analogs of 18F-labeled pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH442416) (18F-FESCH and 18F-FPSCH, respectively) were developed as A2A receptor-specific PET ligands. Our aim was to determine an appropriate compartmental model for tracer kinetics, evaluate a reference tissue approach, and select the most suitable PET ligand. Methods: A 90-min dynamic PET scan with arterial blood sampling and metabolite analysis was acquired for 22 healthy male Wistar rats starting at the time of 18F-FESCH (n = 12) and 18F-FPSCH (n = 10) injection. For each tracer, half the animals were vehicle-treated whereas the other half were pretreated with the A2A receptor-selective antagonist KW-6002, inducing full blocking. Regional tissue total volume of distribution (VT) was estimated by 1- and 2-tissue-compartment modeling (1TCM and 2TCM, respectively) and Logan graphical analysis. Midbrain, cerebellum, and hippocampus were evaluated as the reference region by comparing baseline VT with VT under full blocking conditions and comparing striatal nondisplaceable binding potential (BPND) using a simplified reference tissue model (SRTM) with distribution volume ratio minus 1 (DVR - 1) for 60- and 90-min scans. Results: On the basis of the Akaike information criterion, 1TCM and 2TCM were the most appropriate models for 18F-FPSCH (baseline striatal VT, 3.7 ± 1.1) and 18F-FESCH (baseline striatal VT, 5.0 ± 2.0), respectively. Baseline striatal VT did not significantly differ between tracers. After pretreatment, striatal VT was reduced significantly, with no significant decrease in hippocampus, midbrain, or cerebellum VT Baseline striatal SRTM BPND did not differ significantly from DVR - 1 except for 18F-FPSCH when using a 60-min scan and midbrain as the reference region, whereas Bland-Altman analysis found a smaller bias for 18F-FESCH and a 60-min scan. After pretreatment, striatal SRTM BPND did not significantly differ from zero except for 18F-FPSCH when using hippocampus as the reference region. Striatal SRTM BPND using midbrain or cerebellum as the reference region was significantly lower for 18F-FPSCH (range, 1.41-2.62) than for 18F-FESCH (range, 1.64-3.36). Conclusion: Dynamic PET imaging under baseline and blocking conditions determined 18F-FESCH to be the most suitable PET ligand for quantifying A2A receptor expression in the rat brain. Accurate quantification is achieved by a 60-min dynamic PET scan and the use of either cerebellum or midbrain as the reference region.
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Affiliation(s)
- Shivashankar Khanapur
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Michel J B Koole
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and .,Department of Nuclear Medicine and Molecular Imaging, KU Leuven, Leuven, Belgium
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