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Vāvere AL, Ghosh A, Amador Diaz V, Clay AJ, Hall PM, Neumann KD. Automated radiosynthesis of [ 18F]DPA-714 on a commercially available IBA Synthera®. Appl Radiat Isot 2024; 207:111257. [PMID: 38461627 PMCID: PMC10984111 DOI: 10.1016/j.apradiso.2024.111257] [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: 11/28/2023] [Revised: 02/08/2024] [Accepted: 02/25/2024] [Indexed: 03/12/2024]
Abstract
The goal of this work was to develop a reliable method to produce the well-validated microglial activation PET tracer, [18F]DPA-714, routinely for clinical and preclinical research using an IBA Synthera®. Optimization of literature methods included reduced precursor mass and use of TBA HCO3 as the phase transfer agent in place of Kryptofix® 222 in a 65-min synthesis with an average activity yield of 24.6 ± 3.8% (n = 5). Successful quality control testing and process validation results are reported.
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Affiliation(s)
- Amy L Vāvere
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA.
| | - Arijit Ghosh
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Victor Amador Diaz
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Allison J Clay
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Peter M Hall
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Kiel D Neumann
- Department of Diagnostic Imaging, St. Jude Children's Research Hospital, Memphis, TN, USA
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2
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Ovdiichuk O, Lahdenpohja S, Béen Q, Tanguy L, Kuhnast B, Collet-Defossez C. [ 18F]fluoride Activation and 18F-Labelling in Hydrous Conditions-Towards a Microfluidic Synthesis of PET Radiopharmaceuticals. Molecules 2023; 29:147. [PMID: 38202730 PMCID: PMC10779751 DOI: 10.3390/molecules29010147] [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: 10/27/2023] [Revised: 12/15/2023] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
18F-labelled radiopharmaceuticals are indispensable in positron emission tomography. The critical step in the preparation of 18F-labelled tracers is the anhydrous F-18 nucleophilic substitution reaction, which involves [18F]F- anions generated in aqueous media by the cyclotron. For this, azeotropic drying by distillation is widely used in standard synthesisers, but microfluidic systems are often not compatible with such a process. To avoid this step, several methods compatible with aqueous media have been developed. We summarised the existing approaches and two of them have been studied in detail. [18F]fluoride elution efficiencies have been investigated under different conditions showing high 18F-recovery. Finally, a large scope of precursors has been assessed for radiochemical conversion, and these hydrous labelling techniques have shown their potential for tracer production using a microfluidic approach, more particularly compatible with iMiDEV™ cassette volumes.
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Affiliation(s)
- Olga Ovdiichuk
- Nancyclotep, Molecular Imaging Platform, 54500 Vandoeuvre-les-Nancy, France
| | - Salla Lahdenpohja
- Université Paris Saclay, CEA Inserm, CNRS, BioMaps, 91401 Orsay, France
| | - Quentin Béen
- Nancyclotep, Molecular Imaging Platform, 54500 Vandoeuvre-les-Nancy, France
| | | | - Bertrand Kuhnast
- Université Paris Saclay, CEA Inserm, CNRS, BioMaps, 91401 Orsay, France
| | - Charlotte Collet-Defossez
- Nancyclotep, Molecular Imaging Platform, 54500 Vandoeuvre-les-Nancy, France
- Université de Lorraine, Inserm, IADI, 54000 Nancy, France
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Uzuegbunam BC, Rummel C, Librizzi D, Culmsee C, Hooshyar Yousefi B. Radiotracers for Imaging of Inflammatory Biomarkers TSPO and COX-2 in the Brain and in the Periphery. Int J Mol Sci 2023; 24:17419. [PMID: 38139248 PMCID: PMC10743508 DOI: 10.3390/ijms242417419] [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: 10/24/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 12/24/2023] Open
Abstract
Inflammation involves the activation of innate immune cells and is believed to play an important role in the development and progression of both infectious and non-infectious diseases such as neurodegeneration, autoimmune diseases, pulmonary and cancer. Inflammation in the brain is marked by the upregulation of translocator protein (TSPO) in microglia. High TSPO levels are also found, for example, in macrophages in cases of rheumatoid arthritis and in malignant tumor cells compared to their relatively low physiological expression. The same applies for cyclooxgenase-2 (COX-2), which is constitutively expressed in the kidney, brain, thymus and gastrointestinal tract, but induced in microglia, macrophages and synoviocytes during inflammation. This puts TSPO and COX-2 in the spotlight as important targets for the diagnosis of inflammation. Imaging modalities, such as positron emission tomography and single-photon emission tomography, can be used to localize inflammatory processes and to track their progression over time. They could also enable the monitoring of the efficacy of therapy and predict its outcome. This review focuses on the current development of PET and SPECT tracers, not only for the detection of neuroinflammation, but also for emerging diagnostic measures in infectious and other non-infectious diseases such as rheumatic arthritis, cancer, cardiac inflammation and in lung diseases.
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Affiliation(s)
| | - Christoph Rummel
- Institute of Veterinary Physiology and Biochemistry, Justus Liebig University Giessen, 35392 Gießen, Germany;
- Center for Mind Brain and Behavior, Universities Giessen and Marburg, 35043 Marburg, Germany;
| | - Damiano Librizzi
- Department of Nuclear Medicine, Philipps University of Marburg, 35043 Marburg, Germany;
| | - Carsten Culmsee
- Center for Mind Brain and Behavior, Universities Giessen and Marburg, 35043 Marburg, Germany;
- Institute of Pharmacology and Clinical Pharmacy, Philipps University of Marburg, 35037 Marburg, Germany
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Porret E, Kereselidze D, Dauba A, Schweitzer-Chaput A, Jegot B, Selingue E, Tournier N, Larrat B, Novell A, Truillet C. Refining the delivery and therapeutic efficacy of cetuximab using focused ultrasound in a mouse model of glioblastoma: An 89Zr-cetuximab immunoPET study. Eur J Pharm Biopharm 2023; 182:141-151. [PMID: 36529256 DOI: 10.1016/j.ejpb.2022.12.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 12/04/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Glioblastoma (GBM) is the most common and deadly form of primary brain tumor. Between 30 % and 60 % of GBM are characterized by overexpression of the Epidermal Growth Factor Receptor (EGFR). The anti-EGFR antibody Cetuximab (CTX) showed a favorable effect for EGFR+ colorectal cancer but failed to demonstrate efficacy for GBM. Insufficient CTX passage through the blood-brain barrier (BBB) and the blood-tumor barrier (BTB) is assumed to be the primary determinant of the limited efficacy of this immunotherapy. OBJECTIVE Using positron emission tomography (PET) imaging, we have previously demonstrated that focused ultrasound (FUS) combined with microbubbles (µB) allowed significant and persistent delivery of CTX across the BBB in healthy mice. In the current study, we investigated by PET imaging the combination impact of CTX and FUS on orthotopic GBM preclinical model. METHODS After radiolabeling CTX with the long half-life isotope 89Zr, PET images have been acquired overtime in mice bearing U251 (EGFR+) with or without FUS treatment. Autoradiography combined with immunofluorescence staining was used to corroborate CTX delivery with EGFR expression. A survival study was conducted simultaneously to evaluate the therapeutic benefit of repeated CTX monotherapy associated or not with FUS. RESULTS Ex vivo analysis confirmed that FUS enhanced and homogenized the delivery of CTX into all the FUS exposure area, including the tumor and the contralateral hemisphere at the early-time-point. Interestingly, FUS did not improve the long-term accumulation and retention of CTX in the tumor compared with the control group (no FUS). No significant difference in the CTX treatment efficacy, determined by the survival between FUS and non-FUS groups, has been either observed. This result is consistent with the absence of change in the CTX distribution through the GBM tumor after FUS. The neuroinflammation induced by FUS is not significant enough to explain the failure of the CTX delivery improvement. CONCLUSION All together, these data suggest that the role of FUS combined with µB on the CTX distribution, even after multiple therapeutic sessions and glial cell activation is insufficient to improve survival of GBM mice compared with CTX treatment alone in this model.
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Affiliation(s)
- Estelle Porret
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France
| | - Dimitri Kereselidze
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France
| | - Ambre Dauba
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France
| | - Arnaud Schweitzer-Chaput
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France
| | - Benoit Jegot
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France
| | - Erwan Selingue
- Université Paris-Saclay, CEA, CNRS, NeuroSpin/BAOBAB, Centre d'études de Saclay, Bâtiment 145, 91191 Gif sur Yvette, France
| | - Nicolas Tournier
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France
| | - Benoît Larrat
- Université Paris-Saclay, CEA, CNRS, NeuroSpin/BAOBAB, Centre d'études de Saclay, Bâtiment 145, 91191 Gif sur Yvette, France
| | - Anthony Novell
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France
| | - Charles Truillet
- Université Paris-Saclay, CEA, CNRS, Inserm, BioMaps, Service Hospitalier Frédéric Joliot, 4 place du général Leclerc, 91401 Orsay, France.
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TSPO PET Imaging as a Potent Non-Invasive Biomarker for Diffuse Intrinsic Pontine Glioma in a Patient-Derived Orthotopic Rat Model. Int J Mol Sci 2022; 23:ijms232012476. [PMID: 36293329 PMCID: PMC9603997 DOI: 10.3390/ijms232012476] [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: 09/25/2022] [Revised: 10/07/2022] [Accepted: 10/13/2022] [Indexed: 11/16/2022] Open
Abstract
Diffuse intrinsic pontine gliomas (DIPG), the first cause of cerebral pediatric cancer death, will greatly benefit from specific and non-invasive biomarkers for patient follow-up and monitoring of drug efficacy. Since biopsies are challenging for brain tumors, molecular imaging may be a technique of choice to target and follow tumor evolution. So far, MR remains the imaging technique of reference for DIPG, although it often fails to define the extent of tumors, an essential parameter for therapeutic efficacy assessment. Thanks to its high sensitivity, positron emission tomography (PET) offers a unique way to target specific biomarkers in vivo. We demonstrated in a patient-derived orthotopic xenograft (PDOX) model in the rat that the translocator protein of 18 kDa (TSPO) may be a promising biomarker for monitoring DIPG tumors. We studied the distribution of 18F-DPA-714, a TSPO radioligand, in rats inoculated with HSJD-DIPG-007 cells. The primary DIPG human cell line HSJD-DIPG-007 highly represents this pediatric tumor, displaying the most prevalent DIPG mutations, H3F3A (K27M) and ACVR1 (R206H). Kinetic modeling and parametric imaging using the brain 18F-DPA-714 PET data enabled specific delineation of the DIPG tumor area, which is crucial for radiotherapy dose management.
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McCauley KS, Wilde JH, Bufalino SM, Neumann KD. An automated radiosynthesis of [ 18F]DPA-714 on a commercially available radiosynthesizer, Elixys Flex/Chem. Appl Radiat Isot 2022; 180:110032. [PMID: 34871885 PMCID: PMC8858596 DOI: 10.1016/j.apradiso.2021.110032] [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: 08/06/2021] [Revised: 11/04/2021] [Accepted: 11/16/2021] [Indexed: 02/03/2023]
Abstract
[18F]DPA-714 is a radiotracer specific to the translocator protein (TSPO) and is useful for in vivo Positron Emission Tomography imaging studies. In this report, we have developed an automated radiosynthesis of [18F]DPA-714 on a commercially-available radiosynthesis platform, which comports with USP <823> guidelines. The wide availability of the radiosynthesis module and ease of dissemination of the production sequence will facilitate preclinical and clinical research of TSPO-related pathology.
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Affiliation(s)
- Katelyenn S. McCauley
- Department of Radiology and Medical Imaging, University of
Virginia, Charlottesville, VA, USA
| | - Justin H. Wilde
- Department of Radiology and Medical Imaging, University of
Virginia, Charlottesville, VA, USA
| | - Sophia M. Bufalino
- Department of Chemistry, University of Virginia,
Charlottesville, VA, USA
| | - Kiel D. Neumann
- Department of Radiology and Medical Imaging, University of
Virginia, Charlottesville, VA, USA,Emily Couric Clinical Cancer Center, University of
Virginia, Charlottesville, VA, USA
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Lee SH, Denora N, Laquintana V, Mangiatordi GF, Lopedota A, Lopalco A, Cutrignelli A, Franco M, Delre P, Song IH, Kim HW, Kim SB, Park HS, Kim K, Lee SY, Youn H, Lee BC, Kim SE. Radiosynthesis and characterization of [ 18F]BS224: a next-generation TSPO PET ligand insensitive to the rs6971 polymorphism. Eur J Nucl Med Mol Imaging 2021; 49:110-124. [PMID: 34783879 PMCID: PMC8712300 DOI: 10.1007/s00259-021-05617-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 11/03/2021] [Indexed: 01/03/2023]
Abstract
PURPOSE Translocator protein 18-kDa (TSPO) positron emission tomography (PET) is a valuable tool to detect neuroinflammed areas in a broad spectrum of neurodegenerative diseases. However, the clinical application of second-generation TSPO ligands as biomarkers is limited because of the presence of human rs6971 polymorphism that affects their binding. Here, we describe the ability of a new TSPO ligand, [18F]BS224, to identify abnormal TSPO expression in neuroinflammation independent of the rs6971 polymorphism. METHODS An in vitro competitive inhibition assay of BS224 was conducted with [3H]PK 11195 using membrane proteins isolated from 293FT cells expressing TSPO-wild type (WT) or TSPO-mutant A147T (Mut), corresponding to a high-affinity binder (HAB) and low-affinity binder (LAB), respectively. Molecular docking was performed to investigate the interaction of BS224 with the binding sites of rat TSPO-WT and TSPO-Mut. We synthesized a new 18F-labeled imidazopyridine acetamide ([18F]BS224) using boronic acid pinacol ester 6 or iodotoluene tosylate precursor 7, respectively, via aromatic 18F-fluorination. Dynamic PET scanning was performed up to 90 min after the injection of [18F]BS224 to healthy mice, and PET imaging data were obtained to estimate its absorbed doses in organs. To evaluate in vivo TSPO-specific uptake of [18F]BS224, lipopolysaccharide (LPS)-induced inflammatory and ischemic stroke rat models were used. RESULTS BS224 exhibited a high affinity (Ki = 0.51 nM) and selectivity for TSPO. The ratio of IC50 values of BS224 for LAB to that for HAB indicated that the TSPO binding affinity of BS224 has low binding sensitivity to the rs6971 polymorphism and it was comparable to that of PK 11195, which is not sensitive to the polymorphism. Docking simulations showed that the binding mode of BS224 is not affected by the A147T mutation and consequently supported the observed in vitro selectivity of [18F]BS224 regardless of polymorphisms. With optimal radiochemical yield (39 ± 6.8%, decay-corrected) and purity (> 99%), [18F]BS224 provided a clear visible image of the inflammatory lesion with a high signal-to-background ratio in both animal models (BPND = 1.43 ± 0.17 and 1.57 ± 0.37 in the LPS-induced inflammatory and ischemic stroke rat models, respectively) without skull uptake. CONCLUSION Our results suggest that [18F]BS224 may be a promising TSPO ligand to gauge neuroinflammatory disease-related areas in a broad range of patients irrespective of the common rs6971 polymorphism.
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Affiliation(s)
- Sang Hee Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
| | - Nunzio Denora
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Valentino Laquintana
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | | | - Angela Lopedota
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Antonio Lopalco
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Annalisa Cutrignelli
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Massimo Franco
- Department of Pharmacy – Drug Sciences, University of Bari “A. Moro”, 70121 Bari, Italy
| | - Pietro Delre
- Institute of Crystallography, National Research Council, Via G. Amendola 122/O, 70126 Bari, Italy
- Department of Chemistry, University of Bari “A. Moro”, Via E. Orabona, 4, 70125 Bari, Italy
| | - In Ho Song
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
| | - Hye Won Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
| | - Su Bin Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Department of Transdisciplinary Studies, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
| | - Hyun Soo Park
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
| | - Kyungmin Kim
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul, 03080 Republic of Korea
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, 03080 Republic of Korea
- Laboratory of Molecular Imaging and Therapy, Cancer Research Institute, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea
| | - Seok-Yong Lee
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul, 03080 Republic of Korea
- Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, 03080 Republic of Korea
- Laboratory of Molecular Imaging and Therapy, Cancer Research Institute, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea
| | - Hyewon Youn
- Department of Nuclear Medicine, Seoul National University Hospital, Seoul, 03080 Republic of Korea
- Laboratory of Molecular Imaging and Therapy, Cancer Research Institute, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea
| | - Byung Chul Lee
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon, 16229 Republic of Korea
| | - Sang Eun Kim
- Department of Nuclear Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, 13620 Republic of Korea
- Center for Nanomolecular Imaging and Innovative Drug Development, Advanced Institutes of Convergence Technology, Suwon, 16229 Republic of Korea
- Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul, 08826 Republic of Korea
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Cybulska KA, Bloemers V, Perk LR, Laverman P. Optimised GMP-compliant production of [ 18F]DPA-714 on the Trasis AllinOne module. EJNMMI Radiopharm Chem 2021; 6:20. [PMID: 34037896 PMCID: PMC8155128 DOI: 10.1186/s41181-021-00133-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 04/09/2021] [Indexed: 11/12/2022] Open
Abstract
Background The translocator protein 18 kDa is recognised as an important biomarker for neuroinflammation due to its soaring expression in microglia. This process is common for various neurological disorders. DPA-714 is a potent TSPO-specific ligand which found its use in Positron Emission Tomography following substitution of fluorine-19 with fluorine-18, a positron-emitting radionuclide. [18F]DPA-714 enables visualisation of inflammatory processes in vivo non-invasively. Radiolabelling of this tracer is well described in literature, including validation for clinical use. Here, we report significant enhancements to the process which resulted in the design of a fully GMP-compliant robust synthesis of [18F]DPA-714 on a popular cassette-based system, Trasis AllinOne, boosting reliability, throughput, and introducing a significant degree of simplicity. Results [18F]DPA-714 was synthesised using the classic nucleophilic aliphatic substitution on a good leaving group, tosylate, with [18F]fluoride using tetraethylammonium bicarbonate in acetonitrile at 100∘C. The process was fully automated on a Trasis AllinOne synthesiser using an in-house designed cassette and sequence. With a relatively small precursor load of 4 mg, [18F]DPA-714 was obtained with consistently high radiochemical yields of 55-71% (n=6) and molar activities of 117-350 GBq/µmol at end of synthesis. With a single production batch, starting with 31-42 GBq of [18F]fluoride, between 13-20 GBq of the tracer can be produced, enabling multi-centre studies. Conclusion To the best of our knowledge, the process presented herein is the most efficient [18F]DPA-714 synthesis, with advantageous GMP compliance. The use of a Trasis AllinOne synthesiser increases reliability and allows rapid training of production staff.
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Affiliation(s)
- Klaudia A Cybulska
- Radboud Translational Medicine B.V., Geert Grooteplein 21, Nijmegen, 6525 EZ, Netherlands. .,Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein 10, Nijmegen, 6525 GA, Netherlands.
| | - Vera Bloemers
- Radboud Translational Medicine B.V., Geert Grooteplein 21, Nijmegen, 6525 EZ, Netherlands
| | - Lars R Perk
- Radboud Translational Medicine B.V., Geert Grooteplein 21, Nijmegen, 6525 EZ, Netherlands
| | - Peter Laverman
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Geert Grooteplein 10, Nijmegen, 6525 GA, Netherlands
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Danon JJ, Tregeagle DFL, Kassiou M. Adventures in Translocation: Studies of the Translocator Protein (TSPO) 18 kDa. Aust J Chem 2021. [DOI: 10.1071/ch21176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The 18 kDa translocator protein (TSPO) is an evolutionarily conserved transmembrane protein found embedded in the outer mitochondrial membrane. A secondary target for the benzodiazepine diazepam, TSPO has been a protein of interest for researchers for decades, particularly owing to its well-established links to inflammatory conditions in the central and peripheral nervous systems. It has become a key biomarker for assessing microglial activation using positron emission tomography (PET) imaging in patients with diseases ranging from atherosclerosis to Alzheimer’s disease. This Account describes research published by our group over the past 15 years surrounding the development of TSPO ligands and their use in probing the function of this high-value target.
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An update into the medicinal chemistry of translocator protein (TSPO) ligands. Eur J Med Chem 2020; 209:112924. [PMID: 33081988 DOI: 10.1016/j.ejmech.2020.112924] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 10/06/2020] [Accepted: 10/06/2020] [Indexed: 01/16/2023]
Abstract
The Translocator Protein 18 kDa (TSPO) has been discovered in 1977 as an alternative binding site for the benzodiazepine diazepam. It is an evolutionary well-conserved and tryptophan-rich 169-amino acids protein with five alpha helical transmembrane domains stretching the outer mitochondrial membrane, with the carboxyl-terminus in the cytosol and a short amino-terminus in the intermembrane space of mitochondrion. At this level, together with the voltage-dependent anion channel (VDAC) and the adenine nucleotide translocase (ANT), it forms the mitochondrial permeability transition pore (MPTP). TSPO expression is ubiquitary, with higher levels in steroid producing tissues; in the central nervous system, it is mainly expressed in glial cells and in neurons. TSPO is implicated in a variety of fundamental cellular processes including steroidogenesis, heme biosynthesis, mitochondrial respiration, mitochondrial membrane potential, cell proliferation and differentiation, cell life/death balance, oxidative stress. Altered TSPO expression has been found in some pathological conditions. In particular, high TSPO expression levels have been documented in cancer, neuroinflammation, and brain injury. Conversely, low TSPO expression levels have been evidenced in anxiety disorders. Therefore, TSPO is not only an interesting drug target for therapeutic purpose (anticonvulsant, anxiolytic, etc.), but also a valid diagnostic marker of related-diseases detectable by fluorescent or radiolabeled ligands. The aim of this report is to present an update of previous reviews dealing with the medicinal chemistry of TSPO and to highlight the most outstanding advances in the development of TSPO ligands as potential therapeutic or diagnostic tools, especially referring to the last five years.
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Zammit M, Tao Y, Olsen ME, Metzger J, Vermilyea SC, Bjornson K, Slesarev M, Block WF, Fuchs K, Phillips S, Bondarenko V, Zhang SC, Emborg ME, Christian BT. [ 18F]FEPPA PET imaging for monitoring CD68-positive microglia/macrophage neuroinflammation in nonhuman primates. EJNMMI Res 2020; 10:93. [PMID: 32761399 PMCID: PMC7410886 DOI: 10.1186/s13550-020-00683-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/29/2020] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The aim of this study was to examine whether the translocator protein 18-kDa (TSPO) PET ligand [18F]FEPPA has the sensitivity for detecting changes in CD68-positive microglial/macrophage activation in hemiparkinsonian rhesus macaques treated with allogeneic grafts of induced pluripotent stem cell-derived midbrain dopaminergic neurons (iPSC-mDA). METHODS In vivo positron emission tomography (PET) imaging with [18F]FEPPA was used in conjunction with postmortem CD68 immunostaining to evaluate neuroinflammation in the brains of hemiparkinsonian rhesus macaques (n = 6) that received allogeneic iPSC-mDA grafts in the putamen ipsilateral to MPTP administration. RESULTS Based on assessment of radiotracer uptake and confirmed by visual inspection of the imaging data, nonhuman primates with allogeneic grafts showed increased [18F]FEPPA binding at the graft sites relative to the contralateral putamen. From PET asymmetry analysis of the images, the mean asymmetry index of the monkeys was AI = - 0.085 ± 0.018. Evaluation and scoring of CD68 immunoreactivity by an investigator blind to the treatment identified significantly more neuroinflammation in the grafted areas of the putamen compared to the contralateral putamen (p = 0.0004). [18F]FEPPA PET AI showed a positive correlation with CD68 immunoreactivity AI ratings in the monkeys (Spearman's ρ = 0.94; p = 0.005). CONCLUSION These findings reveal that [18F]FEPPA PET is an effective marker for detecting increased CD68-positive microglial/macrophage activation and demonstrates sufficient sensitivity to detect changes in neuroinflammation in vivo following allogeneic cell engraftment.
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Affiliation(s)
- Matthew Zammit
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Yunlong Tao
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Miles E Olsen
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Jeanette Metzger
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
- Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Scott C Vermilyea
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
- Department of Neuroscience, University of Minnesota-Twin Cities, Minneapolis, MN, USA
| | - Kathryn Bjornson
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Maxim Slesarev
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Walter F Block
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Kerri Fuchs
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| | - Sean Phillips
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| | - Viktorya Bondarenko
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| | - Su-Chun Zhang
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, USA
| | - Marina E Emborg
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA.
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA.
- Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, WI, USA.
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA.
| | - Bradley T Christian
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
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12
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Pigeon H, Pérès EA, Truillet C, Jego B, Boumezbeur F, Caillé F, Zinnhardt B, Jacobs AH, Le Bihan D, Winkeler A. TSPO-PET and diffusion-weighted MRI for imaging a mouse model of infiltrative human glioma. Neuro Oncol 2020; 21:755-764. [PMID: 30721979 DOI: 10.1093/neuonc/noz029] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Glioblastoma (GBM) is the most devastating brain tumor. Despite the use of multimodal treatments, most patients relapse, often due to the highly invasive nature of gliomas. However, the detection of glioma infiltration remains challenging. The aim of this study was to assess advanced PET and MRI techniques for visualizing biological activity and infiltration of the tumor. METHODS Using multimodality imaging, we investigated [18F]DPA-714, a radiotracer targeting the 18 kDa translocator protein (TSPO), [18F]FET PET, non-Gaussian diffusion MRI (apparent diffusion coefficient, kurtosis), and the S-index, a composite diffusion metric, to detect tumor infiltration in a human invasive glioma model. In vivo imaging findings were confirmed by autoradiography and immunofluorescence. RESULTS Increased tumor-to-contralateral [18F]DPA-714 uptake ratios (1.49 ± 0.11) were found starting 7 weeks after glioma cell implantation. TSPO-PET allowed visualization of glioma infiltration into the contralateral hemisphere 2 weeks earlier compared with the clinically relevant biomarker for biological glioma activity [18F]FET. Diffusion-weighted imaging (DWI), in particular kurtosis, was more sensitive than standard T2-weighted MRI to detect differences between the glioma-bearing and the contralateral hemisphere at 5 weeks. Immunofluorescence data reflect in vivo findings. Interestingly, labeling for tumoral and stromal TSPO indicates a predominant expression of TSPO by tumor cells. CONCLUSION These results suggest that advanced PET and MRI methods, such as [18F]DPA-714 and DWI, may be superior to standard imaging methods to visualize glioma growth and infiltration at an early stage.
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Affiliation(s)
- Hayet Pigeon
- UMR 1023, IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay, Orsay, France
| | - Elodie A Pérès
- UMR 1023, IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay, Orsay, France.,NeuroSpin, CEA/Université Paris-Saclay, Gif sur Yvette, France.,Normandie Université, UNICAEN, CEA, CNRS, ISTCT/CERVOxy Group, Caen, France
| | - Charles Truillet
- UMR 1023, IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay, Orsay, France
| | - Benoit Jego
- UMR 1023, IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay, Orsay, France
| | | | - Fabien Caillé
- UMR 1023, IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay, Orsay, France
| | - Bastian Zinnhardt
- EIMI and Department of Nuclear Medicine, University Hospital Münster, Westfälische Wilhelms University Münster, Münster, Germany
| | - Andreas H Jacobs
- EIMI and Department of Nuclear Medicine, University Hospital Münster, Westfälische Wilhelms University Münster, Münster, Germany.,Department of Geriatrics, Johanniter Hospital, Evangelische Kliniken, Bonn, Germany
| | - Denis Le Bihan
- NeuroSpin, CEA/Université Paris-Saclay, Gif sur Yvette, France
| | - Alexandra Winkeler
- UMR 1023, IMIV, Service Hospitalier Frédéric Joliot, CEA, Inserm, Université Paris Sud, CNRS, Université Paris-Saclay, Orsay, France
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13
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Schröder S, Lai TH, Toussaint M, Kranz M, Chovsepian A, Shang Q, Dukić-Stefanović S, Deuther-Conrad W, Teodoro R, Wenzel B, Moldovan RP, Pan-Montojo F, Brust P. PET Imaging of the Adenosine A 2A Receptor in the Rotenone-Based Mouse Model of Parkinson's Disease with [ 18F]FESCH Synthesized by a Simplified Two-Step One-Pot Radiolabeling Strategy. Molecules 2020; 25:molecules25071633. [PMID: 32252340 PMCID: PMC7180622 DOI: 10.3390/molecules25071633] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 03/27/2020] [Accepted: 03/27/2020] [Indexed: 12/16/2022] Open
Abstract
The adenosine A2A receptor (A2AR) is regarded as a particularly appropriate target for non-dopaminergic treatment of Parkinson’s disease (PD). An increased A2AR availability has been found in the human striatum at early stages of PD and in patients with PD and dyskinesias. The aim of this small animal positron emission tomography/magnetic resonance (PET/MR) imaging study was to investigate whether rotenone-treated mice reflect the aspect of striatal A2AR upregulation in PD. For that purpose, we selected the known A2AR-specific radiotracer [18F]FESCH and developed a simplified two-step one-pot radiosynthesis. PET images showed a high uptake of [18F]FESCH in the mouse striatum. Concomitantly, metabolism studies with [18F]FESCH revealed the presence of a brain-penetrant radiometabolite. In rotenone-treated mice, a slightly higher striatal A2AR binding of [18F]FESCH was found. Nonetheless, the correlation between the increased A2AR levels within the proposed PD animal model remains to be further investigated.
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Affiliation(s)
- Susann Schröder
- ROTOP Pharmaka Ltd., Department of Research and Development, Dresden 01328, Germany
- Correspondence: ; Tel.: +49-341-234-179-4631
| | - Thu Hang Lai
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
| | - Magali Toussaint
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
| | - Mathias Kranz
- PET Imaging Center, University Hospital of North Norway (UNN), Tromsø 9009, Norway;
- Nuclear Medicine and Radiation Biology Research Group, The Arctic University of Norway, Tromsø 9009, Norway
| | - Alexandra Chovsepian
- University Hospital Munich, Department of Psychiatry, Ludwig-Maximilians-Universität (LMU) Munich, Munich 80336, Germany; (A.C.); (F.P.-M.)
| | - Qi Shang
- University Hospital Munich, Department of Neurology, Ludwig-Maximilians-Universität (LMU) Munich, Munich 81377, Germany;
- University Hospital Carl Gustav Carus, Clinic of Neurology, Technische Universität Dresden (TUD), Dresden 01307, Germany
| | - Sladjana Dukić-Stefanović
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
| | - Winnie Deuther-Conrad
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
| | - Rodrigo Teodoro
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
| | - Barbara Wenzel
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
| | - Rareş-Petru Moldovan
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
| | - Francisco Pan-Montojo
- University Hospital Munich, Department of Psychiatry, Ludwig-Maximilians-Universität (LMU) Munich, Munich 80336, Germany; (A.C.); (F.P.-M.)
- University Hospital Munich, Department of Neurology, Ludwig-Maximilians-Universität (LMU) Munich, Munich 81377, Germany;
| | - Peter Brust
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Research Site Leipzig, Leipzig 04318, Germany; (T.H.L.); (M.T.); (S.D.-S.); (W.D.-C.); (R.T.); (B.W.); (R.-P.M.); (P.B.)
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Longitudinal mouse-PET imaging: a reliable method for estimating binding parameters without a reference region or blood sampling. Eur J Nucl Med Mol Imaging 2020; 47:2589-2601. [PMID: 32211931 PMCID: PMC7515949 DOI: 10.1007/s00259-020-04755-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 03/03/2020] [Indexed: 01/06/2023]
Abstract
Abstract Longitudinal mouse PET imaging is becoming increasingly popular due to the large number of transgenic and disease models available but faces challenges. These challenges are related to the small size of the mouse brain and the limited spatial resolution of microPET scanners, along with the small blood volume making arterial blood sampling challenging and impossible for longitudinal studies. The ability to extract an input function directly from the image would be useful for quantification in longitudinal small animal studies where there is no true reference region available such as TSPO imaging. Methods Using dynamic, whole-body 18F-DPA-714 PET scans (60 min) in a mouse model of hippocampal sclerosis, we applied a factor analysis (FA) approach to extract an image-derived input function (IDIF). This mouse-specific IDIF was then used for 4D-resolution recovery and denoising (4D-RRD) that outputs a dynamic image with better spatial resolution and noise properties, and a map of the total volume of distribution (VT) was obtained using a basis function approach in a total of 9 mice with 4 longitudinal PET scans each. We also calculated percent injected dose (%ID) with and without 4D-RRD. The VT and %ID parameters were compared to quantified ex vivo autoradiography using regional correlations of the specific binding from autoradiography against VT and %ID parameters. Results The peaks of the IDIFs were strongly correlated with the injected dose (Pearson R = 0.79). The regional correlations between the %ID estimates and autoradiography were R = 0.53 without 4D-RRD and 0.72 with 4D-RRD over all mice and scans. The regional correlations between the VT estimates and autoradiography were R = 0.66 without 4D-RRD and 0.79 with application of 4D-RRD over all mice and scans. Conclusion We present a FA approach for IDIF extraction which is robust, reproducible and can be used in quantification methods for resolution recovery, denoising and parameter estimation. We demonstrated that the proposed quantification method yields parameter estimates closer to ex vivo measurements than semi-quantitative methods such as %ID and is immune to tracer binding in tissue unlike reference tissue methods. This approach allows for accurate quantification in longitudinal PET studies in mice while avoiding repeated blood sampling. Electronic supplementary material The online version of this article (10.1007/s00259-020-04755-5) contains supplementary material, which is available to authorized users.
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15
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Wang L, Yao S, Tang R, Zhu H, Zhang L, Gong J, Chen Q, Collier TL, Xu H, Liang SH. A concisely automated synthesis of TSPO radiotracer [ 18 F]FDPA based on spirocyclic iodonium ylide method and validation for human use. J Labelled Comp Radiopharm 2020; 63:119-128. [PMID: 31895476 DOI: 10.1002/jlcr.3824] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 08/24/2019] [Accepted: 08/26/2019] [Indexed: 12/14/2022]
Abstract
Fluorine-18 labeled N,N-diethyl-2-(2-(4-(2-fluoroethoxy)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide ([18 F]FDPA) is a potent and selective radiotracer for positron-emission tomography (PET) imaging of the translocator protein 18 kDa (TSPO). Our previous in vitro and in vivo evaluations have proven that this tracer is promising for further human translation. Our study addresses the need to streamline the automatic synthesis of this radiotracer to make it more accessible for widespread clinical evaluation and application. Here, we successfully demonstrate a one-step radiolabeling of [18 F]FDPA based on a novel spirocyclic iodonium ylide (SCIDY) precursor using tetra-n-butyl ammonium methanesulfonate (TBAOMs), which has demonstrated the highest radiochemical yields and molar activity from readily available [18 F]fluoride ion. The nucleophilic radiofluorination was completed on a GE TRACERlab FX2 N synthesis module, and the formulated [18 F]FDPA was obtained in nondecay corrected (n.d.c) radiochemical yields of 15.6 ± 4.2%, with molar activities of 529.2 ± 22.5 GBq/μmol (14.3 ± 0.6 Ci/μmol) at the end of synthesis (60 minutes, n = 3) and validated for human use. This methodology facilitates efficient synthesis of [18 F]FDPA in a commercially available synthesis module, which would be broadly applicable for routine production and widespread clinical PET imaging studies.
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Affiliation(s)
- 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, China
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Shaobo Yao
- Department of PET/CT Diagnostic, Tianjin Medical University General Hospital, Tianjin, China
| | - Ruikun Tang
- Department of Radiopharmaceuticals Quality Control, Guangzhou Atom Hightech Radiopharmaceutical Co. Ltd, Guangzhou, China
| | - Honghao Zhu
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Lingling Zhang
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Jian Gong
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Qiusong Chen
- Department of PET/CT Diagnostic, Tianjin Medical University General Hospital, Tianjin, China
| | - Thomas Lee Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, Massachusetts
- Advion Inc., New York, USA
| | - Hao Xu
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, Massachusetts
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16
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Radiotracers for imaging of Parkinson's disease. Eur J Med Chem 2019; 166:75-89. [DOI: 10.1016/j.ejmech.2019.01.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 01/12/2019] [Accepted: 01/13/2019] [Indexed: 12/22/2022]
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17
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Volume-of-interest-based supervised cluster analysis for pseudo-reference region selection in [ 18F]DPA-714 PET imaging of the rat brain. EJNMMI Res 2018; 8:112. [PMID: 30588554 PMCID: PMC6306370 DOI: 10.1186/s13550-018-0467-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/11/2018] [Indexed: 12/13/2022] Open
Abstract
Method Aim of this study was to automatically select a suitable pseudo-reference brain region for the accurate, non-invasive quantification of neuroinflammation in a rat brain using dynamic [18F]DPA-714 PET imaging. Procedures A supervised clustering analysis approach considering three kinetic classes (SVCA3) was used to select an appropriate pseudo-reference brain region. This pseudo-reference region was determined by selecting only brain regions with low specific tracer uptake (SVCA3low) or by taking into account all brain regions and weighting each brain region with the corresponding fraction of low specific binding (SVCA3wlow). Both SVCA3 approaches were evaluated in an animal model of neuro-inflammation induced by lipopolysaccharide injection in the right striatum of female Wistar rats. For this study setup, a population of 25 female Wistar rats received a dynamic PET scan after injection of ~ 60 MBq [18F]DPA-714. Animals were scanned at baseline (n = 3) and at different time points after inducing neuroinflammation: 1 day (n = 3), 3 days (n = 12), 7 days (n = 4), and 30 days (n = 3). Binding potential (BP) values using a simplified reference tissue model (SRTM) and the contralateral striatum as pseudo-reference region were considered as a reference method (BPL STR) and compared with SRTM BP values using a pseudo-reference region obtained by either the SVCA3low or SVCA3wlow approach for both a 90- and 120-min acquisition time interval. Results For the right striatum, SRTM BP values using a SVCA3low- or SVCA3wlow-based pseudo-reference region demonstrated a strong and highly significant correlation with SRTM BPL STR values (Spearman r ≥ 0.89, p < 0.001). For the SVCA3low approach, Friedman tests revealed no significant difference with SRTM BPL STR values for a 120-min acquisition time while small but signification differences were found for a 90-min acquisition time (p < 0.05). For the SVCA3wlow approach, highly signification differences (p < 0.001) were found with SRTM BPL STR values for both a 90- and 120-min acquisition time interval. Conclusions A SVCA3 approach using three kinetic classes allowed the automatic selection of pseudo-reference brain regions with low specific tracer binding for accurate and non-invasive quantification of rat brain PET imaging using [18F]DPA-714. A shorter acquisition time interval of 90 min can be considered with only limited impact on the SVCA3-based selection of the pseudo-reference brain regions.
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18
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Miyajima N, Ito M, Rokugawa T, Iimori H, Momosaki S, Omachi S, Shimosegawa E, Hatazawa J, Abe K. Detection of neuroinflammation before selective neuronal loss appearance after mild focal ischemia using [ 18F]DPA-714 imaging. EJNMMI Res 2018; 8:43. [PMID: 29884977 PMCID: PMC5993708 DOI: 10.1186/s13550-018-0400-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/23/2018] [Indexed: 12/13/2022] Open
Abstract
Background Translocator protein (TSPO) imaging can be used to detect neuroinflammation (including microglial activation) after acute cerebral infarction. However, longitudinal changes of TSPO binding after mild ischemia that induces selective neuronal loss (SNL) without acute infarction are not well understood. Here, we performed TSPO imaging with [18F]DPA-714 to determine the time course of neuroinflammation and SNL after mild focal ischemia. Results Mild focal ischemia was induced by middle cerebral artery occlusion (MCAO) for 20 min. In MCAO rats without acute infarction investigated by 2, 3, 5-triphenyltetrazolium chloride (TTC) staining, in vitro ARG revealed a significant increase of [18F]DPA-714 binding in the ipsilateral striatum compared with that in the contralateral side at 1, 2, 3, and 7 days after MCAO. Increased [18F]DPA-714 binding was observed in the cerebral cortex penumbra, reaching maximal values at 7 days after MCAO. Activation of striatal microglia and astrocytes was observed with immunohistochemistry of ionized calcium binding adaptor molecule 1 (Iba1) and glial fibrillary acidic protein (GFAP) at 2, 3, and 7 days after MCAO. SNL was investigated with Nissl staining and neuronal nuclei (NeuN) immunostaining and observed in the ischemic core region of the striatum on days 3 and 7 after MCAO. We confirmed that total distribution volume of [18F]DPA-714 in the ipsilateral striatum was significantly increased at 2 and 7 days after MCAO using positron emission tomography (PET). Conclusions [18F]DPA-714 binding measured with in vitro ARG was increased before SNL appeared, and this change was detected by in vivo PET. These findings suggest that TSPO PET imaging might be useful for detection of neuroinflammation leading to SNL after focal ischemia.
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Affiliation(s)
- Natsumi Miyajima
- Translational Research Unit, Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, 5610825, Japan.
| | - Miwa Ito
- Translational Research Unit, Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, 5610825, Japan
| | - Takemi Rokugawa
- Translational Research Unit, Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, 5610825, Japan
| | - Hitoshi Iimori
- Department of Applied Chemistry and Analysis, Research Laboratory for Development, Shionogi & Co., Ltd., Osaka, Japan
| | - Sotaro Momosaki
- Translational Research Unit, Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, 5610825, Japan
| | - Shigeki Omachi
- Department of medical affairs, Shionogi & Co., Ltd., Osaka, Japan
| | - Eku Shimosegawa
- Department of Molecular Imaging in Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.,Department of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, Osaka, Japan.,PET Molecular Imaging Center, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Jun Hatazawa
- Department of Nuclear Medicine and Tracer Kinetics, Osaka University Graduate School of Medicine, Osaka, Japan.,PET Molecular Imaging Center, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Kohji Abe
- Translational Research Unit, Biomarker R&D Department, Shionogi & Co., Ltd., Osaka, 5610825, Japan
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Nguyen DL, Wimberley C, Truillet C, Jego B, Caillé F, Pottier G, Boisgard R, Buvat I, Bouilleret V. Longitudinal positron emission tomography imaging of glial cell activation in a mouse model of mesial temporal lobe epilepsy: Toward identification of optimal treatment windows. Epilepsia 2018; 59:1234-1244. [PMID: 29672844 DOI: 10.1111/epi.14083] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/23/2018] [Indexed: 12/20/2022]
Abstract
OBJECTIVE Mesiotemporal lobe epilepsy is the most common type of drug-resistant partial epilepsy, with a specific history that often begins with status epilepticus due to various neurological insults followed by a silent period. During this period, before the first seizure occurs, a specific lesion develops, described as unilateral hippocampal sclerosis (HS). It is still challenging to determine which drugs, administered at which time point, will be most effective during the formation of this epileptic process. Neuroinflammation plays an important role in pathophysiological mechanisms in epilepsy, and therefore brain inflammation biomarkers such as translocator protein 18 kDa (TSPO) can be potent epilepsy biomarkers. TSPO is associated with reactive astrocytes and microglia. A unilateral intrahippocampal kainate injection mouse model can reproduce the defining features of human temporal lobe epilepsy with unilateral HS and the pattern of chronic pharmacoresistant temporal seizures. We hypothesized that longitudinal imaging using TSPO positron emission tomography (PET) with 18 F-DPA-714 could identify optimal treatment windows in a mouse model during the formation of HS. METHODS The model was induced into the right dorsal hippocampus of male C57/Bl6 mice. Micro-PET/computed tomographic scanning was performed before model induction and along the development of the HS at 7 days, 14 days, 1 month, and 6 months. In vitro autoradiography and immunohistofluorescence were performed on additional mice at each time point. RESULTS TSPO PET uptake reached peak at 7 days and mostly related to microglial activation, whereas after 14 days, reactive astrocytes were shown to be the main cells expressing TSPO, reflected by a continuing increased PET uptake. SIGNIFICANCE TSPO-targeted PET is a highly potent longitudinal biomarker of epilepsy and could be of interest to determine the therapeutic windows in epilepsy and to monitor response to treatment.
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Affiliation(s)
- Duc-Loc Nguyen
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Catriona Wimberley
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Charles Truillet
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Benoit Jego
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Fabien Caillé
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Géraldine Pottier
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Raphaël Boisgard
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Irène Buvat
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France
| | - Viviane Bouilleret
- In Vivo Molecular Imaging Laboratory (IMIV), French National Institute of Health and Medical Research (INSERM), French Alternative Energies and Atomic Energy Commission (CEA), French National Center for Scientific Research (CNRS), Paris Saclay University, Frédéric Joliot Hospital service, Orsay, France.,Neurophysiology and Epilepsy Unit, Bicêtre Hospital, Public Hospitals of Paris (AP-HP), France
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20
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Kuszpit K, Hollidge BS, Zeng X, Stafford RG, Daye S, Zhang X, Basuli F, Golden JW, Swenson RE, Smith DR, Bocan TM. [ 18F]DPA-714 PET Imaging Reveals Global Neuroinflammation in Zika Virus-Infected Mice. Mol Imaging Biol 2018; 20:275-283. [PMID: 28900831 PMCID: PMC5862915 DOI: 10.1007/s11307-017-1118-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
PURPOSE The association of Zika virus (ZIKV) infection and development of neurological sequelae require a better understanding of the pathogenic mechanisms causing severe disease. The purpose of this study was to evaluate the ability and sensitivity of positron emission tomography (PET) imaging using [18F]DPA-714, a translocator protein (TSPO) 18 kDa radioligand, to detect and quantify neuroinflammation in ZIKV-infected mice. PROCEDURES We assessed ZIKV-induced pathogenesis in wild-type C57BL/6 mice administered an antibody to inhibit type I interferon (IFN) signaling. [18F]DPA-714 PET imaging was performed on days 3, 6, and 10 post-infection (PI), and tissues were subsequently processed for histological evaluation, quantification of microgliosis, and detection of viral RNA by in situ hybridization (ISH). RESULTS In susceptible ZIKV-infected mice, viral titers in the brain increased from days 3 to 10 PI. Over this span, these mice showed a two- to sixfold increase in global brain neuroinflammation using [18F]DPA-714 PET imaging despite limited, regional detection of viral RNA. No measurable increase in ionized calcium binding adaptor molecule 1 (Iba-1) expression was noted at day 3 PI; however, there was a modest increase at day 6 PI and an approximately significant fourfold increase in Iba-1 expression at day 10 PI in the susceptible ZIKV-infected group relative to controls. CONCLUSIONS The results of the current study demonstrate that global neuroinflammation plays a significant role in the progression of ZIKV infection and that [18F]DPA-714 PET imaging is a sensitive tool relative to histology for the detection of neuroinflammation. [18F]DPA-714 PET imaging may be useful in dynamically characterizing the pathology associated with neurotropic viruses and the evaluation of therapeutics being developed for treatment of infectious diseases.
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Affiliation(s)
- Kyle Kuszpit
- Molecular and Translational Sciences Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA
| | - Bradley S Hollidge
- Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA
| | - Xiankun Zeng
- Pathology Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA
| | - Robert G Stafford
- Molecular and Translational Sciences Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA
| | - Sharon Daye
- Pathology Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA
| | - Xiang Zhang
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 9800 Medical Center Drive, Bldg. B., #2034, Bethesda, MD, 20892, USA
| | - Falguni Basuli
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 9800 Medical Center Drive, Bldg. B., #2034, Bethesda, MD, 20892, USA
| | - Joseph W Golden
- Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA
| | - Rolf E Swenson
- Imaging Probe Development Center, National Heart, Lung, and Blood Institute, National Institutes of Health, 9800 Medical Center Drive, Bldg. B., #2034, Bethesda, MD, 20892, USA
| | - Darci R Smith
- Virology Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA.
| | - Thomas M Bocan
- Molecular and Translational Sciences Division, U.S. Army Medical Research Institute of Infectious Diseases, 1425, Porter St., Ft. Detrick, Frederick, MD, 21702, USA.
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21
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Colás L, Domercq M, Ramos-Cabrer P, Palma A, Gómez-Vallejo V, Padro D, Plaza-García S, Pulagam KR, Higuchi M, Matute C, Llop J, Martín A. In vivo imaging of Α7 nicotinic receptors as a novel method to monitor neuroinflammation after cerebral ischemia. Glia 2018. [PMID: 29528142 DOI: 10.1002/glia.23326] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In vivo positron emission tomography (PET) imaging of nicotinic acetylcholine receptors (nAChRs) is a promising tool for the imaging evaluation of neurologic and neurodegenerative diseases. However, the role of α7 nAChRs after brain diseases such as cerebral ischemia and its involvement in inflammatory reaction is still largely unknown. In vivo and ex vivo evaluation of α7 nAChRs expression after transient middle cerebral artery occlusion (MCAO) was carried out using PET imaging with [11 C]NS14492 and immunohistochemistry (IHC). Pharmacological activation of α7 receptors was evaluated with magnetic resonance imaging (MRI), [18 F]DPA-714 PET, IHC, real time polymerase chain reaction (qPCR) and neurofunctional studies. In the ischemic territory, [11 C]NS14492 signal and IHC showed an expression increase of α7 receptors in microglia and astrocytes after cerebral ischemia. The role played by α7 receptors on neuroinflammation was supported by the decrease of [18 F]DPA-714 binding in ischemic rats treated with the α7 agonist PHA 568487 at day 7 after MCAO. Moreover, compared with non-treated MCAO rats, PHA-treated ischemic rats showed a significant reduction of the cerebral infarct volumes and an improvement of the neurologic outcome. PHA treatment significantly reduced the expression of leukocyte infiltration molecules in MCAO rats and in endothelial cells after in vitro ischemia. Despite that, the activation of α7 nAChR had no influence to the blood brain barrier (BBB) permeability measured by MRI. Taken together, these results suggest that the nicotinic α7 nAChRs play a key role in the inflammatory reaction and the leukocyte recruitment following cerebral ischemia in rats.
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Affiliation(s)
- Lorena Colás
- Experimental Molecular Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Maria Domercq
- Department of Neurosciences, University of the Basque Country, Barrio Sarriena s/n, 48940 Leioa, Spain, Achucarro Basque Center for Neuroscience-UPV/EHU, 48170 Zamudio, Spain and Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, 48940, Spain
| | - Pedro Ramos-Cabrer
- Magnetic Resonance Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Ana Palma
- Department of Neurosciences, University of the Basque Country, Barrio Sarriena s/n, 48940 Leioa, Spain, Achucarro Basque Center for Neuroscience-UPV/EHU, 48170 Zamudio, Spain and Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, 48940, Spain
| | - Vanessa Gómez-Vallejo
- Radiochemistry and Nuclear Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Daniel Padro
- Magnetic Resonance Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Sandra Plaza-García
- Magnetic Resonance Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Krishna R Pulagam
- Radiochemistry and Nuclear Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Makoto Higuchi
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan
| | - Carlos Matute
- Department of Neurosciences, University of the Basque Country, Barrio Sarriena s/n, 48940 Leioa, Spain, Achucarro Basque Center for Neuroscience-UPV/EHU, 48170 Zamudio, Spain and Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Leioa, 48940, Spain
| | - Jordi Llop
- Radiochemistry and Nuclear Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
| | - Abraham Martín
- Experimental Molecular Imaging, Molecular Imaging Unit, CIC biomaGUNE, P° Miramon 182, San Sebastian, Spain
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22
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Keller T, Krzyczmonik A, Forsback S, Picón FRL, Kirjavainen AK, Takkinen J, Rajander J, Cacheux F, Damont A, Dollé F, Rinne JO, Haaparanta-Solin M, Solin O. Radiosynthesis and Preclinical Evaluation of [ 18F]F-DPA, A Novel Pyrazolo[1,5a]pyrimidine Acetamide TSPO Radioligand, in Healthy Sprague Dawley Rats. Mol Imaging Biol 2017; 19:736-745. [PMID: 28083825 PMCID: PMC5574958 DOI: 10.1007/s11307-016-1040-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
PURPOSE Many neurological conditions result in the overexpression of the translocator protein 18 kDa (TSPO), today recognized as a biomarker for microglial activation and neuroinflammation imaging. The pyrazolo[1,5-a]pyrimidine acetamides are a particularly attractive class of TSPO-specific ligands, prompting the development of several positron emission tomography (PET) radiotracers. This includes F-DPA, a recently reported fluorinated ligand (K i = 1.7 nM), wherein the fluorine atom is directly linked to the phenyl moiety without the presence of an alkyl or alkoxy spacer chain. Reported here is the preparation of [18F]F-DPA using [18F]Selectfluor bis(triflate) and the preliminary evaluation of [18F]F-DPA in healthy rats. Its metabolic profile and biodistribution in rats are compared with that of [18F]DPA-714, a closely related structure. PROCEDURES [18F]F-DPA was synthesized by electrophilic fluorination using [18F]Selectfluor bis(triflate), [18F]DPA-714 was synthesized by conventional nucleophilic fluorination. The biodistribution of both radiotracers was compared in Sprague Dawley rats. Radiometabolites of both radiotracers in plasma and brain homogenates were analyzed by radioTLC. RESULTS The radiochemical yield of [18F]F-DPA was 15 ± 3 % and the specific activity was 7.8 ± 0.4 GBq/μmol. The radiochemical purity exceeded 99 %. The in vivo time activity curves of [18F]F-DPA demonstrate rapid entry into the brain and a concentration equilibrium at 20-30 min after injection. The metabolic profiles at 90 min after radiotracer injection in the plasma show that unchanged [18F]F-DPA and [18F]DPA-714 account for 28.3 ± 6.4 and 11.1 ± 2.6 % of the remaining radioactivity, respectively. In the brain, unchanged [18F]F-DPA accounts for 93.5 ± 2.8 % of the radioactivity; whereas for [18F]DPA-714, this value is 53.6 ± 1.6 %. CONCLUSIONS [18F]Selectfluor bis(triflate) was successfully used to label F-DPA with fluorine-18. The labeling position on the aromatic moiety imparts a higher stability compared to [18F]DPA-714 with regard to in vivo metabolism. [18F]F-DPA is a promising new radiotracer and warrants further investigation in animal models of disease.
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Affiliation(s)
- Thomas Keller
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
| | - Anna Krzyczmonik
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
| | - Sarita Forsback
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- Department of Chemistry, University of Turku, Turku, Finland
| | - Francisco R López Picón
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Anna K Kirjavainen
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland
| | - Jatta Takkinen
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Johan Rajander
- Accelerator Laboratory, Turku PET Centre, Åbo Akademi University, Turku, Finland
| | - Fanny Cacheux
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | | | - Frédéric Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Juha O Rinne
- Turku PET Centre, Division of Clinical Neurosciences, Turku University Hospital, Turku, Finland
| | - Merja Haaparanta-Solin
- PET Preclinical Imaging Laboratory, Turku PET Centre, University of Turku, Turku, Finland
- MediCity Research Laboratory, University of Turku, Turku, Finland
| | - Olof Solin
- Radiopharmaceutical Chemistry Laboratory, Turku PET Centre, University of Turku, Turku, Finland.
- Department of Chemistry, University of Turku, Turku, Finland.
- Accelerator Laboratory, Turku PET Centre, Åbo Akademi University, Turku, Finland.
- Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, 20520, Turku, Finland.
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23
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Pottier G, Gómez-Vallejo V, Padro D, Boisgard R, Dollé F, Llop J, Winkeler A, Martín A. PET imaging of cannabinoid type 2 receptors with [ 11C]A-836339 did not evidence changes following neuroinflammation in rats. J Cereb Blood Flow Metab 2017; 37:1163-1178. [PMID: 28079433 PMCID: PMC5363492 DOI: 10.1177/0271678x16685105] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Cannabinoid type 2 receptors (CB2R) have emerged as promising targets for the diagnosis and therapy of brain pathologies. However, no suitable radiotracers for accurate CB2R mapping have been found to date, limiting the investigation of the CB2 receptor expression using positron emission tomography (PET) imaging. In this work, we report the evaluation of the in vivo expression of CB2R with [11C]A-836339 PET after cerebral ischemia and in two rat models of neuroinflammation, first by intrastriatal LPS and then by AMPA injection. PET images and in vitro autoradiography showed a lack of specific [11C]A-836339 uptake in these animal models demonstrating the limitation of this radiotracer to image CB2 receptor under neuroinflammatory conditions. Further, using immunohistochemistry, the CB2 receptor displayed a modest expression increase after cerebral ischemia, LPS and AMPA models. Finally, [18F]DPA-714-PET and immunohistochemistry demonstrated decreased neuroinflammation by a selective CB2R agonist, JWH133. Taken together, these findings suggest that [11C]A-836339 is not a suitable radiotracer to monitor in vivo CB2R expression by using PET imaging. Future studies will have to investigate alternative radiotracers that could provide an accurate binding to CB2 receptors following brain inflammation.
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Affiliation(s)
- Geraldine Pottier
- 1 Imagerie Moléculaire In Vivo, Inserm, CEA, Univ. Paris Sud, CNRS, Université Paris Saclay, CEA - Service Hospitalier Frédéric Joliot, Orsay, France
| | | | - Daniel Padro
- 3 Magnetic Resonance Imaging, CIC biomaGUNE, San Sebastian, Spain
| | - Raphaël Boisgard
- 1 Imagerie Moléculaire In Vivo, Inserm, CEA, Univ. Paris Sud, CNRS, Université Paris Saclay, CEA - Service Hospitalier Frédéric Joliot, Orsay, France
| | - Frédéric Dollé
- 1 Imagerie Moléculaire In Vivo, Inserm, CEA, Univ. Paris Sud, CNRS, Université Paris Saclay, CEA - Service Hospitalier Frédéric Joliot, Orsay, France
| | - Jordi Llop
- 2 Radiochemistry and Nuclear Imaging, CIC biomaGUNE, San Sebastian, Spain
| | - Alexandra Winkeler
- 1 Imagerie Moléculaire In Vivo, Inserm, CEA, Univ. Paris Sud, CNRS, Université Paris Saclay, CEA - Service Hospitalier Frédéric Joliot, Orsay, France
| | - Abraham Martín
- 4 Molecular Imaging Unit, CIC biomaGUNE, San Sebastian, Spain
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Evaluation of TSPO PET imaging, a marker of glial activation, to study the neuroimmune footprints of morphine exposure and withdrawal. Drug Alcohol Depend 2017; 170:43-50. [PMID: 27875800 DOI: 10.1016/j.drugalcdep.2016.10.037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/12/2016] [Accepted: 10/29/2016] [Indexed: 12/13/2022]
Abstract
INTRODUCTION A growing area of research suggests that neuroimmunity may impact the pharmacology of opioids. Microglia is a key component of the brain immunity. Preclinical and clinical studies have demonstrated that microglial modulators may improve morphine-induced analgesia and prevent the development of tolerance and dependence. Positron emission tomography (PET) using translocator protein 18kDa (TSPO) radioligand is a clinically validated strategy for the non-invasive detection of microglial activation. We hypothesized that TSPO PET imaging may be used to study the neuroimmune component of opioid tolerance and withdrawal. METHODS Healthy rats (n=6 in each group) received either saline or escalating doses of morphine (10-40mg/kg) on five days to achieve tolerance and a withdrawal syndrome after morphine discontinuation. MicroPET imaging with [18F]DPA-714 was performed 60h after morphine withdrawal. Kinetic modeling was performed to estimate [18F]DPA-714 volume of distribution (VT) in several brain regions using dynamic PET images and corresponding metabolite-corrected input functions. Immunohistochemistry (IHC) experiments on striatal brain slices were performed to assess the expression of glial markers (Iba1, GFAP and CD68) during 14days after morphine discontinuation. RESULTS The baseline binding of [18F]DPA-714 to the brain (VT=0.086±0.009mLcm-3) was not increased by morphine exposure and withdrawal (VT=0.079±0.010mLcm-3) indicating the absence of TSPO overexpression, even at the regional level. Accordingly, expression of glial markers did not increase after morphine discontinuation. CONCLUSIONS Morphine tolerance and withdrawal did not detectably activate microglia and had no impact on [18F]DPA-714 brain kinetics in vivo.
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Neumann KT, Lindhardt AT, Bang-Andersen B, Skrydstrup T. Synthesis and selective2H-,13C-, and15N-labeling of the Tau protein binder THK-523. J Labelled Comp Radiopharm 2016; 60:30-35. [DOI: 10.1002/jlcr.3470] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 09/30/2016] [Accepted: 09/30/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Karoline T. Neumann
- Carbon Dioxide Activation Center (CADIAC); Department of Chemistry and the Interdisciplinary Nanoscience Center (iNANO); Aarhus University; Aarhus Denmark
| | - Anders T. Lindhardt
- Interdisciplinary Nanoscience Center (iNANO); Department of Engineering; Aarhus University; Aarhus Denmark
| | | | - Troels Skrydstrup
- Carbon Dioxide Activation Center (CADIAC); Department of Chemistry and the Interdisciplinary Nanoscience Center (iNANO); Aarhus University; Aarhus Denmark
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26
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Evaluation of PET Imaging Performance of the TSPO Radioligand [18F]DPA-714 in Mouse and Rat Models of Cancer and Inflammation. Mol Imaging Biol 2016; 18:127-34. [PMID: 26194010 PMCID: PMC4722075 DOI: 10.1007/s11307-015-0877-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Purpose Many radioligands have been explored for imaging the 18-kDa translocator protein (TSPO), a diagnostic and therapeutic target for inflammation and cancer. Here, we investigated the TSPO radioligand [18F]DPA-714 for positron emission tomography (PET) imaging of cancer and inflammation. Procedures [18F]DPA-714 PET imaging was performed in 8 mouse and rat models of breast and brain cancer and 4 mouse and rat models of muscular and bowel inflammation. Results [18F]DPA-714 showed different uptake levels in healthy organs and malignant tissues of mice and rats. Although high and displaceable [18F]DPA-714 binding is observed ex vivo, TSPO-positive PET imaging of peripheral lesions of cancer and inflammation in mice did not show significant lesion-to-background signal ratios. Slower [18F]DPA-714 metabolism and muscle clearance in mice compared to rats may explain the elevated background signal in peripheral organs in this species. Conclusion Although TSPO is an evolutionary conserved protein, inter- and intra-species differences call for further exploration of the pharmacological parameters of TSPO radioligands. Electronic supplementary material The online version of this article (doi:10.1007/s11307-015-0877-x) contains supplementary material, which is available to authorized users.
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Cacheux F, Médran-Navarrete V, Dollé F, Marguet F, Puech F, Damont A. Synthesis and in vitro characterization of novel fluorinated derivatives of the translocator protein 18 kDa ligand CfO-DPA-714. Eur J Med Chem 2016; 125:346-359. [PMID: 27688189 DOI: 10.1016/j.ejmech.2016.09.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 09/07/2016] [Accepted: 09/08/2016] [Indexed: 11/30/2022]
Abstract
The translocator protein 18 kDa (TSPO) is today a validated target for a number of therapeutic applications, but also a well-recognized diagnostic/imaging biomarker for the evaluation of inflammatory related-disease state and progression, prompting the development of specific and dedicated TSPO ligands worldwide. For this purpose, pyrazolo[1,5-a]pyrimidine acetamides constitute a unique class of high affinity and selectivity TSPO ligands; it includes DPA-714, a fluorine-containing derivative that has also been labelled with the positron-emitter fluorine-18, and is nowadays widely used as a Positron Emission Tomography imaging probe. Recently, to prevent defluorination issues encountered in vivo with this tracer, a first series of analogues was reported where the oxygen atom bridging the phenyl ring of the core structure and the fluorinated moiety was replaced with a more robust linkage. Among this new series, CfO-DPA-714 was discovered as a highly promising TSPO ligand. Herein, a novel series of fluorinated analogues of the latter molecule were synthesized and in vitro characterized, where the pharmacomodulation at the amide position of the molecule was explored. Thirteen compounds were thus prepared from a common key-ester intermediate (synthesized in 7 steps from 4-iodobenzoate - 11% overall yield) and a set of commercially available amines and obtained with moderate to good yields (23-81%) and high purities (>95%). With one exception, all derivatives displayed nanomolar to subnanomolar affinity for the TSPO and also high selectivity versus the CBR (Ki (CBR)/Ki (TSPO) > 103). Within this series, three compounds showed better Ki values (0.25, 0.26 and 0.30 nM) than that of DPA-714 (0.91 nM) and CfO-DPA-714 (0.37 nM), and favorable lipophilicity for brain penetration (3.6 < logD7.4 < 4.4). Among these three compounds, the N-methyl-N-propyl amide analogue (9) exhibited similar metabolic stability when compared to CfO-DPA-714 in mouse, rat and human microsomes. Therefore, the latter compound stands out as a promising candidate for drug development or for use as a PET probe, once fluorine-18-labelled, for in vivo neuroinflammation imaging.
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Affiliation(s)
- Fanny Cacheux
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France; Inserm/CEA/Université Paris Sud, UMR 1023, ERL 9218 CNRS, IMIV, Université Paris-Saclay, Orsay, France
| | - Vincent Médran-Navarrete
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France; Inserm/CEA/Université Paris Sud, UMR 1023, ERL 9218 CNRS, IMIV, Université Paris-Saclay, Orsay, France
| | - Frédéric Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France; Inserm/CEA/Université Paris Sud, UMR 1023, ERL 9218 CNRS, IMIV, Université Paris-Saclay, Orsay, France
| | | | | | - Annelaure Damont
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France; Inserm/CEA/Université Paris Sud, UMR 1023, ERL 9218 CNRS, IMIV, Université Paris-Saclay, Orsay, France.
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Fricke IB, Viel T, Worlitzer MM, Collmann FM, Vrachimis A, Faust A, Wachsmuth L, Faber C, Dollé F, Kuhlmann MT, Schäfers K, Hermann S, Schwamborn JC, Jacobs AH. 6-hydroxydopamine-induced Parkinson's disease-like degeneration generates acute microgliosis and astrogliosis in the nigrostriatal system but no bioluminescence imaging-detectable alteration in adult neurogenesis. Eur J Neurosci 2016; 43:1352-65. [PMID: 26950181 DOI: 10.1111/ejn.13232] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 03/03/2016] [Accepted: 03/04/2016] [Indexed: 12/22/2022]
Abstract
Parkinson's disease is a slowly progressing neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra (SN), leading to severe impairment in motor and non-motor functions. Endogenous subventricular zone (SVZ) neural stem cells constantly give birth to new cells that might serve as a possible source for regeneration in the adult brain. However, neurodegeneration is accompanied by neuroinflammation and dopamine depletion, potentially compromising regeneration. We therefore employed in vivo imaging methods to study striatal deafferentation (N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-[(123) I]iodophenyl)nortropane single photon emission computed tomography, DaTscan(™) ) and neuroinflammation in the SN and striatum (N,N-diethyl-2-(2-(4-(2-[(18) F]fluoroethoxy)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide positron emission tomography, [(18) F]DPA-714 PET) in the intranigral 6-hydroxydopamine Parkinson's disease mouse model. Additionally, we transduced cells in the SVZ with a lentivirus encoding firefly luciferase and followed migration of progenitor cells in the SVZ-olfactory bulb axis via bioluminescence imaging under disease and control conditions. We found that activation of microglia in the SN is an acute process accompanying the degeneration of dopaminergic cell bodies in the SN. Dopaminergic deafferentation of the striatum does not influence the generation of doublecortin-positive neuroblasts in the SVZ, but generates chronic astrogliosis in the nigrostriatal system.
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Affiliation(s)
- Inga B Fricke
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany.,ZMBE, Institute of Cell Biology, Stem Cell Biology and Regeneration Group, University of Münster, Münster, Germany
| | - Thomas Viel
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany
| | - Maik M Worlitzer
- ZMBE, Institute of Cell Biology, Stem Cell Biology and Regeneration Group, University of Münster, Münster, Germany
| | - Franziska M Collmann
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany
| | - Alexis Vrachimis
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany.,Department of Nuclear Medicine, University Hospital Münster, Münster, Germany
| | - Andreas Faust
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany
| | - Lydia Wachsmuth
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Cornelius Faber
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany.,DFG EXC 1003, Cluster of Excellence 'Cells in Motion', Münster, Germany
| | - Frédéric Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Michael T Kuhlmann
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany
| | - Klaus Schäfers
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany.,DFG EXC 1003, Cluster of Excellence 'Cells in Motion', Münster, Germany
| | - Sven Hermann
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany.,DFG EXC 1003, Cluster of Excellence 'Cells in Motion', Münster, Germany
| | - Jens C Schwamborn
- ZMBE, Institute of Cell Biology, Stem Cell Biology and Regeneration Group, University of Münster, Münster, Germany.,Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-Belval, Luxembourg
| | - Andreas H Jacobs
- European Institute for Molecular Imaging (EIMI), University of Münster, Waldeyerstraße 15, D-48149, Münster, Germany.,DFG EXC 1003, Cluster of Excellence 'Cells in Motion', Münster, Germany.,Department of Geriatric Medicine, Evangelische Kliniken, Johanniter Krankenhaus, Bonn, Germany
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29
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Henrottin J, Lemaire C, Egrise D, Zervosen A, Van den Eynde B, Plenevaux A, Franci X, Goldman S, Luxen A. Fully automated radiosynthesis of N(1)-[(18)F]fluoroethyl-tryptophan and study of its biological activity as a new potential substrate for indoleamine 2,3-dioxygenase PET imaging. Nucl Med Biol 2016; 43:379-89. [PMID: 27260779 DOI: 10.1016/j.nucmedbio.2016.03.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 02/24/2016] [Accepted: 03/07/2016] [Indexed: 12/31/2022]
Abstract
INTRODUCTION Indoleamine 2,3-dioxygenase (IDO) catalyzes the initial step in the catabolism of l-tryptophan along the kynurenine pathway and exerts immunosuppressive properties in inflammatory and tumor tissues by blocking locally T-lymphocyte proliferation. Recently, 1-(2-[(19)F]fluoroethyl)-dl-tryptophan (1-[(19)F]FE-dl-Trp) was reported as a good and specific substrate of this enzyme. Herein, the radiosynthesis of its radioactive isotopomer (1-[(18)F]FE-dl-Trp, dl-[(18)F]5) is presented along with in vitro enzymatic and cellular uptake studies. METHODS The one-pot n.c.a. radiosynthesis of this novel potential PET imaging tracer, including HPLC purification and formulation, has been fully automated on a FASTlab™ synthesizer. Chiral separation of both isomers and their formulation were implemented on a second cassette. In vitro enzymatic and cellular uptake studies were then conducted with the d-, l- and dl-radiotracers. RESULTS The radiolabeling of the tosylate precursor was performed in DMF (in 5min; RCY: 57% (d.c.), n=3). After hydrolysis, HPLC purification and formulation, dl-[(18)F]5 was obtained with a global radiochemical yield of 18±3% (not decay corrected, n=7, in 80min) and a specific activity of 600±180GBq/μmol (n=5). The subsequent separation of l- and d-enantiomers was performed by chiral HPLC and both were obtained after formulation with an RCY (d.c.) of 6.1% and 5.8%, respectively. In vitro enzymatic assays reveal that l-[(18)F]5 is a better substrate than d-[(18)F]5 for human IDO. In vitro cellular assays show an IDO-specific uptake of the racemate varying from 30% to 50% of that of l-[(18)F]5, and a negligible uptake of d-[(18)F]5. CONCLUSION In vitro studies show that l-[(18)F]5 is a good and specific substrate of hIDO, while presenting a very low efflux. These results confirm that l-[(18)F]5 could be a very useful PET radiotracer for IDO expressing cells in cancer imaging.
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Affiliation(s)
- Jean Henrottin
- Cyclotron Research Center, B30, Université de Liège, Sart-Tilman, B-4000, Liège, Belgium; Department of Chemistry, B6, Université de Liège, Sart-Tilman, B-4000, Liège, Belgium.
| | - Christian Lemaire
- Cyclotron Research Center, B30, Université de Liège, Sart-Tilman, B-4000, Liège, Belgium
| | - Dominique Egrise
- PET/Biomedical Cyclotron Unit and Department of Nuclear Medicine, Erasme Hospital, Université Libre de Bruxelles, B-1070, Brussels, Belgium; Center for Microscopy and Molecular Imaging, Rue Adrienne Bolland 8, B-6041, Gosselies, Belgium
| | - Astrid Zervosen
- Cyclotron Research Center, B30, Université de Liège, Sart-Tilman, B-4000, Liège, Belgium
| | - Benoit Van den Eynde
- Ludwig Institute for Cancer Research, Brussels Branch and de Duve Institute, Université catholique de Louvain, B-1200, Brussels, Belgium
| | - Alain Plenevaux
- Cyclotron Research Center, B30, Université de Liège, Sart-Tilman, B-4000, Liège, Belgium
| | - Xavier Franci
- GE Healthcare, MDx PET Chemistry System, Rue Marie Curie 10/2, B-4431, Loncin (Liège), Belgium
| | - Serge Goldman
- PET/Biomedical Cyclotron Unit and Department of Nuclear Medicine, Erasme Hospital, Université Libre de Bruxelles, B-1070, Brussels, Belgium; Center for Microscopy and Molecular Imaging, Rue Adrienne Bolland 8, B-6041, Gosselies, Belgium
| | - André Luxen
- Cyclotron Research Center, B30, Université de Liège, Sart-Tilman, B-4000, Liège, Belgium
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30
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Gargiulo S, Anzilotti S, Coda ARD, Gramanzini M, Greco A, Panico M, Vinciguerra A, Zannetti A, Vicidomini C, Dollé F, Pignataro G, Quarantelli M, Annunziato L, Brunetti A, Salvatore M, Pappatà S. Imaging of brain TSPO expression in a mouse model of amyotrophic lateral sclerosis with (18)F-DPA-714 and micro-PET/CT. Eur J Nucl Med Mol Imaging 2016; 43:1348-59. [PMID: 26816193 DOI: 10.1007/s00259-016-3311-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 01/05/2016] [Indexed: 12/12/2022]
Abstract
PURPOSE To evaluate the feasibility and sensitivity of (18)F-DPA-714 for the study of microglial activation in the brain and spinal cord of transgenic SOD1(G93A) mice using high-resolution PET/CT and to evaluate the Iba1 and TSPO expression with immunohistochemistry. METHODS Nine symptomatic SOD1(G93A) mice (aged 117 ± 12.7 days, clinical score range 1 - 4) and five WT SOD1 control mice (aged 108 ± 28.5 days) underwent (18)F-DPA-714 PET/CT. SUV ratios were calculated by normalizing the cerebellar (rCRB), brainstem (rBS), motor cortex (rMCX) and cervical spinal cord (rCSC) activities to that of the frontal association cortex. Two WT SOD1 and six symptomatic SOD1(G93A) mice were studied by immunohistochemistry. RESULTS In the symptomatic SOD1(G93A) mice, rCRB, rBS and rCSC were increased as compared to the values in WT SOD1 mice, with a statistically significantly difference in rBS (2.340 ± 0.784 vs 1.576 ± 0.287, p = 0.014). Immunofluorescence studies showed that TSPO expression was increased in the trigeminal, facial, ambiguus and hypoglossal nuclei, as well as in the spinal cord, of symptomatic SOD1(G93A) mice and was colocalized with increased Iba1 staining. CONCLUSION Increased (18)F-DPA-714 uptake can be detected with high-resolution PET/CT in the brainstem of transgenic SOD1(G93A) mice, a region known to be a site of degeneration and increased microglial activation in amyotrophic lateral sclerosis, in agreement with increased TSPO expression in the brainstem nuclei shown by immunostaining. Therefore, (18)F-DPA-714 PET/CT might be a suitable tool to evaluate microglial activation in the SOD1(G93A) mouse model.
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Affiliation(s)
- S Gargiulo
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy.,Ceinge Biotecnologie Avanzate s. c. a r. l., Via G. Salvatore 486, 80145, Naples, Italy
| | - S Anzilotti
- IRCCS SDN, Via E. Gianturco 113, 80143, Naples, Italy
| | - A R D Coda
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy
| | - M Gramanzini
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy.,Ceinge Biotecnologie Avanzate s. c. a r. l., Via G. Salvatore 486, 80145, Naples, Italy
| | - A Greco
- Ceinge Biotecnologie Avanzate s. c. a r. l., Via G. Salvatore 486, 80145, Naples, Italy.,Department of Advanced Biomedical Sciences, University "Federico II", Via S. Pansini 5, 80131, Naples, Italy
| | - M Panico
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy
| | - A Vinciguerra
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, University "Federico II", Via S. Pansini 5, 80131, Naples, Italy
| | - A Zannetti
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy
| | - C Vicidomini
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy
| | - F Dollé
- CEA, Institute for Biomedical Imaging, 4 Place du Général Leclerc, 91401, Orsay, France
| | - G Pignataro
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, University "Federico II", Via S. Pansini 5, 80131, Naples, Italy
| | - M Quarantelli
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy
| | - L Annunziato
- IRCCS SDN, Via E. Gianturco 113, 80143, Naples, Italy.,Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, University "Federico II", Via S. Pansini 5, 80131, Naples, Italy
| | - A Brunetti
- Ceinge Biotecnologie Avanzate s. c. a r. l., Via G. Salvatore 486, 80145, Naples, Italy.,Department of Advanced Biomedical Sciences, University "Federico II", Via S. Pansini 5, 80131, Naples, Italy
| | - M Salvatore
- IRCCS SDN, Via E. Gianturco 113, 80143, Naples, Italy
| | - S Pappatà
- Institute of Biostructure and Bioimaging, National Research Council, Via T. De Amicis 95, 80145, Naples, Italy.
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31
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Bernards N, Pottier G, Thézé B, Dollé F, Boisgard R. In vivo evaluation of inflammatory bowel disease with the aid of μPET and the translocator protein 18 kDa radioligand [18F]DPA-714. Mol Imaging Biol 2015; 17:67-75. [PMID: 25015387 PMCID: PMC4544644 DOI: 10.1007/s11307-014-0765-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Purpose The purpose of the study was to validate [18F]DPA-714, a translocator protein (TSPO) 18 kDa radioligand, as a probe to non-invasively quantify the inflammatory state in inflammatory bowel disease (IBD) animal models. Procedures Quantitative positron emission tomography (PET) imaging of intestinal inflammation was conducted with 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) a glucose metabolism surrogate marker and [18F]DPA-714 a ligand of the 18 kDa TSPO, on two IBD models. The first model was induced using dextran sodium sulfate (DSS), creating global inflammation in the colon. The second model was induced by rectally administering trinitrobenzenesulfonic acid (TNBS), creating local and acute inflammation. Results The level of inflammation was analyzed using PET imaging on days 7 and 8. The analysis obtained with [18F]DPA-714, yielded a significant difference between the DSS treated (0.50 ± 0.17%ID/cc) and non-treated rats (0.35 ± 0.15%ID/cc). [18F]FDG on the other hand did not yield a significant difference. We did observe a mean glucose consumption in the colon increase from 0.40 ± 0.11 %ID/cc to 0.54 ± 0.17 %ID/cc. In the TNBS model, the uptake level of [18 F]DPA-714 increased significantly from 0.46 ± 0.23%ID/cc for the non-treated group, to 1.30 ± 0.62%ID/cc for those treated. PET signal was correlated with increased TSPO expression at cellular level. Conclusions Results indicate that [18F]DPA-714 is suitable for studying inflammation in IBD models. [18F]DPA-714 could be a good molecular probe to non-invasively evaluate the level and localization of inflammation. Moreover, in vivo imaging using this TSPO ligand is potentially a powerful tool to stage and certainly to follow the evolution and therapeutic efficiency at molecular level within this disease family.
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Damont A, Médran-Navarrete V, Cacheux F, Kuhnast B, Pottier G, Bernards N, Marguet F, Puech F, Boisgard R, Dollé F. Novel Pyrazolo[1,5-a]pyrimidines as Translocator Protein 18 kDa (TSPO) Ligands: Synthesis, in Vitro Biological Evaluation, [(18)F]-Labeling, and in Vivo Neuroinflammation PET Images. J Med Chem 2015; 58:7449-64. [PMID: 26280386 DOI: 10.1021/acs.jmedchem.5b00932] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A series of novel pyrazolo[1,5-a]pyrimidines, closely related to N,N-diethyl-2-(2-(4-(2-fluoroethoxy)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide (2, DPA-714), were synthesized and biologically in vitro evaluated for their potential to bind the translocator protein 18 kDa (TSPO), a protein today recognized as an early biomarker of neuroinflammatory processes. This series is composed of fluoroalkyl- and fluoroalkynyl- analogues, prepared from a common iodinated intermediate via Sonogashira coupling reactions. All derivatives displayed subnanomolar affinity for the TSPO (0.37 to 0.86 nM), comparable to that of 2 (0.91 nM). Two of them were radiolabeled with fluorine-18, and their biodistribution was investigated by in vitro autoradiography and positron emission tomography (PET) imaging on a rodent model of neuroinflammation. Brain uptake and local accumulation of both compounds in the AMPA-mediated lesion confirm their potential as in vivo PET-radiotracers. In particular, [(18)F]23 exhibited a significantly higher ipsi- to contralateral ratio at 60 min than the parent molecule [(18)F]2 in vivo.
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Affiliation(s)
- Annelaure Damont
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
| | - Vincent Médran-Navarrete
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
| | - Fanny Cacheux
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
| | - Bertrand Kuhnast
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
| | - Géraldine Pottier
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
| | - Nicholas Bernards
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
| | | | | | - Raphaël Boisgard
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
| | - Frédéric Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France.,Inserm/CEA/Université Paris Sud, UMR 1023-ERL 9218 CNRS, IMIV, Orsay, France
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33
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Ory D, Postnov A, Koole M, Celen S, de Laat B, Verbruggen A, Van Laere K, Bormans G, Casteels C. Quantification of TSPO overexpression in a rat model of local neuroinflammation induced by intracerebral injection of LPS by the use of [(18)F]DPA-714 PET. Eur J Nucl Med Mol Imaging 2015; 43:163-172. [PMID: 26323575 DOI: 10.1007/s00259-015-3172-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 08/10/2015] [Indexed: 11/27/2022]
Abstract
PURPOSE [(18)F]DPA-714 is a radiotracer with high affinity for TSPO. We have characterized the kinetics of [(18)F]DPA-714 in rat brain and evaluated its ability to quantify TSPO expression with PET using a neuroinflammation model induced by unilateral intracerebral injection of lipopolysaccharide (LPS). METHODS Dynamic small-animal PET scans with [(18)F]DPA-714 were performed in Wistar rats on a FOCUS-220 system for up to 3 h. Both plasma and perfused brain homogenates were analysed using HPLC to quantify radiometabolites. Full kinetic modelling of [(18)F]DPA-714 brain uptake was performed using a metabolite-corrected arterial plasma input function. Binding potential (BPND) calculated as the distribution volume ratio minus one (DVR-1) between affected and healthy brain tissue was used as the outcome measure and evaluated against reference tissue models. RESULTS The percentage of intact [(18)F]DPA-714 in arterial plasma samples was 92 ± 4 % at 10 min, 75 ± 8 % at 40 min and 52 ± 6 % at 180 min. The radiometabolite fraction in brain was negligible (<3 % at 30 min). Among the models investigated, the reversible two-tissue (2T) compartment model best described [(18)F]DPA-714 brain kinetics. BPND values obtained with a simplified and a multilinear reference tissue model (SRTM, MRTM) using the contralateral striatum as the reference region correlated well (Spearman's r = 0.96, p ≤ 0.003) with 2T BPND values calculated as DVR-1, and showed comparable bias (bias range 17.94 %, 20.32 %). Analysis of stability over time suggested that the acquisition time should be at least 90 min for SRTM and MRTM. CONCLUSION Quantification of [(18)F]DPA-714 binding to TSPO with full kinetic modelling is feasible using a 2T model. SRTM and MRTM can be suggested as reasonable substitutes with the contralateral striatum as the reference region and a scan duration of at least 90 min. However, selection of the reference region depends on the disease model used.
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Affiliation(s)
- Dieter Ory
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Campus Gasthuisberg O&N2, Herestraat 49 Box 821, BE-3000, Leuven, Belgium
| | - Andrey Postnov
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, University Hospital and KU Leuven, Leuven, Belgium
| | - Michel Koole
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, University Hospital and KU Leuven, Leuven, Belgium
| | - Sofie Celen
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Campus Gasthuisberg O&N2, Herestraat 49 Box 821, BE-3000, Leuven, Belgium
| | - Bart de Laat
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, University Hospital and KU Leuven, Leuven, Belgium
| | - Alfons Verbruggen
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Campus Gasthuisberg O&N2, Herestraat 49 Box 821, BE-3000, Leuven, Belgium
| | - Koen Van Laere
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, University Hospital and KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Campus Gasthuisberg O&N2, Herestraat 49 Box 821, BE-3000, Leuven, Belgium.
| | - Cindy Casteels
- Nuclear Medicine and Molecular Imaging, Department of Imaging and Pathology, University Hospital and KU Leuven, Leuven, Belgium
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34
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Damont A, Marguet F, Puech F, Dollé F. Synthesis and in vitro characterization of novel fluorinated derivatives of the TSPO 18 kDa ligand SSR180575. Eur J Med Chem 2015. [DOI: 10.1016/j.ejmech.2015.07.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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35
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Ory D, Planas A, Dresselaers T, Gsell W, Postnov A, Celen S, Casteels C, Himmelreich U, Debyser Z, Van Laere K, Verbruggen A, Bormans G. PET imaging of TSPO in a rat model of local neuroinflammation induced by intracerebral injection of lipopolysaccharide. Nucl Med Biol 2015. [PMID: 26220690 DOI: 10.1016/j.nucmedbio.2015.06.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE The goal of this study was to measure functional and structural aspects of local neuroinflammation induced by intracerebral injection of lipopolysaccharide (LPS) in rats using TSPO microPET imaging with [(18)F]DPA-714, magnetic resonance imaging (MRI), in vitro autoradiography and immunohistochemistry (IHC) in order to characterize a small animal model for screening of new PET tracers targeting neuroinflammation. METHODS Rats were injected stereotactically with LPS (50 μg) in the right striatum and with saline in the left striatum. [(18)F]DPA-714 microPET, MRI, in vitro autoradiography and IHC studies were performed at different time points after LPS injection for 1 month. RESULTS Analysis of the microPET data demonstrated high uptake of the tracer in the LPS injected site with an affected-to-non-affected side-binding potential ratio (BPright-to-left) of 3.0 at 3 days after LPS injection. This BP ratio decreased gradually over time to 0.9 at 30 days after LPS injection. In vitro autoradiography ([(18)F]DPA-714) and IHC (CD68, GFAP and TSPO) confirmed local neuroinflammation in this model. Dynamic contrast enhanced (DCE) MRI demonstrated BBB breakdown near the LPS injection site at day 1, which gradually resolved over time and was absent at 1 month after LPS injection. CONCLUSION The LPS model is useful for first screening of newly developed tracers because of the easy design and the robust, unilateral inflammatory reaction allowing the use of the contralateral region as control. Additionally, this model can be used to test and follow up the benefits of anti-inflammatory therapies by non-invasive imaging.
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Affiliation(s)
- Dieter Ory
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Anna Planas
- Department of Brain Ischemia and Neurodegeneration, Institute for Biomedical Research, Barcelona, Spain
| | - Tom Dresselaers
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - Willy Gsell
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - Andrey Postnov
- Nuclear Medicine and Molecular Imaging, University Hospital and KU Leuven, Leuven, Belgium
| | - Sofie Celen
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Cindy Casteels
- Nuclear Medicine and Molecular Imaging, University Hospital and KU Leuven, Leuven, Belgium
| | - Uwe Himmelreich
- Biomedical MRI, Department of Imaging and Pathology, KU Leuven, Leuven, Belgium
| | - Zeger Debyser
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Koen Van Laere
- Nuclear Medicine and Molecular Imaging, University Hospital and KU Leuven, Leuven, Belgium
| | - Alfons Verbruggen
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Guy Bormans
- Laboratory for Radiopharmacy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium.
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Neumann KT, Lindhardt AT, Bang-Andersen B, Skrydstrup T. Access to 2-(Het)aryl and 2-Styryl Benzoxazoles via Palladium-Catalyzed Aminocarbonylation of Aryl and Vinyl Bromides. Org Lett 2015; 17:2094-7. [PMID: 25879769 DOI: 10.1021/acs.orglett.5b00642] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A sequential one-pot procedure for the synthesis of either 2-(hetero)aryl or 2-styryl benzoxazoles is reported, starting from aryl and vinyl bromides, respectively, involving an initial aminocarbonylation with 2-aminophenols as nucleophiles followed by an acid mediated ring closure to generate the heterocycle. The methodology displays a broad substrate scope in moderate to excellent yields and can be exploited for (13)C-isotope labeling. Finally, this carbonylative protocol was applied to the synthesis of a potential Alzheimer's plaque binder and a selective PPAR antagonist including site-specific labeling with (13)C-carbon monoxide.
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Affiliation(s)
- Karoline T Neumann
- †Center for Insoluble Protein Structures (inSPIN), Department of Chemistry and the Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
| | - Anders T Lindhardt
- ‡Interdisciplinary Nanoscience Center (iNANO), Biological and Chemical Engineering and Department of Engineering, Aarhus University, Finlandsgade 22, 8200 Aarhus N, Denmark
| | - Benny Bang-Andersen
- §Lundbeck Research Denmark, H. Lundbeck A/S, Ottiliavej 9, 2500 Valby, Denmark
| | - Troels Skrydstrup
- †Center for Insoluble Protein Structures (inSPIN), Department of Chemistry and the Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark
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Banister SD, Beinat C, Wilkinson SM, Shen B, Bartoli C, Selleri S, Da Pozzo E, Martini C, Chin FT, Kassiou M. Ether analogues of DPA-714 with subnanomolar affinity for the translocator protein (TSPO). Eur J Med Chem 2015; 93:392-400. [DOI: 10.1016/j.ejmech.2015.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 02/04/2015] [Accepted: 02/05/2015] [Indexed: 12/13/2022]
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Damont A, Garcia-Argote S, Buisson DA, Rousseau B, Dollé F. Efficient tritiation of the translocator protein (18 kDa) selective ligand DPA-714. J Labelled Comp Radiopharm 2015; 58:1-6. [DOI: 10.1002/jlcr.3252] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Revised: 11/21/2014] [Accepted: 11/28/2014] [Indexed: 12/13/2022]
Affiliation(s)
- Annelaure Damont
- CEA; DSV/I BM, Service Hospitalier Frédéric Joliot; 91401 Orsay France
| | - Sébastien Garcia-Argote
- CEA; DSV/iBiTec-S, Service de Chimie bioorganique et de Marquage; 91191 Gif-sur-Yvette France
| | - David-Alexandre Buisson
- CEA; DSV/iBiTec-S, Service de Chimie bioorganique et de Marquage; 91191 Gif-sur-Yvette France
| | - Bernard Rousseau
- CEA; DSV/iBiTec-S, Service de Chimie bioorganique et de Marquage; 91191 Gif-sur-Yvette France
| | - Frédéric Dollé
- CEA; DSV/I BM, Service Hospitalier Frédéric Joliot; 91401 Orsay France
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Lavisse S, Inoue K, Jan C, Peyronneau MA, Petit F, Goutal S, Dauguet J, Guillermier M, Dollé F, Rbah-Vidal L, Van Camp N, Aron-Badin R, Remy P, Hantraye P. [18F]DPA-714 PET imaging of translocator protein TSPO (18 kDa) in the normal and excitotoxically-lesioned nonhuman primate brain. Eur J Nucl Med Mol Imaging 2014; 42:478-94. [PMID: 25488184 DOI: 10.1007/s00259-014-2962-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 11/12/2014] [Indexed: 01/05/2023]
Abstract
PURPOSE We aimed to characterize pharmacologically the TSPO- radioligand [(18)F]DPA-714 in the brain of healthy cynomolgus monkeys and evaluate the cellular origin of its binding in a model of neurodegeneration induced by intrastriatal injection of quinolinic acid (QA). METHODS [(18)F]DPA-714 PET images were acquired before and at 2, 7, 14, 21, 49, 70, 91 days after putaminal lesioning. Blocking and displacement studies were carried out (PK11195). Different modelling approaches estimated rate constants and V T (total distribution volume) which was used to measure longitudinal changes in the lesioned putamen. Sections for immunohistochemical labelling were prepared at the same time-points to evaluate correlations between in vivo [(18)F]DPA-714 binding and microglial/astrocytic activation. RESULTS [(18)F]DPA-714 showed a widespread distribution with a higher signal in the thalamus and occipital cortex and lower binding in the cerebellum. TSPO was expressed throughout the whole brain and about 73 % of [(18)F]DPA-714 binding was specific for TSPO in vivo. The one-tissue compartment model (1-TCM) provided good and reproducible estimates of V T and rate constants, and V T values from the 1-TCM and the Logan approach were highly correlated (r (2) = 0.85). QA lesioning induced an increase in V T, which was +17 %, +54 %, +157 % and +39 % higher than baseline on days 7, 14, 21 and 91 after QA injection, respectively. Immunohistochemistry revealed an early microglial and a delayed astrocytic activation after QA injection. [(18)F]DPA-714 binding matched TSPO immunopositive areas and showed a stronger colocalization with CD68 microglia than with GFAP-activated astrocytes. CONCLUSION [(18)F]DPA-714 binds to TSPO with high specificity in the primate brain under normal conditions and in the QA model. This tracer provides a sensitive tool for assessing neuroinflammation in the human brain.
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Affiliation(s)
- S Lavisse
- CEA, I2BM, MIRCen, 18 route du Panorama, 92260, Fontenay-aux-Roses, France,
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Vicidomini C, Panico M, Greco A, Gargiulo S, Coda ARD, Zannetti A, Gramanzini M, Roviello GN, Quarantelli M, Alfano B, Tavitian B, Dollé F, Salvatore M, Brunetti A, Pappatà S. In vivo imaging and characterization of [(18)F]DPA-714, a potential new TSPO ligand, in mouse brain and peripheral tissues using small-animal PET. Nucl Med Biol 2014; 42:309-16. [PMID: 25537727 DOI: 10.1016/j.nucmedbio.2014.11.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 11/18/2014] [Accepted: 11/19/2014] [Indexed: 02/05/2023]
Abstract
INTRODUCTION The translocator protein 18 kDa (TSPO), a biochemical marker of neuroinflammation, is highly expressed in the brain activated microglia and it is also expressed by peripheral inflammatory cells and normal peripheral tissues. Thus, development of radioligands for the TSPO may contribute to further understanding the in vivo TSPO function in central and peripheral inflammatory processes and other pathologies. Here, we report the biodistribution, the specific binding and the radiometabolites of [(18)F]DPA-714, a promising fluorinated PET radiotracer, in normal mice using a microPET/CT scanner. METHODS The in vivo biodistribution and kinetics of [(18)F]DPA-714 were measured in mice brain and peripheral tissues. Specific binding to TSPO sites was assessed using pharmacological competitive studies by means of saturation experiments performed by i.v. injection of 1mg/kg of unlabeled DPA-714 or 3mg/kg of unlabeled PK11195. A region of interest analysis was performed to generate time-activity curves in the brain, heart, lung, kidney, spleen and liver. Metabolites assay was performed in the plasma and peripheral organs by radio-HPLC. RESULTS [(18)F]DPA-714 reached high concentration in lung, heart, kidney and spleen, tissues well known to be rich in TSPO sites. [(18)F]DPA-714 kinetics were faster in the lung and slower in the kidney. Pre-injection of unlabeled DPA-714 or PK11195 inhibited about 80% of [(18)F]DPA-714 uptake in the lung and heart (p<0.0005). The percentage of inhibition in the kidney was lower and achieved at later times only with DPA-714 (p<0.05) but not with PK11195. Sixty minutes after radiotracer injection only unmetabolized radioligand was found in the brain, lung, heart and spleen. CONCLUSION These results suggest that [(18)F]DPA-714 is a suitable PET ligand for imaging in mice brain and peripheral tissues since it binds with high specificity TSPO binding sites and it is almost unchanged at 60 minutes after radiotracer injection in the brain and TSPO-rich regions.
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Affiliation(s)
- Caterina Vicidomini
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Mariarosaria Panico
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Adelaide Greco
- Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Sara Gargiulo
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Anna Rita Daniela Coda
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Antonella Zannetti
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Matteo Gramanzini
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | | | | | - Bruno Alfano
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy
| | - Bertrand Tavitian
- Inserm U970, PARCC, Université Paris Descartes, Hôpital Européen Georges Pompidou, Paris, France; CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Frederic Dollé
- CEA, I2BM, Service Hospitalier Frédéric Joliot, Orsay, France
| | - Marco Salvatore
- Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy
| | - Arturo Brunetti
- Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy; CEINGE, Biotecnologie Avanzate, s.c.a.r.l., Naples, Italy
| | - Sabina Pappatà
- Institute of Biostructure and Bioimaging, CNR, Naples, Italy.
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Bourdier T, Henderson D, Fookes CJ, Lam P, Mattner F, Fulham M, Katsifis A. Synthesis of [11C]PBR170, a novel imidazopyridine, for imaging the translocator protein with PET. Appl Radiat Isot 2014; 90:46-52. [DOI: 10.1016/j.apradiso.2014.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 02/26/2014] [Accepted: 03/08/2014] [Indexed: 10/25/2022]
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Chiotellis A, Muller A, Mu L, Keller C, Schibli R, Krämer SD, Ametamey SM. Synthesis and biological evaluation of (18)F-labeled Fluoroethoxy tryptophan analogues as potential PET tumor imaging agents. Mol Pharm 2014; 11:3839-51. [PMID: 24988527 DOI: 10.1021/mp500312t] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
As a continuation of our research efforts toward the development of tryptophan-based radiotracers for tumor imaging with positron emission tomography (PET), three new fluoroethoxy tryptophan analogues were synthesized and evaluated in vivo. These new tracers (namely, 4-(2-[(18)F]fluoroethoxy)-dl-tryptophan ([(18)F]4-FEHTP), 6-(2-[(18)F]fluoroethoxy)-dl-tryptophan ([(18)F]6-FEHTP), and 7-(2-[(18)F]fluoroethoxy)-dl-tryptophan ([(18)F]7-FEHTP) carry the fluoroethoxy side chain either at positions 4-, 6-, or 7- of the indole core. Reference compounds and precursors were synthesized by multistep approaches. Radiosynthesis was accomplished by no-carrier-added nucleophilic (18)F-fluorination following either an indirect approach (O-alkylation of the corresponding hydroxytryptophan with [(18)F]fluoroethyltosylate) or a direct approach (nucleophilic [(18)F] fluorination using a protected mesyl precursor). Radiochemical yields (decay corrected) for both methods were in the range of 10-18%. Small animal PET imaging with xenograft-bearing mice revealed the highest tumor/background ratio for [(18)F]6-FEHTP which, in a direct comparison, outperformed the other two tryptophan tracers and also the well-established tyrosine analogue O-(2-[(18)F]fluoroethyl)-l-tyrosine ([(18)F]l-FET). Investigation of the transport mechanism of [(18)F]6-FEHTP in small cell lung cancer cells (NCI-H69) revealed that it is most probably taken up exclusively via the large neutral amino acid transporter(s) (LAT).
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Affiliation(s)
- Aristeidis Chiotellis
- Center for Radiopharmaceutical Sciences ETH-PSI-USZ, Institute of Pharmaceutical Sciences ETH , Vladimir-Prelog-Weg 4, 8093 Zurich, Switzerland
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Médran-Navarrete V, Bernards N, Kuhnast B, Damont A, Pottier G, Peyronneau MA, Kassiou M, Marguet F, Puech F, Boisgard R, Dollé F. [18F]DPA-C5yne, a novel fluorine-18-labelled analogue of DPA-714: radiosynthesis and preliminary evaluation as a radiotracer for imaging neuroinflammation with PET. J Labelled Comp Radiopharm 2014; 57:410-8. [PMID: 24764161 DOI: 10.1002/jlcr.3199] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/17/2014] [Accepted: 03/19/2014] [Indexed: 12/13/2022]
Abstract
DPA-C5yne, the lead compound of a novel series of DPA-714 derivatives in which the fluoroethoxy chain linked to the phenylpyrazolopyrimidine scaffold has been replaced by a fluoroalkyn-1-yl moiety, is a high affinity (Ki : 0.35 nM) and selective ligand targeting the translocator protein 18 kDa. In the present work, DPA-C5yne was labelled with no-carrier-added [(18)F]fluoride based on a one-step tosyloxy-for-fluorine nucleophilic substitution reaction, purified by cartridge and HPLC, and formulated as an i.v. injectable solution using a TRACERLab FX N Pro synthesizer. Typically, 4.3-5.2 GBq of [(18)F]DPA-C5yne, ready-to-use, chemically and radiochemically pure (> 95%), was obtained with specific radioactivities ranging from 55 to 110 GBq/µmol within 50-60 min, starting from a 30 GBq [(18)F]fluoride batch (14-17%). LogP and LogD of [(18)F]DPA-C5yne were measured using the shake-flask method and values of 2.39 and 2.51 were found, respectively. Autoradiography studies performed on slices of ((R,S)-α-amino-3-hydroxy-5-methyl-4-isoxazolopropionique (AMPA)-lesioned rat brains showed a high target-to-background ratio (1.9 ± 0.3). Selectivity and specificity of the binding for the translocator protein was demonstrated using DPA-C5yne (unlabelled), PK11195 and Flumazenil (central benzodiazepine receptor ligand) as competitors. Furthermore, DPA-C5yne proved to be stable in plasma at 37°C for at least 90 min.
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Pottier G, Bernards N, Dollé F, Boisgard R. [¹⁸F]DPA-714 as a biomarker for positron emission tomography imaging of rheumatoid arthritis in an animal model. Arthritis Res Ther 2014; 16:R69. [PMID: 24621017 PMCID: PMC4060384 DOI: 10.1186/ar4508] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 02/17/2014] [Indexed: 12/23/2022] Open
Abstract
INTRODUCTION Rheumatoid arthritis (RA) is a chronic disease, affecting 0.5 to 1% of adults in industrialized countries, in which systemic inflammation and synovitis drive joint destruction. [¹⁸F]DPA-714 is a specific tracer of the 18 kDa translocator protein (TSPO), which is overexpressed on activated macrophages, and proposed as a biomarker of neuroinflammation. Today, diagnosis of patients with early inflammatory arthritis is limited by poor sensitivity and specificity. The present study aims to investigate the potential of [¹⁸F]DPA-714 to monitor in vivo inflammatory processes at a preclinical stage via positron emission tomography (PET). METHODS RA was induced in Dark Agouti rats by subcutaneous injection of inactivated Mycobacterium tuberculosis. Development of arthritis clinical signs was investigated daily and the severity of the disease evaluated. Animals were imaged at the peak of inflammation using [¹⁸F]DPA-714 and a small-animal PET-CT tomograph. RESULTS The first clinical signs appeared at 10 days post-injection, with a peak of inflammation at 20 days. At this time, PET-analyses showed a clear uptake of [¹⁸F]DPA-714 in swollen ankles, with mean values of 0.52 ± 0.18% injected dose (ID/cc) for treated (n = 11) and 0.19 ± 0.09 for non-treated (n = 6) rats. A good correlation between [¹⁸F]DPA-714's uptake and swelling was also found. Immunohistochemistry showed an enhanced TSPO expression in hind paws, mainly co-localized with the macrophages specific antigen CD68 expressing cells. CONCLUSION These preliminary results demonstrate that the TSPO 18 kDa specific radioligand [¹⁸F]DPA-714 is adapted for the study and follow-up of inflammation linked to RA in our experimental model, suggesting also a strong potential for clinical imaging of peripheral inflammation.
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Médran-Navarrete V, Damont A, Peyronneau MA, Kuhnast B, Bernards N, Pottier G, Marguet F, Puech F, Boisgard R, Dollé F. Preparation and evaluation of novel pyrazolo[1,5-a]pyrimidine acetamides, closely related to DPA-714, as potent ligands for imaging the TSPO 18kDa with PET. Bioorg Med Chem Lett 2014; 24:1550-6. [DOI: 10.1016/j.bmcl.2014.01.080] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 01/24/2014] [Accepted: 01/27/2014] [Indexed: 12/13/2022]
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Synthesis and biological evaluation of positron emission tomography radiotracers targeting serotonin 4 receptors in brain: [18F]MNI-698 and [18F]MNI-699. Bioorg Med Chem Lett 2013; 23:6243-7. [DOI: 10.1016/j.bmcl.2013.09.097] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 09/25/2013] [Accepted: 09/30/2013] [Indexed: 01/06/2023]
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Nemoto T, Ida Y, Iihara Y, Nakajima R, Hirayama S, Iwai T, Fujii H, Nagase H. The most effective influence of 17-(3-ethoxypropyl) substituent on the binding affinity and the agonistic activity in KNT-127 derivatives, δ opioid receptor agonists. Bioorg Med Chem 2013; 21:7628-47. [PMID: 24262888 DOI: 10.1016/j.bmc.2013.10.032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 10/21/2013] [Accepted: 10/22/2013] [Indexed: 10/26/2022]
Abstract
We investigated the structure-activity relationship of KNT-127 (opioid δ agonist) derivatives with various 17-substituents which are different in length and size. The 17-substituent in KNT-127 derivatives exerted a great influence on the affinity and agonistic activity for the δ receptor. While the compounds with electron-donating 17-substituents showed higher affinities for the δ receptor than those with electron-withdrawing groups, KNT-127 derivatives with 17-fluoroalkyl groups (the high electron-withdrawing groups) showed high selectivities for the δ receptor among evaluated compounds. In addition, the basicity of nitrogen as well as the structure of the 17-N substituent such as the length and configuration at an asymmetric carbon atom contributed to agonist properties for the δ receptor. Thus, the analog with a 17-(3-ethoxypropyl) group showed the best selectively and potent agonistic activity for the δ receptor among KNT-127 derivatives. These findings should be useful for designing novel δ selective agonists.
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Affiliation(s)
- Toru Nemoto
- School of Pharmacy, Kitasato University, 5-9-1, Shirokane, Minato-ku, Tokyo 108-8641, Japan
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Wickstrøm T, Clarke A, Gausemel I, Horn E, Jørgensen K, Khan I, Mantzilas D, Rajanayagam T, in 't Veld DJ, Trigg W. The development of an automated and GMP compliant FASTlab™ Synthesis of [(18) F]GE-180; a radiotracer for imaging translocator protein (TSPO). J Labelled Comp Radiopharm 2013; 57:42-8. [PMID: 24448744 DOI: 10.1002/jlcr.3112] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 05/24/2013] [Accepted: 08/12/2013] [Indexed: 11/08/2022]
Abstract
The level of the translocator protein (TSPO) increases dramatically in microglial cells when the cells are activated in response to neuronal injury and insult. The radiotracer [(18) F]GE-180 binds selectively and with high affinity to TSPO and can therefore be used to measure neuroinflammation in a variety of disease states. An optimized, automated synthesis of [(18) F]GE-180 has been developed for the GE FASTlab™ synthesizer. The entire process takes place on the single-use cassette. The radiolabelling is performed by nucleophilic fluorination of the S- enantiomer mesylate precursor. The crude product is purified post-radiolabelling using two solid-phase extraction cartridges integrated on the cassette. Experimental design and multivariate data analysis were used to assess the robustness, and critical steps were optimized with respect to efficacy and quality. The average radiochemical yield is 48% (RSD 6%, non-decay corrected), and the synthesis time including purification is approximately 43 min. The radiochemical purity is ≥95% for radioactive concentration ≤1100 MBq/mL. The total amount of precursor-related chemical impurities is 1-2 µg/mL. The use of solid-phase extraction purification results in a robust GMP compliant process with a product of high chemical and radiochemical purity and consistent performance across positron emission tomography (PET) centers.
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Pan J, Pourghiasian M, Hundal N, Lau J, Bénard F, Dedhar S, Lin KS. f-[18F]fluoroethanol and 3-[18F]fluoropropanol: facile preparation, biodistribution in mice, and their application as nucleophiles in the synthesis of [18F]fluoroalkyl aryl ester and ether PET tracers. Nucl Med Biol 2013; 40:850-7. [PMID: 23774003 DOI: 10.1016/j.nucmedbio.2013.04.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2013] [Revised: 04/01/2013] [Accepted: 04/19/2013] [Indexed: 10/26/2022]
Abstract
INTRODUCTION 2-[(18)F]Fluoroethoxy and 3-[(18)F]fluoropropoxy groups are common moieties in the structures of radiotracers used with positron emission tomography. The objectives of this study were (1) to develop an efficient one-step method for the preparation of 2-[(18)F]fluoroethanol (2-[(18)F]FEtOH) and 3-[(18)F]fluoropropanol (3-[(18)F]FPrOH); (2) to demonstrate the feasibility of using 2-[(18)F]FEtOH as a nucleophile for the synthesis of 2-[(18)F]fluoroethyl aryl esters and ethers; and (3) to determine the biodistribution profiles of 2-[(18)F]FEtOH and 3-[(18)F]FPrOH in mice. METHODS 2-[(18)F]FEtOH and 3-[(18)F]FPrOH were prepared by reacting n-Bu4N[(18)F]F with ethylene carbonate and 1,3-dioxan-2-one, respectively, in diethylene glycol at 165°C and purified by distillation. 2-[(18)F]fluoroethyl 4-fluorobenzoate and 1-(2-[(18)F]fluoroethoxy)-4-nitrobenzene were prepared by coupling 2-[(18)F]FEtOH with 4-fluorobenzoyl chloride and 1-fluoro-4-nitrobenzene, respectively. Biodistribution and PET/CT imaging studies of 2-[(18)F]FEtOH and 3-[(18)F]FPrOH were performed in normal female Balb/C mice. RESULTS The preparation of 2-[(18)F]FEtOH and 3-[(18)F]FPrOH took 60 min, and their decay-corrected yields were 88.6 ± 2.0% (n = 9) and 65.6 ± 10.2% (n = 5), respectively. The decay-corrected yields for the preparation of 2-[(18)F]fluoroethyl 4-fluorobenzoate and 1-(2-[(18)F]fluoroethoxy)-4-nitrobenzene were 36.1 ± 5.4% (n = 3) and 27.7 ± 10.7% (n = 3), respectively. Imaging/biodistribution studies in mice using 2-[(18)F]FEtOH showed high initial radioactivity accumulation in all major organs followed by very slow clearance. On the contrary, by using 3-[(18)F]FPrOH, radioactivity accumulated in all major organs was cleared rapidly, but massive in vivo defluorination (31.3 ± 9.57%ID/g in bone at 1h post-injection) was observed. CONCLUSIONS Using 2-[(18)F]FEtOH/3-[(18)F]FPrOH as a nucleophile is a competitive new strategy for the synthesis of 2-[(18)F]fluoroethyl/3-[(18)F]fluoropropyl aryl esters and ethers. Our biodistribution data emphasize the importance of in vivo stability of PET tracers containing a 2-[(18)F]fluoroethyl or 3-[(18)F]fluoropropyl group due to high background and high bone uptake resulting from 2-[(18)F]FEtOH and 3-[(18)F]FPrOH, respectively. This is especially important for their aryl ester derivatives which are prone to in vivo hydrolysis.
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Affiliation(s)
- Jinhe Pan
- Department of Molecular Oncology, BC Cancer Agency, Vancouver, BC, Canada V5Z1L3
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Jarkas N, Voll RJ, Goodman MM. Synthesis of a phenolic precursor and its efficientO-[18F]fluoroethylation with purified no-carrier-added [18F]2-fluoroethyl brosylate as the labeling agent. J Labelled Comp Radiopharm 2013; 56:539-43. [DOI: 10.1002/jlcr.3046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 03/07/2013] [Accepted: 03/12/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Nashwa Jarkas
- Department of Radiology and Imaging Sciences; Emory University School of Medicine, Center for Systems Imaging, Wesley Woods Health Center; Atlanta; GA; USA
| | - Ronald J. Voll
- Department of Radiology and Imaging Sciences; Emory University School of Medicine, Center for Systems Imaging, Wesley Woods Health Center; Atlanta; GA; USA
| | - Mark M. Goodman
- Department of Radiology and Imaging Sciences; Emory University School of Medicine, Center for Systems Imaging, Wesley Woods Health Center; Atlanta; GA; USA
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