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Kim YI, Lee SH, Jung JH, Kim SY, Ko N, Lee SJ, Oh SJ, Ryu JS, Ko D, Kim W, Kim K. 18F-ASEM PET/MRI targeting alpha7-nicotinic acetylcholine receptor can reveal skeletal muscle denervation. EJNMMI Res 2024; 14:8. [PMID: 38252356 PMCID: PMC10803689 DOI: 10.1186/s13550-024-01067-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 12/31/2023] [Indexed: 01/23/2024] Open
Abstract
BACKGROUND The increased expression of the nicotinic acetylcholine receptor (nAChR) in muscle denervation is thought to be associated with electrophysiological acetylcholine supersensitivity after nerve injury. Hence, we investigated the utility of the 18F-ASEM alpha7-nAChR targeting radiotracer as a new diagnostic method by visualizing skeletal muscle denervation in mouse models of sciatic nerve injury. METHODS Ten-week-old C57BL/6 male mice were utilized. The mice were anesthetized, and the left sciatic nerve was resected after splitting the gluteal muscle. One week (n = 11) and three weeks (n = 6) after the denervation, 18F-ASEM positron emission tomography/magnetic resonance imaging (PET/MRI) was acquired. Maximum standardized uptake values (SUVmax) of the tibialis anterior muscle were measured for the denervated side and the control side. Autoradiographic evaluation was performed to measure the mean counts of the denervated and control tibialis anterior muscles at one week. In addition, immunohistochemistry was used to identify alpha7-nAChR-positive areas in denervated and control tibialis anterior muscles at one week (n = 6). Furthermore, a blocking study was conducted with methyllycaconitine (MLA, n = 5). RESULTS 18F-ASEM PET/MRI showed significantly increased 18F-ASEM uptake in the denervated tibialis anterior muscle relative to the control side one week and three weeks post-denervation. SUVmax of the denervated muscles at one week and three weeks showed significantly higher uptake than the control (P = 0.0033 and 0.0277, respectively). The relative uptake by autoradiography for the denervated muscle was significantly higher than in the control, and immunohistochemistry revealed significantly greater alpha7-nAChR expression in the denervated muscle (P = 0.0277). In addition, the blocking study showed no significant 18F-ASEM uptake in the denervated side when compared to the control (P = 0.0796). CONCLUSIONS Our results suggest that nAChR imaging with 18F-ASEM has potential as a noninvasive diagnostic method for peripheral nervous system disorders.
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Affiliation(s)
- Yong-Il Kim
- Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Seung Hak Lee
- Department of Rehabilitation Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-Ro 43-Gil, Songpa-Gu, Seoul, 05505, Republic of Korea.
| | - Jin Hwa Jung
- Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea
- Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Seog-Young Kim
- Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea
- Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Nare Ko
- Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
- Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Sang Ju Lee
- Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Seung Jun Oh
- Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Jin-Sook Ryu
- Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Dabin Ko
- Department of Rehabilitation Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-Ro 43-Gil, Songpa-Gu, Seoul, 05505, Republic of Korea
| | - Won Kim
- Department of Rehabilitation Medicine, Asan Medical Center, University of Ulsan College of Medicine, 88 Olympic-Ro 43-Gil, Songpa-Gu, Seoul, 05505, Republic of Korea
| | - Kyunggon Kim
- Convergence Medicine Research Center, Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea
- Asan Institute for Life Sciences, Asan Medical Center, Seoul, Republic of Korea
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
- Clinical Proteomics Core Laboratory, Convergence Medicine Research Center, Asan Medical Center, Seoul, Republic of Korea
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Yang T, Wang D, Chen X, Liang Y, Guo F, Wu C, Jia L, Hou Z, Li W, He Z, Wang X. 18F-ASEM Imaging for Evaluating Atherosclerotic Plaques Linked to α7-Nicotinic Acetylcholine Receptor. Front Bioeng Biotechnol 2021; 9:684221. [PMID: 34277585 PMCID: PMC8280778 DOI: 10.3389/fbioe.2021.684221] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/12/2021] [Indexed: 12/21/2022] Open
Abstract
Background Atherosclerosis is a chronic vascular inflammatory procedure alongside with lipid efflux disorder and foam cell formation. α7-Nicotinic acetylcholine receptor (α7nAChR) is a gated-calcium transmembrane channel widely expressed in neuron and non-neuron cells, such as monocytes and macrophages, activated T cells, dendritic cells, and mast cells. 18F-ASEM is an inhibitor targeted to α7nAChR that had been successfully applied in nervous system diseases. Previous studies had highlighted that α7nAChR was related to the emergency of vulnerable atherosclerotic plaques with excess inflammation cells. Thus, 18F-ASEM could be a complementary diagnostic approach to atherosclerotic plaques. Materials and Methods The synthesis of ASEM precursor and 18F-labeling had been performed successfully. We had established the ApoE–/– mice atherosclerotic plaques model (fed with western diet) and New Zealand rabbits atherosclerotic models (balloon-sprained experiment and western diet). After damage of endothelial cells and primary plaque formation, 18F-ASEM imaging of atherosclerotic plaques linked to α7nAChR had been conducted. In vivo micro-PET/CT imaging of ApoE–/– mice and the control group was performed 1 h after injection of 18F-ASEM (100–150 μCi); PET/CT imaging for rabbits with atherosclerotic plaques and control ones was also performed. Meanwhile, we also conducted CT scan on the abdominal aorta of these rabbits. After that, the animals were sacrificed, and the carotid and abdominal aorta were separately taken out for circular sections. The paraffin-embedded specimens were sectioned with 5 μm thickness and stained with hematoxylin–eosin (H&E) and oil red. Results In vivo vessel binding of 18F-ASEM and α7nAChR expression in the model group with atherosclerosis plaques was significantly higher than that in the control group. PET/CT imaging successfully identified the atherosclerotic plaques in ApoE–/– mice and model rabbits, whereas no obvious signals were detected in normal mice or rabbits. Compared with 18F-FDG, 18F-ASEM had more significant effect on the early monitoring of inflammation in carotid atherosclerotic plaques of ApoE–/– mice and model rabbits. 18F-ASEM had relatively more palpable effect on the imaging of abdominal aorta with atherosclerosis in rabbits. H&E and oil red staining identified the formation of atherosclerotic plaques in model animals, which provided pathological basis for the evaluation of imaging effects. Conclusion We first confirmed 18F-ASEM as radiotracer with good imaging properties for precise identification of atherosclerotic diseases.
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Affiliation(s)
- Tao Yang
- Department of Cardiovascular Surgery, Fu Wai Hospital, Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Dawei Wang
- Department of Nuclear Medicine, The Sixth Medical Center of PLA General Hospital, Beijing, China
| | - Xiangyi Chen
- Department of Nuclear Medicine, The First College of Clinical Medical Sciences, China Three Gorges University, Yichang, China.,Yichang Central People's Hospital, Yichang, China
| | - Yingkui Liang
- Department of Nuclear Medicine, The Sixth Medical Center of PLA General Hospital, Beijing, China
| | - Feng Guo
- Department of Nuclear Medicine, The Sixth Medical Center of PLA General Hospital, Beijing, China
| | - Chunxiao Wu
- Department of Cardiovascular Surgery, Fu Wai Hospital, Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Liujun Jia
- Department of Cardiovascular Surgery, Fu Wai Hospital, Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Zhihui Hou
- Department of Cardiovascular Surgery, Fu Wai Hospital, Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Wenliang Li
- School of Pharmacy, Jilin Medical University, Jilin City, China
| | - ZuoXiang He
- Department of Nuclear Medicine, Beijing Tsinghua Changgung Hospital, Tsinghua University, Beijing, China
| | - Xin Wang
- Department of Cardiovascular Surgery, Fu Wai Hospital, Cardiovascular Institute, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Wang X, Daley C, Gakhar V, Lange HS, Vardigan JD, Pearson M, Zhou X, Warren L, Miller CO, Belden M, Harvey AJ, Grishin AA, Coles CJ, O'Connor SM, Thomson F, Duffy JL, Bell IM, Uslaner JM. Pharmacological Characterization of the Novel and Selective α7 Nicotinic Acetylcholine Receptor-Positive Allosteric Modulator BNC375. J Pharmacol Exp Ther 2020; 373:311-324. [PMID: 32094294 DOI: 10.1124/jpet.119.263483] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 02/17/2020] [Indexed: 12/28/2022] Open
Abstract
Treatments for cognitive deficits associated with central nervous system (CNS) disorders such as Alzheimer disease and schizophrenia remain significant unmet medical needs that incur substantial pressure on the health care system. The α7 nicotinic acetylcholine receptor (nAChR) has garnered substantial attention as a target for cognitive deficits based on receptor localization, robust preclinical effects, genetics implicating its involvement in cognitive disorders, and encouraging, albeit mixed, clinical data with α7 nAChR orthosteric agonists. Importantly, previous orthosteric agonists at this receptor suffered from off-target activity, receptor desensitization, and an inverted U-shaped dose-effect curve in preclinical assays that limit their clinical utility. To overcome the challenges with orthosteric agonists, we have identified a novel selective α7 positive allosteric modulator (PAM), BNC375. This compound is selective over related receptors and potentiates acetylcholine-evoked α7 currents with only marginal effect on the receptor desensitization kinetics. In addition, BNC375 enhances long-term potentiation of electrically evoked synaptic responses in rat hippocampal slices and in vivo. Systemic administration of BNC375 reverses scopolamine-induced cognitive deficits in rat novel object recognition and rhesus monkey object retrieval detour (ORD) task over a wide range of exposures, showing no evidence of an inverted U-shaped dose-effect curve. The compound also improves performance in the ORD task in aged African green monkeys. Moreover, ex vivo 13C-NMR analysis indicates that BNC375 treatment can enhance neurotransmitter release in rat medial prefrontal cortex. These findings suggest that α7 nAChR PAMs have multiple advantages over orthosteric α7 nAChR agonists for the treatment of cognitive dysfunction associated with CNS diseases. SIGNIFICANCE STATEMENT: BNC375 is a novel and selective α7 nicotinic acetylcholine receptor (nAChR) positive allosteric modulator (PAM) that potentiates acetylcholine-evoked α7 currents in in vitro assays with little to no effect on the desensitization kinetics. In vivo, BNC375 demonstrated robust procognitive effects in multiple preclinical models across a wide exposure range. These results suggest that α7 nAChR PAMs have therapeutic potential in central nervous system diseases with cognitive impairments.
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Affiliation(s)
- Xiaohai Wang
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Christopher Daley
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Vanita Gakhar
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Henry S Lange
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Joshua D Vardigan
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Michelle Pearson
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Xiaoping Zhou
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Lee Warren
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Corin O Miller
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Michelle Belden
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Andrew J Harvey
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Anton A Grishin
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Carolyn J Coles
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Susan M O'Connor
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Fiona Thomson
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Joseph L Duffy
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Ian M Bell
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
| | - Jason M Uslaner
- Merck Research Laboratories, Merck & Co., Inc., Kenilworth, New Jersey (X.W., C.D., V.G., H.S.L., J.D.V., M.P., X.Z., L.W., C.O.M., M.B., F.T., J.L.D., I.M.B., J.M.U.) and Bionomics Limited, Thebarton, Australia (A.J.H., A.A.G., C.J.C., S.M.O.)
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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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Narayanaswami V, Dahl K, Bernard-Gauthier V, Josephson L, Cumming P, Vasdev N. Emerging PET Radiotracers and Targets for Imaging of Neuroinflammation in Neurodegenerative Diseases: Outlook Beyond TSPO. Mol Imaging 2018; 17:1536012118792317. [PMID: 30203712 PMCID: PMC6134492 DOI: 10.1177/1536012118792317] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 05/31/2018] [Accepted: 07/09/2018] [Indexed: 11/16/2022] Open
Abstract
The dynamic and multicellular processes of neuroinflammation are mediated by the nonneuronal cells of the central nervous system, which include astrocytes and the brain's resident macrophages, microglia. Although initiation of an inflammatory response may be beneficial in response to injury of the nervous system, chronic or maladaptive neuroinflammation can have harmful outcomes in many neurological diseases. An acute neuroinflammatory response is protective when activated neuroglia facilitate tissue repair by releasing anti-inflammatory cytokines and neurotrophic factors. On the other hand, chronic neuroglial activation is a major pathological mechanism in neurodegenerative diseases, likely contributing to neuronal dysfunction, injury, and disease progression. Therefore, the development of specific and sensitive probes for positron emission tomography (PET) studies of neuroinflammation is attracting immense scientific and clinical interest. An early phase of this research emphasized PET studies of the prototypical imaging biomarker of glial activation, translocator protein-18 kDa (TSPO), which presents difficulties for quantitation and lacks absolute cellular specificity. Many alternate molecular targets present themselves for PET imaging of neuroinflammation in vivo, including enzymes, intracellular signaling molecules as well as ionotropic, G-protein coupled, and immunoglobulin receptors. We now review the lead structures in radiotracer development for PET studies of neuroinflammation targets for neurodegenerative diseases extending beyond TSPO, including glycogen synthase kinase 3, monoamine oxidase-B, reactive oxygen species, imidazoline-2 binding sites, cyclooxygenase, the phospholipase A2/arachidonic acid pathway, sphingosine-1-phosphate receptor-1, cannabinoid-2 receptor, the chemokine receptor CX3CR1, purinergic receptors: P2X7 and P2Y12, the receptor for advanced glycation end products, Mer tyrosine kinase, and triggering receptor expressed on myeloid cells-1. We provide a brief overview of the cellular expression and function of these targets, noting their selectivity for astrocytes and/or microglia, and highlight the classes of PET radiotracers that have been investigated in early-stage preclinical or clinical research studies of neuroinflammation.
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Affiliation(s)
- Vidya Narayanaswami
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Kenneth Dahl
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Vadim Bernard-Gauthier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Lee Josephson
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Paul Cumming
- School of Psychology and Counselling and IHBI, Queensland University of Technology, Brisbane, Queensland, Australia
- QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Azrieli Centre for Neuro-Radiochemistry, Research Imaging Centre, Centre for Addiction and Mental Health & Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
- Department of Radiology, Harvard Medical School, Boston, MA, USA
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