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Salerno S, Viviano M, Baglini E, Poggetti V, Giorgini D, Castagnoli J, Barresi E, Castellano S, Da Settimo F, Taliani S. TSPO Radioligands for Neuroinflammation: An Overview. Molecules 2024; 29:4212. [PMID: 39275061 PMCID: PMC11397380 DOI: 10.3390/molecules29174212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/30/2024] [Accepted: 09/03/2024] [Indexed: 09/16/2024] Open
Abstract
The translocator protein (TSPO) is predominately localized on the outer mitochondrial membrane in steroidogenic cells. In the brain, TSPO expression, low under normal conditions, results upregulated in response to glial cell activation, that occurs in neuroinflammation. As a consequence, TSPO has been extensively studied as a biomarker of such conditions by means of TSPO-targeted radiotracers. Although [11C]-PK11195, the prototypical TSPO radioligand, is still widely used for in vivo studies, it is endowed with severe limitations, mainly low sensitivity and poor amenability to quantification. Consequently, several efforts have been focused on the design of new radiotracers for the in vivo imaging of TSPO. The present review will provide an outlook on the latest advances in TSPO radioligands for neuroinflammation imaging. The final goal is to pave the way for (radio)chemists in the future design and development of novel effective and sensitive radiopharmaceuticals targeting TSPO.
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Affiliation(s)
- Silvia Salerno
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Monica Viviano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Emma Baglini
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Valeria Poggetti
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Doralice Giorgini
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Jacopo Castagnoli
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Elisabetta Barresi
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Sabrina Castellano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Federico Da Settimo
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Sabrina Taliani
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
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2
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Kipp M. Astrocytes: Lessons Learned from the Cuprizone Model. Int J Mol Sci 2023; 24:16420. [PMID: 38003609 PMCID: PMC10671869 DOI: 10.3390/ijms242216420] [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: 10/12/2023] [Revised: 11/06/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
A diverse array of neurological and psychiatric disorders, including multiple sclerosis, Alzheimer's disease, and schizophrenia, exhibit distinct myelin abnormalities at both the molecular and histological levels. These aberrations are closely linked to dysfunction of oligodendrocytes and alterations in myelin structure, which may be pivotal factors contributing to the disconnection of brain regions and the resulting characteristic clinical impairments observed in these conditions. Astrocytes, which significantly outnumber neurons in the central nervous system by a five-to-one ratio, play indispensable roles in the development, maintenance, and overall well-being of neurons and oligodendrocytes. Consequently, they emerge as potential key players in the onset and progression of a myriad of neurological and psychiatric disorders. Furthermore, targeting astrocytes represents a promising avenue for therapeutic intervention in such disorders. To gain deeper insights into the functions of astrocytes in the context of myelin-related disorders, it is imperative to employ appropriate in vivo models that faithfully recapitulate specific aspects of complex human diseases in a reliable and reproducible manner. One such model is the cuprizone model, wherein metabolic dysfunction in oligodendrocytes initiates an early response involving microglia and astrocyte activation, culminating in multifocal demyelination. Remarkably, following the cessation of cuprizone intoxication, a spontaneous process of endogenous remyelination occurs. In this review article, we provide a historical overview of studies investigating the responses and putative functions of astrocytes in the cuprizone model. Following that, we list previously published works that illuminate various aspects of the biology and function of astrocytes in this multiple sclerosis model. Some of the studies are discussed in more detail in the context of astrocyte biology and pathology. Our objective is twofold: to provide an invaluable overview of this burgeoning field, and, more importantly, to inspire fellow researchers to embark on experimental investigations to elucidate the multifaceted functions of this pivotal glial cell subpopulation.
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Affiliation(s)
- Markus Kipp
- Institute of Anatomy, Rostock University Medical Center, 18057 Rostock, Germany
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3
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Viviano M, Barresi E, Siméon FG, Costa B, Taliani S, Da Settimo F, Pike VW, Castellano S. Essential Principles and Recent Progress in the Development of TSPO PET Ligands for Neuroinflammation Imaging. Curr Med Chem 2022; 29:4862-4890. [PMID: 35352645 PMCID: PMC10080361 DOI: 10.2174/0929867329666220329204054] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 12/21/2021] [Accepted: 01/25/2022] [Indexed: 11/22/2022]
Abstract
The translocator protein 18kDa (TSPO) is expressed in the outer mitochondrial membrane and is implicated in several functions, including cholesterol transport and steroidogenesis. Under normal physiological conditions, TSPO is present in very low concentrations in the human brain but is markedly upregulated in response to brain injury and inflammation. This upregulation is strongly associated with activated microglia. Therefore, TSPO is particularly suited for assessing active gliosis associated with brain lesions following injury or disease. For over three decades, TSPO has been studied as a biomarker. Numerous radioligands for positron emission tomography (PET) that target TSPO have been developed for imaging inflammatory progression in the brain. Although [11C]PK11195, the prototypical first-generation PET radioligand, is still widely used for in vivo studies, mainly now as its single more potent R-enantiomer, it has severe limitations, including low sensitivity and poor amenability to quantification. Second-generation radioligands are characterized by higher TSPO specific signals but suffer from other drawbacks, such as sensitivity to the TSPO single nucleotide polymorphism (SNP) rs6971. Therefore, their applications in human studies have the burden of needing to genotype subjects. Consequently, recent efforts are focused on developing improved radioligands that combine the optimal features of the second generation with the ability to overcome the differences in binding affinities across the population. This review presents essential principles in the design and development of TSPO PET ligands and discusses prominent examples among the main chemotypes.
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Affiliation(s)
- Monica Viviano
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy
| | | | - Fabrice G. Siméon
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Barbara Costa
- Department of Pharmacy, University of Pisa, 56126, Pisa, Italy
| | - Sabrina Taliani
- Department of Pharmacy, University of Pisa, 56126, Pisa, Italy
| | | | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sabrina Castellano
- Department of Pharmacy, University of Salerno, 84084 Fisciano (SA), Italy
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4
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Jewells VL, Yuan H, Merrill JR, Frank JE, Patel A, Cohen SM, Giglio B, Feinberg NN, Matsushima GK, Li Z. Assessment of 18F-PBR-111 in the Cuprizone Mouse Model of Multiple Sclerosis. Diagnostics (Basel) 2021; 11:diagnostics11050786. [PMID: 33925560 PMCID: PMC8145256 DOI: 10.3390/diagnostics11050786] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 12/28/2022] Open
Abstract
The study aims to assess site assessment of the performance of 18F-PBR-111 as a neuroinflammation marker in the cuprizone mouse model of multiple sclerosis (MS). 18F-PBR-111 PET imaging has not been well evaluated in multiple sclerosis applications both in preclinical and clinical research. This study will help establish the potential utility of 18F-PBR-111 PET in preclinical MS research and future animal and future human applications. 18F-PBR-111 PET/CT was conducted at 3.5 weeks (n = 7) and 5.0 weeks (n = 7) after cuprizone treatment or sham control (n = 3) in the mouse model. A subgroup of mice underwent autoradiography with cryosectioned brain tissue. T2 weighted MRI was performed to obtain the brain structural data of each mouse. 18F-PBR-111 uptake was assessed in multiple brain regions with PET and autoradiography images. The correlation between autoradiography and immunofluorescence staining of neuroinflammation (F4/80 and CD11b) was measured. Compared to control mice, significant 18F-PBR-111 uptake in the corpus callosum (p < 0.001), striatum (caudate and internal capsule, p < 0.001), and hippocampus (p < 0.05) was identified with PET images at both 3.5 weeks and 5.0 weeks, and validated with autoradiography. No significant uptake differences were detected between 3.5 weeks and 5.0 weeks assessing these regions as a whole, although there was a trend of increased uptake at 5.0 weeks compared to 3.5 weeks in the CC. High 18F-PBR-111 uptake regions correlated with microglial/macrophage locations by immunofluorescence staining with F4/80 and CD11b antibodies. 18F-PBR-111 uptake in anatomic locations correlated with activated microglia at histology in the cuprizone mouse model of MS suggests that 18F-PBR-111 has potential for in vivo evaluation of therapy response and potential for use in MS patients and animal studies.
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Affiliation(s)
- Valerie L. Jewells
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (H.Y.); (Z.L.)
- Correspondence: ; Fax: +1-(919)-966-1994
| | - Hong Yuan
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (H.Y.); (Z.L.)
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.R.M.); (J.E.F.); (B.G.)
| | - Joseph R. Merrill
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.R.M.); (J.E.F.); (B.G.)
| | - Jonathan E. Frank
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.R.M.); (J.E.F.); (B.G.)
| | - Akhil Patel
- UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (A.P.); (G.K.M.)
| | - Stephanie M. Cohen
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (S.M.C.); (N.N.F.)
| | - Ben Giglio
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.R.M.); (J.E.F.); (B.G.)
| | - Nana Nikolaishvili Feinberg
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (S.M.C.); (N.N.F.)
| | - Glenn K. Matsushima
- UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (A.P.); (G.K.M.)
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Integrative Program Biological and Genome Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Zibo Li
- Department of Radiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (H.Y.); (Z.L.)
- Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; (J.R.M.); (J.E.F.); (B.G.)
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5
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Behrangi N, Lorenz P, Kipp M. Oligodendrocyte Lineage Marker Expression in eGFP-GFAP Transgenic Mice. J Mol Neurosci 2020; 71:2237-2248. [PMID: 33346907 PMCID: PMC8585802 DOI: 10.1007/s12031-020-01771-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/02/2020] [Indexed: 12/21/2022]
Abstract
Oligodendrocytes, the myelinating cells of the central nervous system, orchestrate several key cellular functions in the brain and spinal cord, including axon insulation, energy transfer to neurons, and, eventually, modulation of immune responses. There is growing interest for obtaining reliable markers that can specifically label oligodendroglia and their progeny. In many studies, anti-CC1 antibodies, presumably recognizing the protein adenomatous polyposis coli (APC), are used to label mature, myelinating oligodendrocytes. However, it has been discussed whether anti-CC1 antibodies could recognize as well, under pathological conditions, other cell populations, particularly astrocytes. In this study, we used transgenic mice in which astrocytes are labeled by the enhanced green fluorescent protein (eGFP) under the control of the human glial fibrillary acidic protein (GFAP) promoter. By detailed co-localization studies we were able to demonstrate that a significant proportion of eGFP-expressing cells co-express markers of the oligodendrocyte lineage, such as the transcription factor Oligodendrocyte Transcription Factor 2 (OLIG2); the NG2 proteoglycan, also known as chrondroitin sulfate proteoglycan 4 (CSPG4); or APC. The current finding that the GFAP promoter drives transgene expression in cells of the oligodendrocyte lineage should be considered when interpreting results from co-localization studies.
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Affiliation(s)
- Newshan Behrangi
- Institute of Anatomy, Rostock University Medical Center, 18057, Rostock, Germany.,Department of Anatomy II, Ludwig-Maximilians-University of Munich, 80336, Munich, Germany
| | - Peter Lorenz
- Institute of Immunology, Rostock University Medical Center, 18057, Rostock, Germany
| | - Markus Kipp
- Institute of Anatomy, Rostock University Medical Center, 18057, Rostock, Germany. .,Center for Transdisciplinary Neurosciences Rostock (CTNR), Rostock University Medical Center, Gelsheimer Strasse 20, 18147, Rostock, Germany.
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6
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Nutma E, Stephenson JA, Gorter RP, de Bruin J, Boucherie DM, Donat CK, Breur M, van der Valk P, Matthews PM, Owen DR, Amor S. A quantitative neuropathological assessment of translocator protein expression in multiple sclerosis. Brain 2020; 142:3440-3455. [PMID: 31578541 PMCID: PMC6821167 DOI: 10.1093/brain/awz287] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 06/11/2019] [Accepted: 07/25/2019] [Indexed: 01/09/2023] Open
Abstract
The 18 kDa translocator protein (TSPO) is increasingly used to study brain and spinal cord inflammation in degenerative diseases of the CNS such as multiple sclerosis. The enhanced TSPO PET signal that arises during disease is widely considered to reflect activated pathogenic microglia, although quantitative neuropathological data to support this interpretation have not been available. With the increasing interest in the role of chronic microglial activation in multiple sclerosis, characterising the cellular neuropathology associated with TSPO expression is of clear importance for understanding the cellular and pathological processes on which TSPO PET imaging is reporting. Here we have studied the cellular expression of TSPO and specific binding of two TSPO targeting radioligands (3H-PK11195 and 3H-PBR28) in tissue sections from 42 multiple sclerosis cases and 12 age-matched controls. Markers of homeostatic and reactive microglia, astrocytes, and lymphocytes were used to investigate the phenotypes of cells expressing TSPO. There was an approximate 20-fold increase in cells double positive for TSPO and HLA-DR in active lesions and in the rim of chronic active lesion, relative to normal appearing white matter. TSPO was uniformly expressed across myeloid cells irrespective of their phenotype, rather than being preferentially associated with pro-inflammatory microglia or macrophages. TSPO+ astrocytes were increased up to 7-fold compared to normal-appearing white matter across all lesion subtypes and accounted for 25% of the TSPO+ cells in these lesions. To relate TSPO protein expression to ligand binding, specific binding of the TSPO ligands 3H-PK11195 and 3H-PBR28 was determined in the same lesions. TSPO radioligand binding was increased up to seven times for 3H-PBR28 and up to two times for 3H-PK11195 in active lesions and the centre of chronic active lesions and a strong correlation was found between the radioligand binding signal for both tracers and the number of TSPO+ cells across all of the tissues examined. In summary, in multiple sclerosis, TSPO expression arises from microglia of different phenotypes, rather than being restricted to microglia which express classical pro-inflammatory markers. While the majority of cells expressing TSPO in active lesions or chronic active rims are microglia/macrophages, our findings also emphasize the significant contribution of activated astrocytes, as well as smaller contributions from endothelial cells. These observations establish a quantitative framework for interpretation of TSPO in multiple sclerosis and highlight the need for neuropathological characterization of TSPO expression for the interpretation of TSPO PET in other neurodegenerative disorders.
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Affiliation(s)
- Erik Nutma
- Department of Pathology, Amsterdam UMC, Location VUmc, The Netherlands
| | - Jodie A Stephenson
- Department of Pathology, Amsterdam UMC, Location VUmc, The Netherlands.,Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, UK
| | - Rianne P Gorter
- Department of Pathology, Amsterdam UMC, Location VUmc, The Netherlands
| | - Joy de Bruin
- Department of Pathology, Amsterdam UMC, Location VUmc, The Netherlands
| | | | | | - Marjolein Breur
- Department of Pathology, Amsterdam UMC, Location VUmc, The Netherlands
| | - Paul van der Valk
- Department of Pathology, Amsterdam UMC, Location VUmc, The Netherlands
| | - Paul M Matthews
- Department of Brain Sciences, Imperial College London, UK.,UK Dementia Research Institute, Imperial College London, UK
| | - David R Owen
- Department of Brain Sciences, Imperial College London, UK
| | - Sandra Amor
- Department of Pathology, Amsterdam UMC, Location VUmc, The Netherlands.,Centre for Neuroscience and Trauma, Blizard Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, UK
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7
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Laquinimod ameliorates secondary brain inflammation. Neurobiol Dis 2019; 134:104675. [PMID: 31731041 DOI: 10.1016/j.nbd.2019.104675] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/21/2019] [Accepted: 11/11/2019] [Indexed: 02/07/2023] Open
Abstract
Accumulating evidence suggests that a degenerative processes within the brain can trigger the formation of new, focal inflammatory lesions in Multiple Sclerosis (MS). Here, we used a novel pre-clinical MS animal model to test whether the amelioration of degenerative brain events reduces the secondary recruitment of peripheral immune cells and, in consequence, inflammatory lesion development. Neural degeneration was induced by a 3 weeks cuprizone intoxication period. To mitigate the cuprizone-induced pathology, animals were treated with Laquinimod (25 mg/kg) during the cuprizone-intoxication period. At the beginning of week 6, encephalitogenic T cell development in peripheral lymphoid organs was induced by the immunization with myelin oligodendrocyte glycoprotein 35-55 peptide (i.e., Cup/EAE). Demyelination, axonal injury and reactive gliosis were determined by immunohistochemistry. Positron emission tomography (PET) imaging was performed to analyze glia activation in vivo. Vehicle-treated cuprizone mice displayed extensive callosal demyelination, glia activation and enhanced TSPO-ligand binding. This cuprizone-induced pathology was profoundly ameliorated in mice treated with Laquinimod. In vehicle-treated Cup/EAE mice, the cuprizone-induced pathology triggered massive peripheral immune cell recruitment into the forebrain, evidenced by multifocal perivascular inflammation, glia activation and neuro-axonal injury. While anti myelin oligodendrocyte glycoprotein 35-55 peptide immune responses were comparable in vehicle- and Laquinimod-treated Cup/EAE mice, the cuprizone-triggered immune cell recruitment was ameliorated by the Laquinimod treatment. This study clearly illustrates that amelioration of a primary brain-intrinsic degenerative process secondary halts peripheral immune cell recruitment and, in consequence, inflammatory lesion development. These findings have important consequences for the interpretation of the results of clinical studies.
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8
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Zinnhardt B, Belloy M, Fricke IB, Orije J, Guglielmetti C, Hermann S, Wagner S, Schäfers M, Van der Linden A, Jacobs AH. Molecular Imaging of Immune Cell Dynamics During De- and Remyelination in the Cuprizone Model of Multiple Sclerosis by [ 18F]DPA-714 PET and MRI. Theranostics 2019; 9:1523-1537. [PMID: 31037121 PMCID: PMC6485187 DOI: 10.7150/thno.32461] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 01/07/2019] [Indexed: 12/27/2022] Open
Abstract
Background: Activation and dysregulation of innate, adaptive and resident immune cells in response to damage determine the pathophysiology of demyelinating disorders. Among the plethora of involved cells, microglia/macrophages and astrocytes play an important role in the pathogenesis of demyelinating disorders. The in-depth investigation of the spatio-temporal profile of these cell types in vivo may inform about the exact disease state and localization as well as may allow to monitor therapeutic modulation of the components of the neuroinflammatory response during the course of multiple sclerosis (MS). In this study, we aimed to non-invasively decipher the degree and temporal profile of neuroinflammation (TSPO - [18F]DPA-714 PET) in relation to selected magnetic resonance imaging (MRI) parameters (T2 maps) in the cuprizone (CPZ)-induced model of demyelination. Methods: C57Bl6 (n=30) mice were fed with a standard chow mixed with 0.2% (w/w) CPZ for 4 (n=10; demyelination) and 6 weeks (n=10; spontaneous remyelination). The degree of neuroinflammation at de- and remyelination was assessed by [18F]DPA-714 PET, multi-echo T2 MRI, autoradiography and immunohistochemistry. Results: CPZ-induced brain alterations were confirmed by increase of T2 relaxation times in both white and grey matter after 3 and 5 weeks of CPZ. Peak [18F]DPA-714 was found in the corpus callosum (CC, white matter), the hippocampus (HC, grey matter) and thalamus (grey matter) after 4 weeks of CPZ treatment and declined after 6 weeks of CPZ. Ex vivo autoradiography and dedicated immunofluorescence showed demyelination/remyelination with corresponding increased/decreased TSPO levels in the CC and hippocampus, confirming the spatial distribution of [18F]DPA-714 in vivo. The expression of TSPO microglia and astrocytes is time-dependent in this model. Microglia predominantly express TSPO at demyelination, while the majority of astrocytes express TSPO during remyelination. The combination of PET- and MRI-based imaging biomarkers demonstrated the regional and temporal development of the CPZ model-associated neuroinflammatory response in grey and white matter regions. Conclusions: The combination of [18F]DPA-714 PET and T2 mapping may allow to further elucidate the regional and temporal profile of inflammatory signals depending on the myelination status, although the underlying inflammatory microenvironment changes. A combination of the described imaging biomarkers may facilitate the development of patient-tailored strategies for immunomodulatory and neuro-restorative therapies in MS.
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Affiliation(s)
- Bastian Zinnhardt
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
- Imaging Neuroinflammation in Neurodegenerative Diseases (INMIND) EU FP7 consortium
- PET Imaging in Drug Design and Development (PET3D)
- Department of Nuclear Medicine, Universitätsklinikum Münster, Münster, Germany
| | - Michaël Belloy
- Bio-Imaging Laboratory, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Imaging Neuroinflammation in Neurodegenerative Diseases (INMIND) EU FP7 consortium
| | - Inga B. Fricke
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
- Imaging Neuroinflammation in Neurodegenerative Diseases (INMIND) EU FP7 consortium
- Current affiliation: TECHNA Institute for the Advancement of Technology for Health, University Health Network; Institute of Biomaterials and Biomedical Engineering, University of Toronto; both Toronto, Ontario, Canada
| | - Jasmien Orije
- Bio-Imaging Laboratory, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Imaging Neuroinflammation in Neurodegenerative Diseases (INMIND) EU FP7 consortium
| | - Caroline Guglielmetti
- Bio-Imaging Laboratory, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Imaging Neuroinflammation in Neurodegenerative Diseases (INMIND) EU FP7 consortium
| | - Sven Hermann
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
| | - Stefan Wagner
- Department of Nuclear Medicine, Universitätsklinikum Münster, Münster, Germany
| | - Michael Schäfers
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
- Department of Nuclear Medicine, Universitätsklinikum Münster, Münster, Germany
| | - Annemie Van der Linden
- Bio-Imaging Laboratory, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- Imaging Neuroinflammation in Neurodegenerative Diseases (INMIND) EU FP7 consortium
| | - Andreas H. Jacobs
- European Institute for Molecular Imaging (EIMI), University of Münster, Münster, Germany
- Imaging Neuroinflammation in Neurodegenerative Diseases (INMIND) EU FP7 consortium
- PET Imaging in Drug Design and Development (PET3D)
- Department of Geriatrics, Johanniter Hospital, Evangelische Kliniken, Bonn, Germany
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9
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Nack A, Brendel M, Nedelcu J, Daerr M, Nyamoya S, Beyer C, Focke C, Deussing M, Hoornaert C, Ponsaerts P, Schmitz C, Bartenstein P, Rominger A, Kipp M. Expression of Translocator Protein and [18F]-GE180 Ligand Uptake in Multiple Sclerosis Animal Models. Cells 2019; 8:cells8020094. [PMID: 30696113 PMCID: PMC6406715 DOI: 10.3390/cells8020094] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/16/2019] [Accepted: 01/23/2019] [Indexed: 12/19/2022] Open
Abstract
Positron emission tomography (PET) ligands targeting the translocator protein (TSPO) represent promising tools to visualize neuroinflammation in multiple sclerosis (MS). Although it is known that TSPO is expressed in the outer mitochondria membrane, its cellular localization in the central nervous system under physiological and pathological conditions is not entirely clear. The purpose of this study was to assess the feasibility of utilizing PET imaging with the TSPO tracer, [18F]-GE180, to detect histopathological changes during experimental demyelination, and to determine which cell types express TSPO. C57BL/6 mice were fed with cuprizone for up to 5 weeks to induce demyelination. Groups of mice were investigated by [18F]-GE180 PET imaging at week 5. Recruitment of peripheral immune cells was triggered by combining cuprizone intoxication with MOG35–55 immunization (i.e., Cup/EAE). Immunofluorescence double-labelling and transgene mice were used to determine which cell types express TSPO. [18F]-GE180-PET reliably detected the cuprizone-induced pathology in various white and grey matter regions, including the corpus callosum, cortex, hippocampus, thalamus and caudoputamen. Cuprizone-induced demyelination was paralleled by an increase in TSPO expression, glia activation and axonal injury. Most of the microglia and around one-third of the astrocytes expressed TSPO. TSPO expression induction was more severe in the white matter corpus callosum compared to the grey matter cortex. Although mitochondria accumulate at sites of focal axonal injury, these mitochondria do not express TSPO. In Cup/EAE mice, both microglia and recruited monocytes contribute to the TSPO expressing cell populations. These findings support the notion that TSPO is a valuable marker for the in vivo visualization and quantification of neuropathological changes in the MS brain. The pathological substrate of an increase in TSPO-ligand binding might be diverse including microglia activation, peripheral monocyte recruitment, or astrocytosis, but not axonal injury.
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MESH Headings
- Animals
- Astrocytes/pathology
- Astrocytes/ultrastructure
- Axons/metabolism
- Axons/ultrastructure
- Biomarkers/metabolism
- Carbazoles/metabolism
- Cuprizone
- Demyelinating Diseases/diagnostic imaging
- Demyelinating Diseases/pathology
- Disease Models, Animal
- Encephalomyelitis, Autoimmune, Experimental/diagnostic imaging
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Female
- Inflammation/pathology
- Ligands
- Mice, Inbred C57BL
- Mitochondria/metabolism
- Mitochondria/ultrastructure
- Monocytes/metabolism
- Multiple Sclerosis/diagnostic imaging
- Neuroglia/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, GABA/genetics
- Receptors, GABA/metabolism
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Affiliation(s)
- Anne Nack
- Department of Anatomy II, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany.
- Department of Anatomy, 39071 Rostock University Medical Center, Rostock, Germany.
| | - Matthias Brendel
- Department of Nuclear Medicine, University Hospital, LMU Munich, 80336 Munich, Germany.
| | - Julia Nedelcu
- Department of Anatomy II, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany.
- Department of Anatomy, 39071 Rostock University Medical Center, Rostock, Germany.
| | - Markus Daerr
- Department of Anatomy II, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany.
- Department of Anatomy, 39071 Rostock University Medical Center, Rostock, Germany.
| | - Stella Nyamoya
- Department of Anatomy II, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany.
- Institute of Neuroanatomy, RWTH Aachen University, 52074 Aachen, Germany.
- Department of Anatomy, 39071 Rostock University Medical Center, Rostock, Germany.
| | - Cordian Beyer
- Institute of Neuroanatomy, RWTH Aachen University, 52074 Aachen, Germany.
| | - Carola Focke
- Department of Nuclear Medicine, University Hospital, LMU Munich, 80336 Munich, Germany.
| | - Maximilian Deussing
- Department of Nuclear Medicine, University Hospital, LMU Munich, 80336 Munich, Germany.
| | - Chloé Hoornaert
- Laboratory of Experimental Hematology, University of Antwerp, Antwerp, Belgium.
- Vaccine and Infectious Disease Institute (Vaxinfectio), University of Antwerp, Antwerp, Belgium.
| | - Peter Ponsaerts
- Laboratory of Experimental Hematology, University of Antwerp, Antwerp, Belgium.
- Vaccine and Infectious Disease Institute (Vaxinfectio), University of Antwerp, Antwerp, Belgium.
| | - Christoph Schmitz
- Department of Anatomy II, Ludwig-Maximilians-University of Munich, 80336 Munich, Germany.
| | - Peter Bartenstein
- Department of Nuclear Medicine, University Hospital, LMU Munich, 80336 Munich, Germany.
| | - Axel Rominger
- Department of Nuclear Medicine, University Hospital, LMU Munich, 80336 Munich, Germany.
- Department of Nuclear Medicine, Inselspital, University Hospital Bern, Bern, Switzerland.
| | - Markus Kipp
- Department of Anatomy, 39071 Rostock University Medical Center, Rostock, Germany.
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10
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Tournier BB, Tsartsalis S, Rigaud D, Fossey C, Cailly T, Fabis F, Pham T, Grégoire MC, Kövari E, Moulin-Sallanon M, Savioz A, Millet P. TSPO and amyloid deposits in sub-regions of the hippocampus in the 3xTgAD mouse model of Alzheimer’s disease. Neurobiol Dis 2019; 121:95-105. [DOI: 10.1016/j.nbd.2018.09.022] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 09/03/2018] [Accepted: 09/23/2018] [Indexed: 11/16/2022] Open
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11
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TSPO in diverse CNS pathologies and psychiatric disease: A critical review and a way forward. Pharmacol Ther 2018; 194:44-58. [PMID: 30189290 DOI: 10.1016/j.pharmthera.2018.09.003] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The use of Translocator Protein 18 kDa (TSPO) as a clinical neuroimaging biomarker of brain injury and neuroinflammation has increased exponentially in the last decade. There has been a furious pace in the development of new radiotracers for TSPO positron emission tomography (PET) imaging and its use has now been extensively described in many neurological and mental disorders. This fast pace of research and the ever-increasing number of new laboratories entering the field often times lack an appreciation of the historical perspective of the field and introduce dogmatic, but unproven facts, related to the underlying neurobiology of the TSPO response to brain injury and neuroinflammation. Paradoxically, while in neurodegenerative disorders and in all types of CNS pathologies brain TSPO levels increase, a new observation in psychiatric disorders such as schizophrenia is decreased brain levels of TSPO measured by PET. The neurobiological bases for this new finding is currently not known, but rigorous experimental design using multiple experimental approaches and careful interpretation of results is critically important to provide the methodological and/or biological underpinnings to this new observation. This review provides a perspective of the early history of validating TSPO as a biomarker of brain injury and neuroinflammation and a critical analysis of controversial topics in the literature related to the cellular sources of the TSPO response. The latter is important in order to provide the correct interpretation of PET studies in neurodegenerative and psychiatric disorders. Furthermore, this review proposes some yet to be explored explanations to new findings in psychiatric disorders and new approaches to quantitatively assess the glial sources of the TSPO response in order to move the field forward.
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12
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Tsartsalis S, Tournier BB, Habiby S, Ben Hamadi M, Barca C, Ginovart N, Millet P. Dual-radiotracer translational SPECT neuroimaging. Comparison of three methods for the simultaneous brain imaging of D2/3 and 5-HT2A receptors. Neuroimage 2018; 176:528-540. [DOI: 10.1016/j.neuroimage.2018.04.063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 03/11/2018] [Accepted: 04/27/2018] [Indexed: 12/27/2022] Open
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13
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Cumming P, Burgher B, Patkar O, Breakspear M, Vasdev N, Thomas P, Liu GJ, Banati R. Sifting through the surfeit of neuroinflammation tracers. J Cereb Blood Flow Metab 2018; 38:204-224. [PMID: 29256293 PMCID: PMC5951023 DOI: 10.1177/0271678x17748786] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/26/2017] [Accepted: 11/09/2017] [Indexed: 01/09/2023]
Abstract
The first phase of molecular brain imaging of microglial activation in neuroinflammatory conditions began some 20 years ago with the introduction of [11C]-( R)-PK11195, the prototype isoquinoline ligand for translocator protein (18 kDa) (TSPO). Investigations by positron emission tomography (PET) revealed microgliosis in numerous brain diseases, despite the rather low specific binding signal imparted by [11C]-( R)-PK11195. There has since been enormous expansion of the repertoire of TSPO tracers, many with higher specific binding, albeit complicated by allelic dependence of the affinity. However, the specificity of TSPO PET for revealing microglial activation not been fully established, and it has been difficult to judge the relative merits of the competing tracers and analysis methods with respect to their sensitivity for detecting microglial activation. We therefore present a systematic comparison of 13 TSPO PET and single photon computed tomography (SPECT) tracers belonging to five structural classes, each of which has been investigated by compartmental analysis in healthy human brain relative to a metabolite-corrected arterial input. We emphasize the need to establish the non-displaceable binding component for each ligand and conclude with five recommendations for a standard approach to define the cellular distribution of TSPO signals, and to characterize the properties of candidate TSPO tracers.
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Affiliation(s)
- Paul Cumming
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Bjorn Burgher
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Omkar Patkar
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Michael Breakspear
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Paul Thomas
- Herston Imaging Research Facility, Faculty of Medicine, University of Queensland Centre for Clinical Research, Herston, Australia
| | - Guo-Jun Liu
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
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14
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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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15
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Changes in Binding of [(123)I]CLINDE, a High-Affinity Translocator Protein 18 kDa (TSPO) Selective Radioligand in a Rat Model of Traumatic Brain Injury. Neuromolecular Med 2016; 18:158-69. [PMID: 26969181 DOI: 10.1007/s12017-016-8385-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 02/02/2016] [Indexed: 01/01/2023]
Abstract
After traumatic brain injury (TBI), secondary injuries develop, including neuroinflammatory processes that contribute to long-lasting impairments. These secondary injuries represent potential targets for treatment and diagnostics. The translocator protein 18 kDa (TSPO) is expressed in activated microglia cells and upregulated in response to brain injury and therefore a potential biomarker of the neuroinflammatory processes. Second-generation radioligands of TSPO, such as [(123)I]CLINDE, have a higher signal-to-noise ratio as the prototype ligand PK11195. [(123)I]CLINDE has been employed in human studies using single-photon emission computed tomography to image the neuroinflammatory response after stroke. In this study, we used the same tracer in a rat model of TBI to determine changes in TSPO expression. Adult Sprague-Dawley rats were subjected to moderate controlled cortical impact injury and sacrificed at 6, 24, 72 h and 28 days post surgery. TSPO expression was assessed in brain sections employing [(123)I]CLINDE in vitro autoradiography. From 24 h to 28 days post surgery, injured animals exhibited a marked and time-dependent increase in [(123)I]CLINDE binding in the ipsilateral motor, somatosensory and parietal cortex, as well as in the hippocampus and thalamus. Interestingly, binding was also significantly elevated in the contralateral M1 motor cortex following TBI. Craniotomy without TBI caused a less marked increase in [(123)I]CLINDE binding, restricted to the ipsilateral hemisphere. Radioligand binding was consistent with an increase in TSPO mRNA expression and CD11b immunoreactivity at the contusion site. This study demonstrates the applicability of [(123)I]CLINDE for detailed regional and quantitative assessment of glial activity in experimental models of TBI.
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16
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Radiopharmaceuticals for PET imaging of neuroinflammation. MEDECINE NUCLEAIRE-IMAGERIE FONCTIONNELLE ET METABOLIQUE 2016. [DOI: 10.1016/j.mednuc.2016.01.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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17
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Insight into the Molecular Imaging of Alzheimer's Disease. Int J Biomed Imaging 2016; 2016:7462014. [PMID: 26880871 PMCID: PMC4736963 DOI: 10.1155/2016/7462014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 12/16/2015] [Indexed: 12/13/2022] Open
Abstract
Alzheimer's disease is a complex neurodegenerative disease affecting millions of individuals worldwide. Earlier it was diagnosed only via clinical assessments and confirmed by postmortem brain histopathology. The development of validated biomarkers for Alzheimer's disease has given impetus to improve diagnostics and accelerate the development of new therapies. Functional imaging like positron emission tomography (PET), single photon emission computed tomography (SPECT), functional magnetic resonance imaging (fMRI), and proton magnetic resonance spectroscopy provides a means of detecting and characterising the regional changes in brain blood flow, metabolism, and receptor binding sites that are associated with Alzheimer's disease. Multimodal neuroimaging techniques have indicated changes in brain structure and metabolic activity, and an array of neurochemical variations that are associated with neurodegenerative diseases. Radiotracer-based PET and SPECT potentially provide sensitive, accurate methods for the early detection of disease. This paper presents a review of neuroimaging modalities like PET, SPECT, and selected imaging biomarkers/tracers used for the early diagnosis of AD. Neuroimaging with such biomarkers and tracers could achieve a much higher diagnostic accuracy for AD and related disorders in the future.
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18
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Lee DE, Yue X, Ibrahim WG, Lentz MR, Peterson KL, Jagoda EM, Kassiou M, Maric D, Reid WC, Hammoud DA. Lack of neuroinflammation in the HIV-1 transgenic rat: an [(18)F]-DPA714 PET imaging study. J Neuroinflammation 2015; 12:171. [PMID: 26377670 PMCID: PMC4574011 DOI: 10.1186/s12974-015-0390-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 09/02/2015] [Indexed: 11/29/2022] Open
Abstract
Background HIV-associated neuroinflammation is believed to be a major contributing factor in the development of HIV-associated neurocognitive disorders (HAND). In this study, we used micropositron emission tomography (PET) imaging to quantify neuroinflammation in HIV-1 transgenic rat (Tg), a small animal model of HIV, known to develop neurological and behavioral problems. Methods Dynamic [18F]DPA-714 PET imaging was performed in Tg and age-matched wild-type (WT) rats in three age groups: 3-, 9-, and 16-month-old animals. As a positive control for neuroinflammation, we performed unilateral intrastriatal injection of quinolinic acid (QA) in a separate group of WT rats. To confirm our findings, we performed multiplex immunofluorescent staining for Iba1 and we measured cytokine/chemokine levels in brain lysates of Tg and WT rats at different ages. Results [18F]DPA-714 uptake in HIV-1 Tg rat brains was generally higher than in age-matched WT rats but this was not statistically significant in any age group. [18F]DPA-714 uptake in the QA-lesioned rats was significantly higher ipsilateral to the lesion compared to contralateral side indicating neuroinflammatory changes. Iba1 immunofluorescence showed no significant differences in microglial activation between the Tg and WT rats, while the QA-lesioned rats showed significant activation. Finally, cytokine/chemokine levels in brain lysates of the Tg rats and WT rats were not significantly different. Conclusion Microglial activation might not be the primary mechanism for neuropathology in the HIV-1 Tg rats. Although [18F]DPA-714 is a good biomarker of neuroinflammation, it cannot be reliably used as an in vivo biomarker of neurodegeneration in the HIV-1 Tg rat. Electronic supplementary material The online version of this article (doi:10.1186/s12974-015-0390-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dianne E Lee
- Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health/Clinical Center, 10 Center Drive, Room 1C368, Bethesda, MD, 20814-9692, USA
| | - Xuyi Yue
- Department of Radiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Wael G Ibrahim
- Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health/Clinical Center, 10 Center Drive, Room 1C368, Bethesda, MD, 20814-9692, USA
| | - Margaret R Lentz
- Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health/Clinical Center, 10 Center Drive, Room 1C368, Bethesda, MD, 20814-9692, USA
| | - Kristin L Peterson
- Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health/Clinical Center, 10 Center Drive, Room 1C368, Bethesda, MD, 20814-9692, USA
| | - Elaine M Jagoda
- Molecular Imaging Program (MIP), National Cancer Institute (NCI), Bethesda, MD, USA
| | - Michael Kassiou
- Chemistry Department, The University of Sydney, Sydney, Australia
| | - Dragan Maric
- Division of Intermural Research (DIR), National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, USA
| | - William C Reid
- Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health/Clinical Center, 10 Center Drive, Room 1C368, Bethesda, MD, 20814-9692, USA
| | - Dima A Hammoud
- Center for Infectious Disease Imaging (CIDI), Radiology and Imaging Sciences, National Institutes of Health/Clinical Center, 10 Center Drive, Room 1C368, Bethesda, MD, 20814-9692, USA.
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19
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Praet J, Guglielmetti C, Berneman Z, Van der Linden A, Ponsaerts P. Cellular and molecular neuropathology of the cuprizone mouse model: clinical relevance for multiple sclerosis. Neurosci Biobehav Rev 2015; 47:485-505. [PMID: 25445182 DOI: 10.1016/j.neubiorev.2014.10.004] [Citation(s) in RCA: 281] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/18/2014] [Accepted: 10/01/2014] [Indexed: 01/30/2023]
Abstract
The cuprizone mouse model allows the investigation of the complex molecular mechanisms behind nonautoimmune-mediated demyelination and spontaneous remyelination. While it is generally accepted that oligodendrocytes are specifically vulnerable to cuprizone intoxication due to their high metabolic demands, a comprehensive overview of the etiology of cuprizone-induced pathology is still missing to date. In this review we extensively describe the physico-chemical mode of action of cuprizone and discuss the molecular and enzymatic mechanisms by which cuprizone induces metabolic stress, oligodendrocyte apoptosis, myelin degeneration and eventually axonal and neuronal pathology. In addition, we describe the dual effector function of the immune system which tightly controls demyelination by effective induction of oligodendrocyte apoptosis, but in contrast also paves the way for fast and efficient remyelination by the secretion of neurotrophic factors and the clearance of cellular and myelinic debris. Finally, we discuss the many clinical symptoms that can be observed following cuprizone treatment, and how these strengthened the cuprizone model as a useful tool to study human multiple sclerosis, schizophrenia and epilepsy.
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20
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Mattner F, Quinlivan M, Greguric I, Pham T, Liu X, Jackson T, Berghofer P, Fookes CJR, Dikic B, Gregoire MC, Dolle F, Katsifis A. Radiosynthesis, In Vivo Biological Evaluation, and Imaging of Brain Lesions with [123I]-CLINME, a New SPECT Tracer for the Translocator Protein. DISEASE MARKERS 2015; 2015:729698. [PMID: 26199457 PMCID: PMC4496498 DOI: 10.1155/2015/729698] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Accepted: 06/10/2015] [Indexed: 11/17/2022]
Abstract
The high affinity translocator protein (TSPO) ligand 6-chloro-2-(4'-iodophenyl)-3-(N,N-methylethyl)imidazo[1,2-a]pyridine-3-acetamide (CLINME) was radiolabelled with iodine-123 and assessed for its sensitivity for the TSPO in rodents. Moreover neuroinflammatory changes on a unilateral excitotoxic lesion rat model were detected using SPECT imaging. [(123)I]-CLINME was prepared in 70-80% radiochemical yield. The uptake of [(123)I]-CLINME was evaluated in rats by biodistribution, competition, and metabolite studies. The unilateral excitotoxic lesion was performed by injection of α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid unilaterally into the striatum. The striatum lesion was confirmed and correlated with TSPO expression in astrocytes and activated microglia by immunohistochemistry and autoradiography. In vivo studies with [(123)I]-CLINME indicated a biodistribution pattern consistent with TPSO distribution and the competition studies with PK11195 and Ro 5-4864 showed that [(123)I]-CLINME is selective for this site. The metabolite study showed that the extractable radioactivity was unchanged [(123)I]-CLINME in organs which expresses TSPO. SPECT/CT imaging on the unilateral excitotoxic lesion indicated that the mean ratio uptake in striatum (lesion:nonlesion) was 2.2. Moreover, TSPO changes observed by SPECT imaging were confirmed by immunofluorescence, immunochemistry, and autoradiography. These results indicated that [(123)I]-CLINME is a promising candidate for the quantification and visualization of TPSO expression in activated astroglia using SPECT.
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Affiliation(s)
- F. Mattner
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
- Department of Molecular Imaging, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
| | - M. Quinlivan
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - I. Greguric
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - T. Pham
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - X. Liu
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - T. Jackson
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - P. Berghofer
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - C. J. R. Fookes
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - B. Dikic
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - M.-C. Gregoire
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
| | - F. Dolle
- CEA, DSV/I2BM, Service Hospitalier Frédéric Joliot, 4 Place du Général Leclerc, 91401 Orsay, France
| | - A. Katsifis
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia
- Department of Molecular Imaging, Royal Prince Alfred Hospital, Camperdown, NSW 2050, Australia
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21
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Tsartsalis S, Dumas N, Tournier BB, Pham T, Moulin-Sallanon M, Grégoire MC, Charnay Y, Millet P. SPECT imaging of glioma with radioiodinated CLINDE: evidence from a mouse GL26 glioma model. EJNMMI Res 2015; 5:9. [PMID: 25853015 PMCID: PMC4385259 DOI: 10.1186/s13550-015-0092-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 02/24/2015] [Indexed: 12/30/2022] Open
Abstract
Background Recent research has demonstrated the potential of 18-kDa translocator protein (TSPO) to serve as a target for nuclear imaging of gliomas. The aim of this study was to evaluate SPECT imaging of GL26 mouse glioma using radioiodinated CLINDE, a TSPO-specific tracer. Methods GL26 cells, previously transfected with an enhanced green fluorescent protein (EGFP)-expressing lentivirus, were stereotactically implanted in the striatum of C57/Bl6 mice. At 4 weeks post-injection, dynamic SPECT scans with [123I]CLINDE were performed. A displacement study assessed specificity of tracer binding. SPECT images were compared to results of autoradiography, fluorescence microscopy, in situ nucleic acid hybridization, histology, and immunohistochemistry. Western blotting was performed to verify TSPO production by the tumor. Results Specific uptake of tracer by the tumor is observed with a high signal-to-noise ratio. Tracer uptake by the tumor is indeed 3.26 ± 0.32 times higher than that of the contralateral striatum, and 78% of the activity is displaceable by unlabeled CLINDE. Finally, TSPO is abundantly expressed by the GL26 cells. Conclusions The present study demonstrates the feasibility of [123I]CLINDE SPECT in translational studies and underlines its potential for clinical glioma SPECT imaging.
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Affiliation(s)
- Stergios Tsartsalis
- Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Mental Health and Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1225 Geneva, Chêne-Bourg Switzerland ; Department of Psychiatry, University of Geneva, 1 rue Michel-Servet, CH1211 Geneva 4, Switzerland
| | - Noé Dumas
- Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Mental Health and Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1225 Geneva, Chêne-Bourg Switzerland
| | - Benjamin B Tournier
- Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Mental Health and Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1225 Geneva, Chêne-Bourg Switzerland
| | - Tien Pham
- ANSTO LifeSciences, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Sydney, NSW 2234 Australia
| | | | - Marie-Claude Grégoire
- ANSTO LifeSciences, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Sydney, NSW 2234 Australia
| | - Yves Charnay
- Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Mental Health and Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1225 Geneva, Chêne-Bourg Switzerland
| | - Philippe Millet
- Vulnerability Biomarkers Unit, Division of General Psychiatry, Department of Mental Health and Psychiatry, University Hospitals of Geneva, Chemin du Petit-Bel-Air 2, CH1225 Geneva, Chêne-Bourg Switzerland
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22
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Feng L, Svarer C, Thomsen G, de Nijs R, Larsen VA, Jensen P, Adamsen D, Dyssegaard A, Fischer W, Meden P, Krieger D, Møller K, Knudsen GM, Pinborg LH. In Vivo Quantification of Cerebral Translocator Protein Binding in Humans Using 6-Chloro-2-(4′-123I-Iodophenyl)-3-(N,N-Diethyl)-Imidazo[1,2-a]Pyridine-3-Acetamide SPECT. J Nucl Med 2014; 55:1966-72. [DOI: 10.2967/jnumed.114.143727] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
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23
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Chua SW, Kassiou M, Ittner LM. The translocator protein as a drug target in Alzheimer's disease. Expert Rev Neurother 2014; 14:439-48. [PMID: 24625007 DOI: 10.1586/14737175.2014.896201] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The translocator protein (TSPO) recently emerged as a potential drug target in Alzheimer's disease (AD). This has been fuelled mainly by positron emission topography studies that show the upregulation of TSPO in AD, especially in relation to microgliosis and astrogliosis in amyloid-β and tau pathology. Although data as to the exact role of TSPO in AD is still inconclusive, TSPO appears to be involved in neuroinflammatory processes and AD has been shown to involve substantial inflammation. Therefore, further development and investigation of the pharmacological effect of TSPO ligands in AD pathology are warranted.
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Affiliation(s)
- Sook W Chua
- Dementia Research Unit, School of Medical Sciences, Wallace Wurth Building, University of New South Wales, Sydney, NSW 2052, Australia
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24
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Liu G, Middleton RJ, Hatty CR, Kam WW, Chan R, Pham T, Harrison‐Brown M, Dodson E, Veale K, Banati RB. The 18 kDa translocator protein, microglia and neuroinflammation. Brain Pathol 2014; 24:631-53. [PMID: 25345894 PMCID: PMC8029074 DOI: 10.1111/bpa.12196] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Accepted: 08/19/2014] [Indexed: 12/17/2022] Open
Abstract
The 18 kDa translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor, is expressed in the injured brain. It has become known as an imaging marker of "neuroinflammation" indicating active disease, and is best interpreted as a nondiagnostic biomarker and disease staging tool that refers to histopathology rather than disease etiology. The therapeutic potential of TSPO as a drug target is mostly based on the understanding that it is an outer mitochondrial membrane protein required for the translocation of cholesterol, which thus regulates the rate of steroid synthesis. This pivotal role together with the evolutionary conservation of TSPO has underpinned the belief that any loss or mutation of TSPO should be associated with significant physiological deficits or be outright incompatible with life. However, against prediction, full Tspo knockout mice are viable and across their lifespan do not show the phenotype expected if cholesterol transport and steroid synthesis were significantly impaired. Thus, the "translocation" function of TSPO remains to be better substantiated. Here, we discuss the literature before and after the introduction of the new nomenclature for TSPO and review some of the newer findings. In light of the controversy surrounding the function of TSPO, we emphasize the continued importance of identifying compounds with confirmed selectivity and suggest that TSPO expression is analyzed within specific disease contexts rather than merely equated with the reified concept of "neuroinflammation."
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Affiliation(s)
- Guo‐Jun Liu
- Life SciencesAustralian Nuclear Science and Technology OrganisationNSWAustralia
- Brain & Mind Research InstituteThe University of SydneyNSWAustralia
- Discipline of Medical Imaging & Radiation SciencesFaculty of Health SciencesThe University of SydneyNSWAustralia
| | - Ryan J. Middleton
- Life SciencesAustralian Nuclear Science and Technology OrganisationNSWAustralia
| | - Claire R. Hatty
- Brain & Mind Research InstituteThe University of SydneyNSWAustralia
- Discipline of Medical Imaging & Radiation SciencesFaculty of Health SciencesThe University of SydneyNSWAustralia
| | - Winnie Wai‐Ying Kam
- Life SciencesAustralian Nuclear Science and Technology OrganisationNSWAustralia
- Brain & Mind Research InstituteThe University of SydneyNSWAustralia
- Discipline of Medical Imaging & Radiation SciencesFaculty of Health SciencesThe University of SydneyNSWAustralia
| | - Ronald Chan
- Brain & Mind Research InstituteThe University of SydneyNSWAustralia
- Discipline of Medical Imaging & Radiation SciencesFaculty of Health SciencesThe University of SydneyNSWAustralia
| | - Tien Pham
- Life SciencesAustralian Nuclear Science and Technology OrganisationNSWAustralia
| | - Meredith Harrison‐Brown
- Life SciencesAustralian Nuclear Science and Technology OrganisationNSWAustralia
- Discipline of Medical Imaging & Radiation SciencesFaculty of Health SciencesThe University of SydneyNSWAustralia
| | - Eoin Dodson
- Life SciencesAustralian Nuclear Science and Technology OrganisationNSWAustralia
| | - Kelly Veale
- Discipline of Medical Imaging & Radiation SciencesFaculty of Health SciencesThe University of SydneyNSWAustralia
| | - Richard B. Banati
- Life SciencesAustralian Nuclear Science and Technology OrganisationNSWAustralia
- Brain & Mind Research InstituteThe University of SydneyNSWAustralia
- Discipline of Medical Imaging & Radiation SciencesFaculty of Health SciencesThe University of SydneyNSWAustralia
- National Imaging Facility and Ramaciotti Brain Imaging CentreSydneyNSWAustralia
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25
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Callaghan PD, Wimberley CA, Rahardjo GL, Berghofer PJ, Pham TQ, Jackson T, Zahra D, Bourdier T, Wyatt N, Greguric I, Howell NR, Siegele R, Pastuovic Z, Mattner F, Loc’h C, Gregoire MC, Katsifis A. Comparison of in vivo binding properties of the 18-kDa translocator protein (TSPO) ligands [18F]PBR102 and [18F]PBR111 in a model of excitotoxin-induced neuroinflammation. Eur J Nucl Med Mol Imaging 2014; 42:138-51. [DOI: 10.1007/s00259-014-2895-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Accepted: 08/13/2014] [Indexed: 12/22/2022]
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Abstract
Neuroinflammation plays a central role in a variety of neurological diseases, including stroke, multiple sclerosis, Alzheimer’s disease, and malignant CNS neoplasms, among many other. Different cell types and molecular mediators participate in a cascade of events in the brain that is ultimately aimed at control, regeneration and repair, but leads to damage of brain tissue under pathological conditions. Non-invasive molecular imaging of key players in the inflammation cascade holds promise for identification and quantification of the disease process before it is too late for effective therapeutic intervention. In this review, we focus on molecular imaging techniques that target inflammatory cells and molecules that are of interest in neuroinflammation, especially those with high translational potential. Over the past decade, a plethora of molecular imaging agents have been developed and tested in animal models of (neuro)inflammation, and a few have been translated from bench to bedside. The most promising imaging techniques to visualize neuroinflammation include MRI, positron emission tomography (PET), single photon emission computed tomography (SPECT), and optical imaging methods. These techniques enable us to image adhesion molecules to visualize endothelial cell activation, assess leukocyte functions such as oxidative stress, granule release, and phagocytosis, and label a variety of inflammatory cells for cell tracking experiments. In addition, several cell types and their activation can be specifically targeted in vivo, and consequences of neuroinflammation such as neuronal death and demyelination can be quantified. As we continue to make progress in utilizing molecular imaging technology to study and understand neuroinflammation, increasing efforts and investment should be made to bring more of these novel imaging agents from the “bench to bedside.”
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Affiliation(s)
- Benjamin Pulli
- Center for Systems Biology and Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA
| | - John W Chen
- Center for Systems Biology and Department of Radiology, Massachusetts General Hospital and Harvard Medical School, 185 Cambridge Street, Boston, MA 02114, USA
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27
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Motbey CP, Clemens KJ, Apetz N, Winstock AR, Ramsey J, Li KM, Wyatt N, Callaghan PD, Bowen MT, Cornish JL, McGregor IS. High levels of intravenous mephedrone (4-methylmethcathinone) self-administration in rats: neural consequences and comparison with methamphetamine. J Psychopharmacol 2013; 27:823-36. [PMID: 23739178 DOI: 10.1177/0269881113490325] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mephedrone (MMC) is a relatively new recreational drug that has rapidly increased in popularity in recent years. This study explored the characteristics of intravenous MMC self-administration in the rat, with methamphetamine (METH) used as a comparator drug. Male Sprague-Dawley rats were trained to nose poke for intravenous MMC or METH in daily 2 h sessions over a 10 d acquisition period. Dose-response functions were then established under fixed- and progressive-ratio (FR and PR) schedules over three subsequent weeks of testing. Brains were analyzed ex vivo for striatal serotonin (5-HT) and dopamine (DA) levels and metabolites, while autoradiography assessed changes in the regional density of 5-HT and serotonin transporter (SERT) and DA transporter (DAT) and induction of the inflammation marker translocator protein (TSPO). Results showed that MMC was readily and vigorously self-administered via the intravenous route. Under a FR1 schedule, peak responding for MMC was obtained at 0.1 mg/kg/infusion, versus 0.01 mg/kg/infusion for METH. Break points under a PR schedule peaked at 1 mg/kg/infusion MMC versus 0.3 mg/kg/infusion for METH. Final intakes of MMC were 31.3 mg/kg/d compared to 4 mg/kg/d for METH. Rats self-administering MMC, but not METH, gained weight at a slower rate than control rats. METH, but not MMC, self-administration elevated TSPO receptor density in the nucleus accumbens and hippocampus, while MMC, but not METH, self-administration decreased striatal 5-hydroxyindolacetic acid (5-HIAA) concentrations. In summary, MMC supported high levels of self-administration, matching or exceeding those previously reported with other drugs of abuse.
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Affiliation(s)
- Craig P Motbey
- School of Psychology, University of Sydney, Sydney, Australia
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28
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Obenaus A. Neuroimaging biomarkers for epilepsy: advances and relevance to glial cells. Neurochem Int 2013; 63:712-8. [PMID: 23665337 DOI: 10.1016/j.neuint.2013.05.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 04/24/2013] [Accepted: 05/01/2013] [Indexed: 12/11/2022]
Abstract
Glial cells play an important role in normal brain function and emerging evidence would suggest that their dysfunction may be responsible for some epileptic disease states. Neuroimaging of glial cells is desirable, but there are no clear methods to assess neither their function nor localization. Magnetic resonance imaging (MRI) is now part of a standardized epilepsy imaging protocol to assess patients. Structural volumetric and T2-weighted imaging changes can assist in making a positive diagnosis in a majority of patients. The alterations reported in structural and T2 imaging is predominantly thought to reflect early neuronal loss followed by glial hypertrophy. MR spectroscopy for myo-inositol is a being pursued to identify glial alterations along with neuronal markers. Diffusion weighted imaging (DWI) is ideal for acute epileptiform events, but is not sensitive to either glial cells or neuronal long-term changes found in epilepsy. However, DWI variants such as diffusion tensor imaging or q-space imaging may shed additional light on aberrant glial function in the future. The sensitivity and specificity of PET radioligands, including those targeting glial cells (translocator protein) hold promise in being able to image glial cells. As the role of glial function/dysfunction in epilepsy becomes more apparent neuroimaging methods will evolve to assist the clinician and researcher in visualizing their location and function.
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Affiliation(s)
- Andre Obenaus
- Department of Pediatrics, School of Medicine, Loma Linda University, Loma Linda, CA, USA; Division of Interdisciplinary Studies, School of Behavioral Health, Loma Linda University, Loma Linda, CA, USA; Cell and Molecular Development and Biology Program, University of California, Riverside, CA, USA; Neuroscience Graduate Program, University of California, Riverside, CA, USA.
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29
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Mattner F, Staykova M, Berghofer P, Wong HJ, Fordham S, Callaghan P, Jackson T, Pham T, Gregoire MC, Zahra D, Rahardjo G, Linares D, Katsifis A. Central nervous system expression and PET imaging of the translocator protein in relapsing-remitting experimental autoimmune encephalomyelitis. J Nucl Med 2013; 54:291-8. [PMID: 23321458 DOI: 10.2967/jnumed.112.108894] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Glial neuroinflammation is associated with the development and progression of multiple sclerosis. PET imaging offers a unique opportunity to evaluate neuroinflammatory processes longitudinally in a noninvasive and clinically translational manner. (18)F-PBR111 is a newly developed PET radiopharmaceutical with high affinity and selectivity for the translocator protein (TSPO), expressed on activated glia. This study aimed to investigate neuroinflammation at different phases of relapsing-remitting (RR) experimental autoimmune encephalomyelitis (EAE) in the brains of SJL/J mice by postmortem histologic analysis and in vivo by PET imaging with (18)F-PBR111. METHODS RR EAE was induced by immunization with PLP(139-151) peptide in complete Freund's adjuvant. Naive female SJL/J mice and mice immunized with saline-complete Freund's adjuvant were used as controls. The biodistribution of (18)F-PBR111 was measured in 13 areas of the central nervous system and compared with PET imaging results during different phases of RR EAE. The extents of TSPO expression and glial activation were assessed with immunohistochemistry, immunofluorescence, and a real-time polymerase chain reaction. RESULTS There was significant TSPO expression in all of the central nervous system areas studied at the peak of the first clinical episode and, importantly, at the preclinical stage. In contrast, only a few TSPO-positive cells were observed at the second episode. At the third episode, there was again an increase in TSPO expression. TSPO expression was associated with microglial cells or macrophages without obvious astrocyte labeling. The dynamics of (18)F-PBR111 uptake in the brain, as measured by in vivo PET imaging and biodistribution, followed the pattern of TSPO expression during RR EAE. CONCLUSION PET imaging with the TSPO ligand (18)F-PBR111 clearly reflected the dynamics of microglial activation in the SJL/J mouse model of RR EAE. The results are the first to highlight the discrepancy between the clinical symptoms of EAE and TSPO expression in the brain, as measured by PET imaging at the peaks of various EAE episodes. The results suggest a significant role for PET imaging investigations of neuroinflammation in multiple sclerosis and allow for in vivo follow-up of antiinflammatory treatment strategies.
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Affiliation(s)
- Filomena Mattner
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia.
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30
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Benadiba M, Luurtsema G, Wichert-Ana L, Buchpigel CA, Filho GB. New Molecular Targets for PET and SPECT Imaging in Neurodegenerative Diseases. BRAZILIAN JOURNAL OF PSYCHIATRY 2012; 34 Suppl 2:S125-36. [DOI: 10.1016/j.rbp.2012.07.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 02/29/2012] [Indexed: 01/23/2023]
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31
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Motbey CP, Karanges E, Li KM, Wilkinson S, Winstock AR, Ramsay J, Hicks C, Kendig MD, Wyatt N, Callaghan PD, McGregor IS. Mephedrone in adolescent rats: residual memory impairment and acute but not lasting 5-HT depletion. PLoS One 2012; 7:e45473. [PMID: 23029034 PMCID: PMC3445542 DOI: 10.1371/journal.pone.0045473] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Accepted: 08/17/2012] [Indexed: 11/19/2022] Open
Abstract
Mephedrone (4-methylmethcathinone, MMC) is a popular recreational drug, yet its potential harms are yet to be fully established. The current study examined the impact of single or repeated MMC exposure on various neurochemical and behavioral measures in rats. In Experiment 1 male adolescent Wistar rats received single or repeated (once a day for 10 days) injections of MMC (30 mg/kg) or the comparator drug methamphetamine (METH, 2.5 mg/kg). Both MMC and METH caused robust hyperactivity in the 1 h following injection although this effect did not tend to sensitize with repeated treatment. Striatal dopamine (DA) levels were increased 1 h following either METH or MMC while striatal and hippocampal serotonin (5-HT) levels were decreased 1 h following MMC but not METH. MMC caused greater increases in 5-HT metabolism and greater reductions in DA metabolism in rats that had been previously exposed to MMC. Autoradiographic analysis showed no signs of neuroinflammation ([(125)I]CLINDE ligand used as a marker for translocator protein (TSPO) expression) with repeated exposure to either MMC or METH. In Experiment 2, rats received repeated MMC (7.5, 15 or 30 mg/kg once a day for 10 days) and were examined for residual behavioral effects following treatment. Repeated high (30 mg/kg) dose MMC produced impaired novel object recognition 5 weeks after drug treatment. However, no residual changes in 5-HT or DA tissue levels were observed at 7 weeks post-treatment. Overall these results show that MMC causes acute but not lasting changes in DA and 5-HT tissue concentrations. MMC can also cause long-term memory impairment. Future studies of cognitive function in MMC users are clearly warranted.
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Affiliation(s)
- Craig P. Motbey
- School of Psychology, University of Sydney, New South Wales, Australia
| | - Emily Karanges
- School of Psychology, University of Sydney, New South Wales, Australia
| | - Kong M. Li
- Department of Pharmacology, University of Sydney, New South Wales, Australia
| | - Shane Wilkinson
- School of Chemistry, University of Sydney, New South Wales, Australia
| | - Adam R. Winstock
- Institute of Psychiatry, Kings College, University of London, United Kingdom
| | - John Ramsay
- TICTAC Communications Ltd., St George’s College, University of London, United Kingdom
| | - Callum Hicks
- School of Psychology, University of Sydney, New South Wales, Australia
| | - Michael D. Kendig
- School of Psychology, University of Sydney, New South Wales, Australia
| | - Naomi Wyatt
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Paul D. Callaghan
- Life Sciences Division, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Iain S. McGregor
- School of Psychology, University of Sydney, New South Wales, Australia
- * E-mail:
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32
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Jacobs AH, Tavitian B. Noninvasive molecular imaging of neuroinflammation. J Cereb Blood Flow Metab 2012; 32:1393-415. [PMID: 22549622 PMCID: PMC3390799 DOI: 10.1038/jcbfm.2012.53] [Citation(s) in RCA: 188] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2011] [Revised: 03/05/2012] [Accepted: 03/23/2012] [Indexed: 12/23/2022]
Abstract
Inflammation is a highly dynamic and complex adaptive process to preserve and restore tissue homeostasis. Originally viewed as an immune-privileged organ, the central nervous system (CNS) is now recognized to have a constant interplay with the innate and the adaptive immune systems, where resident microglia and infiltrating immune cells from the periphery have important roles. Common diseases of the CNS, such as stroke, multiple sclerosis (MS), and neurodegeneration, elicit a neuroinflammatory response with the goal to limit the extent of the disease and to support repair and regeneration. However, various disease mechanisms lead to neuroinflammation (NI) contributing to the disease process itself. Molecular imaging is the method of choice to try to decipher key aspects of the dynamic interplay of various inducers, sensors, transducers, and effectors of the orchestrated inflammatory response in vivo in animal models and patients. Here, we review the basic principles of NI with emphasis on microglia and common neurologic disease mechanisms, the molecular targets which are being used and explored for imaging, and molecular imaging of NI in frequent neurologic diseases, such as stroke, MS, neurodegeneration, epilepsy, encephalitis, and gliomas.
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Affiliation(s)
- Andreas H Jacobs
- European Institute for Molecular Imaging (EIMI) at the Westfalian Wilhelms-University of Münster (WWU), Münster, Germany.
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Maia S, Arlicot N, Vierron E, Bodard S, Vergote J, Guilloteau D, Chalon S. Longitudinal and parallel monitoring of neuroinflammation and neurodegeneration in a 6-hydroxydopamine rat model of Parkinson's disease. Synapse 2012; 66:573-83. [DOI: 10.1002/syn.21543] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 01/24/2012] [Indexed: 12/20/2022]
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