1
|
Ohshima M, Moriguchi T, Enmi JI, Kawashima H, Koshino K, Zeniya T, Tsuji M, Iida H. [ 123I]CLINDE SPECT as a neuroinflammation imaging approach in a rat model of stroke. Exp Neurol 2024; 378:114843. [PMID: 38823675 DOI: 10.1016/j.expneurol.2024.114843] [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: 01/22/2024] [Revised: 05/21/2024] [Accepted: 05/28/2024] [Indexed: 06/03/2024]
Abstract
Poststroke neuroinflammation exacerbates disease progression. [11C]PK11195-positron emission tomography (PET) imaging has been used to visualize neuroinflammation; however, its short half-life of 20 min limits its clinical use. [123I]CLINDE has a longer half-life (13h); therefore, [123I]CLINDE-single-photon emission computed tomography (SPECT) imaging is potentially more practical than [11C]PK11195-PET imaging in clinical settings. The objectives of this study were to 1) validate neuroinflammation imaging using [123I]CLINDE and 2) investigate the mechanisms underlying stroke in association with neuroinflammation using multimodal techniques, including magnetic resonance imaging (MRI), gas-PET, and histological analysis, in a rat model of ischemic stroke, that is, permanent middle cerebral artery occlusion (pMCAo). At 6 days post-pMCAo, [123I]CLINDE-SPECT considerably corresponded to the immunohistochemical images stained with the CD68 antibody (a marker for microglia/microphages), comparable to the level observed in [11C]PK11195-PET images. In addition, the [123I]CLINDE-SPECT images corresponded well with autoradiography images. Rats with severe infarcts, as defined by MRI, exhibited marked neuroinflammation in the peri-infarct area and less neuroinflammation in the ischemic core, accompanied by a substantial reduction in the cerebral metabolic rate of oxygen (CMRO2) in 15O-gas-PET. Rats with moderate-to-mild infarcts exhibited neuroinflammation in the ischemic core, where CMRO2 levels were mildly reduced. This study demonstrates that [123I]CLINDE-SPECT imaging is suitable for neuroinflammation imaging and that the distribution of neuroinflammation varies depending on the severity of infarction.
Collapse
Affiliation(s)
- Makiko Ohshima
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Department of Neurobiology, Care Sciences & Society, Karolinska Institute, Visionsgatan 4, Solna 171 64, Sweden
| | - Tetsuaki Moriguchi
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Institute of Physics, University of Tsukuba, Ibaraki 305-8571, Japan
| | - Jun-Ichiro Enmi
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Center for Information and Neural Networks (CiNet), Advanced ICT Research Institute, National Institute of Information and Communications Technology (NICT), 1-4 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hidekazu Kawashima
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Radioisotope Research Center, Kyoto Pharmaceutical University, 1 Misasagi-Shichono-cho, Yamashina-ku, Kyoto 607-8412, Japan
| | - Kazuhiro Koshino
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Department of Systems and Informatics, Hokkaido Information University, 59-2 Nishi-nopporo, Ebetsu, Hokkaido, Japan
| | - Tsutomu Zeniya
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Graduate School of Science and Technology, Hirosaki University, 3 Bunkyo-cho, Hirosaki, Aomori 036-8561, Japan
| | - Masahiro Tsuji
- Department of Regenerative Medicine and Tissue Engineering, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Department of Food and Nutrition, Kyoto Women's University, 35 Kitahiyoshi-cho, Imakumano, Higashiyama-ku, Kyoto 605-8501, Japan.
| | - Hidehiro Iida
- Department of Investigative Radiology, National Cerebral and Cardiovascular Center, 6-1 Kishibe-Shimmachi, Suita, Osaka 564-8565, Japan; Faculty of Medicine, University of Turku, and Turku PET Centre, Turku University Hospital, Kiinamyllynkatu 4-8, 20520 Turku, Finland
| |
Collapse
|
2
|
Koukalova L, Chmelova M, Amlerova Z, Vargova L. Out of the core: the impact of focal ischemia in regions beyond the penumbra. Front Cell Neurosci 2024; 18:1336886. [PMID: 38504666 PMCID: PMC10948541 DOI: 10.3389/fncel.2024.1336886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 02/08/2024] [Indexed: 03/21/2024] Open
Abstract
The changes in the necrotic core and the penumbra following induction of focal ischemia have been the focus of attention for some time. However, evidence shows, that ischemic injury is not confined to the primarily affected structures and may influence the remote areas as well. Yet many studies fail to probe into the structures beyond the penumbra, and possibly do not even find any significant results due to their short-term design, as secondary damage occurs later. This slower reaction can be perceived as a therapeutic opportunity, in contrast to the ischemic core defined as irreversibly damaged tissue, where the window for salvation is comparatively short. The pathologies in remote structures occur relatively frequently and are clearly linked to the post-stroke neurological outcome. In order to develop efficient therapies, a deeper understanding of what exactly happens in the exo-focal regions is necessary. The mechanisms of glia contribution to the ischemic damage in core/penumbra are relatively well described and include impaired ion homeostasis, excessive cell swelling, glutamate excitotoxic mechanism, release of pro-inflammatory cytokines and phagocytosis or damage propagation via astrocytic syncytia. However, little is known about glia involvement in post-ischemic processes in remote areas. In this literature review, we discuss the definitions of the terms "ischemic core", "penumbra" and "remote areas." Furthermore, we present evidence showing the array of structural and functional changes in the more remote regions from the primary site of focal ischemia, with a special focus on glia and the extracellular matrix. The collected information is compared with the processes commonly occurring in the ischemic core or in the penumbra. Moreover, the possible causes of this phenomenon and the approaches for investigation are described, and finally, we evaluate the efficacy of therapies, which have been studied for their anti-ischemic effect in remote areas in recent years.
Collapse
Affiliation(s)
- Ludmila Koukalova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Martina Chmelova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, Czechia
| | - Zuzana Amlerova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Lydia Vargova
- Department of Neuroscience, Second Faculty of Medicine, Charles University, Prague, Czechia
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the Czech Academy of Sciences, Prague, Czechia
| |
Collapse
|
3
|
A pilot [ 11C]PBR28 PET/MRI study of neuroinflammation and neurodegeneration in chronic stroke patients. Brain Behav Immun Health 2021; 17:100336. [PMID: 34589819 PMCID: PMC8474408 DOI: 10.1016/j.bbih.2021.100336] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 08/18/2021] [Accepted: 08/21/2021] [Indexed: 11/24/2022] Open
Abstract
Neuroinflammation occurs in response to acute ischemic stroke, and has been speculated to underlie secondary poststroke pathologies, such as depression, that often develop over time poststroke. However, no study has examined whether neuroinflammation is present in chronic stroke patients (e.g., ≥ 1 year poststroke). This study tested whether neuroinflammation is present in chronic stroke patients, and is associated with neurodegeneration, using [11C]PBR28 PET and diffusion MRI. Eight patients with middle cerebral artery (MCA) ischemic stroke incurred 1–3 years prior and 16 healthy controls underwent [11C]PBR28 PET to measure glial activation and diffusion MRI to measure microstructural integrity by mean diffusivity (MD) and fractional anisotropy (FA) using an integrated PET/MRI scanner. Group differences in [11C]PBR28 binding, MD and FA were analyzed voxelwise across the whole brain excluding the infarct zone defined as voxels containing the infarct in any patient. Compared to controls, patients showed elevations in [11C]PBR28 binding in several brain regions outside the infarct zone, including regions with presumed direct neuroanatomical connections to the infarct (e.g., ipsilesional internal capsule and thalamus) and those without known direct connections (e.g., contralesional thalamus and cingulate gyrus). Patients also showed widespread elevations in MD, with a subset of these regions having reduced FA. In patients, MD was more elevated in regions with co-localized elevations in [11C]PBR28 binding than in contralateral regions without elevations in [11C]PBR28 binding. This pilot study supports the presence of extensive glial activation along with widespread loss in microstructural integrity in non-infarcted tissue in a cohort of patients with chronic MCA stroke. The loss in microstructural integrity was greater in regions with co-localized glial activation. It is possible that stroke risk factors (e.g., hypertension) contributed to these tissue changes in patients. Chronic neuroinflammation speculated to underlie secondary poststroke pathologies such as depression. Measured neuroinflammation in chronic stroke patients using [11C]PBR28 PET. First study showing extensive neuroinflammation in non-infarcted tissue in chronic stroke patients.
Collapse
|
4
|
Yu F, Huang T, Ran Y, Li D, Ye L, Tian G, Xi J, Liu Z. New Insights Into the Roles of Microglial Regulation in Brain Plasticity-Dependent Stroke Recovery. Front Cell Neurosci 2021; 15:727899. [PMID: 34421544 PMCID: PMC8374071 DOI: 10.3389/fncel.2021.727899] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 07/13/2021] [Indexed: 01/07/2023] Open
Abstract
Stroke remains the leading cause of long-term disability worldwide with significant long-term sequelae. However, there is no highly effective treatment to enhance post-stroke recovery despite extensive efforts in exploring rehabilitative therapies. Neurorehabilitation is recognized as the cornerstone of functional restoration therapy in stroke, where treatments are focused on neuroplastic regulation to reverse neural structural disruption and improve neurofunctional networks. Post-stroke neuroplasticity changes begin within hours of symptom onset and reaches a plateau by 3 to 4 weeks within the global brain in animal studies. It plays a determining role in spontaneous stroke recovery. Microglia are immediately activated following cerebral ischemia, which has been found both proximal to the primary ischemic injury and at the remote brain regions which have functional connections to the primary injury area. Microglia exhibit different activation profiles based on the microenvironment and adaptively switch their phenotypes in a spatiotemporal manner in response to brain injuries. Microglial activation coincides with neuroplasticity after stroke, which provides the fundamental base for the microglia-mediated inflammatory responses involved in the entire neural network rewiring and brain repair. Microglial activation exerts important effects on spontaneous recovery after stroke, including structural and functional reestablishment of neurovascular networks, neurogenesis, axonal remodeling, and blood vessel regeneration. In this review, we focus on the crosstalk between microglial activation and endogenous neuroplasticity, with a special focus on the plastic alterations in the whole brain network and their implications for structural and functional restoration after stroke. We then summarize recent advances in the impacts of microglial phenotype polarization on brain plasticity, trying to discuss the potential efficacy of microglia-based extrinsic restorative interventions in promoting post-stroke recovery.
Collapse
Affiliation(s)
- Fang Yu
- Department of Neurology, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Anesthesiology, Westchester Medical Center, New York Medical College, Valhalla, NY, United States
| | - Tingting Huang
- Department of Anesthesiology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuanyuan Ran
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China
| | - Da Li
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China
| | - Lin Ye
- School of Materials Science and Engineering, Beijing Institute of Technology, Beijing, China
| | - Guiqin Tian
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China
| | - Jianing Xi
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China
| | - Zongjian Liu
- Department of Rehabilitation, Beijing Rehabilitation Hospital, Capital Medical University, Beijing, China
| |
Collapse
|
5
|
Kreisl WC, Kim MJ, Coughlin JM, Henter ID, Owen DR, Innis RB. PET imaging of neuroinflammation in neurological disorders. Lancet Neurol 2020; 19:940-950. [PMID: 33098803 PMCID: PMC7912433 DOI: 10.1016/s1474-4422(20)30346-x] [Citation(s) in RCA: 106] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Revised: 08/06/2020] [Accepted: 08/21/2020] [Indexed: 12/11/2022]
Abstract
A growing need exists for reliable in-vivo measurement of neuroinflammation to better characterise the inflammatory processes underlying various diseases and to inform the development of novel therapeutics that target deleterious glial activity. PET is well suited to quantify neuroinflammation and has the potential to discriminate components of the neuroimmune response. However, there are several obstacles to the reliable quantification of neuroinflammation by PET imaging. Despite these challenges, PET studies have consistently identified associations between neuroimmune responses and pathophysiology in brain disorders such as Alzheimer's disease. Tissue studies have also begun to clarify the meaning of changes in PET signal in some diseases. Furthermore, although PET imaging of neuroinflammation does not have an established clinical application, novel targets are under investigation and a small but growing number of studies have suggested that this imaging modality could have a role in drug development. Future studies are needed to further improve our knowledge of the cellular mechanisms that underlie changes in PET signal, how immune response contributes to neurological disease, and how it might be therapeutically modified.
Collapse
Affiliation(s)
- William C Kreisl
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA
| | - Min-Jeong Kim
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD, USA
| | - Jennifer M Coughlin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Ioline D Henter
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD, USA
| | - David R Owen
- Department of Brain Sciences, Imperial College London, London, UK
| | - Robert B Innis
- Molecular Imaging Branch, National Institute of Mental Health, Bethesda, MD, USA.
| |
Collapse
|
6
|
Cao Z, Harvey SS, Bliss TM, Cheng MY, Steinberg GK. Inflammatory Responses in the Secondary Thalamic Injury After Cortical Ischemic Stroke. Front Neurol 2020; 11:236. [PMID: 32318016 PMCID: PMC7154072 DOI: 10.3389/fneur.2020.00236] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 03/12/2020] [Indexed: 12/12/2022] Open
Abstract
Stroke is one of the major causes of chronic disability worldwide and increasing efforts have focused on studying brain repair and recovery after stroke. Following stroke, the primary injury site can disrupt functional connections in nearby and remotely connected brain regions, resulting in the development of secondary injuries that may impede long-term functional recovery. In particular, secondary degenerative injury occurs in the connected ipsilesional thalamus following a cortical stroke. Although secondary thalamic injury was first described decades ago, the underlying mechanisms still remain unclear. We performed a systematic literature review using the NCBI PubMed database for studies that focused on the secondary thalamic degeneration after cortical ischemic stroke. In this review, we discussed emerging studies that characterized the pathological changes in the secondary degenerative thalamus after stroke; these included excitotoxicity, apoptosis, amyloid beta protein accumulation, blood-brain-barrier breakdown, and inflammatory responses. In particular, we highlighted key findings of the dynamic inflammatory responses in the secondary thalamic injury and discussed the involvement of several cell types in this process. We also discussed studies that investigated the effects of blocking secondary thalamic injury on inflammatory responses and stroke outcome. Targeting secondary injuries after stroke may alleviate network-wide deficits, and ultimately promote stroke recovery.
Collapse
Affiliation(s)
- Zhijuan Cao
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States.,Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, United States
| | - Sean S Harvey
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States.,Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, United States
| | - Tonya M Bliss
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States.,Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, United States
| | - Michelle Y Cheng
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States.,Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, United States
| | - Gary K Steinberg
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States.,Stanford Stroke Center, Stanford University School of Medicine, Stanford, CA, United States
| |
Collapse
|
7
|
Oleoylethanolamide treatment reduces neurobehavioral deficits and brain pathology in a mouse model of Gulf War Illness. Sci Rep 2018; 8:12921. [PMID: 30150699 PMCID: PMC6110778 DOI: 10.1038/s41598-018-31242-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/15/2018] [Indexed: 12/12/2022] Open
Abstract
There are nearly 250,000 Gulf War (GW) veterans who suffer from Gulf War Illness (GWI), a multi-symptom condition that remains untreatable. The main objective was to determine if targeting peroxisomal function could be of therapeutic value in GWI. We performed a pilot study that showed accumulation of very long chain fatty acids (VLCFA), which are metabolized in peroxisomes, in plasma from veterans with GWI. We then examined if targeting peroxisomal β-oxidation with oleoylethanolamide (OEA) restores these lipids to the normal levels and mitigates neuroinflammation and neurobehavioral deficits in a well-established mouse model of GWI. In GWI mice, treatment with OEA corresponded with cognitive benefits and reduced fatigue and disinhibition-like behavior in GWI mice. Biochemical and molecular analysis of the brain tissue showed reduced astroglia and microglia staining, decreased levels of chemokines and cytokines, and decreased NFκB phosphorylation. Treatment with OEA reduced accumulation of peroxisome specific VLCFA in the brains of GWI mice. These studies further support the translational value of targeting peroxisomes. We expect that OEA may be a potential therapy for treating neurobehavioral symptoms and the underlying lipid dysfunction and neuroinflammation associated with GWI. Oleoylethanolamide is available as a dietary supplement, making it appealing for human translational studies.
Collapse
|
8
|
Selvaraj S, Bloomfield PS, Cao B, Veronese M, Turkheimer F, Howes OD. Brain TSPO imaging and gray matter volume in schizophrenia patients and in people at ultra high risk of psychosis: An [ 11C]PBR28 study. Schizophr Res 2018; 195:206-214. [PMID: 28893493 PMCID: PMC6027955 DOI: 10.1016/j.schres.2017.08.063] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 08/31/2017] [Accepted: 08/31/2017] [Indexed: 12/12/2022]
Abstract
Patients with schizophrenia show whole brain and cortical gray matter (GM) volume reductions which are progressive early in their illness. Microglia, the resident immune cells in the CNS, phagocytose neurons and synapses. Some post mortem and in vivo studies in schizophrenia show evidence for elevated microglial activation compared to matched controls. However, it is currently unclear how these results relate to changes in cortical structure. METHODS Fourteen patients with schizophrenia and 14 ultra high risk for psychosis (UHR) subjects alongside two groups of age and genotype matched healthy controls received [11C]PBR28 PET scans to index TSPO expression, a marker of microglial activation and a 3T MRI scan. We investigated the relationship between the volume changes of cortical regions and microglial activation in cortical GM (as indexed by [11C]PBR28 distribution volume ratio (DVR). RESULTS The total cortical GM volume was significantly lower in SCZ than the controls [mean (SD)/cm3: SCZ=448.83 (39.2) and controls=499.6 (59.2) (p=0.02) but not in UHR (mean (SD)=503.06 (57.9) and controls=524.46 (45.3) p=0.3). Regression model fitted the total cortical GM DVR values with the cortical regional volumes in SCZ (r=0.81; p<0.001) and in UHR (r=0.63; p=0.02). We found a significant negative correlation between the TSPO signal and total cortical GM volume in SCZ with the highest absolute correlation coefficient in the right superior-parietal cortex (r=-0.72; p=0.006). CONCLUSIONS These findings suggest that microglial activity is related to the altered cortical volume seen in schizophrenia. Longitudinal investigations are required to determine whether microglial activation leads to cortical gray matter loss.
Collapse
Affiliation(s)
- Sudhakar Selvaraj
- Department of Psychiatry and Behavioural Sciences, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA; Psychiatric Imaging Group, MRC Clinical Sciences Centre, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London, W12 0NN, UK.
| | - Peter S Bloomfield
- Psychiatric Imaging Group, MRC Clinical Sciences Centre, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London, W12 0NN, UK
| | - Bo Cao
- Department of Psychiatry and Behavioural Sciences, The University of Texas Health Science Center at Houston, Houston, TX 77054, USA
| | - Mattia Veronese
- Centre for Neuroimaging Sciences, IoPPN, King's College London, Box PO89, De Crespigny Park, London SE5 8AF, UK
| | - Federico Turkheimer
- Centre for Neuroimaging Sciences, IoPPN, King's College London, Box PO89, De Crespigny Park, London SE5 8AF, UK
| | - Oliver D Howes
- Psychiatric Imaging Group, MRC Clinical Sciences Centre, Institute of Clinical Sciences, Imperial College London, Hammersmith Hospital, London, W12 0NN, UK; Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, De Crespigny Park, London SE5 8AF, UK
| |
Collapse
|
9
|
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: 13] [Impact Index Per Article: 1.6] [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.
Collapse
|
10
|
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
|
11
|
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."
Collapse
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
| |
Collapse
|
12
|
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]
|
13
|
Plog BA, Moll KM, Kang H, Iliff JJ, Dashnaw ML, Nedergaard M, Vates GE. A novel technique for morphometric quantification of subarachnoid hemorrhage-induced microglia activation. J Neurosci Methods 2014; 229:44-52. [PMID: 24735531 DOI: 10.1016/j.jneumeth.2014.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 03/24/2014] [Accepted: 04/05/2014] [Indexed: 11/26/2022]
Abstract
BACKGROUND Subarachnoid hemorrhage (SAH) is a neurologic catastrophe and poor outcome is typically attributed to vasospasm; however, there is also evidence that SAH causes a pro-inflammatory state and these two phenomena may be interrelated. SAH causes activation of microglia, but the time course and degree of microglial activation after SAH and its link to poor patient outcome and vasospasm remains unknown. NEW METHOD Transgenic mice expressing eGFP under the control of the CX3CR1 locus, in which microglia are endogenously fluorescent, were randomly assigned to control or SAH groups. Immunohistochemistry for CD-68 and CD-31 was performed at different time points after SAH. Using confocal microscopy and MatLab software, we have developed a novel technique to detect and quantify the stages of microglial activation and return to quiescence using an automated computerized morphometric analysis. RESULTS We detected a statistically significant decrease in microglial process complexity 2 and 7 days following SAH. In addition, we detected a statistically significant increase in microglial domain volume 1 day following SAH; however, microglial domain volume returned to baseline by 2 days. COMPARISON WITH EXISTING METHOD Most techniques for microglia assessment are qualitative, not quantitative, and are therefore inadequate to address the effects of anti-inflammatory drug treatment or other therapies after SAH. CONCLUSIONS Using novel image analysis techniques we were able to reproducibly quantify activation of microglia following SAH, which will improve our ability to study the biology of microglial activation, and may ultimately improve management of disease progression and response to therapies directed at microglial activation.
Collapse
Affiliation(s)
- Benjamin A Plog
- University of Rochester School of Medicine and Dentistry, Rochester, NY, USA; Department of Neurosurgery, Center for Translation Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA; Department of Pathology, University of Rochester Medical Center, Rochester, NY, USA.
| | - Katherine M Moll
- University of Rochester School of Medicine and Dentistry, Rochester, NY, USA; Department of Neurosurgery, Center for Translation Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA.
| | - Hongyi Kang
- Department of Neurosurgery, Center for Translation Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA.
| | - Jeffrey J Iliff
- Department of Neurosurgery, Center for Translation Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA.
| | - Matthew L Dashnaw
- Department of Neurosurgery, Center for Translation Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA.
| | - Maiken Nedergaard
- Department of Neurosurgery, Center for Translation Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA.
| | - G Edward Vates
- Department of Neurosurgery, Center for Translation Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA.
| |
Collapse
|
14
|
Arlicot N, Tronel C, Bodard S, Garreau L, de la Crompe B, Vandevelde I, Guilloteau D, Antier D, Chalon S. Translocator Protein (18 kDa) Mapping with [
125
I]-CLINDE in the Quinolinic Acid Rat Model of Excitotoxicity: A Longitudinal Comparison with Microglial Activation, Astrogliosis, and Neuronal Death. Mol Imaging 2014. [DOI: 10.2310/7290.2013.00075] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Nicolas Arlicot
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Claire Tronel
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Sylvie Bodard
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Lucette Garreau
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Brice de la Crompe
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Inge Vandevelde
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Denis Guilloteau
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Daniel Antier
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| | - Sylvie Chalon
- From Inserm, U930; Université François-Rabelais de Tours, UMR-U930; CHRU de Tours, Hôpital Bretonneau, Pôle Santé Publique – Produits de Santé; and CHRU de Tours, Hôpital Bretonneau, Service de Médecine Nucléaire In Vitro, Tours, France
| |
Collapse
|
15
|
Rodriguez-Grande B, Blackabey V, Gittens B, Pinteaux E, Denes A. Loss of substance P and inflammation precede delayed neurodegeneration in the substantia nigra after cerebral ischemia. Brain Behav Immun 2013; 29:51-61. [PMID: 23232501 DOI: 10.1016/j.bbi.2012.11.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 11/01/2012] [Accepted: 11/29/2012] [Indexed: 12/16/2022] Open
Abstract
Focal cerebral ischemia leads to delayed neurodegeneration in remote brain regions. The substantia nigra (SN) does not normally show primary neuronal death after ischemic events affecting the striatum, but can exhibit delayed neuronal loss after the ischemic injury through mechanisms that are unknown. No data are available in mice showing acute post-stroke inflammation and remote injury in the SN. Substance P (SP), a mediator of neurogenic inflammation, is a key element of the striato-nigral circuitry, but alterations of SP in the SN have not been studied after acute striatal injury. Inflammation, a key contributor to neuronal death, is found in the SN after striatal ischemia, but it is unknown whether it precedes or occurs concomitantly with neuronal death. We hypothesised that focal striatal ischemia induces changes in SP levels in the SN and that inflammation precedes neuronal death in the SN. Using the middle cerebral artery occlusion model, we found a significant loss of SP in the ipsilateral SN 24h after striatal ischemia in mice. In the same area where SP loss occurs, significant glial and vascular activation, but no neuronal death, were observed. In contrast, a marked neuronal loss was observed within six days in the area of SP loss and inflammation. Our data suggest that focal loss of SP and early inflammatory changes in the SN precede remote neuronal injury after striatal ischemic damage. These observations may have important implications for motor impairment in stroke patients and indicate that striatal ischemia might facilitate Parkinson's disease development.
Collapse
Affiliation(s)
- Beatriz Rodriguez-Grande
- Faculty of Life Sciences, 2.002 A.V. Hill Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Victoria Blackabey
- Faculty of Life Sciences, 2.002 A.V. Hill Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Beatrice Gittens
- Faculty of Life Sciences, 2.002 A.V. Hill Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK
| | - Emmanuel Pinteaux
- Faculty of Life Sciences, 2.002 A.V. Hill Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
| | - Adam Denes
- Faculty of Life Sciences, 2.002 A.V. Hill Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK; Laboratory of Molecular Neuroendocrinology, Institute of Experimental Medicine, Budapest, Hungary
| |
Collapse
|
16
|
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]
|
17
|
Hughes JL, Jones PS, Beech JS, Wang D, Menon DK, Aigbirhio FI, Fryer TD, Baron JC. A microPET study of the regional distribution of [11C]-PK11195 binding following temporary focal cerebral ischemia in the rat. Correlation with post mortem mapping of microglia activation. Neuroimage 2011; 59:2007-16. [PMID: 22056528 DOI: 10.1016/j.neuroimage.2011.10.060] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2011] [Revised: 10/07/2011] [Accepted: 10/18/2011] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND Post-stroke microglial activation (MA) may have both neurotoxic and pro-repair effects, particularly in the salvaged penumbra. Mapping MA in vivo is therefore an important goal. 11C-PK11195, a ligand for the 18 kDa translocator protein, is the reference radioligand for MA imaging, but a correlation between the regional distributions of in vivo tracer binding and post mortem MA after stroke, as assessed with PET and immunohistochemistry, respectively, has not been demonstrated so far. Here we performed 11C-PK11195 microPET in a rat model previously shown to induce extensive cortical MA, and determined the correlation between 11C-PK11195 and immunostaining with the CD11 antibody OX42, so as to verify the presence of activated microglia, in a template of PET-resolution size regions-of-interest (ROIs) spanning the whole affected hemisphere. METHODS Adult spontaneously hypertensive rats underwent 45 min distal middle cerebral artery occlusion and 11C-PK11195 PET at Days 2 and 14 after stroke according to a longitudinal design. Following perfusion-fixation at Day 14, brains were removed and coronally cut for OX42 staining. 11C-PK11195 binding potential (BPND) parametric maps were generated, and in each rat both BP(ND) and OX42 (intensity×extent score) were obtained in the same set of 44 ROIs extracted from a cytoarchitectonic atlas to cover the whole hemisphere. Correlations were computed across the 44 ROIs both within and across subjects. RESULTS Significant BPND increases were observed in both the infarct and surrounding areas in all rats at day 14; less strong but still significant increases were present at day 2. There were highly significant (all p<0.001) positive correlations, both within- and across-subjects, between day 14 BPND values and OX42 scores. CONCLUSIONS The correlation between Day 14 11C-PK11195 and OX42 across the affected hemisphere from the same brain regions and animals further supports the validity of 11C-PK11195 as an in vivo imaging marker of MA following stroke. The finding of statistically significant increases in 11C-PK11195 as early as 48 h after stroke is novel. These results have implications for mapping MA after stroke, with potential therapeutic applications.
Collapse
Affiliation(s)
- J L Hughes
- Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, UK
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Colak G, Filiano AJ, Johnson GVW. The application of permanent middle cerebral artery ligation in the mouse. J Vis Exp 2011:3039. [PMID: 21808231 PMCID: PMC3196186 DOI: 10.3791/3039] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Focal cerebral ischemia is among the most common type of stroke seen in patients. Due to the clinical significance there has been a prolonged effort to develop suitable animal models to study the events that unfold during ischemic insult. These techniques include transient or permanent, focal or global ischemia models using many different animal models, with the most common being rodents. The permanent MCA ligation method which is also referred as pMCAo in the literature is used extensively as a focal ischemia model in rodents. This method was originally described for rats by Tamura et al. in 1981. In this protocol a craniotomy was used to access the MCA and the proximal regions were occluded by electrocoagulation. The infarcts involve mostly cortical and sometimes striatal regions depending on the location of the occlusion. This technique is now well established and used in many laboratories. Early use of this technique led to the definition and description of "infarct core" and "penumbra", and it is often used to evaluate potential neuroprotective compounds. Although the initial studies were performed in rats, permanent MCA ligation has been used successfully in mice with slight modifications. This model yields reproducible infarcts and increased post-survival rates. Approximately 80% of the ischemic strokes in humans happen in the MCA area and thus this is a very relevant model for stroke studies. Currently, there is a paucity of effective treatments available to stroke patients, and thus there is a need for good models to test potential pharmacological compounds and evaluate physiological outcomes. This method can also be used for studying intracellular hypoxia response mechanisms in vivo. Here, we present the MCA ligation surgery in a C57/BL6 mouse. We describe the pre-surgical preparation, MCA ligation surgery and 2,3,5 Triphenyltetrazolium chloride (TTC) staining for quantification of infarct volumes.
Collapse
Affiliation(s)
- Gozde Colak
- Department of Pharmacology and Physiology, University of Rochester, USA
| | | | | |
Collapse
|
19
|
Mattner F, Bandin DL, Staykova M, Berghofer P, Gregoire MC, Ballantyne P, Quinlivan M, Fordham S, Pham T, Willenborg DO, Katsifis A. Evaluation of [¹²³I]-CLINDE as a potent SPECT radiotracer to assess the degree of astroglia activation in cuprizone-induced neuroinflammation. Eur J Nucl Med Mol Imaging 2011; 38:1516-28. [PMID: 21484375 DOI: 10.1007/s00259-011-1784-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 03/01/2011] [Indexed: 10/18/2022]
Abstract
PURPOSE The purpose of this study was to assess the feasibility and sensitivity of the high-affinity translocator protein (TSPO) ligand [(123)I]-CLINDE in imaging TSPO changes in vivo and characterise and compare astroglial and TSPO changes in the cuprizone model of demyelination and remyelination in C57BL/6 mice. METHODS C57BL/6 mice were fed with cuprizone for 4 weeks to induce demyelination followed by 2-4 weeks of standard diet (remyelination). Groups of mice were followed by in vivo single photon emission computed tomography (SPECT)/CT imaging using [(123)I]-CLINDE and uptake correlated with biodistribution, autoradiography, immunohistochemistry, immunofluorescence and real-time polymerase chain reaction (RT-PCR). RESULTS The uptake of [(123)I]-CLINDE in the brain as measured by SPECT imaging over the course of treatment reflects the extent of the physiological response, with significant increases observed during demyelination followed by a decrease in uptake during remyelination. This was confirmed by autoradiography and biodistribution studies. A positive correlation between TSPO expression and astrogliosis was found and both activated astrocytes and microglial cells expressed TSPO. [(123)I]-CLINDE uptake reflects astrogliosis in brain structures such as corpus callosum, caudate putamen, medium septum and olfactory tubercle as confirmed by both in vitro and in vivo results. CONCLUSION The dynamics in the cuprizone-induced astroglial and TSPO changes, observed by SPECT imaging, were confirmed by immunofluorescence, RT-PCR and autoradiography. The highly specific TSPO radioiodinated ligand CLINDE can be used as an in vivo marker for early detection and monitoring of a variety of neuropathological conditions using noninvasive brain imaging techniques.
Collapse
Affiliation(s)
- Filomena Mattner
- ANSTO LifeSciences, Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, Sydney, NSW 2234, Australia.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|