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Wang Z, Song Y, Bai S, Xiang W, Zhou X, Han L, Zhu D, Guan Y. Imaging of microglia in post-stroke inflammation. Nucl Med Biol 2023; 118-119:108336. [PMID: 37028196 DOI: 10.1016/j.nucmedbio.2023.108336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2022] [Revised: 03/21/2023] [Accepted: 03/21/2023] [Indexed: 04/03/2023]
Abstract
Microglia constantly survey the central nervous system microenvironment and maintain brain homeostasis. Microglia activation, polarization and inflammatory response are of great importance in the pathophysiology of ischemic stroke. For exploring biochemical processes in vivo, positron emission tomography (PET) is a superior imaging tool. Translocator protein 18 kDa (TSPO), is a validated neuroinflammatory biomarker which is widely used to evaluate various central nervous system (CNS) pathologies in both preclinical and clinical studies. TSPO level can be elevated due to peripheral inflammatory cells infiltration and glial cells activation. Therefore, a clear understanding of the dynamic changes between microglia and TSPO is critical for interpreting PET studies and understanding the pathophysiology after ischemic stroke. Our review discusses alternative biological targets that have attracted considerable interest for the imaging of microglia activation in recent years, and the potential value of imaging of microglia in the assessment of stroke therapies.
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18F-Radiolabeled Translocator Protein (TSPO) PET Tracers: Recent Development of TSPO Radioligands and Their Application to PET Study. Pharmaceutics 2022; 14:pharmaceutics14112545. [PMID: 36432736 PMCID: PMC9697781 DOI: 10.3390/pharmaceutics14112545] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
Abstract
Translocator protein 18 kDa (TSPO) is a transmembrane protein in the mitochondrial membrane, which has been identified as a peripheral benzodiazepine receptor. TSPO is generally present at high concentrations in steroid-producing cells and plays an important role in steroid synthesis, apoptosis, and cell proliferation. In the central nervous system, TSPO expression is relatively modest under normal physiological circumstances. However, some pathological disorders can lead to changes in TSPO expression. Overexpression of TSPO is associated with several diseases, such as neurodegenerative diseases, neuroinflammation, brain injury, and cancers. TSPO has therefore become an effective biomarker of related diseases. Positron emission tomography (PET), a non-invasive molecular imaging technique used for the clinical diagnosis of numerous diseases, can detect diseases related to TSPO expression. Several radiolabeled TSPO ligands have been developed for PET. In this review, we describe recent advances in the development of TSPO ligands, and 18F-radiolabeled TSPO in particular, as PET tracers. This review covers pharmacokinetic studies, preclinical and clinical trials of 18F-labeled TSPO PET ligands, and the synthesis of TSPO ligands.
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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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Microglia and Stem-Cell Mediated Neuroprotection after Neonatal Hypoxia-Ischemia. Stem Cell Rev Rep 2021; 18:474-522. [PMID: 34382141 PMCID: PMC8930888 DOI: 10.1007/s12015-021-10213-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2021] [Indexed: 12/14/2022]
Abstract
Neonatal hypoxia-ischemia encephalopathy (HIE) refers to a brain injury in term infants that can lead to death or lifelong neurological deficits such as cerebral palsy (CP). The pathogenesis of this disease involves multiple cellular and molecular events, notably a neuroinflammatory response driven partly by microglia, the brain resident macrophages. Treatment options are currently very limited, but stem cell (SC) therapy holds promise, as beneficial outcomes are reported in animal studies and to a lesser degree in human trials. Among putative mechanisms of action, immunomodulation is considered a major contributor to SC associated benefits. The goal of this review is to examine whether microglia is a cellular target of SC-mediated immunomodulation and whether the recruitment of microglia is linked to brain repair. We will first provide an overview on microglial activation in the rodent model of neonatal HI, and highlight its sensitivity to developmental age. Two complementary questions are then addressed: (i) do immune-related treatments impact microglia and provide neuroprotection, (ii) does stem cell treatment modulates microglia? Finally, the immune-related findings in patients enrolled in SC based clinical trials are discussed. Our review points to an impact of SCs on the microglial phenotype, but heterogeneity in experimental designs and methodological limitations hamper our understanding of a potential contribution of microglia to SC associated benefits. Thorough analyses of the microglial phenotype are warranted to better address the relevance of the neuroimmune crosstalk in brain repair and improve or advance the development of SC protocols in humans.
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Li T, Zhao J, Xie W, Yuan W, Guo J, Pang S, Gan WB, Gómez-Nicola D, Zhang S. Specific depletion of resident microglia in the early stage of stroke reduces cerebral ischemic damage. J Neuroinflammation 2021; 18:81. [PMID: 33757565 PMCID: PMC7986495 DOI: 10.1186/s12974-021-02127-w] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/11/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Ischemia can induce rapid activation of microglia in the brain. As key immunocompetent cells, reactive microglia play an important role in pathological development of ischemic stroke. However, the role of activated microglia during the development of ischemia remains controversial. Thus, we aimed to investigate the function of reactive microglia in the early stage of ischemic stroke. METHODS A Rose Bengal photothrombosis model was applied to induce targeted ischemic stroke in mice. CX3CR1CreER:R26iDTR mice were used to specifically deplete resident microglia through intragastric administration of tamoxifen (Ta) and intraperitoneal injection of diphtheria toxin (DT). At day 3 after ischemic stroke, behavioral tests were performed. After that, mouse brains were collected for further histological analysis and detection of mRNA expression of inflammatory factors. RESULTS The results showed that specific depletion of microglia resulted in a significant decrease in ischemic infarct volume and improved performance in motor ability 3 days after stroke. Microglial depletion caused a remarkable reduction in the densities of degenerating neurons and inducible nitric oxide synthase positive (iNOS+) cells. Importantly, depleting microglia induced a significant increase in the mRNA expression level of anti-inflammatory factors TGF-β1, Arg1, IL-10, IL-4, and Ym1 as well as a significant decline of pro-inflammatory factors TNF-α, iNOS, and IL-1β 3 days after stroke. CONCLUSIONS These results suggest that activated microglia is an important modulator of the brain's inflammatory response in stroke, contributing to neurological deficit and infarct expansion. Modulation of the inflammatory response through the elimination of microglia at a precise time point may be a promising therapeutic approach for the treatment of cerebral ischemia.
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Affiliation(s)
- Ting Li
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, Gansu, 730000, People's Republic of China
| | - Jin Zhao
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, Gansu, 730000, People's Republic of China
| | - Wenguang Xie
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, Gansu, 730000, People's Republic of China
| | - Wanru Yuan
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, Gansu, 730000, People's Republic of China
| | - Jing Guo
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, Gansu, 730000, People's Republic of China
| | - Shengru Pang
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, Gansu, 730000, People's Republic of China
| | - Wen-Biao Gan
- Molecular Neurobiology Program, The Kimmel Center for Biology and Medicine of the Skirball Institute, Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, 10016, USA.
| | - Diego Gómez-Nicola
- Centre for Biological Sciences, University of Southampton, South Lab and Path Block, Mail Point 840 LD80C, Southampton General Hospital, Tremona Road, Southampton, SO16 6YD, UK.
| | - Shengxiang Zhang
- Gansu Key Laboratory of Biomonitoring and Bioremediation for Environmental Pollution, School of Life Sciences, Lanzhou University, No. 222 South Tianshui Road, Lanzhou, Gansu, 730000, People's Republic of China.
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Matano Y, Nojiri Y, Nomura M, Masuda A, Moriike Y, Suzuki Y, Umemura K, Nagai N. Repair of brain damage size and recovery of neurological dysfunction after ischemic stroke are different between strains in mice: evaluation using a novel ischemic stroke model. Exp Anim 2021; 70:344-354. [PMID: 33731549 PMCID: PMC8390305 DOI: 10.1538/expanim.20-0182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
In the current study, we established a novel murine ischemic brain damage model using a photochemical reaction to evaluate the recovery of neurological
dysfunction and brain repair reactions. In this model, reproducible damage was induced in the frontal lobe of the cortex, which was accompanied by neurological
dysfunction. Sequential changes in damage size, microglial accumulation, astrocyte activation, and neurological dysfunction were studied in C57BL/6J and BALB/c
mouse strains. Although the initial size of damage was comparable in both strains, the extent of damage was later reduced to a greater extent in C57BL/6J mice
than that in BALB/c mice. In addition, C57BL/6J mice showed later edema clearance until day 7, less microglial accumulation, and relatively more astrocyte
activation on day 7. Neurologic dysfunction was evaluated by three behavioral tests: the von Frey test, the balance beam test, and the tail suspension test. The
behavioral abnormalities evaluated by these tests were remarkable following the induction of damage and recovered by day 21 in both strains. However, the
abnormalities were more prominent and the recovery was later in C57BL/6J mice. These findings demonstrate that our novel ischemic stroke model is useful for
evaluating brain repair reactions and the recovery of neurological dysfunction in mice with different genetic backgrounds. In addition, we found that both the
brain repair reactions and the recovery of neurological dysfunction after comparable ischemic brain damage varied between strains; in that, they both occurred
later in C57BL/6J mice.
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Affiliation(s)
- Yasuki Matano
- Laboratory of Animal Physiology, Division of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Yuuto Nojiri
- Laboratory of Animal Physiology, Division of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Mizuki Nomura
- Laboratory of Animal Physiology, Division of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Akira Masuda
- Laboratory of Animal Physiology, Division of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Yuuki Moriike
- Laboratory of Animal Physiology, Division of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
| | - Yasuhiro Suzuki
- School of Pharmaceutical Sciences, Faculty of Pharmacy, Ohu University, 31-1 Sankaku-do, Tomita-cho, Kohriyama, Fukushima 963-8611, Japan
| | - Kazuo Umemura
- Department of Pharmacology, Hamamatsu University School of Medicine, 1-20-1 Handa-yama, Higashi-ku, Hamamatsu, Shizuoka 431-3125, Japan
| | - Nobuo Nagai
- Laboratory of Animal Physiology, Division of Bioscience, Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama, Shiga 526-0829, Japan
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Barca C, Wiesmann M, Calahorra J, Wachsmuth L, Döring C, Foray C, Heiradi A, Hermann S, Peinado MÁ, Siles E, Faber C, Schäfers M, Kiliaan AJ, Jacobs AH, Zinnhardt B. Impact of hydroxytyrosol on stroke: tracking therapy response on neuroinflammation and cerebrovascular parameters using PET-MR imaging and on functional outcomes. Theranostics 2021; 11:4030-4049. [PMID: 33754046 PMCID: PMC7977466 DOI: 10.7150/thno.48110] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 01/07/2021] [Indexed: 12/14/2022] Open
Abstract
Immune cells have been implicated in influencing stroke outcomes depending on their temporal dynamics, number, and spatial distribution after ischemia. Depending on their activation status, immune cells can have detrimental and beneficial properties on tissue outcome after stroke, highlighting the need to modulate inflammation towards beneficial and restorative immune responses. Novel dietary therapies may promote modulation of pro- and anti-inflammatory immune cell functions. Among the dietary interventions inspired by the Mediterranean diet, hydroxytyrosol (HT), the main phenolic component of the extra virgin olive oil (EVOO), has been suggested to have antioxidant and anti-inflammatory properties in vitro. However, immunomodulatory effects of HT have not yet been studied in vivo after stroke. The aim of this project is therefore to monitor the therapeutic effect of a HT-enriched diet in an experimental stroke model using non-invasive in vivo multimodal imaging, behavioural phenotyping and cross-correlation with ex vivo parameters. Methods: A total of N = 22 male C57BL/6 mice were fed with either a standard chow (n = 11) or a HT enriched diet (n = 11) for 35 days, following a 30 min transient middle cerebral artery occlusion (tMCAo). T2-weighted (lesion) and perfusion (cerebral blood flow)-/diffusion (cellular density)-weighted MR images were acquired at days 1, 3, 7, 14, 21 and 30 post ischemia. [18F]DPA-714 (TSPO, neuroinflammation marker) PET-CT scans were acquired at days 7, 14, 21 and 30 post ischemia. Infarct volume (mm3), cerebral blood flow (mL/100g/min), apparent diffusion coefficient (10-4·mm2/s) and percentage of injected tracer dose (%ID/mL) were assessed. Behavioural tests (grip test, rotarod, open field, pole test) were performed prior and after ischemia to access therapy effects on sensorimotor functions. Ex vivo analyses (IHC, IF, WB) were performed to quantify TSPO expression, immune cells including microglia/macrophages (Iba-1, F4/80), astrocytes (GFAP) and peripheral markers in serum such as thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) 35 days post ischemia. Additionally, gene expression of pro- and anti-inflammatory markers were assessed by rt-qPCR, including tspo, cd163, arg1, tnf and Il-1β. Results: No treatment effect was observed on temporal [18F]DPA-714 uptake within the ischemic and contralateral region (two-way RM ANOVA, p = 0.71). Quantification of the percentage of TSPO+ area by immunoreactivity indicated a slight 2-fold increase in TSPO expression within the infarct region in HT-fed mice at day 35 post ischemia (p = 0.011) correlating with a 2-3 fold increase in Iba-1+ cell population expressing CD163 as anti-inflammatory marker (R2 = 0.80). Most of the GFAP+ cells were TSPO-. Only few F4/80+ cells were observed at day 35 post ischemia in both groups. No significant treatment effect was observed on global ADC and CBF within the infarct and the contralateral region over time. Behavioural tests indicated improved strength of the forepaws at day 14 post ischemia (p = 0.031). Conclusion: An HT-enriched diet significantly increased the number of Iba-1+ microglia/macrophages in the post-ischemic area, inducing higher expression of anti-inflammatory markers while no clear-cut effect was observed. Also, HT did not affect recovery of the cerebrovascular parameters, including ADC and CBF. Altogether, our data indicated that a prolonged dietary intervention with HT, as a single component of the Mediterranean diet, induces molecular changes that may improve stroke outcomes. Therefore, we support the use of the Mediterranean diet as a multicomponent therapy approach after stroke.
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Yang Y, Torbey MT. Angiogenesis and Blood-Brain Barrier Permeability in Vascular Remodeling after Stroke. Curr Neuropharmacol 2020; 18:1250-1265. [PMID: 32691713 PMCID: PMC7770645 DOI: 10.2174/1570159x18666200720173316] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 05/27/2020] [Accepted: 07/11/2020] [Indexed: 11/22/2022] Open
Abstract
Angiogenesis, the growth of new blood vessels, is a natural defense mechanism helping to restore oxygen and nutrient supply to the affected brain tissue following an ischemic stroke. By stimulating vessel growth, angiogenesis may stabilize brain perfusion, thereby promoting neuronal survival, brain plasticity, and neurologic recovery. However, therapeutic angiogenesis after stroke faces challenges: new angiogenesis-induced vessels have a higher than normal permeability, and treatment to promote angiogenesis may exacerbate outcomes in stroke patients. The development of therapies requires elucidation of the precise cellular and molecular basis of the disease. Microenvironment homeostasis of the central nervous system is essential for its normal function and is maintained by the blood-brain barrier (BBB). Tight junction proteins (TJP) form the tight junction (TJ) between vascular endothelial cells (ECs) and play a key role in regulating the BBB permeability. We demonstrated that after stroke, new angiogenesis-induced vessels in peri-infarct areas have abnormally high BBB permeability due to a lack of major TJPs in ECs. Therefore, promoting TJ formation and BBB integrity in the new vessels coupled with speedy angiogenesis will provide a promising and safer treatment strategy for improving recovery from stroke. Pericyte is a central neurovascular unite component in vascular barriergenesis and are vital to BBB integrity. We found that pericytes also play a key role in stroke-induced angiogenesis and TJ formation in the newly formed vessels. Based on these findings, in this article, we focus on regulation aspects of the BBB functions and describe cellular and molecular special features of TJ formation with an emphasis on role of pericytes in BBB integrity during angiogenesis after stroke.
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Affiliation(s)
- Yi Yang
- Department of Neurology, University of New Mexico Health Sciences Center; Albuquerque, New Mexico, 87131, United States
| | - Michel T Torbey
- Department of Neurology, University of New Mexico Health Sciences Center; Albuquerque, New Mexico, 87131, United States
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Assessing the Effects of Cytoprotectants on Selective Neuronal Loss, Sensorimotor Deficit and Microglial Activation after Temporary Middle Cerebral Occlusion. Brain Sci 2019; 9:brainsci9100287. [PMID: 31652564 PMCID: PMC6827002 DOI: 10.3390/brainsci9100287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 10/18/2019] [Accepted: 10/20/2019] [Indexed: 01/21/2023] Open
Abstract
Although early reperfusion after stroke salvages the still-viable ischemic tissue, peri-infarct selective neuronal loss (SNL) can cause sensorimotor deficits (SMD). We designed a longitudinal protocol to assess the effects of cytoprotectants on SMD, microglial activation (MA) and SNL, and specifically tested whether the KCa3.1-blocker TRAM-34 would prevent SNL. Spontaneously hypertensive rats underwent 15 min middle-cerebral artery occlusion and were randomized into control or treatment group, which received TRAM-34 intraperitoneally for 4 weeks starting 12 h after reperfusion. SMD was assessed longitudinally using the sticky-label test. MA was quantified at day 14 using in vivo [11C]-PK111195 positron emission tomography (PET), and again across the same regions-of-interest template by immunofluorescence together with SNL at day 28. SMD recovered significantly faster in the treated group (p = 0.004). On PET, MA was present in 5/6 rats in each group, with no significant between-group difference. On immunofluorescence, both SNL and MA were present in 5/6 control rats and 4/6 TRAM-34 rats, with a non-significantly lower degree of MA but a significantly (p = 0.009) lower degree of SNL in the treated group. These findings document the utility of our longitudinal protocol and suggest that TRAM-34 reduces SNL and hastens behavioural recovery without marked MA blocking at the assessed time-points.
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Spatial Dynamics of Vascular and Biochemical Injury in Rat Hippocampus Following Striatal Injury and Aβ Toxicity. Mol Neurobiol 2018; 56:2714-2727. [DOI: 10.1007/s12035-018-1225-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 07/05/2018] [Indexed: 01/09/2023]
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Zinnhardt B, Wiesmann M, Honold L, Barca C, Schäfers M, Kiliaan AJ, Jacobs AH. In vivo imaging biomarkers of neuroinflammation in the development and assessment of stroke therapies - towards clinical translation. Theranostics 2018; 8:2603-2620. [PMID: 29774062 PMCID: PMC5956996 DOI: 10.7150/thno.24128] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 01/31/2018] [Indexed: 01/01/2023] Open
Abstract
Modulation of the inflammatory microenvironment after stroke opens a new avenue for the development of novel neurorestorative therapies in stroke. Understanding the spatio-temporal profile of (neuro-)inflammatory imaging biomarkers in detail thereby represents a crucial factor in the development and application of immunomodulatory therapies. The early integration of quantitative molecular imaging biomarkers in stroke drug development may provide key information about (i) early diagnosis and follow-up, (ii) spatio-temporal drug-target engagement (pharmacodynamic biomarker), (iii) differentiation of responders and non-responders in the patient cohort (inclusion/exclusion criteria; predictive biomarkers), and (iv) the mechanism of action. The use of targeted imaging biomarkers for may thus allow clinicians to decipher the profile of patient-specific inflammatory activity and the development of patient-tailored strategies for immunomodulatory and neuro-restorative therapies in stroke. Here, we highlight the recent developments in preclinical and clinical molecular imaging biomarkers of neuroinflammation (endothelial markers, microglia, MMPs, cell labeling, future developments) in stroke and outline how imaging biomarkers can be used in overcoming current translational roadblocks and attrition in order to advance new immunomodulatory compounds within the clinical pipeline.
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Affiliation(s)
- Bastian Zinnhardt
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms University Münster, Münster, Germany
- EU 7 th FP Programme “Imaging Inflammation in Neurodegenerative Diseases (INMiND)”
- Cells in Motion (CiM) Cluster of Excellence, University of Münster, Münster, Germany
- PET Imaging in Drug Design and Development (PET3D)
- Department of Nuclear Medicine, Universitätsklinikum Münster, Münster, Germany
| | - Maximilian Wiesmann
- Department of Anatomy, Radboud university medical center, Donders Institute for Brain, Cognition & Behaviour, Nijmegen, The Netherlands
| | - Lisa Honold
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms University Münster, Münster, Germany
| | - Cristina Barca
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms University Münster, Münster, Germany
- PET Imaging in Drug Design and Development (PET3D)
| | - Michael Schäfers
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms University Münster, Münster, Germany
- Cells in Motion (CiM) Cluster of Excellence, University of Münster, Münster, Germany
- Department of Nuclear Medicine, Universitätsklinikum Münster, Münster, Germany
| | - Amanda J Kiliaan
- Department of Anatomy, Radboud university medical center, Donders Institute for Brain, Cognition & Behaviour, Nijmegen, The Netherlands
| | - Andreas H Jacobs
- European Institute for Molecular Imaging (EIMI), Westfälische Wilhelms University Münster, Münster, Germany
- EU 7 th FP Programme “Imaging Inflammation in Neurodegenerative Diseases (INMiND)”
- Cells in Motion (CiM) Cluster of Excellence, University of Münster, Münster, Germany
- PET Imaging in Drug Design and Development (PET3D)
- Department of Geriatrics, Johanniter Hospital, Evangelische Kliniken, Bonn, Germany
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Anttila JE, Whitaker KW, Wires ES, Harvey BK, Airavaara M. Role of microglia in ischemic focal stroke and recovery: focus on Toll-like receptors. Prog Neuropsychopharmacol Biol Psychiatry 2017; 79:3-14. [PMID: 27389423 PMCID: PMC5214845 DOI: 10.1016/j.pnpbp.2016.07.003] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 06/20/2016] [Accepted: 07/02/2016] [Indexed: 12/21/2022]
Abstract
Stroke is the leading cause of disability in adults. Drug treatments that target stroke-induced pathological mechanisms and promote recovery are desperately needed. In the brain, an ischemic event triggers major inflammatory responses that are mediated by the resident microglial cells. In this review, we focus on the microglia activation after ischemic brain injury as a target of immunomodulatory therapeutics. We divide the microglia-mediated events following ischemic stroke into three categories: acute, subacute, and long-term events. This division encompasses the spatial and temporal dynamics of microglia as they participate in the pathophysiological changes that contribute to the symptoms and sequela of a stroke. The importance of Toll-like receptor (TLR) signaling in the outcomes of these pathophysiological changes is highlighted. Increasing evidence shows that microglia have a complex role in stroke pathophysiology, and they mediate both detrimental and beneficial effects on stroke outcome. So far, most of the pharmacological studies in experimental models of stroke have focused on neuroprotective strategies which are impractical for clinical applications. Post-ischemic inflammation is long lasting and thus, could provide a therapeutic target for novel delayed drug treatment. However, more studies are needed to elucidate the role of microglia in the recovery process from an ischemic stroke and to evaluate the therapeutic potential of modulating post-ischemic inflammation to promote functional recovery.
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Affiliation(s)
- Jenni E Anttila
- Institute of Biotechnology, P.O. Box 56, 00014, University of Helsinki, Finland
| | - Keith W Whitaker
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD, USA; Human Research and Engineering Directorate, US Army Research Laboratory, Aberdeen, Proving Ground, MD 21005, USA
| | - Emily S Wires
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD, USA
| | - Brandon K Harvey
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD, USA
| | - Mikko Airavaara
- Institute of Biotechnology, P.O. Box 56, 00014, University of Helsinki, Finland.
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Abstract
PURPOSE OF REVIEW This article provides an overview of the recent literature regarding the application of in-vivo brain imaging techniques to animal models of ischemic stroke. RECENT FINDINGS Major breakthroughs concerned the effects of sensory stimulation on neuronal function, local hemodynamics, and tissue outcome in the hyperacute phase of stroke; the novel application to stroke of hybrid scanners allowing simultaneous PET and magnetic resonance; the refinements of magnetic resonance-based oxygen imaging, allowing to map the ischemic penumbra in a completely noninvasive way; the implementation of new PET ligands to selectively map poststroke neuronal death and neuroinflammation; and the use of novel mesoscale imaging techniques to demonstrate the major role of interhemispheric connectivity in poststroke plasticity and functional recovery. SUMMARY The array of techniques to map in vivo the key pathophysiological brain processes involved in stroke is currently enlarging at an amazing pace. This is paralleled by ever-increasing sophistication in postprocessing tools. The combination of techniques allowing simultaneous access to several variables is particularly powerful as it affords unprecedented insights into the intimate processes underlying the tissue and neuronal changes that follow a stroke. These major leaps forward will hopefully lead to therapeutic breakthroughs aiming at improving functional outcome after stroke.
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14
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Janssen B, Vugts DJ, Funke U, Molenaar GT, Kruijer PS, van Berckel BNM, Lammertsma AA, Windhorst AD. Imaging of neuroinflammation in Alzheimer's disease, multiple sclerosis and stroke: Recent developments in positron emission tomography. Biochim Biophys Acta Mol Basis Dis 2015; 1862:425-41. [PMID: 26643549 DOI: 10.1016/j.bbadis.2015.11.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/09/2015] [Accepted: 11/19/2015] [Indexed: 12/13/2022]
Abstract
Neuroinflammation is thought to play a pivotal role in many diseases affecting the brain, including Alzheimer's disease, multiple sclerosis and stroke. Neuroinflammation is characterised predominantly by microglial activation, which can be visualised using positron emission tomography (PET). Traditionally, translocator protein 18kDa (TSPO) is the target for imaging of neuroinflammation using PET. In this review, recent preclinical and clinical research using PET in Alzheimer's disease, multiple sclerosis and stroke is summarised. In addition, new molecular targets for imaging of neuroinflammation, such as monoamine oxidases, adenosine receptors and cannabinoid receptor type 2, are discussed. This article is part of a Special Issue entitled: Neuro Inflammation edited by Helga E. de Vries and Markus Schwaninger.
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Affiliation(s)
- Bieneke Janssen
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
| | - Danielle J Vugts
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Uta Funke
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands; BV Cyclotron VU, Amsterdam, The Netherlands
| | - Ger T Molenaar
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands; BV Cyclotron VU, Amsterdam, The Netherlands
| | | | - Bart N M van Berckel
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Adriaan A Lammertsma
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands
| | - Albert D Windhorst
- Department of Radiology & Nuclear Medicine, VU University Medical Center, Amsterdam, The Netherlands.
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15
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Attenuation of acute stroke injury in rat brain by minocycline promotes blood-brain barrier remodeling and alternative microglia/macrophage activation during recovery. J Neuroinflammation 2015; 12:26. [PMID: 25889169 PMCID: PMC4340283 DOI: 10.1186/s12974-015-0245-4] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 01/11/2015] [Indexed: 12/20/2022] Open
Abstract
Background Minocycline reduces reperfusion injury by inhibiting matrix metalloproteinases (MMPs) and microglia activity after cerebral ischemia. Prior studies of minocycline investigated short-term neuroprotective effects during subacute stage of stroke; however, the late effects of minocycline against early reperfusion injury on neurovascular remodeling are less well studied. We have shown that spontaneous angiogenesis vessels in ischemic brain regions have high blood–brain barrier (BBB) permeability due to lack of major tight junction proteins (TJPs) in endothelial cells at three weeks. In the present study, we longitudinally investigated neurological outcome, neurovascular remodeling and microglia/macrophage alternative activation after spontaneous and minocycline-induced stroke recovery. Methods Adult spontaneously hypertensive rats had a 90 minute transient middle cerebral artery occlusion. At the onset of reperfusion they received a single dose of minocycline (3 mg/kg intravenously) or a vehicle. They were studied at multiple time points up to four weeks with magnetic resonance imaging (MRI), immunohistochemistry and biochemistry. Results Minocycline significantly reduced the infarct size and prevented tissue loss in the ischemic hemispheres compared to vehicle-treated rats from two to four weeks as measured with MRI. Cerebral blood flow measured with arterial spin labeling (ASL) showed that minocycline improved perfusion. Dynamic contrast-enhanced MRI indicated that minocycline reduced BBB permeability accompanied with higher levels of TJPs measured with Western blot. Increased MMP-2 and −3 were detected at four weeks. Active microglia/macrophage, surrounding and within the peri-infarct areas, expressed YM1, a marker of M2 microglia/macrophage activation, at four weeks. These microglia/macrophage expressed both pro-inflammatory factors tumor necrosis factors-α (TNF-α) and interleukin-1β (IL-1β) and anti-inflammatory factors transforming growth factor-β (TGF-β) and interleukin-10 (IL-10). Treatment with minocycline significantly reduced levels of TNF-α and IL-1β, and increased levels of TGF-β, IL-10 and YM1. Conclusions Early minocycline treatment against reperfusion injury significantly promotes neurovascular remodeling during stroke recovery by reducing brain tissue loss, enhancing TJP expression in ischemic brains and facilitating neuroprotective phenotype alternative activation of microglia/macrophages. Electronic supplementary material The online version of this article (doi:10.1186/s12974-015-0245-4) contains supplementary material, which is available to authorized users.
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16
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Wang Y, Yue X, Kiesewetter DO, Wang Z, Lu J, Niu G, Teng G, Chen X. [(18)F]DPA-714 PET imaging of AMD3100 treatment in a mouse model of stroke. Mol Pharm 2014; 11:3463-70. [PMID: 25157648 PMCID: PMC4186675 DOI: 10.1021/mp500234d] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
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Chemokine
receptor 4 and stromal-cell-derived factor 1 have been
found to be related to the initiation of neuroinflammation in ischemic
brain. Herein, we aimed to monitor the changes of neuorinflammation
after AMD3100 treatment using a translocator protein (TSPO) specific
PET tracer in a mouse model of stroke. The transient MCAO model was
established with Balb/C mice. The success of the model was confirmed
by magnetic resonance imaging and FDG PET. The treatment started the
same day after surgery via daily intraperitoneal injection of 1 mg
of AMD3100/kg for three consecutive days. [18F]DPA-714
was used as the TSPO imaging tracer. In vivo PET
was performed at different time points after surgery in both control
and treated mice. Ex vivo histological and immunofluorescence
staining of brain slices was performed to confirm the lesion site
and inflammatory cell activation. The TSPO level was also evaluated
using Western blotting. Longitudinal PET scans revealed that the level
of [18F]DPA-714 uptake was significantly increased in the
ischemic brain area with a peak accumulation at around day 10 after
surgery, and the level of uptake remained high until day 16. The in vivo PET data were consistent with those from ex vivo immunofluorescence staining. After AMD3100 treatment,
the signal intensity was significantly decreased compared with that
of normal saline-treated control group. In conclusion, TSPO-targeted
PET imaging using [18F]DPA-714 can be used to monitor inflammatory
response after stroke and provide a useful method for evaluating the
efficacy of anti-inflammation treatment.
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Affiliation(s)
- Yu Wang
- Jiangsu Key Laboratory of Molecular Imaging and Functional Imaging, Department of Radiology, Zhongda Hospital, Medical School of Southeast University , Nanjing 210009, China
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