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Jolly AA, Brown RB, Tozer DJ, Hong YT, Fryer TD, Aigbirhio FI, O'Brien JT, Markus HS. Are central and systemic inflammation associated with fatigue in cerebral small vessel disease? Int J Stroke 2024:17474930241245613. [PMID: 38533609 DOI: 10.1177/17474930241245613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
BACKGROUND Fatigue is a common symptom in cerebral small vessel disease (SVD), but its pathogenesis is poorly understood. It has been suggested that inflammation may play a role. We determined whether central (neuro) inflammation and peripheral inflammation were associated with fatigue in SVD. METHODS Notably, 36 patients with moderate-to-severe SVD underwent neuropsychometric testing, combined positron emission tomography and magnetic resonance imaging (PET-MRI) scan, and blood draw for the analysis of inflammatory blood biomarkers. Microglial signal was taken as a proxy for neuroinflammation, assessed with radioligand 11C-PK11195. Of these, 30 subjects had full PET datasets for analysis. We assessed global 11C-PK11195 binding and hotspots of 11C-PK11195 binding in the normal-appearing white matter, lesioned tissue, and combined total white matter. Peripheral inflammation was assessed with serum C-reactive protein (CRP) and using the Olink cardiovascular III proteomic panel comprising 92 biomarkers of cardiovascular inflammation and endothelial activation. Fatigue was assessed using the fatigue severity scale (FSS), the visual analog fatigue scale, and a subscale of the Geriatric Depression Scale. RESULTS Mean (SD) age was 68.7 (11.2) years, and 63.9% were male. Of these, 55.6% showed fatigue on the FSS. Fatigued participants had higher disability scores (p = 0.02), higher total GDS scores (p = 0.02), and more commonly reported a history of depression (p = 0.04). 11C-PK11195 ligand binding in the white matter was not associated with any measure of fatigue. Serum CRP was significantly associated with average fatigue score on FSS (ρ = 0.48, p = 0.004); this association persisted when controlling for age, sex, disability score, and depression (β = 0.49, 95% CI (0.17, 2.26), p = 0.03). Blood biomarkers from the Olink panel showed no association with fatigue. CONCLUSION In symptomatic SVD patients, neuroinflammation, assessed with microglial marker 11C-PK11195, was not associated with fatigue. We found some evidence for a role of systematic inflammation, evidenced by an association between fatigue severity and raised CRP, but further studies are required to understand this relationship and inform whether it could be therapeutically modified to reduce fatigue severity. DATA ACCESS STATEMENT Data for this study are available from the corresponding author upon reasonable request.
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Affiliation(s)
- Amy A Jolly
- Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Robin B Brown
- Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Daniel J Tozer
- Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Young T Hong
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Tim D Fryer
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Franklin I Aigbirhio
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - John T O'Brien
- Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Hugh S Markus
- Stroke Research Group, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
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Carlson ML, Jackson IM, Azevedo EC, Reyes ST, Alam IS, Kellow R, Castillo JB, Nagy SC, Sharma R, Brewer M, Cleland J, Shen B, James ML. Development and Initial Assessment of [ 18F]OP-801: a Novel Hydroxyl Dendrimer PET Tracer for Preclinical Imaging of Innate Immune Activation in the Whole Body and Brain. Mol Imaging Biol 2023; 25:1063-1072. [PMID: 37735280 DOI: 10.1007/s11307-023-01850-5] [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: 07/25/2023] [Revised: 07/25/2023] [Accepted: 08/09/2023] [Indexed: 09/23/2023]
Abstract
PURPOSE Innate immune activation plays a critical role in the onset and progression of many diseases. While positron emission tomography (PET) imaging provides a non-invasive means to visualize and quantify such immune responses, most available tracers are not specific for innate immune cells. To address this need, we developed [18F]OP-801 by radiolabeling a novel hydroxyl dendrimer that is selectively taken up by reactive macrophages/microglia and evaluated its ability to detect innate immune activation in mice following lipopolysaccharide (LPS) challenge. PROCEDURES OP-801 was radiolabeled in two steps: [18F]fluorination of a tosyl precursor to yield [18F]3-fluoropropylazide, followed by a copper-catalyzed click reaction. After purification and stability testing, [18F]OP-801 (150-250 μCi) was intravenously injected into female C57BL/6 mice 24 h after intraperitoneal administration of LPS (10 mg/kg, n=14) or saline (n=6). Upon completing dynamic PET/CT imaging, mice were perfused, and radioactivity was measured in tissues of interest via gamma counting or autoradiography. RESULTS [18F]OP-801 was produced with >95% radiochemical purity, 12-52 μCi/μg specific activity, and 4.3±1.5% decay-corrected yield. Ex vivo metabolite analysis of plasma samples (n=4) demonstrated high stability in mice (97±3% intact tracer >120 min post-injection). PET/CT images of mice following LPS challenge revealed higher signal in organs known to be inflamed in this context, including the liver, lung, and spleen. Gamma counting confirmed PET findings, showing significantly elevated signal in the same tissues compared to saline-injected mice: the liver (p=0.009), lung (p=0.030), and spleen (p=0.004). Brain PET/CT images (summed 50-60 min) revealed linearly increasing [18F]OP-801 uptake in the whole brain that significantly correlated with murine sepsis score (r=0.85, p<0.0001). Specifically, tracer uptake was significantly higher in the brain stem, cortex, olfactory bulb, white matter, and ventricles of LPS-treated mice compared to saline-treated mice (p<0.05). CONCLUSION [18F]OP-801 is a promising new PET tracer for sensitive and specific detection of activated macrophages and microglia that warrants further investigation.
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Affiliation(s)
| | - Isaac M Jackson
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - E Carmen Azevedo
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - Samantha T Reyes
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - Israt S Alam
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - Rowaid Kellow
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - Jessa B Castillo
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - Sydney C Nagy
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - Rishi Sharma
- Ashvattha Therapeutics, Inc., Redwood City, CA, USA
| | | | | | - Bin Shen
- Department of Radiology at Stanford University, Stanford, CA, USA
| | - Michelle L James
- Department of Radiology at Stanford University, Stanford, CA, USA.
- Department of Neurology and Neurological Sciences at Stanford University, Stanford, CA, USA.
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Altomonte S, Pike VW. Candidate Tracers for Imaging Colony-Stimulating Factor 1 Receptor in Neuroinflammation with Positron Emission Tomography: Issues and Progress. ACS Pharmacol Transl Sci 2023; 6:1632-1650. [PMID: 37974622 PMCID: PMC10644394 DOI: 10.1021/acsptsci.3c00213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Indexed: 11/19/2023]
Abstract
The tyrosine kinase, colony-stimulating factor 1 receptor (CSF1R), has attracted attention as a potential biomarker of neuroinflammation for imaging studies with positron emission tomography (PET), especially because of its location on microglia and its role in microglia proliferation. The development of an effective radiotracer for specifically imaging and quantifying brain CSF1R is highly challenging. Here we review the progress that has been made on PET tracer development and discuss issues that have arisen and which remain to be addressed and resolved.
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Affiliation(s)
- Stefano Altomonte
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes
of Health, Building 10,
B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
| | - Victor W. Pike
- Molecular Imaging Branch, National Institute of Mental Health, National Institutes
of Health, Building 10,
B3 C346A, 10 Center Drive, Bethesda, Maryland 20892, United States
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Jackson IM, Webb EW, Scott PJ, James ML. In Silico Approaches for Addressing Challenges in CNS Radiopharmaceutical Design. ACS Chem Neurosci 2022; 13:1675-1683. [PMID: 35606334 PMCID: PMC9945852 DOI: 10.1021/acschemneuro.2c00269] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Positron emission tomography (PET) is a highly sensitive and versatile molecular imaging modality that leverages radiolabeled molecules, known as radiotracers, to interrogate biochemical processes such as metabolism, enzymatic activity, and receptor expression. The ability to probe specific molecular and cellular events longitudinally in a noninvasive manner makes PET imaging a particularly powerful technique for studying the central nervous system (CNS) in both health and disease. Unfortunately, developing and translating a single CNS PET tracer for clinical use is typically an extremely resource-intensive endeavor, often requiring synthesis and evaluation of numerous candidate molecules. While existing in vitro methods are beginning to address the challenge of derisking molecules prior to costly in vivo PET studies, most require a significant investment of resources and possess substantial limitations. In the context of CNS drug development, significant time and resources have been invested into the development and optimization of computational methods, particularly involving machine learning, to streamline the design of better CNS therapeutics. However, analogous efforts developed and validated for CNS radiotracer design are conspicuously limited. In this Perspective, we overview the requirements and challenges of CNS PET tracer design, survey the most promising computational methods for in silico CNS drug design, and bridge these two areas by discussing the potential applications and impact of computational design tools in CNS radiotracer design.
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Affiliation(s)
- Isaac M. Jackson
- Department of Radiology, Stanford University, Stanford, CA 94305
| | - E. William Webb
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109
| | - Peter J.H. Scott
- Department of Radiology, University of Michigan, Ann Arbor, MI 48109;,Corresponding Authors: Peter J. H. Scott − Department of Radiology, University of Michigan, Ann Arbor, MI 48109, United States; , Michelle L. James − Departments of Radiology, and Neurology & Neurological Sciences, 1201 Welch Rd., P-206, Stanford, CA 94305-5484, United States;
| | - Michelle L. James
- Department of Radiology, Stanford University, Stanford, CA 94305;,Department of Neurology & Neurological Sciences, Stanford University, Stanford, CA 94304.,Corresponding Authors: Peter J. H. Scott − Department of Radiology, University of Michigan, Ann Arbor, MI 48109, United States; , Michelle L. James − Departments of Radiology, and Neurology & Neurological Sciences, 1201 Welch Rd., P-206, Stanford, CA 94305-5484, United States;
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