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Near Infrared Fluorescence (NIRF) Molecular Imaging of Oxidized LDL with an Autoantibody in Experimental Atherosclerosis.

ABSTRACT: We aimed to develop a quantitative antibody-based near infrared fluorescence (NIRF) approach for the imaging of oxidized LDL in atherosclerosis. LO1, a well- characterized monoclonal autoantibody that reacts with malondialdehyde-conjugated LDL, was labeled with a NIRF dye to yield LO1-750. LO1-750 specifically identified necrotic core in ex vivo human coronary lesions. Injection of LO1-750 into high fat (HF) fed atherosclerotic Ldlr(-/-) mice led to specific focal localization within the aortic arch and its branches, as detected by fluorescence molecular tomography (FMT) combined with micro-computed tomography (CT). Ex vivo confocal microscopy confirmed LO1-750 subendothelial localization of LO1-750 at sites of atherosclerosis, in the vicinity of macrophages. When compared with a NIRF reporter of MMP activity (MMPSense-645-FAST), both probes produced statistically significant increases in NIRF signal in the Ldlr(-/-) model in relation to duration of HF diet. Upon withdrawing the HF diet, the reduction in oxLDL accumulation, as demonstrated with LO1-750, was less marked than the effect seen on MMP activity. In the rabbit, in vivo injected LO1-750 localization was successfully imaged ex vivo in aortic lesions with a customised intra-arterial NIRF detection catheter. A partially humanized chimeric LO1-Fab-Cys localized similarly to the parent antibody in murine atheroma showing promise for future translation.

SUBMITTER: Khamis RY

PROVIDER: S-EPMC4766560 | biostudies-literature | 2016 Feb

REPOSITORIES: biostudies-literature

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Near Infrared Fluorescence (NIRF) Molecular Imaging of Oxidized LDL with an Autoantibody in Experimental Atherosclerosis.

Khamis Ramzi Y RY Woollard Kevin J KJ Hyde Gareth D GD Boyle Joseph J JJ Bicknell Colin C Chang Shang-Hung SH Malik Talat H TH Hara Tetsuya T Mauskapf Adam A Granger David W DW Johnson Jason L JL Ntziachristos Vasilis V Matthews Paul M PM Jaffer Farouc A FA Haskard Dorian O DO

Scientific reports 20160225

We aimed to develop a quantitative antibody-based near infrared fluorescence (NIRF) approach for the imaging of oxidized LDL in atherosclerosis. LO1, a well- characterized monoclonal autoantibody that reacts with malondialdehyde-conjugated LDL, was labeled with a NIRF dye to yield LO1-750. LO1-750 specifically identified necrotic core in ex vivo human coronary lesions. Injection of LO1-750 into high fat (HF) fed atherosclerotic Ldlr(-/-) mice led to specific focal localization within the aortic ...[more]

PMID: 26911995

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Project description:This study sought to determine whether indocyanine green (ICG)-enhanced near-infrared fluorescence (NIRF) imaging can illuminate high-risk histologic plaque features of human carotid atherosclerosis, and in coronary atheroma of living swine, using intravascular NIRF-optical coherence tomography (OCT) imaging.New translatable imaging approaches are needed to identify high-risk biological signatures of atheroma. ICG is a U.S. Food and Drug Administration-approved NIRF imaging agent that experimentally targets plaque macrophages and lipid in areas of enhanced endothelial permeability. However, it is unknown whether ICG can target atheroma in patients.Eight patients were enrolled in the BRIGHT-CEA (Indocyanine Green Fluorescence Uptake in Human Carotid Artery Plaque) trial. Five patients were injected intravenously with ICG 99 ± 25 min before clinically indicated carotid endarterectomy. Three saline-injected endarterectomy patients served as control subjects. Excised plaques underwent analysis by intravascular NIRF-OCT, reflectance imaging, microscopy, and histopathology. Next, following ICG intravenous injection, in vivo intracoronary NIRF-OCT and intravascular ultrasound imaged 3 atheroma-bearing coronary arteries of a diabetic, cholesterol-fed swine.ICG was well tolerated; no adverse clinical events occurred up to 30 days post-injection. Multimodal NIRF imaging including intravascular NIRF-OCT revealed that ICG accumulated in all endarterectomy specimens. Plaques from saline-injected control patients exhibited minimal NIRF signal. In the swine experiment, intracoronary NIRF-OCT identified ICG uptake in all intravascular ultrasound-identified plaques in vivo. On detailed microscopic evaluation, ICG localized to plaque areas exhibiting impaired endothelial integrity, including disrupted fibrous caps, and within areas of neovascularization. Within human plaque areas of endothelial abnormality, ICG was spatially related to localized zones of plaque macrophages and lipid, and, notably, intraplaque hemorrhage.This study demonstrates that ICG targets human plaques exhibiting endothelial abnormalities and provides new insights into its targeting mechanisms in clinical and experimental atheroma. Intracoronary NIRF-OCT of ICG may offer a novel, clinically translatable approach to image pathobiological aspects of coronary atherosclerosis. (Indocyanine Green Fluorescence Uptake in Human Carotid Artery Plaque [BRIGHT-CEA]; NCT01873716).

Project description:This study sought to develop a 2-dimensional (2D) intravascular near-infrared fluorescence (NIRF) imaging strategy for investigation of arterial inflammation in coronary-sized vessels.Molecular imaging of arterial inflammation could provide new insights into the pathogenesis of acute myocardial infarction stemming from coronary atheromata and implanted stents. Presently, few high-resolution approaches can image inflammation in coronary-sized arteries in vivo.A new 2.9-F rotational, automated pullback 2D imaging catheter was engineered and optimized for 360° viewing intravascular NIRF imaging. In conjunction with the cysteine protease-activatable imaging reporter Prosense VM110 (VisEn Medical, Woburn, Massachusetts), intra-arterial 2D NIRF imaging was performed in rabbit aortas with atherosclerosis (n =10) or implanted coronary bare-metal stents (n = 10, 3.5-mm diameter, day 7 post-implantation). Intravascular ultrasound provided coregistered anatomical images of arteries. After sacrifice, specimens underwent ex vivo NIRF imaging, fluorescence microscopy, and histological and immunohistochemical analyses.Imaging of coronary artery-scaled phantoms demonstrated 8-sector angular resolution and submillimeter axial resolution, nanomolar sensitivity to NIR fluorochromes, and modest NIRF light attenuation through blood. High-resolution NIRF images of vessel wall inflammation with signal-to-noise ratios >10 were obtained in real-time through blood, without flushing or occlusion. In atherosclerosis, 2D NIRF, intravascular ultrasound-NIRF fusion, microscopy, and immunoblotting studies provided insight into the spatial distribution of plaque protease activity. In stent-implanted vessels, real-time imaging illuminated an edge-based pattern of stent-induced arterial inflammation.A new 2D intravascular NIRF imaging strategy provides high-resolution in vivo spatial mapping of arterial inflammation in coronary-sized arteries and reveals increased inflammation-regulated cysteine protease activity in atheromata and stent-induced arterial injury.

Project description:PURPOSE:Near-infrared fluorescence (NIRF) imaging has been widely used in preclinical studies; however, its low tissue penetration represents a daunting problem for translational clinical imaging of neurodegenerative diseases. The retina is known as an extension of the central nerve system (CNS), and it is widely considered as a window to the brain. Therefore, the retina can be considered as an alternative organ for investigating neurodegenerative diseases, and an eye represents an ideal NIRF imaging organ, due to its minimal opacity. PROCEDURES:NIRF ocular imaging (NIRFOI), for the first time, was explored for imaging of Alzheimer's disease (AD) via utilizing "smart" fluorescent probes CRANAD-X (X = - 2, - 3, - 30, - 58, and - 102) for amyloid beta (Aβ), and CRANAD-61 for reactive oxygen species (ROS). Mice were intravenously injected the fluorescence dyes and images from the eyes were captured with an IVIS imaging system at different time points. RESULTS:All of the tested NIRF probes could be used to differentiate transgenic AD mice and WT mice, and NIRFOI could provide much higher sensitivity for imaging Aβs than NIRF brain imaging did. Our data suggested that NIRFOI could capture the imaging signals from both soluble and insoluble Aβ species. Moreover, we demonstrated that NIRFOI with CRANAD-102 could be used to monitor the therapeutic effects of BACE-1 inhibitor LY2811376. Compared to NIRF brain imaging, NIRFOI provided a larger change of Aβ levels before and after LY2811376 treatment. In addition, we demonstrated that CRANAD-61 could be used to image reactive oxygen species in the eyes. CONCLUSION:The large detection margin by NIRFOI is very important for both diagnosis and therapy response monitoring. Compared to fluorescence microscopic imaging, NIRFOI captures signals with a wide angle (large field of view (FOV)) and can be used to detect soluble Aβs. We believe that NIRFOI has remarkable translational potential for future human studies and can be a potential imaging technology for fast, cheap, accessible, and reliable screening of AD in the future.

Dataset Information

Near Infrared Fluorescence (NIRF) Molecular Imaging of Oxidized LDL with an Autoantibody in Experimental Atherosclerosis.

Publications

Near Infrared Fluorescence (NIRF) Molecular Imaging of Oxidized LDL with an Autoantibody in Experimental Atherosclerosis.

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