Person: Aguirre, Aaron
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Aguirre
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Aaron
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Aguirre, Aaron
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Publication Identifying Early Changes in Myocardial Microstructure in Hypertensive Heart Disease(Public Library of Science, 2014) Hiremath, Pranoti; Bauer, Michael; Aguirre, Aaron; Cheng, Hui-Wen; Unno, Kazumasa; Patel, Ravi B.; Harvey, Bethany W.; Chang, Wei-Ting; Groarke, John; Liao, Ronglih; Cheng, SusanThe transition from healthy myocardium to hypertensive heart disease is characterized by a series of poorly understood changes in myocardial tissue microstructure. Incremental alterations in the orientation and integrity of myocardial fibers can be assessed using advanced ultrasonic image analysis. We used a modified algorithm to investigate left ventricular myocardial microstructure based on analysis of the reflection intensity at the myocardial-pericardial interface on B-mode echocardiographic images. We evaluated the extent to which the novel algorithm can differentiate between normal myocardium and hypertensive heart disease in humans as well as in a mouse model of afterload resistance. The algorithm significantly differentiated between individuals with uncomplicated essential hypertension (N = 30) and healthy controls (N = 28), even after adjusting for age and sex (P = 0.025). There was a trend in higher relative wall thickness in hypertensive individuals compared to controls (P = 0.08), but no difference between groups in left ventricular mass (P = 0.98) or total wall thickness (P = 0.37). In mice, algorithm measurements (P = 0.026) compared with left ventricular mass (P = 0.053) more clearly differentiated between animal groups that underwent fixed aortic banding, temporary aortic banding, or sham procedure, on echocardiography at 7 weeks after surgery. Based on sonographic signal intensity analysis, a novel imaging algorithm provides an accessible, non-invasive measure that appears to differentiate normal left ventricular microstructure from myocardium exposed to chronic afterload stress. The algorithm may represent a particularly sensitive measure of the myocardial changes that occur early in the course of disease progression.Publication New techniques for motion-artifact-free in vivo cardiac microscopy(Frontiers Media S.A., 2015) Vinegoni, Claudio; Lee, Sungon; Aguirre, Aaron; Weissleder, RalphIntravital imaging microscopy (i.e., imaging in live animals at microscopic resolution) has become an indispensable tool for studying the cellular micro-dynamics in cancer, immunology and neurobiology. High spatial and temporal resolution, combined with large penetration depth and multi-reporter visualization capability make fluorescence intravital microscopy compelling for heart imaging. However, tissue motion caused by cardiac contraction and respiration critically limits its use. As a result, in vitro cell preparations or non-contracting explanted heart models are more commonly employed. Unfortunately, these approaches fall short of understanding the more complex host physiology that may be dynamic and occur over longer periods of time. In this review, we report on novel technologies, which have been recently developed by our group and others, aimed at overcoming motion-induced artifacts and capable of providing in vivo subcellular resolution imaging in the beating mouse heart. The methods are based on mechanical stabilization, image processing algorithms, gated/triggered acquisition schemes or a combination of both. We expect that in the immediate future all these methodologies will have considerable applications in expanding our understanding of the cardiac biology, elucidating cardiomyocyte function and interactions within the organism in vivo, and ultimately improving the treatment of cardiac diseases.Publication IRF3 and type I interferons fuel a fatal response to myocardial infarction(Springer Nature, 2017) King, Kevin R; Aguirre, Aaron; Ye, Yu-Xiang; Sun, Yuan; Roh, Jason; Ng, Richard; Kohler, Rainer; Arlauckas, Sean; Iwamoto, Yoshiko; Savol, Andrej J; Sadreyev, Ruslan; Kelly, Mark; Fitzgibbons, Timothy P; Fitzgerald, Katherine A; Mitchison, Timothy; Libby, Peter; Nahrendorf, Matthias; Weissleder, RalphInterferon regulatory factor 3 (IRF3) and type I interferons (IFNs) protect against infections and cancer, but excessive IRF3 activation and type I IFN production cause autoinflammatory conditions such as Aicardi–Goutières syndrome and STING-associated vasculopathy of infancy (SAVI)3. Myocardial infarction (MI) elicits inflammation5, but the dominant molecular drivers of MI-associated inflammation remain unclear. Here we show that ischemic cell death and uptake of cell debris by macrophages in the heart fuel a fatal response to MI by activating IRF3 and type I IFN production. In mice, single-cell RNA-seq analysis of 4,215 leukocytes isolated from infarcted and non-infarcted hearts showed that MI provokes activation of an IRF3–interferon axis in a distinct population of interferon-inducible cells (IFNICs) that were classified as cardiac macrophages. Mice genetically deficient in cyclic GMP-AMP synthase (cGAS), its adaptor STING, IRF3, or the type I IFN receptor IFNAR exhibited impaired interferon-stimulated gene (ISG) expression and, in the case of mice deficient in IRF3 or IFNAR, improved survival after MI as compared to controls. Interruption of IRF3-dependent signaling resulted in decreased cardiac expression of inflammatory cytokines and chemokines and decreased inflammatory cell infiltration of the heart, as well as in attenuated ventricular dilation and improved cardiac function. Similarly, treatment of mice with an IFNAR-neutralizing antibody after MI ablated the interferon response and improved left ventricular dysfunction and survival. These results identify IRF3 and the type I IFN response as a potential therapeutic target for post-MI cardioprotection.Publication Polyglucose nanoparticles with renal elimination and macrophage avidity facilitate PET imaging in ischaemic heart disease(Nature Publishing Group, 2017) Keliher, Edmund J.; Ye, Yu-Xiang; Wojtkiewicz, Gregory R.; Aguirre, Aaron; Tricot, Benoit; Senders, Max L.; Groenen, Hannah; Fay, Francois; Perez-Medina, Carlos; Calcagno, Claudia; Carlucci, Giuseppe; Reiner, Thomas; Sun, Yuan; Courties, Gabriel; Iwamoto, Yoshiko; Kim, Hye-Yeong; Wang, Cuihua; Chen, John; Swirski, Filip; Wey, Hsiao-Ying; Hooker, Jacob; Fayad, Zahi A.; Mulder, Willem J. M.; Weissleder, Ralph; Nahrendorf, MatthiasTissue macrophage numbers vary during health versus disease. Abundant inflammatory macrophages destruct tissues, leading to atherosclerosis, myocardial infarction and heart failure. Emerging therapeutic options create interest in monitoring macrophages in patients. Here we describe positron emission tomography (PET) imaging with 18F-Macroflor, a modified polyglucose nanoparticle with high avidity for macrophages. Due to its small size, Macroflor is excreted renally, a prerequisite for imaging with the isotope flourine-18. The particle's short blood half-life, measured in three species, including a primate, enables macrophage imaging in inflamed cardiovascular tissues. Macroflor enriches in cardiac and plaque macrophages, thereby increasing PET signal in murine infarcts and both mouse and rabbit atherosclerotic plaques. In PET/magnetic resonance imaging (MRI) experiments, Macroflor PET imaging detects changes in macrophage population size while molecular MRI reports on increasing or resolving inflammation. These data suggest that Macroflor PET/MRI could be a clinical tool to non-invasively monitor macrophage biology.Publication Clinical Predictors for Lack of Favorable Vascular Response to Statin Therapy in Patients With Coronary Artery Disease: A Serial Optical Coherence Tomography Study(John Wiley and Sons Inc., 2017) Minami, Yoshiyasu; Wang, Zhao; Aguirre, Aaron; Ong, Daniel S.; Kim, Chong‐Jin; Uemura, Shiro; Soeda, Tsunenari; Lee, Hang; Fujimoto, James; Jang, Ik‐KyungBackground: Previous studies have demonstrated that statin therapy improves cardiac outcomes, probably by stabilizing thin‐cap fibroatheroma in patients with coronary artery disease. However, major adverse cardiac events still occur in some patients, despite statin therapy. The aim of this study is to identify clinical predictors for the lack of a favorable vascular response to statin therapy in patients with coronary artery disease. Methods and Results: A total of 140 nonculprit plaques from 84 patients with coronary artery disease who were treated with a statin and had serial optical coherence tomography imaging (median interval, 6.3 months) were included. Thin‐cap area (fibrous cap thickness, <200 μm) was measured using a novel 3‐dimensional computer‐aided algorithm. Overall, the thin‐cap area significantly decreased from baseline (median, 2.852 mm2; 25th–75th percentile, 1.023–6.157 mm2) to follow‐up (median, 1.210 mm2; 25th–75th percentile, 0.250–3.192 mm2; P<0.001), and low‐density lipoprotein cholesterol significantly decreased from baseline (mean±SD, 92.9±30.1 mg/dL) to follow‐up (mean±SD, 76.3±23.3 mg/dL; P<0.001). The general linear model with multiple predictor variables revealed that the thin‐cap area was significantly higher in patients with chronic kidney disease than in those without it (regression coefficient b, 1.691 mm2; 95% confidence interval, 0.350–3.033 mm2; P=0.013) and lower in patients with acute coronary syndrome (regression coefficient b, −1.535 mm2; 95% confidence interval, −2.561 to −0.509 mm2; P=0.003). Conclusions: Chronic kidney disease is an independent predictor for the lack of a favorable vascular response to statin therapy, whereas acute coronary syndrome is an independent predictor for favorable vascular response to statin therapy. These findings should be further warranted in future prospective studies. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT01110538.