Yohana Camila Toner

In Chapter II, DOTATATE was extensively evaluated as a diagnostic probe for cardiovascular inflammation. Its affinity for the somatostatin receptor subtype 2, abundant on macrophages, makes it a promising PET tracer for macrophage imaging. DOTATATE was compared head-to-head with the gold standard 18F-FDG in preclinical models of atherosclerosis and myocardial infarction. The performance of both tracers was scrutinized using in vivo SUV measurements, ex vivo gamma counting, flow cytometric analyses, and near-infrared imaging of macrophage burden. The potential for DOTATATE to replace or complement 18F-FDG was discussed. In Chapter III, we further explored the use of immune-based tracers in the context of cardiovascular disease imaging. We utilized a diverse range of tracers to thoroughly map myocardial infarction inflammation non-invasively. Preclinical animal models of temporary and permanent occlusion were deployed head-to-head and evaluated for cardiac function (MRI) and tissue damage (FDG PET), bone marrow cell division (FLT PET), hematopoietic organ metabolic activity (FDG PET), immune cell influx and egression (CD11b nanobody PET, CCR2 PET, and 18F-MRI), atherogenic plaque burden, and inflammation (histology and flow cytometry). In Chapter IV, we characterized a cell-specific nanoparticle-based tracer to track macrophage dynamics and validated it across large and small animal models of inflammation, including myocardial infarction, atherosclerosis, sepsis, and heart and lung inflammation. These data were validated using flow cytometry and histological analysis. Leveraging the macrophage affinity of HDL, in Chapter V, we labeled an ApoA-I mimetic with 89Zr, developing a tracer for inflammation imaging in mouse models of myocardial infarction and cancer. The 89Zr-ApoA-I mimetic's affinity for lipoproteins and in vivo behavior were validated in vitro and in vivo. The tracer's biodistribution mirrored that of ApoA1 and HDL, showing uptake in tumors of melanoma-bearing mice as well as in ischemic myocardium of infarcted animals. Macrophage-specific uptake was conclusively confirmed by CyTOF analyses. Building upon these findings, we deployed 19F-HDL and 89Zr-19F-HDL to comprehensively dissect systemic myeloid cell dynamics following a myocardial infarction. These data are discussed in Chapter VI, where multimodal approaches were harnessed to image myeloid cells in atherosclerotic and infarcted animals. We observed the timed egression of cells from the spleen and bone marrow to the damaged tissues. Ex vivo assays confirmed myeloid cell accumulation in atherosclerotic plaques and infarcted myocardium following the ischemic event, with imaging readouts strongly supported by flow cytometry and autoradiography. Chapter VII explores the potential of a nanobiologic mTOR-inhibitor to tame dysregulated inflammation. First, sc-RNA sequencing analysis of a COVID-19 patient database underscored the critical role of mTOR in inflammatory pathways. Subsequently, myeloid cell-specific mTORi nanobiologics were evaluated in in vitro and in vivo models of inflammation. The mTORi nanobiologics efficiently reduced inflammatory cytokine production and dampened hematopoietic cell metabolism, demonstrating significant potential as a therapeutic strategy for innate immune cell hyperinflammation. Finally, we present our efforts to overcome the clinical translation barriers associated with nanobiologics. In Chapter VIII, we scaled up the production of a nanoimmunotherapeutic drug for the treatment of atherosclerosis (S-HDL) and leveraged a comprehensive array of clinical imaging modalities to assess its in vivo behavior and therapeutic efficacy in large animals. We observed a marked reduction in systemic inflammation and the halting of atherosclerotic plaque progression in these cohorts, successfully establishing a proof-of-concept for clinical advancement of this targeted nanotherapy.