Targeting glycolysis in endothelial cells to prevent intraplaque neovascularization and atherogenesis in mice

Abstract

In recent years, the study of endothelial cell (EC) metabolism has led to the discovery of novel regulatory mechanisms and potential new targets for vascular-related diseases. Despite the fact that ECs have readily available oxygen in the blood, they mainly generate ATP via anaerobic glycolysis rather than Krebs cycle. In the context of atherosclerosis, there has been growing interest in understanding how EC metabolism affects plaque formation and intraplaque (IP) angiogenesis, which has been identified as a contributing factor for plaque vulnerability in human atherosclerosis.

Among the enzymes involved in glycolytic flux modulation, PFKFB3 plays a critical role for the proliferation and migration of ECs. PFKFB3 is upregulated in atheroprone regions of arterial vessels and in carotid plaques of patients with elevated levels of lipoprotein(a). The experimental work of this thesis focuses on PFKFB3 as a modulator of EC glycolysis and its effects on atherosclerosis progression and IP angiogenesis.

In the first part of this thesis, a pharmacological study with partial glycolysis inhibitor 3PO in the context of advanced atherosclerotic plaques is described. 3PO treatment restrains IP angiogenesis and plaque frequency but it does not affect plaque size and composition in ApoE-/-Fbn1C1039G+/- mice. In addition, a 3PO-mediated reduction in plaque formation is also observed in ApoE-/- mice that develop plaques without IP neovascularization.

Furthermore, EC-specific PFKFB3 deletion leads to a significant reduction in plaque size, IP angiogenesis and hemorrhagic complications in a vein graft model. These findings suggest that endothelial glycolysis inhibition may represent a new therapeutic strategy to slow down plaque progression in vein grafts. A study performed in collaboration with the University of Aberdeen is also presented in this thesis. Here the development of a new PFKFB3-targeted PET radiotracer, [18F]ZCDD083, for in vivo plaque imaging is described. The specificity of the tracer for atherosclerotic plaques is demonstrated by a combination of ex vivo autoradiography and en face Oil Red O staining. This tracer is a promising non-invasive diagnostic tool to detect rupture-prone atherosclerotic plaques, Finally, a novel imaging method for a three-dimensional reconstruction of the IP vessel network is presented. This method is based on iDISCO immunolabeling and confocal microscopy. It may represent a novel tool to investigate the causal relationship between IP angiogenesis and atherogenesis. Overall, the experimental data generated in this thesis strongly argue for a critical role of EC metabolism in the formation and progression of atherosclerosis in addition to IP angiogenesis.