Atherosclerotic disease activity is associated with glycolytic enzyme expression across multiple cell types and is trackable by FDG-PET

Abstract

Positron emission tomography (PET) imaging with the radiolabeled glucose analog fluorodeoxyglucose (18FDG) is used to monitor atherosclerosis in clinical trials, but there is uncertainty regarding the plaque cell types that accumulate FDG and how uptake is regulated. The long-standing view that 18FDG is mainly taken up by macrophages is at odds with human and experimental data, and the impact of disease activity on 18FDG uptake has not been examined directly. To analyze the ability of 18FDG-PET to monitor disease activity, we developed a model of plaque regression in minipigs with hepatic overexpression of a gain-of-function mutant of proprotein convertase subtilisin/kexin type 9 (PCSK9). Atherosclerosis was induced through 12 months of high-fat feeding in the porcine model. Disease activity was then lowered for 3 months by reducing plasma cholesterol with a low-fat diet alone or in combination with the microsomal transfer protein (MTP) inhibitor BMS-212122. Plaque regression in advanced lesions of the abdominal aorta was evident from reduced lipid content, reduced necrotic core size, and partial resolution of plaque inflammation and was accompanied by a decline in 18FDG-PET signal. Single-cell gene expression profiling revealed that plaque regression involved substantial down-regulation of genes encoding glycolytic enzymes in smooth muscle cells (SMCs), macrophages, and lymphocytes, which was corroborated by analysis of the plaque cellular proteome. These findings in a large-animal model suggest that 18FDG-PET can monitor atherosclerosis because of a close association between disease activity and glycolytic enzyme expression in all of the major plaque cell types.