18F]fluorodeoxyglucose uptake in atherosclerotic plaques is associated with reduced coronary flow reserve in mice.

Abstract

Coronary microvascular dysfunction, observed as impaired coronary vasodilator capacity, is an early manifestation of coronary artery disease. Inflammation plays an important role in different stages of atherogenesis. To study the role of vessel wall inflammation in the development of coronary dysfunction, we compared [(18)F]fluorodeoxyglucose (FDG) uptake in the aorta and coronary flow reserve (CFR) in atherosclerotic mice. We studied healthy young C57BL/6 mice fed a normal diet (n = 7) as well as hypercholesterolemic low-density lipoprotein receptor-disrupted/apolipoprotein B100-expressing (LDLR(-/-)ApoB(100/100)) mice (n = 15) and hypercholesterolemic and diabetic LDLR(-/-)ApoB(100/100)insulinlike growth factor II-overexpressing mice (n = 14) fed a western-type diet, aged 4 to 6 months. Doppler sonography was used to measure CFR as the ratio of coronary flow velocity during isoflurane-induced hyperemia and at rest. Uptake of [(18)F]FDG into the aorta was measured by autoradiography of tissue sections. Histologic sections showed extensive atherosclerosis in the aorta, but coronary arteries were not obstructed. Both hyperemic coronary flow velocity and CFR were reduced (P < .05) in hypercholesterolemic mice with and without diabetes in comparison to healthy young C57BL/6 controls. Among hypercholesterolemic mice, both hyperemic flow velocity and CFR inversely correlated with atherosclerotic plaque [(18)F]FDG uptake in the aorta (r = -0.73; P < .001; r = -0.63; P = .001, respectively). In a multivariate analysis, including animal weight, aortic plaque burden, plasma glucose, plasma cholesterol, and [(18)F]FDG uptake in atherosclerotic plaques, only [(18)F]FDG uptake remained an independent predictor of reduced CFR (β = 0.736; P = .001). The inflammatory activity in atherosclerotic plaques of the aorta independently predicts reduced CFR in atherosclerotic mice without obstructive coronary artery disease. This finding suggests that atherosclerotic inflammation contributes to coronary dysfunction.