Hyperlipidemia Promotes Thrombosis After Injury to Atherosclerotic Vessels in Apolipoprotein E–Deficient Mice

Abstract

Abstract-The increased risk of hyperlipidemia on the development of complications of atherosclerosis is well established.Cholesterol-lowering therapies lead to a decrease in the incidence of vascular thrombotic events that is out of proportion to the reduction in plaque size. This suggests that the occurrence of acute thrombosis overlying a disrupted plaque is influenced by changes in lipid levels. The influence of acute hyperlipidemia on the development of thrombosis overlying an atherosclerotic plaque in vivo has not been extensively studied. We used a murine model of vascular injury induced by a photochemical reaction to elicit thrombus formation overlying an atherosclerotic plaque. Fifteen apolipoprotein E-deficient mice were maintained on normal chow until the age of 30 weeks. Five days before the induction of thrombosis, 6 mice were started on a high fat diet, and 9 mice were continued on normal chow. Mice then underwent photochemical injury to the common carotid artery immediately proximal to the carotid bifurcation, where an atherosclerotic plaque is consistently present. Mice maintained on normal chow developed occlusive thrombi, determined by cessation of blood flow, 44Ϯ5 minutes (meanϮSEM) after photochemical injury, whereas mice fed a high fat chow developed occlusive thrombosis at 27Ϯ3 minutes (PϽ0.02). Histological analysis confirmed the presence of acute thrombus formation overlying an atherosclerotic plaque. These studies demonstrate a useful model for assessing the determinants of thrombosis in the setting of atherosclerosis and show that acute elevations in plasma cholesterol facilitate thrombus formation at sites of atherosclerosis after vascular injury. Key Words: carotid artery Ⅲ transgenic mice Ⅲ cholesterol Ⅲ plaque Ⅲ rose bengal A rterial thrombosis after plaque disruption is the critical event leading to acute vascular syndromes, including myocardial infarction, unstable angina pectoris, and stroke. 1 Elevated cholesterol levels increase the risk of arterial thrombotic events in patients with atherosclerosis, and cholesterollowering therapy reduces the risk of myocardial infarction and stroke to an extent that is out of proportion to the reduction in plaque size. 2 Alterations in lipid levels have been proposed to influence thrombosis by modifying the activity of coagulation proteins, 3,4 platelets, 5 and fibrinolytic factors. 6,7 However, the effect of acute high fat feeding-induced hypercholesterolemia on the development of occlusive thrombosis after injury to an atherosclerotic artery has not been extensively analyzed.We have developed a model of atherosclerotic plaque disruption with the use of atherosclerosis-prone mice that leads to occlusive arterial thrombosis. This model was used to analyze the effect of high fat feeding on the time to occlusive thrombosis. Methods MiceApoE-deficient (apoE Ϫ/Ϫ ) mice were purchased from Jackson Labs, Bar Harbor, Me. These mice were backcrossed to C57BL/6J mice for at least 10 generations. All mice were maintained on normal chow (PicoLab Rodent C...

Carbon Monoxide-Induced Early Thrombolysis Contributes to Heme Oxygenase-1-Mediated Inhibition of Neointimal Growth after Vascular Injury in Hypercholesterolemic Mice

“…Hypercholesterolemia has been shown to influence the arterial thrombotic response after injury [12].…”

“…It is a complex process influenced by coagulation and fibrinolytic pathways [9,10], inflammation [11], and hypercholesterolemic state [12]. The first line of evidence supporting the anti-thrombotic effect of HO-1 in vivo is the observation that CO suppressed vascular thrombosis occurring during the cardiac graft rejection likely through inhibiting platelet aggregation [13].…”

Conservation of Critical Functional Domains in Murine Plasminogen Activator Inhibitor-1

“…One possibility for this refractiveness in the absence of challenge is a possible redundancy of PAI-1 single functions with other proteins. On the other hand, a number of studies have indicated that a deficiency of PAI-1 in mice is manifested by altered responses to vascular and dermal injury (31)(32)(33)(34), tumor growth and angiogenesis (19,(35)(36)(37), and clot lysis (30). As a result, under these challenge conditions, a functional redundancy may be overwhelmed, and the multiplicity of functions in a single protein may offer the most broad and economical response.…”

Monocyte tissue factor–dependent activation of coagulation in hypercholesterolemic mice and monkeys is inhibited by simvastatin

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