Predilection of Low Protein C-induced Spontaneous Atherothrombosis for the Right Coronary Sinus in Apolipoprotein E deficient mice

Atherothrombosis model by silencing of protein C in APOE*3-Leiden.CETP transgenic mice

Murine atherosclerosis models are key for investigation of atherosclerosis pathophysiology and drug development. However, they do not feature spontaneous atherothrombosis as a final stage of atherosclerosis. Transgenic mice expressing both the human mutant apolipoprotein E form APOE*3-Leiden and human cholesteryl ester transfer protein (CETP), i.e. APOE*3-Leiden.CETP mice, feature a moderate hyperlipoproteinemia and atherosclerosis phenotype. In contrast to apolipoprotein E deficient (Apoeˉ^/ˉ) mice, APOE*3-Leiden.CETP mice respond well to lipid-lowering and anti-atherosclerotic drugs. The aim of the study was to investigate whether silencing of anticoagulant Protein C (Proc) allows APOE*3-Leiden.CETP mice to feature thrombosis as a final stage of atherosclerosis. Female APOE*3-Leiden.CETP mice were fed a Western-type diet to induce advanced atherosclerosis, followed by an injection with a small interfering RNA targeting Proc (siProc). Presence of atherosclerosis and atherothrombosis was determined by histologic analysis of the aortic root. Atherosclerosis severity in the aortic root area of APOE*3-Leiden.CETP mice varied from type “0” (no lesions) to type “V” lesions (advanced and complex lesions). Atherothrombosis following siProc injection was observed for 4 out of 21 APOE*3-Leiden.CETP mice (19% incidence). The atherothrombosis presented as large, organized, fibrin- and leukocyte-rich thrombi on top of advanced (type “V”) atherosclerotic plaques in the aortic root. This atherothrombosis was comparable in appearance and incidence as previously reported for Apoeˉ^/ˉ mice with a more severe atherosclerosis (19% incidence). APOE*3-Leiden.CETP mice with modest hyperlipidemia and atherosclerosis can develop atherothrombosis upon transient Proc-silencing. This further extends the use of these mice as a test model for lipid-lowering and anti-atherosclerotic drugs.

Vulnerable plaque and vulnerable blood: Two critical factors for spontaneous atherothrombosis in mouse models

Atherothrombotic events such as myocardial infarction and ischemic stroke are a major cause of morbidity and mortality worldwide. Understanding the molecular and cellular mechanisms of atherosclerotic plaque destabilization or erosion, and developing new therapeutics to prevent acute cardiovascular events is important for vascular biology research and clinical cardiovascular medicine. However, basic research on plaque destabilization, rupture and erosion is hampered by the lack of appropriate animal models of atherothrombosis. Unprovoked atherothrombosis is very scarce in commonly used mouse models for atherosclerosis, the low-density lipoprotein receptor knockout and apolipoprotein E knockout mice. Therefore, specific interventions are required to induce atherothrombosis in these models. Two strategies can be employed to induce atherothrombosis: 1) plaque destabilization and 2) induction of blood hypercoagulability. Although the individual strategies yield atherothrombosis at low incidence, it appears that the combination of both plaque destabilization and an increase in blood coagulability is the most promising strategy to induce atherothrombosis on a larger scale. In this review, we summarize the recent developments on mouse models for the investigation of atherothrombosis.