动脉粥样硬化 z-bio 2021-04-12 260

　　Dyslipidemia is the driving factor of atherosclerosis and can also accelerate the occurrence of atherosclerosis. The construction of animal models of atherosclerosis began when Nikolai Anitschkov and others first fed rabbits with cholesterol in the nineteenth century. Since then, many species including non-human primates, rabbits, dogs, pigs, large/mouse have been used to construct such models, but mice are the most commonly used. The main reasons include:

　　(1) Genetic engineering is less difficult;

　　(2) Short pregnancy period and high cost performance;

　　(3) Small size, easy to raise;

　　(4) The progression of atherosclerotic lesions is relatively rapid.

　　But mice and humans also have some significant differences in physiological indicators in the process of atherosclerosis. For example, the heart rate of mice is much higher than that of humans (550-700bpm for mice and 60-100bpm for humans); the main lipoprotein of mice is high-density lipoprotein (HDL), while the main lipoprotein of humans is low-density lipoprotein Protein (LDL), which may be related to the lack of cholesteryl ester transfer protein (CETP) in mice.

　　Some scholars have compared the occurrence and development of atherosclerosis in three wild-type mouse strains C57BL/6J, BALB/c and C3H. These wild-type mouse strains are fed with a high-fat diet that causes atherosclerosis. The results showed that C57BL/6J is most prone to atherosclerosis. In addition, changing lipid distribution through the manipulation of certain lipid metabolism-related genes can also accelerate the development of atherosclerotic lesions.

　　ApoE knockout mice

　　ApoE -/- mice are currently the most commonly used genetically modified mouse strains. As a spontaneous atherosclerosis model, it is most similar to the human atherosclerosis process. ApoE is a component of very low-density lipoprotein (VLDL) and high-density lipoprotein (HDL), and is involved in the transport of cholesterol. Contrary to the human lipoprotein profile, mice have higher HDL, while low-density lipoprotein (LDL) content is lower, and their cholesterol is mainly found in HDL. After knocking out the ApoE gene, cholesterol is mainly distributed in VLDL, and the large amount of cholesterol it carries cannot be bound by lipoprotein receptors on the cell surface and then degraded, accumulating and leading to atherosclerosis. Studies have shown that ApoE -/- mice can spontaneously develop hypercholesterolemia (300-500 mg/dL) and develop significant atherosclerotic lesions under normal diet conditions. The high-fat/high-cholesterol atherogenic diet will increase the plasma cholesterol level by more than 1000 mg/dL and accelerate the atherosclerosis process. The level of triacylglycerol in the plasma of ApoE -/- mice is 68% higher than that of normal mice, regardless of age and gender. Its high-density lipoprotein is only 45% of normal mice. The lesions of these mice mainly occur in the aortic root, aortic arch, innominate artery, aortic branch and renal artery bifurcation. Under normal diet conditions, early foam cell lesions can occur within 10 weeks. After 15 weeks, it developed into atherosclerotic lesions. After 20 weeks, it developed into advanced fibrosis. A high-fat/high-cholesterol diet can accelerate this disease process, including promoting the formation of cholesterol crystals, necrotic cores, and calcifications.

　　Ldlr knockout mice

　　low-density lipoprotein receptor transgenic (Ldlr-/-) mice is another commonly used animal model of atherosclerosis. The advantage of this model is that knocking out the LDL receptor (LDLR) has no additional effects other than affecting the uptake and clearance of lipoproteins. The most important point is that under normal diet conditions, Ldlr-/- mice have no obvious hyperlipidemia, but only mild atherosclerotic lesions. However, after the high-fat/high-cholesterol diet was induced, the mouse showed extensive intimal thickening of the aorta after 12 weeks, and 60%-80% of the intimal surface was positive for Sudan staining; obvious appearance at 20 weeks Of hypercholesterolemia and atherosclerotic lesions. Therefore, unlike ApoE -/- mice, researchers can start a high-fat/high-cholesterol diet on Ldlr-/- mice of different months of age at any given time point to construct an atherosclerotic environmental exposure.

　　Other mouse models of atherosclerosis

　　In addition, some scholars also target two blood lipid metabolism-related genes to construct a co-knockout mouse model. For example, the offspring of Ldlr-/- mice mated with apolipoprotein B-related knockout mice showed hypercholesterolemia (300 mg/dL) and extensive atherosclerotic lesions even under normal diet conditions. ApoE*3 Leiden mice express human ApoE3 variants with low affinity for LDLR, leading to the occurrence of atherosclerotic lesions. Low-density lipoprotein receptor and apolipoprotein E double mutant mice (ApoE -/-/Ldlr-/-) showed more severe hypercholesterolemia and atherosclerotic lesions than ApoE -/- mice. Since mice do not express CETP, which reduces HDL, some scholars have used the offspring of transgenic mice expressing human CETP and Ldlr-/-, human ApoB-100] or ApoE*3 Leiden mice to construct atherosclerosis models. . The proprotein convertase subtilisin/kexin type 9 (PCSK9) increases plasma LDL cholesterol levels by degrading LDLR in the liver. Studies have shown that adeno-associated virus (AAV)-mediated overexpression of PCSK9 can induce hypercholesterolemia and atherosclerosis at a relatively early time point (12 weeks) under high-fat diet conditions without the need for genetic manipulation. High-density lipoprotein receptor SR-BI (scavenger receptor class B, type I) and ApoE gene double knock homozygous mutant mice (SR-BI KO/ApoeR61 (h/h) even under low-fat diet feeding conditions It also shows a series of pathological features shared with human coronary heart disease, such as hypercholesterolemia, myocardial infarction, cardiac insufficiency (enlarged heart, decreased left ventricular ejection fraction, abnormal electrocardiogram) and premature death (average 6 weeks of age) .