A New Translational Model Of Hypercholesterolemia And Atherosclerosis: Effect Of Statins On Ldlr Ko Miniature Swine

Small animal models of atherosclerosis are commonly used in drug studies; however, the results often fail to translate into the clinic. A large animal model that more accurately reflects the human disease is needed. We recently developed a transgenic Yucatan pig model in which the LDL receptor (LDLR) gene is knocked out. Five groups of Yucatan pigs (N=4 per group), either wild type (LDLR+/+) or heterozygote (LDLR+/-) were fed a normal diet or a high fat diet for a six month period. One of the heterozygote/high fat diet groups in addition received a daily dose of a statin (atorvastatin) at 3 mg/kg. Every two weeks during the study a variety of clinical chemistry parameters were measured. At study termination, select arteries were collected, stained for lipid deposits and quantitated. In addition, sections of these arteries were prepared for immunohistochemistry to detect selected markers of macrophage infiltration into the atherosclerotic plaques. As expected, pigs fed a high fat diet gained significantly more weight at six months whether they were wild type or LDLR+/-. Atorvastatin appeared to attenuate this weight gain. There were significant increases in total cholesterol, HDL and LDL in pigs fed the high fat diet compared to their corresponding control group. The group receiving the atorvastatin had reduced values of these parameters compared to controls showing that a statin had a beneficial effect on lipid levels even in a high fat diet scenario. VLDL levels were not affected but there were triglyceride changes across the groups. Liver function was unchanged based on total bilirubin and AST while ALT measurements were altered in some of the groups. Immunohistochemistry and histomorphometry was performed on some arteries. Atorvastatin-induced amelioration of hypercholesterolemia in this model underscores its translational utility.