Abstract 149: Manipulating Bile Acid Production Using Genome Editing To Modulate Cardio-metabolic Disease

Cardiovascular disease (CVD) remains the leading cause of death in the United States, in part due to consumption of a high cholesterol Western diet. Absorption of dietary cholesterol is facilitated by detergents, called bile acids, which are produced in the liver. Bile acids are a functionally diverse group of molecules with different capacities to affect lipid absorption. We hypothesize that specific changes in the bile acid pool will change cholesterol absorption and alter development of CVD. To alter the bile acid pool, we disrupted three enzymes ( Cyp7a1 , Cyp8b1 and Cyp2c70 ) using liver-directed AAV-CRISPR. Cyp7a1 catalyzes the rate-limiting step of bile acid synthesis, whereas both Cyp8b1 and Cyp2c70 mediates production of specific bile acids (cholic acid and muricholic acid respectively). Using UPLC-MS/MS, we show that loss of CYP7A1 in adult mice reduces the size of the bile acid pool while loss of CYP8B1 or CYP2C70 alters the composition without changing total bile acid levels. To study atherosclerosis, we co-disrupted Cyp7a1, Cyp8b1 and Cyp2c70 concurrently with Low Density Lipoprotein Receptor ( Ldlr ) to induce hypercholesterolemia on a Western diet for 20 weeks. Loss of all three bile acid enzymes resulted in different atherosclerosis outcomes. Loss of CYP7A1 resulted in modest protection from atherosclerosis. Using a novel GC-MS-based technique, we demonstrate these mice have reduced cholesterol absorption. Loss of CYP8B1 caused modest reductions in plasma cholesterol and moderate atheroprotection, but did not alter cholesterol absorption. Finally, loss of CYP2C70 led to an early onset of hypercholesterolemia, which we hypothesize is due to enhanced cholesterol absorption, resulting in accelerated development of atherosclerosis. We hypothesize that these differences in atherosclerosis observed with different bile acid profiles are due to systemic changes in cholesterol metabolism that are driven, in part, by changes in cholesterol absorption. Our studies suggest specific changes in bile acids have the potential to become a novel precision treatment for cardio-metabolic diseases.