Abstract 2004: Sex Differences In Bile Acid Metabolism Impact Cholesterol Homeostasis And Cardiovascular Disease

Abstract

Cardiovascular disease (CVD) remains the leading cause of death in the United States for both men and women, despite cholesterol-lowering drugs such as statins. Diets rich in cholesterol are well-known to contribute to disease progression. The absorption of dietary cholesterol is facilitated by liver-synthesized detergents called bile acids. We hypothesized that manipulating bile acid metabolism to reduce cholesterol absorption would result in decreased plasma cholesterol levels and protect from atherosclerosis. To alter the bile acid pool, we used liver-directed AAV-CRISPR to disrupt Cyp7a1, which catalyzes the rate-limiting step of bile acid synthesis. Consequently, we show that loss of CYP7A1 in adult male mice reduces the size of the bile acid pool. To study atherosclerosis, we co-disrupted Cyp7a1 concurrently with Low Density Lipoprotein Receptor ( Ldlr ) to induce hypercholesterolemia on a Western diet for 20 weeks. Loss of hepatic CYP7A1 in males reduced atherosclerosis and reduced cholesterol absorption. In stark contrast to what we observed in male mice, the absence of this rate limiting enzyme in female mice resulted in only a modest reduction in the bile acid pool. This blunted reduction in bile acids in female Cyp7a1 CRISPR mice was not sufficient to decrease cholesterol absorption, resulting in accumulation of cholesterol, and consequently increasing cardiovascular risk. We hypothesize that there is a female-specific mechanism to preserve bile acid production that operates in the absence of CYP7A1. We are currently in the process of testing candidate female-specific enzymes for bile acid production. These studies indicate new avenues by which female bile acid and cholesterol metabolism regulation differs from than that of males. The resulting differences in cardiovascular risk highlight the essential need for male- and female-specific personalized medicine approaches for cardiovascular disease prevention.