Abstract 17113: Dietary Supplementation of Hyodeoxycholic Acid and D-Limonene Decreased Atherosclerotic Lesion Formation in LDLR Knockout Mouse

In this study, we examined the effects of dietary supplementation of two natural emulsifiers, hyodeoxycholic acid (HDCA) and D-limonene (D-Lim), on atherosclerotic lesion formation in LDLRKO mouse. Female LDLRKO mice were maintained on a western diet for 8 weeks, then divided into 3 groups that received the following diets for 15 weeks before euthanization, chow diet, chow diet + 1.25% HDCA, or chow diet + 5% D-Lim. We found that 1.25% HDCA was able to significantly suppress the development of plaque area throughout the aorta (beyond the root of the aorta) by 47% (p<0.01) over 15 weeks of treatment. 5% D-lim treated mice showed a 25% (p<0.05) reduction in plaque formation. Atherosclerotic lesion size at the innominate artery was decreased by 94% (p<0.0001) and 53% (p<0.05) in the HDCA and D-Lim groups, respectively, as compared to the chow diet group. Plasma VLDL/IDL/LDL cholesterol levels were significantly decreased by 61% (p<0.0001) and 23% (p=0.01) in the HDCA and D-Lim groups, respectively, as compared to the chow diet group. We found that HDCA supplementation decreased cholesterol absorption from gut by 76% (p<0.0001), whereas D-Lim had no effect on cholesterol absorption. Interestingly, hepatic mRNA level of Cyp7a1, a key enzyme in bile acid synthesis, was significantly increased by more than 100% (p<0.05) in D-Lim group, suggesting D-Lim may act as a bile sequestrant in the gut. In addition, HDL isolated from the HDCA and D-Lim groups exhibited significantly increased ability (49% and 45% increase, respectively) to mediate cholesterol efflux from cholesterol loaded RAW 264.7 cells as compared to those of the chow diet group. In summary, our data demonstrated that HDCA supplementation decreased plasma VLDL/IDL/LDL cholesterol levels mainly through its ability to block intestinal cholesterol absorption. D-Lim decreased plasma VLDL/IDL/LDL cholesterol levels probably through decreased bile acid re-absorption in the intestine and increased conversion of cholesterol into bile acid in the liver. HDCA and D-Lim improve the cholesterol efflux ability of HDL as well. These anti-atherogenic effects resulted in significantly decreased atherosclerosis in LDLRKO mice receiving HDCA or D-Lim. HDCA and D-Lim may be new candidates for anti-atherosclerotic drugs.