A complex plasma plant sterol locus on mouse chromosome 14 has at least two genes regulating intestinal sterol absorption

The effectiveness and cost-effectiveness of plant sterol or stanol-enriched functional foods as a primary prevention strategy for people with cardiovascular disease risk in England: a modeling study

This study appraises the effectiveness and cost-effectiveness of consumption of plant sterol-enriched margarine-type spreads for the prevention of cardiovascular disease (CVD) in people with hypercholesterolemia in England, compared to a normal diet. A nested Markov model was employed using the perspective of the British National Health Service (NHS). Effectiveness outcomes were the 10-year CVD risk of individuals with mild (4-6 mmol/l) and high (above 6 mmol/l) cholesterol by gender and age groups (45-54, 55-64, 65-74, 75-85 years); CVD events avoided and QALY gains over 20 years. This study found that daily consumption of enriched spread reduces CVD risks more for men and older age groups. Assuming 50% compliance, 69 CVD events per 10,000 men and 40 CVD events per 10,000 women would be saved over 20 years. If the NHS pays the excess cost of enriched spreads, for the high-cholesterol group, the probability of enriched spreads being cost-effective is 100% for men aged over 64 years and women over 74, at £20,000/QALY threshold. Probabilities of cost-effectiveness are lower at younger ages, with mildly elevated cholesterol and over a 10-year time horizon. If consumers bear the full cost of enriched spreads, NHS savings arise from reduced CVD events.

Cathepsin B is a novel gender-dependent determinant of cholesterol absorption from the intestine

We used a mouse C57BL/6J×CASA/Rk intercross to map a locus on chromosome 14 that displayed a gender-dependent effect on cholesterol absorption from the intestine. Studies in congenic animals revealed a complex locus with multiple operating genetic determinants resulting in alternating gender-dependent phenotypic effects. Fine-mapping narrowed the locus to a critical 6.3 Mb interval. Female subcongenics, but not males, of the critical interval displayed a decrease of 33% in cholesterol absorption. RNA-Seq analysis of female subcongenic jejunum revealed that cysteine protease cathepsin B (Ctsb) is a candidate to explain the interval effect. Consistent with the phenotype in critical interval subcongenics, female Ctsb knockout mice, but not males, displayed a decrease of 31% in cholesterol absorption. Although studies in Ctsb knockouts revealed a gender-dependent effect on cholesterol absorption, further fine-mapping dismissed a role for Ctsb in determining the effect of the critical 6.3 Mb interval on cholesterol absorption.

Moderately decreased cholesterol absorption rates are associated with a large atheroprotective effect

OBJECTIVE

Human treatment with ezetimibe results in a moderate 50% to 54% decrease in cholesterol absorption and a 15% to 20% decrease in plasma LDL-cholesterol levels; nevertheless, the efficacy of ezetimibe therapy has been recently challenged by the ENHANCE trial. We examined the efficacy of a moderate decrease in cholesterol absorption in preventing atherosclerosis formation in the mouse.

METHODS AND RESULTS

Congenic 14DKK animals, consisting of a castaneus (CASA/Rk) chromosome 14 interval introgressed onto the C57BL/6J background, displayed a moderate decrease in cholesterol absorption rates. The effect of moderately decreased absorption on atherosclerosis formation was determined in 14DKK apolipoprotein E knockouts (14DKK-apoEKO). When compared to chow diet-fed control apoEKO mice, congenic 14DKK-apoEKO displayed a moderate 41% decrease in cholesterol absorption rates, 30% to 37% decrease in plasma cholesterol levels, and a 70% decrease in atherosclerosis formation. Studies on cholesterol efflux and reverse cholesterol transport (RCT) from 14DKK bone marrow-derived macrophages rejected a 14DKK interval-dependent atheroprotective effects that operate in macrophages. In contrast, 14DKK-apoEKO congenics were characterized by a 60% increase in RCT from peripheral tissue macrophages.

CONCLUSIONS

These studies strongly suggest that moderately decreased cholesterol absorption rates result in a large atheroprotective effect attributable to a decrease in plasma cholesterol levels and an increase in RCT from peripheral tissue macrophages.

Cholesterol absorption from the intestine is a major determinant of reverse cholesterol transport from peripheral tissue macrophages

OBJECTIVE

We examined the effect of ezetimibe, a cholesterol absorption (CA) inhibitor, and genetic determinants of CA on reverse cholesterol transport (RCT) from subcutaneously injected macrophages using a new dual isotope label technique.

METHODS AND RESULTS

Treatment of C57BL/6J mice with ezetimibe decreased dietary CA by 86% and increased RCT from peripheral tissue macrophages (PTM) by 6-fold (P<0.0001). Moreover, congenic 14DKK mice with a modest 41% decrease in dietary CA displayed a 67% increase in RCT from PTM (P<0.007).

CONCLUSIONS

These findings indicate that pharmacological and genetic modifiers of cholesterol absorption are major determinants of reverse cholesterol transport from peripheral tissue macrophages.