High soluble endoglin levels regulate cholesterol homeostasis and bile acids turnover in the liver of transgenic mice

Aims: Increased plasma soluble endoglin concentrations (sEng) are frequently detected in metabolic disorders accompanied with hypercholesterolemia in serum, but effect of sEng on the Cholesterol biochemistry is unknown. Cholesterol and bile acids (BA) are important products of liver metabolism with numerous functions within the organism. Turnover of these substances requires precise regulation due to potential toxicities during their cumulation. In this study, we hypothesized that high sEng levels affect Cholesterol homeostasis and BA turnover in mice liver.

Main methods: Nine-month-old transgenic male mice overexpressing human sEng and wild-type mice underwent plasma, bile, stool, and organ samples analysis by analytical, qRT-PCT and Western blot methods.

Key findings: sEng mice demonstrated decreased plasma total and LDL Cholesterol concentrations due to upregulation of hepatic Sr-b1 and LDLR receptors, increased liver Cholesterol content, and increased Abcg8-mediated Cholesterol efflux into bile. sEng also increased conversion of Cholesterol into bile acids (BA) via upregulation of Cyp7a1 and increased Mdr1 expression. Plasma concentrations of BA were increased in sEng mice due to their enhanced reabsorption via ileum. Increased hepatic disposition of BA led to their increased biliary excretion coupled with choleretic activity.

Significance: For the first time, we have shown that high sEng plasma levels affect Cholesterol and BA homeostasis on the basis of complex liver and intestinal effects. The significance of these findings for pathophysiology of diseases associated with increased sEng concentrations remains to be elucidated in prospective studies.