Cafestol Increases Serum Cholesterol Levels in Apolipoprotein E*3-Leiden Transgenic Mice by Suppression of Bile Acid Synthesis

Abstract

Abstract-Cafestol, a diterpene present in unfiltered coffee, potently increases serum cholesterol levels in humans. So far, no suitable animal model has been found to study the biochemical background of this effect. We determined the effect of cafestol on serum cholesterol and triglycerides in different mouse strains and subsequently studied its mechanism of action in apolipoprotein (apo) E*3-Leiden transgenic mice. ApoE*3-Leiden, heterozygous low density lipoproteinreceptor (LDLRϩ/Ϫ) knockout, or wild-type (WT) C57BL/6 mice were fed a high-(0.05% wt/wt) or a low-(0.01% wt/wt) cafestol diet or a placebo diet for 8 weeks. Standardized to energy intake, these amounts are equal to 40, 8, or 0 cups of unfiltered coffee per 10 MJ per day in humans. In apoE*3-Leiden mice, serum cholesterol was statistically significantly increased by 33% on the low-and by 61% on the high-cafestol diet. In LDLRϩ/Ϫ and WT mice, the increases were 20% and 24%, respectively, on the low-cafestol diet and 55% and 46%, respectively, on the high-cafestol diet. These increases were mainly due to a rise in very low density lipoprotein (VLDL) and intermediate density lipoprotein cholesterol in all 3 mouse strains. To investigate the mechanism of this effect, apoE*3-Leiden mice were fed a high-cafestol or a placebo diet for 3 weeks. Cafestol suppressed enzyme activity and mRNA levels of cholesterol 7␣-hydroxylase by 57% and 58%, respectively. mRNA levels of enzymes involved in the alternate pathway of bile acid synthesis, ie, sterol 27-hydroxylase and oxysterol 7␣-hydroxylase, were reduced by 32% and 48%, respectively. The total fecal bile acid output was decreased by 41%. Cafestol did not affect hepatic free and esterified cholesterol, but it decreased LDLR mRNA levels by 37%. The VLDL apoB and triglyceride production rates, as measured after Triton injection, were 2-fold decreased by cafestol, indicating that the number of particles secreted had declined and that there was no change in the amount of triglycerides present in the VLDL particle during cafestol treatment. However, the VLDL particles contained a 4-times higher amount of cholesteryl esters, resulting in a net 2-fold increased secretion of cholesteryl esters. The decrease in triglyceride production was the result of a reduction in hepatic triglyceride content by 52%. In conclusion, cafestol increases serum cholesterol levels in apoE*3-Leiden mice by suppression of the major regulatory enzymes in the bile acid synthesis pathways, leading to decreased LDLR mRNA levels and increased secretion of hepatic cholesterol esters. We suggest that suppression of bile acid synthesis may provide an explanation for the cholesterol-raising effect of cafestol in humans. Key Words: bile acid synthesis Ⅲ cholesterol 7␣-hydroxylase Ⅲ sterol 27-hydroxylase Ⅲ apolipoprotein E*3-Leiden mice Ⅲ cafestol U nfiltered coffee markedly increases serum cholesterol levels in humans. The compounds responsible for this effect are cafestol and kahweol, 2 diterpenes that are present in coffee beans. 1 From our experimen...

Anti-Obesity and Hypotriglyceridemic Properties of Coffee Bean Extract in SD Rats

“…Raw green coffee bean contains cafestol, which is a diterpene, and potently increases serum cholesterol level in humans and experimental animals (Urgert and Katan, 1997;Post et al, 2000). CBE prepared from raw green coffee beans contains cafestol.…”

Fibrates Suppress Bile Acid Synthesis via Peroxisome Proliferator–Activated Receptor-α–Mediated Downregulation of Cholesterol 7α-Hydroxylase and Sterol 27-Hydroxylase Expression

“…Materials used for the isolation and culturing of rat hepatocytes and for assaying cholesterol 7␣-hydroxylase and sterol 27-hydroxylase were obtained from sources described previously. 24,25 Male Wistar rats weighing 250 to 350 g were used throughout and were maintained on standard chow and water ad libitum. In vitro experiments were as follows: Two days before the hepatocyte isolation, the rats were fed a diet supplemented with 2% (wt/wt) cholestyramine (Questran, Bristol Myers B.V.) to obtain a sufficient level of expression of cholesterol 7␣-hydroxylase.…”

“…Enzyme activities of cholesterol 7␣-hydroxylase and sterol 27-hydroxylase in cell homogenates and isolated liver microsomes and mitochondria were determined as described previously, 25 measuring the mass conversion of cholesterol into 7␣-and 27-hydroxycholesterol.…”

“…Aliquots of lyophilized feces were used for determination of neutral and acidic sterol content by gas-liquid chromatographic procedures. 25 …”

Absorption, Distribution, and Biliary Excretion of Cafestol, a Potent Cholesterol-Elevating Compound in Unfiltered Coffees, in Mice

“…The selection of the mouse as a model was based on previous studies showing that among various animal models, the ApoE*3-Leiden transgenic mouse is the only model that responds to cafestol as humans do (Post et al, 2000).…”