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Cholesteryl ester transfer protein (CETP) activity results in a proatherogenic lipoprotein profile. In cholestatic conditions, farnesoid X receptor (FXR) signaling by bile acids (BA) is activated and plasma HDL cholesterol (HDL-C) levels are low. This study tested the hypothesis that FXR-mediated induction of CETP contributes to this phenotype. Patients with cholestasis and high plasma BA had lower HDL-C levels and higher plasma CETP activity and mass compared with matched controls with low plasma BA (each P < 0.01). BA feeding in APOE3*Leiden transgenic mice expressing the human CETP transgene controlled by its endogenous promoter increased cholesterol within apoB-containing lipoproteins and decreased HDL-C (each P < 0.01), while hepatic CETP mRNA expression and plasma CETP activity and mass increased (each P < 0.01). In vitro studies confirmed that FXR agonists substantially augmented CETP mRNA expression in hepatocytes and macrophages dependent on functional FXR expression (each P < 0.001). These transcriptional effects are likely mediated by an ER8 FXR response element (FXRE) in the first intron. In conclusion, using a translational approach, this study identifies CETP as novel FXR target gene. By increasing CETP expression, FXR activation leads to a proatherogenic lipoprotein profile. These results have clinical relevance, especially when considering FXR agonists as emerging treatment strategy for metabolic disease and atherosclerosis.

Treatment of chronic hepatitis C with type I interferons and ribavirin can be associated with exacerbation of hepatitis and sometimes liver decompensation. We report two patients with chronic hepatitis C virus infection who experienced a severe increase of bilirubin levels of up to 17 times upper the limit of normal value in the absence of deterioration of hepatic function during therapy with pegylated-interferon and ribavirin. A genetic disposition for Gilbert’s syndrome explained the adverse events and permitted a continuation of therapy leading to a sustained clearance of chronic hepatitis C infection. Since one patient jaundiced already during a lead-in treatment period with ribavirin monotherapy we suggest that hyperbilirubinaemia during combination therapy is primarily caused by ribavirin rather than by effects of interferon alpha on UDP-glucuronosyltransferase activities. Of note, both patients recovered from their initial unconjugated hyperbilirubinemia despite continuation of ribavirin therapy, which indicates that compensatory mechanisms leading to a normalization of UGT1A1 activity are likely.