Rosuvastatin does not affect human apolipoprotein A-I expression in genetically modified mice: a clue to the disputed effect of statins on HDL

BACKGROUND AND PURPOSE Besides a significant reduction of low-density lipoprotein (LDL) cholesterol, statins moderately increase high-density lipoprotein (HDL) levels. In vitro studies have indicated that this effect may be the result of an increased expression of apolipoprotein (apo)A-I, the main protein component of HDL. The aim of the present study was to investigate in vivo the effect of rosuvastatin on apoA-I expression and secretion in a transgenic mouse model for human apoA-I. EXPERIMENTAL APPROACH Human apoA-I transgenic mice were treated for 28 days with 5, 10 or 20 mg.kg(-1).day(-1) of rosuvastatin, the most effective statin in raising HDL levels. Possible changes of apoA-I expression by treatment were investigated by quantitative real-time RT-PCR on RNA extracted from mouse livers. The human apoA-I secretion rate was determined in primary hepatocytes isolated from transgenic mice from each group after treatment. KEY RESULTS Rosuvastatin treatment with 5 and 10 mg.kg(-1).day(-1) did not affect apoA-I plasma levels, whereas a significant decrease was observed in mice treated with 20 mg.kg(-1).day(-1) of rosuvastatin (-16%, P < 0.01). Neither relative hepatic mRNA concentrations of apoA-I nor apoA-I secretion rates from primary hepatocytes were influenced by rosuvastatin treatment at each tested dose. CONCLUSIONS AND IMPLICATIONS In human apoA-I transgenic mice, rosuvastatin treatment does not increase either apoA-I transcription and hepatic secretion, or apoA-I plasma levels. These results support the hypothesis that other mechanisms may account for the observed HDL increase induced by statin therapy in humans.