Evidence for statin pleiotropy in humans: differential effects of statins and ezetimibe on rho-associated coiled-coil containing protein kinase activity, endothelial function, and inflammation

Abstract

Background: By inhibiting 3-hydroxy-3-methylglutaryl coenzyme A reductase, statins not only reduce cholesterol biosynthesis but also decrease the formation of isoprenoids, which are important for mediating signaling through the Rho-associated coiled-coil containing protein kinase (ROCK) pathway. Increased ROCK activity has been implicated in endothelial dysfunction and vascular inflammation. We hypothesize that ezetimibe, which inhibits intestinal cholesterol absorption, may not exert similar cholesterol-independent or pleiotropic effects of statins and, when used with a lower dose of statin, have less effect on ROCK activity than a higher dose of statin.

Methods and results: In a prospective, randomized, observer-blinded study, we treated 60 dyslipidemic subjects without cardiovascular disease with simvastatin 40 mg/d, simvastatin/ezetimibe 10/10 mg/d, or placebo tablets for 28 days (n=20 in each arm). We evaluated baseline demographics and lipid levels, ROCK activity, C-reactive protein, and flow-mediated dilation before and after treatment. Compared with the placebo group, both treatment regimens decreased low-density lipoprotein cholesterol by 38% and C-reactive protein by 38% to 40% after 28 days (P<0.01 for both compared with placebo). Although the low-density lipoprotein cholesterol and C-reactive protein reductions were comparable with either lipid-lowering regimen, only simvastatin 40 mg reduced ROCK activity and improved flow-mediated dilation (P<0.01 for both compared with baseline). Reduction in ROCK activity with simvastatin 40 mg remained significant even after controlling for changes in low-density lipoprotein cholesterol (P=0.01) and correlated with improvement in flow-mediated dilation (R(2)=-0.78, P<0.01). No correlation was found between changes in flow-mediated dilation and changes in low-density lipoprotein cholesterol or C-reactive protein.

Conclusions: These results indicate that high-dose statin monotherapy exerts greater effects on ROCK activity and endothelial function, but not on C-reactive protein, than low-dose statin plus ezetimibe. These findings provide additional evidence of statin benefits beyond cholesterol lowering.

Trial registration: ClinicalTrials.gov NCT00560170.

Figure 1

Effects of simvastatin (40 mg/d) and simvastatin/ezetimibe (10/10 mg/d) on leukocyte ROCK activity. Leukocyte ROCK activity was measured as percent staining of phosphorylated (p- and phospho-) MBS of myosin light-chain phosphatase (pThr⁸⁵³-MBS) relative to the staining of total (t) MBS.

Figure 2

Correlation between changes in ROCK activity and changes in LDL-C (A) , FMD (B), and hsCRP (C). Scatterplots depict the correlation in the change from day 28 to baseline for both parameters.