Abstract 474: Rosuvastatin Restores NO-dependent Endothelial Function by Increasing Vascular PPARg and SOD1 Expression
Background- Statins improve atherosclerotic diseases through their cholesterol-reducing effect. In a mouse model of the metabolic syndrome (doubly deficient in leptin and LDLr genes, DKO mice), we observed that, as with diet restriction, rosuvastatin (RSV) lowered blood pressure and improved NO-dependent endothelial function, but in the absence of body weight loss or major change in plasma cholesterol. A high-density transcriptomic analysis had identified PPARs as potential target genes for the effect of diet restriction. We therefore examined whether RSV regulates PPARs expression/activity in endothelial cells as well as PPAR-responsive genes susceptible to mediating improved NO regulation.
Methods and results- We examined the effect of RSV on PPARγ expression in aortic tissue of DKO mice and cultured endothelial cells by RT-qPCR. RSV(10mg/kg i.p., 12 weeks) increased aortic PPARγ (but not-α) expression in vivo (+100%; P=0.007; n=6 mice) and in cultured BAEC (10−5 mol/L; +76%; P=0.002). RSValso increased mRNA (+38%; P=0.01) and, dose-dependently, protein (P=0.002 for linear trend) abundance of SOD1, a PPAR-responsive gene (n=6 exp). The effect was reversed upon co-incubation with mevalonate, confirming the dependence on HMG-CoA reductase inhibition. The PPARγ agonist pioglitazone similarly increased PPARγ (+73%; P=0.04) and SOD1 (+37%; P=0.01) mRNAs. Both GW9662, a PPARγ-specific antagonist, and cell transfection with two siRNAs raised against PPARγ abrogated the upregulation of SOD1 in response to RSV, confirming the causality of PPARγ activation for this effect. In trans-activation assays using co-transfection of plasmids encoding PPARγ or PPARα with a luciferase reporter construct under the control of PPAR-responsive elements, cell treatment with RSV enhanced PPARγ - (but not PPARα-) dependent luciferase activity (+100%; P=0.04), an effect, again, blocked by GW9662 (P=0.03; n=5 exp in triplicate).
Conclusion- RSV increases PPARγ expression in endothelial cells, as well as its trans-activation of downstream PPAR-responsive genes, including SOD1. The resulting increase in the anti-oxidant SOD1 protein in endothelial cells may represent a unique mechanism of vascular protection and NO-dependent BP correction by RSV treatment.