Basic Science Review: Statin Therapy-Part I: The Pleiotropic Effects of Statins in Cardiovascular Disease

3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA-reductase) inhibitors, otherwise known as statins, are currently the medical treatment of choice for hypercholesterolemia. Hypercholesterolemia is a known risk factor for cardiovascular disease, and statin therapy has led to a significant reduction in morbidity and mortality from adverse cardiac events, stroke, and peripheral arterial disease. In addition to achieving a therapeutic decrease in serum cholesterol levels, statin therapy appears to promote other effects that are independent of changes in serum cholesterol. These ‘‘pleiotropic’’ effects include attenuation of vascular inflammation, improved endothelial cell function, stabilization of atherosclerotic plaque, decreased vascular smooth muscle cell migration and proliferation, and inhibition of platelet aggregation. This article is part I of a 2-part review, and it focuses on the pleiotropic effects of statins at the cellular level. </jats:p

Abstract 488: Acute Fluvastatin Pleiotropy Is Mevalonate Independent

Objectives Thrombospondin 1 (TSP1) is a matricellular glycoprotein present in injured arteries, and acts as a chemoattractant for vascular smooth muscle cells (VSMC). Migration of VSMCs to an area of injury plays a role in the development of intimal hyperplasia. We have recently shown that acute treatment of VSMCs with statins leads to a decrease in TSP1-induced VSMC chemotaxis. The purpose of this study was to determine whether the acute statin effect is dependent on the mevalonate pathway or is a pleiotropic effect. Methods Quiescent VSMCs were treated for 20 hours (standard time) or 20 minutes (acute treatment) with 100μM mevalonolactone, 0.5 μM fluvastatin, or mevalonolactone and fluvastatin combined. Migration of VSMCs towards 20 μg/ml TSP1 was assessed using a modified Boyden microchemotaxis chamber. Data was recorded as cells migrated per 5 high power fields and converted to percent positive control. Extracellular signal-regulated kinase 1/2 (ERK 1/2) activation was determined by Western blot. Densitometry is presented as percent positive control. Results TSP1 induced VSMC migration compared to SFM, 100% + 7.6 vs. 35.3% + 4.5. Treatment with fluvastatin for 20 hours (34.3% + 6.9) or 20 minutes (38.4% + 9) inhibited TSP1-induced VSMC migration. 20 hour mevalonate treatment together with fluvastatin restored the migratory effect of TSP1, 81% +9.9, p=0.11. Addition of mevalonate to acute fluvastatin treatment, did not reverse the anti-migratory effect of fluvastatin compared to TSP1 alone, 35.6% + 9.9, p&lt;0.0001. TSP1 significantly activated ERK 1/2 compared to basal medium, p42: 100% + 0 vs. 62.3% + 12.6; p44: 100% + 0 vs. 56.9% + 8.7. Acute fluvastatin did not inhibit ERK1/2 activation compared to TSP1, p42: 86.7% + 12.7; p44: 81.7% + 9.9. Conclusion These data indicate long-term fluvastatin inhibition of TSP1 stimulated migration is at least partially dependent on the mevalonate pathway. In contrast, acute fluvastatin inhibition of TSP1-induced chemotaxis involves an alternate pathway resulting in pleiotropic statin effects. Previous studies found that standard treatment time with statins inhibited ERK 1/2 activation. Our current study found that acute fluvastatin inhibition of TSP1-induced chemotaxis does not appear to be ERK1/2 dependent. </jats:p

Abstract 282: Differential Effects of Thrombospondins on Angiogenesis Gene Expression: Contribution of Statins

Objectives: Angiogenesis is important for vascular repair and of interest for treating peripheral arterial disease (PAD). Thrombospondins (TSP) are matricellular proteins involved in PAD. TSP-1 is the first endogenous angiogenesis inhibitor found. TSP-2, which is structurally similar, is also anti-angiogenic. TSP-5 (Cartilage Oligomeric Matrix Protein) differs structurally and may not be anti-angiogenic. Statins have pleiotropic vascular effects that impact TSPs. We studied the effects of TSPs and statin on endothelial cells (ECs). Hypothesis: TSP-1 and -2 induce anti-angiogenic genes, and inhibit EC tube formation while TSP-5 or statin induce pro-angiogenic genes and stimulate EC tube formation. Methods: ECs were exposed to serum free medium (SFM), TSP-1, -2, or -5 (20μg/mL) for 6 hours with or without 24 hour statin (0.5μM) pre-treatment. qrtPCR was done on 94 angiogenesis related genes. Analysis was by t-test and ANOVA, p &lt; 0.05 was significant. Canonical pathways were examined with IPA software. EC tube formation and disruption were assessed with Matrigel and SFM, TSP-1, -2, or -5 (20μg/mL) treatment with or without statin. Results: TSP-1 and -2 downregulated pro-angiogenic genes while TSP-5 both up-regulated and downregulated pro-angiogenic genes (Fig. 1). All TSPs were affected by statin. TSP-1, and -2 decreased EC tube formation (47% and 28% respectively, p&lt;0.05) and disrupted EC tubes (36% and 26% respectively, p&lt;0.05). Addition of statin trends towards attentuation of TSP tube disruption. TSP-5 had no effect on EC tubes formation. Conclusions: TSP-1, -2, and -5 impact EC angiogenesis pathways. TSP-1 and -2 downregulated pro-angiogenic genes in similar pathways. TSP-5 upregulated pro-angiogenic genes, and statin augmented this effect. TSP-1 and -2 are anti-angiogenic while TSP-5 is not in vitro . The role of statin in EC tube formation is unclear but statin does impact TSP regulation of angiogenesis gene expression and thus further studies are needed. </jats:p