Effect of Atorvastatin (Lipitor) on Gene Expression in People With Vascular Disease

Background: Atherosclerosis and its consequences - coronary heart disease and stroke - are principal causes of mortality in developed countries. Being able to accurately predict an individual's risk of vascular disease is needed for preventive strategies and measuring the effectiveness thereof. Current risk assessment tools are imperfect at best. It is possible that information from gene expression profiling of peripheral white blood cells may add predictive information about vascular risk. We previously identified a panel of 78 genes in the peripheral blood that correlated with an individual's future risk of stroke. We hypothesize that gene expression in white blood cells will be modified by an intervention that has been shown to reduce vascular risk via anti-inflammatory mechanisms: the 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase inhibitor class of lipid lowering drugs, known as "statins". The vascular protective effects of statins appear to be due in part to immune modulation and to be dose-dependent. Statin administration has been shown to modulate gene expression in peripheral blood mononuclear cells in vitro.

Objectives: Overall: To determine if atorvastatin modulates gene expression in peripheral blood mononuclear cells in a dose dependent manner in a cohort of subjects at risk of vascular disease. Specific: To determine if: (1) Inflammatory genes are specifically and temporarily modified by atrovastatin in a dose dependent manner; (2) A previously defined panel of 78 genes is included among the genes modified by atorvastatin; and (3) Gene expression changes correlate the degree of gene expression modulation by atorvastatin with the degree of lipid lowering and other inflammatory parameters such as high sensitivity C-reactive protein.

Study Design: Dose-response randomized, blinded study of atorvastatin treatment of 120 volunteer subjects with at least two conventional vascular risk factors who are not currently taking a statin. In the first and primary phase of the study, subjects will be administered atorvastatin in a blinded fashion in one of four doses (0mg, 10mg, 20mg or 40mg) for a period of three months. Block randomization will stratify on age and risk factor status. In the second and validation phase of the study, the subjects randomized to 0mg of atorvastatin in phase 1 will receive 40mg of atorvastatin for a further 3 month period. The remaining subjects will not be randomized to study drug in phase II of the study. Lipid profiles, liver function tests and muscle enzymes will be measured prior to enrollment, and during the treatment phases of the study. Gene expression profiles in the peripheral blood will be measured using Affymetrix microarrays pre treatment and at the end of phases I and II.

Outcome measures: (1) Gene changes induced by statin treatment by dosage and over time; (2) Accuracy of vascular gene panel for defining gene expression changes induced by statin treatment; and (3) Correlations of gene expression changes with conventional vascular risk factors, changes in lipid and inflammatory markers and determination of best vascular risk prediction paradigm.