Abstract 676: 14q32 MicroRNA Inhibition Reduces Atherosclerotic Lesion Formation and Increases Plaque Stability

Abstract

Introduction: Atherosclerosis is a multifactorial disease involving inflammatory, metabolic and lipid-related processes. As microRNAs (miRs) regulate expression of up to hundreds of target genes, we aimed to identify miRs that target genes involved in all processes of atherosclerosis. Using www.targetscan.org, we performed a Reverse Target Prediction on a set of 150 atherosclerosis-related genes. We found enrichment of binding sites for several miRs from a single gene cluster on human chromosome 14. Methods: ApoE-/- mice fed a Western type diet received semi-constrictive collars around both carotid arteries to induce atherosclerotic lesion formation. Gene Silencing Oligonucleotides (GSOs) were used to inhibit 3 14q32 miRs: miR-329, miR-494 and miR-495. Mice were injected with 1 mg GSO at day 4 after collar placement and again with 0.5 mg GSO at day 18. Mice were sacrificed at day 7 and day 28 for analysis of carotid arteries, liver, spleen, bone marrow and blood samples. Results: Atherosclerotic plaque analysis revealed a striking decrease of lesion size in mice treated with GSO-494 and GSO-495 (GSO-Control: 47 ± 11*103 μm2; GSO-494: 16 ± 3*103 μm2; GSO-495: 22 ± 5*103 μm2), whereas a trend towards reduced plaque size was observed in mice treated with GSO-329 (27 ± 6*103 μm2). Moreover, plaque stability was increased in mice treated with GSO-494 and GSO-495, determined by both a decrease in necrotic core size (GSO-494: 80% decrease; GSO-495: 60% decrease compared to GSO-Control) and an increase in plaque collagen content (GSO-Control: 6.6 ± 1.6%; GSO-494: 12.7 ± 2.1%; GSO-495: 15.8 ± 3.1%). Furthermore, inhibition of miR-494 and miR-495 resulted in decreased plasma cholesterol levels (GSO-Control: 30.4 ± 1.1 mM; GSO-494: 26.4 ± 0.7 mM; GSO-495: 26.4 ± 1.6) and decreased VLDL fractions. Conclusions: Inhibition of miR-494, miR-495 and, to a lesser extent, miR-329, leads to reduced plaque size, increased plaque stability and reduced plasma cholesterol levels. This makes 14q32 miRs promising novel therapeutic targets in atherosclerosis.