Abstract 14484: 14q32 MicroRNA Inhibition Reduces Atherosclerotic Lesion Formation, Increases Plaque Stability and Lowers Cholesterol Levels
Introduction and Hypothesis: Atherosclerosis is a multifactorial disease involving inflammatory, metabolic and lipid-related processes. As microRNAs (miRs) regulate expression of up to several hundred target genes, we hypothesized that specific miRs may target not just single aspects of atherosclerosis, but atherosclerosis as a whole. We set out to identify miRs that target genes in all processes involved in atherosclerotic plaque formation. 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 were fed a Western type diet to induce hypercholesterolemia and semi-constrictive collars were placed 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 with 0.5 mg GSO at day 18. Mice were sacrificed at day 28 and both carotid arteries, liver tissue and blood samples were harvested.
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 clearly increased in mice treated with GSO-494 and GSO-495, determined by both a significant decrease in necrotic core size (GSO-494: 80% decrease; GSO-495: 60% decrease compared to GSO-Control) and a significant 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 total 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 identifies 14q32 miRs as promising therapeutic targets in atherosclerosis.
- © 2013 by American Heart Association, Inc.