Abstract 660: Inhibition of 14q32 “AngiomiR” MicroRNA-494 Reduces Atherosclerotic Lesion Formation, Increases Plaque Stability and Lowers Cholesterol Levels

Abstract

We have shown that inhibition of 14q32 microRNAs (miRs) miR-329, miR-487b, miR-494 and miR-495 increased both angiogenesis and arteriogenesis, leading to a 40% increase in blood flow recovery after ischemia. As many vascular remodelling processes share underlying mechanisms, we also investigated the effects of 14q32 microRNA inhibition in atherosclerosis When looking at expression patterns of 14q32 “angiomiRs”, we found that miR-494 was abundantly expressed in murine tissues involved in atherosclerosis, including the liver, spleen and carotid arteries. When looking at human carotid artery lesions, we found that miR-494 expression was doubled in vulnerable plaques compared to plaques of a stable phenotype. We used Gene Silencing Oligonucleotides (GSOs) to inhibit miR-494 in ApoE-/- mice, after placing semi-constrictive collars around both carotid arteries for 28 days to induce atherosclerotic lesion formation. We observed efficient uptake of IRD-800CW-labeled GSO-494 into the carotid artery, leading to a 50% reduction of miR-494 expression and significant upregulation of multiple anti-atherogenic target genes. Atherosclerotic lesion formation was drastically reduced in mice treated with GSO-494 (GSO-Control: 47 ± 11*103 μm2; GSO-494: 16 ± 3*103 μm2), while plaque stability was increased, determined by both a decrease in necrotic core size and an increase in plaque collagen content. Furthermore, inhibition of miR-494 resulted in increased cholesterol efflux in vitro (p<0,05). Indeed, in vivo, plasma total cholesterol levels and VLDL fractions were decreased after miR-494 inhibition (GSO-Control: 30.4 ± 1.1 mM; GSO-494: 26.4 ± 0.7 mM). In conclusion, inhibition of miR-494 results in smaller, more stable, atherosclerotic lesions, while simultaneously improving neovascularization. The so-called Janus phenomenon, which is a major drawback in translation towards the clinic, is hereby circumvented. The 14q32 miR-494 therefore provides a promising novel therapeutic target in prevention and treatment of atherosclerotic diseases.