Abstract 13518: Augmenting SOD2 Levels in Apoe -/- Mice With Peptide-mRNA Nanoparticles Preserves Atherosclerotic Plaque Stability in Advanced Atherosclerosis

Abstract

Erosion or rupture of the advanced atherosclerotic plaque is the leading cause of atherosclerosis complications such as acute coronary syndrome and stroke. Atherosclerotic plaques in aging hypercholesterolemic mice have decreased SOD2 levels and increased mitochondrial oxidative stress, which leads to cell apoptosis, necrotic core expansion, and fibrous cap thinning and rupture. We hypothesized that increasing SOD2 expression in advanced atherosclerotic plaque cells in mice using mRNA polyplex would protect mitochondria from oxidative damage and preserve plaque stability. Macrophages isolated from Sod2 +/- mice treated with amphipathic cationic peptide p5RHH: Sod2 mRNA polyplexes had markedly increased levels of Sod2 mRNA and mitochondrial SOD2 (p<0.01), higher SOD activity, which resulted in lower levels of mitochondrial and cellular reactive oxygen species (ROS) and improved mitochondrial function. RNA-Seq analysis showed that macrophages treated with Sod2 nanoplexes had broadly decreased inflammatory cytokines and immune activation pathways. In Apoe -/- mice, atherosclerotic lesions with vulnerable plaque features were induced in the carotid artery by placing a perivascular collar over the carotid artery and 4-months Western diet. Mice were treated for 4 weeks with saline or with 0.5 mg/kg p5RHH: Sod2 mRNA polyplexes which selectively accumulated in atherosclerotic lesion macrophages. The carotid plaques of the mice treated with Sod2 mRNA differed significantly from the plaques of the control Apoe -/- mice by higher SOD2 expression, lower mitochondrial ROS and oxidative DNA damage, and reduced expression of CCL2, IL1, IL6, MMP 2 and 9 (p<0.01). Sod2 polyplexes-treated mouse plaques exhibited 25% fewer inflammatory macrophages (p<0.01) and 98% more smooth muscle cells (p<0.001) with a reduced lipid core, preserved fibromuscular cap, and decreased plaque vulnerability index (p<0.05). The results suggest that selective overexpression of Sod2 in plaque macrophages using nanoplexes reduces mitochondrial stress and preserves plaque stability without adverse effects. Using nanoparticle-based mRNA therapeutics to modulate plaque morphology has great potential in the prevention and treatment of atherosclerosis complications.