Abstract 15353: JNK2 RNA Silencing Promotes Plaque Healing and Reduces Thrombotic Risk in Atherosclerotic Mice

Introduction: JNK2, one of three isoforms in the c-jun N-terminal kinase family, is a principal mediator of foam cell formation by activating the macrophage scavenger receptor signaling pathway. Although JNK2 is a clear therapeutic target for suppressing atherosclerosis, there are no approved pharmaceutical agents with acceptable isoform specificity and safety profiles. To this end, we report the utility of a new potent peptide-based siRNA delivery nanoplatform that rapidly conveys serum-stable anti-JNK2 oligonucleotides into growing plaques but not to normal vasculature. Methods and Results: ApoE null mice were fed a Western diet for 3 months followed by treatment for one month (2x/week i.v.; 7 total doses) with a 55 nm siRNA-p5RHH nanoparticle specific for JNK2. Evaluation of thrombotic risk by conventional dye-laser injury to the carotid artery revealed a 118% increase in clotting times, indicative of attenuated thrombotic risk. Endothelial barrier integrity was restored according to magnetic resonance spectroscopic measurements of ~200 nm semipermeant perfluorocarbon ( 19 F) nanoparticles that penetrated aortic plaques after 2 hours of circulation time, revealing a 60% reduction in plaque permeability in treated mice indicative of endothelial healing. JNK2 knockdown in plaques was confirmed by RT-PCR and Western assays, yielding reduced plaque necrosis and macrophage content. Interestingly, inflammatory signaling through NF-κB was reduced according to confocal images of nuclear p65 in plaques where 43% of neointimal cells from the control animals exhibited activated NF-κB signaling, but only 22.48% of cells were positive after JNK2 knockdown, a 47% reduction despite serum cholesterol levels u003e 1000 mg/dl. Safety was confirmed by normal serum blood test values after multiple doses, and no stimulation of innate or adaptive immunity. Conclusions: RNA silencing of c-jun N-terminal kinase 2 (JNK2) in atherosclerotic mice rapidly restores endothelial barrier integrity, reduces thrombotic risk, and decreases plaque inflammation in hypercholesterolemic mice.