Cell-specific role and therapeutic potential of KCa3.1 in atherosclerosis

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Pathogenesis of coronary artery disease is complex, with multiple cell types contributing to lesion size and composition. Acute coronary syndromes are most often associated with rupture of complex, vulnerable plaques that are otherwise clinically benign. The progression to either a relatively benign, stable lesion or a rupture-prone, vulnerable plaque has been linked to key lesion characteristics, i.e. smooth muscle (SM) and collagen content, macrophage infiltration and necrotic core area within the lesion. The objectives of this proposal are to 1) determine the SM-specific role and underlying mechanism(s) by which the intermediate conductance, Ca2+-activated K+ channel, KCa3.1 (encoded by Kcnn4), dictates atherosclerotic lesion formation and composition and 2) determine the translational potential of clinically approved KCa3.1 inhibitors on lesion development in a large mammal model of coronary artery disease (CAD). In support, we provide the first genetic evidence of a causal link between KCa3.1 and lesion size and SM and macrophage recruitment. The overall hypothesis is that KCa3.1 activation increases migration of SM and macrophages into the intima and contributes to lesion formation. Conversely, blocking KCa3.1, both by genetic silencing or pharmacologically, will decrease atherosclerotic lesion size and beneficially alter composition. Aim 1 will determine the contribution of KCa3.1 in smooth muscle to atherosclerotic lesion formation and composition. Specifically, we will use SM-specific, inducible KO mice to examine the role of KCa3.1 in determining plaque size, composition and gene expression. Aim 2 will define both upstream (REST) and downstream (DOCK2) mechanisms determining KCa3.1 effects on SM and atherosclerosis. We will use genetically modified mice to examine the role of REST and DOCK2 in mediating SM effects of KCa3.1 on phenotype, proliferation, migration, plaque size and composition. In addition, we will use RNA sequencing to identify novel mechanisms of atherosclerosis development by KCa3.1. We will use VSM lineage-tracking in Aim 3 will use SM lineage-tracking to determine role of SMC-KCa3.1 in mediating SMC intimal to medial migration and foam cell transdifferentiation during atherosclerotic lesion development. Finally, Aim 4 will determine the effect of the FDA approved KCa3.1 inhibitor, senicapoc, on atherosclerosis development in a swine model of CAD. We longitudinally track coronary artery disease progression using angiography and IVUS in familial hypercholesterolemic (FH) swine to test the ability of KCa3.1 inhibition with senicapoc, to decrease the size and promote a more favorable composition of coronary lesions. The long-term goal is to provide the pre-clinical foundation for translating current therapeutic tools and developing the next generation drugs targeting KCa3.1 and/or downstream signaling to beneficially manipulate atherosclerotic lesion composition.