Bender, S. B. | bioRxiv Science

bioRxiv2024

Genetic silencing of KCa3.1 inhibits atherosclerosis in ApoE null mice

Increased expression of KCa3.1 has been found in vascular smooth muscle (SMC), macrophages, and T cells in atherosclerotic lesions from humans and mice. Proliferating SMC cells increase the expression of KCa3.1, such that it becomes a dominant K+ channel and contributes to SMC cell migration. The efficacy of pharmacological inhibition of KCa3.1 in limiting atherosclerosis progression has been demonstrated in mice and pigs, however direct, loss-of-function, i.e. gene silencing, studies are absent. To investigate the role of KCa3.1, we used CRISPR/Cas9 to generate KCa3.1-/-Apoe-/- (DKO) mice and assessed lesion development in the brachiocephalic artery (BCA) of DKO versus Apoe-/- mice on a Western diet for 3 months. Notably, the loss of KCa3.1 did not affect serum total cholesterol or body weight. In BCAs of DKO mice, lesion size (0.036 mm{superscript 2} vs. 0.118 mm{superscript 2}, p<0.05) and relative stenosis (13.9% vs. 43.0%, p<0.05) were reduced by 70% compared to Apoe-/- mice, with no effect on medial or lumen area. Additionally, DKO mice exhibited a significant reduction in macrophage content within atherosclerotic plaques compared to Apoe-/- mice, independent of sex. In vitro migration assays further showed a significant reduction in migration of bone marrow-derived macrophages (BMDMs) from DKO mice compared to those from Apoe-/- mice. Furthermore, in vitro experiments using rat aortic smooth muscle cells (RAOSMCs) revealed significant inhibition of PDGF-BB-induced MCP1/Ccl21 expression upon KCa3.1 inhibition, while activation of KCa3.1 further enhanced MCP1/Ccl21 expression. Both in vivo and in vitro analyses showed that silencing KCa3.1 and sex had no significant effect on the collagen content of plaque. RNAseq analysis of BCA samples from DKO and Apoe-/- mice revealed PPAR-dependent signaling as a potential key mediator of the reduction in atherosclerosis due to KCa3.1 silencing. Overall, this study provides the first genetic evidence that KCa3.1 is a critical regulator of atherosclerotic lesion development and composition and provides novel mechanistic insight into the link between KCa3.1 and atherosclerosis.

physiology↗

bioRxiv2022

Multi-omic analysis of the cardiac cellulome defines a vascular contribution to cardiac diastolic dysfunction in obese female mice

Coronary microvascular dysfunction (CMD) is associated with cardiac dysfunction and predictive of cardiac mortality in obesity, especially in females. Emerging evidence suggests development of heart failure with preserved ejection fraction in females with CMD and that mineralocorticoid receptor (MR) antagonism may be more efficacious in obese female, versus male, HFpEF patients. Accordingly, we examined the hypothesis that smooth muscle cell (SMC)-specific MR deletion prevents obesity-associated coronary and cardiac diastolic dysfunction in females. Obesity was induced in female mice via western diet (WD) feeding alongside littermates fed standard diet. Initial studies revealed that global MR blockade with spironolactone prevented impaired coronary vasodilation and diastolic dysfunction in obese females. Importantly, specific deletion of SMC-MR similarly prevented obesity-associated coronary and cardiac dysfunction. Cardiac gene expression profiling suggested reduced cardiac inflammation in WD-fed mice with SMC-MR deletion independent of blood pressure, aortic stiffening, and cardiac hypertrophy. Further mechanistic studies utilizing single-cell RNA sequencing of non-cardiomyocyte cell populations revealed novel impacts of SMC-MR deletion on the cardiac cellulome in obese mice. Specifically, WD feeding induced inflammatory gene signatures in multiple non-myocyte populations (B/T cells, macrophages, and endothelium), independent of cardiac fibrosis, that was prevented by SMC-MR deletion. Further, SMC-MR deletion induced a basal reduction in cardiac mast cells and prevented WD-induced cardiac pro-inflammatory chemokine expression and leukocyte recruitment. These data reveal a central role for SMC-MR signaling in obesity-associated coronary and cardiac dysfunction thus supporting the emerging paradigm of a vascular origin of cardiac dysfunction in obesity.

physiology↗