Abstract 1047: Cerebral Cavernous Malformation 2 Knockout Hinders Murine Atherosclerosis And Lowers Vascular Inflammation

Introduction: Genome-wide association studies (GWAS) have identified >300 loci associated with coronary artery disease (CAD). The chr7p13 locus harbors several variants associated with decreased CAD risk, which are within the exon or the potential regulatory element of cerebral cavernous malformation 2 (CCM2, odds ratio = 0.95, p=1.53e-08). While CCM2 has been studied in venous endothelial cells (ECs) in the context of cerebral cavernous malformation, the role of CCM2 in aortic ECs and coronary atherosclerosis remains unknown. Methods and Results: To test whether CCM2 regulates atherosclerosis development, CCM2 heterozygous knockout (CCM2 +/-) mice and their control littermates (CCM2 +/+) were injected with AAV-PCKS9-D377Y and subjected to a high-fat, high cholesterol diet for 12 weeks. Atherosclerotic lesions were quantified at three different aortic sites (aortic root, minor aortic arch, and the brachiocephalic artery). Notably, heterozygous CCM2 knockout mice exhibited reduced atherosclerosis lesion in the aortic root in male mice (p=0.03), but not in female mice. Next, we sought to understand the mechanism by which CCM2 regulates the development of atherosclerosis. Single cell RNA-seq was conducted using aorta from CCM2 +/- mice and CCM2 +/+ mice. Gene set enrichment analysis on the EC population suggested that CCM2 heterozygous knockout suppressed inflammation pathways especially the TNF-alpha signaling pathway. Concordantly, after 12-weeks of high-fat, high cholesterol diet, the number of monocytes in the aorta were decreased in CCM2 +/- mice when compared to CCM2 +/+ mice. Furthermore, in vitro, ECs lacking CCM2 showed impaired THP-1 monocyte adhesion (p=0.001) and decreased expression of MCP-1 (p=3e-4). Conclusions: Our findings suggest that CCM2 heterozygous knockout hinders the development of atherosclerosis. This is likely achieved by lowering MCP-1 expression and decreasing monocyte recruitment. Further investigations are being conducted to functionally identify the causal variant in the CCM2 locus, specifically under disease-relevant stimuli, to further our understanding of CCM2’s potential as a diagnostic and therapeutic target in CAD.