Abstract P3090: The Role Of Circular Cdr1as In Macrophage Cardiac Inflammation And Fibrosis

Abstract

In response to cardiac injury, macrophages are recruited in high numbers to the infarcted myocardium and undergo phenotypic switching from pro-inflammatory in the early stage to anti-inflammatory in the later stage. Thereby, controlling the initiation, maintenance, and resolution of the inflammatory response. Circular RNAs are newly discovered non-coding RNA generated from protein-coding genes that implicated in the regulation of immune cells. However, there are currently no reports on the role of circRNAs in macrophage biology and function during cardiac ischemia. We aim to determine the specific role of circ-CDR1as in macrophage class switching and how circ-CDR1as modulates function post-cardiac injury. We performed circular RNA microarray analyses to assess circRNA transcriptome changes using RNA isolated from bone marrow derived macrophages (BMDM) polarized to a M1 or M2 phenotype. We validated circRNA expression by RT-qPCR in 3D post-MI hearts and within specific cell types. We generated circCdr1as overexpression plasmid transfected into BMDM, changes in phenotype were determined by FACS and RT-qPCR analysis. We generated circ-CDR1as overexpression associated adenoviral vector plasmid under control of CMV promoter and administered by tail vein injection. LV function was determined by echocardiography. Macrophage phenotype and CD31 was determined by immunohistochemistry and fibrosis by masson trichrome staining. Circ-CDR1as is downregulated in M1 macrophages and upregulated in M2 macrophages. There is a downregulation of cdr1as in cardiomyocytes and macrophages (F4/80+) 3 days post MI, during which pro-inflammatory macrophages are dominant. Administration of AAV9 circCDR1as in vivo significantly improved %EF and %FS at 21 and 28D days post-MI. Masson trichrome staining showed significant decrease in fibrotic area. Additionally, there is an increase in CD206+ cells at the border zone/infarcted area. This study suggests that circ-Cdr1as plays a role in macrophage biology by upregulating anti-inflammatory markers to promote an M2 phenotype and exogenous gene delivery of circCDR1as may improve LV function over time. Therefore, circ-Cdr1as may potentially be a therapeutic for the resolution of inflammation after cardiac injury.