Abstract 17622: CCN3 Deficiency in Myeloid Cells Exacerbates Aortic Dissection by Governing a Proinflammatory Program in Macrophages

Abstract

Introduction: Aortic dissection (AD) is a fatal disease. Macrophages are known central regulators of aortic inflammation and elastic fiber disruption, two major hallmarks of AD. Cellular communication network factor 3 (CCN3/NOV) is a matricellular protein associated with various biological cellular functions in cardiovascular disease and cancers. Emerging evidence strongly implicates a protective role of CCN3 against several types of vascular pathologies, however its role in AD remains unknown. Hypothesis: CCN3 deficiency in myeloid cells promotes AD development in murine models through the modulation of macrophage phenotype. Aims: We investigated the causal role of CCN3 loss in AD pathogenesis, focusing on its role in macrophages. Methods: 3-4-week-old male myeloid-specific CCN3 knockout mice (CCN3F/F;LysMCre) and control mice (LysMCre) were given BAPN (β-aminopropionitrile monofumarate; 0.2%) in their drinking water for 4 weeks for AD modeling. Mouse survival rate and histological changes of the aorta were assessed. Single cell RNA sequencing analysis was performed to recapitulate cellular transcriptome profile changes. Finally, gain and loss of function studies in bone marrow-derived macrophages (BMDMs) were performed to decipher the underlying mechanism by which CCN3 controls macrophage plasticity. Results: Following BAPN administration, myeloid-specific CCN3 knockout mice had a higher mortality rate due to AD formation and aortic rupture. In accordance with this phenotype, vascular media thickness was markedly reduced, and elastic fiber fragmentation and macrophage infiltration were elevated in myeloid-specific CCN3 knockout mice. Using single-cell RNA-seq, we found that myeloid-deficiency of CCN3 was associated with a pathogenic pro-inflammatory phenotype of perivascular tissue-resident macrophages, which promoted deleterious aortic wall remodeling at early stages. Furthermore, CCN3 deficient BMDMs are prone to M1 macrophage polarization, an effect dependent on the activation of the JAK/STAT1 signaling pathway. Conclusions: Myeloid-deficiency of CCN3 drives vascular macrophages toward an M1-like, pathogenic phenotype and promotes dissecting aortic aneurysm.