Abstract MP41: Myeloid Ccn3 Protects Against Aortic Valve Calcification

Objective: CCN3, an inhibitor in osteoblast differentiation, can modulate calcium signaling, yet, whether CCN3 can regulate valvular calcification is unknown. While it has been suggested that macrophages are important in the regulation of valvular calcification, the molecular and cellular mechanisms of this process remain poorly understood. In the present study, we investigated the specific role that macrophage-derived CCN3 plays during the progression of calcific aortic valve disease (CAVD). Methods and Results: Myeloid-specific knockout of CCN3 (Mye-CCN3-KO) and control mice were subjected to a single injection of AAV encoding mutant mPCSK9 (rAAV8/D377Y-mPCSK9) to induce hyperlipidemia. AAV-injected mice were then fed a high fat diet (HFD) for 40 weeks. At the conclusion of HFD feeding, tissues were harvested for subsequent histological and pathological analysis. Echocardiography revealed that both male and female mye-CCN3-KO animals displayed compromised aortic valvular function accompanied by exacerbated valve thickness and cardiac dysfunction. Histologically, alizarin red and OsteoSense staining revealed a marked increase of aortic valve calcification in mye-CCN3-KO animals when compared to controls. In vitro, CCN3 deficiency augmented bmp2 production and secretion from bone marrow derived macrophages (BMDMs). Further, human valvular interstitial cells (VICs) cocultured with conditional media from CCN3-deficient BMDMs resulted in exaggerated pro-calcifying gene expression and the attendant calcification as revealed by alizarin red staining. Conclusions: Our data uncovered a novel role of myeloid CCN3 in the regulation of aortic valve calcification. Modulation of bmp2 production and secretion in macrophages might serve as a key mechanism for CCN3’s anti-calcification function in the development of CAVD.