Di Maria, L.; Boel, H.; Perzo, N.; Renet, S.; Valentin, C.; Lemarcis, T.; Marais, B.; Badji, Z.; Levesque, T.; Beziau-Gasnier, D.; Eltchaninoff, H.; Brakenhielm, E.; Durand, E.; Fraineau, S.

Background: Calcific aortic valve disease (CAVD) is the most common valvular heart disease in developed countries, yet no pharmacological therapy is available to slow or halt its progression. CAVD is driven by progressive calcification of aortic valve leaflets, in which myeloid cells play a central role. While macrophages have been implicated in CAVD pathogenesis, the contribution of their precursors, monocytes, remains poorly understood. We hypothesized that circulating monocytes acquire a pro-calcific and pro-inflammatory phenotype contributing to valve remodelling and CAVD progression. Methods: We profiled circulating CD14+ monocytes from healthy volunteers (Vol), patients with CAVD, and without CAVD (NCAVD). Peripheral blood mononuclear cells (PBMCs) were isolated, and monocyte subpopulations were phenotyped by flow cytometry. Transcriptome profiling by RNA sequencing identified disease-associated gene signatures, which were validated by RT-qPCR. The CD14+ monocyte secretome was analysed using multiplex assays. Functional ability of CAVD-derived CD14+ monocytes to induce myofibroblastic transdifferentiation (MT) and osteoblastic differentiation (OD) of human valvular interstitial cells (VICS) was evaluated by immunocytochemistry and quantitative o-cresolphthalein complexone assays. Results: In PBMCs, CAVD monocytes displayed a subpopulation shift, with an increased proportion of CD14CD16- classical monocytes and a reduced CD14CD16 non-classical monocyte levels. In CD14+ monocytes, transcriptomic analysis revealed upregulation of inflammation-related (PDK4) and calcification-related (ATP2B1) genes, alongside downregulation of immunomodulatory genes (DDR1, IKBKE). Secretome analysis showed reduced production of immunomodulatory and anti-osteoblastogenic cytokines (IL-4, CCL3) while promoting gene expression of factors promoting MT and OD in VICS. These alterations were associated with a marked monocyte-induced increase in SMA and OPN expression in VICS and a two-fold increase in calcification. Conclusion: We demonstrate for the first time that circulating monocytes from patients with CAVD exhibit enhanced pro-inflammatory and pro-calcific properties that may contribute to CAVD progression. Additionally, we identify dysregulated gene sets within these monocytes that represent potential novel therapeutic targets for CAVD.