Osteopontin-expressing valvular interstitial cell subpopulation as a driver of extracellular matrix remodeling in aortic valve disease.

INTRODUCTION

Aortic valve disease (AVD) is a cardiovascular disorder highly prevalent in the elderly population. Aortic valve leaflets suffer hardening due to extracellular matrix (ECM) remodeling and subsequent calcification, leading to impaired blood flow and aortic valve stenosis. Valve interstitial cells (VICs) are fibroblast-like cells that can undergo myofibroblast activation and osteogenic transformation, contributing to disease progression.

METHODS

We performed a bioinformatic re-analysis of a publicly available scRNA-seq dataset to identify pathogenic VIC subpopulations and characterize cell-cell communication networks relevant to early AVD.

RESULTS

Re-analysis of scRNA-seq data from aortic valves of Apoe -/- and Ldlr -/- mice revealed a distinct VIC subpopulation enriched in osteopontin (Spp1), fibromodulin (Fmod), and chondrocyte-specific genes, including Chad, Comp, and Cilp2. Differential expression and gene ontology enrichment analyses indicated a strong signature of ECM organization and remodeling in this cluster under atherosclerotic conditions. Cell-cell communication analysis using CellChat showed enhanced intercellular signaling involving the VIC Spp1+ cluster. Moreover, incoming interaction strength was increased through collagen, fibronectin, Spp1, and cyclophilin A (CypA) signaling pathways, while the thrombospondin pathway was decreased. NicheNet analysis suggested a crosstalk between VICs Spp1+ with immune and valvular cells via receptors such as Icam1, Itgav, osteoprotegerin, Sdc4, and Itga10. Moreover, gene regulatory network reconstruction using pySCENIC identified NFE2L1 as a shared transcriptional regulator in both hyperlipidemic conditions, potentially driving the fibrotic program in VIC Spp1+ across both models.

DISCUSSION: These findings suggests the presence of a disease-associated VIC Spp1+ subpopulation, that may contribute to valve sclerosis through ECM remodeling and deposition, providing mechanistic insights into early valve sclerosis.