Beyond the vessel wall: single-cell dissection of epicardial fat-myocardial crosstalk in coronary artery disease.

AIMS: Epicardial adipose tissue (EAT) has emerged as an active regulator of cardiovascular disease, yet the cellular and molecular features of myocardial-associated EAT (mEAT) in coronary artery disease (CAD) remain incompletely defined. METHODS AND RESULTS: We performed single-nucleus RNA sequencing of mEAT from patients with CAD (n = 9), nonCAD cardiovascular surgery patients (n = 9), and forensic controls without cardiac disease (n = 2), integrated with histology, CT-based EAT volume assessment, matched right atrial myocardium analysis, and functional in vitro assays. mEAT contained diverse adipocyte, stromal, immune, and vascular cell populations. In CAD, we identified two disease-enriched inflammatory cell states, inflammatory adipogenic cells (IAC) and inflammatory stromal cells (ISC), characterized by immune activation, stress-response signalling, extracellular matrix remodelling, and impaired adipogenic features. Histological analyses confirmed enlarged adipocytes, increased fibrosis, and higher abundance of IAC/ISC-associated markers in CAD-mEAT. Exploratory integration with CT imaging suggested a possible association between increased EAT volume and enrichment of inflammatory cell states. Comparative analyses with published adipose and cardiac single-cell datasets indicated that IAC and ISC share features with previously described inflammatory adipocyte and stromal populations, while displaying a distinct marker combination enriched in CAD-associated mEAT.Cell-cell communication analyses identified THBS1-CD36 and SEMA4A/SEMA3C-NRP1/PLXNA signalling as predicted CAD-associated communication axes involving inflammatory mEAT populations and myocardial cell types. Conditioned medium from CAD-mEAT-derived adipocytes/IAC altered contractile properties of human iPSC-derived cardiomyocyte (CM) microtissues, while simultaneously impairing endothelial tube formation and migration. Recombinant THBS1 and SEMA3C partially recapitulated selected effects, whereas combined CD36 and NRP1 blockade partially attenuated endothelial and CM responses. CONCLUSION: Together, these data provide a high-resolution map of CAD-associated mEAT remodelling and identify IAC and ISC as inflammatory cell states linked to altered adipose-vascular and adipose-myocardial signalling. These findings support the concept that cellular and molecular features of mEAT may complement imaging-based EAT assessment and inform future studies on CAD-associated adipose tissue inflammation.