Single-cell and extracellular vesicle profiling reveals fibroblast-macrophage crosstalk in epicardial adipose tissue during acute myocardial infarction

Background Epicardial adipose tissue (EAT) modulates coronary atherosclerosis via paracrine signalling. We aimed to define the cellular heterogeneity and extracellular vesicle (EV)-mediated crosstalk within human EAT during acute myocardial infarction (AMI). Methods We integrated single-cell RNA sequencing (scRNA-seq) and EV transcriptomic profiling of EAT from patients with AMI , unstable angina (UA), and non-coronary artery disease (non-CAD). Analyses included clustering, pseudotime trajectory inference, cell-cell communication (CellChat), and computational deconvolution of EV cellular origins. Results scRNA-seq revealed a dramatic shift in EAT cellularity during AMI, characterised by a 3.3-fold expansion of fibroblasts (dominated by profibrotic SPSB1+ and IGLC2+ subsets) and significant infiltration of myeloid cells, alongside a marked reduction in endothelial cells. Pseudotime analysis indicated inflammatory reprogramming of these key populations. Cell-cell communication analysis identified significantly reinforced fibroblast-macrophage crosstalk in AMI, primarily mediated by ECM ligand-receptor pairs FN1-CD44 and COL1A2-CD44. EV cargo analysis showed enrichment for TNF, mTOR, and IL-17 signalling pathways in AMI. Bioinformatic deconvolution suggested a shift in the predominant EV source from immune cells in UA to activated fibroblasts (~68% contribution) in AMI, with their cargo enriched for lipid metabolism and oxidative stress genes. Conclusion This study unveils an AMI-specific cellular and vesicular axis within EAT, featuring expanded profibrotic fibroblasts engaging reinforced crosstalk with macrophages. The concomitant shift towards a fibroblast-dominated EV profile suggests a novel paracrine mechanism. These findings highlight potential diagnostic and therapeutic targets within the EAT microenvironment for post-infarction remodelling.