Cross-Dataset Validation of Activated Fibroblast Phenotypic Shift and Signatures in Dilated Cardiomyopathy at Single-cell Resolution

Dilated cardiomyopathy (DCM) is characterized by progressive ventricular remodeling, in which cardiac fibroblast activation drives excessive extracellular matrix deposition, fibrosis, and subsequent functional decline. Recent studies have highlighted the expansion of a pathologically activated fibroblast subpopulation with pro-inflammatory and pro-fibrotic properties that plays a central role in disease progression. However, this subpopulation remains incompletely defined due to a lack of systematic cross-dataset validation to confirm its conserved gene signatures and enriched pathways.  

 

Here, we present a comprehensive cross-cohort analysis to identify, characterize, and validate this fibroblast subpopulation across multiple single-cell RNA sequencing (scRNA-seq) and single-nuclei sequencing (snRNA-seq) datasets curated in the Pythiomics database - a standardized and harmonized omics data resource developed by Pythia Biosciences. We consistently observed a marked overrepresentation of this fibroblast population in DCM compared to healthy controls, underscoring its disease-specific enrichment. Cross-dataset differential expression analysis revealed a conserved, cell-type-specific gene signature including THBS4, POSTN, ANO1, MEOX1, and DDAH1. Pathway analysis further revealed the activation of extracellular matrix remodeling and mechanotransduction process, while immune-modulatory and vasoregulatory signaling pathways were concurrently suppressed. Together, these findings provide a robust molecular definition of the pathological fibroblast subpopulation in DCM and lay the foundation for targeted functional studies and therapeutic exploration.