Cross-dataset transcriptomic analyses identify a conserved ENPP2+ macrophage–fibroblast activation axis in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a condition where approximately 65% of patients exhibit myocardial fibrosis, indicated by late gadolinium enhancement, with the severity and extent of fibrosis being positively correlated with the risk of sudden cardiac death. While fibroblast activation in HCM has been noted in previous studies, the underlying regulatory mechanisms have not been thoroughly explored. In this study, we analyzed the latest single-nucleus sequencing (snRNA-seq) datasets related to HCM caused by the two most common mutations. We also examined the largest existing snRNA-seq and spatial transcriptomics datasets of HCM for external validation. Additionally, we conducted preliminary histopathological and molecular biology experiments to validate our findings and explore potential mechanisms. Our analysis revealed a phenotypic transformation of macrophages in both cases of HCM. These pro-inflammatory macrophages, driven by the high expression of ENPP2, mediated intercellular interactions that influenced fibroblast activation. The resulting increase in lysophosphatidic acid appeared to act as a plausible intermediary. Activated fibroblasts secreted substantial amounts of COL14A1, which is a critical component of myocardial fibrosis. These findings were consistent across different genetic backgrounds, suggesting their universal applicability in most HCM cases. Our study provides valuable insights into the mechanisms underlying myocardial fibrosis in HCM, highlighting the role of macrophage transformation and fibroblast activation. These findings offer potential for the identification of novel diagnostic or prognostic biomarkers and the development of targeted therapies with clinical translational potential.