Single-cell transcriptomic profiling reveals PDK4 upregulation and impaired VEGF-C/VEGFR3 signaling in cardiac lymphatic endothelial cells in diabetic cardiomyopathy

BACKGROUND: Diabetic cardiomyopathy (DCM) is characterized by microvascular dysfunction. While vascular endothelial cells (ECs) have been widely studied, the role of cardiac lymphatic ECs (LECs) in DCM remains unknown. METHODS: A mouse model of DCM was induced by a high-fat diet (HFD) with streptozotocin (STZ) injection. We performed single-cell RNA sequencing (scRNA-seq) on cardiac tissues from mice with DCM and control mice. We then applied clustering, RNA velocity, pseudotime analysis, and CellChat cell-cell communication analysis to define lymphatic endothelial cell (LEC) heterogeneity and underlying regulatory networks. RESULTS: Our analysis revealed profound pathological remodeling of the cardiac lymphatic architecture in diabetic hearts, marked by decreased LEC numbers and impaired function. Cell-cell communication analysis demonstrated impaired VEGF-C/VEGFR3 signaling between venous ECs (VECs) and LECs in diabetic hearts. We identified the upregulation of pyruvate dehydrogenase kinase 4 (PDK4) expression in diabetic LECs as a key driver of metabolic reprogramming, leading to impaired cell migration. CONCLUSIONS: This study mapped the profile of LECs in diabetic hearts and revealed a dual pathogenic mechanism involving metabolic disorders driven by PDK4 and disruption of venous-lymphatic communication. These findings may provide new strategies for the treatment of DCM.