Background: Doxorubicin cardiomyopathy (DoxCM) remains a significant clinical problem, but its underlying mechanisms remain incompletely understood. Identifying DoxCM mechanisms can lead to therapeutic interventions that improve patient outcomes.
Methods: We performed single-nucleus RNA sequencing on left ventricular myocardial tissue from patients with DoxCM versus nonischemic cardiomyopathy and nonfailing donors. This approach aimed to uncover the transcriptional changes associated with DoxCM. Additionally, we conducted immunostaining, flow cytometry, antibody neutralization, and cell depletion studies to validate our findings and define in vivo mechanisms.
Results: Compared with nonfailing donors and patients with nonischemic cardiomyopathy, left ventricular myocardium from patients with DoxCM exhibited increased POSTN (periostin)+ activated fibroblasts, downregulation of genes involved in phagocytosis, and increased expression of the antiphagocytic molecule CD47. Immunostaining of human cardiac sections and murine studies demonstrated increased POSTN+ cells and CD47 in DoxCM and in a murine breast cancer model. CD47 antibody neutralization both prevented and treated doxorubicin-induced reduction in left ventricular ejection fraction and fibrosis. Mechanistically, depletion of resident cardiac macrophages blocked the cardioprotective effects of CD47 neutralization and clearance of cardiac fibroblasts.
Conclusions: Our data support CD47 as a disease-specific target and promising therapeutic approach for mitigating cardiac dysfunction in DoxCM.
Keywords: CD47; activated fibroblasts; doxorubicin cardiomyopathy; resident macrophage.