Shanghai Chest Hospital, Shanghai Jiao Tong University Shanghai, Shanghai
X. Su1, Y. Zeng2, J. Jia1, Y. Wang1, Y. Lu1, Y. Z. Deng3, and X. Cai1; 1Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China, 2Department of Radiation Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University, Shanghai, China, 3Shanghai Institute of Thoracic Oncology, Shanghai Chest Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, shanghai, China
Purpose/Objective(s): Fibroblasts (FB) have been identified as key players in radiation-induced heart disease (RIHD). However, the FB heterogeneity and effect of FB subtypes on the development of RIHD remain unknown. This study aims to characterize pivotal FB subpopulations involved in RIHD. Materials/
Methods: C57BL/6J male mice were treated with a single fraction (20Gy) of irradiation to the whole heart (IR group, n=3) or sham irradiation (NC group, n=3). At 9 weeks after irradiation, heart tissues were subjected to Single-nucleus RNA sequencing by a 10x Genomics-based protocol. Immunofluorescence (IF) and Flow cytometry were used to validate the key results. Results: Twenty-two distinct cell subsets encompassing 50093 cells were identified. Next, we selected FB clusters based on the expression of FB markers (Col1a1, Pdgfra, Gsn) and obtained a total of 13527 FB cells. Then, we performed a sub-clustering analysis of FB cells. We observed that the subset of POSTN+ FBs was increased in the IR group and presented gene expression signatures related to extracellular matrix remodeling. Notably, MHC class II (MHC II)–related genes, CD74+ FBs, were also enriched in the IR group and presented gene expression signatures related to antigen processing and presentation. IF revealed the presence of CD74+/Pdgfra+ double-positive FBs in the IR group. Flow cytometry confirmed a significant increase of MHCII+ FBs in the IR group after 9 weeks. Conclusion: These findings demonstrate that the CD74+/POSTN+ FBs were key subpopulations of RIHD, which may provide novel insights into the potential mechanisms of RIHD.
