Single‐cell RNA sequencing reveals a mechanism underlying the susceptibility of the left atrial appendage to intracardiac thrombogenesis during atrial fibrillation

• Published in: Clinical and translational medicine 2023-06, Vol.13 (6), p.e1297-n/a
• Main Authors: Yang, Jie, Tan, Hu, Sun, Mengjia, Chen, Renzheng, Jian, Zhao, Song, Yuanbin, Zhang, Jihang, Bian, Shizhu, Zhang, Bo, Zhang, Yi, Gao, Xubin, Chen, Zhen, Wu, Boji, Ye, Xiaowei, Lv, Hailin, Liu, Zhen, Huang, Lan
• Format: Article
• Language: English
• Subjects: ADAMTS1; Animals; Anticoagulants; Anticoagulants - metabolism; Atrial Appendage - metabolism; atrial fibrillation; Atrial Fibrillation - complications; Atrial Fibrillation - genetics; Blood clots; Cardiac arrhythmia; Clinical medicine; Embolisms; endocardial endothelial cells; Endothelial Cells - metabolism; Gene expression; Genomes; Genomics; Hemodynamics; Inflammation; Mice; Ontology; Sequence Analysis, RNA; Shear stress; single‐cell RNA‐sequencing; TFPI family; Thromboembolism; thrombogenesis; Thrombosis - genetics
• ISSN: 2001-1326; 2001-1326
• DOI: 10.1002/ctm2.1297

Background Atrial fibrillation (AF) is associated with an increased risk of thrombosis of the left atrial appendage (LAA). However, the molecular mechanisms underlying this site‐specificity remain poorly understood. Here, we present a comparative single‐cell transcriptional profile of paired atrial appendages from patients with AF and illustrate the chamber‐specific properties of the main cell types. Methods Single‐cell RNA sequencing analysis of matched atrial appendage samples from three patients with persistent AF was evaluated by 10× genomics. The AF mice model was created using Tbx5 knockout mice. Validation experiments were performed by glutathione S‐transferase pull‐down assays, coimmunoprecipitation (Co‐IP), cleavage assays and shear stress experiments in vitro. Results In LAA, phenotype switching from endothelial cells to fibroblasts and inflammation associated with proinflammatory macrophage infiltration were observed. Importantly, the coagulation cascade is highly enriched in LAA endocardial endothelial cells (EECs), accompanying the up‐regulation of a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1) and the down‐regulation of the tissue factor pathway inhibitor (TFPI) and TFPI2. Similar alterations were verified in an AF mouse model (Tbx5+/−) and EECs treated with simulated AF shear stress in vitro. Furthermore, we revealed that the cleavage of both TFPI and TFPI2 based on their interaction with ADAMTS1 would lead to loss of anticoagulant activities of EECs. Conclusions This study highlights the decrease in the anticoagulant status of EECs in LAA as a potential mechanism underlying the propensity for thrombosis, which may aid the development of anticoagulation therapeutic approaches targeting functionally distinct cell subsets or molecules during AF. Single‐cell RNA‐sequencing revealed atrial appendage‐specific transcriptional heterogeneity of atrial fibrillation patients. Differences in the local expression of anticoagulants by endocardial endothelial cells (EECs) contribute to the left atrial appendage (LAA)‐specific propensity for thrombogenesis. Deficiency of the anticoagulants TFPI and TFPI2 in the EECs of the LAA can be attributed to the proteolytic activity of ADAMTS1 in response to shear stress.