Upregulated FoxO1 promotes arrhythmogenesis in mice with heart failure and preserved ejection fraction [scRNA-seq]

Myocardial fibrosis leads to cardiac dysfunction and arrhythmias in heart failure with preserved ejection fraction (HFpEF), but the underlying mechanisms remain poorly understood. Here, RNA sequencing identifies Forkhead Box1 (FoxO1) signaling as abnormal in HFpEF hearts. Genetic suppression of FoxO1 alters the intercellular communication between cardiomyocytes and fibroblasts, alleviates abnormal diastolic relaxation, and reduces arrhythmias. Targeted downregulation of FoxO1 in activated fibroblasts reduces cardiac fibrosis, blunts arrhythmogenesis and improves diastolic function in HFpEF. These results not only implicate FoxO1 in arrhythmogenesis and lusitropy but also demonstrate that pro-fibrotic cardiomyocyte-fibroblast communication can be corrected, constituting a novel therapeutic strategy for HFpEF. Overall design: single-cell RNA sequencing from isolated left ventricular cells was performed to identify transcriptomic changes in C56Bl6 fed with a standard diet (control), High-Fat + L-NAME diet treated with AAV-scramble-sh (HFpEF-scr), and High-Fat + L-NAME diet treated with AAV-FoxO1-sh (HFpEF-FoxO1-sh).

射血分数保留型心力衰竭（heart failure with preserved ejection fraction, HFpEF）患者的心肌纤维化可诱发心功能障碍与心律失常，但其潜在机制仍未得到充分阐明。本研究通过RNA测序（RNA sequencing）发现，HFpEF模型小鼠的心脏中，叉头框蛋白O1（Forkhead Box1, FoxO1）信号通路存在异常。对FoxO1进行基因沉默可改变心肌细胞与成纤维细胞间的细胞通讯，改善异常舒张功能，并减少心律失常的发生。在活化成纤维细胞中靶向下调FoxO1的表达，可减轻HFpEF模型中的心肌纤维化，抑制心律失常发生，并改善舒张功能。上述研究结果不仅揭示了FoxO1在心律失常发生与心肌舒张性能调控中的作用，同时证实了促纤维化的心肌细胞-成纤维细胞间通讯可被纠正，为HFpEF提供了全新的治疗策略。实验整体设计：通过对分离得到的左心室细胞进行单细胞RNA测序（single-cell RNA sequencing），分析三组小鼠的转录组变化：饲喂标准饲料的C56Bl6小鼠（对照组）、饲喂高脂+L-NAME饲料并经腺相关病毒（adeno-associated virus, AAV）介导的乱序短发夹RNA（AAV-scramble-sh）处理的小鼠（HFpEF-scr组），以及饲喂高脂+L-NAME饲料并经AAV介导的FoxO1短发夹RNA（AAV-FoxO1-sh）处理的小鼠（HFpEF-FoxO1-sh组）。