Defining cardiac functional recovery in end-stage heart failure at single cell resolution

Recovery of cardiac function is the ultimate goal of heart failure therapy yet is infrequently observed and remains poorly understood. Here we characterize the cellular landscape and predictors of cardiac recovery by performing single nucleus RNA-sequencing (snRNA-seq) from 40 heart failure patients who recovered LV systolic function following left ventricular assist device (LVAD) implantation and patients who did not recover and non-diseased donors. We identify cell type specific transcriptional signatures of recovery in all cell types, most prominently in macrophages and fibroblasts. Pro-inflammatory macrophages and inflammatory signalling in fibroblasts were negative predictors of recovery, while downregulation of RUNX1 transcriptional activity in macrophages and fibroblasts was associated with recovery. In silico perturbation of RUNX1 in macrophages and fibroblasts recapitulated the transcriptional state of recovery. In a mouse model of cardiac recovery mediated by BRD4 inhibition, we observed a decrease in macrophage and fibroblast Runx1 expression, diminished chromatin accessibility within a Runx1 intronic peak, and acquisition of human recovery signatures. These findings suggest that cardiac recovery is a unique biological state and identify RUNX1 as a possible therapeutic target to facilitate cardiac recovery. snRNA-seq in donor and HF (pre-post LVAD split by responders and non-responders)

心脏功能恢复是心力衰竭治疗的终极目标，但该现象罕有发生，且其背后机制至今仍未被充分阐明。
本研究通过对40例心力衰竭患者开展单细胞核RNA测序（single nucleus RNA-sequencing, snRNA-seq）：其中部分患者在接受左心室辅助装置（left ventricular assist device, LVAD）植入后左心室收缩功能得以恢复，其余患者未出现功能恢复，同时纳入非疾病供者作为对照，以此解析心脏恢复的细胞图谱及其预测因子。
本研究在所有细胞类型中均鉴定出与恢复相关的细胞类型特异性转录特征，其中以巨噬细胞和成纤维细胞最为显著。
促炎巨噬细胞与成纤维细胞内的炎症信号通路均为心脏恢复的负向预测因子；而巨噬细胞与成纤维细胞内runt相关转录因子1（RUNX1）的转录活性下调则与心脏恢复呈正相关。
在巨噬细胞与成纤维细胞中对RUNX1进行计算机模拟扰动，可重现心脏恢复相关的转录状态。
在溴结构域蛋白4（BRD4）抑制介导的心脏恢复小鼠模型中，我们观察到巨噬细胞与成纤维细胞内Runx1表达水平下调，Runx1内含子区域染色质可及性峰的信号强度减弱，同时获得了人类心脏恢复相关的转录特征。
上述研究结果表明，心脏功能恢复是一种独特的生物学状态，并鉴定出RUNX1可作为促进心脏恢复的潜在治疗靶点。
本研究的snRNA-seq数据来自非疾病供者、心力衰竭患者（按LVAD植入前后分组，并进一步分为功能恢复应答者与未恢复非应答者亚组）