Cober Nicholas D, McCourt Emma, Godoy Rafael Soares, Deng Yupu, Schlosser Ken, Qamsari Elmira Safaie, Azami Jalil, Salehisiavashani Elham, Cook David P, Lemay Sarah-Eve, Klouda Timothy, Yuan Ke, Bonnet Sébastien, Stewart Duncan J
Ottawa Hospital Research Institute, Sinclair Centre for Regenerative Medicine Program, Ottawa, ON, Canada.
University of Ottawa, Faculty of Medicine, Department of Cellular and Molecular Medicine, Ottawa, ON, Canada.
Cardiovasc Res. 2025 Aug 28. doi: 10.1093/cvr/cvaf146.
Pulmonary arterial hypertension (PAH) is a lethal pulmonary vascular disease characterized by arteriolar pruning and occlusive vascular remodeling leading to increased pulmonary vascular resistance and eventually right heart failure. While endothelial cell (EC) injury and apoptosis are known triggers for this disease, the mechanisms by which they lead to complex arterial remodeling remain obscure.
We employed multiplexed single-cell RNA sequencing at multiple timepoints during the onset and progression of disease in a model of severe PAH to identify mechanisms involved in the development of occlusive arterial lesions.
Single cell transcriptional analysis resolved 44 global lung cell populations, with widespread early transcriptomic changes at 1 week affecting endothelial, stromal and immune cell populations. In particular, two EC clusters were greatly expanded during PAH development and were identified as being disease specific: a relatively dedifferentiated (dD) EC population that was enriched for Cd74 expression while exhibiting a loss of endothelial identity; and an activated arterial EC (aAEC) population that uniquely exhibited persistent differential gene expression throughout PAH development consistent with a growth regulated state. dDECs were primed to undergo endothelial-mesenchymal transition as evidenced by reduced activity of master EC transcription factors, Erg and Fli1, and further supported by RNA velocity analysis showing vectors leading to fibroblast clusters. Of note, aAECs exhibited high expression of Tm4sf1, a gene implicated in cancer cell growth, that was also expressed by a smooth muscle (SM)-like pericyte cluster, and were highly localized to regions of arterial remodeling in both the rat model and PAH patients, contributing to intimal occlusive lesions and SM-like pericytes forming bands of medial muscularization.
Together these findings implicate disease-specific vascular cells in PAH progression and suggest that TM4SF1 may be a novel therapeutic target for arterial remodeling.
Using single cell transcriptomic analysis in both human lung samples and a rat model of severe PAH we have identified disease-specific EC populations contributing to complex arterial remodeling, including growth-dysregulated, activated arterial ECs (aAECs) and dedifferentiated ECs (dDECs) that may be primed for endothelial to mesenchymal transition. In particular, aAECs exhibit high expression of a surface marker, TM4SF1, which is essential for their hyper-proliferative phenotype and represents a promising therapeutic target for RNA silencing approaches or as an antigen to guide immune-mediated ablation of this cancer-like EC population in PAH.
肺动脉高压（PAH）是一种致命的肺血管疾病，其特征是小动脉修剪和闭塞性血管重塑，导致肺血管阻力增加，最终引发右心衰竭。虽然已知内皮细胞（EC）损伤和凋亡是该疾病的触发因素，但它们导致复杂动脉重塑的机制仍不清楚。
我们在严重PAH模型疾病发生和发展的多个时间点采用多重单细胞RNA测序，以确定参与闭塞性动脉病变发展的机制。
单细胞转录分析解析出44种全肺细胞群，在第1周时广泛的早期转录组变化影响内皮细胞、基质细胞和免疫细胞群。特别是，两个EC簇在PAH发展过程中大幅扩增，并被确定为疾病特异性：一个相对去分化（dD）的EC群体，富含Cd74表达，同时表现出内皮细胞特征丧失；以及一个活化的动脉EC（aAEC）群体，在整个PAH发展过程中独特地表现出持续的差异基因表达，与生长调节状态一致。dDEC有向内皮-间充质转化的倾向，主要内皮细胞转录因子Erg和Fli1的活性降低证明了这一点，RNA速度分析进一步支持这一结论，该分析显示有指向成纤维细胞簇的向量。值得注意的是，aAEC高表达Tm4sf1，这是一个与癌细胞生长有关的基因，也由一个平滑肌（SM）样周细胞簇表达，并且在大鼠模型和PAH患者中都高度定位于动脉重塑区域，促成内膜闭塞性病变和SM样周细胞形成中层肌化带。
这些发现共同表明疾病特异性血管细胞参与PAH进展，并提示TM4SF1可能是动脉重塑的一个新治疗靶点。
通过在人类肺样本和严重PAH大鼠模型中使用单细胞转录组分析，我们确定了导致复杂动脉重塑的疾病特异性EC群体，包括生长失调的活化动脉EC（aAEC）和可能准备向内皮-间充质转化的去分化EC（dDEC）。特别是，aAEC高表达一种表面标志物TM4SF1，这对其过度增殖表型至关重要，是RNA沉默方法的一个有前景的治疗靶点，或作为一种抗原，用于指导免疫介导的消融PAH中这种癌症样EC群体。
