Novel mechanisms of obliterative pulmonary vascular remodeling and severe pulmonary arterial hypertension

肺动脉高压（PAH）是一种以肺动脉高压为特征的疾病， 阻力和闭塞性血管重塑，导致右心衰竭和过早死亡。 鉴于闭塞性血管重塑的潜在分子机制仍然是个谜， 目前的治疗没有针对基本的疾病修饰机制 导致发病率和死亡率略有改善。我们最近发现，Egln 1 Tie 2Cre 小鼠表现出前所未有的自发性重度PAH和闭塞性肺血管重塑 包括新生内膜形成和血管闭塞，如在特发性PAH（IPAH）患者中观察到的， 在IPAH患者的闭塞肺血管的EC中PHD 2表达减少。此续订 该建议基于我们的基本新观察，即1）巨噬细胞（Mφ）的遗传耗竭 MaFIA小鼠抑制闭塞性血管重塑并减弱Egln 1 Tie 2Cre/MaFIA中的PAH 2）单细胞RNA测序分析鉴定了一个新出现的PAH特异性 Egln 1 Tie 2Cre肺内的祖细胞Mφ; 3）Egln 1 Tie 2Cre血管病变中的CD 206 + Mφ积聚 肺组织表达大量血管生成因子，诱导PASMC增殖; Egln 1 Tie 2Cre小鼠中PI 3 K的GPCR依赖性p110γ亚型抑制这些因子的产生 和闭塞性血管重塑因此，我们推测，CD 206 + Mφ的显著积聚可能是由于 肺血管病变中来源于祖细胞Mφ的诱导闭塞性肺血管 通过EC-Mφ p110γ PI 3 K依赖性诱导PAH前体因子导致的重塑和重度PAH 互动目的1中的研究将确定CD 206 + Mφ亚群在 促进闭塞性肺血管重塑和重度PAH。我们将使用单细胞RNA 测序、谱系追踪和遗传消除方法，以确定CD 206+的因果作用 Mφ和pMφ介导闭塞性肺血管重构在目标2中，我们将描述 CD 206 + Mφ介导闭塞性肺血管重塑的分子基础及其机制探讨 靶向这些分子机制治疗PAH的翻译潜力。分子 将在SuHx PAH大鼠中验证小鼠模型中确定的机制。临床相关性将 用PASMCs和IPAH患者肺组织也可测定。我们希望拟议的研究 通过描绘分子和细胞机制， 闭塞性血管重塑，确定可药用靶点，并探索新的药理学 用于预防和治疗的可间接抑制/逆转血管重塑的药剂 PAH患者。

Pulmonary arterial hypertension (PAH) is characterized by progressive increase of pulmonary vascular resistance and obliterative vascular remodeling that causes right heart failure and premature death. Given the underlying molecular mechanisms of obliterative vascular remodeling remain enigmatic, current therapies have not targeted the fundamental disease modifying mechanisms and hence only resulted in a modest improvement in the morbidity and mortality. We have recently shown that Egln1Tie2Cre mice exhibit unprecedented spontaneous severe PAH and obliterative pulmonary vascular remodeling including neointima formation, and vascular occlusion as seen in patients with idiopathic PAH (IPAH) and PHD2 expression is diminished in ECs of occlusive pulmonary vessels of IPAH patients. This renewal proposal is based on our fundamental new observations that 1) genetic depletion of macrophages (Mφ) with the MaFIA mice inhibited obliterative vascular remodeling and attenuated PAH in Egln1Tie2Cre/MaFIA mice; 2) Single cell RNA sequencing analysis identified an emerging subpopulation of PAH-specific progenitor Mφ in Egln1Tie2Cre lungs; 3) CD206+ Mφ accumulated in the vascular lesions of Egln1Tie2Cre lungs expressed abundantly angiogenic factors inducing PASMC proliferation; 4) genetic disruption of the GPCR-dependent p110γ isoform of PI3K in Egln1Tie2Cre mice inhibited the production of these factors and obliterative vascular remodeling. Thus, we hypothesize that marked accumulation of CD206+ Mφ derived from progenitor Mφ in pulmonary vascular lesions induces obliterative pulmonary vascular remodeling and severe PAH through p110γPI3K-dependent induction of pro-PAH factors via EC-Mφ interaction. Studies in Aim 1 will determine the fundamental role of CD206+ Mφ subpopulation in promoting obliterative pulmonary vascular remodeling and severe PAH. We will employ single cell RNA sequencing, lineage tracing and genetic depletion approaches to determine the causal role of CD206+ Mφ and pMφ in mediating obliterative pulmonary vascular remodeling. In Aim 2, we will delineate the molecular basis of CD206+ Mφ in mediating obliterative pulmonary vascular remolding and explore the translational potential of targeting these molecular mechanisms for treatment of PAH. The molecular mechanisms identified in mouse models will be validated in SuHx PAH rats. The clinical relevance will also be determined with PASMCs and lung tissues of IPAH patients. We expect that the proposed studies have significant translational potential by delineating the molecular and cellular mechanisms of obliterative vascular remodeling, identifying druggable targets, and exploring novel pharmacological agents that can pharmacologically inhibit/reverse vascular remodeling for the prevention and treatment of PAH in patients.