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

肺动脉高压(PAH)的特征是肺血管进行性增加。 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是个谜， 目前的治疗方法没有针对基本的疾病改善机制，因此仅 导致发病率和死亡率略有改善。我们最近证明了Egln1Tie2Cre 小鼠表现出前所未有的自发性重度PAH和闭塞性肺血管重构 包括特发性肺动脉高压(IPAH)患者的新生内膜形成和血管闭塞。 IPAH患者闭塞型肺血管内皮细胞PHD2表达降低。此次续订 提出的建议是基于我们基本的新观察结果，即1)巨噬细胞(Mφ)的遗传耗竭 用MAFIA抑制Egln1Tie2Cre/MAFIA小鼠闭塞性血管重塑和PAH 小鼠；2)单细胞RNA测序分析鉴定了一个新出现的PAH特异性亚群 Egln1Tie2Cre肺Mφ祖细胞；3)Egln1Tie2Cre血管病变中聚集的CD206+Mφ 肺组织表达丰富的血管生成因子诱导PASMC增殖；4)基因干扰 Egln1Tie2Cre小鼠依赖于gpr的PI3K的p110γ亚型抑制这些因子的产生 以及闭塞性血管重塑。因此，我们假设CD206+Mφ的显著积累 祖细胞M-φ在肺血管病变中诱导闭塞肺血管 P110γ依赖的PI3K通过EC-Mφ诱导促PAH因子的重塑和严重的PAH 互动。目标1中的研究将确定CD206+Mφ亚群在 促进闭塞性肺血管重塑和严重的PAH。我们将使用单细胞RNA 用测序、谱系追踪和基因耗竭等方法确定CD206+的致病作用 M-φ和PM-φ在介导闭塞性肺血管重塑中的作用在目标2中，我们将描述 CD206+Mφ介导闭塞性肺血管重塑的分子基础及机制探讨 靶向这些分子机制治疗PAH的翻译潜力。分子 在小鼠模型中发现的机制将在SuHx PAH大鼠身上得到验证。临床相关性将会是 也可用IPAH患者的PASMC和肺组织进行检测。我们期望拟议的研究 通过描述分子和细胞机制，具有显著的翻译潜力 阻断血管重塑，确定可用药靶点，探索新的药理作用 可药理抑制/逆转血管重塑的防治药物 患者体内多环芳烃的含量。

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.