Endothelial Injury, BMPR2 Dysfunction and Macrophage Activation Cause EndMT and PAH

大量的知识表明，炎症和免疫失调在 肺动脉高压（PAH）的发展现在已经导致了第一次免疫治疗试验， 这个条件。然而，这种方法的成功要求我们确定异常的 对肺动脉内皮细胞（PAEC）损伤的免疫/炎症反应发展并促成 闭塞性动脉病的演变，其特征在于细胞凋亡、细胞凋亡抵抗和 内皮间质转化（EndMT）。同样重要的是，将这些特征与患者的功能障碍联系起来， PAH的关键遗传修饰剂，骨形态发生蛋白受体（BMPR）2。该提案带来了独特的 重点关注两种关键的先天免疫介质，它们在血管周围巨噬细胞（MCs）中高度表达， PAH患者，对肺血管系统进行协调攻击：白三烯，LTB 4， 以及内源性逆转录病毒HERV-K，其是日益被认识到的自身免疫损伤的原因。整体 有一种假设是，BMPR 2信号传导功能障碍的PAEC受损后，募集并激活了扩增LTB 4的MMPs 和HERV-K;这些免疫因子协同工作，通过以下方式维持炎症并促进重度PAH： 凋亡和EndMT。目的1评估LTB 4如何由受损的PAEC自主产生， 当BMPR 2激活MMPs，刺激LTB 4的进一步生物合成，导致PAEC凋亡和EndMT， 信号被破坏。这一目的还探讨了内源性HERV-K的扩增如何进一步刺激 LTB 4生物合成以及LTB 4如何诱导单核细胞中HERV-K表达。单细胞RNA测序将 基因型PAEC群体注定响应LTB 4而凋亡或EndMT，以描绘基因 标志着向凋亡抗性和EndMT转变的表达变化。目标2评估是否 来自PAH患者的PAEC，包括BMPR 2功能降低的PAEC，分泌响应于 氧化剂或炎性损伤，其放大单核细胞中HERV-K的表达。这一目标还考虑到 单核细胞中BMPR 2的缺失对HERV-K扩增以及转录和 翻译机制参与了这一过程。还需要研究的是分泌的HERV-K是否 产品dUTR促进具有BMPR 2功能障碍的PAEC中的EndMT， 转型单细胞RNA测序分析将阐明HERV-K诱导的基因表达变化， PAEC向EndMT的演变。目的3研究BMPR 2缺陷动物发育的脆弱性 严重PH和EndMT使用在命运定位EC中具有BMPR 2缺失的小鼠，和新的转基因大鼠PH BMPR 2单倍不足模型。用气管内滴注Ad-5LO处理动物， 产生高LTB 4水平或静脉内给予重组HERV-K dUTR。逆转EndMT的策略 将检测与PAH中致死性闭塞性血管病变具有转化相关性的重度PH 患者

A considerable body of knowledge indicating that inflammation and immune dysregulation play a pivotal role in the development of pulmonary arterial hypertension (PAH) have now led to the first immunotherapy trials for this condition. However the success of this approach requires that we determine how the aberrant immune/inflammatory response to pulmonary artery endothelial cell (PAEC) injury develops and contributes to the evolution of the occlusive arteriopathy, that is characterized by apoptosis, apoptosis resistance and endothelial mesenchymal transition (EndMT). It is also important to relate these features to dysfunction of a key genetic modifier of PAH, bone morphogenetic protein receptor (BMPR)2. This proposal brings unique focus to two key innate immune mediators that are highly expressed in perivascular macrophages (MØs) from patients with PAH and that mount a coordinated attack on the pulmonary vasculature: the leukotriene, LTB4, and the endogenous retrovirus, HERV-K, an increasingly recognized cause of autoimmune injury. The overall hypothesis is injured PAECs with dysfunctional BMPR2 signaling recruit and activate MØs that amplify LTB4 and HERV-K; these immune factors work in concert to sustain inflammation and promote severe PAH by apoptosis and EndMT. Aim 1 evaluates how LTB4 may be autonomously produced by injured PAECs, which in turn activate MØs to stimulate further LTB4 biosynthesis to cause PAEC apoptosis and EndMT when BMPR2 signaling is impaired. This aim also explores how amplification of endogenous HERV-K may further stimulate LTB4 biosynthesis and how LTB4 can induce HERV-K expression in monocytes. Single cell RNA Seq will genotype PAEC populations that are fated for apoptosis or EndMT in response to LTB4 to delineate gene expression changes that mark the transition to apoptosis resistance and EndMT. Aim 2 evaluates whether PAECs from PAH patients including those with reduced BMPR2 function, secrete factors in response to oxidant or inflammatory injury, that amplify HERV-K expression in monocytes. This aim also considers the additive effects of loss of BMPR2 in monocytes, on amplification of HERV-K and whether transcriptional and translational mechanisms are involved in this process. Also to be investigated is whether the secreted HERV-K product, dUTPase, promotes EndMT in PAEC with BMPR2 dysfunction that are primed to undergo transformation. Single cell RNA Seq analyses will elucidate gene expression changes induced by HERV-K in the PAEC evolution to EndMT. Aim 3 investigates the vulnerability of BMPR2-deficient animals to develop severe PH and EndMT using a mouse with loss of BMPR2 in fate mapped EC, and a new transgenic rat PH model with BMPR2 haploinsufficiency. The animals are treated with endotracheal instillation of Ad-5LO to generate high LTB4 levels or recombinant HERV-K dUTPase given intravenously. Strategies to reverse EndMT and severe PH will be tested that have translational relevance to the fatal obliterative vasculopathy in PAH patients.