Interventions Against the Molecular Etiology of BMPR2-induced PAH

描述（由申请方提供）：特发性肺动脉高压（PAH）是一种致死性疾病，其特征为肺动脉重塑、RVSP增加、慢性炎症和血管收缩。PAH的家族性形式通常是由于骨形态发生蛋白2型受体BMPR 2的突变。在转基因小鼠和细胞培养物中检查BMPR 2突变的后果，并通过文献中的人类数据证实，暗示了几种会聚促进PAH的途径。我们的初步数据表明，BMPR 2突变导致cofilin的去磷酸化，可能是通过直接调节LIMK。cofilin的去磷酸化驱动糖皮质激素受体（GR）进入细胞核，在缺乏配体的情况下，它导致异常信号传导和糖皮质激素不敏感性。这矛盾地导致一些GR依赖性激动剂效应，因此BMPR 2突变体人类和小鼠的体重增加和高血糖，但导致无法通过其他人发出信号，使BMPR 2突变携带者容易受到慢性炎症的影响，而糖皮质激素旨在抑制这种炎症。糖皮质激素激活和血糖升高可通过线粒体ROS产生导致活性氧（ROS）升高。我们的数据表明，BMPR 2突变小鼠在整个肺中的脂质过氧化增加了约2倍，肺血管过氧化脂质染色增加，ROS反应基因的表达增加。此外，在培养的平滑肌细胞中测试的所有BMPR 2突变导致过氧化物形成增加约2倍，并且RNA表达变化表明ROS增加以及向有氧糖酵解和β-氨基丁酸解的转变。异常糖皮质激素受体信号传导导致单核细胞的血管粘附性和渗透性增加，并且这与增加的ROS组合可驱动单核细胞的募集和替代性（M2）巨噬细胞活化，这可驱动其微环境中的肺脉管系统的病理变化。为了综合这些数据，我们假设BMPR 2突变引起的重要早期病因学变化是糖皮质激素受体信号传导异常和ROS增加，这驱动单核细胞募集增加，替代（M2）巨噬细胞活化和肺血管重塑。毛细血管前肺动脉中的这种慢性炎症状态通过正常血管反应性丧失、血栓形成增加以及由BMPR 2突变血管细胞和巨噬细胞之间的相互作用信号传导引起的微环境变化引起的增殖倾向而导致PAH。这项研究将阐明BMPR 2诱导的PAH的早期分子病因学，以及提供有关BMP调节炎症的信息，并对许多疾病产生影响。 公共卫生相关性：该项目测试了BMPR 2突变通过直接引起糖皮质激素受体功能障碍导致活性氧增加和循环细胞向肺部募集而易患肺动脉高压的假设。将使用细胞培养和转基因小鼠模型实验的组合来检验这一假设。

DESCRIPTION (provided by applicant): Idiopathic pulmonary arterial hypertension (PAH) is a lethal disorder characterized by pulmonary arterial remodeling, increased RVSP, chronic inflammation and vasoconstriction. The familial form of PAH is usually due to mutations in the type 2 receptor for Bone Morphogenic Protein, BMPR2. Examination of the consequences of BMPR2 mutation in transgenic mice and in cell culture, corroborated by human data from the literature, implicates several pathways that converge to promote PAH. Our preliminary data indicate that BMPR2 mutation causes dephosphorylation of cofilin, likely through direct regulation of LIMK. Dephosphorylation of cofilin drives the glucocorticoid receptor (GR) into the nucleus, where in the absence of ligand it causes both abnormal signaling and glucocorticoid insensitivity. This paradoxically causes some GR-dependent agonist effects, thus weight gain and high blood glucose in BMPR2 mutant humans and mice, but causes inability to signal through others, leaving BMPR2 mutation carriers susceptible to the chronic inflammation, which glucocorticoids are meant to suppress. Glucocorticoid activation and elevated blood glucose can lead to elevated reactive oxygen species (ROS) through mitochondrial ROS production. Our data indicate that BMPR2 mutant mice have a ~2x increase in lipid peroxidation in whole lung, increased pulmonary vascular peroxidized lipid staining, and increased expression of ROS-responsive genes. Also, all BMPR2 mutations tested in cultured smooth muscle cells lead to a ~2x increase in peroxide formation, and RNA expression changes suggestive of increased ROS and a shift to aerobic glycolysis and glutaminolysis. Aberrant glucocorticoid receptor signaling leads to increased vascular adhesion and permeability by monocytes, and this in combination with increased ROS may drive recruitment of monocytes and alternative (M2) macrophage activation, which can drive pathologic changes to the pulmonary vasculature in their microenvironment. To synthesize these data, we hypothesize that the important early etiologic changes caused by BMPR2 mutation are aberrant glucocorticoid receptor signaling and increased ROS, which drive increased recruitment of monocytes, alternative (M2) macrophage activation, and remodeling of the pulmonary vasculature. This chronic inflammatory state in precapillary pulmonary arteries leads to PAH through loss of normal vasoreactivity, increased formation of thrombi, and a predisposition to proliferation caused by microenvironmental changes brought about by interactive signaling between BMPR2 mutant vascular cells and macrophages. This study will clarify the early molecular etiology of BMPR2-induced PAH, as well as providing information about BMP regulation of inflammation with implications to a host of diseases. PUBLIC HEALTH RELEVANCE: This project tests the hypothesis that BMPR2 mutation predisposes to pulmonary hypertension by directly causing glucocorticoid receptor dysfunction leading to increased reactive oxygen species and recruitment of circulating cells to the lungs. A combination of cell culture and transgenic mouse model experiments will be used to test this hypothesis.