Interventions Against the Molecular Etiology of BMPR2-induced PAH

描述(申请人提供)：特发性肺动脉高压(PAH)是一种致命性疾病，其特征是肺动脉重构、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BMPR2的突变。对BMPR2突变在转基因小鼠和细胞培养中的后果的研究，得到了文献中人类数据的证实，暗示了几种汇聚在一起促进PAH的途径。我们的初步数据表明，BMPR2突变可能通过直接调节LIMK而导致cofilin的去磷酸化。Cofilin的去磷酸化驱动糖皮质激素受体(GR)进入核内，在缺乏配体的情况下，它会导致异常信号和糖皮质激素不敏感。这自相矛盾地导致了一些GR依赖的激动剂效应，从而导致BMPR2突变人类和小鼠体重增加和高血糖，但导致无法通过其他人发出信号，使BMPR2突变携带者容易受到慢性炎症的影响，而糖皮质激素本应抑制慢性炎症。糖皮质激素激活和血糖升高可通过线粒体ROS的产生导致ROS的升高。我们的数据表明，BMPR2突变小鼠全肺脂质过氧化增加~2倍，肺血管过氧化脂质染色增加，ROS反应基因表达增加。此外，在培养的平滑肌细胞中检测到的所有BMPR2突变都会导致过氧化氢形成增加~2倍，RNA表达的变化提示ROS增加，并转向有氧糖酵解和谷氨酰胺分解。糖皮质激素受体信号的异常导致单核细胞的血管黏附和通透性增加，再加上ROS的增加，可能会导致单核细胞的募集和替代(M2)巨噬细胞的激活，从而导致微环境中肺血管的病理变化。为了综合这些数据，我们假设BMPR2突变引起的重要早期病因学变化是糖皮质激素受体信号异常和ROS增加，这导致单核细胞募集增加、M2巨噬细胞交替激活和肺血管重塑。毛细血管前动脉的这种慢性炎症状态通过丧失正常的血管反应性，增加血栓的形成，以及由BMPR2突变的血管细胞和巨噬细胞之间的相互作用信号引起的微环境变化而导致的增殖，导致PAH。这项研究将阐明BMPR2诱导的PAH的早期分子病因学，并提供关于BMP对炎症的调控的信息，对一系列疾病有意义。

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.