Mutation Specific Therapies in Patients with HPAH

描述：肺动脉高压（PAH）患者的现有治疗方法均不能降低死亡率或逆转已建立的肺血管病变。然而，遗传性PAH （HPAH）患者遗传BMP 2型受体基因BMPR2的杂合子常染色体显性突变，这表明纠正BMP信号缺陷的策略可能为该疾病提供新的治疗途径。已经鉴定出超过300种HPAH BMPR2突变，每种突变对BMPR2功能都有潜在的不同影响。然而，这些可以分为3个功能群：i) i类：mRNA通过无义介导的RNA衰变（NMD+）降解；ii类：受体表达（NMD-），但错误折叠，不在细胞表面表达；iii类：受体表达（NMD-），定位正确，但无功能。这种分类很重要，因为NMD抑制剂可以恢复I类突变的BMP信号，而纠正蛋白质折叠的化合物可以恢复II类而不是III类BMPR2突变的信号。重要的是，NMD抑制剂和蛋白质折叠剂在其他遗传性疾病（如囊性纤维化）患者中都是有效、安全的，并且正在评估中。这些研究将确定突变特异性疗法是否也能纠正HPAH患者的BMPR2表达和功能。作为建立这种模式在HPAH中的适用性的第一步，我们将使用HPAH患者来源的内皮细胞（ECs）。理想情况下，我们将使用肺动脉高压患者的肺内皮细胞（PECs）进行所有这些研究。然而，这些细胞供应有限，在培养中寿命短。因此，我们将使用从PHBI Cell Core中获得的HPAH PECs来补充初始研究，并使用从已知BMPR2突变的HPAH患者外周血中获得的晚期生长内皮祖细胞（LEPCs）进行研究。其中一些单元格已经生成，并将由合作者提供。然而，我们在范德比尔特有一个独特的位置来补充这些研究，使用来自美国最大的BMPR2突变的HPAH患者队列的样本。通过这种方式，我们将能够研究一组HPAH患者衍生的ECs，其中包括来自所有3种功能突变类别的BMPR2突变的代表性分布。因此，我们将利用这些细胞确定BMPR2突变的性质和功能分类，并评估NMD途径抑制剂和蛋白质折叠剂对这些HPAH患者BMPR2表达和功能的影响。因此，这些研究将确定相关细胞类型中BMPR2突变亚型和对NMD途径或蛋白质折叠治疗的反应性，并将为分类治疗可靶向的BMPR2突变和更广泛地评估hah中NMD抑制剂和/或蛋白质折叠剂奠定基础。

DESCRIPTION: None of the established therapies for patients with Pulmonary Arterial Hypertension (PAH) reduce mortality or reverse established pulmonary vasculopathy. However, patients with Hereditary PAH (HPAH) inherit heterozygous, autosomal dominant mutations in the BMP type 2 receptor gene, BMPR2, suggesting that strategies to correct BMP signaling defects could present a new therapeutic approach for this disease. Over 300 HPAH BMPR2 mutations have been identified, each with potentially different effects on BMPR2 function. However, these can be classified into 3 functional groups: i) Class I: mRNA is degraded by non-sense mediated RNA decay, (NMD+); ii) Class II: receptors are expressed (NMD-), but mis-folded and are not expressed on the cell surface; and iii) Class III: receptors are expressed (NMD-) and correctly localized but non functional. This classification is important since NMD inhibitors may restore BMP signaling with Class I mutations, while compounds that correct protein folding may restore signaling with Class II but not Class III BMPR2 mutations. Importantly, both NMD inhibitors and protein folding agents, are effective, safe and being evaluated in patients with other heritable diseases, such as cystic fibrosis. These studies will determine whether mutation-specific therapies also correct BMPR2 expression and function in HPAH patients. As an initial step to establish the applicability of this paradigm in HPAH, we will use HPAH patient-derived endothelial cells (ECs). Ideally we would use pulmonary endothelial cells (PECs) from HPAH patients for all of these studies. However these cells are in limited supply and have short lifespan in culture. For this reason we will supplement initial studies using HPAH PECs obtained from the PHBI Cell Core, with studies using late outgrowth endothelial progenitor cells (LEPCs) obtained from peripheral blood of HPAH patients with known BMPR2 mutations. Some of these cells have been generated and will be provided by a collaborator. However, we are in a unique position at Vanderbilt to supplement these studies using samples derived from the largest cohort of HPAH patients with defined BMPR2 mutations in the USA. In this way we will be able to study a cohort of HPAH patient-derived ECs that include a representative distribution of BMPR2 mutations from all 3 functional classes of mutation. Using these cells therefore, we will determine the nature and functional classification of BMPR2 mutations, and evaluate the effects of NMD pathway inhibitors and protein folding agents on BMPR2 expression and function in these HPAH patients. These studies therefore will identify BMPR2 mutant sub-types and responsiveness to NMD pathway or protein folding therapy in a relevant cell type, and will form the foundation to classify therapeutically targetable BMPR2 mutations and more extensive evaluation of NMD inhibitors and/or protein folding agents in HPAH. PUBLIC HEALTH RELEVANCE: Pulmonary Arterial Hypertension is an invariably fatal disease for which there is no curative treatment. A major challenge for the scientific community therefore is to develop therapeutic approaches to prevent the progression of pulmonary vascular disease that develops in these patients. Our studies will provide important insight into a common pathway that regulates this process and identify approaches to interfere with this pathway and prevent the development of irreversible pulmonary vascular disease in these patients. (End of Abstract)