Sex Hormones in Pulmonary Arterial Hypertension

项目摘要 进行性致死性疾病--肺动脉高压(PAH)的最强危险因素 是女性(约3：1的女性：男性)。循环雌激素水平升高和雌激素水平增强 信令，是PAH的一个特征。我们的证据表明，活跃的雌激素信号会导致 男性和女性线粒体功能和能量底物利用的紊乱。然而，并非所有PAH 患者雌激素升高，我们不知道肺血管床对雌激素的亲和力。 在PAH患者的初步研究中，肺毛细血管前的雌二醇(E2)水平高于肺后毛细血管 床上，暗示着肺部摄取了E2。虽然这种跨肺(TP)梯度在 诊断时，TP梯度越负的患者血流动力学指标越严重。 雌二醇和其他雌激素，如16α-羟雌酮(16αOHE1)，通过典型的雌激素受体传递信号 (ESRα和ESRβ)。在多环芳烃转基因小鼠模型中，我们发现给予16αOHE1 PAH外显率显著增加，伴随着氧化应激、胰岛素抵抗和 线粒体功能障碍--我们和其他人在人类身上描述的所有特征。ESR信令还 PPARγ的表达通过减少Pgc1α的表达而降低。使用ESR的直接拮抗剂他莫昔芬，我们阻止了 转基因小鼠模型中的细胞代谢缺陷和肺血管表型。 他莫昔芬是一种耐受性良好的FDA批准的药物，也是治疗 对抗ESRS。在我们的模型系统中，我们使用 用雌激素示踪剂进行PET扫描。在人类身上，我们已经将这种方法应用于使用他莫昔芬治疗的患者 乳腺癌--提供了一个将对抗程度与治疗反应联系起来的机会。 我们的中心假设是，他莫昔芬的雌激素拮抗作用将是一种安全的治疗PAH的方法， 血液和肺中高度雌激素样物质的特征将识别PAH患者可能 有最大的好处。我们将以以下具体目标检验这一假说：(1)检验假说 使用他莫昔芬的雌激素拮抗剂在患有PAH的人类中是安全的，使用24周的概念验证安全性试验 将他莫昔芬(n=12)与安慰剂(n=12)进行比较。(2)确定帕金森病患者的表型特征 雌激素拮抗剂可能是一种有效的治疗方法--TP、E_2水平和肺ESR密度将 在诊断时确定，并与疾病严重程度相关。(3)检验雌激素的假说 信号通过以下途径驱动线粒体断裂和氧化损伤导致肺动脉高压 调节Pgc1α，以发现仅针对Pgc1有害影响的新治疗方法 多环芳烃中的雌激素。最终，我们的目标是证明直接ESR拮抗的安全性，这些患者最 可能受益，以及驱动雌激素信号促进PAH的细胞机制。这项建议 应该为使用精确医学方法进行雌激素拮抗的最终试验提供基础。

Project Summary The strongest established risk factor for the progressively fatal disease pulmonary arterial hypertension (PAH) is female sex (~3:1 ratio of females: males). Elevated circulating estrogen levels, and enhanced estrogen signaling, are a feature of PAH. Our evidence suggests that exuberant estrogen signaling causes a perturbation of mitochondrial function and energy substrate utilization in both sexes. However, not all PAH patients have elevated estrogens, and we don’t know the affinity of the pulmonary vascular bed for estrogens. In preliminary studies of PAH patients, estradiol (E2) levels were higher pre- than post-pulmonary capillary bed, suggestive of E2 uptake by the lungs. While this transpulmonary (TP) gradient was variable among patients, those with a more negative TP gradient had more severe hemodynamic metrics at diagnosis. E2 and other estrogens, such as 16α-hydroxyestrone (16αOHE1), signal via the canonical estrogen receptors (ESRα and ESRβ). In a transgenic mouse model of PAH, we found that administration of 16αOHE1 significantly increased PAH penetrance concomitant with features of oxidant stress, insulin resistance and mitochondrial dysfunction—all characteristics we and others have described in humans. ESR signaling also reduced PPARγ expression via a reduction in PGC1α. With tamoxifen, a direct ESR antagonist, we prevented the cellular metabolic defects and pulmonary vascular phenotype in our transgenic murine model system. Tamoxifen is a well-tolerated FDA-approved drug and the most commonly used hormonal therapy to antagonize ESRs. In our model system, we measured the degree of ESR antagonism by tamoxifen using a PET scan with estrogen tracer. In humans, we have applied this approach to those treated with tamoxifen for breast cancer—providing an opportunity to associate the degree of antagonism with therapeutic response. Our central hypothesis is that estrogen antagonism by tamoxifen will be a safe therapeutic approach for PAH, and that characteristics of a highly estrogenic profile in the blood and lungs will identify PAH patients likely to have the most benefit. We will test this hypothesis with these Specific Aims: (1) Test the hypothesis that estrogen antagonism with tamoxifen is safe in humans with PAH, using a 24 week proof-of-concept safety trial comparing tamoxifen (n=12) to placebo (n=12). (2) Determine the phenotype profile of subjects with PAH for whom estrogen antagonism may be an effective therapeutic approach—TP E2 levels and lung ESR density will be determined at diagnosis, and associated with disease severity. (3) Test the hypothesis that estrogen signaling drives mitochondrial fragmentation and oxidative damage leading to pulmonary hypertension via regulation of PGC1α, to uncover novel therapeutic approaches that target only the deleterious effects of estrogens in PAH. Ultimately, we aim to demonstrate the safety of direct ESR antagonism, those patients most likely to benefit, and the cellular mechanisms that drive estrogen signaling to promote PAH. This proposal should provide the foundation for a definitive trial of estrogen antagonism using a precision medicine approach.