Nicotinic Acetylcholine Receptors and RV Dysfunction in Pulmonary Hypertension

描述(由申请人提供)：肺动脉高压(PAH)是一种毁灭性的疾病，其特征是肺动脉压升高、肺血管阻力、血管重构和右室(RV)衰竭。右心衰竭是与PAH相关的死亡原因，并与适应性不良的右室重构和纤维化有关。心脏成纤维细胞(CF)通过增殖和基质生成在心脏重塑和纤维化中发挥关键作用。我们的初步数据表明，在衰竭的右室，非神经元性乙酰胆碱(ACh)合成途径和A7-烟碱型乙酰胆碱受体(NAChR)途径上调，并与促纤维化的血管紧张素II信号相互作用，因此可能是抑制心肌纤维化和功能障碍的重要机制和新靶点。然而，nAChRs在CF和与PH相关的心肌纤维化中的作用仍不清楚。我们假设，PAH患者CF中非神经性nAChR通路的激活会导致RV纤维化和衰竭。如果这是正确的，化学抑制 在PAH的临床前模型中，nAChR可改善右室功能。为了验证这一假说，我们提出了以下具体目标：具体目标1：我们将阐明Ach/nAChR在调节CFs增殖和胶原合成中的作用和潜在机制。我们将对Ach/nAChR在重度PH和RV功能障碍/纤维化的临床前模型中的表达进行表征，并确定与nAChR激活导致的CF增殖和胶原合成增加相关的信号机制。具体目标2：我们将确定nAChR在血管紧张素II信号转导中的作用，并阐明其相互作用的机制(S)。我们将使用原代分离的心脏成纤维细胞进行体外实验，以阐明nAChR和血管紧张素1型受体(AT1R)之间的协同信号机制。具体目标3：在PAH的临床前模型中，我们将确定抑制nAChR对RV纤维化以及功能和运动能力的影响。本研究的目的是用nAChR和AT1R拮抗剂治疗PH动物，以评价nAChR拮抗剂对RV纤维化和功能的影响。这些研究将描绘一条导致PAH患者右室纤维化增加的新的信号通路，并将为nAChR拮抗剂对PAH患者RV功能的疗效提供数据。这些实验的结果将为我们设计一项试验性翻译研究，评估临床上可用的nAChR拮抗剂在PAH环境下RV功能障碍患者中的有效性和安全性。

DESCRIPTION (provided by applicant): Pulmonary Arterial Hypertension (PAH) is a devastating disease characterized by increased pulmonary artery pressures, pulmonary vascular resistance, vascular remodeling, and right ventricular (RV) failure. Right ventricular failure is the cause of mortality associated with PAH, and is associated with maladaptive RV remodeling and fibrosis. The cardiac fibroblasts (CF) play a key role in cardiac remodeling and fibrosis through proliferation and matrix generation. Our preliminary data suggests that non-neuronal acetylcholine (ACh) synthetic pathway and a7-nicotinic acetylcholine receptor (nAChR) pathway in the failing right ventricle is upregulated, interacts with pro-fibrotic angiotensin II signaling, and thus may be an important mechanism and a novel target to inhibit ventricular fibrosis and dysfunction. However, the role of nAChRs in CF and in myocardial fibrosis associated with PH remains unknown. We hypothesize that activation of a non-neuronal nAChR pathway in the CF in PAH causes RV fibrosis and failure. If this is correct, chemical inhibition of nAChR should result in improvement of RV function in a preclinical model of PAH. In order to test this hypothesis we propose the following Specific Aims: Specific Aim 1: We will elucidate the role and underlying mechanism of Ach/nAChR in mediating CF proliferation and collagen synthesis. We will characterize the Ach/nAChR expression in preclinical model of severe PH and RV dysfunction/fibrosis and determine the signaling mechanism associated with increased CF proliferation and collagen synthesis in response to nAChR activation. Specific Aim 2: We will determine the role of nAChR in angiotensin II signaling resulting in CF proliferation and collagen synthesis and elucidate the mechanism(s) of interaction. We will use primary isolated cardiac fibroblasts in in vitro assays to elucidate the cooperative signaling mechanism between the nAChR and angiotensin type 1 receptor (AT1R). Specific Aim 3: We will determine the effect of inhibiting nAChR on RV fibrosis and function and exercise capacity in a preclinical model of PAH. The approach used in this aim is to treat animals with PH with nAChR and AT1R antagonists to evaluate the efficacy of nAChR antagonism on RV fibrosis and function. These studies will delineate a novel signaling pathways leading to the increased fibrosis observed in the RV in PAH and will provide data on the efficacy of nAChR antagonism on RV function in PAH. The results from these experiments will inform us in designing a pilot translational study evaluating the efficacy and safety of use of clinically available nAChR antagonists in patients with RV dysfunction in settings of PAH.