Right Heart Function in Health and Chronic Disease

右室衰竭(RVF)是严重的临床问题，预后差。然而，具体的治疗 RVF的选择非常有限。最近的研究表明，强大的心脏保护作用是由 α1-肾上腺素能受体，特别是α1A亚型(α1A-AR)。在目前的资助期内，我们发现 慢性刺激α1A-ARs对两种RVF模型小鼠的RV功能有显著的有益影响 肺纤维化或肺动脉收缩(PAC)所致。该更新项目将确定 α1A-AR介导的RVF逆转机制及慢性心绞痛的疗效观察 α1A-AR的刺激延伸到对人体心肌制剂的有益影响。 这一更新项目将以本供资期间取得的以下初步成果为基础： ·在PAC诱导的右室颤动模型中，用高度特异的α1A慢性治疗可逆转右室颤动。 AR激动剂(A61603)，低剂量，不会升高血压。 ·A61603治疗的有益效果包括促进生存的激酶ERK信号转导增加， 增加bcl2(保护线粒体的抗凋亡因子)，增加心肌ATP水平， 以及降低活性氧(ROS)水平，这表明对线粒体有保护作用。 ·RVF与一种新的细胞内基质亚型丰度增加有关- 金属蛋白酶-2：N-末端截短的基质金属蛋白酶-2(NTT-MMP-2)。报道了NTT-MMP2的表达 由ROS诱导，导致线粒体功能障碍，ATP生成减少，并进一步 ROS一代。我们的初步结果显示，A61603治疗降低了NTT-MMP-2的表达 线粒体，并增加心肌的三磷酸腺苷，表明线粒体功能得到改善。 在RVF的PAC模型中，慢性A61603治疗降低了ROS，减少了ROS介导的 肌丝蛋白的修饰和肌丝力的增加。初步研究 使用计算模型表明，增加的肌丝力量发展是一个关键因素 经A61603治疗后右室功能改善。 ·我们最近报道，α1A-AR在人RV心肌中介导了强大的变力反应 研究表明，α1A-AR-ERK1信号通路存在于衰竭的人体心肌中。 这些发现表明，α1A-AR在衰竭的人RV中存在并发挥功能，可能是一种 旨在诱导RVF患者心脏保护作用的治疗靶点。 假设1.对于衰竭的RV，慢性A61603治疗挽救了线粒体的生物能量功能， 导致ATP水平升高，ROS生成减少，收缩增加。 假设2：线粒体生物能功能的恢复是通过降低NTT-MMP2水平来实现的。 假设3.慢性α1A-AR刺激对人体心肌准备是有益的。 目的1.确定慢性A61603治疗RVF是否能挽救线粒体的生物能功能； 导致ATP水平升高，ROS水平降低，肌丝收缩增加，RVF挽救。 目的2.确定线粒体功能的恢复是否通过降低NTT-MMP2的水平来实现。我们 将确定慢性A61603治疗RVF是否会降低NTT-MMP-2水平，从而挽救 线粒体功能。我们将确定抑制NTT-MMP-2是否实验上拯救了线粒体 功能。 目的3.确定长期服用A61603是否对人体心肌有益 准备工作。作为对人类翻译的原则证明，我们将确定慢性A61603治疗是否 在两种心肌制剂中具有有益作用：含有诱导剂的工程化人类心脏组织 多能干细胞(IPSC)来源的心肌细胞和RVF患者培养的RV小梁。

Right ventricular failure (RVF) is a serious clinical problem with a poor prognosis. However, specific treatment options for RVF are very limited. Recent studies suggest that powerful cardioprotective effects are mediated by α1-adrenergic receptors, in particular the α1A-subtype (α1A-AR). In the current funding period, we found that chronic stimulation of α1A-ARs had major beneficial effects on RV function in two mouse models of RVF induced by pulmonary fibrosis or pulmonary artery constriction (PAC). This renewal project will identify the mechanisms involved in α1A-AR-mediated reversal of RVF and investigate if the beneficial effects of chronic α1A-AR stimulation extend to beneficial effects in human cardiac muscle preparations. This renewal project will build on the following preliminary results from the current funding period: · In a model of RVF induced by PAC, RVF was reversed by chronic treatment with a highly specific α1A- AR agonist (A61603), at a low dose that did not raise blood pressure. · The beneficial effect of A61603 treatment involved increased signaling by the pro-survival kinase ERK, increased BCL-2 (anti-apoptosis factor that protects mitochondria), increased myocardial ATP levels, and decreased levels of reactive oxygen species (ROS), suggesting protective effects on mitochondria. · RVF was associated with increased abundance of a novel intracellular isoform of matrix- metalloproteinase-2: N-terminal truncated MMP-2 (NTT-MMP-2). NTT-MMP-2 expression was reported to be induced by ROS and result in mitochondrial dysfunction, decreased ATP production and further ROS generation. Our preliminary results show that A61603 treatment reduces NTT-MMP-2 in mitochondria, and increased myocardial ATP, suggesting improved mitochondrial function. · In the PAC model of RVF, chronic A61603 treatment decreased ROS, decreased ROS-mediated modification of myofilament proteins and increased myofilament force development. Preliminary studies using computational modeling suggest that increased myofilament force development is a critical factor in the improved RV function resulting from A61603 treatment. · We recently reported that the α1A-AR mediates a robust inotropic response in human RV myocardium from heart failure patients and that α1A-AR-ERK signaling is present in failing human myocardium. These findings suggest that the α1A-AR is present and functional in failing human RV and might be a therapeutic target to induce cardioprotective effects in patients with RVF. Hypothesis 1. For failing RV, chronic A61603 treatment rescues mitochondrial bioenergetic function, resulting in increased ATP levels, reduced ROS generation and increased contraction. Hypothesis 2. Rescue of mitochondrial bioenergetic function is mediated by reduced NTT-MMP-2 levels. Hypothesis 3. Chronic α1A-AR stimulation is beneficial in human cardiac muscle preparations. Aim 1. Determine if chronic A61603 treatment of RVF rescues mitochondrial bioenergetic function; leading to increased ATP levels, reduced ROS levels, increased myofilament contraction and rescue of RVF. Aim 2. Determine if rescue of mitochondrial function is mediated by reduced levels of NTT-MMP-2. We will determine if chronic A61603 treatment of RVF reduces levels of NTT-MMP-2 and thereby rescues mitochondrial function. We will determine if inhibiting NTT-MMP-2 experimentally rescues mitochondrial function. Aim 3. Determine if chronic treatment with A61603 has beneficial effects in human cardiac muscle preparations. As proof of principle for translation to humans, we will determine if chronic A61603 treatment has beneficial effects in two cardiac muscle preparations: engineered human heart tissue containing induced pluripotent stem cell (iPSC)-derived cardiomyocytes, and cultured RV trabeculae from RVF patients.