Role of Skeletal Muscle in Pulmonary Vascular Remodeling

肺动脉高压伴射血分数保留性心力衰竭（PH-HFpEF）是最常见的肺动脉高压。 全球PH的常见原因，影响美国约150万心力衰竭患者 只有国家。目前，还没有确定具体的治疗方法，主要是由于主要途径 参与PH-HFpEF调控的基因仍不清楚。我们最近发现 PH-HFpEF调节sirtuin-3（SIRT 3）在骨骼肌中主要减少的证据。在 事实上，我们新的初步数据表明，骨骼肌中SIRT 3的缺失导致骨骼肌中的SIRT 3水平急剧下降。 肺血管树，伴随着增加的血管重塑和较高的肺 这表明骨骼肌SIRT 3在肺血管重塑和PH-HFpEF中的关键作用。 基于全球质谱比较分泌组分析，我们的新数据表明， 骨骼肌SIRT 3缺陷驱动赖氨酰氧化酶同源物2（LOXL 2）的分泌， 已知可促进胶原蛋白交联，以及骨形态发生蛋白（BMP）gremlin-1（Grem 1） 拮抗剂已知诱导过度增殖。我们假设骨骼肌SIRT 3缺乏 通过分泌LOXL 2和Grem 1促进PH-HFpEF，LOXL 2和Grem 1作为内分泌信号分子诱导 肺血管重构我们计划使用一些尖端的方法，其中包括使用 离体精确切割肺切片和体内骨骼肌特异性KO小鼠，以解决突出的 问题. 具体目的：1）确定骨骼肌SIRT 3缺陷是否与代谢综合征有关 有助于PH-HFpEF的发展。使用野生型和骨骼肌特异性Sirt 3 KO小鼠， 或没有诱导PH-HFpEF表型的高脂喂养（HFD），我们将表征 骨骼肌SIRT 3缺乏对PH-HFpEF的发展有重要影响。结果可能揭示了系统性的 骨骼肌SIRT 3缺乏对远端肺血管重构和PH- HFpEF。2，3）为了确定LOXL 2和Grem 1是否是由SIRT 3 - 1产生的内分泌信号分子， 缺乏骨骼肌细胞诱导肺血管重塑。来自SIRT 3的条件培养基 有或没有LOXL 2和Grem 1抑制的缺陷型骨骼肌细胞将应用于离体精密度- 切割肺切片，以测试SIRT 3缺陷与随后的LOXL 2和Grem 1分泌增加是否促进了 通过胶原蛋白交联增加和肺动脉过度增生进行血管重塑 内皮细胞和平滑肌细胞。骨骼肌分泌的LOXL 2和Grem 1在肺动脉高压中的作用 血管重塑和PH-HFpEF将使用骨骼肌特异性Loxl 2和Grem 1在体内测定 HFD KO小鼠。LOXL 2和Grem 1靶向治疗也将在我们最近开发的大鼠中进行评估。 PH-HFpEF模型。 我们的目标是牢固地建立PH-HFpEF中骨骼肌-肺血管系统串扰的新范例 通过内分泌信号。我们希望，成功执行拟议的研究计划将提供 PH-HFpEF的新机制的理解和鉴定骨骼肌SIRT 3，沿着其下游 LOXL 2和Grem 1是PH-HFpEF诊断和治疗的潜在分子靶点。此外，委员会认为， 我们的研究将为代谢综合征、衰老和缺乏运动如何影响 肺血管健康

Pulmonary hypertension associated with heart failure with preserved ejection fraction (PH-HFpEF) is the most common cause of PH worldwide, affecting approximately 1.5 million patients with heart failure in the United States alone. At present, no specific therapy has been identified mainly due to the fact that major pathways involved in the regulation of PH-HFpEF are still not well understood. We have recently found convincing evidence that PH-HFpEF-regulating sirtuin-3 (SIRT3) is predominantly decreased in the skeletal muscle. In fact, our new preliminary data show that the absence of SIRT3 in skeletal muscle leads to a drastic reduction of the pulmonary vascular tree, accompanied by increased vascular remodeling and higher pulmonary pressures, indicating a critical role of skeletal muscle SIRT3 in pulmonary vascular remodeling and PH-HFpEF. Based on a global mass spectrometry-based comparative secretome analysis, our new data indicate that skeletal muscle SIRT3 deficiency drives the secretion of lysyl oxidase homolog 2 (LOXL2), a matrix enzyme known to promote cross-linking of collagen, and gremlin-1 (Grem1), a bone morphogenetic protein (BMP) antagonist known to induce excessive proliferation. We hypothesize that skeletal muscle SIRT3 deficiency promotes PH-HFpEF by secreting LOXL2 and Grem1, which act as endocrine signaling molecules to induce pulmonary vascular remodeling. We plan to use a number of cutting-edge approaches, which include the use of ex vivo precision-cut lung slices and in vivo skeletal muscle-specific KO mice, to address the outstanding questions. Specific Aims: 1) To determine whether skeletal muscle SIRT3 deficiency in the metabolic syndrome contributes to the development of PH-HFpEF. Using wild-type and skeletal muscle-specific Sirt3 KO mice, with or without high-fat feeding (HFD), which induces a PH-HFpEF phenotype, we will characterize the contribution of skeletal muscle SIRT3 deficiency to the development of PH-HFpEF. Results may reveal a systemic pathogenic impact of skeletal muscle SIRT3 deficiency in remote pulmonary vascular remodeling and PH- HFpEF. 2, 3) To determine whether LOXL2 and Grem1 are endocrine signaling molecules produced by SIRT3- deficient skeletal muscle cells to induce pulmonary vascular remodeling. Conditioned media from SIRT3- deficient skeletal muscle cells, with or without LOXL2 and Grem1 inhibition, will be applied to ex vivo precision- cut lung slices to test if SIRT3 deficiency with subsequent elevated secretion of LOXL2 and Grem1 promotes vascular remodeling via increased collagen cross-linking and excessive proliferation of pulmonary artery endothelial and smooth muscle cells. The role of skeletal muscle-secreted LOXL2 and Grem1 in pulmonary vascular remodeling and PH-HFpEF will be determined in vivo using skeletal muscle-specific Loxl2 and Grem1 KO mice with HFD. LOXL2 and Grem1 targeting therapies will also be evaluated in our recently developed rat model of PH-HFpEF. We aim to firmly establish the novel paradigm of a skeletal muscle-lung vasculature crosstalk in PH-HFpEF through endocrine signaling. We expect that successful execution of the proposed research plan would provide new mechanistic understanding of PH-HFpEF and identify skeletal muscle SIRT3, along with its downstream LOXL2 and Grem1, as potential molecular targets for the diagnosis and treatment of PH-HFpEF. Furthermore, our studies would provide new insights into how metabolic syndrome, aging, and exercise inactivity affect pulmonary vascular health.