Role of Skeletal Muscle in Pulmonary Vascular Remodeling

肺动脉高压伴心衰并保留射血分数(PH-HFpEF)是最多的 世界范围内PH的共同原因，影响到美国约150万心力衰竭患者 只有一个州。目前，尚未确定具体的治疗方法，这主要是因为主要途径 目前对PH-HFpEF的调控机制还不是很清楚。我们最近发现了令人信服的 有证据表明，PH-HFpEF调节sirtuin-3(SIRT3)主要在骨骼肌中减少。在……里面 事实上，我们新的初步数据显示，骨骼肌中SIRT3的缺失会导致SIRT3的急剧减少 肺血管树病变，伴有血管重塑增加和肺活量增加 压力，表明骨骼肌SIRT3在肺血管重塑和PH-HFpEF中起关键作用。 基于基于全球质谱学的比较分泌组分析，我们的新数据表明 骨骼肌SIRT3缺乏促使基质酶赖氨酰氧化酶同源2(LOXL2)的分泌 已知促进胶原和骨形态发生蛋白(BMP)Gremlin-1(Grem1)的交叉连接 已知可引起过度增殖的拮抗剂。我们假设骨骼肌SIRT3缺乏 通过分泌LOXL2和Grem1促进PH-HFpEF，它们作为内分泌信号分子诱导 肺血管重塑。我们计划使用一些尖端方法，其中包括使用 体外精密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)确定代谢综合征是否存在骨骼肌SIRT3缺陷 有助于PH-HFpEF的发展。使用野生型和骨骼肌特异性SIRT3KO小鼠， 或者没有诱导PH-HFpEF表型的高脂喂养(HFD)，我们将表征其贡献 骨骼肌SIRT3缺乏对PH-HFpEF发生的影响。结果可能揭示出系统性的 骨骼肌SIRT3缺乏对远端肺血管重构和肺高压的致病作用 HFpEF。2、3)确定LOXL2和Grem1是否是SIRT3产生的内分泌信号分子- 骨骼肌细胞缺乏诱导肺血管重塑。来自SIRT3的条件媒体- 缺失的骨骼肌细胞，无论是否有LOXL2和Grem1抑制，都将被应用于体外精确- 切肺切片以检测SIRT3缺乏是否促进LOXL2和Grem1的分泌 胶原交联增加和肺动脉过度增殖所致的血管重塑 血管内皮细胞和平滑肌细胞。骨骼肌分泌的LOXL2和Grem1在肺损伤中的作用 血管重构和PH-HFpEF将使用骨骼肌特异性LOXL2和Grem1在体内确定 感染HFD的KO小鼠。LOXL2和Grem1靶向治疗也将在我们最近开发的大鼠身上进行评估 PH-HFpEF模型。 我们的目标是在PH-HFpEF中牢固地建立骨骼肌-肺血管系统串扰的新范式 通过内分泌信号。我们预计，拟议研究计划的成功执行将提供 对PH-HFpEF的新机制认识和鉴定骨骼肌SIRT3及其下游 LOXL2和Grem1作为诊断和治疗PH-HFpEF的潜在分子靶点。此外， 我们的研究将为新陈代谢综合征、衰老和运动缺乏如何影响提供新的见解 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.