Ramipril treatment of claudication: oxidative damage and muscle fibrosis

 描述（由申请人提供）：跛行患者经历了严重的残疾，并且面临着有限的治疗选择，其中仅包括两种FDA批准的药物喷替茶碱和西洛他唑，这两种药物最多具有中等效果。最近的一项临床试验确定了雷米普利作为一种有前途的治疗药物，其步行距离的改善是Penaldifylline和Cilostazol的数倍，并且与监督运动疗法和手术血运重建产生的改善相似。拉米替尼产生这些效应的机制尚不清楚。根据我们对周围动脉疾病（PAD）跛行患者小腿肌肉组织病理学及其与腿部功能的关系的研究，我们设计了本研究，旨在确定雷米普利如何在跛行患者中产生有益作用。我们的假设是，用雷米普利治疗跛行PAD患者，通过改善腓肠肌肌病改善步行能力和生活质量。改善的肌病是减少氧化损伤、减少血管平滑肌细胞产生TGF-β 1和减少受累腓肠肌中胶原沉积的结果。我们将通过实现以下具体目标来检验我们的假设。具体目的#1将检验以下假设：在PAD患者中，雷米普利介导的行走参数改善与受损肢体腓肠肌中肌纤维的形态测量学和生物化学的改善相关。具体目的#2将检验以下假设：雷米普利介导的PAD患者行走参数的改善与受损肢体腓肠肌中小血管和微血管中纤维化事件的减少相关，并与全身胶原蛋白沉积的减少和组织氧合的改善相关。我们认为血管平滑肌细胞是PAD肌肉纤维化的主要介质。在具体目标#3中，我们将在体外使用成人动脉平滑肌细胞（AHASMC）来检验ACE抑制剂雷米普利的假设，雷米普利作为血管紧张素II 1型受体（ART 1）刺激的拮抗剂，通过减少组织血管紧张素II（Ang II），阻碍Ang II刺激ART 1和暴露于缺氧增强AHASMC增殖及其TGF-β 1和胶原蛋白产生的机制，通过刺激磷酸肌醇-3-激酶信号传导和抑制磷酸酶和张力蛋白同源物（细胞生长的主要调节物）。如果我们的假设是正确的，那么目标1和目标2中的工作将证明， 首次发现拉米替尼治疗可改善缺血下肢骨骼肌肌病，从而改善肢体功能和生活质量。目标3中的工作将确定缺氧和血管紧张素II协同诱导缺血性肌肉肌病的途径。针对这些通路的特异性药物可能成为跛行和更晚期PAD的新治疗方法。最后，这项研究的信息可能会发现新的工具，用于PAD的精确分期，评估治疗干预措施，并确定哪些患者将受益于积极的治疗。

 DESCRIPTION (provided by applicant): Patients with claudication experience significant disability and are faced with limited therapeutic options that include only two FDA approved medications Pentoxifylline and Cilostazol which have at best modest effects. A recent clinical trial identified Ramipril as a promising therapeutic agent that produced improvements in walking distances several times those of Pentoxifylline and Cilostazol and similar to those produced by supervised exercise therapy and operative revascularization. The mechanism(s) by which Ramipril produced these effects is unknown. On the basis of our work on the histopathology of lower leg muscle of claudicating patients with peripheral artery disease (PAD) and its relationship to leg function, we have designed the present study aimed at determining how Ramipril produces its beneficial effects in claudicating patients. Our HYPOTHESIS is that Treatment of claudicating PAD patients with Ramipril improves walking performance and quality of life by improving the myopathy of the gastrocnemius. Improved myopathy is a consequence of reduced oxidative damage, reduced TGF-ß1 production by vascular smooth muscle cells and reduced collagen deposition in the affected gastrocnemius. We will test our hypothesis by implementing the following Specific Aims. SPECIFIC AIM #1 will Test the hypothesis that Ramipril-mediated improvements of walking parameters among patients with PAD correlate with improvements in both the morphometrics and biochemistry of myofibers in the gastrocnemius of the impaired limb. SPECIFIC AIM #2 will Test the hypothesis that Ramipril-mediated improvements of walking parameters in patients with PAD, correlate with reduced fibrotic events in small vessels and microvasculature, in association with reduced generalized collagen deposition and improved tissue oxygenation, in the gastrocnemius of the impaired limb. We view vascular smooth muscle cells as the principle mediators of fibrosis in PAD muscle. In SPECIFIC AIM #3 we will use adult human arterial smooth muscle cells (AHASMC), in vitro, to test the hypothesis that the ACE inhibitor Ramipril, which acts as an antagonist of Angiotensin II type 1 receptor (ART1) stimulation by reducing tissue Angiotensin II (Ang II), impedes a mechanism in which Ang II stimulation of ART1 and exposure to hypoxia enhance proliferation of AHASMC and their production of TGF-ß1 and collagen, via stimulation of phosphoinositide-3-kinase signaling and suppression of phosphatase and tensin homologue, a master regulator of cell growth. If our hypothesis is correct, then the work in Aims #1 and #2 will demonstrate for the first time that therapy with Ramipril improves limb function and quality of life by improving the myopathy of skeletal muscles in the ischemic lower limbs. The work in Aim #3 will identify pathways by which hypoxia and Ang II collaborate to induce myopathy in ischemic muscle. Specific agents targeting these pathways could become new treatments for claudication and for more advanced stages of PAD. Finally, information from this study may identify new tools for precise staging of PAD, evaluating therapeutic interventions and identifying patients who will benefit from aggressive therapy.