Systems Biology of Angiogenesis in Peripheral Arterial Disease

 描述(申请人提供)：外周动脉疾病(PAD)是一种主要的健康问题，它是由动脉粥样硬化引起的，阻碍了流向下肢的血液流动。目前尚无药物治疗PAD具有增加血流灌注量和纠正血流受损的能力。到目前为止，覆盖数千名患者的数十项人体治疗性血管生成试验几乎一致失败。我们认为，PAD的人类血管生成治疗方案的部署没有充分认识到在分子、细胞、组织/器官和全身水平上调节众多相互竞争的过程的复杂性，从而解释了临床试验失败的原因。为了从根本上理解这些现象并开发新的治疗方法，将定量计算系统生物学方法与实验测量相结合不仅是可取的，而且是绝对必要的。该项目的广泛目标是通过预测计算建模和活体实验的高度协同组合，获得对PAD中血管生成的定量了解；并进一步利用这些知识，设计改进的和新型的人类疗法。该项目提出了一种范式转变，从单纯通过给予促血管生成分子来刺激血管生成，到通过抑制内源性抗血管生成分子来刺激血管生成。在具体目标1中，我们将扩展非缺血肌和缺血肌的系统特征，以了解以前未被解释的内源性抗血管生成异构体血管内皮生长因子VEGFxxxb的影响。我们将建立计算模型来预测健康的非缺血小鼠肌肉和后肢缺血(HLI)后以及人类患者中血管内皮生长因子受体配体的激活动态，以探索PAD的新的潜在治疗靶点。在特定的目标2中，我们将内源性抗血管生成蛋白血栓反应蛋白-1(TSP1)表征为PAD的潜在治疗靶点。TSP1是一种通过多个受体传递信号的强抗血管生成剂；已有研究表明，TSP1在PAD中升高。我们将重新开发通过TSP1受体的信号转导的计算模型，同时考虑它们与血管内皮生长因子通路的串扰。我们将在小鼠身上进行体内实验，以量化TSP1的作用，无论是否给予TSP1及其受体的中和剂。这一结果将为PAD的新的治疗方法提供基础。具体目标3致力于描述先前存在的血管稀疏的影响。人类PAD是一种慢性疾病，伴随着多年的动脉粥样硬化堆积，导致受影响远端肌肉中的血管稀疏，而目前的PAD小鼠模型没有这种预先存在的较低的血管密度，从而人为地增加了治疗的有效性。我们将重点放在鼠标垫模型的后期阶段，而不是更常见的急性阶段。该项目将为PAD带来重要的新知识和新的治疗策略。

 DESCRIPTION (provided by applicant): Peripheral arterial disease (PAD), caused by atherosclerosis that impairs blood flow to the lower extremities, is a major health problem. Currently there are no pharmacological therapies for PAD that have the ability to increase perfusion and correct the impaired blood flow. To date, dozens of trials of therapeutic angiogenesis in humans covering thousands of patients have almost uniformly failed. We pose that human angiogenesis treatment regimens for PAD were deployed without an adequate appreciation of the complexities that regulate the numerous competing processes at the molecular, cellular, tissue/organ, and whole body levels; thus accounting for clinical trial failurs. To understand these phenomena at the fundamental level and to develop novel therapeutic approaches, quantitative computational systems biology approaches synergistically combined with experimental measurements are not only desirable but absolutely necessary. The broad goal of the project is to gain a quantitative understanding of angiogenesis in PAD, using a highly synergistic combination of predictive computational modeling and in vivo experiments; and further, using this knowledge, to design improved and novel human therapeutics. This project presents a paradigm shift from stimulating angiogenesis purely by administration of pro-angiogenic molecules to stimulating angiogenesis by inhibiting endogenous anti-angiogenic molecules. In Specific Aim 1 we will expand systems characterization of non-ischemic and ischemic muscle to understand the impact of previously unaccounted-for endogenous anti-angiogenic isoforms of vascular endothelial growth factor VEGFxxxb. We will formulate computational models to predict the dynamics of VEGF receptor-ligand activation in healthy non-ischemic mouse muscle and following hind-limb ischemia (HLI) and in human patients to explore novel potential therapeutic targets for PAD. In Specific Aim 2 we will characterize endogenous anti-angiogenic protein thrombospondin-1 (TSP1) as a potential therapeutic target for PAD. TSP1 is a strong anti-angiogenic agent transducing signals through multiple receptors; TSP1 has been shown to be elevated in PAD. We will develop, de novo, computational models of signal transduction through TSP1 receptors, also considering their crosstalks with the VEGF pathways. We will conduct in vivo experiments in mice to quantitate the role of TSP1, with and without administration of neutralizing agents for TSP1 and its receptors. The results will serve a basis for novel therapeutic approaches to PAD. Specific Aim 3 is devoted to characterization of the impact of pre- existing vascular rarefaction. Human PAD is a chronic disease that follows years of atherosclerotic buildup, resulting in vascular rarefaction in the affected distal muscle, whereas current mouse models of PAD do not have this pre-existing lower vascular density, thereby artificially increasing the perceived effectiveness of therapies. We will focus on later stages of the mouse PAD model, instead of the more common acute stage. The project should lead to important new knowledge and to novel therapeutic strategies in PAD.