Pathomechanisms and modulation of impaired angiogenesis in chronic kidney disease (CKD)

慢性肾脏病（CKD）患者不成比例地遭受心血管并发症和心源性死亡。其发病机制尚不清楚，现有的预防心血管并发症的策略在CKD患者中往往失败。基于我们以前的工作，我们提出CKD中形成新毛细血管的能力受损有助于心血管疾病的负担。毛细血管生成是一个不可或缺的适应性过程，以科普过程，如大血管狭窄/闭塞或心脏肥大，通过恢复受影响器官的灌注。我们建议的总体目标是更好地了解CKD中血管生成受损的病理生理学，并开发治疗方法来改善CKD中的毛细血管形成。使用一个完善的大鼠模型CKD（肾大部切除术）和以前采用的读出系统，以评估心肌毛细血管密度，缺血诱导的毛细血管生成骨骼肌以及心肌梗死面积，我们提出了以下具体目标：首先，我们将使用脯氨酰羟化酶（伊卡）的抑制剂，以稳定缺氧诱导因子（HIF），以改善毛细血管的形成。在初步实验中，我们已经证明：（a）缺血对HIF靶点的激活在CKD中减少，以及（B）在缺血前应用非药理学方法（0.1%CO气体）和使用伊卡的药理学方法以稳定HIF大大改善CKD大鼠缺血后肢中的毛细血管形成。我们现在将开发这种方法作为诱导缺血后应用的治疗方案中的药理学工具。此外，我们将评估伊卡治疗是否改善CKD大鼠的心肌毛细血管供应并限制心肌梗死范围。（CCL 7和金属硫蛋白-1a）对CKD中受损的血管生成的作用，其来源于来自CKD与对照大鼠的缺血性与非缺血性肢体中的Affyphin微阵列基因表达筛选，在诱导缺血后24小时获得。这两个候选人都有已知的血管生成特性，他们的时间和空间表达模式将进行研究。此外，将进行体外实验以研究脯氨酰羟化酶抑制剂CCL 7和金属硫蛋白-1a对毛细血管形成的功能。增殖、凋亡和不同的细胞迁移试验将用于阐明我们的分子靶标的潜在促血管生成作用是否是由于对内皮细胞的直接作用（而不是通过例如浸润单核细胞的间接作用）。随后，我们将阐明所观察到的促血管生成作用的信号转导途径。从我们提出的实验中，我们期望在CKD血管生成受损的发病机制方面有新的见解，并展望新的治疗方法。

Patients with chronic kidney disease (CKD) suffer disproportionately from cardiovascular complications and cardiac death. The pathogenesis is not well understood, and existing strategies to prevent cardiovascular complications have often failed in CKD patients. Based on our previous work, we propose that an impaired capacity to form new capillary vessels in CKD contributes to the burden of cardiovascular disease. Capillary angiogenesis is an indispensable adaptive process to cope with processes such as macrovascular stenosis/occlusion or heart hypertrophy by restoring the perfusion of the affected organs. The overall aim of our proposal is to better understand the pathophysiology of impaired angiogenesis in CKD, and to develop therapeutic approaches to improve capillary formation in CKD. Using a well-established rat model of CKD (subtotal nephrectomy) and previously employed readout systems to assess myocardial capillary density, ischemia-induced capillary angiogenesis in skeletal muscle as well as myocardial infarct size, we propose the following specific aims:First, we will use an inhibitor of prolyl hydroxylase (ICA) to stabilize hypoxia-inducible factors (HIF) in order to improve capillary formation. In preliminary experiments, we have already demonstrated that (a) activation of HIF targets by ischemia is diminished in CKD, and that (b) a non-pharmacological approach (0.1% CO gas) and a pharmacological approach using ICA both applied before ischemia to stabilize HIF greatly improve capillary formation in the ischemic hindlimb of CKD rats. We will now develop this approach as a pharmacological tool in a therapeutic protocol for application after the induction of ischemia. Further, we will assess whether ICA treatment improves myocardial capillary supply and limits myocardial infarct size in CKD rats.Second, we will test the functional role of 2 candidate molecular targets (CCL7 and Metallothionein-1a) for impaired angiogenesis in CKD which were derived from an Affymetrix microarray gene expression screen in ischemic versus non-ischemic limbs from CKD versus control rats, obtained 24 hours after induction of ischemia. Both candidates have known angiogenic properties; their temporal and spatial expression pattern will be investigated. Furthermore, in vitro experiments will be performed to investigate the function of the prolylhydroxylase inhibitor, CCL7 and metallothionein-1a for capillary formation. Proliferation-, apoptosis- and different cell migration assays will be used to elucidate if the potential pro-angiogenic effects of our molecular targets are due to direct actions on endothelial cells (as opposed to indirect effects via e.g. infiltrating mononuclear cells). Subsequently, we will elucidate the signal transduction pathwaysmediating the observed pro-angiogenic effects.From our proposed experiments, we expect novel insight in the pathogenesis of impaired angiogenesis in CKD, and a perspective toward new therapeutic approaches.