Cellular Mechanisms of Retinopathy: Role of Arginase

项目摘要 该提案解决了一个具有重大临床意义的问题：缺乏有效的治疗方法来限制 神经血管损伤和促进修复在早期阶段的潜在致盲缺血性视网膜病变。 我们提出的研究旨在表明，增加免疫细胞中β-淀粉酶1的活性， 一种限制神经血管损伤和促进视网膜组织修复的新型高效策略， 缺血性视网膜病变的早期阶段。我们以前的研究表明尿素水解酶 糖尿病视网膜病变（DR）的神经血管损伤、缺血/再灌注损伤、视网膜缺血再灌注损伤、视网膜神经节细胞损伤等都与糖尿病视网膜病变有关。 (IR)和氧诱导的视网膜病变（OIR）。精氨酸酶代谢L-精氨酸以形成多胺、脯氨酸和脯氨酸。 谷氨酸盐。多胺氧化和谷氨酸的分解代谢产物可促进氧化损伤和细胞凋亡， 死亡过量的精氨酸酶活性也可减少生产精氨酸所需的L-精氨酸底物的供应。 一氧化氮（NO）通过一氧化氮合酶（NOS）。我们对DR模型的研究表明， 血管生成酶1（A1）亚型的表达/活性参与血管功能障碍和早产儿的发生。 衰老的机制涉及减少内皮型一氧化氮合酶（eNOS）的NO形成。相比之下，我们 在IR和OIR模型中的研究表明，腺苷酸酶2（A2）亚型通过以下途径参与神经血管损伤： 诱导型一氧化氮合酶（iNOS）和肿瘤坏死因子-α（TNF α）的上调机制， 通过激活TNF受体相互作用蛋白3激酶（RIP3）/动力蛋白相关蛋白1导致细胞死亡 （DRP1）轴。初步数据还表明，A2的缺失通过一种机制限制了这种损伤， 增加A1表达并抑制iNOS介导的NO形成。A1缺失全局或髓系- 衍生的细胞或M Φ耗竭可减轻损伤，而玻璃体内注射聚乙二醇化重组A1 （PegA1）限制损害。基于我们之前的工作和初步数据，我们假设A1可以保护 视网膜缺血性神经血管损伤通过降低iNOS水平和促进M Φ/髓样细胞介导的促增殖来实现。 生存功能这将通过以下目的进行测试：目的1将确定A1表达在IR中的作用。 引起神经血管损伤。目的2将确定A1是否通过促进修复性损伤来限制IR诱导的损伤。 M Φ。目的3：研究A1在OIR诱导的神经血管损伤中的作用，并探讨其在治疗OIR中的作用。 修复.如果成功，拟议的研究将代表视网膜病变研究领域的范式转变， 确定A1作为神经保护和血管修复的介质。

PROJECT SUMMARY This proposal addresses a problem of great clinical significance: the lack of effective therapies to limit neurovascular injury and promote repair during the early stages of potentially blinding ischemic retinopathies. We propose studies designed to show that increasing activity of the arginase 1 enzyme in immune cells offers a novel and highly effective strategy for limiting neurovascular injury and promoting retinal tissue repair in the early stages of ischemic retinopathy. Our previous studies have shown that the urea hydrolase enzyme arginase is critically involved in neurovascular injury in diabetic retinopathy (DR), ischemia/reperfusion injury (IR) and oxygen-induced retinopathy (OIR). Arginase metabolizes L-arginine to form polyamines, proline, and glutamate. Catabolic products of polyamine oxidation and glutamate can promote oxidative injury and cell death. Excessive arginase activity also can reduce the supply of L-arginine substrate needed for production of nitric oxide (NO) by NO synthase (NOS). Our studies in models of DR have shown that increased expression/activity of the arginase 1 (A1) isoform is involved in vascular dysfunction and premature senescence by a mechanism involving decreased NO formation by endothelial NOS (eNOS). In contrast, our studies in models of IR and OIR indicate that the arginase 2 (A2) isoform is involved in neurovascular injury by mechanisms involving upregulation of inducible NOS (iNOS) and tumor necrosis factor-α (TNFα) which leads to cell death via activation of the TNF receptor interacting protein 3 kinase (RIP3)/dynamin-related protein 1 (DRP1) axis. Preliminary data also show that deletion of A2 limits this damage by a mechanism involving increased A1 expression and suppressed iNOS-mediated NO formation. A1 deletion globally or in myeloid- derived cells, or MΦ depletion aggravates the injury whereas intravitreal injection of Pegylated recombinant A1 (PegA1) limits damage. Based on our prior work and preliminary data, we hypothesize that A1 protects against retinal ischemic neurovascular injury by reducing iNOS levels and promoting MΦ/myeloid cell-mediated pro- survival function. This will be tested by the following aims: Aim 1 will determine the role of A1 expression in IR- induced neurovascular injury. Aim 2 will determine whether A1 limits IR-induced injury by promoting reparative MΦ. Aim 3 will determine the role of A1 in OIR-induced neurovascular injury and test its potential in therapeutic repair. If successful, the proposed studies will represent a paradigm shift in the field of retinopathy research by identifying A1 as a mediator of neuroprotection and vascular repair.