Cellular Mechanisms of Retinopathy: Role of Arginase

项目总结 这项建议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 在潜在致盲的缺血性视网膜病变的早期阶段，神经血管损伤和促进修复。 我们提出的研究旨在表明，免疫细胞中精氨酸酶1活性的增加提供了 一种限制神经血管损伤和促进视网膜组织修复的新而高效的策略 缺血性视网膜病变的早期阶段。我们之前的研究表明，尿素水解酶 精氨酸酶在糖尿病视网膜病变中的神经血管损伤、缺血/再灌注损伤中起重要作用 (IR)和氧源性视网膜病变(OIR)。精氨酸酶代谢L-精氨酸形成多胺、脯氨酸和 谷氨酸。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 死亡。精氨酸酶活性过高也会减少生产所需的L-精氨酸底物的供应 一氧化氮(NO)通过一氧化氮合酶(NOS)。我们对糖尿病视网膜病变模型的研究表明， 精氨酸酶1(A1)亚型的表达/活性与血管功能障碍和早产有关 衰老的机制与内皮型一氧化氮合酶(ENOS)减少NO生成有关。相比之下，我们的 在IR和OIR模型中的研究表明，精氨酸酶2(A2)亚型通过 诱导型一氧化氮合酶和肿瘤坏死因子-α上调的机制 通过激活肿瘤坏死因子受体相互作用蛋白3激酶(RIP3)/动力蛋白相关蛋白1而导致细胞死亡 (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害 增加A1的表达，抑制iNOS介导的NO形成。A1全局或髓系中的缺失- 衍生细胞或MΦ的耗尽会加重损伤，而玻璃体内注射聚乙二醇化的重组A1 (PegA1)限制伤害。根据我们之前的工作和初步数据，我们假设A1可以预防 降低诱导型一氧化氮合酶水平和促进M-Φ/髓系细胞介导的促进性神经血管损伤 生存函数。这将通过以下目标进行检验：目标1将确定A1表达在IR中的作用- 诱发神经血管损伤。目标2将确定A1是否通过促进修复来限制IR诱导的损伤 我是Φ。目的3将确定A1在OIR诱导的神经血管损伤中的作用并测试其在治疗中的潜力 修理。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 确认A1是神经保护和血管修复的媒介。

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.