Microglial cells are important contributors to the neuroinflammation and blood vessel damage that occurs in ischemic retinopathies. We hypothesized that key effectors of the renin-angiotensin aldosterone system, angiotensin II (Ang II) and aldosterone, increase the density of microglia in the retina and stimulate their production of reactive oxygen species (ROS) as well as pro-angiogenic and pro-inflammatory factors. Two animal models were studied that featured up-regulation of Ang II or aldosterone and included transgenic Ren-2 rats which overexpress renin and Ang II in tissues including the retina, and Sprague Dawley rats with ischemic retinopathy and infused with aldosterone. Complementary studies were performed in primary cultures of retinal microglia from neonatal Sprague Dawley rats exposed to hypoxia (0.5% O2) and inhibitors of the angiotensin type 1 receptor (valsartan), the mineralocorticoid receptor (spironolactone) or aldosterone synthase (FAD286). In both in vivo models, the density of ionized calcium-binding adaptor protein-1 labelled microglia/macrophages was increased in retina compared to genetic or vehicle controls. In primary cultures of retinal microglia, hypoxia increased ROS (superoxide) levels as well as the expression of the NADPH oxidase (NOX) isoforms, NOX1, NOX2 and NOX4. The elevated levels of ROS as well as NOX2 and NOX4 were reduced by all of the treatments, and valsartan and FAD286 also reduced NOX1 mRNA levels. A protein cytokine array of retinal microglia revealed that valsartan, spironolactone and FAD286 reduced the hypoxia-induced increase in the potent pro-angiogenic and pro-inflammatory agent, vascular endothelial growth factor as well as the inflammatory factors, CCL5 and interferon γ. Valsartan also reduced the hypoxia-induced increase in IL-6 and TIMP-1 as well as the chemoattractants, CXCL2, CXCL3, CXCL5 and CXCL10. Spironolactone and FAD286 reduced the levels of CXCL2 and CXCL10, respectively. In conclusion, our findings that both Ang II and aldosterone influence the activation of retinal microglia implicates the renin-angiotensin aldosterone system in the pathogenesis of ischemic retinopathies.

中文翻译：

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血管紧张素II和醛固酮激活视网膜小胶质细胞。

小胶质细胞是缺血性视网膜病中发生的神经炎症和血管损伤的重要因素。我们假设肾素-血管紧张素醛固酮系统的关键效应物，血管紧张素II（Ang II）和醛固酮会增加视网膜中的小胶质细胞密度，并刺激其产生活性氧（ROS）以及促血管生成和促血管生成。炎性因子。研究了两个动物模型，它们具有Ang II或醛固酮的上调特征，包括在包括视网膜在内的组织中过表达肾素和Ang II的转基因Ren-2大鼠，以及患有缺血性视网膜病并注入了醛固酮的Sprague Dawley大鼠。在暴露于缺氧的新生Sprague Dawley大鼠的视网膜小胶质细胞的原代培养物中进行了补充研究（0。5％O2）和1型血管紧张素受体（valsartan），盐皮质激素受体（spironolactone）或醛固酮合酶（FAD286）的抑制剂。在两个体内模型中，与遗传或媒介物对照相比，视网膜中离子化钙结合适配器蛋白1标记的小胶质细胞/巨噬细胞的密度增加。在视网膜小胶质细胞的原代培养中，缺氧会增加ROS（超氧化物）水平以及NADPH氧化酶（NOX）亚型，NOX1，NOX2和NOX4的表达。所有处理均降低了ROS以及NOX2和NOX4的升高水平，而缬沙坦和FAD286也降低了NOX1 mRNA的水平。视网膜小胶质细胞的蛋白质细胞因子阵列显示，缬沙坦，螺内酯和FAD286可减少缺氧引起的有效促血管生成和促炎剂的增加，血管内皮生长因子以及炎性因子CCL5和干扰素γ。缬沙坦还减少了低氧诱导的IL-6和TIMP-1以及趋化因子CXCL2，CXCL3，CXCL5和CXCL10的增加。螺内酯和FAD286分别降低了CXCL2和CXCL10的水平。总之，我们的研究结果表明，Ang II和醛固酮均会影响视网膜小胶质细胞的激活，这提示肾素-血管紧张素醛固酮系统参与缺血性视网膜病的发病机理。