Department of Immunology and Pathology, The Central Clinical School, Monash University, Melbourne, Victoria, Australia; Victoria University, Ballarat Road, Footscray, Victoria, Australia.
Department of Diabetes, The Central Clinical School, Monash University, Melbourne, Victoria, Australia; Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia.
Exp Eye Res. 2020 Feb;191:107902. doi: 10.1016/j.exer.2019.107902. Epub 2019 Dec 26.
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% O) 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.
小胶质细胞是神经炎症和血管损伤的重要贡献者，这些损伤发生在缺血性视网膜病变中。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，会增加视网膜中小胶质细胞的密度，并刺激它们产生活性氧（ROS）以及促血管生成和促炎因子。研究了两种动物模型，它们的特征是 Ang II 或醛固酮的上调，包括在组织中过度表达肾素和 Ang II 的转基因 Ren-2 大鼠，以及接受醛固酮输注的缺血性视网膜病变的 Sprague Dawley 大鼠。在接受低氧（0.5% O）和血管紧张素 1 型受体（缬沙坦）、盐皮质激素受体（螺内酯）或醛固酮合酶（FAD286）抑制剂处理的新生 Sprague Dawley 大鼠视网膜小胶质细胞的原代培养物中进行了补充研究。在两种体内模型中，与遗传或载体对照相比，离子钙结合衔接蛋白 1 标记的小胶质细胞/巨噬细胞的密度在视网膜中增加。在视网膜小胶质细胞的原代培养物中，低氧增加了活性氧（超氧）水平以及 NADPH 氧化酶（NOX）同工型 NOX1、NOX2 和 NOX4 的表达。所有处理均降低了升高的 ROS 水平以及 NOX2 和 NOX4 的水平，缬沙坦和 FAD286 还降低了 NOX1 mRNA 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 降低了缺氧诱导的强力促血管生成和促炎剂血管内皮生长因子以及炎症因子 CCL5 和干扰素 γ的增加。缬沙坦还降低了缺氧诱导的 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，我们的发现表明，Ang II 和醛固酮都影响视网膜小胶质细胞的激活，这表明肾素-血管紧张素-醛固酮系统参与了缺血性视网膜病变的发病机制。
