Division of Endocrinology and Metabolism, Department of Internal Medicine, College of Medicine, Chung-Ang University, Seoul, Republic of Korea.
Department of Ophthalmology, College of Medicine, Yeungnam University, Daegu, Republic of Korea.
Biochem Biophys Res Commun. 2019 Aug 20;516(2):350-356. doi: 10.1016/j.bbrc.2019.06.046. Epub 2019 Jun 14.
Receptor activator of NF-κB ligand (RANKL) is a member of the TNF superfamily. RANKL increases endothelial permeability and induces angiogenesis, suggesting its critical roles in the vasculature. Despite the evidence implicating RANKL in vascular pathology, its role in ischemic retinopathy has not been previously reported. In this study, neonatal mice were exposed to 75% oxygen from postnatal day (P)7 to P12 to induce vaso-obliteration, and then returned to room air from P12 to P17, causing the retina to become hypoxic and inducing vascular endothelial growth factor (VEGF) signaling, which produces pathological neovascularization. On P12, the mice received a single intravitreal injection of control IgG1 or RANK-Fc, and retinas were obtained at P17. On P17, RANKL was expressed strongly and selectively in the neovascular tufts (NVT) area. RANKL colocalized with αSMA or PDGFRβ in NVT. However, co-immunostaining revealed that CD31-positive areas were not the same as RANKL, which indicates that RANKL might be produced by retinal pericytes, not endothelial cells. Consistent with this finding, chemical hypoxia upregulated RANKL expression in cultured human retinal pericytes but not in endothelial cells. Treatment with RANK-Fc markedly reduced the NVT area compared to that in mice administered the IgG1 injection. In contrast, the central avascular region of RANKL-Fc retina was comparable to the controls. In addition, we assessed retinal vascular permeability using FITC-labeled dextran. RANK-Fc treated mice displayed decreased vascular leakages compared to those injected with IgG1. Our work supports the use of an RANKL blockade as a potential therapeutic approach against ischemic retinopathies.
核因子-κB 受体激活物配体（RANKL）是肿瘤坏死因子超家族的一员。RANKL 增加血管内皮通透性并诱导血管生成，表明其在血管中起关键作用。尽管有证据表明 RANKL 与血管病理学有关，但它在缺血性视网膜病变中的作用尚未被报道。在这项研究中，新生小鼠从出生后第 7 天（P7）至 P12 暴露于 75%的氧气中以诱导血管闭塞，然后从 P12 至 P17 回到常氧环境，导致视网膜缺氧并诱导血管内皮生长因子（VEGF）信号转导，从而产生病理性新生血管。在 P12 时，小鼠接受了单次玻璃体腔内注射对照 IgG1 或 RANK-Fc，并在 P17 时获得视网膜。在 P17 时，RANKL 在新生血管丛（NVT）区域强烈且选择性地表达。RANKL 在 NVT 中与 αSMA 或 PDGFRβ 共定位。然而，共免疫染色显示 CD31 阳性区域与 RANKL 不同，这表明 RANKL 可能由视网膜周细胞产生，而不是内皮细胞。与这一发现一致，化学缺氧上调了培养的人视网膜周细胞中的 RANKL 表达，但对内皮细胞没有作用。与 IgG1 注射组相比，RANK-Fc 治疗显著减少了 NVT 区域。相比之下，RANKL-Fc 视网膜的中央无血管区域与对照组相当。此外，我们使用 FITC 标记的葡聚糖评估视网膜血管通透性。与注射 IgG1 的小鼠相比，RANK-Fc 处理的小鼠显示出血管渗漏减少。我们的工作支持使用 RANKL 阻断作为治疗缺血性视网膜病变的潜在方法。
