Gremlin在早产儿视网膜病变中的作用和相关机制研究

Pathological angiogenesis and fibrous proliferation are crucial in the pathological process of retinopathy of premature (ROP), which is retinal neovascular disease with unclear definite mechanism. Futher exploring the pathogenesis of ROP could provide underlying therapeutic targets. Gremlin has been recently recognized as a factor promoting pathological angiogenesis and fibrous proliferation. More recent researches found that Gremlin represents a novel proangiogenic VEGFR2 agonist distinct from the VEGF family ligands. Gremlin is constitutively expressed in retina and significantly increased by hypoxia in vivo. Gremlin can induce retinal vascular endothelial cell proliferation and retinal pigment epithelial cell epithelial-to-mesenchymal transition,thus promote retinal neovascularization and fibroproliferative membrane formation. Considerable evidences have been presented for an important role for Gremlin in the development of ROP. Our research is intending to silence the expression of Gremlin mRNA and protein in vitro by RNA interference (RNAi), and inhibit effects with an anti-Gremlin 1 monoclonal antibody in vivo, investigate cellular interactions of Gremlin with other proangiogenic factors, observe the pathological process of ROP by suppressing Gremlin, clarify the potential mechanism of Gremlin contributing to ROP, and evalute the effects of Gremlin as a new therapeutic target in the prevention and treatment of ROP.

早产儿视网膜病变（ROP）是一种视网膜血管性疾病，病理性血管新生和纤维增殖是其发生发展中的两个重要环节，对其发生机制的深入探讨可为ROP的早期治疗提供潜在靶点。Gremlin是促病理性血管新生和纤维增殖的重要调控因子。最新研究证实，Gremlin是血管内皮生长因子受体（VEGFR2）激动剂，低氧可诱导Gremlin基因的高表达，Gremlin在视网膜上阳性表达，可促进视网膜血管内皮细胞增殖形成新的血管，能诱导视网膜色素上皮细胞转化，促进视网膜的增殖。这些都提示Gremlin可能在ROP发病过程中有重要作用。本课题拟应用RNAi技术，在细胞水平沉默Gremlin表达，在动物水平应用抗体抑制Gremlin的作用，验证Gremlin与其他血管生成调节因子之间的功能联系，初步阐明Gremlin在ROP发病过程中的作用机理，观察Gremlin抑制后ROP的病程变化，评价其治疗效果。

早产儿视网膜病变（ROP）是一种视网膜血管性疾病，病理性血管新生和纤维增殖是其发生发展中的两个重要环节，对其发生机制的深入探讨可为ROP的早期治疗提供潜在靶点。Gremlin是一个重要的血管内皮生长因子（VEGF）受体2（VEGFR2）激动剂，低氧可诱导Gremlin基因的高表达，且Gremlin在视网膜上呈阳性表达。Netrin-1是一种神经导向因子，对脉管系统的增殖和形态构建发挥正负双向调节作用。本项目研究了Gremlin和Netrin-1在视网膜细胞中的表达和功能，通过基因沉默技术抑制Gremlin和Netrin-1的表达，进一步验证其功能作用，并检测Gremlin和Netrin-1发挥作用的信号通路。本研究发现Gremlin和Netrin-1在ROP模型小鼠视网膜上显著高表达，与VEGF因子上调相关；Gremlin和Netrin-1均可促进视网膜色素上皮细胞（RPE）的增殖、迁移和VEGF生成；shRNA敲除VEGFR2，shRNA敲除Netrin-1受体UNC5B，可分别阻断Gremlin和Netrin-1的上述作用；Gremlin通过激活VEGFR2-Akt-mTORC2信号通路，Netrin-1通过激活UNC5B-mTORC2通路发挥作用。本研究揭示Gremlin和Netrin-1可能是ROP病理过程中除VEGF以外的重要致病因子，抑制其作用可能为ROP的早期治疗提供新的靶点。