Notch信号调控小胶质细胞亚群和功能异质性在缺血性视网膜病变血管重构中的作用和机制

The reconstruction of retinal vasculature in ischemic retinopathy is the basis of retinal homeostasis and functional recovery. Retinal microglia (MG) is the specialized macrophage (MΦ) involved in tissue development, homeostasis and wound repair, and could play multiple roles in retinal vascular repair. Microglia could be consisted of tissue resident microglia (MG-T) derived from yolk sac and inflammatory microglia (MG-I) specialized from bone marrow derived monocytes. However, the contribution, functional heterogeneity and molecular modulations of these two subpopulations in retinal vascular reconstruction are still unclear. We previously demonstrated that Notch signaling play a crucial role in vascular homeostasis and MΦ activation. The specific role of Notch signaling on MG subpopulations in retinal vascular reconstruction, and the underlying mechanisms are still obscure. Here, by using CX3CR1GFP/+ transgenic mice which could specifically identify MG-T, CCR2-/- mice which are deficient of bone marrow macrophage, MΦ/MG specific knockout of Notch/RBP-J mice and oxygen induced retinopathy mice model, we aim to reveal the contribution of MG-T and MG-I in retinal vascular repair, and to investigate the molecular mechanisms of Notch–mediated regulation of MG subpopulations, and moreover, from this point, to look into the possibility to promote retinal vascular reconstruction by modulation on MG. These studies are expected to expand the knowledge of MG on retinal angiogenesis and vascular reconstruction. The results will provide new strategies and targets for the intervention of MG; therefore it should have important theoretical significance and potential application value in ischemic ocular diseases.

缺血性视网膜病的血管重构是视网膜恢复组织稳态和功能的重要基础。小胶质细胞(MG)作为视网膜内调节微环境的一群巨噬细胞(MΦ)，在血管重构中发挥多重作用。MG由卵黄囊来源的组织定居型MG(MG-T)和骨髓单核细胞分化的炎性MG(MG-I)组成。它们各自对血管重构的贡献如何、通过何种机制调控尚未阐明。我们前期报道Notch信号在血管稳态中的关键作用，并可调控MΦ/MG的功能，但其是否调控MG参与血管重构及机制都有待回答。本课题拟采用CX3CR1GFP/+小鼠、CCR2-/-小鼠、MΦ/MG中特异性敲除Notch/RBP-J小鼠和氧诱导视网膜病变模型，首先明确MG亚群对视网膜血管重构的贡献，进而阐明Notch信号介导MG亚群参与血管重构的作用和机制，最后探讨调控MG功能异质性对血管重构的促进作用。本研究可深入揭示MG在视网膜血管重构中的作用及机制，为缺血性眼病的靶向防治提供新思路。

缺血性视网膜病的血管重构是视网膜恢复组织稳态和功能的重要基础。小胶质细胞(MG)作为视网膜内调节微环境的一群组织定居的特殊类型巨噬细胞(MΦ)，在血管重构中发挥多重作用。有研究提示，视网膜中MG可由卵黄囊来源的组织定居型MG(MG-T)和骨髓单核细胞分化的炎性MG(MG-I)组成。然而，它们各自对血管重构的贡献如何、通过何种机制调控尚未阐明。我们前期报道Notch信号在血管稳态中的关键作用，并可调控MΦ/MG的功能，但Notch信号是否调控MG参与血管重构及机制都有待回答。 .基于这些问题，本课题采用CX3CR1GFP/+小鼠、CX3CR1-Cre、MΦ/MG中特异性敲除Notch/RBP-J小鼠和氧诱导视网膜病变模型（OIR模型），利用单细胞测序技术、流式细胞鉴定和分选等技术，首先明确在视网膜血管重构过程中，活化的MG存在两种来源即MG-T （CX3CR1highCCR2-）和MG-I（CX3CR1highCCR2+），两个MG亚群通过细胞代谢、细胞增殖和迁移等多重功能差异对视网膜血管重构有着不同的贡献。随后，通过体内和体外特异性敲除Notch信号，证实敲除MG-I中Notch信号确实可影响血管重构中的视网膜无灌注区及新生血管面积，MG-I与内皮细胞的共培养抑制新生血管形成，结果初步阐明Notch信号可能介导MG亚群参与血管重构。本研究初步证实在视网膜血管重构阶段，不同来源MG均参与其中，且发挥不用的作用。不同来源的MG在细胞代谢、炎症等多方面呈现不同的功能。Notch信号通路可能对不同来源的MG发挥不同的调控作用，从而参与视网膜血管重构。本研究有望深入揭示MG在视网膜血管重构中的作用及机制，为缺血性眼病的靶向防治提供新思路。