The role of phagocytosis for modulation and clearance of pathological angiogenesis.

增殖性视网膜病，例如早产儿视网膜病（ROP）或增殖性糖尿病视网膜病（DR）代表重要的健康负担，是失明的主要原因。退行性视网膜病的特征在于视网膜中的病理性新血管形成（血管生成），导致形成异常的新血管，所谓的簇，其突出超过视网膜内界膜进入玻璃体腔，引起严重的视力损害。有趣的是，我们观察到，内皮细胞凋亡是这些簇的标志，这可能启动在ROP中观察到的簇消退和血管正常化的过程。视网膜病变的病理生理学基础的一个主要组成部分是内皮细胞与炎症细胞的密切相互作用，其由微环境的特定组分调节，例如局部缺氧/复氧。本提案的目的是研究小胶质细胞的吞噬特性是否参与ROP过程中病理性簇中凋亡内皮细胞的清除，从而调节增殖性视网膜病变背景下的病理性血管生成。我们将通过将SOCS 3的小胶质细胞特异性缺失作为一种特异性工具来解决这个问题，因为我们有初步证据表明该因子调节吞噬作用。特别地，我们将评估（I）具有改变的吞噬能力的小胶质细胞Socs 3是否可以通过参与小鼠缺氧诱导的早产儿血管增生性视网膜病变（ROP）模型来影响体内生理和病理视网膜血管生成。(II)此外，我们希望在报告小鼠的帮助下鉴定体内内皮细胞或内皮细胞颗粒是否被小胶质细胞摄取，并且我们将研究小鼠ROP模型中促吞噬细胞分子和抗吞噬细胞分子的表达动力学。(III)此外，我们将分析缺氧/再氧合和/或凋亡内皮细胞的摄取是否刺激骨髓细胞向促凋亡和促消退表型重编程。 (IV)最后，作为原理的证明，我们将评估单核细胞对凋亡细胞清除率（凋亡细胞增多）的调节是否可用作治疗病理性血管疾病的新治疗策略。 尽管在过去几年中取得了进展，但对视网膜病变的发病机制、潜在机制以及内皮细胞和炎性细胞相互作用的了解仍然不足，治疗方法也有限。因此，这一建议是高度创新的，因为它将提供新的机制见解的作用，小胶质细胞吞噬活性的背景下，增殖性视网膜病变。对潜在机制的更好理解可能随后导致新的治疗概念，以防止失明。

Proliferative retinopathies, such as retinopathy of prematurity (ROP) or proliferative diabetic retinopathy (DR) represent an important health burden being a major cause of blindness. Proliferative retinopathies are characterized by pathological neovascularization (angiogenesis) in the retina leading to the formation of aberrant neo-vessels, so called tufts, which protrude beyond the retinal inner limiting membrane into the vitreous cavity, causing severe vision impairment. Interestingly we observed, that endothelial cell apoptosis is a hallmark of these tufts, which might initiate the process of tuft regression and vessel normalization, observed in ROP. A major component of the pathophysiology underlying retinopathy is the close interplay of endothelial cells with inflammatory cells that is regulated by specific components of the micro-environment, e.g. local hypoxia/ reoxygenation. The aim of the present proposal is to investigate whether the phagocytic property of microglia is involved in the clearance of apoptotic endothelial cells in the pathological tufts during ROP and thus modulates pathological angiogenesis in the context of proliferative retinopathy. We will address this question by engaging microglia-specific deletion of SOCS3 as a specific tool, as we have preliminary evidence, that this factor regulates phagocytosis. In particular, we will assess (I) whether microglial Socs3, with its altered phagocytic capacity, can affect in-vivo physiological and pathological retinal angiogenesis by engaging the mouse hypoxia-induced vasoproliferative retinopathy of prematurity (ROP) model. (II) In addition, we want to identify with the help of reporter mice, whether in vivo endothelial cells or endothelial cell particles are taken up by microglia and we will study the expression kinetics of pro- and anti-phagocytic molecules in the mouse ROP-model. (III) Moreover we will analyse whether hypoxia/reoxigenation and/ or the uptake of apoptotic endothelial cells are stimuli to reprogram myeloid cells towards a pro-efferocytic and pro-resolving phenotype. (IV) Finally, as a proof of principle, we will evaluate if the modulation of apoptotic cell clearance (efferocytosis) by mononuclear cells can be used as a new therapeutic strategy for the treatment of pathological vascular disorders. Despite the progress made in the last years, understanding the pathogenesis of retinopathy, the knowledge of the underlying mechanisms and the interaction of endothelial and inflammatory cells is still insufficient and therapeutics are limited. Therefore, this proposal is highly innovative, since it will provide novel mechanistic insights into the role of microglia cell phagocytic activity in the context of proliferative retinopathy. The improved understanding of the underlying mechanism may subsequently lead to novel therapeutic concepts to prevent blindness.