Trained immunity in the retina and its influence on retinal degenerative disorders

我们和其他人已经证明，当视网膜小胶质细胞被持续刺激病理激活时，它们会释放炎症介质，这些介质对产生视觉的视网膜神经元有害。然而，目前还不清楚哪些分子机制支撑了这些夸大的反应。我们在激光脉络膜新生血管模型中的初步数据表明，视网膜中存在先天免疫记忆。因此，本研究的目的是进一步探讨训练性免疫在小鼠视网膜非适应性炎症反应中的作用，以期更好地了解视网膜退行性疾病的免疫学基础。这项拟议的研究细分为两个具体目标。在具体目标1中，我们将努力确定是否可以通过在体内暴露于代谢或微生物小胶质启动刺激(外周或局部应用)来在视网膜上印记免疫记忆，以对随后的遗传或实验诱导的视网膜损伤产生增强的炎症反应。我们将在两个不同的小鼠模型中应用体内成像、小胶质细胞组织形态计量学和三种不同的高通量测序方法(RNA-Seq、ATAC-Seq和ChIP-Seq)，模拟人类视网膜色素变性和萎缩性年龄相关性黄斑变性的一些重要神经病理特征，并确定视网膜中的免疫记忆如何改变疾病的发病机制。在具体目标2中，我们将进行一项概念验证研究，并确定在两种视网膜病理模型中，使用细胞特异性敲除转化生长因子激活激酶1(Tak1)来阻断视网膜小胶质细胞的免疫记忆是否可以对两种视网膜病理模型的疾病结局产生积极影响。这项工作的成功完成将揭示控制视网膜免疫细胞激活的机制，并探索长期暴露于环境和生活方式应激源之间的潜在相互作用，这些应激源可能有助于视网膜病理的发展和进展。重要的是，完成拟议的工作有望识别视网膜中训练有素的免疫的关键介质，并为通过炎症成分减轻视网膜病变的新策略铺平道路。

We and others have shown that when retinal microglia become pathologically activated by sustained stimulation, they release inflammatory mediators which are detrimental to vision-producing retinal neurons. However, it is not yet clear which molecular mechanisms underpin these exaggerated responses. Our preliminary data in the laser model of choroidal neovascularization indicates the presence of innate immune memory in the retina. Therefore, the goal of this study is to further investigate the role of trained immunity in the development of maladaptive inflammatory responses in the mouse retina with the aim of better understanding the immunological basis of retinal degenerative disorders. The proposed study is subdivided into two specific aims. In specific aim 1, we will endeavor to determine whether immunological memory can be imprinted in the retina by in vivo exposure to a metabolic or microbial microglial priming stimulus (peripheral or local application) to generate an enhanced inflammatory response to subsequent genetically or experimentally induced retinal damage. We will apply in vivo imaging, microglia histomorphometry and three different high throughput sequencing methods (RNA-seq, ATAC-Seq, ChIP-seq) in two different mouse models that mimic some important neuropathological features of human retinitis pigmentosa and atrophic age-related macular degeneration and determine how immune memory in the retina can modify disease pathogenesis. In specific aim 2, we will perform a proof-of concept study and determine whether blocking immunological memory in retinal microglia using cell-specific knockout of transforming growth factor-activated kinase 1 (Tak1), a key epigenetic pathway for immune training, can positively influence disease outcome in the two mouse models of retinal pathology. Successful completion of this work will uncover mechanisms governing immune cell activation in the retina and explore the potential interactions between long-term exposure to environmental and lifestyle stressors that may contribute to the development and progression of retinal pathologies. Importantly, completing the proposed work holds promise to identify critical mediators of trained immunity in the retina and pave the way towards new strategies for mitigating retinal pathologies with an inflammatory component.