Nrf2 signaling and oxidative stress in age-related macular degeneration

描述(申请人提供)：老年性黄斑变性(AMD)是老年人失明的主要原因，但早期疾病的患者没有治疗。为了解决这一缺陷，这项提议侧重于早期疾病。早期AMD的两个关键事件是视网膜色素上皮细胞(RPE)功能障碍和玻璃体生物发生。未充分中和的活性氧物种(ROS)和调节失调的天然免疫相互作用，发挥关键作用。氧化动态平衡的核心是Nrf2转录因子，它控制着最全面的抗氧化反应系统，尤其是在线粒体中。NRF2信号会随着年龄的增长和/或吸烟而受损。这项提案的目的是定义Nrf2如何保护RPE线粒体功能障碍和不受调节的天然免疫。需要检验的假设是，Nrf2信号受损导致线粒体和RPE功能障碍，导致氧化、炎症和病理微环境。提出的具体目标是：1.确定吸烟暴露下Nrf2信号受损导致未中和的线粒体ROS和RPE功能障碍的程度。我们的假设是，衰老和长期吸烟导致RPE中Nrf2信号的受损，降低了线粒体的抗氧化防御，导致ROS和RPE功能障碍的不充分中和。2.在香烟烟雾暴露下，确定Nrf2信号受损导致有丝分裂减少，并导致RPE功能障碍的程度。我们的假设是，衰老和长期吸烟导致RPE中Nrf2信号的受损，减少了有丝分裂，累积增加了功能障碍的线粒体数量，不能充分中和ROS，导致RPE功能障碍。3.确定受损的Nrf2信号干扰天然免疫调节的程度。基于我们的工作表明CS和Nrf2缺乏导致C3a和IL-1b的产生，我们的假设是Nrf2信号受损放大了氧化应激，从而激活了炎症小体，促进了促炎微环境的形成，并积累了功能受损的巨噬细胞。这些贡献意义重大，因为它们将使Nrf2成为早期AMD的治疗靶点。这项研究具有创新性，因为它将使用独特的、最先进的遗传小鼠来研究未被研究的(线粒体抗氧化剂和有丝分裂上的Nrf2信号减少)、未解决的(炎症体和巨噬细胞功能)和独特的(ROS和先天免疫的协同)因素对RPE和巨噬细胞功能的影响。巨噬细胞将从一个定义表型和功能的新角度进行研究，因为两者都受到环境的影响。我们发现，随着年龄的增长和CS的增加，Nrf2减少，产生C3a和IL-1b，这是炎症体的关键底物，拟议的研究将补体与炎症体、巨噬细胞功能和AMD表型联系起来，具有很高的创新性。这项工作有望产生重振Nrf2以维持氧化动态平衡和保护性先天免疫的靶向治疗。

DESCRIPTION (provided by applicant): Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly, yet patients with early disease are without therapy. To address this shortcoming, this proposal focuses on early disease. Two key events in early AMD are retinal pigment epithelial cell (RPE) dysfunction and drusen biogenesis. Inadequately neutralized reactive oxygen species (ROS) and dysregulated innate immunity interact together to play a pivotal role. Central to oxidative homeostasis, especially in mitochondria, is the Nrf2 transcription factor, which controls the most comprehensive antioxidant response system. Nrf2 signaling can become impaired with aging and/or smoking. The objective of this proposal to define how Nrf2 protects against RPE mitochondrial dysfunction and unregulated innate immunity. The hypothesis to be tested is that that impaired Nrf2 signaling induces mitochondrial and RPE dysfunction that results in an oxidative, inflammatory, and pathologic microenvironment. The proposed specific aims are: 1. Determine the extent that impaired Nrf2 signaling leads to un-neutralized mitochondrial ROS and RPE dysfunction with cigarette smoke exposure. Our hypothesis is that impaired Nrf2 signaling in the RPE from aging and chronic smoking reduces mitochondrial antioxidant defense resulting in inadequately neutralized ROS and RPE dysfunction. 2. Determine the extent that impaired Nrf2 signaling decreases mitophagy, and results in RPE dysfunction with cigarette smoke exposure. Our hypothesis is that impaired Nrf2 signaling in the RPE from aging and chronic smoking decreases mitophagy, cumulatively increasing the number of dysfunctional mitochondria and inadequately neutralized ROS, resulting in RPE dysfunction. 3. Determine the extent that impaired Nrf2 signaling disrupts regulation of innate immunity. Based on our work showing C3a and IL-1b generation by CS and Nrf2 deficiency, our hypothesis is that impaired Nrf2 signaling magnifies oxidative stress, which activates the inflammasome to promote a pro-inflammatory microenvironment with accumulation of macrophages with impaired function. These contributions are significant because they will establish Nrf2 as a treatment target for early AMD. The research is innovative since it will investigate understudied (decreased Nrf2 signaling on mitochondrial antioxidants and mitophagy), unresolved (inflammasome and macrophage function) and unique (the synergy of ROS and innate immunity) factors on RPE and macrophage function using unique, state-of-the- art genetic mice with fresh, but decisive factors that have not been previously tested. Macrophages will be studied from a new perspective that defines both phenotype and function since both are influenced by their surroundings. Our discovery of reduced Nrf2 with aging and CS, which generates C3a and IL-1b, a key substrate of the inflammasome, and the proposed studies, which will link complement with the inflammasome, macrophage function, and an AMD phenotype, is highly innovative. Targeted therapy that reinvigorates Nrf2 to maintain oxidative homeostasis and protective innate immunity is expected to result from this work.