Non-canonical inflammasome in activation in RPE degeneration

地理性萎缩(GA)是老年性黄斑变性(AMD)的一种高级形式，是全球主要原因 影响着100多万美国人的失明。在构成GA的许多病理特征中， 主要标志之一是视网膜色素上皮(RPE)的退化，这也是FDA- 注册临床试验的接受终点。GA仍然是一个未得到满足的医疗需求，因为在很大程度上， 促进RPE退变的机制尚未完全解决。 早些时候，我们在GA眼的RPE中发现了有毒的非编码Alu RNA的特定积累，其结果是 由于DICER1的缺陷(自然，2011)，它通过激活规范的 Caspase-1炎症体(细胞2012)。最近，我们阐明了协调这一过程的信号交响乐 细胞毒性：DICER1的破坏：Alu RNA动态平衡调节导致非典型炎症体 激活，caspase-4/11和一种新的非裂解Gasdermin D(GSDMD)介导的分子级联反应- 依赖于caspase-1的激活和IL-18的分泌(自然医学，2018)。增强了这些方面的水平 在人类GA中也发现了分子，这标志着它是第一种与之相关的非传染性人类疾病 非典型性炎症性肿块。结合我们令人兴奋的初步数据，淀粉样蛋白β，另一个 RPE变性的触发，也激活了非典型炎症小体，这些发现表明 非典型炎症体可能是多种毒性信号的集合体，导致GA的RPE变性。 鉴于炎症小体对无数细胞危难的触发因素做出反应，它可能代表着一个危急的 触发细胞死亡的检查点，因此是阻止RPE退化的有吸引力的靶点。然而，我们 对于GA中炎性小体的激活，以及它如何导致RPE变性，目前还缺乏完整的认识。 对这些机制的严格定义对于加强我们对分子驱动因素的理解至关重要。 这是GA的标志，并致力于开发合理的治疗方法。我们将提供新的功能洞察，了解 调节失调的非典型炎症体激活通过以下途径促进RPE退变 主题整合而又独立的目标：(1)创建非规范炎症的空间地图 (2)确定Gasdermin D(GSDMD)在非典型性炎症中的作用 激活；(3)确定靶向非典型炎症体途径是否改善RPE 急性和慢性动物模型的退行性变。这些研究将阐明分子的新方面。 和RPE变性的生化基础，并帮助验证分子靶向策略 转化为临床试验。因此，这项建议与NEI的视网膜疾病五年目标是一致的 计划战略计划。

Geographic atrophy (GA), an advanced form of age-related macular degeneration (AMD), is a major global cause of blindness that affects more than 1 million Americans. Of the many pathological features that comprise GA, one of the cardinal hallmarks is degeneration of the retinal pigmented epithelium (RPE), which also is an FDA- accepted endpoint for registration clinical trials. GA remains an unmet medical need because, in large part, the mechanisms that promote RPE degeneration are not fully resolved. Earlier, we identified a specific accumulation of toxic non-coding Alu RNAs in the RPE of GA eyes that results from a deficiency in DICER1 (Nature 2011), which triggers RPE degeneration by activating the canonical caspase-1 inflammasome (Cell 2012). Recently, we elucidated the signaling symphony that orchestrates this cellular toxicity: disruption of DICER1:Alu RNA homeostatic regulation induces non-canonical inflammasome activation, a molecular cascade mediated by caspase-4/11 and a novel, non-lytic gasdermin D (GSDMD)- dependent activation of caspase-1 and secretion of IL-18 (Nature Medicine 2018). Enhanced levels of these molecules were also identified in human GA, marking it as the first non-infectious human disease associated with the non-canonical inflammasome. Combined with our exciting preliminary data that amyloid β, another trigger of RPE degeneration, also activates the non-canonical inflammasome, these findings suggest that the non-canonical inflammasome could be an integrator of multiple toxic signals that drive RPE degeneration in GA. Given that the inflammasome responds to myriad triggers of cellular distress, it could represent a critical checkpoint that triggers cell death, and therefore an attractive target for halting RPE degeneration. However, we still lack an integrated understanding of inflammasome activation in GA, and how it induces RPE degeneration. A rigorous definition of these mechanisms is crucial to enhancing our understanding of the molecular drivers of this hallmark of GA and to developing rational treatments. We will provide novel functional insights into how dysregulated non-canonical inflammasome activation contributes to RPE degeneration via the following thematically integrated yet independent Aims: (1) Create a spatial map of the non-canonical inflammasome pathway in human donor eyes; (2) Define the role of Gasdermin D (GSDMD) in non-canonical inflammasome activation; (3) Determine whether targeting the non-canonical inflammasome pathway ameliorates RPE degeneration in acute and chronic animal models. These studies will illuminate novel aspects of the molecular and biochemical bases of RPE degeneration, and help validate a molecular targeting strategy that could be translated into clinical trials. As such, this proposal is aligned with the 5-year goals of the NEI's Retinal Diseases Program strategic plan.