Kynurenine Pathway Regulation of CNS Senescence in Alzheimer's Disease Pathology

这是一份NOT-AG-22-025行政补充申请，基于我们的上级非 阿尔茨海默病(AD)奖R01(AG067510-01A1)，有可能提供初步数据证明 另一份以广告为重点的R01提交。我们最近发现并广泛发表了一个新时代-- 相关的机制，驱动骨骼内稳态的破坏，似乎也适用于AD。具体来说， 作为犬尿氨酸(KYN)途径一部分的膳食必需氨基酸色氨酸(Trp)的代谢物 (KP)是由氧化损伤和炎症因子产生的。我们已经证明，增加的水平 Kyn和其他KP代谢物在体外和体内，阻止自噬，并诱导干细胞衰老， 单核细胞，以及破坏细胞和组织功能的成骨/肌肉细胞。衰老开始出现了 被认为是AD发病机制中的关键效应因子。关键是，我们有初步数据显示ROS和 炎症因素导致星形胶质细胞和小胶质细胞的衰老，更重要的是，KYN对此产生负面影响 影响人类单核细胞来源的小胶质细胞，包括诱导衰老标志物。衰老 而肌肉骨骼组织中的衰老表型组织功能障碍可以通过阻断信号转导来挽救 初级KP代谢物受体芳香烃受体(AhR)的途径或通过抑制关键KP 产生KYN的吲哚胺2，3-双加氧酶(IDO)或犬尿氨酸单氧化酶(KMO)等酶 这会产生其他针对KP代谢物的CNS。我们建议确定以金伯利进程为目标的适用性 导致AD的致病衰老，部分最初使用快速(4-5个月)发展为AD的5xFAD模型 病理学。重要的是，在支持的临床试验中，有对AhR、IDO-1和KMO的药物抑制剂 快速评估潜在的AD治疗新方法。假设：衰老相关的氧化 应激/炎症导致KP介导的衰老细胞在大脑中积累，从而促进 通过加重淀粉样β蛋白(Aβ)诱导的神经毒性与AD的发病和进展 Tau病理，和/或直接通过衰老的中枢神经系统细胞功能障碍。来自该提案的初步数据 演示关键技术和概念方法的可行性将支持成功的AD R01 申请。目的1.论证对衰老标记物进行大规模Cytoff评估的可行性 与特定的细胞类型标记共定位。这是识别特定的KP模式的关键技术 中枢神经系统神经胶质细胞、内皮细胞自噬抑制及衰老的诱导和扩散 和神经细胞，或用KP酶抑制逆转其作用。AIM2.Kp引起的衰老的评估 可用于一年项目的AD鼠标模型(5xFAD)。5xFAD和控件将被处理 使用KP代谢物的子集或使用AhR、IDO-1或KMO抑制剂。这将确定年龄和 ROS/炎症产生的KP代谢物介导衰老和AD病理，如果抑制其 产生或信号阻断AD的进展，导致新的近期疗法。

This is a NOT-AG-22-025 Administrative Supplement application based on work derived from our Parent non- Alzheimer’s disease (AD) award R01 (AG067510-01A1), that has potential to provide preliminary data justifying a separate AD focused R01 submission. We have recently identified, and extensively published, on a novel age- related mechanism that drives a disruption in bone homeostasis that appears to also apply to AD. Specifically, metabolites of the diet derived essential amino acid tryptophan (TRP) as part of the Kynurenine (KYN) Pathway (KP) are generated by oxidative injury and inflammatory factors. We have shown that the increased levels of KYN and other KP metabolites in vitro, and in vivo, block autophagy, and induce senescence in stem cells, monocytes, and osteogenic/muscle cells disrupting cell and tissue function. Senescence is beginning to be recognized as a key effector in AD pathogenesis. Critically, we have preliminary data showing that ROS and inflammatory factors drive senescence in astrocytes and microglial cells, and importantly that KYN negatively affects human monocyte derived microglial cells including the induction of senescence markers. Senescence and the aging-phenotype tissue disfunction in musculoskeletal tissue can be rescued by blocking the signaling pathway for the primary KP metabolite receptor, the Aryl Hydrocarbon Receptor (AhR), or by inhibiting key KP enzymes such as indoleamine 2,3-dioxygenase (IDO) that generates KYN, or kynurenine monooxidase (KMO) that generates other CNS targeting KP metabolites. We propose to determine applicability of targeting the KP driven pathogenic senescence in AD, in part initially using 5xFAD model that rapidly (4-5 months) develops AD pathology. Importantly, there are pharmacological inhibitors to AhR, IDO-1 and KMO in clinical trials supporting rapid assessment of potential novel AD therapeutic approaches. Hypothesis: Aging-associated oxidative stress/inflammation leads to KP mediated accumulation of senescent cells in the brain, which promote the pathogenesis and progression of AD via exacerbating amyloid beta (Aβ)-induced neurotoxicity and tau pathology, and/or directly via senescent CNS cell dysfunction. Preliminary data from this proposal demonstrating feasibility of key technical and conceptual approaches will support a successful AD R01 application. Aim 1. Demonstrate the feasibility of a large scale CyTOFF assessment of senescent markers co-localized with specific cell type markers. This is a key technology to identify specific patterns of KP mediated inhibition of autophagy together with the induction and spread of senescence in CNS glial, endothelial and neuronal cells or its reversal with KP enzyme inhibition. Aim2. Assessment of KP driven senescence in an AD mouse model (5xFAD) that can be used in a single year project. 5xFAD and controls will be treated with a subset of KP metabolites or with AhR, IDO-1 or KMO inhibitors. This will establish if age and ROS/inflammation generated KP metabolites mediate senescence and AD pathologies, and if inhibition of their production or signaling blocks AD progression, leading to novel near-term therapeutics.