cGAS inhibitors for Alzheimer's disease treatment

摘要 阿尔茨海默病(AD)是老年人最常见的痴呆症。淀粉样蛋白-β(Aβ)与tau病理 和神经炎症是阿尔茨海默病的三个主要特征。绝大多数的药物发现 在过去的几十年里，人们的努力集中在针对Aβ病理的研究上，但没有一项在临床试验中成功。 虽然tau病理，而不是Aβ病理，已经出现在AD记忆减退的关键作用，药物 针对tau对神经元的直接影响的研究也没有取得成功。引人注目的人类基因研究 将先天免疫反应与迟发性阿尔茨海默病风险增加联系起来，支持靶向小胶质细胞， 大脑中的常驻免疫细胞，作为治疗AD的下一代药物。我们展示了一个关键的角色 环GMP-AMP合成酶-干扰素基因刺激物信号转导在小胶质细胞毒性和 Tau介导的认知功能下降。激活cGAS，一个主要的胞质dsDNA传感器，催化产生 CGAMP是一种非常有效的刺痛激动剂，作为激活cGAS-刺痛途径的第二信使， 通过激活干扰素调节因子(IRF)产生抗病毒反应 细胞因子和I型干扰素基因的表达。我们发现部分或完全的遗传性cGAS消融 对tau介导的PS19Tau小鼠的空间学习和记忆缺陷具有保护作用。此外，治疗 使用cGAS小分子抑制剂可减少干扰素反应，减少小胶质细胞增生，并受到保护 抗阿尔茨海默病小鼠模型中的认知缺陷。我们假设抑制cGAS活性 将抑制神经炎症和适应不良免疫反应，保护AD相关缺陷。我们 建议开发小分子人cGAS(h-cGAS)抑制剂作为治疗AD的新型小胶质细胞调节剂。 在目标1中，我们将开发先导h-cGAS抑制剂，从两种已知的药物开始，并确定这些药物是否 在无细胞和基于细胞的检测中，抑制剂有效地调节cGAS-STING途径。我们希望能确定 新的命中通过命中扩展和合成&gt；200类比。目标2侧重于优化有效的类比 CGAS抑制剂，TDI-6570，是一种铅低纳摩尔效力的小鼠cGAS(m-cGAS)抑制剂，具有 H-cGAS活性降低10倍。我们将设计多达50个新的类似物。合成孔径雷达、对接试验和对接试验结果 将使用电子计算来最大限度地提高引线质量。完成目标1和目标2将领先5 用于体内和功效研究的化合物。在目标3中，我们将建立h-cGAS抑制剂的PK和疗效 自闭症小鼠模型的建立及其对人干细胞来源的小胶质细胞和脑器官的疗效 紧张症。在拟议的5年研究结束时，我们预计将确定1-2先导h-cGAS抑制剂作为工具。 化合物和作为治疗阿尔茨海默病的候选药物进一步发展的原则证明 相关的神经性疾病。

ABSTRACT Alzheimer's disease (AD) is the most common form of dementia in elderly. Amyloid-β (Aβ) and tau pathologies and neuroinflammation are three major hallmarks of Alzheimer's disease. Vast majority of the drug discovery efforts in the past decades have focused on targeting the Aβ pathology, but none are successful in Clinical Trials. While tau pathology, not the Aβ pathology, has emerged to play critical role in memory decline in AD, drugs targeting the direct effects of tau on neurons also have not met success either. Compelling human genetic studies link the innate immune responses to elevated risk of developing late-onset AD, supporting targeting microglia, resident immune cells in the brain, as the next-generation treatment for AD. We showed that a critical role of cyclic GMP-AMP synthase (cGAS)-Stimulator of interferon genes (STING) signaling in microglial toxicity and tau-mediated cognitive decline. Activation of cGAS, a major cytosolic dsDNA sensor, catalyzes production of cGAMP, an extremely potent STING agonist as the second messenger that activates cGAS-STING pathway, leading to a production of the antiviral responses through activation of interferon regulatory factors (IRFs) and expression of cytokine and type I interferon genes. We found that a partial or complete genetic cGAS ablation protected against the tau-mediated spatial learning and memory deficits in PS19 Tau mice. Moreover, treatment with a small molecule inhibitor of cGAS reduces interferon responses, diminished microgliosis, and protected against cognitive deficits in an AD mouse model with tauopathy. We hypothesize that inhibitors the cGAS activity will dampen neuroinflammation and maladaptive immune responses, protect against AD-related deficit. We propose to develop small molecule human cGAS (h-cGAS) inhibitors as novel microglial modulators to treat AD. In Aim 1, we will develop lead h-cGAS inhibitors starting with two known hits and determine whether these inhibitors effectively modulate the cGAS-STING pathway in cell-free and cell-based assays. We expect to identify new hits via hits expansion and synthesize >200 analogs. Aim 2 focuses on optimization of analogs a potent cGAS inhibitor, TDI-6570, which is a lead low nanomolar potent mouse cGAS (m-cGAS) inhibitor and possesses 10x less h-cGAS activity. We will design up to 50 new analogs. Results of SAR, docking experiments, and in- silico calculation will be used to maximize the lead quality. Completion of Aim 1 and Aim 2 will lead to 5 lead compounds for in vivo and efficacy studies. In Aim 3, we will establish PK and efficacy of h-cGAS inhibitors in mouse model of tauopathy, and efficacy in human stem cell-derived microglia and cerebral organoids with tauopathy. At the end of the proposed 5 years study, we anticipate identifying 1-2 lead h-cGAS inhibitors as tool compounds and a proof of principle to further advance as drug candidates to treat Alzheimer's disease and related neurological disorders.