Immunoproteasome inhibitors for the treatment of Alzheimer’s disease

项目摘要 到目前为止，几乎所有AD药物的临床试验都失败了，识别出一类新的药物 候选人已经成为带来有效的AD疗法的当务之急。一个主要的障碍是缺乏 前景看好的新药靶点与导致淀粉样β蛋白(Aβ)和Tau-2积聚的事件无关 蛋白。我们最近报道了针对免疫蛋白酶体(IP)的线性多肽环氧酮，以及 20S结构性蛋白酶体(CP)的可诱导变异体，可能代表了一类新的AD药物，可以 改善认知缺陷，不依赖于Aβ或tau的积累。在显示良好疗效的同时， 然而，这些线性多肽环氧酮在AD临床上的应用前景目前似乎有限， 由于大脑可及性差、体内代谢不稳定和循环时间短等潜在问题 (主要归因于ABCB1介导的药物在血脑屏障的外流以及多肽酶和 环氧化物水解酶)。然而，环氧酮多肽家族(C-末端α‘，β短肽)-环氧酮 弹头)仍然是有吸引力的候选药物，因为他们的药物赋予了他们 已证实的蛋白酶体靶标特异性和临床长期安全性。 我们目前的发现表明，一些含有大环的环氧酮多肽家族成员 抵抗ABCB1介导的外流和代谢稳定性的能力优于它们的线性对应者，以及 有可能成为AD患者的一种有意义的新疗法。我们在此应用程序中的目标是识别 并表征其中一种最适合在体内抑制大脑IP的大环化合物，并继续进行 药物开发的下一阶段。为了做到这一点，在目标1中，我们将准备当前几组有希望的大环 具有不同结构特征的具有类似靶标抑制和生物学特性的多肽环氧酮 在体外和纤维素中的活性以克为单位。在目标2中，我们将在体内表征每个大环的性质 多肽环氧酮，以确定一个先导候选药物。在目标3中，我们将在体内验证疗效和建议的 先导候选药物IP抑制→(NLRP3炎症小体)→抑制的作用机制 小胶质细胞IL-1α释放→阻断星形胶质细胞转化(向A1亚型)→神经元存活] AD小鼠模型(APP/PS1和PS19 tau转基因小鼠)。完成拟议的研究后，我们将拥有 确定了一位具备最佳IND能力研究和新颖行动模式的主要候选人。这些 预计结果将产生重要的积极影响，通过检查以前未开发的 IP靶向治疗AD可能为AD药物开发提供新的方向。

Project Summary With the failure of nearly all clinical trials for AD drugs in the pipeline to date, identification of a new class of drug candidates has become imperative to bring about effective AD therapies. A major obstacle is the lack of promising new drug targets unrelated to the events leading to the accumulation of the amyloid-beta (Aβ) and tau- protein. We recently reported that linear peptide epoxyketones targeting the immunoproteasome (iP), an inducible variant of the 20S constitutive proteasome (cP), may represent a new class of AD drugs that can ameliorate cognitive deficits, independently of Aβ or tau accumulation. While displaying promising efficacy, however, the prospect of these linear peptide epoxyketones for clinical use in AD appears limited at this time, due to potential issues of having a poor brain accessibility, in vivo metabolic instability, and short circulation time (largely attributable to the ABCB1-mediated drug efflux at the BBB and enzymatic hydrolysis by peptidases and epoxide hydrolases). Yet, the family of peptide epoxyketones (‘short peptides with C-terminal α′,β′-epoxyketone warhead’) remain attractive drug candidates considering their pharmacological advantages conferred by their proven target specificity for the proteasomes and long-term safety in the clinic. Our current findings reveal that some of the peptide epoxyketone family members containing a macrocycle have the ability to resist the ABCB1-mediated efflux and metabolic stability superior to their linear counterparts, and the potential to be a meaningful new treatment for patients with AD. Our objective in this application is to identify and characterize one of these macrocyclic compounds best suited for brain iP inhibition in vivo and proceed to the next phase of drug development. To do this, in aim 1 we will prepare the current sets of promising macrocyclic peptide epoxyketones with different structural features that displayed comparable target inhibition and biological activity in vitro and in cellulo on a gram scale. In aim 2, we will characterize in vivo properties of each macrocyclic peptide epoxyketone to identify a lead drug candidate. In aim 3, we will verify in vivo efficacy and the proposed mechanism of action of the lead drug candidate [iP inhibition → (NLRP3 inflammasome) → suppression of microglial IL-1α release → blockade of astrocytes transformation (to A1 subtype) → neuronal survival] using two mouse models of AD (APP/PS1 and PS19 tau transgenic mice). By completing the proposed study, we will have identified a lead candidate with the best attributes for IND enabling studies and novel mode of action. These results are expected to have an important positive impact by examining the validity of the previously untapped iP-targeting approach for AD therapy and potentially offering a new direction for AD drug discovery.