CGT and ACD Inhibitors for SRT Treatment of Krabbe Disease

摘要 Krabbe病(KD)是由普遍表达的溶酶体酶缺乏引起的。 半乳糖神经酰胺酶(GALC)，负责降解半乳糖神经酰胺和 半乳糖鞘氨醇(神经素)。因为通向精神药物的合成途径不受 Kd，精神素在Krabbe神经系统中不断产生和积累。有毒的水平 精神药物被认为是疾病的主要致病诱因。目前，KD的护理标准是 造血干细胞移植(HSCT)仅适用于无症状或早期症状 婴儿型KD病例，仅久病不愈。用腺相关病毒进行临床前基因治疗研究 (AAV)载体显示出巨大的前景，事实上，在生命早期应用AAV基因治疗可以提高存活率， 改善抽动小鼠(Twitcher，KD的天然模型)的生活质量，减少神经病理改变。基座 在这些重要的成功方面，基于AAV的基因治疗的临床试验仅开始用于婴儿KD。 然而，尽管预防了重大的疾病相关缺陷，但造血干细胞移植和临床前AAV基因 治疗试验表明，神经疾病的长期疗效和复发情况各不相同。 因此，KD的基因治疗的现状，HSCT主要治疗症状前婴儿的局限性 KD和青少年和成人发病KD患者的事实，这涵盖了Krabbe的很大一部分 大部分患者仍未接受任何治疗，他们强调需要制定更多的策略来维持 对KD患者的长期保护。使用底物减少疗法(SRT)策略，单独或 结合目前和新的治疗KD的方法，是实现这一目标的一个潜在途径。在此应用程序中，我们将 使用两种选择性抑制神经酰胺半乳糖基转移酶(CGT)和酸的新化合物 神经酰胺酶(ACD)，通过神经酰胺的半乳糖化和 鞘氨醇(CGT)和半乳糖基神经酰胺(ACD)的脱酰化。基于这样一个前提，即减少 精神药物的合成将在出生后早期预防/减少与精神药物相关的病理 哺乳动物大脑，我们将测试CGT和ACD的SRT对HSCT和AAV-GALC基因的增强作用 川崎病幼鼠模型的治疗及单药治疗的疗效 CGT或ACD抑制剂在一种新的成人型KD模型中改善/预防疾病。

SUMMARY Krabbe disease (KD) is caused by the deficiency of the ubiquitously expressed lysosomal enzyme galactosylceramidase (GALC) which is responsible for the degradation of galactosylceramides and galactosylsphingosine (psychosine). Because the synthetic pathway conducing to psychosine is not affected in KD, psychosine is continuously produced and accumulated in the Krabbe nervous system. Toxic levels of psychosine are considered the main pathogenic trigger of disease. Currently, the standard of care for KD is hematopoietic stem cell transplantation (HSCT), which is only applicable to asymptomatic or early symptomatic infantile KD cases and only protracts disease. Pre-clinical gene therapy studies using adeno-associated viral (AAV) vectors have shown great promise and in fact, AAV gene therapy applied early in life increases survival, improves quality of life, and decreases neuropathology in twitcher (twi) mice, the natural model for KD. Based on these important successes, AAV-based gene therapy clinical trials are being started only for infantile KD. However, despite the prevention of significant disease-related deficits, HSCT and pre-clinical AAV-gene therapy trials show varied long-term efficacy and resurgence of neurological disease. Thus, the status of gene therapy for KD, the limitations of HSCT to treat primarily presymptomatic infantile KD and the fact that juvenile and adult onset KD patients, which encompass a significant fraction of Krabbe patients, largely remain without any treatment, highlight the need to develop additional strategies to sustain long-term protection for KD patients. The use of substrate reduction therapies (SRT) strategies, singly or combined with current and new therapies for KD, is one potential way to achieve this. In this application we will use two small new compounds which selectively inhibit ceramide galactosyltransferase (CGT) and acid ceramidase (ACD), enzymes that mediate the production of psychosine via galactosylation of ceramides and sphingosine (CGT) and deacylation of galactosylceramide (ACD). Based on the premise that reducing psychosine synthesis will prevent/reduce psychosine-related pathology at early postnatal development of the mammalian brain, we will test the efficacy of SRT of CGT and ACD to enhance HSCT and AAV-GALC gene therapy in the mouse model of infantile KD (twitcher mouse) and the efficacy of single treatment with CGT or ACD inhibitors to ameliorate/prevent disease in a new model of adult-onset KD.