Mechanisms of Substrate Reduction Therapy for Niemann-Pick C Disease

描述（由申请方提供）：C型尼曼-匹克（NPC）病是一种胆固醇-鞘糖脂（GSL）溶酶体贮积症，最常见的原因是NPC 1缺陷，NPC 1是一种跨膜蛋白，被认为在从溶酶体逆向内吞转运底物中起关键作用。大多数受影响的儿童在出生时表现正常，在早年发展为进行性神经系统疾病，并在第二个十年死亡。我们率先开发了两种治疗这种疾病的化合物。第一种，N-丁基脱氧野尻霉素（NB-DNJ）或麦格司他是一种记录在案的GSL合成抑制剂，而第二种，羟丙基-环糊精（HPBCD）是FDA批准的用于药物溶解的辅料。在NPC 1疾病的小鼠模型中，这两种化合物在延迟神经系统疾病的发作和延长生命（分别延长25%和100%）方面是有效的。然而，这两种药物都没有被理解为其有效性负责的确切机制。对于麦格司他，Npc 1小鼠经口给药后神经节苷脂蓄积持续减少的证据缺乏。类似地，对于HPBCD，虽然在Npc 1小鼠中治疗后胆固醇和GSL储存都大幅减少，但这种益处的机制完全未知，甚至对其穿过血脑屏障的能力仍存在争议。该提案将采用当前和新型试剂和动物模型进行一系列补充性体内和体外研究，以及定量高分辨率成像，生化和遗传评估，每一项都针对NPC疾病的治疗机制。我们的前两个目的是精确定义HPBCD减少神经元中胆固醇/GSL蓄积的作用机制，并严格重新检查和评估麦格司他减少GSL合成的能力，作为其对神经元存活产生有益影响的基础。我们的第三个目标是使用无偏见的基因分析方法来探索每种药物影响的全部代谢途径。利用在这些目标中吸取的经验教训，新的组合治疗策略将在第四个目标中进行测试，作为大幅改善NPC疾病儿童治疗的一种手段。

DESCRIPTION (provided by applicant): Niemann-Pick type C (NPC) disease is a cholesterol-glycosphingolipid (GSL) lysosomal storage disorder caused most commonly by defects in NPC1, a transmembrane protein believed critical in retroendocytic trafficking of substrates from lysosomes. Most affected children appear normal at birth, develop progressive neurological disease in their early years and die in their second decade. We have pioneered the development of two compounds for this disorder. The first, N-butyldeoxynojirimycin (NB-DNJ) or miglustat is a documented inhibitor of GSL synthesis, whereas the second, hydroxypropyl ¿-cyclodextrin (HPBCD), is an FDA-approved excipient used for drug solublization. Both compounds are efficacious in delaying onset of neurological disease and prolonging life (by 25% and 100%, respectively) in the mouse model of NPC1 disease. Yet neither drug is understood in terms of the precise mechanism responsible for its effectiveness. For miglustat, evidence for sustained reductions in ganglioside storage following oral administration to Npc1 mice is lacking. Similarly, for HPBCD, while both cholesterol and GSL storage are substantially reduced following treatment in Npc1 mice, the mechanism underlying this benefit is completely unknown, and indeed controversy continues even over its ability to cross the blood brain barrier. This proposal will carry out a series of complementary in vivo and in vitro studies employing current and novel reagents and animal models, and quantitative high-resolution imaging, biochemical and genetic evaluations, each directed at treatment mechanisms for NPC disease. Our first two aims are to precisely define HPBCD's mechanism of action in reducing cholesterol/GSL storage in neurons and to critically re-examine and assess miglustat's ability to reduce GSL synthesis as a basis for its beneficial impact on neuron survival. Our third aim uses an unbiased gene analysis approach to explore the full range of metabolic pathways impacted by each drug. Capitalizing on lessons learned in these aims, new combinatorial treatment strategies will be tested in the fourth aim as a means to substantially improve therapy for children with NPC disease.