Glycosphingolipids in Murine Neurodegenerative Diseases

描述(申请人提供)：研究目标是开发一种有效的神经节苷脂储存疾病的终身治疗方法。神经节苷脂增多症是一组不可治愈的常染色体隐性遗传性代谢性疾病，涉及神经节苷脂GM1或GM2在中枢神经系统溶酶体中的储存。GM1或GM2的积聚会导致广泛的炎症和神经变性。神经节苷脂GM1病是由于分解神经节苷脂GM1的酸性半乳糖苷酶的遗传缺陷引起的，而桑德霍夫病(SD)则是由于分解神经节苷脂GM2的氨基己糖苷酶亚基的遗传缺陷引起的。我们的研究将涉及疾病管理的多样化和互补性方法，主要涉及底物减少疗法和基因疗法。这些研究将主要在分别积累GM1和GM2的半乳糖和十六烷基硫酸酯小鼠身上进行。抑制合成抵消了分解代谢受损的速度，被称为底物减少疗法。亚氨基糖NB-DNJ和NB-DGJ以及新型PDMP类似物“3h”抑制神经鞘糖脂(GSL)的生物合成。我们最近的研究结果表明，当该抑制剂与受限的高脂肪、低碳水化合物生酮饮食(KD-R)联合使用时，NB-DNJ的中枢神经系统传递和治疗效果显著增加。腺相关病毒(AAV)基因治疗提供了缺失的溶酶体酶，从而减少了GSL在整个中枢神经系统的储存。拟议的研究将是在上一个供资期间进行的研究的延伸，并将涉及以下具体目标。目标1将研究限制生酮饮食(KD-R)促进大脑将亚氨基糖分和3h输送到中枢神经系统的主动和被动转运机制。目标2将确定生酮饮食可以在多大程度上促进亚胺糖和3h通过大坝的牛奶输送到新生小鼠的大脑。目的3将评估AAV基因治疗在多大程度上纠正储存疾病小鼠提纯的髓鞘、视神经和视网膜中的脂质异常和炎症。我们的初步研究首次显示，在人类SD和半乳糖/-小鼠和十六-/-小鼠的大脑中，不寻常的磷脂双(单酰甘油)磷酸水平升高。这种脂质将被用作一种新的生物标志物，用于纠正神经节苷脂的储存和脑部炎症。这项拟议的研究将为管理人类神经节苷脂储存疾病的新治疗策略提供见解。

DESCRIPTION (provided by applicant): The research goal is to develop an effective life-long therapy for ganglioside storage diseases. The gangliosidoses are a group of incurable autosomal recessive inborn errors of metabolism involving storage of either ganglioside GM1 or GM2 in CNS lysosomes. Accumulation of GM1 or GM2 causes wide spread inflammation and neurodegeneration. GM1 gangliosidosis arises from a genetic deficiency of the acid ¿-galactosidase that catabolizes ganglioside GM1, whereas Sandhoff disease (SD) arises from genetic deficiency in the ¿-hexosaminidase ¿ subunit that catabolizes ganglioside GM2. Our studies will involve diverse and complimentary approaches for disease management primarily involving substrate reduction therapy and gene therapy. The studies will be largely conducted in ¿-gal -/-, and Hex¿ -/- mice that accumulate GM1 and GM2, respectively. Inhibited synthesis counterbalances impaired rate of catabolism and is referred to as substrate reduction therapy. The imino sugars, NB-DNJ, and NB-DGJ, as well as the novel PDMP analogue "3h" inhibit the rate of glycosphingolipid (GSL) biosynthesis. Our recent findings show that CNS delivery and therapeutic efficacy of NB-DNJ is significantly increased when the inhibitor is administered together with the restricted high-fat, low carbohydrate ketogenic diet (KD-R). Adeno-Associated Virus (AAV) gene therapy provides the missing lysosomal enzyme thereby reducing GSL storage throughout the CNS. The proposed studies will be an extension of those conducted over the previous funding period and will involve the following specific aims. Aim 1 will examine active and passive transport mechanisms by which the restricted ketogenic diet (KD-R) facilitates brain delivery of imino sugar and 3h to the CNS. Aim 2 will determine the degree to which the ketogenic diet can facilitate delivery of imino sugar and 3h to neonatal mouse brain through the dam's milk. Aim 3 will evaluate the degree to which AAV gene therapy corrects lipid abnormalities and inflammation in purified myelin, optic nerve, and retina in storage disease mice. Our preliminary studies show for the first time elevated levels of the unusual phospholipid, bis(monoacylglycerol)phosphate in the brains of human SD and in the ¿-gal -/-, and Hex¿ -/- mice. This lipid will be used as a novel biomarker for correction of ganglioside storage and brain inflammation. The proposed research will provide insight on novel therapeutic strategies for managing human ganglioside storage diseases.