Substrate reduction therapy using Genz-667161 reduces levels of pathogenic components in a mouse model of neuronopathic forms of Gaucher disease. Substrate reduction therapy using Genz-667161 reduces levels of pathogenic components in a mouse model of neuronopathic forms of Gaucher disease

Most lysosomal storage diseases (LSDs) have a significant neurological component, including types 2 and 3 Gaucher disease (neuronal forms of Gaucher disease; nGD). No therapies are currently available for nGD since the recombinant enzymes used in the systemic form of Gaucher disease do not cross the blood-brain barrier. However, a number of promising approaches are currently being tested, including substrate reduction therapy (SRT), in which partial inhibition of the synthesis of the glycosphingolipids (GSLs) that accumulate in nGD lowers their accumulation. We now induce nGD in mice by injection with conduritol B-epoxide (CBE), an irreversible inhibitor of acid beta-glucosidase (GCase), the enzyme defective in nGD, with or without co-injection with GZ-667161, a prototype for SRT. Significant neuropathology, and a reduction in lifespan, was observed upon CBE injection, and this was largely reversed by co-injection with GZ-667161, along with a reduction in glucosylceramide and glucosylsphingosine levels. Analysis of gene expression by RNAseq revealed that GZ-667161 largely reversed the changes in genes and pathways that were differentially-expressed upon CBE injection, specifically pathways of GSL metabolism, lipoproteins and other lipid metabolic pathways, lipid droplets, astrocyte activation, neuronal function, and to some extent, neuroinflammation. Together, this demonstrates the efficacy of SRT to reverse the effects of substrate accumulation on pathological components and pathways in nGD brain. Overall design: Brain homogenates from control mice (PBS), CBE injected mice and CBE+GZ-667161 injected mice

大多数溶酶体贮积症（lysosomal storage diseases, LSDs）均存在显著的神经系统受累表现，其中包括2型及3型戈谢病（Gaucher disease），即神经型戈谢病（neuronal forms of Gaucher disease, nGD）。目前针对神经型戈谢病尚无获批治疗手段：用于系统性戈谢病的重组酶无法透过血脑屏障（blood-brain barrier）。尽管如此，目前已有多种颇具前景的治疗策略正处于临床试验阶段，其中包括底物减少疗法（substrate reduction therapy, SRT）——该疗法通过部分抑制在神经型戈谢病中异常蓄积的糖鞘脂（glycosphingolipids, GSLs）的合成，以降低其组织内的蓄积水平。本研究通过向小鼠注射环氧康迪托耳B（conduritol B-epoxide, CBE）——一种酸性β-葡糖苷酶（acid beta-glucosidase, GCase）的不可逆抑制剂，而该酶正是神经型戈谢病的缺陷酶——并联合或不联合注射底物减少疗法的原型药物GZ-667161，成功构建了神经型戈谢病小鼠模型。研究观察到，单独注射CBE可导致小鼠出现显著的神经病理损伤，并缩短其生存期；而联合注射GZ-667161可显著逆转上述病理改变，同时降低小鼠脑内葡糖基神经酰胺（glucosylceramide）与葡糖基鞘氨醇（glucosylsphingosine）的水平。通过RNA测序（RNAseq）分析基因表达谱发现，GZ-667161可大体逆转CBE注射所诱导的差异表达基因及通路异常，具体涉及糖鞘脂代谢、脂蛋白及其他脂质代谢通路、脂滴、星形胶质细胞活化（astrocyte activation）、神经元功能，以及一定程度的神经炎症（neuroinflammation）通路。综上，本研究证实了底物减少疗法可有效逆转底物蓄积对神经型戈谢病大脑内病理改变及通路异常的影响。实验整体设计：取自对照组（PBS注射）小鼠、单独CBE注射小鼠及联合CBE+GZ-667161注射小鼠的脑组织匀浆。