Combination Therapy, Biomarkers, and Imaging in Canine Krabbe Disease

 描述（由申请方提供）：克拉伯病（球状细胞脑白质营养不良）是一种遗传性神经退行性疾病，由半乳糖神经酰胺酶基因（GALC）突变引起，导致半乳糖脂蓄积、中枢和外周神经系统（CNS和PNS）髓鞘形成异常、少突胶质细胞和雪旺细胞死亡以及多核巨噬细胞（球状细胞）浸润。受影响的婴儿会出现认知能力下降和运动功能退化，通常在5岁之前死亡。目前在许多州进行新生儿克拉布病筛查，从而允许用造血干细胞移植（HPCT）治疗症状前婴儿，这是目前的护理标准。然而，虽然HPCT导致一些认知改善，但运动缺陷持续存在。目前还没有治愈克拉布病的方法。最近在Twitch小鼠（Krabbe病的鼠模型）中的研究表明，颅内注射携带野生型鼠GALC cDNA拷贝的腺相关病毒（AAV）载体与HPCT协同作用，可显著改善运动缺陷、存活时间和CNS病理学。虽然在治疗水平上有明显的前景，但在Twitch小鼠中观察到的联合治疗协同作用的机制尚不清楚。我们假设，在联合治疗中观察到的协同作用是由HPCT驱动的CNS效应和AAV介导的PNS基因治疗效应引起的。鼠和人Krabbe病之间疾病表型的差异以及小鼠的小尺寸限制了该模型的转化效用。相比之下，犬自然发生的Krabbe病再现了人类疾病的临床、病理和生化异常。此外，犬的大小与婴儿相似，可用于评价与婴儿相同的HPCT和CNS基因转移方法，并使用儿科诊所使用的方法鉴定和验证神经系统疾病严重程度和治疗有效性的临床、生化和成像标志物。拟议的研究将有助于确定联合治疗的协同作用机制，并将提供对疾病发病机制的深入了解，可能为未来设计其他治疗策略确定新的途径。我们的实验室非常适合在人类神经系统疾病的大型动物模型中评估实验疗法的机制效应。

 DESCRIPTION (provided by applicant): Krabbe disease (globoid cell leukodystrophy) is an inherited neurodegenerative disorder caused by mutations in the galactosylceramidase gene (GALC), leading to galactolipid accumulation, abnormal central and peripheral nervous system (CNS and PNS) myelination, oligodendrocyte and Schwann cell death, and the infiltration of multinucleated macrophages (globoid cells). Cognitive decline and motor deterioration develop in affected infants with death commonly occurring before the age of five. Newborn screening for Krabbe disease is currently performed in many states, thereby allowing for treatment of presymptomatic babies with hematopoietic stem-cell transplantation (HPCT), the current standard of care. However, while HPCT results in some cognitive improvement, motor deficits persist. There is no cure for Krabbe disease. Recent studies in the Twitcher mouse, a murine model of Krabbe disease, have shown that a combination of intracranial injection of an adeno-associated virus (AAV) vector carrying a wild type copy of murine GALC cDNA synergizes with HPCT to significantly improve motor deficits, survival time, and CNS pathology. Although clearly promising at a therapeutic level, the mechanisms responsible for the synergy of combination therapy observed in the Twitcher mouse are not understood. We hypothesize that the synergy observed with combination therapy results from HPCT-driven effects in the CNS effects and AAV-mediated gene therapy effects in the PNS. Differences in disease phenotype between murine and human Krabbe disease and the small size of the mouse limit the translational utility of this model. In contrast, naturally-occurring Krabbe disease in dogs recapitulates the clinical, pathological, and biochemical abnormalities of human disease. Additionally, the dog, similar in size to that of an infant, allows for the evaluation of HPCT and CNS gene transfer methods identical to those that can be used in infants, and for the identification and validation of clinicl, biochemical, and imaging markers of nervous system disease severity and therapeutic efficacy using methods that are used in pediatric clinics. The proposed studies will help determine the mechanism of the synergy seen with combination therapy, and will provide insight into disease pathogenesis, potentially identifying new pathways for future design of additional therapeutic strategies. Our lab is uniquely suited to evaluating the mechanistic effects of experimental therapies in large animal models of human nervous system disease.