Division of Medical Genetics, Department of Pediatrics, Harbor-UCLA Medical Center and The Lundquist Institute, Torrance, California 90502, United States.
Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States.
Mol Pharm. 2021 Jan 4;18(1):214-227. doi: 10.1021/acs.molpharmaceut.0c00831. Epub 2020 Dec 15.
There is currently no cure or effective treatment available for mucopolysaccharidosis type IIID (MPS IIID, Sanfilippo syndrome type D), a lysosomal storage disorder (LSD) caused by the deficiency of α--acetylglucosamine-6-sulfatase (GNS). The clinical symptoms of MPS IIID, like other subtypes of Sanfilippo syndrome, are largely localized to the central nervous system (CNS), and any treatments aiming to ameliorate or reverse the catastrophic and fatal neurologic decline caused by this disease need to be delivered across the blood-brain barrier. Here, we report a proof-of-concept enzyme replacement therapy (ERT) for MPS IIID using recombinant human α--acetylglucosamine-6-sulfatase (rhGNS) intracerebroventricular (ICV) delivery in a neonatal MPS IIID mouse model. We overexpressed and purified rhGNS from CHO cells with a specific activity of 3.9 × 10 units/mg protein and a maximal enzymatic activity at lysosomal pH (pH 5.6), which was stable for over one month at 4 °C in artificial cerebrospinal fluid (CSF). We demonstrated that rhGNS was taken up by MPS IIID patient fibroblasts the mannose 6-phosphate (M6P) receptor and reduced intracellular glycosaminoglycans to normal levels. The delivery of 5 μg of rhGNS into the lateral cerebral ventricle of neonatal MPS IIID mice resulted in normalization of the enzymatic activity in brain tissues; rhGNS was found to be enriched in lysosomes in MPS IIID-treated mice relative to the control. Furthermore, a single dose of rhGNS was able to reduce the accumulated heparan sulfate and β-hexosaminidase. Our results demonstrate that rhGNS delivered into CSF is a potential therapeutic option for MPS IIID that is worthy of further development.
目前，对于黏多糖贮积症 IIID（MPS IIID，Sanfilippo 综合征 D 型），即由于α--乙酰氨基葡萄糖-6-硫酸酯酶（GNS）缺乏引起的溶酶体贮积症（LSD），尚无有效的治疗方法。MPS IIID 的临床症状与其他 Sanfilippo 综合征亚型相似，主要局限于中枢神经系统（CNS），任何旨在改善或逆转这种疾病引起的灾难性和致命性神经衰退的治疗方法都需要跨越血脑屏障。在这里，我们报告了使用重组人α--乙酰氨基葡萄糖-6-硫酸酯酶（rhGNS）经脑室内（ICV）给药在新生 MPS IIID 小鼠模型中进行 MPS IIID 的酶替代疗法（ERT）的概念验证。我们从 CHO 细胞中过表达和纯化 rhGNS，其比活性为 3.9×10 单位/mg 蛋白，在溶酶体 pH（pH 5.6）下具有最大酶活性，在 4°C 下在人工脑脊液（CSF）中稳定保存一个月以上。我们证明 rhGNS 被 MPS IIID 患者成纤维细胞摄取，通过甘露糖 6-磷酸（M6P）受体，并将细胞内糖胺聚糖降低至正常水平。将 5μg rhGNS 递送到新生 MPS IIID 小鼠的侧脑室中，可使脑组织中的酶活性正常化；与对照相比，rhGNS 在 MPS IIID 治疗的小鼠中发现富集在溶酶体中。此外，单次给予 rhGNS 能够减少累积的硫酸乙酰肝素和β-己糖胺酶。我们的结果表明，递送到 CSF 中的 rhGNS 是 MPS IIID 的一种潜在治疗选择，值得进一步开发。
