Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
Proc Natl Acad Sci U S A. 2013 Feb 19;110(8):2999-3004. doi: 10.1073/pnas.1222742110. Epub 2013 Feb 4.
To realize the potential of large molecular weight substances to treat neurological disorders, novel approaches are required to surmount the blood-brain barrier (BBB). We investigated whether fusion of a receptor-binding peptide from apolipoprotein E (apoE) with a potentially therapeutic protein can bind to LDL receptors on the BBB and be transcytosed into the CNS. A lysosomal enzyme, α-L-iduronidase (IDUA), was used for biological and therapeutic evaluation in a mouse model of mucopolysaccharidosis (MPS) type I, one of the most common lysosomal storage disorders with CNS deficits. We identified two fusion candidates, IDUAe1 and IDUAe2, by in vitro screening, that exhibited desirable receptor-mediated binding, endocytosis, and transendothelial transport as well as appropriate lysosomal enzyme trafficking and biological function. Robust peripheral IDUAe1 or IDUAe2 generated by transient hepatic expression led to elevated enzyme levels in capillary-depleted, enzyme-deficient brain tissues and protein delivery into nonendothelium perivascular cells, neurons, and astrocytes within 2 d of treatment. Moreover, 5 mo after long-term delivery of moderate levels of IDUAe1 derived from maturing red blood cells, 2% to 3% of normal brain IDUA activities were obtained in MPS I mice, and IDUAe1 protein was detected in neurons and astrocytes throughout the brain. The therapeutic potential was demonstrated by normalization of brain glycosaminoglycan and β-hexosaminidase in MPS I mice 5 mo after moderate yet sustained delivery of IDUAe1. These findings provide a noninvasive and BBB-targeted procedure for the delivery of large-molecule therapeutic agents to treat neurological lysosomal storage disorders and potentially other diseases that involve the brain.
为了实现大分子量物质治疗神经紊乱的潜力，需要采用新方法来克服血脑屏障（BBB）。我们研究了将载脂蛋白 E（apoE）的受体结合肽与潜在治疗性蛋白融合，是否可以与 BBB 上的 LDL 受体结合，并被转胞吞进入中枢神经系统。溶酶体酶α-L-艾杜糖苷酸酶（IDUA）被用于黏多糖贮积症（MPS）I 型的小鼠模型中的生物学和治疗评估，这是最常见的溶酶体贮积症之一，伴有中枢神经系统缺陷。我们通过体外筛选鉴定了两个融合候选物 IDUAe1 和 IDUAe2，它们表现出理想的受体介导结合、内吞作用和跨内皮转运，以及适当的溶酶体酶转运和生物学功能。通过短暂的肝表达产生的强大的外周 IDUAe1 或 IDUAe2 导致在毛细血管耗竭、酶缺乏的脑组织中酶水平升高，并在治疗后 2 天内将蛋白递送至非内皮周细胞、神经元和星形胶质细胞内。此外，在长期给予来自成熟红细胞的中等水平 IDUAe1 后 5 个月，MPS I 小鼠中获得了 2%至 3%的正常大脑 IDUA 活性，并且在整个大脑中都检测到了 IDUAe1 蛋白。在中等但持续给予 IDUAe1 5 个月后，MPS I 小鼠的脑糖苷和β-己糖胺酶得到正常化，证明了该治疗方法的潜力。这些发现为大分子量治疗剂的非侵入性和 BBB 靶向递送提供了一种方法，可用于治疗神经溶酶体贮积症，以及可能涉及大脑的其他疾病。
