Targeted replacement of defective lysosomal enzymes in the lung and brain

尽管发病率很低，但遗传疾病给家庭和卫生系统带来的经济负担极高，因为治疗费用(100,000美元/病人年)在缓解这些慢性病方面大多不是最理想的。这就是酶替代疗法(ERT)治疗溶酶体储存障碍(LSD)的情况，LSD是由于溶酶体酶缺乏而导致的普遍遗传缺陷。ERT的成功仅限于少数影响肝、脾和肾的疾病，在这些疾病中，注射的酶通过血液清除机制获得进入。然而，由于缺乏亲和力和酶在组织中的运输，ERT传递到肺或大脑(对于大多数常见的神经系统LSD)是受阻的。一个例子是由于酸性鞘磷脂酶(ASM)缺乏而导致的尼曼-皮克病(NPD)的ERT，其中溶酶体过量的鞘磷脂会导致严重的神经功能障碍(A型表型)，并影响肺、肝和脾(B型表型)。我们的目标是制定战略，改善ERT对疾病部位(肺和脑)的传递。我们建议靶向ASM的细胞间黏附分子-1(ICAM-1)表达于所有器官的内皮和组织实质中的细胞靶点，并在NPD中上调。我们的结果表明，在NPD中，与囊泡从血液到组织和细胞表面到溶酶体的运输有关的经典内吞作用是有缺陷的，但在NPD中，通过多价抗ICAM/聚苯乙烯原型载体与ICAM-1结合而诱导的非经典途径完全活跃。这些原型增强了ASM对溶酶体的靶向性，并在培养的内皮细胞和小鼠中减少了鞘磷脂。一小部分抗ICAM原型载体通过内皮细胞培养进行运输。我们假设，生物相容的ICAM-1靶向载体可以通过内皮屏障(不影响通透性)提供ASM的囊泡运输，并在组织实质的细胞内内吞和溶酶体递送，从而减弱NPD肺和脑的表型。我们将在细胞和小鼠模型中测试这一点，使用我们的新型生物兼容PLGA载体，通过其天然配体衍生的多肽靶向ICAM-1，旨在评估和优化：1-跨内皮细胞转运的有效性和安全性，2-非内皮细胞转运，以及3-NPD表型的影响。这种将治疗药物跨越内皮屏障进入细胞的策略的好处可能超过其他LSD和CNS治疗。

Despite a low incidence, the economical burden of genetic diseases to families and the health system is extremely high, due to the cost of therapies ($100,000/patient-year) mostly suboptimal in alleviating these chronic conditions. This is the case for enzyme replacement therapies (ERTs) for treatment of lysosomal storage disorders (LSDs), prevalent genetic defects due to deficiency of lysosomal enzymes. ERT success is restricted to a few diseases affecting liver, spleen, and kidneys, where injected enzymes gain access via mechanisms of blood clearance. However, ERT delivery to the lungs, or brain for most common neurological LSDs, is hindered by the lack of affinity and transport of the enzymes to and into tissues. An example is ERT for Niemann-Pick disease (NPD) due to acid sphingomyelinase (ASM) deficiency, where lysosomal excess of sphingomyelin causes strong neurological disorder (type A phenotype) and affects lungs, liver and spleen (type B phenotype). Our goal is to develop strategies to improve ERT delivery to disease sites (lungs and brain). We propose to target ASM to intercellular adhesion molecule-1 (ICAM-1) expressed on the endothelium of all organs and cell targets in the parenchyma of tissues, and up-regulated in NPD. Our results indicate that classical endocytosis associated to vesicular transport from the blood to the tissue and the cell surface to lysosomes are defective in NPD, yet the non-classical pathway induced by ICAM-1 engagement by multivalent anti-ICAM/polystyrene prototype carriers is fully active in NPD. These prototypes enhance ASM targeting to lysosomes and sphingomyelin reduction in cultured endothelial cells and mice. A fraction of anti-ICAM prototype carriers are transported across endothelial cultures. We hypothesize that biocompatible ICAM-1- targeted carriers can provide vesicular transport of ASM across endothelial barriers (without affecting permeability) and endocytosis and lysosomal delivery in cells of the tissue parenchyma, attenuating NPD lung and brain phenotype. We will test this in cells and mouse models, using our new biocompatible PLGA carriers targeted to ICAM-1 by a peptide derived from its natural ligand, in Aims to evaluate and optimize: 1-Efficacy and safety of transendothelial transport, 2-Non-endothelial delivery, and 3-Effects in the NPD phenotype. The benefits of this strategy to transport therapeutics across endothelial barriers and into cells may transcend other LSDs and CNS treatments.