Targeted replacement of defective lysosomal enzymes in the lung and brain

尽管发病率很低，但遗传性疾病给家庭和卫生系统带来的经济负担非常高，因为治疗费用（每患者每年10万美元）在缓解这些慢性疾病方面大多达不到最佳水平。这就是酶替代疗法（ERTs）治疗溶酶体贮积症（lsd）的情况，lsd是由于溶酶体酶缺乏引起的普遍遗传缺陷。ERT的成功仅限于影响肝脏、脾脏和肾脏的少数疾病，在这些疾病中，注射的酶通过血液清除机制进入。然而，对于大多数常见的神经性lsd来说，ERT向肺部或大脑的传递受到缺乏亲和力和酶进入组织的运输的阻碍。一个例子是由于酸性鞘磷脂酶（ASM）缺乏导致的尼曼-皮克病（NPD）的ERT，其中溶酶体鞘磷脂过量导致强烈的神经系统疾病（A型表型），并影响肺、肝和脾（B型表型）。我们的目标是制定策略来改善ERT对疾病部位（肺和脑）的递送。我们建议将ASM定位于细胞间粘附分子-1 (ICAM-1)， ICAM-1表达于所有器官的内皮和组织实质的细胞靶点，并在NPD中上调。我们的研究结果表明，与从血液到组织和细胞表面到溶酶体的囊泡运输相关的经典内噬作用在NPD中是缺陷的，而由多价抗icam /聚苯乙烯原型载体参与ICAM-1诱导的非经典途径在NPD中是完全活跃的。在培养的内皮细胞和小鼠中，这些原型增强了ASM对溶酶体的靶向性和鞘磷脂的减少。一小部分抗icam原型载体在内皮细胞培养物中运输。我们假设生物相容性的ICAM-1靶向载体可以提供ASM的囊泡运输，跨越内皮屏障（不影响渗透性），并在组织实质细胞中内吞和溶酶体递送，从而减弱NPD肺和脑表型。我们将在细胞和小鼠模型中测试这一点，使用我们新的生物相容性PLGA载体，通过天然配体衍生的肽靶向ICAM-1，目的是评估和优化：1-跨内皮运输的有效性和安全性，2-非内皮输送，3- NPD表型的影响。这种通过内皮屏障转运药物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.