Testing a Novel DMD Therapeutic in MDX Mice

描述（由申请人提供）：已提出将肌营养蛋白的药理学上调作为治疗DMD的治疗策略。遗传学研究表明，肌营养不良蛋白表达的增加可以补偿mdx小鼠中肌营养不良蛋白的损失并纠正营养不良病理学。然而，用于utrophin上调的遗传方法在人类中尚不可行。双糖蛋白聚糖是一种细胞外蛋白，其是肌营养不良蛋白复合物的组分，并与α-肌营养不良蛋白聚糖结合（Bowe等人，2000），a -和？-肌聚糖（Rafii等人，2006年）。重组双糖蛋白聚糖蛋白可以在体内递送至肌肉，在那里它拯救双糖蛋白聚糖缺失小鼠中细胞内DAPC组分的肌膜表达（Mercado等人，2006年）。在所提出的研究中，我们将使用mdx小鼠来测试双糖链聚糖作为DMD治疗剂的潜在功效。在初步的实验中，我们已经表明，纯化的重组双糖蛋白聚糖蛋白全身递送给mdx小鼠上调utrophin表达，减少肌纤维死亡和单核细胞浸润。此外，治疗实用水平的单剂量有效长达三周。在拟定的研究中，我们将生产重组双糖链蛋白聚糖，并使用组织病理学标记物来确定其使用的最佳剂量、频率和给药途径。然后进行功能研究以确定双糖蛋白聚糖治疗是否改善mdx小鼠的骨骼肌功能。来自这些研究的积极数据将成为将这种治疗方法快速转化为临床试验的基础。杜氏肌营养不良症（DMD）是最常见的遗传性肌营养不良症。目前没有有效的治疗方法，受影响的男孩在12岁时被轮椅束缚，在30岁时死亡。在拟议的研究中，我们将进行关键的临床前研究，以测试DMD的新疗法。

DESCRIPTION (provided by applicant): The pharmacological upregulation of utrophin has been proposed as a therapeutic strategy for treating DMD. Genetic studies show that increasing utrophin expression can compensate for the loss of dystrophin and correct dystrophic pathology in the mdx mouse. However, genetic approaches for utrophin upregulation are not yet feasible in humans. Biglycan is an extracellular protein that is a component of the Dystrophin complex and binds to a-dystroglycan (Bowe et al., 2000), a - and ?- sarcoglycan (Rafii et al., 2006). Recombinant biglycan protein can be delivered to muscle in vivo where it rescues the sarcolemmal expression of intracellular DAPC components in biglycan null mice (Mercado et al., 2006). In the proposed studies we will use mdx mice to test the potential efficacy of biglycan as a therapeutic for DMD. In preliminary experiments we have shown that purified recombinant biglycan protein delivered systemically to mdx mice upregulates utrophin expression and decreases myofiber death and mononuclear infiltration. Moreover, single doses at therapeutically-practical levels are effective for up to three weeks. In the proposed studies we will produce recombinant biglycan and use histopathological markers to determine the optimal dose, frequency and route(s) of administration for its use. Functional studies will then be carried out to determine whether biglycan treatment improves the function of skeletal muscle in mdx mice. Positive data from these studies would form the basis for a rapid translation of this therapeutic approach to clinical trials. Duchenne Muscular Dystrophy (DMD) is the most common form of inherited muscular dystrophy. Currently there are no effective treatments and affected boys are wheelchair bound by age twelve and die by their third decade. In the proposed studies we will perform critical preclinical studies to test a novel therapy for DMD.