Oral Gene Delivery to Improve Iron Overload Disorders

项目总结/摘要 高铁储存是多种疾病发病机制的明确风险因素，包括心力衰竭， 肝硬化、关节炎、糖尿病和高脂血症。铁超负荷最好的代表是遗传性的 血色病（HH）是北美高加索人最常见的遗传性疾病之一， 人群，其特征在于肠吸收增加和铁的进行性组织沉积。 HFE（高铁）基因多态性是HH的主要原因，在北方占7-32%。 美国人口。铁超载也发生在输血，这是需要几个贫血 (e.g.地中海贫血、镰状细胞性贫血）。值得注意的是，高铁储存在 大脑与几种神经退行性疾病（如阿尔茨海默病和帕金森病）有关， 一些病理状况，包括创伤性脑损伤。铁螯合剂，如去铁胺和 地拉罗司在临床上用于降低铁负荷，但螯合剂的使用受到许多限制。 显著的副作用，包括粒细胞缺乏症、中性粒细胞减少症、眼/听觉毒性、肌肉关节炎 疼痛、胃肠道紊乱甚至死亡。考虑到受影响的数亿人 由于各种类型的铁过载，对通过控制铁过载的新的治疗策略存在前所未有的需求。 铁在体内的运输。虽然二价金属转运蛋白1（DMT 1）在细胞凋亡中起着公认的作用， 铁作为一种必需营养素从饮食中吸收，肠道DMT 1的上调与HH相关， 人类和老鼠都是。由于骨髓中红细胞的产生也需要DMT 1，因此“选择性” 通过将DMT 1抑制剂直接递送到 吸收部位（即口服给药），无全身效应。虽然一些小分子 DMT 1抑制剂已被研究，但总体热情较低，因为这些抑制剂“间接”改变DMT 1 功能，例如通过改变氧化还原状态，以及它们不利的体内药代动力学 性质（溶解性差和快速代谢）。基因沉默增加了治疗潜力， 选择性地降低不需要的分子的水平，如致癌蛋白和促炎蛋白。 细胞因子我们最近证实，在小鼠中，肠道TNFα显著下调， 在口服给予微球中的纳米颗粒（NM）中的siRNA后的结肠炎模型， 结肠炎条件。因此，主要的潜在假设是，通过siRNA包裹的口服DMT 1沉默， NM降低膳食铁的肠道摄取，并改善铁过载和铁介导的毒性。的 本研究的具体目的集中在1）开发和验证DMT 1 siRNA/NM以抑制肠 铁转运蛋白和铁吸收，以及2）使用 铁超载小鼠模型。总的来说，这一战略提供了一种有选择性的有效方法， 通过siRNA和纳米技术的组合对许多铁过载疾病的治疗益处。

PROJECT SUMMARY/ABSTRACT High iron stores are a well-defined risk factor for the pathogenesis of several diseases, including heart failure, liver cirrhosis, arthritis, diabetes and hypertriglyceridemia. Iron overload is best represented by hereditary hemochromatosis (HH), one of the most common genetic diseases in the North American Caucasian population, which is characterized by elevated intestinal absorption and progressive tissue deposition of iron. Polymorphisms in the HFE (High Fe) gene are the leading cause of HH, accounting for 7-32% in North American populations. Iron overload also occurs in blood transfusion, which is required for several anemias (e.g. thalassemia, sickle cell anemia) due to defects in blood cell metabolism. Notably, high iron stores in the brain are associated with several neurodegenerative diseases (e.g. Alzheimer’s and Parkinson’s diseases) and some pathological conditions, including traumatic brain injury. Iron chelators, such as deferoxamine and deferasirox, are clinically used to reduce iron burden, but the use of chelators is limited by a number of significant side effects, including agranulocytosis, neutropenia, ocular/auditory toxicities, musculoskeletal-joint pains, gastrointestinal disturbances and even death. Considering hundreds of millions of people affected by various types of iron overload, there are unprecedented needs for a new therapeutic strategy by controlling the transport of iron in the body. While the Divalent Metal Transporter 1 (DMT1) plays a well-established role in the absorption of iron as an essential nutrient from diet, up-regulation of intestinal DMT1 is associated with HH in both humans and mice. Since DMT1 is also required for red cell production in the bone marrow, a “selective” suppression of intestinal DMT1 can be an excellent therapeutic target by direct delivery of DMT1 inhibitors to the site of absorption (i.e. oral administration) with no systemic effects. Although a few small molecule-based DMT1 inhibitors have been studied, overall enthusiasm is low because these inhibitors “indirectly” alter DMT1 function, for example, by modifying redox status, as well as their unfavorable in vivo pharmacokinetic properties (poor solubility and rapid metabolism). Gene silencing has increased therapeutic potential to selectively decrease the levels of unwanted molecules, such as oncogenic proteins and pro-inflammatory cytokines. We have recently demonstrated that intestinal TNFα was significantly down-regulated in a mouse model of colitis after oral administration of siRNA in nanoparticles-in-microspheres (NMs), which improved colitis conditions. Thus, the major underlying hypothesis is that oral DMT1 silencing by siRNA-encapsulated NMs decreases intestinal uptake of dietary iron and improves iron overload and iron-mediated toxicity. The specific aims of this study are focused on 1) developing and validating DMT1 siRNA/NMs to inhibit intestinal iron transporters and iron absorption and 2) evaluating the therapeutic efficacy of DMT1 siRNA/NMs using a mouse model of iron overload. Overall, this strategy provides a selective and effective method to support therapeutic benefits over numerous iron overload disorders by a combination of siRNA and nanotechnology.