Dendrimer therapies for treatment of Rett Syndrome

项目摘要 由神经胶质活化和谷氨酸神经传递的破坏诱导的脑中的炎症已经被研究。 涉及Rett综合征（RTT）的发病机制和症状恶化， 与癫痫发作、智力残疾、运动和自主神经相关的发育障碍 功能障碍和无目的的手部运动。活化的小胶质细胞和星形胶质细胞介导了 神经炎症反应，导致氧化损伤和谷氨酸毒性增加。有针对性的治疗 这些“激活的”小胶质细胞用于减少炎症，氧化损伤和过量谷氨酸盐的产生 可以通过阻止损伤并促进修复和再生来影响RTT。除了超过 通过这些机制产生谷氨酸，RTT和小鼠中谷氨酸受体表达改变， Mecp 2功能不全的模型可能导致RTT中的突触功能障碍。基于我们积极的 初步结果，我们提出了一种创新的，纳米的方法来减弱/逮捕RTT的伤害。 使用系统给药后内在靶向激活的小胶质细胞和星形胶质细胞的树枝状聚合物，我们 将提供特定的药物来下调氧化应激，谷氨酸盐的产生和炎症。我们有 先前显示树枝状聚合物可以靶向激活的神经胶质细胞并递送药物以产生显著的功效， 大脑性麻痹和新生儿中风的模型中。我们在小鼠RTT模型中的初步结果表明， 树枝状聚合物纳米器件定位于半合子雄性（Mecp 2-null）小鼠的小胶质细胞和星形胶质细胞中，但不定位于 野生型（WT）小鼠。此外，树枝状聚合物缀合的N-乙酰半胱氨酸（D-NAC）全身递送 当Mecp 2-null小鼠出现症状时，从3周龄开始每周一次， 6-7周龄时的神经行为评分。我们假设靶向递送抗- 炎性/抗氧化剂沿着与抗β-淀粉酶剂一起对Mecp 2中活化的小胶质细胞和星形胶质细胞的作用。 null和Mecp 2杂合（HET）小鼠将导致氧化损伤和谷氨酸毒性降低 导致改善的神经行为结果和无症状存活。这将使用 与N-乙酰半胱氨酸（D-NAC;抗炎/抗氧化剂）缀合的树枝状聚合物和与N-乙酰半胱氨酸（D-NAC;抗炎/抗氧化剂）缀合的树枝状聚合物 BPTES的新类似物（双-2-（5-苯基乙酰氨基-1，3，4-噻二唑-2-基）乙基硫醚; D-JHU 29; 转氨酶抑制剂）。我们的具体目的是：1）评价D-NAC或D-NAC单药治疗的疗效。 在Mecp 2-null和HET小鼠中使用D-JHU 29，以及2）确定用D-NAC和D-JHU的组合疗法是否 在改善生存率和长期神经学结局方面，比单药治疗更有效。影响 存活率、体重、行为、视力、呼吸、谷氨酸和谷胱甘肽水平以及氧化应激和大脑 量将进行评估。这些初步的概念验证研究不仅可以更好地了解 激活的神经胶质细胞在RTT中的作用，但也将成为未来研究的基础，使临床翻译。

PROJECT SUMMARY Inflammation in the brain induced by glial activation and disruption of glutamate neurotransmission have been implicated in the pathogenesis and worsening of symptoms in Rett syndrome (RTT), a debilitating, developmental disorder that is associated with seizures, intellectual disability, motor and autonomic dysfunction, and non-purposeful hand movements. Activated microglial cells and astrocytes mediate the neuroinflammatory response that leads to oxidative injury and increased glutamate toxicity. Therapies targeted to these ‘activated’ microglia for diminishing inflammation, oxidative injury and excess glutamate production could have an impact in RTT by arresting the injury and promoting repair and regeneration. In addition to over production of glutamate by these mechanisms, glutamate receptor expression is altered in RTT and mouse models of Mecp2 insufficiency that may contribute to synaptic dysfunction in RTT. Building on our positive preliminary results, we propose an innovative, nanotherapeutic approach to attenuate/arrest the injury in RTT. Using dendrimers that intrinsically target activated microglia and astrocytes upon systemic administration, we will deliver specific drugs to down regulate oxidative stress, glutamate production and inflammation. We have previously shown that dendrimers can target activated glia and deliver drugs to produce significant efficacies, in models of cerebral palsy and neonatal stroke. Our preliminary results in a mouse model of RTT indicate that dendrimer nanodevices localize in microglia and astrocytes of hemizygous male (Mecp2-null) mice but not in wild-type (WT) mice. Moreover, dendrimer-conjugated N-acetyl cysteine (D-NAC) delivered systemically weekly from 3 weeks of age, when Mecp2-null mice become symptomatic, results in significant improvement in neurobehavioral scores at 6-7 weeks of age. We hypothesize that targeted delivery of an anti- inflammatory/anti-oxidant along with an anti-glutaminase agent to activated microglia and astrocytes in Mecp2- null and Mecp2-heterozygous (HET) mice will lead to decreased oxidative injury and glutamate toxicity resulting in improved neurobehavioral outcomes and symptom free survival. This will be evaluated using dendrimer conjugated to N-acetyl cysteine (D-NAC; anti-inflammatory/anti-oxidant) and dendrimer conjugated to a novel analogue of BPTES (Bis-2-(5-phenylacetamido-1,3,4-thiadiazol-2-yl)ethyl sulfide; D-JHU 29; glutaminase inhibitor). Our Specific Aims are: 1) to evaluate the efficacy of monotherapy with D-NAC or D- JHU29 in Mecp2-null and HET mice, and 2) to determine whether combination therapy with D-NAC and D-JHU will be more effective than monotherapy in improving survival and long-term neurologic outcomes. Effects on survival, weight, behavior, vision, respiration, glutamate and glutathione levels and oxidative stress, and brain volume will be evaluated. These initial proof-of-concept studies will not only provide a greater understanding of the role of activated glia in RTT, but will also form the basis for future studies enabling clinical translation.