Dendrimer therapies for treatment of Rett Syndrome

项目总结 由胶质细胞激活和谷氨酸神经传递中断引起的脑部炎症一直是 与Rett综合征(RTT)的发病机制和症状恶化有关，RTT是一种使人虚弱的 与癫痫、智力残疾、运动和自主神经相关的发育障碍 功能障碍和非目的性的手部运动。激活的小胶质细胞和星形胶质细胞介导 导致氧化损伤和谷氨酸毒性增加的神经炎性反应。靶向治疗 这些“激活的”小胶质细胞可减轻炎症、氧化损伤和过量谷氨酸的产生 可以通过止伤和促进修复和再生对RTT产生影响。除了超过 通过这些机制产生谷氨酸，RTT和小鼠谷氨酸受体的表达发生变化 MeCP2缺乏可能导致RTT中突触功能障碍的模型。在我们积极的基础上 根据初步结果，我们提出了一种创新的纳米治疗方法来减轻/阻止RTT中的损伤。 使用树枝状大分子在全身给药时固有地靶向激活的小胶质细胞和星形胶质细胞，我们 将提供特定的药物来降低氧化应激、谷氨酸的产生和炎症。我们有 先前的研究表明，树枝状大分子可以靶向激活的神经胶质细胞，并输送药物以产生显著的疗效， 在脑性瘫痪和新生儿中风的模型中。我们在RTT小鼠模型上的初步结果表明 树枝状大分子纳米器件定位于半合子雄性(MeCP2基因缺失)小鼠的小胶质细胞和星形胶质细胞，而不是 野生型(WT)小鼠。此外，树枝状大分子偶联的N-乙酰半胱氨酸(D-NAC)系统地传递 从3周大开始，当MeCP2基因缺失的小鼠出现症状时，每周一次，结果显著改善 6-7周龄时进行神经行为评分。我们假设靶向投放一种反- 炎症/抗氧化剂联合抗谷氨酰胺酶制剂激活MeCP2小胶质细胞和星形胶质细胞 Null和MeCP2杂合子(HET)小鼠将减少氧化损伤和谷氨酸毒性 从而改善神经行为结果和无症状生存。这将使用以下工具进行评估 N-乙酰半胱氨酸(D-NAC；抗炎/抗氧化剂)和树枝状大分子 得到一种新的(Bis-2-(5-phenylacetamido-1，3，4-thiadiazol-2-yl)ethyl硫化物类似物：D-JHU29； 谷氨酰胺酶抑制剂)。我们的具体目标是：1)评价D-NAC或D-NAC单一疗法的疗效。 2)确定D-NAC和D-JHU联合治疗是否 在改善存活率和长期神经预后方面将比单一疗法更有效。对……的影响 生存、体重、行为、视力、呼吸、谷氨酸和谷胱甘肽水平以及氧化应激，以及大脑 将评估音量。这些初步的概念验证研究不仅将提供对 激活的神经胶质细胞在RTT中的作用，但也将形成未来研究的基础，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.