Acute and Long-Term Benefits of Methylene blue Intervention after TBI on Neuroinflammation, Glial Dysfunction, and Neuropsychiatric Complications

项目摘要/摘要： 创伤性脑损伤会导致继发性神经精神并发症，并持续数年。 在受伤后，对健康寿命有负面影响。越来越多的证据表明，神经炎性过程 在最初的头部损伤后进展，并随着时间的推移而恶化。颅脑损伤后正在进行的炎症过程是 由小胶质细胞和星形胶质细胞介导。事实上，这些神经胶质细胞是损伤的主要炎症反应细胞。 因此，重要的是确定可以在脑损伤后立即提供的干预措施，以减少神经胶质细胞损伤。 调节炎症，促进康复。同样重要的是，立即进行干预，防止 行为、认知和病理方面与颅脑损伤相关的长期并发症的发展。新的数据是 以显示立即使用亚甲基蓝(MB)，一种抗氧化剂和抗炎药物 减少中度和弥漫性脑损伤后小鼠的神经炎症，促进功能恢复，以及 限制损伤后1个月启动的和反应性的小胶质细胞的发育。一种底漆的研制 小胶质细胞的表型是相关的，因为它代表了炎症的增加状态。这些被启动的神经胶质细胞 对随后的免疫挑战高度反应，这引发了神经精神病学的发展 并发症。总体而言，我们表明，立即进行甲基溴干预既有急性好处，也有长期好处 在TBI之后。MB临床用于脓毒症、缺血和血管麻痹综合征，但尚未用于临床。 对于TBI。MB是安全的，可以穿过血脑屏障，并可以静脉注射。因此，我们的目标是 为了确定MB干预在多大程度上改变小胶质细胞和星形胶质细胞的激活模式，以及 预防脑外伤后的继发性并发症，包括认知功能下降，神经胶质细胞介导的炎症， 以及神经胶质细胞对免疫挑战的反应性。为了解决这一问题，提出了使用中线流体的三个目标 小鼠颅脑损伤模型的建立。在AIM-1中，我们将确定在TBI后MB干预是否促进 小胶质细胞和星形胶质细胞的神经保护性“修复”图谱。我们将使用独特的方法来确定 特异度脑损伤和亚甲基蓝干预对小胶质细胞和星形胶质细胞mRNA表达及形态的影响 概况，以及与神经元的体外相互作用。在AIM-2中，我们将确定甲基溴干预(立即或 延迟)预防或逆转脑损伤后几个月神经胶质细胞介导的炎症和认知恶化。 在脑损伤后6米内进行认知能力评估。与这些评估平行的是，神经胶质炎症状态 并于伤后1、3、6m测定相关轴索损伤和髓鞘改变。在AIM-3中，我们 将确定立即的MB干预是否阻止了脑损伤诱导的小胶质细胞的免疫反应以及 神经精神并发症的发展。为了解决这个问题，小鼠将接受一百万次免疫挑战。 颅脑损伤后，将确定神经胶质细胞的轮廓和抑郁样行为。总体而言，完成这些 AIMS将为脑外伤诱导的胶质细胞启动和免疫反应性提供新的见解，并将解决其有效性 亚甲基蓝干预的长期效益。

PROJECT SUMMARY/ABSTRACT: Traumatic brain injury (TBI) leads to secondary neuropsychiatric complications that develop and persist years after injury and negatively affect health span. Mounting evidence indicates that neuroinflammatory processes advance after the initial head injury and worsen with time. The ongoing inflammatory processes after TBI are mediated by microglia and astrocytes. In fact, these glia are the primary inflammatory responders to the injury. Therefore, it is important to identify interventions that can be provided immediately after TBI to reduce glial- mediated inflammation and facilitate recovery. It is also critical that immediate interventions prevent the development of TBI-related long-term complications in behavior, cognition, and pathology. New data are provided to show that immediate intervention with methylene blue (MB), an antioxidant and anti-inflammatory agent, reduces neuroinflammation in mice after moderate and diffuse TBI, improves functional recovery, and limits the development of primed and reactive microglia 1 month after injury. Development of a primed microglial phenotype is relevant because it represents an increased state of inflammation. These primed glia are highly reactive to subsequent immune challenges, which trigger the development of neuropsychiatric complications. Overall, we show that there are both acute and long-term benefits of immediate MB intervention after TBI. MB is used clinically in sepsis, ischemia, and vasoplegic syndrome but it has not been used clinically for TBI. MB is safe, crosses the blood brain barrier, and is administered intravenously. Therefore, our goal is to determine the degree to which MB intervention shifts the activation profile of microglia and astrocytes and protects against secondary complications following TBI including cognitive decline, glia-mediated inflammation, and glial reactivity to immune challenge. To address this, three objectives are proposed using a midline fluid percussion injury model of TBI in mice. In Aim-1 we will ascertain if MB intervention after TBI promotes a neuroprotective “repair” profile of microglia and astrocytes. We will use unique approaches to determine the effects of TBI and MB intervention specifically on microglia and astrocyte mRNA expression, morphological profiles, and ex vivo interactions with neurons. In Aim-2 we will determine if MB intervention (immediate or delayed) prevents or reverses glia-mediated inflammation and cognitive deterioration months after TBI. Cognitive ability will be assessed for 6 m after TBI. Parallel to these assessments, glial inflammatory states and associated axonal injury and myelination changes will be determined 1, 3, and 6 m after TBI. In Aim-3, we will determine if immediate MB intervention prevents TBI-induced immune-reactivity of microglia and the development of neuropsychiatric complications. To address this, mice will receive an immune challenge 1 m after TBI and glial profiles and depressive-like behavior will be determined. Collectively, completion of these aims will provide new insight into TBI-induced glial priming and immune-reactivity and will address the efficacy and long-term benefit of methylene blue intervention.