Systemic Inflammation and Central Nervous System Dysfunction

描述（由申请人提供）：越来越多的证据表明，老年人的不良健康结果与慢性轻度炎症状态的发展密切相关。在人类中，炎症循环标志物，包括炎症细胞因子白细胞介素-6 (IL-6)，与虚弱、肌肉质量和力量丧失、残疾和过早死亡、急性和慢性认知能力下降、阿尔茨海默病的发展以及药物和压力引起的谵妄的风险增加相关，或者可以预测这些风险。 IL-6 通过经典的 Jak/STAT 途径激活一系列炎症作用，但我们最近发现 IL-6 通过转录因子 NFkB 的非经典激活起作用，诱导 NADPH 氧化酶 (Nox2) 的神经元表达和激活，NADPH 氧化酶 (Nox2) 是一种多聚酶复合物，最初被描述为中性粒细胞中的呼吸爆发氧化酶。 Nox2 旨在产生大量活性氧 (ROS)，主要是超氧阴离子。我们进一步表明，Nox2 在衰老大脑的神经元中被诱导和激活，并且 Nox2 实际上是老年小鼠神经元和突触超氧化物产生的主要来源。 Nox2 的炎症诱导导致海马、皮质和杏仁核中抑制性中间神经元亚群的超氧化物依赖性损失。在啮齿类动物、狗和灵长类动物中观察到这些神经元的丧失，并被认为是跨认知领域认知缺陷的基础。我们将检验以下假设：年龄相关的 IL-6 增加（可能由炎症细胞因子 TNFa 或抗炎细胞因子 IL-10 的缺失介导）会诱导神经元 Nox2 表达，而 Nox2 反过来会导致学习、注意力和记忆编码所需的抑制性神经回路持续缺陷。老年野生型小鼠和经过修饰（遗传或药理学）修饰 IL-6 表达、信号传导或特定下游靶标的老年小鼠将用于检验我们的假设。各种技术，包括 Nox2 活性的活体动物荧光成像、EPR、共聚焦成像、免疫荧光、电生理学和大脑区域特定功能的行为测试（例如空间学习、海马 CA3 依赖性过程）将用于测试我们假设序列中的每个链接。最后，将进行一系列调节 IL-6 的药物和免疫疗法或拟议的事件序列的介入研究，以确定小鼠中与年龄相关的认知缺陷是否得到改善，并进一步测试我们的假设序列。对人类健康的重要性：认知功能的变化是老年人和社会的一个重要健康问题。炎症通路激活与大脑衰老之间的联系仍有待完全确定。这里提出的研究旨在探索一种可能将炎症途径和与年龄相关的认知缺陷联系起来的途径，并有可能为衰老大脑中重要且可能可逆的生物和神经回路变化提供更多见解。

DESCRIPTION (provided by applicant): Increasing evidence indicates that adverse health outcomes in older adults are strongly associated with the development of a state of chronic, mild inflammation. In humans, circulating markers of inflammation, including the inflammatory cytokine interleukin-6 (IL-6), are associated with, or predict, enhanced risk of frailty, loss of muscle mass and strength, disability, and early mortality, as well as acute and chronic cognitive decline, development of Alzheimer's disease, and drug- and stress-induced delirium. IL-6 activates a host of inflammatory actions through classical Jak/STAT pathway, but we recently found that IL-6, acting through non-cannonical activation of the transcription factor, NFkB, induces neuronal expression and activation of NADPH oxidase (Nox2), a multimeric enzyme complex first described as the respiratory burst oxidase in neutrophils. Nox2 is designed to produce large amounts of reactive oxygen species (ROS), primarily superoxide anion. We have further shown that Nox2 is induced and activated in neurons in the aging brain, and that Nox2 is in fact the major source of neuronal and synaptic superoxide production in aged mice. Inflammatory induction of Nox2 led to a superoxide-dependent loss of subsets of inhibitory interneurons in hippocampus, cortex, and amygdala. Loss of these neurons is observed in rodents, dogs, and primates, and has been proposed to underlie cognitive deficits across cognitive domains. We will test the hypothesis that age-related increase in IL-6, potentially mediated by the inflammatory cytokine TNFa or loss of the anti-inflammatory cytokine IL-10, induces neuronal Nox2 expression and that Nox2, in turn, results in persistent deficits in inhibitory neural circuits required for learning, attention, and memory encoding. Aged wild-type mice, and aged mice with modifications (either genetic or pharmacologic) which modify IL-6 expression, signaling, or specific downstream targets, will be used to test our hypothesis. A variety of techniques, including live animal fluorescence imaging of Nox2 activity, EPR, confocal imaging, immuno-fluorescence, electrophysiology and behavioral testing of brain region-specific function (e.g. spatial learning, a hippocampal CA3-dependent process) will be used to test each link in our hypothesized sequence. Finally, a series of interventional studies with drugs and immunotherapies which modulate IL-6, or the proposed sequence of events, will be carried out to determine whether age-related cognitive deficits in the mice are ameliorated, and to further test our hypothetical sequence. Importance to Human Health: Changes in cognitive function are an important health concern for older adults, and for society. The link between inflammatory pathway activation and aging in the brain remains to be fully defined. The studies proposed here are designed to explore one pathway which may link inflammatory pathways and age-related cognitive deficits, with the potential to provide additional insights into important and possibly reversible biological and neural circuitry changes in the aging brain.