Intermittent Hypoxia-Induced Inflammation Modulates Respiratory Plasticity

项目摘要/摘要 破坏控制呼吸的神经系统的因素会降低补偿能力 病理，威胁生命本身。可塑性是神经系统的基本特征，包括神经系统 控制呼吸。指导这一提议的基本假设是全身炎症 损害呼吸运动的可塑性，破坏对多种疾病的补偿能力， 包括慢性肺部疾病、创伤性、缺血性和退行性神经疾病以及阻塞性睡眠 呼吸暂停。我们建议研究炎症损害一个研究得很好的模型的机制。 急性间歇性低氧后呼吸运动可塑性、膈神经长期便捷化(PLTF)。我们会 内毒素致炎与一天重度间歇致炎的对比研究 低氧(SIH)；SIH模拟阻塞性睡眠呼吸暂停的各个方面，阻塞性睡眠呼吸暂停是一种广泛存在的临床疾病，主要 对人类健康的影响。令人兴奋的初步数据表明，内毒素和sih都通过脊髓阻断pLTF。 发炎。由于内毒素和SIH在不同类型的脊髓细胞中诱导差异基因表达，但 对于pLTF的类似影响，我们提出了一个统一的假设，即多个炎症分子 汇聚在一个共同的“下游”信号级联上，从而限制呼吸运动的可塑性。 将使用一种创新的、多学科的方法来检验我们的假设；实验方法 包括：麻醉大鼠的膈神经记录，非麻醉大鼠的隔膜肌电记录， 标记膈运动神经元蛋白质的免疫组织化学分析及炎症基因分析 新分离的脊髓星形胶质细胞和小胶质细胞的表达，以及流式细胞仪检测蛋白质在 确定了细胞类型。为了促进我们的理解，我们将测试五个具体的假设：1)系统性内毒素 和sih引起脊髓炎症，从而损害隔膜和隔膜Ltf；2)不同的内毒素和sih 损伤到膈运动促进(PMF)的不同通路。我们将确定内毒素和SIH对ERK的影响- 依赖(例如PLTF)、Akt依赖和ERK/Akt依赖的PMF；3)内毒素和SiH诱导明显的炎症反应 配置文件。SiH只影响脊髓小胶质细胞，而内毒素也影响星形胶质细胞；4)尽管不同 炎症反应、内毒素和sih通过共同的涉及p38map的“下游”机制损害pLTF。 5)脊髓p38活性增加蛋白磷酸酶2A 在膈运动神经元的活动，从而抑制ERK和抑制pLTF。了解机制 炎症破坏呼吸道可塑性是至关重要的，因为炎症可能 在病理状态下降低自然的、补偿性可塑性的能力。我们的长期目标是 利用和促进呼吸可塑性作为治疗毁灭性呼吸障碍的一种治疗策略， 例如在颈椎损伤或运动神经元病期间。

PROJECT SUMMARY/ABSTRACT Factors that undermine the neural system controlling breathing diminish the capacity to compensate for pathology, threatening life itself. Plasticity is an essential feature of neural systems, including the neural system controlling breathing. The fundamental hypothesis guiding this proposal is that systemic inflammation impairs respiratory motor plasticity, undermining the ability to compensate for multiple pathologies, including chronic lung disease, traumatic, ischemic and degenerative neural disorders, and obstructive sleep apnea. We propose to investigate mechanisms whereby inflammation impairs a well-studied model of respiratory motor plasticity, phrenic long-term facilitiation (pLTF) following acute intermittent hypoxia. We will contrast inflammation induced by lipopolysaccharide (LPS) with that induced by one day of severe intermittent hypoxia (sIH); sIH simulates aspects of obstructive sleep apnea, a widespread clinical disorder with major implications for human health. Exciting preliminary data suggest that both LPS and sIH block pLTF via spinal inflammation. Since LPS and sIH elicit differential gene expression in different spinal cell types, yet have similar effects on pLTF, we propose a unifying hypothesis whereby multiple inflammatory molecules converge on a common "downstream" signaling cascade that constrains respiratory motor plasticity. An innovative, multidisciplinary approach will be used to test our hypotheses; experimental approaches include: phrenic nerve recordings in anesthetized rats, diaphragm EMG recordings in unanesthetized rats, immunohistochemical analysis of proteins in labeled phrenic motor neurons, analysis of inflammatory gene expression in freshly-isolated spinal astrocytes and microglia, and flow cytometry to assess proteins in identified cell types. Five specific hypotheses will be tested to advance our understanding: 1) Systemic LPS and sIH elicit spinal inflammation, thereby impairing phrenic and diaphragm LTF; 2) LPS and sIH differentially impair distinct pathways to phrenic motor facilitation (pMF). We will determine LPS and sIH effects on ERK- dependent (eg. pLTF), Akt-dependent and ERK/Akt-dependent pMF; 3) LPS and sIH elicit distinct inflammatory profiles. sIH affects only spinal microglia, whereas LPS also affects astrocytes; 4) Despite different inflammatory profiles, LPS and sIH impair pLTF by a common "downstream" mechanism involving p38 MAP kinase activation in phrenic motor neurons; and 5) Spinal p38 activity increases protein phosphatase 2A activity in phrenic motor neurons, thereby inhibiting ERK and constraining pLTF. Understanding mechanisms whereby inflammation undermines respiratory plasticity is of fundamental importance since inflammation may diminish the capacity for natural, compensatory plasticity during pathological states. Our long-range goal is to harness and promote respiratory plasticity as a therapeutic strategy to treat devastating breathing disorders, such as during cervical spinal injury or motor neuron disease.