阻塞性睡眠呼吸暂停模式间歇低氧暴露后神经元小胶质细胞相互作用的机制以及内皮祖细胞的干预作用

The prevalence of obstructive sleep apnea (OSA) is about 2%~4%, and the major pathophysiologic characteristic from OSA is intermittent hypoxia (IH). IH resulting from OSA may cause structural neuron damage and dysfunction in the central nervous system (CNS). Clinically, it manifests as neurocognitive and behavioral deficits, and may be orchestrated largely by microglia-neuron crosstalk mediated oxidative stress and inflammation, which may continue and cascade persistently upon activation. In this study, IH circumstance for animals and cells will be mimicked and microglia-neuron crosstalk model will be developed in vitro. We will measure ① initial inflammatory status following IH exposure; ② if the initial inflammation may cause neuronal secondary damage through microglia-neuron crosstalk, and finally, resulting in positive inflammatory feedback in microglia-neuron system? ③ the roles in progressive inflammation bridged by high-mobility group box 1 (HMGB1)/ macrophage antigen complex 1 (Mac1)—nuclear factor (NF)-κB pathway and by HMGB1/ Mac1—NADPH oxidase signaling axis; and the bounding mechanisms for HMGB1/ Mac1 interaction; ④ endothelial progenitor cells (EPCs) will be utilized through Transwell to antagonize progressive neuronal inflammation in vitro; and the functional classification of EPCs according to aldehyde dehydrogenase (ALDH) activity following IH exposure. In virtue of this study, we may explore the potential possibilities and targets for cognition and behavior deficiencies with pharmacologic therapy or other modalities in OSA patients, and may provide individual regimen to prohibit progressive CNS inflammation without severe immune-suppression.

阻塞性睡眠呼吸暂停(OSA)病生理特点为间歇低氧(IH)。本课题组前期研究提出，OSA IH可能导致中枢神经系统(CNS)神经元小胶质细胞相互作用(N-M)主导的持续进展级联放大炎性损伤，致CNS神经元损伤与功能障碍。用本小组开发的IH环境并构建N-M对话模型，测定：IH暴露后初始炎症；初始炎症是否通过N-M造成神经元二次打击与炎性正反馈？该过程中高迁移率族蛋白B1/巨噬细胞抗原复合体1(HMGB1/Mac1)相互作用介导的核因子(NF)-κB通道和尼克酰胺腺嘌呤二核苷酸磷酸氧化酶通道的作用；并探索HMGB1与Mac1膜结合机制；在本小组前期研究基础上，用内皮祖细胞(EPC)通过Transwell拮抗IH进展性炎症；测IH后EPC功能分类。研究试图揭示OSA IH暴露后CNS认知、行为障碍药物治疗可能性和潜在靶点；通过药物或如EPC输注改变小胶质细胞功能，维持CNS免疫并拮抗CNS损伤。

本研究在本课题组前期研究基础上成功构建OSA动物模型—IH暴露的C57BL/6小鼠，以及T2DM动物模型—KK-Ay小鼠。运用Morris水迷宫实验证明两种动物模型小鼠存在学习和记忆的认知功能障碍，并进一步发现IH可加重T2DM小鼠认知缺陷，证明OSA合并T2DM会使认知障碍加重。我们发现IH+HG可通过激活的小胶质细胞释放HMGB1到细胞外空间，之后反作用于小胶质细胞表面受体，维持小胶质细胞活化状态，导致神经炎症和氧化应激状态。IH+HG的物理刺激和长期慢性的炎症反应对海马神经元造成“二次打击”，通过调控PI3K/Akt/GSK3β/β-catenin信号通路失活引起海马神经元凋亡，最终导致认知功能障碍的发生。同时我们发现IH+HG可通过HMGB1/TLR4相互作用介导海马神经元自噬抑制和凋亡增加。本课题组通过向C57BL/6小鼠腹腔注射LPS成功构建脓毒症模型小鼠，并进行NOX2基因敲除试验，通过病态行为的观察及旷场实验，确定了NOX2-/-可以减轻短期的病态行为及抑制CNS炎症反应。我们发现中枢镇咳药DM可作为NOX2抑制剂减少脓毒症小鼠脑内小胶质细胞活化，抑制神经炎症，减轻短期的病态行为。我们还发现超低剂量DM还可以显著降低脓毒血症小鼠的血清丙氨酸氨基转移酶活性，血清TNF-α水平和肝细胞损伤程度。超低剂量的DM可显著降低Kupffer细胞中NADPH氧化酶产生的超氧自由基，进而抑制了其下游ROS的升高，减轻了Kupffer细胞中氧化应激程度并降低了TNF-α 水平。这些发现使我们提出了使用超低浓度的DM干预败血症或败血性休克以及神经炎症损伤的新颖治疗概念。