Neuroinflammatory Mechanisms of Vascular Cognitive Impairment

摘要 与衰老相关的痴呆是一个主要的公共卫生问题，它给人们带来了巨大的情感、身体和 给患者、他们的家人和医疗保健系统带来经济压力。临床和流行病学证据 提示血管和代谢危险因素的存在，如肥胖、糖尿病、血脂异常和 高血压，统称为代谢综合征(METS)，在中年会增加患高血压的风险 晚年痴呆的严重程度。拟议的研究将使用蛋氨酸的慢性高脂饮食(HFD)模型 目的：探讨蛋氨酸相关认知功能障碍(MetSCD)的发病机制及其年龄依赖性。 我们在有痴呆史的死后人脑和饲喂HFD的小鼠脑中的观察 提示蛋氨酸可增加脑组织中酶溶环氧化物水解酶的表达和活性 微血管内皮细胞，导致其底物环氧二十碳三烯酸酯(EETs)的生物利用度降低， 具有抗炎作用。内皮EETs降低易使内皮细胞活化， 外周免疫细胞渗入脑实质，神经炎症和认知功能障碍。在……里面 支持sEH上调、神经炎症和认知障碍之间的因果联系，小鼠 内皮细胞过度表达的人sEH表现出年龄依赖性的神经炎症和认知障碍，而 SEH的药理抑制对HFD诱导的神经炎症和认知损害具有保护作用。 我们将检验这一假说，即蛋氨酸通过渗透 外周免疫细胞和进行性神经炎。目标1将使用雄性和雌性野生型(WT) 小鼠和内皮特异性sEH缺失的小鼠，标准饮食(STD)或高脂饮食(HFD)，以确定 内皮细胞sEH在12月龄和24月龄MetSCD中的作用AIM 2将使用流式细胞术， 免疫组织化学(IHC)和单细胞RNAseq(ScRNAseq)以确定HFD是否诱导AGE- 以中性粒细胞早期浸润和延迟浸润为特征的依赖型神经炎性反应 T和B淋巴细胞。我们将使用免疫细胞报告小鼠(Fgd5-CreERT2；Ai9)来确认外周血细胞 白细胞的来源，表征免疫细胞侵袭的时间过程，并确定内皮细胞特异性 SEH的缺失可防止免疫细胞渗入HFD小鼠的大脑。目标3将确定sEH是否 抑制剂t-AUCB(脑渗透剂)和 GSK2256294(不跨越血脑屏障，BBB) 保护 抗慢性肾衰小鼠的神经认知功能障碍。我们还将确定是否存在性别差异 在治疗效果上。建议的研究具有很高的翻译性，并将促进对 机制和年龄依赖的MetSCD。大鼠年龄依赖性免疫细胞浸润的内皮来源 MetSC是新的，使用Fgd5-CreERT2；Ai9小鼠的scRNAseq和免疫细胞命运图谱也是新的。

ABSTRACT Aging-related dementia is a major public health concern that places an enormous emotional, physical, and financial stress on patients, their families and health-care systems. Clinical and epidemiological evidence suggests that the presence of vascular and metabolic risk factors, such as obesity, diabetes, dyslipidemia and hypertension, collectively known as the metabolic syndrome (MetS), during midlife increases the risk for and severity of dementia in late-life. The proposed studies will use the chronic high-fat diet (HFD) model of MetS in mice to investigate the mechanism and age-dependency of MetS-related cognitive dysfunction (MetSCD). Our observations made in postmortem human brain with a history of dementia and in brains of HFD-fed mice suggest that MetS increases the expression and activity of the enzyme soluble epoxide hydrolase (sEH) in brain microvascular endothelium, leading to reduced bioavailability of its substrate epoxyeicosatrienoates (EETs), which have anti-inflammatory properties. Reduced endothelial EETs predisposes to endothelial cell activation, peripheral immune cell infiltration into brain parenchyma, neuroinflammation and cognitive dysfunction. In support of a causal link between sEH upregulation, neuroinflammation and cognitive impairment, mice with endothelial overexpression of human sEH exhibit age-dependent neuroinflammation and cognitive deficit, while pharmacological inhibition of sEH protects against HFD-induced neuroinflammation and cognitive impairment. We will test the hypothesis that MetS contributes to late-life cognitive dysfunction via the infiltration of peripheral immune cells and progressive neuroinflammation. Aim 1 will use male and female wild-type (WT) mice and mice with endothelial-specific deletion of sEH, on standard (STD) or high-fat diet (HFD), to determine the role of endothelial sEH in MetSCD at 12 and 24 months of age. Aim 2 will use flow cytometry, immunohistochemistry (IHC) and single-cell RNAseq (scRNAseq) to determine if HFD induces an age- dependent neuroinflammatory response characterized by early infiltration of neutrophils and delayed infiltration of T and B lymphocytes. We will use immune cell reporter mice (Fgd5-CreERT2;Ai9) to confirm the peripheral origin of leukocytes, characterize the time course of immune cell invasion, and determine if endothelial-specific deletion of sEH prevents immune cell infiltration into the brain of mice on HFD. Aim 3 will determine if sEH inhibitors t-AUCB (brain-penetrant) and GSK2256294 (does not cross the blood-brain barrier, BBB) protect against neurocognitive impairment in mice on chronic HFD. We will also determine if there are sex differences in treatment effects. The proposed studies are highly translational, and will advance understanding of mechanisms and age-dependency MetSCD. The endothelial origin of age-dependent immune cell infiltration in MetSC is novel, and so is the use of scRNAseq and immune cell fate mapping using Fgd5-CreERT2; Ai9 mice.