Influence of APOE genotypes on blood brain barrier transport of DHA by mfsd2a in Alzheimer's Disease

APOE基因型对阿尔茨海默病中mfsd2a血脑屏障转运DHA的影响

• 批准号: 9663028
• 负责人: Laila Abdullah
• 金额: --
• 依托单位: JAMES A. HALEY VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-10-01 至 2023-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9663028
• 关键词: Address; Affect; Afghanistan; Age; Alleles; Alzheimer' s Disease; Alzheimer' s disease brain; Alzheimer' s disease model; Alzheimer' s disease pathology; Alzheimer' s disease patient; Alzheimer' s disease risk; Alzheimer' s disease therapy; Amyloid; Amyloid beta-Protein; Animals; Antiinflammatory Effect; Apolipoprotein E; Astrocytes; Biological Availability; Blood; Blood - brain barrier anatomy; Blood Circulation; Brain; Cerebrovascular system; Chronic; Cognitive; Data; Dementia; Development; Diagnosis; Diet; Disease; Docosahexaenoic Acids; Encephalitis; Environment; Exposure to; Extracellular Matrix; Gelatinase B; General Population; Genes; Genotype; High Prevalence; Human; Impairment; In Vitro; Individual; Inflammation; Inflammatory; Injury; Integral Membrane Protein; Investigation; Iraq; Lecithin; Life; Lipids; Lysophosphatidylcholines; Mediating; Membrane; Microglia; Mus; Neurofibrillary Tangles; Nuclear; Omega-3 Fatty Acids; Patients; Pattern; Pericytes; Peripheral; Peroxisome Proliferators; Pharmacology; Plasma; Play; Population; Post-Traumatic Stress Disorders; Protein Isoforms; Proteins; Resistance; Risk; Role; Senile Plaques; Signal Pathway; Signal Transduction; Soldier; Therapeutic; Transgenic Mice; Traumatic Brain Injury; Up-Regulation; Veterans; War; Work; apolipoprotein E-4; blood-brain barrier function; brain endothelial cell; brain parenchyma; combat; cytokine; disorder control; experience; genetic risk factor; high risk; improved; in vivo; lipid transport; mouse model; neuroinflammation; neurotransmission; pre-clinical; prevent; receptor; repaired; uptake; β-amyloid burden

Over 200,000 US Veterans are suffering from Alzheimer's disease (AD) and this figure is expected to increase dramatically in the next few decades due to a higher prevalence of traumatic brain injury (TBI) and post- traumatic stress disorder (PTSD) that are risk factors of AD among soldiers returning from Iraq and Afghanistan wars. The apolipoprotein E (APOE) ε4 allele is the most prevalent genetic risk factor for AD, representing 60% of AD subjects in the general population. The apoE protein is a functional component of plasma involved in the transport of docosahexaenoic acid (DHA) into the brain which plays a key role in neurotransmission, membrane repair and cell signaling. Recent investigations have identified loss of DHA within phosphatidylcholine (PC) in both the brain and blood of AD patients. Our previous work shows that pattern of DHA alterations seen in ε4 carriers with preclinical AD is similar to those seen in ε4 carriers with TBI or TBI +PTSD. While the brain is able to synthesize most lipids, DHA has to be acquired from the periphery since its de novo synthesis is insufficient to meet the high demand in the brain. Studies show that among ε4 carriers, transport of DHA to the brain is reduced compared to non-ε4 carriers, contributing to the pro-inflammatory and pro-amyloidogenic brain environment that is conducive to the development of AD. As such, increasing DHA transport into the brain could be important for preventing or treating AD among ε4 carriers who are at an exceptionally higher risk for developing AD and don't respond well to experimental AD treatments. Lyso-PC (LPC)-DHA is specially transported to the brain through a specialized transporter major facilitator superfamily domain containing 2A (mfsd2a) within the blood-brain-barrier (BBB). We have observed that the expression of mfds2a is reduced in the cerebrovasculature of ε4 carriers compared to non-ε4 carriers, in humans and in a mouse model of AD with human APOE4 gene (E4FAD). We observed that LPC-DHA levels are reduced in the brain parenchyma of ε4 AD patients compared to ε4 controls and non-ε4 AD patients and in E4FAD compared to E3FAD mice. We also observed an increase in matrix metalloproteinase 9 (MMP9) expression in ε4 AD patients and in E4FAD mice. We hypothesize that MMP9 activity is elevated in the presence of ε4 which leads to alterations of the cerebrovasculature, including reduced mfsd2a levels. This results in insufficient brain entry of LPC-DHA, inflammation, and exacerbated AD pathology. To address this problem, we will characterize DHA containing PC and LPC species within the brains of AD and control subjects stratified by different APOE genotypes and quantify corresponding changes in mfsd2a expression. Using EFAD mice, we will generate temporal profiles of PC and LPC-DHA changes and corresponding mfsd2a reduction and its relationship with AD pathology. Moreover, we will use both in vitro and in vivo approaches to determine whether the presence of the apoE4 isoform in the absence of mfsd2a leads to a reduction of LPC-DHA and free DHA transport into the brain and if boosting mfsd2a expression counteracts these effects. We will delve deeper into the fundamental role of MMP9 in the transport of lipids into the brain and evaluate the impact of MMP9-directed therapies on mfsd2a expression and LPC-DHA brain entry in AD. To this point, we have preliminary data indicating that increasing mfsd2a in the brain cerebrovasculature increases brain LPC-DHA levels and reduces inflammation in older E4FAD mice with well-established AD pathology. We find these observations to be extremely compelling as AD therapies have consistently failed in patients with 1) existing AD and 2) those carrying the ε4 allele. These preliminary findings shows promise in treating both of these notoriously resistant populations. Overall, these studies will elucidate mechanisms by which MMP9-mediated loss of mfsd2a causes reduced uptake of DHA in the brain and, additionally, will explore therapeutic avenues to increase LPC-DHA transport into the brain to prevent and treat AD, particularly in ε4 carriers.

超过200,000名美国退伍军人患有阿尔茨海默氏病（AD），预计这一数字将增加 由于脑损伤的率高（TBI）和后，在接下来的几十年中，在接下来的几十年中急剧 创伤应力障碍（PTSD）是伊拉克和阿富汗返回的士兵中广告的风险因素 战争。载脂蛋白E（APOE）ε4等位基因是AD最普遍的遗传危险因素，代表60％ 一般人群中的广告主题。 APOE蛋白是与参与的血浆的功能成分 将二十六烯酸（DHA）运输到大脑中，在神经传递中起着关键作用， 膜修复和细胞信号传导。最近的投资已经确定了DHA内部的损失 AD患者的大脑和血液中的磷脂酰胆碱（PC）。我们以前的工作表明了 在具有临床前AD的ε4载体中看到的DHA变化与TBI或TBI中的ε4载体中看到的变化相似 +PTSD。虽然大脑能够合成大多数脂质，但必须从外围获取DHA，因为 从头合成不足以满足大脑的高需求。研究表明，在ε4载体中， 与非ε4载体相比，DHA向大脑的运输减少了 促淀粉样蛋白生成的大脑环境，为AD的发展进行。因此，增加DHA 进入大脑的运输对于预防或处理AD的ε4载体可能很重要 开发AD的风险异常更高，并且对实验广告处理的反应不佳。 LYSO-PC （LPC）-DHA专门通过专门运输蛋白的主要促进剂超级家族运输到大脑 血脑屏障（BBB）中包含2A（MFSD2A）的结构域。我们观察到的表达 与非 - ε4载体，人类和A中的非ε4载体相比 与人ApoE4基因（E4FAD）AD的小鼠模型。我们观察到LPC-DHA水平降低了 与ε4对照组和非 - ε4AD患者相比，ε4AD患者的脑实质，在E4FAD中 到E3FAD小鼠。我们还观察到ε4AD中基质金属蛋白酶9（MMP9）表达的增加 患者和E4FAD小鼠。我们假设MMP9活性在存在的存在下升高 脑桥一次的改变，包括降低的MFSD2A水平。这导致大脑进入不足 LPC-DHA，炎症和恶化的AD病理学。为了解决这个问题，我们将表征DHA 在AD和控制受试者的大脑中包含PC和LPC物种，由不同的APOE分层 基因型并量化MFSD2A表达的相应变化。使用EFAD小鼠，我们将生成 PC和LPC-DHA的临时专题变化以及相应的MFSD2A降低及其与其与之的关系 广告病理学。此外，我们将同时使用体外和体内方法来确定是否存在 在没有MFSD2A的情况下，APOE4同工型导致LPC-DHA和自由DHA转运降低 大脑以及增加MFSD2A表达会抵消这些影响。我们将深入研究 MMP9在脂质进入大脑中的基本作用并评估MMP9指导的影响 AD中的MFSD2A表达和LPC-DHA脑进入的疗法。至此，我们有初步数据 表明脑大脑脑中的MFSD2A增加会增加脑LPC-DHA水平并降低 具有良好成熟的AD病理学的老年E4FAD小鼠的炎症。我们发现这些观察结果是 由于AD疗法在1）现有AD和2）的患者中始终失败，因此非常引人注目 携带ε4等位基因。这些初步发现显示了这两种臭名昭著的抗药性 人群。总体而言，这些研究将阐明MMP9介导的MFSD2A损失的机制 减少了大脑中DHA的吸收，此外，将探索热途径以增加LPC-DHA 进入大脑以预防和治疗AD，特别是在ε4载体中。