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: 10515657
• 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 2024-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10515657
• 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; Brain; Cerebrovascular system; Chronic; Circulation; Data; Dementia; Development; Diagnosis; Disease; Docosahexaenoic Acids; Encephalitis; Environment; Exposure to; Extracellular Matrix; Gelatinase B; General Population; Genes; Genotype; High Prevalence; Human; Impaired cognition; Impairment; In Vitro; Individual; Inflammation; Inflammatory; Inhibition of Matrix Metalloproteinases Pathway; 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 Proliferator-Activated Receptors; 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 injury; cytokine; dietary; experience; genetic risk factor; high risk; high risk population; improved; in vivo; lipid transport; military veteran; mouse model; neuroinflammation; neurotransmission; pharmacologic; pre-clinical; prevent; 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病（AD），预计这一数字将增加 由于创伤性脑损伤（TBI）和脑损伤后的更高患病率， 创伤性应激障碍（PTSD）是从伊拉克和阿富汗返回的士兵中AD的危险因素 大战载脂蛋白E（APOE）ε4等位基因是AD最常见的遗传危险因素，占60%。 AD受试者在一般人群中的比例。apoE蛋白是血浆的一种功能成分，参与了 将二十二碳六烯酸（DHA）转运到大脑中，其在神经传递中起关键作用， 膜修复和细胞信号传导。最近的调查发现， 磷脂酰胆碱（PC）在AD患者的大脑和血液。我们之前的研究表明， 在临床前AD的ε4携带者中观察到的DHA改变与在TBI或TBI的ε4携带者中观察到的DHA改变相似 +创伤后应激障碍。虽然大脑能够合成大多数脂质，但DHA必须从外周获得，因为它 从头合成不足以满足大脑的高需求。研究表明，在ε4携带者中， 与非ε4载体相比，DHA向大脑的转运减少，导致促炎和 促淀粉样蛋白生成的大脑环境，这有利于AD的发展。因此，增加DHA 转运到大脑中可能对预防或治疗AD的ε4携带者很重要， 患AD的风险异常高，并且对实验性AD治疗反应不佳。溶血PC （LPC）-DHA通过一个专门的转运蛋白主要促进剂超家族专门转运到大脑 在血脑屏障（BBB）内含有2A结构域（mfsd 2a）。我们观察到， 与非ε4携带者相比，在人类和哺乳动物中，ε4携带者的血管系统中mfds 2a减少。 具有人APOE 4基因（E4 FAD）的AD小鼠模型。我们观察到，LPC-DHA水平降低， ε4 AD患者与ε4对照和非ε4 AD患者的脑实质比较，以及E4 FAD患者与E4 FAD患者的脑实质比较， E3 FAD小鼠。我们还观察到基质金属蛋白酶9（MMP 9）在ε4 AD中的表达增加， 患者和E4 FAD小鼠。我们假设MMP 9活性在ε4的存在下升高，这导致MMP 9的表达增加。 包括降低的MFSD 2a水平。这导致大脑进入不足 LPC-DHA的增加，并加重AD病理学。为了解决这个问题，我们将描述DHA 包含AD和对照受试者脑内PC和LPC物质，通过不同APOE分层艾德 基因型并定量MFSD 2a表达的相应变化。使用EFAD小鼠，我们将产生 PC和LPC-DHA变化的时间分布和相应的mfsd 2a减少及其与 AD病理学此外，我们将使用体外和体内方法来确定是否存在 在缺乏mfsd 2a的情况下，apoE 4同种型的减少导致LPC-DHA和游离DHA转运到 脑和IF增强MFSD 2a表达抵消了这些作用。我们将深入探讨 MMP 9在脂质转运到大脑中的基本作用，并评估MMP 9导向的 治疗对AD患者mfsd 2a表达和LPC-DHA脑内进入的影响。 表明增加脑血管系统中的mfsd 2a增加脑LPC-DHA水平， 在具有明确AD病理学的老年E4 FAD小鼠中的再灌注。我们发现这些观察结果是 非常引人注目，因为AD治疗在1）现有AD患者和2） 携带ε4等位基因这些初步的发现显示了治疗这两种众所周知的耐药性的希望。 人口。总之，这些研究将阐明MMP 9介导的mfsd 2a缺失导致 减少DHA在大脑中的摄取，此外，将探索治疗途径，以增加LPC-DHA 转运到大脑中以预防和治疗AD，特别是在ε4携带者中。