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: 10292958
• 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/10292958
• 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; Disease; Docosahexaenoic Acids; Encephalitis; Environment; Exposure to; Extracellular Matrix; Gelatinase B; General Population; Genes; Genotype; High Prevalence; Human; Impairment; In Vitro; Individual; Inflammation; Inflammatory; 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 injury; cytokine; dietary; disorder control; experience; genetic risk factor; high risk; improved; in vivo; lipid transport; military veteran; 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病 (AD)，并且这一数字预计还会增加 由于创伤性脑损伤 (TBI) 和术后创伤性脑损伤 (TBI) 的患病率较高，未来几十年将出现戏剧性的变化。 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 战争。载脂蛋白 E (APOE) ε4 等位基因是 AD 最常见的遗传风险因素，占 60% 普通人群中 AD 受试者的比例。 apoE 蛋白是血浆的功能成分，参与 将二十二碳六烯酸 (DHA) 转运至大脑，在神经传递中发挥关键作用， 膜修复和细胞信号传导。最近的研究发现 DHA 的损失 AD 患者大脑和血液中的磷脂酰胆碱 (PC)。我们之前的工作表明了这种模式 患有临床前 AD 的 ε4 携带者中观察到的 DHA 改变与患有 TBI 或 TBI 的 ε4 携带者中观察到的类似。 +创伤后应激障碍。虽然大脑能够合成大多数脂质，但 DHA 必须从外周获取，因为它 从头合成不足以满足大脑的高需求。研究表明，在 ε4 载流子中， 与非 ε4 载体相比，DHA 向大脑的运输减少，有助于促炎和 促淀粉样蛋白生成的大脑环境有利于 AD 的发展。因此，增加DHA 转运到大脑对于预防或治疗处于 ε4 携带者中的 AD 可能很重要 患 AD 的风险特别高，并且对实验性 AD 治疗反应不佳。溶血PC (LPC)-DHA 通过专门的转运蛋白主要促进子超家族专门转运到大脑 血脑屏障 (BBB) 内含有 2A (mfsd2a) 的结构域。我们观察到表达 与非 ε4 携带者相比，在人类和动物中，ε4 携带者的脑血管系统中 mfds2a 减少 带有人类 APOE4 基因 (E4FAD) 的 AD 小鼠模型。我们观察到 LPC-DHA 水平在 ε4 AD 患者的脑实质与 ε4 对照组和非 ε4 AD 患者相比，以及 E4FAD 的脑实质比较 E3FAD 小鼠。我们还观察到 ε4 AD 中基质金属蛋白酶 9 (MMP9) 表达增加 患者和 E4FAD 小鼠。我们假设 ε4 存在时 MMP9 活性升高，从而导致 脑血管系统的改变，包括 mfsd2a 水平降低。这导致大脑进入不足 LPC-DHA、炎症和 AD 病理恶化。为了解决这个问题，我们将DHA AD 和对照受试者大脑中含有 PC 和 LPC 物种，按不同的 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 变化的时间曲线和相应的 mfsd2a 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 在没有 mfsd2a 的情况下，apoE4 同工型的减少会导致 LPC-DHA 和游离 DHA 转运减少 如果增强 mfsd2a 表达可以抵消这些影响。我们将深入探讨 MMP9 在脂质转运至大脑中的基本作用并评估 MMP9 导向的影响 AD 中 mfsd2a 表达和 LPC-DHA 脑进入的治疗。 至此，我们已经有了初步数据 表明增加大脑脑血管系统中的 mfsd2a 会增加大脑 LPC-DHA 水平并降低 具有明确 AD 病理学的老年 E4FAD 小鼠的炎症。我们发现这些观察结果是 非常引人注目，因为 AD 疗法对于 1) 现有 AD 和 2) 那些患有 AD 的患者一直失败 携带ε4等位基因。这些初步发现显示出治疗这两种众所周知的耐药性的希望 人口。总体而言，这些研究将阐明 MMP9 介导的 mfsd2a 缺失导致的机制 减少大脑中 DHA 的摄取，此外，将探索增加 LPC-DHA 的治疗途径 转运到大脑中以预防和治疗 AD，特别是 ε4 携带者。