Antifungal activity of amyloid beta as a driver of dementia and AD pathogenesis.

β 淀粉样蛋白的抗真菌活性是痴呆和 AD 发病机制的驱动因素。

• 批准号: 10711875
• 负责人: ANGIE GELLI
• 金额: $ 37.42万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-15 至 2024-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10711875
• 关键词: Abeta clearance; Adult; Aged, 80 and over; Alzheimer' s Disease; Alzheimer' s disease patient; Amyloid beta-Protein; Amyloid beta-Protein Precursor; Animal Model; Animals; Antifungal Agents; Area; Autopsy; Binding Proteins; Blood - brain barrier anatomy; Blood brain barrier dysfunction; Brain; Brain region; Candida; Cell Wall; Cells; Central Nervous System; Cerebrospinal Fluid; Chitin; Cryptococcus; Cryptococcus neoformans; Cryptococcus neoformans infection; Data; Decision Making; Dementia; Diagnosis; Endothelium; Environment; EphA2 Receptor; Exhibits; Freezing; Functional disorder; Fungal Components; Fungal DNA; Fungal Spores; Gene Expression Profile; Genes; Health; Human; Immunity; Impaired cognition; Impairment; Infection; Inflammation; Inflammatory; Inhalation; Innate Immune Response; Invaded; Mediating; Mediator; Memory Loss; Meningoencephalitis; Mission; Moods; Mus; Mycoses; Nature; Neurodegenerative Disorders; Neurologic Symptoms; Neuronal Injury; Neurons; Oxidative Stress; Pathogenesis; Patients; Polysaccharides; Process; Proliferating; Property; Proteins; Regulation; Reporting; Reproduction spores; Research; Research Project Grants; Role; Sampling; Senile Plaques; Signal Transduction; Structure; Structure of parenchyma of lung; Temperament; Testing; Tissues; United States National Institutes of Health; abeta deposition; aerosolized; amyloid precursor protein processing; antimicrobial; blood damage; brain endothelial cell; brain tissue; experience; extracellular; fungus; improved; in vitro Model; in vivo; long term memory; mouse model; neuroinflammation; neurotropic; parent grant; parent project; pathogenic fungus; therapeutic development

PROJECT ABSTRACT The blood-brain barrier (BBB) is a highly-restrictive structure that protects the central nervous system (CNS). Few fungal pathogens, such as Cryptococcus neoformans (Cn), can breach the BBB and invade the CNS. Fungal spores are prevalent in our environment and we become infected following inhalation of aerosolized spores. Once inhaled, spores of Cn proliferate in lung tissue and disseminate to the CNS due to their neurotropic nature. Cn is the leading cause of fungal meningoencephalitis in adults and it is often misdiagnosed as Alzheimer’s Disease (AD) due to similar neurological symptoms. Indeed, cognitive impairment was reported in 61% of subjects at least one year following Cn infection diagnosis. In AD, inflammatory and infectious processes promote BBB dysfunction underscoring the potentially critical role of the amyloid precursor protein (APP) in endothelial inflammation of the BBB and its subsequent dysfunction. We resolved the transcriptional signature of human brain microvascular endothelial cells (BMECs) infected with Cn. BMECs challenged with Cn showed significant dysregulation of several genes essential to the proper function of the brain endothelium (i.e. BBB), including EphA2-receptor tyrosine kinase, a key mediator of BBB dysfunction during Cn challenge (based on studies from our parent grant). We also identified APBB3 (amyloid beta precursor binding protein 3) as a potential mediator of BBB dysfunction. APBB3 is an uncharacterized protein whose role in APP processing/regulation has never been examined. Our results are consistent with similar changes reported in the abnormal BBB in AD pathogenesis. Reduced BBB integrity is associated with neuroinflammation, neuronal injury, oxidative stress and faulty clearance of amyloid beta (A). Based on our data we propose that fungal brain infection causes BBB dysfunction in part by dysregulating APP and reducing A clearance which would further damage the BBB. Our data are consistent with recent reports that found various brain regions from AD patients at autopsy infected with different species of fungi. Fungal DNA, proteins and structures were identified in frozen brain tissue from AD patients, but not from control patient tissue. Moreover fungal material was detected intra- and extracellularly in neurons from AD patients. Chitin polysaccharides, a key component of fungal cell walls, were also identified and human AD cerebral spinal fluid samples further confirmed the presence of fungi, including Cryptococcus and Candida. Indeed, following these recent discoveries, and the proposed antimicrobial properties of A a new AD hypothesis referred to as “antimicrobial protection hypothesis” has emerged. This hypothesis suggests that deposition of A plaque in brain can initiate early innate immune responses, where A entraps and neutralizes the invading fungal pathogen under normal conditions. The proposed supplement research project will address 2 specific aims that are an extension of the parent project and are fundamentally relevant to the pathogenesis of AD. The following specific aims will test the hypothesis that brain fungal infection dysregulates APP via APBB3 and the resulting antifungal immunity activity of amyloid beta (A) is mediated by EphA2- signaling. Specific aim 1 will examine the role of APP in BBB dysfunction in a mouse model of fungal brain infection. APP and APBB3 activity and their effects on BBB integrity will be examined in wild type and ephA2-/- mice infected with Cn. The physical interaction of A peptides with fungal cells will be examined in vivo and direct effects of A peptides on BBB integrity will be assessed in BBB spheroids, a highly-relevant in vitro model of the BBB. Specific aim 2 will determine whether A exhibits antifungal activity or induces antifungal immunity activity via EphA2-mediated signaling. We have performed several animal studies to resolve mechanisms of fungal brain pathogenesis by examining EphA2 activity in BBB dysfunction, however we have not examined neurological markers of AD in the context of cryptococcal brain infection. Given our expertise in animal models of fungal infection and experience working with in vitro models of the BBB, the studies proposed below are a natural segue to exploring an exciting and potentially ground breaking area of AD pathogenesis and therapeutic development.

项目摘要 血脑屏障（BBB）是一种高度限制的结构，可保护中枢神经系统 （CNS）。很少有真菌病原体，例如新型虫（CN），可以违反BBB并入侵 CNS。真菌孢子在我们的环境中普遍存在，事故发生后我们被感染 气溶性孢子。一旦继承，CN的孢子在肺组织中增殖，并由于 他们的神经性质。 CN是成人真菌脑膜脑炎的主要原因，通常是 由于类似的神经系统符号，误诊为阿尔茨海默氏病（AD）。确实，认知 CN感染诊断后至少一年的受试者中有61％的受试者据报道受损。在广告中， 炎症和传染性过程促进了BBB功能障碍，强调了潜在的关键作用 BBB内皮炎症及其随后的功能障碍中的淀粉样蛋白前体蛋白（APP）。 我们解决了感染的人脑微血管内皮细胞（BMEC）的转录特征 与CN。受到CN挑战的BMEC显示出适当的几种基因的明显失调 脑内皮（即BBB）的功能，包括Epha2受体酪氨酸激酶，BBB的关键介体 CN挑战期间的功能障碍（基于我们父母赠款的研究）。我们还确定了APBB3（淀粉样蛋白 β前体结合蛋白3）作为BBB功能障碍的潜在介体。 APBB3是一个未表征的 从未研究过其在应用程序处理/调节中的作用的蛋白质。我们的结果与 AD发病机理中BBB异常的类似变化。降低的BBB完整性与 神经炎症，神经元损伤，氧化应激和淀粉样ββ（A）的清除率故障。基于我们 数据我们提出，真菌脑感染会导致BBB功能障碍，部分原因是使应用程序失调和减少 清除将进一步损坏BBB。我们的数据与最新报告一致 来自尸检的AD患者的各种大脑区域感染了不同种类的真菌。真菌DNA， 在AD患者的冷冻脑组织中鉴定出蛋白质和结构，但不能来自对照患者 组织。此外，在AD患者的神经元中，在神经元内检测到了真菌材料。几丁质 多糖也是真菌细胞壁的关键组成部分，也被鉴定 流体样品进一步证实了真菌的存在，包括加密摄氏和念珠菌。确实，跟随 这些最新发现，以及新的AD假设的拟议抗菌特性 随着“抗菌保护假设”的出现。该假设表明A斑块的沉积 在大脑中可以发起早期的先天免疫反应，其中a陷入困境并中和入侵的真菌 在正常情况下病原体。拟议的补充研究项目将解决2个具体目标 这是母体项目的扩展，并且与AD的发病机理有根本相关。 以下特定目标将检验以下假设：脑真菌感染通过APBB3和 淀粉样蛋白β（A）产生的抗真菌免疫活性是通过EPHA2信号介导的。具体目标 1将检查APP在真菌脑感染小鼠模型中BBB功能障碍中的作用。 APP和APBB3 活性及其对BBB完整性的影响将在感染CN的野生型和EPHA2 - / - 小鼠中检查。 A肽与真菌细胞的物理相互作用将在体内检查和A的直接影响 BBB完整性上的肽将在BBB球体中评估，BBB球体是BBB的高度相关的体外模型。 特定的目标2将确定A是否表现出抗真菌活性或诱导抗真菌免疫活性 通过EPHA2介导的信号传导。我们已经进行了几项动物研究来解决真菌的机制 通过检查BBB功能障碍中的EPHA2活性，脑发病机理，但是我们尚未检查 在隐球菌脑感染的背景下，AD的神经系统标记。鉴于我们在动物模型方面的专业知识 在真菌感染和与BBB体外模型一起工作的经验中，下面提出的研究是一个 自然选择，探索AD发病机理和 治疗发展。