Inhibition of CD33-sialic acid binding in Late-Onset Alzheimer's Disease

迟发性阿尔茨海默病中 CD33-唾液酸结合的抑制

基本信息

批准号：
10752139
负责人：
Jennifer Leigh Green
金额：
$ 4.77万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2023
资助国家：
美国
起止时间：
2023-09-01 至 2026-08-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10752139
关键词：
Affinity Alanine Alzheimer&apos s Disease Alzheimer&apos s disease model Alzheimer&apos s disease patient Amyloid Amyloid beta-Protein Binding Binding Proteins Biological Assay Brain Cells Development Disease Progression Gene Expression Genes Genetic study Genotype Glycoproteins Human Immune Immune signaling Immunoprecipitation Impaired cognition In Vitro Individual Inflammatory Investigation Late Onset Alzheimer Disease Length Ligands Measures Mediating Methods Microglia Molecular Morphology Myeloid Cells Neurodegenerative Disorders PTPRC gene Pathogenesis Pathogenicity Pathology Pathway interactions Peptides Phase Phosphoric Monoester Hydrolases Predisposition Process Property Protein Isoforms Proteins Risk Risk Factors Role Senile Plaques Sialic Acids Signal Pathway Signal Transduction Solid Specificity Structure Surface TREM2 gene Testing Thick Western Blotting abeta accumulation amyloid pathology design experimental study genetic association genetic risk factor genome wide association study glial activation human model human old age (65+)improved in vitro Model in vivo imaging inhibitor insight monocyte neuron loss protein expression receptor response risk variant sialic acid binding Ig-like lectin sialic acid receptor targeted treatment tau Proteins uptake

项目摘要

PROJECT SUMMARY Alzheimer’s disease (AD) is a debilitating neurodegenerative disease characterized by progressive cognitive decline and pre-symptomatic accumulation of amyloid-beta (Aβ) and tau pathology with older age. AD pathogenesis is poorly understood, however genetic studies have clearly indicated a causal role for microglia, the innate immune cells of the CNS. Indeed, GWAS established the innate immune gene CD33 as a risk factor for Late-Onset AD (LOAD) in 2011. The CD33 LOAD associated rs3865444CC risk genotype is associated with diminished internalization of amyloid-β1-42 peptide, accumulation of neuritic amyloid pathology and fibrillar amyloid on in vivo imaging, and increased numbers of human microglia with small, thick processes, and a rounded morphology compared to the rs3865444AA protective genotype. Individuals with the LOAD associated rs3865444CC risk genotype have increased expression of full-length CD33, the isoform containing the sialic acid binding domain, compared to those with the rs3865444AA protective genotype, suggesting that the sialic- acid binding domain may be critical to the genetic association to AD. Based on the known inhibitory function of CD33, my hypothesis is that sialic acid mediated CD33 activation leads to microglial suppression, resulting in the inability to resolve inflammatory processes and mitigate pathogenic amyloid plaques, which may heighten susceptibility to neuronal loss and contribute to AD progression. To test this hypothesis, our lab developed an alternative approach for inhibiting CD33 function, by using peptides designed to bind to sialic acid to act as “decoy” receptors for sialic acid to reduce it’s binding to CD33 and inhibit CD33 signaling. I hypothesize that competitive inhibition of CD33 with sialic acid will reduce CD33 activation, restore microglial responsiveness, and increase Aβ uptake. The overarching objective of this proposal is to characterize the binding properties of these peptides and their inhibitory effects on CD33 activation and signaling (Aim 1) and then examine the functional responses of these peptides on immune pathways in vitro (Aim 2). In Aim 1, I will determine the potency and selectivity of peptides 1 and 2 in inhibiting CD33-sialic acid binding in a solid-phase binding assay I have optimized (Aim1a), determine the critical residues for efficacy through an alanine screen (Aim1b), and investigate the effects of the peptides on CD33 activation and signaling (Aim1c). In Aim 2, I will look at how human microglia functionally respond to treatment with peptides 1 and 2 in the context of AD using primary microglia-like cells from healthy donor and AD patients expressing the CD33 risk and protective genotypes by measuring gene expression changes in markers of microglial activation and amyloid uptake (Aim2a) and expression changes in key LOAD-associated immune-related proteins (Aim 2b).These experiments will provide insights to not only the mechanism of action of these peptides, but also to further clarify the role of CD33 and Siglec receptors in microglial activation, immune signaling pathways, and the pathogenesis of Alzheimer’s disease.

项目摘要阿尔茨海默氏病（AD）是一种令人衰弱的神经退行性疾病，其特征是进行性认知年龄较大的淀粉样蛋白β（Aβ）和TAU病理学的下降和症状前积累。广告发病机理知之甚少，但是遗传研究清楚地表明小胶质细胞的因果作用，中枢神经系统的先天免疫细胞。实际上，GWAS将先天免疫基因CD33建立为危险因素对于2011年晚发广告（负载）。与CD33负载相关的RS3865444CC风险基因型与淀粉样蛋白-β1-42肽的内在化减少，神经淀粉样蛋白病理学和原纤维的积累体内成像上的淀粉样蛋白，人类小胶质细胞的数量增加，较小，较厚的过程和A 与RS3865444AA受保护的基因型相比，圆形的形态。与负载相关的个人 RS3865444CC风险基因型的表达增加了全长CD33，含有唾液的同工型与具有RS3865444AA保护基因型的酸性结合结构域相比酸结合结构域对于与AD的遗传关联可能至关重要。基于已知的抑制功能 CD33，我的假设是唾液酸介导的CD33激活导致小胶质细胞抑制，从而导致无法解决炎症过程并减轻致病性淀粉样斑块，这可能会增强神经元丧失的敏感性并导致AD进展。为了检验这一假设，我们的实验室开发了抑制CD33功能的替代方法，通过使用旨在与唾液酸结合的肽充当唾液酸的“诱饵”受体可减少其与CD33的结合并抑制CD33信号传导。我假设这一点用唾液酸对CD33的竞争性抑制作用将降低CD33激活，恢复小胶质反应性，并增加Aβ的吸收。该提案的总体目的是表征这些宠物及其对CD33激活和信号传导的抑制作用（AIM 1），然后检查这些肽在体外对免疫途径的功能反应（AIM 2）。在AIM 1中，我将确定在固相结合测定中抑制CD33-硅酸结合中Petides 1和2的效力和选择性我已经优化了（AIM1A），确定通过丙氨酸屏幕（AIM1B）轻松的关键残差，然后研究Petides对CD33激活和信号传导的影响（AIM1C）。在AIM 2中，我将研究如何人类小胶质细胞在AD的背景下使用主要的肽1和2的治疗作用来自健康供体和AD患者的小胶质细胞样细胞表达CD33风险并通过测量小胶质激活和淀粉样蛋白摄取标记的基因表达变化（AIM2A）和关键负荷相关免疫相关蛋白的表达变化（AIM 2B）。这些实验将提供洞察不仅是这些肽的作用机理，而且还进一步阐明了CD33和小胶质激活，免疫信号通路和阿尔茨海默氏病的发病机理中的Siglec受体疾病。