Screening for LXR agonists-inhibitors of brain amyloidosis and inflammation

筛选 LXR 激动剂 - 脑淀粉样变性和炎症抑制剂

• 批准号: 7449780
• 负责人: ILIYA LEFTEROV
• 金额: $ 22.42万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-15 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7449780
• 关键词: Academia; Accounting; Active Sites; Address; Affect; Agonist; Alzheimer' s Disease; Amyloid; Amyloid deposition; Amyloidosis; Apolipoprotein E; Astrocytes; Behavioral; Biological Assay; Biological Models; Brain; Cell Line; Cells; Chemicals; Cholesterol; Cholesterol Homeostasis; Classification; Clinical; Clinical Research; Clinical Trials; Complex; Data; Deposition; Development; Disease; Disease model; Drug Industry; Endopeptidases; Evaluation; Fatty Acids; Gene Expression; Generations; Genes; Genetic Transcription; Goals; Impaired cognition; In Vitro; Industry; Inflammation; Inflammatory; Knock-out; Laboratories; Lead; Ligands; Link; Lipoproteins; Liver; Mediating; Membrane; Messenger RNA; Metabolic Pathway; Microglia; Molecular; Mus; Nerve Degeneration; Neurons; Nuclear; Numbers; Outcome; Pathogenesis; Pathway interactions; Patients; Peptide Hydrolases; Pharmaceutical Preparations; Phospholipids; Physiological; Preclinical Drug Evaluation; Process; Production; Proteolytic Processing; Public Health; Reaction; Reporter; Screening procedure; Testing; Therapeutic; Transgenic Mice; Triglycerides; Up-Regulation; Vaccination; activating transcription factor; amyloid formation; base; cholesterol transporters; cytokine; design; disease phenotype; drug discovery; extracellular; in vivo; in vivo Model; inhibitor/antagonist; neuronal survival; novel therapeutics; prevent; receptor; response; secretase; small molecule; transcription factor

DESCRIPTION (provided by applicant): Despite the enormous efforts in academia and in pharmaceutical industry, Ab vaccination, y- and b-secretase inhibitors are still far from clinical use. Drugs that ameliorate AD phenotypes by interfering cholesterol metabolism have been also suggested, but the rationale for using those is poorly defined and in all of the cases the molecular mechanisms which account for their beneficial effects are poorly understood. Therefore there remains a great need for other strategies of lowering Ab. Nuclear Liver X receptors (LXRa and LXRb) are transcription factors that control the expression of genes involved in cholesterol metabolism. We have found that activated LXR regulate metabolic pathways of brain cholesterol intra- and extracellular transport that influence APP processing, b-amyloid deposition and its clearance from brain. Moreover, we and others have shown, that treatments of neuronal cell lines and primary neurons with natural or synthetic LXR ligands decrease Ab secretion, and that in vivo treatment of young AD model mice with a synthetic LXR ligand, increased the expression of LXR responsive genes in CNS and decreased soluble b-amyloid levels in their brains. We have also found that the application of LXR ligands inhibited secretion of inflammatory cytokines and increased neuronal survival following Ab or LPS treatment. The ultimate beneficial outcome of LXR ligand treatment on AD phenotype in vivo is a combination of effects mediated by genes expressed in neurons and astrocytes influencing Ab generation, b-amyloid formation and clearance, and by genes expressed in microglia which are tightly related to both - Ab clearance and inflammation. The data therefore substantiate the design of a drug discovery study for identification of LXR activators/agonists and their systematic evaluation in well established in vitro and in vivo model systems. In Specific aim 1, the activated status of LXR will be evaluated by their ability to increase dramatically the transcription of ABCA1 - a major LXR response gene. Thus, the increased amount of ABCA1 mRNA following in vitro application of a given compound (altogether >50,000 for screening) will serve as a reporter for LXR activation. Compounds that meet the criteria for LXR activation will be further screened for their ability to reduce Ab production in vitro. "Hits" with dual stimulatory effect on ABCA1 expression and apoE secretion, ability to reduce Ab and to facilitate cholesterol efflux will be further characterized in LXR knockout cell based assays. In addition, potent compounds will be characterized for their inhibitory effects on cytokine expression and regulatory effects on transcriptional activity of genes with undesired effects on fatty acids and triglyceride synthesis. In Specific Aim 2, the two most potent compounds will be chosen for initial in vivo tests in PS1APP transgenic mice. PUBLIC HEALTH RELEVANCE: Despite the enormous efforts in academia and in pharmaceutical industry, drugs based on the recent progress in our understanding for Alzheimer disease are still not available for clinical use. Brain cholesterol metabolism and its relation to different aspects of the disease pathogenesis substantiates the development of new therapeutic approaches based on complex regulatory networks controlled by transcription factors and their responsive genes. We are proposing a drug screening approach for identification of natural or synthetic compounds that activate transcription factors called Nuclear Liver X receptors (LXRa and LXRb) and therefore lead to upregulation and increased expression of genes involved in cholesterol metabolism. This drug discovery study is based on data generated in our and other laboratories which confirm that LXR controlled cholesterol transporters and lipoproteins in brain are involved in b-amyloid aggregation, deposition and clearance. Therefore, LXR activators can be used for lowering Ab inhibition of inflammation and improvement of behavioral deficits.

描述（由申请人提供）：尽管学术界和制药行业付出了巨大的努力，但抗体疫苗接种、γ-和β-分泌酶抑制剂距离临床应用仍很遥远。还提出了通过干扰胆固醇代谢来改善 AD 表型的药物，但使用这些药物的基本原理尚不清楚，并且在所有情况下，对其有益作用的分子机制知之甚少。因此，仍然非常需要其他降低抗体的策略。核肝 X 受体（LXRa 和 LXRb）是控制胆固醇代谢相关基因表达的转录因子。我们发现激活的 LXR 调节脑胆固醇细胞内和细胞外运输的代谢途径，从而影响 APP 加工、b-淀粉样蛋白沉积及其从大脑中的清除。此外，我们和其他人已经证明，用天然或合成的 LXR 配体处理神经元细胞系和原代神经元会减少 Ab 分泌，并且用合成的 LXR 配体对年轻 AD 模型小鼠进行体内处理，增加 LXR 响应基因的表达中枢神经系统中的β-淀粉样蛋白水平降低，并且大脑中可溶性β-淀粉样蛋白水平降低。我们还发现，使用 LXR 配体可抑制炎症细胞因子的分泌，并增加 Ab 或 LPS 治疗后神经元的存活率。 LXR 配体治疗体内 AD 表型的最终有益结果是由神经元和星形胶质细胞中表达的影响 Ab 生成、b-淀粉样蛋白形成和清除的基因以及小胶质细胞中表达的基因介导的效应组合，这些基因与以下两者密切相关：抗体清除和炎症。因此，这些数据证实了用于鉴定 LXR 激活剂/激动剂的药物发现研究的设计及其在完善的体外和体内模型系统中的系统评估。在具体目标 1 中，LXR 的激活状态将通过其显着增加 ABCA1（主要 LXR 反应基因）转录的能力来评估。因此，体外应用给定化合物后增加的 ABCA1 mRNA 量（总共 >50,000 用于筛选）将作为 LXR 激活的报告基因。符合 LXR 激活标准的化合物将进一步筛选其在体外减少抗体产生的能力。对 ABCA1 表达和 apoE 分泌具有双重刺激作用的“命中”、减少 Ab 和促进胆固醇流出的能力将在基于 LXR 敲除细胞的测定中进一步表征。此外，有效化合物的特征在于其对细胞因子表达的抑制作用和对基因转录活性的调节作用，并对脂肪酸和甘油三酯合成产生不良影响。在具体目标 2 中，将选择两种最有效的化合物在 PS1APP 转基因小鼠中进行初步体内测试。公共健康相关性：尽管学术界和制药行业做出了巨大努力，但基于我们对阿尔茨海默病的理解的最新进展的药物仍然无法用于临床。脑胆固醇代谢及其与疾病发病机制不同方面的关系证实了基于转录因子及其响应基因控制的复杂调节网络的新治疗方法的发展。我们提出了一种药物筛选方法，用于鉴定天然或合成化合物，这些化合物可激活称为核肝 X 受体（LXRa 和 LXRb）的转录因子，从而导致参与胆固醇代谢的基因上调和表达增加。这项药物发现研究基于我们和其他实验室产生的数据，这些数据证实大脑中 LXR 控制的胆固醇转运蛋白和脂蛋白参与 b-淀粉样蛋白聚集、沉积和清除。因此，LXR激活剂可用于降低抗体对炎症的抑制并改善行为缺陷。