Homocysteine's role in Age-Related Macular Degeneration

同型半胱氨酸在年龄相关性黄斑变性中的作用

• 批准号: 10457086
• 负责人: Amany M Tawfik
• 金额: $ 25.34万
• 依托单位: OAKLAND UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10457086
• 关键词: Age related macular degeneration; Aging; Amino Acids; Biological Assay; Blindness; Blood; Cells; Choroidal Neovascularization; Cystathionine; Data; Development; Dietary Supplementation; Elderly; Endothelial Cells; Endothelium; Enzymes; Evaluation; Exhibits; Experimental Models; Fluorescein Angiography; Folic Acid; Functional disorder; Genetic; Glycolysis; Goals; Homocysteine; Human; Hyperhomocysteinemia; In Vitro; Intestinal Absorption; Joints; Knockout Mice; Lasers; Life Expectancy; Mediating; Medical; Metabolic; Metabolism; Mitochondria; Modality; Modeling; Modification; Molecular; Mus; N-Methyl-D-Aspartate Receptors; N-Methylaspartate; Optical Coherence Tomography; Oxidative Phosphorylation; Pathogenesis; Pathway interactions; Patients; Pharmacology; Phenotype; Photoreceptors; Population; Prevalence; Proteins; Reporting; Respiration; Retina; Risk; Role; SLC2A1 gene; Serum; Signal Pathway; Signal Transduction; Structure of retinal pigment epithelium; Testing; Therapeutic; Tight Junctions; Up-Regulation; Vascular Endothelial Growth Factors; Vision Disorders; Vitamin B 12; Vitamin B6; Vitamins; Wild Type Mouse; bevacizumab; conditional knockout; electric impedance; experimental study; fluorescein isothiocyanate dextran; folic acid supplementation; gene therapy; genetic manipulation; in vivo; inhibitor/antagonist; intravitreal injection; mouse model; overexpression; preservation; prevent; receptor; retinal damage; therapeutic target

Summary/Abstract Age-related macular degeneration (AMD) is the leading cause of vision loss in among elderly populations. Elevated homocysteine (Hcy), also known as hyperhomocysteinemia (HHcy) has been reported in patients with AMD; thereby suggesting an association between HHcy and the risk of AMD. Recently, we reported retinal changes similar to AMD in a mouse model of HHcy which lacks Cystathionine-β-synthase (cbs+/-) or received intravitreal injections of Hcy. These models showed significant retinal pigment epithelium (RPE) dysfunction and choroidal neovascularization (CNV) However, the lack of understanding the molecular/cellular mechanisms of these changes is a critical barrier in proposing Hcy as a therapeutic target in AMD. Our preliminary data show that HHcy-induced RPE dysfunction is associated with the upregulation of the N-methyl-D-aspartate (NMDAr) and GLUT1 receptors and increased glycolysis. Hence, we hypothesize that HHcy contributes to the pathogenesis of AMD via activation of the NMDAr and GLUT1 signaling pathways that induce the metabolic switch from oxidative phosphorylation to glycolysis. Therefore, elimination of excess Hcy through pharmacological or genetic intervention could be beneficial in the treatment of AMD. To test our hypothesis, we will conduct in vitro experiments, using RPE and choroidal endothelial cells (CEC) and in vivo using cbs+/-, wild type mice receiving intravitreal injection of Hcy and mice lacking the endothelial or RPE NMDAr (NMDAr-/-E or NMDAr-/-R respectively). Our specific aims include: 1: Testing the hypothesis that HHcy induces the metabolic switch from mitochondrial respiration to glycolysis via activation of GLUT1 in RPE cells: We will examine the changes in the retinal expression and localization of GLUT1, mitochondrial respiration, glycolysis and rate-limiting glycolytic enzymes in HHcy models. Moreover, we will determine the effect of GLUT1 inhibition on HHcy-induced RPE dysfunction and CNV. Aim 2: Testing the hypothesis that inhibition of NMDAr preserves RPE function and reduces the development of CNV under HHcy. We will examine the effects of pharmacological inhibition or genetic manipulation of the NMDAr on HHcy-induced RPE dysfunction and CNV. The effect of intravitreal injection of Hcy will be evaluated in NMDAr-/-E or NMDAr-/-R as compared to wild type and cbs+/- mice with or without NAMDAr inhibitors. Parallel in vitro experiments will be performed on RPE and CEC subjected to Hcy with or without NMDAr inhibitors followed by assessment of RPE function and angiogenic potential of CEC. Aim 3: Testing the hypothesis that elimination of excess Hcy by dietary supplementation or genetic/ pharmacological modifications prevents the progression of AMD. Hcy clearance will be enhanced in models of HHcy through two approaches, followed by assessment of RPE function and angiogenic potential of CEC: (a) Enhancing the remethylation pathway of Hcy metabolism using vitamins B6, B12 and folic acid supplementation. (b) Enhancing the transsulforation pathway of Hcy metabolism via CBS overexpression. Successful clearance of excess Hcy holds immense promise in the treatment of AMD.

摘要/摘要 与年龄相关的黄斑变性（AMD）是老年人群中视力丧失的主要原因。 据报道，升高的同型半胱氨酸（HCY），也称为高层同星菌血症（HHCY） amd;从而表明HHCY与AMD风险之间存在关联。最近，我们再次报道了 在缺乏胱硫醚-β合酶（CBS +/-）的HHCY小鼠模型中类似的变化或接收的变化 玻璃体内注射Hcy。这些模型显示出明显的残留色素上皮（RPE）功能障碍和 然而，脉络膜新生血管形成（CNV），缺乏了解分子/细胞机制 这些变化是提出HCY作为AMD的治疗靶点的关键障碍。我们的初步数据显示 HHCY诱导的RPE功能障碍与N-甲基-D-天冬氨酸（NMDAR）的上调有关 和GLUT1受体并增加糖酵解。因此，我们假设HHCY有助于 通过激活NMDAR和GLUT1信号通路，AMD的发病机理，诱导代谢 从氧化物磷酸化转变为糖酵解。因此，消除多余的HCY 药理或遗传干预可能对AMD的治疗有益。为了检验我们的假设，我们 将使用RPE和脉络膜内皮细胞（CEC）和体内使用CBS +/-，野外进行体外实验 接受玻璃体内注射的HCY和小鼠缺乏内皮或RPE NMDAR的小鼠（nmdar - / - e或 nmdar - / - r）。我们的具体目的包括：1：检验HHCY诱导的假设 通过在RPE细胞中激活GLUT1，从线粒体呼吸转向糖酵解的代谢转换：我们 将检查glut1的残留表达和定位的变化，线粒体呼吸， HHCY模型中的糖酵解和限速糖酵解酶。此外，我们将确定Glut1的效果 抑制HCY诱导的RPE功能障碍和CNV。目标2：检验抑制的假设 NMDAR保留RPE功能并减少HHCY下的CNV的发展。我们将检查 NMDAR的药物抑制或遗传操纵对HCY诱导的RPE功能障碍的影响 和CNV。与NMDAR - / - E或NMDAR - / - R相比 野生型和CBS +/-鼠标具有或没有NAMDAR抑制剂。将对体外实验进行平行 RPE和CEC受到或没有NMDAR抑制剂的HCY，然后评估RPE功能和 CEC的血管生成潜力。目标3：检验以下假设：消除饮食过多的HCY 补充或遗传/药理修饰可预防AMD的进展。 HCY 通过两种方法，HHCY模型将增强清除率，然后评估RPE功能 CEC的血管生成潜力：（a）使用维生素增强HCY代谢的再甲基化途径 B6，B12和补充叶酸。 （b）通过CBS增强HCY代谢的义务途径 过表达。成功清除过多的HCY在治疗AMD方面具有巨大的承诺。