Quantitative Analysis of Aging Retina

描述（由申请人提供）：视网膜相关黄斑病变（ARM）是西方社会老年人无法治疗的视力丧失的主要原因。早期ARM的特征是视网膜下的脂肪沉积物知之甚少。我们建议：与动脉粥样硬化性心血管疾病一样，ARM涉及对血管内膜中含有载脂蛋白（apo）B的脂蛋白的保留的局部细胞反应，其中含有apoB的脂蛋白来源于视网膜色素上皮（RPE）。我们表明，酯化胆固醇和80 - 100 nm的固体颗粒存在于正常老化的布鲁赫膜（BrM），玻璃疣和基底沉积物含有胆固醇和载脂蛋白B，和RPE含有mRNA和蛋白质的载脂蛋白B和微粒体甘油三酯转移蛋白（MTTP），脂蛋白分泌细胞的标志。组成性RPE脂蛋白通路的扰动是形成胆固醇富集病变的合理机制。RPE脂蛋白的合理功能是从吞噬的感光细胞外节清除脂肪酸。我们的首要任务是证明RPE脂蛋白通路的存在并了解其正常功能。在人类的眼睛，我们将描述脂蛋白颗粒在孤立的玻璃疣和BrM，使用电子显微镜，免疫组织化学，密度梯度超声，和酶脂质测定。在培养的ARPE-19细胞中，我们将确定最佳的脂质加载方法，以便分泌颗粒的组分可以在化学和超微结构上表征，并且我们将确定调节MTTP活性对体外RPE脂蛋白组装和分泌的影响。在小鼠中，我们将研究在正常和明亮的光下，在光感受器吞噬作用后，全身施用特异性和有效的MTTP抑制剂对RPE中细胞内油滴形成的影响。我们的研究结果将是有价值的，在评估ARM和动脉粥样硬化性心血管疾病的共享机制方面的胞外脂蛋白积累和脂蛋白分泌细胞的细胞生物学的程度。需要这些信息来确定是否应该考虑改变肝脂蛋白产生的治疗来治疗早期ARM。

DESCRIPTION (provided by applicant): Age-related maculopathy (ARM) is the leading cause of untreatable vision loss among the elderly in Western society. Early ARM features poorly understood fatty deposits under the retina. We propose that: ARM, like atherosclerotic cardiovascular disease, involves local cellular response to the retention of an apolipoprotein (apo) B-containing lipoprotein in a vascular intima, with the twist that the apoB-containing lipoprotein derives from retinal pigment epithelium (RPE). We show that esterified cholesterol and 80-100 nm solid particles are present in normal aged Bruch's membrane (BrM), drusen and basal deposits contain cholesterol and apoB, and the RPE contains mRNA and protein for apoB and microsomal triglyceride transfer protein (MTTP), the hallmark of a lipoprotein secreting cell. Perturbation of a constitutive RPE lipoprotein pathway is a plausible mechanism for the formation of cholesterol-enriched lesions. A plausible function for an RPE lipoprotein is to clear fatty acids from phagocytosed photoreceptor outer segments. Our first priority is proving that an RPE lipoprotein pathway exists and learning its normal function. In human eyes, we will describe lipoprotein particles in isolated drusen and in BrM, using electron microscopy, immunohistochemistry, density gradient ultracentrifugation, and enzymatic lipid assays. In cultured ARPE-19 cells, we will determine the optimal method for lipid-loading so that the components of secreted particles can be characterized chemically and ultrastructurally, and we will determine the effect of modulating MTTP activity on RPE lipoprotein assembly and secretion in vitro. In mice, we will study the effect of systemic administration of specific and potent inhibitors of MTTP on the formation of intracellular oil droplets in RPE following photoreceptor phagocytosis in normal and bright light. Our results will be valuable in assessing the extent which ARM and atherosclerotic cardiovascular disease share mechanisms with regard to extracellular lipoprotein accumulation and the cell biology of lipoprotein secreting cells. This information is required to determine if treatments that modify hepatic lipoprotein production should be considered for treating early ARM.