Chowers Itay, Wong Robert, Dentchev Tzvete, Farkas Ronald H, Iacovelli Jared, Gunatilaka Tushara L, Medeiros Nancy E, Presley J Brett, Campochiaro Peter A, Curcio Christine A, Dunaief Joshua L, Zack Donald J
Department of Ophthalmology, Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
Invest Ophthalmol Vis Sci. 2006 May;47(5):2135-40. doi: 10.1167/iovs.05-1135.
Iron can cause oxidative stress, and elevated iron levels have been associated with several neurodegenerative diseases including age-related macular degeneration (AMD). Transferrin, an iron transport protein, is expressed at high levels in the retina. The purpose of this study was to assess transferrin involvement in AMD by determining the expression profile of transferrin in retinas with AMD compared with retinas without evidence of disease.
Postmortem retinas were obtained from AMD and non-AMD eyes. Expression of transferrin was assessed in a microarray dataset from 33 retinas of unaffected donors and 12 retinas of patients with AMD (six with neovascular AMD and six with non-neovascular AMD). Quantitative real-time RT-PCR (QPCR) was used to confirm the microarray results. Transferrin protein expression was assessed by semiquantitative Western blot analysis and immunohistochemistry.
In comparison to unaffected retinas, mean transferrin mRNA levels, as measured by microarray analysis were elevated 3.5- and 2.1-fold in non-neovascular and neovascular AMD retinas, respectively. Semiquantitative Western blot analysis demonstrated a 2.1-fold increase in transferrin protein in AMD eyes. Immunohistochemistry showed more intense and widespread transferrin label in AMD maculas, particularly in large drusen, Müller cells, and photoreceptors.
These data demonstrate that transferrin expression is increased in the retinas of patients with AMD relative to those of healthy control patients of comparable age. Along with previous studies that have demonstrated elevated iron levels in AMD retinas, early onset drusen formation in a patient with retinal iron overload resulting from aceruloplasminemia, and retinal degeneration with some features of macular degeneration in the iron-overloaded retinas of ceruloplasmin/hephestin knockout mice, the present study suggests that altered iron homeostasis is associated with AMD.
铁可引起氧化应激，铁水平升高与包括年龄相关性黄斑变性（AMD）在内的多种神经退行性疾病有关。转铁蛋白是一种铁转运蛋白，在视网膜中高水平表达。本研究的目的是通过确定AMD视网膜与无疾病证据的视网膜中转铁蛋白的表达谱，评估转铁蛋白在AMD中的作用。
从AMD和非AMD眼中获取死后视网膜。在一个包含33名未受影响供体的视网膜和12名AMD患者（6名新生血管性AMD患者和6名非新生血管性AMD患者）视网膜的微阵列数据集中评估转铁蛋白的表达。采用定量实时RT-PCR（QPCR）来确认微阵列结果。通过半定量蛋白质免疫印迹分析和免疫组织化学评估转铁蛋白的蛋白表达。
与未受影响的视网膜相比，通过微阵列分析测得，非新生血管性和新生血管性AMD视网膜中转铁蛋白mRNA的平均水平分别升高了3.5倍和2.1倍。半定量蛋白质免疫印迹分析表明AMD眼中转铁蛋白增加了2.1倍。免疫组织化学显示AMD黄斑中转铁蛋白标记更强烈且分布更广，尤其是在大的玻璃膜疣、Müller细胞和光感受器中。
这些数据表明，与年龄相当的健康对照患者相比，AMD患者视网膜中转铁蛋白表达增加。连同先前的研究表明AMD视网膜中铁水平升高、因血浆铜蓝蛋白缺乏导致视网膜铁过载的患者早期出现玻璃膜疣形成，以及血浆铜蓝蛋白/亚铁氧化酶敲除小鼠铁过载视网膜中出现具有黄斑变性某些特征的视网膜变性，本研究提示铁稳态改变与AMD有关。
