Department of Ophthalmology, Wilmer Ophthalmological Institute, Johns Hopkins Hospital, Baltimore, Maryland 21287-9115, USA.
Br J Ophthalmol. 2011 Sep;95(9):1323-30. doi: 10.1136/bjo.2010.199216. Epub 2011 Jun 1.
There is increasing evidence that inflammation and immune-mediated processes (complement activation) play an important role in age-related macular degeneration (AMD) pathogenesis. A genetic variation in the gene encoding complement factor H (CFH) and plasma levels of C-reactive protein (CRP), a systemic marker of subclinical inflammation, have consistently been shown to be associated with an increased risk for AMD. In the present study, we examined the immunolocalisation of CRP and CFH in aged control human donor eyes (n=10; mean age 79 years) and eyes with AMD (n=18; mean age 83 years).
Alkaline phosphatase immunohistochemistry was performed using polyclonal antibodies against CRP and CFH on cryopreserved tissue sections from disc/macular blocks. Three independent masked observers scored the reaction product (0-8).
In aged control eyes, the retinal pigment epithelium/Bruch's membrane/choriocapillaris (RPE/BrM/CC) complex including intercapillary septa (ICS) had the most prominent immunostaining for CRP and CFH. CRP was significantly higher than controls in BrM/CC/ICS and choroidal stroma in early and wet AMD eyes (p<0.05). In contrast, CFH was significantly lower in BrM/CC/ICS complex of AMD choroids than in controls (p<0.05). Interestingly, CRP and CFH were significantly reduced in BrM/CC/ICS complex in atrophic area of macula in geographical atrophy (p<0.05). Drusen and basal laminar deposits were intensely positive for CRP and CFH.
These immunohistochemical findings show that changes in distribution and relative levels of CRP and CFH were evident in early and late AMD eyes. This suggests that high levels of CRP and insufficient CFH at the retina/choroid interface may lead to uncontrolled complement activation with associated cell and tissue damage. This study supports the hypothesis that inflammation and immune-mediated mechanisms are involved in the pathogenesis of AMD.
越来越多的证据表明，炎症和免疫介导的过程（补体激活）在年龄相关性黄斑变性（AMD）发病机制中起着重要作用。编码补体因子 H（CFH）的基因中的遗传变异和 C 反应蛋白（CRP）的血浆水平，一种亚临床炎症的系统标志物，一直与 AMD 的风险增加相关。在本研究中，我们检查了 CRP 和 CFH 在老年对照人供体眼中（n=10；平均年龄 79 岁）和 AMD 眼中（n=18；平均年龄 83 岁）的免疫定位。
使用针对 CRP 和 CFH 的多克隆抗体，通过碱性磷酸酶免疫组织化学在来自盘/黄斑块的冷冻组织切片上进行。三位独立的盲法观察者对反应产物（0-8）进行评分。
在老年对照眼中，视网膜色素上皮/布鲁赫膜/脉络膜毛细血管（RPE/BrM/CC）复合体包括毛细血管间隔（ICS）对 CRP 和 CFH 的免疫染色最明显。CRP 在早期和湿性 AMD 眼中的 BrM/CC/ICS 和脉络膜基质中明显高于对照组（p<0.05）。相比之下，AMD 脉络膜的 BrM/CC/ICS 复合体中的 CFH 明显低于对照组（p<0.05）。有趣的是，在地理萎缩的黄斑萎缩区，BrM/CC/ICS 复合体中的 CRP 和 CFH 明显降低（p<0.05）。玻璃膜疣和基底膜沉积物对 CRP 和 CFH 呈强阳性。
这些免疫组织化学发现表明，CRP 和 CFH 的分布和相对水平的变化在早期和晚期 AMD 眼中是明显的。这表明视网膜/脉络膜界面处 CRP 水平升高和 CFH 水平不足可能导致补体激活失控，伴有细胞和组织损伤。本研究支持炎症和免疫介导的机制参与 AMD 发病机制的假说。
