Frank R N, Amin R H, Puklin J E
Kresge Eye Institute of Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Am J Ophthalmol. 1999 Jun;127(6):694-709. doi: 10.1016/s0002-9394(99)00032-x.
To test the hypothesis that neovascular age-related macular degeneration is related to oxidative stress involving the macular retinal pigment epithelium. This study investigated, as a function of age, levels of enzymes that defend tissues against oxidative stress in the macular retinal pigment epithelium of human eyes with this disease.
Surgical specimens of macular choroidal neovascular membranes from eyes with age-related macular degeneration and the macular regions of whole donor eyes with neovascular age-related macular degeneration or without evident ocular disease were studied by quantitative electron microscopic immunocytochemistry with colloidal gold-labeled second antibodies. Relative levels in retinal pigment epithelium cell cytoplasm and lysosomes were determined of five enzymes believed to protect cells from oxidative stress, as well as levels of the retinal pigment epithelium marker cytoplasmic retinaldehyde-binding protein, for comparison with the enzymes.
Copper, zinc superoxide dismutase immunoreactivity increased and catalase immunoreactivity decreased with age in cytoplasm and lysosomes from macular retinal pigment epithelium cells of normal eyes and eyes with age-related macular degeneration. Cytoplasmic retinaldehyde-binding protein immunoreactivity showed no significant relationship to age or the presence of neovascular age-related macular degeneration. Glutathione peroxidase immunoreactivity was absent from human retinal pigment epithelium cells. Both heme oxygenase-1 and heme oxygenase-2 had highly significantly greater immunoreactivity in retinal pigment epithelium cell lysosomes than in cytoplasm, differing from the much greater cytoplasmic immunoreactivity of the other proteins studied. This immunoreactivity decreased with age, particularly in the lysosomes of retinal pigment epithelium cells from eyes with neovascular age-related macular degeneration. These decreases were of borderline significance (P = .067 for heme oxygenase-1; P = .12 for heme oxygenase-2) when eyes with age-related macular degeneration were compared with normal eyes by multivariable logistic regression.
The high heme oxygenase-1 and heme oxygenase-2 lysosomal antigen levels in macular retinal pigment epithelium cells of eyes with neovascular age-related macular degeneration suggest that oxidative stress causes a pathologic upregulation of these enzymes. Increased lysosomal disposal may indicate that the reparative functions of these enzymes are accompanied by deleterious effects, necessitating their rapid removal from the cell. The much higher heme oxygenase-1 and heme oxygenase-2 antigen levels in macular retinal pigment epithelium cells from younger individuals suggest that protective mechanisms against oxidation and, hence, presumably to the development of age-related macular degeneration, decrease with age.
检验新生血管性年龄相关性黄斑变性与涉及黄斑视网膜色素上皮的氧化应激相关这一假说。本研究调查了患有该疾病的人眼黄斑视网膜色素上皮中作为年龄函数的、保护组织免受氧化应激的酶的水平。
通过用胶体金标记二抗的定量电子显微镜免疫细胞化学方法，研究了年龄相关性黄斑变性患者眼睛的黄斑脉络膜新生血管膜手术标本，以及患有新生血管性年龄相关性黄斑变性或无明显眼部疾病的全供体眼的黄斑区域。测定了视网膜色素上皮细胞质和溶酶体中五种被认为可保护细胞免受氧化应激的酶的相对水平，以及视网膜色素上皮标记物细胞质视黄醛结合蛋白的水平，以便与这些酶进行比较。
在正常眼睛和年龄相关性黄斑变性眼睛的黄斑视网膜色素上皮细胞的细胞质和溶酶体中，铜锌超氧化物歧化酶免疫反应性随年龄增加，而过氧化氢酶免疫反应性随年龄降低。细胞质视黄醛结合蛋白免疫反应性与年龄或新生血管性年龄相关性黄斑变性的存在无显著关系。人视网膜色素上皮细胞中不存在谷胱甘肽过氧化物酶免疫反应性。血红素加氧酶-1和血红素加氧酶-2在视网膜色素上皮细胞溶酶体中的免疫反应性均显著高于细胞质，这与所研究的其他蛋白质在细胞质中更高的免疫反应性不同。这种免疫反应性随年龄降低，尤其是在患有新生血管性年龄相关性黄斑变性的眼睛的视网膜色素上皮细胞溶酶体中。当通过多变量逻辑回归将年龄相关性黄斑变性眼睛与正常眼睛进行比较时，这些降低具有临界显著性（血红素加氧酶-1的P = 0.067；血红素加氧酶-2的P = 0.12）。
患有新生血管性年龄相关性黄斑变性的眼睛的黄斑视网膜色素上皮细胞中血红素加氧酶-1和血红素加氧酶-2溶酶体抗原水平较高，表明氧化应激导致这些酶的病理性上调。溶酶体处理增加可能表明这些酶的修复功能伴随着有害影响，需要将它们迅速从细胞中清除。年轻个体的黄斑视网膜色素上皮细胞中血红素加氧酶-1和血红素加氧酶-2抗原水平高得多，表明抗氧化保护机制以及因此可能与年龄相关性黄斑变性的发生相关的机制随年龄降低。
