Rózanowska Małgorzata, Pawlak Anna, Rózanowski Bartosz, Skumatz Christine, Zareba Mariusz, Boulton Mike E, Burke Janice M, Sarna Tadeusz, Simon John D
Department of Biophysics, Faculty of Biotechnology, Kraków, Poland. School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom.
Invest Ophthalmol Vis Sci. 2004 Apr;45(4):1052-60. doi: 10.1167/iovs.03-0277.
Lipofuscin accumulates in human retinal pigment epithelium (RPE) cells with age and may be the main factor responsible for the increasing susceptibility of RPE to photo-oxidation with age. As the composition, absorption, and fluorescence of lipofuscin undergo age-related changes, the purpose of this study was to determine whether photoreactivity of lipofuscin granules also changes with the donor age.
To determine whether the photoreactivity of lipofuscin itself is age related, lipofuscin granules were isolated from human RPE and pooled into age groups. Photoreactivity was assessed by measuring action spectra of photo-induced oxygen uptake and photogeneration of reactive oxygen species. Separation of chloroform-soluble (ChS) and -insoluble (ChNS) components by Folch's extraction was used to determine the factors responsible for the age-related increase in lipofuscin photoreactivity.
The observed rates of photo-induced oxygen uptake and photo-induced accumulation of superoxide-derived spin adducts indicated that when normalized to equal numbers of lipofuscin granules, aerobic photoreactivity of lipofuscin increased with age. Both ChS and ChNS mediated photogeneration of singlet oxygen, superoxide radical anion, and photo-oxidation of added lipids and proteins. Although both ChS and ChNS exhibited substantial photoreactivities, neither exhibited significant age-related changes when normalized to equal dry mass. In contrast, ChNS contents in lipofuscin granules significantly increased with aging.
Aerobic photoreactivity of RPE lipofuscin substantially increases with aging. This effect may be ascribed to the increased content of insoluble components.
脂褐素随年龄增长在人视网膜色素上皮（RPE）细胞中蓄积，可能是RPE随年龄增长对光氧化敏感性增加的主要因素。由于脂褐素的组成、吸收和荧光会发生与年龄相关的变化，本研究的目的是确定脂褐素颗粒的光反应性是否也随供体年龄而改变。
为了确定脂褐素本身的光反应性是否与年龄相关，从人RPE中分离出脂褐素颗粒并按年龄组汇集。通过测量光诱导的氧摄取作用光谱和活性氧的光生成来评估光反应性。采用福尔克萃取法分离氯仿可溶（ChS）和不可溶（ChNS）成分，以确定导致脂褐素光反应性随年龄增加的因素。
观察到的光诱导氧摄取速率和超氧化物衍生自旋加合物的光诱导积累表明，当以相等数量的脂褐素颗粒进行归一化时，脂褐素的需氧光反应性随年龄增加。ChS和ChNS均介导单线态氧、超氧阴离子自由基的光生成以及添加脂质和蛋白质的光氧化。虽然ChS和ChNS都表现出显著的光反应性，但当以相等干质量进行归一化时，两者均未表现出显著的与年龄相关的变化。相反，脂褐素颗粒中的ChNS含量随衰老显著增加。
RPE脂褐素的需氧光反应性随衰老显著增加。这种效应可能归因于不溶成分含量的增加。
