Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, CO.
Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado, Aurora, CO.
Photochem Photobiol. 2017 Jul;93(4):1091-1095. doi: 10.1111/php.12717. Epub 2017 Feb 22.
Whether ascorbate oxidation is promoted by UVA light in human lenses and whether this process is influenced by age and GSH levels are not known. In this study, we used paired lenses from human donors. One lens of each pair was exposed to UVA light, whereas the other lens was kept in the dark for the same period of time as the control. Using LC-MS/MS analyses, we found that older lenses (41-73 years) were more susceptible to UVA-induced ascorbate oxidation than younger lenses (18-40 years). Approximately 36% of the ascorbate (relative to control) was oxidized in older lenses compared to ~16% in younger lenses. Furthermore, lenses with higher levels of GSH were less susceptible to UVA-induced ascorbate oxidation compared to those with lower levels, and this effect was not dependent on age. The oxidation of ascorbate led to elevated levels of reactive α-dicarbonyl compounds. In summary, our study showed that UVA light exposure leads to ascorbate oxidation in human lenses and that such oxidation is more pronounced in aged lenses and is inversely related to GSH levels. Our findings suggest that UVA light exposure could lead to protein aggregation through ascorbate oxidation in human lenses.
UVA 光是否会促进人眼晶状体中的抗坏血酸氧化，以及这一过程是否会受到年龄和 GSH 水平的影响，目前尚不清楚。在本研究中，我们使用了来自人类供体的成对晶状体。每对晶状体中的一只暴露在 UVA 光下，而另一只则在黑暗中放置相同的时间作为对照。通过 LC-MS/MS 分析，我们发现与年轻晶状体（18-40 岁）相比，年龄较大的晶状体（41-73 岁）更容易受到 UVA 诱导的抗坏血酸氧化。与年轻晶状体相比，老年晶状体中约有 36%的抗坏血酸（相对于对照）被氧化，而年轻晶状体中约有 16%被氧化。此外，GSH 水平较高的晶状体比 GSH 水平较低的晶状体更不容易受到 UVA 诱导的抗坏血酸氧化，而且这种效应与年龄无关。抗坏血酸的氧化导致活性 α-二羰基化合物水平升高。总之，我们的研究表明，UVA 光照射会导致人眼晶状体中的抗坏血酸氧化，而且这种氧化在老年晶状体中更为明显，并且与 GSH 水平呈负相关。我们的研究结果表明，UVA 光照射可能会导致人眼晶状体中的蛋白质通过抗坏血酸氧化而聚集。
