Abstract
Purpose :
We have previously developed a model of lens ageing using hyperbaric oxygen (HBO) treatment of ex vivo bovine lenses. While this model induced some of the biochemical characteristics of ageing, no overt cataract was observed. Therefore, we aimed to assess the effects of a physiologically relevant wavelength of ultraviolet (UV) light as an additional environmental oxidative stress to lens transparency.
Methods :
Bovine lenses were exposed to one of three doses (0.11 J cm-2, 25 J cm-2, 152 J cm-2) of UV-A light (365 nm). UV treated lenses, and their incubation controls, were assessed for transparency (using light/dark field microscopy) and then microdissected into outer cortex (OC), inner cortex (IC) and core (C) regions. Lens regions were homogenised for quantification of lipid peroxidation (using a malondialdehyde assay) and glutathione, to assess changes in oxidative stress. Mass spectrometry imaging (MSI) of axial tissues sections was used to map specific changes in lens metabolites. Finally, changes to lens proteins were assessed using Western blotting to assess protein mixed disulphide (e.g. PSSC and PSSG) formation, and gel electrophoresis to assess formation of high molecular weight protein aggregates.
Results :
Regardless of the UV dose, all lenses remained transparent post-UV exposure. The highest dose of UV caused the biggest increase in MDA compared to control lenses, in all regions of the lens, but predominantly in the IC (P= <0.05). MSI showed that all of the UV doses caused an increase in glutathione-cysteine disulfide (CySSG), in the inner cortex of the lens when compared to untreated lenses. Preliminary results suggest that high doses of UV cause an increase in protein aggregation within the lens.
Conclusions :
The increase in lipid peroxidation and the formation of CySSG shows that high doses of UVA light induce oxidative stress within the bovine lens. Furthermore, the formation of CySSG by oxidation of glutathione in the inner cortex of the lens suggests that UV-A is able to penetrate into the deeper layers of the lens. In future experiments we will determine whether UVA as an oxidative stress can induce cataract in bovine lenses pre-treated with HBO to deplete glutathione levels.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.