Absence of glutaredoxin1 increases lens susceptibility to oxidative stress induced by UVR-B

We investigated if the absence of glutaredoxin1, a critical protein thiol repair enzyme, increases lens susceptibility to oxidative stress caused by in vivo exposure to ultraviolet radiation type B (UVR-B). Glrx−/− mice and Glrx+/+ mice were unilaterally exposed in vivo to UVR-B for 15 min. Groups of 12 animals each received 4.3, 8.7, and 14.5 kJ/m2 respectively. 48 h post UVR-B exposure, the induced cataract was quantified as forward lens light scattering. Cataract morphology was documented with darkfield illumination photography. Glutathione (GSH/GSSG) content was analyzed in Glrx−/− and Glrx+/+ lenses. UVR-B exposure induced anterior sub-capsular cataract (ASC) in Glrx−/− and Glrx+/+ mice. In Glrx−/− lenses the opacities extended further towards the lens equator than in wild type animals (Glrx+/+). Lens light scattering in Glrx−/− mice was increased in all dose groups compared to lenses with normal glutaredoxin1 function. The difference was more pronounced with increasing exposure dose. Lens sensitivity for UVR-B induced damage was significantly higher in Glrx−/− lenses compared to Glrx+/+ lenses. The Glrx gene provides a 44% increase of protection against close to threshold UVR-B induced oxidative stress compared to the absence of the Glrx gene. In conclusion, the absence of glutaredoxin1 increases lens susceptibility to UVR-B induced oxidative stress in the mouse.