Loss of NQO1 exacerbates female susceptibility to the development of Fuchs dystrophy in response to ultraviolet light.

Abstract

Purpose : Fuchs endothelial corneal dystrophy (FECD) is a genetic, female-predominant disorder that leads to degenerative loss of corneal endothelial cells (CEnCs). Previously, we have reported a decrease in [NAD(P)H: quinone oxidoreductase 1 (NQO1)], an estrogen metabolite detoxifying enzyme, and upregulation of CYP1B1, known to induce estrogen metabolism, in FECD. In this study, we investigated the role of NQO1 in causing female susceptibility to UVA-induced damage seen in FECD.

Methods : NQO1+/+ and NQO1-/- male and female mice were irradiated with UVA (500 J/cm²). CEnCs were imaged using Heidelberg Retinal Imaging Rostock Corneal module (HRT-RCT) and quantified manually at weeks 1, 2 and 4 post-UVA. For in vitro studies, NQO1+/+ and NQO1-/- cells were treated with UVA (5 J/cm²) and CYP1B1 activation was detected by western blot.

Results : At week 2 post-UVA, NQO1-/- male mice demonstrated significantly decreased CEnC number (17%) compared to NQO1+/+ male mice. [Control NQO1+/+ male: 2259 ± 49, UVA NQO1+/+ male: 2105± 29, (6.8 % decrease); Control NQO1-/- male: 2331± 39, UVA NQO1-/- male: 1748±29, (25% decrease)]. Furthermore, NQO1-/- female mice had a significantly greater decrease in CEnC number (21%) compared to NQO1+/+ female. [Control NQO1+/+ female: 2271± 45, UVA NQO1+/+ female: 1705± 20, (25 % decrease); Control NQO1-/- female: 2310±25, UVA NQO1-/- female: 1255± 68, (46% decrease)]. Overall, NQO1-/- female had approximately 5 % more CEnC loss than NQO-/- male, indicating increased female susceptibility to UVA-induced oxidative stress. Interestingly, NQO1+/+ females had similar CEnC loss to NQO1-/- males, indicating that the absence of NQO1 in males creates a similar cell loss seen in wild-type females when exposed to UVA. At week 4 post-UVA, NQO1+/+ female mice had 16% more CEnC loss compared to cell loss at week 2. CYP1B1 protein levels were upregulated (2 fold, p< 0.05) in NQO1-/- cells compared to NQO1+/+ 24 hours post-UVA.

Conclusions : Our study indicates that NQO1 deficiency accelerates UVA-induced CEnC loss, which is further exacerbated in female NQO1-null mice when compared to males. Upregulation of CYP1B1 under NQO1 loss likely leads to increased reactive estrogen production and DNA damage seen in FECD. This study highlights the importance of studying impaired estrogen metabolism in order to understand sex differences in FECD.

This is a 2020 ARVO Annual Meeting abstract.