Deciphering NRF2- Dysregulations and Oxidative Stress in Keratoconus Corneal Degeneration

Abstract

Purpose : Oxidative stress is considered to play a role in the pathogenesis of keratoconus. A recent study from our group identified reduced expression of several antioxidant genes and their regulatory transcription factor, NRF2, in individual keratoconus (KC) patient corneas. Poorly functioning antioxidants lead to the accumulation of reactive oxygen and nitrogen species that modify cellular macromolecules. Malondialdehyde (MDA), a component of NRF2 signaling pathway, is a reactive aldehyde byproduct of oxidative damage to cellular lipoproteins. To determine whether MDA can be used as a biomarker for KC, we measured MDA in the tear fluid of KC and control subjects. We are also examining expression of key antioxidant genes in the epithelia of KC and cadaver control donor corneas.

Methods : MDA levels were measured by ELISA in tear fluids of patients with KC (n=19), and healthy controls (HC; n=16). We assessed the mRNA expression of antioxidant genes Glutathione peroxidase 3 (GPX3), MAF bZIP transcription factor F (MAFF) and Peroxiredoxin 1 (PRDX1) in total RNA from epithelial scrapings of KC (n=4) and cadaver (n=4) corneal epithelial scrapings.

Results : We detected an increase in MDA (p≤0.01) in KC tear samples (204.36±118.37), compared to healthy controls (159.34±56.58). The KC corneal epithelium also exhibited significantly decreased expression of GPX3 (p≤0.0001) and MAFF (p≤0.017) suggesting diminished antioxidant activities in KC compared to healthy controls. Conversely, PRDX1, encoding another antioxidant enzyme (p≤0.033) was increased in KC.

Conclusions : Our study identified increased MDA levels in KC tear samples, supporting its potential use as a biomarker. Further studies on a larger cohort will determine whether levels of MDA and antioxidant gene expression changes correlate with disease severity or have prognostic capacities. We are also investigating the regulatory genes and signaling mechanisms underlying oxidative stress in keratoconus.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Demographic Characteristics of Study Participants