AQUAPORINS MODULATION IN CHRONIC MUSTARD GAS KERATOPATHY CONDITION IN RABBIT CORNEAS IN VIVO

Abstract

Purpose : Aquaporins (AQPs) regulate corneal hydration, homeostasis, and repair in vivo. The mechanistic role of AQPs in chronic mustard gas keratopathy (MGK) is elusive. This study investigated changes in mRNA and protein levels of AQP1, AQP3, and AQP5 in age-matched normal, sulfur mustard (SM) injured, and SM injured and topical eyedrop (TED) treated rabbit corneas collected at 2-month and 4-month post SM injury.

Methods : New Zealand White Rabbits exposed to SM vapor (200 mg-min/m³ for 8 mins) were divided into 3 groups: Naïve, SM, and SM+TED (2 drops/day for 4 weeks). Clinical eyes examinations, fluorescein eye test, Schirmer’s tear tests, pachymetry, tonometry, and optical coherence tomography were performed. At 2-month and 4-month post SM-injury euthanasia was performed and corneas were harvested to prepare serial sections, mRNA, and cDNA. H&E, immunofluorescence, and qRT-PCR analyzed corneal anatomy, AQP1, AQP3, and AQP5 levels.

Results : SM-injured corneas in live rabbits showed a significant corneal haze, corneal edema, and enhanced tear flow, distressed stromal organization, reduced endothelial density, and neovascularization compared to naïve corneas. These clinical signs were significantly reduced in SM+TED corneas. H&E histology validated clinical observations. The SM-exposed rabbit cornea showed a significantly decreased AQP1 [(0.5±0.04 fold; p<0.001), AQP3 (0.62±0.01 fold; p<0.001) and AQP5 (0.75±0.05 fold; p<0.001)] at 2-month and AQP1 [(0.59±0.03 fold; p<0.001), AQP3 (0.35±0.04 fold; p<0.001) and AQP5 (0.43±0.05 fold; p<0.001)] at 4-month compared to naïve corneas. In corneas of SM+TED group, a significant rescue of lost AQPs levels was noted as evident from increased AQP1 [(2.18±0.03 fold; p<0.001), AQP3 (1.75±0.05 fold; p<0.001) and AQP5 (1.45±0.04 fold; p<0.001) levels at 2-month and AQP1 (1.84±0.03 fold; p<0.001), AQP3 (3.11±0.22 fold; p=0.004) and AQP5 (2.8±0.22 fold; p=0.03) expression at 4-month.

Conclusions : Aquaporins modulation in SM-injured and rescue in SM+TED corneas illustrations its potential for developing medical countermeasures for MGK. More studies are warranted.

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