Abstract
Purpose :
Chemical injuries to the eye are medical emergencies with limited acute treatment options. We developed a perfluorodecalin-based supersaturated oxygen emulsion (SSOE) to deliver high concentration of oxygen. We previously demonstrated that a single topical application of SSOE to the eye after alkali injury promotes corneal epithelial wound healing and reduces optical opacity and cataract formation in mice. Herein we aim to investigate the mechanisms underlying SSOE’s protective functions.
Methods :
Alkali burn was induced by placing a 2-mm-diameter filter paper soaked with 1M sodium hydroxide solution onto central cornea of BALB/C mice for 20 seconds, followed by PBS irrigation. SSOE containing 25% oxygen-carrier perfluorodecalin was manufactured in hyperbaric condition and applied to the cornea immediately after burn for 30 minutes. Tissue oxygen level was determined using a micro-oxygen sensor. Inflammatory cell infiltration, cytokine production, and cell signaling were determined using flow cytometry and RT-PCR. Cell death was determined with TUNEL staining.
Results :
After alkali burn, there was immediate tissue hypoxia (165.4 μmol/L to 66.1, p<0.0001) which was reversed by topical application of SSOE, but not un-oxygenated vehicle control. Hypoxia-inducible factor 1-alpha (Hif-1α), master regulators of tissue response to hypoxia, increased significantly up to 7 days in the cornea and conjunctiva after burn (percentage of Hif-1α positive cells 33.5% after burn vs 10.7% in naïve, and MFI 88.1 vs 31.2). SSOE led to a decrease in Hif-1α signaling initially at day 1 (22.6% and 59.6 for MFI) but not at day 7. SSOE also reduced CD45+ leukocytes infiltration and expression of IL-1β, IL-6, MMP9, and Cxcl1 at the ocular surface. At 1 hour after burn, nearly all cells in central corneas were TUNEL-positive; and by 4 hours, the lens epithelial cells stained positive for TUNEL. SSOE treatment significantly reduced cell death (TUNEL staining) in both the cornea and the lens epithelium.
Conclusions :
Topical application of perfluorodecalin-based oxygenated emulsion reduces intraocular hypoxia, Hif-1α signaling, leukocyte infiltration, production of inflammatory mediators, and cell death, thus protecting ocular tissues against alkali burn and hastening recovery of tissue integrity.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.