Acrolein exposure severely damages cornea, eyelids, conjunctiva and causes vision loss in rabbits in vivo

Abstract

Purpose: Acrolein was used recently in Syria and during World War I as a chemical weapon. It caused severe eye, skin and lung problems besides many casualties. At present, no animal model exists, to study acrolein’s toxicity to eye. We sought to develop an in-vivo rabbit model to understand mechanisms causing blindness by assessing damages to the cornea, conjunctiva, eyelids and sclera, and identify potential targets for developing antidotes for acrolein’s toxicity.

Methods: New Zealand White rabbits were used. Eyes were exposed to varied acrolein conc (0.5M, 2M, 6M or 10M) for 1 min. Slit-lamp biomicroscopy and eye examination were performed before and after acrolein exposure at 0h, 4h, 24h, 3day, 7day, 10day and 14day and record to analyze ocular inflammation and corneal pathology. Cornea, eyelid and sclera tissues were harvested and cryo-preserved for histology and various assays. H&E and immunofluorescence study investigated the role of macrophages, neutrophils and lymphocytes, keratocyte density, in damage cornea and other ocular tissues. Tissue lysates were used to quantify oxidative stress, glutathione peroxidase, superoxide dismutase, total lipid peroxidation and eicosanoids.

Results: Acrolein caused severe inflammation, irritation, and damage to cornea, eyelids and sclera within 15 min of exposure. This pathology and vision loss enhanced over time. The damages to cornea, eyelid and conjunctiva were dose dependent. High acrolein concentrations (6M and 10M) caused severe morbidity, thus animals were humanely euthanized after 4h or 24h. Dramatically increased leukocyte invasion, leukotriene LTB4 (2.5 fold) and reactive oxygen species levels (5 fold) and remarkably decreased glutathione levels (40-60%; p <0.01) were detected in eyelid and corneal tissues. All acrolein-exposed eyes developed eyelid and meibomian gland dysfunction, corneal fibrosis and neovascularization by day5; pathology deteriorated by day14. H&E and immunofluorescence detected exceptionally increased levels of TGFβ, VEGF, keratocyte death, invading-vessels, and neutrophils in corneal sections.

Conclusions: Acrolein causes severe acute ocular inflammation, corneal damage and vision loss. TGFβ, VEGF, leukotrienes and glutathione are attractive targets to counter acrolein’s toxicity. More in-vivo studies are warranted.