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Cyclooxygenase 2 expression in rat corneas after ethanol exposure.

Miyamoto T, Saika S, Ueyama T, Okada Y, Shirai K, Sumioka T, Fujita K, Ishiwaka N, Ohnishi Y

Department of Ophthalmology, Wakayama Medical University, Kimiidera, Wakayama-City, Wakayama, Japan. tmiyam@wakayama-med.ac.jp

PURPOSE: To evaluate the effects of ethanol exposure of the cornea on inflammation in corneal epithelium. SETTING: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. METHODS: One cornea of Wistar rats (n = 60) was exposed to ethanol 20% for 30 seconds. The animals were killed 0.5, 1.0, 1.5, 2.0, 6.0, 12.0, 24.0, 48.0, or 72.0 hours or 7 days after treatment. The paraffin section or cryosection of the treated eyes was processed for histology; immunohistochemistry for cyclooxygenase 2 (COX2); p65 subunit of nuclear factor kappa B (NF-kappaB), which is the major transcription factor involved in COX2 expression; phospho-IkappaB; or in situ hybridization for COX2 mRNA. RESULTS: In the uninjured corneas, faint immunoreactivity for COX2 was detected in the basal cells of the corneal epithelium, but not in other cell layers. Cyclooxygenase 2 mRNA was not observed in the injured epithelium; it was expressed 2 hours after ethanol exposure, but not 3 hours or later after treatment. The COX2 protein was detected in the corneal epithelium throughout the epithelial layers from 3 to 72 hours, but not at 7 days. The p65 of NF-kappaB translocated to the nuclei of corneal epithelium 3 to 24 hours after treatment but was not seen in the nuclei 48 hours after treatment. Phospho-I kappaB was detected in corneal epithelium 6 hours after treatment, but not 12 hours or later. CONCLUSION: Ethanol exposure activated NF-kappaB and upregulated COX2 expression, which may cause inflammation in corneal tissue.

Published 2 October 2006 in J Cataract Refract Surg, 32(10): 1736-40.
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