Expression of cyclooxygenase-2 in corneal cells after photorefractive keratectomy and laser in situ keratomileusis in rabbits
Accepted 6 April 2004.
Purpose
To compare the expression pattern of cyclooxygenase-2 (COX-2) in rabbit corneal cells after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) with the same refractive correction.
Setting
Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan.
Methods
Thirty adult albino rabbits were used in the study. Photorefractive keratectomy or LASIK was performed in 1 eye of each animal for the same refractive correction. Each animal was killed after healing intervals up to 6 months. Paraffin sections of the cornea were processed for immunohistochemistry for COX-2 and NFκB (p65).
Results
After PRK, the central and peripheral corneal epithelia up-regulated COX-2 at 3 days; the central epithelium was positive at 4 weeks. Central and peripheral epithelia returned to negative 3 months later. After LASIK, the central epithelium on the corneal flap up-regulated COX-2 at 1 and 2 weeks; it returned to negative at 4 weeks. The peripheral epithelium was labeled with the antibody. Keratocytes around the stromal incision between the flap and the stromal bed up-regulated COX-2 and returned to negative at 3 months. COX-1 was not detected immunohistochemically in corneal tissue during the healing intervals after both procedures. Nuclear factor κB was detected in the cytoplasm and nuclei of migrating corneal epithelial cells 1 day after PRK, was positive in the cytoplasm at 3 days and negative in cytoplasm and nuclei at week and later.
Conclusions
Migrating injured epithelium expressed COX-2 until week 4 during post-PRK healing. Central uninjured epithelium as well as stromal keratocytes expressed COX-2 from 3 days to 2 weeks after LASIK. Uninjured peripheral epithelium also expressed COX-2 at 4 weeks. Activation of stromal keratocytes may induce expression of COX-2 in overlying uninjured epithelium via the inflammatory cytokine(s)/NFκB pathway.
From the Department of Ophthalmology, Wakayama Medical University (Miyamoto, Saika, Okada, Kawashima, Sumioka, Fujita, Ohnishi), Wakayama, Nidek Co., Ltd. (Suzuki), Aichi, and Kobe Kaisei Hospital (Yamanaka), Hyogo, Japan
Reprint requests to Takeshi Miyamoto, MD, PhD, Department of Ophthalmology, Wakayama Medical University, 11-1, Kimiidera, Wakayama 641-8509, Japan.
None of the authors has a financial or proprietary interest in any material or method mentioned.
ABSTRACT