Abstract
Abstract: :
Purpose: There are two known isoforms of cyclooxygenase (COX): COX-1 is relatively ubiquitously and constitutively expressed in most normal tissues and is required for their normal physiological function, whereas COX-2 is induced in various inflammatory-induced pathologies. Despite many reports on COX-1 and COX-2 in systemic organs, its expression has not been characterized in the ocular surface. We examined expression of COX-1 and COX-2 in human cornea, conjunctiva, lacrimal gland and meibomian gland. Methods: Four samples of human corneas and 6 samples of human conjunctiva that included tarsal plates and lacrimal glands were obtained from autopsies. By using immunohistochemistry, we compared the cellular expression and localization of COX-1 and COX-2 in the normal human cornea, conjunctiva, lacrimal gland and meibomian gland. Results: COX-1 immunoreactivity was present in mast cells in conjunctiva, acinar and ductal epithelial cells in lacrimal gland, some lymphocytes in conjunctiva and lacrimal gland, some acinar cells in meibomian gland and vascular endothelial cells. In contrast, COX-2 immunoreactivity was present in mast cells in conjunctiva, acinar and ductal epithelial cells in lacrimal gland and some acinar cells in meibomian gland. Intensity of COX-2 expression in lacrimal gland and meibomian gland was weaker than that of COX-1 expression in those tissues. No immunoreactivity was present in corneal and conjunctival epithelium. Conclusions: These results suggest that prostaglandins in the tear fluid, synthesized by COX-1 or COX-2, may derive from lacrimal gland, and contribute to normal physiological and homeostatic functions in the ocular surface.
Keywords: lacrimal gland • inflammation • conjunctiva