CYCLO-OXYGENASE-2 EXPRESSION IN HUMAN IDIOPATHIC EPIRETINAL MEMBRANE

KASE, SATORU MD^*; SAITO, WATARU MD^*; OHNO, SHIGEAKI MD^†; ISHIDA, SUSUMU MD^*

From the Departments of *Ophthalmology and †Ocular Inflammation and Immunology, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.

Supported by the Research Foundation of the Japan Society for the Promotion of Science, by a grant for Research on Sensory and Communicative Disorders from The Ministry of Health, Labor, and Welfare, and by grants-in-aid for Scientific Research from The Ministry of Education, Culture, Sports, Science, and Technology (MEXT).

Reprint requests: Satoru Kase, PhD, MD, Department of Ophthalmology, Hokkaido University Graduate School of Medicine, N 7, W 15, Kita-ku, Sapporo, Hokkaido, 060-8638, Japan; e-mail:[email protected]

Retina30(5):p 719-723, May 2010. |DOI:10.1097/IAE.0b013e3181c59698

Purpose:

The purpose of this study was to examine the expression of cyclo-oxygenase (COX)-2 in the idiopathic epiretinal membrane (IERM), inner limiting membrane (ILM), and proliferative diabetic retinopathy membrane.

Methods:

Twenty membranes, consisting of eight IERMs, four ILMs, and eight proliferative diabetic retinopathy membranes, were surgically removed. Formalin-fixed, paraffin-embedded tissue sections were processed for immunohistochemistry using anti-COX-2 antibody. The nuclear density showing the density of cells situated in IERM and ILM specimens was calculated under high-power fields using a light microscope.

Results:

The IERM comprised flattened cells with oval nuclei constituting a monolayer. The ILM contained a few cells with abundant collagenous tissues. Neither endothelial nor inflammatory cells were observed in the IERM and ILM. COX-2 immunoreactivity was markedly detected in cells located in the IERM. In contrast, COX-2 immunoreactivity was faintly detected in the ILM. The COX-2-positive rate was 65.4 ± 15.5% and 34.3 ± 20.3% in the IERM and ILM, respectively, being significantly higher in the former (P = 0.046). The nuclear density was 39.3 ± 10.3 and 8.6 ± 7.2 in the IERM and ILM, respectively, being significantly higher in the former (P = 0.0003). The proliferative diabetic retinopathy membranes consisted of many vascular endothelial and stromal cells. Cytoplasmic immunoreactivity for COX-2 was detected in endothelial and stromal cells in the proliferative diabetic retinopathy membranes.

Conclusion:

These results suggest that COX-2 plays a potential role in the formation of avascular and vascularized epiretinal membranes if an epiphenomenon of COX-2 expression within these epiretinal membranes has been ruled out in future studies.