Expression of cyclooxygenase-2 in orbital fibroadipose connective tissues of Graves' ophthalmopathy patients

Objective: The aim of this study is to evaluate the expression of cycloocygenase-2 (COX-2) in orbital fibroadipose connective tissue in Graves' ophthalmopathy (GO) patients, and investigate the associations between COX-2 expression and GO characteristics. Methods: The orbital fibroadipose connective tissues of 2 3 cases demonstrating moderate or severe GO, and eight control subjects without any history of thyroid or autoimmune disease were analyzed for COX-2 mRNA expression. Real-time relative quantitative PCR was performed to assess transcripts of COX-2 using the LightCycler. The disease activity was evaluated by the clinical activity score (CAS). The clinical features of GO were evaluated by total eye score (TES) and the cases were divided into two groups; type I cases included higher degrees of proptosis with orbital fat volume increase, and type 2 cases included cases with compressive neuropathy and limited extraocular muscle functions. Results: The mean +/- S.D. disease duration was 5.7 +/- 7.1 years. The mean +/- S.D. CAS and TES of cases were 1.60 +/- 1.04 and 7.5 +/- 1.8 respectively. The mean +/- S.D. expression of COX-2 was 0.023 +/- 0.013 and 0.010 +/- 0.002 in GO cases and controls (P=0.008), and 0.015 +/- 0.073 and 0.029 +/- 0.135 in type I and type 2 cases respectively (P=0.007). COX-2 expression showed a statistically significant positive correlation with TES (r=0.634, P=0.001), and a negative correlation with the disease duration (r= -0.621, P=0.002). Conclusions: COX-2 is expressed at higher levels in orbital fibroadipose tissues of GO cases. This showed a positive correlation with increasing severity of orbital disease suggesting possible relation with COX-2 expression and orbital inflammation in GO.