The role of arachidonic acid metabolites in DR

Abstract

Abstract Purpose The inducible enzyme cyclooxygense‐2 (COX‐2) and its metabolic products are important mediators for angiogenesis. We investigated the expression of COX‐2 and its downstream enzymes microsomal prostaglandin‐E synthase (mPGES)‐1, cytosolic PGES (cPGES) and thromboxane synthase (TXS) and correlated it with vascular endothelial growth factor (VEGF) expression and level of vascularization in proliferative diabetic retinopathy (PDR) epiretinal membranes. Methods Fourteen membranes were studied by immunohistochemistry. Results Vascular endothelial cells expressed COX‐2, mPGES‐1 and VEGF in 75.6%, 64.3% and 50% of the membranes, respectively. TXS was expressed in stromal cells in 85.7% of the membranes. There was no immunoreactivity for cPGES. There were significant correlations between number of blood vessels expressing CD34 and the numbers of blood vessels expressing COX‐2 (rs = 0.858; p<0.001), mPGES‐1 (rs = 0.743; p = 0.002) and VEGF (rs = 0.845; p = 0.001) and the number of cells expressing TXS (rs = 0.74; p = 0.002). Number of blood vessels expressing VEGF correlated significantly with the numbers of blood vessels expressing COX‐2 (rs = 0.879; p<0.001) and mPGES‐1 (rs = 0.942; p<0.001) and the number of cells expressing TXS (rs = 0.702; p = 0.011). Conclusion COX‐2 and its metabolic products might contribute to PDR angiogenesis.