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Kasra Attaran-Rezaei, Hssanain Toma, Stephen J. Kim; Reduced VEGF Expression in Retinal Pigment Epithelium Cells from Cyclooxygenase-2 Null Mice. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1791.
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To assess the degree of hypoxia-induced VEGF production in retinal pigment epithelium (RPE) cells cultured from wildtype (WT) and cyclooxygenase (COX)-2 null mice and the effects of pharmacologic inhibition of COX with nonsteroidal anti-inflammatory drugs (NSAIDs).
RPE cells were isolated from WT and COX-2 null mice (on the same background) at 6 weeks of age and cultured until at least 80% confluent. Passages 4 to 6 were used for all experiments. RPE cultures were exposed to increasing durations (0, 6, 12, 24 hours) of hypoxia (<1% oxygen) and mRNA was isolated and tested for VEGF, COX-1, and COX-2 expression by reverse-transcription-polymerase chain reaction. VEGF protein was measured in tissue supernatant by enzyme-linked immunosorbent assay. WT and COX-2 -/- RPE cells cultured under hypoxia were then exposed to increasing concentrations (0, 0.01, 0.1, 1, 10 µm) of Celecoxib (selective COX-2 inhibitor) and Ketorolac (COX-1 and COX-2 inhibitor) and mRNA and tissue supernatant were collected and tested as above.
Both WT and COX-2-/- RPE cells demonstrated significant increases in VEGF production after 24 hours of hypoxia when compared to their respective controls cultured under normoxia (P < 0.05). COX-2-/- RPE cells appeared to produce approximately 30% less VEGF than WT RPE cells after 24 hours hypoxia. Both celecoxib and ketorolac significantly reduced VEGF production in WT RPE cells exposed to 12 hours hypoxia (P < 0.01) from approximately 400 pg/ml in untreated cells to 200 pg/ml in cells exposed to increasing concentrations of either NSAID.
Cultured COX-2 -/- RPE cells appear to produce less VEGF than WT cells under hypoxia. Both Celecoxib and Ketorolac significantly reduce hypoxia-induced VEGF production in WT RPE cells. These results suggest that COX-2 modulates VEGF expression in RPE cells and provides a mechanism to explain the inhibitory effects of NSAIDs observed on choroidal neovascularization (CNV) in published studies and suggests a potential therapeutic role of NSAIDs in the treatment of CNV.
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