Inflammatory factors in experimental retinal vein occlusion

Abstract

Abstract Purpose Vascular endothelial growth factor (VEGF) is a key player in the development of macular edema (ME) in patients with retinal vein occlusion (RVO). In addition to VEGF, various other factors are altered in the hypoxic retina and influence the development of ME. In a rat model of RVO, we determined the changes in the gene expression of factors implicated in the development/resolution of ME (VEGF‐A, PEDF, IL‐6, Il‐1β, potassium und water channels) in the retina and pigment epithelium (RPE). Methods In one eye of Long‐Evans rats (n=30), retinal veins near the optic nerve head were photocoagulated using a blue‐green argon laser. Untreated eyes served as controls. The eyes were enucleated 1, 3 and 7 days after laser treatment, and the mRNA levels were determined with real‐time PCR. Results In the neural retina, VEFG expression showed fast upregulation at 1 day after RVO, and returned to the control level after 3 days. The expression of VEGF was not altered in the RPE. Potassium and water channels were downregulated in both tissues through the entire time period investigated. IL‐6 and IL‐1β were rapidly and strongly upregulated in the retina and RPE (to levels 80‐times higher as control) within 1 day after RVO, and decreased only slowly after 7 days. Conclusion In RVO, there is fast and transient upregulation of the expression of VEGF, which is dominant for the acute stage of the disease. The strong and long‐lasting upregulation of IL‐6 and IL‐1β suggests that inflammatory factors play an important role in chronic hypoxia.