Abstract
Purpose: :
A considerable amount of evidence has linked some retinal diseases, such as age–related macular degeneration (AMD) to the inflammatory process. Platelet–activating factor (PAF) is the most potent proinflammatory lipid mediator described. We have previously reported the expression of PAF receptor (PAF–R) in human retinal pigment epithelial (RPE) in vivo as well as in cultured RPE and choroidal cells (CE). We further studied the functionalities of these receptors in cultured human RPE and choroidal cells.
Methods: :
Human RPE and monkey CE cells were cultured in Ham F–12 medium at 37º C until the cells reached 80% confluence. Cells were then harvested following trypsinization. Proliferation and apoptosis of these cells were analyzed in the presence and absence of the exogenous stable derivative of PAF (c–PAF) and the PAF receptor antagonist, WEB 2086. Colorimetric assay with Thiazolyl Blue Terazolium Bromide (MMT) as the marker was used to study cell proliferation. Annexin V was utilized as the apoptotic cell marker. In addition, vascular endothelial growth factor (VEGF) production was studied using enzyme–linked immunosorbent assay (ELISA) in the presence and absence of C–PAF and WEB compound.
Results: :
C–PAF increased proliferation of human RPE cells by 20% compared to the control. The addition of WEB further reduced the stimulation to 12%. The addition of c–PAF and WEB showed no significant effect in apoptosis of human RPE cells compared to the control. In both cultured human RPE and monkey CE cells, c–PAF increases VEGF production, which was neutralized by adding WEB compound. The addition of the WEB–2086 alone significantly decreased the VEGF production of RPE cells in the absence of c–PAF.
Conclusions: :
These findings provide further evidence for the suggestion that PAF plays an important role in the retinal cell physiology and pathology.
Keywords: growth factors/growth factor receptors • retinal pigment epithelium • choroid