Expression of cytokines and transcription factors in photocoagulated human retinal pigment epithelial cells

Background: It has been shown that scatter photocoagulation induces regression of retinal neovascularization, but the mechanism for this effect is not completely understood. The main focus of our research is to determine the mechanism for the beneficial effects of photocoagulation. In the present study, we quantified the expression of growth factors and transcription factors that inhibit or induce angiogenesis in photocoagulated human retinal pigment epithelial (RPE) cells in vitro. Methods: RPE cells were grown to confluence, and RNA was isolated from the RPE cells with or without photocoagulation. The following growth factors, their receptors and transcription factors were examined by reverse transcription polymerase chain reaction (RT-PCR): transforming growth factor (TGF)-beta1, basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), kinase insert domain-containing receptor (KDR/flk-1), hypoxia-inducible factor (HIF)-1, ETS-I, nuclear factor kappa B (NF-kappaB), interleukin-8 (IL-8). Results. Laser photocoagulation increased the expression of TGF-beta1. Expression of angiogenic factors bFGF, VEGF, IL-8 and their transcription factor, ETS1, was also increased. However, the up-regulation of these factors was observed early (6 h) after photocoagulation. Seventy-two hours after photocoagulation, when RPE cells were repaired, the expression of VEGF IL-8, ETS-1, and NF-kappaB was decreased to the levels before photocoagulation. Conclusions: These results suggest that TGF-beta produced by photocoagulated RPE cells and the down-regulation of angiogenic factors in repaired RPE cells, in all likelihood, play an important role in the processes that occur after laser photocoagulation.