Changes in the mRNA expression of cytokines and chemokines by stimulated RPE cells in vitro

Purpose. The transplantation of retinal pigment epithelial (RPE) cells is a possible therapy for degenerative diseases of the retina. However, the imm une response and the subsequent rejection of the allografts are major probl ems in this field. We investigated the effect of pro-inflammatory factors o n the cytokine and chemokine mRNA expression of human RPE cells during long -term observations in vitro. Methods. Human RPE cells were cultured in the presence of tumor necrosis fa ctor-alpha (TNF-alpha, 10 ng/ml), interferon-gamma (IFN-gamma, 1000 U/ml) o r with a combination of both up to 96 hours. Cells were harvested and total RNA was isolated. The changes in expression of mRNA coding for RANTES, the interleukines (IL)-6, 8, 10, 15, IFN-gamma, monocyte chemotactic protein-1 (MCP-1) and transforming growth factor-beta 1 (TGF-beta 1) during the stim ulation were investigated using the ribonuclease protection assay. Results. IL-10 and IFN-gamma mRNA were detected in neither unstimulated nor stimulated cells. Human RPE cells constitutively express the mRNA for IL-6 , MCP-1, IL-8, IL-15, TGF-beta 1 and, at very low levels, for RANTES. The T GF-beta 1 mRNA expression was not influenced by either stimulation. The mRN A of the other factors was up-regulated for 24-48 h dependent on the stimul ation. Conclusions. Human RPE cells are able to increase their mRNA expression for the detected cytokines in response to the pro-inflammatory factors which a re detectable in the rejection process. These up-regulated cytokines themse lves are known to be involved in several inflammatory and immunological pro cesses, suggesting their role in the rejection of transplanted RPE allograf ts.