CYTOKINE-MEDIATED AND NEUROPEPTIDE-MEDIATED DIFFERENTIATION IN RETINAL-PIGMENT EPITHELIAL-CELLS IN-VITRO

To determine the mechanism of growth and differentiation of:retinal pi gment epithelial (RPE) cells it is important to understand the pathoge nesis of several retinal diseases. Recently it has been reported that several cytokines and neuropeptides regulate the growth of RPE cells. In this study, the role of cytokines and neuropeptides in melanin synt hesis, which is one indication of the RPE cell differentiation, was ex amined using chick RPE cells in vitro. IL-1 beta, TNF-alpha, substance P, beta-endorphin and methionine-enkephalin stimulated the melanin sy nthesis of RPE cells in a dose-dependent manner. The most effective co ncentrations of these agents on RPE cell melanin synthesis were not th e same as that for RPE cell proliferation. These results indicate that cytokines and neuropeptides play an important role not on:ly for the growth but also for the differentiation of RPE cells. (C) 1997 Academi c Press Limited.