TRANSFORMING GROWTH-FACTOR-BETA INHIBITS THE CYTOKINE-MEDIATED EXPRESSION OF THE INDUCIBLE NITRIC-OXIDE SYNTHASE MESSENGER-RNA IN HUMAN RETINAL-PIGMENT EPITHELIAL-CELLS

Human retinal pigment epithelial (RPE) cells in culture respond to a m ixture of cytokines (IFN-gamma, IL-1 beta, TNF-alpha) by producing lar ge amounts of nitric oxide. Transforming growth factor-beta, unlike ot her growth factors, was found to inhibit this response by more than 75 %. The expression of mRNA for the inducible form of nitric oxide synth ase in RPE cells treated with cytokines was demonstrated by reverse tr anscription-polymerase chain reaction, sequencing of the PCR product a nd northern blotting. Transforming growth factor-beta was highly effec tive in inhibiting (by 75%) the cytokine-induced nitric oxide synthase mRNA expression. This response by RPE may play an important role in t he etiology of infectious and inflammatory diseases affecting retina. (C) 1995 Academic Press, Inc.