Dopamine receptor signaling regulates fibrotic activation of retinal pigmented epithelial cells

Retinal pigmented epithelial (RPE) cells play an important role in retinal fibrotic diseases such as proliferative vitreoretinopathy (PVR). The purpose of this study was to elucidate the involvement of dopamine receptor signaling in regulating the fibrotic activation of RPE cells. Dopamine receptor expression, the effect of dopamine on fibrotic activity, and dopamine production were measured in the human RPE cell line ARPE-19. The fibrotic activation of RPE cells was evaluated in response to treatments with selective dopamine receptor agonists and antagonists by measuring gene expression, migration, proliferation, and fibronectin deposition. DRD2 and DRD5 are the dominant dopaminergic receptors expressed in ARPE-19 cells and TGF-β stimulation enhances the autocrine release of dopamine, which we show further exasperates fibrotic activation. Finally, treatment with D2 dopamine receptor antagonists or D5 dopamine receptor agonists inhibits profibrotic gene expression, migration, proliferation, and fibronectin deposition and thus may serve as effective mechanisms for treating retinal fibrosis including PVR.