Nrf2 Activator RS9 Suppresses Pathological Ocular Angiogenesis and Hyperpermeability

Ocular angiogenesis, including retinopathy of prematurity, diabetic retinopathy, and exudative age-related macular degeneration, are closely related to oxidative stress. Many reports have shown that the cellular protective mechanism against oxidative stress and inflammatory response has nuclear factor-erythroid 2-related factor-2 (Nrf2) activity. The aim of this study was to investigate the effectiveness and mechanism of Nrf2 activation in treating the ocular diseases with abnormal vessels.

The effects of Nrf2 activators, bardoxolone methyl (BARD) and RS9, were evaluated against vascular endothelial growth factor (VEGF)-induced cell migration in human retinal microvascular endothelial cells (HRMECs). We measured the expression of the Nrf2 target genes, Ho-1 and Nqo-1 mRNA, in mouse retinas after a single injection of BARD and RS9. The effects and mechanisms of RS9 against retinal angiogenesis were evaluated using an oxygen-induced retinopathy (OIR) model in mice. Moreover, the effect of RS9 against choroidal neovascularization (CNV) was evaluated in a laser-induced CNV monkey model.

Both BARD and RS9 decreased VEGF-induced cell migration, and significantly increased Ho-1 mRNA expression; however, only RS9 significantly increased Nqo-1 mRNA. RS9 decreased retinal neovascularization through suppressing VEGF expression and increasing Nrf2, HO-1, platelet-derived growth factor receptor (PDGFR)-β, and tight junction proteins in OIR murine retinas. Furthermore, RS9 showed a tendency toward decreasing CNV lesions, and improved vascular leakage in a CNV monkey model.

These data indicate that a Nrf2 activator might be a candidate for treatment of ocular diseases characterized by pathophysiological angiogenesis and hyperpermeability.