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Yuka Matsuda, Mamiko Machida, Yasuhiro Nakagami, Takeshi Nakajima, Mitsuyoshi Azuma; NRF2 activator RS9 protects corneal epithelium from cell damage in dry eye models. Invest. Ophthalmol. Vis. Sci. 2019;60(9):270. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Oxidative stress may cause ocular surface damage during the development of dry eye. Mammalian cells have defense systems against oxidative stress. A central regulator of the stress response is the transcription factor called nuclear factor-erythroid 2-related factor 2 (NRF2), which may be involved in dry eye. NRF2 is activated by the novel triterpenoid RS9 (biotransformation compound of RTA 402). The purpose of this study was to assess the efficacy of RS9 against dry eye in in vitro and in vivo models. Parent compound RTA 402 was used as comparative control in some experiments.
Bioactivity was estimated by induction of mRNAs for two NRF2-targeted genes: NQO1 (prevents radical species) and GCLC (glutathione synthesis), using a corneal epithelial cell line (HCE-T). Protection against oxidation and cell damage was tested in vitro by culture under hyperosmotic stress or by addition of menadione, a generator of reactive oxygen species (ROS). Dry eye in in vivo was induced by injection of scopolamine into rats. 500 ng/ml of RS9 was applied to both eyes for 2-week. Oxidative stress was measured by accumulation of 8-hydroxy-2’-deoxyguanosine (8-OHdG). Corneal wound healing was measured by scoring for superficial punctate keratitis (SPK). Corneal epithelial cell densities were evaluated histologically.
RS9 and RTA 402 induced expression of NQO1 and GCLC mRNAs in HCE-T cells. RS9 showed a stronger protective effect than RTA 402, and both compounds suppressed hyperosmotic-ROS generation and menadione cellular damage. Ocular instillation of RS9 also significantly upregulated expression of Nqo1 mRNA in corneal epithelium. Accumulation of 8-OHdG and increased SPK scores were observed in corneal epithelium from scopolamine-injected rats. Density of cells in the corneal basal layer was decreased. These changes were significantly ameliorated by topical RS9.
Our data show that RS9 induced NRF2-targeted genes, reduced oxidation, and ameliorated symptoms of dry eye in in vitro and in vivo models. NRF2 activator may be a potent candidate agent against dry eye disease.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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