Lipidomics reveal the protective effects of a vegetable-derived isothiocyanate against retinal degeneration.

Background: Age-related macular degeneration (AMD) is a leading cause of blindness in the ageing population. Without effective treatment strategies that can prevent disease progression, there is an urgent need for novel therapeutic interventions to reduce the burden of vision loss and improve patients' quality of life. Dysfunctional innate immune responses to oxidative stress observed in AMD can be caused by the formation of oxidised lipids, whilst polyunsaturated fatty acids have shown to increase the risk of AMD and disease progression in affected individuals. Previously, our laboratory has shown that the vegetable-derived isothiocyanate, L-sulforaphane (LSF), can protect human adult pigment epithelial cells from oxidative damage by upregulating gene expression of the oxidative stress enzyme Glutathione-S-Transferase µ1. This study aims to validate the protective effects of LSF on human retinal cells under oxidative stress conditions and to reveal the key players in fatty acid and lipid metabolism that may facilitate this protection. Methods: The in vitro oxidative stress model of AMD was based on the exposure of an adult retinal pigment epithelium-19 cell line to 200µM hydrogen peroxide. Percentage cell proliferation following LSF treatment was measured using tetrazolium salt-based assays. Untargeted fatty acid profiling was performed by gas chromatography-mass spectrometry. Untargeted lipid profiling was performed by liquid chromatography-mass spectrometry. Results: Under hydrogen peroxide-induced oxidative stress conditions, LSF treatment induced dose-dependent cell proliferation. The key fatty acids that were increased by LSF treatment of the retinal cells include oleic acid and eicosatrienoic acid. LSF treatment also increased levels of the lipid classes phosphatidylcholine, cholesteryl ester and oxo-phytodienoic acid but decreased levels of phosphatidylethanolamine lipids. Conclusions: We propose that retinal cells at risk of oxidative damage and apoptosis can be pre-conditioned with LSF to regulate levels of selected fatty acids and lipids known to be implicated in the pathogenesis and progression of AMD.

L-Sulforaphane Confers Protection Against Oxidative Stress in an In Vitro Model of Age-Related Macular Degeneration.

BACKGROUND: In age-related macular degeneration, oxidative damage and abnormal neovascularization in the retina are caused by the upregulation of vascular endothelium growth factor and reduced expression of Glutathione-S-transferase genes. Current treatments are only palliative. Compounds from cruciferous vegetables (e.g. L-Sulforaphane) have been found to restore normal gene expression levels in diseases including cancer via the activity of histone deacetylases and DNA methyltransferases, thus retarding disease progression. OBJECTIVE: To examine L-Sulforaphane as a potential treatment to ameliorate aberrant levels of gene expression and metabolites observed in age-related macular degeneration. METHOD: The in vitro oxidative stress model of AMD was based on the exposure of Adult Retinal Pigment Epithelium-19 cell line to 200µM hydrogen peroxide. The effects of L-Sulforaphane on cell proliferation were determined by MTS assay. The role of GSTM1, VEGFA, DNMT1 and HDAC6 genes in modulating these effects was investigated using quantitative real-time polymerase chain reaction. The metabolic profiling of L-Sulforaphane-treated cells via gas-chromatography massspectrometry was established. Significant differences between control and treatment groups were validated using one-way ANOVA, student t-test and post-hoc Bonferroni statistical tests (p<0.05). RESULTS: L-Sulforaphane induced a dose-dependent increase in cell proliferation in the presence of hydrogen peroxide by upregulating Glutathione-S-Transferase µ1 gene expression. Metabolic profiling revealed that L-Sulforaphane increased levels of 2-monopalmitoglycerol, 9, 12, 15,-(Z-Z-Z)- Octadecatrienoic acid, 2-[Bis(trimethylsilyl)amino]ethyl bis(trimethylsilyl)-phosphate and nonanoic acid but decreased ß-alanine levels in the absence or presence of hydrogen peroxide, respectively. CONCLUSION: This study supports the use of L-Sulforaphane to promote regeneration of retinal cells under oxidative stress conditions.

Mimicking the ocular environment for the study of inflammatory posterior eye disorders.

The common inflammatory posterior eye disorders, age-related degeneration and glaucoma often lead to irreversible vision loss. Current treatments do not target early stages or prevent disease progression. Consequently, the identification of biomarkers or early disease models that can accurately mimic the pathological processes involved is essential. Although none of the existing models can recapitulate all pathological aspects of these disorders, these models have revealed new therapeutic targets. Efforts to accurately phenotype eye disorders at various disease stages are warranted to generate a 'super' model that can replicate the microenvironment of the eye and associated pathological hallmarks effectively.