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| 196P London, UK Pharmacology 2016 |
Phenotype screening identifies vitamin D to regulate ocular developmental angiogenesis in vivo
Introduction: Abnormal ocular vasculature growth underpins age- and diabetes-related blindness. Current treatments have efficacy and delivery limitations. Our objective was to discover novel inhibitors of vasculature development through phenotype-based screening of a bioactive drug library.
Method: 472 ICCB library compounds were screened for inhibition of ocular hyaloid vessel (HV) development in Tg(fli1:EGFP) zebrafish larvae. Hit compounds were tested for inhibition of non-ocular inter-segmental vessel (ISV) development. mRNA and miRNA expression studies in larval eyes were carried out by quantitative RT-PCR. Safety studies evaluated retinal morphology by light microscopy. In vitro viability in ARPE-19 cells was evaluated by Alamar Blue assay. ARPE-19 cell factor secretion studies were carried out by ELISA.
Results: Hit compound calcitriol and 6 additional vitamin D receptor agonists (VDRAs) significantly inhibited ocular developmental angiogenesis. Despite presence of the VDR in larval trunks, VDRAs did not inhibit ISV development. Safety studies showed calcitriol-treated larvae to have normal retinal lamination/morphology. miR21, VEGFaa and VEGFab expression was significantly upregulated in calcitriol-treated eyes and miR150 expression was unchanged. VEGF receptor flt1 and kdrl are not significantly upregulated but a dose dependant increase in expression was seen in calcitriol-treated eyes. In ARPE-19 cells; selected VDRAs had no effect on cell viability and preliminary data shows TNFα induced IL-8 and GM-CSF expression to be attenuated by VDRA treatment.
Conclusion: VDRAs significantly and specifically inhibit ocular angiogenesis during zebrafish development. This anti-angiogenic activity correlates with increased miR21 expression and an up-regulation of VEGF. Future studies will evaluate the anti-angiogenic mechanism of VDRAs and validate anti-angiogenic activity in mouse models.
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