September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Phenotype Screening Identifies Vitamin D As a Significant Regulator of Ocular Developmental Angiogenesis.
Author Affiliations & Notes
  • Stephanie Merrigan
    University College Dublin, Conway Institute, Dubin, Ireland
  • Alison L Reynolds
    University College Dublin, Conway Institute, Dubin, Ireland
  • Breandan N Kennedy
    University College Dublin, Conway Institute, Dubin, Ireland
  • Footnotes
    Commercial Relationships   Stephanie Merrigan, None; Alison Reynolds, None; Breandan Kennedy, None
  • Footnotes
    Support  Government of Ireland Postgraduate Scholarship [GOIPG/2015/2061]
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 5059. doi:
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      Stephanie Merrigan, Alison L Reynolds, Breandan N Kennedy; Phenotype Screening Identifies Vitamin D As a Significant Regulator of Ocular Developmental Angiogenesis.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5059.

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      © ARVO (1962-2015); The Authors (2016-present)

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Purpose : Pathological angiogenesis underpins blindness in age- and diabetes-related blindness. Current treatments have efficacy and delivery limitations. Our objective is to discover novel pharmacological inhibitors of developmental angiogenesis based on a phenotype-based screen of a bioactive drug library.

Methods : 472 ICCB library compounds were screened at 10 µM for inhibitors of hyaloid vessel (HV) development in Tg(fli1:EGFP) zebrafish eyes. Hit compounds were tested for inhibition of non-ocular inter-segmental vessel (ISV) development. Gene expression in the eye and trunk was analysed by RT-PCR. Safety studies used light microscopy to evaluate retinal morphology and the optokinetic response (OKR) assay to assess visual function. Quantitative RT-PCR determined the expression of angiogenic genes and miRNAs.

Results : The biologically active form of vitamin D calcitriol significantly inhibited ocular developmental angiogenesis by ~50 % in a dose dependent manner compared to 0.1 % DMSO vehicle controls(P values <0.001) (N≥20). 8 additional vitamin D receptor agonists (VDRAs) also inhibited ocular developmental angiogenesis including EB 1089 which has reduced calcemic side-effects (P values <0.001) (N≥13). Despite presence of the VDR in the larval trunk, VRRAs did not significantly inhibit ISV development. Safety studies showed calcitriol-treated larvae to have normal retinal lamination/morphology (N=3) but a marked reduction in visual function (N≥17) (P values <0.001). Vitamin D is known to regulate miRNA expression (Craig et al., Zebrafish., 2014). Here, miR21 expression is 7 fold upregulated in calcitriol-treated eyes (N≥150) whereas miR150 expression was unaltered (N≥150). Interestingly, zebrafish VEGFaa but not VEGFab and VEGFac expression is upregulated in calcitriol-treated eyes (N≥50).

Conclusions : VDRAs significantly and specifically inhibit ocular angiogenesis during zebrafish development. This anti-angiogenic activity correlates with increased miR21 expression and an up-regulation of VEGFaa. Future studies are evaluating the role of miR21 and VEGFaa in hyaloid vessel angiogenesis and the safety-efficacy of VDRAs in pre-clinical mouse models of retinal angiogenesis.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.


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