Abstract
Purpose :
Retinal angiogenesis underlies proliferative diabetic retinopathy, and new therapies are sorely needed. We previously identified the heme biosynthesis enzyme ferrochelatase (FECH) as an angiogenesis mediator. FECH is upregulated in human and mouse eyes undergoing choroidal neovascularization, and knockdown or mutation abolished angiogenesis in vitro and in vivo. FECH inhibition is therefore a promising therapeutic approach for blocking neovascularization in the eye. The FDA-approved antifungal drug, griseofulvin, inhibits FECH as an off-target effect and blocks choroidal neovascularization ex vivo and in mice. Here, we investigated the anti-angiogenic effect of griseofulvin on retinal angiogenesis in the mouse oxygen-induced retinopathy (OIR) and ex vivo retinal sprouting models, and explored its ocular toxicity.
Methods :
Temporal expression of FECH was analyzed by immunofluorescence at various ages in retinas of mice undergoing oxygen-induced retinopathy (OIR). Griseofulvin was intravitreally injected in OIR mice at P12 and retinal neovascularization assessed at P17 using Isolectin B4 staining. Tip cell filopodia and retinal sprouting was assessed ex vivo. For toxicity studies, adult mice were intravitreally injected with griseofulvin and retinal damage analyzed on days 7 and 14. Structural and morphological analyses were performed using optical coherence tomography (OCT) and histology. Vascular leakage was assessed by fluorescein angiography (FA). Functional analysis of retina was performed using electroretinogram (ERG). Cell death analysis and immune cell activation were assessed by immunohistochemistry.
Results :
FECH was upregulated in mouse OIR retinas. Griseofulvin inhibited neovascularization and also decreased the avascular area in the OIR retina. Further, griseofulvin inhibited retinal tip cell filopodia and retinal sprouting. Retinal structure and function were maintained and no vascular leakage was found in griseofulvin treated eyes. Immunostaining revealed no aberrant cell death, microglia activation or gliosis in griseofulvin treated eyes, suggesting no cellular toxicity or stress.
Conclusions :
Griseofulvin inhibits retinal neovascularization and also promotes revascularization, suggesting a dual effect on vascular repair, without evidence of ocular toxicity. Taken together, these findings suggest that griseofulvin could be repurposed to treat retinal neovascularization.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.