Abstract
Purpose :
Retinal pigment epithelium (RPE) is a main source of vascular endothelial growth factor (VEGF), leading to choroidal neovascularization (CNV). Recently, mitochondrial dysfunction in RPE was observed in neovascular age-related macular degeneration (nAMD) patients. Excessive mitochondrial fission by dynamin-related protein 1 (Drp1) leads to mitochondrial dysfunction and promotes several pathological angiogenesis. However, the relationship between mitochondrial fission and pathological process in nAMD was unknown. The purpose of this study was to elucidate the involvement of mitochondrial fission in the CNV development.
Methods :
The murine CNV model was performed by laser photocoagulation using C57BL/6J mice. The expression levels of mitochondrial fission related protein in RPE-choroid-sclera complex were assessed by Western blotting. The localization of phospho-Drp1 (p-Drp1) was investigated by immunostaining. Additionally, we examined the effect of mitochondrial division inhibitor 1 (Mdivi-1), a Drp1 inhibitor, on CNV development by evaluating the CNV area and fluorescein leakage. Mdivi-1 was administrated by intravitreal injection. To examine whether mitochondrial fission promoted the production of pro-angiogenic factors in RPE, we evaluated the effect of Mdivi-1 on hypoxia-induced mitochondrial fission by immunostaining of translocase outer membrane 20, known as a mitochondrial marker, and the mRNA expression levels of pro-angiogenic factors by real time (RT)-PCR using human-derived RPE cell line (ARPE-19).
Results :
In the RPE-choroid-sclera complex, the expression level of p-DRP1 and mitochondria fission factor, known as a receptor of Drp1, significantly increased after laser irradiation. Especially, p-Drp1 was increased in F-actin positive RPE cells around CNV lesion. In addition, the intravitreal administration of Mdivi-1 significantly suppressed the CNV formation and vascular leakage. Furthermore, in ARPE-19, Mdivi-1 treatment suppressed hypoxia-induced mitochondrial fission and the upregulation of VEGF, monocyte chemotactic protein 1, and glucose transporter 1.
Conclusions :
These findings suggest that mitochondrial fission in RPE contributes to CNV development, and its inhibition could be a novel therapeutic strategy for nAMD.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.