Mineralocorticoid receptor invalidation in vascular endothelial cells prevents CNV development

Abstract

Purpose : Choroidal neovascularization (CNV) is a major cause of visual impairment in wet age-related macular degeneration (nAMD) patients, particularly when refractory to intraocular anti-VEGF injections. While a growing body of evidence identifies mineralocorticoid receptor (MR) as a player in vascular inflammation, fibrosis and angiogenesis, their role in the pathogenesis of CNV has not been investigated. The aim of this work was to decipher the role of MR in the development of CNV using various transgenic models invalidated for MR in specific cell types.

Methods : CNV was induced by Argon laser (532 nm) in eyes of rodents. The expression of MR in the RPE/choroid was evaluated in the time course of CNV development using qPCR. Transgenic mice with cell-type-specific MR deletion were used: tamoxifen-inducible Vecadh-MR-KO and constitutive Tie2-MR-KO in vascular endothelial cells, tamoxifen-inducible SMA-MR-KO in smooth muscle cells, and constitutive Lys-MR-KO in myeloid cells. Because our transcriptional experiments showed NGAL as MR-regulated genes, we also evaluated mice with NGAL KO in myeloid cells. Fluorescein angiography was performed to estimate CNV leakage. The volume of CNV was quantified on choroidal flat mounts. Statistical analysis was performed using a linear mixed model for repeated measures.

Results : MR was over-expressed as early as day 3 after laser induction in the RPE/choroid. While no difference in CNV permeability and formation was observed between SMA-MR-KO and their control littermates, Vecadh-MR-KO showed reduced choroidal neovascular leakage and decreased CNV volume. Tie2-MR-KO is less specific to endothelial cells as Tie2 is also expressed in myeloid cells. We observed a protection of CNV development in these mice whilst Lys-MR-KO mice did not inhibit CNV. This finding indicates that endothelial MR but not myeloid MR contributes essentially to CNV development. NGAL KO did not protect mice from laser-induced CNV.

Conclusions : MR is over expressed in the early phases of CNV development. Using different transgenic models, we show that MR invalidation in the vascular endothelial cells is mandatory to drive anti-angiogenic effects in CNV. NGAL is not mediating the anti-angiogenic effect in laser-induced CNV.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.