Abstract
Purpose :
Choroidal neovascularization (CNV) is a key characteristic of wet Age-related macular degeneration (AMD) and is incompletely and inefficiently targeted by the current anti-VEGF (vascular endothelial growth factor) standard of care. The bile acid receptor farnesoid X receptor (FXR) exerts anti-inflammatory, antifibrotic, and antiangiogenic effects in non-ocular tissues and, as per our previous study, limits retinal neovascularization in a mouse model of oxygen-induced retinopathy. However, its role in choroidal neovascularization has never been studied and is a focus of the current study.
Methods :
Laser injury-induced CNV was carried out in wild-type (WT) and FXR-deficient (FXR-/-) mice to perform visual functions (optical coherence tomography; OCT and fluorescein angiography; FA) or sacrificed to collect eyes for various analyses at 7-, 14- and 21 days post-laser-injury. The choroidal flat mounts were stained with isolectin-B4, alpha-smooth muscle actin (SMA), and collagen-1, and the lesion areas were quantified. A different set of mouse eyes was also stained with H&E (Hematoxylin & Eosin). Additionally, changes in the expression of various inflammatory and fibrotic genes was evaluated by qPCR. Lastly, micro-dissected choroid explants from WT and FXR-/- were grown on the Matrigel matrix to assess the angiogenic potential of choroidal endothelial cells.
Results :
Following CNV, we observed that FXR-/- mice exhibited greater lesion size on OCT and FA evaluations than WT counterparts at different time intervals. The same was confirmed in H&E-stained retinal sections. Furthermore, the fluorescence microscopy analysis of choroidal flat mounts indicated that FXR-/- mice had a larger choroidal injury area stained with markers of angiogenesis (isolectin-B4), fibrosis (collagen-1) and epithelial-mesenchymal transition (alpha SMA). These changes were corroborated by the results of the qPCR analysis. Lastly, ex vivo FXR-/- choroid explants had irregular choroidal endothelial cell sprouting compared to WT mice.
Conclusions :
Our data comprehensively provided the first evidence for the pivotal role of FXR in regulating choroidal neovascularization in mice. The ongoing studies in our laboratory are targeted at understanding the underlying molecular mechanisms. Hence, the clinically used FXR agonists may be repurposed to regulate angiogenesis, inflammation, and fibrosis associated with wet AMD.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.