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Mayur Choudhary, Stephen H Safe, Goldis Malek; Aryl hydrocarbon receptor (AhR) activation decreases severity of laser-induced choroidal neovascular lesions (CNV). Invest. Ophthalmol. Vis. Sci. 2017;58(8):1939.
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The large number of anti-VEGF non-responders necessitates identification of alternative therapeutic targets for patients with wet age-related macular degeneration (AMD). AhR is a transcription factor important in toxin clearance. It has also been shown to regulate several AMD-pathogenic pathways including inflammation, extracellular matrix remodeling and angiogenesis. Previously we found that the absence of AhR in mice, results in smaller and less complex CNV lesions compared to AhR+/+ mice. Herein, we tested the therapeutic potential of AhR activation on angiogenesis in a mouse model of wet AMD.
AhR activity in human primary RPE (hRPE) cells (n=2 donors; 3 replicates) and macaque choroidal endothelial cells (RF6A; 3 replicates) was determined by luciferase reporter activity assays and assessment of target gene expression (CYP1A1, CYP1B1, IL-1b) following treatment with a panel of endogenous (n=5) and pharmacological (n=8) AhR ligands. Angiogenesis assays were performed to evaluate the effect of ligands on regression of VEGF-induced cell migration. CNV lesions were laser induced in C57BL/6J mice (12 month old, n=10/drug, males and females) treated with the two ligands with the greatest efficacy to decrease cell migration in vitro. Severity of the lesions was determined on flatmounts of the posterior pole (n=10) stained with isolectin GS-IB4. Distribution of immune cells and extracellular matrix molecules was determined by immunohistochemistry.
All endogenous and pharmacological drugs activated AhR in both hRPE and RF/6A cells. AhR activity in RF/6A cells was greater when treated with pharmacological ligands (10-25 fold over vehicle) in comparison to the endogenous compounds (3-7 fold over vehicle). Leflunomide and flutamide, inhibited endothelial cell migration (p=0.0001 and p<0.0001, respectively) and proliferation (p<0.05, both) significantly. In vivo, leflunomide (38% decrease in area, p<0.05 and 56% decrease in volume, p<0.05) and flutamide (72% decrease in area, p<0.01 and 55% decrease in volume, p<0.05) significantly decreased lesion size and volume. A significant decrease in the number of Iba+ microglia/macrophages within the lesions following drug treatment was seen in retinal cryosections.
Our results support the hypothesis that activation of AhR may be used as a potential treatment in wet-AMD.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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