Effects and Mechanism of Action of PX-478 in Oxygen-Induced Retinopathy in Mice

Abstract

Importance: Retinopathy of prematurity (ROP) is an important risk factor for blindness in children due to neovascularization (NV). Hypoxia stimulates the formation of NV, as retinal hypoxia affects the stability and function of hypoxia-inducible factor (HIF) transcription factors. The purpose of this study is to study the mechanism of ROP and provide theoretical basis for clinical treatment of ROP. Objective: In the present study, we used a mouse model of oxygen-induced retinopathy (OIR) to demonstrate the effects of the HIF-1α inhibitor PX-478 on OIR, and to determine its mechanism of action, to provide a theoretical basis for the clinical treatment of ROP. Materials and Methods: The OIR mouse model was induced by exposing neonatal mouse pups and their mothers to 75 ± 5% oxygen from postnatal day 7 (P7) to P12, before being returned to room air from P12 to P17. Flat mount analyses were performed at P12 and P17. Hif1a, Hif2a, Hif3a, and Vegfa mRNA were detected by reverse transcription-polymerase chain reaction in OIR mice at P12 and P17. Hif1a and Vegfa mRNA were detected in OIR mice at P12 and P17 treatment with PX-478. Western blot analyses were used to assess the levels of HIF-1α, VEGF-A, and EPO before and after treatment with PX-478 at P12 and P17. Results: Hif1a mRNA was increased in OIR mice at P12 and P17, while Vegfa mRNA was increased at P12 and P17. HIF-1α, VEGF-A, and EPO protein levels were increased in OIR mice at P12 and P17, as compared to control mice at the same age (all p < 0.05). Inhibition of HIF-1α by injection of PX-478 in OIR mice (P9–P16) caused a decrease in the retinal avascular area at P12 and P17 (both p < 0.05), NV areas at P17 (p < 0.05), Vegfa mRNA decreased at P12 and P17, as compared to control mice (p < 0.05), and VEGF-A and EPO protein levels at P12 and P17, as compared to control mice. Our study found that there were PX-478 both retina and vitreous body of OIR. Inhibition of HIF-1α by injection of PX-478 in OIR mice caused a decrease in the retinal avascular area at P12 and P17, NV areas decreased at P17, VEGF-A and EPO protein levels at P12 and P17. Endothelial cell migration assays and cell tube formation indication PX-478 attenuate cell migration and significantly weakened the cell cavity formation under the condition of hypoxia. Conclusion: HIF-1α plays a main role in OIR and can be considered a therapeutic target in OIR by suppressing downstream angiogenic factors, PX-478 decreasing the retinal avascular area and NV.