Abstract
Purpose :
To help anti-VEGF therapy non-responders, one potential alternative approach is to target molecules upstream of the VEGF signaling cascade, such as the hypoxia-inducible transcription factor HIF-1α (in the ischemic retina, HIF-1α promotes the expression of VEGF and other angiogenic factors) (Uschi-Ouchi PNAS 2020). In these studies, using an intrinsically disordered protein CITED2, a direct product of HIF-mediated transcription that displaces HIF-1α to hinder the hypoxic response, we evaluate its effects at different timepoints in the OIR mouse model.
Methods :
Mice were place in a hyperoxic environment (75% O2) at P6 and returned to room air at P11. IVT studies: The left eyes were IVT injected with IgG (control) (n=3), 0.68ng (n=3), 3.4ng(n=3), and 34ng CITED2 (Human and Mouse C-terminal transactivation domain (residues 216 to 269 human/mouse with pentapeptide GSHMS) peptide (n=3) (ThermoFisher) at P11 (Study 1), P12 (Study 2), and P13 (Study 3). Eyes were collected at P16. All retinas were stained with FITC-labeled Griffornia simplicifolia lectin I (Vector Laboratories) and anti-NG2 (Millipore). Retinal avascular areas and abnormal neovascularization areas were analyzed. RNAseq studies: Mice were collected P6 (n=3), OIR P11 (n=3), OIR P12 (n=5), and OIR P15 (n=4).
Results :
With IVT injection at P11, CITED2 was able to improve revascularization by 50% (p <0.001) and decrease neovascularization by 70% (p < 0.005) at all doses of CITED2 compared to IgG control. With IVT at P12, CITED2 peptide was able to improve revascularization by 40% (p <0.01) and decrease neovascularization by 70% (p <0.01) at 34ng CITED2 compared to IgG control. With IVT at P13, CITED2 was able to improve revascularization by 35% (p <0.05) at 3.4ng and 34ng and decrease neovascularization by 40% (p <0.05) at 34ng CITED2 compared to IgG control. With RNAseq, Hif-1α log fold expression increased by 0.3 (p <0.0001) at P11 and 0.17 (p <0.001) at P12 and did not change at P15 (-0.029, p=.29) compared to P6.
Conclusions :
These studies indicate that early intervention with CITED2, is effective in reducing avascular area and neovascularization in the hypoxic vascular retina. These studies suggest a potential strategy to combat pathological vasculature.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.