Mitochondrial control of hypoxia-induced pathological retinal angiogenesis

Abstract

Purpose : Retinopathy of prematurity (ROP) characterized by retinal dysfunction and neovascularization is a leading cause of childhood blindness worldwide. Underlying mechanisms remain poorly understood. Improving neural retinal metabolism might provide a potential therapeutic option for ROP. We aim to explore mitochondrial function and the effect of fuel substrate supplementation in oxygen-induced retinopathy (OIR) modeling proliferative ROP.

Methods : In OIR, mouse pups (C57BL/6J) and their nursing dam were exposed to 75% oxygen from postnatal day (P) 7 to P12 and returned to room air at P12 leading to formation of retinal neovascularization (NV) and vaso-obliteration (VO). Healthy control pups were kept in room air. At P17 in OIR vs. control retinas, global proteomics analysis was conducted with liquid chromatography separation/tandem mass spectrometry. Enrichr was used for pathway analysis. Mitochondrial vs. nuclear DNA copy numbers were analyzed. Oxygen consumption rates (OCR) of ex vivo OIR and control retinas were measured using a multichannel microfluidics system (BaroFuse). Pyruvate (50µg/g body weight) or vehicle control was injected intraperitoneally to OIR pups from P12 to P16. The vascular phenotype was assessed via isolectin B4 staining.

Results : Proteomics analysis identified 7,870 proteins (6,421 with ≥2 unique peptides). Confirming existing knowledge, hypoxia-inducible factor 1 abundance was increased in OIR vs. healthy control retinas (1.47-fold change, p<0.01, n=6 mice/group). Pathways such as mitochondrial respiration and synaptic vesicles were downregulated, while cell migration, platelet aggregation, and apoptosis were upregulated in OIR retinas. Mitochondrial/nuclear DNA copy number was decreased by 64.0% in OIR vs. controls (p<0.05, n=7-8 mice/group). OIR vs. control retinas showed reduced OCR (1.50 vs. 1.96 nmol/min/retina, p<0.01, n=3 retinas/group). Pyruvate vs. vehicle administration decreased NV by 20.5% (p<0.05, n=15 retinas/group). VO and body weight were unaffected. Pyruvate administration in ex vivo OIR retinas was able to sustain OCR upon glucose deprivation.

Conclusions : Our results demonstrated a critical role of mitochondrial function in hypoxia-induced retinal neovascularization and point to a potential therapeutic effect of fuel supplementation in ROP.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.