Direct Suppression of Pathological Neovascularization in a Mouse OIR Model

Abstract

Purpose: : Retinopathy of prematurity (ROP) and diabetic retinopathy, leading causes of blindness, are characterized by two critical phases: vessel loss followed by hypoxia-driven pathological neovascularization (NV). Previously, we found that a ω-3 long-chain polyunsaturated fatty acid (LCPUFA) enriched diet (DHA and EPA) given from birth protected mice from oxygen-induced retinopathy, relative to ω-6 LCPUFA fed mice. The ω-3 LCPUFA diet prevented pathological NV through revascularization of hypoxic retina but had no effect on vessel loss. Although we showed that with early feed, suppression of NV occurs by increased re-growth of normal vessels it had not been determined if a ω-3 LCPUFA diet would directly increase or suppress pathological NV if given late in the course of the disease.

Methods: : We exposed C57Bl/6 mice to a ω-3 or ω-6 LCPUFAs from birth or starting at P12 or P15 during the development of NV (after O2 induced vessel loss (P7-12)) in oxygen-induced retinopathy. The fatty acid profile of the mother’s milk reflects the mother’s diet. We quantified retinal vaso-obliteration and revascularization on P17.Retinal RNA was isolated for real-time PCR analysis.

Results: : Pathological retinal NV was significantly reduced in the ω-3 (~50%, P<0.001), relative to ω-6 LCPUFA mice within the P12 and P15 feeding paradigms. No difference in the revascularization of vaso-obliterated areas at post-natal day 17 existed between the two dietary groups or in expression of macrophage-associated genes. Differential expression of genes for the pro-inflammatory molecules Tnf- and Icam1 (~35%, P<0.01) and in vascular endothelial growth factor (~50%, P<0.001) existed through the later stages of disease with the ω-3 LCPUFA group showing relatively lower values. As previously found, mice fed a ω-3 vs. ω-6 LCPUFA diet from birth had significantly less pathological retinal NV and an increase in vessel re-growth (4.3+/-0.7% vs. 8.3+/-0.8%, p ≤ 0.001); in the ω-3 group we observed a significant decrease in expression of macrophage-related genes and those of associated pro-inflammatory molecules.

Conclusions: : These data indicate that dietary ω-3 LCPUFAs administered after vaso-obliteration can reduce severity of pathological retinal NV and may alter gene expression of the pro-inflammatory factors implicated in this process.

Keywords: lipids • retinal neovascularization • retinopathy of prematurity