Gene Expression Analysis Of Retinas From -3-PUFAs And -6-PUFAs Fed Mice In Oxygen-induced Retinopathy (OIR) Model

Abstract

Purpose: : We have previously demonstrated that, in a mouse model of oxygen-induced retinopathy (OIR) that dietary ω-3-polyunsaturated fatty acids (PUFAs) protect against pathological neovascularization (NV) after vessel loss by promoting normal vascular regrowth thereby decreasing avascular area and decreasing stimulus for pathological NV. To further explore the factors and signaling pathways promoting regrowth of normal vessels in ω-3-PUFAs-fed versus ω-6-PUFAs-fed mice, we performed Illumina microarray analysis on retinas at P14 after exposure to hyperoxia (P7-P12) with vessel loss and return to room air when vessels are regrowing (P12-P17).

Methods: : C57BL/6 mouse mothers at delivery were fed a defined rodent diet with 10% (w/w) safflower oil containing either 2% ω-6-PUFAs (arachidonic acid) or 2% ω-3-PUFAs (DHA and EPA). Retinopathy was induced by exposing neonatal mice with their nursing mother to 75% oxygen from postnatal day (P) 7 to P12 and returning them to room air. Retinas from P14 pups were isolated. Total RNA was extracted and prepared for microarray analysis with Illumina Mouse-ref 6 chip. Data were acquired using BeadStudio software and analyzed with Significance Analysis of Microarrays (SAM) program and BIOBASE.

Results: : Using p<0.05 and a 1.5 fold change cutoff of gene expression, we identified 612 up-regulated and 597 down-regulated genes in ω-3-PUFAs-fed compared to ω-6-PUFAs-fed mice at P14. Consistent with a cyto-protective role of ω-3-PUFAs, our Gene-Ontology (GO) analysis revealed that anti-apoptosis genes such as Atm, Bcl2 are ~2.5 fold up-regulated by ω-3-PUFAs. On the other hand, ω-3-PUFAs down-regulates key genes involved in the response to hypoxia and oxidative stress such as Adm (8.6 fold), Vegf (3.0 fold) and Angptl4 (2.5 fold).

Conclusions: : These findings suggest that ω-3-PUFAs may be responsible for neuroprotection in retina during OIR by repressing cell apoptosis and hypoxia responses, thereby resulting in an enhanced vascular regrowth and a less severe pathological neovascularization.

Keywords: lipids • retinal neovascularization • oxidation/oxidative or free radical damage