Short- and long-term impact of hyperoxia on the blood and retinal cells’ transcriptome in a mouse model of oxygen-induced retinopathy

Abstract

BACKGROUND: We aimed to identify global blood and retinal gene expression patterns in murine oxygen-induced retinopathy (OIR), a common model of retinopathy of prematurity, which may allow better understanding of the pathogenesis of this severe ocular prematurity complication and identification of potential blood biomarkers. METHODS: A total of 120 C57BL/6J mice were randomly divided into an OIR group, in which 7-day-old pups were maintained in 75% oxygen for 5 days, or a control group. RNA was extracted from the whole-blood mononuclear cells and retinal cells on days 12, 17, and 28. Gene expression in the RNA samples was evaluated with mouse gene expression microarrays. RESULTS: There were 38, 1370 and 111 genes, the expression of which differed between the OIR and control retinas on days 12, 17, and 28, respectively. Gene expression in the blood mononuclear cells was significantly altered only on day 17. Deptor and Nol4 genes showed reduced expression both in the blood and retinal cells on day 17. CONCLUSION: There are sustained marked changes in the global pattern of gene expression in the OIR mice retinas. An altered expression of Deptor and Nol4 genes in the blood mononuclear cells requires further investigation as they may indicate retinal neovascularization.

In-depth transcriptomic analysis of human retina reveals molecular mechanisms underlying diabetic retinopathy

“…Several transcriptomic studies analyzing retinae of animal models in the context of DR have been carried out, including Streptozotocin (STZ) induced diabetic rodents models 6 – 8 , and models of oxygen-induced retinopathy (OIR) 9 , 10 . Another focus has been the measurement of small non-coding RNA in blood of DR patients 11 – 15 .…”

Gene expression profile of the murine ischemic retina and its response to Aflibercept (VEGF-Trap)

“…While these approaches offer the possibility to dissect the heterogeneity of cellular responses with high resolution and to identify novel gene isoforms, they often select for polyadenylated transcripts and might be limited by sequencing depth. In contrast, microarrays robustly detect both highly and lowly expressed genes, non-coding RNAs and predicted sequences 113 . On this basis, microarrays have been extensively used to study the retinal transcriptome 74 , 113 – 116 , with us being the first to use them for investigating the response of the OIR retina to AFL administration 22 .…”

“…In contrast, microarrays robustly detect both highly and lowly expressed genes, non-coding RNAs and predicted sequences 113 . On this basis, microarrays have been extensively used to study the retinal transcriptome 74 , 113 – 116 , with us being the first to use them for investigating the response of the OIR retina to AFL administration 22 . Further, as retinopathy gives rise to complex phenotypic features involving and affecting most retinal cell types 3 , studying the tissue as a whole might be advantageous to understand the pathogenesis of retinal ischemic diseases at the systemic level.…”

“…To validate our results, we aimed at comparing them with previously published datasets. However, most studies used distinct time-points or focused on just a subset of genes 113 . Moreover, when comparing with suitable studies, we detected divergences potentially arising from thresholding differences, the presence of sex chromosome-linked genes (omitted in our study), the use of distinct animal species, and/or modifications to the OIR protocol 19 (we started hyperoxia one day earlier).…”

“…Two more genes prominently involved in angiogenesis and modulated by AFL were Esm1 and Cd34 . Esm1 has been previously reported as a top overexpressed gene in OIR retinas at P17 113 , 119 and plays a role in both pathological and physiological angiogenesis, modulating VEGF bioavailability and regulating leukocyte extravasation 128 . Moreover, increased expression of Esm1 enhances the proliferative capacity, colony forming ability, migration and invasiveness of radiotherapy-resistant breast cancer cells all by itself, with its down-regulation reversing these effects 129 .…”