Identification of candidate genes involved in proliferative sickle cell retinopathy by RNAseq.

Abstract

Purpose : To compare gene expression profile of late endothelial progenitor cells from patients with hemoglobinopathy SC and proliferative sickle-cell retinopathy versus patients with hemoglobinopathy SC without retinopathy.

Methods : Late endothelial progenitor cells, also called Endothelial Colony-Forming Cells (ECFC) were isolated and cultured from peripheral blood samples of eight HbSC patients. Five patients had proliferative retinopathy and three showed no changes in the retina during ophthalmologic evaluation: fundus biomicroscopy, retinal mapping and retinography. The isolated ECFC were characterized by cobblestone morphology and flow cytometry. RNA was extracted from the cells and transcriptome analysis was performed by next-generation sequencing (RNA-seq). Differentially expressed genes between the two groups were identified through DESeq2 package.

Results : Comparative transcriptome analysis have identified 34 differentially expressed transcripts, 24 negatively regulated and 10 positively regulated. Among these genes, we highlight the most upregulated genes, ROBO1 and SLC38A5. Importantly, the expression of ROBO1 (log2FoldChange = 4,325 and padj value = 1,35E-11) and SLC38A5 (log2FoldChange = 3,364 and padj value = 1,59E-07) genes was significantly higher in patients with proliferative sickle-cell retinopathy than in patients without retinopathy.

Conclusions : The ROBO1-mediated pathway has been proposed as a target for the treatment of several ocular neovascular diseases, so our data suggest that sickle cell proliferative retinopathy may also benefit from therapeutic strategies blocking this pathway. The SLC38A5 gene is the principal mediator of glutamine transport in retinal Müller cells and its possible interaction with the LRP5 / Norrin / FZD4 signaling pathway has been reported. In addition, glutamine metabolism is crucial for vessel formation, since glutamine deprivation severely impaired endothelial cells proliferation and vessel sprouting in mice. Hence, the blockage of SLC38A5 transporter deserves further attention as an alternative strategy to inhibit pathological angiogenesis.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.