Abstract
Purpose :
Retinopathy of prematurity (ROP) causes 100,000 new cases of childhood blindness each year. We have previously demonstrated the efficacy of hypoxia inducible factor (HIF) stabilization in the liver through systemic HIF prolyl hydroxylase inhibition in protecting retinal vasculature from oxygen-induced retinopathy (OIR, animal model of ROP) using dimethyloxalylglycine (DMOG). In order to define the molecular mechanism of protection, we further compare retinal and hepatic transcriptomes of mice treated with isoquinolone Roxadustat (RXD) that is currently in phase 3 clinical trials for treating anemia in patients with chronic kidney disease, to DMOG.
Methods :
Next generation RNA sequencing was performed on three sets of liver and retinal tissue from PBS-, DMOG-, or RXD-injected mice, respectively. The reads were aligned to the mouse transcriptome, abundance of the assembled transcripts was estimated as FPKM values and the cuffdiff program was used to determine differential gene expression analysis. In silico analyses of affected pathways and functions were performed using both licensed as well as open-access software tools and databases (IPA, Metacore, DAVID). Secondary validation of selected gene products was performed by RT-qPCR, serum ELISA, retinal IHC, Western blot and HIF reporter transgenic mouse.
Results :
RXD induces vascular protection during hyperoxia with a 3-fold reduction in oxygen-induced capillary loss. Similar gene expression profiles were identified in liver but very different effects on transcription were found in retinal tissues because RXD, in contrast to DMOG, directly targets retina, confirmed by retinal HIF Western, by the induction of HIF-regulated genes the retina and by rescue of the hepatic HIF-1 knockout from OIR, criteria that DMOG is unable to fulfill. Stratification of liver transcriptomes to secreted gene products again shows close consensus of hepatic genes induced by both small molecules, and includes upregulation of PAI-1, EPO, and ORM2 further confirmed by serum ELISA.
Conclusions :
These findings demonstrate that systemic HIF stabilization can prevent OIR by two pathways: direct retinal HIF stabilization and induction of aerobic glycolysis or indirect, hepatic HIF stabilization and increased serum angiokines. Systems pharmacology analysis provides a rationale for considering low dose, intermittent systemic administration of RXD to eradicate ROP in children.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.