Purchase this article with an account.
George Hoppe, Youstina Bolok, Leah McCollum, Charandeep Singh, Jonathan E Sears; Müller Cell HIF-2 is Not Required for Protection Against Oxygen Induced Retinopathy by Prolyl Hydroxylase Inhibition. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1655.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
The promise of hypoxia inducible factor (HIF) stabilization in the treatment of anemia secondary to chronic kidney disease and in the prevention of retinopathy of prematurity (ROP) is tempered by the concern that HIF stabilizers might exacerbate pathologic angiogenesis (neovascularization) associated with either diabetic retinopathy or with ROP. In the retina, pathologic angiogenesis is mediated by Müller cell macroglia that span the retina. We tested whether Müller cell HIF-2 activation was necessary to HIF stabilization induced prevention of oxygen-induced retinopathy (OIR) in order to determine whether Roxadustat, a 2-oxoglutarate analog, activates pathologic angiogenesis.
To generate conditional knockout of HIF-2α in Müller cells, mice carrying loxP-flanked Epas1were crossed to Pdgfra-Cremice. Newborn mice were subjected to 75% oxygen from postnatal day 7 (P7) to P12 and intraperitoneally injected three times with PBS or Roxadustat (10 μg/g) at P6, P8 and P10. At P17 retinal flat mount stained with isolectin B4; the areas of vaso-obliteration and neovascular tufts were measured using automated deep-learning software. Retinal HIF protein levels were assessed by western blotting after a single injection of Roxadustat at P8 and protein extraction 6 hrs later. Retinal gene expression was analyzed by next generation RNA sequencing.
Administration of Roxadustat during hyperoxia efficiently prevented OIR, and this effect was maintained in Müller cell HIF-2α KO mice. Systemic Roxadustat primarily upregulated HIF-1α when compared to HIF-2α in both liver and retina, but retinal HIF-2α is definitely increased by 50%. Retinal expression of the established HIF-2 targets that promote angiogenesis and endothelia cell migration, i.e., Arrdc3, Pparg, Mme, and Ralgps2, was not increased. When wild-type pups were treated with HIF stabilization after ischemia developed, there was an increase in vascular loss and a trend to increase neovascularization.
Roxadustat does not induce expression of HIF-2 dependent genes critical to pathological angiogenesis and HIF-2α stabilization is not required for Roxadustat induced vasoprotection and prevention of OIR. Nevertheless the upregulation of HIF-2 could provoke worsening of existent neovascularization and vasoobliteration and reinforces the need to use HIF stabilization to prevent ischemia, not react to it.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
This PDF is available to Subscribers Only