Chronic HIF1A activity in rod photoreceptors causes type 3 neovascularization and retinal atrophy

Morphological changes in the ageing eye impede oxygen delivery from the choroid to the outer retina causing tissue hypoxia, which activates a molecular response that adapts the transcriptomic fingerprint of the retina and retinal pigment epithelium (RPE). This response, orchestrated by hypoxia-inducible transcription factors (HIFs), leads to the production of pro-angiogenic factors and plays a critical role in the pathogenesis of age-related macular degeneration (AMD). To evaluate the specific contribution of HIF1 to this response we expressed a constitutively active form of HIF1A in rod photoreceptors of the adult mouse retina. This elicited a transcriptional response characterized by the upregulation of genes involved in cell death, inflammation and angiogenesis, all of which play an important role in AMD. The HIF1-mediated response in rods caused severe retinal degeneration, disruption of the RPE and retinal neovascularization. Pathological vessels originated from the deep vascular plexus and penetrated the RPE resembling type 3 macular neovascularization found in over 20% of neovascular AMD patients. Our study provides further evidence for the involvement of tissue hypoxia in the pathogenesis of AMD and highlights the potential of HIF1A as a potential therapeutic target.