Endothelial Cell Metabolism Determines Healthy or Diseased Revascularization of the Ischemic Retina

Authors: Sheetal Pundir  ¹, Gael Cagnone², Jin Sung Kim³, Florian Wünnemann⁴, Clary B. Clish⁵, Bruno Maranda⁶, Sergio Crespo-Garcia⁷, Gregor Andelfinger⁸, Jean Sébastien Joyal⁹.  ¹McGill University Health Centre, ²CHU St.Justine, ³McGill University, ⁴Montreal Heart Institute, ⁵The Broad institute of MIT and Harvard University, ⁶Sherbrooke University, ⁷Hôpital Maisonneuve-Rosemont, ⁸University of Montreal, ⁹University of Montreal, CHU St. Justine.

Author Disclosures: S. Pundir:   None.  G. Cagnone:   None.  J. Kim:   None.  F. Wünnemann:   None.  C.B. Clish:   None.  B. Maranda:   None.  S. Crespo-Garcia:   None.  G. Andelfinger:   None.  J.S. Joyal:   None.

Abstract Body: 

Purpose:   Glycolysis and fatty acid oxidation are known energy sources for endothelial cells to support angiogenesis, but the specific metabolic reliance of physiological and pathological neovessels is ill-defined.    We have studied the role of fatty acid oxidation and glycolysis in pathological angiogenesis in diabetic retinopathy and in mouse model of retinopathy of prematurity.   

Study Design:   Basic (experimental)   Methods:   We used a multiomics approach to study the metabolic hallmarks of physiological and pathological angiogenesis in proliferative retinopathies. We compared the metabolomic profile of human vitreous from proliferative diabetic retinopathy subjects to a mouse model of proliferative retinopathy (PR). In mouse PR we enriched retinal endothelial cells and performed a single-cell transcriptomics analysis to identify transcriptional signature for pathological neovessels.   

Results:   Physiological angiogenesis revascularizes the ischemic retina, while misguided pathological neovessels grow towards the vitreous. We analysed the metabolite profile in vitreous humor samples from patients with proliferative diabetic retinopathy. We observed an accumulation of fatty acyl carnitines, by-products of mitochondrial fatty-acid-oxidation (FAO) in diabetic retinopathy samples compared to controls. In mouse PR, using unbiased large-scale approaches combining metabolomics and single-cell transcriptomics, we observed distinct metabolic pathways define glycolytic migratory tip endothelial cells (ECs), essential to the regenerative process, and misguided yet actively proliferating neovascular endothelial cells (nvECs) that rely instead on fatty acid oxidation. Direct comparison showed 449 differentially expressed genes (DEGs) between healthy tip EC and nvEC (P value < 0.05, log2(FC) > 0.5. nvECs up-regulated genes were significantly enriched in pathways such as fatty-acid degradation, tyrosine and nicotinamide metabolism, whereas tip ECs were enriched for extra-cellular matrix-receptor interaction, and glycolysis. Inhibition of FAO in ischemic retina primed endothelial metabolism to glycolysis, accelerated physiological revascularization and improved visual function.  

Conclusions:   In this study, we have defined the metabolic traits of the healthy and diseased vasculature in proliferative retinopathy. Our results illustrate shifting the metabolism towards glycolysis can inhibit pathological vessel formation and improve vision. We identified fatty acid oxidation as a metabolic hallmark of pathological angiogenesis.