Endothelial dysfunction in acute myocardial infarction: cell-autonomous metabolic reprogramming and oxidative stress.

Background: Compelling evidence has accumulated on the role of oxidative stress on the endothelial cell (EC) dysfunction underlying acute coronary syndrome. However, unveiling the underlying metabolic determinants has been hampered by the scarcity of appropriate cell models to address cell-autonomous mechanisms of ED dysfunction. Methods: We have generated endothelial cells derived from thrombectomy specimens from patients affected with acute myocardial infarction (AMI) and conducted phenotypical and metabolic characterization, focused on central carbon metabolism. Results: AMI-derived endothelial cells (AMIECs), but not control healthy coronary endothelial cells, display impaired growth, migration and tubulogenesis. Metabolically, AMIECs displayed augmented reactive oxygen species (ROS) and glutathione intracellular content, along with a diminished glucose consumption coupled to high lactate production. Consistent with diminished glycolysis in AMIECs, the protein levels of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase type 3, PFKFB3, were downregulated. In contrast, PFKFB4 levels were upregulated, suggesting a shunting of glycolysis towards the pentose phosphate pathway (PPP), supported by upregulation in AMIECs of G6PD, the key enzyme in the oxidative branch of the PPP. Further, the glutaminolytic enzyme GLS was upregulated in AMIECs, providing a mechanistic explanation for the observed increase in glutathione content. Finally, AMIECs displayed a significantly higher mitochondrial membrane potential than control ECs, which, together with high ROS levels, suggest a highly coupled mitochondrial activity in patient ECs. Conclusions: We suggest high mitochondrial proton coupling underlies the abnormally high production of ROS, balanced by PPP- and glutaminolysis-driven synthesis of glutathione, as a primary, cell-autonomous abnormality driving EC dysfunction in AMI. Funding: European Commission Horizon 2020; CIBER- Carlos III National Institute of Health, Spain; Ministerio de Economia y Competitividad (MINECO) and Ministerio de Ciencia e Innovación, Spain; Generalitat de Catalunya-AGAUR, Catalonia; Plataforma Temática Interdisciplinar Salud Global (PTI-SG), Spain; British Heart Foundation, UK.