Inflammatory activation of endothelial cells increases glycolysis and oxygen consumption despite inhibiting cell proliferation

Endothelial cell function and metabolism are closely linked to differential use of energy substrate sources and combustion. While endothelial cell migration is promoted by 2‐phosphofructokinase‐6/fructose‐2,6‐bisphosphatase (PFKFB3)‐driven glycolysis, proliferation also depends on fatty acid oxidation for dNTP synthesis. We show that inflammatory activation of human umbilical vein endothelial cells (HUVECs) by interleukin‐1β (IL‐1β), despite inhibiting proliferation, promotes a shift toward more metabolically active phenotype. This was reflected in increased cellular glucose uptake and consumption, which was preceded by an increase in PFKFB3 mRNA and protein expression. However, despite a modest increase in extracellular acidification rates, the increase in glycolysis did not correlate with extracellular lactate accumulation. Accordingly, IL‐1β stimulation also increased oxygen consumption rate, but without a concomitant rise in fatty acid oxidation. Together, this suggests that the IL‐1β‐stimulated energy shift is driven by shunting of glucose‐derived pyruvate into mitochondria to maintain elevated oxygen consumption in HUVECs. We also revealed a marked donor‐dependent variation in the amplitude of the metabolic response to IL‐1β and postulate that the donor‐specific response should be taken into account when considering targeting dysregulated endothelial cell metabolism. Inflammatory activation of human umbilical vein endothelial cells (HUVECs) by interleukin‐1β (IL‐1β) increases glucose uptake and consumption, and simultaneously inhibits cell proliferation. Despite reducing fatty acid oxidation, IL‐1β also increases oxygen consumption rates while maintaining extracellular lactate levels. Our observations suggest that increased glycolysis in IL‐1β‐stimulated HUVECs predominantly fuels an increase in mitochondrial pyruvate metabolism.