The Glycolysis Regulatory Enzyme PFK‐FB3 Enhances Endothelial Barrier Restoration in Acute Lung Injury

Acute lung injury (ALI) is a devastating inflammatory complication of infectious lung disease, characterized by a breakdown of the pulmonary vascular barrier and the subsequent formation of protein‐rich alveolar edema. In recent years, considerable advances have been made in the understanding of how intracellular signaling regulates the disruption and re‐assembly of adherens junctions (AJs) which are mediators of the endothelial barrier function. Little is known about the role of endothelial metabolism as a modulator of endothelial barrier function and its restoration in the setting of lung vascular injury. We hypothesized that the glycolysis regulatory enzyme PFK‐FB3 would support re‐annealing of the endothelial barrier because glycolysis allows for the local generation of ATP at the AJs. We observed a 2–3‐fold upregulation of PFK‐FB3, an enzyme which is a critical regulator of glycolytic activity, in response to inflammatory injury in human lung endothelial cells (p<0.05). ATP levels also increased at the AJs during recovery after LPS‐induced injury. Depletion of the hypoxia‐regulator transcription factor Hif1α attenuated the upregulation of PFK‐FB3, suggesting that hypoxic signaling activates PFK‐FB3 mediated upregulation of glycolysis. Suppression of PFK‐FB3 activity by either pharmacologic inhibition or genetic depletion delayed restoration of the endothelial barrier. In vivo delivery of liposomal PFK‐FB3, on the other hand, enhanced restoration of lung vascular barrier function in a model of experimental acute lung injury by 24 h (p<0.05). These findings suggest that upregulation of glycolysis via enhanced PFK‐FB3 activity serves as an endogenous metabolic adaptation to inflammatory vascular injury and facilitates endothelial barrier restoration. Support or Funding Information supported by NIH grant P01 HL60678‐16A1.