Immunometabolic Endothelial Phenotypes: Integrating Inflammation and Glucose Metabolism

Rationale: Specific mechanisms linking inflammation and metabolic reprogramming—two hallmarks of many pathobiological processes—remain incompletely defined. Objective: To delineate the integrative regulatory actions governing inflammation and metabolism in endothelial cells. Methods and Results: Metabolomic profiling, glucose labeling and tracing, and Seahorse extracellular flux analyses revealed that the inflammatory mediators, TNFα (tumor necrosis factor alpha) and lipopolysaccharide, extensively reprogram cellular metabolism and particularly enhance glycolysis, mitochondrial oxidative phosphorylation (OXPHOS), and the pentose phosphate pathway in primary human arterial endothelial cells. Mechanistically, the enhancement in glycolysis and pentose phosphate pathway is mediated by activation of the NF-κB (nuclear factor-kappa B)–PFKFB3 (6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase 3) axis and upregulation of G6PD (glucose 6-phosphate dehydrogenase), respectively, while enhanced OXPHOS was attributed to suppression of the FOXO1 (forkhead box O1)-PDK4 (pyruvate dehydrogenase kinase 4) axis. Restoration of the FOXO1-PDK4 axis attenuated the TNFα- or lipopolysaccharide-induced increase in OXPHOS but worsened inflammation in vitro, whereas enhancement of OXPHOS by pharmacological blockade of PDKs attenuated inflammation in mesenteric vessels of lipopolysaccharide-treated mice. Notably, suppression of G6PD expression or its activity potentiated the metabolic shift to glycolysis or endothelial inflammation, while inhibition of the NF-κB–PFKFB3 signaling, conversely, blunted the increased glycolysis or inflammation in in vitro and in vivo sepsis models. Conclusions: These results indicate that inflammatory mediators modulate the metabolic fates of glucose and that stimulation of glycolysis promotes inflammation, whereas enhancement of OXPHOS and the pentose phosphate pathway suppresses inflammation in the endothelium. Characterization of these immunometabolic phenotypes may have implications for the pathogenesis and treatment of many cardiovascular diseases.