Phospho-enol pyruvate carboxykinase inhibition limits inflammatory T cell activation

Following antigenic stimulation, T cells switch from a catabolic metabolic state maintained by low levels of nutrient uptake to an anabolic metabolism that sustains the biosynthetic and energetic demands of clonal expansion, differentiation and effector function. Much progress has been made in understanding the transcriptional and enzymatic regulation of activated T cell metabolism. However less is understood of the role for regulators of anaplerosis and cataplerosis such as phospho-enol pyruvate carboxykinases (PEPCK) in T cells. In the current work, we show that mitochondrial isoform PEPCK-M is upregulated following T cell activation whilst cytosolic PEPCK-C is not expressed. PEPCK inhibitors limited CD8+ T cell cytotoxic capacity and both CD4+ and CD8+ T cell inflammatory cytokine production. Suppression of T cell effector functions by PEPCK inhibitors was associated with decreased maximal mitochondrial respiration. These data suggest that PEPCK-M acts as a metabolic rheostat to enable optimal T cell activation.