T cell-based cellular therapies benefit from a product with reduced differentiation and enhanced oxidative metabolism. Methods to achieve this balance without negatively impacting T cell expansion or impairing T cell function have proven elusive. AMP-activated protein kinase (AMPK) is a cellular energy sensor which promotes mitochondrial health and improves oxidative metabolism. We hypothesized that increasing AMPK activity in human T cells would augment their oxidative capacity, creating an ideal product for adoptive cellular therapies. Lentiviral transduction of the regulatory AMPKγ2 subunit stably enhanced intrinsic AMPK signaling and promoted mitochondrial respiration with increased basal oxygen consumption rates (OCR), higher maximal OCR, and augmented spare respiratory capacity. These changes were accompanied by increased mitochondrial density and elevated expression of proteins involved in mitochondrial fusion. AMPKγ2-transduction also increased T cell glycolytic activity. This combination of metabolic reprogramming enhanced in vitro T cell expansion while promoting memory T cell yield. Finally, when activated under decreasing glucose conditions, AMPKγ2-transduced T cells maintained higher levels of both proliferation and inflammatory cytokine production. Together, these data suggest that augmenting intrinsic AMPK signaling via overexpression of AMPKγ2 can improve the expansion and function of human T cells for subsequent use in adoptive cellular therapies.

BACKGROUND Adoptive immunotherapies are limited by the increased differentiation and metabolic exhaustion of the T cell product. The cellular energy sensor AMP-activated protein kinase (AMPK) controls many metabolic pathways. We hypothesized that increasing AMPK signaling during T cell expansion would create more metabolically efficient T cells. RESULTS Human T cells were stimulated in vitro, expanded with or without AMPK agonist A769662, and restimulated under varying glucose concentrations. Agonist treatment increased T cell expansion by manual cell counts (1.5× increase in cell number, p<0.01), and produced a higher percentage of CD62L+CD27+ cells by flow cytometry (10% increase, p<0.01). Twenty-four hours after re-stimulation, agonist-treated cells exhibited decreased basal oxygen consumption and extracellular acidification rates (45% and 20% decrease, p<0.001) but increased spare respiratory capacity (SRC) (97% increase, p<0.001). At 72 hours, control cells decreased proliferation in a glucose dose-dependent manner, as measured by BrDU uptake, whereas treated cells maintained a higher level of proliferation despite limited glucose availability. DISCUSSION Increasing AMPK signaling during T cell expansion improves doubling time while maintaining higher CD27 positivity, suggesting a greater yield of less differentiated cells. Upon re-stimulation, treated cells initiate less metabolic activity but maintain greater proliferation and SRC under glucose-limiting conditions. These results suggest that greater metabolic efficiency in agonist-treated cells allows for continued function despite nutrient restriction, a trait which could confer significant advantages to adoptive immunotherapies. Supported by grants from NIH (5K12 HD052892) and the St. Baldrick's Foundation (St. Baldrick's Fellowship Grant)