Differential effects of glutamine inhibition strategies on anti-tumor CD8 T cell function
Activated T cells undergo metabolic reprogramming to meet anabolic, differentiation, and functional demands. Glutamine supports many processes in activated T cells, and inhibition of glutamine metabolism alters T cell function in autoimmune disease and cancer. Multiple glutamine-targeting molecules are under investigation, yet the precise mechanisms of glutamine-dependent CD8 T cell differentiation remain unclear. We show that distinct strategies of glutamine inhibition by glutaminase-specific inhibition with small molecule CB-839, pan-glutamine inhibition with 6-diazo-5-oxo-L-norleucine (DON), or by glutamine deprivation (No Q) produce distinct metabolic differentiation trajectories in CD8 T cells. T cell activation with CB-839 treatment had a milder effect than DON or No Q treatment. A key difference was that CB-839-treated cells compensated with increased glycolytic metabolism, while DON and No Q-treated cells increased oxidative metabolism. However, all glutamine treatment strategies elevated CD8 T cell dependence on glucose metabolism, and No Q treatment caused adaptation toward reduced glutamine dependence. DON treatment reduced histone modifications and numbers of memory-like cells in adoptive transfer studies, but those T cells that persisted could expand normally upon secondary antigen encounter. In contrast, No Q-treated cells persisted well yet demonstrated decreased secondary expansion. Consistent with impaired function, CD8 T cells activated in the presence of DON had reduced ability to control tumor growth and reduced tumor infiltration in adoptive cell therapy. Overall, each approach to inhibit glutamine metabolism confers distinct effects on CD8 T cells and highlights that targeting the same pathway in different ways can elicit opposing metabolic and functional outcomes. Overall design: Uinsg RNAseq and CUT&RUN to profile how glutamine metabolism reprogram CD8+ T cell function.