Quantitative proteomics of expanded resting and activated human MAIT (mucosal associated invariant T cells)

Mucosal associated invariant T (MAIT) cells are an abundant population of innate T cells that recognize bacterial ligands and play a key role in host protection against bacterial and viral pathogens. Upon activation, MAIT cells undergo proliferative expansion and increase their production of effector molecules such as cytokines. In this study, we found that mRNA and protein the abundance of the key metabolism regulator and transcription factor MYC was increased in stimulated MAIT cells. Using quantitative mass spectrometry, we identified the activation of two MYC controlled metabolic pathways, amino acid transport and glycolysis, both of which were necessary for MAIT cell proliferation. Finally, we showed that MAIT cells isolated from people with obesity showed decreased MYC mRNA abundance upon activation, which was associated with defective MAIT cell proliferation and functional responses. Collectively, our data uncovers the importance of MYC-regulated metabolism for MAIT cell proliferation and provides additional insight into the molecular basis for the functional defects of MAIT cells in obesity.