Memory is no longer a privilege of adaptive immunity. Innate immune cells can exhibit a long-term immune activation after infection or vaccination, which is called "trained immunity." In addition to defense against mycobacterial infection, BCG-induced trained immunity can also exert nonspecific protection, which is regulated by metabolic rewiring and epigenetic reprograming. Enhanced glycolysis and glutamine-driven tricarboxylic acid cycle have been proven to be important metabolic pathways for trained immunity induced by BCG, which is dependent on Akt/mTOR pathway.
Keywords: BCG; glucose; macrophage; metabolism; trained immunity.