Vitamin B1 Supports the Differentiation of T Cells through TGF-β Superfamily Production in Thymic Stromal Cells

Homeostatic generation of T cells, which occurs in the thymus, is controlled at least in part by endogenous cytokines and ligands. In addition, nutritional factors are other key regulators for the homeostasis of host immunity, but whether and how nutrition affects the homeostatic generation of thymocytes remains to be established. Here, we showed that vitamin B1 deficiency resulted in a bias toward the maturation of γδ thymocytes accompanied by decreased differentiation into double-positive thymocytes during thymic involution. These events were mediated through the increased production of TGF-β superfamily members due to the accumulation of branched-chain α-keto acids in thymic stromal cells. These findings revealed essential roles of vitamin B1 in the appropriate differentiation of T cells through the metabolism of thymic stromal cells.