Links Between IL-7Rα Ligands and Th17 Cells in Immune Disorders

Abstract

The interleukin (IL)-7 receptor α-chain (IL-7Rα) is expressed on effector T cells, including T helper (Th) 17 cells. Its ligands IL-7 and thymic stromal lymphopoietin (TSLP) are suggested to play a role in regulating naive T cell differentiation into the different Th subsets. Of these subsets, Th17 cells are most recently discovered and associated with several immune disorders. This thesis discusses the IL-7Rα ligands and Th17 cells in health and disease and the relation between the two cytokines in immune disorders. IL-7 is proposed to promote Th1 and Th17 generation. In turn, cytokines produced by these cells prevent Th2 generation. TSLP drives Th2 development and inhibits differentiation into Th1 or Th17 cells. The balance between these different Th subtypes may be disturbed in immune disorders and could therefore be modulated by IL-7Rα ligands. As well, IL-7 induces secretion of proinflammatory cytokines TNF-α, IL-17 and IL-21. These cytokines have the potential to induce a positive feedback loop, resulting in more cytokine secretion and Th17 generation. Hence, they might contribute to immune disorders.