Figure 1.
Development of pathogenic Th17 cells. Synergistic exposure to TGF-β and IL-6 induces transcription factors RORγt and Foxp3 to produce IL-17, IL-21 and an anti-inflammatory cytokine IL-10. Another way of inducing Th17 cells is synergistic exposure to IL-6 and IL-1β, which are produced under influence of TNFα. However, exposure to IL-23 induces receptor IL-23R to produce IL-17, IL-21, IL-22 and GM-CSF, therefore making Th17 cells pathogenic. Furthermore, it has been shown that IL-23 reduces the concentrations of IL-10, additionally contributing to Th17 pathogenicity.
