Role of Th17 Cells in the Pathogenesis of Human IBD

Figure 3

Th1/Th17 balance. Th17 cells exhibit plasticity towards the Th1 phenotype: Th17/Th1 cells or Th17-driven Th1 cells are cells capable of producing both IL-17 and IFN-𝛾. Th1 cells that derive from Th17 cells can be identified by the expression of CD161, a signature surface marker of Th17 cells progenitors, as opposed to classic CD161⁻ Th1 cells. TGF𝛽 is required for sustained expression of IL-17F and IL-17A, but in the absence of TGF𝛽, both IL-23 and IL-12 downregulate ROR𝛾t and upregulate T-bet expression, which may result in the suppression of IL-17 and enhancement of IFN-𝛾 production, in a STAT4- and T-bet-dependent manner.