PLZF supports the acquisition and maintenance of the Th17 phenotype in human cells (CCR5P.250)

All human Th17 cells express the chemokine receptor CCR6, making CCR6 a potential therapeutic target. We hypothesized that the variable levels of CCR6 expression on blood CD4+ T cells reflect a continuum of Th17 differentiation, and that regulators of Th17 differentiation could be identified by evaluating global changes in gene expression in cells with increasing levels of CCR6. We found that ZBTB16, which encodes the BTB-ZF transcription factor PLZF, was expressed at increasing levels from the CCR6- to CCR6bright subsets and was poorly expressed in Th1, Th2, and TFH cells. Knockdown of ZBTB16 mRNA down-regulated CCR6 and other Th17-associated genes such as RORC, IL17A, IL22, and IL23R in CCR6+ memory Th cells from blood and in naive cells activated under Th17 conditions ex vivo. In naive Th cells from cord blood, ZBTB16 expression was limited to the CD161+, Th17 cell precursors. ZBTB16 was not expressed in mouse Th17 cells and Th17 cells could be made from luxoid mice. Using ChIP for modified histones, p300, and Pol II to analyze CCR6, we identified regulatory regions at -10 and -14 kb from the TSS. We detected PLZF binding at these sites in the CCR6+ cells, which was diminished in cells transfected with ZBTB16 siRNA. These studies demonstrate a novel role for PLZF as a transcriptional activator important both for Th17 differentiation and for the maintenance of the Th17 phenotype in human cells, and an expanded role for the BTB-ZF family in the human immune system.