Gata3 plays a supportive role for the development of Tbet-expressing Th17 cells in EAE

Abstract

Abstract IFNg+IL-17A+(or Tbet+RORgt+) Th17 cells are known to be key players in the pathology of experimental autoimmune encephalomyelitis (EAE), however the dynamics and overall stability of Tbet+ Th17 cells is less clear. Recent data from our lab (Zhong, C. et.al. 2016) has demonstrated that Gata3 plays a role in deciding the balance between Tbet and RORgt expression in gut NKp46+ ILC3 cells. Here, we hypothesized that Gata3 might be expressed by Th17 cell subsets during EAE, and that Gata3 expression would affect the generation or functionality of Tbet-expressing Th17 cells. Surprisingly, we found that all differentiating polyclonal and 2D2 transgenic Th17 cells upregulate Gata3 and subsequently maintain low levels of Gata3 thereafter, both in vitro and in vivo. Additionally, the re-stimulation or re-polarization of Th17 cells does not further affect Gata3 expression, reaffirming that Gata3 is induced during de novo Th17 polarization. To examine how the loss of Gata3 might affect the generation of Th17 or Tbet+ Th17 cells in EAE, we utilized complimentary Gata3 conditional knockout models. In a tamoxifen-inducible Gata3 knockout system, Tamoxifen treated CreERT2 Gata3Fl/Flmice (d6 P.I.) were resistant to EAE, and failed to mount a robust Tbet+Th17 response in comparison to vehicle controls. Similarly, Tbet-dependent Gata3 knockout Tbx21CreGata3Fl/Flmice failed to mount a robust Tbet+ Th17 response in the dLN or CNS, and were resistant to EAE symptoms in active and passive EAE models. Together, these data suggest that while all Th17 cells induce and maintain Gata3 expression, Tbet+ Th17 cells require Gata3 for their generation and survival in EAE. This research was supported by the Intramural Research Program of NIAID, NIH.