Control of Th17 Cell Development Through Cooperative Transcriptional Activities of Class IIa HDAC4 and HDAC7

Histone deacetylases (HDACs) are long recognized for important functions in regulating gene transcription in biology and diseases. However, unlike for ubiquitously expressed class I HDACs, we have little mechanistic understanding of class II HDACs that have postulated tissue specific functions. Here we report that class IIa Hdac4 and Hdac7 are up-regulated in transcription through IL-6-Stat3 signaling selectively in mouse T-helper 17 (Th17) cells during lineage-specific differentiation, but not in Th1, Th2, and Treg subtypes. Genetic knockout of Hdac4 or Hdac7 established their importance for Th17 differentiation with different functional mechanisms. Hdac4 works with Th17 transcription factors JunB-Irf4-Batf for transcriptional activation of Th17 signature genes Il17a/f, whereas Hdac7 acts distinctively in concert with Aiolos/Ncor1/Hdac3 co-repressor complex for transcriptional repression of Th17 negative regulators including Il2. Pharmacological inhibition or gene knockout of Hdac4 and Hdac7 ameliorates development of T-cell transfer induced colitis and experimental autoimmune encephalomyelitis (EAE) in mice through blockage of Th17 cell development in colon and central nervous system that recapitulate inflammatory bowel diseases and multiple sclerosis in humans, respectively. Our study highlights a previously unknown distinct mechanisms of Hdac4 and Hdac7 in transcriptional control of Th17 cell development, and rationalizes a new therapeutic strategy of targeting class IIa HDAC4/7 for the treatment of Th17-related inflammatory and autoimmune diseases. Overall design: Murine Th17 cells were treated with TMP269 and collected for RNA-seq along with non-treatment controls. Genome-wide occupancy of Hdac proteins was assessed in Th17 cells using specific antibodies.