Transcriptional regulation of the Th17 immune response by IKK(alpha).

Th17 cells are a subset of T cells that play crucial roles in the pathogenesis of many inflammatory diseases. We report here the identification of IKKα (inhibitor of NF-κB kinase-α) as a key transcriptional regulator of the Th17 lineage. T cells expressing a nonactivatable form of IKKα were significantly compromised in their ability to produce IL-17 and to initiate neural inflammation. IKKα is present in the nuclei of resting CD4(+) T cells. Upon Th17 differentiation, IKKα selectively associated with the Il17a locus, and promoted its histone H3 phosphorylation and transcriptional activation in a NF-κB-independent manner. These findings indicate that nuclear IKKα maintains the Th17 phenotype by activating the Il17a gene.