Selective inhibition of CD4 + T-cell cytokine production and autoimmunity by BET protein and c-Myc inhibitors

• DOI: 10.1073/pnas.1212264109
• Publication Date: 2012-08-22T00:17:07Z
• Authors: Hozefa S. Bandukwala; John Gagnon; Susan Togher; Jason A. Greenbaum; Edward D. Lamperti; Nigel J. Parr; Amy M. H. Molesworth; Nicholas Smithers; Kevin Lee; Jason Witherington; David F. Tough; Rab K. Prinjha; Bjoern Peters; Anjana Rao
• Keywords: CD4-Positive T-Lymphocytes; 0303 health sciences; Encephalomyelitis, Autoimmune, Experimental; Reverse Transcriptase Polymerase Chain Reaction; Gene Expression Profiling; Nuclear Proteins; Cell Differentiation; Flow Cytometry; Microarray Analysis; Real-Time Polymerase Chain Reaction; Adoptive Transfer; 3. Good health; Histones; Mice, Inbred C57BL; Benzodiazepines; Mice; 03 medical and health sciences; Gene Expression Regulation; Salivary alpha-Amylases; Animals; Cytokines; Positive Transcriptional Elongation Factor B; Phosphorylation

Bromodomain-containing proteins bind acetylated lysine residues on histone tails and are involved in the recruitment of additional factors that mediate histone modifications and enable transcription. A compound, I-BET-762, that inhibits binding of an acetylated histone peptide to proteins of the bromodomain and extra-terminal domain (BET) family, was previously shown to suppress the production of proinflammatory proteins by macrophages and block acute inflammation in mice. Here, we investigated the effect of short-term treatment with I-BET-762 on T-cell function. Treatment of naïve CD4 + T cells with I-BET-762 during the first 2 d of differentiation had long-lasting effects on subsequent gene expression and cytokine production. Gene expression analysis revealed up-regulated expression of several antiinflammatory gene products, including IL-10, Lag3, and Egr2, and down-regulated expression of several proinflammatory cytokines including GM-CSF and IL-17. The short 2-d treatment with I-BET-762 inhibited the ability of antigen-specific T cells, differentiated under Th1 but not Th17 conditions in vitro, to induce pathogenesis in an adoptive transfer model of experimental autoimmune encephalomyelitis. The suppressive effects of I-BET-762 on T-cell mediated inflammation in vivo were accompanied by decreased recruitment of macrophages, consistent with decreased GM-CSF production by CNS-infiltrating T cells. These effects were mimicked by an inhibitor of c-myc function, implicating reduced expression of c-myc and GM-CSF as one avenue by which I-BET-762 suppresses the inflammatory functions of T cells. Our study demonstrates that inhibiting the functions of BET-family proteins during early T-cell differentiation causes long-lasting suppression of the proinflammatory functions of Th1 cells.