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Retinoic acid receptor-related orphan nuclear receptor γ (RORγ) orchestrates a pro-inflammatory gene expression programme in multiple lymphocyte lineages including T helper type 17 (Th17) cells, γδ T cells, innate lymphoid cells and lymphoid tissue inducer cells. There is compelling evidence that RORγ-expressing cells are relevant targets for therapeutic intervention in the treatment of autoimmune and inflammatory diseases. Unlike Th17 cells, where RORγ expression is induced under specific pro-inflammatory conditions, γδ T cells and other innate-like immune cells express RORγ in the steady state. Small molecule mediated disruption of RORγ function in cells with pre-existing RORγ transcriptional complexes represents a significant and challenging pharmacological hurdle. We present data demonstrating that a novel, selective and potent small molecule RORγ inhibitor can block the RORγ-dependent gene expression programme in both Th17 cells and RORγ-expressing γδ T cells as well as a disease-relevant subset of human RORγ-expressing memory T cells. Importantly, systemic administration of this inhibitor in vivo limits pathology in an innate lymphocyte-driven mouse model of psoriasis. [ABSTRACT FROM AUTHOR]

Circadian rhythms govern a wide variety of physiological and metabolic functions in many organisms, from prokaryotes to humans. We previously reported that silent information regulator 1 (SIRT1), a NAD+-dependent deacetylase, contributes to circadian control. In addition, SIRT1 activity is regulated in a cyclic manner in virtue of the circadian oscillation of the coenzyme NAD+. Here we used specific SIRT1 activator compounds both in vitro and in vivo. We tested a variety of compounds to show that the activation of SIRT1 alters CLOCK:BMAL1-driven transcription in different systems. Activation of SIRT1 induces repression of circadian gene expression and decreases H3 K9/K14 acetylation at corresponding promoters in a time-specific manner. Specific activation of SIRT1 was demon- strated in vivo using liver-specific SIRT1-deficient mice, where the effect of SIRT1 activator compounds was shown to be dependent on SIRT1. Our findings demonstrate that SIRT1 can fine-tune circadian rhythm and pave the way to the development of pharmacological strategies to address a broad range of therapeutic indications. [ABSTRACT FROM AUTHOR]