Bromodomain and extra-terminal protein inhibitors modulate natural killer cell function and differentiation.

Natural killer (NK) cells are integral to the innate immune system, playing a crucial role in immune surveillance and the rapid response to virally infected and tumor cells. Epigenetic gene expression regulation significantly influences NK cell function and differentiation. Using a high-throughput small-molecule drug screening approach, we identified bromodomain and extra-terminal domain (BET) inhibitors (BETi) as potent modulators of NK cell function, reducing proinflammatory cytokine secretion while increasing markers of NK cell maturation and cytotoxicity. During NK lineage specification from hematopoietic stem cells, we demonstrated that BETi reduced NK cell fate and promoted increased myeloid cell differentiation. Moreover, differentiated NK cell types had more functionally differentiated gene expression programs. Thus, BET proteins are crucial for both mature NK cell functions and controlling NK cell lineage development from progenitors in the bone marrow. These findings suggest that BETi can fine-tune NK cell responses, offering promising therapeutic potential for cancer immunotherapy and the treatment of inflammatory and autoimmune diseases. Our study underscores the critical role of BET inhibitors in regulating NK cell function and opens new avenues for targeted immune modulation.