Genome-wide Analyses of Chromatin State in Human Mast Cells Reveal Molecular Drivers and Mediators of Allergic and Inflammatory Diseases

Mast cells (MCs) are versatile immune cells capable of rapidly responding to a diverse range of extracellular cues. Here, we mapped the genomic and transcriptomic changes in human MCs upon diverse stimuli. Our analyses revealed broad H3K4me3 domains and enhancers associated with activation. Notably, the rise of intracellular calcium concentration upon immunoglobulin E (IgE)-mediated crosslinking of the high-affinity IgE receptor (Fc epsilon RI) resulted in genome-wide reorganization of the chromatin landscape and was associated with a specific chromatin signature, which we term Ca2+dependent open chromatin (COC) domains. Examination of differentially expressed genes revealed potential effectors of MC function, and we provide evidence for fibrinogen-like protein 2 (FGL2) as an MC mediator with potential relevance in chronic spontaneous urticaria. Disease-associated singlenucleotide polymorphisms mapped onto cis-regulatory regions of human MCs suggest that MC function may impact a broad range of pathologies. The datasets presented here constitute a resource for the further study of MC function.