Establishment, Maintenance and Recall of Inflammatory Memory

Known for nearly a century, but through mechanisms that remain elusive, cells retain a memory of inflammation that equips them to react quickly and broadly to diverse secondary stimuli. Using mouse epidermal stem cells as a model, we elucidate how cells establish, maintain and recall inflammatory memory. Specifically, we landscape and functionally interrogate temporal, dynamic changes to chromatin accessibility, histone modifications and transcription factor binding that occur during inflammation, post-resolution and in memory recall following injury. We unearth an essential, unifying role for the general stress-responsive transcription factor FOS, which partners with JUN and cooperates with stimulus-specific STAT3 to establish memory; JUN then remains with other homeostatic factors on memory domains, facilitating rapid FOS re-recruitment and gene re-activation upon diverse secondary challenges. Extending our findings, we offer a comprehensive, potentially universal mechanism behind inflammatory memory and less discriminate recall, phenomena with profound implications for tissue fitness in health and disease. Overall design: ATAC-Seq, CUT&RUN, ChIP-seq