Cytokine-induced Chromatin Accessibility in Whole Blood Neutrophils Links to Sepsis Transcriptional 1 States

BackgroundNeutrophils play an important role in the immune system and sense environmental perturbations including pathogens. Upon pathogen detection, neutrophils extrude their chromatin, forming neutrophil extracellular traps (NETs) trapping and removing pathogens. Previous studies have shown that controlled chromatin decondensation occurs during NET formation, reflecting NET inducing pathways, and the cellular environment. While NET inducing stimuli like phorbol 12-myristate 13-acetate (PMA) is commonly used to study NET formation, it bypassing regulatory mechanisms, limiting insights. MethodsWe used the Assay for Transposase-Accessible Chromatin with sequencing (ATAC-Seq) to profile chromatin accessibility in neutrophils stimulated in whole blood with PMA and physiologically relevant inflammatory factors (NFs), including TNF-, GM-CSF, fMLP, C5a, and IL-1{beta}, alone and in combination. Chromatin responses were compared across conditions and integrated with publicly available transcriptomic sepsis cohorts. ResultsWe found that NF stimulation induced stimulus specific chromatin accessibility programs distinct from PMA. Individual NFs increased specific transcription factor (TF) motif enrichments in a stimulus dependent manner, with GM-CSF increasing STATs, TNF- increasing NF-{kappa}B, C5a/fMLP increasing AP-1, and Combined with a cooperative response including CEBP. Integration with sepsis transcriptomic datasets revealed that promoter accessibility changes within NF stimulations correspond to transcriptional states associated with sepsis disease severity, highlighting the upstream regulatory programs linked to clinical outcomes. ConclusionsThese findings demonstrate that NF stimulation in whole blood reveals chromatin accessibility programs in neutrophils that correlate with disease severity in sepsis. This approach provides a framework for linking cytokine driven neutrophil regulation to heterogenous inflammatory states in sepsis and other NET-associated diseases.