Immature neutrophil subsets and emergency granulopoiesis drive sepsis immune suppression and a specific extreme response to infection [HSPC_ECG]
Sepsis, the dysregulated host response to infection leading to organ dysfunction, arises from diverse mechanisms that are poorly resolved by sepsis as a syndromic classification, confounding immunotherapy trials. Here we delineate neutrophil and granulopoietic disturbances underlying sepsis pathophysiology. We present a whole blood single-cell multiomic sepsis response atlas (272,993 cells, n=39 individuals), revealing multiple immature neutrophil populations that were collectively immunosuppressive, inhibiting CD4+ T cell proliferation and activation in co-culture. We traced this to altered granulopoiesis using single-cell multiomic mapping of circulating hematopoietic stem cells (HSCs) (29,366 cells, n=27). We show how these features are enriched in a subset of patients, resolving a specific poor outcome endotype (sepsis response signature SRS1). SRS1 patients have increased IL1R2+ immature neutrophils, epigenetic signatures of emergency granulopoiesis transcription factors in HSCs, and STAT3 features across infectious disease settings.  Our findings delineate an immunohematopoietic axis, therapeutic targets and stratified medicine approach to sepsis. Overall design: Cryopreserved PBMCs from sepsis patients and healthy volunteers were thawed, MACS enriched for CD34+ HSPCs, FACS sorted for CD34+CD45+ HSPCs then subjected to 10X multiome single-nucleus ATAC-seq and RNA-seq