Identification of an Early Unipotent Neutrophil Progenitor with Pro-Tumoral Activity in Mouse and Human Bone Marrow

Abstract

Neutrophils are short-lived immune cells that play important roles in a variety of diseases. The oligopotent Granulocyte Monocyte Progenitors (GMP) in the bone marrow give rise to monocytes and all granulocytes. Although several monocyte progenitors have been identified in mouse bone marrow, the unipotent neutrophil progenitors are still not well-defined. Here, we use Cytometry by Time-of-Flight (CyTOF) and Single-cell RNA-Sequencing (scRNA-Seq) methodologies to identify a committed unipotent early-stage neutrophil progenitor in adult mouse bone marrow. Importantly, we also discovered a similar unipotent, committed neutrophil progenitor (hNeP) that is present in healthy human bone marrow. Both mouse and human progenitors demonstrate unipotent neutrophil potency in vivo. Study of the identified mouse (NeP) and human (hNeP) neutrophil progenitors in cancer revealed that both NeP and hNeP significantly increased tumor growth when transferred into murine cancer models, including a humanized model. Further, we discovered that the hNeP was present in the blood of human patients recently diagnosed with melanoma, and could be readily identified by flow cytometry, suggesting that this human neutrophil progenitor could be used as a biomarker for early cancer discovery. The discovery of this early committed unipotent neutrophil progenitor in humans will allow for development of important new therapeutic targets for regulation of neutrophil levels and function in disease.