Discovery of a Pro-Tumoral Clonogenic Unipotent Neutrophil Progenitor in Mouse and Human Bone Marrow

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, particularly in cancers, where neutrophils play a significant role. Overall design: Neutrophil progenitor isolated from mouse and human fresh bone marrow without treatment were sequeced to explore heterogeneities; 3'' Transcriptome sequencing (10X genomics)中性粒细胞（Neutrophils）是一类寿命较短的免疫细胞，在多种疾病中发挥关键作用。骨髓中的寡能粒细胞-单核细胞祖细胞（Granulocyte Monocyte Progenitors，GMP）可分化为单核细胞与所有粒细胞类群。尽管目前已在小鼠骨髓中鉴定出多种单核细胞祖细胞，但单能性中性粒细胞祖细胞的特征仍未被充分阐明。本研究借助飞行时间流式细胞术（Cytometry by Time-of-Flight，CyTOF）与单细胞RNA测序（Single-cell RNA-Sequencing，scRNA-Seq）技术，在成年小鼠骨髓中鉴定出一种定型的单能性早期中性粒细胞祖细胞。值得注意的是，本研究同时在健康人骨髓中发现了一类与之类似的单能性定型中性粒细胞祖细胞（hNeP）。小鼠与人类的该类祖细胞在体内均表现出仅分化为中性粒细胞的单能性潜能。针对已鉴定的小鼠中性粒细胞祖细胞（NeP）与人类hNeP在癌症中的功能研究显示，将二者移植入小鼠癌症模型（包括人源化模型）后，均可显著促进肿瘤生长。进一步研究发现，近期确诊为黑色素瘤的患者血液中存在hNeP，且该细胞可通过流式细胞术便捷鉴定，提示这类人类中性粒细胞祖细胞可作为癌症早期筛查的生物标志物。人类早期定型单能性中性粒细胞祖细胞的发现，将为调控疾病状态下中性粒细胞的数量与功能提供重要的新型治疗靶点，尤其在中性粒细胞发挥关键作用的癌症领域中极具应用价值。实验设计方案：从未经处理的小鼠与人类新鲜骨髓中分离中性粒细胞祖细胞并进行测序，以探究其异质性；采用3'端转录组测序（10X Genomics）技术。