Project description:Extramedullary hematopoiesis (EMH) refers to the differentiation of hematopoietic stem cells (HSCs) into effector cells that occurs in compartments outside of the bone marrow. Previous studies linked pattern recognition receptor (PRR)-expressing HSCs, EMH and immune responses to microbial stimuli. However, the factors that regulate EMH and whether EMH operates in broader immune contexts remain unknown. Here, we demonstrate a previously unrecognized role for thymic stromal lymphopoietin (TSLP) in promoting the population expansion of progenitor cells in the periphery and identify that TSLP-elicited progenitors differentiate into effector cells including macrophages, dendritic cells and granulocytes that contribute to TH2 cytokine responses. The frequency of circulating progenitor cells was also increased in allergic patients with a gain-of-function polymorphism in TSLP, suggesting the TSLP-EMH pathway may operate in human disease. These data identify that TSLP-induced EMH contributes to the development of allergic inflammation and indicate that EMH is a conserved mechanism of innate immunity. In this study, we performed gene expression profiling to examine how the transcriptional signatures compared between TSLP-elcited GMP-like cells and naïve bone marrow-resident GMPs. Splenic TSLP-elicited GMP-like cells (CD3-, CD4-, CD5-, CD8-, CD19-, CD11b-, CD11c-, NK1.1-, FcεRI-, CD34+ c-kit+) were sort-purified from the spleen of C57BL/6 mice on day 5 post-TSLP-cDNA treatment. BM-resident GMPs (CD3-, CD4-, CD5-, CD8-, CD19-, CD11b-, CD11c-, NK1.1-, FcεRI-, Sca1- c-kit+ CD34+ CD16/32+) were sort-purified from mice that received a control-cDNA injection.
Project description:Extramedullary hematopoiesis (EMH) refers to the differentiation of hematopoietic stem cells (HSCs) into effector cells that occurs in compartments outside of the bone marrow. Previous studies linked pattern recognition receptor (PRR)-expressing HSCs, EMH and immune responses to microbial stimuli. However, the factors that regulate EMH and whether EMH operates in broader immune contexts remain unknown. Here, we demonstrate a previously unrecognized role for thymic stromal lymphopoietin (TSLP) in promoting the population expansion of progenitor cells in the periphery and identify that TSLP-elicited progenitors differentiate into effector cells including macrophages, dendritic cells and granulocytes that contribute to TH2 cytokine responses. The frequency of circulating progenitor cells was also increased in allergic patients with a gain-of-function polymorphism in TSLP, suggesting the TSLP-EMH pathway may operate in human disease. These data identify that TSLP-induced EMH contributes to the development of allergic inflammation and indicate that EMH is a conserved mechanism of innate immunity. In this study, we performed gene expression profiling to examine how the transcriptional signatures compared between TSLP-elcited GMP-like cells and naïve bone marrow-resident GMPs.
Project description:Granulocyte-monocyte progenitors (GMPs) and monocyte-dendritic cell progenitors (MDPs) produce monocytes during homeostasis and in response to increased demand during infection. Both progenitor populations are thought to derive from common myeloid progenitors (CMPs), and a hierarchical relationship (CMP-GMP-MDP-monocyte) is presumed to underlie monocyte differentiation. Here, however, we demonstrate that mouse MDPs arose from CMPs independently of GMPs, and that GMPs and MDPs produced monocytes via similar, but distinct, monocyte-committed progenitors. GMPs and MDPs yielded classical (Ly6Chi) monocytes with gene expression signatures that were defined by their origins and impacted their function. GMPs produced a subset of “neutrophil-like” monocytes, whereas MDPs gave rise to a subset of monocytes that yielded monocyte-derived dendritic cells. GMPs and MDPs were also independently mobilized to produce specific combinations of myeloid cell types following the injection of microbial components. Thus, the balance of GMP and MDP differentiation shapes the myeloid cell repertoire during homeostasis and following infection.
Project description:Granulocyte-monocyte progenitors (GMPs) and monocyte-dendritic cell progenitors (MDPs) produce monocytes during homeostasis and in response to increased demand during infection. Both progenitor populations are thought to derive from common myeloid progenitors (CMPs), and a hierarchical relationship (CMP-GMP-MDP-monocyte) is presumed to underlie monocyte differentiation. Here, however, we demonstrate that mouse MDPs arose from CMPs independently of GMPs, and that GMPs and MDPs produced monocytes via similar, but distinct, monocyte-committed progenitors. GMPs and MDPs yielded classical (Ly6Chi) monocytes with gene expression signatures that were defined by their origins and impacted their function. GMPs produced a subset of “neutrophil-like” monocytes, whereas MDPs gave rise to a subset of monocytes that yielded monocyte-derived dendritic cells. GMPs and MDPs were also independently mobilized to produce specific combinations of myeloid cell types following the injection of microbial components. Thus, the balance of GMP and MDP differentiation shapes the myeloid cell repertoire during homeostasis and following infection.
Project description:Examination of open chromatin regions between clonal neutrophil progenitor populations. Conditionally immortalized CD45.1 naive paired granulocyte-monocyte progenitors (GMPs) and their mature neutrophil counterpart were profiled in an in vitro cell system. We identified 29,966 differentially accessible regions (DARs) between GMPs and neutrophils, from a total of 74,009 consensus peaks of chromatin accessibility. There is some correlation of open chromatin between GMP and mature neutrophil clones.
Project description:Transcriptional profiling of clonal neutrophil progenitor populations. Conditionally immortalized CD45.1 naive paired granulocyte-monocyte progenitors (GMPs) and their mature neutrophil counterpart were profiled in an in vitro cell system. Clones demonstrated an overall similar transcriptional profile within the GMP or neutrophil states, however, individual clones had several differentially expressed genes (DEGs) between each other at both the progenitor and mature cell stages.
Project description:The pathways by which oncogenes, such as MLL-AF9, initiate transformation and leukemia in humans and mice are incompletely defined. In a study of target cells and oncogene dosage, we found that Mll-AF9, when under endogenous regulatory control, efficiently transformed LSK (Lin- Sca1+ c-kit+) stem cells while committed granulocyte-monocyte progenitors (GMPs) were transformation-resistant and did not cause leukemia. Mll-AF9 was expressed at higher levels in hematopoietic stem (HSC) than GMP cells. Mll- AF9 gene dosage effects were directly shown in experiments where GMPs were efficiently transformed by the high dosage of Mll-AF9 resulting from retroviral transduction. Mll-AF9 up-regulated expression of 196 genes in both LSK and progenitor cells, but to higher levels in LSKs than in committed myeloid progenitors. Experiment Overall Design: Comparison of gene expression profiles among four types of hematopoietic cells (GMP, CMP, CLP and HSC), FACS sorted from wild type and Mll-AF9 knock-in mice. The goal was to identify genes differentially expressed in each Mll-AF9 cell type compared to the corresponding wild type cells.
Project description:Granulocyte-monocyte progenitors (GMPs) have been previously defined for their potential to generate various myeloid progenies such as neutrophils and monocytes. Although studies have proposed lineage heterogeneity within GMPs, it is unclear if committed progenitors already exist among these progenitors and how they may behave differently during inflammation. By combining single-cell transcriptomic and proteomic analyses, we identified the early committed progenitor within the GMPs responsible for the strict production of neutrophils, which we designate as proNeu1. Our dissection of the GMP hierarchy led us to further identify a previously unknown intermediate proNeu2 population. Similar populations could be detected in human samples. proNeu1s, but not proNeu2s, selectively expanded during the early phase of sepsis at the expense of monocytes. Collectively, our findings help shape the neutrophil maturation trajectory roadmap and challenge the current definition of GMPs.
Project description:Granulocyte-monocyte progenitors (GMPs) have been previously defined for their potential to generate various myeloid progenies such as neutrophils and monocytes. Although studies have proposed lineage heterogeneity within GMPs, it is unclear if committed progenitors already exist among these progenitors and how they may behave differently during inflammation. By combining single-cell transcriptomic and proteomic analyses, we identified the early committed progenitor within the GMPs responsible for the strict production of neutrophils, which we designate as proNeu1. Our dissection of the GMP hierarchy led us to further identify a previously unknown intermediate proNeu2 population. Similar populations could be detected in human samples. proNeu1s, but not proNeu2s, selectively expanded during the early phase of sepsis at the expense of monocytes. Collectively, our findings help shape the neutrophil maturation trajectory roadmap and challenge the current definition of GMPs.