Project description:Severe congenital neutropenia (SCN) is a rare disorder characterized by a maturation arrest of myeloid progenitor cells in the bone marrow and severe reduction in the amount of circulating neutrophils. Loss-of-function mutations in the CSF3R (the gene encoding the granulocyte colony-stimulating factor (G-CSF) receptor) have been reported in a handful of cases. We describe two novel pedigrees with moderate neutropenia. G-CSFR immunostaining was greatly reduced on patient neutrophils. G-CSF did not prolong neutrophil survival or enhanced reactive oxygen species generation, and STAT-3 phosphorylation was absent, while neutrophils did respond to granulocyte-macrophage colony-stimulating factor (GM-CSF). Despite a lack of G-CSF signaling, morphology and cellular proteomics were normal. We suggest the major role of G-CSF is not in myeloid differentiation, but in generation of sufficient number of committed progenitor cells for neutrophil release and their survival during inflammation, which corresponds with G-CSFR expression in myeloid cell fractions from bone marrow of healthy individuals.
Project description:Adult hematopoietic stem cells (HSCs) reside primarily in bone marrow. However, hematopoietic stresses such as myelofibrosis, anemia, pregnancy, infection or myeloablation can mobilize HSCs to the spleen and induce extramedullary hematopoiesis (EMH). While the bone marrow HSC niche has been studied intensively, the EMH niche has received little attention. Here, we systematically assessed the physiological sources of the key niche factors, SCF and CXCL12, in the mouse spleen after EMH induction by cyclophosphamide plus granulocyte colony-stimulating factor, blood loss, or pregnancy. In each case, Scf was expressed by endothelial cells and Tcf21+ stromal cells, primarily around sinusoids in red pulp, while Cxcl12 was expressed by a subset of Tcf21+ stromal cells. EMH induction markedly expanded the Scf-expressing endothelial cells and stromal cells by inducing proliferation. Most splenic HSCs were adjacent to Tcf21+ stromal cells in red pulp. Conditional deletion of Scf from spleen endothelial cells or Scf or Cxcl12 from Tcf21+ stromal cells severely reduced spleen EMH and reduced blood cell counts without affecting bone marrow hematopoiesis. Endothelial cells and Tcf21+ stromal cells thus create the splenic EMH niche, which is necessary for the physiological response to diverse hematopoietic stresses. Unfractionated spleen cells (2 replicates) and FACS-sorted VE-cadherein negative Scf-GFP positive cells (3 replicates)
Project description:Highly purified Hematopoietic stem cells (HSC) from mouse bone marrow (BM) were compared to HSC after two days of cytoxan/GCSF treatment (Cyclophosphamide/granulocyte colony-stimulating factor) (Day2Mob) and leukemic HSC from mice lacking JunB. See Forsberg et. al. 2010 for details. CML - chronic myelogenous leukemia. Biological Replicate
Project description:Highly purified Hematopoietic stem cells (HSC) from mouse bone marrow (BM) were compared to HSC after two days of cytoxan/GCSF treatment (Cyclophosphamide/granulocyte colony-stimulating factor) (Day2Mob) and leukemic HSC from mice lacking JunB. See Forsberg et. al. 2010 for details. CML - chronic myelogenous leukemia.
Project description:Adult hematopoietic stem cells (HSCs) reside primarily in bone marrow. However, hematopoietic stresses such as myelofibrosis, anemia, pregnancy, infection or myeloablation can mobilize HSCs to the spleen and induce extramedullary hematopoiesis (EMH). While the bone marrow HSC niche has been studied intensively, the EMH niche has received little attention. Here, we systematically assessed the physiological sources of the key niche factors, SCF and CXCL12, in the mouse spleen after EMH induction by cyclophosphamide plus granulocyte colony-stimulating factor, blood loss, or pregnancy. In each case, Scf was expressed by endothelial cells and Tcf21+ stromal cells, primarily around sinusoids in red pulp, while Cxcl12 was expressed by a subset of Tcf21+ stromal cells. EMH induction markedly expanded the Scf-expressing endothelial cells and stromal cells by inducing proliferation. Most splenic HSCs were adjacent to Tcf21+ stromal cells in red pulp. Conditional deletion of Scf from spleen endothelial cells or Scf or Cxcl12 from Tcf21+ stromal cells severely reduced spleen EMH and reduced blood cell counts without affecting bone marrow hematopoiesis. Endothelial cells and Tcf21+ stromal cells thus create the splenic EMH niche, which is necessary for the physiological response to diverse hematopoietic stresses.
Project description:Neutrophil homeostasis is maintained, in part, by the regulated release of neutrophils from the bone marrow. Constitutive expression of the chemokine CXCL12 by bone marrow stromal cells provides a key retention signal for neutrophils in the bone marrow through activation of its receptor CXCR4. Herein, we show that the ELR chemokines CXCL1 and CXCL2 are constitutively expressed by bone marrow endothelial cells and osteoblasts, and CXCL2 expression is induced in endothelial cells during granulocyte colony-stimulating factor (G-CSF)-induced neutrophil mobilization. Neutrophils lacking CXCR2, the receptor for CXCL1 and CXCL2, are preferentially retained in the bone marrow, reproducing a myelokathexis phenotype. Transient disruption of CXCR4 failed to mobilize CXCR2 neutrophils. However, doubly deficient neutrophils (CXCR2-/- CXCR4-/-) displayed constitutive mobilization, showing that CXCR4 plays a dominant role. Collectively, these data suggest that CXCR2 signaling is a second chemokine axis that interacts antagonistically with CXCR4 to regulate neutrophil release from the bone marrow. We used gene expression microarrays to determine the changes in osteoblasts and bone marrow endothelial cells after G-CSF treatment. 3 untreated and G-CSF-treated osteoblast samples and 4 untreated and G-CSF-treated endothelial samples.
Project description:Neutrophil homeostasis is maintained, in part, by the regulated release of neutrophils from the bone marrow. Constitutive expression of the chemokine CXCL12 by bone marrow stromal cells provides a key retention signal for neutrophils in the bone marrow through activation of its receptor CXCR4. Herein, we show that the ELR chemokines CXCL1 and CXCL2 are constitutively expressed by bone marrow endothelial cells and osteoblasts, and CXCL2 expression is induced in endothelial cells during granulocyte colony-stimulating factor (G-CSF)-induced neutrophil mobilization. Neutrophils lacking CXCR2, the receptor for CXCL1 and CXCL2, are preferentially retained in the bone marrow, reproducing a myelokathexis phenotype. Transient disruption of CXCR4 failed to mobilize CXCR2 neutrophils. However, doubly deficient neutrophils (CXCR2-/- CXCR4-/-) displayed constitutive mobilization, showing that CXCR4 plays a dominant role. Collectively, these data suggest that CXCR2 signaling is a second chemokine axis that interacts antagonistically with CXCR4 to regulate neutrophil release from the bone marrow. We used gene expression microarrays to determine the changes in osteoblasts and bone marrow endothelial cells after G-CSF treatment.
Project description:BM monocytes were treated with 20ug/ml of M-CSF (macrophage colony stimulating factor) or GM-CSF (granulocyte monocyte colony stimulating factor) for 0, 6, 12 hours before harvesting RNA for analysis