scholarly journals Interleukin-6 and the Granulocyte Colony-Stimulating Factor Receptor Are Major Independent Regulators of Granulopoiesis In Vivo But Are Not Required for Lineage Commitment or Terminal Differentiation

Blood ◽  
1997 ◽  
Vol 90 (7) ◽  
pp. 2583-2590 ◽  
Author(s):  
Fulu Liu ◽  
Jennifer Poursine-Laurent ◽  
Huai Yang Wu ◽  
Daniel C. Link

Abstract Multiple hematopoietic cytokines can stimulate granulopoiesis; however, their relative importance in vivo and mechanisms of action remain unclear. We recently reported that granulocyte colony-stimulating factor receptor (G-CSFR)-deficient mice have a severe quantitative defect in granulopoiesis despite which phenotypically normal neutrophils were still detected. These results confirmed a role for the G-CSFR as a major regulator of granulopoiesis in vivo, but also indicated that G-CSFR independent mechanisms of granulopoiesis must exist. To explore the role of interleukin-6 (IL-6) in granulopoiesis, we generated IL-6 × G-CSFR doubly deficient mice. The additional loss of IL-6 significantly worsened the neutropenia present in young adult G-CSFR–deficient mice; moreover, exogenous IL-6 stimulated granulopoiesis in vivo in the absence of G-CSFR signals. Near normal numbers of myeloid progenitors were detected in the bone marrow of IL-6 × G-CSFR–deficient mice and their ability to terminally differentiate into mature neutrophils was observed. These results indicate that IL-6 is an independent regulator of granulopoiesis in vivo and show that neither G-CSFR or IL-6 signals are required for the commitment of multipotential progenitors to the myeloid lineage or for their terminal differentiation.

Blood ◽  
1997 ◽  
Vol 90 (7) ◽  
pp. 2583-2590 ◽  
Author(s):  
Fulu Liu ◽  
Jennifer Poursine-Laurent ◽  
Huai Yang Wu ◽  
Daniel C. Link

Multiple hematopoietic cytokines can stimulate granulopoiesis; however, their relative importance in vivo and mechanisms of action remain unclear. We recently reported that granulocyte colony-stimulating factor receptor (G-CSFR)-deficient mice have a severe quantitative defect in granulopoiesis despite which phenotypically normal neutrophils were still detected. These results confirmed a role for the G-CSFR as a major regulator of granulopoiesis in vivo, but also indicated that G-CSFR independent mechanisms of granulopoiesis must exist. To explore the role of interleukin-6 (IL-6) in granulopoiesis, we generated IL-6 × G-CSFR doubly deficient mice. The additional loss of IL-6 significantly worsened the neutropenia present in young adult G-CSFR–deficient mice; moreover, exogenous IL-6 stimulated granulopoiesis in vivo in the absence of G-CSFR signals. Near normal numbers of myeloid progenitors were detected in the bone marrow of IL-6 × G-CSFR–deficient mice and their ability to terminally differentiate into mature neutrophils was observed. These results indicate that IL-6 is an independent regulator of granulopoiesis in vivo and show that neither G-CSFR or IL-6 signals are required for the commitment of multipotential progenitors to the myeloid lineage or for their terminal differentiation.


1998 ◽  
Vol 188 (6) ◽  
pp. 1173-1184 ◽  
Author(s):  
Pu Zhang ◽  
Atsushi Iwama ◽  
Milton W. Datta ◽  
Gretchen J. Darlington ◽  
Daniel C. Link ◽  
...  

Cytokines stimulate granulopoiesis through signaling via receptors whose expression is controlled by lineage-specific transcription factors. Previously, we demonstrated that granulocyte colony-stimulating factor (G-CSF) receptor mRNA was undetectable and granulocyte maturation blocked in CCAAT enhancer binding protein α (C/EBPα)-deficient mice. This phenotype is distinct from that of G-CSF receptor−/− mice, suggesting that other genes are likely to be adversely affected by loss of C/EBPα. Here we demonstrate loss of interleukin 6 (IL-6) receptor and IL-6–responsive colony-forming units (CFU-IL6) in C/EBPα−/− mice. The observed failure of granulopoiesis could be rescued by the addition of soluble IL-6 receptor and IL-6 or by retroviral transduction of G-CSF receptors, demonstrating that loss of both of these receptors contributes to the absolute block in granulocyte maturation observed in C/EBPα-deficient hematopoietic cells. The results of these and other studies suggest that additional C/EBPα target genes, possibly other cytokine receptors, are also important for the block in granulocyte differentiation observed in vivo in C/EBPα-deficient mice.


Blood ◽  
1994 ◽  
Vol 84 (6) ◽  
pp. 1737-1746 ◽  
Author(s):  
GJ Lieschke ◽  
D Grail ◽  
G Hodgson ◽  
D Metcalf ◽  
E Stanley ◽  
...  

Mice lacking granulocyte colony-stimulating factor (G-CSF) were generated by targeted disruption of the G-CSF gene in embryonal stem cells. G-CSF-deficient mice (genotype G-CSF-/-) are viable, fertile, and superficially healthy, but have a chronic neutropenia. Peripheral blood neutrophil levels were 20% to 30% of wild-type mice (genotype G- CSF+/+) and mice heterozygous for the null mutation had intermediate neutrophil levels, suggesting a gene-dosage effect. In the marrow of G- CSF-/- mice, granulopoietic precursor cells were reduced by 50% and there were reduced levels of granulocyte, macrophage, and blast progenitor cells. Despite G-CSF deficiency, mature neutrophils were still present in the blood and marrow, indicating that other factors can support neutrophil production in vivo. G-CSF-/- mice had reduced numbers of neutrophils available for rapid mobilization into the circulation by a single dose of G-CSF. G-CSF administration reversed the granulopoietic defect of G-CSF-/- mice. One day of G-CSF administration to G-CSF-/- mice elevated circulating neutrophil levels to normal, and after 4 days of G-CSF administration, G-CSF+/+ and G-CSF- /- marrows were morphologically indistinguishable. G-CSF-/- mice had a markedly impaired ability to control infection with Listeria monocytogenes, with diminished neutrophil and delayed monocyte increases in the blood and reduced infection-driven granulopoiesis. Collectively, these observations indicate that G-CSF is indispensible for maintaining the normal quantitative balance of neutrophil production during “steady-state” granulopoiesis in vivo and also implicate G-CSF in “emergency” granulopoiesis during infections.


Blood ◽  
1999 ◽  
Vol 94 (2) ◽  
pp. 560-571 ◽  
Author(s):  
Xinping Wang ◽  
Edward Scott ◽  
Charles L. Sawyers ◽  
Alan D. Friedman

Within hematopoiesis, C/EBP is expressed only in myeloid cells, and PU.1 is expressed mainly in myeloid and B-lymphoid cells. C/EBP-deficient mice lack the neutrophil lineage and retain monocytes, whereas PU.1-deficient mice lack monocytes and have severely reduced neutrophils. We expressed a C/EBP-estrogen receptor ligand-binding domain fusion protein, C/EBPWT-ER, in 32D cl3 myeloblasts. 32D cl3 cells proliferate in interleukin-3 (IL-3) and differentiate to neutrophils in granulocyte colony-stimulating factor (G-CSF). In the presence of estradiol, C/EBPWT-ER induced morphologic differentiation and the expression of the myeloperoxidase, lactoferrin, and G-CSF receptor mRNAs. C/EBPWT-ER also induced a G1/S cell cycle block, with induction of p27 and Rb hypophosphorylation. bcr-ablp210 prevented 32D cl3 cell differentiation. Activation of C/EBP-ER in 32D-bcr-ablp210 or Ba/F3 B-lymphoid cells induced cell cycle arrest independent of terminal differentiation. C/EBPWT-ER induced endogenous PU.1 mRNA within 8 hours in both 32D cl3 and Ba/F3 cells, even in the presence of cycloheximide, indicating that C/EBP directly activates the PU.1 gene. However, activation of a PU.1-ER fusion protein in 32D cl3 cells induced myeloperoxidase (MPO) RNA but not terminal differentiation. Thus, C/EBP acts downstream of G-CSF and upstream of PU.1, p27, and potentially other factors to induce myeloblasts to undergo granulocytic differentiation and cell cycle arrest.


Blood ◽  
1994 ◽  
Vol 84 (6) ◽  
pp. 1737-1746 ◽  
Author(s):  
GJ Lieschke ◽  
D Grail ◽  
G Hodgson ◽  
D Metcalf ◽  
E Stanley ◽  
...  

Abstract Mice lacking granulocyte colony-stimulating factor (G-CSF) were generated by targeted disruption of the G-CSF gene in embryonal stem cells. G-CSF-deficient mice (genotype G-CSF-/-) are viable, fertile, and superficially healthy, but have a chronic neutropenia. Peripheral blood neutrophil levels were 20% to 30% of wild-type mice (genotype G- CSF+/+) and mice heterozygous for the null mutation had intermediate neutrophil levels, suggesting a gene-dosage effect. In the marrow of G- CSF-/- mice, granulopoietic precursor cells were reduced by 50% and there were reduced levels of granulocyte, macrophage, and blast progenitor cells. Despite G-CSF deficiency, mature neutrophils were still present in the blood and marrow, indicating that other factors can support neutrophil production in vivo. G-CSF-/- mice had reduced numbers of neutrophils available for rapid mobilization into the circulation by a single dose of G-CSF. G-CSF administration reversed the granulopoietic defect of G-CSF-/- mice. One day of G-CSF administration to G-CSF-/- mice elevated circulating neutrophil levels to normal, and after 4 days of G-CSF administration, G-CSF+/+ and G-CSF- /- marrows were morphologically indistinguishable. G-CSF-/- mice had a markedly impaired ability to control infection with Listeria monocytogenes, with diminished neutrophil and delayed monocyte increases in the blood and reduced infection-driven granulopoiesis. Collectively, these observations indicate that G-CSF is indispensible for maintaining the normal quantitative balance of neutrophil production during “steady-state” granulopoiesis in vivo and also implicate G-CSF in “emergency” granulopoiesis during infections.


Blood ◽  
1997 ◽  
Vol 90 (8) ◽  
pp. 3037-3049 ◽  
Author(s):  
John F. Seymour ◽  
Graham J. Lieschke ◽  
Dianne Grail ◽  
Cathy Quilici ◽  
George Hodgson ◽  
...  

Abstract Mice lacking granulocyte colony-stimulating factor (G-CSF) are neutropenic with reduced hematopoietic progenitors in the bone marrow and spleen, whereas those lacking granulocyte-macrophage colony-stimulating factor (GM-CSF) have impaired pulmonary homeostasis and increased splenic hematopoietic progenitors, but unimpaired steady-state hematopoiesis. These contrasting phenotypes establish unique roles for these factors in vivo, but do not exclude the existence of additional redundant functions. To investigate this issue, we generated animals lacking both G-CSF and GM-CSF. In the process of characterizing the phenotype of these animals, we further analyzed G-CSF– and GM-CSF–deficient mice, expanding the recognized spectrum of defects in both. G-CSF–deficient animals have a marked predisposition to spontaneous infections, a reduced long-term survival, and a high incidence of reactive type AA amyloidosis. GM-CSF–deficient mice have a modest impairment of reproductive capacity, a propensity to develop lung and soft-tissue infections, and a similarly reduced survival as in G-CSF–deficient animals. The phenotype of mice lacking both G-CSF and GM-CSF was additive to the features of the constituent genotypes, with three novel additional features: a greater degree of neutropenia among newborn mice than in those lacking G-CSF alone, an increased neonatal mortality rate, and a dominant influence of the lack of G-CSF on splenic hematopoiesis resulting in significantly reduced numbers of splenic progenitors. In contrast to newborn animals, adult mice lacking both G-CSF and GM-CSF exhibited similar neutrophil levels as G-CSF–deficient animals. These findings demonstrate that the additional lack of GM-CSF in G-CSF–deficient animals further impairs steady-state granulopoiesis in vivo selectively during the early postnatal period, expand the recognized roles of both G-CSF and GM-CSF in vivo, and emphasize the utility of studying multiply deficient mouse strains in the investigation of functional redundancy.


Blood ◽  
1998 ◽  
Vol 91 (6) ◽  
pp. 2099-2107
Author(s):  
Solveig G. Ericson ◽  
Yue Zhao ◽  
Huilan Gao ◽  
Kathryn L. Miller ◽  
Laura F. Gibson ◽  
...  

Polymorphonuclear neutrophils (PMNs) are essential effector cells in host defense and tissue inflammatory responses. These responses may be initiated after cross-linking of cell surface Fc receptors that bind the constant portion of IgG (FcγR). We evaluated the effect of cross-linking FcγRI or FcγRII on interleukin-6 (IL-6) production by purified PMNs from normal donors or from patients being treated with recombinant human granulocyte colony-stimulating factor (rhG-CSF). In PMNs from normal donors, IL-6 mRNA was detected by reverse transcriptase-polymerase chain reaction only after FcγRI or FcγRII cross-linking. We also found that IL-6 mRNA could be detected in PMNs after either in vitro or in vivo rhG-CSF treatment in the absence of FcγR cross-linking. IL-6 protein was found to be produced intracellularly and secreted by PMNs after cross-linking FcγRI or FcγRII or after rhG-CSF stimulation. Cross-linking FcγRI or FcγRII on PMNs from patients treated with rhG-CSF resulted in a synergistic increase in IL-6 secretion. Upregulation of IL-6 production by PMNs after rhG-CSF treatment may contribute to a clinical engraftment syndrome that occurs during periods of rapid increase in PMN numbers in patients receiving rhG-CSF.


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