Combined corticosteroid/granulocyte colony-stimulating factor (G-CSF) therapy in the treatment of severe congenital neutropenia unresponsive to G-CSF: Activated glucocorticoid receptors synergize with G-CSF signals.
More than 90% of patients with severe congenital neutropenia (SCN) respond to granulocyte colony-stimulating factor (G-CSF) therapy. The basis for the refractory state in the remaining patients is unknown. To address this issue, we studied a child with SCN who was totally unresponsive to G-CSF and had a novel point mutation in the extracellular domain of the G-CSF receptor (GCSF-R). Marrow stromal support of granulopoiesis was evaluated by plating CD34(+) cells on preformed stromal layers. Nonadherent cells were harvested and assayed in clonogenic assays for granulocytic colony production. The in vitro effect of G-CSF and corticosteroids on granulopoiesis was evaluated in clonogenic assays of marrow mononuclear cells, by proliferation studies of the murine myeloid cell line 32D expressing the patient's mutated G-CSFR, and by measuring STAT5 activation in nuclear extracts from stimulated cells.Patient's stroma supported granulopoiesis derived from control marrow CD34(+) cells in a normal manner. Normal stroma, however, failed to induce granulopoiesis from patient's CD34(+) cells. Clonogenic assays of the patient's marrow mononuclear cells incorporating either G-CSF or hydrocortisone produced little neutrophil growth. In contrast, inclusion of both G-CSF and hydrocortisone in the cytokine "cocktail" markedly increased the neutrophil numbers. Proliferation of 32D cells expressing the mutated receptor and STAT5 activation were improved by a combination of G-CSF and dexamethasone. When small daily doses of oral prednisone were then administered to the patient with conventional doses of subcutaneous G-CSF, the patient responded with increased neutrophil numbers and with a complete reversal of the infectious problems. These data provide insight into SCN unresponsive to standard G-CSF treatment and to the potential corrective action of combined treatment with G-CSF and corticosteroids through synergistic activation of STAT5.
Dror
Y
Y
Department of Pediatrics, Division of Hematology and Oncology and Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Ward
A C
AC
Touw
I P
IP
Freedman
M H
MH
D000305:Adrenal Cortex Hormones / Q000008:administration & dosage / Q000627:therapeutic use*; D018952:Antigens, CD34 / Q000032:analysis; D017209:Apoptosis; D001854:Bone Marrow Cells / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D003907:Dexamethasone / Q000008:administration & dosage / Q000627:therapeutic use; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage / Q000627:therapeutic use; D016179:Granulocyte Colony-Stimulating Factor / Q000008:administration & dosage / Q000627:therapeutic use*; D006410:Hematopoiesis; D006801:Humans; D006854:Hydrocortisone / Q000494:pharmacology; D007231:Infant, Newborn; D008894:Milk Proteins; D009503:Neutropenia / Q000188:drug therapy* / Q000235:genetics*; D009504:Neutrophils / Q000473:pathology; D017354:Point Mutation; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000235:genetics*; D050799:STAT5 Transcription Factor; D017154:Stromal Cells / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism
D000305:Adrenal Cortex Hormones; D018952:Antigens, CD34; D004268:DNA-Binding Proteins; D005938:Glucocorticoids; D008894:Milk Proteins; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D016179:Granulocyte Colony-Stimulating Factor; D003907:Dexamethasone; D006854:Hydrocortisone