Interferon-gamma mediates suppression of erythropoiesis but not reduced red cell survival following CpG-ODN administration in vivo.
OBJECTIVE
Cytokines released during inflammatory processes have been proposed to play a central role in mediating mechanism(s) leading to anemia. Here, we used CpG-ODN to investigate the effects of a pro-inflammatory response on the pathophysiological processes leading to anemia.


METHODS
Naïve and erythropoietin (EPO)-treated mice were injected for 2 days with 100 microg CpG-ODN or control ODN and the effects on the course of red blood cell (RBC) and reticulocyte counts, RBC turnover, and EPO-stimulated maturation of erythroid cells were analyzed. To study the effect of CpG-ODN on erythroid cell maturation in vitro, we obtained primary EPO-responsive cells by treating mice with thiamphenicol (15 mg/g body weight).


RESULTS
CpG-ODN-treated mice developed anemia, which persisted for 5 days and was associated with a 50% reduction in EPO-stimulated differentiation of EPOR+ cells to TER119+ erythroblasts. CpG-ODN-induced suppression required accessory cells, including antigen presenting cells, which activated other cells to produce pro-inflammatory cytokines. In vitro neutralization of IFN-gamma, but not IL-12, TNF-alpha, IFN-alpha, IL-1alpha, or IL-1beta, abrogated the erythropoietic suppression induced by CpG-ODN. The anemia observed in CpG-ODN-treated mice was also associated with reduced RBC survival in vivo, as demonstrated by a sevenfold to eightfold higher turnover of biotinylated RBC compared to control ODN-treated mice. In vivo IFN-gamma neutralization confirmed that IFN-gamma contributed to erythropoietic suppression but not reduced RBC survival.


CONCLUSIONS
Together, these results demonstrate that CpG-ODN anemia is associated with suppressed erythropoiesis and decreased RBC survival. Importantly, CpG-ODN-induced IFN-gamma was found to be the major factor mediating erythropoietic suppression but not decreased RBC survival.
Thawani
Neeta
N
Centre for the Study of Host Resistance, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada.
Tam
Mifong
M
Chang
Kai-Hsin
KH
Stevenson
Mary M
MM
D000740:Anemia / Q000139:chemically induced; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004912:Erythrocytes / Q000187:drug effects*; D004920:Erythropoiesis / Q000187:drug effects*; D004921:Erythropoietin / Q000008:administration & dosage / Q000037:antagonists & inhibitors; D005260:Female; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D007279:Injections, Subcutaneous; D007371:Interferon-gamma / Q000096:biosynthesis / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009838:Oligodeoxyribonucleotides / Q000008:administration & dosage*; D011994:Recombinant Proteins; D045262:Reticulocytosis / Q000187:drug effects; D013154:Spleen / Q000187:drug effects; D013839:Thiamphenicol / Q000008:administration & dosage
C408982:CPG-oligonucleotide; D009838:Oligodeoxyribonucleotides; D011994:Recombinant Proteins; D004921:Erythropoietin; D007371:Interferon-gamma; D013839:Thiamphenicol