title: Interleukin-6 directly impairs the erythroid development of human TF-1 erythroleukemic cells.
abstract: Anemia of inflammation or chronic disease is a highly prevalent form of anemia. The inflammatory cytokine interleukin-6 (IL-6) negatively correlates with hemoglobin concentration in many disease states. The IL-6-hepcidin antimicrobial peptide axis promotes iron-restricted anemia; however the full role of IL-6 in anemia of inflammation is not well-defined. We previously reported that chronic inflammation had a negative impact on maturation of erythroid progenitors in a mouse model. We hypothesized that IL-6 may be responsible for impaired erythropoiesis, independent of iron restriction. To test the hypothesis we utilized the human erythroleukemia TF-1 cell line to model erythroid maturation and exposed them to varying doses of IL-6 over six days. At 10 ng/ml, IL-6 significantly repressed erythropoietin-dependent TF-1 erythroid maturation. While IL-6 did not decrease the expression of genes associated with hemoglobin synthesis, we observed impaired hemoglobin synthesis as demonstrated by decreased benzidine staining. We also observed that IL-6 down regulated expression of the gene SLC4a1 which is expressed late in erythropoiesis. Those findings suggested that IL-6-dependent inhibition of hemoglobin synthesis might occur. We investigated the impact of IL-6 on mitochondria. IL-6 decreased the mitochondrial membrane potential at all treatment doses, and significantly decreased mitochondrial mass at the highest dose. Our studies indicate that IL-6 may impair mitochondrial function in maturing erythroid cells resulting in impaired hemoglobin production and erythroid maturation. Our findings may indicate a novel pathway of action for IL-6 in the anemia of inflammation, and draw attention to the potential for new therapeutic targets that affect late erythroid development.
authors.affiliation: Division of Geriatric Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: McCranor
authors.affiliation: Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Division of Geriatric Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Cruz
authors.affiliation: Division of Geriatric Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
authors.forename: Qian-Li
authors.initials: QL
authors.lastname: Xue
authors.affiliation: Lowe Family Genomics Core, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
authors.forename: Alan E
authors.initials: AE
authors.lastname: Berger
authors.affiliation: Division of Geriatric Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA.
authors.forename: Jeremy D
authors.initials: JD
authors.lastname: Walston
authors.affiliation: Center for Stem Cell Biology & Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Pediatrics, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Curt I
authors.initials: CI
authors.lastname: Civin
authors.affiliation: Division of Geriatric Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA; Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA. Electronic address: croy6@jhmi.edu.
authors.forename: Cindy N
authors.initials: CN
authors.lastname: Roy
mesh_terms: D000954:Antigens, Surface / Q000378:metabolism; D045744:Cell Line, Tumor; D004920:Erythropoiesis / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D016130:Immunophenotyping; D015850:Interleukin-6 / Q000494:pharmacology*; D004915:Leukemia, Erythroblastic, Acute / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D015850:Interleukin-6; D017382:Reactive Oxygen Species
keywords: AICD; ALAS2; Anemia; Band 3; CM-H(2)DCFDA; Cytokine; Epo; Erythropoiesis; GM-CSF; GYPA; HBB; Hemoglobin; IFN; IL-6; Inflammation; Mitochondria; SCF; SFEM; SLC4a1; TMRM; TNF; aminolevulinate synthase 2; anemia of inflammation or chronic disease; chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate, acetyl ester; erythropoietin/Epoetin Alfa; glycophorin A; granulocyte-macrophage colony-stimulating factor; hemoglobin beta; interferon; interleukin-6; serum free expansion medium; stem cell factor; tetramethylrhodamine methyl ester perchlorate; tumor necrosis factor