Dexamethasone targeted directly to macrophages induces macrophage niches that promote erythroid expansion
Mario Falchi,
Lilian Varricchio,
Fabrizio Martelli,
Francesca Masiello,
Giulia Federici,
Maria Zingariello,
Gabriella Girelli,
Carolyn Whitsett,
Emanuel F. Petricoin,
Søren Kragh Moestrup,
Ann Zeuner,
Anna Rita Migliaccio
Affiliations
Mario Falchi
National AIDS Center, New York, NY, USA;Tisch Cancer Institute, Mount Sinai School of Medicine, New York, NY, USA
Lilian Varricchio
Tisch Cancer Institute, Mount Sinai School of Medicine, New York, NY, USA
Fabrizio Martelli
Tisch Cancer Institute, Mount Sinai School of Medicine, New York, NY, USA;Hematology/Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
Francesca Masiello
Hematology/Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
Giulia Federici
Regina Elena National Cancer Institute, Rome, Italy;Hematology/Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
Maria Zingariello
Medicine, Campus Biomedicus, Università La Sapienza, Rome, Italy
Gabriella Girelli
Transfusion Center, Università La Sapienza, Rome, Italy
Carolyn Whitsett
Kings County Hospital and Downstate Medical Center, Brooklyn, NY, USA
Emanuel F. Petricoin
Center for Applied Proteomics and Molecular Medicine, George Mason University, Manassas, VA, USA
Søren Kragh Moestrup
Department of Biomedicine, University of Aarhus, Aarhus C, Denmark;Institute of Molecular Medicine, University of Souther Denmark, Denmark
Ann Zeuner
Hematology/Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
Anna Rita Migliaccio
Tisch Cancer Institute, Mount Sinai School of Medicine, New York, NY, USA;Hematology/Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
Cultures of human CD34pos cells stimulated with erythroid growth factors plus dexamethasone, a model for stress erythropoiesis, generate numerous erythroid cells plus a few macrophages (approx. 3%; 3:1 positive and negative for CD169). Interactions occurring between erythroblasts and macrophages in these cultures and the biological effects associated with these interactions were documented by live phase-contrast videomicroscopy. Macrophages expressed high motility interacting with hundreds/thousands of erythroblasts per hour. CD169pos macrophages established multiple rapid ‘loose’ interactions with proerythroblasts leading to formation of transient erythroblastic island-like structures. By contrast, CD169neg macrophages established ‘tight’ interactions with mature erythroblasts and phagocytosed these cells. ‘Loose’ interactions of CD169pos macrophages were associated with proerythroblast cytokinesis (the M phase of the cell cycle) suggesting that these interactions may promote proerythroblast duplication. This hypothesis was tested by experiments that showed that as few as 103 macrophages significantly increased levels of 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide incorporation frequency in S/G2/M and cytokinesis expressed by proerythroblasts over 24 h of culture. These effects were observed also when macrophages were co-cultured with dexamethasone directly conjugated to a macrophage-specific CD163 antibody. In conclusion, in addition to promoting proerythroblast proliferation directly, dexamethasone stimulates expansion of these cells indirectly by stimulating maturation and cytokinesis supporting activity of macrophages.
