|MAES, KEN - Vrije University|
|NEMETH, ELIZABETA - University Of California|
|ROODMAN, DAVID - University Of Pittsburgh|
|HUSTON, ALISSA - University Of Pittsburgh|
|ESTEVE, FLAVIA - University Of Pittsburgh|
|FREYTES, CESAR - University Of Texas At San Antonio|
|CALLANDAR, NATALILE - University Of Wisconsin|
|KATODRITOU, EIRININ - Vrije University|
|Tussing Humphreys, Lisa|
|RIVERA, SETH - University Of California|
|VANDERKERKEN, KARIN - Vrije University|
|LICHTENSTEIN, ALAN - University Of California|
|GANZ, TOMAS - University Of California|
Submitted to: Blood
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2010
Publication Date: 11/4/2010
Citation: Maes, K., Nemeth, E., Roodman, D., Huston, A., Esteve, F., Freytes, C., Callandar, N., Katodritou, E., Tussing Humphreys, L.M., Rivera, S., Vanderkerken, K., Lichtenstein, A., Ganz, T. 2010. In anemia of multiple myeloma hepcidin is induced by increased bone-morphogenetic protein-2. Blood. 116(18):3635-3644.
Interpretive Summary: Hepcidin is a molecule in the body that controls iron status, and is the principal factor in the development of the anemia of inflammation. Patients with multiple myeloma (MM) frequently present with anemia. We showed that MM patients had increased serum hepcidin, which inversely correlated with hemoglobin, suggesting that hepcidin contributes to MM-related anemia. Searching for hepcidin-inducing inflammatory markers in MM, we focused on the inflammatory markers named BMPs and IL-6, the two major transcriptional regulators of hepcidin. Using blood-based serum from MM patients and normal individuals, we tested the ability of their sera to stimulate hepcidin using a novel test we developed, and also the amount of BMPs. Results showed MM sera activated hepcidin significantly more compared to normal sera, and MM sera contained significantly higher BMP-2 concentrations than normal sera. Our results demonstrate that BMP-2 is a major mediator of the hepcidin-stimulatory activity of MM patient sera.
Technical Abstract: Hepcidin is the principal iron-regulatory hormone and pathogenic factor in anemia of inflammation. Patients with multiple myeloma (MM) frequently present with anemia. We showed that MM patients had increased serum hepcidin, which inversely correlated with hemoglobin, suggesting that hepcidin contributes to MM-related anemia. Searching for hepcidin-inducing cytokines in MM, we focused on BMPs and IL-6, the major transcriptional regulators of hepcidin. We developed an in vitro reporter system consisting of JuH7 cells, and human hepcidin promoter-luciferase constructs to quantify hepcidin promoter activity in response to MM patient sera. The effects of IL-6 or BMPs were selectively disrupted by mutating the promoter at STAT3-binding site (STAT3-B@) or two BMP-responsive elements (BREs), respectively. MM patient sera activated the hepcidin promoter significantly more than normal sera. Mutations in BREs abrogated the activation dramatically, while mutations in STAT3-BS had only a minor effect. Co-treatment of MM sera with anti-BMP-2/-4 or noggin-Fc blocked the induction, whereas, anti-IL-6, anti-BMP -4, -6, or -9 antibodies did not. BMP-2 immunodepleted MM sera had decreased promoter-stimulatory capacity, and ELISA assay showed that MM sera contained significantly higher BMP-2 concentrations than normal sera. Our results demonstrate that BMP-2 is a major mediator of the hepcidin-stimulatory activity of MM patient sera.