Background and Objectives. Homozygous b-thalassemia patients may develop iron overload even if untransfused, due to inappropriately high intestinal iron absorption. Reduction of hepcidin synthesis has been reported both in patients and in animal models. We have measured liver hepcidin and other iron gene transcripts in two different mouse models of b-thalassemia at different ages. Design and Methods. Mice Hbbth/th, characterized by spontaneous homozygous deletion of the major b1 globin gene were studied at 2 and 8 months. Mice Hbbth3/+, characterized by the heterozygous deletion of b1 and b2 globin genes were studied at 4 and 10 months. Hematologic data were obtained and iron overload estimated by Perls’ staining of the liver. Expression of liver hepcidin, Tfr2, Hjv, Fpn and Hfe RNA was assessed by real-time polymerase chain reaction. Levels of serum cytokines (interleukin-6, IL-1b, IL-10, granulocyte-macrophage colony-stimulating factor) levels were assayed by enzyme-linked immunosorbent assay. Results. Hemoglobin, hematocrit and mean corpuscolar volume were significantly reduced in both b-thalassemia models, more significantly in Hbbth3/+, which have the greater, age-dependent, iron overload. Hepcidin RNA was not increased despite iron overload in both strains. Fpn RNA was increased and Tfr2 was decreased in older animals. Inflammatory cytokine levels were striking variable and unrelated to hepcidin levels. Interpretation and Conclusions. Although anemia is reported to inhibit hepcidin expression, normal hepcidin synthesis was maintained in both thalassemic models studied. However, hepcidin levels were inappropriate for the body iron, especially in Hbbth3/+ 10- month-old animals. As we previously reported in wild type mice after parenteral iron overload, Tfr2 is reduced and Fpn RNA increased in thalassemic mice. Inflammatory cytokines did not play a major role in increasing hepcidin levels or in modifying iron homeostasis in this study
Liver expression of hepcidin and other iron genes in two mouse models of beta-thalassemia
DE FRANCESCHI, Lucia;
2006-01-01
Abstract
Background and Objectives. Homozygous b-thalassemia patients may develop iron overload even if untransfused, due to inappropriately high intestinal iron absorption. Reduction of hepcidin synthesis has been reported both in patients and in animal models. We have measured liver hepcidin and other iron gene transcripts in two different mouse models of b-thalassemia at different ages. Design and Methods. Mice Hbbth/th, characterized by spontaneous homozygous deletion of the major b1 globin gene were studied at 2 and 8 months. Mice Hbbth3/+, characterized by the heterozygous deletion of b1 and b2 globin genes were studied at 4 and 10 months. Hematologic data were obtained and iron overload estimated by Perls’ staining of the liver. Expression of liver hepcidin, Tfr2, Hjv, Fpn and Hfe RNA was assessed by real-time polymerase chain reaction. Levels of serum cytokines (interleukin-6, IL-1b, IL-10, granulocyte-macrophage colony-stimulating factor) levels were assayed by enzyme-linked immunosorbent assay. Results. Hemoglobin, hematocrit and mean corpuscolar volume were significantly reduced in both b-thalassemia models, more significantly in Hbbth3/+, which have the greater, age-dependent, iron overload. Hepcidin RNA was not increased despite iron overload in both strains. Fpn RNA was increased and Tfr2 was decreased in older animals. Inflammatory cytokine levels were striking variable and unrelated to hepcidin levels. Interpretation and Conclusions. Although anemia is reported to inhibit hepcidin expression, normal hepcidin synthesis was maintained in both thalassemic models studied. However, hepcidin levels were inappropriate for the body iron, especially in Hbbth3/+ 10- month-old animals. As we previously reported in wild type mice after parenteral iron overload, Tfr2 is reduced and Fpn RNA increased in thalassemic mice. Inflammatory cytokines did not play a major role in increasing hepcidin levels or in modifying iron homeostasis in this study
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