Investigation of the role of interleukin-6 and hepcidin antimicrobial peptide in the development of anemia with age

Haematologica (Impact Factor: 5.81). 08/2013; 98(10). DOI: 10.3324/haematol.2013.087114
Source: PubMed


Anemia is common in older adults and associated with adverse health outcomes in epidemiologic studies. A thorough understanding of the complex pathophysiological mechanisms driving anemia in the elderly is lacking; but inflammation, iron restriction, and impaired erythroid maturation are thought to influence the phenotype. We hypothesized that interleukin-6 contributes to this anemia, given its pro-inflammatory activities, its ability to induce hepcidin antimicrobial peptide, and its negative impact on several tissues in older adults. We tested this hypothesis by comparing changes in indices of inflammation, iron metabolism and erythropoiesis in aged C57BL/6 mice to aged mice with targeted deletions of interleukin-6 or hepcidin antimicrobial peptide. Circulating neutrophil and monocyte numbers and inflammatory cytokines increased with age. Declines in hemoglobin concentration and red blood cell number indicated that C57BL/6, interleukin-6 knockout mice, and hepcidin antimicrobial peptide knockout mice all demonstrated impaired erythropoiesis by 24 months. However, the interleukin-6 knock out genotype and the hepcidin antimicrobial peptide knock out genotype resulted in improved erythropoiesis in aged mice. Increased erythropoietic activity in the spleen suggested that the erythroid compartment was stressed in aged C57BL/6 mice compared to aged interleukin-6 knockout mice. Our data suggest C57BL/6 mice are an appropriate mammalian model for the study of anemia with age. Furthermore, although interleukin-6 and hepcidin antimicrobial peptide are not required, they can participate in the development of anemia in aging mice, and could be targeted, pre-clinically, with existing interventions to determine the feasibility of such agents for the treatment of anemia in older adults.

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Available from: Alan Berger, Jul 14, 2014
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    • "Although the nature of the suppressive signal is still unknown, there is some evidence that, at least in conditions of stimulated erythropoiesis, it could be represented by a circulating factor produced by the erythroid progenitors in the bone marrow (Kautz et al., 2013). On the other hand, hepcidin is strongly induced by inflammation (Nemeth et al., 2003, 2004), in particular by the pro-inflammatory cytokine interleukin-6 (IL-6), and it is responsible for iron-limited erythropoiesis in patients with acute and chronic inflammatory states (Ganz, 2003; McCranor et al., 2013). Nevertheless, recent studies in mouse models (Gardenghi et al., 2014; Kim et al., 2014) have suggested that the iron-restricted anemia induced by inflammation likely recognizes a more complex pathogenesis, only partially dependent on hepcidin. "
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