Mycobacteria-induced anaemia: a molecular approach reveals the involvement of NRAMP1 and lipocalin-2 but not hepcidin
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ABSTRACT: Anaemia is a frequent complication of chronic infectious diseases but the exact mechanisms by which it develops remain to be clarified. In the present work, we used a mouse model of mycobacterial infection to study molecular alterations of iron metabolism. We show that four weeks after infection with Mycobacterium avium BALB/c mice exhibit a moderate anaemia, which cannot be explained by elevated hepatic hepcidin mRNA expression. Instead, the mice respond with increased mRNA expression of ferroportin (Slc40a1), ceruloplasmin (Cp), hemopexin (Hpx), heme-oxygenase-1 (Hmox1) and lipocalin-2 (Lcn2). Both the anemia and the mRNA expression changes of iron-related genes are largely absent in C.D2 mice which bear a functional allele of the Nramp1 gene. These data suggest that anaemia due to a chronic infection with M. avium develops independently of elevated hepcidin expression and possibly involves ferroportin and/or lipocalin-2. A pool of five mice total RNAs for each condition was used in the experiments. Each two channel chip experiment was done in duplicates with swapped dyes.
Project description:We determined duodenal and liver gene response patterns in mice with primary (Hfe ?/? and C282Y homozygous mice) and secondary iron overload versus 129S6/SvEvTac wild type controls.
Project description:Hereditary hemochromatosis and transfusional iron overload are frequent clinical conditions associated with progressive iron accumulation in parenchymal tissues leading to eventual organ failure. We have discovered a novel mechanism to reverse iron overload by pharmacological modulation of the divalent metal transporter-1 (DMT-1). DMT-1 mediates intracellular iron transport during the transferrin cycle and apical iron absorption in the duodenum. Additional functions in iron handling in the kidney and liver are less well understood. We show that the L- type calcium-channel blocker nifedipine increases DMT-1 mediated cellular iron transport 10-to 100-fold at concentrations between 1-100 uM. Mechanistically, nifedipine causes this effect by prolongation of the activity of DMT-1 to transport iron. We show that nifedipine mobilizes iron from the liver of mice with primary and secondary iron overload, and enhances urinary iron excretion. Modulation of DMT-1 function by L-type calcium-channel blockers emerges a novel pharmacological concept to treat iron overload disorders.<br> <br> In this experiment mice were subjected to dietary iron overload before being treated with nifedipine at 5 ug/g bodyweight, or mock treated with the same volume of solvent.
Project description:Inflammation influences iron balance in the whole organism. A common clinical manifestation of these changes is the anemia of chronic disease (ACD; also called anemia of inflammation). Inflammation reduces duodenal iron absorption and increases macrophage iron storage, resulting in low serum iron concentrations (hyposideremia). Despite the protection hyposideremia provides against proliferating microorganisms, this iron withholding reduces the iron available to developing red blood cells and eventually contributes to the development of anemia. Hepcidin antimicrobial peptide (Hamp) is a hepatic defensin-like peptide hormone that inhibits duodenal iron absorption and macrophage iron release. Hamp has antimicrobial activity and is part of the type II acute phase response. It is also thought to play a critical regulatory role in the sequestration of iron in the context of ACD. We report that mice with deficiencies in the hemochromatosis gene product, Hfe, mount a general inflammatory response, but lack appropriate Hamp expression and fail to develop hyposideremia. These data suggest a previously unidentified role for Hfe in innate immunity and ACD.
Project description:Anaemia is a frequent complication of chronic infectious diseases but the exact mechanisms by which it develops remain to be clarified. In the present work, we used a mouse model of mycobacterial infection to study molecular alterations of iron metabolism. We show that four weeks after infection with Mycobacterium avium BALB/c mice exhibit a moderate anaemia, which cannot be explained by elevated hepatic hepcidin mRNA expression. Instead, the mice respond with increased mRNA expression of ferroportin (Slc40a1), ceruloplasmin (Cp), hemopexin (Hpx), heme-oxygenase-1 (Hmox1) and lipocalin-2 (Lcn2). Both the anemia and the mRNA expression changes of iron-related genes are largely absent in C.D2 mice which bear a functional allele of the Nramp1 gene. These data suggest that anaemia due to a chronic infection with M. avium develops independently of elevated hepcidin expression and possibly involves ferroportin and/or lipocalin-2.
Project description:This SuperSeries is composed of the following subset Series: GSE29319: Iron-starvation effect on transcriptome of Pseudomonas fluorescens Pf-5: iron(II) chloride GSE29320: Iron-starvation effect on transcriptome of Pseudomonas fluorescens Pf-5: iron(III) chloride Refer to individual Series
Project description:Transcriptomic profiling of Pseudomonas fluorescens Pf-5 comparing iron(III) chloride supplemented grown culture against non-iron treated grown culture in M9 minimal media Two-condition experiment, iron(III) chloride supplemented culture versus non-iron treated culture. 3 biological replicates including 3 technical replicates for one of the biological replicate and 2 technical replicates for another biological replicate. Swap-dye experiments were performed
Project description:Transcriptomic profiling of Pseudomonas fluorescens Pf-5 comparing iron(II) chloride supplemented grown culture against non-iron treated grown culture in M9 minimal media Two-condition experiment, iron(II) chloride supplemented culture versus non-iron treated culture. 4 biological replicates including 3 technical replicates for one of the biological replicates. Swap-dye experiments were performed
Project description:Osteosarcoma (OS) is a common primary bone malignancy that is characterized by high degree of aneuploidy, gene amplification, and multiple unbalanced chromosomal rearrangements. The human osteosarcoma U-2 OS and Sa OS cells lines have been generated more than three decades ago and are used in a wide spectrum of biomedical research. Nevertheless, and despite scattered information about their genetic context, no comprehensive comparative study of their transcriptome profile has been reported to date. The aim of this study was to elucidate common molecular characteristics of the two cell lines as well as differences in their expression profile. Thus the genome wide gene expression profile of the Sa OS cells was compared with reference RNA of U-2 OS cells. These results may provide the basis for future studies and illuminate the molecular differences of the two widely used cell lines.
Project description:Background: Host iron deficiency is protective against severe malaria as the human malaria parasite Plasmodium falciparum depends on free iron from its host to proliferate. Due to the absence of transferrin, ferritin, ferroportin, and a functional heme oxygenase, the parasite’s essential pathways of iron acquisition, storage, export, and detoxification differ from those in humans and may thus be excellent targets for therapeutic development. However, the proteins involved in these processes in P. falciparum remain largely unknown. Experimental design: To identify iron-regulated mechanisms and putative iron transporters in the human malaria parasite Plasmodium falciparum 3D7, we carried out whole-transcriptome profiling using bulk RNA-sequencing. The parasites were cultured either using erythrocytes from a donors with high, medium (healthy) or low iron status (experiment 1); or with red blood cells from another healthy donor in the presence or absence of 0.7 µM hepcidin, a specific ferroportin inhibitor and iron-regulatory hormone (experiment 2). This concentration of hepcidin was reported to reduce binding of ferrous iron to ferroportin by 50% in vitro (39). Samples from three biological replicates each were harvested at the ring and trophozoite stage (6 – 9 and 26 – 29 hours post invasion, hpi) during the second intra-erythrocytic developmental cycle under the conditions specified.
Project description:Iron-sequestration by the human host is a first line defense against respiratory pathogens like Moraxella catarrhalis, which consequently experiences a period of iron-starvation during colonization and infection. We determined the genetic requirements for M. catarrhalis growth during iron-starvation using the high-throughput genome-wide screening technology genomic array footprinting (GAF). To this end, a large marinerT7 transposon mutant library (~28,000 independent transposon mutants) was grown under iron-limiting conditions, achieved by sequestration of iron by 30 M-BM-5M Desferal (DF30), and under control growth conditions (brain heart infusion broth, DF0). Mutants were recovered at exponential- and the early-stationary growth phase and used for the generation of mutant-specific cDNA probes that were hybridized to custom-designed NimbleGen GAF microarrays. The results described in this study are further discussed in Stefan P.W. de Vries, Peter Burghout, Jeroen D. Langereis, Aldert Zomer, Peter W.M. Hermans, Hester J. Bootsma: Genetic requirements for Moraxella catarrhalis growth under iron-limiting conditions, Molecular Microbiology. cDNA probes generated from mutants recovered during the exponential growth phase, or early-stationary phase under challenge (iron-limiting, DF30) or control conditions (DF0). Hybridization on GAF 4x72K custom design Nimblegen GAF arrays for read-out.