title: Kupffer cells and macrophages are not required for hepatic hepcidin activation during iron overload.
abstract: Hepcidin, the iron hormone, is produced by the liver in response to iron and inflammation. Its synthesis during inflammation is triggered by cytokines, but the details of iron activation are obscure. We tested the role of Kupffer cells and macrophages by studying iron-loaded or inflamed mice with selective inactivation of Kupffer cells or the in vitro effect of conditioned human macrophages on hepcidin expression. Hepcidin messenger RNA (mRNA) expression was studied by Northern blot and reverse transcriptase polymerase chain reaction analysis in mice that were treated with 40 mg/kg gadolinium (III) chloride (GdCl(3)) as a Kupffer cell inactivating agent and subjected to inflammatory challenges with either lipopolysaccharide (LPS) and turpentine or iron overload by iron-dextran administration. Similar analyses were performed in human hepatoma cells (HepG2) cultured with medium from LPS- or iron-conditioned macrophages from blood donors or patients with HFE-linked hereditary hemochromatosis (HH). In vivo, LPS and particularly turpentine stimulated hepcidin mRNA expression, and this effect was prevented by the inactivation of Kupffer cells. Also, iron overload markedly upregulated hepatic hepcidin mRNA, but this activity persisted in spite of Kupffer cell blockade. In vitro, the medium of LPS-treated normal or hemocromatotic macrophages turned on hepcidin expression. On the contrary, medium of iron-manipulated macrophages, regardless of their HFE status, did not affect hepcidin mRNA steady-state levels. In conclusion, Kupffer cells are required for the activation of hepcidin synthesis during inflammation, and HH inflamed macrophages are capable of mounting a normal response, eventually leading to hepcidin stimulation. However, both Kupffer cells and human macrophages are dispensable for the regulatory activity exerted by iron on hepatic hepcidin.
authors.affiliation: Center for Hemochromatosis, Department of Internal Medicine, University of Modena and Reggio Emilia, Policlinico, Modena, Italy.
authors.forename: Giuliana
authors.initials: G
authors.lastname: Montosi
authors.forename: Elena
authors.initials: E
authors.lastname: Corradini
authors.forename: Cinzia
authors.initials: C
authors.lastname: Garuti
authors.forename: Samuele
authors.initials: S
authors.lastname: Barelli
authors.forename: Stefania
authors.initials: S
authors.lastname: Recalcati
authors.forename: Gaetano
authors.initials: G
authors.lastname: Cairo
authors.forename: Linda
authors.initials: L
authors.lastname: Valli
authors.forename: Elisa
authors.initials: E
authors.lastname: Pignatti
authors.forename: Chiara
authors.initials: C
authors.lastname: Vecchi
authors.forename: Francesca
authors.initials: F
authors.lastname: Ferrara
authors.forename: Antonello
authors.initials: A
authors.lastname: Pietrangelo
mesh_terms: D000328:Adult; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000235:genetics*; D002478:Cells, Cultured; D005260:Female; D005682:Gadolinium / Q000494:pharmacology; D000071020:Hemochromatosis Protein; D064451:Hepcidins; D015395:Histocompatibility Antigens Class I / Q000502:physiology; D006801:Humans; D019190:Iron Overload / Q000378:metabolism*; D007728:Kupffer Cells / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008099:Liver / Q000378:metabolism*; D008264:Macrophages / Q000502:physiology*; D008297:Male; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis
chemical_list: D023181:Antimicrobial Cationic Peptides; C578702:HAMP protein, human; C103673:HFE protein, human; C579599:Hamp protein, mouse; D000071020:Hemochromatosis Protein; D064451:Hepcidins; C499535:Hfe protein, mouse; D015395:Histocompatibility Antigens Class I; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D012333:RNA, Messenger; D005682:Gadolinium; C038958:gadolinium chloride