title: Regulation of iron uptake in primary culture rat hepatocytes: the role of acute-phase cytokines.
abstract: Decreased serum and increased hepatic iron uptake is the hallmark of acute-phase (AP) response. Iron uptake is controlled by iron transport proteins such as transferrin receptors (TfRs) and lipocalin 2 (LCN-2). The current study aimed to understand the regulation of iron uptake in primary culture hepatocytes in the presence/absence of AP mediators. Rat hepatocytes were stimulated with different concentrations of iron alone (0.01, 0.1, 0.5 mM) and AP cytokines (interleukin 6 [IL-6], IL-1β, tumor necrosis factor α) in the presence/absence of iron (FeCl3: 0.1 mM). Hepatocytes were harvested at different time points (0, 6, 12, 24 h). Total mRNA and proteins were extracted for reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blot. A significant iron uptake was detected with 0.1 mM iron administration with a maximum (133.37 ± 4.82 µg/g of protein) at 24 h compared with control and other iron concentrations. This uptake was further enhanced in the presence of AP cytokines with a maximum iron uptake (481 ± 25.81 µg/g of protein) after concomitant administration of IL-6 + iron to cultured hepatocytes. Concomitantly, gene expression of LCN-2 and ferritin subunits (light- and heavy-chain ferritin subunits) was upregulated by iron or/and AP cytokines with a maximum at 24 h both at mRNA and protein levels. In contrast, a decreased TfR1 level was detected by IL-6 and iron alone, whereas combination of iron and AP cytokines (mainly IL-6) abrogated the downregulation of TfR1. An increase in LCN-2 release into the supernatant of cultured hepatocytes was observed after addition of iron/AP cytokines into the medium. This increase in secretion was further enhanced by combination of IL-6 + iron. In conclusion, iron uptake is tightly controlled by already present iron concentration in the culture. This uptake can be further enhanced by AP cytokines, mainly by IL-6.
authors.affiliation: Division of Gastroenterology and Endocrinology, Department of Internal Medicine, University Medical Center, Georg-August University, Goettingen, Germany.
authors.forename: Shakil
authors.initials: S
authors.lastname: Ahmad
authors.forename: Sadaf
authors.initials: S
authors.lastname: Sultan
authors.forename: Naila
authors.initials: N
authors.lastname: Naz
authors.forename: Ghayyor
authors.initials: G
authors.lastname: Ahmad
authors.forename: Salamah Mohammad
authors.initials: SM
authors.lastname: Alwahsh
authors.forename: Silke
authors.initials: S
authors.lastname: Cameron
authors.forename: Federico
authors.initials: F
authors.lastname: Moriconi
authors.forename: Giuliano
authors.initials: G
authors.lastname: Ramadori
authors.forename: Ihtzaz Ahmed
authors.initials: IA
authors.lastname: Malik
mesh_terms: D000210:Acute-Phase Reaction / Q000378:metabolism*; D000818:Animals; D001052:Apoferritins / Q000096:biosynthesis; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism*; D015850:Interleukin-6 / Q000494:pharmacology; D007501:Iron / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D000071068:Lipocalin-2; D054834:Lipocalins / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D011990:Receptors, Transferrin / Q000096:biosynthesis; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016207:Cytokines; D004338:Drug Combinations; D015850:Interleukin-6; C097278:Lcn2 protein, rat; D000071068:Lipocalin-2; D054834:Lipocalins; D012333:RNA, Messenger; D011990:Receptors, Transferrin; C545564:Tfrc protein, rat; D001052:Apoferritins; D007501:Iron; D007770:L-Lactate Dehydrogenase