Regulation of iron uptake in primary culture rat hepatocytes: the role of acute-phase cytokines

Shakil Ahmad, Sadaf Sultan, Naila Naz, Ghayyor Ahmad, Salamah Mohammad Alwahsh, Silke Cameron, Federico Moriconi, Giuliano Ramadori, Ihtzaz Ahmed Malik

Research output: Contribution to journalArticlepeer-review

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.

Original languageEnglish
Pages (from-to)337-45
Number of pages9
JournalShock. Injury,Inflammation and Sepsis
Volume41
Issue number4
DOIs
Publication statusPublished - Apr 2014

Keywords

  • Acute-Phase Reaction
  • Animals
  • Apoferritins
  • Cells, Cultured
  • Cytokines
  • Dose-Response Relationship, Drug
  • Drug Combinations
  • Hepatocytes
  • Interleukin-6
  • Iron
  • L-Lactate Dehydrogenase
  • Lipocalins
  • Male
  • RNA, Messenger
  • Rats
  • Rats, Wistar
  • Receptors, Transferrin
  • Up-Regulation

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