|Title||Iron enhances hepatic fibrogenesis and activates TGF-β signaling in murine hepatic stellate cells|
|Authors||Mehta, K.J., Coombes, J.D., Briones-Orta, M., Manka, P.P., Williams, R., Patel, V.B. and Sin, W.-K.|
Although excess iron induces oxidative stress in the liver, it is unclear whether it directly activates the hepatic stellate cells (HSC).
We evaluated effects of excess iron on fibrogenesis and TGF-β signaling in murine HSC. Cells were treated with holotransferrin (0.005–5 g/L) for 24 h, with or without the iron chelator deferoxamine (10 µM). Gene expressions (α-SMA, Col1-α1, Serpine-1, TGF-β, Hif1-α, Tfrc and Slc40a1) were analyzed by qRT-PCR, while TfR1, ferroportin, ferritin, vimentin, collagen, TGF-β RII and phospho-Smad2 proteins were evaluated by immunofluorescence, western blot and ELISA.
HSC express the iron-uptake protein TfR1, and the iron-export protein ferroportin. Holotransferrin up-regulated TfR1 expression by 1.8-fold (p<0.03) and ferritin accumulation (iron storage) by 2-fold (p<0.01), and activated HSC with 2-fold elevations (p<0.03) in α-SMA mRNA and collagen secretion, and a 1.6-fold increase (p<0.01) in vimentin protein. Moreover, holotransferrin activated the TGF-β pathway with TGF-β mRNA elevated 1.6-fold (p=0.05), and protein levels of TGF-β RII and phospho-Smad2 increased by 1.8-fold (p<0.01) and 1.6-fold (p<0.01), respectively. By contrast, iron chelation decreased ferritin levels by 30% (p<0.03), inhibited collagen secretion by 60% (p<0.01), repressed fibrogenic genes α-SMA (0.2-fold; p<0.05) and TGF-β (0.4-fold; p<0.01), and reduced levels of TGF-β RII and phospho-Smad2 proteins.
HSC express iron transport proteins. Holotransferrin (iron) activates HSC fibrogenesis and the TGF-β pathway, while iron depletion by chelation reverses this, suggesting that this could be a useful adjunct therapy for patients with fibrosis. Further studies in primary human HSC and animal models are necessary to confirm this.
|Keywords||Fibrosis, Fibroblasts, Holotransferrin, Liver|
|Journal||American Journal of the Medical Sciences|
|Journal citation||355 (2), pp. 183-190|
|Accepted author manuscript||Mehta et al. Revised manuscript with figs.pdf|
|Supplementary data or files||Revised Supplementary data 25.1.2017.pdf|
|Mehta et al Revised Figures.pdf|
|Digital Object Identifier (DOI)||doi:10.1016/j.amjms.2017.08.012|
|Published in print||Feb 2018|
|Published online||23 Aug 2017|
|Published||23 Aug 2017|
|License||CC BY-NC-ND 4.0|