Phagocytosis of gadolinium chloride or zymosan induces simultaneous upregulation of hepcidin- and downregulation of hemojuvelin- and Fpn-1-gene expression in murine liver

Abstract

The liver and the spleen are the organs in which cellular material and aged erythrocytes are eliminated from the blood. Within the liver, Kupffer cells (KCs) are mainly responsible for this task, as such KCs have a pivotal role in iron metabolism. The aim of this study is to investigate the changes of hepatic gene expression in two models of KC phagocytosis. Gadolinium chloride (GD) or zymosan was injected intraperitoneally into rats and to endotoxin-resistant mice (C3H/HeJ). The animals were killed at different time points and their livers were immediately frozen in liquid nitrogen for RNA isolation and immunohistological studies. RNA was analyzed by real-time PCR and northern blot. Sera were used to measure transaminases, hepcidin and iron levels. The expression of iron metabolism genes, hepcidin, hemojuvelin (Hjv), ferroportin-1 (Fpn-1) and of the inflammatory cytokines IL-6, IL-1b, TNF-a and IFN-g was determined. Although phagocytosed material was detected in ED-1-and C1q-positive cells, no inflammatory cells were identified within the liver parenchyma. Serum levels of hepcidin, iron and transaminases did not differ from those of control animals. Both GD and zymosan induced an upregulation of hepcidin-gene expression in rat liver as early as 3 h, reaching a maximum 6 h after treatment. Hjv-and Fpn-1-gene expression was downregulated at the same time. IL-6 was by far the most induced acute-phase-cytokine in GD-and zymosan-treated livers, although IL-1b and TNF-a were also strongly upregulated by zymosan and to a lesser extent by GD. Similar results were obtained in the C3H/HeJ mouse strain excluding the possible role of contaminating endotoxin. This study shows that phagocytosis upregulates hepcidin-gene expression and downregulates Hjv-and Fpn-1-gene expression within the liver. These changes in iron-regulating-gene expression may be mediated by the locally produced acute-phase-cytokines.

Kinetic analysis of superparamagnetic iron oxide nanoparticles in the liver of body-temperature-controlled mice using dynamic susceptibility contrast magnetic resonance imaging and an empirical mathematical model

“…As shown in Table 2, there were no significant changes in both ALT and T-BIL among groups injected with various doses of GdCl 3 , suggesting that GdCl 3 does not affect liver function. These results are consistent with previously reported finding [28,29]. When zymosan was used to stimulate the Kupffer cells, the AUC, ΔR 2 max , and ΔR 2 last values increased significantly with increasing dose (Fig.…”

Immunosuppressant-Induced Oxidative Stress and Iron: A Paradigm Shift from Systemic to Intrahepatic Abnormalities

“…Downregulation of Hjv and Heph expression in this study confirms previous studies [12,15,28] in different rat models of extrahepatic and intrahepatic APR that Hepc and Hjv-Heph gene expression together with Fpn-1 changes simultaneously and in an opposite direction. The same results occurred in rats after oral administration of tacrolimus; an early upregulation of Hepc gene expression associated with time-dependent downregulation of Fpn-1, Hjv, and Heph gene expression was observed.…”

Ferroportin-1 is a ‘nuclear'-negative acute-phase protein in rat liver: a comparison with other iron-transport proteins

“…47,48 In fact, the findings presented here are consistent with earlier studies obtained at RNA level, wherein a downregulation of Fpn-1-specific transcripts occurred in parallel with an increase in the level of the acute-phase cytokines (IL-6, IL-1b and TNF-a) reported in different rat models. [48][49][50] Furthermore, in our current study, treatment of rat hepatocytes with cytokines (IL-6, IL-1b and TNF-a) reduced the Fpn-1 gene expression; however, the impact of IL-6 was the strongest compared with that induced by the two other cytokines. Taken together, it became evident that early-observed hepatic Fpn-1 reduction could be due to direct effect of the acute-phase cytokines, 25,48 whereas late decrease in Fpn-1 protein could be due to the combination of both hepcidin and the acute-phase cytokines.…”