Distinct requirements for Hfe in basal and induced hepcidin levels in iron overload and inflammation

被引:57
作者
Constante, Marco
Jiang, Wenlei
Wang, Dongmei
Raymond, Valerie-Ann
Bilodeau, Marc
Santos, Manuela M.
机构
[1] CHUM, Hop Notre Dame, Ctr Rech, Montreal, PQ H2L 4M1, Canada
[2] Hop St Luc, Montreal, PQ H2X 1P1, Canada
来源
AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY | 2006年 / 291卷 / 02期
基金
加拿大健康研究院;
关键词
ferroportin; 1; Toll-like receptor 4; beta; 2m; hereditary hemochromatosis; lipopolysaccharide;
D O I
10.1152/ajpgi.00092.2006
中图分类号
R57 [消化系及腹部疾病];
学科分类号
摘要
Hepcidin is a negative regulator of iron absorption produced mainly by the liver in response to changes in iron stores and inflammation, and its levels have been shown to regulate the intestinal basolateral iron transporter ferroportin1 (Fp1). Hereditary hemochromatosis patients and Hfe-deficient mice show inappropriate expression of hepcidin but, in apparent contradiction, still retain the ability to regulate iron absorption in response to alterations of iron metabolism. To further understand the molecular relationships among Hfe, hepcidin, and Fp1, we investigated hepcidin and Fp1 regulation in Hfe-deficient mice (Hfe(-/-) and beta 2m(-/-)) in response to iron deprivation, iron loading, and acute inflammation. We found that whereas basal hepcidin levels were manifestly dependent on the presence of Hfe and on the mouse background, all Hfe-deficient mice were still able to regulate hepcidin in situations of altered iron homeostasis. In the liver, Fp1 was modulated in opposite directions by iron and LPS, and its regulation in Hfe-deficient mice was similar to that observed in wild-type mice. In addition, we found that iron-deprived mice were able to mount a robust response after LPS challenge and that Toll-like receptor 4 (TLR-4)-deficient mice fail to regulate hepcidin expression in response to LPS. In conclusion, these results suggest that although Hfe is necessary for the establishment of hepcidin basal levels, it is dispensable for hepcidin regulation through both the iron-sensing and inflammatory pathways, and hepatic Fp1 regulation is largely independent of hepcidin and Hfe. The inflammatory pathway overrides the iron-sensing pathway and is TLR-4 dependent.
引用
收藏
页码:G229 / G237
页数:9
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