Effect of lipopolysaccharide and bleeding on the expression of intestinal proteins involved in iron and haem transport.

Haem carrier protein 1 (Hcpl) is a component of the haem-iron uptake pathway in the small intestine. Using quantitative real-time PCR, we examined the expression of Hcp1 and other intestinal iron-transporting proteins in male C57BL/6 mice with experimentally altered iron homeostasis. Intestinal Hcp1 mRNA content was not significantly changed by iron overload (600 mg/kg); however, it was increased to 170 % of controls 72 h after withdrawal of 0.7 ml of blood; the same treatment increased intestinal Cybrd1 mRNA to 900 % of controls. LPS treatment (1 mg/kg, 6 h) decreased intestinal Hcp1 mRNA content to 66 % of controls and Flvcr mRNA content to 65 % of controls, while Cybrd1 mRNA, Dmt1 mRNA and Fpn1 mRNA decreased to 6 %, 43 % and 32 %, respectively. In 129SvJ mice with targeted disruption of the hemojuvelin (Hfe2) gene, which display very low expression of liver hepcidin, Cybrd1 mRNA content increased to 1040 %, Dmt1 mRNA content to 200 % and Fpn1 mRNA to 150 % when compared to wild-type mice; changes in Hcp1, Abcg2 and Flver mRNA content were only minor. Overall, these results suggest that, during inflammation, the intestinal haem-iron uptake pathway is not as strongly transcriptionally downregulated as the non-haem iron uptake pathway. A decrease in circulating hepcidin increases the expression of proteins participating in non-haem iron uptake, but has no significant effect on Hcp1 mRNA content.