Iron supplementation affects the production of pro-inflammatory cytokines in IL-10 deficient mice

Iron supplements may increase disease activity in inflammatory bowel disease through the production of the hydroxyl radical because of its catalytic activity in the Fenton reaction. The purpose of this study was to assess the effect of dietary and locally administered iron in the IL-10 knock-out (-/-) mouse, a model of chronic inflammatory bowel disease.

IL10-/- and wild-type mice received a standard or a high-iron diet (35 mg kg(-1) ferrosulphate vs. 500 mg kg(-1) ferrosulphate) after weaning. After 4 weeks the mice were sacrificed. Furthermore, a group of adult IL-10 knock-out mice was given three iron-containing enema's (0.2 mL of 1 mM ferrous-ammonium sulphate) or phosphate buffered saline. These mice were sacrificed after 1 week. Production of pro-inflammatory cytokines by colon tissue cultures, haematological parameters and histology was determined to assess inflammatory activity.

Oral as well as rectal administration of iron resulted in increased pro-inflammatory cytokine production in IL-10-/- mice. Neutrophil counts in IL10-/- on a high iron diet increased as well. No enhanced colonic inflammation was noted on histology after iron supplementation.

We conclude that dietary or topical administered iron increases pro-inflammatory cytokine production in the colon of IL10-/- mice. No significant increase of histological intestinal inflammation was observed.