Ironing out the details of mucosal healing Anemia is a frequent complication of disorders such as inflammatory bowel disease, occurring in part as a result of increased bleeding into the intestine. Bessman et al. show that the peptide hormone hepcidin, which regulates systemic iron homeostasis, is required for intestinal repair in a mouse model of inflammatory bowel disease (see the Perspective by Rescigno). This effect was independent of hepatocyte-produced hepcidin and systemic iron levels. Instead, production of hepcidin by conventional dendritic cells was necessary and sufficient to promote local iron sequestration by macrophages, which in turn modulated the makeup of the gut microbiota to one with a more beneficial distribution of species. Science , this issue p. 186 ; see also p. 129