Iron-Refractory Iron Deficiency Anemia: New Molecular Mechanisms

摘要

Iron deficiency is a common cause of anemia. In end-stage renal disease (ESRD), iron deficiency impairs the therapeutic efficacy of recombinant erythropoietin. Oral or parental iron supplements usually are effective in treating iron deficiency anemia (IDA). Some patients, however, respond poorly to iron supplements and are diagnosed as having iron-refractory iron deficiency anemia (IRIDA). The disease represents a medical challenge but its underlying mechanism was unclear. Hepcidin is a central player in iron homeostasis. It down-regulates the iron exporter ferroportin, thereby inhibiting iron absorption, release and recycling. In ESRD, plasma hepcidin levels are elevated, which contributes to iron deficiency in patients. Matriptase-2, a liver transmembrane serine protease, has been found to have a major role in controlling hepcidin gene expression. In mice, defects in the Tmprss6 gene encoding matriptase-2 result in high hepcidin expression and cause severe microcytic anemia. Similarly, mutations in the human TMPRSS6 gene have been identified in patients with IRIDA. Thus, matriptase-2 is critical for iron homeostasis and may play a role in renal disease.