Halofuginone suppresses hepcidin by a heparan sulfate-dependent mechanism to treat iron disorders in mice

ABSTRACT: Hepcidin, a liver-derived hormone, is the central regulator of systemic iron homeostasis. Elevated hepcidin levels contribute to iron-refractory iron-deficiency anemia and anemia of inflammation, both characterized by restricted iron availability. Current treatments, such as parenteral iron infusions, are often ineffective and pose risks of adverse reactions, underscoring the need for alternative therapeutic strategies targeting hepcidin. We previously identified a novel hepcidin regulatory pathway involving liver heparan sulfate (HS) proteoglycans (HSPGs), which modulate receptor-ligand interactions through their sulfated HS chains. Recently, we found that halofuginone (HF) impairs HS biosynthesis and considered whether it could be used as a hepcidin modulator. Here, we demonstrate that in human hepatoma (Hep3B) cells, HF inhibits both basal and bone morphogenetic protein 6-induced hepcidin expression and SMAD1 phosphorylation signaling in a dose- and time-dependent manner. Consistently, Hep3B cells lacking HS (EXT1-/-) show no hepcidin suppression in response to HF. In vivo administration of HF reduces hepcidin expression in an iron-overload mouse model (8.3 g/kg carbonyl iron). This effect was absent in mice with impaired liver HS sulfation (Ndst1f/fAlbCre+), confirming that HF suppresses hepcidin via HSPG-mediated mechanisms. Additionally, HF decreased hepcidin expression in mice subjected to acute inflammation. These findings establish HF as a potential therapeutic for mitigating hepcidin-driven iron restriction in anemic disorders.