Synthetic Porcine Hepcidin Exhibits Different Roles in Escherichia coli and Salmonella Infections

Hepcidin, an antimicrobial peptide, was discovered to integrate diverse signals from iron status and an infection threat and orchestrate a series of host-protective responses. Several studies have investigated the antimicrobial role of hepcidin, but the results have been controversial. Here, we aimed to examine the role of hepcidin in bacterial adherence and invasion in vitro We found that porcine hepcidin could decrease the amount of the extracellular pathogen enterotoxigenic Escherichia coli (ETEC) K88 that adhered to cells because it caused the aggregation of the bacteria. However, addition of hepcidin to macrophages infected with the intracellular pathogen Salmonella enterica serovar Typhimurium enhanced the intracellular growth of the pathogen through the degradation of ferroportin, an iron export protein, and then the sequestration of intracellular iron. Intracellular iron was unavailable by use of the iron chelator deferiprone (DFO), which reduced intracellular bacterial growth. These results demonstrate that hepcidin exhibits different functions in extracellular and intracellular bacterial infections, which suggests that different defense strategies should be taken to prevent bacterial infection.