Teleost antimicrobial peptide hepcidin contributes to host defense of goldfish (Carassius auratus L.) against Trypanosoma carassii.

Hepcidin is an antimicrobial peptide and an iron regulatory protein that prevents the release of excess iron in the blood. There is evidence suggesting that teleost hepcidin is a major player in antimicrobial defense against various bacteria species, but little is known regarding the effects of teleost hepcidin in protozoan parasitic infections. We examined the role of hepcidin during the course of infection of goldfish with Trypanosoma carassii. Quantitative real-time PCR was used to determine the expression of hepcidin in goldfish immune organs during the course of T. carassii infection. During the acute phase of the T. carassii infection, the mRNA levels of hepcidin were up-regulated in liver and kidney. In contrast, an up-regulation of hepcidin mRNA expression in spleen was observed during the chronic phase of the infection. Furthermore, a synthetic goldfish hepcidin peptide induced trypanosome lysis in vitro, and parasite surface disruption was confirmed by scanning electron microscopy (SEM) analysis. These results suggest that, in addition to well-characterized direct antibacterial activities, teleost hepcidin also exhibits trypanocidal activity.