Participation of hepcidins in the inflammatory response triggers by λ-carrageenin in gilthead seabream (Sparus aurata)

Abstract

The role of hepcidins, antimicrobial peptides involved in iron metabolism, immunity, and inflammation is studied. First, gilthead seabream (Sparus aurata L.) head-kidney leucocytes (HKLs) were incubated with λ-carrageenin to study the expression of hepcidin and iron metabolism-related genes. The expression of most of the genes studied was up-regulated, whereas the ferroportin gene (slc40a) was down-regulated in HKLs incubated with λ-carrageenin. In the second part of the study, seabream specimens were injected with λ-carrageenin or buffer (control). The expression of the same genes was evaluated in the head kidney, liver, and skin at different time points after injection. The expression of Hamp1m, ferritin b and ferroportin genes (hamp1, fthb, and slc40a) was up-regulated in the head kidney of fish from the λ-carrageenin group, while the expression of Hamp2C and Hamp2E genes (hamp2.3 and hamp2.7) was down-regulated. In the liver, the expression of hamp1, ferritin a (ftha), slc40a, Hamp2J and Hamp2D (hamp2.5/6) genes was down-regulated in the λ-carrageenin group. In the skin, the expression of hamp1 and (Hamp2A Hamp2C) hamp2.1/3/4 genes was up-regulated in the λ-carrageenin group. A bioinformatic analysis was performed to predict the presence of transcription factor binding sites in the promoter region of hepcidins. Structural and physicochemical variations were found in the different mature hepcidin peptides. This study sheds light on the poorly understood roles of hepcidins in fish. The results provide insight into the regulatory mechanisms of inflammation in fish and could contribute to the development of new strategies for treat inflammation in farm animals.