Host defense peptides (HDPs, also known as antimicrobial peptides) are crucial components of the immune system. To date, the piscidin family has been described exclusively in teleosts, and they are recognized for forming helical structures (Asensio-Calavia et al., 2023). In this study, our objective was to characterize the in vitro activity of two synthetic piscidins (piscidin 1 and piscidin 2) originally identified in the genome of gilthead seabream (Sparus aurata) (Serna-Duque et al., 2022). We studied their antimicrobial activity by determining the minimum inhibitory concentration (MIC) against three pathogens (Vibrio harveyi, Vibrio anguillarum, Vibrio alginolyticus) and one probiotic (Shewanella putrefaciens, SpPdp11), their hemolytic activity against gilthead seabream erythrocytes and cytotoxic activity against a fish cell line (SAF-1). Finally, we set out to explore their immunomodulatory properties that are less well known in HDPs, specifically, to study whether piscidins modulate the release of extracellular traps (ETs) from seabream head kidney leucocytes. Piscidin 1 has strong antimicrobial activity (MIC: < 50µM) against pathogenic bacteria and low activity against Pdp11. Piscidin 1 has a remarkable hemolytic activity (<40%) and modulates immune responses by promoting the release of ETs from seabream head kidney leucocytes. In contrast, piscidin 2 showed lesser effects than piscidin 1 in all activities tested. Therefore, the results suggest the different involvement of the two piscidins in immunity. Piscidin 1 could be a potential therapeutic candidate to address some of the current health challenges present in aquaculture production.
Bibliography
Asensio-Calavia, P., González-Acosta, S., Otazo-Pérez, A., López, M. R., Morales-delaNuez, A., & Pérez de la Lastra, J. M. (2023). Teleost Piscidins-In Silico Perspective of Natural Peptide Antibiotics from Marine Sources. Antibiotics (Basel), 12(5). https://doi.org/10.3390/antibiotics12050855
Serna-Duque, J. A., Cuesta, A., Sánchez-Ferrer, Á., & Esteban, M. Á. (2022). Two duplicated piscidin genes from gilthead seabream (Sparus aurata) with different roles in vitro and in vivo. Fish & Shellfish Immunology, 127, 730-739. https://doi.org/https://doi.org/10.1016/j.fsi.2022.07.013
Acknowledgments
Claudia Marín-Parra (PRE2021-098414) and Jhon A.Serna Duque (FPU19/02192) have PhD grants. This study was funded by the Proyecto de investigación PID2020-113637RB-C21 financiado por MCIN/ AEI /10.13039/501100011033 and forms part of the ThinkInAzul programme supported by MCIN with funding from European Union Next Generation EU(PRTR-C17.I1) and by the Comunidad Autónoma de la Región de Murcia-Fundación Séneca (Spain).