AUTHOR=Ortega Leonardo , Carrera Crisleri , Muñoz-Flores Carolina , Salazar Santiago , Villegas Milton F. , Starck María F. , Valenzuela Ariel , Agurto Niza , Montesino Raquel , Astuya Allisson , Parra Natalie , Pérez Ercilia T. , Santibáñez Natacha , Romero Alex , Ruíz Pamela , Lamazares Emilio , Reyes Fátima , Sánchez Oliberto , Toledo Jorge R. , Acosta Jannel 

TITLE=New insight into the biological activity of Salmo salar NK-lysin antimicrobial peptides

JOURNAL=Frontiers in Immunology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1191966

DOI=10.3389/fimmu.2024.1191966

ISSN=1664-3224

ABSTRACT=<p>NK-lysin is a potent antimicrobial peptide (AMP) with antimicrobial activity against bacteria, fungi, viruses, and parasites. NK-lysin is a type of granulysin, a member of the saposin-like proteins family first isolated from a pig’s small intestine. In previous work, for the first time, we identified four variants of <italic>nk-lysin</italic> from Atlantic salmon (<italic>Salmo salar</italic>) using EST sequences. In the present study, we reported and characterized two additional transcripts of <italic>NK-lysin</italic> from <italic>S. salar</italic>. Besides, we evaluated the tissue distribution of three <italic>NK-lysins</italic> from <italic>S. salar</italic> and assessed the antimicrobial, hemolytic, and immunomodulatory activities and signaling pathways of three NK-lysin-derived peptides. The synthetic peptides displayed antimicrobial activity against <italic>Piscirickettsia salmonis</italic> (LF-89) and <italic>Flavobacterium psychrophilum</italic>. These peptides induced the expression of immune genes related to innate and adaptive immune responses <italic>in vitro</italic> and <italic>in vivo</italic>. The immunomodulatory activity of the peptides involves the mitogen-activated protein kinases-mediated signaling pathway, including p38, extracellular signal-regulated kinase 1/2, and/or c-Jun N-terminal kinases. Besides, the peptides modulated the immune response induced by pathogen-associated molecular patterns (PAMPs). Our findings show that NK-lysin could be a highly effective immunostimulant or vaccine adjuvant for use in fish aquaculture.</p>