Immunomodulatory effects of hydrolyzed Debaryomyces hansenii in Atlantic salmon (Salmo salar L): From the in vitro model to a natural pathogen challenge after seawater transfer

• Published in: Aquaculture Vol. 578; p. 740035
• Main Authors: Morales-Lange, Byron, Hansen, Jon Øvrum, Djordjevic, Brankica, Mydland, Liv Torunn, Castex, Mathieu, Mercado, Luis, Imarai, Mónica, Sørum, Henning, Øverland, Margareth
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-01-2024
• Subjects: Functional aquafeeds; Head kidney leukocytes; Humoral response; Microbial ingredients; Non-saccharomyces yeast; Specific immunoglobulins; Winter ulcer; Microbial ingredients; Humoral response; Winter ulcer; Specific immunoglobulins; Non-saccharomyces yeast; Functional aquafeeds; Head kidney leukocytes
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2023.740035

Non-Saccharomyces yeast such as Debaryomyces hansenii or its cell wall-components are emerging candidates for novel functional aquafeeds, as they contain several microbe-associated molecular patterns (MAMPs) that can activate and modulate the host's physiological responses, thereby improving fish health and welfare. In this study, we combined in vitro work using SHK-1 cell line and primary cultures of head kidney leukocytes (HKL) from Atlantic salmon (HKL), with an in vivo trial in which two groups of Atlantic salmon were fed 0.1% hydrolyzed D. hansenii (LAN6) in freshwater (7 weeks) and seawater (6 weeks). In vitro results by ELISA showed that after induction with LAN6, SHK-1 cells increased the levels of TNFα and iNOS (at 6 h post-induction), while HKL increased TNFα (6 h post-induction) and IL-10 (24 h post-induction), and reduced TNFα levels at 24 h post-induction. In addition, during an early natural pathogen challenge in the seawater stage (week 5), an increase in specific plasma immunoglobulins against Moritella viscosa, along with an upregulation in pathways associated with humoral immunity and complement activation in the liver was detected in vaccinated fish fed LAN6 (Group A). These data suggest that LAN6 was able to modulate the immune response of Atlantic salmon making it a promising functional feed additive for aquafeeds to achieve a more resilient farmed salmon.
•SHK-1 cells showed an increase in TNFα and iNOS at 6 h post-induction with hydrolyzed Debaryomyces hansenii (LAN6).•Primary cultures of salmon head kidney leukocytes showed higher levels of TNFα (6h) and IL-10 (24h) post-LAN6 induction.•Vaccinated salmon (Group A) fed LAN6 showed higher levels of specific plasma immunoglobulins against Moritella viscosa.•RNAseq on liver from fish (Group A) fed LAN6 showed an up-regulation of humoral immune response by the complement pathway.