Effect of dietary replacement of fish meal with insect meal on in vitro bacterial and viral induced gene response in Atlantic salmon (Salmo salar) head kidney leukocytes

• Published in: Fish & Shellfish Immunology
• Main Authors: Oda Kvalsvik Stenberg, Elisabeth Holen, Luisa Piemontese, Nina S. Liland, Erik-Jan Lock, Marit Espe, Ikram Belghit
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: Atlantic salmon; Salmo salar
• Online Access: https://www.openaccessrepository.it/record/35898; https://doi.org/10.1016/j.fsi.2019.05.042

Abstract With the fast growth of today's aquaculture industry, the demand for aquafeeds is expanding dramatically. Insects, which are part of the natural diet of salmonids, could represent a sustainable ingredient for aquaculture feed. The aim of the current study was to test how a partial or total replacement of dietary fishmeal with insect meal affect gene responses involved in inflammation, the eicosanoid pathway and stress response in Atlantic salmon (Salmo salar L.) in isolated head kidney leukocytes after exposure to bacterial or viral mimic. Insect meal (IM) was produced from black soldier fly (BSF, Hermetia illucens) larvae. Seawater Atlantic salmon were fed three different diets for 8 weeks; a control diet (IM0, protein from fishmeal and plant based ingredients (25:75) and lipid from fish oil and vegetable oil (33:66); and two insect-meal containing diets, IM66 and IM100, where 66 and 100% of the fishmeal protein was replaced with IM, respectively. Leukocytes were isolated from the head kidney of fish (n = 6) from each of the three dietary groups. Isolated leukocytes were seeded into culture wells and added either a bacterial mimic (lipopolysaccharide, LPS) or a viral mimic (polyinosinic acid: polycytidylic acid, poly I: C) to induce an inflammatory response. Controls (Ctl) without LPS and poly I: C were included. The transcription of interleukins IL-1β, IL-8, IL-10 and TNF-α were elevated in LPS treated leukocytes isolated from salmon fed the three dietary groups (IM0, IM66 and IM100). The inflammatory-related gene expression in head kidney cells were, however, not affected by the pre-fed substitution of fish meal with IM in the diet of salmon. Gene transcriptions of PTGDS and PTGES were neither affected by LPS, poly I: C or the experimental diets fed prior to cell isolation, while salmon fed with IM showed a lower expression of LOX5. The gene expression of TLR22 and C/EBP-β were down-regulated by the LPS treatment in the cells isolated from salmon fed insect-based diets (IM66 and IM100) compared to ...