Dietary Immunostimulant CpG Modulates MicroRNA Biomarkers Associated with Immune Responses in Atlantic Salmon (Salmo salar)

• Published in: Cells
• Main Authors: Xue, Xi, Woldemariam, Nardos Tesfaye, Rise, Matthew L., Andreassen, Rune
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI 2019
• Subjects: CpG ODN; Immunostimulants; Functional feed; Immune responses; miRNA; Biomarkers; Micro ribonucleic acids; Cytosine–phosphate–guanine oligodeoxynucleotide motifs; Canada; Newfoundland; Atlantic salmon; Salmo salar; University of Newfoundland
• Online Access: https://hdl.handle.net/10642/7942; https://doi.org/10.3390/cells8121592

MicroRNAs (miRNAs) are key regulators in fish immune responses. However, no study has previously characterized the impact of polyriboinosinic polyribocytidylic acid (pIC) and formalin-killed typical Aeromonas salmonicida (ASAL) on miRNA expression in Atlantic salmon fed a commercial diet with and without immunostimulant CpG. To this end, first, we performed small RNA deep sequencing and qPCR analyses to identify and confirm pIC- and/or ASAL-responsive miRNAs in the head kidney of salmon fed a control diet. DESeq2 analyses identified 12 and 18 miRNAs differentially expressed in pIC and ASAL groups, respectively, compared to the controls. Fifteen of these miRNAs were studied by qPCR; nine remained significant by qPCR. Five miRNAs (miR-27d-1-2-5p, miR-29b-2-5p, miR-146a-5p, miR-146a-1-2-3p, miR-221-5p) were shown by qPCR to be significantly induced by both pIC and ASAL. Second, the effect of CpG-containing functional feed on miRNA expression was investigated by qPCR. In pre-injection samples, 6 of 15 miRNAs (e.g., miR-181a-5-3p, miR-462a-3p, miR-722-3p) had significantly lower expression in fish fed CpG diet than control diet. In contrast, several miRNAs (e.g., miR-146a-1-2-3p, miR-192a-5p, miR-194a-5p) in the PBS- and ASAL-injected groups had significantly higher expression in CpG-fed fish. Multivariate statistical analyses confirmed that the CpG diet had a greater impact on miRNA expression in ASAL-injected compared with pIC-injected fish. This study identified immune-relevant miRNA biomarkers that will be valuable in the development of diets to combat infectious diseases of salmon. This study was funded by a Norwegian Research Council grant (280839/E40) to R.A., a High North Programmegrant(HNP-2015/10026)ofNorwaytoR.A.andM.L.R.,aGenomicApplicationsPartnershipProgram [GAPP #6607: the Integrated Pathogen Management of Co-infection in Atlantic salmon (IPMC) project] funded by the Government of Canada through Genome Canada and Genome Atlantic, and Cargill Innovation (formerly EWOS Innovation) to M.L.R., as well as a Natural Sciences and Engineering Research Council of Canada (NSERC) DiscoveryGranttoM.L.R.(341304-2012). TheIPMCprojectwasalsofundedbytheGovernmentofNewfoundland and Labrador through the Department of Tourism, Culture, Industry and Innovation (Leverage R&D award #5401-1019-108). X.X. is supported by a Postgraduate Scholarship-Doctoral (PGS D) from NSERC and a Memorial University of Newfoundland SGS fellowship. publishedVersion