Department of Animal and Aquaculture Sciences, Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway.
Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway.
Front Immunol. 2021 Aug 20;12:708747. doi: 10.3389/fimmu.2021.708747. eCollection 2021.
Aquaculture feeds have changed dramatically from being largely based on fishmeal (FM) towards increased use of plant protein sources, which could impact the fish's immune response. In order to characterize immunomodulatory properties of novel functional ingredients, this study used four diets, one based on FM, a challenging diet with 40% soybean meal (SBM), and two diets containing 40% SBM with 5% of yeast exposed to different down-stream processing conditions: heat-inactivated (ICJ) or autolysation (ACJ). The immunomodulatory effects of the diets were analyzed in the spleen of Atlantic salmon after 37 days of feeding, using a transcriptomic evaluation by RNA sequencing (RNA-seq) and the detection of specific immunological markers at the protein level through indirect Enzyme-linked Immunosorbent Assay (indirect ELISA). The results showed that SBM (compared to FM) induced a down-regulation of pathways related to ion binding and transport, along with an increase at the protein level of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ). On the other hand, while ICJ (compared to FM-group) maintain the inflammatory response associated with SBM, with higher levels of TNFα and IFNγ, and with an upregulation of creatine kinase activity and phosphagen metabolic process, the inclusion of ACJ was able to modulate the response of Atlantic salmon compared to fish fed the SBM-diet by the activation of biological pathways related to endocytosis, Pattern recognition receptor (PPRs)-signal transduction and transporter activity. In addition, ACJ was also able to control the pro-inflammatory profile of SBM, increasing Interleukin 10 (IL-10) levels and decreasing TNFα production, triggering an immune response similar to that of fish fed an FM-based diet. Finally, we suggest that the spleen is a good candidate to characterize the immunomodulatory effects of functional ingredients in Atlantic salmon. Moreover, the inclusion of ACJ in fish diets, with the ability to control inflammatory processes, could be considered in the formulation of sustainable salmon feed.
水产养殖饲料已经从主要以鱼粉 (FM) 为基础，向更多地使用植物蛋白源转变，这可能会影响鱼类的免疫反应。为了描述新型功能性成分的免疫调节特性，本研究使用了四种饲料，一种以 FM 为基础，一种以 40%豆粕 (SBM) 为基础的挑战性饲料，以及两种以 40%SBM 为基础、添加 5%酵母的饲料，酵母经过不同的下游加工处理：热失活（ICJ）或自溶（ACJ）。在经过 37 天的喂养后，通过 RNA 测序（RNA-seq）进行转录组评估，并通过间接酶联免疫吸附试验（indirect ELISA）在蛋白质水平上检测特定的免疫标志物，分析了饲料对大西洋鲑鱼脾脏的免疫调节作用。结果表明，与 FM 相比，SBM 诱导与离子结合和转运相关的途径下调，同时促炎细胞因子如肿瘤坏死因子-α (TNFα) 和干扰素-γ (IFNγ) 的蛋白水平升高。另一方面，与 FM 组相比，ICJ 维持与 SBM 相关的炎症反应，TNFα 和 IFNγ 水平更高，肌酸激酶活性和磷酸原代谢过程上调，而 ACJ 的添加能够通过激活与内吞作用、模式识别受体（PPRs）-信号转导和转运体活性相关的生物学途径，调节大西洋鲑鱼的反应。此外，ACJ 还能够控制 SBM 的促炎特征，增加白细胞介素 10 (IL-10) 水平，降低 TNFα 产生，引发与基于 FM 的饮食喂养的鱼类相似的免疫反应。最后，我们认为脾脏是描述大西洋鲑鱼功能性成分免疫调节作用的良好候选器官。此外，在可持续鲑鱼饲料的配方中，考虑在饲料中添加 ACJ，以控制炎症过程。
