Department of Biology, University of Waterloo, Waterloo, ON, Canada.
Canadian Centre for Human Microbiome and Probiotics Research, Lawson Health Research Institute, London, ON, Canada.
Front Immunol. 2024 Mar 27;15:1306458. doi: 10.3389/fimmu.2024.1306458. eCollection 2024.
Microbial management is central to aquaculture's efficiency. MA18/5M has shown promising results promoting growth, modulation of the immune response, and disease resistance in many fishes. However, the mechanisms through which this strain confers health benefits in fish are poorly understood, particularly in Pacific salmonid models. Briefly, the aims of this study were to i) assess the protective effects of MA18/5M by examining gut barrier function and the expression of tight junction (TJ) and immune genes and , and ii) to determine the protective effects of this strain against a common saltwater pathogen, J382. An model of the salmonid gut was employed utilizing the cell line RTgutGC. Barrier formation and integrity assessed by TEER measurements in RTgutGC, showed a significant decrease in resistance in cells exposed only to J382 for 24 h, but pre-treatment with MA18/5M for 48 h mitigated these effects. While MA18/5M did not significantly upregulate tight junction and immune molecules, pre-treatment with this strain protected against pathogen-induced insults to the gut barrier. In particular, the expression of was significantly induced by J382, suggesting that this molecule might play a role in the host response against this pathogen. To corroborate these observations in live fish, the effects of MA18/5M was evaluated in Chinook salmon reared in real aquaculture conditions. Supplementation with MA18/5M had no effect on Chinook salmon growth parameters after 10 weeks. Interestingly, histopathological results did not show alterations associated with MA18/5M supplementation, indicating that this strain is safe to be used in the industry. Finally, the expression pattern of transcripts encoding TJ and immune genes in all the treatments suggest that variation in expression is more likely to be due to developmental processes rather than MA18/5M supplementation. Overall, our results showed that MA18/5M is a safe strain for use in fish production, however, to assess the effects on growth and immune response previously observed in other salmonid species, an assessment in adult fish is needed.
微生物管理是水产养殖效率的核心。MA18/5M 在促进许多鱼类生长、调节免疫反应和抗病性方面表现出了有前景的结果。然而，这种菌株在鱼类中赋予健康益处的机制还了解甚少，特别是在太平洋鲑鱼模型中。简而言之，本研究的目的是：i）通过检查肠道屏障功能以及紧密连接（TJ）和免疫基因的表达来评估 MA18/5M 的保护作用，和 ii）确定该菌株对常见海水病原体 J382 的保护作用。利用 RTgutGC 细胞系，采用鲑鱼肠道模型。在 RTgutGC 中通过 TEER 测量评估屏障形成和完整性，结果显示仅暴露于 J382 24 小时的细胞的电阻显著降低，但用 MA18/5M 预处理 48 小时减轻了这些影响。虽然 MA18/5M 没有显著上调紧密连接和免疫分子，但该菌株的预处理可防止病原体对肠道屏障的损伤。特别是，J382 显著诱导了 的表达，表明该分子可能在宿主对这种病原体的反应中发挥作用。为了在活体鱼中证实这些观察结果，评估了 MA18/5M 在真实水产养殖条件下养殖的奇努克鲑鱼的影响。在 10 周后，MA18/5M 的补充对奇努克鲑鱼的生长参数没有影响。有趣的是，组织病理学结果没有显示与 MA18/5M 补充相关的改变，表明该菌株在工业中使用是安全的。最后，所有处理中编码 TJ 和免疫基因的转录本的表达模式表明，表达的变化更可能是由于发育过程而不是 MA18/5M 的补充。总的来说，我们的结果表明 MA18/5M 是一种安全的菌株，可用于鱼类生产，但要评估其在其他鲑鱼物种中观察到的生长和免疫反应的影响，需要对成鱼进行评估。
