Sino-Norway Joint Lab on Fish Gut Microbiota, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China; Jiangxi Academy of Agricultural Sciences, Nanchang, Jiangxi, China.
Sino-Norway Joint Lab on Fish Gut Microbiota, Feed Research Institute, Chinese Academy of Agricultural Sciences, Beijing, China.
Fish Shellfish Immunol. 2019 Mar;86:1064-1071. doi: 10.1016/j.fsi.2018.12.058. Epub 2018 Dec 24.
In this study, we firstly tested the effects of dietary nucleotides on the disease resistance and innate immunity of zebrafish. Further, we investigated the role of intestinal microbiota in the nucleotides-induced immunostimulatory effect by using a germ-free zebrafish model and microbiota transfer technique. Fish were fed control or nucleotides (NT)-supplemented diets (at 0.05%,0.1%, 0.15% or 0.2%, m/m) for 4 weeks, followed by immersion challenge with Aeromonas hydrophila NJ-1. The results showed that 0.1% NT group enhanced the resistance of zebrafish against A. hydrophila infection. We further observed that the relative expressions of mucin, claudin16, occlusin1, hepcidin, defensin beta-like, myeloperoxidase (Mpo), and serum amyloid A (Saa) increased in the 0.1% NT group compared with control (P < 0.05), indicating that dietary nucleotides enhanced the physical barrier and mucosal immunity in the intestine of zebrafish. Moreover, ROS level in the head kidney was significantly increased in NT fed zebrafish versus control (P < 0.05), indicating enhanced systematic immunity. Furthermore, dietary NT significantly elevated the relative expressions of mpo, saa and the ROS activity in germ-free zebrafish, while germ-free zebrafish colonized with NT-altered microbiota had no significant difference in the relative expressions of mpo, saa and the ROS activity compared with the control microbiota-colonized fish, suggesting that the immunostimulatory effect of dietary NT is mediated by direct action of NT and does not involve the microbiota. Consistently, dietary NT can protect germ-free zebrafish from pathogenic infection, whereas germ-free zebrafish colonized with NT microbiota showed no difference in disease resistance compared with control microbiota colonized counterparts. Together, these results indicated that the immunostimulatory and disease protection effect of dietary nucleotides in zebrafish was mediated by direct action of the nucleotides, and does not involve the intestinal microbiota.
在这项研究中，我们首先测试了膳食核苷酸对斑马鱼抗病性和先天免疫的影响。此外，我们通过无菌斑马鱼模型和微生物转移技术，研究了肠道微生物群在核苷酸诱导的免疫刺激作用中的作用。鱼连续 4 周喂食对照或核苷酸（NT）补充饮食（0.05%、0.1%、0.15%或 0.2%，m/m），然后用嗜水气单胞菌 NJ-1 进行浸泡攻毒。结果表明，0.1% NT 组增强了斑马鱼对嗜水气单胞菌感染的抵抗力。我们进一步观察到，与对照组相比，0.1% NT 组斑马鱼肠黏蛋白、 Claudin16、Occludin1、Hepcidin、β-防御素、髓过氧化物酶（Mpo）和血清淀粉样蛋白 A（Saa）的相对表达增加（P<0.05），表明膳食核苷酸增强了斑马鱼肠的物理屏障和黏膜免疫。此外，与对照组相比，NT 喂养的斑马鱼头肾中的 ROS 水平显著增加（P<0.05），表明系统免疫增强。此外，膳食 NT 显著提高了无菌斑马鱼的 mpo、saa 相对表达和 ROS 活性，而用 NT 改变的微生物群定植的无菌斑马鱼在 mpo、saa 相对表达和 ROS 活性方面与对照微生物群定植的鱼没有显著差异，表明膳食 NT 的免疫刺激作用是由 NT 的直接作用介导的，不涉及微生物群。一致地，膳食 NT 可以保护无菌斑马鱼免受致病性感染，而用 NT 微生物群定植的无菌斑马鱼在抗病性方面与对照微生物群定植的对应物没有差异。总之，这些结果表明，膳食核苷酸对斑马鱼的免疫刺激和疾病保护作用是由核苷酸的直接作用介导的，不涉及肠道微生物群。
