Laboratory of Aquaculture & Artemia Reference Center, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Gent, Belgium.
Department of Animal Nutrition and Management, Faculty of Veterinary Medicine and Animal Sciences, Swedish University of Agricultural Sciences, 75007, Uppsala, Sweden.
Fish Shellfish Immunol. 2020 Jul;102:307-315. doi: 10.1016/j.fsi.2020.04.062. Epub 2020 May 3.
β-Glucans have long been used as an immunostimulant in aquaculture. However, the relationship of its structure to its immunomodulatory properties are poorly understood. In this study, the particle size and chemical structure of β-glucans extracted from wild-type strain of baker's yeast (Saccharomyces cerevisiae) and its null-mutant yeasts Gas1 were characterised. Using Sigma β-glucan as a reference, the immunomodulatory properties of these polysaccharides in the germ-free Artemia franciscana model system in the presence of Vibrio harveyi bacterial challenge were investigated. The survival of the A. franciscana nauplii, upon challenge with V. harveyi, was significantly higher in all three glucan-treated groups compared to the control. The glucan Gas1 with a lower degree of branching and shorter side chain length had the most prominent V. harveyi-protective effects. The particle size did not affect the nauplii survival when challenged with V. harveyi. Results also showed that the salutary effect of the tested glucans was associated with the upregulation of innate immune genes such as lipopolysaccharide and β-1,3-glucan-binding protein (lgbp), high mobility group box protein (hmgb), and prophenoloxidase (proPO). Interestingly, the up-regulation of superoxidase dismutase (sod) and glutathione-s-transferase (gst) was only observed in Gas1 treated group, indicating that Gas1 could function to induce higher reactive oxygen species and stronger immunomodulatory function in A. franciscana, and therefore higher survival rate. The expression of heat shock protein 70 (hsp70), peroxinectin (pxn), and down syndrome cell adhesion molecule (dscam) remain unaltered in response to glucan treatment. Taken together, this study provides insights into the structure-function relationship of β-glucan and the results confirmed that β-glucan can be an effective immunostimulant in aquaculture, especially the Gas1 glucan.
β-葡聚糖一直被用作水产养殖中的免疫刺激剂。然而，其结构与其免疫调节特性之间的关系尚未得到充分了解。在这项研究中，我们对从野生型酿酒酵母（Saccharomyces cerevisiae）及其 Gas1 缺失突变酵母中提取的β-葡聚糖的粒径和化学结构进行了表征。以Sigma β-葡聚糖为参照，研究了这些多糖在无菌卤虫（Artemia franciscana）模型系统中的免疫调节特性，同时还研究了在哈维弧菌（Vibrio harveyi）挑战下的情况。与对照组相比，所有三种葡聚糖处理组的卤虫无节幼体在受到哈维弧菌挑战后的存活率均显著提高。分支程度较低、侧链较短的 Gas1 葡聚糖具有最显著的哈维弧菌保护作用。当受到哈维弧菌的挑战时，粒径大小并不会影响无节幼体的存活率。结果还表明，所测试的葡聚糖的有益效果与先天免疫基因的上调有关，如脂多糖和β-1,3-葡聚糖结合蛋白（lgbp）、高迁移率族蛋白 B（hmgb）和原酚氧化酶（proPO）。有趣的是，只有在 Gas1 处理组中观察到超氧化物歧化酶（sod）和谷胱甘肽 S-转移酶（gst）的上调，这表明 Gas1 可以在卤虫中诱导更高的活性氧和更强的免疫调节功能，从而提高存活率。葡聚糖处理后热休克蛋白 70（hsp70）、过氧化物酶（pxn）和唐氏综合征细胞黏附分子（dscam）的表达均未发生变化。综上所述，本研究深入了解了β-葡聚糖的结构-功能关系，结果证实β-葡聚糖可以成为水产养殖中的一种有效免疫刺激剂，尤其是 Gas1 葡聚糖。
