Immunology & Vaccinology Group, Centro de Investigaciones Biológicas del Noroeste (CIBNOR), Av. Instituto Politécnico Nacional 195, Playa Palo de Santa Rita, La Paz, B.C.S. 23096, Mexico.
Centro Interdisciplinar de Investigação Marinha e Ambiental (CIIMAR), University of Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208 Porto, Portugal.
Fish Shellfish Immunol. 2018 Jul;78:392-403. doi: 10.1016/j.fsi.2018.04.043. Epub 2018 Apr 21.
β-Glucans are naturally occurring polysaccharides that are produced by bacteria, fungi and yeast. They are considered immunostimulants in fish acting on non-specific defense mechanism. Yeast-derived glucans from cell wall (Sterigmatomyces halophilus, β-Gluc/Sh) have been used for this purpose in this study. Therefore, an in vitro assay using peripheral blood leucocytes (PBLs) from Pacific red snapper was performed to evaluate the stimulant effects of β-Gluc/Sh and zymosan A (positive control) for 12 and 24 h and after bacterial challenge with Aeromonas hydrophila at 24 h. In addition, structural characterization of this marine yeast glucan was performed by proton nuclear magnetic resonance (NMR) revealing structures containing (1-6)-branched (1-3)-β-D-glucan. PBLs responded positively to β-Gluc/Sh where cell viability was higher than 80%. After challenge, β-Gluc/Sh was able to inhibit cytotoxicity caused by A. hydrophila, highlighting that the PBLs incubated with β-Gluc/Sh significantly increased the non-specific immune response, such as phagocytic activity, respiratory burst, nitric oxide and peroxidase activities followed by an increase in superoxide dismutase and catalase activities after 12 and 24 h post-stimulation and after challenge with the pathogen. Regarding induction of antioxidant gene expression, it was more pronounced in stimulated β-Gluc/Sh leucocytes compared to other groups at all experimental times of the trial and after bacterial challenge. Indeed, our results clearly showed the ability of leucocytes to strongly react to β-Gluc/Sh with an increase in cytokine gene expression, particularly the IL-1β, IL-10 and IL-17 genes. These results confirm that S. halophilus yeast-derived β-glucan, isolated from an extreme marine environment, is beneficial for increasing innate immune response and enhancing resistance against A. hydrophila in vitro.
β-葡聚糖是一种天然存在的多糖，由细菌、真菌和酵母产生。它们被认为是鱼类的免疫刺激物，作用于非特异性防御机制。本研究中使用来自细胞壁的酵母衍生葡聚糖（Sterigmatomyces halophilus，β-葡聚糖/Sh）达到此目的。因此，进行了一项使用太平洋红鲷外周血白细胞（PBL）的体外试验，以评估β-葡聚糖/Sh 和酵母聚糖 A（阳性对照）在 12 和 24 小时以及在 24 小时用嗜水气单胞菌进行细菌攻毒后的刺激作用。此外，通过质子核磁共振（NMR）对这种海洋酵母葡聚糖进行了结构表征，揭示了含有（1-6）支链（1-3）-β-D-葡聚糖的结构。PBL 对β-葡聚糖/Sh 反应良好，细胞活力高于 80%。攻毒后，β-葡聚糖/Sh 能够抑制嗜水气单胞菌引起的细胞毒性，这表明与β-葡聚糖/Sh 孵育的 PBL 显著增加了非特异性免疫反应，如吞噬活性、呼吸爆发、一氧化氮和过氧化物酶活性，随后在刺激后 12 和 24 小时以及在病原体攻毒后增加超氧化物歧化酶和过氧化氢酶活性。关于诱导抗氧化基因表达，与其他组相比，在试验的所有实验时间以及在细菌攻毒后，刺激的β-葡聚糖/Sh 白细胞中的表达更为明显。事实上，我们的结果清楚地表明白细胞能够强烈地对β-葡聚糖/Sh 反应，增加细胞因子基因表达，特别是 IL-1β、IL-10 和 IL-17 基因。这些结果证实，从极端海洋环境中分离出的 S. halophilus 酵母衍生的β-葡聚糖有利于提高先天免疫反应，增强体外对嗜水气单胞菌的抵抗力。
