Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 2TZ, UK.
Grupo de Investigación en Acuicultura (GIA), Instituto Universitario ECOAQUA, Universidad de Las Palmas de Gran Canaria (ULPGC), Crta. Taliarte s/n, 35214, Telde, Las Palmas, Canary Islands, Spain.
Mol Immunol. 2019 Oct;114:378-388. doi: 10.1016/j.molimm.2019.08.005. Epub 2019 Aug 23.
Antimicrobial peptides (AMPs) play an important role in the innate immune response of vertebrates by creating a hostile environment for any invading pathogens. Piscidins are potent teleost specific AMPs, which have a broad spectrum activity. We have identified a novel piscidin active peptide, in the greater amberjack, Seriola dumerili, that consists of 25 aa, which forms an amphipathic helix with distinct hydrophobic and positively charged regions. Following homology and phylogenetic analysis the greater amberjack piscidin was deemed to belong to the group 3 family of piscidins. Piscidin was expressed constitutively at immune sites, with transcript level highest in the spleen and gut, at an intermediate level in the gills and lowest in the head kidney. Following in vivo stimulation with PAMPs (poly I:C, LPS and flagellin) piscidin transcript level increased in gills in response to flagellin, in gut and spleen in response to poly I:C, and in head kidney in response to poly I:C, LPS and flagellin. Head kidney and spleen cells were then isolated from greater amberjack and incubated with each of the PAMPs for 4, 12 and 24 h. Piscidin expression was unchanged at 4 and 12 h post PAMP stimulation in head kidney cells but at 24 h transcript level was markedly upregulated compared to control (unstimulated) cells, especially with the bacterial PAMPs. In contrast, spleen cells upregulated piscidin expression by 4 h post stimulation with poly I:C and flagellin, and remained upregulated to 24 h with flagellin exposure, but had returned to baseline levels by 12 h using poly I:C. To determine if piscidin expression could be modulated by diet, greater amberjack were fed diets supplemented with MOS and cMOS for 30 days when transcript level was determined. It was found that MOS supplemented diets increased expression in the spleen, cMOS supplemented diets upregulated transcript levels in the gills and head kidney, whilst a diet containing both MOS and cMOS upregulated transcript in the gut, when compared to fish fed the control diet. Finally, a synthetic greater amberjack piscidin was produced and showed bacteriostatic activity against a number of bacterial strains, including both Gram positive and Gram negative fish pathogens.
抗菌肽 (AMPs) 在脊椎动物的先天免疫反应中发挥重要作用，为任何入侵的病原体创造了一个敌对的环境。鱼精蛋白是一种有效的硬骨鱼特异性 AMP，具有广谱活性。我们在黄鳍金枪鱼中发现了一种新的鱼精蛋白活性肽，由 25 个氨基酸组成，形成一个具有明显疏水性和正电荷区域的两亲性螺旋。经过同源性和系统发育分析，黄鳍金枪鱼鱼精蛋白被认为属于鱼精蛋白第 3 组家族。鱼精蛋白在免疫部位持续表达，脾脏和肠道中的转录水平最高，鳃和头肾中的转录水平中等，头肾中的转录水平最低。在体内用 PAMP（聚 I:C、LPS 和鞭毛蛋白）刺激后，黄鳍金枪鱼的鱼精蛋白转录水平在鳃中对鞭毛蛋白、在肠中和脾脏中对聚 I:C、在头肾中对聚 I:C、LPS 和鞭毛蛋白均有升高。然后从黄鳍金枪鱼中分离出头肾和脾脏细胞，并分别用每种 PAMP 孵育 4、12 和 24 小时。在头肾细胞中，PAMP 刺激后 4 和 12 小时，鱼精蛋白的表达没有变化，但在 24 小时时，与对照（未刺激）细胞相比，转录水平显著上调，尤其是在细菌 PAMP 刺激后。相比之下，在 PAMP 刺激后 4 小时，脾脏细胞中鱼精蛋白的表达上调，在鞭毛蛋白刺激下，24 小时仍保持上调，但在聚 I:C 刺激下 12 小时已恢复到基线水平。为了确定鱼精蛋白的表达是否可以通过饮食来调节，在进行转录水平测定时，用添加 MOS 和 cMOS 的饲料喂养黄鳍金枪鱼 30 天。结果发现，MOS 补充饲料增加了脾脏中的表达，cMOS 补充饲料增加了鳃和头肾中的转录水平，而同时含有 MOS 和 cMOS 的饲料则增加了肠道中的转录水平，与对照组相比，鱼精蛋白在肠道中表达上调。最后，合成了一种黄鳍金枪鱼鱼精蛋白，并显示出对多种细菌菌株的抑菌活性，包括革兰氏阳性和革兰氏阴性鱼类病原体。
