Qiu Xingyang, Lv Mengyuan, Jian Xiaoyu, Chen Di, Zhou Hong, Zhang Anying, Wang Xinyan
Center for Informational Biology, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China.
Center for Informational Biology, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, People's Republic of China.
Fish Shellfish Immunol. 2017 Jul;66:148-155. doi: 10.1016/j.fsi.2017.05.024. Epub 2017 May 8.
Interleukin 26 (IL-26) gene has been identified in human, amphibian and teleost but not in rodents. It is well accepted that IL-26 was a crucial member of IL-10 family which acts as a pro-inflammatory cytokine in human. However, the role of IL-26 in regulating inflammation in lower vertebrates including teleost has not been defined yet. In the present study, grass carp IL-26 (gcIL-26) coding sequence was isolated and identified. Its chromosomal synteny was also analyzed, showing that gcIL-26 gene is flanked by IL-22 and IFN-γ genes with the same transcriptional orientation as seen in human, amphibian and zebrafish. Given that zebrafish and grass carp IL-26 shared relatively low amino acid identities with human IL-26, the functional roles of fish IL-26 are indispensable to be elucidated. Accordingly, recombinant gcIL-26 (rgcIL-26) was prepared by using Pichia pastoris expression system, and it was found to be partially glycosylated. Using grass carp head kidney leucocytes as cell model, rgcIL-26 displayed the bioactivity to stimulate the mRNA expression of some pro-inflammatory cytokines including IL-8, IL-1β and IL-6, while inhibit mRNA expression of an anti-inflammatory cytokine, IL-10. Moreover, rgcIL-26 also up-regulated inos expression and NO production in grass carp monocytes/macrophages, strengthening its pro-inflammatory properties in fish. Those results collectively demonstrated the functional role of IL-26 in regulating inflammatory response in fish.
白细胞介素26（IL-26）基因已在人类、两栖动物和硬骨鱼中被鉴定出来，但在啮齿动物中未被发现。人们普遍认为IL-26是IL-10家族的关键成员，在人类中作为促炎细胞因子发挥作用。然而，IL-26在包括硬骨鱼在内的低等脊椎动物炎症调节中的作用尚未明确。在本研究中，分离并鉴定了草鱼IL-26（gcIL-26）编码序列。还分析了其染色体同线性，结果表明gcIL-26基因两侧是IL-22和IFN-γ基因，转录方向与人类、两栖动物和斑马鱼相同。鉴于斑马鱼和草鱼的IL-26与人类IL-26的氨基酸同源性相对较低，鱼类IL-26的功能作用有待阐明。因此，利用毕赤酵母表达系统制备了重组gcIL-26（rgcIL-26），发现其部分糖基化。以草鱼头肾白细胞为细胞模型，rgcIL-26表现出刺激包括IL-8、IL-1β和IL-6在内的一些促炎细胞因子mRNA表达的生物活性，同时抑制抗炎细胞因子IL-10的mRNA表达。此外，rgcIL-26还上调了草鱼单核细胞/巨噬细胞中inos的表达和NO的产生，增强了其在鱼类中的促炎特性。这些结果共同证明了IL-26在调节鱼类炎症反应中的功能作用。
