Beijing Fisheries Research Institute & Beijing Key Laboratory of Fishery Biotechnology, Beijing, 100068, People's Republic of China; National Freshwater Fisheries Engineering Technology Research Center, Beijing, 100068, People's Republic of China.
Beijing Fisheries Research Institute & Beijing Key Laboratory of Fishery Biotechnology, Beijing, 100068, People's Republic of China; National Freshwater Fisheries Engineering Technology Research Center, Beijing, 100068, People's Republic of China.
Fish Shellfish Immunol. 2020 Jul;102:296-306. doi: 10.1016/j.fsi.2020.03.023. Epub 2020 Mar 14.
Interleukin-6 (IL-6) is a pleiotropic cytokine with crucial immunoregulatory functions in both innate and adaptive immune responses. However, the IL-6 sequence and function remain unknown in sturgeon, one chondrostean fish. In the present study, we identified an interleukin-6 homolog from Siberian sturgeon (Acipenser baeri), named AbIL-6. Its open reading frame (ORF) was 657 nucleotides in length, encoding a polypeptide of 218 amino acids, which contains a signal peptide and the IL-6 family domain. Phylogenetic analysis showed that sturgeon IL-6 had close relationship with both teleost and chondrichthyes IL-6s. Abil-6 mRNA was highly expressed in spleen, brain and liver tissues of healthy sturgeon, and significantly up-regulated in the spleen, head kidney and liver by A.hydrophila (A.h) challenge. Heat-killed A.h and LPS effectively stimulated Abil-6 transcripts in primary spleen cells in vitro. In order to understand the bioactivity and influence of AbIL-6 on immune responses, recombinant AbIL-6 (rAbIL-6) was synthesized by prokaryotes and demonstrated to promote the proliferation of spleen cells and head kidney cells in vitro. Additionally, intraperitoneal injection of rAbIL-6 induced significantly higher expression of four immuno-related genes including il-1β, cxcl10, mhcIIβ and igm. rAbIL-6 improved the survival rate and reduced the tissue bacterial load after A.h infection. Taken together, these results suggest that AbIL-6 plays an important role in inflammatory responses and immune defense against bacterial infection of sturgeon.
白细胞介素-6（IL-6）是一种多功能细胞因子，在先天和适应性免疫反应中具有至关重要的免疫调节功能。然而，在软骨鱼类鲟鱼中，IL-6 的序列和功能仍然未知。在本研究中，我们从西伯利亚鲟（Acipenser baeri）中鉴定出一种白细胞介素-6 同源物，命名为 AbIL-6。其开放阅读框（ORF）长 657 个核苷酸，编码 218 个氨基酸的多肽，其中包含信号肽和 IL-6 家族结构域。系统发育分析表明，鲟鱼 IL-6 与硬骨鱼和软骨鱼的 IL-6 具有密切的关系。Abil-6 mRNA 在健康鲟鱼的脾脏、大脑和肝脏组织中高度表达，在 A.hydrophila（A.h）挑战后，在脾脏、头肾和肝脏中显著上调。热灭活的 A.h 和 LPS 可有效刺激体外原代脾脏细胞中 Abil-6 转录本的表达。为了了解 AbIL-6 的生物活性及其对免疫反应的影响，我们通过原核生物合成了重组 AbIL-6（rAbIL-6），并证明其在体外可促进脾脏细胞和头肾细胞的增殖。此外，rAbIL-6 的腹腔注射可显著诱导四个免疫相关基因 il-1β、cxcl10、mhcIIβ 和 igm 的表达上调。rAbIL-6 提高了 A.h 感染后的存活率，并降低了组织细菌负荷。综上所述，这些结果表明 AbIL-6 在鲟鱼的炎症反应和对细菌感染的免疫防御中发挥重要作用。
