Yan Kaiheng, Zhang Youyi, Li Yuanbo, Tang Mengke, Xu Yifan, Yan Xiaojun, Hu Jiabao, Wang Yajun
College of Marine Sciences, Ningbo University, Ningbo, China.
Institute of Marine Science and Technology, Shandong University, Qingdao, China.
J Fish Dis. 2025 Jan;48(1):e14032. doi: 10.1111/jfd.14032. Epub 2024 Oct 23.
Chemokines play a crucial role in immune responses by facilitating the migration of cells expressing corresponding chemokine receptors along concentration gradients. Photobacterium damselae subsp. Damselae (PDD) and Nocardia seriolae (NS) are known to induce substantial mortality in silver pomfret populations, yet there exists a dearth of research regarding the immune response of CCLs in PDD- or NS-infected silver pomfret. In our investigation, we identified 10 PaCCLs, which include one fish-specific CCL (PaCCL44). Phylogenetic analysis revealed considerable diversity in CCL types and copy numbers among various teleost fishes. Notably, silver pomfret lacks specific CCL genes, with most PaCCLs exhibiting heightened expression levels in immune-related organs such as the spleen and kidney, and some being expressed in mucosal immune-related organs like the skin and gills. Transcriptome analysis conducted on silver pomfret infected with NS and PDD elucidated that the expression changes of PaCCLs primarily manifested in the spleen during the initial stages of NS infection, shifting to the kidney in later stages. Conversely, the expression changes of PaCCLs following PDD infection predominantly occurred in the kidney. In vitro studies using silver pomfret spleen cell lines demonstrated an early peak in PaCCLs expression during infection, followed by gradual decline with NS treatment and rapid diminishment with PDD treatment. These findings suggest that PaCCLs primarily support the innate immunity of silver pomfret, potentially exhibiting chemotactic effects in the early infection stages, such as the synergistic action of PaCCL4 and PaCCL25, and later serving as direct antibacterial agents. NS invasion is characterised by a chronic infection affecting multiple organs, whereas PDD primarily inflicts severe damage to the kidney. PaCCL19a and PaCCL19b are specific to PDD, and their expression levels may decrease in the later stages of infection due to PDD immune escape. These data offer initial insights into understanding the mechanism underlying the innate immune response of the CCL gene family in silver pomfret and provide theoretical underpinnings for fish culture practices.
趋化因子通过促进表达相应趋化因子受体的细胞沿浓度梯度迁移，在免疫反应中发挥关键作用。创伤弧菌海豚亚种（PDD）和鰤诺卡氏菌（NS）已知会导致银鲳种群大量死亡，但关于感染PDD或NS的银鲳中CCL的免疫反应研究却很匮乏。在我们的研究中，我们鉴定出10种银鲳趋化因子（PaCCLs），其中包括一种鱼类特异性CCL（PaCCL44）。系统发育分析显示，不同硬骨鱼类的CCL类型和拷贝数存在相当大的差异。值得注意的是，银鲳缺乏特定的CCL基因，大多数PaCCLs在脾脏和肾脏等免疫相关器官中表达水平升高，有些则在皮肤和鳃等黏膜免疫相关器官中表达。对感染NS和PDD的银鲳进行的转录组分析表明，PaCCLs的表达变化在NS感染初期主要表现在脾脏，后期转移到肾脏。相反，PDD感染后PaCCLs的表达变化主要发生在肾脏。使用银鲳脾脏细胞系的体外研究表明，感染期间PaCCLs表达出现早期峰值，随后随着NS处理逐渐下降，随着PDD处理迅速降低。这些发现表明，PaCCLs主要支持银鲳的先天免疫，可能在感染早期表现出趋化作用，如PaCCL4和PaCCL25的协同作用，后期则作为直接抗菌剂。NS入侵的特点是慢性感染影响多个器官，而PDD主要对肾脏造成严重损害。PaCCL19a和PaCCL19b是PDD特有的，它们的表达水平可能在感染后期因PDD免疫逃逸而降低。这些数据为理解银鲳CCL基因家族先天免疫反应的潜在机制提供了初步见解，并为鱼类养殖实践提供了理论基础。
