Sun Huaqing, Li Chao, Lei Yang, Wang Yujie, Li Bingxi, Ye Jianmin
Institute of Modern Aquaculture Science and Engineering, School of Life Sciences, South China Normal University, Guangdong, 510631, PR China.
Institute of Modern Aquaculture Science and Engineering, School of Life Sciences, South China Normal University, Guangdong, 510631, PR China; Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Institute of Guangdong Ocean University, Shenzhen, Guangdong, 518120, PR China.
Fish Shellfish Immunol. 2025 Oct;165:110426. doi: 10.1016/j.fsi.2025.110426. Epub 2025 May 28.
Interferon regulatory factor 8 (IRF8) participates in the defense against pathogens. In this study, we cloned and characterized OnIRF8 from Nile tilapia (Oreochromis niloticus) and investigating its immune response functions both in vivo and in vitro. The encoded open reading frame comprises of 420 amino acids, with a predicted molecular weight of 47.645 kDa. It exhibits a high degree of sequence homology (ranging from 50.57 % to 98.81 %) with IRF8 orthologs from other vertebrates. Ubiquitous OnIRF8 expression was detected across tissues, with the highest expression observed in the spleen. Both in vivo and in vitro analyses revealed that the transcription levels of OnIRF8 were significantly up-regulated in response to treatments with Streptococcus agalactiae, Aeromonas hydrophila, Lipopolysaccharide (LPS) and polyinosinic acid:polycytidylic acid (poly (I:C)) in the head kidney and spleen. Furthermore, overexpression of OnIRF8 in Nile tilapia significantly enhanced immune-related gene expression in head kidney monocytes/macrophages. Overexpression of OnIRF8 also reduced bacterial load in head kidney and spleen post-S. agalactiae infection, with up-regulation of inflammatory factor production. OnIFN-γ recombinant protein and poly (I:C) could both markedly amplified OnIRF8 expression, implying its potential dual role in modulating both OnIFN-γ and TLR signaling pathways. These findings indicate that OnIRF8 may serve a protective function against bacterial infections and act as an immunomodulatory factor in Nile tilapia.
干扰素调节因子8（IRF8）参与抵御病原体。在本研究中，我们从尼罗罗非鱼（Oreochromis niloticus）中克隆并鉴定了OnIRF8，并研究了其在体内和体外的免疫反应功能。编码的开放阅读框由420个氨基酸组成，预测分子量为47.645 kDa。它与其他脊椎动物的IRF8直系同源物具有高度的序列同源性（范围从50.57%到98.81%）。在各个组织中均检测到OnIRF8的普遍表达，其中在脾脏中的表达最高。体内和体外分析均显示，在无乳链球菌、嗜水气单胞菌、脂多糖（LPS）和聚肌苷酸：聚胞苷酸（poly（I:C））处理后，头肾和脾脏中OnIRF8的转录水平显著上调。此外，尼罗罗非鱼中OnIRF8的过表达显著增强了头肾单核细胞/巨噬细胞中免疫相关基因的表达。OnIRF8的过表达还降低了无乳链球菌感染后头肾和脾脏中的细菌载量，并上调了炎症因子的产生。OnIFN-γ重组蛋白和poly（I:C）均可显著增强OnIRF8的表达，这意味着它在调节OnIFN-γ和TLR信号通路中可能具有潜在的双重作用。这些发现表明，OnIRF8可能在尼罗罗非鱼中发挥抗细菌感染的保护作用，并作为一种免疫调节因子。
