Zhou Xu, Li Jun-Jie, Li Shuang, Liu Hui-Hui, Chi Chang-Feng
National and Provincial Joint Engineering Research Centre for Marine Germplasm Resources Exploration and Utilization, School of Marine Science and Technology, Zhejiang Ocean University, 1st Haidanan Road, Changzhi Island, Lincheng, Zhoushan 316022, China.
National and Provincial Joint Engineering Research Centre for Marine Germplasm Resources Exploration and Utilization, School of Marine Science and Technology, Zhejiang Ocean University, 1st Haidanan Road, Changzhi Island, Lincheng, Zhoushan 316022, China; Changdao Enhancement and Experiment Station, Chinese Academy of Fishery Sciences, Yantai, Shandong 265800, China.
Int J Biol Macromol. 2025 Aug;319(Pt 4):145704. doi: 10.1016/j.ijbiomac.2025.145704. Epub 2025 Jul 1.
In mammals, 5-hydroxytryptamine receptors (5-HTRs) are expressed on various immune cells, and regulate the host immune response. However, the immunomodulatory function of 5-HTR in fish still remains poorly understood. In this study, Lc_5-HTR and Lc_5-HTR genes were cloned from large yellow croaker (Larimichthys crocea), showing highly conserved structural characteristics with other vertebrates orthologs. Lc_5-HTR and Lc_5-HTR mRNAs exhibited high expression not only in the brain, but also in the immune-related tissues (gill and head kidney). Following Cryptocaryon irritans infection, the expressions of Lc_5-HTR mRNA were strikingly induced in the brain and immune-related tissues (gill, intestine, liver, head kidney and spleen), whereas Lc_5-HTR mRNAs showed notably up-regulation in the liver and head kidney (P < 0.05 or 0.01). Afterwards, 5-HTR antagonist (BRL15572) markedly inhibited the expression of TNF-α, IL-1β, CXCL8, and IL-17A/F3 mRNA in LPS or C. irritans protein-activated head kidney macrophages (HKMs) (P < 0.05). Conversely, 5-HTR antagonist (SB204741) notably enhanced TNF-α and IL-1β mRNA expression in LPS or C. irritans protein-activated HKMs (P < 0.05 or 0.01). Moreover, 5-HTR antagonist significantly inhibited the phagocytosis of C. irritans protein-activated HKMs, while 5-HTR antagonist distinctly promoted this process (P < 0.05). Finally, 5-HTR antagonist notably hindered the phosphorylation levels of JNK and IκB-α in C. irritans protein-activated HKMs (P < 0.05), whereas 5-HTR antagonist exerted no significant effects on p38, JNK and IκB-α phosphorylation levels in C. irritans protein-activated HKMs. The findings collectively demonstrated the differential and critical roles of Lc_5-HTR and Lc_5-HTR in regulating the inflammatory response and host defense mechanisms, and provides a new perspective for neuroimmune regulation of teleost.
在哺乳动物中，5-羟色胺受体（5-HTRs）在多种免疫细胞上表达，并调节宿主免疫反应。然而，5-HTR在鱼类中的免疫调节功能仍知之甚少。在本研究中，从大黄鱼（Larimichthys crocea）中克隆了Lc_5-HTR和Lc_5-HTR基因，它们与其他脊椎动物的直系同源基因具有高度保守的结构特征。Lc_5-HTR和Lc_5-HTR mRNA不仅在脑中高表达，在免疫相关组织（鳃和头肾）中也高表达。感染刺激隐核虫后，Lc_5-HTR mRNA在脑和免疫相关组织（鳃、肠、肝、头肾和脾）中显著诱导表达，而Lc_5-HTR mRNA在肝和头肾中显著上调（P < 0.05或0.01）。随后，5-HTR拮抗剂（BRL15572）显著抑制LPS或刺激隐核虫蛋白激活的头肾巨噬细胞（HKMs）中TNF-α、IL-1β、CXCL8和IL-17A/F3 mRNA的表达（P < 0.05）。相反，5-HTR拮抗剂（SB204741）显著增强LPS或刺激隐核虫蛋白激活的HKMs中TNF-α和IL-1β mRNA的表达（P < 0.05或0.01）。此外，5-HTR拮抗剂显著抑制刺激隐核虫蛋白激活的HKMs的吞噬作用，而5-HTR拮抗剂则明显促进这一过程（P < 0.05）。最后，5-HTR拮抗剂显著阻碍刺激隐核虫蛋白激活的HKMs中JNK和IκB-α的磷酸化水平（P < 0.05），而5-HTR拮抗剂对刺激隐核虫蛋白激活的HKMs中p38、JNK和IκB-α的磷酸化水平无显著影响。这些发现共同证明了Lc_5-HTR和Lc_5-HTR在调节炎症反应和宿主防御机制中的差异和关键作用，并为硬骨鱼的神经免疫调节提供了新的视角。
