Abstract：
As lower vertebrates, fish have both innate and adaptive immune systems, but the role of the adaptive immune system is limited, and the innate immune system plays an important role in the resistance to pathogen infection. C-type lectins (CLRs) are one of the major pattern recognition receptors (PRRs) of the innate immune system. CLRs can combine with pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs) to trigger NF-κB signaling pathway and exert immune efficacy. In this study, Ssclec12b and Ssclec4e of the C-type lectins, were found to be significantly up-regulated in the transcripts of Sebastes schlegelii macrophages stimulated by bacteria. The identification, expression and function of these lectins were studied. In addition, the recombinant proteins of the above two CLRs were obtained by prokaryotic expression. We found that rSsCLEC12B and rSsCLEC4E could bind to a variety of bacteria in a Ca2+-dependent manner, and promoted the agglutination of bacteria and blood cells. rSsCLEC12B and rSsCLEC4E assisted macrophages to recognize PAMPs and activate the NF-κB signaling pathway, thereby promoting the expression of inflammatory factors (TNF-α, IL-1β, IL-6, IL-8) and regulating the early immune inflammation of macrophages. These results suggested that SsCLEC12B and SsCLEC4E could serve as PRRs in S. schlegelii macrophages to recognize pathogens and participate in the host antimicrobial immune process, and provided a valuable reference for the study of CLRs involved in fish innate immunity.
摘要：
作为低等脊椎动物，鱼类有先天和适应性免疫系统，但是适应性免疫系统的作用是有限的，先天免疫系统在抵抗病原体感染中起着重要作用。C型凝集素（CLR）是先天免疫系统的主要模式识别受体（PRR）之一。CLR可以与病原体相关分子模式（PAMPs）或损伤相关分子模式（DAMPs）结合，触发NF-κB信号通路并发挥免疫功效。在这项研究中,C型凝集素的Scclec12b和Scclec4e，发现细菌刺激的Sebastesschlegelii巨噬细胞的转录本显着上调。身份证明,研究了这些凝集素的表达和功能。此外,通过原核表达获得上述两种CLR的重组蛋白。我们发现rSsCLEC12B和rSsCLEC4E可以以Ca2+依赖的方式与多种细菌结合,促进细菌和血细胞的凝集。rSsCLEC12B和rSsCLEC4E辅助巨噬细胞识别PAMPs并激活NF-κB信号通路,从而促进炎症因子(TNF-α,IL-1β,IL-6、IL-8)和调控巨噬细胞的早期免疫炎症。这些结果表明，SsCLEC12B和SsCLEC4E可以在S.schlegelii巨噬细胞中作为PRR识别病原体并参与宿主的抗菌免疫过程。为CLRs参与鱼类先天免疫的研究提供了有价值的参考。
