补体系统在先天免疫中有重要作用，但多种感染炎症疾病与C5aR1（补体C5a受体1）介导的C5a/C5aR1通路过度活化有关，可是鱼类上缺乏相关研究。本项目前期研究发现：重要海水鱼类半滑舌鳎C5aR1和鱼类特有miR-722参与免疫应答，miR-722转录后调控C5aR1并影响吞噬细胞功能。据此提出假说：C5aR1介导的C5a/C5aR1过度活化与鱼类细菌感染炎症密切相关，miR-722通过C5aR1调控细菌炎症。拟在前期基础上，从组织病理、病菌扩散、免疫细胞功能、C5a、C5aR1、炎症细胞因子表达等评估C5a/C5aR1与炎症相关性；通过对C5aR1过表达和基因编辑敲除、上调和下调miR-722表达、高通量测序等明确C5aR1和miR-722在细菌炎症个体及细胞水平上的功能，发现关键效应免疫基因、信号通路及调控分子，解析分子作用机制和调控机理。创新鱼类天然免疫新理论，探索病害防治新思路。

The complements play a key role especially in innate immune system and is a well-known powerful effector mechanism of the immune system that normally contributes to protection from infection. However, excessive activation of the complement signaling C5a/C5aR1 (the receptor 1 of C5a) contributes a variety of pathogenesis of inflammatory diseases and autoimmune diseases in mammals, while inflammation is attenuated via deficient of C5a/C5aR1, especially C5aR1，which belongs to one of the research focus. Unfortunately, the role of C5a/C5aR1 axis in the bacterial pathogen-associated inflammation and disorders as well as the regulation mechanism remains largely unknown in marine fish so far. We identified the C5aR1 gene of half smooth tongue sole Cynoglossus semilaevis and determined it is as the target gene regulated on the post transcription by the miR-722, which is the fish specific miRNA only found in zebrafish and common carp recently. In this project，base on the these important findings mainly supported by the previous NSFC funding, firstly, we will determine that the bacterial pathogen-associated inflammation and disorders is induced by the excessive activation of C5a/C5aR1 signaling, find the evidences by the means of pathological sections, distribution of pathogens in immune tissues, morbidity, expression of C5a, C5aR1, some inflammatory cytokines and anti-inflammatory cytokines, the immune cell migration and the functions such as the phagocytic activity and respiratory burst. Furthermore, treat bacteria challenge fish or cultured immune cells using the overexpress such as the recombinant proteins and PcDNA3.1-C5aR1 vector and siRNAs or Crisp-Cas9 editing to knock down (out) C5aR1, as well as the overexpress and silence miR-722 to regulate C5aR1 , all of the above items plus the transcriptomes were detected, the key immune signal pathways and noncoding RNAs associate C5a/C5aR1 in the serious infectious fish, Finally, the role and the regulated mechanism on complement C5a/C5aR1-mediated diseases in half smooth tongue sole will be elucidate. Our data will contribute to the new theory of innate immune and provide the novel clue for fish bacterial pathogen diseases prevention.