The immune response after transplantation during pearl production is a major factor that cause nucleus rejection and death of the host pearl oysters. To find out the crucial metabolites involved in the immune response after transplantation, we performed metabolomic analysis of the serum before and after transplantation from pearl oyster Pinctada fucata martensii. The analysis detected a total of 201 metabolites, which included many amino acids. Among the 201 metabolites, 35 were revealed as significantly diff ;erential metabolites (SDMs), such as acetylcholine (ACh) and d-glutamine. Pathway analysis indicated that the identified SDMs were involved in six pathways, such as sphingolipid metabolism and d-glutamine and d-glutamate metabolism. Transcriptomic analysis showed 19 and 18 nAChRs were induced by 2–3000-fold through the pre-conditioning treatment or transplantation surgery, respectively. Dual-Luciferase analysis demonstrated that overexpression of nAChRs downregulated the luciferase activity of the pNF-κB-Luc reporter, and stimulation of nAChRs could inhibit the LPS-induced up-regulation of NF-κb, IKK and IL-17, suggesting that the upregulated ACh after transplantation may function through nAChRs by inhibiting NF-κb signal pathway. These findings could help elucidate the corresponding metabolites after transplantation, thereby providing useful information in regulating the immune response to improve the survival rate of pearl oyster after transplantation.

珍珠生产过程中移植后的免疫反应是导致细胞核排斥和宿主珍珠牡蛎死亡的主要因素。为了找出参与移植后免疫反应的关键代谢物，我们对珍珠牡蛎Pinctada fucata martensii的移植前后血清进行了代谢组学分析。分析检测到总共201种代谢物，其中包括许多氨基酸。在201种代谢产物中，有35种显着地表现出不同的代谢产物（SDM），例如乙酰胆碱（ACh）和d-谷氨酰胺。途径分析表明，鉴定出的SDMs参与了6种途径，如鞘脂代谢，d-谷氨酰胺和d-谷氨酸代谢。转录组分析显示，通过预处理或移植手术分别诱导了19例和18例nAChR的2到3000倍。双重萤光素酶分析表明，nAChRs的过表达下调了pNF-κB-Luc报告基因的萤光素酶活性，刺激nAChRs可以抑制LPS诱导的NF-κb，IKK和IL-17的上调，表明该表达上调移植后的ACh可能通过抑制NF-κb信号通路而通过nAChR发挥功能。这些发现可以帮助阐明移植后相应的代谢产物，从而为调节免疫反应以提高珍珠牡蛎的存活率提供有用的信息。