Signaling pathways underlying extracellular trap formation induced by Vibrio alginolyticus in Strongylocentrotus intermedius

Extracellular traps (ETs), comprising a DNA-protein network, are widespread and function as an innate immune defense in many species. Notably, Strongylocentrotus intermedius solely depend on innate immunity for disease resistance. This study investigated the formation and preliminary mechanism of ETs in the coelomocytes of the S. intermedius under the stimulation of bacterium Vibrio alginolyticus. These results revealed that as the concentration of V. alginolyticus increased, the formation of ETs became more significant. Flow cytometry analysis showed that the formation process of ETs was accompanied by changes in mitochondrial indicators, suggesting that mitochondria may be involved in the formation process of V. alginolyticus-induced ETs. Transcriptome analysis indicated that the ETs production by coelomocytes of the S. intermedius was related to glycolysis and ATP synthesis. A total of 2631 differentially expressed genes (DEGs) were screened in this transcriptome. We then screened 34 immune-related DEGs from 16 signaling pathways to construct the PPI network, and defined hub proteins corresponding to genes such as ATP6, ND2, G3PDH, MAPK7 and other related genes. These genes are related to mitochondrial function, glycolytic pathways, and immune pathways. Additionally, the formation of ETs led to alterations in multiple immune regulators, such as TNF, NF-κB, MAPK, PI3K-AKT, and mTOR, implying its role in cellular immunomodulation. Quantitative real-time PCR experiment revealed that the expression changes of some DEGs identified and validated in ET-formation coelomocytes matched transcriptome analysis results. This study provided insights into S. intermedius aquaculture, elucidated marine organism immune mechanisms, and advanced invertebrate innate immunity understanding.