The exosomal miRNAs involve in the inflammatory balance of Cynoglossus semilaevis by Vibrio harveyi infection

Cynoglossus semilaevis is infected by the main pathogenic Vibrio harveyi to induce inflammation response, resulting in epidermal ulceration. The exosomes are extracellular vesicles that play a crucial role on intercellular communication and transportation. In C. semilaevis, serum-derived exosomes regulate the production of inflammatory related cytokines, but the regulation mechanism remains unclear. In this study, the serum-derived exosomes from C. semilaevis were investigated the molecular mechanism on the inflammation response following V. harveyi infection. The results showed that V. harveyi infection induced the production of skin ulceration and inflammatory response in C. semilaevis. In vivo and in vitro, the serum-derived exosomes could internalize into the hemocytes and head kidney monocytes of C. semilaevis. The expression of six miRNAs could be detected in the serum-derived exosomes. In exosomes, the expressions level of miR-128-3p and miR-730 were decreased, whereas the expression level of miR-133-3p was increased following V. harveyi infection. The expression levels of pro-inflammatory cytokines were up-regulated at the early stage of V. harveyi infection, whereas the anti-inflammatory cytokines were increased the expression at the late stage of infection. Further study found that miR-128-3p, miR-730, and miR-133-3p could interact with the 3'UTR of their target genes. These results indicated that exosomal miRNAs are involved in anti-bacterial infection and played an important role in the inflammatory balance of C. semilaevis.