Interleukin-6 receptor (IL-6R) is involved in the innate immune response of olive flounder (Paralichthys olivaceus) to resist pathogens

The immunity of bony fish depends on the conserved components and functional complexity of immune cytokines. Herein, we used the pleiotropic cytokine IL-6 receptor as a target gene to study the defense response of PoIL-6R resist pathogens in different immune tissues of olive flounder, we found that PoIL-6R is widely expressed in these tissues studied and shows a significant immune response after stimulation with bacteria in vivo. In addition, we found a broad-spectrum immune response of PoIL-6R to bacterial and pathogen-associated molecular patterns through in vitro stimulation of olive flounder embryonic cell lines (FEC), and further revealed the function of PoIL-6R in positively regulating the natural immunity of olive flounder through activation of the NF-κB signaling pathway by overexpression of PoIL-6R in FEC. Collectively, these results demonstrate for the involvement of interleukin-6 receptors in the innate immune response of olive flounder to resist pathogens, and provides new perspectives and theoretical foundations for assessing the evolutionary mechanisms of adaptive immunity in vertebrates.