Abstract

Interleukine-1β (IL-1β) is the first identified pro-inflammatory cytokine, which is cleaved by caspase-1 following the inflammasomes activation, playing critical roles in innate immunity . However, few studies have been performed to characterize the IL-1β in lower vertebrates. Herein, we distinguished the Scophthalmus maximus IL-1β ( Sm IL-1β) from three IL-1β like sequences and found that Sm IL-1β was cleaved by S. maximus caspase at a non-conserved Asp 86 , then targeted to the plasma membrane . Moreover, during the immersion infection of Edwardsiella piscicida , we found that E. piscicida were mainly colonized in gills at early time points and invaded to systemic sites after 5 days post infection, which was consistent with the dynamic up-regulated transcription of Sm IL-1β. Furthermore, knockdown of Sm IL-1β promotes the bacterial colonization in gills at early time points and result into systemic colonization, while overexpression of Sm IL-1β hampers the bacterial colonization in both spleen and kidney . Taken together, these data provide new insights into the molecular mechanisms of Sm IL-1β and reveal its role in limiting bacterial infection in vivo , which will support the idea for better understanding the evolutionary of IL-1β functions in teleost.