Molecular characterization and expression analysis of IL-1β and two types of IL-1 receptor in barbel steed (Hemibarbus labeo)

Abstract Interleukin-1β (IL-1β) is a pivotal proinflammatory cytokine that plays important roles in regulating immune responses and in inducing a series of inflammatory reactions in response to infection. Recently, increasing attention has focused on the regulatory mechanisms of IL-1β activity in teleosts. In this regard, IL-1 receptor type 1 plays a crucial role in immune responses, whereas IL-1 receptor type 2 is a decoy receptor that functions as an IL-1β signaling inhibitor. However, the interactions of these three proteins with respect to fish immunity have rarely been studied. In the present study, cDNAs of the il1b, il1r1, and il1r2 genes of the barbel steed (Hemibarbus labeo) were cloned and sequenced. Amino acid sequence analysis revealed that the IL-1β protein and its two receptors identified in barbel steed are conserved in most teleosts, whereas phylogenetic tree analysis indicated that these three proteins are closely related to those of cyprinids. In response to lipopolysaccharide treatment, expression of the genes encoding IL-1β and its two receptors was significantly upregulated in the immune-related tissues of barbel steed. Furthermore, expression of the il1r1 and il1r2 genes was induced in monocytes/macrophages in response to stimulation with recombinant IL-1β.