IL-6 Signaling Protects Zebrafish Larvae during Infection in a Bath Immersion Model.

The host immune responses to a frequent cause of nosocomial infections, are not well understood. We have established a bath immersion model of this infection in zebrafish () larvae. Macrophages play a primary role in the host immune response and are involved in clearance of infection in the larvae. infection results in upregulation of There is marked inflammation characterized by heightened NF-κB signaling and elevation of several proinflammatory cytokines. There is rapid upregulation of and transcripts, whereas an increase in levels is relatively more delayed. The IL-6 signaling pathway is further amplified by elevation of IL-6 signal transducer () levels, which negatively correlates with miRNA dre-miR-142a-5p. Enhanced IL-6 signaling is protective to the host in this model as inhibition of the signaling pathway resulted in increased mortality upon infection. Our study describes the host immune responses to infection, establishes the importance of IL-6 signaling, and identifies a potential role of miR-142-5p- interaction in this infection model.