miR-142 regulates IL-6 signalling during host immune response to Staphylococcus epidermidis infection in zebrafish

The host immune responses to Staphylococcus epidermidis, a frequent cause of nosocomial infections, is not well understood. We have established a novel 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. S.epidermidis infection activates Tlr-2 signalling pathway by upregulation of tlr-2. There is a marked inflammation characterised by heightened NF-{kappa}B signalling and elevation of several pro-inflammatory cytokines. There is rapid upregulation of il-1b and tnf-a transcripts, while increase in il-6 levels is relatively more delayed. IL-6 signalling pathway is further amplified by elevation of IL-6 signal transducer (il-6st) levels, which is negatively-regulated by dre-miR-142-5p. Our studies describe the host immune responses to S.epidermidis infection and identifies a novel role for miR-142-5p - il-6st interaction in modulating this response.