cells were transfected in 96 well plates by using 100 nM antimiRs and 0.6 µg of DNA per well

Interleukin 6 (IL-6) is a major pro-inflammatory cytokine and dysregulation of IL-6 is relevant to many inflammatory diseases. Endotoxin induced tolerance of IL-6 is an important mechanism to avoid the excessive immune reaction. But to date, the molecular mechanisms of endotoxin tolerance of IL-6 remain unclear. Here we reported that IL-6 secretion and microRNA-181b (miR-181b) expression were inversely correlated following LPS stimulation. We also demonstrated that miR-181b targeting the 3'-UTR of IL-6 transcripts and up-regulation of miR-181b was associated with NF-kB. We further demonstrated that up-regulation of miR-181b in response to LPS was required for inducing IL-6 tolerance in macrophage. Our results suggested that the post-transcriptional control mediated by miR-181b could be involved in fine tuning the critical level of IL-6 expression in endotoxin tolerance.