IL-10 inhibits miR-155 induction by Toll-like receptors

IL-10 is a potent anti-inflammatory cytokine that is crucial for down-regulating pro-inflammatory genes, which are induced by Toll-like receptor (TLR) signaling. In this study, we have examined whether modulation of microRNAs plays a role in the inhibitory effect of IL-10 on TLR4 signaling. Analyzing microRNAs known to be induced by TLR4, we found that IL-10 could inhibit the expression of miR-155 in response to lipopolysaccharide but had no effect on miR-21 or miR-146a. IL-10 inhibited miR-155 transcription from the BIC gene in a STAT3-dependent manner. This inhibitory effect of IL-10 on miR-155 led to an increase in the expression of the miR-155 target, SHIP1. This is the first example of IL-10 playing a role in microRNA function and suggests that through its inhibitory effect on miR-155, IL-10 has the ability to promote anti-inflammatory gene expression.