Type I IFN inhibits innate IL-10 production in macrophages through histone deacetylase 11 by downregulating microRNA-145.

Innate immune responses must be tightly regulated to avoid overactivation and subsequent inflammatory damage to host tissue while eliminating invading pathogens. IL-10 is a crucial suppressor of inflammatory responses and its expression is under precise regulation involving complex regulatory networks and multiple feedback loops. MicroRNAs are now emerging as critical regulators in immune response. Our previous work showed that miR-143/145 cluster was markedly downregulated in macrophages upon vesicular stomatitis virus infection. However, the particular role of miR-143/145 cluster in the regulation of innate immune response remains unknown. In this study, we found that miR-143/145 cluster expression was also downregulated dramatically by TLR signals in macrophages, which was dependent on the subsequent type I IFN (IFN-I) production and downstream IFN-I receptor-JAK1-STAT1 signal cascade. Further studies demonstrated that miR-145, but not miR-143, promoted IL-10 expression in TLR4-triggered macrophages through directly targeting the epigenetic Il10 gene silencer histone deacetylase 11. Therefore, we demonstrate that miR-145, downregulated by IFN-I, targets histone deacetylase 11 to promote innate IL-10 expression in macrophages. Our findings suggest a new IFN-I-mediated negative feedback loop in the fine-tuning of innate IL-10 production that creates precise coordination of innate immune responses.